%%
@article{fds344877,
Author = {Boone, JM and Becker, AE and Hernandez, AM and Dobbins, JT and Schwoebel, P},
Title = {Multi-x-ray source array for stationary tomosynthesis or
multi-cone angle cone beam CT},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {10948},
Year = {2019},
Month = {January},
ISBN = {9781510625433},
url = {http://dx.doi.org/10.1117/12.2512959},
Abstract = {Field-emission x-ray source arrays have been studied for
both tomosynthesis and CT applications, however these arrays
tend to have limited output. We propose the use of
multi-source x-ray arrays using thermionic cathodes,
contained within a single vacuum housing. A prototype
3-source x-ray array has been fabricated and tested, and the
utility of multi-x-ray-source arrays has been demonstrated
using physical simulations in both tomosynthesis and in cone
beam CT. The prototype x-ray tube made use of a cylindrical
molybdenum anode, machined to have 3 specific focal tracks.
Grid-controlled cathode assemblies were fabricated and
aligned to each focal tract, and the individual x-ray focal
spots were evaluated with a star pattern at 35 kV and 40 mA.
The 3-source assembly was used to physically simulate
tomosynthesis imaging geometry, and tomosynthesis images of
a lemon were obtained. Physical simulations using a cone
beam breast CT scanner were also performed, by vertically
moving the single x-ray source into 5 different locations -
simulating 5 different source positions. A new geometry for
cone beam CT imaging is proposed, where each source of a
multi-x-ray source array is individually collimated to
eliminate rays involving large cone angles. This geometry
also allows three sources to be simultaneously pulsed onto a
single flat panel detector, achieving better duty cycle and
view sampling in cone beam CT. A reconstruction algorithm
was written to accommodate the different source positions,
and phantoms designed to demonstrate cone beam artifacts
were imaged. The tomosynthesis images illustrate appropriate
depth resolution in the test object. Analysis of the CT data
demonstrate marked improvement compared to one source. We
conclude that multi-source x-ray arrays using thermionic
cathodes will have important applications in medical
imaging, especially breast tomosynthesis and cone beam
computed tomography.},
Doi = {10.1117/12.2512959},
Key = {fds344877}
}
@article{fds348487,
Author = {Dobbins, JT and Frush, DP and Kigongo, CJN and MacFall, JR and Reiman,
RE and Trahey, GE and Bradway, DP},
Title = {Medical imaging safety in global health radiology},
Pages = {85-105},
Booktitle = {Radiology in Global Health: Strategies, Implementation, and
Applications},
Year = {2018},
Month = {December},
ISBN = {9783319984841},
url = {http://dx.doi.org/10.1007/978-3-319-98485-8_9},
Doi = {10.1007/978-3-319-98485-8_9},
Key = {fds348487}
}
@article{fds327404,
Author = {Pawlicki, T and Ayers, RG and Brock, KK and Clements, JB and Curran, BH and Dobbins, JT and Samei, E and Adams, E and Martin, MC and Schober,
L},
Title = {Proposed changes to the American Association of Physicists
in Medicine governance.},
Journal = {Journal of Applied Clinical Medical Physics},
Volume = {18},
Number = {4},
Pages = {4-6},
Year = {2017},
Month = {July},
url = {http://dx.doi.org/10.1002/acm2.12124},
Doi = {10.1002/acm2.12124},
Key = {fds327404}
}
@article{fds323140,
Author = {Dobbins, JT and McAdams, HP and Sabol, JM and Chakraborty, DP and Kazerooni, EA and Reddy, GP and Vikgren, J and Båth,
M},
Title = {Multi-Institutional Evaluation of Digital Tomosynthesis,
Dual-Energy Radiography, and Conventional Chest Radiography
for the Detection and Management of Pulmonary
Nodules.},
Journal = {Radiology},
Volume = {282},
Number = {1},
Pages = {236-250},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1148/radiol.2016150497},
Abstract = {Purpose To conduct a multi-institutional, multireader study
to compare the performance of digital tomosynthesis,
dual-energy (DE) imaging, and conventional chest radiography
for pulmonary nodule detection and management. Materials and
Methods In this binational, institutional review
board-approved, HIPAA-compliant prospective study, 158
subjects (43 subjects with normal findings) were enrolled at
four institutions. Informed consent was obtained prior to
enrollment. Subjects underwent chest computed tomography
(CT) and imaging with conventional chest radiography
(posteroanterior and lateral), DE imaging, and tomosynthesis
with a flat-panel imaging device. Three experienced thoracic
radiologists identified true locations of nodules (n = 516,
3-20-mm diameters) with CT and recommended case management
by using Fleischner Society guidelines. Five other
radiologists marked nodules and indicated case management by
using images from conventional chest radiography,
conventional chest radiography plus DE imaging,
tomosynthesis, and tomosynthesis plus DE imaging.
Sensitivity, specificity, and overall accuracy were measured
by using the free-response receiver operating characteristic
method and the receiver operating characteristic method for
nodule detection and case management, respectively. Results
were further analyzed according to nodule diameter
categories (3-4 mm, >4 mm to 6 mm, >6 mm to 8 mm, and >8 mm
to 20 mm). Results Maximum lesion localization fraction was
higher for tomosynthesis than for conventional chest
radiography in all nodule size categories (3.55-fold for all
nodules, P < .001; 95% confidence interval [CI]: 2.96,
4.15). Case-level sensitivity was higher with tomosynthesis
than with conventional chest radiography for all nodules
(1.49-fold, P < .001; 95% CI: 1.25, 1.73). Case management
decisions showed better overall accuracy with tomosynthesis
than with conventional chest radiography, as given by the
area under the receiver operating characteristic curve
(1.23-fold, P < .001; 95% CI: 1.15, 1.32). There were no
differences in any specificity measures. DE imaging did not
significantly affect nodule detection when paired with
either conventional chest radiography or tomosynthesis.
Conclusion Tomosynthesis outperformed conventional chest
radiography for lung nodule detection and determination of
case management; DE imaging did not show significant
differences over conventional chest radiography or
tomosynthesis alone. These findings indicate performance
likely achievable with a range of reader expertise. © RSNA,
2016 Online supplemental material is available for this
article.},
Doi = {10.1148/radiol.2016150497},
Key = {fds323140}
}
@article{fds337356,
Author = {Chen, Y and Zhou, W and Dobbins, JT},
Title = {Fourier-domain methods for optimization of tomosynthesis
(NEQ)},
Pages = {135-145},
Booktitle = {Tomosynthesis Imaging},
Year = {2016},
Month = {April},
ISBN = {9781138199651},
Key = {fds337356}
}
@article{fds305761,
Author = {Erickson, DW and Wells, JR and Sturgeon, GM and Samei, E and Dobbins,
JT and Segars, WP and Lo, JY},
Title = {Population of 224 realistic human subject-based
computational breast phantoms.},
Journal = {Med Phys},
Volume = {43},
Number = {1},
Pages = {23},
Year = {2016},
Month = {January},
ISSN = {0094-2405},
url = {http://dx.doi.org/10.1118/1.4937597},
Abstract = {PURPOSE: To create a database of highly realistic and
anatomically variable 3D virtual breast phantoms based on
dedicated breast computed tomography (bCT) data. METHODS: A
tissue classification and segmentation algorithm was used to
create realistic and detailed 3D computational breast
phantoms based on 230 + dedicated bCT datasets from normal
human subjects. The breast volume was identified using a
coarse three-class fuzzy C-means segmentation algorithm
which accounted for and removed motion blur at the breast
periphery. Noise in the bCT data was reduced through
application of a postreconstruction 3D bilateral filter. A
3D adipose nonuniformity (bias field) correction was then
applied followed by glandular segmentation using a 3D
bias-corrected fuzzy C-means algorithm. Multiple tissue
classes were defined including skin, adipose, and several
fractional glandular densities. Following segmentation, a
skin mask was produced which preserved the interdigitated
skin, adipose, and glandular boundaries of the skin
interior. Finally, surface modeling was used to produce
digital phantoms with methods complementary to the XCAT
suite of digital human phantoms. RESULTS: After rejecting
some datasets due to artifacts, 224 virtual breast phantoms
were created which emulate the complex breast parenchyma of
actual human subjects. The volume breast density (with skin)
ranged from 5.5% to 66.3% with a mean value of 25.3% ±
13.2%. Breast volumes ranged from 25.0 to 2099.6 ml with a
mean value of 716.3 ± 386.5 ml. Three breast phantoms were
selected for imaging with digital compression (using finite
element modeling) and simple ray-tracing, and the results
show promise in their potential to produce realistic
simulated mammograms. CONCLUSIONS: This work provides a new
population of 224 breast phantoms based on in vivo bCT data
for imaging research. Compared to previous studies based on
only a few prototype cases, this dataset provides a rich
source of new cases spanning a wide range of breast types,
volumes, densities, and parenchymal patterns.},
Doi = {10.1118/1.4937597},
Key = {fds305761}
}
@article{fds268504,
Author = {Dobbins, JT and Frush, DP and Kigongo, CJN and MacFall, JR and Reiman,
RE and Trahey, GE},
Title = {Medical imaging safety in the developing
world},
Volume = {9781461406044},
Pages = {41-60},
Booktitle = {Radiology in Global Health: Strategies, Implementation, and
Applications},
Publisher = {Springer New York},
Year = {2014},
Month = {October},
ISBN = {146140603X},
url = {http://dx.doi.org/10.1007/978-1-4614-0604-4_7},
Abstract = {Attention to matters of safety is important in any imaging
facility. In the context of the developing world, limited
resources may complicate the attempt to set up and operate
an imaging facility with the highest standards of safety,
but it is nonetheless important to see that all applicable
safety measures are carried out. Imaging safety involves
several general principles, including the need to minimize
radiation exposure consistent with answering the clinical
question at hand. Safety considerations relevant to
patients, staff, and the general public must be addressed.
Safety considerations specific to individual modalities
include appropriate limitations on exposure in X-ray and CT
imaging, attention to hazards from the magnetic field in
magnetic resonance imaging, proper preparation and control
of radionuclides in nuclear medicine, and avoidance of
excessive prenatal imaging procedures with ultrasound. An
important general safety consideration for all imaging
modalities is assuring proper clinical utilization; proper
utilization includes factors such as not performing imaging
procedures without medical referral and supervision,
attention to image quality to ensure that procedures do not
need to be repeated unnecessarily, and carefully considering
the clinical appropriateness of any requested imaging
procedure. Training and credentialing of staff is also of
utmost importance and includes staff who design, prepare,
and evaluate a new imaging facility as well as medical staff
who acquire, order, or review images. Ensuring imaging
safety requires the input of a team of experts, including
trained and qualified medical physicists, health physicists,
radiation safety officers, clinical safety personnel,
installation and service personnel, radiologic
technologists, and radiologists. With appropriate attention
to safety, diagnostic imaging can provide a very useful
component of healthcare services in resource-limited
regions.},
Doi = {10.1007/978-1-4614-0604-4_7},
Key = {fds268504}
}
@article{fds268505,
Author = {Kiarashi, N and Lo, JY and Lin, Y and Ikejimba, LC and Ghate, SV and Nolte,
LW and Dobbins, JT and Segars, WP and Samei, E},
Title = {Development and application of a suite of 4-D virtual breast
phantoms for optimization and evaluation of breast imaging
systems.},
Journal = {Ieee Trans Med Imaging},
Volume = {33},
Number = {7},
Pages = {1401-1409},
Year = {2014},
Month = {July},
ISSN = {0278-0062},
url = {http://dx.doi.org/10.1109/TMI.2014.2312733},
Abstract = {Mammography is currently the most widely utilized tool for
detection and diagnosis of breast cancer. However, in women
with dense breast tissue, tissue overlap may obscure
lesions. Digital breast tomosynthesis can reduce tissue
overlap. Furthermore, imaging with contrast enhancement can
provide additional functional information about lesions,
such as morphology and kinetics, which in turn may improve
lesion identification and characterization. The performance
of these imaging techniques is strongly dependent on the
structural composition of the breast, which varies
significantly among patients. Therefore, imaging system and
imaging technique optimization should take patient
variability into consideration. Furthermore, optimization of
imaging techniques that employ contrast agents should
include the temporally varying breast composition with
respect to the contrast agent uptake kinetics. To these
ends, we have developed a suite of 4-D virtual breast
phantoms, which are incorporated with the kinetics of
contrast agent propagation in different tissues and can
realistically model normal breast parenchyma as well as
benign and malignant lesions. This development presents a
new approach in performing simulation studies using truly
anthropomorphic models. To demonstrate the utility of the
proposed 4-D phantoms, we present a simplified example study
to compare the performance of 14 imaging paradigms
qualitatively and quantitatively.},
Doi = {10.1109/TMI.2014.2312733},
Key = {fds268505}
}
@article{fds268506,
Author = {Dobbins, JT and Wells, JR and Segars, WP},
Title = {Dose reduction in CT with correlated-polarity noise
reduction: Context-dependent spatial resolution and noise
properties demonstrating two-fold dose reduction with
minimal artifacts},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {9033},
Publisher = {SPIE},
Year = {2014},
Month = {January},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2043685},
Abstract = {Correlated-polarity noise reduction (CPNR) is a novel noise
reduction technique that uses a statistical approach to
reducing noise while maintaining excellent spatial
resolution and a traditional noise appearance. It was
demonstrated in application to CT imaging for the first time
at SPIE 2013 and showed qualitatively excellent image
quality at half of normal CT dose. In this current work, we
measure quantitatively the spatial resolution and noise
properties of CPNR in CT imaging. To measure the spatial
resolution, we developed a metrology approach that is
suitable for nonlinear algorithms such as CPNR. We introduce
the formalism of Signal Modification Factor, SMF(u,v), which
is the ratio in frequency space of the CPNR-processed image
divided by the noise-free image, averaged over an ensemble
of ROIs in a given anatomical context. SMF is a nonlinear
analog to the MTF. We used XCAT computer-generated
anthropomorphic phantom images followed by projection space
processing with CPNR. The SMF revealed virtually no effect
from CPNR on spatial resolution of the images (<7%
degradation at all frequencies). Corresponding
contextdependent NPS measurements generated with CPNR at
half-dose were about equal to the NPS of full-dose images
without CPNR. This result demonstrates for the first time
the quantitative determination of a two-fold reduction in
dose with CPNR with less than 7% reduction in spatial
resolution. We conclude that CPNR shows strong promise as a
method for reduction of noise (and hence, dose) in CT. CPNR
may also be used in combination with iterative
reconstruction techniques for yet further dose reduction,
pending further investigation. © 2014 SPIE.},
Doi = {10.1117/12.2043685},
Key = {fds268506}
}
@article{fds268507,
Author = {Segars, WP and Veress, AI and Wells, JR and Sturgeon, GM and Kiarashi,
N and Lo, JY and Samei, E and Dobbins, JT},
Title = {Population of 100 realistic, patient-based computerized
breast phantoms for multi-modality imaging
research},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {9033},
Publisher = {SPIE},
Year = {2014},
Month = {January},
ISBN = {9780819498267},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2043868},
Abstract = {Breast imaging is an important area of research with many
new Techniques being investigated To further reduce The
morbidity and mortality of breast cancer Through early
detection. Computerized phantoms can provide an essential
Tool To quantitatively compare new imaging systems and
Techniques. Current phantoms, however, lack sufficient
realism in depicting The complex 3D anatomy of The breast.
In This work, we created one-hundred realistic and detailed
3D computational breast phantoms based on high-resolution CT
datasets from normal patients. We also developed a
finiteelement application To simulate different compression
states of The breast, making The phantoms applicable To
multimodality imaging research. The breast phantoms and
Tools developed in This work were packaged into
user-friendly software applications To distribute for breast
imaging research. © 2014 SPIE.},
Doi = {10.1117/12.2043868},
Key = {fds268507}
}
@article{fds268508,
Author = {Wells, JR and Dobbins, JT},
Title = {Frequency response and distortion properties of nonlinear
image processing algorithms and the importance of imaging
context.},
Journal = {Med Phys},
Volume = {40},
Number = {9},
Pages = {091906},
Year = {2013},
Month = {September},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/24007157},
Abstract = {PURPOSE: The most common metrics for resolution analysis in
medical imaging are valid only for (approximately) linear
systems. While analogues to these metrics have been used in
attempts to describe resolution performance in nonlinear
systems, the analysis is incomplete since distortion effects
are often ignored. The authors have developed a methodology
to analyze the amplitude modulation and waveform distortion
properties of nonlinear systems with specific application to
medical image processing algorithms. METHODS: Using
sinusoidal basis functions, two metrics were derived which
distinguish amplitude modulation from nonlinear waveform
distortion: principle frequency response and distortion
power spectrum, respectively. Additionally, two figures of
merit were developed to describe the relative impact of
nonlinear distortion as a result of image processing:
distortion index (DI) and ΣDI. Three nonlinear denoising
algorithms, the median, bilateral, and wavelet denoising
filters, were selected as example functions to demonstrate
the utility of the metrics derived in this study. RESULTS:
Each filter showed very different resolution and waveform
distortion properties. In particular, the amplitude and
extent of nonlinear distortion depended strongly on image
context and the type of nonlinear mechanism employed.
Nonlinear waveform distortion constituted up to 30% of the
median filter output signal power in high contrast-to-noise
ratio (CNR) scenarios. Conversely, nonlinear distortion
never exceeded 1% of the bilateral filter output signal
power. The wavelet denoising response contained between 1%
and 9% distortion which varied weakly as a function of CNR.
CONCLUSIONS: The analytical metrics described in the paper
demonstrate the importance of considering both resolution-
and distortion-related effects in characterizing the
performance of nonlinear imaging systems with specific
application to image processing algorithms. Findings with
three common nonlinear algorithms demonstrate a range of CNR
values over which it is important to consider the impact of
the nonlinear nature of each algorithm. Background context
is also shown to influence the degree to which the nonlinear
nature of the algorithm influences resolution and
distortion. While no single metric can yet anticipate
observer performance in nonlinear systems, the approach
described can demonstrate the range of imaging contexts over
which such nonlinear effects are important to
consider.},
Doi = {10.1118/1.4817477},
Key = {fds268508}
}
@article{fds268514,
Author = {Hsu, CML and Palmeri, ML and Segars, WP and Veress, AI and Dobbins,
JT},
Title = {Generation of a suite of 3D computer-generated breast
phantoms from a limited set of human subject
data.},
Journal = {Med Phys},
Volume = {40},
Number = {4},
Pages = {043703},
Year = {2013},
Month = {April},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23556929},
Abstract = {PURPOSE: The authors previously reported on a
three-dimensional computer-generated breast phantom, based
on empirical human image data, including a realistic
finite-element based compression model that was capable of
simulating multimodality imaging data. The computerized
breast phantoms are a hybrid of two phantom generation
techniques, combining empirical breast CT (bCT) data with
flexible computer graphics techniques. However, to date,
these phantoms have been based on single human subjects. In
this paper, the authors report on a new method to generate
multiple phantoms, simulating additional subjects from the
limited set of original dedicated breast CT data. The
authors developed an image morphing technique to construct
new phantoms by gradually transitioning between two human
subject datasets, with the potential to generate hundreds of
additional pseudoindependent phantoms from the limited bCT
cases. The authors conducted a preliminary subjective
assessment with a limited number of observers (n = 4) to
illustrate how realistic the simulated images generated with
the pseudoindependent phantoms appeared. METHODS: Several
mesh-based geometric transformations were developed to
generate distorted breast datasets from the original human
subject data. Segmented bCT data from two different human
subjects were used as the "base" and "target" for morphing.
Several combinations of transformations were applied to
morph between the "base' and "target" datasets such as
changing the breast shape, rotating the glandular data, and
changing the distribution of the glandular tissue. Following
the morphing, regions of skin and fat were assigned to the
morphed dataset in order to appropriately assign mechanical
properties during the compression simulation. The resulting
morphed breast was compressed using a finite element
algorithm and simulated mammograms were generated using
techniques described previously. Sixty-two simulated
mammograms, generated from morphing three human subject
datasets, were used in a preliminary observer evaluation
where four board certified breast radiologists with varying
amounts of experience ranked the level of realism (from 1 =
"fake" to 10 = "real") of the simulated images. RESULTS: The
morphing technique was able to successfully generate new and
unique morphed datasets from the original human subject
data. The radiologists evaluated the realism of simulated
mammograms generated from the morphed and unmorphed human
subject datasets and scored the realism with an average
ranking of 5.87 ± 1.99, confirming that overall the phantom
image datasets appeared more "real" than "fake." Moreover,
there was not a significant difference (p > 0.1) between the
realism of the unmorphed datasets (6.0 ± 1.95) compared to
the morphed datasets (5.86 ± 1.99). Three of the four
observers had overall average rankings of 6.89 ± 0.89, 6.9
± 1.24, 6.76 ± 1.22, whereas the fourth observer ranked
them noticeably lower at 2.94 ± 0.7. CONCLUSIONS: This work
presents a technique that can be used to generate a suite of
realistic computerized breast phantoms from a limited number
of human subjects. This suite of flexible breast phantoms
can be used for multimodality imaging research to provide a
known truth while concurrently producing realistic simulated
imaging data.},
Doi = {10.1118/1.4794924},
Key = {fds268514}
}
@article{fds268515,
Author = {Godfrey, DJ and McAdams, HP and Dobbins, JT},
Title = {The effect of averaging adjacent planes for artifact
reduction in matrix inversion tomosynthesis.},
Journal = {Med Phys},
Volume = {40},
Number = {2},
Pages = {021907},
Year = {2013},
Month = {February},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23387755},
Abstract = {PURPOSE: Matrix inversion tomosynthesis (MITS) uses linear
systems theory and knowledge of the imaging geometry to
remove tomographic blur that is present in conventional
backprojection tomosynthesis reconstructions, leaving
in-plane detail rendered clearly. The use of partial-pixel
interpolation during the backprojection process introduces
imprecision in the MITS modeling of tomographic blur, and
creates low-contrast artifacts in some MITS planes. This
paper examines the use of MITS slabs, created by averaging
several adjacent MITS planes, as a method for suppressing
partial-pixel artifacts. METHODS: Human chest tomosynthesis
projection data, acquired as part of an IRB-approved pilot
study, were used to generate MITS planes, three-plane MITS
slabs (MITSa3), five-plane MITS slabs (MITSa5), and
seven-plane MITS slabs (MITSa7). These were qualitatively
examined for partial-pixel artifacts and the visibility of
normal and abnormal anatomy. Additionally, small (5 mm)
subtle pulmonary nodules were simulated and digitally
superimposed upon human chest tomosynthesis projection
images, and their visibility was qualitatively assessed in
the different reconstruction techniques. Simulated images of
a thin wire were used to generate modulation transfer
function (MTF) and slice-sensitivity profile curves for the
different MITS and MITS slab techniques, and these were
examined for indications of partial-pixel artifacts and
frequency response uniformity. Finally, mean-subtracted,
exposure-normalized noise power spectra (ENNPS) estimates
were computed and compared for MITS and MITS slab
reconstructions, generated from 10 sets of tomosynthesis
projection data of an acrylic slab. The simulated in-plane
MTF response of each technique was also combined with the
square root of the ENNPS estimate to yield stochastic
signal-to-noise ratio (SNR) information about the different
reconstruction techniques. RESULTS: For scan angles of 20°
and 5 mm plane separation, seven MITS planes must be
averaged to sufficiently remove partial-pixel artifacts.
MITSa7 does appear to subtly reduce the contrast of
high-frequency "edge" information, but the removal of
partial-pixel artifacts makes the appearance of
low-contrast, fine-detail anatomy even more conspicuous in
MITSa7 slices. MITSa7 also appears to render simulated
subtle 5 mm pulmonary nodules with greater visibility than
MITS alone, in both the open lung and regions overlying the
mediastinum. Finally, the MITSa7 technique reduces
stochastic image variance, though the in-plane stochastic
SNR (for very thin objects which do not span multiple MITS
planes) is only improved at spatial frequencies between 0.05
and 0.20 cycles∕mm. CONCLUSIONS: The MITSa7 method is an
improvement over traditional single-plane MITS for thoracic
imaging and the pulmonary nodule detection task, and thus
the authors plan to use the MITSa7 approach for all future
MITS research at the authors' institution.},
Doi = {10.1118/1.4773891},
Key = {fds268515}
}
@article{fds327405,
Author = {Wells, J and Segars, P and Dobbins, J},
Title = {TH‐A‐103‐10: Improved Segmentation of Low‐Contrast
Fibroglandular Structures in High‐Noise Breast CT Volumes
for XCAT Modeling},
Journal = {Medical Physics},
Volume = {40},
Number = {6},
Pages = {527},
Publisher = {WILEY},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1118/1.4815727},
Abstract = {Purpose: This work improves the accuracy and realism of
automated breast computed tomography (bCT) tissue
segmentation by refining the detection of low‐contrast
fibroglandular structures to produce high‐resolution
realistic computer‐generated (XCAT) breast phantoms from
empirical human subject data. Methods: Previous work by Hsu
et al. [Med. Phys. 38, 5756‐5770 (2011)] produced
high‐resolution realistic computer‐generated breast
phantoms from empirical human subject data but challenges
were encountered with the accurate segmentation of fine,
low‐contrast glandular structures. The current work
addresses those challenges. A 3‐D anisotropic diffusion
algorithm was used to denoise fourteen bCT datasets. After
breast masking, two adipose non‐uniformity correction
techniques were applied. The first has been described by
Altunbas, et al. [Med. Phys. 34, 3109‐3118 (2007)]. The
second approach employed an original technique using
higher‐order polynomials to correct for residual adipose
non‐uniformity. Histogram thresholding then produced
initial gland and skin segmentations. This was followed by a
novel glandular linking and extension protocol based on
skeletonization of the skin and glandular segmentations and
a pixel gray‐level‐weighted distance transform. Skin
mask definition and glandular density differentiation
completed the segmentation. Results: Volumetric denoising
reduced the standard deviation of the adipose background by
an average of 60.4%. The Altunbas method corrected for
radially symmetric, quadratic non‐uniformities in breasts
with circular coronal cross sections, but performed poorly
on high‐density breasts and breasts with asymmetric
adipose non‐uniformity. Follow‐up correction using the
novel method improved adipose uniformity by an average of
24.6%. The new fibroglandular linking and extension protocol
improved the detection of low‐contrast fibroglandular
structures, including Cooper's ligaments. The total number
of fibroglandular tissue islands was also reduced.
Conclusion: The semi‐automated bCT segmentation protocol
improved low‐contrast glandular fiber detection in
high‐noise reconstructions. Linking of disparate
fibroglandular tissue islands and capture of Cooper's
ligaments will contribute to the overall accuracy and
realism of empirically‐derived XCAT breast phantoms. This
work was supported by NIH Grant 5R01‐CA‐134658. © 2013,
American Association of Physicists in Medicine. All rights
reserved.},
Doi = {10.1118/1.4815727},
Key = {fds327405}
}
@article{fds268510,
Author = {Wells, JR and III, JTD},
Title = {Preliminary investigation of the frequency response and
distortion properties of nonlinear image processing
algorithms},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {8668},
Publisher = {SPIE},
Year = {2013},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2008549},
Abstract = {Assessment of the resolution properties of nonlinear imaging
systems is a useful but challenging task. While the
modulation transfer function (MTF) fully describes contrast
resolution as a function of spatial frequency for linear
systems, an equivalent metric does not exist for systems
with significant nonlinearity. Therefore, this preliminary
investigation attempts to classify and quantify the amount
of scaling and distortion imposed on a given image signal as
the result of a nonlinear process (nonlinear image
processing algorithm). As a proof-of-concept, a median
filter is assessed in terms of its principle frequency
response (PFR) and distortion response (DR) functions. These
metrics are derived in frequency space using a sinusoidal
basis function, and it is shown that, for a narrow-band
sinusoidal input signal, the scaling and distortion
properties of the nonlinear filter are described exactly by
PFR and DR, respectively. The use of matched sinusoidal
basis and input functions accurately reveals the frequency
response to long linear structures of different scale.
However, when more complex (multi-band) input signals are
considered, PFR and DR fail to adequately characterize the
frequency response due to nonlinear interaction effects
between different frequency components during processing.
Overall, the results reveal the context-dependent nature of
nonlinear image processing algorithm performance, and they
emphasize the importance of the basis function choice in
algorithm assessment. In the future, more complex forms of
nonlinear systems analysis may be necessary to fully
characterize the frequency response properties of nonlinear
algorithms in a context-dependent manner. © 2013
SPIE.},
Doi = {10.1117/12.2008549},
Key = {fds268510}
}
@article{fds268511,
Author = {Kiarashi, N and Sturgeon, GM and Nolte, LW and Lo, JY and III, JTD and Segars, WP and Samei, E},
Title = {Development of matched virtual and physical breast phantoms
based on patient data},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {8668},
Publisher = {SPIE},
Year = {2013},
ISBN = {9780819494429},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2008406},
Abstract = {Physical phantoms are essential for the development,
optimization, and clinical evaluation of x-ray systems.
These phantoms are used for various tests such as quality
assurance testing, system characterization, reconstruction
evaluation, and dosimetry. They should ideally be capable of
serving as ground truth for purposes such as virtual
clinical trials. Currently, there is no anthropomorphic 3D
physical phantom commercially available. We present our
development of a new suite of physical breast phantoms based
on real patient data. The phantoms were generated from the
NURBS-based extended cardiac-torso (XCAT) breast phantoms,
which were segmented from patient dedicated breast computed
tomography data. High-resolution multi-material 3D printing
technology was used to fabricate the physical models.
Glandular tissue and skin were presented by the most
radiographically dense photopolymer available to the
printer, mimicking a 75% glandular tissue. Adipose tissue
was presented by the least radiographically dense
photopolymer, mimicking a 35% glandular tissue. The
glandular equivalency was measured by comparing x-ray images
of samples of the photopolymers available to the printer
with those of breast tissue-equivalent materials. The
mammographic projections and tomosynthesis reconstructed
images of fabricated models showed great improvement over
available phantoms, presenting a more realistic breast
background. © 2013 SPIE.},
Doi = {10.1117/12.2008406},
Key = {fds268511}
}
@article{fds268512,
Author = {III, JTD and Wells, JR and Segars, WP},
Title = {Dose reduction in CT with correlated-polarity noise
reduction: Comparable image quality at half the dose with
projection space processing},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {8668},
Publisher = {SPIE},
Year = {2013},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2008563},
Abstract = {Correlated-polarity noise reduction (CPNR) is a novel noise
reduction technique that uses a statistical approach to
reduce noise while maintaining excellent resolution and a
"normal" noise appearance. It is applicable to any type of
medical imaging, and we introduced it at SPIE 2011 for
reducing dose three-fold in radiography while maintaining
excellent image quality. In this current work, we
demonstrate for the first time its use in reducing the noise
in CT images as a means of reducing the dose in CT.
Simulated chest CT images were generated using the XCAT
phantom and Poisson noise was added to simulate a
conventional full-dose CT image and a half-dose CT image.
CPNR was applied to the half-dose images in projection image
space, and then the images were reconstructed using filtered
backprojection with a Feldkamp methodology. The resulting
CPNR processed half-dose images showed essentially
equivalent relative standard deviation in the central heart
region to the full-dose images, and about 0.7 times that in
half-dose images that were not processed with CPNR. This
noise reduction was consistent with a two-fold reduction in
dose that is possible with CPNR in CT. The CPNR images
demonstrated virtually identical sharpness of vessels and no
apparent artifacts. We conclude that CPNR shows strong
promise as a new noise reduction method for dose reduction
in CT. CPNR could also be used in combination with
model-based iterative reconstruction techniques for yet
further dose reduction. © 2013 SPIE.},
Doi = {10.1117/12.2008563},
Key = {fds268512}
}
@article{fds268542,
Author = {Lin, Y and Luo, H and Dobbins, JT and Page McAdams and H and Wang, X and Sehnert, WJ and Barski, L and Foos, DH and Samei,
E},
Title = {An image-based technique to assess the perceptual quality of
clinical chest radiographs.},
Journal = {Medical Physics},
Volume = {39},
Number = {11},
Pages = {7019-7031},
Year = {2012},
Month = {November},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23127093},
Abstract = {PURPOSE: Current clinical image quality assessment
techniques mainly analyze image quality for the imaging
system in terms of factors such as the capture system
modulation transfer function, noise power spectrum,
detective quantum efficiency, and the exposure technique.
While these elements form the basic underlying components of
image quality, when assessing a clinical image, radiologists
seldom refer to these factors, but rather examine several
specific regions of the displayed patient images, further
impacted by a particular image processing method applied, to
see whether the image is suitable for diagnosis. In this
paper, the authors developed a novel strategy to simulate
radiologists' perceptual evaluation process on actual
clinical chest images. METHODS: Ten regional based
perceptual attributes of chest radiographs were determined
through an observer study. Those included lung grey level,
lung detail, lung noise, rib-lung contrast, rib sharpness,
mediastinum detail, mediastinum noise, mediastinum
alignment, subdiaphragm-lung contrast, and subdiaphragm
area. Each attribute was characterized in terms of a
physical quantity measured from the image algorithmically
using an automated process. A pilot observer study was
performed on 333 digital chest radiographs, which included
179 PA images with 10:1 ratio grids (set 1) and 154 AP
images without grids (set 2), to ascertain the correlation
between image perceptual attributes and physical
quantitative measurements. To determine the acceptable range
of each perceptual attribute, a preliminary quality
consistency range was defined based on the preferred 80% of
images in set 1. Mean value difference (μ(1) - μ(2)) and
variance ratio (σ(1) (2)/σ(2) (2)) were investigated to
further quantify the differences between the selected two
image sets. RESULTS: The pilot observer study demonstrated
that our regional based physical quantity metrics of chest
radiographs correlated very well with their corresponding
perceptual attributes. The distribution comparisons, mean
value difference estimations, and variance ratio estimations
of each physical quantity between sets of images from two
different techniques matched our expectation that the image
quality of set 1 should be better than that of set 2.
CONCLUSIONS: The measured physical quantities provide a
robust reflection of perceptual image quality in clinical
images. The methodology can be readily applied for automated
evaluation of perceptual image quality in clinical chest
radiographs.},
Doi = {10.1118/1.4760886},
Key = {fds268542}
}
@article{fds268541,
Author = {Wells, JR and Dobbins, JT},
Title = {Estimation of the two-dimensional presampled modulation
transfer function of digital radiography devices using
one-dimensional test objects.},
Journal = {Medical Physics},
Volume = {39},
Number = {10},
Pages = {6148-6160},
Year = {2012},
Month = {October},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23039654},
Abstract = {PURPOSE: The modulation transfer function (MTF) of medical
imaging devices is commonly reported in the form of
orthogonal one-dimensional (1D) measurements made near the
vertical and horizontal axes with a slit or edge test
device. A more complete description is found by measuring
the two-dimensional (2D) MTF. Some 2D test devices have been
proposed, but there are some issues associated with their
use: (1) they are not generally available; (2) they may
require many images; (3) the results may have diminished
accuracy; and (4) their implementation may be particularly
cumbersome. This current work proposes the application of
commonly available 1D test devices for practical and
accurate estimation of the 2D presampled MTF of digital
imaging systems. METHODS: Theory was developed and applied
to ensure adequate fine sampling of the system line spread
function for 1D test devices at orientations other than
approximately vertical and horizontal. Methods were also
derived and tested for slit nonuniformity correction at
arbitrary angle. Techniques were validated with experimental
measurements at ten angles using an edge test object and
three angles using a slit test device on an
indirect-detection flat-panel system [GE Revolution XQ∕i
(GE Healthcare, Waukesha, WI)]. The 2D MTF was estimated
through a simple surface fit with interpolation based on
Delaunay triangulation of the 1D edge-based MTF
measurements. Validation by synthesis was also performed
with simulated images from a hypothetical direct-detection
flat-panel device. RESULTS: The 2D MTF derived from physical
measurements yielded an average relative precision error of
0.26% for frequencies below the cutoff (2.5 mm(-1)) and
approximate circular symmetry at frequencies below 4 mm(-1).
While slit analysis generally agreed with the results of
edge analysis, the two showed subtle differences at
frequencies above 4 mm(-1). Slit measurement near 45°
revealed radial asymmetry in the MTF resulting from the
square pixel aperture (0.2 mm × 0.2 mm), a
characteristic which was not necessarily appreciated with
the orthogonal 1D MTF measurements. In simulation
experiments, both slit- and edge-based measurements resolved
the radial asymmetries in the 2D MTF. The average absolute
relative accuracy error in the 2D MTF between the DC and
cutoff (2.5 mm(-1)) frequencies was 0.13% with average
relative precision error of 0.11%. Other simulation results
were similar to those derived from physical data.
CONCLUSIONS: Overall, the general availability, acceptance,
accuracy, and ease of implementation of 1D test devices for
MTF assessment make this a valuable technique for 2D MTF
estimation.},
Doi = {10.1118/1.4752442},
Key = {fds268541}
}
@article{fds268538,
Author = {Kiarashi, N and Lin, Y and Segars, WP and Ghate, SV and Ikejimba, L and Chen, B and Lo, JY and Dobbins, JT and Nolte, LW and Samei,
E},
Title = {Development of a dynamic 4D anthropomorphic breast phantom
for contrast-based breast imaging},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {8313},
Publisher = {SPIE},
Year = {2012},
Month = {May},
ISBN = {9780819489623},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.913332},
Abstract = {Mammography is currently the most widely accepted tool for
detection and diagnosis of breast cancer. However, the
sensitivity of mammography is reduced in women with dense
breast tissue due to tissue overlap, which may obscure
lesions. Digital breast tomosynthesis with contrast
enhancement reduces tissue overlap and provides additional
functional information about lesions (i.e. morphology and
kinetics), which in turn may improve lesion
characterization. The performance of such techniques is
highly dependent on the structural composition of the
breast, which varies significantly across patients.
Therefore, optimization of breast imaging systems should be
done with respect to this patient versatility. Furthermore,
imaging techniques that employ contrast require the
inclusion of a temporally varying breast composition with
respect to the contrast agent kinetics to enable the
optimization of the system. To these ends, we have developed
a dynamic 4D anthropomorphic breast phantom, which can be
used for optimizing a breast imaging system by incorporating
material characteristics. The presented dynamic phantom is
based on two recently developed anthropomorphic breast
phantoms, which can be representative of a whole population
through their randomized anatomical feature generation and
various compression levels. The 4D dynamic phantom is
incorporated with the kinetics of contrast agent uptake in
different tissues and can realistically model benign and
malignant lesions. To demonstrate the utility of the
proposed dynamic phantom, contrast-enhanced digital
mammography and breast tomosynthesis were simulated where a
ray-tracing algorithm emulated the projections, a filtered
back projection algorithm was used for reconstruction, and
dual-energy and temporal subtractions were performed and
compared. © 2012 Copyright Society of Photo-Optical
Instrumentation Engineers (SPIE).},
Doi = {10.1117/12.913332},
Key = {fds268538}
}
@article{fds268539,
Author = {Schnell, EA and Samei, E and Dobbins, JT},
Title = {Plate-specific gain map correction for the improvement of
detective quantum efficiency in computed
radiography.},
Journal = {Medical Physics},
Volume = {39},
Number = {3},
Pages = {1495-1504},
Year = {2012},
Month = {March},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22380382},
Abstract = {PURPOSE: The purpose of this work is to improve the noise
power spectrum (NPS), and thus the detective quantum
efficiency (DQE), of computed radiography (CR) images by
correcting for spatial gain variations specific to
individual imaging plates. CR devices have not traditionally
employed gain-map corrections, unlike the case with
flat-panel detectors, because of the multiplicity of plates
used with each reader. The lack of gain-map correction has
limited the DQE(f) at higher exposures with CR. This current
work describes a feasible solution to generating
plate-specific gain maps. METHODS: Ten high-exposure open
field images were taken with an RQA5 spectrum, using a sixth
generation CR plate suspended in air without a cassette.
Image values were converted to exposure, the plates
registered using fiducial dots on the plate, the ten images
averaged, and then high-pass filtered to remove low
frequency contributions from field inhomogeneity. A gain-map
was then produced by converting all pixel values in the
average into fractions with mean of one. The resultant
gain-map of the plate was used to normalize subsequent
single images to correct for spatial gain fluctuation. To
validate performance, the normalized NPS (NNPS) for all
images was calculated both with and without the gain-map
correction. Variations in the quality of correction due to
exposure levels, beam voltage/spectrum, CR reader used, and
registration were investigated. RESULTS: The NNPS with
plate-specific gain-map correction showed improvement over
the noncorrected case over the range of frequencies from
0.15 to 2.5 mm(-1). At high exposure (40 mR), NNPS was
50%-90% better with gain-map correction than without. A
small further improvement in NNPS was seen from carefully
registering the gain-map with subsequent images using small
fiducial dots, because of slight misregistration during
scanning. Further improvement was seen in the NNPS from
scaling the gain map about the mean to account for different
beam spectra. CONCLUSIONS: This study demonstrates that a
simple gain-map can be used to correct for the fixed-pattern
noise in a given plate and thus improve the DQE of CR
imaging. Such a method could easily be implemented by
manufacturers because each plate has a unique bar code and
the gain-map for all plates associated with a reader could
be stored for future retrieval. These experiments indicated
that an improvement in NPS (and hence, DQE) is possible,
depending on exposure level, over a wide range of
frequencies with this technique.},
Doi = {10.1118/1.3685580},
Key = {fds268539}
}
@article{fds268540,
Author = {Wang, J and Dobbins, JT and Li, Q},
Title = {Automated lung segmentation in digital chest
tomosynthesis.},
Journal = {Medical Physics},
Volume = {39},
Number = {2},
Pages = {732-741},
Year = {2012},
Month = {February},
ISSN = {0094-2405},
url = {http://dx.doi.org/10.1118/1.3671939},
Abstract = {PURPOSE: The purpose of this study was to develop an
automated lung segmentation method for computerized
detection of lung nodules in digital chest tomosynthesis.
METHODS: The authors collected 45 digital tomosynthesis
scans and manually segmented reference lung regions in each
scan to assess the performance of the method. The authors
automated the technique by calculating the edge gradient in
an original image for enhancing lung outline and
transforming the edge gradient image to polar coordinate
space. The authors then employed a dynamic programming
technique to delineate outlines of the unobscured lungs in
the transformed edge gradient image. The lung outlines were
converted back to the original image to provide the final
segmentation result. The above lung segmentation algorithm
was first applied to the central reconstructed tomosynthesis
slice because of the absence of ribs overlapping lung
structures. The segmented lung in the central slice was then
used to guide lung segmentation in noncentral slices. The
authors evaluated the segmentation method by using (1) an
overlap rate of lung regions, (2) a mean absolute distance
(MAD) of lung borders, (3) a Hausdorff distance of lung
borders between the automatically segmented lungs and
manually segmented reference lungs, and (4) the fraction of
nodules included in the automatically segmented lungs.
RESULTS: The segmentation method achieved mean overlap rates
of 85.7%, 88.3%, and 87.0% for left lungs, right lungs, and
entire lungs, respectively; mean MAD of 4.8, 3.9, and 4.4 mm
for left lungs, right lungs, and entire lungs, respectively;
and mean Hausdorrf distance of 25.0 mm, 25.5 mm, and 30.1 mm
for left lungs, right lungs, and entire lungs, respectively.
All of the nodules inside the reference lungs were correctly
included in the segmented lungs obtained with the lung
segmentation method. CONCLUSIONS: The method achieved
relatively high accuracy for lung segmentation and will be
useful for computer-aided detection of lung nodules in
digital tomosynthesis.},
Doi = {10.1118/1.3671939},
Key = {fds268540}
}
@article{fds268545,
Author = {Samei, E and Majdi-Nasab, N and Dobbins, JT and McAdams,
HP},
Title = {Biplane correlation imaging: a feasibility study based on
phantom and human data.},
Journal = {J Digit Imaging},
Volume = {25},
Number = {1},
Pages = {137-147},
Year = {2012},
Month = {February},
ISSN = {1618-727X},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21618054},
Keywords = {Adult • Aged • Algorithms* • Artifacts •
False Positive Reactions • Feasibility Studies •
Humans • Lung Neoplasms • Middle Aged •
Pattern Recognition, Automated • Phantoms, Imaging*
• ROC Curve • Radiographic Image Enhancement
• Radiographic Image Interpretation, Computer-Assisted
• Radiography, Thoracic • Sampling Studies •
Solitary Pulmonary Nodule • methods • methods*
• radiography • radiography*},
Abstract = {The objective of this study was to implement and evaluate
the performance of a biplane correlation imaging (BCI)
technique aimed to reduce the effect of anatomic noise and
improve the detection of lung nodules in chest radiographs.
Seventy-one low-dose posterior-anterior images were acquired
from an anthropomorphic chest phantom with 0.28° angular
separations over a range of ±10° along the vertical axis
within an 11 s interval. Similar data were acquired from 19
human subjects with institutional review board approval and
informed consent. The data were incorporated into a
computer-aided detection (CAD) algorithm in which suspect
lesions were identified by examining the geometrical
correlation of the detected signals that remained relatively
constant against variable anatomic backgrounds. The data
were analyzed to determine the effect of angular separation,
and the overall sensitivity and false-positives for lung
nodule detection. The best performance was achieved for
angular separations of the projection pairs greater than
5°. Within that range, the technique provided an order of
magnitude decrease in the number of false-positive reports
when compared with CAD analysis of single-view images.
Overall, the technique yielded ~1.1 false-positive per
patient with an average sensitivity of 75%. The results
indicated that the incorporation of angular information can
offer a reduction in the number of false-positives without a
notable reduction in sensitivity. The findings suggest that
the BCI technique has the potential for clinical
implementation as a cost-effective technique to improve the
detection of subtle lung nodules with lowered rate of
false-positives.},
Language = {eng},
Doi = {10.1007/s10278-011-9392-z},
Key = {fds268545}
}
@article{fds327406,
Author = {Dobbins, J and Chakrabarti, K},
Title = {WE‐E‐217BCD‐01: Digital Breast Tomosynthesis: Basic
Principles and the QMP's Role},
Journal = {Medical Physics},
Volume = {39},
Number = {6},
Pages = {3954},
Publisher = {WILEY},
Year = {2012},
Month = {January},
url = {http://dx.doi.org/10.1118/1.4736138},
Abstract = {Digital breast tomosynthesis is a form of limited angle
tomography, in which section (slice) images are produced
from a series of discrete projection images acquired at
different angles. Tomosynthesis can be useful in breast
imaging by providing potentially better visibility of
lesions over conventional mammography, especially in
patients with dense breasts. This talk will cover the
various physics aspects of DBT, including reconstruction
algorithms, the importance of deblurring, and optimizing
image acquisition parameters. Remaining important research
questions in DBT will be presented and discussed. The
presentation will also discuss MQSA Certificate extension
process for currently approved digital breast tomosynthesis
(DBT) systems. Training requirements, manufacturer required
tests for Mammography Equipment Evaluation (MEE) as
acceptance tests, and phantom imaging for the purpose of
approval of certificate extension will be described. The
talk will emphasize the specific tests where special
attention must be given and will discuss how the techs
should be advised to perform these tests. Learning
Objectives: 1. To understand the fundamentals of
tomosynthesis reconstruction, including deblurring,
algorithm choice, and optimization 2. To understand FDA's
certificate extension process for DBT 3. To understand the
requirements for MEE 4. To understand the required AEC
tracking data Research sponsored in part by NIH, Siemens,
and GE Healthcare. © 2012, American Association of
Physicists in Medicine. All rights reserved.},
Doi = {10.1118/1.4736138},
Key = {fds327406}
}
@article{fds327407,
Author = {Wells, J and Dobbins, J},
Title = {TU‐A‐218‐01: Estimation of the 2‐D Presampled MTF of
a Digital Flat Panel Detector Using an Edge Test
Device},
Journal = {Medical Physics},
Volume = {39},
Number = {6},
Pages = {3894},
Publisher = {WILEY},
Year = {2012},
Month = {January},
url = {http://dx.doi.org/10.1118/1.4735895},
Abstract = {Purpose: In this work, we report on the novel application of
an opaque edge test device for practical estimation of the
2‐D modulation transfer function (MTF) of a digital flat
panel (DFP) detector. Methods: We estimated the 2‐ D MTF
of a prototype GE Revolution XQ/i DFP detector (GE
Healthcare, Waukesha, WI) using an opaque edge test device.
The original work by Samei et al. [Med. Phys. 25, 102–113
(1998)] served as the basis of our methodology to which we
also contributed further theoretical analysis regarding
sub‐pixel precision of 1 ‐D MTF measurements at
arbitrary angle. The edge was imaged five times at each of
ten angles relative to the sampling lattice: 1.33, 7.59,
20.22, 30.29, 37.90, 48.07, 58.85, 69.78, 78.13, and 88.02
degrees. The 1‐D MTF was computed from edge data at each
angle using Fourier analysis. The 2‐D MTF was estimated
through a simple surface fit and linear interpolation scheme
based on Delaunay triangulation of the collection of 1‐D
MTF data. Results: All angles yielded nearly identical 1‐D
MTFs with relative standard deviations of 0.39%, 1.3%, 4.2%,
and 5.6% at 1, 2, 3, and 4 cycles/mm, respectively. These
measurements exhibited no discernible patterns with respect
to acquisition angle indicating that the 2‐D MTF has
approximate circular symmetry at frequencies below 4
cycles/mm. Although this assertion agrees with the
conclusions of other authors, blur due to the finite
rectangular pixel aperture may merit further investigation
at the highest spatial frequencies where the MTF may not
behave in a circularly symmetric manner. Conclusions: We
present for the first time the practical estimation of the
2‐D MTF of a DFP detector using an edge test device. The
general availability, acceptance, and ease of implementation
of edge‐based MTF assessments make this a valuable
technique for 2‐D MTF measurement in academic, industrial,
and clinical settings. © 2012, American Association of
Physicists in Medicine. All rights reserved.},
Doi = {10.1118/1.4735895},
Key = {fds327407}
}
@article{fds327408,
Author = {Dobbins, J},
Title = {TU‐A‐217A‐02: Radiographic Tomosynthesis:
Reconstruction Algorithms},
Journal = {Medical Physics},
Volume = {39},
Number = {6},
Pages = {3893},
Publisher = {WILEY},
Year = {2012},
Month = {January},
url = {http://dx.doi.org/10.1118/1.4735892},
Abstract = {Digital tomosynthesis is a form of limited angle tomography,
in which section (slice) images are produced from a series
of discrete projection images acquired at different angles.
The simplest form of tomosynthesis reconstruction is the
shift‐and‐add technique, whereby the projection images
are shifted with respect to one another and then summed to
render a particular section of the patient. While this
technique is efficient, it also leaves blurry artifacts from
structures that are outside of the plane of interest. High
quality tomosynthesis reconstruction therefore requires some
means of reducing these blurry artifacts. Three approaches
have been widely reported for tomosynthesis reconstruction
with blur removal: (1) filtered backprojection, (2) matrix
inversion tomosynthesis, and (3) various iterative
reconstruction schemes. Fundamentals of these three
approaches will be discussed, along with the advantages and
limitations of each. Learning Objectives: 1. To understand
the basics of tomosynthesis reconstruction 2. To understand
the mathematical background and implementation strategies
for filtered backprojection, matrix inversion tomosynthesis,
and iterative reconstruction schemes 3. To understand the
relative advantages and disadvantages of the three
reconstruction algorithmsResearch sponsored in part by NIH
and GE Healthcare. © 2012, American Association of
Physicists in Medicine. All rights reserved.},
Doi = {10.1118/1.4735892},
Key = {fds327408}
}
@article{fds268547,
Author = {Hsu, CML and Palmeri, ML and Segars, WP and Veress, AI and Dobbins,
JT},
Title = {An analysis of the mechanical parameters used for finite
element compression of a high-resolution 3D breast
phantom.},
Journal = {Medical Physics},
Volume = {38},
Number = {10},
Pages = {5756-5770},
Year = {2011},
Month = {October},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21992390},
Keywords = {Algorithms • Biomechanics • Breast • Computer
Simulation • Data Compression • Female •
Finite Element Analysis • Humans • Imaging,
Three-Dimensional • Mammography • Models, Anatomic
• Phantoms, Imaging • Stress, Mechanical •
Tomography, X-Ray Computed • methods • methods*
• pathology*},
Abstract = {PURPOSE: The authors previously introduced a methodology to
generate a realistic three-dimensional (3D),
high-resolution, computer-simulated breast phantom based on
empirical data. One of the key components of such a phantom
is that it provides a means to produce a realistic
simulation of clinical breast compression. In the current
study, they have evaluated a finite element (FE) model of
compression and have demonstrated the effect of a variety of
mechanical properties on the model using a dense mesh
generated from empirical breast data. While several groups
have demonstrated an effective compression simulation with
lower density finite element meshes, the presented study
offers a mesh density that is able to model the morphology
of the inner breast structures more realistically than lower
density meshes. This approach may prove beneficial for
multimodality breast imaging research, since it provides a
high level of anatomical detail throughout the simulation
study. METHODS: In this paper, the authors describe methods
to improve the high-resolution performance of a FE
compression model. In order to create the compressible
breast phantom, dedicated breast CT data was segmented and a
mesh was generated with 4-noded tetrahedral elements. Using
an explicit FE solver to simulate breast compression,
several properties were analyzed to evaluate their effect on
the compression model including: mesh density, element type,
density, and stiffness of various tissue types, friction
between the skin and the compression plates, and breast
density. Following compression, a simulated projection was
generated to demonstrate the ability of the compressible
breast phantom to produce realistic simulated mammographic
images. RESULTS: Small alterations in the properties of the
breast model can change the final distribution of the tissue
under compression by more than 1 cm; which ultimately
results in different representations of the breast model in
the simulated images. The model properties that impact
displacement the most are mesh density, friction between the
skin and the plates, and the relative stiffness of the
different tissue types. CONCLUSIONS: The authors have
developed a 3D, FE breast model that can yield high spatial
resolution breast deformations under uniaxial compression
for imaging research purposes and demonstrated that small
changes in the mechanical properties can affect images
generated using the phantom.},
Language = {eng},
Doi = {10.1118/1.3637500},
Key = {fds268547}
}
@article{fds268546,
Author = {Samei, E and Ranger, NT and Dobbins, JT and Ravin,
CE},
Title = {Effective dose efficiency: an application-specific metric of
quality and dose for digital radiography.},
Journal = {Phys Med Biol},
Volume = {56},
Number = {16},
Pages = {5099-5118},
Year = {2011},
Month = {August},
ISSN = {1361-6560},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21775791},
Keywords = {Adult • Humans • Infant • Male •
Phantoms, Imaging • Quality Control • Radiation
Dosage* • Radiographic Image Enhancement •
Radiography, Thoracic • methods* •
standards*},
Abstract = {The detective quantum efficiency (DQE) and the effective DQE
(eDQE) are relevant metrics of image quality for digital
radiography detectors and systems, respectively. The current
study further extends the eDQE methodology to technique
optimization using a new metric of the effective dose
efficiency (eDE), reflecting both the image quality as well
as the effective dose (ED) attributes of the imaging system.
Using phantoms representing pediatric, adult and large adult
body habitus, image quality measurements were made at 80,
100, 120 and 140 kVp using the standard eDQE protocol and
exposures. ED was computed using Monte Carlo methods. The
eDE was then computed as a ratio of image quality to ED for
each of the phantom/spectral conditions. The eDQE and eDE
results showed the same trends across tube potential with 80
kVp yielding the highest values and 120 kVp yielding the
lowest. The eDE results for the pediatric phantom were
markedly lower than the results for the adult phantom at
spatial frequencies lower than 1.2-1.7 mm(-1), primarily due
to a correspondingly higher value of ED per entrance
exposure. The relative performance for the adult and large
adult phantoms was generally comparable but affected by
kVps. The eDE results for the large adult configuration were
lower than the eDE results for the adult phantom, across all
spatial frequencies (120 and 140 kVp) and at spatial
frequencies greater than 1.0 mm(-1) (80 and 100 kVp).
Demonstrated for chest radiography, the eDE shows promise as
an application-specific metric of imaging performance,
reflective of body habitus and radiographic technique, with
utility for radiography protocol assessment and
optimization.},
Language = {eng},
Doi = {10.1088/0031-9155/56/16/002},
Key = {fds268546}
}
@article{fds268535,
Author = {Lin, Y and Samei, E and Luo, H and Dobbins, JT and McAdams, HP and Wang, X and Sehnert, WJ and Barski, L and Foos, DH},
Title = {A patient image-based technique to assess the image quality
of clinical chest radiographs},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7961},
Publisher = {SPIE},
Year = {2011},
Month = {May},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.878765},
Abstract = {Current clinical image quality assessment techniques mainly
analyze image quality for the imaging system in terms of
factors such as the capture system DQE and MTF, the exposure
technique, and the particular image processing method and
processing parameters. However, when assessing a clinical
image, radiologists seldom refer to these factors, but
rather examine several specific regions of the image to see
whether the image is suitable for diagnosis. In this work,
we developed a new strategy to learn and simulate
radiologists' evaluation process on actual clinical chest
images. Based on this strategy, a preliminary study was
conducted on 254 digital chest radiographs (38 AP without
grids, 35 AP with 6:1 ratio grids and 151 PA with 10:1 ratio
grids). First, ten regional based perceptual qualities were
summarized through an observer study. Each quality was
characterized in terms of a physical quantity measured from
the image, and as a first step, the three physical
quantities in lung region were then implemented
algorithmically. A pilot observer study was performed to
verify the correlation between image perceptual qualities
and physical quantitative qualities. The results
demonstrated that our regional based metrics have promising
performance for grading perceptual properties of chest
radiographs. © 2011 SPIE.},
Doi = {10.1117/12.878765},
Key = {fds268535}
}
@article{fds268536,
Author = {Wells, JR and Segars, WP and Kigongo, CJN and Dobbins,
JT},
Title = {Refinement of motion correction strategies for lower-cost CT
for under-resourced regions of the world},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7961},
Publisher = {SPIE},
Year = {2011},
Month = {May},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.878697},
Abstract = {This paper describes a recently developed post-acquisition
motion correction strategy for application to lower-cost
computed tomography (LCCT) for under-resourced regions of
the world. Increased awareness regarding global health and
its challenges has encouraged the development of more
affordable healthcare options for underserved people
worldwide. In regions such as sub-Saharan Africa,
intermediate level medical facilities may serve millions
with inadequate or antiquated equipment due to financial
limitations. In response, the authors have proposed a LCCT
design which utilizes a standard chest x-ray examination
room with a digital flat panel detector (FPD). The patient
rotates on a motorized stage between the fixed cone-beam
source and FPD, and images are reconstructed using a
Feldkamp algorithm for cone-beam scanning. One of the most
important proofs-of-concept in determining the feasibility
of this system is the successful correction of undesirable
motion. A 3D motion correction algorithm was developed in
order to correct for potential patient motion, stage
instabilities and detector misalignments which can all lead
to motion artifacts in reconstructed images. Motion will be
monitored by the radiographic position of fiducial markers
to correct for rigid body motion in three dimensions. Based
on simulation studies, projection images corrupted by motion
were re-registered with average errors of 0.080 mm, 0.32 mm
and 0.050 mm in the horizontal, vertical and depth
dimensions, respectively. The overall absence of motion
artifacts in motion-corrected reconstructions indicates that
reasonable amounts of motion may be corrected using this
novel technique without significant loss of image quality.
© 2011 SPIE.},
Doi = {10.1117/12.878697},
Key = {fds268536}
}
@article{fds268537,
Author = {Dobbins, JT and Wells, JR},
Title = {Correlated-polarity noise reduction: Feasibility of a new
statistical approach to reduce image noise},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7961},
Publisher = {SPIE},
Year = {2011},
Month = {May},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.879076},
Abstract = {Reduction of image noise is an important goal in producing
the highest quality medical images. A very important benefit
of reducing image noise is the ability to reduce patient
exposure while maintaining adequate image quality. Various
methods have been described in the literature for reducing
image noise by means of image processing, both deterministic
and statistical. Deterministic methods tend to degrade image
resolution or lead to artifacts or non-uniform noise texture
that does not look "natural" to the observer. Statistical
methods, including Bayesian estimation, have been
successfully applied to image processing, but may require
more time-consuming steps of computing priors. The approach
described in this paper uses a new statistical method we
have developed in our laboratory to reduce image noise. This
approach, Correlated-Polarity Noise Reduction (CPNR), makes
an estimate of the polarity of noise at a given pixel, and
then subtracts a random value from a normal distribution
having a sign that matches the estimated polarity of the
noise in the pixel. For example, if the noise is estimated
to be positive in a given pixel, then a random number that
is also positive will be subtracted from that pixel. The
CPNR method reduces the noise in an image by about 20% per
iteration, with little negative impact on image resolution,
few artifacts, and final image noise characteristics that
appears "normal." Examples of the feasibility of this
approach are presented in application to radiography and CT,
but it also has potential utility in tomosynthesis and
fluoroscopy. © 2011 SPIE.},
Doi = {10.1117/12.879076},
Key = {fds268537}
}
@article{fds268520,
Author = {Dobbins, JT and Wells, JR and Segars, WP and Li, CM and Kigongo,
CJN},
Title = {Initial investigation into lower-cost CT for resource
limited regions of the world},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7622},
Number = {PART 2},
Publisher = {SPIE},
Year = {2010},
Month = {December},
ISBN = {9780819480231},
ISSN = {0277-786X},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000285047200114&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {This paper describes an initial investigation into means for
producing lower-cost CT scanners for resource limited
regions of the world. In regions such as sub-Saharan Africa,
intermediate level medical facilities serving millions have
no CT machines, and lack the imaging resources necessary to
determine whether certain patients would benefit from being
transferred to a hospital in a larger city for further
diagnostic workup or treatment. Low-cost CT scanners would
potentially be of immense help to the healthcare system in
such regions. Such scanners would not produce
state-of-the-art image quality, but rather would be intended
primarily for triaging purposes to determine the patients
who would benefit from transfer to larger hospitals. The
lower-cost scanner investigated here consists of a fixed
digital radiography system and a rotating patient stage.
This paper describes initial experiments to determine if
such a configuration is feasible. Experiments were conducted
using (1) x-ray image acquisition, a physical
anthropomorphic chest phantom, and a flat-panel detector
system, and (2) a computer-simulated XCAT chest phantom.
Both the physical phantom and simulated phantom produced
excellent image quality reconstructions when the phantom was
perfectly aligned during acquisition, but artifacts were
noted when the phantom was displaced to simulate patient
motion. An algorithm was developed to correct for motion of
the phantom and demonstrated success in correcting for 5-mm
motion during 360-degrce acquisition of images. These
experiments demonstrated feasibility for this approach, but
additional work is required to determine the exact
limitations produced by patient motion. © 2010
SPIE.},
Doi = {10.1117/12.844293},
Key = {fds268520}
}
@article{fds327409,
Author = {Schnell, E and Dobbins, J},
Title = {WE‐E‐201C‐03: Plate‐Specific Gain Map Correction for
the Improvement of DQE in Computed Radiography},
Journal = {Medical Physics},
Volume = {37},
Number = {6},
Pages = {3439-3440},
Publisher = {WILEY},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1118/1.3469440},
Abstract = {Purpose: To improve the NPS, and thus DQE, of CR images by
correcting for pixel‐to‐pixel gain variations specific
to each plate. Method and Materials: Ten high‐exposure,
open field images were taken with an RQA5 spectrum, with a
sixth generation CR plate suspended in air without a
cassette. Image values were converted to exposure, the
plates registered using fiducial dots on the plate, ten
images averaged, and then high‐pass filtered to remove low
frequency contributions from field inhomogeneity. A
gain‐map was then produced by converting all pixel values
in the average into fractions with mean of one. The
resultant gain‐map of the plate was used to normalize
subsequent single images to correct for pixel‐to‐pixel
gain fluctuation. The normalized NPS (NNPS) for all images
was calculated both with and without the gain‐map
correction. Results: The NNPS with correction showed
improvement over the non‐corrected case over the range of
frequencies from 0.15 – 2.5 mm−1. At high exposure (40
mR), NNPS was 50–90% better with gain‐map correction
than without. A small further improvement in NNPS was seen
from careful registering of the gain‐map with subsequent
images using small fiducial dots, because of slight
misregistration during scanning. Conclusion: CR devices have
not traditionally employed gain‐map corrections common
with DR detectors because of the multiplicity of plates used
with each reader. This study demonstrates that a simple
gain‐map can be used to correct for the fixed‐pattern
noise and thus improve the DQE of CR imaging. Such a method
could easily be implemented by manufacturers because each
plate has a unique bar code and the gain‐map could be
stored for retrieval after plate reading. These experiments
indicated that an improvement in NPS (and hence, DQE) is
possible, depending on exposure level, over all frequencies
with this technique. © 2010, American Association of
Physicists in Medicine. All rights reserved.},
Doi = {10.1118/1.3469440},
Key = {fds327409}
}
@article{fds172346,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, McAdams HP. Digital tomosynthesis. In
Advances in Medical Physics 2010. Wolbarst AB, Mossman KL,
Hendee WR (eds). Medical Physics Publishing, Madison,
Wisconsin, 2010 (in press)},
Year = {2010},
Key = {fds172346}
}
@article{fds268556,
Author = {Dobbins, JT and McAdams, HP},
Title = {Chest tomosynthesis: technical principles and clinical
update.},
Journal = {Eur J Radiol},
Volume = {72},
Number = {2},
Pages = {244-251},
Year = {2009},
Month = {November},
ISSN = {1872-7727},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19616909},
Keywords = {Europe • Humans • Radiographic Image Enhancement
• Radiographic Image Interpretation, Computer-Assisted
• Radiography, Thoracic • Tomography, X-Ray
Computed • methods* • trends*},
Abstract = {Digital tomosynthesis is a radiographic technique that can
produce an arbitrary number of section images of a patient
from a single pass of the X-ray tube. It utilizes a
conventional X-ray tube, a flat-panel detector, a
computer-controlled tube mover, and special reconstruction
algorithms to produce section images. While it does not have
the depth resolution of computed tomography (CT),
tomosynthesis provides some of the tomographic benefits of
CT but at lower cost and radiation dose than CT. Compared to
conventional chest radiography, chest tomosynthesis results
in improved visibility of normal structures such as vessels,
airway and spine. By reducing visual clutter from overlying
normal anatomy, it also enhances detection of small lung
nodules. This review article outlines the components of a
tomosynthesis system, discusses results regarding improved
lung nodule detection from the recent literature, and
presents examples of nodule detection from a clinical trial
in human subjects. Possible implementation strategies for
use in clinical chest imaging are discussed.},
Language = {eng},
Doi = {10.1016/j.ejrad.2009.05.054},
Key = {fds268556}
}
@article{fds268557,
Author = {Samei, E and Ranger, NT and MacKenzie, A and Honey, ID and Dobbins, JT and Ravin, CE},
Title = {Effective DQE (eDQE) and speed of digital radiographic
systems: an experimental methodology.},
Journal = {Medical Physics},
Volume = {36},
Number = {8},
Pages = {3806-3817},
Year = {2009},
Month = {August},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19746814},
Keywords = {Humans • Mammography • Phantoms, Imaging •
Radiographic Image Enhancement • Scattering, Radiation
• Time Factors • methods*},
Abstract = {Prior studies on performance evaluation of digital
radiographic systems have primarily focused on the
assessment of the detector performance alone. However, the
clinical performance of such systems is also substantially
impacted by magnification, focal spot blur, the presence of
scattered radiation, and the presence of an antiscatter
grid. The purpose of this study is to evaluate an
experimental methodology to assess the performance of a
digital radiographic system, including those attributes, and
to propose a new metric, effective detective quantum
efficiency (eDQE), a candidate for defining the efficiency
or speed of digital radiographic imaging systems. The study
employed a geometric phantom simulating the attenuation and
scatter properties of the adult human thorax and a
representative indirect flat-panel-based clinical digital
radiographic imaging system. The noise power spectrum (NPS)
was derived from images of the phantom acquired at three
exposure levels spanning the operating range of the clinical
system. The modulation transfer function (MTF) was measured
using an edge device positioned at the surface of the
phantom, facing the x-ray source. Scatter measurements were
made using a beam stop technique. The eDQE was then computed
from these measurements, along with measures of phantom
attenuation and x-ray flux. The MTF results showed notable
impact from the focal spot blur, while the NPS depicted a
large component of structured noise resulting from use of an
antiscatter grid. The eDQE was found to be an order of
magnitude lower than the conventional DQE. At 120 kVp,
eDQE(0) was in the 8%-9% range, fivefold lower than DQE(0)
at the same technique. The eDQE method yielded reproducible
estimates of the system performance in a clinically relevant
context by quantifying the inherent speed of the system,
that is, the actual signal to noise ratio that would be
measured under clinical operating conditions.},
Language = {eng},
Doi = {10.1118/1.3171690},
Key = {fds268557}
}
@article{fds268549,
Author = {Li, CM and Segars, WP and Tourassi, GD and Boone, JM and Dobbins,
JT},
Title = {Methodology for generating a 3D computerized breast phantom
from empirical data.},
Journal = {Medical Physics},
Volume = {36},
Number = {7},
Pages = {3122-3131},
Year = {2009},
Month = {July},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19673211},
Keywords = {Algorithms • Breast • Computer Simulation •
Female • Humans • Imaging, Three-Dimensional
• Male • Mammography • Models, Anatomic*
• Phantoms, Imaging* • Tomography, X-Ray Computed
• anatomy & histology* • methods*},
Abstract = {The initial process for creating a flexible
three-dimensional computer-generated breast phantom based on
empirical data is described. Dedicated breast
computed-tomography data were processed to suppress noise
and scatter artifacts in the reconstructed image set. An
automated algorithm was developed to classify the breast
into its primary components. A preliminary phantom defined
using subdivision surfaces was generated from the segmented
data. To demonstrate potential applications of the phantom,
simulated mammographic image data were acquired of the
phantom using a simplistic compression model and an analytic
projection algorithm directly on the surface model. The
simulated image was generated using a model for a
polyenergetic cone-beam projection of the compressed
phantom. The methods used to create the breast phantom
generate resulting images that have a high level of tissue
structure detail available and appear similar to actual
mammograms. Fractal dimension measurements of simulated
images of the phantom are comparatively similar to
measurements from images of real human subjects. A realistic
and geometrically defined breast phantom that can accurately
simulate imaging data may have many applications in breast
imaging research.},
Language = {eng},
Doi = {10.1118/1.3140588},
Key = {fds268549}
}
@article{fds268533,
Author = {Li, CM and Segars, WP and Lo, JY and Veress, AI and Boone, JM and Dobbins,
JT},
Title = {Computerized 3D breast phantom with enhanced High-Resolution
detail},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7258},
Publisher = {SPIE},
Year = {2009},
Month = {June},
ISBN = {9780819475091},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.813529},
Abstract = {We previously proposed a three-dimensional computerized
breast phantom that combines empirical data with the
flexibility of mathematical models1. The goal of this
project is to enhance the breast phantom to include a more
detailed anatomy than currently visible and create
additional phantoms from different breast CT data. To
improve the level of detail in our existing segmentations,
the breast CT data is reconstructed at a higher resolution
and additional image processing techniques are used to
correct for noise and scatter in the image data. A refined
segmentation algorithm is used that incorporates more detail
than previously defined. To further enhance high-resolution
detail, mathematical models, implementing branching
algorithms to extend the glandular tissue throughout the
breast and to define Cooper's ligaments, are under
investigation. We perform the simulation of mammography and
tomosynthesis using an analytical projection algorithm that
can be applied directly to the mathematical model of the
breast without voxelization 2. This method speeds up image
acquisition, reduces voxelization artifacts, and produces
higher resolution images than the previously used method.
The realistic 3D computerized breast phantom will ultimately
be incorporated into the 4DXCAT phantom 3-5 to be used for
breast imaging research.©2009 SPIE.},
Doi = {10.1117/12.813529},
Key = {fds268533}
}
@article{fds268534,
Author = {Ranger, NT and Mackenzie, A and Honey, ID and Dobbins, JT and Ravin, CE and Samei, E},
Title = {Extension of DQE to include scatter, grid, magnification,
and focal spot blur: A new experimental technique and
metric},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {7258},
Publisher = {SPIE},
Year = {2009},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.813779},
Abstract = {In digital radiography, conventional DQE evaluations are
performed under idealized conditions that do not reflect
typical clinical operating conditions. For this reason, we
have developed and evaluated an experimental methodology for
measuring the effective detective quantum efficiency (eDQE)
of digital radiographic systems and its utility in chest
imaging applications.To emulate the attenuation and scatter
properties of the human thorax across a range of sizes, the
study employed pediatric and adult geometric chest imaging
phantoms designed for use in the FDA/CDRH Nationwide
Evaluation of X-Ray Trends (NEXT) program and a third
phantom configuration designed to represent the bariatric
population. The MTF for each phantom configuration was
measured using images of an opaque edge device placed at the
nominal surface of each phantom and at a common reference
point. For each phantom, the NNPS was measured in a uniform
region within the phantom image acquired at an exposure
level determined from a prior phototimed acquisition.
Scatter measurements were made using a beam-stop technique.
These quantities were used along with measures of phantom
attenuation and estimates of x-ray flux, to compute the eDQE
at the beam-entrance surface of the phantoms, reflecting the
presence of scatter, grid, magnification, and focal spot
blur. The MTF results showed notable degradation due to
focal spot blurring enhanced by geometric magnification,
with increasing phantom size. Measured scatter fractions
were 33%, 34% and 46% for the pediatric, adult, and
bariatric phantoms, respectively. Correspondingly, the
measured narrow beam transmission fractions were 16%, 9%,
and 3%. The eDQE results for the pediatric and adult
phantoms correlate well at low spatial frequencies but show
degradation in the eDQE at increasing spatial frequencies
for the adult phantom in comparison to the pediatric
phantom. The results for the bariatric configuration showed
a marked decrease in eDQE in comparison to the adult phantom
results, across all spatial frequencies, attributable to the
combined differences in geometric magnification, and
scatter. The eDQE metric has been demonstrated to be
sensitive to body habitus suggesting its usefulness in
assessing system response across a range of chest sizes and
potentially making it a useful factor in protocol assessment
and optimization.©2009 SPIE.},
Doi = {10.1117/12.813779},
Key = {fds268534}
}
@article{fds268550,
Author = {Dobbins, JT},
Title = {Tomosynthesis imaging: at a translational
crossroads.},
Journal = {Medical Physics},
Volume = {36},
Number = {6},
Pages = {1956-1967},
Year = {2009},
Month = {June},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19610284},
Keywords = {Algorithms* • Imaging, Three-Dimensional •
Radiographic Image Enhancement • instrumentation •
methods* • trends*},
Abstract = {Tomosynthesis is a decades-old technique for section imaging
that has seen a recent upsurge in interest due to its
promise to provide three-dimensional information at lower
dose and potentially lower cost than CT in certain clinical
imaging situations. This renewed interest in tomosynthesis
began in the late 1990s as a new generation of flat-panel
detectors became available; these detectors were the one
missing piece of the picture that had kept tomosynthesis
from enjoying significant utilization earlier. In the past
decade, tomosynthesis imaging has been investigated in a
variety of clinical imaging situations, but the two most
prominent have been in breast and chest imaging.
Tomosynthesis has the potential to substantially change the
way in which breast cancer and pulmonary nodules are
detected and managed. Commercial tomosynthesis devices are
now available or on the horizon. Many of the remaining
research activities with tomosynthesis will be translational
in nature and will involve physicist and clinician alike.
This overview article provides a forward-looking assessment
of the translational questions facing tomosynthesis imaging
and anticipates some of the likely research and clinical
activities in the next five years.},
Language = {eng},
Doi = {10.1118/1.3120285},
Key = {fds268550}
}
@article{fds268559,
Author = {Godfrey, DJ and McAdams, HP and Dobbins, JTT},
Title = {Stochastic noise characteristics in matrix inversion
tomosynthesis (MITS).},
Journal = {Medical Physics},
Volume = {36},
Number = {5},
Pages = {1521-1532},
Year = {2009},
Month = {May},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19544768},
Keywords = {Algorithms* • Computer Simulation • Image
Enhancement • Image Interpretation, Computer-Assisted
• Models, Statistical • Reproducibility of Results
• Sensitivity and Specificity • Stochastic
Processes • Tomography • methods*},
Abstract = {Matrix inversion tomosynthesis (MITS) uses known imaging
geometry and linear systems theory to deterministically
separate in-plane detail from residual tomographic blur in a
set of conventional tomosynthesis ("shift-and-add") planes.
A previous investigation explored the effect of scan angle
(ANG), number of projections (N), and number of
reconstructed planes (NP) on the MITS impulse response and
modulation transfer function characteristics, and concluded
that ANG = 20 degrees, N = 71, and NP = 69 is the optimal
MITS imaging technique for chest imaging on our prototype
tomosynthesis system. This article examines the effect of
ANG, N, and NP on the MITS exposure-normalized noise power
spectra (ENNPS) and seeks to confirm that the imaging
parameters selected previously by an analysis of the MITS
impulse response also yield reasonable stochastic properties
in MITS reconstructed planes. ENNPS curves were generated
for experimentally acquired mean-subtracted projection
images, conventional tomosynthesis planes, and MITS planes
with varying combinations of the parameters ANG, N, and NP.
Image data were collected using a prototype tomosynthesis
system, with 11.4 cm acrylic placed near the image receptor
to produce lung-equivalent beam hardening and scattered
radiation. Ten identically acquired tomosynthesis data sets
(realizations) were collected for each selected technique
and used to generate ensemble mean images that were
subtracted from individual image realizations prior to noise
power spectra (NPS) estimation. NPS curves were normalized
to account for differences in entrance exposure (as measured
with an ion chamber), yielding estimates of the ENNPS for
each technique. Results suggest that mid- and high-frequency
noise in MITS planes is fairly equivalent in magnitude to
noise in conventional tomosynthesis planes, but
low-frequency noise is amplified in the most anterior and
posterior reconstruction planes. Selecting the largest
available number of projections (N = 71) does not incur any
appreciable additive electronic noise penalty compared to
using fewer projections for roughly equivalent cumulative
exposure. Stochastic noise is minimized by maximizing N and
NP but increases with increasing ANG. The noise trend
results for NP and ANG are contrary to what would be
predicted by simply considering the MITS matrix conditioning
and likely result from the interplay between noise
correlation and the polarity of the MITS filters. From this
study, the authors conclude that the previously determined
optimal MITS imaging strategy based on impulse response
considerations produces somewhat suboptimal stochastic noise
characteristics, but is probably still the best technique
for MITS imaging of the chest.},
Language = {eng},
Doi = {10.1118/1.3103399},
Key = {fds268559}
}
@article{fds327410,
Author = {Hendee, W and Giger, M and Starkschall, G and Molloy, J and Peroni, C and Seibert, J and Dobbins, J and Smilowitz, J and Hogstrom, K and Montemayor, V and Jackson, E},
Title = {TU‐C‐211A‐01: Becoming a Better Teacher},
Journal = {Medical Physics},
Volume = {36},
Number = {6},
Pages = {2719},
Publisher = {WILEY},
Year = {2009},
Month = {January},
url = {http://dx.doi.org/10.1118/1.3182318},
Abstract = {Every medical physicist is a teacher, either formally in the
classroom or informally in the clinic. Some physicists
skillfully fulfill their educational obligations, while
others struggle with their teaching responsibilities.
However, everyone can be a good teacher — what are
required are determination, dedication and diligence. This
objective was the focus of a 3‐day AAPM Educational Summit
held immediately after the 2008 AAPM annual meeting in
Houston. It will also be the goal of a second Educational
Summit scheduled to follow the 2010 annual meeting in
Philadelphia. Discussion of the outcomes of the 2008
Educational Summit, and plans for the 2010 Summit, are the
topics of this educational session scheduled for the 2009
annual meeting. This session will include solicitation of
suggestions from the audience for the 2010 Educational
Summit. © 2009, American Association of Physicists in
Medicine. All rights reserved.},
Doi = {10.1118/1.3182318},
Key = {fds327410}
}
@article{fds172323,
Author = {J.T. Dobbins},
Title = {Yin FF, Godfrey DJ, Oldham M, Dobbins JT 3rd. Use of
simulation tomosynthesis and verification tomosynthesis for
treatment target localization. US Patent. Allowed
2009.},
Year = {2009},
Key = {fds172323}
}
@article{fds172324,
Author = {J.T. Dobbins},
Title = {Samei E, Ranger NT, Bisset GS III, Maxfield C, Hollingsworth
CL, Lo JY, Dobbins JT 3rd, Wilson KL. Image quality and dose
in radiography. RSNA/AAPM Educational module, RSNA
Publications, 2009.},
Year = {2009},
Key = {fds172324}
}
@article{fds172344,
Author = {J.T. Dobbins},
Title = {Li CM, Segars WP, Lo JY, Veress AI, Boone JM, Dobbins JT
3rd. Computerized 3D breast phantom with enhanced
high-resolution detail. SPIE Medical Imaging Conference.
2009;7258:0S1-OS8.
},
Year = {2009},
Key = {fds172344}
}
@article{fds172345,
Author = {J.T. Dobbins},
Title = {Ranger NT, Mackenzie A, Honey ID, Dobbins JT 3rd, Ravin CE,
Samei E. Extension of DQE to include scatter, grid,
magnification, and focal spot blur: a new experimental
technique and metric. SPIE Medical Imaging Conference.
2009;7258:1A1-1A12.
},
Year = {2009},
Key = {fds172345}
}
@article{fds268551,
Author = {Samei, E and Ranger, NT and MacKenzie, A and Honey, ID and Dobbins, JT and Ravin, CE},
Title = {Detector or system? Extending the concept of detective
quantum efficiency to characterize the performance of
digital radiographic imaging systems.},
Journal = {Radiology},
Volume = {249},
Number = {3},
Pages = {926-937},
Year = {2008},
Month = {December},
ISSN = {1527-1315},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19011189},
Keywords = {Efficiency • Phantoms, Imaging • Radiographic
Image Enhancement • Radiography, Thoracic •
Scattering, Radiation • instrumentation* •
standards • standards*},
Abstract = {PURPOSE: To develop an experimental method for measuring the
effective detective quantum efficiency (eDQE) of digital
radiographic imaging systems and evaluate its use in select
imaging systems. MATERIALS AND METHODS: A geometric phantom
emulating the attenuation and scatter properties of the
adult human thorax was employed to assess eight imaging
systems in a total of nine configurations. The noise power
spectrum (NPS) was derived from images of the phantom
acquired at three exposure levels spanning the operating
range of the system. The modulation transfer function (MTF)
was measured by using an edge device positioned at the
anterior surface of the phantom. Scatter measurements were
made by using a beam-stop technique. All measurements,
including those of phantom attenuation and estimates of
x-ray flux, were used to compute the eDQE. RESULTS: The MTF
results showed notable degradation owing to focal spot blur.
Scatter fractions ranged between 11% and 56%, depending on
the system. The eDQE(0) results ranged from 1%-17%,
indicating a reduction of up to one order of magnitude and
different rank ordering and performance among systems,
compared with that implied in reported conventional
detective quantum efficiency results from the same systems.
CONCLUSION: The eDQE method was easy to implement, yielded
reproducible results, and provided a meaningful reflection
of system performance by quantifying image quality in a
clinically relevant context. The difference in the magnitude
of the measured eDQE and the ideal eDQE of 100% provides a
great opportunity for improving the image quality of
radiographic and mammographic systems while reducing patient
dose.},
Language = {eng},
Doi = {10.1148/radiol.2492071734},
Key = {fds268551}
}
@article{fds268544,
Author = {James, TD and McAdams, HP and Song, J-W and Li, CM and Godfrey, DJ and DeLong, DM and Paik, S-H and Martinez-Jimenez,
S},
Title = {Digital tomosynthesis of the chest for lung nodule
detection: interim sensitivity results from an ongoing
NIH-sponsored trial.},
Journal = {Medical Physics},
Volume = {35},
Number = {6},
Pages = {2554-2557},
Year = {2008},
Month = {June},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18649488},
Keywords = {Cohort Studies • Humans • Lung • National
Institutes of Health (U.S.)* • Radiographic Image
Enhancement • Radiography, Thoracic • Sensitivity
and Specificity • Tomography • United States
• methods* • pathology* •
radiography*},
Abstract = {The authors report interim clinical results from an ongoing
NIH-sponsored trial to evaluate digital chest tomosynthesis
for improving detectability of small lung nodules.
Twenty-one patients undergoing computed tomography (CT) to
follow up lung nodules were consented and enrolled to
receive an additional digital PA chest radiograph and
digital tomosynthesis exam. Tomosynthesis was performed with
a commercial CsI/a-Si flat-panel detector and a custom-built
tube mover. Seventy-one images were acquired in 11 s,
reconstructed with the matrix inversion tomosynthesis
algorithm at 5-mm plane spacing, and then averaged (seven
planes) to reduce noise and low-contrast artifacts. Total
exposure for tomosynthesis imaging was equivalent to that of
11 digital PA radiographs (comparable to a typical
screen-film lateral radiograph or two digital lateral
radiographs). CT scans (1.25-mm section thickness) were
reviewed to confirm presence and location of nodules. Three
chest radiologists independently reviewed tomosynthesis
images and PA chest radiographs to confirm visualization of
nodules identified by CT. Nodules were scored as: definitely
visible, uncertain, or not visible. 175 nodules (diameter
range 3.5-25.5 mm) were seen by CT and grouped according to
size: < 5, 5-10, and > 10 mm. When considering as true
positives only nodules that were scored definitely visible,
sensitivities for all nodules by tomosynthesis and PA
radiography were 70% (+/- 5%) and 22% (+/- 4%),
respectively, (p < 0.0001). Digital tomosynthesis showed
significantly improved sensitivity of detection of known
small lung nodules in all three size groups, when compared
to PA chest radiography.},
Language = {eng},
Doi = {10.1118/1.2937277},
Key = {fds268544}
}
@article{fds268532,
Author = {Li, CM and Segars, WP and Lo, JY and Veress, AI and Boone, JM and Dobbins,
JT},
Title = {Three-dimensional computer generated breast phantom based on
empirical data},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6913},
Publisher = {SPIE},
Year = {2008},
Month = {May},
ISBN = {9780819470973},
ISSN = {1605-7422},
url = {http://hdl.handle.net/10161/3119 Duke open
access},
Abstract = {The goal of this work is to create a detailed
three-dimensional (3D) digital breast phantom based on
empirical data and to incorporate it into the
four-dimensional (4D) NCAT phantom, a computerized model of
the human anatomy widely used in imaging research. Twenty
sets of high-resolution breast CT data were used to create
anatomically diverse models. The datasets were segmented
using techniques developed in our laboratory and the breast
structures will be defined using a combination of
non-uniform rational b-splines (NURBS) and subdivision
surfaces (SD). Imaging data from various modalities (x-ray
and nuclear medicine) were simulated to demonstrate the
utility of the new breast phantoms. As a proof of concept, a
simple compression technique was used to deform the breast
models while maintaining a constant volume to simulate
modalities (mammography and tomosynthesis) that involve
compression. Initial studies using one CT dataset indicate
that the simulated breast phantom is capable of providing a
realistic and flexible representation of breast tissue and
can be used with different acquisition methods to test
varying imaging parameters such as dose, resolution, and
patient motion. The final model will have a more accurate
depiction of the internal breast structures and will be
scaleable in terms of size and density. Also, more realistic
finite-element techniques will be used to simulate
compression. With the ability to simulate realistic,
predictive patient imaging data, we believe the phantom will
provide a vital tool to investigate current and emerging
breast imaging methods and techniques.},
Doi = {10.1117/12.772185},
Key = {fds268532}
}
@article{fds268558,
Author = {Dobbins, JT and McAdams, HP and Godfrey, DJ and Li,
CM},
Title = {Digital tomosynthesis of the chest.},
Journal = {Journal of Thoracic Imaging},
Volume = {23},
Number = {2},
Pages = {86-92},
Year = {2008},
Month = {May},
ISSN = {0883-5993},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18520565},
Keywords = {Humans • Imaging, Three-Dimensional • Lung •
Lung Diseases • Lung Neoplasms • Radiographic
Image Enhancement • Radiographic Image Interpretation,
Computer-Assisted • Radiography, Thoracic • Signal
Processing, Computer-Assisted • diagnosis •
diagnosis* • methods • methods* • radiography
• trends},
Abstract = {Digital tomosynthesis is a technique that generates an
arbitrary number of section images of a patient from a
single pass of the x-ray tube. It is under investigation for
application to a number of clinical detection tasks, and has
recently been implemented in commercial devices for chest
radiography. Tomosynthesis provides improved visibility of
structures in the chest, such as pulmonary nodules, airways,
and spine. This review article outlines the components of a
typical tomosynthesis system, and presents examples of
improved pulmonary nodule detection from a clinical trial in
human subjects. Possible implementation strategies for use
in chest imaging are discussed.},
Language = {eng},
Doi = {10.1097/RTI.0b013e318173e162},
Key = {fds268558}
}
@article{fds172322,
Author = {J.T. Dobbins},
Title = {Chen Y, Lo JY, Dobbins JT 3rd. Impulse response and
modulation transfer function analysis for shift-and-add and
back projection image reconstruction algorithms in digital
breast tomosynthesis (DBT). Int. J. of Functional
Informatics and Personalised Medicine. 2008;1(2):189-204.
},
Year = {2008},
Key = {fds172322}
}
@article{fds172343,
Author = {J.T. Dobbins},
Title = {Li CM, Segars WP, Lo JY, Veress AI, Boone JM, Dobbins JT
3rd. Three-dimensional computer generated breast phantom
based on empirical data. SPIE Medical Imaging Conference.
2008;6913:14.1-14.8.
},
Year = {2008},
Key = {fds172343}
}
@article{fds268509,
Author = {Chen, Y and Lo, JY and Dobbins, JT},
Title = {Impulse response and Modulation Transfer Function analysis
for Shift-And-Add and Back Projection image reconstruction
algorithms in Digital Breast Tomosynthesis
(DBT).},
Journal = {International Journal of Functional Informatics and
Personalised Medicine},
Volume = {1},
Number = {2},
Pages = {189-204},
Year = {2008},
ISSN = {1756-2104},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23935707},
Abstract = {Breast cancer is second only to lung cancer as the leading
cause of non-preventable cancer death in women. Digital
Breast Tomosynthesis (DBT) is a promising technique to
improve early breast cancer detection. In this paper, we
present the impulse response and Modulation Transfer
Function (MTF) analysis to quantitatively compare
Shift-And-Add (SAA) and point-by-point Back Projection (BP)
three-dimensional image reconstruction algorithms in DBT. A
Filtered Back Projection (FBP) deblurring algorithm based on
point-by-point BP was used to demonstrate deblurred
tomosynthesis images.},
Doi = {10.1504/IJFIPM.2008.020187},
Key = {fds268509}
}
@article{fds268531,
Author = {Chen, Y and Lo, JY and Dobbins, JT},
Title = {A comparison between traditional shift-and-add (SAA) and
point-by-point back projection (BP) - Relevance to
morphology of microcalcifications for isocentric motion in
Digital Breast tomosynthesis (DBT)},
Journal = {Proceedings of the 7th Ieee International Conference on
Bioinformatics and Bioengineering, Bibe},
Pages = {563-569},
Publisher = {IEEE},
Year = {2007},
Month = {December},
url = {http://dx.doi.org/10.1109/BIBE.2007.4375617},
Abstract = {Digital breast tomosynthesis (DBT) is a three-dimensional
imaging technique providing an arbitrary set of
reconstruction planes in the breast with limited series of
projection images. This paper describes a comparison between
traditional shift-and-add (SAA) and point-by-point back
projection (BP) algorithms by impulse response and
modulation transfer function (MTF) analysis. Due to the
partial isocentric motion of the x-ray tube in DBT,
structures such as microcalcifications appear slightly
blurred in traditional shift-and-add (SAA) images in the
direction perpendicular to the direction of tube 's motion.
Point-by-point BP improved rendition of microcalcifications.
The sharpness and morphology of calcifications were improved
in a human subject images. A Filtered Back Projection (FBP)
deblurring approach was used to demonstrate deblurred
point-by-point BP tomosynthesis images. The point-by-point
BP rather than traditional SAA should be considered as the
foundation of further deblurring algorithms for DBT
reconstruction. ©2007 IEEE.},
Doi = {10.1109/BIBE.2007.4375617},
Key = {fds268531}
}
@article{fds268529,
Author = {Li, CM and Dobbins, JT},
Title = {Methodology for determining dose reduction for chest
tomosynthesis},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6510},
Number = {PART 2},
Publisher = {SPIE},
Year = {2007},
Month = {October},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.713554},
Abstract = {Digital tomosynthesis is an imaging technique that
reconstructs tomographic planes in an object from a set of
projection images taken over a fixed angle1. Preliminary
results show that this technique increases the detectability
of lung nodules 2. Current settings acquire images with
approximately the same exposure as a screen-film lateral.
However, due to the increased detectability of lung nodules
from the removal of overlying structures, patient dose may
be reduced while still maintaining increased sensitivity and
specificity over conventional chest radiographs. This study
describes a simulation method that provides realistic
reduced dose images by adding noise to digital chest
tomosynthesis images in order to simulate lower exposure
settings for the purpose of dose optimization. Tomosynthesis
projections of human subjects were taken at dose levels
which were specified based on either patient thickness or a
photo-timed digital chest radiograph acquired prior to
tomosynthesis acquisition. For the purposes of this study,
subtle nodules of varying size were simulated in the image
for demonstration purposes before the noise simulation in
order to have a known truth for nodule location and to
evaluate the effect of additive noise on tumor detection.
Noise was subsequently added in order to simulate 3/4, 1/2,
and 1/4 of the original exposure in each projection. The
projections were then processed with the MITS algorithm to
produce slice images. This method will be applied to a study
of dose reduction in the future using human subject
cases.},
Doi = {10.1117/12.713554},
Key = {fds268529}
}
@article{fds268530,
Author = {Chen, Y and Lo, JY and Ranger, NT and Samei, E and Dobbins,
JT},
Title = {Methodology of NEQ (f) analysis for optimization and
comparison of digital breast tomosynthesis acquisition
techniques and reconstruction algorithms},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6510},
Number = {PART 1},
Publisher = {SPIE},
Year = {2007},
Month = {October},
ISBN = {081946628X},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.713737},
Abstract = {As a new three-dimensional imaging technique, digital breast
tomosynthesis allows the reconstruction of an arbitrary set
of planes in the breast from a limited-angle series of
projection images. Though several tomosynthesis algorithms
have been proposed, no complete optimization and comparison
of different tomosynthesis acquisition techniques for
available methods has been conducted as of yet. This paper
represents a methodology of noise-equivalent quanta NEQ (f)
analysis to optimize and compare the efficacy of
tomosynthesis algorithms and imaging acquisition techniques
for digital breast tomosynthesis. It combines the modulation
transfer function (MTF) of system signal performance and the
noise power spectrum (NPS) of noise characteristics. It
enables one to evaluate the performance of different
acquisition parameters and algorithms for comparison and
optimization purposes. An example of this methodology was
evaluated on a selenium-based direct-conversion flat-panel
Siemens Mammomat Novation prototype system. An edge method
was used to measure the presampled MTF of the detector. The
MTF associated with the reconstruction algorithm and
specific acquisition technique was investigated by
calculating the Fourier Transform of simulated impulse
responses. Flat field tomosynthesis projection sequences
were acquired and then reconstructed. A mean-subtracted NPS
on the reconstructed plane was studied to remove fixed
pattern noise. An example of the application of this
methodology was illustrated in this paper using a
point-by-point Back Projection correction (BP)
reconstruction algorithm and an acquisition technique of 25
projections with 25 degrees total angular tube
movement.},
Doi = {10.1117/12.713737},
Key = {fds268530}
}
@article{fds268552,
Author = {Chen, Y and Lo, JY and Dobbins, JT},
Title = {Importance of point-by-point back projection correction for
isocentric motion in digital breast tomosynthesis: relevance
to morphology of structures such as microcalcifications.},
Journal = {Medical Physics},
Volume = {34},
Number = {10},
Pages = {3885-3892},
Year = {2007},
Month = {October},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17985634},
Keywords = {Algorithms • Breast • Breast Neoplasms •
Calcinosis • Calibration • Female • Humans
• Image Processing, Computer-Assisted • Imaging,
Three-Dimensional • Mammography • Phantoms,
Imaging • Radiographic Image Interpretation,
Computer-Assisted • Reproducibility of Results •
Signal Processing, Computer-Assisted • X-Rays •
diagnosis* • instrumentation • methods •
methods* • pathology • pathology*},
Abstract = {Digital breast tomosynthesis is a three-dimensional imaging
technique that provides an arbitrary set of reconstruction
planes in the breast from a limited-angle series of
projection images acquired while the x-ray tube moves.
Traditional shift-and-add (SAA) tomosynthesis reconstruction
is a common mathematical method to line up each projection
image based on its shifting amount to generate
reconstruction slices. With parallel-path geometry of tube
motion, the path of the tube lies in a plane parallel to the
plane of the detector. The traditional SAA algorithm gives
shift amounts for each projection image calculated only
along the direction of x-ray tube movement. However, with
the partial isocentric motion of the x-ray tube in breast
tomosynthesis, small objects such as microcalcifications
appear blurred (for instance, about 1-4 pixels in blur for a
microcalcification in a human breast) in traditional SAA
images in the direction perpendicular to the direction of
tube motion. Some digital breast tomosynthesis algorithms
reported in the literature utilize a traditional
one-dimensional SAA method that is not wholly suitable for
isocentric motion. In this paper, a point-by-point back
projection (BP) method is described and compared with
traditional SAA for the important clinical task of
evaluating morphology of small objects such as
microcalcifications. Impulse responses at different
three-dimensional locations with five different combinations
of imaging acquisition parameters were investigated.
Reconstruction images of microcalcifications in a human
subject were also evaluated. Results showed that with
traditional SAA and 45 degrees view angle of tube movement
with respect to the detector, at the same height above the
detector, the in-plane blur artifacts were obvious for
objects farther away from x-ray source. In a human subject,
the appearance of calcifications was blurred in the
direction orthogonal to the tube motion with traditional
SAA. With point-by-point BP, the appearance of
calcifications was sharper. The point-by-point BP method
demonstrated improved rendition of microcalcifications in
the direction perpendicular to the tube motion direction.
With wide angles or for imaging of larger breasts, this
point-by-point BP rather than the traditional SAA should
also be considered as the basis of further deblurring
algorithms that work in conjunction with the BP
method.},
Language = {eng},
Doi = {10.1118/1.2776256},
Key = {fds268552}
}
@article{fds268554,
Author = {Ranger, NT and Samei, E and Dobbins, JT and Ravin,
CE},
Title = {Assessment of detective quantum efficiency: intercomparison
of a recently introduced international standard with prior
methods.},
Journal = {Radiology},
Volume = {243},
Number = {3},
Pages = {785-795},
Year = {2007},
Month = {June},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17517933},
Keywords = {Equipment Failure Analysis • Internationality* •
Practice Guidelines as Topic* • Radiographic Image
Enhancement • Reference Standards •
Reproducibility of Results • Sensitivity and
Specificity • instrumentation* • methods* •
standards*},
Abstract = {PURPOSE: To prospectively evaluate the recently introduced
international standard method for measurement of the
detective quantum efficiency (DQE) of digital radiography
systems, in comparison with representative prior methods.
MATERIALS AND METHODS: A recently introduced international
standard method (International Electrotechnical Commission
[IEC] 62220-1, 2003) for DQE measurement and two previously
described DQE evaluation methods were considered. In
addition to an overall comparison, evaluations of the
following method factors were performed: beam quality,
beam-limiting devices (apertures or collimators), noise
power spectrum (NPS) analysis algorithms and parameters
(area, region of interest size, background detrending), and
modulation transfer function (MTF) test devices and methods.
RESULTS: Overall, at low to middle frequencies, the IEC
method yielded DQE estimates that were 3.3% and 6.5% lower
than the values yielded by the two previous methods.
Averaged over the frequency range of 1.5-2.5 mm(-1), the DQE
estimate derived by using the IEC method was 7.1% lower and
12.4% higher than the estimates derived by using the other
two methods. Results obtained with the two previous DQE
evaluation methods agreed well (within 2.0%) in the low- to
middle-frequency range but diverged by up to 10% at higher
frequencies. When the DQE method factors were evaluated
separately, the largest percentage deviations in DQE were
associated with (in order of decreasing influence) the MTF
analysis method ( approximately 11%), the beam limitation
(about 7%-10%), the beam quality ( approximately 9%), and
the NPS analysis method ( approximately 3%). CONCLUSION:
Comparison of DQE estimates obtained by using the recently
introduced international standard technique with those
obtained by using prior methods revealed that the overall
measurement method can affect the DQE estimate by as much as
12%. Findings further suggest that both beam limitation
achieved by means of internal collimation (rather than
external apertures) and use of a radio-opaque edge MTF
device yield a more accurate estimation of the
DQE.},
Language = {eng},
Doi = {10.1148/radiol.2433060485},
Key = {fds268554}
}
@article{fds268553,
Author = {Samei, E and Stebbins, SA and Dobbins, JT and McAdams, HP and Lo,
JY},
Title = {Multiprojection correlation imaging for improved detection
of pulmonary nodules.},
Journal = {Ajr. American Journal of Roentgenology},
Volume = {188},
Number = {5},
Pages = {1239-1245},
Year = {2007},
Month = {May},
ISSN = {1546-3141},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17449766},
Keywords = {Aged • Algorithms • Cost-Benefit Analysis •
Female • Humans • Imaging, Three-Dimensional
• Lung Neoplasms • Male • Middle Aged •
Phantoms, Imaging • Radiation Dosage •
Radiographic Image Interpretation, Computer-Assisted* •
economics • radiography*},
Abstract = {OBJECTIVE: The purpose of this study was the development and
preliminary evaluation of multiprojection correlation
imaging with 3D computer-aided detection (CAD) on chest
radiographs for cost- and dose-effective improvement of
early detection of pulmonary nodules. SUBJECTS AND METHODS:
Digital chest radiographs of 10 configurations of a chest
phantom and of seven human subjects were acquired in
multiple angular projections with an acquisition time of 11
seconds (single breath-hold) and total exposure comparable
with that of a posteroanterior chest radiograph. An initial
2D CAD algorithm with two difference-of-gaussians filters
and multilevel thresholds was developed with an independent
database of 44 single-view chest radiographs with confirmed
lesions. This 2D CAD algorithm was used on each projection
image to find likely suspect nodules. The CAD outputs were
reconstructed in 3D, reinforcing signals associated with
true nodules while simultaneously decreasing false-positive
findings produced by overlapping anatomic features. The
performance of correlation imaging was tested on two to 15
projection images. RESULTS: Optimum performance of
correlation imaging was attained when nine projection images
were used. Compared with conventional, single-view CAD,
correlation imaging decreased as much as 79% the frequency
of false-positive findings in phantom cases at a sensitivity
level of 65%. The corresponding reduction in false-positive
findings in the cases of human subjects was 78%. CONCLUSION:
Although limited by a relatively simple CAD implementation
and a small number of cases, the findings suggest that
correlation imaging performs substantially better than
single-view CAD and may greatly enhance identification of
subtle solitary pulmonary nodules on chest
radiographs.},
Language = {eng},
Doi = {10.2214/AJR.06.0843},
Key = {fds268553}
}
@article{fds268518,
Author = {lo, JY and Singh, S and Dobbins, JT and Samei, E},
Title = {MO‐D‐L100F‐03: New Developments in Digital Breast
Tomosynthesis},
Journal = {Medical Physics},
Volume = {34},
Number = {6},
Pages = {2518},
Publisher = {WILEY},
Year = {2007},
Month = {January},
ISSN = {0094-2405},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000247479600854&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {Digital tomosynthesis is one of the most exciting recent
developments in breast imaging. By modifying existing full
field digital mammography systems, one can achieve this type
of limited‐angle cone‐beam CT imaging which produces 3D
slice images of the breast. Overlapping dense tissue in
mammography is one of the most common causes for unnecessary
callbacks as well as missed cancers. Since the 3D images
remove such overlapping tissue, breast tomosynthesis can
improve radiologists' specificity by obviating unnecessary
callbacks. It can also improve sensitivity by allowing
easier detection and characterization of breast cancers
which might otherwise be obscured. Most remarkably,
tomosynthesis can achieve all this with a scan that is
comparable to the speed, resolution, cost, and dose of
conventional mammography. For these reasons, tomosynthesis
stands poised as the only imaging technique with the
potential to completely replace the current role of
mammography as the primary tool in breast cancer screening
and diagnosis. This presentation will cover both the hype
and hope surrounding breast tomosynthesis. From a medical
physics perspective, the latest results will be reviewed
from recent studies to optimize radiographic techniques,
acquisition modes, and reconstruction algorithms. In
addition, emerging results will be surveyed from advanced
applications including display/visualization, computer aided
detection, and contrast enhanced tomosynthesis. Finally, the
clinical promise and risks of this new technology will be
discussed using initial clinical trial results. This
research was supported in part by research grants from
Siemens Medical Solutions, US Army Breast Cancer Research
Program, and NIH/NCI. Educational Objectives: 1. Understand
the difference between breast tomosynthesis and dedicated
breast CT. 2. Appreciate the many medical physics issues
involved in the development and optimization of breast
tomosynthesis. 3. Understand the clinical promise and
concerns of using breast tomosynthesis. © 2007, American
Association of Physicists in Medicine. All rights
reserved.},
Doi = {10.1118/1.2761222},
Key = {fds268518}
}
@article{fds327285,
Author = {Ranger, N and Mackenzie, A and Honey, I and Dobbins, J and Ravin, C and Samei, E},
Title = {TU‐EE‐A4‐06: Experimental Evaluation of Effective
Detective Quantum Efficiency for Digital Radiographic
Imaging Systems},
Journal = {Medical Physics},
Volume = {34},
Number = {6},
Pages = {2564},
Publisher = {WILEY},
Year = {2007},
Month = {January},
url = {http://dx.doi.org/10.1118/1.2761409},
Abstract = {Purpose: To develop and evaluate an experimental methodology
for measuring the effective detective quantum efficiency
(eDQE) of digital radiographic systems which reflects the
actual signal‐to‐noise performance of the system per
unit exposure. Method and Materials: A NEXT phantom,
simulating the scatter and attenuation properties of an
adult human thorax was used to measure the resolution,
noise, and scatter performance of a digital radiographic
system (GE xQi) under conditions approximating those seen in
clinical chest radiography. The resolution was measured in
terms of the modulation transfer function (MTF) using an
edge device placed at the phantom surface closest to the
x‐ray tube. The noise was measured in terms of the noise
power spectrum (NPS) of the region corresponding to the
phantom center, acquired at three exposure levels. The
scatter fraction (SF) was evaluated using a beam‐stop
technique. These measurements along with measures of phantom
attenuation and estimates of x‐ray flux and exposure were
incorporated in the computation of the effective Detective
Quantum Efficiency (eDQE). Results: The phantom exhibited a
broad‐beam transmission fraction of 18.65%. The measured
scatter fraction in the presence of grid and phantom was
33%. The MTF of the system dropped by 25% at 1.0 cycles/mm
when the edge was placed at the phantom surface due to
scatter and focal spot blurring. The computed eDQE was
assessed to be 0.038 and 0.028 at 0.5 and 1.0 cycles/mm,
respectively (for E= 5.6 mR). Conclusion: Conventional DQE
measurements performed under relatively idealized conditions
do not accurately represent the relative performance of
digital radiographic imaging systems in routine clinical
use. A more appropriate metric, the eDQE, measured under
conditions that reasonably approximate those encountered
clinically reflects the additional contributions from
scatter, grid, and focal spot blurring, and provides a
better estimate of the relative clinical performance of
digital radiographic imaging systems. © 2007, American
Association of Physicists in Medicine. All rights
reserved.},
Doi = {10.1118/1.2761409},
Key = {fds327285}
}
@article{fds172341,
Author = {J.T. Dobbins},
Title = {Chen Y, Lo JY, Dobbins JT 3rd. Methodology of NEQ(f)
analysis for optimization and comparison of digital breast
tomosynthesis acquisition techniques and reconstruction
algorithms. SPIE Medical Imaging Conference.
2007;6510:1I1-1I9.},
Year = {2007},
Key = {fds172341}
}
@article{fds172342,
Author = {J.T. Dobbins},
Title = {Li CM, Dobbins JT 3rd. Methodology for determining dose
reduction for chest tomosynthesis. SPIE Medical Imaging
Conference. 2007;6510:2D1-2D10.
},
Year = {2007},
Key = {fds172342}
}
@article{fds268548,
Author = {McAdams, HP and Samei, E and Dobbins, J and Tourassi, GD and Ravin,
CE},
Title = {Recent advances in chest radiography.},
Journal = {Radiology},
Volume = {241},
Number = {3},
Pages = {663-683},
Year = {2006},
Month = {December},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17114619},
Keywords = {Data Display • Humans • Image Processing,
Computer-Assisted • Radiographic Image Interpretation,
Computer-Assisted • Radiography, Thoracic •
Scattering, Radiation • Subtraction Technique •
X-Ray Intensifying Screens • methods* •
trends*},
Abstract = {There have been many remarkable advances in conventional
thoracic imaging over the past decade. Perhaps the most
remarkable is the rapid conversion from film-based to
digital radiographic systems. Computed radiography is now
the preferred imaging modality for bedside chest imaging.
Direct radiography is rapidly replacing film-based chest
units for in-department posteroanterior and lateral
examinations. An exciting aspect of the conversion to
digital radiography is the ability to enhance the diagnostic
capabilities and influence of chest radiography.
Opportunities for direct computer-aided detection of various
lesions may enhance the radiologist's accuracy and improve
efficiency. Newer techniques such as dual-energy and
temporal subtraction radiography show promise for improved
detection of subtle and often obscured or overlooked lung
lesions. Digital tomosynthesis is a particularly promising
technique that allows reconstruction of multisection images
from a short acquisition at very low patient dose.
Preliminary data suggest that, compared with conventional
radiography, tomosynthesis may also improve detection of
subtle lung lesions. The ultimate influence of these new
technologies will, of course, depend on the outcome of
rigorous scientific validation.},
Language = {eng},
Doi = {10.1148/radiol.2413051535},
Key = {fds268548}
}
@article{fds268527,
Author = {Li, CM and Dobbins, JT},
Title = {Preliminary assessment of the temporal subtraction of
tomosynthesis images for improved detection of pulmonary
nodules},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6142 III},
Publisher = {SPIE},
Year = {2006},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.652492},
Abstract = {Digital tomosynthesis is an imaging technique which
reconstructs tomographic planes in an object from a set of
projection images taken over a fixed angle [1]. Results from
our initial pilot study show that tomosynthesis increases
the detectability of lung nodules; while only 50% of CT
confirmed nodules were found on typical chest radiographs,
81% were found on tomosynthesis image sets[2]. Temporal
subtraction is a method which takes two sequential images
and subtracts one from another, emphasizing the appearance
of interval change[3-6]. As an addition to conventional
chest radiography, it has been shown in several studies to
significantly increase observer performance in detecting
newly developed abnormalities[7-10]. Thus the combination of
temporal subtraction and tomosynthesis may yield improved
sensitivity of detection over either method alone. For this
preliminary evaluation into the combination of these
techniques, images were taken of an anthropomorphic chest
phantom in different orientations and subtle lung nodules
were simulated in order to emulate temporal discrepancies in
anatomy. An automated method of segmentation, registration,
and image warping was employed to align corresponding lung
regions of each image set. The visibility of temporal change
of simulated nodules was more apparent in the subtraction
image. By our subjective analysis, tomosynthesis
substantially improved the visibility of nodules relative to
conventional chest radiography; and tomosynthesis augmented
by temporal subtraction even further enhanced the
conspicuity of difficultly placed subtle
nodules.},
Doi = {10.1117/12.652492},
Key = {fds268527}
}
@article{fds268528,
Author = {Chen, Y and Lo, JY and Dobbins, JT},
Title = {Noise power spectrum analysis for several digital breast
tomosynthesis reconstruction algorithms},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6142 III},
Publisher = {SPIE},
Year = {2006},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.652282},
Abstract = {Digital breast tomosynthesis is a three-dimensional imaging
technique that allows the reconstruction of an arbitrary set
of planes in the breast from limited-angle series of
projection images. Though several tomosynthesis algorithms
have been proposed, no complete optimization and comparison
of all available methods has been conducted as of yet. This
paper presents an analysis of noise power spectrum to
examine the noise characteristics of several tomosynthesis
algorithms with different imaging acquisition techniques.
Flat images were acquired with the following acquisition
parameters: 13, 25, 49 projections with ±12.5 and ±25
degrees of angular ranges. Three algorithms, including
Shift-And-Add (SAA), Matrix Inversion Tomosynthesis (MITS),
and Filtered Back Projection (FBP) were investigated with
reconstruction slice spacing of 1mm, 2mm, and 4mm. The noise
power spectra of the reconstruction plane at 23.5mm above
the detector surface were analyzed. Results showed that MITS
has better noise responses with narrower slice spacing for
low-to-middle frequencies. No substantial difference was
noticed for SAA and FBP with different slice spacings. With
the same acquisition technique and slice spacing, MITS
performed better than FBP at middle frequencies, but FBP
showed better performance at high frequencies because of
applied Hamming and Gaussian low-pass filters. For different
imaging acquisition techniques, SAA, MITS and FBP performed
the best with 49 projections and ±25 degrees. For 25
projections specifically, FBP performed better with wider
angular range, while MITS performed better with narrower
angular range. For SAA, narrow angular range is slightly
better for 25 projections and 13 projections.},
Doi = {10.1117/12.652282},
Key = {fds268528}
}
@article{fds268543,
Author = {Chen, Y and Lo, JY and Baker, JA and Dobbins, JT},
Title = {Gaussian frequency blending algorithm with Matrix Inversion
Tomosynthesis (MITS) and Filtered Back Projection (FBP) for
better digital breast tomosynthesis reconstruction},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6142 I},
Publisher = {SPIE},
Year = {2006},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.652264},
Abstract = {Breast cancer is a major problem and the most common cancer
among women. The nature of conventional mammography makes it
very difficult to distinguish a cancer from overlying breast
tissues. Digital Tomosynthesis refers to a three-dimensional
imaging technique that allows reconstruction of an arbitrary
set of planes in the breast from limited-angle series of
projection images as the x-ray source moves. Several
tomosynthesis algorithms have been proposed, including
Matrix Inversion Tomosynthesis (MITS) and Filtered Back
Projection (FBP) that have been investigated in our lab.
MITS shows better high frequency response in removing
out-of-plane blur, while FBP shows better low frequency
noise prosperities. This paper presents an effort to combine
MITS and FBP for better breast tomosynthesis reconstruction.
A high-pass Gaussian filter was designed and applied to
three-slice "slabbing" MITS reconstructions. A low-pass
Gaussian filter was designed and applied to the FBP
reconstructions. A frequency weighting parameter was studied
to blend the high-passed MITS with low-passed FBP frequency
components. Four different reconstruction methods were
investigated and compared with human subject images: 1) MITS
blended with Shift-And-Add (SAA), 2) FBP alone, 3) FBP with
applied Hamming and Gaussian Filters, and 4) Gaussian
Frequency Blending (GFB) of MITS and FBP. Results showed
that, compared with FBP, Gaussian Frequency Blending (GFB)
has better performance for high frequency content such as
better reconstruction of micro-calcifications and removal of
high frequency noise. Compared with MITS, GFB showed more
low frequency breast tissue content.},
Doi = {10.1117/12.652264},
Key = {fds268543}
}
@article{fds268526,
Author = {Nasab, NM and Samei, E and Dobbins, JT},
Title = {Biplane correlation imaging for lung nodule detection:
Initial human subject results},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {6144 I},
Publisher = {SPIE},
Year = {2006},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.652582},
Abstract = {In this paper, we present performance of biplane correlation
imaging (BCI) on set of chest x-ray projections of human
data. BCI significantly minimizes the number of false
positives (FPs) when used in conjunction with computer aided
detection (CAD) by eliminating non-correlated nodule
candidates. Sixty-one low exposure posterior projections
were acquired from more than 20 human subjects with small
angular separations (0.32 degree) over a range of 20 degrees
along the vertical axis. All patients were previously
diagnosed for the presence of lung nodules based on computed
tomography (CT) examination. Images were processed following
two steps. First, all images were analyzed using our CAD
routine for chest radiography. This process proceeded with a
BCI processing in which the results of CAD on each single
projection were examined in terms of their geometrical
correlation with those found in the other 60 projections
based on the predetermined shift of possible nodule
locations in each projection. The suspect entities with a
geometrical correlation that coincided with the known
location of the lesions were selected as nodules; otherwise
they were ignored. An expert radiologist with reference to
the associated CT dataset determined the truth regarding
nodule location and sizes, which were then used to determine
if the found nodules are true positive or false positive.
The preliminary results indicated that the best performance
was obtained when the angular separation of the projection
pair was greater than about 6.7 degrees. Within the range of
optimum angular separation, the number of FPs per image was
0-1 without impacting the number of true positives (TPs),
averaged around 92%. (Supported by grants from the NIH:
R01-CA80490 and R01CA109074).},
Doi = {10.1117/12.652582},
Key = {fds268526}
}
@article{fds172306,
Author = {JT Dobbins 3rd and E Samei and NT Ranger and Y Chen},
Title = {Intercomparison of methods for image quality
characterization. II. Noise power spectrum.},
Journal = {Medical physics},
Volume = {33},
Number = {5},
Pages = {1466-75},
Year = {2006},
Month = {May},
ISSN = {0094-2405},
Keywords = {Algorithms* • Artifacts • Quality Assurance,
Health Care • Radiographic Image Enhancement •
Radiographic Image Interpretation, Computer-Assisted •
Reproducibility of Results • Sensitivity and
Specificity • Stochastic Processes •
methods*},
Abstract = {Second in a two-part series comparing measurement techniques
for the assessment of basic image quality metrics in digital
radiography, in this paper we focus on the measurement of
the image noise power spectrum (NPS). Three methods were
considered: (1) a method published by Dobbins et al. [Med.
Phys. 22, 1581-1593 (1995)], (2) a method published by Samei
et al. [Med. Phys. 30, 608-622 (2003)], and (3) a new method
sanctioned by the International Electrotechnical Commission
(IEC 62220-1, 2003), developed as part of an international
standard for the measurement of detective quantum
efficiency. In addition to an overall comparison of the
estimated NPS between the three techniques, the following
factors were also evaluated for their effect on the measured
NPS: horizontal versus vertical directional dependence, the
use of beam-limiting apertures, beam spectrum, and
computational methods of NPS analysis, including the
region-of-interest (ROI) size and the method of ROI
normalization. Of these factors, none was found to
demonstrate a substantial impact on the amplitude of the NPS
estimates (< or = 3.1% relative difference in NPS averaged
over frequency, for each factor considered separately).
Overall, the three methods agreed to within 1.6% +/- 0.8%
when averaged over frequencies > 0.15 mm(-1).},
Language = {eng},
Key = {fds172306}
}
@article{fds172308,
Author = {E Samei and NT Ranger and JT Dobbins 3rd and Y Chen},
Title = {Intercomparison of methods for image quality
characterization. I. Modulation transfer
function.},
Journal = {Medical physics},
Volume = {33},
Number = {5},
Pages = {1454-65},
Year = {2006},
Month = {May},
ISSN = {0094-2405},
Keywords = {Algorithms* • Quality Assurance, Health Care •
Radiographic Image Enhancement • Radiographic Image
Interpretation, Computer-Assisted • Reproducibility of
Results • Sensitivity and Specificity •
methods*},
Abstract = {The modulation transfer function (MTF) and the noise power
spectrum (NPS) are widely recognized as the most relevant
metrics of resolution and noise performance in radiographic
imaging. These quantities have commonly been measured using
various techniques, the specifics of which can have a
bearing on the accuracy of the results. As a part of a study
aimed at comparing the relative performance of different
techniques, in this paper we report on a comparison of two
established MTF measurement techniques: one using a slit
test device [Dobbins et al., Med. Phys. 22, 1581-1593
(1995)] and another using a translucent edge test device
[Samei et al., Med. Phys. 25, 102-113 (1998)], with one
another and with a third technique using an opaque edge test
device recommended by a new international standard (IEC
62220-1, 2003). The study further aimed to substantiate the
influence of various acquisition and processing parameters
on the estimated MTF. The slit test device was made of 2 mm
thick Pb slabs with a 12.5 microm opening. The translucent
edge test device was made of a laminated and polished
Pt(0.9)Ir(0.1). alloy foil of 0.1 mm thickness. The opaque
edge test device was made of a 2 mm thick W slab. All test
devices were imaged on a representative indirect flat-panel
digital radiographic system using three published beam
qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm
Al filtration, and 74 kV with 21 mm Al filtration
(IEC-RQA5). The latter technique was also evaluated in
conjunction with two external beam-limiting apertures (per
IEC 62220-1), and with the tube collimator limiting the beam
to the same area achieved with the apertures. The presampled
MTFs were deduced from the acquired images by Fourier
analysis techniques, and the results analyzed for relative
values and the influence of impacting parameters. The
findings indicated that the measurement technique has a
notable impact on the resulting MTF estimate, with estimates
from the overall IEC method 4.0% +/- 0.2% lower than that of
Dobbins et al. and 0.7% +/- 0.4% higher than that of Samei
et al. averaged over the zero to cutoff frequency range.
Over the same frequency range, keeping beam quality and
limitation constant, the average MTF estimate obtained with
the edge techniques differed by up to 5.2% +/- 0.2% from
that of the slit, with the opaque edge providing lower MTF
estimates at lower frequencies than those obtained with the
translucent edge or slit. The beam quality impacted the
average estimated MTF by as much as 3.7% +/- 0.9% while the
use of beam limiting devices alone increased the average
estimated MTF by as much as 7.0% +/- 0.9%. While the slit
method is inherently very sensitive to misalignment, both
edge techniques were found to tolerate misalignments by as
much as 6 cm. The results suggest the use of the opaque edge
test device and the tube internal collimator for beam
limitation in order to achieve an MTF result most reflective
of the overall performance of the imaging system and least
susceptible to misalignment and scattered radiation. Careful
attention to influencing factors is warranted to achieve
accurate results.},
Language = {eng},
Key = {fds172308}
}
@article{8909923,
Author = {Dobbins, JT and Samei, E and Ranger, NT and Chen,
Y},
Title = {Intercomparison of methods for image quality
characterization. II. Noise power spectrum.},
Journal = {Medical Physics},
Volume = {33},
Number = {5},
Pages = {1466-1475},
Year = {2006},
Month = {May},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16752581},
Keywords = {diagnostic radiography;image resolution;noise;},
Abstract = {Second in a two-part series comparing measurement techniques
for the assessment of basic image quality metrics in digital
radiography, in this paper we focus on the measurement of
the image noise power spectrum (NPS). Three methods were
considered: (1) a method published by Dobbins et al. [Med.
Phys. 22, 1581-1593 (1995)], (2) a method published by Samei
et al. [Med. Phys. 30, 608-622 (2003)], and (3) a new method
sanctioned by the International Electrotechnical Commission
(IEC 62220-1, 2003), developed as part of an international
standard for the measurement of detective quantum
efficiency. In addition to an overall comparison of the
estimated NPS between the three techniques, the following
factors were also evaluated for their effect on the measured
NPS: horizontal versus vertical directional dependence, the
use of beam-limiting apertures, beam spectrum, and
computational methods of NPS analysis, including the
region-of-interest (ROI) size and the method of ROI
normalization. Of these factors, none was found to
demonstrate a substantial impact on the amplitude of the NPS
estimates (< or = 3.1% relative difference in NPS averaged
over frequency, for each factor considered separately).
Overall, the three methods agreed to within 1.6% +/- 0.8%
when averaged over frequencies > 0.15 mm(-1).},
Doi = {10.1118/1.2188819},
Key = {8909923}
}
@article{8909922,
Author = {Samei, E and Ranger, NT and Dobbins, JT and Chen,
Y},
Title = {Intercomparison of methods for image quality
characterization. I. Modulation transfer
function.},
Journal = {Medical Physics},
Volume = {33},
Number = {5},
Pages = {1454-1465},
Year = {2006},
Month = {May},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16752580},
Keywords = {aluminium;biomedical equipment;copper;diagnostic
radiography;filtration;Fourier analysis;image
resolution;platinum compounds;},
Abstract = {The modulation transfer function (MTF) and the noise power
spectrum (NPS) are widely recognized as the most relevant
metrics of resolution and noise performance in radiographic
imaging. These quantities have commonly been measured using
various techniques, the specifics of which can have a
bearing on the accuracy of the results. As a part of a study
aimed at comparing the relative performance of different
techniques, in this paper we report on a comparison of two
established MTF measurement techniques: one using a slit
test device [Dobbins et al., Med. Phys. 22, 1581-1593
(1995)] and another using a translucent edge test device
[Samei et al., Med. Phys. 25, 102-113 (1998)], with one
another and with a third technique using an opaque edge test
device recommended by a new international standard (IEC
62220-1, 2003). The study further aimed to substantiate the
influence of various acquisition and processing parameters
on the estimated MTF. The slit test device was made of 2 mm
thick Pb slabs with a 12.5 microm opening. The translucent
edge test device was made of a laminated and polished
Pt(0.9)Ir(0.1). alloy foil of 0.1 mm thickness. The opaque
edge test device was made of a 2 mm thick W slab. All test
devices were imaged on a representative indirect flat-panel
digital radiographic system using three published beam
qualities: 70 kV with 0.5 mm Cu filtration, 70 kV with 19 mm
Al filtration, and 74 kV with 21 mm Al filtration
(IEC-RQA5). The latter technique was also evaluated in
conjunction with two external beam-limiting apertures (per
IEC 62220-1), and with the tube collimator limiting the beam
to the same area achieved with the apertures. The presampled
MTFs were deduced from the acquired images by Fourier
analysis techniques, and the results analyzed for relative
values and the influence of impacting parameters. The
findings indicated that the measurement technique has a
notable impact on the resulting MTF estimate, with estimates
from the overall IEC method 4.0% +/- 0.2% lower than that of
Dobbins et al. and 0.7% +/- 0.4% higher than that of Samei
et al. averaged over the zero to cutoff frequency range.
Over the same frequency range, keeping beam quality and
limitation constant, the average MTF estimate obtained with
the edge techniques differed by up to 5.2% +/- 0.2% from
that of the slit, with the opaque edge providing lower MTF
estimates at lower frequencies than those obtained with the
translucent edge or slit. The beam quality impacted the
average estimated MTF by as much as 3.7% +/- 0.9% while the
use of beam limiting devices alone increased the average
estimated MTF by as much as 7.0% +/- 0.9%. While the slit
method is inherently very sensitive to misalignment, both
edge techniques were found to tolerate misalignments by as
much as 6 cm. The results suggest the use of the opaque edge
test device and the tube internal collimator for beam
limitation in order to achieve an MTF result most reflective
of the overall performance of the imaging system and least
susceptible to misalignment and scattered radiation. Careful
attention to influencing factors is warranted to achieve
accurate results.},
Doi = {10.1118/1.2188816},
Key = {8909922}
}
@article{fds172307,
Author = {DJ Godfrey and HP McAdams and JT Dobbins 3rd},
Title = {Optimization of the matrix inversion tomosynthesis (MITS)
impulse response and modulation transfer function
characteristics for chest imaging.},
Journal = {Medical physics},
Volume = {33},
Number = {3},
Pages = {655-67},
Year = {2006},
Month = {March},
ISSN = {0094-2405},
Keywords = {Algorithms • Humans • Phantoms, Imaging •
Radiographic Image Enhancement • Radiographic Image
Interpretation, Computer-Assisted • Radiography,
Thoracic • Reproducibility of Results •
Sensitivity and Specificity • Solitary Pulmonary Nodule
• Thorax* • Tomography, X-Ray • diagnosis
• methods* • radiography*},
Abstract = {Matrix inversion tomosynthesis (MITS) uses linear systems
theory, along with a priori knowledge of the imaging
geometry, to deterministically distinguish between true
structure and overlying tomographic blur in a set of
conventional tomosynthesis planes. In this paper we examine
the effect of total scan angle (ANG), number of input
projections (N), and plane separation/number of
reconstructed planes (NP) on the MITS impulse response (IR)
and modulation transfer function (MTF), with the purpose of
optimizing MITS imaging of the chest. MITS IR and MTF data
were generated by simulating the imaging of a very thin
wire, using various combinations of ANG, N, and NP. Actual
tomosynthesis data of an anthropomorphic chest phantom were
acquired with a prototype experimental system, using the
same imaging parameter combinations as those in the
simulations. Thoracic projection data from two human
subjects were collected for corroboration of the system
response analysis in vivo. Results suggest that ANG=20
degrees, N=71, NP=69 is the optimal combination for MITS
chest imaging given the inherent constraints of our
prototype system. MITS chest data from human subjects
demonstrates that the selected imaging strategy can
effectively produce high-quality MITS thoracic images in
vivo.},
Language = {eng},
Key = {fds172307}
}
@article{8832235,
Author = {Godfrey, DJ and McAdams, HP and Dobbins, JT},
Title = {Optimization of the matrix inversion tomosynthesis (MITS)
impulse response and modulation transfer function
characteristics for chest imaging.},
Journal = {Medical Physics},
Volume = {33},
Number = {3},
Pages = {655-667},
Year = {2006},
Month = {March},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16878569},
Keywords = {diagnostic radiography;image reconstruction;lung;matrix
inversion;medical image processing;optical transfer
function;optimisation;transient response;},
Abstract = {Matrix inversion tomosynthesis (MITS) uses linear systems
theory, along with a priori knowledge of the imaging
geometry, to deterministically distinguish between true
structure and overlying tomographic blur in a set of
conventional tomosynthesis planes. In this paper we examine
the effect of total scan angle (ANG), number of input
projections (N), and plane separation/number of
reconstructed planes (NP) on the MITS impulse response (IR)
and modulation transfer function (MTF), with the purpose of
optimizing MITS imaging of the chest. MITS IR and MTF data
were generated by simulating the imaging of a very thin
wire, using various combinations of ANG, N, and NP. Actual
tomosynthesis data of an anthropomorphic chest phantom were
acquired with a prototype experimental system, using the
same imaging parameter combinations as those in the
simulations. Thoracic projection data from two human
subjects were collected for corroboration of the system
response analysis in vivo. Results suggest that ANG=20
degrees, N=71, NP=69 is the optimal combination for MITS
chest imaging given the inherent constraints of our
prototype system. MITS chest data from human subjects
demonstrates that the selected imaging strategy can
effectively produce high-quality MITS thoracic images in
vivo.},
Doi = {10.1118/1.2170398},
Key = {8832235}
}
@article{fds268517,
Author = {Ranger, NT and Samei, E and Dobbins, JT and Ravin,
CE},
Title = {SU‐FF‐I‐48: Assessment of Detective Quantum
Efficiency: Inter‐Comparison of IEC 62220‐1 with
Representative Prior Methods},
Journal = {Medical Physics},
Volume = {33},
Number = {6},
Pages = {2007},
Publisher = {WILEY},
Year = {2006},
Month = {January},
ISSN = {0094-2405},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000238688500148&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {Purpose: To evaluate a new international standard method for
the measurement of detective quantum efficiency (DQE) of
digital radiography systems in comparison with
representative prior methods. Methods and Materials: Three
DQE evaluation methods were considered: 1) a relatively
recent international standard method published by the
International Electrotechnical Commission (IEC, 62220‐1,
2003) which was evaluated in comparison with previously
published methods by 2) Dobbins et al (Med Phys
22:1581–1593, 1995) and 3) Samei et al (Med Phys 30:
608–622, 2003). In addition to an overall comparison of
the methods, the impact of the defining factors that
comprise each method were evaluated including: beam quality,
the presence of beam‐limiting devices (apertures or
collimators), the NNPS analysis algorithm and processing
parameters, and the MTF test device and associated analysis
methodology. Results: The IEC DQE results at
low/mid‐frequencies were lower than those obtained using
the method of Dobbins et al and Samei et al by 3.3% and
6.5%, respectively. Averaged over 1.5–2.5 mm−1, the DQE
estimate according to the IEC method was 7.1% lower and
̃12.4% higher than that of the other two methods,
respectively. The overall DQE methods of Dobbins et al and
Samei et al agreed well (within 2.0%) in the low‐ to
mid‐frequency range but diverged by up to 10% at higher
frequencies. Of the influencing factors on the DQE estimate
considered, the most significant impact was seen with the
MTF measurement method, followed by the beam‐limitation
method. Conclusions: Comparison of DQE estimates using the
new standard technique with results using prior methods
demonstrated that measurement method can impact the DQE
estimate by as much as 12%. Specifically, the results
suggest the use of beam limitation using internal
collimation (rather than external apertures) and use of a
radio‐opaque edge MTF test device for more accurate
estimation of the DQE. © 2006, American Association of
Physicists in Medicine. All rights reserved.},
Doi = {10.1118/1.2240288},
Key = {fds268517}
}
@article{fds327411,
Author = {Chen, Y and Lo, J and Baker, J and Dobbins, J},
Title = {SU‐FF‐I‐21: Two‐Dimensional Shift‐And‐Add (SAA)
Algorithm for Digital Breast Tomosynthesis
Reconstruction},
Journal = {Medical Physics},
Volume = {33},
Number = {6},
Pages = {2001},
Publisher = {WILEY},
Year = {2006},
Month = {January},
url = {http://dx.doi.org/10.1118/1.2240260},
Abstract = {Purpose: To investigate a two‐dimensional
Shift‐And‐Add algorithm for three‐dimensional digital
breast tomosynthsis reconstruction to correct for defects
existing in the traditional Shift‐And‐Add algorithm that
calculates only one‐dimensional shift amount along the
axis of x‐ray tube's motion. Method and Materials: With
the traditional Shift‐And‐Add (SAA) algorithm for breast
tomosynthesis reconstruction, shift amounts for each
projection plane are calculated only along the axis of
x‐ray tube's movement. As a result, small objects such as
microcalcifications appear slightly blurred in the direction
perpendicular to the direction of tube motion. In this
project, a two‐dimensional SAA method was developed to
correct for this phenomenon. Shift amounts for every pixel
location on each reconstruction plane were computed, taking
into account the 2D arc projection location of reconstructed
objects in each plane. Bilinear interpolation was used for
partial pixel locations. Impulses at different 3‐D
locations were simulated and a few human subject
tomosynthesis sequences were acquired for investigation.
Results: Two‐dimensional SAA demonstrated the improvement
in the direction that is perpendicular to the tube motion
direction. For human subjects, the appearance of
calcifications from 2D SAA was sharper than traditional SAA
at the direction orthogonal to the tube motion direction.
The out‐of‐plane artifacts of calcifications changed
from curved to be straight. Conclusion: Two‐dimensional
SAA is an effective method to reconstruct 3D tomosynthesis
images of the breast. Compared with the traditional SAA, the
new method corrects for 2D shift amounts coming from the
isocentric tube motion. This provides more accurate and
reliable results compared with other SAA algorithms.
Conflict of Interest: Research sponsored in part by a
research grant from Siemens Medical Solutions. © 2006,
American Association of Physicists in Medicine. All rights
reserved.},
Doi = {10.1118/1.2240260},
Key = {fds327411}
}
@article{fds172337,
Author = {J.T. Dobbins},
Title = {Chen Y, Lo JY, Baker JA, Dobbins JT 3rd. Gaussian frequency
blending algorithm with matrix inversion tomosynthesis
(MITS) and filtered back projection (FBP) for better digital
breast tomosynthesis reconstruction. SPIE Medical Imaging
Conference. 2006;6142:0E1-0E9.},
Year = {2006},
Key = {fds172337}
}
@article{fds172338,
Author = {J.T. Dobbins},
Title = {Chen Y, Lo JY, Dobbins JT 3rd. Noise power spectrum analysis
for several digital breast tomosynthesis reconstruction
algorithms. SPIE Medical Imaging Conference.
2006;6142:59.1-59.8.
},
Year = {2006},
Key = {fds172338}
}
@article{fds172339,
Author = {J.T. Dobbins},
Title = {Li CM, Dobbins JT 3rd. Preliminary assessment of the
temporal subtraction of tomosynthesis images for improved
detection of pulmonary nodules. SPIE Medical Imaging
Conference. 2006;6142: 5C1-6C8.
},
Year = {2006},
Key = {fds172339}
}
@article{fds172340,
Author = {J.T. Dobbins},
Title = {Nasab NM, Samei E, Dobbins JT 3rd. Biplane correlation
imaging for lung nodule detection: initial human subject
results. SPIE Medical Imaging Conference.
2006;6144:1X-1X8.},
Year = {2006},
Key = {fds172340}
}
@article{fds331534,
Author = {Godfrey, DJ and Oldham, M and Dobbins, JT and Yin,
F},
Title = {Online Digital Tomosynthesis (DTS): A Novel Technique for
Improving Target Localization in Radiation
Therapy},
Journal = {International Journal of Radiation Oncology, Biology,
Physics},
Volume = {63},
Number = {2},
Pages = {S556-S556},
Publisher = {Elsevier BV},
Year = {2005},
Month = {October},
url = {http://dx.doi.org/10.1016/j.ijrobp.2005.07.937},
Doi = {10.1016/j.ijrobp.2005.07.937},
Key = {fds331534}
}
@article{fds268524,
Author = {Baydush, AH and Godfrey, DJ and Oldham, M and Dobbins,
JT},
Title = {Initial application of digital tomosynthesis with on-board
imaging in radiation oncology},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {5745},
Number = {II},
Pages = {1300-1305},
Publisher = {SPIE},
Year = {2005},
Month = {August},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.596245},
Abstract = {We present preliminary investigations that examine the
feasibility of incorporating digital tomosynthesis into
radiation oncology practice with the use of kilovoltage
on-board imagers (OBI). Modern radiation oncology linear
accelerators now include hardware options for the addition
of OBI for on-line patient setup verification. These systems
include an x-ray tube and detector mounted directly on the
accelerator gantry that rotate with the same isocenter.
Applications include cone beam computed tomography (CBCT),
fluoroscopy, and radiographs to examine daily patient
positioning to determine if the patient is in the same
location as the treatment plan. While CBCT provides the
greatest anatomical detail, this approach is limited by long
acquisition and reconstruction times and higher patient
dose. We propose to examine the use of tomosynthesis
reconstructed volumetric data from limited angle projection
images for short imaging time and reduced patient dose.
Initial data uses 61 projection images acquired over an
isocentric arc of twenty degrees with the detector
approximately fifty-four centimeters from isocenter. A
modified filtered back projection technique, which included
a mathematical correction for isocentric motion, was used to
reconstruct volume images. These images will be visually and
mathematically compared to volumetric computed tomography
images to determine efficacy of this system for daily
patient positioning verification. Initial images using the
tomosynthesis reconstruction technique show much promise and
bode well for effective daily patient positioning
verification with reduced patient dose and imaging time.
Additionally, the fast image acquisition may allow for a
single breath hold imaging sequence, which will have no
breath motion.},
Doi = {10.1117/12.596245},
Key = {fds268524}
}
@article{fds268525,
Author = {Chen, Y and Lo, JY and Dobbins, JT},
Title = {Impulse response analysis for several digital tomosynthesis
mammography reconstruction algorithms},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {5745},
Number = {I},
Pages = {541-549},
Publisher = {SPIE},
Year = {2005},
Month = {August},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.595684},
Abstract = {Digital tomosynthesis mammography algorithms allow
reconstructions of arbitrary planes in the breast from
limited-angle series of projection images as the x-ray
source moves along an arc above the breast. Though several
tomosynthesis algorithms have been proposed, no complete
comparison of the methods has previously been conducted.
This paper presents an analysis of impulse response for four
different tomosynthesis mammography reconstruction
algorithms. Simulated impulses at different 3-D locations
were simulated to investigate the sharpness of reconstructed
in-plane structures and to see how effective each algorithm
is at removing out-of-plane blur. Datasets with 41, 21 and
11 projection images of the impulse were generated with a
total angular movement of +/-10 degrees of the simulated
x-ray point source. Four algorithms, including shift-and-add
method, Niklason algorithm, filtered back projection (FBP),
and matrix inversion tomosynthesis (MITS) are investigated.
Compared with shift-and-add algorithm and Niklason method,
MITS and FBP performed better for in-plane response and
out-of-plane blur removal. MITS showed better out-of-plane
blur removal in general. MITS and FBP performed better when
projection numbers increase.},
Doi = {10.1117/12.595684},
Key = {fds268525}
}
@article{fds268555,
Author = {Ranger, NT and Samei, E and Dobbins, JT and Ravin,
CE},
Title = {Measurement of the detective quantum efficiency in digital
detectors consistent with the IEC 62220-1 standard:
Practical considerations regarding the choice of filter
material.},
Journal = {Med Phys},
Volume = {32},
Number = {7Part1},
Pages = {2305-2311},
Year = {2005},
Month = {July},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/16121586},
Keywords = {Equipment Failure Analysis • Filtration •
Guidelines as Topic • Internationality • Quality
Assurance, Health Care • Quantum Theory •
Radiographic Image Enhancement • Reference Standards
• Reproducibility of Results • Sensitivity and
Specificity • Technology Assessment, Biomedical •
Transducers* • X-Ray Intensifying Screens •
instrumentation* • methods • standards •
standards*},
Abstract = {As part of a larger evaluation we attempted to measure the
detective quantum efficiency (DQE) of an amorphous silicon
flat-panel detector using the method described in the
International Electrotechnical Commission standard 62220-1
published in October 2003. To achieve the radiographic beam
conditions specified in the standard, we purchased
scientific-grade ultrahigh purity aluminum (99.999% purity,
type-11999 alloy) filters in thicknesses ranging from 0.1
through 10.0 mm from a well-known, specialty metals
supplier. Qualitative evaluation of flat field images
acquired at 71 kV (RQA5 beam quality) with 21 mm of
ultrahigh purity aluminum filtration demonstrated a low
frequency mottle that was reproducible and was not observed
when the measurement was repeated at 74 kV (RQA5 beam
quality) with 21 mm of lower-purity aluminum (99.0% purity,
type-1100 alloy) filtration. This finding was ultimately
attributed to the larger grain size (approximately 1-2 mm)
of high purity aluminum metal, which is a well-known
characteristic, particularly in thicknesses greater than 1
mm. The impact of this low frequency mottle is to
significantly overestimate the noise power spectrum (NPS) at
spatial frequencies ⩽0.2mm-1, which in turn would cause an
underestimation of the DQE in this range. A subsequent
evaluation of ultrahigh purity aluminum, purchased from a
second source, suggests, that reduced grain size can be
achieved by the process of annealing. Images acquired with
this sample demonstrated vertical striated nonuniformities
that are attributed to the manufacturing method and which do
not appear to appreciably impact the NPS at spatial
frequencies ⩾0.5mm-1, but do result in an asymmetry in the
x- and y-NPS at spatial frequencies ⩽0.2mm-1. Our
observations of markedly visible nonuniformities in images
acquired with high purity aluminum filtration suggest that
the uniformity of filter materials should be carefully
evaluated and taken into consideration when measuring the
DQE.},
Language = {eng},
Doi = {10.1118/1.1929187},
Key = {fds268555}
}
@article{fds268569,
Author = {Samei, E and Lo, JY and Yoshizumi, TT and Jesneck, JL and Dobbins, JT and Floyd, CE and McAdams, HP and Ravin, CE},
Title = {Comparative scatter and dose performance of slot-scan and
full-field digital chest radiography systems.},
Journal = {Radiology},
Volume = {235},
Number = {3},
Pages = {940-949},
Year = {2005},
Month = {June},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15845791},
Keywords = {Phantoms, Imaging • Radiation Dosage •
Radiographic Image Enhancement* • Radiography, Thoracic
• methods • standards*},
Abstract = {PURPOSE: To evaluate the scatter, dose, and effective
detective quantum efficiency (DQE) performance of a
slot-scan digital chest radiography system compared with
that of a full-field digital radiography system. MATERIALS
AND METHODS: Scatter fraction of a slot-scan system was
measured for an anthropomorphic and a geometric phantom by
using a posterior beam-stop technique at 117 and 140 kVp.
Measurements were repeated with a full-field digital
radiography system with and without a 13:1 antiscatter grid
at 120 and 140 kVp. For both systems, the effective dose was
measured on posteroanterior and lateral views for standard
clinical techniques by using dosimeters embedded in a female
phantom. The effective DQEs of the two systems were assessed
by taking into account the scatter performance and the DQE
of each system. The statistical significance of all the
comparative differences was ascertained by means of t test
analysis. RESULTS: The slot-scan system and the full-field
system with grid yielded scatter fractions of 0.13-0.14 and
0.42-0.48 in the lungs and 0.30-0.43 and 0.69-0.78 in the
mediastinum, respectively. The sum of the effective doses
for posteroanterior and lateral views for the slot-scan
system (0.057 mSv +/- 0.003 [+/- standard deviation]) was
34% lower than that for the full-field system (0.086 mSv +/-
0.001, P < .05) at their respective clinical peak voltages
(140 and 120 kVp, respectively). The effective DQE of the
slot-scan system was equivalent to that of the full-field
system in the lung region but was 37% higher in the dense
regions (P < .05). CONCLUSION: The slot-scan design leads to
marked scatter reduction compared with the more conventional
full-field geometries with a grid. The improved scatter
performance of a slot-scan geometry can effectively
compensate for low DQE and lead to improved image
quality.},
Language = {eng},
Doi = {10.1148/radiol.2353040516},
Key = {fds268569}
}
@article{fds327286,
Author = {Godfrey, D and Oldham, M and Dobbins, J and Yin, F},
Title = {SU‐FF‐J‐57: Digital Tomosynthesis for Verification of
Radiation Therapy Positioning: Preliminary Results From a
Kilovoltage On‐Board Imaging System},
Journal = {Medical Physics},
Volume = {32},
Number = {6},
Pages = {1932},
Publisher = {WILEY},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1118/1.1997603},
Abstract = {Purpose: This study introduces a new radiation therapy
target localization technique using online digital
tomosynthesis (DTS), a method for reconstructing 3‐D
slices from 2‐D projection data acquired with limited
source motion. By separating the visualization of
overlapping structure, DTS is expected to improve the
visualization of anatomy compared with 2‐D planar
radiographic imaging techniques, and may therefore yield
more accurate target localization during radiation therapy
set‐up. Method and Materials: We simulated treatment
planning and setup of an anthropomorphic chest phantom. A
treatment isocenter was marked in CT images. The phantom was
then aligned for treatment on a Varian 21EX equipped with an
on‐board‐imager (OBI), attached to the gantry orthogonal
to the megavoltage treatment axis. Once aligned, 2‐D image
projections were acquired over 200 degrees and coronal and
sagittal DTS planes were reconstructed through the treatment
isocenter from projection sub‐sets spanning 40°.
Comparison of DTS images with corresponding planes from the
CT data, as well as lateral and postero‐anterior (PA)
planar radiographs, yielded estimations of set‐up error.
Results: Sagittal and coronal DTS slices improved the
visibility of anatomy when compared with planar radiograph
equivalents, improving estimation of the set‐up error.
Registration of sagittal and coronal DTS reconstructions
with corresponding planes through the isocenter in the CT
data was found to be feasible for estimating set‐up error.
Preliminary determination of the set‐up accuracy of our
clinical procedure was determined to be within 1mm for the
phantom study presented here. Conclusion: Tomosynthesis has
been demonstrated on a commercially available medical
accelerator, and may be practical for improving patient
set‐up when full cone‐beam‐CT is not required. DTS
significantly improves the visibility of soft‐tissue
detail that is obscured by overlying anatomy in radiographs
and portal images. Additional benefits include a reduction
in dose, acquisition and reconstruction time, and easier
data handling compared with full cone‐beam‐CT. © 2005,
American Association of Physicists in Medicine. All rights
reserved.},
Doi = {10.1118/1.1997603},
Key = {fds327286}
}
@article{fds327412,
Author = {Godfrey, D and Mcadams, H and Dobbins, J},
Title = {MO‐D‐I‐6B‐04: Matrix Inversion Tomosynthesis (MITS)
Imaging of the Chest},
Journal = {Medical Physics},
Volume = {32},
Number = {6},
Pages = {2058},
Publisher = {WILEY},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1118/1.1999682},
Abstract = {Tomosynthesis is a method for reconstructing 3‐dimensional
(3‐D) image data from a series of x‐ray projection
radiographs, acquired with limited motion of the x‐ray
source (typically no more than 40 degrees). Digital
tomosynthesis (DTS) is implemented with a flat‐panel
digital detector and can be integrated into standard digital
chest radiography or mammography systems, providing a
flexible platform for the acquisition of 3‐D image data in
the clinical environment. DTS can be performed with short
acquisition times (single breath‐hold duration), and
requires lower dose and will likely be less expensive than
traditional CT. Resolution in DTS images is high in the two
dimensions displayed by a single reconstructed plane, but is
reduced in the third dimension (plane‐to‐plane) by the
limited scan angle. Conventional tomosynthesis reconstructs
3‐D planes by simply shifting and summing projection
images to bring a user‐specified depth into focus.
Unfortunately, planes reconstructed in this manner contain
substantial low‐frequency tomographic blur from distant
anatomy, which reduces the visibility of in‐plane
structure. More sophisticated reconstruction methods include
filtered‐backprojection, direct inverse solutions, and
iterative inverse algorithms which allow the user to impose
constraints upon the inverse solution. Matrix inversion
tomosynthesis (MITS) is a direct inverse solution which uses
the known image acquisition geometry to model a set of
conventional tomosynthesis planes in terms of true
in‐plane structure and out‐of‐plane tomographic blur.
In‐plane structure is separated from residual blur by
solving systems of linear algebraic equations in the Fourier
domain. Resulting MITS reconstructions exhibit enhanced
visibility of in‐plane anatomy compared with conventional
tomosynthesis planes. MITS imaging of the chest is likely to
improve the detection of lung nodules by resolving anatomy
which would otherwise overlap in radiographs. A MITS pilot
study was performed with 20 human volunteers who were known
to have subtle pulmonary lung nodules, as determined by CT.
MITS projection images were collected using a commercial
x‐ray tube and stationary flat‐panel detector, equipped
with prototype rapid‐readout electronics. Angulation of
the x‐ray source was controlled with prototype motion
hardware constructed in our laboratory. Total tomosynthesis
exposures ranged from 1x to 2x the radiation exposure that
would have been necessary to acquire a 250‐speed
film/screen lateral radiograph. All projection data was
acquired during a single breath‐hold (roughly 11 seconds).
Preliminary human observer results indicate that MITS
improved the sensitivity of retrospective lung nodule
detection by 50% compared with standard radiography in the
pilot study. This work was supported in part by grants from
the National Institutes of Health (RO1 CA80490) and G. E.
Medical Systems. Educational Objectives: 1. To gain a
general understanding of tomosynthesis and its relation to
both radiography and computed tomography. 2. To understand
the benefits and limitations of tomosynthesis. 3. To view
sample human chest tomosynthesis data for illustration of
key concepts. © 2005, American Association of Physicists in
Medicine. All rights reserved.},
Doi = {10.1118/1.1999682},
Key = {fds327412}
}
@article{8523003,
Author = {Samei, E. and Dobbins, J.T., III and Lo, J.Y. and Tornai,
M.P.},
Title = {A framework for optimising the radiographic technique in
digital X-ray imaging},
Journal = {Radiat. Prot. Dosim. (UK)},
Volume = {114},
Number = {1-3},
Pages = {220 - 9},
Address = {Malmo, Sweden},
Year = {2005},
url = {http://dx.doi.org/10.1093/rpd/nch562},
Keywords = {bone;caesium compounds;computerised tomography;diagnostic
radiography;mammography;medical image processing;optimisation;rhodium;selenium;tungsten;},
Abstract = {The transition to digital radiology has provided new
opportunities for improved image quality, made possible by
the superior detective quantum efficiency and
post-processing capabilities of new imaging systems, and
advanced imaging applications, made possible by rapid
digital image acquisition. However, this transition has
taken place largely without optimising the radiographic
technique used to acquire the images. This paper proposes a
framework for optimising the acquisition of digital X-ray
images. The proposed approach is based on the signal and
noise characteristics of the digital images and the applied
exposure. Signal is defined, based on the clinical task
involved in an imaging application, as the difference
between the detector signal with and without a target
present against a representative background. Noise is
determined from the noise properties of uniformly acquired
images of the background, taking into consideration the
absorption properties of the detector. Incident exposure is
estimated or otherwise measured free in air, and converted
to dose. The main figure of merit (FOM) for optimisation is
defined as the signal-difference-to-noise ratio (SdNR)
squared per unit exposure or (more preferably) dose. This
paper highlights three specific technique optimisation
studies that used this approach to optimise the radiographic
technique for digital chest and breast applications. In the
first study, which was focused on chest radiography with a
CsI flat-panel detector, a range of kV<sub>p</sub> (50-150)
and filtration (Z=13-82) were examined in terms of their
associated FOM as well as soft tissue to bone contrast, a
factor of importance in digital chest radiography. The
results indicated that additive Cu filtration can improve
image quality. A second study in digital mammography using a
selenium direct flat-panel detector indicated improved SdNR
per unit exposure with the use of a tungsten target and a
rhodium filter than conventional molybdenum
target/molybdenum filter techniques. Finally, a third study
focusing on cone-beam computed tomography of the breast
using a CsI flat-panel detector indicated that high Z
filtration of a tungsten target X-ray beam can notably
improve the signal and noise characteristics of the image.
The general findings highlight the fact that the techniques
that are conventionally assumed to be optimum may need to be
revisited for digital radiography},
Key = {8523003}
}
@article{fds131771,
Author = {J.T. Dobbins},
Title = {Samei E, Dobbins JT III, Lo JY, Tornai M: A framework for
optimizing the radiographic technique in digital x-ray
imaging. Radiation Protection Dosimetry (accepted
2005).},
Year = {2005},
Key = {fds131771}
}
@article{fds131772,
Author = {J.T. Dobbins},
Title = {Chen Y, Dobbins JT III: Impulse response analysis for
several digital tomosynthesis mammography reconstruction
algorithms. Proc. SPIE Medical Imaging Symposium.
2005;5745:541-549.},
Year = {2005},
Key = {fds131772}
}
@article{fds131773,
Author = {J.T. Dobbins},
Title = {Bissonnette M, Hansroul M, Masson E, Savard S, Cadieux S,
Warmoes P, Gravel D, Agopyan J, Polischuk B, Haerer W,
Mertelmeier T, Lo JY, Chen Y, Dobbins JT III, Jesneck JL and
Singh S: Digital breast tomosynthesis using an amorphous
selenium flat panel detector. Proc. SPIE Medical Imaging
Symposium. 2005;5745:529-540.},
Year = {2005},
Key = {fds131773}
}
@article{fds131774,
Author = {J.T. Dobbins},
Title = {Baydush AH, Godfrey DJ, Oldham M, Dobbins JT III: Initial
application of digital tomosynthesis with on-board imaging
in radiation oncology. Proc. SPIE Medical Imaging Symposium.
2005;5745:1300-1305.},
Year = {2005},
Key = {fds131774}
}
@article{fds131775,
Author = {J.T. Dobbins},
Title = {Samei E, Dobbins JT III, Ranger NT, Chen Y:
Inter-comparison of methods for image quality comparison:
1. Modulation transfer function. Medical Physics
(submitted), 2005.},
Year = {2005},
Key = {fds131775}
}
@article{fds131776,
Author = {J.T. Dobbins},
Title = {Dobbins JT III, Samei E, Ranger NT, Chen Y:
Inter-comparison of methods for image quality comparison:
2. Noise power spectrum. Medical Physics (submitted),
2005.},
Year = {2005},
Key = {fds131776}
}
@article{fds131777,
Author = {J.T. Dobbins},
Title = {Ranger NT, Samei E, Dobbins JT III, Ravin CE:
Inter-comparison of methods for image quality comparison:
3. Detective quantum efficiency. Medical Physics
(submitted), 2005.},
Year = {2005},
Key = {fds131777}
}
@article{fds131778,
Author = {J.T. Dobbins},
Title = {Ranger NT, Samei E, Dobbins JT III, Ravin CE:
Measurement of the detective quantum efficiency in digital
detectors consistent with the IEC 62220-1 standard:
practical considerations regarding the choice of filter
material. Medical Physics (accepted 2005).},
Year = {2005},
Key = {fds131778}
}
@article{fds131779,
Author = {J.T. Dobbins},
Title = {Godfrey DJ, McAdams HP, Dobbins JT III: Stochastic noise
characteristics in matrix inversion tomosynthesis (MITS).
Medical Physics (submitted), 2005.},
Year = {2005},
Key = {fds131779}
}
@article{fds131780,
Author = {J.T. Dobbins},
Title = {Godfrey DJ, McAdams HP, Dobbins JT III: Averaging adjacent
planes for artifact reduction in matrix inversion
tomosynthesis (MITS). Medical Physics (submitted),
2005.},
Year = {2005},
Key = {fds131780}
}
@article{fds131781,
Author = {J.T. Dobbins},
Title = {Godfrey DJ, McAdams HP, Dobbins JT III: Optimization of
the matrix inversion tomosynthesis (MITS) impulse response
and modulation transfer function characteristics for chest
imaging. Medical Physics (submitted), 2005.},
Year = {2005},
Key = {fds131781}
}
@article{fds172309,
Author = {J.T. Dobbins},
Title = {Eberhard JW, Claus BEH, Alkhalidy AA, Dobbins JT III,
Godfrey DJ. Continuous scan RAD tomosynthesis system and
method. U.S. patent # 6,970,531, November 29,
2005.},
Year = {2005},
Key = {fds172309}
}
@article{8503490,
Author = {Samei, E. and Lo, J.Y. and Yoshizumi, T.T. and Jesneck, J.L. and Dobbins, J.T., III and Floyd, C.E., Jr. and McAdams,
H.P. and Ravin, C.E.},
Title = {Comparative scatter and dose performance of slot-scan and
full-field digital chest radiography systems},
Journal = {Radiology (USA)},
Volume = {235},
Number = {3},
Pages = {940 - 9},
Year = {2005},
url = {http://dx.doi.org/10.1148/radiol.2353040516},
Keywords = {diagnostic radiography;dosimeters;dosimetry;lung;phantoms;},
Abstract = {The purpose of this paper is to evaluate the scatter, dose,
and effective detective quantum efficiency (DQE) performance
of a slot-scan digital chest radiography system compared
with that of a full-field digital radiography system.
Scatter fraction of a slot-scan system was measured for an
anthropomorphic and a geometric phantom by using a posterior
beam-stop technique at 117 and 140 kVp. Measurements were
repeated with a full-field digital radiography system with
and without a 13:1 antiscatter grid at 120 and 140 kVp. For
both systems, the effective dose was measured on
posteroanterior and lateral views for standard clinical
techniques by using dosimeters embedded in a female phantom.
The effective DQEs of the two systems were assessed by
taking into account the scatter performance and the DQE of
each system. The statistical significance of all the
comparative differences was ascertained by means of t test
analysis. The slot-scan system and the full-field system
with grid yielded scatter fractions of 0.13-0.14 and
0.42-0.48 in the lungs and 0.30-0.43 and 0.69-0.78 in the
mediastinum, respectively. The sum of the effective doses
for posteroanterior and lateral views for the slot-scan
system (0.057 mSv±0.003 [±standard deviation])
was 34% lower than that for the full-field system (0.086
mSv±0.001, P<.05) at their respective clinical
peak voltages (140 and 120 kVp, respectively). The effective
DQE of the slot-scan system was equivalent to that of the
full-field system in the lung region but was 37% higher in
the dense regions (P<.05). The slot-scan design leads to
marked scatter reduction compared with the more conventional
full-field geometries with a grid. It is concluded that the
improved scatter performance of a slot-scan geometry can
effectively compensate for low DQE and lead to improved
image quality},
Key = {8503490}
}
@article{fds268560,
Author = {Samei, E and Dobbins, JT and Lo, JY and Tornai, MP},
Title = {A framework for optimising the radiographic technique in
digital X-ray imaging.},
Journal = {Radiation Protection Dosimetry},
Volume = {114},
Number = {1-3},
Pages = {220-229},
Year = {2005},
ISSN = {0144-8420},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15933112},
Keywords = {Bone and Bones • Cesium • Computers •
Equipment Design • Humans • Iodides •
Mammography • Models, Statistical • Radiation
Dosage • Radiographic Image Enhancement •
Radiographic Image Interpretation, Computer-Assisted •
Radiography • Radiography, Thoracic • Radiology
• Scattering, Radiation • Software • Tungsten
• X-Ray Intensifying Screens • X-Rays* •
chemistry • instrumentation* • methods •
methods* • radiography},
Abstract = {The transition to digital radiology has provided new
opportunities for improved image quality, made possible by
the superior detective quantum efficiency and
post-processing capabilities of new imaging systems, and
advanced imaging applications, made possible by rapid
digital image acquisition. However, this transition has
taken place largely without optimising the radiographic
technique used to acquire the images. This paper proposes a
framework for optimising the acquisition of digital X-ray
images. The proposed approach is based on the signal and
noise characteristics of the digital images and the applied
exposure. Signal is defined, based on the clinical task
involved in an imaging application, as the difference
between the detector signal with and without a target
present against a representative background. Noise is
determined from the noise properties of uniformly acquired
images of the background, taking into consideration the
absorption properties of the detector. Incident exposure is
estimated or otherwise measured free in air, and converted
to dose. The main figure of merit (FOM) for optimisation is
defined as the signal-difference-to-noise ratio (SdNR)
squared per unit exposure or (more preferably) dose. This
paper highlights three specific technique optimisation
studies that used this approach to optimise the radiographic
technique for digital chest and breast applications. In the
first study, which was focused on chest radiography with a
CsI flat-panel detector, a range of kV(p) (50-150) and
filtration (Z = 13-82) were examined in terms of their
associated FOM as well as soft tissue to bone contrast, a
factor of importance in digital chest radiography. The
results indicated that additive Cu filtration can improve
image quality. A second study in digital mammography using a
selenium direct flat-panel detector indicated improved SdNR
per unit exposure with the use of a tungsten target and a
rhodium filter than conventional molybdenum
target/molybdenum filter techniques. Finally, a third study
focusing on cone-beam computed tomography of the breast
using a CsI flat-panel detector indicated that high Z
filtration of a tungsten target X-ray beam can notably
improve the signal and noise characteristics of the image.
The general findings highlight the fact that the techniques
that are conventionally assumed to be optimum may need to be
revisited for digital radiography.},
Language = {eng},
Doi = {10.1093/rpd/nch562},
Key = {fds268560}
}
@article{05349316242,
Author = {Bissonnette, M and Hansroul, M and Masson, E and Savard, S and Cadieux,
S and Warmoes, P and Gravel, D and Agopyan, J and Polischuk, B and Haerer,
W and Mertelmeier, T and Lo, JY and Chen, Y and Dobbins III and JT and Jesneck, JL and Singh, S},
Title = {Digital breast tomosynthesis using an amorphous selenium
flat panel detector},
Journal = {Progress in Biomedical Optics and Imaging Proceedings of
Spie},
Volume = {5745},
Number = {I},
Pages = {529-540},
Publisher = {SPIE},
Address = {San Diego, CA, United States},
Year = {2005},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.601622},
Keywords = {Computerized tomography;Biological organs;Selenium;Radiation
detectors;Metal detectors;Quantum efficiency;Optical
transfer function;Image quality;Image reconstruction;Data
acquisition;Three dimensional computer graphics;X ray
analysis;Algorithms;},
Abstract = {A prototype breast tomosynthesis system* has been developed,
allowing a total angular view of ±25°. The
detector used in this system is an amorphous selenium
direct-conversion digital flat-panel detector suitable for
digital tomosynthesis. The system is equipped with various
readout sequences to allow the investigation of different
tomosynthetic data acquisition modes. In this paper, we will
present basic physical properties - such as MTF, NPS, and
DQE - measured for the full resolution mode and a binned
readout mode of the detector. From the measured projections,
slices are reconstructed employing a special version of
filtered backprojection algorithm. In a phantom study, we
compare binned and full resolution acquisition modes with
respect to image quality. Under the condition of same dose,
we investigate the impact of the number of views on
artifacts. Finally, we show tomosynthesis images
reconstructed from first clinical data.},
Doi = {10.1117/12.601622},
Key = {05349316242}
}
@article{fds268585,
Author = {Samei, E and Saunders, RS and Lo, JY and Dobbins, JT and Jesneck, JL and Floyd, CE and Ravin, CE},
Title = {Fundamental imaging characteristics of a slot-scan digital
chest radiographic system.},
Journal = {Medical Physics},
Volume = {31},
Number = {9},
Pages = {2687-2698},
Year = {2004},
Month = {September},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15487752},
Keywords = {Equipment Design • Equipment Failure Analysis* •
Humans • Phantoms, Imaging • Radiographic Image
Enhancement • Radiography, Thoracic •
Reproducibility of Results • Scattering, Radiation
• Sensitivity and Specificity • Technology
Assessment, Biomedical • Technology, Radiologic •
instrumentation • instrumentation* •
methods},
Abstract = {Our purpose in this study was to evaluate the fundamental
image quality characteristics of a new slot-scan digital
chest radiography system (ThoraScan, Delft Imaging
Systems/Nucletron, Veenendaal, The Netherlands). The
linearity of the system was measured over a wide exposure
range at 90, 117, and 140 kVp with added Al filtration.
System uniformity and reproducibility were established with
an analysis of images from repeated exposures. The
modulation transfer function (MTF) was evaluated using an
established edge method. The noise power spectrum (NPS) and
the detective quantum efficiency (DQE) of the system were
evaluated at the three kilo-voltages over a range of
exposures. Scatter fraction (SF) measurements were made
using a posterior beam stop method and a geometrical chest
phantom. The system demonstrated excellent linearity, but
some structured nonuniformities. The 0.1 MTF values occurred
between 3.3-3.5 mm(-1). The DQE(0.15) and DQE(2.5) were 0.21
and 0.07 at 90 kVp, 0.18 and 0.05 at 117 kVp, and 0.16 and
0.03 at 140 kVp, respectively. The system exhibited
remarkably lower SFs compared to conventional full-field
systems with anti-scatter grid, measuring 0.13 in the lungs
and 0.43 in the mediastinum. The findings indicated that the
slot-scan design provides marked scatter reduction leading
to high effective DQE (DQEeff) of the system and reduced
patient dose required to achieve high image
quality.},
Language = {eng},
Doi = {10.1118/1.1783531},
Key = {fds268585}
}
@article{8163357,
Author = {Duryea, J and Neumann, G and Yoshioka, H and Dobbins,
JT},
Title = {Digital tomosynthesis rendering of joint margins for
arthritis assessment},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {5368},
Number = {1},
Pages = {12-18},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2004},
Month = {July},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.535850},
Keywords = {computerised tomography;diagnostic radiography;diseases;image
reconstruction;image segmentation;mean square error
methods;medical image processing;orthopaedics;},
Abstract = {Purpose: Rheumatoid arthritis (RA) of the hand is a
significant healthcare problem. Techniques to accurately
quantity the structural changes from RA are crucial for the
development and prescription of therapies. Analysis of
radiographic joint space width (JSW) is widely used and has
demonstrated promise. However, radiography presents a 2D
view of the joint. In this study we performed tomosynthesis
reconstructions of proximal interphalangeal (PIP), and
metacarpophalangeal (MCP) joints to measure the 3D joint
structure. Methods: We performed a reader study using
simulated radiographs of 12 MCP and 12 PIP joints from
skeletal specimens imaged with micro-CT. The tomosynthesis
technique provided images of reconstructed planes with 0.75
mm spacing, which were presented to 2 readers with a
computer tool. The readers were instructed to delineate the
joint surfaces on tomosynthetic slices where they could
visualize the margins. We performed a quantitative analysis
of 5 slices surrounding the central portion of each joint.
Reader-determined JSW was compared to a gold standard. As a
figure of merit we calculated the average root-mean square
deviation (RMSD). Results: RMSD was 0.22 mm for both joints.
For the individual joints, RMSD was 0.18 mm (MCP), and 0.26
mm (PIP). The reduced performance for the smaller PIP joints
suggests that a slice spacing less than 0.75 mm may be more
appropriate. Conclusions: We have demonstrated the
capability of limited 3D rendering of joint surfaces using
digital tomosynthesis. This technique promises to provide an
improved method to visualize the structural changes of
RA.},
Doi = {10.1117/12.535850},
Key = {8163357}
}
@article{fds268516,
Author = {Maidment, ADA and Antonuk, L and Dobbins, JT and Flynn, M and Seibert,
J and Yorkston, J},
Title = {A debate on the relative merits of digital radiography and
mammography technologies},
Journal = {Medical Physics},
Volume = {31},
Number = {6},
Pages = {1755-1755},
Publisher = {AMER ASSOC PHYSICISTS MEDICINE AMER INST
PHYSICS},
Year = {2004},
Month = {June},
ISSN = {0094-2405},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000222259100230&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Key = {fds268516}
}
@article{fds131769,
Author = {J.T. Dobbins},
Title = {Samei E, Lo JY, Yoshizumi T, Jesneck J, Dobbins JT III,
Floyd CE Jr, McAdams HP, Ravin CE. Comparative scatter and
dose performance of slot-scan and wide-beam digital chest
radiographic systems. Radiology (accepted)
2004.},
Year = {2004},
Key = {fds131769}
}
@article{fds172299,
Author = {J.T. Dobbins},
Title = {Duryea JW, Neumann G, Yoshioka H and Dobbins JT 3rd; Digital
tomosynthesis rendering of joint margins for arthritis
assessment; Proc. SPIE Medical Imaging Symposium.
2004;5368:12-18.},
Year = {2004},
Key = {fds172299}
}
@article{fds268588,
Author = {Dobbins, JT and Godfrey, DJ},
Title = {Digital x-ray tomosynthesis: current state of the art and
clinical potential.},
Journal = {Physics in Medicine and Biology},
Volume = {48},
Number = {19},
Pages = {R65-106},
Year = {2003},
Month = {October},
ISSN = {0031-9155},
url = {http://www.ncbi.nlm.nih.gov/pubmed/14579853},
Keywords = {Algorithms* • Angiography • Bone and Bones •
Imaging, Three-Dimensional • Mammography •
Radiographic Image Enhancement • Radiographic Image
Interpretation, Computer-Assisted • Radiography,
Thoracic • Review Literature as Topic • Signal
Processing, Computer-Assisted* • Tomography, X-Ray
Computed • Tooth • methods • methods* •
radiography • trends},
Abstract = {Digital x-ray tomosynthesis is a technique for producing
slice images using conventional x-ray systems. It is a
refinement of conventional geometric tomography, which has
been known since the 1930s. In conventional geometric
tomography, the x-ray tube and image receptor move in
synchrony on opposite sides of the patient to produce a
plane of structures in sharp focus at the plane containing
the fulcrum of the motion; all other structures above and
below the fulcrum plane are blurred and thus less visible in
the resulting image. Tomosynthesis improves upon
conventional geometric tomography in that it allows an
arbitrary number of in-focus planes to be generated
retrospectively from a sequence of projection radiographs
that are acquired during a single motion of the x-ray tube.
By shifting and adding these projection radiographs,
specific planes may be reconstructed. This topical review
describes the various reconstruction algorithms used to
produce tomosynthesis images, as well as approaches used to
minimize the residual blur from out-of-plane structures.
Historical background and mathematical details are given for
the various approaches described. Approaches for optimizing
the tomosynthesis image are given. Applications of
tomosynthesis to various clinical tasks, including
angiography, chest imaging, mammography, dental imaging and
orthopaedic imaging, are also described.},
Language = {eng},
Doi = {10.1088/0031-9155/48/19/r01},
Key = {fds268588}
}
@article{7793732,
Author = {Godfrey, DJ and Rader, A and Dobbins, JT},
Title = {Practical strategies for the clinical implementation of
matrix inversion tomosynthesis (MITS)},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {5030 I},
Pages = {379-390},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2003},
Month = {September},
url = {http://dx.doi.org/10.1117/12.480352},
Keywords = {biomedical equipment;computerised tomography;diagnostic
radiography;image reconstruction;image sequences;lung;matrix
inversion;medical image processing;phantoms;X-ray
detection;},
Abstract = {Digital tomosynthesis is a method that enables the
retroactive reconstruction of arbitrary tomographic planes
in an object from a finite series of digital projection
radiographs, acquired with limited angle tube movement.
Conventional tomosynthesis suffers from the presence of
blurring artifacts, created by objects located outside of
each reconstructed plane. Matrix inversion tomosynthesis
(MITS) utilizes known acquisition geometry to solve directly
for the unwanted out-of-plane blur artifacts, thus enabling
their removal. This paper examines practical strategies for
the implementation of MITS in a clinical setting, on a
flat-panel fast-readout detector, with the aim of minimizing
procedure time and image reconstruction artifacts
concurrently. Topics include a comparison of continuous vs.
incremental tube motion, the presence of reconstruction
artifacts due to error in computing the x-ray tube location,
the effect of scrubbing the detector between projections to
reduce image retention, and a method for accounting for data
that gets projected off the detector. We conclude that MITS
is robust enough to be clinically applicable, even under
less-than-ideal conditions. Rapid image acquisition with
continuous tube movement and no detector scrubbing is
clinically desirable for MITS imaging of the chest, where
patient motion is a concern. Knowledge of the
source-detector geometry can be satisfactorily determined
via either a lead fiducial marker placed on the patient, or
a tube motion device with sufficient precision and accuracy.
Extrapolation of data at the top and bottom of projection
images provides excellent amelioration of image truncation
artifacts.},
Doi = {10.1117/12.480352},
Key = {7793732}
}
@article{fds268586,
Author = {Duryea, J and Dobbins, JT and Lynch, JA},
Title = {Digital tomosynthesis of hand joints for arthritis
assessment.},
Journal = {Medical Physics},
Volume = {30},
Number = {3},
Pages = {325-333},
Year = {2003},
Month = {March},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12674232},
Keywords = {Arthritis • Artifacts • Finger Joint • Hand
• Humans • Imaging, Three-Dimensional •
Metacarpophalangeal Joint • Radiographic Image
Enhancement • Radiographic Image Interpretation,
Computer-Assisted • Reference Values •
Reproducibility of Results • Sensitivity and
Specificity • methods • methods* •
radiography • radiography*},
Abstract = {The two principal forms of hand arthritis, rheumatoid
arthritis (RA) and osteoarthritis (OA) have large clinical
and economic costs. Radiography has been shown to be a
useful tool to assess the condition of the disease. A hand
radiograph, however, is a two-dimensional projection of a
three-dimensional object. In this report we present the
results of a study that applied digital tomosynthesis to
hand radiography in order to extract three-dimensional
outcome measures that should be more sensitive to arthritis
progression. The study was performed using simulated
projection radiographs created using micro computed
tomography (microCT) and a set of five dry-bone hand
skeletons. These simulated projection images were then
reconstructed into tomographic slices using the matrix
inversion tomosynthesis (MITS) algorithm. The accuracy of
the tomosynthesis reconstruction was evaluated by comparing
the reconstructed images to a gold standard created using
the microCT data. A parameter from image registration
science, normalized mutual information, provided a
quantifiable figure of merit. This study examined the
effects of source displacement, number of reconstructed
planes, number of acquisitions, noise added to the gray
scale images, and errors in the location of a fiducial
marker. We also optimized the reconstruction as a function
of two variables k and alpha, that controlled the mixing of
MITS with conventional shift-and-add tomosynthesis. A study
using hand delineated joint margins demonstrated that MITS
images provided a better measurement of average joint space
width. We found good agreement between the MITS slices and
the true planes. Both joint margins and trabecular structure
were visible and the reconstructed slices showed additional
structures not visible with the standard projection image.
Using hand-delineated joint margins we compared the average
joint space width of the gold standard slices to the MITS
and projection images. A root-mean square deviation (RMSD),
calculated for this comparison, gave RMSDproj = 0.18 mm and
RMSDMITS = 0.14 mm for the projection and MITS images,
respectively. We have demonstrated the potential of digital
tomosynthesis for imaging of the hand to assess arthritic
changes. We have also developed a methodology that can be
used to optimize the technique and have studied the issues
that will control the feasibility of clinical
implementation.},
Language = {eng},
Doi = {10.1118/1.1543573},
Key = {fds268586}
}
@article{fds268587,
Author = {Warp, RJ and Dobbins, JT},
Title = {Quantitative evaluation of noise reduction strategies in
dual-energy imaging.},
Journal = {Medical Physics},
Volume = {30},
Number = {2},
Pages = {190-198},
Year = {2003},
Month = {February},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12607836},
Keywords = {Algorithms* • Artifacts • Humans • Lung
• Phantoms, Imaging • Quality Control •
Radiographic Image Enhancement • Radiography,
Dual-Energy Scanned Projection • Reproducibility of
Results • Sensitivity and Specificity •
instrumentation • methods* • radiography*},
Abstract = {In this paper we describe a quantitative evaluation of the
performance of three dual-energy noise reduction algorithms:
Kalender's correlated noise reduction (KCNR), noise clipping
(NOC), and edge-predictive adaptive smoothing (EPAS). These
algorithms were compared to a simple smoothing filter
approach, using the variance and noise power spectrum
measurements of the residual noise in dual-energy images
acquired with an a-Si TFT flat-panel x-ray detector. An
estimate of the true noise was made through a new method
with subpixel accuracy by subtracting an individual image
from an ensemble average image. The results indicate that in
the lung regions of the tissue image, all three algorithms
reduced the noise by similar percentages at high spatial
frequencies (KCNR=88%, NOC=88%, EPAS=84%, NOC/KCNR=88%) and
somewhat less at low spatial frequencies (KCNR=45%, NOC=54%,
EPAS=52%, NOC/KCNR=55%). At low frequencies, the presence of
edge artifacts from KCNR made the performance worse, thus
NOC or NOC combined with KCNR performed best. At high
frequencies, KCNR performed best in the bone image, yet NOC
performed best in the tissue image. Noise reduction
strategies in dual-energy imaging can be effective and
should focus on blending various algorithms depending on
anatomical locations.},
Language = {eng},
Doi = {10.1118/1.1538232},
Key = {fds268587}
}
@article{7788104,
Author = {Maidment, ADA and Albert, M and Bunch, PC and Cunningham, IA and Dobbins, JT and Gagne, R and Nishikawa, RM and Metter, RV and Wagner,
RF},
Title = {Standardization of NPS measurement: Interim report of AAPM
TG16},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {5030 I},
Pages = {523-532},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1117/12.480451},
Keywords = {biomedical equipment;diagnostic radiography;mammography;measurement
standards;noise measurement;reviews;},
Abstract = {This article reviews the state of the Noise Power Standard
being drafted by Task Group No. 16 for the American
Association of Physicists in Medicine. The Standard is
intended to represent a consensus on acceptable practices in
the measurement and reporting of noise power spectra for
digital radiographic imaging devices based on single
projections and to contain informative sections which will
be of use to those not completely familiar with the
measurement and interpretation of noise power spectra.
Several of the issues considered by the committee are
reviewed, including issues of conditioning and windowing
data, issues specific to several modalities, and various
methods of data presentation. A note on the historical
background of noise power measurements and a brief
discussion of possible avenues for future research is
included.},
Doi = {10.1117/12.480451},
Key = {7788104}
}
@article{fds268602,
Author = {Dobbins, JT and Samei, E and Chotas, HG and Warp, RJ and Baydush, AH and Floyd, CE and Ravin, CE},
Title = {Chest radiography: optimization of X-ray spectrum for cesium
iodide-amorphous silicon flat-panel detector.},
Journal = {Radiology},
Volume = {226},
Number = {1},
Pages = {221-230},
Year = {2003},
Month = {January},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/12511694},
Keywords = {Cesium • Computer Simulation • Humans •
Iodides • Radiography, Thoracic • Silicon •
methods*},
Abstract = {PURPOSE: To ascertain the optimum x-ray spectrum for chest
radiography with a cesium iodide-amorphous silicon
flat-panel detector. MATERIALS AND METHODS: End points for
optimization included the ratio of tissue contrast to bone
contrast and a figure of merit (FOM) equal to the square of
the signal-to-noise ratio of tissue divided by incident
exposure to the patient. Studies were conducted with both
computer spectrum modeling and experimental measurement in
narrow-beam and full-field exposure conditions for four
tissue thicknesses (8-32 cm). Three parameters that affect
spectra were considered: the atomic number (Z) of filter
material (Z = 13, 26, 29, 42, 50, 56, 64, 74, and 82),
kilovoltage (from 50 to 150 kVp), and filter thickness (from
0.25 to 2.00 half-value layer [HVL]). RESULTS: Computer
modeling and narrow-beam experimental data showed similar
trends for the full range of parameters evaluated. Spectrum
model results showed that copper filtration at 120 kVp or
more was optimum for FOM. The ratio of contrasts showed a
trend to be higher with higher kilovoltage and only a minor
variation with filter material. Full-field experimental
results, which reflect the added contribution of x-ray
scatter, differed in magnitude but not trends from the
narrow-beam data in all cases except the ratio of contrasts
in the mediastinum. CONCLUSION: The best performance
overall, including both FOM and ratio of contrasts, was at
120 kVp with 1-HVL copper filtration (0.2 mm). With this
beam spectrum and an increase in tube output (ie,
milliampere seconds) of about 50%, a chest radiograph can be
obtained with image quality approximately equal to that with
a conventional spectrum but with about 25% less patient
exposure.},
Language = {eng},
Doi = {10.1148/radiol.2261012023},
Key = {fds268602}
}
@article{7875470,
Author = {Dobbins, J.T., III and Godfrey, D.J.},
Title = {Digital x-ray tomosynthesis: current state of the art and
clinical potential},
Journal = {Phys. Med. Biol. (UK)},
Volume = {48},
Number = {19},
Pages = {65 - 106},
Year = {2003},
url = {http://dx.doi.org/10.1088/0031-9155/48/19/R01},
Keywords = {computerised tomography;dentistry;diagnostic
radiography;mammography;medical image processing;orthopaedics;},
Abstract = {Digital x-ray tomosynthesis is a technique for producing
slice images using conventional x-ray systems. It is a
refinement of conventional geometric tomography, which has
been known since the 1930s. In conventional geometric
tomography, the x-ray tube and image receptor move in
synchrony on opposite sides of the patient to produce a
plane of structures in sharp focus at the plane containing
the fulcrum of the motion: all other structures above and
below the fulcrum plane are blurred and thus less visible in
the resulting image. Tomosynthesis improves upon
conventional geometric tomography in that it allows an
arbitrary number of in-focus planes to be generated
retrospectively from a sequence of projection radiographs
that are acquired during a single motion of the x-ray tube.
By shifting and adding these projection radiographs,
specific planes may be reconstructed. This topical review
describes the various reconstruction algorithms used to
produce tomosynthesis images. as well as approaches used to
minimize the residual blur from out-of-plane structures.
Historical background and mathematical details are given for
the various approaches described. Approaches for optimizing
the tomosynthesis image are given. Applications of
tomosynthesis to various clinical tasks. including
angiography, chest imaging, mammography, dental imaging and
orthopaedic imaging, are also described},
Key = {7875470}
}
@article{fds131725,
Author = {J.T. Dobbins},
Title = {Maidment ADA, Albert M, Bunch PC, Cunningham IA, Dobbins JT
3rd, Gagne RM, Nishikawa RM, Wagner RF, Van Metter RL.
Standardization of NPS measurement: interim report of AAPM
TG16. Proc. SPIE Medical Imaging Symposium.
2003;5030:523-532.},
Year = {2003},
Key = {fds131725}
}
@article{fds131729,
Author = {J.T. Dobbins},
Title = {Nicolas FS, Rader AE, Barber MJ, Dobbins JT 3rd. System and
method for synchronization of the acquisition of images with
the cardiac cycle for dual energy imaging. U.S. Patent #
6,643,536, 2003. Assignees: GE Medical Systems Global
Technology Company and Duke University.},
Year = {2003},
Key = {fds131729}
}
@article{fds131730,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Godfrey DJ, McAdams HP. Chest tomosynthesis.
In Advances in Digital Radiography: RSNA Categorical course
in Digital Radiography, Samei E, Flynn MJ (eds),
Radiological Society of North America, Oak Brook, Illinois,
2003.},
Year = {2003},
Key = {fds131730}
}
@article{fds131731,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Warp RJ. Dual-energy methods for tissue
discrimination in chest radiography. In Advances in Digital
Radiography: RSNA Categorical course in Digital Radiography,
Samei E, Flynn MJ (eds), Radiological Society of North
America, Oak Brook, Illinois, 2003.},
Year = {2003},
Key = {fds131731}
}
@article{fds131749,
Author = {J.T. Dobbins},
Title = {Vyborny C, Bunch P, Chotas J, Dobbins J, Niklason L,
Schaefer-Prokop C. Image quality in chest radiography.
Report #70 of the International Commission on Radiation
Units and Measurements (ICRU). Journal of the ICRU.
2003;3(2):1-176.},
Year = {2003},
Key = {fds131749}
}
@article{fds131765,
Author = {J.T. Dobbins},
Title = {Godfrey DJ, Rader A, Dobbins JT 3rd. Practical strategies
for the clinical implementation of matrix inversion
tomosynthesis. Proc. SPIE Medical Imaging Symposium.
2003;5030:379-390.},
Year = {2003},
Key = {fds131765}
}
@article{7588976,
Author = {Duryea, J. and Dobbins, J.T. and Lynch, J.A.},
Title = {Digital tomosynthesis of hand joints for arthritis
assessment},
Journal = {Med. Phys. (USA)},
Volume = {30},
Number = {3},
Pages = {325 - 33},
Year = {2003},
url = {http://dx.doi.org/10.1118/1.1543573},
Keywords = {diagnostic radiography;diseases;image reconstruction;medical
image processing;orthopaedics;},
Abstract = {The two principal forms of hand arthritis, rheumatoid
arthritis (RA) and osteoarthritis (OA) have large clinical
and economic costs. Radiography has been shown to be a
useful tool to assess the condition of the disease. A hand
radiograph, however, is a two-dimensional projection of a
three-dimensional object. In this report we present the
results of a study that applied digital tomosynthesis to
hand radiography in order to extract three-dimensional
outcome measures that should be more sensitive to arthritis
progression. The study was performed using simulated
projection radiographs created using micro computed
tomography (μCT) and a set of five dry-bone hand
skeletons. These simulated projection images were then
reconstructed into tomographic slices using the matrix
inversion tomosynthesis (MITS) algorithm. The accuracy of
the tomosynthesis reconstruction was evaluated by comparing
the reconstructed images to a gold standard created using
the μCT data. A parameter from image registration
science, normalized mutual information, provided a
quantifiable figure of merit. This study examined the
effects of source displacement, number of reconstructed
planes, number of acquisitions, noise added to the gray
scale images, and errors in the location of a fiducial
marker. We also optimized the reconstruction as a function
of two variables k and α, that controlled the mixing
of MITS with conventional shift-and-add tomosynthesis. A
study using hand delineated joint margins demonstrated that
MITS images provided a better measurement of average joint
space width. We found good agreement between the MITS slices
and the true planes. Both joint margins and trabecular
structure were visible and the reconstructed slices showed
additional structures not visible with the standard
projection image. Using hand-delineated joint margins we
compared the average joint space width of the gold standard
slices to the MITS and projection images. A root-mean square
deviation (RMSD), calculated for this comparison, gave
RMSD<sub>proj</sub>=0.18 mm and RMSD<sub>MITS</sub>=0.14 mm
for the projection and MITS images, respectively. We have
demonstrated the potential of digital tomosynthesis for
imaging of the hand to assess arthritic changes. We have
also developed a methodology that can be used to optimize
the technique and have studied the issues that will control
the feasibility of clinical implementation},
Key = {7588976}
}
@article{7579227,
Author = {Warp, R.J. and Dobbins, J.T., III},
Title = {Quantitative evaluation of noise reduction strategies in
dual-energy imaging},
Journal = {Med. Phys. (USA)},
Volume = {30},
Number = {2},
Pages = {190 - 8},
Year = {2003},
url = {http://dx.doi.org/10.1118/1.1538232},
Keywords = {algorithm theory;amorphous semiconductors;diagnostic
radiography;elemental semiconductors;medical image
processing;semiconductor device noise;silicon;silicon
radiation detectors;thin film transistors;X-ray
detection;},
Abstract = {In this paper we describe a quantitative evaluation of the
performance of three dual-energy noise reduction algorithms:
Kalender's correlated noise reduction (KCNR), noise clipping
(NOC), and edge-predictive adaptive smoothing (EPAS). These
algorithms were compared to a simple smoothing filter
approach, using the variance and noise power spectrum
measurements of the residual noise in dual-energy images
acquired with an a-Si TFT flat-panel x-ray detector. An
estimate of the true noise was made through a new method
with subpixel accuracy by subtracting an individual image
from an ensemble average image. The results indicate that in
the lung regions of the tissue image, all three algorithms
reduced the noise by similar percentages at high spatial
frequencies (KCNR=88%,NOC=88%,EPAS=84%,NOC/KCNR=88%) and
somewhat less at low spatial frequencies
(KCNR=45%,NOC=54%,EPAS=52%,NOC/KCNR=55%). At low
frequencies, the presence of edge artifacts from KCNR made
the performance worse, thus NOC or NOC combined with KCNR
performed best. At high frequencies, KCNR performed best in
the bone image, yet NOC performed best in the tissue image.
Noise reduction strategies in dual-energy imaging can be
effective and should focus on blending various algorithms
depending on anatomical locations},
Key = {7579227}
}
@article{fds331535,
Author = {Samei, E and Dobbins, JT and Chotas, HG and Baydush, AH and Floyd, CE and Ravin, CE},
Title = {Optimum radiographic technique for chest radiography using a
flat-panel digital detector},
Journal = {Radiology},
Volume = {225},
Pages = {642-643},
Publisher = {RADIOLOGICAL SOC NORTH AMERICA},
Year = {2002},
Month = {November},
Key = {fds331535}
}
@article{fds268522,
Author = {Miyamoto, I and Kobayashi, KF and Sugioka, K and Poprawe, R and Helvajian, H},
Title = {Proceedings of SPIE - The International Society for Optical
Engineering: Introduction},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {4830},
Pages = {xiii-xiv},
Year = {2002},
Month = {January},
Key = {fds268522}
}
@article{fds268599,
Author = {Floyd, CE and Warp, RJ and Dobbins, JT and Chotas, HG and Baydush, AH and Vargas-Voracek, R and Ravin, CE},
Title = {Imaging characteristics of an amorphous silicon flat-panel
detector for digital chest radiography.},
Journal = {Radiology},
Volume = {218},
Number = {3},
Pages = {683-688},
Year = {2001},
Month = {March},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11230640},
Keywords = {Evaluation Studies as Topic • Radiographic Image
Enhancement • Radiography, Thoracic •
instrumentation*},
Abstract = {PURPOSE: To evaluate the imaging characteristics of an
amorphous silicon flat-panel detector (FPD) for digital
chest radiography. MATERIALS AND METHODS: The 41 x 41-cm
digital FPD is constructed on a single monolithic glass
substrate with a structured cesium iodide scintillator layer
and an amorphous silicon thin-film transistor array for
image readout. Basic imaging characteristics of the FPD and
associated image processing system were assessed on acquired
images, including linearity, repeatability, uniformity of
response, modulation transfer function (MTF), noise power
spectrum, detective quantum efficiency (DQE), contrast
sensitivity, and scatter content. Results with the FPD
system were compared to those with a storage phosphor
computed radiography (CR) system. RESULTS: Images obtained
with the FPD demonstrated excellent uniformity,
repeatability, and linearity, as well as MTF and DQE that
were superior to those with the storage phosphor CR system.
The contrast and scatter content of images acquired with the
FPD were equivalent to those acquired with the storage
phosphor system. CONCLUSION: The FPD provides radiographic
images with excellent inherent physical image
quality.},
Language = {eng},
Doi = {10.1148/radiology.218.3.r01fe45683},
Key = {fds268599}
}
@article{7295843,
Author = {Godfrey, DJ and Warp, RJ and Dobbins, JT},
Title = {Optimization of matrix inverse tomosynthesis},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {4320},
Pages = {696-704},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1117/12.430908},
Keywords = {computerised tomography;diagnostic radiography;image
reconstruction;matrix inversion;medical image
processing;optimisation;},
Abstract = {Digital tomosynthesis is a method for reconstructing
arbitrary planes in an object from a series of projection
radiographs, acquired with limited angle tube movement.
Conventional 'shift and add' tomosynthesis suffers from the
presence of blurring artifacts, created by objects located
outside of each reconstructed plane. Matrix inversion
tomosynthesis (MITS) uses known geometry, and a set of
coupled linear algebra equations to solve for the blurring
function in each reconstructed plane, enabling removal of
the unwanted out-of-plane blur artifacts. For this paper,
both MITS and conventional tomosynthesis reconstructions
were generated for a simulated impulse located at varying
distance from the detector, and also an anthropomorphic
chest phantom. Exploration of the effects of total angular
tube movement, number of projection radiographs acquired,
and number of planes reconstructed via matrix inversion
tomosynthesis, on residual out-of-plane blur ensued. We
conclude that optimization of image acquisition and plane
reconstruction parameters can improve slice image quality.
In all examined scenarios, the MITS algorithm outperforms
conventional tomosynthesis in removing out-of-plane
blur.},
Doi = {10.1117/12.430908},
Key = {7295843}
}
@article{7295831,
Author = {Sabol, JM and Avinash, GB and Nicolas, F and Claus, B and Zhao, J and Dobbins, JT},
Title = {The development and characterization of a dual-energy
subtraction imaging system for chest radiography based on
CsI:Tl amorphous silicon flat-panel technology},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {4320},
Pages = {399-408},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1117/12.430897},
Keywords = {amorphous semiconductors;caesium compounds;diagnostic
radiography;image sensors;lung;medical image
processing;silicon;solid scintillation detectors;thallium;X-ray
detection;},
Abstract = {Dual-energy subtraction imaging increases the sensitivity
and specificity of pulmonary nodule detection in chest
radiography by reducing the contrast of overlying bone
structures. A prototype dual-energy system which enables
rapid, dual-exposure imaging of the chest using a
commercially available high-efficiency, flat-panel x-ray
detector was constructed. As such, the quality of the
clinical images generated with this prototype exceeds that
of CR techniques and demonstrates the potential for improved
detection and characterization of lung disease through
dual-energy imaging.},
Doi = {10.1117/12.430897},
Key = {7295831}
}
@article{7291234,
Author = {Samei, E and Flynn, MJ and Chotas, HG and Dobbins,
JT},
Title = {DQE of direct and indirect digital radiographic
systems},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {4320},
Pages = {189-197},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1117/12.430953},
Keywords = {biomedical equipment;diagnostic radiography;X-ray
detection;},
Abstract = {Current flat-panel detectors either directly convert x-ray
energy to electronic charge or use indirect conversion with
an intermediate optical process. The purpose of this work
was to compare direct and indirect detectors in terms of
their modulation transfer function (MTF), noise power
spectrum (NPS), and detective quantum efficiency (DQE).
Measurements were made on the three flat-panel detectors,
Philips Digital Diagnost, GE Revolution XQ/i, and Hologic
Direct-Ray DR1000 using the IEC-defined RQA5 (∼ 75 kVp, 21
mm Al) and RQA9 (∼ 120 kVp, 40 mm Al) radiographic
techniques. The presampled MTF of the systems was measured
using an edge method (Samei et al., Med Phys 25:102, 1998).
The NPS of the systems was determined for a range of
exposure levels by 2D Fourier analysis of uniformly exposed
radiographs (Flynn and Samei, Med Phys 26:1612, 1999). The
ideal signal-to-noise ratio per exposure for each system was
estimated using a semi-empirical x-ray model. The DQE,
reported only at the RQA5 technique, was assessed from the
measured MTF, NPS, exposure, and the ideal signal-to-noise
ratio. For the direct system, the MTF was found to be
significantly higher than that for the indirect systems and
very close to an ideal function associated with the detector
pixel size. The NPS for the direct system was found to be
constant in relation to frequency. The DQE results reflected
expected differences based on the absorption efficiency of
the different detector materials. Using RQA5 and 0.3 mR
exposure, the measured DQE values at spatial frequencies of
0.15 mm-1 and 2.5 mm-1 were 64% and 14% for the XQ/i system
and 35% and 19% for DR-1000. Using RQA5 and the averages at
all exposures, the corresponding values were 58% and 13% for
the XQ/i system and 36% and 19% for DR-1000.},
Doi = {10.1117/12.430953},
Key = {7291234}
}
@article{7295842,
Author = {Duryea, J and Dobbins, JT},
Title = {Application of digital tomosynthesis to hand radiography for
arthritis assessment},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {4320},
Pages = {688-695},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1117/12.430907},
Keywords = {bone;computerised tomography;diagnostic radiography;diseases;image
reconstruction;medical image processing;},
Abstract = {Joint space width (JSW) is an important arthritis outcome
measure, However, a single radiographic image is a 2D
projection of a 3D structure and diseased areas can be
obscured. To quantify the JSW in three dimensions, a
tomosynthesis algorithm was modified to provide
reconstructed slices through the bones that formed joints of
the hand. The algorithm produced tomographic slices through
the ones of the joint with minimal loss of spatial
resolution. It was also discovered that hand radiography is
ideally suited for tomosynthesis imaging due to the small
amount of scatter and lack of truncation
artifacts.},
Doi = {10.1117/12.430907},
Key = {7295842}
}
@article{fds131718,
Author = {J.T. Dobbins},
Title = {Godfrey DJ, Warp RJ, Dobbins JT 3rd. Optimization of Matrix
Inversion Tomosynthesis. Proc. SPIE Medical Imaging
Conference. 2001;4320:696-704.},
Year = {2001},
Key = {fds131718}
}
@article{fds131719,
Author = {J.T. Dobbins},
Title = {Samei EJ, Flynn MJ, Chotas HG, Dobbins JT 3rd. DQE of direct
and indirect digital radiography systems. Proc. SPIE Medical
Imaging Conference. 2001;4320:189-197.},
Year = {2001},
Key = {fds131719}
}
@article{fds131747,
Author = {J.T. Dobbins},
Title = {Duryea J, Dobbins JT 3rd. Application of digital
tomosynthesis to hand radiography for arthritis assessment.
Proc. SPIE Medical Imaging Conference. 2001;4320:688-695.},
Year = {2001},
Key = {fds131747}
}
@article{fds131748,
Author = {J.T. Dobbins},
Title = {Sabol JM, Avinash, GB, Nicolas F, Claus B, Zhao J, Dobbins
JT 3rd. Development and characterization of a dual-energy
subtraction imaging system for chest radiography based on
CsI:Tl amorphous silicon flat-panel technology. Proc. SPIE
Medical Imaging Conference. 2001;4320:399-408.},
Year = {2001},
Key = {fds131748}
}
@article{6990254,
Author = {Floyd, C.E., Jr. and Warp, R.J. and Dobbins, J.T. and Chotas, H.G. and Baydush, A.H. and Vargas-Voracek, R. and Ravin, C.E.},
Title = {Imaging characteristics of an amorphous silicon flat-panel
detector for digital chest radiography},
Journal = {Radiology (USA)},
Volume = {218},
Number = {3},
Pages = {683 - 8},
Year = {2001},
Keywords = {amorphous semiconductors;caesium compounds;diagnostic
radiography;elemental semiconductors;medical image
processing;sensitivity;silicon;silicon radiation
detectors;solid scintillation detectors;thin film
transistors;X-ray detection;},
Abstract = {Evaluates the imaging characteristics of an amorphous
silicon flat-panel detector (FPD) for digital chest
radiography. The 41×41-cm digital FPD is constructed
on a single monolithic glass substrate with a structured
cesium iodide scintillator layer and an amorphous silicon
thin-film transistor array for image readout. Basic imaging
characteristics of the FPD and associated image processing
system were assessed on acquired images, including
linearity, repeatability, uniformity of response, modulation
transfer function (MTF), noise power spectrum, detective
quantum efficiency (DQE), contrast sensitivity, and scatter
content. Results with the FPD system were compared to those
with a storage phosphor computed radiography (CR) system.
Images obtained with the FPD demonstrated excellent
uniformity, repeatability, and linearity, as well as MTF and
DQE that were superior to those with the storage phosphor CR
system. The contrast and scatter content of images acquired
with the FPD were equivalent to those acquired with the
storage phosphor system. The FPD provides radiographic
images with excellent inherent physical image
quality},
Key = {6990254}
}
@article{fds331536,
Author = {Samei, E and Flynn, MJ and Dobbins, JT and Chotas,
HG},
Title = {Comparative assessment of image quality in three flat-panel
digital radiographic systems},
Journal = {Radiology},
Volume = {221},
Pages = {462-463},
Year = {2001},
Key = {fds331536}
}
@article{6785097,
Author = {Warp, RJ and Godfrey, DJ and Dobbins, JT},
Title = {Applications of matrix inverse tomosynthesis},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {3977},
Pages = {376-383},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1117/12.384512},
Keywords = {computerised tomography;diagnostic radiography;image
restoration;matrix inversion;medical image
processing;orthopaedics;},
Abstract = {The improved image quality and characteristics of new
flat-panel x-ray detectors have renewed interest in advanced
algorithms such as tomosynthesis. Digital tomosynthesis is a
method of acquiring and reconstructing a three-dimensional
data set with limited-angle tube movement. Historically,
conventional tomosynthesis reconstruction has suffered
contamination of the planes of interest by blurred
out-of-plane structures. This paper focuses on a Matrix
Inversion Tomosynthesis (MITS) algorithm to remove unwanted
blur from adjacent planes. The algorithm uses a set of
coupled equations to solve for the blurring function in each
reconstructed plane. This paper demonstrates the use of the
MITS algorithm in three imaging applications: small animal
microscopy, chest radiography, and orthopedics. The results
of the MITS reconstruction process demonstrate an improved
reduction of blur from out-of-plane structures when compared
to conventional tomosynthesis. We conclude that the MITS
algorithm holds potential in a variety of applications to
improve three-dimensional image reconstruction.},
Doi = {10.1117/12.384512},
Key = {6785097}
}
@article{fds131717,
Author = {J.T. Dobbins},
Title = {Warp RJ, Godfrey DG, Dobbins JT 3rd. Applications of Matrix
Inverse Tomosynthesis. Proc. SPIE Medical Imaging
Conference. 2000;3977:376-383.},
Year = {2000},
Key = {fds131717}
}
@article{fds131745,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd. Image quality metrics for digital systems.
In Handbook of Medical Imaging, Vol. 1, Van Metter RL,
Beutel J, Kundel H (eds), SPIE Press, Bellingham, WA,
2000.},
Year = {2000},
Key = {fds131745}
}
@article{fds131746,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Boone JM (eds). Medical Imaging 2000:
Physics of Medical Imaging, SPIE, Bellingham, WA,
2000.},
Year = {2000},
Key = {fds131746}
}
@article{fds268603,
Author = {Chotas, HG and Dobbins, JT and Ravin, CE},
Title = {Principles of digital radiography with large-area,
electronically readable detectors: a review of the
basics.},
Journal = {Radiology},
Volume = {210},
Number = {3},
Pages = {595-599},
Year = {1999},
Month = {March},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/10207454},
Keywords = {Analog-Digital Conversion • Electronics, Medical •
Equipment Design • Humans • Image Processing,
Computer-Assisted • Light • Radiochemistry •
Radiographic Image Enhancement • Semiconductors •
Technology, Radiologic • Time Factors • X-Ray Film
• X-Rays • instrumentation • instrumentation*
• methods*},
Language = {eng},
Doi = {10.1148/radiology.210.3.r99mr15595},
Key = {fds268603}
}
@article{fds268600,
Author = {Bradford, CD and Peppler, WW and Dobbins, JT},
Title = {Performance characteristics of a Kodak computed radiography
system.},
Journal = {Medical Physics},
Volume = {26},
Number = {1},
Pages = {27-37},
Year = {1999},
Month = {January},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9949395},
Keywords = {Evaluation Studies as Topic • Fourier Analysis •
Radiographic Image Enhancement* • Radiographic Image
Interpretation, Computer-Assisted* • X-Ray Intensifying
Screens • instrumentation • methods},
Abstract = {The performance characteristics of a photostimulable
phosphor based computed radiographic (CR) system were
studied. The modulation transfer function (MTF), noise power
spectra (NPS), and detective quantum efficiency (DQE) of the
Kodak Digital Science computed radiography (CR) system
(Eastman Kodak Co.-model 400) were measured and compared to
previously published results of a Fuji based CR system
(Philips Medical Systems-PCR model 7000). To maximize
comparability, the same measurement techniques and analysis
methods were used. The DQE at four exposure levels (30, 3,
0.3, 0.03 mR) and two plate types (standard and high
resolution) were calculated from the NPS and MTF
measurements. The NPS was determined from two-dimensional
Fourier analysis of uniformly exposed plates. The
presampling MTF was determined from the Fourier transform
(FT) of the system's finely sampled line spread function
(LSF) as produced by a narrow slit. A comparison of the slit
type ("beveled edge" versus "straight edge") and its effect
on the resulting MTF measurements was also performed. The
results show that both systems are comparable in resolution
performance. The noise power studies indicated a higher
level of noise for the Kodak images (approximately 20% at
the low exposure levels and 40%-70% at higher exposure
levels). Within the clinically relevant exposure range
(0.3-3 mR), the resulting DQE for the Kodak plates ranged
between 20%-50% lower than for the corresponding Fuji
plates. Measurements of the presampling MTF with the two
slit types have shown that a correction factor can be
applied to compensate for transmission through the relief
edges.},
Language = {eng},
Doi = {10.1118/1.598781},
Key = {fds268600}
}
@article{fds131716,
Author = {J.T. Dobbins},
Title = {Boone JM, Dobbins JT 3rd (eds). Medical Imaging 1999:
Physics of Medical Imaging, SPIE, Bellingham, WA,
1999.},
Year = {1999},
Key = {fds131716}
}
@article{6281092,
Author = {Chotas, H.C. and Dobbins, J.T., III and Ravin,
C.E.},
Title = {Principles of digital radiography with large-area,
electronically readable detectors: a review of the
basics},
Journal = {Radiology (USA)},
Volume = {210},
Number = {3},
Pages = {595 - 9},
Year = {1999},
Keywords = {biomedical electronics;CCD image sensors;diagnostic
radiography;reviews;thin film transistors;X-ray
detection;},
Abstract = {In this report, the authors provide an overview of digital
electronic X-ray detectors, including two broad classes of
detectors based on thin-film transistor arrays and the
older, CCD-based designs. Computed radiographic systems
based on photostimulable storage phosphors are omitted from
this report because they do not contain integrated readout
mechanisms. The authors' goal is to provide a brief review
of the basic methods, designs, and materials used in
direct-readout radiographic systems and to emphasize
important characteristics that may affect system performance
and image quality. The advantages and disadvantages of the
different detectors, as well as the important factors that
should be considered when performing a critical analysis of
these new digital imaging systems, are discussed},
Key = {6281092}
}
@article{6132753,
Author = {Bradford, C.D. and Peppler, W.W. and Dobbins, J.T.,
III},
Title = {Performance characteristics of a Kodak computed radiography
system},
Journal = {Med. Phys. (USA)},
Volume = {26},
Number = {1},
Pages = {27 - 37},
Year = {1999},
url = {http://dx.doi.org/10.1118/1.598781},
Keywords = {biomedical equipment;diagnostic radiography;medical image
processing;phosphors;},
Abstract = {The performance characteristics of a photostimulable
phosphor based computed radiographic (CR) system were
studied. The modulation transfer function (MTF), noise power
spectra (NPS), and detective quantum efficiency (DQE) of the
Kodak Digital Science computed radiography (CR) system
(Eastman Kodak Co.-model 400) were measured and compared to
previously published results of a Fuji based CR system
(Philips Medical Systems-PCR model 7000). To maximize
comparability, the same measurement techniques and analysis
methods were used. The DQE at four exposure levels (30, 3,
0.3, 0.03 mR) and two plate types (standard and high
resolution) were calculated from the NPS and MTF
measurements. The NPS was determined from two-dimensional
Fourier analysis of uniformly exposed plates. The
presampling MTF was determined from the Fourier transform
(FT) of the system's finely sampled line spread function
(LSF) as produced by a narrow slit. A comparison of the slit
type (“beveled edge” versus “straight
edge”) and its effect on the resulting MTF
measurements was also performed. The results show that both
systems are comparable in resolution performance. The noise
power studies indicated a higher level of noise for the
Kodak images (~20% at the low exposure levels and 40%-70% at
higher exposure levels). Within the clinically relevant
exposure range (0.3-3 mR), the resulting DQE for the Kodak
plates ranged between 20%-50% lower than for the
corresponding Fuji plates. Measurements of the presampling
MTF with the two slit types have shown that a correction
factor can be applied to compensate for transmission through
the relief edges},
Key = {6132753}
}
@article{02397114234,
Author = {Dobbins, JT and Boone, JM},
Title = {Erratum: (Medical Imaging 1998 - Physics of Medical Imaging
(22-24 February 1998))},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {3336},
Pages = {838},
Address = {San Diego, CA, United States},
Editor = {Dobbins III and J.T.;Boone, J.M.;},
Year = {1998},
Month = {December},
Keywords = {Imaging systems;Image sensors;Liquid crystal displays;Thin
film transistors;Phosphors;Monochromators;Optical resolving
power;Amorphous silicon;Contrast media;Photoconducting
materials;Laser produced plasmas;Crystals;Ionization;Image
quality;Anodes;X ray diffraction;},
Abstract = {The proceedings contains 86 paper from the Conference on the
Medical Imaging 1998: Physics of Medical Imaging. Topics
discussed include: improved imaging performance of 14
× 17-in; large area x-ray image sensing using a
PbI<sub>2</sub> photoconductor; technical and clinical
results of an experimental flat dynamic (digital) x-ray
image detector (FDXD) system with real-time corrections;
diffraction spectrometer for spectral analysis of
mammographic x-ray sources; resolution properties of a
large-area quasi-monochromatic x-ray source for mammography
and monochromatic plasma x-ray generator and its
applications.},
Key = {02397114234}
}
@article{fds343280,
Author = {Dobbins, JT and Boone, JM},
Title = {Proceedings of SPIE - The International Society for Optics:
Introduction},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {3336},
Year = {1998},
Month = {December},
Key = {fds343280}
}
@article{fds131708,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Boone JM (eds). Medical Imaging 1998:
Physics of Medical Imaging, SPIE, Bellingham, WA,
1998.},
Year = {1998},
Key = {fds131708}
}
@article{fds131728,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Hames SM, Haseqawa BH, Degrado TR, Zagzebski
JA, Frayne R. Medical imaging. In Measurement,
Instrumentation and Sensors Handbook, Webster JG (ed), CRC
Press, Boca Raton, FL, 1998.},
Year = {1998},
Key = {fds131728}
}
@article{fds268604,
Author = {Althof, RJ and Wind, MG and Dobbins, JT},
Title = {A rapid and automatic image registration algorithm with
subpixel accuracy.},
Journal = {Ieee Transactions on Medical Imaging},
Volume = {16},
Number = {3},
Pages = {308-316},
Year = {1997},
Month = {June},
ISSN = {0278-0062},
url = {http://www.ncbi.nlm.nih.gov/pubmed/9184893},
Keywords = {Algorithms* • Humans • Image Processing,
Computer-Assisted* • Radiographic Image
Enhancement*},
Abstract = {A number of digital imaging techniques in medicine require
the combination of multiple images. Using these techniques,
it is essential that the images be adequately aligned and
registered prior to addition, subtraction, or any other
combination of the images. This paper describes an alignment
routine developed to register an image of a fixed object
containing a global offset error, rotation error, and
magnification error relative to a second image. The
described routine uses sparsely sampled regional correlation
in a novel way to reduce computation time and avoid the use
of markers and human interaction. The result is a fast,
robust, and automatic alignment algorithm, with accuracy
better than about 0.2 pixel in a test with clinical computed
radiography images.},
Language = {eng},
Doi = {10.1109/42.585765},
Key = {fds268604}
}
@article{5617266,
Author = {Althof, R.J. and Wind, M.G.J. and Dobbins, J.T.,
III},
Title = {A rapid and automatic image registration algorithm with
subpixel accuracy},
Journal = {IEEE Trans. Med. Imaging (USA)},
Volume = {16},
Number = {3},
Pages = {308 - 16},
Year = {1997},
url = {http://dx.doi.org/10.1109/42.585765},
Keywords = {diagnostic radiography;image registration;medical image
processing;},
Abstract = {A number of digital imaging techniques in medicine require
the combination of multiple images. Using these techniques,
it is essential that the images be adequately aligned and
registered prior to addition, subtraction, or any other
combination of the images. This paper describes an alignment
routine developed to register an image of a fixed object
containing a global offset error, rotation error, and
magnification error relative to a second image. The
described routine uses sparsely sampled regional correlation
in a novel way to reduce computation time and avoid the use
of markers and human interaction. The result is a fast,
robust, and automatic alignment algorithm, with accuracy
better than about 0.2 pixel in a test with clinical computed
radiography images},
Key = {5617266}
}
@article{fds268606,
Author = {Hinshaw, DA and Dobbins, JT},
Title = {Plate scatter correction for improved performance in
dual-energy imaging.},
Journal = {Medical Physics},
Volume = {23},
Number = {6},
Pages = {871-876},
Year = {1996},
Month = {June},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8798172},
Keywords = {Air • Biophysical Phenomena • Biophysics •
Humans • Models, Theoretical • Radiography,
Dual-Energy Scanned Projection • Scattering, Radiation
• instrumentation • methods* • statistics &
numerical data},
Abstract = {We have developed a method for correcting for the scatter
produced by the computed radiography plates in single-shot
dual-energy imaging. In our technique, which uses a series
of four computed radiography plates (the middle two plates
act as a filter), the back plate can have scatter fractions
as high as 30% due to the scatter from the first three
plates. We use the deconvolution method to correct for this
scatter, as the scatter medium is uniform and isotropic with
a constant air gap. The ratio of the modulation transfer
function (MTF) of a standard computed radiography plate to
that of a dual-energy plate gives us the correction factor
we need to scale the Fourier transforms of our images, thus
compensating for the reduced response of the system due to
scatter. We also investigated the effect of having an air
gap between the back dual-energy plate and the first three
plates. Our measurements show that this degrades the
signal-to-noise response of the back plate slightly at low
spatial frequencies. We also used independent scatter
fraction measurements to verify the validity of our MTF
measurements. Applying the correction to a back plate image
improves the fine detail contrast by approximately
30%.},
Language = {eng},
Doi = {10.1118/1.597855},
Key = {fds268606}
}
@article{95052693478,
Author = {Hinshaw, DA and Dobbins, JT},
Title = {Recent progress in noise reduction and scatter correction in
dual-energy imaging},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {2432},
Pages = {134-142},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {1995},
Month = {December},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.208330},
Keywords = {Spurious signal noise;Scattering;Medical imaging;Image
quality;},
Abstract = {We report on several new techniques which we are developing
for scatter correction and noise suppression in single-shot
dual-energy chest radiography. For scatter, we use a
deconvolution technique to correct for the scatter produced
within the dual-energy cassette, which can result in scatter
fractions as high as 30% in the high-energy image. For
patient scatter, we have developed a technique which
estimates the scatter by viewing each pixel in the image as
a scattering source, and summing up its scatter contribution
over all pixels. For scatter suppression, we describe the
methods of noise clipping and noise forcing, both which use
information from the low- and high-energy images to correct
pixel values in the high-energy image which are unphysical.
The noise clipping can also be combined with the correlated
noise reduction technique, in order to combine the strengths
of the two methods.},
Doi = {10.1117/12.208330},
Key = {95052693478}
}
@article{fds268596,
Author = {Dobbins, JT and Ergun, DL and Rutz, L and Hinshaw, DA and Blume, H and Clark, DC},
Title = {DQE(f) of four generations of computed radiography
acquisition devices.},
Journal = {Medical Physics},
Volume = {22},
Number = {10},
Pages = {1581-1593},
Year = {1995},
Month = {October},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8551982},
Keywords = {Humans • Mathematics • Radiographic Image
Interpretation, Computer-Assisted • Radiography,
Thoracic • Reproducibility of Results •
instrumentation* • methods*},
Abstract = {Measurements were made of the MTF(f), NPS(f), and DQE(f) of
four generations of computed radiography (CR) imaging plates
and three generations of CR image readers. The MTF generally
showed only a minor change between generations of plates and
readers, but the DQE(f) has improved substantially from a
very early plate/reader combination to a more recent one.
The DQE in the more recent plate/reader combination is 1.3X
greater at low frequencies and about 3X greater at high
frequencies than the much earlier versions. Thus there has
been substantial improvement in the imaging performance
obtainable with CR since some of the early observer studies
which indicated poorer performance with CR than with
screen-film.},
Language = {eng},
Doi = {10.1118/1.597627},
Key = {fds268596}
}
@article{fds268601,
Author = {Dobbins, JT},
Title = {Effects of undersampling on the proper interpretation of
modulation transfer function, noise power spectra, and noise
equivalent quanta of digital imaging systems.},
Journal = {Medical Physics},
Volume = {22},
Number = {2},
Pages = {171-181},
Year = {1995},
Month = {February},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/7565348},
Keywords = {Fourier Analysis • Humans • Mathematics •
Models, Theoretical* • Quantum Theory •
Radiography • instrumentation • methods* •
standards*},
Abstract = {The proper understanding of modulation transfer function
(MTF), noise power spectra (NPS), and noise equivalent
quanta (NEQ) in digital systems is significantly hampered
when the systems are undersampled. Undersampling leads to
three significant complications: (1) MTF and NPS do not
behave as transfer amplitude and variance, respectively, of
a single sinusoid, (2) the response of a digital system to a
delta function is not spatially invariant and therefore does
not fulfill certain technical requirements of classical
analysis, and (3) NEQ loses its common meaning as maximum
available SNR2 (signal-to-noise) at a particular frequency.
These three complications cause the comparisons of MTF and
NEQ between undersampled digital systems to depend on the
frequency content of the images being evaluated. A tutorial
of MTF, NPS, and NEQ concepts for digital systems is
presented, along with a complete theoretical treatment of
the above-mentioned complications from undersampling.},
Language = {eng},
Doi = {10.1118/1.597600},
Key = {fds268601}
}
@article{5129122,
Author = {Dobbins, J.T., III and Ergunb, D.L. and Rutz, L. and Hinshaw, D.A. and Blume, H. and Clark, D.C.},
Title = {DQE(f) of four generations of computed radiography
acquisition devices},
Journal = {Med. Phys. (USA)},
Volume = {22},
Number = {10},
Pages = {1581 - 93},
Year = {1995},
url = {http://dx.doi.org/10.1118/1.597627},
Keywords = {biomedical equipment;data acquisition;diagnostic
radiography;},
Abstract = {Measurements were made of the MTF(f), NPS(f), and DQE(f) of
four generations of computed radiography (CR) imaging plates
and three generations of CR image readers. The MTF generally
showed only a minor change between generations of plates and
readers, but the DQE(f) has improved substantially from a
very early plate/reader combination to a more recent one.
The DQE in the more recent plate/reader combination is
1.3× greater at low frequencies and about 3×.
Greater at high frequencies than the much earlier versions.
Thus there has been substantial improvement in the imaging
performance obtainable with CR since some of the early
observer studies which indicated poorer performance with CR
than with screen-film},
Key = {5129122}
}
@article{fds131707,
Author = {J.T. Dobbins},
Title = {Hinshaw DA, Dobbins JT 3rd. Recent progress in noise
reduction and scatter correction in dual-energy imaging.
Proc. SPIE Medical Imaging Conference. 1995
Feb;2432:134-142.},
Year = {1995},
Key = {fds131707}
}
@article{4921239,
Author = {Dobbins, J.T., III},
Title = {Effects of undersampling on the proper interpretation of
modulation transfer function, noise power spectra, and noise
equivalent quanta of digital imaging systems},
Journal = {Med. Phys. (USA)},
Volume = {22},
Number = {2},
Pages = {171 - 81},
Year = {1995},
url = {http://dx.doi.org/10.1118/1.597600},
Keywords = {diagnostic radiography;digital systems;noise;},
Abstract = {The proper understanding of modulation transfer function
(MTF), noise power spectra (NPS), and noise equivalent
quanta (NEQ) in digital systems is significantly hampered
when the systems are undersampled. Undersampling leads to
three significant complications: (1) MTF and NPS do not
behave as transfer amplitude and variance, respectively, of
a single sinusoid, (2) the response of a digital system to a
delta function is not spatially invariant and therefore does
not fulfill certain technical requirements of classical
analysis, and (3) NEQ loses its common meaning as maximum
available SNR<sup>2</sup> (signal-to-noise) at a particular
frequency. These three complications cause the comparisons
of MTF and NEQ between undersampled digital systems to
depend on the frequency content of the images being
evaluated. A tutorial of MTF, NPS, and NEQ concepts for
digital systems is presented, along with a complete
theoretical treatment of the above-mentioned complications
from undersampling},
Key = {4921239}
}
@article{fds347608,
Author = {Ergun, DL and Peppler, WW and Dobbins, JT and Zink, FE and Kruger, DG and Kelcz, F and De Bruijn and FJ and Bellers, EW and Wang, Y and Althof, RJ and Wind, MGJ},
Title = {Dual-energy computed radiography: Improvements in
processing},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {2167},
Pages = {663-671},
Year = {1994},
Month = {May},
url = {http://dx.doi.org/10.1117/12.175102},
Abstract = {We have reported on a single-exposure dual-energy system
based on computed radiography (CR) technology. In a clinical
study conducted over a two year period, the dual-energy
system proved to be highly successful in improving the
detection (p=0.0005) and characterization (p=0.005) of
pulmonary nodules when compared to conventional screen-film
radiography. The basic components of our dual-energy
detector system include source filtration with gadolinium to
produce a bi-modal x-ray spectrum and a cassette containing
four CR imaging plates. The front and back plates record the
low-energy and high-energy images, respectively, and the
middle two plates serve as an intermediate filter. Since our
initial report, a number of improvements have been made to
make the system more practical. An automatic registration
algorithm based on image features has been developed to
align the front and back image plates. There have been two
improvements in scatter correction: A simple correction is
now made to account for scatter within the multiplate
detector; and a correction algorithm is applied to account
for scatter variations between patients. An improved basis
material decomposition (BMD) algorithm has been developed to
facilitate automatic operation of the algorithm. Finally,
two new noise suppression techniques are under
investigation: one adjusts the noise filtering parameters
depending on the strength of edge signals in the detected
image in order to greatly reduce quantum mottle while
minimizing the introduction of artifacts; a second routine
uses knowledge of the region of valid low-energy and
highenergy image data to suppress noise with minimal
introduction of artifacts. This paper is a synthesis of
recent work aimed at improving the performance of
dual-energy CR conducted at three institutions: Philips
Medical Systems, the University of Wisconsin, and Duke
University.},
Doi = {10.1117/12.175102},
Key = {fds347608}
}
@article{fds131764,
Author = {J.T. Dobbins},
Title = {Ergun DL, Peppler WW, Dobbins JT 3rd, Zink FE, Kruger DG,
Kelcz F, de Bruijn FJ, Bellers EW, Wang Y, Althof RJ, Wind
MGJ. Dual-energy computed radiography: improvements in
processing. Proc. SPIE Medical Imaging Conference. 1994
Feb;2167:663-671.},
Year = {1994},
Key = {fds131764}
}
@article{fds268519,
Author = {Chotas, HG and Floyd, CE and Dobbins, JT and Ravin,
CE},
Title = {Dr Chotas and colleagues respond},
Journal = {Radiology},
Volume = {189},
Number = {1},
Pages = {290-290},
Publisher = {Radiological Society of North America (RSNA)},
Year = {1993},
Month = {October},
ISSN = {0033-8419},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1993LY02300064&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Doi = {10.1148/radiology.189.1.290-a},
Key = {fds268519}
}
@article{fds268592,
Author = {Dobbins, JT and Rice, JJ and Goodman, PC and Patz, EF and Ravin,
CE},
Title = {Variable compensation chest radiography performed with a
computed radiography system: design considerations and
initial clinical experience.},
Journal = {Radiology},
Volume = {187},
Number = {1},
Pages = {55-63},
Year = {1993},
Month = {April},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8451437},
Keywords = {Aged • Humans • Male • Middle Aged •
Radiographic Image Enhancement • Radiography, Thoracic
• Technology, Radiologic • Tomography, X-Ray
Computed • instrumentation • methods*},
Abstract = {The authors describe a variable compensation (VC) technique
in which an x-ray equalizer and a computed radiography
system are used. The VC technique allows retrospective
alteration of equalized chest appearance with maintenance of
improved signal-to-noise ratio in dense regions. Two imaging
plates are used: one upstream of the patient to record the
incident beam profile and one down-stream to record the
equalized image. Subtraction of a weighted version of the
upstream image from the down-stream image permits alteration
of the appearance of the VC image, from the extremes of
stimulated-unequalized to highly equalized. VC image
appearance was optimized with a real-time workstation. The
quality of VC images obtained in 33 patients was evaluated
by three chest radiologists. Mediastinal appearance was
better on VC equalized images than on conventional
screen-film images. The stimulation of the appearance of a
conventional radiograph with VC proved useful in
interpretation of lung appearances on equalized
radiographs.},
Language = {eng},
Doi = {10.1148/radiology.187.1.8451437},
Key = {fds268592}
}
@article{fds268597,
Author = {Chotas, HG and Floyd, CE and Dobbins, JT and Ravin,
CE},
Title = {Digital chest radiography with photostimulable storage
phosphors: signal-to-noise ratio as a function of
kilovoltage with matched exposure risk.},
Journal = {Radiology},
Volume = {186},
Number = {2},
Pages = {395-398},
Year = {1993},
Month = {February},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/8421741},
Keywords = {Electricity* • Humans • Maximum Allowable
Concentration • Radiographic Image Enhancement* •
Radiography, Thoracic • X-Ray Intensifying Screens*
• methods*},
Abstract = {A photostimulable storage phosphor (PSP) digital radiography
system was evaluated regarding the signal-to-noise ratio
(S/N) on chest images acquired at differing peak kilovoltage
settings but with matched risk from radiation exposure.
Images of two chest phantoms were acquired by using bedside
(portable) imaging equipment at tube voltages ranging from
60 to 120 kV. Exposure factors were set so that the
effective dose equivalent, a risk estimator weighted for
various organs, was approximately equal in all exposures.
The S/N in the lung-equivalent regions was found to be
slightly higher (maximum, 15%) in the low-energy exposures,
while the S/N values in the mediastinum- and
subdiaphragm-equivalent regions were approximately equal at
all kilovoltage settings. The absence of a high sensitivity
of S/N to kilovoltage in risk-matched PSP images should
enable institutions to select x-ray beam quality on the
basis of other imaging criteria.},
Language = {eng},
Doi = {10.1148/radiology.186.2.8421741},
Key = {fds268597}
}
@article{4482357,
Author = {Dobbins, J.T., III and Rice, J.J. and Goodman, P.C. and Patz, E.F., Jr. and Ravin, C.E.},
Title = {Variable compensation chest radiography performed with a
computed radiography system: design considerations and
initial clinical experience},
Journal = {Radiology (USA)},
Volume = {187},
Number = {1},
Pages = {55 - 63},
Year = {1993},
Keywords = {diagnostic radiography;lung;},
Abstract = {The authors describe a variable compensation (VC) technique
in which an X-ray equalizer and a computed radiography
system are used. The VC technique allows retrospective
alteration of equalized chest appearance with maintenance of
improved signal-to-noise ratio in dense regions. Two imaging
plates are used: one upstream of the patient to record the
incident beam profile and one downstream to record the
equalized image. Subtraction of a weighted version of the
upstream image from the downstream image permits alteration
of the appearance of the VC image, from the extremes of
simulated-unequalized to highly equalized. VC image
appearance was optimized with a real-time workstation. The
quality of VC images obtained in 33 patients was evaluated
by three chest radiologists. Mediastinal appearance was
better on VC equalized images than on conventional
screen-film images. The simulation of the appearance of a
conventional radiograph with VC proved useful in
interpretation of lung appearances on equalized
radiographs},
Key = {4482357}
}
@article{4402611,
Author = {Chotas, H.G. and Floyd, C.E., Jr. and Dobbins, J.T., III and Ravin, C.E.},
Title = {Digital chest radiography with photostimulable storage
phosphors: signal-to-noise ratio as a function of
kilovoltage with matched exposure risk},
Journal = {Radiology (USA)},
Volume = {186},
Number = {2},
Pages = {395 - 8},
Year = {1993},
Keywords = {diagnostic radiography;phosphors;},
Abstract = {A photostimulable storage phosphor (PSP) digital radiography
system was evaluated regarding the signal-to-noise ratio
(S/N) on chest images acquired at differing peak kilovoltage
settings but with matched risk from radiation exposure.
Images of two chest phantoms were acquired by using bedside
(portable) imaging equipment at tube voltages ranging from
60 to 120 kV. Exposure factors were set so that the
effective dose equivalent, a risk estimator weighted for
various organs, was approximately equal in all exposures.
The S/N in the lung-equivalent regions was found to be
slightly higher (maximum, 15%) in the low-energy exposures,
while the S/N values in the mediastinum-m and
subdiaphragm-equivalent regions were approximately equal at
all kilovoltage settings. The absence of a high sensitivity
of S/N to kilovoltage in risk-matched PSP images should
enable institutions to select X-ray beam quality on the
basis of other imaging criteria},
Key = {4402611}
}
@article{fds268605,
Author = {Dobbins, JT and Chotas, HG and Benveniste, H},
Title = {Direct digitization of optical images using a
photostimulable phosphor system.},
Journal = {Medical Physics},
Volume = {19},
Number = {4},
Pages = {1071-1080},
Year = {1992},
Month = {July},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1518470},
Keywords = {Humans • Image Processing, Computer-Assisted •
Luminescent Measurements • Metals, Rare Earth •
Radiographic Image Enhancement • methods*},
Abstract = {The authors describe a method for directly digitizing
optical images with a photostimulable phosphor (PSP) system.
A PSP plate is initially charged with an exposure to a
uniform x-ray field, and is then exposed to an optical image
which discharges the plate in relation to the amount of
incident light. Two applications were investigated: a
contact-print technique for digitizing film radiographs, and
a projection technique for digitizing transparent objects
such as histology slides. Spatial uniformity was found to be
adequate, and linearity of optical density response was
excellent from 0.0-2.9 o.d. after look-up table correction.
Spatial frequency response was degraded with the optical
technique relative to the x-ray imaging properties of the
plates, but was restorable by Fourier filtering. Image noise
following spatial enhancement was satisfactory at
intermediate to high optical densities using a
high-resolution PSP plate, but was somewhat degraded at low
densities.},
Language = {eng},
Doi = {10.1118/1.596917},
Key = {fds268605}
}
@article{fds268591,
Author = {Dobbins, JT and Rice, JJ and Beam, CA and Ravin, CE},
Title = {Threshold perception performance with computed and
screen-film radiography: implications for chest
radiography.},
Journal = {Radiology},
Volume = {183},
Number = {1},
Pages = {179-187},
Year = {1992},
Month = {April},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/1549669},
Keywords = {Humans • Models, Structural • Observer Variation
• Radiographic Image Enhancement* • Radiography,
Thoracic* • X-Ray Intensifying Screens*},
Abstract = {Images of a phantom obtained with computed radiography and
standard screen-film imaging were compared to evaluate
observer threshold perception performance with a modified
contrast-detail technique. Optimum exposure necessary for
performance with the imaging plate technique to match that
with screen-film techniques was determined, as was
comparative performance with variation in kilovoltages,
plate type, spatial enhancement, and hard-copy interpolation
method. It was found that computed radiography necessitates
about 75%-100% more exposure than screen-film radiography to
optimally match performance with Ortho-C film with Lanex
regular or medium screens (Eastman Kodak, Rochester, NY) for
detection of objects 0.05-2.0 cm in diameter. However, only
minimal loss of detection performance (approximately 10%
overall) was experienced if standard screen-film exposures
were used with computed radiography. Little change in
observer performance was found with variation in plate type,
spatial enhancement, or method of hard-copy interpolation.
However, perception performance with computed radiographic
images was better at lower kilovoltages.},
Language = {eng},
Doi = {10.1148/radiology.183.1.1549669},
Key = {fds268591}
}
@article{fds131727,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd. Variable compensation method and apparatus
for radiological images (continuation in part). U.S. Patent
#5,081,659. January, 1992. Assignee: Duke
University.},
Year = {1992},
Key = {fds131727}
}
@article{4278454,
Author = {Dobbins, J.T., III and Chotas, H.G. and Benvensite,
H.},
Title = {Direct digitization of optical images using a
photostimulable phosphor system},
Journal = {Med. Phys. (USA)},
Volume = {19},
Number = {4},
Pages = {1071 - 80},
Year = {1992},
url = {http://dx.doi.org/10.1118/1.596917},
Keywords = {biomedical equipment;diagnostic radiography;optical
images;},
Abstract = {The authors describe a method for directly digitizing
optical images with a photostimulable phosphor (PSP) system.
A PSP plate is initially charged with an exposure to a
uniform X-ray field, and is then exposed to an optical image
which discharges the plate in relation to the amount of
incident light. Two applications were investigated: a
contact-print technique for digitizing film radiographs, and
a projection technique for digitizing transparent objects
such as histology slides. Spatial uniformity was found to be
adequate, and linearity of optical density response was
excellent from 0.0-2.9 o.d. after look-up table correction.
Spatial frequency response was degraded with the optical
technique relative to the X-ray imaging properties of the
plates, but was restorable by Fourier filtering. Image noise
following spatial enhancement was satisfactory at
intermediate to high optical densities using a
high-resolution PSP plate, but was somewhat degraded at low
densities},
Key = {4278454}
}
@article{4253350,
Author = {Dobbins, J.T., III and Rice, J.J. and Beam, C.A. and Ravin,
C.E.},
Title = {Threshold perception performance with computed and
screen-film radiography: implications for chest
radiography},
Journal = {Radiology (USA)},
Volume = {183},
Number = {1},
Pages = {179 - 87},
Year = {1992},
Keywords = {diagnostic radiography;visual perception;},
Abstract = {Images of a phantom obtained with computed radiography and
standard screen-film imaging were compared to evaluate
observer threshold perception performance with a modified
contrast-detail technique. Optimum exposure necessary for
performance with the imaging plate technique to match that
with screen-film techniques was determined, as was
comparative performance with variation in kilovoltages,
plate type, spatial enhancement, and hard-copy interpolation
method. It was found that computed radiography necessitates
about 75%-100% more exposure than screen-film radiography to
optimally match performance with Ortho-C film with Lanex
regular or medium screens (Eastman Kodak, Rochester, NY) for
detection of objects 0.05-20 cm in diameter. However, only
minimal loss of detection performance (~10% overall) was
experienced if standard screen-film exposures were used with
computed radiography. Little change in observer performance
was found with variation in plate type, spatial enhancement,
or method of hard-copy interpolation. However, perception
performance with computed radiographic images was better at
lower kilovoltages},
Key = {4253350}
}
@article{fds268590,
Author = {Chotas, HG and Dobbins, JT and Floyd, CE and Ravin,
CE},
Title = {Single-exposure conventional and computed radiography image
acquisition.},
Journal = {Investigative Radiology},
Volume = {26},
Number = {5},
Pages = {438-445},
Year = {1991},
Month = {May},
ISSN = {0020-9996},
url = {http://www.ncbi.nlm.nih.gov/pubmed/2055742},
Keywords = {Humans • Radiographic Image Enhancement •
Technology, Radiologic • X-Ray Intensifying Screens*
• methods*},
Abstract = {A technique for simultaneously acquiring a conventional
film-screen radiographic image and a digital computed
radiography (CR) image with a single x-ray exposure is
described. Measurements of image contrast, spatial
resolution, and signal-to-noise ratios demonstrate that a
modified film cassette in which the first intensifier screen
has been replaced with a CR imaging plate permits
dual-image, single-exposure imaging with only nominal
degradation in film and CR image quality relative to the two
standard image counterparts. This technique may be used to
acquire matched image pairs for research or as a way to
provide full-size conventional film images in the clinical
environment, while retaining the advantages offered by
computed radiography systems.},
Language = {eng},
Doi = {10.1097/00004424-199105000-00011},
Key = {fds268590}
}
@article{fds268609,
Author = {Chotas, HG and Floyd, CE and Dobbins, JT and Lo, JY and Ravin,
CE},
Title = {Scatter fractions in AMBER imaging.},
Journal = {Radiology},
Volume = {177},
Number = {3},
Pages = {879-880},
Year = {1990},
Month = {December},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/2244003},
Keywords = {Radiography, Thoracic* • Scattering, Radiation* •
Technology, Radiologic*},
Abstract = {Images of two phantoms were obtained with use of an advanced
multiple-beam equalization radiography system, and scatter
fractions were estimated with use of a photostimulable
phosphor imaging system. Scatter fractions in the equalized
images were lower in the mediastinum-equivalent areas and
higher in the lung-equivalent areas, relative to images that
were conventionally acquired with use of an antiscatter
grid. The differences are attributed to a reduction in
incident exposure in the lungs and the presence of
cross-scatter between lung and mediastinal
regions.},
Language = {eng},
Doi = {10.1148/radiology.177.3.2244003},
Key = {fds268609}
}
@article{3896171,
Author = {Chotas, H.G. and Floyd, C.E., Jr. and Dobbins, J.T., III and Lo, J.Y. and Ravin, C.E.},
Title = {Scatter fractions in AMBER imaging},
Journal = {Radiology (USA)},
Volume = {177},
Number = {3},
Pages = {879 - 80},
Year = {1990},
Keywords = {diagnostic radiography;X-ray scattering;},
Abstract = {Images of two phantoms were obtained with use of an advanced
multiple-beam equalization radiography system, and scatter
fractions were estimated with use of a photostimulable
phosphor imaging system. Scatter fractions in the equalized
images were lower in the mediastinum-equivalent areas and
higher in the lung-equivalent areas relative to images that
were conventionally acquired with use of an antiscatter
grid. The differences are attributed to a reduction in
incident exposure in the lungs and the presence of cross
scatter between lung and mediastinal regions},
Key = {3896171}
}
@article{fds131768,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd. Matrix Inversion Tomosynthesis improvements
in longitudinal x-ray slice imaging. U.S. Patent #4,903,204,
1990. Assignee: Duke University.},
Year = {1990},
Key = {fds131768}
}
@article{3714521,
Author = {Floyd, C.E., Jr. and Chotas, H.G. and Dobbins, J.T., III and Ravin, C.E.},
Title = {Quantitative radiographic imaging using a photostimulable
phosphor system},
Journal = {Med. Phys. (USA)},
Volume = {17},
Number = {3},
Pages = {454 - 9},
Year = {1990},
url = {http://dx.doi.org/10.1118/1.596569},
Keywords = {biomedical equipment;diagnostic radiography;phosphors;},
Abstract = {The authors have evaluated a photostimulable phosphor X-ray
imaging system [Philips Computed Radiography (PCR) system]
for use in quantification of X-ray exposure in diagnostic
radiography. An exponential function was fitted to a data
yielding quantitative X-ray exposure values as a function of
digital pixel values. The authors investigated several
factors that affect the accuracy of exposure measurement
using the PCR including repeatability, background noise as a
function of time delay between plate erasure and use,
sensitivity variation between different plates,
nonuniformity of sensitivity within a plate, decay of the
latent image between time of exposure and readout (observed
as a change in sensitivity), and the accuracy with which the
(exponential) calibration function yields exposure values as
a function of digital pixel values. The calibration was
performed over the exposure range from 5.1×10<sup>-9</sup>
to 2.0×10<sup>-5</sup> C/kg (0.02-75 mR). The accuracy
of exposure measurements made with a single imaging plate is
between 1.6% and 4.2%. If measurements from several plates
are involved, the uncertainty in the final measurements from
several plates are involved, the uncertainty in the final
measurement will be between 5% and 5.9%},
Key = {3714521}
}
@article{fds268589,
Author = {Floyd, CE and Chotas, HG and Dobbins, JT and Ravin,
CE},
Title = {Quantitative radiographic imaging using a photostimulable
phosphor system.},
Journal = {Medical Physics},
Volume = {17},
Number = {3},
Pages = {454-459},
Year = {1990},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/2385203},
Keywords = {Evaluation Studies as Topic • Humans • Luminescent
Measurements • Radiation Dosage* • Radiography
• instrumentation* • standards},
Abstract = {We have evaluated a photostimulable phosphor x-ray imaging
system [Philips Computed Radiography (PCR) system] for use
in quantification of x-ray exposure in diagnostic
radiography. An exponential function was fitted to data
yielding quantitative x-ray exposure values as a function of
digital pixel values. We investigated several factors that
affect the accuracy of exposure measurement using the PCR
including repeatability, background noise as a function of
time delay between plate erasure and use, sensitivity
variation between different plates, nonuniformity of
sensitivity within a plate, decay of the latent image
between time of exposure and readout (observed as a change
in sensitivity), and the accuracy with which the
(exponential) calibration function yields exposure values as
a function of digital pixel values. The calibration was
performed over the exposure range from 5.1 X 10(-9) to 2.0 X
10(-5) C/kg (0.02-75 mR). The accuracy of exposure
measurements made with a single imaging plate is between
1.6% and 4.2%. If measurements from several plates are
involved, the uncertainty in the final measurement will be
between 5% and 5.9%.},
Language = {eng},
Doi = {10.1118/1.596569},
Key = {fds268589}
}
@article{fds268594,
Author = {Dobbins, JT and Powell, AO},
Title = {Variable compensation technique for digital radiography of
the chest.},
Journal = {Radiology},
Volume = {173},
Number = {2},
Pages = {451-458},
Year = {1989},
Month = {November},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/2798877},
Keywords = {Humans • Mediastinum • Models, Structural •
Radiographic Image Enhancement • Radiography, Thoracic
• methods* • radiography},
Abstract = {The authors describe a new technique, variable compensation
(VC) radiography, for digital radiography of the chest. It
permits retrospective adjustment of image display while
maintaining improved mediastinal signal-to-noise ratio (S/N)
from aggressive x-ray equalization. A fraction of a
logarithmic image representing the profile of the beam
intensity incident on the patient is subtracted from a
logarithmic equalized image. VC images of a chest phantom
were generated with various weightings of the beam-profile
image. Edge artifacts were substantially reduced with a
weighting of greater than 0.5 and eliminated with a
weighting of 1.0. The S/N properties of VC images were
measured with a series of plastic squares placed over
various regions of the chest phantom. The S/N of the squares
in the dense sub-diaphragm were improved twofold compared
with the S/N on unequalized radiographs, whereas the S/N in
the lung was reduced by 30%. Studies of a volunteer revealed
the ability to render images with aggressive equalization
(for improved mediastinal visualization) and images with the
appearance of traditional chest radiographs.},
Language = {eng},
Doi = {10.1148/radiology.173.2.2798877},
Key = {fds268594}
}
@article{3566251,
Author = {Dobbins, J.T., III and Powell, A.O.},
Title = {Variable compensation technique for digital radiography of
the chest},
Journal = {Radiology (USA)},
Volume = {173},
Number = {2},
Pages = {451 - 8},
Year = {1989},
Keywords = {diagnostic radiography;},
Abstract = {Describes a new technique, variable compensation (VC)
radiography, for digital radiography of the chest. It
permits retrospective adjustment of image display while
maintaining improved mediastinal signal-to-noise ratio (S/N)
from aggressive X-ray equalization. A fraction of a
logarithmic image representing the profile of the beam
intensity incident on the patient is subtracted from a
logarithmic equalized image. VC images of a chest phantom
were generated with various weightings of the beam-profile
image. Edge artifacts were substantially reduced with a
weighting of greater than 0.5 and eliminated with a
weighting of 1.0. The S/N properties of VC images were
measured with a series of plastic squares placed over
various regions of the chest phantom. The S/N of the squares
in the dense subdiaphragm were improved twofold compared
with the S/N on unequalized radiographs, whereas the S/N in
the lung was reduced by 30%},
Key = {3566251}
}
@article{fds131726,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd. Variable Compensation method and apparatus
for radiological images. U.S. Patent #4,868,857, Sept. 1989.
Assignee: Duke University.},
Year = {1989},
Key = {fds131726}
}
@article{fds131724,
Author = {J.T. Dobbins},
Title = {Sorenson JA, Dobbins JT 3rd. Techniques for chest
radiography. Proc. Chest Imaging Conference 1987, WW Peppler
and AA Alter (eds.), pp. 1-15, 1987.},
Year = {1987},
Key = {fds131724}
}
@article{fds131763,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Powell AO. Characterization of variable
compensation radiography of the chest. Proc. Chest Imaging
Conference 1987, WW Peppler and AA Alter (eds.), pp.
144-154, 1987.},
Year = {1987},
Key = {fds131763}
}
@article{2995879,
Author = {Hasegawa, B.H. and Dobbins, J.T., III. and Naimuddin, S. and Peppler, W.W. and Mistretta, C.A.},
Title = {Geometrical properties of a digital beam attenuator
system},
Journal = {Med. Phys. (USA)},
Volume = {14},
Number = {3},
Pages = {314 - 21},
Year = {1987},
url = {http://dx.doi.org/10.1118/1.596086},
Keywords = {diagnostic radiography;},
Abstract = {A digital beam attenuator system has been developed to
automatically generate patient-specific compensating filters
for chest radiography. An initial low-dose test image is
used to generate the attenuator, which is fabricated by
overprinting multiple layers of a heavy-metal material onto
a nonattenuating substrate. The attenuator is subsequently
inserted into the X-ray beam for a final compensated
radiograph. The effects of focal spot blurring and limited
attenuator resolution result in the final compensated image
containing only high-spatial frequency information. The
frequency response of the process is not strictly
describable by a modulation transfer function, but an
approximation of the frequencies remaining in the
compensated image is obtained for low-contrast conditions.
It is found that a 4×4 blurring function on the
original 64×64 test image is required for the
attenuator to give appropriate compensated image appearance.
A proposed attenuator printing scheme prints the attenuator
in a 16×16 matrix, staggering successively printed
layers to achieve the required 64×64 sampling with
appropriate blurring. The resulting compensated image has
good anatomical definition and contains a frequency response
similar to that obtained by compensation techniques being
investigated by Plewes and Sorenson},
Key = {2995879}
}
@article{fds268607,
Author = {Hasegawa, BH and Dobbins, JT and Naimuddin, S and Peppler, WW and Mistretta, CA},
Title = {Geometrical properties of a digital beam attenuator
system.},
Journal = {Medical Physics},
Volume = {14},
Number = {3},
Pages = {314-321},
Year = {1987},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/3600518},
Keywords = {Humans • Models, Anatomic • Radiography, Thoracic
• instrumentation • methods*},
Abstract = {A digital beam attenuator system has been developed to
automatically generate patient-specific compensating filters
for chest radiography. An initial low-dose test image is
used to generate the attenuator, which is fabricated by
overprinting multiple layers of a heavy-metal material onto
a nonattenuating substrate. The attenuator is subsequently
inserted into the x-ray beam for a final compensated
radiograph. The effects of focal spot blurring and limited
attenuator resolution result in the final compensated image
containing only high-spatial frequency information. The
frequency response of the process is not strictly
describable by a modulation transfer function, but an
approximation of the frequencies remaining in the
compensated image is obtained for low-contrast conditions.
It is found that a 4 X 4 blurring function on the original
64 X 64 test image is required for the attenuator to give
appropriate compensated image appearance. A proposed
attenuator printing scheme prints the attenuator in a 16 X
16 matrix, staggering successively printed layers to achieve
the required 64 X 64 sampling with appropriate blurring. The
resulting compensated image has good anatomical definition
and contains a frequency response similar to that obtained
by compensation techniques being investigated by Plewes and
Sorenson.},
Language = {eng},
Doi = {10.1118/1.596086},
Key = {fds268607}
}
@article{fds268595,
Author = {Hasegawa, BH and Naimuddin, S and Dobbins, JT and Mistretta, CA and Peppler, WW and Hangiandreou, NJ and Cusma, JT and McDermott, JC and Kudva, BV and Melbye, KM},
Title = {Digital beam attenuator technique for compensated chest
radiography.},
Journal = {Radiology},
Volume = {159},
Number = {2},
Pages = {537-543},
Year = {1986},
Month = {May},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/3961188},
Keywords = {Humans • Male • Models, Structural •
Radiographic Image Enhancement • Radiography, Thoracic
• methods*},
Abstract = {The feasibility of producing patient-specific beam
attenuators for chest radiography has been investigated
using an anthropomorphic phantom and a human volunteer. A
low-dose test exposure is digitized, processed, and used to
print a small cerium filter, which is placed in the x-ray
beam near the collimator. The final radiograph is recorded
on film. The technique results in relatively uniform film
exposure, so that structures in all regions of the chest are
simultaneously displayed with optimal film contrast. The
equalized exposure improves image quality in the normally
underpenetrated regions and reduces the role of
cross-scatter from the lungs. The image is analogous to
optical or computer-processed unsharp masking techniques,
but the processing is accomplished in the x-ray beam and
results in an improved exposure distribution, giving
advantages that cannot be achieved with image processing
techniques alone.},
Language = {eng},
Doi = {10.1148/radiology.159.2.3961188},
Key = {fds268595}
}
@article{2749911,
Author = {Hasegawa, B.H. and Naimuddin, S. and Dobbins, J.T., III and Mistretta, C.A. and Peppler, W.W. and Hangiandreou, N.J. and Cusma, J.T. and McDermott, J.C. and Kudva, B.V. and Melbye,
K.M.},
Title = {Digital beam attenuator technique for compensated chest
radiography},
Journal = {Radiology (USA)},
Volume = {159},
Number = {2},
Pages = {537 - 43},
Year = {1986},
Keywords = {diagnostic radiography;},
Abstract = {The feasibility of producing patient-specific beam
attenuators for chest radiography has been investigated
using an anthropomorphic phantom and a human volunteer. A
low-dose test exposure is digitized, processed, and used to
print a small cerium filter, which is placed in the X-ray
beam near the collimator. The final radiograph is recorded
on film. The technique results in relatively uniform film
exposure, so that structures in all regions of the chest are
simultaneously displayed with optimal film contrast. The
equalized exposure improves image quality in the normally
underpenetrated regions and reduces the role of
cross-scatter from the lungs. The image is analogous to
optical or computer processed unsharp masking techniques,
but the processing is accomplished in the X-ray beam and
results in an improved exposure distribution, giving
advantages that cannot be achieved with image processing
techniques alone},
Key = {2749911}
}
@article{2857369,
Author = {Hasegawa, BH and Naimuddin, S and Dobbins, JT and Mistretta, CA and Peppler, WW and Hangiandreou, NJ and Cusma, JT and McDermott, JC and Kudva, BV and Melbve, KM},
Title = {Chest radiography using patient-specific digitally-prepared
compensating filters},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {555},
Pages = {262-265},
Publisher = {SPIE},
Address = {Boston, MA, USA},
Year = {1985},
Month = {September},
url = {http://dx.doi.org/10.1117/12.949502},
Keywords = {diagnostic radiography;digital filters;},
Abstract = {We have used a prototype digital beam attenuator (DBA)
system to generate patient-specific digitally-prepared
compensating filters for chest radiography of a human
subject. The compensated radiographs demonstrate
substantially more information in areas such as the
mediastinum and upper abdomen which normally are
underpenetrated in conventional chest radiographs. The
compensated image was acquired with high contrast, high
speed film-screen receptors improving the visibility of
pulmonary parenchymal detail while minimizing patient
radiation exposure. Currently we are limited by a two-hour
preparation time and position the attenuator manually. We
are developing a second generation DBA system featuring fast
(15 second) fabrication times and automatic positioning of
the attenuator. We expect that these features will relieve
some of the misregistration errors present in our initial
examination. © 1985 SPIE.},
Doi = {10.1117/12.949502},
Key = {2857369}
}
@article{2588962,
Author = {Lee, CSR and Peppier, WW and Van Lysel and MS and Cusma, JT and Folts, JD and Zarnstorff, WC and Mistretta, CA and Dobbins, JT and Hasegawa, BH and Naimuddin, S and Molloi, S and Hangiandreou, N and Lancaster,
JC},
Title = {Adaptive processing algorithms for intravenous digital
subtraction coronary angiography},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {535},
Pages = {369-377},
Publisher = {SPIE},
Address = {Newport Beach, CA, USA},
Year = {1985},
Month = {June},
url = {http://dx.doi.org/10.1117/12.947292},
Keywords = {cardiology;computerised picture processing;diagnostic
radiography;},
Abstract = {Digital Subtraction Angiography (DSA) is commonly used in
conjunction with intravenous contrast injection for
detection of atherosclerotic disease in arteries outside of
the heart. Images of coronary arteries obtained with
intravenous DSA have been limited in quality by several
important factors. Among these is the confusing background
provided by superposed pulmonary veins. Because these
opacity just before the coronary arteries, conventional
remasking results in substantial loss in coronary artery
contrast. This paper presents preliminary work on a
processing scheme in which the degree of correlation between
the contrast pass curves in individual pixels and a
reference region can be used to adaptively suppress
pulmonary structures. © 1985 SPIE.},
Doi = {10.1117/12.947292},
Key = {2588962}
}
@article{2588957,
Author = {Hasegawa, BH and Dobbins, JT and Naimuddin, S and Mistretta, CA and Peppier, WW and Van Lysel and MS and Cusma, JT and Lancaster, JC and Hoffman, P and Lee, CS and Molloi, S and Hangiandreou, N and Kudva, BV and Melbye, KM},
Title = {Design of a digital beam attenuator system for chest
radiography},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {535},
Pages = {332-339},
Publisher = {SPIE},
Address = {Newport Beach, CA, USA},
Year = {1985},
Month = {June},
url = {http://dx.doi.org/10.1117/12.947279},
Keywords = {biomedical equipment;diagnostic radiography;},
Abstract = {We have been testing a digital beam attenuator (DBA) system
for fabricating patient- specific compensating filters to
improve image quality in chest radiography. At present, the
technique is limited by a 2 hour attenuator fabrication time
and a 20 mR exposure used to acquire an initial image from
which the attenutor is designed. We now are developing an
improved DBA system capable of generating, in a few seconds,
patient-specific compensating filters for clinical chest
radiography. The initial image will be acquired at less than
1 mR of skin exposure using an intensifying screen viewed by
a low light-level television camera. Image processing
including scatter and beam-hardening corrections generate a
64x64 matrix of values from which the attenuator is
fabricated. The attenutor will be fabricated with individual
layers having a 16x16 format using a special purpose
dot-matrix printer. Successive layers are shifted by a
quarter of a dot width to maintain the 64x64 sampling
frequency in the final attenuator. After the attenuator is
positioned automatically in the x-ray beam, a final image
will be acquired directly on film. © 1985
SPIE.},
Doi = {10.1117/12.947279},
Key = {2588957}
}
@article{85110168916,
Author = {Hasegawa, Bruce H. and Dobbins, James T. III and Naimuddin,
Shaikh and Mistretta, Charles A. and Peppler, Walter W. and Van Lysel and Michael S. and Cusma, Jack T. and Lancaster,
Jerome C. and Hoffman, Perry and Lee, Ching-Shan and Molloi,
Sabee and Hangiandreou, Nicholas and Kudva, Bakki V. and Melbye, Kenneth M.},
Title = {DESIGN OF A DIGITAL BEAM ATTENUATOR SYSTEM FOR CHEST
RADIOGRAPHY.},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {535},
Pages = {332 - 339},
Address = {Newport Beach, CA, USA},
Year = {1985},
Keywords = {IMAGE PROCESSING - Enhancement;},
Abstract = {The authors have been testing a digital beam attenuator
(DBA) system for fabricating patient-specific compensating
filters to improve image quality in chest radiography. At
present, the technique is limited by a 2 hour attenuator
fabrication time and a 2 mR exposure used to acquire an
initial image from which the attenutor is designed. They now
are developing an improved DBA system capable of generating,
in a few seconds, patient-specific compensating filters for
clinical chest radiography. The initial image will be
acquired at less than 1 mR of skin exposure using an
intensifying screen viewed by a low light-level television
camera. Image processing including scatter and
beam-hardening corrections generate a 64 multiplied by 64
matrix of values from which the attenuator is fabricated.
After the attenuator is positioned automatically in the
x-ray beam, a final image will be acquired directly on
film.},
Key = {85110168916}
}
@article{fds131723,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Naimuddin S, Dobbins JT 3rd, Peppler WW, Van
Lysel MS, Cusma JT, Lancaster JC, Hoffman P, Lee CS, Molloi
S, Mistretta CA, Kudva BV, Melbye KM. Design of a digital
beam attenuator system for chest radiography. Proc. SPIE
Conference on Applications of Optical Instrumentation in
Medicine XIII. Vol. 535, February 1985.},
Year = {1985},
Key = {fds131723}
}
@article{fds131761,
Author = {J.T. Dobbins},
Title = {Lee CS, Peppler WW, Van Lysel MS, Cusma JT, Folts JD,
Zarnstorff WC, Mistretta CA, Dobbins JT 3rd, Hasegawa BH,
Naimuddin S, Molloi S, Hangiandreou N, Lancaster JC.
Adaptive processing algorithms for intravenous digital
subtraction coronary angiography. Proc. SPIE Conference on
Applications of Optical Instrumentation in Medicine XIII.
Vol. 535, Feb. 1985.},
Year = {1985},
Key = {fds131761}
}
@article{fds131762,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Naimuddin S, Dobbins JT 3rd, Mistretta CA,
Peppler WW, Hangiandreou NJ, Cusma JT, McDermott JC. Chest
radiography using patient-specific digitally-prepared
compensating filters. Proc. SPIE Conference on Medical
Imaging and Instrumentation. Vol. 555, April
1985.},
Year = {1985},
Key = {fds131762}
}
@article{fds131767,
Author = {J.T. Dobbins},
Title = {Mistretta CA, Peppler WW, Hasegawa BH, Dobbins JT 3rd, Kudva
BV. Digitally controlled x-ray beam attenuation method and
apparatus. U.S. Patent #4,497,062, January
1985.},
Year = {1985},
Key = {fds131767}
}
@article{fds268521,
Author = {Hasegawa, BH and Peppler, WW and Dobbins, JT and Kudva, BV and Mistretta, CA and Cusma, JT and Van Lysel and MS and Lee, CS and Naimuddin,
S and Molloi, S and Lancaster, JC and Melbye, K},
Title = {DIGITAL BEAM ATTENUATOR FOR DSA AND CHEST
RADIOGRAPHY.},
Pages = {56},
Year = {1984},
Month = {December},
Abstract = {During the past year our group has investigated an extension
of the concept of beam compensating filters. Our approach
involves the acquisition of a low dose patient positioning
image which is digitized and used to drive a mechanism which
places attenuating materials in the x-ray beam. Our initial
experiments involved a 6 multiplied by 6 array of pistons
which deformed a bladder filled with cerous chloride. This
device had inadequate spatial resolution and excessive
common mode x-ray attenuation. More recently we have
developed a technique involving a digitally controlled
dot-matrix printer equipped with a ribbon containing cerium
oxide. This is used to type an attenuating image of the
patient. This attenuator is then servoed into the x-ray
beam. Current attenuator formation times are on the order of
five minutes. Soon we hope to be able to accomplish this in
30 seconds. Preliminary results using a Humanoid chest
phantom and laboratory animals demonstrate the distinct
advantages of the technique. Image quality relative to
uncompensated images is striking in simulated chest
radiography and DSA.},
Key = {fds268521}
}
@article{2465776,
Author = {Hasegawa, BH and Naimuddin, S and Dobbins, JT and Peppier, WW and Cusma,
JT and Van Lysel and MS and Lancaster, JC and Lee, CS and Molloi, S and Mistretta, CA and Kudva, BV and Melbye, KM},
Title = {Application of a digital beam attenuator to chest
radiography},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {486},
Pages = {2-7},
Publisher = {SPIE},
Address = {Las Vegas, NV, USA},
Year = {1984},
Month = {August},
url = {http://dx.doi.org/10.1117/12.943191},
Keywords = {biomedical equipment;diagnostic radiography;},
Abstract = {Although image quality in chest radiography can be improved
dramatically with compensat-ing attenuators, it is difficult
to match attenuator geometry to that of the patient and to
properly position the filter in the x-ray beam. We are
developing a system which will fabricate a compensating
filter specific for individual patient anatomy and position
the filter automatically. A low-dose image is acquired from
which the attenuator is designed using a hardwired
algorithm. The attenuator then is typed in multiple layers
of a cerium oxide material onto a sheet of paper with a
dot-matrix printer. Following positioning of the attenuator
in the x-ray beam, the final compensated image is acquired
with a photographic or electronic detector.Initial studies
with our prototype digital beam attenuator have produced
images with improved image quality. The improvement occurs
because the attenuator allows the entire image to be placed
in the linear portion of the film characteristic curve. In
addition, decreased scatter fractions and increased
signal-to-noise contribute to improved visualization of low-
contrast signals behind the most attenuating regions of the
patient. © 1984 SPIE.},
Doi = {10.1117/12.943191},
Key = {2465776}
}
@article{2364693,
Author = {Hasegawa, BH and Dobbins, JT and Peppier, WW and Cusma, JT and Mistretta, CA and Kudva, BV and Van Lysel and MS and Lee, CS and Naimuddin,
S and Lancaster, JC and Molloi, S and Melbye, KM},
Title = {Feasibility of selective exposure radiography},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {454},
Pages = {271-278},
Publisher = {SPIE},
Address = {San Diego, CA, USA},
Year = {1984},
Month = {June},
url = {http://dx.doi.org/10.1117/12.939342},
Keywords = {radiography;},
Abstract = {The concept of selective exposure radiography encompasses
those techniques which spatially modulate the incident x-ray
field to produce a more uniform exit field arising from the
patient. The resulting reduction in the dynamic range of the
exposure field offers several advantages. In conventional
radiography, selective exposure techniques allow all areas
of the image to be placed in the linear portion of the film
characteristic curve so that local contrast is maximized.
With video systems, the reduction in dynamic range minimizes
the impact of electronic noise behind the least transmissive
regions of the patient. With both electronic and
photographic detectors, selective exposure radiography is
characterized by uniform quantum statistics and uniform
scatter across the image. Several selective exposure
techniques currently are being investigated. They include
compensating filters placed manually in the x-ray field as
well as fan-beam geometries in which the x-ray tube output
is modulated with a feedback circuit to maintain constant
exposure to the image receptor. At the University of
Wisconsin, we have been investigating a digital system which
uses an initial low-dose patient image to design an
attenuator with transmission complimentary to that of the
patient. The attenuator is fabricated for each patient and
is positioned automatically in the x-ray beam prior to the
acquisition of the final compensated image. The possible
applications of this device include chest radiography,
coronary angiography, subtraction angiography, and accurate
digital videodensitometry. © 1984 SPIE.},
Doi = {10.1117/12.939342},
Key = {2364693}
}
@article{fds131754,
Author = {J.T. Dobbins},
Title = {Mistretta CA, Van Lysel MS, Peppler W, Dobbins JT 3rd,
Hasegawa B, Zarnstorff W, Lee CS, Naimuddin S, Myerowitz PD,
Swanson D, Strother CM, Crummy AB, Sackett JF. Applicazioni
attuali e aspetti tecnici della angiografia digitale. La
Radiologia Medica 1984 Apr;70(4):177-84.},
Year = {1984},
Key = {fds131754}
}
@article{fds131759,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Dobbins JT 3rd, Peppler WW, Cusma JT, Kudva BV,
Mistretta CA, Van Lysel MS, Lee CS, Naimuddin S, Lancaster
JC, Melbye K. Feasibility of selective exposure radiography.
Proc. SPIE Conference on Applications of Optical
Instrumentation in Medicine XII. 1984 Feb;454:271-78.},
Year = {1984},
Key = {fds131759}
}
@article{fds131760,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Dobbins JT 3rd, Peppler WW, Kudva BV, Mistretta
CA, Cusma JT, Melbye KM, Van Lysel MS, Lee CS,
Naimuddin S, Molloi S, Lancaster JC. Application of a
digital beam attenuator to chest radiography. Proc. SPIE
Conference on Medical Imaging and Instrumentation 1984
Apr;486:2-7.},
Year = {1984},
Key = {fds131760}
}
@article{fds172347,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Dobbins JT 3rd, Peppler WW, Kudva BV, Mistretta
CA, Cusma JT, Melbye KM, Van Lysel MS, Lee CS, Naimuddin S,
Molloi S, Lancaster JC. Application of a digital beam
attenuator to chest radiography. Proc. SPIE Conference on
Medical Imaging and Instrumentation 1984 Apr;486:2-7.
},
Year = {1984},
Key = {fds172347}
}
@article{fds268598,
Author = {Dobbins, JT and Pedersen, PL and Mazess, RB and Cameron, JR and Hansen,
JL and Hefner, LV},
Title = {A scanning-slit x-ray videoabsorptiometric technique for
bone mineral measurement.},
Journal = {Medical Physics},
Volume = {11},
Number = {5},
Pages = {582-588},
Year = {1984},
ISSN = {0094-2405},
url = {http://www.ncbi.nlm.nih.gov/pubmed/6503872},
Keywords = {Aged • Bone and Bones • Female • Femur •
Fluoroscopy • Humans • Minerals • analysis
• analysis* • instrumentation •
methods},
Abstract = {An x-ray videoabsorptiometric technique was developed for
measurement of bone mineral content (BMC) in vivo. The
principle utility of this technique is the precise
measurement of commonly fractured bones, such as the femoral
neck, that are difficult to measure by other techniques
because of repositioning problems. Scanning slits reduce
scattered radiation and improve linearity of measurements.
Heavily filtered, high-kVp beams are used to minimize errors
from beam hardening, and data renormalization is employed to
compensate for spatial nonuniformities of the beam and
detector. Linearity of measured BMC over the range 0.8 to 5
g/cm2 is very good (r = 0.998) and compares well to single-
and dual-photon absorptiometry. A 1.6% change in measured
BMC is observed for a 10% change (approximately 2 cm) in
tissue thickness while a 10% change in marrow type causes a
0.6%-0.8% change in BMC. Manual repositioning of a femur
phantom revealed a variation of 0.84% over ten measurements
when femur values were referenced to standards. A computer
repositioning algorithm provides much easier identification
of the region for analysis and yields comparable variation
(0.9%).},
Language = {eng},
Doi = {10.1118/1.595554},
Key = {fds268598}
}
@article{2306544,
Author = {Dobbins, JT and Van Lysel and MS and Hasegawa, BH and Peppier, WW and Mistretta, CA},
Title = {Spatial frequency filtering in digital subtraction
angiography (DSA) by real-time digital video
convolution},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {419},
Pages = {111-121},
Publisher = {SPIE},
Address = {Atlanta, GA, USA},
Year = {1983},
Month = {December},
url = {http://dx.doi.org/10.1117/12.936013},
Keywords = {computerised picture processing;densitometry;radiography;spatial
filters;},
Abstract = {A circuit has been constructed to perform spatial frequency
filtration on DSA images at real-time video rates. The
10-bit device performs low-pass or high-pass filtering, and
with external memory can perform bandpass and more
sophisticated filtering. Pixels in the convolving kernel are
weighted independendently in the x-and y-directions to
provide a Gauss-ian-like convolving function. The kernel
width ranges from 3-30 pixels and appropriate weighting
yields a FWHM of the Gaussian kernel function as small as
0.85 pixel width for horizontal image widths of ≤256
pixels and as small as 1.25 pixel width for a horizontal
image width of 512 pixels. Applications to be investigated
include scatter and glare correction for videodensitometry,
enhancement of arteries behind large opacified structures
such as the ventricle and aorta, noise suppression in
low-spatial frequency DSA exams, edge-enhancement of images,
and partial-pixel shifting. Peli and Lim have suggested a
more sophisticated algorithm which enhances high-pass
filtration only in dark regions of an image. This and other
techniques may be implemented with the current circuit to
enhance small detail in highly opacified regions such as the
ventricle, while leaving the rest of the image unaltered. ©
1983 SPIE.},
Doi = {10.1117/12.936013},
Key = {2306544}
}
@article{84050086380,
Author = {Hasegawa, BH and Dobbins, JT and Peppler, WW and Kudva, BV and Melbye,
KM and Van Lysel and MS and Lee, CS and Naimuddin, S and Lancaster, JC and Mistretta, CA},
Title = {SELECTIVE EXPOSURE RADIOGRAPHY USING DIGITALLY-FORMED X-RAY
BEAM ATTENUATORS.},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {419},
Pages = {282-288},
Address = {Atlanta, Ga, USA},
Year = {1983},
Month = {December},
Keywords = {BIOMEDICAL ENGINEERING;},
Key = {84050086380}
}
@article{fds268513,
Author = {Mistretta, CA and Peppler, WW and Van Lysel and M and Dobbins, J and Hasegawa, B and Myerowitz, PD and Swanson, D and Lee, CS and Shaik, N and Zarnstorff, W},
Title = {Recent advances in digital radiography.},
Journal = {Annales De Radiologie},
Volume = {26},
Number = {7},
Pages = {537-542},
Year = {1983},
Month = {November},
ISSN = {0003-4185},
Abstract = {The authors present several recents advances in digital
angiography; combined energy time subtraction angiography;
temporal filtration and integration schemes and problems
concerning intravenous coronary angiography.},
Key = {fds268513}
}
@article{fds268593,
Author = {Van Lysel and MS and Dobbins, JT and Peppler, WW and Hasegawa, BH and Lee,
CS and Mistretta, CA and Zarnstorff, WC and Crummy, AB and Kubal, W and Bergsjordet, B and Strother, CM and Sackett, JF},
Title = {Work in progress: hybrid temporal-energy subtraction in
digital fluoroscopy.},
Journal = {Radiology},
Volume = {147},
Number = {3},
Pages = {869-874},
Year = {1983},
Month = {June},
ISSN = {0033-8419},
url = {http://www.ncbi.nlm.nih.gov/pubmed/6342038},
Keywords = {Analog-Digital Conversion • Angiography • Carotid
Arteries • Computers • Fluoroscopy • Humans
• Subtraction Technique • instrumentation* •
methods • methods* • radiography},
Abstract = {Initial clinical results using a digital fluoroscopic
implementation of the combined time-energy ("hybrid")
subtraction technique are described, with emphasis on
carotid and renal imaging. Where patient motion artifacts
are due to soft-tissue motion alone, hybrid subtraction can
remove them. Due to the need for a finite separation time
between high- and low-energy pairs, however, the present
implementation of the hybrid technique is not completely
immune to soft-tissue motion. The intrinsic signal-to-noise
ratio of hybrid imaging is less than that of conventional
temporal subtraction. However, since the low-energy temporal
subtraction images are included in the hybrid data set, the
diagnostic quality of the examination is not
compromised.},
Language = {eng},
Doi = {10.1148/radiology.147.3.6342038},
Key = {fds268593}
}
@article{fds268608,
Author = {Swanson, DK and Myerowitz, PD and Hasegawa, B and Van Lysel and MS and Watson, KM and Frantz, DW and Banaszak, S and Hausman-Stokes, E and Peppler, WW and Dobbins, JT},
Title = {Videodensitometric quantitation of mean blood
flow.},
Journal = {Journal of Surgical Research},
Volume = {34},
Number = {6},
Pages = {524-532},
Year = {1983},
Month = {June},
ISSN = {0022-4804},
url = {http://www.ncbi.nlm.nih.gov/pubmed/6855221},
Keywords = {Absorptiometry, Photon • Angiography • Animals
• Blood Circulation* • Computers • Dogs
• Femoral Artery • Videotape Recording* •
methods • methods* • radiography},
Abstract = {Standard angiography demonstrates the anatomy of arterial
occlusive disease but does not define its physiological
significance. However, measurement of flow in a compromised
vessel at rest and following peripheral dilatation provides
important physiological information. Using digital
subtraction angiography, femoral arterial flows determined
by the cross-correlation transit time technique were
compared to measurements by electromagnetic flowmeter.
Thirty-five femoral arterial flow measurements were obtained
in nine dogs instrumented with an electromagnetic flow probe
and balloon occluder. Renografin 76 (7 cc) was
power-injected at 14 cc/sec into the distal abdominal aorta.
Angiographic flow measurements correlated well with
electromagnetic flowmeter measurements (r = 0.94, standard
deviation of the difference (SDD) = 15 ml/min). Intravenous
studies provided somewhat poorer correlation due to
difficulties in defining dimensions (r = 0.72, SDD = 36).
Paired contrast injections (2 injections in succession) in
11 studies increased flow from an average of 80 to 250
ml/min (a 210 +/- 100% increase), providing an estimate of a
vessel's capacity to provide increased flow during
peripheral dilatation. Thus, reliable angiographic flow
determinations may be obtained by arterial and intravenous
contrast injections, adding physiological information to
anatomical definition.},
Language = {eng},
Doi = {10.1016/0022-4804(83)90105-1},
Key = {fds268608}
}
@article{84050086358,
Author = {Dobbins, J. T. III and Van Lysel and M. S. and Hasegawa, B. H. and Peppler, W. W. and Mistretta, C. A.},
Title = {SPATIAL FREQUENCY FILTERING IN DIGITAL SUBTRACTION
ANGIOGRAPHY (DSA) BY REAL-TIME DIGITAL VIDEO
CONVOLUTION.},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {419},
Pages = {111 - 121},
Address = {Atlanta, Ga, USA},
Year = {1983},
Keywords = {BIOMEDICAL ENGINEERING;},
Key = {84050086358}
}
@article{2299694,
Author = {Hasegawa, B.H. and Dobbins, J.T. and Peppler, W.W. and Kudva, B.V. and Melbye, K.M. and Van Lysel and M.S. and Lee,
C.S. and Naimuddin, S. and Lancaster, J.C. and Mistretta,
C.A.},
Title = {Selective exposure radiography using digitally-formed X-ray
beam attenuators},
Journal = {Proc. SPIE - Int. Soc. Opt. Eng. (USA)},
Volume = {419},
Pages = {282 - 8},
Address = {Atlanta, GA, USA},
Year = {1983},
Keywords = {computerised picture processing;radiography;},
Abstract = {Compensation attenuators can provide fundamental
improvements in radiographic image formation by modifying
patient dose distribution, reducing scatter fractions in
dark regions of the image, and easing dynamic range
requirements for film and video systems. The authors have
designed a software-based system which forms a heavy-metal
attenuator from a digital image of the patient. At present,
the attenuators are constructed manually from a pattern
generated by the computer, but several techniques are being
investigated which may permit fabrication and positioning
during suspension of respiration. Phantom studies
demonstrates that, in nonsubtractive applications, unsharp
masking by the X-ray beam attenuator enhances local
contrast, while in digitally subtracted images, attenuators
eliminate dark regions where iodine signals otherwise are
degraded by video and quantum noise},
Key = {2299694}
}
@article{fds131721,
Author = {J.T. Dobbins},
Title = {Crummy AB, Stieghorst MF, Van Lysel MS, Dobbins JT 3rd.
Advances in diagnosis: applying digital subtraction
arteriography. J Cardiovascular Med. 1983
Mar;8(3):345-62.},
Year = {1983},
Key = {fds131721}
}
@article{fds131753,
Author = {J.T. Dobbins},
Title = {Mistretta CA, Peppler WW, Van Lysel M, Dobbins JT 3rd,
Hasegawa B, Myerowitz PD, Swanson D, Lee CS, Naimuddin S,
Zarnstorff W, Crummy AB, Strother CM, Sackett JF. Recent
advances in digital radiography. Annales de Radiologie 1983
Nov;26(7):537-42.},
Year = {1983},
Key = {fds131753}
}
@article{fds131756,
Author = {J.T. Dobbins},
Title = {Dobbins JT 3rd, Van Lysel MS, Hasegawa BH, Peppler WW,
Mistretta CA. Spatial frequency filtering in digital
subtraction angiography (DSA) by real-time digital video
convolution. Proc. SPIE Conference on Applications of
Optical Instrumentation in Medicine XI. 1983
Apr;419:111-21.},
Year = {1983},
Key = {fds131756}
}
@article{fds131757,
Author = {J.T. Dobbins},
Title = {Hasegawa BH, Dobbins JT 3rd, Peppler WW, Kudva BV, Melbye K,
Van Lysel MS, Lee CS, Naimuddin S, Lancaster JC, Mistretta
CA. Selective exposure radiography using digitally-formed
x-ray beam attenuators. Proc. SPIE Conference on
Applications of Optical Instrumentation in Medicine XI. 1983
Apr;419:282-88.},
Year = {1983},
Key = {fds131757}
}
@article{fds131758,
Author = {J.T. Dobbins},
Title = {Peppler WW, Van Lysel MS, Dobbins JT 3rd, Lancaster JC,
Hicks J, Hasegawa BH, Lee CS, Shaikh N, Zarnstorff WC,
Mistretta CA, Myerowitz PD, Swanson DK. Progress report on
the University of Wisconsin digital video image processor
(DVIP II). Digital Imaging in Cardiovascular Radiology,
Heintzen PH and Brennecke R (eds), Georg Theime Verlag,
Stuttgart, 1983.},
Year = {1983},
Key = {fds131758}
}
@article{2100651,
Author = {Van Lysel and M.S. and Dobbins, J.T., III. and Peppler, W.W. and Hasegawa, B.H. and Ching-Shan Lee and Mistretta, C.A. and Zarnstorff, W.C. and Crummy, A.B. and Kubal, W. and Bergsjordet, B. and Strother, C.M. and Sackett,
J.F.},
Title = {Work in progress: hybrid temporal-energy subtraction in
digital fluoroscopy},
Journal = {Radiology (USA)},
Volume = {147},
Number = {3},
Pages = {869 - 74},
Year = {1983},
Keywords = {computerised picture processing;radiography;},
Abstract = {Initial clinical results using a digital fluoroscopic
implementation of the combined time-energy (`hybrid')
subtraction technique are described, with emphasis on
carotid and renal imaging. Where patient motion artifacts
are due to soft-tissue motion alone, hybrid subtraction can
remove them. Due to the need for a finite separation time
between high- and low-energy pairs, however, the present
implementation of the hybrid technique is not completely
immune to soft-tissue motion. The intrinsic signal-to-noise
ratio of hybrid imaging is less than that of conventional
temporal subtraction. However, since the low-energy temporal
subtraction images are included in the hybrid data set, the
diagnostic quality of the examination is not
compromised},
Key = {2100651}
}
@article{2050922,
Author = {Peppler, CW and Kudva, B and Dobbins, JT and Lee, CS and Lysel, MS and Hasegawa, BH and Mistretta, CA},
Title = {Digitally controlled beam attenuator},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {347},
Pages = {106-111},
Publisher = {SPIE},
Address = {New Orleans, LA, USA},
Year = {1982},
Month = {December},
url = {http://dx.doi.org/10.1117/12.933815},
Keywords = {biomedical equipment;computerised control;radiography;},
Abstract = {In digital fluorographic techniques the video camera must
accommodate a wide dynamic range due to the large variation
in the infject thickness within the field of view. Typically
exposure factors and the optical aperture are selected such
that the maximum video signal is obtained in the most
transmissive region of the infject. Consequently, it has
been shown that the signal-to-noise ratio is severely
reduced in the dark regions. We have developed a prototype
digital beam attenuator (DBA) which will alleviate this and
some related problems in digital fluorography. The prototype
DBA consists of a 6x6 array of pistons which are
individually controlled. A membrane containing an
attenuating solu-tion of (CeC13) in water and the piston
matrix are placed between the x-ray tube and the infject.
Under digital control the pistons are moved into the
attenuating material in order to adjust the beam intensity
over each of the 36 cells. The DBA control unit which
digitizes the image during patient positioning will direct
the pistons under hydraulic control to produce a uniform
x-ray field exiting the infject. The pistons were designed
to produce very little structural background in the image.
In inftraction studies any structure would be cancelled. For
non-inftraction studies such as cine-cardiology we are
considering higher cell densities (eg. 64x64). Due to the
narrow range of transmission provided by the DBA, in such
studies ultra-high contrast films could be used to produce a
high resolution quasi-inftraction display. Additional
benefits of the DBA are: 1) reduced dose to the bright image
areas when the dark areas are properly exposed. 2) improved
scatter and glare to primary ratios, leading to improved
contrast in the dark areas. © 1982 SPIE.},
Doi = {10.1117/12.933815},
Key = {2050922}
}
@article{83100157091,
Author = {Peppler, W. W. and Kudva, B. and Dobbins, J. T. III and Lee,
C. S. and Van Lysel and M. S. and Hasegawa, B. H. and Mistretta, C. A.},
Title = {DIGITALLY CONTROLLED BEAM ATTENUATOR.},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {347},
Pages = {106 - 111},
Address = {New Orleans, LA, USA},
Year = {1982},
Keywords = {BIOMEDICAL ENGINEERING;},
Key = {83100157091}
}
@article{fds131722,
Author = {J.T. Dobbins},
Title = {Peppler WW, Kudva BV, Dobbins JT 3rd, Lee CS, Hasegawa BH,
Van Lysel M, Mistretta CA. A digitally controlled beam
attenuator. Proc. SPIE Conference on Applications of Optical
Instrumentation in Medicine X. 1982 May;347:106-11.},
Year = {1982},
Key = {fds131722}
}
@article{fds131766,
Author = {J.T. Dobbins},
Title = {Myerowitz PD, Mistretta CA, Shaw CG, Van Lysel MS, Swanson
DK, Lasser TA, Dhanani SP, Zarnstorff WC, Vander Ark CR,
Dobbins JT 3rd, Peppler WW, Crummy AB. Digital
cardiovascular imaging. In Coronary Artery Disease Today,
Bruschke AVG, van Herpen G, Vermeulen FEE (eds), Excerpta
Medica, Amsterdam, 1982.},
Year = {1982},
Key = {fds131766}
}
@article{82100136225,
Author = {Van Lysel and MS and Zarnstorff, WC and Lancaster, JC and Mistretta, CA and Dobbins, JT},
Title = {REAL-TIME DIGITAL VIDEO RECORDING SYSTEM.},
Journal = {Smart Structures and Materials 2005: Active Materials:
Behavior and Mechanics},
Volume = {314},
Pages = {389-395},
Address = {Stanford, CA, USA},
Year = {1981},
Month = {December},
Keywords = {IMAGE PROCESSING;},
Key = {82100136225}
}
@article{fds131755,
Author = {J.T. Dobbins},
Title = {Van Lysel MS, Zarnstorff WC, Lancaster JC, Mistretta CA,
Dobbins JT 3rd. Real-time digital video recording system.
Proc. SPIE Conference on Digital Radiography. 1981
Sep;314:389-95.},
Year = {1981},
Key = {fds131755}
}
@article{82100136184,
Author = {Shaw, CG and Ergun, DL and Lysel, MSV and Peppler, WW and Dobbins, JT and Zarnstorff, WC and Myerowitz, PD and Swanson, DK and Lasser, TA and Mistretta, CA and Dhanani, SP and Strother, CM and Crummy,
AB},
Title = {QUANTITATION TECHNIQUES IN DIGITAL SUBTRACTION
VIDEOANGIOGRAPHY.},
Journal = {Proceedings of Spie the International Society for Optical
Engineering},
Volume = {314},
Pages = {121-129},
Publisher = {SPIE},
Address = {Stanford, CA, USA},
Year = {1981},
url = {http://dx.doi.org/10.1117/12.933033},
Keywords = {RADIOGRAPHY;},
Abstract = {Digital subtraction videoangiography has been proven to be
suitable for imaging the left ventricle and other cardiac
chambers.l, 2 The high contrast sensitivity and good
cancellation of structural background enable this imaging
technique to be used with intra-venous injections, which
result in complete mixing of contrast medium with blood in
the left ventricle.3 The digital nature of the image
processor used in subtraction video-angiography enables
convenient data collection and analysis. For these reasons,
digital videoangiography is well suited to
videodensitometric calculation of physiological quantities
such as left ventricular ejection fraction. © 1981
SPIE.},
Doi = {10.1117/12.933033},
Key = {82100136184}
}
@article{2398373,
Author = {Dobbins, J.T., III and Pedersen, P.L. and Mazess, R.B. and Cameron, J.R. and Hansen, J.L. and Hefner,
L.V.},
Title = {A scanning-slit X-ray videoabsorptiometric technique for
bone mineral measurement},
Journal = {Med. Phys. (USA)},
Volume = {11},
Number = {5},
Pages = {582 - 8},
url = {http://dx.doi.org/10.1118/1.595554},
Keywords = {biomedical measurement;bone;diagnostic radiography;},
Abstract = {An X-ray videoabsorptiometric technique was developed for
measurement of bone mineral content (BMC) in vivo. The
principle utility of this technique is the precise
measurement of commonly fractured bones, such as the femoral
neck, that are difficult to measure by other techniques
because of repositioning problems. Scanning slits reduce
scattered radiation and improve linearity of measurements.
Heavily filtered, high-kVp beams are used to minimize errors
from beam hardening, and data renormalization is employed to
compensate for spatial nonuniformities of the beam and
detector. Linearity of measured BMC over the range 0.8 to 5
g/cm<sup>2</sup> is very good (<i>r</i>=0.998) and compares
well to single- and dual-photon absorptiometry. A 1.6%
change in measured BMC is observed for a 10% change (~2 cm)
in tissue thickness while a 10% change in marrow type causes
a 0.6%-0.8% change in BMC. Manual repositioning of a femur
phantom revealed a variation of 0.84% over ten measurements
when femur values were referenced to standards. A computer
repositioning algorithm provides much easier identification
of the region for analysis and yields comparable variation
(0.9%)},
Key = {2398373}
}
@article{8104164,
Author = {Samei, E. and Saunders, R.S. and Lo, J.Y. and Dobbins, J.T. and Jesneck, J.L. and Floyd, C.E. and Ravin,
C.E.},
Title = {Fundamental imaging characteristics of a slot-scan digital
chest radiographic system},
Journal = {Med. Phys. (USA)},
Volume = {31},
Number = {9},
Pages = {2687 - 98},
url = {http://dx.doi.org/10.1118/1.1783531},
Keywords = {aluminium;diagnostic radiography;flat panel displays;image
resolution;lung;medical image processing;phantoms;},
Abstract = {Our purpose in this study was to evaluate the fundamental
image quality characteristics of a new slot-scan digital
chest radiography system (ThoraScan, Delft Imaging
Systems/Nucletron, Veenendaal, The Netherlands). The
linearity of the system was measured over a wide exposure
range at 90, 117, and 140 kVp with added Al filtration.
System uniformity and reproducibility were established with
an analysis of images from repeated exposures. The
modulation transfer function (MTF) was evaluated using an
established edge method. The noise power spectrum (NPS) and
the detective quantum efficiency (DQE) of the system were
evaluated at the three kilo-voltages over a range of
exposures. Scatter fraction (SF) measurements were made
using a posterior beam stop method and a geometrical chest
phantom. The system demonstrated excellent linearity, but
some structured nonuniformities. The 0.1 MTF values occurred
between 3.3-3.5 mm<sup>-1</sup>. The DQE(0.15) and DQE(2.5)
were 0.21 and 0.07 at 90 kVp, 0.18 and 0.05 at 117 kVp, and
0.16 and 0.03 at 140 kVp, respectively. The system exhibited
remarkably lower SFs compared to conventional full-field
systems with anti-scatter grid, measuring 0.13 in the lungs
and 0.43 in the mediastinum. The findings indicated that the
slot-scan design provides marked scatter reduction leading
to high effective DQE (DQE<sub>eff</sub>) of the system and
reduced patient dose required to achieve high image
quality},
Key = {8104164}
}