Publications of James T. Dobbins    :recent first  alphabetical  combined listing:

%% Papers Published   
@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}
}

@article{82100136225,
   Author = {Lysel, MSV and Zarnstorff, WC and Lancaster, JC and Mistretta, CA and III, JTD},
   Title = {REAL-TIME DIGITAL VIDEO RECORDING SYSTEM.},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {314},
   Pages = {389-395},
   Address = {Stanford, CA, USA},
   Year = {1981},
   Keywords = {IMAGE PROCESSING;},
   Key = {82100136225}
}

@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},
   Address = {Stanford, CA, USA},
   Year = {1981},
   Keywords = {RADIOGRAPHY;},
   Key = {82100136184}
}

@article{fds131755,
   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{2050922,
   Author = {Peppler, WW and Kudva, B and III, JTD and Lee, CS and Lysel, MSV and Hasegawa, BH and Mistretta, CA},
   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 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 subject 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 subject. Consequently, it has
             been shown that the signal-to-noise ratio is severely
             reduced in the dark regions. The authors 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 6&times;6 array of pistons which
             are individually controlled. A membrane containing an
             attenuating solution of (CdCl<sub>3</sub>) in water and the
             piston matrix are placed between the X-ray tube and the
             subject. 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 directs
             the pistons under hydraulic control to produce a uniform
             X-ray field exiting the subject. The pistons were designed
             to produce very little structural background in the
             image},
   Key = {2050922}
}

@article{fds131722,
   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,
   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{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{2306544,
   Author = {III, JTD and Lysel, MSV and Hasegawa, BH and Peppler, WW and Mistretta,
             CA},
   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 = {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 and
             weighted independently in the x- and y-directions to provide
             a Gaussian-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 &les;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 video densitometry, 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},
   Key = {2306544}
}

@article{84050086380,
   Author = {Hasegawa, BH and III, JTD and Peppler, WW and Kudva, BV and Melbye, KM and Lysel, MSV and Lee, CS and Naimuddin, S and Lancaster, JC and Mistretta,
             CA},
   Title = {SELECTIVE EXPOSURE RADIOGRAPHY USING DIGITALLY-FORMED X-RAY
             BEAM ATTENUATORS.},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {419},
   Pages = {282-288},
   Address = {Atlanta, Ga, USA},
   Year = {1983},
   Keywords = {BIOMEDICAL ENGINEERING;},
   Key = {84050086380}
}

@article{fds268513,
   Author = {Mistretta, CA and Peppler, WW and Lysel, MV 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},
   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{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{fds131721,
   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,
   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,
   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,
   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,
   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{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{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},
   Key = {fds268608}
}

@article{2465776,
   Author = {Hasegawa, BH and Naimuddin, S and III, JTD and Peppler, WW and Cusma,
             JT and Lysel, MSV and Lancaster, JC and Lee, C-S and Molloi, S and Mistretta, CA and Kudva, BV and Melbye, KM},
   Title = {APPLICATION OF A DIGITAL BEAM ATTENUATOR TO CHEST
             RADIOGRAPHY.},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {486},
   Pages = {2-7},
   Address = {Las Vegas, NV, USA},
   Year = {1984},
   Keywords = {biomedical equipment;diagnostic radiography;},
   Abstract = {Although image quality in chest radiography can be improved
             dramatically with compensating attenuators, it is difficult
             to match attenuator geometry to that of the patient and to
             properly position the filter in the x-ray beam. The authors
             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 the prototype digital beam attenuator have produced
             images with improved image quality. Decreased scatter
             fractions and increased signal-to-noise contribute to
             improved visualization of low-contrast signals behind the
             most attenuating regions of the patient.},
   Key = {2465776}
}

@article{2364693,
   Author = {Hasegawa, BH and III, JTD and Peppler, WW and Cusma, JT and Mistretta,
             CA and Kudva, BV and Lysel, MSV and Lee, C-S and Naimuddin, S and Lancaster, JC and Molloi, S and Melbye, KM},
   Title = {FEASIBILITY OF SELECTIVE EXPOSURE RADIOGRAPHY.},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {454},
   Pages = {271-278},
   Address = {San Diego, CA, USA},
   Year = {1984},
   Keywords = {radiography;},
   Abstract = {Several selective exposure radiography 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.},
   Key = {2364693}
}

@article{fds268521,
   Author = {Hasegawa, BH and Peppler, WW and Dobbins, JT and Kudva, BV and Mistretta, CA and Cusma, JT and Lysel, MSV 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},
   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{fds131754,
   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,
   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,
   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,
   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}, Month = {September}, 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{2588962, Author = {Lee, C-SR and Peppler, WW and Lysel, MSV and Cusma, JT and Folts, JD and Zarnstorff, WC and Mistretta, CA and III, JTD 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 = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {535}, Pages = {369-377}, Address = {Newport Beach, CA, USA}, Year = {1985}, 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 opacify 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.}, Key = {2588962} } @article{2588957, Author = {Hasegawa, BH and III, JTD and Naimuddin, S and Mistretta, CA and Peppler, WW and Lysel, MSV and Cusma, JT and Lancaster, JC and Hoffman, P and Lee, C-S and Molloi, S and Hangiandreou, N and Kudva, BV and Melbye, KM}, 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 = {biomedical equipment;diagnostic radiography;}, 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 = {2588957} } @article{2857369, Author = {Hasegawa, BH and Naimuddin, S and III, JTD and Mistretta, CA and Peppler, WW and Hangiandreou, NJ and Cusma, JT and McDermott, JC and Kudva, BV and Melbye, KM}, Title = {CHEST RADIOGRAPHY USING PATIENT-SPECIFIC DIGITALLY-PREPARED COMPENSATING FILTERS.}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {555}, Pages = {262-265}, Address = {Boston, MA, USA}, Year = {1985}, 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 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 sec) fabrication times and automatic positioning of the attenuator.}, Key = {2857369} } @article{fds131723, 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, 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, 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, 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{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{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{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{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&times;4 blurring function on the original 64&times;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&times;16 matrix, staggering successively printed layers to achieve the required 64&times;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{fds131724, 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, 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{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}, Month = {May}, 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{fds131726, 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{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{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{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&times;10<sup>-9</sup> to 2.0&times;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{fds131768, 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{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{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}, Month = {May}, 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{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{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}, Key = {fds268590} } @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{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{fds131727, 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{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{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{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{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{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{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{fds268519, Author = {CHOTAS, HG and FLOYD, CE and DOBBINS, JT and RAVIN, CE}, Title = {USE OF RADIATION RISK AS THE BASIS FOR IMAGE QUALITY COMPARISONS - REPLY}, Journal = {Radiology}, Volume = {189}, Number = {1}, Pages = {290-290}, 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}, Key = {fds268519} } @article{fds131764, 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{95052693478, Author = {Hinshaw, DA and III, JTD}, Title = {Recent progress in noise reduction and scatter correction in dual-energy imaging}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {2432}, Pages = {134-142}, Address = {San Diego, CA, USA}, Year = {1995}, 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.}, Key = {95052693478} } @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{fds131707, 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{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&times; greater at low frequencies and about 3&times;. 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{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{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{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{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{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{02397114234, Author = {III, JTD and Boone, JM}, Title = {Erratum: (Medical Imaging 1998 - Physics of Medical Imaging (22-24 February 1998))}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {3336}, Pages = {838-}, Address = {San Diego, CA, United States}, Editor = {Dobbins III and J.T.;Boone, J.M.;}, Year = {1998}, 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 &times; 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{fds268522, Author = {III, JTD and Boone, JM}, Title = {Proceedings of SPIE - The International Society for Optics: Introduction}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {3336}, Pages = {xiii-xiv}, Year = {1998}, Key = {fds268522} } @article{fds131708, Title = {Dobbins JT 3rd, Boone JM (eds). Medical Imaging 1998: Physics of Medical Imaging, SPIE, Bellingham, WA, 1998.}, Year = {1998}, Key = {fds131708} } @article{fds131728, 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{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 (&ldquo;beveled edge&rdquo; versus &ldquo;straight edge&rdquo;) 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{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{fds131716, Title = {Boone JM, Dobbins JT 3rd (eds). Medical Imaging 1999: Physics of Medical Imaging, SPIE, Bellingham, WA, 1999.}, Year = {1999}, Key = {fds131716} } @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{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{6785097, Author = {Warp, RJ and Godfrey, DJ and III, JTD}, Title = {Applications of matrix inverse tomosynthesis}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {3977}, Pages = {376-383}, Address = {San Diego, CA, USA}, Year = {2000}, 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.}, Key = {6785097} } @article{fds131717, 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, 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, Title = {Dobbins JT 3rd, Boone JM (eds). Medical Imaging 2000: Physics of Medical Imaging, SPIE, Bellingham, WA, 2000.}, Year = {2000}, Key = {fds131746} } @article{7295843, Author = {Godfrey, DJ and Warp, RJ and Dobbins, JT}, Title = {Optimization of matrix inverse tomosynthesis}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {4320}, Pages = {696-704}, Address = {San Diego, CA, USA}, Year = {2001}, 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 III, JTD}, 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 = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {4320}, Pages = {399-408}, Address = {San Diego, CA, USA}, Year = {2001}, 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 III, JTD}, Title = {DQE of direct and indirect digital radiographic systems}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {4320}, Pages = {189-197}, Address = {San Diego, CA, USA}, Year = {2001}, 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 = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {4320}, Pages = {688-695}, Address = {San Diego, CA, USA}, Year = {2001}, 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{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&times;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{fds131718, 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, 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, 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, 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{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{7788104, Author = {Maidment, ADA and Albert, M and Bunch, PC and Cunningham, IA and III, JTD and Gagne, R and Nishikawa, RM and Metter, RV and Wagner, RF}, Title = {Standardization of NPS measurement: Interim report of AAPM TG16}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {5030 I}, Pages = {523-532}, Address = {San Diego, CA, USA}, Year = {2003}, 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{7793732, Author = {Godfrey, DJ and Rader, A and III, JTD}, Title = {Practical strategies for the clinical implementation of matrix inversion tomosynthesis (MITS)}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {5030 I}, Pages = {379-390}, Address = {San Diego, CA, USA}, Year = {2003}, 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{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{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 (&mu;CT) 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 &mu;CT 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 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{fds131725, 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, 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, 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, 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, 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, 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{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{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{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{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{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}, Key = {fds268588} } @article{8163357, Author = {Duryea, J and Neumann, G and Yoshioka, H and III, JTD}, Title = {Digital tomosynthesis rendering of joint margins for arthritis assessment}, Journal = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {5368}, Number = {1}, Pages = {12-18}, Address = {San Diego, CA, USA}, Year = {2004}, 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{fds131769, 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, 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{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}, 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{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{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 III, JTD and Jesneck, JL and Singh, S}, Title = {Digital breast tomosynthesis using an amorphous selenium flat panel detector}, Journal = {Proceedings of SPIE}, Volume = {5745}, Number = {I}, Pages = {529-540}, 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{fds268524, Author = {Baydush, AH and Godfrey, DJ and Oldham, M and III, JTD}, Title = {Initial application of digital tomosynthesis with on-board imaging in radiation oncology}, Journal = {Proceedings of SPIE}, Volume = {5745}, Number = {II}, Pages = {1300-1305}, Year = {2005}, 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 III, JTD}, Title = {Impulse response analysis for several digital tomosynthesis mammography reconstruction algorithms}, Journal = {Proceedings of SPIE}, Volume = {5745}, Number = {I}, Pages = {541-549}, Year = {2005}, 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{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{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&plusmn;0.003 [&plusmn;standard deviation]) was 34% lower than that for the full-field system (0.086 mSv&plusmn;0.001, P&lt;.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&lt;.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{fds131771, 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, 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, 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, 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, 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, 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, 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, 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, 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, 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, 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, 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{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{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 = {6Part5}, Pages = {1932-1932}, Year = {2005}, Month = {June}, url = {http://dx.doi.org/10.1118/1.1997603}, Doi = {10.1118/1.1997603}, Key = {fds327286} } @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{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 = {6Part14}, Pages = {2058-2058}, Year = {2005}, Month = {June}, url = {http://dx.doi.org/10.1118/1.1999682}, Doi = {10.1118/1.1999682}, Key = {fds327412} } @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 = {Medical physics}, Volume = {32}, Number = {7}, 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 < or = 0.2 mm(-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 > or = 0.5 mm(-1), but do result in an asymmetry in the x- and y-NPS at spatial frequencies < or = 0.2 mm(-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{fds268526, Author = {Nasab, NM and Samei, E and III, JTD}, Title = {Biplane correlation imaging for lung nodule detection: Initial human subject results}, Journal = {Proceedings of SPIE}, Volume = {6144 I}, Year = {2006}, 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{fds268527, Author = {Li, CM and III, JTD}, Title = {Preliminary assessment of the temporal subtraction of tomosynthesis images for improved detection of pulmonary nodules}, Journal = {Proceedings of SPIE}, Volume = {6142 III}, Year = {2006}, 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 III, JTD}, Title = {Noise power spectrum analysis for several digital breast tomosynthesis reconstruction algorithms}, Journal = {Proceedings of SPIE}, Volume = {6142 III}, Year = {2006}, 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 III, JTD}, Title = {Gaussian frequency blending algorithm with Matrix Inversion Tomosynthesis (MITS) and Filtered Back Projection (FBP) for better digital breast tomosynthesis reconstruction}, Journal = {Proceedings of SPIE}, Volume = {6142 I}, Year = {2006}, 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{fds172337, 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, 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, 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, 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{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{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{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{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{fds268517, Author = {Ranger, NT and Samei, E and Dobbins, JT and Ravin, CE}, Title = {Assessment of detective quantum efficiency: Inter-comparison of IEC 62220-1 with representative prior methods}, Journal = {Medical physics}, Volume = {33}, Number = {6}, Pages = {2007-2007}, Year = {2006}, Month = {June}, 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}, 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 = {6Part3}, Pages = {2001-2001}, Year = {2006}, Month = {June}, url = {http://dx.doi.org/10.1118/1.2240260}, Doi = {10.1118/1.2240260}, Key = {fds327411} } @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{fds268530, Author = {Chen, Y and Lo, JY and Ranger, NT and Samei, E and III, JTD}, Title = {Methodology of NEQ (f) analysis for optimization and comparison of digital breast tomosynthesis acquisition techniques and reconstruction algorithms}, Journal = {Proceedings of SPIE}, Volume = {6510}, Number = {PART 1}, Year = {2007}, 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{fds268529, Author = {Li, CM and III, JTD}, Title = {Methodology for determining dose reduction for chest tomosynthesis}, Journal = {Proceedings of SPIE}, Volume = {6510}, Number = {PART 2}, Year = {2007}, 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{fds268531, Author = {Chen, Y and Lo, JY and III, JTD}, 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}, Year = {2007}, 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{fds172341, 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, 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{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 III, DJT and Samei, E}, Title = {New developments in digital breast tomosynthesis}, Journal = {Medical physics}, Volume = {34}, Number = {6}, Pages = {2518-2518}, Year = {2007}, Month = {June}, 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}, Doi = {10.1118/1.2761222}, Key = {fds268518} } @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{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 = {6Part18}, Pages = {2564-2564}, Year = {2007}, Month = {June}, 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{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{fds268532, Author = {Li, CM and Segars, WP and Lo, JY and Veress, AI and Boone, JM and III, JTD}, Title = {Three-dimensional computer generated breast phantom based on empirical data}, Journal = {Proceedings of SPIE}, Volume = {6913}, Year = {2008}, 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{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{fds172322, 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, 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{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{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{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{fds268533, Author = {Li, CM and Segars, WP and Lo, JY and Veress, AI and Boone, JM and III, JTD}, Title = {Computerized 3D breast phantom with enhanced High-Resolution detail}, Journal = {Proceedings of SPIE}, Volume = {7258}, Year = {2009}, 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 III, JTD 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 = {Proceedings of SPIE}, Volume = {7258}, Year = {2009}, 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{fds172323, 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, 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, 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, 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{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 = {6Part22}, Pages = {2719-2719}, Year = {2009}, Month = {June}, url = {http://dx.doi.org/10.1118/1.3182318}, Doi = {10.1118/1.3182318}, Key = {fds327410} } @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{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{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{fds268556, Author = {Dobbins, JT and McAdams, HP}, Title = {Chest tomosynthesis: technical principles and clinical update.}, Journal = {European Journal of Radiology}, 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{fds268520, Author = {III, DJT 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 = {Proceedings of SPIE - The International Society for Optical Engineering}, Volume = {7622}, Year = {2010}, 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}, Doi = {10.1117/12.844293}, Key = {fds268520} } @article{fds172346, 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{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 = {6Part7}, Pages = {3439-3440}, Year = {2010}, Month = {June}, url = {http://dx.doi.org/10.1118/1.3469440}, Doi = {10.1118/1.3469440}, Key = {fds327409} } @article{fds268535, Author = {Lin, Y and Samei, E and Luo, H and Iii, JTD 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 = {Proceedings of SPIE}, Volume = {7961}, Year = {2011}, 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 Iii, JTD}, Title = {Refinement of motion correction strategies for lower-cost CT for under-resourced regions of the world}, Journal = {Proceedings of SPIE}, Volume = {7961}, Year = {2011}, 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 = {III, JTD and Wells, JR}, Title = {Correlated-polarity noise reduction: Feasibility of a new statistical approach to reduce image noise}, Journal = {Proceedings of SPIE}, Volume = {7961}, Year = {2011}, 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{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 = {Physics in Medicine and Biology}, 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{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{fds268538, Author = {Kiarashi, N and Lin, Y and Segars, WP and Ghate, SV and Ikejimba, L and Chen, B and Lo, JY and Iii, JTD and Nolte, LW and Samei, E}, Title = {Development of a dynamic 4D anthropomorphic breast phantom for contrast-based breast imaging}, Journal = {Proceedings of SPIE}, Volume = {8313}, Year = {2012}, 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{fds268540, Author = {Wang, J and III, JTD and Li, Q}, Title = {Automated lung segmentation in digital chest tomosynthesis}, Journal = {Medical physics}, Volume = {39}, Number = {2}, Pages = {732-741}, Year = {2012}, 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. © 2012 American Association of Physicists in Medicine.}, 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 = {Journal of Digital 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{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{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 = {6Part27}, Pages = {3954-3954}, Year = {2012}, Month = {June}, url = {http://dx.doi.org/10.1118/1.4736138}, 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 = {6Part23}, Pages = {3894-3894}, Year = {2012}, Month = {June}, url = {http://dx.doi.org/10.1118/1.4735895}, 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 = {6Part23}, Pages = {3893-3893}, Year = {2012}, Month = {June}, url = {http://dx.doi.org/10.1118/1.4735892}, Doi = {10.1118/1.4735892}, Key = {fds327408} } @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 = {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.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.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.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{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{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 = {Proceedings of SPIE}, Volume = {8668}, Year = {2013}, 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{fds268510, Author = {Wells, JR and III, JTD}, Title = {Preliminary investigation of the frequency response and distortion properties of nonlinear image processing algorithms}, Journal = {Proceedings of SPIE}, Volume = {8668}, 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{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 = {Proceedings of SPIE}, Volume = {8668}, 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{fds268515, Author = {Godfrey, DJ and McAdams, HP and Dobbins, JT}, Title = {The effect of averaging adjacent planes for artifact reduction in matrix inversion tomosynthesis.}, 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{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.}, 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{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 = {6Part32}, Pages = {527-527}, Year = {2013}, Month = {June}, url = {http://dx.doi.org/10.1118/1.4815727}, Doi = {10.1118/1.4815727}, Key = {fds327405} } @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 = {Medical physics}, Volume = {40}, Number = {9}, Pages = {091906}, Year = {2013}, Month = {September}, ISSN = {0094-2405}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24007157}, Abstract = {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.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.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.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{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 = {Proceedings of SPIE}, Volume = {9033}, 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{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 = {Proceedings of SPIE}, Volume = {9033}, 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{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 Transactions on Medical 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{fds268504, Author = {Dobbins, JT and Frush, DP and Kigongo, CJN and MacFall, JR and Reiman, RE and Trahey, GE and Dobbins, JT and Frush, DP and Kigongo, CJN and MacFall, JR and Reiman, RE and Trahey, GE}, Title = {Medical imaging safety in the developing worldMedical imaging safety in the developing world}, Volume = {9781461406044}, Pages = {41-60}, Booktitle = {Radiology in Global Health: Strategies, Implementation, and Applications}, Year = {2014}, Month = {October}, ISBN = {9781461406044}, url = {http://dx.doi.org/10.1007/978-1-4614-0604-4_7}, Abstract = {© 2014 Springer Science+Business Media New York. All rights are reserved. 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 unnecessar ily, 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{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 = {Medical physics}, Volume = {43}, Number = {1}, Pages = {23}, Year = {2016}, Month = {January}, ISSN = {0094-2405}, url = {http://dx.doi.org/10.1118/1.4937597}, Abstract = {To create a database of highly realistic and anatomically variable 3D virtual breast phantoms based on dedicated breast computed tomography (bCT) data.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.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.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{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{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 / American College of 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} }