Publications of Anuj J Kapadia    :chronological  alphabetical  by type listing:

%%    
@article{fds328153,
   Author = {Fu, W and Sturgeon, GM and Agasthya, G and Segars, WP and Kapadia, AJ and Samei, E},
   Title = {Breast dose reduction with organ-based, wide-angle tube
             current modulated CT.},
   Journal = {Journal of medical imaging (Bellingham, Wash.)},
   Volume = {4},
   Number = {3},
   Pages = {031208},
   Year = {2017},
   Month = {July},
   url = {http://dx.doi.org/10.1117/1.jmi.4.3.031208},
   Abstract = {This study aimed to estimate the organ dose reduction
             potential for organ-dose-based tube current modulated (ODM)
             thoracic computed tomography (CT) with a wide dose reduction
             arc. Twenty-one computational anthropomorphic phantoms
             (XCAT) were used to create a virtual patient population with
             clinical anatomic variations. The phantoms were created
             based on patient images with normal anatomy (age range: 27
             to 66 years, weight range: 52.0 to 105.8 kg). For each
             phantom, two breast tissue compositions were simulated:
             [Formula: see text] and [Formula: see text]
             (glandular-to-adipose ratio). A validated Monte Carlo
             program (PENELOPE, Universitat de Barcelona, Spain) was used
             to estimate the organ dose for standard tube current
             modulation (TCM) (SmartmA, GE Healthcare) and ODM (GE
             Healthcare) for a commercial CT scanner (Revolution, GE
             Healthcare) using a typical clinical thoracic CT protocol.
             Both organ dose and [Formula: see text]-to-organ dose
             conversion coefficients ([Formula: see text] factors) were
             compared between TCM and ODM. ODM significantly reduced all
             radiosensitive organ doses ([Formula: see text]). The breast
             dose was reduced by [Formula: see text]. For [Formula: see
             text] factors, organs in the anterior region (e.g., thyroid
             and stomach) exhibited substantial decreases, and the
             medial, distributed, and posterior region saw either an
             increase of less than 5% or no significant change. ODM
             significantly reduced organ doses especially for
             radiosensitive superficial anterior organs such as the
             breasts.},
   Doi = {10.1117/1.jmi.4.3.031208},
   Key = {fds328153}
}

@article{fds328154,
   Author = {Hoye, J and Zhang, Y and Agasthya, G and Sturgeon, G and Kapadia, A and Segars, WP and Samei, E},
   Title = {Organ dose variability and trends in tomosynthesis and
             radiography.},
   Journal = {Journal of medical imaging (Bellingham, Wash.)},
   Volume = {4},
   Number = {3},
   Pages = {031207},
   Year = {2017},
   Month = {July},
   url = {http://dx.doi.org/10.1117/1.jmi.4.3.031207},
   Abstract = {The purpose of this study was to investigate relationships
             between patient attributes and organ dose for a population
             of computational phantoms for 20 tomosynthesis and
             radiography protocols. Organ dose was estimated from 54
             adult computational phantoms (age: 18 to 78 years, weight 52
             to 117 kg) using a validated Monte-Carlo simulation
             (PENELOPE) of a system capable of performing tomosynthesis
             and radiography. The geometry and field of view for each
             exam were modeled to match clinical protocols. For each
             protocol, the energy deposited in each organ was estimated
             by the simulations, converted to dose units, and then
             normalized by exposure in air. Dose to radiosensitive organs
             was studied as a function of average patient thickness in
             the region of interest and as a function of body mass index.
             For tomosynthesis, organ doses were also studied as a
             function of x-ray tube position. This work developed
             comprehensive information for organ dose dependencies across
             a range of tomosynthesis and radiography protocols. The
             results showed a protocol-dependent exponential decrease
             with an increasing patient size. There was a variability in
             organ dose across the patient population, which should be
             incorporated in the metrology of organ dose. The results can
             be used to prospectively and retrospectively estimate organ
             dose for tomosynthesis and radiography.},
   Doi = {10.1117/1.jmi.4.3.031207},
   Key = {fds328154}
}

@article{fds326927,
   Author = {Spencer, JR and Carter, JE and Leung, CK and McCall, SJ and Greenberg,
             JA and Kapadia, AJ},
   Title = {Coded aperture coherent scatter spectral imaging for
             assessment of breast cancers: An ex-vivo
             demonstration},
   Journal = {Proceedings of SPIE},
   Volume = {10132},
   Year = {2017},
   Month = {January},
   ISBN = {9781510607095},
   url = {http://dx.doi.org/10.1117/12.2253975},
   Abstract = {© 2017 SPIE. A Coded Aperture Coherent Scatter Spectral
             Imaging (CACSSI) system was developed in our group to
             differentiate cancer and healthy tissue in the breast. The
             utility of the experimental system was previously
             demonstrated using anthropomorphic breast phantoms and
             breast biopsy specimens. Here we demonstrate CACSSI utility
             in identifying tumor margins in real time using breast
             lumpectomy specimens. Fresh lumpectomy specimens were
             obtained from Surgical Pathology with the suspected
             cancerous area designated on the specimen. The specimens
             were scanned using CACSSI to obtain spectral scatter
             signatures at multiple locations within the tumor and
             surrounding tissue. The spectral reconstructions were
             matched with literature form-factors to classify the tissue
             as cancerous or non-cancerous. The findings were then
             compared against pathology reports to confirm the presence
             and location of the tumor. The system was found to be
             capable of consistently differentiating cancerous and
             healthy regions in the breast with spatial resolution of 5
             mm. Tissue classification results from the scanned specimens
             could be correlated with pathology results. We now aim to
             develop CACSSI as a clinical imaging tool to aid breast
             cancer assessment and other diagnostic purposes.},
   Doi = {10.1117/12.2253975},
   Key = {fds326927}
}

@article{fds326928,
   Author = {Fu, W and Sturgeon, GM and Agasthya, G and Segars, WP and Kapadia, AJ and Samei, E},
   Title = {Estimation of breast dose reduction potential for
             organ-based tube current modulated CT with wide dose
             reduction arc},
   Journal = {Proceedings of SPIE},
   Volume = {10132},
   Year = {2017},
   Month = {January},
   ISBN = {9781510607095},
   url = {http://dx.doi.org/10.1117/12.2255797},
   Abstract = {© 2017 SPIE. This study aimed to estimate the organ dose
             reduction potential for organ-dose-based tube current
             modulated (ODM) thoracic CT with wide dose reduction arc.
             Twenty-one computational anthropomorphic phantoms (XCAT, age
             range: 27- 75 years, weight range: 52.0-105.8 kg) were used
             to create a virtual patient population with clinical
             anatomic variations. For each phantom, two breast tissue
             compositions were simulated: 50/50 and 20/80
             (glandular-to-adipose ratio). A validated Monte Carlo
             program was used to estimate the organ dose for standard
             tube current modulation (TCM) (SmartmA, GE Healthcare) and
             ODM (GE Healthcare) for a commercial CT scanner (Revolution,
             GE Healthcare) with explicitly modeled tube current
             modulation profile, scanner geometry, bowtie filtration, and
             source spectrum. Organ dose was determined using a typical
             clinical thoracic CT protocol. Both organ dose and CTDI vol
             -to-organ dose conversion coefficients (h factors) were
             compared between TCM and ODM. ODM significantly reduced all
             radiosensitive organ doses (p < 0.01). The breast dose was
             reduced by 30±2%. For h factors, organs in the anterior
             region (e.g. thyroid, stomach) exhibited substantial
             decreases, and the medial, distributed, and posterior region
             either saw an increase or no significant change. The
             organ-dose-based tube current modulation significantly
             reduced organ doses especially for radiosensitive
             superficial anterior organs such as the breasts.},
   Doi = {10.1117/12.2255797},
   Key = {fds326928}
}

@article{fds326929,
   Author = {Abadi, E and Sturgeon, GM and Agasthya, G and Harrawood, B and Hoeschen,
             C and Kapadia, A and Segars, WP and Samei, E},
   Title = {Airways, vasculature, and interstitial tissue: Anatomically
             informed computational modeling of human lungs for virtual
             clinical trials},
   Journal = {Proceedings of SPIE},
   Volume = {10132},
   Year = {2017},
   Month = {January},
   ISBN = {9781510607095},
   url = {http://dx.doi.org/10.1117/12.2254739},
   Abstract = {© 2017 SPIE. This study aimed to model virtual human lung
             phantoms including both non-parenchymal and parenchymal
             structures. Initial branches of the non-parenchymal
             structures (airways, arteries, and veins) were segmented
             from anatomical data in each lobe separately. A
             volume-filling branching algorithm was utilized to grow the
             higher generations of the airways and vessels to the level
             of terminal branches. The diameters of the airways and
             vessels were estimated using established relationships
             between flow rates and diameters. The parenchyma was modeled
             based on secondary pulmonary lobule units. Polyhedral shapes
             with variable sizes were modeled, and the borders were
             assigned to interlobular septa. A heterogeneous background
             was added inside these units using a non-parametric texture
             synthesis algorithm which was informed by a high-resolution
             CT lung specimen dataset. A voxelized based CT simulator was
             developed to create synthetic helical CT images of the
             phantom with different pitch values. Results showed the
             progressive degradation in depiction of lung details with
             increased pitch. Overall, the enhanced lung models combined
             with the XCAT phantoms prove to provide a powerful toolset
             to perform virtual clinical trials in the context of
             thoracic imaging. Such trials, not practical using clinical
             datasets or simplistic phantoms, can quantitatively evaluate
             and optimize advanced imaging techniques towards
             patient-based care.},
   Doi = {10.1117/12.2254739},
   Key = {fds326929}
}

@article{fds326926,
   Author = {Hoye, J and Zhang, Y and Agasthya, G and Sturgeon, G and Kapadia, A and Segars, WP and Samei, E},
   Title = {An atlas-based organ dose estimator for tomosynthesis and
             radiography},
   Journal = {Proceedings of SPIE},
   Volume = {10132},
   Year = {2017},
   Month = {January},
   ISBN = {9781510607095},
   url = {http://dx.doi.org/10.1117/12.2255583},
   Abstract = {© 2017 SPIE. The purpose of this study was to provide
             patient-specific organ dose estimation based on an atlas of
             human models for twenty tomosynthesis and radiography
             protocols. The study utilized a library of 54 adult
             computational phantoms (age: 18-78 years, weight 52-117 kg)
             and a validated Monte-Carlo simulation (PENELOPE) of a
             tomosynthesis and radiography system to estimate organ dose.
             Positioning of patient anatomy was based on radiographic
             positioning handbooks. The field of view for each exam was
             calculated to include relevant organs per protocol. Through
             simulations, the energy deposited in each organ was binned
             to estimate normalized organ doses into a reference
             database. The database can be used as the basis to devise a
             dose calculator to predict patient-specific organ dose
             values based on kVp, mAs, exposure in air, and patient
             habitus for a given protocol. As an example of the utility
             of this tool, dose to an organ was studied as a function of
             average patient thickness in the field of view for a given
             exam and as a function of Body Mass Index (BMI). For
             tomosynthesis, organ doses can also be studied as a function
             of x-ray tube position. This work developed comprehensive
             information for organ dose dependencies across tomosynthesis
             and radiography. There was a general exponential decrease
             dependency with increasing patient size that is highly
             protocol dependent. There was a wide range of variability in
             organ dose across the patient population, which needs to be
             incorporated in the metrology of organ dose.},
   Doi = {10.1117/12.2255583},
   Key = {fds326926}
}

@article{fds325758,
   Author = {Lakshmanan, MN and Greenberg, JA and Samei, E and Kapadia,
             AJ},
   Title = {Accuracy assessment and characterization of x-ray coded
             aperture coherent scatter spectral imaging for breast cancer
             classification.},
   Journal = {Journal of medical imaging (Bellingham, Wash.)},
   Volume = {4},
   Number = {1},
   Pages = {013505},
   Year = {2017},
   Month = {January},
   url = {http://dx.doi.org/10.1117/1.jmi.4.1.013505},
   Abstract = {Although transmission-based x-ray imaging is the most
             commonly used imaging approach for breast cancer detection,
             it exhibits false negative rates higher than 15%. To improve
             cancer detection accuracy, x-ray coherent scatter computed
             tomography (CSCT) has been explored to potentially detect
             cancer with greater consistency. However, the 10-min scan
             duration of CSCT limits its possible clinical applications.
             The coded aperture coherent scatter spectral imaging
             (CACSSI) technique has been shown to reduce scan time
             through enabling single-angle imaging while providing high
             detection accuracy. Here, we use Monte Carlo simulations to
             test analytical optimization studies of the CACSSI
             technique, specifically for detecting cancer in ex vivo
             breast samples. An anthropomorphic breast tissue phantom was
             modeled, a CACSSI imaging system was virtually simulated to
             image the phantom, a diagnostic voxel classification
             algorithm was applied to all reconstructed voxels in the
             phantom, and receiver-operator characteristics analysis of
             the voxel classification was used to evaluate and
             characterize the imaging system for a range of parameters
             that have been optimized in a prior analytical study. The
             results indicate that CACSSI is able to identify the
             distribution of cancerous and healthy tissues (i.e.,
             fibroglandular, adipose, or a mix of the two) in tissue
             samples with a cancerous voxel identification
             area-under-the-curve of 0.94 through a scan lasting less
             than 10 s per slice. These results show that coded aperture
             scatter imaging has the potential to provide scatter images
             that automatically differentiate cancerous and healthy
             tissue within ex vivo samples. Furthermore, the results
             indicate potential CACSSI imaging system configurations for
             implementation in subsequent imaging development
             studies.},
   Doi = {10.1117/1.jmi.4.1.013505},
   Key = {fds325758}
}

@article{fds319491,
   Author = {Lakshmanan, MN and Greenberg, JA and Samei, E and Kapadia,
             AJ},
   Title = {Design and implementation of coded aperture coherent scatter
             spectral imaging of cancerous and healthy breast tissue
             samples.},
   Journal = {Journal of medical imaging (Bellingham, Wash.)},
   Volume = {3},
   Number = {1},
   Pages = {013505},
   Year = {2016},
   Month = {January},
   url = {http://dx.doi.org/10.1117/1.jmi.3.1.013505},
   Abstract = {A scatter imaging technique for the differentiation of
             cancerous and healthy breast tissue in a heterogeneous
             sample is introduced in this work. Such a technique has
             potential utility in intraoperative margin assessment during
             lumpectomy procedures. In this work, we investigate the
             feasibility of the imaging method for tumor classification
             using Monte Carlo simulations and physical experiments. The
             coded aperture coherent scatter spectral imaging technique
             was used to reconstruct three-dimensional (3-D) images of
             breast tissue samples acquired through a single-position
             snapshot acquisition, without rotation as is required in
             coherent scatter computed tomography. We perform a
             quantitative assessment of the accuracy of the cancerous
             voxel classification using Monte Carlo simulations of the
             imaging system; describe our experimental implementation of
             coded aperture scatter imaging; show the reconstructed
             images of the breast tissue samples; and present
             segmentations of the 3-D images in order to identify the
             cancerous and healthy tissue in the samples. From the Monte
             Carlo simulations, we find that coded aperture scatter
             imaging is able to reconstruct images of the samples and
             identify the distribution of cancerous and healthy tissues
             (i.e., fibroglandular, adipose, or a mix of the two) inside
             them with a cancerous voxel identification sensitivity,
             specificity, and accuracy of 92.4%, 91.9%, and 92.0%,
             respectively. From the experimental results, we find that
             the technique is able to identify cancerous and healthy
             tissue samples and reconstruct differential coherent scatter
             cross sections that are highly correlated with those
             measured by other groups using x-ray diffraction. Coded
             aperture scatter imaging has the potential to provide
             scatter images that automatically differentiate cancerous
             and healthy tissue inside samples within a time on the order
             of a minute per slice.},
   Doi = {10.1117/1.jmi.3.1.013505},
   Key = {fds319491}
}

@article{fds320201,
   Author = {Morris, RE and Albanese, KE and Lakshmanan, MN and McCall, SJ and Greenberg, JA and Kapadia, AJ},
   Title = {Validation of coded aperture coherent scatter spectral
             imaging for normal and neoplastic breast tissues via
             surgical pathology},
   Journal = {Proceedings of SPIE},
   Volume = {9783},
   Year = {2016},
   Month = {January},
   ISBN = {9781510600188},
   url = {http://dx.doi.org/10.1117/12.2216974},
   Abstract = {© 2016 SPIE. This study intends to validate the sensitivity
             and specificity of coded aperture coherent scatter spectral
             imaging (CACSSI) by comparison to standard histological
             preparation and pathologic analysis methods used to
             differentiate normal and neoplastic breast tissues. A
             composite overlay of the CACSSI rendered image and
             pathologist interpreted stained sections validate the
             ability of CACSSI to differentiate normal and neoplastic
             breast structures ex-vivo. Via comparison to pathologist
             annotated slides, the CACSSI system may be further optimized
             to maximize sensitivity and specificity for differentiation
             of breast carcinomas.},
   Doi = {10.1117/12.2216974},
   Key = {fds320201}
}

@article{fds321500,
   Author = {Lakshmanan, MN and Morris, RE and Greenberg, JA and Samei, E and Kapadia, AJ},
   Title = {Coded aperture coherent scatter imaging for breast cancer
             detection: A Monte Carlo evaluation},
   Journal = {Proceedings of SPIE},
   Volume = {9783},
   Year = {2016},
   Month = {January},
   ISBN = {9781510600188},
   url = {http://dx.doi.org/10.1117/12.2216482},
   Abstract = {© 2016 SPIE. It is known that conventional x-ray imaging
             provides a maximum contrast between cancerous and healthy
             fibroglandular breast tissues of 3% based on their linear
             x-ray attenuation coefficients at 17.5 keV, whereas coherent
             scatter signal provides a maximum contrast of 19% based on
             their differential coherent scatter cross sections.
             Therefore in order to exploit this potential contrast, we
             seek to evaluate the performance of a coded- aperture
             coherent scatter imaging system for breast cancer detection
             and investigate its accuracy using Monte Carlo simulations.
             In the simulations we modeled our experimental system, which
             consists of a raster-scanned pencil beam of x-rays, a
             bismuth-tin coded aperture mask comprised of a repeating
             slit pattern with 2-mm periodicity, and a linear-array of
             128 detector pixels with 6.5-keV energy resolution. The
             breast tissue that was scanned comprised a 3-cm sample taken
             from a patient-based XCAT breast phantom containing a
             tomosynthesis- based realistic simulated lesion. The
             differential coherent scatter cross section was
             reconstructed at each pixel in the image using an iterative
             reconstruction algorithm. Each pixel in the reconstructed
             image was then classified as being either air or the type of
             breast tissue with which its normalized reconstructed
             differential coherent scatter cross section had the highest
             correlation coefficient. Comparison of the final tissue
             classification results with the ground truth image showed
             that the coded aperture imaging technique has a cancerous
             pixel detection sensitivity (correct identification of
             cancerous pixels), specificity (correctly ruling out healthy
             pixels as not being cancer) and accuracy of 92.4%, 91.9% and
             92.0%, respectively. Our Monte Carlo evaluation of our
             experimental coded aperture coherent scatter imaging system
             shows that it is able to exploit the greater contrast
             available from coherently scattered x-rays to increase the
             accuracy of detecting cancerous regions within the
             breast.},
   Doi = {10.1117/12.2216482},
   Key = {fds321500}
}

@article{fds319492,
   Author = {Odinaka, I and O'Sullivan, JA and Politte, DG and MacCabe, KP and Kaganovsky, Y and Greenberg, JA and Lakshmanan, MN and Krishnamurthy,
             K and Kapadia, AJ and Carin, L and Brady, DJ},
   Title = {Joint System and Algorithm Design for Computationally
             Efficient Fan Beam Coded Aperture X-ray Coherent Scatter
             Imaging.},
   Journal = {CoRR},
   Volume = {abs/1603.06400},
   Year = {2016},
   Key = {fds319492}
}

@article{fds319493,
   Author = {Lakshmanan, MN and Harrawood, BP and Samei, E and Kapadia,
             AJ},
   Title = {Volumetric x-ray coherent scatter imaging of cancer in
             resected breast tissue: a Monte Carlo study using virtual
             anthropomorphic phantoms.},
   Journal = {Physics in Medicine and Biology},
   Volume = {60},
   Number = {16},
   Pages = {6355-6370},
   Year = {2015},
   Month = {August},
   url = {http://dx.doi.org/10.1088/0031-9155/60/16/6355},
   Abstract = {Breast cancer patients undergoing surgery often choose to
             have a breast conserving surgery (BCS) instead of mastectomy
             for removal of only the breast tumor. If post-surgical
             analysis such as histological assessment of the resected
             tumor reveals insufficient healthy tissue margins around the
             cancerous tumor, the patient must undergo another surgery to
             remove the missed tumor tissue. Such re-excisions are
             reported to occur in 20%-70% of BCS patients. A real-time
             surgical margin assessment technique that is fast and
             consistently accurate could greatly reduce the number of
             re-excisions performed in BCS. We describe here a tumor
             margin assessment method based on x-ray coherent scatter
             computed tomography (CSCT) imaging and demonstrate its
             utility in surgical margin assessment using Monte Carlo
             simulations. A CSCT system was simulated in GEANT4 and used
             to simulate two virtual anthropomorphic CSCT scans of
             phantoms resembling surgically resected tissue. The
             resulting images were volume-rendered and found to
             distinguish cancerous tumors embedded in complex
             distributions of adipose and fibroglandular breast tissue
             (as is expected in the breast). The images exhibited
             sufficient spatial and spectral (i.e. momentum transfer)
             resolution to classify the tissue in any given voxel as
             healthy or cancerous. ROC analysis of the classification
             accuracy revealed an area under the curve of up to 0.97.
             These results indicate that coherent scatter imaging is
             promising as a possible fast and accurate surgical margin
             assessment technique.},
   Doi = {10.1088/0031-9155/60/16/6355},
   Key = {fds319493}
}

@article{fds319494,
   Author = {Greenberg, JA and Lakshmanan, MN and Brady, DJ and Kapadia,
             AJ},
   Title = {Optimization of a coded aperture coherent scatter spectral
             imaging system for medical imaging},
   Journal = {Proceedings of SPIE},
   Volume = {9412},
   Year = {2015},
   Month = {January},
   ISBN = {9781628415025},
   url = {http://dx.doi.org/10.1117/12.2082110},
   Abstract = {© 2015 SPIE. Coherent scatter X-ray imaging is a technique
             that provides spatially-resolved information about the
             molecular structure of the material under investigation,
             yielding material-specific contrast that can aid medical
             diagnosis and inform treatment. In this study, we
             demonstrate a coherent-scatter imaging approach based on the
             use of coded apertures (known as coded aperture coherent
             scatter spectral imaging 1, 2 ) that enables fast,
             dose-efficient, high-resolution scatter imaging of
             biologically-relevant materials. Specifically, we discuss
             how to optimize a coded aperture coherent scatter imaging
             system for a particular set of objects and materials,
             describe and characterize our experimental system, and use
             the system to demonstrate automated material detection in
             biological tissue.},
   Doi = {10.1117/12.2082110},
   Key = {fds319494}
}

@article{fds319495,
   Author = {Lakshmanan, MN and Greenberg, JA and Samei, E and Kapadia,
             AJ},
   Title = {Experimental implementation of coded aperture coherent
             scatter spectral imaging of cancerous and healthy breast
             tissue samples},
   Journal = {Proceedings of SPIE},
   Volume = {9412},
   Year = {2015},
   Month = {January},
   ISBN = {9781628415025},
   url = {http://dx.doi.org/10.1117/12.2082318},
   Abstract = {© 2015 SPIE. A fast and accurate scatter imaging technique
             to differentiate cancerous and healthy breast tissue is
             introduced in this work. Such a technique would have
             wide-ranging clinical applications from intra-operative
             margin assessment to breast cancer screening. Coherent
             Scatter Computed Tomography (CSCT) has been shown to
             differentiate cancerous from healthy tissue, but the need to
             raster scan a pencil beam at a series of angles and slices
             in order to reconstruct 3D images makes it prohibitively
             time consuming. In this work we apply the coded aperture
             coherent scatter spectral imaging technique to reconstruct
             3D images of breast tissue samples from experimental data
             taken without the rotation usually required in CSCT. We
             present our experimental implementation of coded aperture
             scatter imaging, the reconstructed images of the breast
             tissue samples and segmentations of the 3D images in order
             to identify the cancerous and healthy tissue inside of the
             samples. We find that coded aperture scatter imaging is able
             to reconstruct images of the samples and identify the
             distribution of cancerous and healthy tissues (i.e.,
             fibroglandular, adipose, or a mix of the two) inside of
             them. Coded aperture scatter imaging has the potential to
             provide scatter images that automatically differentiate
             cancerous and healthy tissue inside of ex vivo samples
             within a time on the order of a minute.},
   Doi = {10.1117/12.2082318},
   Key = {fds319495}
}

@article{fds319496,
   Author = {Lakshmanan, MN and Harrawood, BP and Rusev, G and Agasthya, GA and Kapadia, AJ},
   Title = {Simulations of nuclear resonance fluorescence in
             Geant4},
   Journal = {Nuclear Instruments and Methods in Physics Research Section
             A: Accelerators, Spectrometers, Detectors and Associated
             Equipment},
   Volume = {763},
   Pages = {89-96},
   Year = {2014},
   Month = {November},
   url = {http://dx.doi.org/10.1016/j.nima.2014.06.030},
   Doi = {10.1016/j.nima.2014.06.030},
   Key = {fds319496}
}

@article{fds319497,
   Author = {Harrawood, BP and Agasthya, GA and Lakshmanan, MN and Raterman, G and Kapadia, AJ},
   Title = {Geant4 distributed computing for compact
             clusters},
   Journal = {Nuclear Instruments and Methods in Physics Research Section
             A: Accelerators, Spectrometers, Detectors and Associated
             Equipment},
   Volume = {764},
   Pages = {11-17},
   Year = {2014},
   Month = {November},
   url = {http://dx.doi.org/10.1016/j.nima.2014.07.014},
   Doi = {10.1016/j.nima.2014.07.014},
   Key = {fds319497}
}

@article{fds319498,
   Author = {Lakshmanan, MN and Kapadia, AJ and Sahbaee, P and Wolter, SD and Harrawood, BP and Brady, D and Samei, E},
   Title = {An X-ray scatter system for material identification in
             cluttered objects: A Monte Carlo simulation
             study},
   Journal = {Nuclear Instruments and Methods in Physics Research Section
             B: Beam Interactions with Materials and Atoms},
   Volume = {335},
   Pages = {31-38},
   Year = {2014},
   Month = {September},
   url = {http://dx.doi.org/10.1016/j.nimb.2014.05.021},
   Doi = {10.1016/j.nimb.2014.05.021},
   Key = {fds319498}
}

@article{fds319499,
   Author = {Belley, MD and Segars, WP and Kapadia, AJ},
   Title = {Assessment of individual organ doses in a realistic human
             phantom from neutron and gamma stimulated spectroscopy of
             the breast and liver.},
   Journal = {Medical physics},
   Volume = {41},
   Number = {6},
   Pages = {063902},
   Year = {2014},
   Month = {June},
   url = {http://dx.doi.org/10.1118/1.4873684},
   Abstract = {Understanding the radiation dose to a patient is essential
             when considering the use of an ionizing diagnostic imaging
             test for clinical diagnosis and screening. Using Monte Carlo
             simulations, the authors estimated the three-dimensional
             organ-dose distribution from neutron and gamma irradiation
             of the male liver, female liver, and female breasts for
             neutron- and gamma-stimulated spectroscopic imaging.Monte
             Carlo simulations were developed using the Geant4 GATE
             application and a voxelized XCAT human phantom. A male and a
             female whole body XCAT phantom was voxelized into 256 × 256
             × 600 voxels (3.125 × 3.125 × 3.125 mm(3)). A
             monoenergetic rectangular beam of 5.0 MeV neutrons or 7.0
             MeV photons was made incident on a 2 cm thick slice of the
             phantom. The beam was rotated at eight different angles
             around the phantom ranging from 0° to 180°. Absorbed dose
             was calculated for each individual organ in the body and
             dose volume histograms were computed to analyze the absolute
             and relative doses in each organ.The neutron irradiations of
             the liver showed the highest organ dose absorption in the
             liver, with appreciably lower doses in other proximal
             organs. The dose distribution within the irradiated slice
             exhibited substantial attenuation with increasing depth
             along the beam path, attenuating to ~15% of the maximum
             value at the beam exit side. The gamma irradiation of the
             liver imparted the highest organ dose to the stomach wall.
             The dose distribution from the gammas showed a region of
             dose buildup at the beam entrance, followed by a relatively
             uniform dose distribution to all of the deep tissue
             structures, attenuating to ~75% of the maximum value at the
             beam exit side. For the breast scans, both the neutron and
             gamma irradiation registered maximum organ doses in the
             breasts, with all other organs receiving less than 1% of the
             breast dose. Effective doses ranged from 0.22 to 0.37 mSv
             for the neutron scans and 41 to 66 mSv for the gamma
             scans.Neutron and gamma irradiation of a primary target
             organ was found to impart the majority of the total dose to
             the primary target organ (and other large organs) within the
             beam plane and considerably lower dose to proximal organs
             outside of the beam. These results also indicate that
             despite the use of a highly scattering particle such as a
             neutron, the dose from neutron stimulated emission computed
             tomography scans is on par with other clinical imaging
             techniques such as x-ray computed tomography (x-ray CT).
             Given the high nonuniformity in the dose across an organ
             during the neutron scan, care must be taken when computing
             average doses from neutron irradiations. The effective doses
             from neutron scanning were found to be comparable to x-ray
             CT. Further technique modifications are needed to reduce the
             effective dose levels from the gamma scans.},
   Doi = {10.1118/1.4873684},
   Key = {fds319499}
}

@article{fds319500,
   Author = {Lakshmanan, MN and Harrawood, BP and Agasthya, GA and Kapadia,
             AJ},
   Title = {Simulations of breast cancer imaging using gamma-ray
             stimulated emission computed tomography.},
   Journal = {IEEE Transactions on Medical Imaging},
   Volume = {33},
   Number = {2},
   Pages = {546-555},
   Year = {2014},
   Month = {February},
   url = {http://dx.doi.org/10.1109/tmi.2013.2290287},
   Abstract = {Here, we present an innovative imaging technology for breast
             cancer using gamma-ray stimulated spectroscopy based on the
             nuclear resonance fluorescence (NRF) technique. In NRF, a
             nucleus of a given isotope selectively absorbs gamma rays
             with energy exactly equal to one of its quantized energy
             states, emitting an outgoing gamma ray with energy nearly
             identical to that of the incident gamma ray. Due to its
             application of NRF, gamma-ray stimulated spectroscopy is
             sensitive to trace element concentration changes, which are
             suspected to occur at early stages of breast cancer, and
             therefore can be potentially used to noninvasively detect
             and diagnose cancer in its early stages. Using Monte-Carlo
             simulations, we have designed and demonstrated an imaging
             system that uses gamma-ray stimulated spectroscopy for
             visualizing breast cancer. We show that gamma-ray stimulated
             spectroscopy is able to visualize breast cancer lesions
             based primarily on the differences in the concentrations of
             trace elements between diseased and healthy tissue, rather
             than differences in density that are crucial for X-ray
             mammography. The technique shows potential for early breast
             cancer detection; however, improvements are needed in
             gamma-ray laser technology for the technique to become a
             clinically feasible method of detecting and diagnosing
             cancer at early stages.},
   Doi = {10.1109/tmi.2013.2290287},
   Key = {fds319500}
}

@article{fds319501,
   Author = {Lakshmanan, MN and Kapadia, AJ and Harrawood, BP and Brady, D and Samei,
             E},
   Title = {X-ray coherent scatter imaging for surgical margin
             detection: A Monte Carlo study},
   Journal = {Proceedings of SPIE},
   Volume = {9033},
   Year = {2014},
   Month = {January},
   url = {http://dx.doi.org/10.1117/12.2043856},
   Abstract = {Instead of having the entire breast removed (a mastectomy),
             breast cancer patients often receive a breast con-serving
             surgery (BCS) for removal of only the breast tumor. If
             post-surgery analysis reveals ta missed margin around the
             tumor tissue excised through the BCS procedure, the
             physician must often call the patient back for another
             surgery, which is both difficult and risky for the patient.
             If this “margin detectionâ€could be performed
             during the BCS procedure itself, the surgical team could use
             the analysis to ensure that all tumor tissue was removed in
             a single surgery, thereby potentially reducing the number of
             call backs from breast cancer surgery. We describe here a
             potential technique to detect surgical tumor margins in
             breast cancer using x-ray coherent scatter imaging. In this
             study, we demonstrate the imaging ability of this technique
             using Monte Carlo simulations. © 2014 SPIE.},
   Doi = {10.1117/12.2043856},
   Key = {fds319501}
}

@article{fds319502,
   Author = {Kapadia, AJ and Rhee, DJ and Han, Z},
   Title = {Brain imaging using fast neutron spectroscopy},
   Journal = {Proceedings of the 2014 Biomedical Sciences and Engineering
             Conference - 5th Annual ORNL Biomedical Sciences and
             Engineering Conference: Collaborative Biomedical Innovations
             - The Multi-Scale Brain: Spanning Molecular, Cellular,
             Systems, Cognitive, Behavioral, and Clinical Neuroscience,
             BSEC 2014},
   Year = {2014},
   Month = {January},
   ISBN = {9781479941599},
   url = {http://dx.doi.org/10.1109/BSEC.2014.6867741},
   Abstract = {© 2014 IEEE. Most clinical methods of imagin. The brain
             rely on imagin. The anatomic and functional changes
             accompanying disease in brain tissue. This approach,
             although successful, has two limitations: first. The
             abnormality of interest must be large enough to be imaged
             using existing technologies, and second, confirmation o. The
             abnormality usually requires a biopsy. To overcome
             limitations, we describe here a new method of brain imaging
             that uses fast neutrons to imag. The element distribution
             withi. The brain tissue and identify disease based on
             relative concentration gradients in different regions o. The
             brain. The method, called Neutron Stimulated Emission
             Computed Tomography, has been successfully tested previously
             in imaging cancers i. The breast, liver, kidneys and colon.
             Here we describe a study demonstratin. The potential o. The
             technology in detecting deep-seated brain tumors using a
             different signature compared to other imaging
             methods.},
   Doi = {10.1109/BSEC.2014.6867741},
   Key = {fds319502}
}

@article{fds319503,
   Author = {Viana, RS and Agasthya, GA and Yoriyaz, H and Kapadia,
             AJ},
   Title = {3D element imaging using NSECT for the detection of renal
             cancer: a simulation study in MCNP.},
   Journal = {Physics in Medicine and Biology},
   Volume = {58},
   Number = {17},
   Pages = {5867-5883},
   Year = {2013},
   Month = {September},
   url = {http://dx.doi.org/10.1088/0031-9155/58/17/5867},
   Abstract = {This work describes a simulation study investigating the
             application of neutron stimulated emission computed
             tomography (NSECT) for noninvasive 3D imaging of renal
             cancer in vivo. Using MCNP5 simulations, we describe a
             method of diagnosing renal cancer in the body by mapping the
             3D distribution of elements present in tumors using the
             NSECT technique. A human phantom containing the kidneys and
             other major organs was modeled in MCNP5. The element
             composition of each organ was based on values reported in
             literature. The two kidneys were modeled to contain elements
             reported in renal cell carcinoma (RCC) and healthy kidney
             tissue. Simulated NSECT scans were executed to determine the
             3D element distribution of the phantom body. Elements
             specific to RCC and healthy kidney tissue were then analyzed
             to identify the locations of the diseased and healthy
             kidneys and generate tomographic images of the tumor. The
             extent of the RCC lesion inside the kidney was determined
             using 3D volume rendering. A similar procedure was used to
             generate images of each individual organ in the body. Six
             isotopes were studied in this work - (32)S, (12)C, (23)Na,
             (14)N, (31)P and (39)K. The results demonstrated that
             through a single NSECT scan performed in vivo, it is
             possible to identify the location of the kidneys and other
             organs within the body, determine the extent of the tumor
             within the organ, and to quantify the differences between
             cancer and healthy tissue-related isotopes with p ≤ 0.05.
             All of the images demonstrated appropriate concentration
             changes between the organs, with some discrepancy observed
             in (31)P, (39)K and (23)Na. The discrepancies were likely
             due to the low concentration of the elements in the tissue
             that were below the current detection sensitivity of the
             NSECT technique.},
   Doi = {10.1088/0031-9155/58/17/5867},
   Key = {fds319503}
}

@article{fds327413,
   Author = {Belley, M and Segars, P and Kapadia, A},
   Title = {SU-C-144-04: Whole Body and Relative Organ Dose Values From
             Neutron and Gamma Irradiation of the Liver and Breast in a
             Voxelized Anthropomorphic Phantom Using Monte Carlo
             Methods},
   Journal = {Medical physics},
   Volume = {40},
   Number = {6Part3},
   Pages = {99-99},
   Year = {2013},
   Month = {June},
   url = {http://dx.doi.org/10.1118/1.4813993},
   Doi = {10.1118/1.4813993},
   Key = {fds327413}
}

@article{fds319504,
   Author = {Rhee, DJ and Agasthya, GA and Kapadia, AJ},
   Title = {Neutron stimulated emission computed tomography for brain
             cancer imaging},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Year = {2013},
   Month = {January},
   url = {http://dx.doi.org/10.1109/NSSMIC.2013.6829159},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) uses
             photons emitted from inelastic scattering of neutrons with
             biological objects to quantify the elemental composition of
             the object and reconstruct an image. Previously, NSECT has
             been used to detect liver and breast disease in vivo. In
             this study, we investigated the capability of imaging brain
             tumors using NSECT. A GEANT4 simulation was developed to
             model the brain, skull, and a spherical lesion. Images
             corresponding to phosphorus, sulfur, and iron (both
             individually and as combinations) were generated from a
             simulated NSECT scan. Signal-to-noise ratio (SNR) and full
             width at half maximum (FWHM) in the tumor region were
             calculated to assess image accuracy (FWHM ≤ 5% error) and
             detectability (SNR > 2.5). The scan with the least amount of
             absorbed dose required to achieve these criteria was defined
             as the optimal acquisition. The lowest dose value was found
             to be 0.0837 cGy for a 2 cm brain tumor imaged using a
             single germanium detector, 6 equally spaced angles from 0 to
             180 degrees, 20 projections per angle and 0.5 million
             neutrons per projection. The SNR for the combination of
             phosphorus, sulfur, and iron with the given condition was
             9.288 and FWHM for the iron was 15 mm with the given
             condition. In conclusion, NSECT is capable of imaging a 2 cm
             brain tumor using the elemental composition of phosphorus,
             sulfur, and iron with reasonable SNR, FWHM and radiation
             dose. © 2013 IEEE.},
   Doi = {10.1109/NSSMIC.2013.6829159},
   Key = {fds319504}
}

@article{fds319505,
   Author = {Greenberg, JA and Krishnamurthy, K and Lakshmanan, M and MacCabe, K and Wolter, S and Kapadia, A and Brady, D},
   Title = {Coding and sampling for compressive x-ray diffraction
             tomography},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {8858},
   Year = {2013},
   url = {http://dx.doi.org/10.1117/12.2027128},
   Abstract = {Coded apertures and energy resolving detectors may be used
             to improve the sampling efficiency of x-ray tomography and
             increase the physical diversity of x-ray phenomena measured.
             Coding and decompressive inference enable increased
             molecular specificity, reduced exposure and scan times. We
             outline a specific coded aperture x-ray coherent scatter
             imaging architecture that demonstrates the potential of such
             schemes. Based on this geometry, we develop a physical model
             using both a semi-analytic and Monte Carlo-based framework,
             devise an experimental realization of the system, describe a
             reconstruction algorithm for estimating the object from raw
             data, and propose a classification scheme for identifying
             the material composition of the object at each location. ©
             2013 SPIE.},
   Doi = {10.1117/12.2027128},
   Key = {fds319505}
}

@article{fds319506,
   Author = {Kapadia, AJ and Lakshmanan, MN and Krishnamurthy, K and Sahbaee, P and Chawla, A and Wolter, S and Maccabe, K and Brady, D and Samei,
             E},
   Title = {Monte-Carlo simulations of a coded-aperture X-ray scatter
             imaging system for molecular imaging},
   Journal = {Proceedings of SPIE},
   Volume = {8668},
   Year = {2013},
   url = {http://dx.doi.org/10.1117/12.2008484},
   Abstract = {In this work, we demonstrate the ability to determine the
             material composition of a sample by measuring coherent
             scatter diffraction patterns generated using a
             coded-aperture x-ray scatter imaging (CAXSI) system. Most
             materials are known to exhibit unique diffraction patterns
             through coherent scattering of low-energy x-rays. However,
             clinical x-ray imagers typically discard scatter radiation
             as noise that degrades image quality. Through the addition
             of a coded aperture, the system can be sensitized to
             coherent scattered photons that carry information about the
             identity and location of the scattering material. In this
             work, we demonstrate this process using a Monte-Carlo
             simulation of a CAXSI system. A simulation of a CAXSI system
             was developed in GEANT4 with modified physics libraries to
             model coherent scatter diffraction patterns in materials.
             Simulated images were generated from 10 materials including
             plastics, hydrocarbons, and biological tissue. The materials
             were irradiated using collimated pencil- and fan-beams with
             energies of 160 kVp. The diffraction patterns were imaged
             using a simulated 2D detector and mathematically
             deconstructed using an analytical projection model that
             accounted for the known x-ray source spectrum. The
             deconstructed diffraction patterns were then matched with a
             library of known coherent scatter form-factors of different
             materials to determine the identity of the scatterer at
             different locations in the object. The results showed good
             agreement between the measured and known scatter patterns
             from the materials, demonstrating the ability to image and
             identify materials at different 3D locations within an
             object using a projection-based CAXSI system. © 2013
             SPIE.},
   Doi = {10.1117/12.2008484},
   Key = {fds319506}
}

@article{fds319507,
   Author = {Lakshmanan, MN and Kapadia, AJ},
   Title = {Quantitative assessment of lesion detection accuracy,
             resolution, and reconstruction algorithms in neutron
             stimulated emission computed tomography.},
   Journal = {IEEE Transactions on Medical Imaging},
   Volume = {31},
   Number = {7},
   Pages = {1426-1435},
   Year = {2012},
   Month = {July},
   url = {http://dx.doi.org/10.1109/TMI.2012.2192134},
   Abstract = {We present a quantitative analysis of the image quality
             obtained using filtered back-projection (FBP) with Ram-Lak
             filtering and maximum likelihood-expectation maximization
             (ML-EM)-with no post-reconstruction filtering in either
             case-in neutron stimulated emission computed tomography
             (NSECT) imaging using Monte Carlo simulations in the context
             of clinically relevant models of liver iron overload. The
             ratios of pixel intensities for several regions of interest
             and lesion shape detection using an active-contours
             segmentation algorithm are assessed for accuracy across
             different scanning configurations and reconstruction
             algorithms. The modulation transfer functions (MTFs) are
             also computed for the cases under study and are applied to
             determine a minimum detectable lesion spacing as a form of
             sensitivity analysis. The accuracy of NSECT imaging in
             measuring relative tissue concentration is presented for
             simulated clinical liver cases. When using the 15th
             iteration, ML-EM provides at least 25% better resolution
             than FBP and proves to be highly robust under low-signal
             high-noise conditions prevalent in NSECT. However, FBP gives
             more accurate lesion pixel intensity ratios and size
             estimates in some cases; due to advantages provided by both
             reconstruction algorithms, it is worth exploring the
             development of an algorithm that is a hybrid of the two. We
             also show that NSECT imaging can be used to accurately
             detect 3-cm lesions in backgrounds that are a significant
             fraction (one-quarter) of the concentration of the lesion,
             down to a 4-cm spacing between lesions.},
   Doi = {10.1109/TMI.2012.2192134},
   Key = {fds319507}
}

@article{fds327414,
   Author = {Kapadia, A and Crowell, A and Fallin, B and Howell, C and Agasthya, G and Lakshmanan, M and Newton, J and Juang, T and Oldham,
             M},
   Title = {SU-E-T-108: 3D Measurement of Neutron Dose from a Novel
             Neutron Imaging Technique.},
   Journal = {Medical physics},
   Volume = {39},
   Number = {6Part11},
   Pages = {3727},
   Year = {2012},
   Month = {June},
   url = {http://dx.doi.org/10.1118/1.4735166},
   Abstract = {We have been developing a fast-neutron spectroscopic
             technique to quantitatively image the distribution of
             elements in the body using quasi-monochromatic neutron
             beams. Previously, we demonstrated the ability of the
             technique to quantify specific elements in the liver and
             breast while limiting radiation dose to clinically
             acceptable levels. Here we present the results of a physical
             dose measurement performed through neutron irradiation of 3D
             PRESAGE dosimetry phantoms.Two PRESAGE optical-CT dosimeters
             were placed inside a physical phantom of the human torso and
             irradiated with 8 MeV neutrons produced via the 2H(d,n)
             reaction using a tandem Van-de-Graaff accelerator. The
             dosimeters, measuring 10 cm and 4 cm in diameter, were
             located in regions corresponding to the liver (10 cm), and
             the kidney (4 cm). Irradiation was performed with the
             neutron beam incident directly on the larger dosimeter.
             Cumulative neutron fluence incident upon each dosimeter was
             determined using an aluminum-foil activation technique.
             Following irradiation, the change in optical density in both
             dosimeters was measured to determine the relative
             irradiation and dose distribution in each volume.Both
             PRESAGE dosimeters exhibited detectable changes in optical
             density corresponding to the dose deposited in the volume.
             The two dosimeters registered doses of 8.5 Gy (direct
             incidence, 4.5 hour irradiation) and 0.25 Gy (off-axis, 20
             hour irradiation), respectively. The larger dosimeter showed
             highest intensity at the entry point of the beam with
             exponential drop-off along the beam direction. The smaller
             dosimeter registered a more uniform change in intensity,
             consistent with the higher incidence of scattered neutrons
             at this location.The results demonstrate the utility of
             PRESAGE dosimeters in measuring dose from neutron
             irradiation and highlight the difference in relative doses
             between primary and proximal organs when exposed to neutron
             beams. This work was supported by the United States
             Department of Energy, Office of Nuclear Physics under Grant
             No. DE-FG02-97ER41033, the National Cancer Institute under
             grant R01CA100835, and by the Department of Defense under
             award W81XWH-09-1-0066.},
   Doi = {10.1118/1.4735166},
   Key = {fds327414}
}

@article{fds327415,
   Author = {Kapadia, A and Samei, E and Harrawood, B and Sahbaee, P and Chawla, A and Tan, Z and Brady, D},
   Title = {SU-E-I-77: X-Ray Coherent Scatter Diffraction Pattern
             Modeling in GEANT4.},
   Journal = {Medical physics},
   Volume = {39},
   Number = {6Part5},
   Pages = {3642-3643},
   Year = {2012},
   Month = {June},
   url = {http://dx.doi.org/10.1118/1.4734794},
   Abstract = {To model X-ray coherent scatter diffraction patterns in
             GEANT4 for simulating experiments involving material
             detection through diffraction pattern measurement. Although
             coherent scatter cross-sections are modeled accurately in
             GEANT4, diffraction patterns for crystalline materials are
             not yet included. Here we describe our modeling of
             crystalline diffraction patterns in GEANT4 for specific
             materials and the validation of the results against
             experimentally measured data.Coherent scatter in GEANT4 is
             currently based on Hubbell's non-relativistic form factor
             tabulations from EPDL97. We modified the form-factors by
             introducing an interference function that accounts for the
             angular dependence between the Rayleigh-scattered photons
             and the photon wavelength. The modified form factors were
             used to replace the inherent form-factors in GEANT4. The
             simulation was tested using monochromatic and polychromatic
             x-ray beams (separately) incident on objects containing one
             or more elements with modified form-factors. The simulation
             results were compared against the experimentally measured
             diffraction images of corresponding objects using an
             in-house x-ray diffraction imager for validation. The
             comparison was made using the following metrics: number of
             diffraction rings, radial distance, absolute intensity, and
             relative intensity.Sharp diffraction pattern rings were
             observed in the monochromatic simulations at locations
             consistent with the angular dependence of the photon
             wavelength. In the polychromatic simulations, the
             diffraction patterns exhibited a radial blur consistent with
             the energy spread of the polychromatic spectrum. The
             simulated and experimentally measured patterns showed
             identical numbers of rings with close agreement in radial
             distance, absolute and relative intensities (barring
             statistical fluctuations). No significant change was
             observed in the execution time of the simulations.This work
             demonstrates the ability to model coherent scatter
             diffraction in GEANT4 in an accurate and efficient manner
             without compromising the accuracy or runtime of the
             simulation. This work was supported by the Department of
             Homeland Security under grant DHS (BAA 10-01 F075), and by
             the Department of Defense under award W81XWH-09-1-0066.},
   Doi = {10.1118/1.4734794},
   Key = {fds327415}
}

@article{fds319508,
   Author = {Agasthya, GA and Harrawood, BC and Shah, JP and Kapadia,
             AJ},
   Title = {Sensitivity analysis for liver iron measurement through
             neutron stimulated emission computed tomography: a Monte
             Carlo study in GEANT4.},
   Journal = {Physics in Medicine and Biology},
   Volume = {57},
   Number = {1},
   Pages = {113-126},
   Year = {2012},
   Month = {January},
   ISSN = {1361-6560},
   url = {http://dx.doi.org/10.1088/0031-9155/57/1/113},
   Keywords = {Humans • Iron • Liver • Monte Carlo Method*
             • Neutrons • Sensitivity and Specificity •
             Tomography, Emission-Computed • metabolism* •
             methods* • radionuclide imaging* • therapeutic
             use*},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being developed as a non-invasive imaging modality to detect
             and quantify iron overload in the human liver. NSECT uses
             gamma photons emitted by the inelastic interaction between
             monochromatic fast neutrons and iron nuclei in the body to
             detect and quantify the disease. Previous simulated and
             physical experiments with phantoms have shown that NSECT has
             the potential to accurately diagnose iron overload with
             reasonable levels of radiation dose. In this work, we
             describe the results of a simulation study conducted to
             determine the sensitivity of the NSECT system for hepatic
             iron quantification in patients of different sizes. A GEANT4
             simulation of the NSECT system was developed with a human
             liver and two torso sizes corresponding to small and large
             patients. The iron concentration in the liver ranged between
             0.5 and 20 mg g(-1), corresponding to clinically reported
             iron levels in iron-overloaded patients. High-purity
             germanium gamma detectors were simulated to detect the
             emitted gamma spectra, which were background corrected using
             suitable water phantoms and analyzed to determine the
             minimum detectable level (MDL) of iron and the sensitivity
             of the NSECT system. These analyses indicate that for a
             small patient (torso major axis = 30 cm) the MDL is 0.5 mg
             g(-1) and sensitivity is ∼13 ± 2 Fe counts/mg/mSv and for
             a large patient (torso major axis = 40 cm) the values are 1
             mg g(-1) and ∼5 ± 1 Fe counts/mg/mSv, respectively. The
             results demonstrate that the MDL for both patient sizes lies
             within the clinically significant range for human iron
             overload.},
   Language = {eng},
   Doi = {10.1088/0031-9155/57/1/113},
   Key = {fds319508}
}

@article{fds319509,
   Author = {Agasthya, GA and Shah, JP and Harrawood, BP and Kapadia,
             AJ},
   Title = {Low dose, non-tomographic estimation of lesion position and
             trace element concentration in NSECT},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {3796-3799},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2011.6153719},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is a
             quantitative imaging method that uses fast-neutron inelastic
             scatter to identify the elemental composition of diseased
             tissue in biological organs. Previous NSECT work has shown
             the ability to quantitatively image liver iron
             concentrations through tomographic imaging; however, such
             acquisition imparts considerable radiation dose. To
             implement NSECT as a low-dose diagnostic tool, we are
             developing a technique to simultaneously determine the
             element concentration and position from a single-angle scan
             of the tissue, thereby eliminating the need for tomography
             and reducing both scan time and radiation dose. Using known
             physical factors such as neutron and gamma attenuation that
             affect the detected gamma signal, a unique equation
             corresponding to the expected gamma counts can be developed
             for each detector in the acquisition system, and these
             equations can be solved iteratively to obtain a simultaneous
             estimate of the lesion position and iron concentration. As
             the first step towards the development of this algorithm, we
             describe here a graphical approach to localize and quantify
             an iron lesion in the liver without tomographic imaging. The
             acquisition system with a collimated neutron source,
             multiple gamma detectors, and a tissue phantom were
             simulated in GEANT4 and used to generate gamma spectra from
             50 different combinations of lesion position and iron
             concentration: 49 known cases and 1 unknown 'test' case.
             Surface plots of gamma counts vs. lesion position and iron
             concentration from the 49 known combinations were generated
             for each detector. The 'test' lesion signal was overlaid on
             the surface plots to obtain the best estimate of the unknown
             lesion concentration and position in the beam. The results
             showed 100% accurate identification of the concentration and
             less than 20% error in the identified position. The results
             validate the approach for non-tomographic determination of
             these parameters. © 2011 IEEE.},
   Doi = {10.1109/NSSMIC.2011.6153719},
   Key = {fds319509}
}

@article{fds319510,
   Author = {Kapadia, AJ and Ye, Q and Agasthya, GA},
   Title = {Elemental quantification through gamma-stimulated
             spectroscopy: An NRF simulation in GEANT4},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {4281-4284},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2011.6153823},
   Abstract = {Since 2008, we have been developing a new method for the
             quantification of naturally occurring elements in the human
             body. The technique, called gamma-stimulated spectroscopy
             (GSS), uses high-energy, tuned gamma-ray beams to stimulate
             selected energy levels in specific stable isotopes in the
             body through nuclear resonance fluorescence (NRF). Such
             selective excitation can be used to detect a variety of
             human disorders that exhibit differences in element
             concentration between diseased and healthy tissue. In
             previous work, we have developed a prototype GSS device
             using the free-electron-laser (FEL) source at Duke
             University and demonstrated the selective excitation of iron
             in water. Here we describe the development of a GEANT4
             simulation of the GSS system including the modeling of the
             NRF process. A monochromatic, collimated gamma source,
             virtual gamma-ray detectors, and an aqueous iron-copper
             phantom were simulated in GEANT4. The NRF process was
             modeled by creating a new NRF process class that calculated
             the interaction cross-section and the nuclear deexcitation
             data. The simulation was tested at two source energies
             (846.7 keV and 3448.41 keV) corresponding to excitable
             energy levels in natural iron. The resulting spectra showed
             accurate gamma energy response and emission patterns and
             exhibited excellent correlation between the simulated and
             the measured iron concentration. Following benchmarking
             against experimental data, the simulation will provide an
             accurate tool for modeling NRF processes in GEANT4 and will
             be used to guide the development of the clinical GSS system.
             © 2011 IEEE.},
   Doi = {10.1109/NSSMIC.2011.6153823},
   Key = {fds319510}
}

@article{fds319511,
   Author = {Agasthya, GA and Shah, JP and Harrawood, BP and Nolte, LW and Kapadia,
             AJ},
   Title = {Computerized detection of low SNR cases in NSECT: An
             ROC-based sensitivity analysis},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {3935-3938},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2011.6153748},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             an imaging technique that uses gamma energy spectra emitted
             from inelastic scattering of fast neutrons to extract
             quantitative elemental information from tissue. The NSECT
             acquisition system consists of a neutron source and one or
             more gamma detectors. For the NSECT system to be adequately
             sensitive to low elemental concentrations it is important to
             accurately extract the relevant gamma counts despite low
             signal to noise ratio (SNR) conditions. One technique to
             improve the sensitivity of the system and lower the minimum
             detectable level is to use computerized post processing of
             the gamma spectra. In this project, we describe a method of
             improving the sensitivity of the NSECT system through
             computerized post processing of the NSECT signal. The signal
             and noise in NSECT are photon-counting systems and hence are
             Poisson distributed. Modifying the Gaussian signal known
             exactly (SKE) case of signal detection theory to incorporate
             Poisson distributions, a likelihood based optimum detector
             was designed for each gamma detector in the NSECT
             acquisition system. This detector was implemented in MATLAB
             for the simulated iron concentrations and was followed by
             ROC analysis to study the detection sensitivity of the
             designed detector. In this project a GEANT4 simulation of a
             tissue sample with a 2 cm lesion (at a fixed location) was
             used to generate an NSECT spectrum from a single projection
             for different iron concentrations in the lesion. The iron
             concentration values were set to represent clinical liver
             iron overload. The gamma signal corresponding to iron and
             the background noise from Compton scattering of high-energy
             gamma photons were estimated using Poisson distributions.
             The results showed that for the simulated lesion position,
             the area under the curve (AUC) increased with increasing
             iron concentration, and 4 of the 6 gamma detectors were able
             to detect the lowest simulated iron concentration (1 mg/g).
             These results demonstrate that NSECT combined with
             computerized post processing has the potential to detect
             clinically relevant concentrations of iron to diagnose and
             quantify liver iron overload. © 2011 IEEE.},
   Doi = {10.1109/NSSMIC.2011.6153748},
   Key = {fds319511}
}

@article{fds319512,
   Author = {Agasthya, GA and Shah, JP and Harrawood, BP and Kapadia,
             AJ},
   Title = {Neutron time-of-flight spectroscopy for depth-resolved
             quantification through NSECT},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {3034-3037},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2011.6152547},
   Abstract = {With advances in detector technology, gamma-ray detectors
             are now capable of reporting both time of arrival of a
             photon and its energy. Although the gamma energies detected
             from the inelastic scattering of neutrons with elemental
             nuclei in the tissue of interest are being exploited in
             Neutron Stimulation Emission Computed Tomography (NSECT) to
             detect different elemental disorders, the timing information
             is largely ignored. Here we present a technique to utilize
             the time of arrival of gamma photons at a detector to locate
             focal liver lesions in diseases such as hemochromatosis and
             liver cancer. A GEANT4 simulation of 5-MeV neutrons was used
             to irradiate a liver phantom with multiple lesions with
             different iron concentrations. The time of arrival of gamma
             photons from neutron- 56Fe inelastic scatter was recorded
             using a 360 degree, 100% efficient detection system and used
             to locate the lesions in the beam path. The resulting
             spectra were resolved in nanosecond time bins (corresponding
             to the expected arrival time of inelastic-scatter gamma
             photons from the lesion) and clearly demonstrated the
             ability to localize the focal liver lesions through neutron
             time-of-flight (TOF) spectroscopy. The preliminary results
             showed errors of only 10-20% in lesion position,
             demonstrating the strong potential of the technique. © 2011
             IEEE.},
   Doi = {10.1109/NSSMIC.2011.6152547},
   Key = {fds319512}
}

@article{fds319513,
   Author = {Lakshmanan, MN and Kapadia, AJ},
   Title = {Quantitative assessment of lesion detection accuracy,
             resolution, and reconstruction algorithms in neutron
             stimulated emission computed tomography.},
   Journal = {IEEE Transactions on Medical Imaging},
   Volume = {31},
   Number = {7},
   Pages = {1426-1435},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/TMI.2012.2192134},
   Abstract = {We present a quantitative analysis of the image quality
             obtained using filtered back-projection (FBP) with Ram-Lak
             filtering and maximum likelihood-expectation maximization
             (ML-EM)-with no post-reconstruction filtering in either
             case-in neutron stimulated emission computed tomography
             (NSECT) imaging using Monte Carlo simulations in the context
             of clinically relevant models of liver iron overload. The
             ratios of pixel intensities for several regions of interest
             and lesion shape detection using an active-contours
             segmentation algorithm are assessed for accuracy across
             different scanning configurations and reconstruction
             algorithms. The modulation transfer functions (MTFs) are
             also computed for the cases under study and are applied to
             determine a minimum detectable lesion spacing as a form of
             sensitivity analysis. The accuracy of NSECT imaging in
             measuring relative tissue concentration is presented for
             simulated clinical liver cases. When using the 15th
             iteration, ML-EM provides at least 25% better resolution
             than FBP and proves to be highly robust under low-signal
             high-noise conditions prevalent in NSECT. However, FBP gives
             more accurate lesion pixel intensity ratios and size
             estimates in some cases; due to advantages provided by both
             reconstruction algorithms, it is worth exploring the
             development of an algorithm that is a hybrid of the two. We
             also show that NSECT imaging can be used to accurately
             detect 3-cm lesions in backgrounds that are a significant
             fraction (one-quarter) of the concentration of the lesion,
             down to a 4-cm spacing between lesions.},
   Doi = {10.1109/TMI.2012.2192134},
   Key = {fds319513}
}

@article{fds319514,
   Author = {Magana, Q and Kapadia, A and Agasthya, G and Balinskas,
             S},
   Title = {Automated hemochromatosis spectra analysis using neutron
             stimulated emission tomography},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {2497-2500},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2012.6551570},
   Abstract = {We identified and diagnosed hemochromatotic cases with an
             automatic technique based on peak recognition and
             chemometrics. Hemochromatosis is a disease characterized by
             an accumulation of iron in body organs. Neutron-stimulated
             emission computed tomography (NSECT) has demonstrated its
             ability to detect elevated iron concentrations in the liver
             through a non-invasive, low dose scan. Fast neutrons are
             used to generate gamma-ray emission from atomic nuclei in
             the liver, and the spectral energies of the emitted gamma
             photons are used to identify the elements of interest. The
             ability to analyze all gamma lines in the spectra, belonging
             either to an individual element or to different elements,
             significantly enhances the overall sensitivity, accuracy,
             and effectiveness of the diagnosis. We developed a novel
             peak-finding/peak-fitting algorithm, which rapidly processes
             all spectra collected on a large scale (i.e. all peaks
             within each spectrum in a set of spectra), and classifies
             the samples into healthy and diseased categories. The
             technique finds, deconvolves, and characterizes peaks based
             on their position, height, full width at half maximum
             (FWHM), and area, classifying the samples automatically with
             two methods, incriminant (novel) and discriminant analysis.
             We demonstrated that the algorithm classified a population
             of 64 healthy and 120 diseased simulated patients into
             healthy and hemochromatotic groups with clinically
             significant accuracy. © 2012 IEEE.},
   Doi = {10.1109/NSSMIC.2012.6551570},
   Key = {fds319514}
}

@article{fds319515,
   Author = {Lakshmanan, MN and Harrawood, BP and Agasthya, GA and Rusev, G and Kapadia, AJ},
   Title = {Nuclear resonance fluorescence (NRF) in GEANT4: Development,
             validation, and testing},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {1731-1734},
   Year = {2012},
   url = {http://dx.doi.org/10.1109/NSSMIC.2012.6551406},
   Abstract = {Despite its utility and applicability, the ability to
             simulate the NRF technique is not currently included in
             GEANT4. Here we describe the development, validation and
             testing of NRF in GEANT4 for 10 separate isotopes. An NRF
             class named G4NRF was developed to handle NRF physics.
             Validation of the simulation was performed by benchmarking
             it against experimental measurements for measured counts
             from gamma-ray scattering in water and metallic samples. The
             validation results show agreement between the simulation and
             experimental spectra for the appearance of the NRF peak. We
             have begun applying the NRF simulation for medical research,
             and we are seeking to make the NRF physics code available to
             the GEANT4 community in a future release. © 2012
             IEEE.},
   Doi = {10.1109/NSSMIC.2012.6551406},
   Key = {fds319515}
}

@article{fds199039,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Ye Q, Agasthya GA, “Elemental Quantification
             through Gamma-Stimulated Spectroscopy in GEANT4”,
             Proceedings of IEEE Nuclear Science Symposium, Medical
             Imaging Conference, 2011.},
   Year = {2011},
   Key = {fds199039}
}

@article{fds199040,
   Author = {A.J. Kapadia},
   Title = {Agasthya GA, Shah JP, Harrawood BP, Kapadia AJ, “Low Dose,
             Non-Tomographic Technique to Estimate Lesion Position and
             Trace Element Concentration in NSECT”, IEEE Nuclear
             Science Symposium, Medical Imaging Conference,
             2011.},
   Year = {2011},
   Key = {fds199040}
}

@article{fds199041,
   Author = {A.J. Kapadia},
   Title = {Agasthya GA, Shah JP, Harrawood BP, Kapadia AJ, “Neutron
             Time-of-Flight Spectroscopy for Depth-Resolved
             Quantification through NSECT”, IEEE Nuclear Science
             Symposium, Medical Imaging Conference, 2011.},
   Year = {2011},
   Key = {fds199041}
}

@article{fds199042,
   Author = {A.J. Kapadia},
   Title = {Agasthya GA, Shah JP, Harrawood BP, Nolte LW, Kapadia AJ,
             “Computerized Detection of Low SNR Cases in NSECT: an
             ROC-Based Sensitivity Analysis”, IEEE Nuclear Science
             Symposium, Medical Imaging Conference, 2011.},
   Year = {2011},
   Key = {fds199042}
}

@article{fds327416,
   Author = {Kapadia, A and Agasthya, G and Cumberbatch, L and Howell,
             C},
   Title = {SU-GG-I-159: In-Vivo Iron Measurement through Nuclear
             Resonance Fluorescence},
   Journal = {Medical physics},
   Volume = {37},
   Number = {6Part5},
   Pages = {3138-3138},
   Year = {2010},
   Month = {June},
   url = {http://dx.doi.org/10.1118/1.3468195},
   Doi = {10.1118/1.3468195},
   Key = {fds327416}
}

@article{fds199038,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Shah JP, Agasthya GA, “Quantitative Elemental
             Imaging with Neutrons for Breast Cancer Diagnosis: a GEANT4
             Study”, IEEE Nuclear Science Symposium, Medical Imaging
             Conference, pp 3065 – 3068, 2010. },
   Year = {2010},
   Key = {fds199038}
}

@article{fds319516,
   Author = {Kapadia, AJ and Shah, JP and Agasthya, GA},
   Title = {Quantitative elemental imaging with neutrons for breast
             cancer diagnosis: A GEANT4 study},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {3065-3068},
   Year = {2010},
   url = {http://dx.doi.org/10.1109/NSSMIC.2010.5874363},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) has
             been proposed as an early cancer-detection technique with
             the capability of 3-D tomographic imaging for identification
             of malignant tumors. In previous work we have demonstrated
             the ability of the technique to differentiate between normal
             and malignant breast tumors based on the concentration of
             cancer-marking elements in the tissue. Here we present
             tomographic images from a breast phantom with benign and
             malignant tumors simulated in GEANT4. A simulated model of
             the NSECT system was developed in GEANT4, along with
             phantoms corresponding to the human breast with benign and
             malignant tumors. Each tumor within the breast was given a
             different concentration of cancer-marking trace elements
             based on values reported in literature. The phantom was
             scanned with a 5-MeV neutron beam over a 180-degree angle.
             Tomographic images were reconstructed for six elements of
             interest from 10 different spectral lines. The results
             showed excellent agreement between the location of the tumor
             and the concentration of trace element detected in gamma
             lines from bromine, cesium, sodium and zinc. These results
             demonstrate the ability of NSECT in quantitative elemental
             imaging for breast cancer detection. © 2010
             IEEE.},
   Doi = {10.1109/NSSMIC.2010.5874363},
   Key = {fds319516}
}

@article{fds159507,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Agasthya GA, Tourassi GD. Detection of Iron
             Overload through Neutron Stimulated Emission Computed
             Tomography: A Sensitivity Analysis Study. Proceedings of
             SPIE Medical Imaging. 2009;7258:725811-725819.},
   Year = {2009},
   Key = {fds159507}
}

@article{fds159509,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ. Neutron Stimulated Emission Computed Tomography:
             A New Technique for Spectroscopic Medical Imaging. Neutron
             Imaging and Applications, Springer, ISBN: 978-0-387-78692-6,
             2009.},
   Year = {2009},
   Key = {fds159509}
}

@article{fds172766,
   Author = {A.J. Kapadia},
   Title = {Agasthya GA and Kapadia AJ. Locating stored iron in the
             liver through attenuation measurement in NSECT. IEEE Nuclear
             Science Symposium and Medical Imaging Conference
             2009;2419-2422.},
   Year = {2009},
   Key = {fds172766}
}

@article{fds319517,
   Author = {Agasthya, GA and Kapadia, AJ},
   Title = {Locating stored iron in the liver through attenuation
             measurement in NSECT},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {2419-2422},
   Year = {2009},
   url = {http://dx.doi.org/10.1109/NSSMIC.2009.5402150},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is a
             quantitative spectroscopic technique to detect element
             concentrations in the body. In previous work, we have
             demonstrated the ability to detect non-uniform distributions
             of iron overload in liver (in hemochromatosis) with a
             sensitivity of approximately 5mg/g. The diagnosis of
             hemochromatosis is performed by detecting characteristic
             gamma photons emitted by iron nuclei after they undergo
             inelastic scatter with incident neutrons. The efficiency of
             detection of the gamma photons is a combination of the
             attenuation of neutrons passing through the body and the
             attenuation of gamma photons before reaching the detectors.
             With non-uniform iron distributions, therefore, the
             resulting total attenuation depends on the position of the
             iron store within the body with respect to the neutron beam
             and the gamma detectors. We are developing an attenuation
             correction technique which takes into consideration the
             position of the iron-store in the liver to compute a
             correction factor based on a combination of neutron and
             gamma attenuation. In this work we present results from a
             Monte-Carlo simulation study exploring the effect of the
             location of the iron-store within the liver. The NSECT
             scanning geometry used for data collection was simulated in
             GEANT4 [1]. A lesion of iron was placed at different
             locations within the liver and scanned to obtain an estimate
             of the detected signal. An estimate of the unattenuated
             signal was obtained and used to determine the total
             attenuation in the liver tissue. The attenuation profile was
             obtained for each position of the lesion and compared
             against a theoretical value. The results were found to be in
             agreement with each other, indicating that a theoretically
             calculated attenuation profile can be accurately used to
             create attenuation maps and hence locate iron-stores in the
             liver using NSECT. ©2009 IEEE.},
   Doi = {10.1109/NSSMIC.2009.5402150},
   Key = {fds319517}
}

@article{fds319518,
   Author = {Kapadia, AJ and Agasthya, GA and Tourassi, GD},
   Title = {Detection of iron overload through neutron stimulated
             emission computed tomography: A sensitivity analysis
             study},
   Journal = {Proceedings of SPIE},
   Volume = {7258},
   Year = {2009},
   url = {http://dx.doi.org/10.1117/12.811737},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being developed as a non-invasive technique to diagnose iron
             overload in the liver. It uses inelastic scatter
             interactions between fast neutrons and iron nuclei to
             quantify localized distributions of iron within the liver.
             Preliminary studies have demonstrated the feasibility of
             iron overload detection through NSECT using a Monte-Carlo
             simulation model in GEANT4. The work described here uses the
             GEANT4 simulation model to analyze iron-overload detection
             sensitivity in NSECT. A simulation of a clinical NSECT
             system was designed in GEANT4. Simulated models were created
             for human liver phantoms with concentrations of iron varying
             from 0.5 mg/g to 20 mg/g (wet). Each liver phantom was
             scanned with 100 million neutron events to generate gamma
             spectra showing gamma-lines corresponding to iron in the
             liver. A background spectrum was obtained using a water
             phantom of equal mass as the liver phantom and was
             subtracted from each liver spectrum. The height of the gamma
             line at 847 keV (corresponding to 56Fe) was used as a
             measure of the detected iron concentration in each
             background-corrected spectrum. The variation in detected
             gamma counts was analyzed and plotted as a function of the
             liver iron concentration to quantify measurement error.
             Analysis of the differences between the measured and
             expected value of iron concentration indicate that NSECT
             sensitivity for detection of iron in liver tissue may lie in
             the range of 0.5 mg/g - 1 mg/g, which represents a
             clinically significant range for iron overload detection in
             humans. © 2009 SPIE.},
   Doi = {10.1117/12.811737},
   Key = {fds319518}
}

@article{fds319519,
   Author = {Kapadia, AJ and Gallmeier, FX and Iverson, EB and Ferguson, PD and IEEE},
   Title = {Detection of Iron Overload with the ORNL Spallation Neutron
             Source: an MCNPX Simulation Study},
   Journal = {IEEE Conference Record - Nuclear Science Symposium & Medical
             Imaging Conference : IEEE Nuclear Science Symposium And
             Medical Imaging Conference. Proceedings},
   Pages = {4238-+},
   Year = {2009},
   ISBN = {978-1-4244-2714-7},
   Key = {fds319519}
}

@article{fds319520,
   Author = {Kapadia, AJ and Tourassi, GD and Sharma, AC and Crowell, AS and Kiser,
             MR and Howell, CR},
   Title = {Experimental detection of iron overload in liver through
             neutron stimulated emission spectroscopy.},
   Journal = {Physics in Medicine and Biology},
   Volume = {53},
   Number = {10},
   Pages = {2633-2649},
   Year = {2008},
   Month = {May},
   ISSN = {0031-9155},
   url = {http://dx.doi.org/10.1088/0031-9155/53/10/013},
   Keywords = {Animals • Cattle • Feasibility Studies •
             Humans • Image Processing, Computer-Assisted •
             Iron • Iron Overload • Liver • Neutrons*
             • Phantoms, Imaging • Radiation Dosage •
             Sensitivity and Specificity • Tomography,
             Emission-Computed • diagnosis* • metabolism •
             metabolism* • methods* • pathology*},
   Abstract = {Iron overload disorders have been the focus of several
             quantification studies involving non-invasive imaging
             modalities. Neutron spectroscopic techniques have
             demonstrated great potential in detecting iron
             concentrations within biological tissue. We are developing a
             neutron spectroscopic technique called neutron stimulated
             emission computed tomography (NSECT), which has the
             potential to diagnose iron overload in the liver at
             clinically acceptable patient dose levels through a
             non-invasive scan. The technique uses inelastic scatter
             interactions between atomic nuclei in the sample and
             incoming fast neutrons to non-invasively determine the
             concentration of elements in the sample. This paper
             discusses a non-tomographic application of NSECT
             investigating the feasibility of detecting elevated iron
             concentrations in the liver. A model of iron overload in the
             human body was created using bovine liver tissue housed
             inside a human torso phantom and was scanned with a 5 MeV
             pulsed beam using single-position spectroscopy. Spectra were
             reconstructed and analyzed with algorithms designed
             specifically for NSECT. Results from spectroscopic
             quantification indicate that NSECT can currently detect
             liver iron concentrations of 6 mg g(-1) or higher and has
             the potential to detect lower concentrations by optimizing
             the acquisition geometry to scan a larger volume of tissue.
             The experiment described in this paper has two important
             outcomes: (i) it demonstrates that NSECT has the potential
             to detect clinically relevant concentrations of iron in the
             human body through a non-invasive scan and (ii) it provides
             a comparative standard to guide the design of iron overload
             phantoms for future NSECT liver iron quantification
             studies.},
   Language = {eng},
   Doi = {10.1088/0031-9155/53/10/013},
   Key = {fds319520}
}

@article{fds319521,
   Author = {Floyd, CE and Kapadia, AJ and Bender, JE and Sharma, AC and Xia, JQ and Harrawood, BP and Tourassi, GD and Lo, JY and Crowell, AS and Kiser, MR and Howell, CR},
   Title = {Neutron-stimulated emission computed tomography of a
             multi-element phantom.},
   Journal = {Physics in Medicine and Biology},
   Volume = {53},
   Number = {9},
   Pages = {2313-2326},
   Year = {2008},
   Month = {May},
   ISSN = {0031-9155},
   url = {http://dx.doi.org/10.1088/0031-9155/53/9/008},
   Keywords = {Algorithms • Diagnostic Imaging • Equipment Design
             • Gamma Rays • Humans • Image Interpretation,
             Computer-Assisted • Image Processing, Computer-Assisted
             • Models, Statistical • Neoplasms • Neutrons*
             • Phantoms, Imaging • Scattering, Radiation •
             Spectrophotometry • Tomography, Emission-Computed
             • diagnosis • instrumentation* • methods
             • methods*},
   Abstract = {This paper describes the implementation of
             neutron-stimulated emission computed tomography (NSECT) for
             non-invasive imaging and reconstruction of a multi-element
             phantom. The experimental apparatus and process for
             acquisition of multi-spectral projection data are described
             along with the reconstruction algorithm and images of the
             two elements in the phantom. Independent tomographic
             reconstruction of each element of the multi-element phantom
             was performed successfully. This reconstruction result is
             the first of its kind and provides encouraging proof of
             concept for proposed subsequent spectroscopic tomography of
             biological samples using NSECT.},
   Language = {eng},
   Doi = {10.1088/0031-9155/53/9/008},
   Key = {fds319521}
}

@article{fds159379,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR,
             Crowell AS, Kiser MR, Harrawood BP, Pedroni RS, and Floyd
             CE. Neutron stimulated emission computed tomography for
             diagnosis of breast cancer. IEEE Transactions on Nuclear
             Science. 2008;55(1):501–509.},
   Year = {2008},
   Key = {fds159379}
}

@article{fds159506,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Harrawood BP, Tourassi GD. GEANT4 simulation of
             NSECT for detection of iron overload in the liver.
             Proceedings of SPIE Medical Imaging. 2008;6913:691309.},
   Year = {2008},
   Key = {fds159506}
}

@article{fds159508,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ. Accuracy and Patient Dose in Neutron Stimulated
             Emission Computed Tomography using Simulations in GEANT4.
             VDM Verlag Publishing. ISBN: 978-3-639-10855-2,
             2008},
   Year = {2008},
   Key = {fds159508}
}

@article{fds172767,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Gallmeier FX, Iverson EB and Ferguson PD.
             Detection of iron overload with the ORNL Spallation Neutron
             Source: An MCNPX simulation study. IEEE Nuclear Science
             Symposium and Medical Imaging Conference
             2008;4972-4975.},
   Year = {2008},
   Key = {fds172767}
}

@article{fds172768,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Harrawood BP and Tourassi GD. Validation of a
             GEANT4 simulation of neutron stimulated emission computed
             tomography. SPIE Medical Imaging Conference.
             2008;6913:69133H-69136.},
   Year = {2008},
   Key = {fds172768}
}

@article{fds319522,
   Author = {Kapadia, AJ and Sharma, AC and Tourassi, GD and Bender, JE and Howell,
             CR and Crowell, AS and Kiser, MR and Harrawood, BP and Pedroni, RS and Jr,
             CEF},
   Title = {Neutron stimulated emission computed tomography for
             diagnosis of breast cancer},
   Journal = {IEEE Transactions on Nuclear Science},
   Volume = {55},
   Number = {1},
   Pages = {501-509},
   Year = {2008},
   url = {http://dx.doi.org/10.1109/TNS.2007.909847},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being developed as a non-invasive spectroscopic imaging
             technique to determine element concentrations in the human
             body. NSECT uses a beam of fast neutrons that scatter
             inelastically from atomic nuclei in tissue, causing them to
             emit characteristic gamma photons that are detected and
             identified using an energy-sensitive gamma detector. By
             measuring the energy and number of emitted gamma photons,
             the system can determine the elemental composition of the
             target tissue. Such determination is useful in detecting
             several disorders in the human body that are characterized
             by changes in element concentration, such as breast cancer.
             In this paper we describe our experimental implementation of
             a prototype NSECT system for the diagnosis of breast cancer
             and present experimental results from sensitivity studies
             using this prototype. Results are shown from three sets of
             samples: (a) excised breast tissue samples with unknown
             element concentrations, (b) a multi-element calibration
             sample used for sensitivity studies, and (c) a small-animal
             specimen, to demonstrate detection ability from in-vivo
             tissue. Preliminary results show that NSECT has the
             potential to detect elements in breast tissue. Several
             elements were identified common to both benign and malignant
             samples, which were confirmed through neutron activation
             analysis (NAA). Statistically significant differences were
             seen for peaks at energies corresponding to 37Cl, 56Fe,
             58Ni, 59Co, 66Zn, 79Br and 87Rb. The spectrum from the small
             animal specimen showed the presence of 12C from tissue, 40Ca
             from bone, and elements 39K, 27Al, 37Cl, 56Fe, 68Zn and
             25Mg. Threshold sensitivity for the four elements analyzed
             was found to range from 0.3 grams to 1 gram, which is higher
             than the microgram sensitivity required for cancer
             detection. Patient dose levels from NSECT were found to be
             comparable to those of screening mammography. © 2008
             IEEE.},
   Doi = {10.1109/TNS.2007.909847},
   Key = {fds319522}
}

@article{fds319523,
   Author = {Kapadia, AJ and Gallmeier, FX and Iverson, EB and Ferguson,
             PD},
   Title = {Detection of iron overload with the ORNL spallation neutron
             source: An MCNPX simulation study},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Pages = {4972-4975},
   Year = {2008},
   url = {http://dx.doi.org/10.1109/NSSMIC.2008.4774356},
   Abstract = {In previous work we have demonstrated the use of neutrons to
             detect iron overload in the liver. We are developing a
             non-invasive technique to measure liver iron concentration
             in the human body through neutron inelastic scatter
             spectroscopy. The measurement is performed using an incident
             neutron beam that scatters inelastically with iron nuclei in
             the liver, causing characteristic gamma emission that is
             used to quantify the tissue iron content. Due to its high
             neutron flux, the Spallation Neutron Source (SNS) at ORNL
             presents anttractive option for initial development and
             optimization of the technique. In this manuscript we
             describe a simulation study to evaluate feasibility of the
             SNS beam for iron overload detection in the liver. An MCNPX
             simulation was developed to model the parameters of the SNS
             beam and scan a liver phantom with tissue iron content
             varying from 2 mg/g (mild iron overloaded) to 10 mg/g
             (severe iron overload). A torso phantom filled with water
             was placed around the liver and used to simulate scattering
             effects of the human torso. The emitted gamma spectrum was
             acquired with a simulated ring detector. Background
             subtraction was performed by substituting the liver with a
             water phantom. Background corrected spectra were analyzed to
             identify gamma lines corresponding to iron in the liver
             tissue. Statistically significant differences with p &lt;
             0.05 were identified for the 56Fe gamma line at 847 keY.
             Counts in the gamma line were found to be higher in the 10
             mg/g sample by a factor of 4.72, differing by less than 6%
             from the expected value of 5. These results demonstrate the
             feasibility of the SNS beam to determine iron content in
             liver tissue. ©2008 IEEE.},
   Doi = {10.1109/NSSMIC.2008.4774356},
   Key = {fds319523}
}

@article{fds319524,
   Author = {Kapadia, AJ and Harrawood, BP and Tourassi, GD},
   Title = {Validation of a GE ANT4 simulation of neutron stimulated
             emission computed tomography},
   Journal = {Proceedings of SPIE},
   Volume = {6913},
   Year = {2008},
   url = {http://dx.doi.org/10.1117/12.773196},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being proposed as a non-invasive technique to detect
             concentrations of elements in the body for diagnosis of
             liver iron overload. Several experiments have been conducted
             to investigate NSECT's ability to determine iron
             concentration in liver tissue and evaluate the accuracy and
             sensitivity of the system. While these experiments have been
             successful in demonstrating NSECT's capability of
             quantifying iron and other tissue elements in-vivo, they
             have been prohibitively time consuming, often requiring as
             much as 24 hour acquisitions for accurate quantification.
             Such extensive scan times limit the use of the experimental
             system for initial feasibility testing and optimization. As
             a practical alternative, GEANT4 simulations are being
             developed to investigate system optimization and aid further
             progress of the experimental technique. This work presents
             results of a validation study comparing the results of a
             GEANT4 simulation with experimental data obtained from a
             sample of iron. A simulation of the NSECT system is
             implemented in GEANT4 and used to acquire a spectrum from a
             simulated iron sample. Scanning is performed with a 7.5 MeV
             neutron beam to stimulate gamma emission from iron nuclei.
             The resulting gamma spectrum is acquired and reconstructed
             using high-purity germanium (HPGe) detectors and analyzed
             for energy peaks corresponding to iron. The simulated
             spectrum is compared with a corresponding experimental
             spectrum acquired with an identical source-detector-sample
             configuration. Five peaks are detected corresponding to
             gamma transitions from iron in both spectra with relative
             errors ranging from 4.5% to 17% for different peaks. The
             result validates the GEANT4 simulation as a feasible
             alternative to perform simulated NSECT experiments using
             only computational resources.},
   Doi = {10.1117/12.773196},
   Key = {fds319524}
}

@article{fds319525,
   Author = {Kapadia, AJ and Harrawood, BP and Tourassi, GD},
   Title = {GEANT4 simulation of NSECT for detection of iron overload in
             the liver},
   Journal = {Proceedings of SPIE},
   Volume = {6913},
   Year = {2008},
   url = {http://dx.doi.org/10.1117/12.773245},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being proposed as a non-invasive technique to diagnose iron
             overload in humans. It uses inelastic scatter interactions
             between incident neutrons and iron nuclei to stimulate
             gamma-ray emission from iron. Tomographic detection of the
             emitted gamma-rays yields information about the
             concentration and spatial distribution of iron in the liver.
             Early proof-of-concept experiments have shown that NSECT has
             the potential to quantify clinical quantities of liver iron
             overload through single-position spectroscopy. However, a
             tomography application for patient diagnosis has never been
             tested. This work uses a Monte-Carlo simulation of a
             tomographic NSECT system to investigate the feasibility of
             imaging the spatial distribution of liver iron through
             tomography. A simulation of an NSECT system has been
             designed in GEANT4 and used to tomographically scan a
             simulated human liver phantom with high-concentration iron
             lesions. Images are reconstructed with the MLEM algorithm
             and analyzed for pixel values within iron regions to
             determine the statistical significance of detection.
             Analysis results indicate that a wet iron concentration of 3
             mg/g can be detected in surrounding liver tissue with
             p-value ≤ 0.0001 for neutron exposure corresponding to a
             radiation dose of 0.72 mSv. The research performed here
             demonstrates that NSECT has the ability to image clinically
             relevant distributions of iron through tomographic
             scanning.},
   Doi = {10.1117/12.773245},
   Key = {fds319525}
}

@article{fds319526,
   Author = {Sharma, AC and Harrawood, BP and Bender, JE and Tourassi, GD and Kapadia, AJ},
   Title = {Neutron stimulated emission computed tomography: a Monte
             Carlo simulation approach.},
   Journal = {Physics in Medicine and Biology},
   Volume = {52},
   Number = {20},
   Pages = {6117-6131},
   Year = {2007},
   Month = {October},
   ISSN = {0031-9155},
   url = {http://dx.doi.org/10.1088/0031-9155/52/20/003},
   Keywords = {Computer Simulation • Image Interpretation,
             Computer-Assisted • Models, Biological* • Models,
             Statistical • Monte Carlo Method • Neutrons •
             Radiation Dosage • Radiometry • Scattering,
             Radiation • Tomography, Emission-Computed •
             diagnostic use* • methods*},
   Abstract = {A Monte Carlo simulation has been developed for neutron
             stimulated emission computed tomography (NSECT) using the
             GEANT4 toolkit. NSECT is a new approach to biomedical
             imaging that allows spectral analysis of the elements
             present within the sample. In NSECT, a beam of high-energy
             neutrons interrogates a sample and the nuclei in the sample
             are stimulated to an excited state by inelastic scattering
             of the neutrons. The characteristic gammas emitted by the
             excited nuclei are captured in a spectrometer to form
             multi-energy spectra. Currently, a tomographic image is
             formed using a collimated neutron beam to define the line
             integral paths for the tomographic projections. These
             projection data are reconstructed to form a representation
             of the distribution of individual elements in the sample. To
             facilitate the development of this technique, a Monte Carlo
             simulation model has been constructed from the GEANT4
             toolkit. This simulation includes modeling of the neutron
             beam source and collimation, the samples, the neutron
             interactions within the samples, the emission of
             characteristic gammas, and the detection of these gammas in
             a Germanium crystal. In addition, the model allows the
             absorbed radiation dose to be calculated for internal
             components of the sample. NSECT presents challenges not
             typically addressed in Monte Carlo modeling of high-energy
             physics applications. In order to address issues critical to
             the clinical development of NSECT, this paper will describe
             the GEANT4 simulation environment and three separate
             simulations performed to accomplish three specific aims.
             First, comparison of a simulation to a tomographic
             experiment will verify the accuracy of both the gamma energy
             spectra produced and the positioning of the beam relative to
             the sample. Second, parametric analysis of simulations
             performed with different user-defined variables will
             determine the best way to effectively model low energy
             neutrons in tissue, which is a concern with the high
             hydrogen content in biological tissue. Third, determination
             of the energy absorbed in tissue during neutron
             interrogation in order to estimate the dose. Results from
             these three simulation experiments demonstrate that GEANT4
             is an effective simulation platform that can be used to
             facilitate the future development and optimization of
             NSECT.},
   Language = {eng},
   Doi = {10.1088/0031-9155/52/20/003},
   Key = {fds319526}
}

@article{fds319527,
   Author = {Bender, JE and Kapadia, AJ and Sharma, AC and Tourassi, GD and Harrawood, BP and Floyd, CE},
   Title = {Breast cancer detection using neutron stimulated emission
             computed tomography: prominent elements and dose
             requirements.},
   Journal = {Medical physics},
   Volume = {34},
   Number = {10},
   Pages = {3866-3871},
   Year = {2007},
   Month = {October},
   ISSN = {0094-2405},
   url = {http://dx.doi.org/10.1118/1.2775669},
   Keywords = {Algorithms • Breast Neoplasms • Computer
             Simulation • Gamma Rays • Humans • Image
             Processing, Computer-Assisted • Monte Carlo Method
             • Neutrons • ROC Curve • Radiometry •
             Software • Spectrum Analysis • Tomography,
             Emission-Computed • diagnosis* • methods •
             methods* • pathology*},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being developed to noninvasively determine concentrations of
             trace elements in biological tissue. Studies have shown
             prominent differences in the trace element concentration of
             normal and malignant breast tissue. NSECT has the potential
             to detect these differences and diagnose malignancy with
             high accuracy with dose comparable to that of a single
             mammogram. In this study, NSECT imaging was simulated for
             normal and malignant human breast tissue samples to
             determine the significance of individual elements in
             determining malignancy. The normal and malignant models were
             designed with different elemental compositions, and each was
             scanned spectroscopically using a simulated 2.5 MeV neutron
             beam. The number of incident neutrons was varied from 0.5
             million to 10 million neutrons. The resulting gamma spectra
             were evaluated through receiver operating characteristic
             (ROC) analysis to determine which trace elements were
             prominent enough to be considered markers for breast cancer
             detection. Four elemental isotopes (133Cs, 81Br, 79Br, and
             87Rb) at five energy levels were shown to be promising
             features for breast cancer detection with an area under the
             ROC curve (A(Z)) above 0.85. One of these elements--87Rb at
             1338 keV--achieved perfect classification at 10 million
             incident neutrons and could be detected with as low as 3
             million incident neutrons. Patient dose was calculated for
             each gamma spectrum obtained and was found to range from
             between 0.05 and 0.112 mSv depending on the number of
             neutrons. This simulation demonstrates that NSECT has the
             potential to noninvasively detect breast cancer through five
             prominent trace element energy levels, at dose levels
             comparable to other breast cancer screening
             techniques.},
   Language = {eng},
   Doi = {10.1118/1.2775669},
   Key = {fds319527}
}

@article{fds319528,
   Author = {Sharma, AC and Tourassi, GD and Kapadia, AJ and Harrawood, BP and Bender, JE and Crowell, AS and Kiser, MR and Howell, CR and Jr,
             FCE},
   Title = {Design and development of a high-energy gamma camera for use
             with NSECT imaging: Feasibility for breast
             Imaging},
   Journal = {IEEE Transactions on Nuclear Science},
   Volume = {54},
   Number = {5},
   Pages = {1498-1505},
   Year = {2007},
   Month = {October},
   url = {http://dx.doi.org/10.1109/TNS.2007.902367},
   Doi = {10.1109/TNS.2007.902367},
   Key = {fds319528}
}

@article{fds159375,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Tourassi GD, Kapadia AJ, Harrawood BP, Crowell
             AS, Kiser MR, Howell CR, and Floyd CE. Design and
             development of a high-energy gamma camera for use with NSECT
             imaging: Feasibility for breast imaging. IEEE Transactions
             on Nuclear Science. 2007;54:1498-1505.},
   Year = {2007},
   Key = {fds159375}
}

@article{fds159376,
   Author = {A.J. Kapadia},
   Title = {Floyd CE, Sharma AC, Bender JE, Kapadia AJ, Xia JQ,
             Harrawood BP, Tourassi GD, Lo JY, Kiser MR, Crowell AS,
             Pedroni RS, Macri RA, Tajima S, and Howell CR. Neutron
             stimulated emission computed tomography: Background
             corrections. Nuclear Instruments and Methods in Physics
             Research Section B. 2007;254:329-336.},
   Year = {2007},
   Key = {fds159376}
}

@article{fds159503,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Tourassi GD, Kapadia AJ, Crowell AS, Kiser MR,
             Hutcheson A, Harrawood BP, Howell CR, Floyd CE. Elemental
             Spectrum of a Mouse Obtained via Neutron Stimulation.
             Proceedings of SPIE Medical Imaging. 2007;6510:65100K.},
   Year = {2007},
   Key = {fds159503}
}

@article{fds159504,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Harrawood BP, Tourassi GD. A Geant4 Simulation
             for Iron Overload Detection using NSECT. Proceedings of IEEE
             Nuclear Science Symposium and Medical Imaging Conference.
             2007;6:4604-4607.},
   Year = {2007},
   Key = {fds159504}
}

@article{fds159505,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Kapadia AJ, Harrawood BP and Tourassi GD.
             Optimization of a rotating modulation collimator for neutron
             stimulated emission computed tomography (NSECT) imaging;
             IEEE Nuclear Science Symposium. 2007;5:3812-3815.},
   Year = {2007},
   Key = {fds159505}
}

@article{fds319533,
   Author = {Sharma, AC and Tourassi, GD and Kapadia, AJ and Crowell, AS and Kiser,
             MR and Hutcheson, A and Harrawood, BP and Howell, CR and Jr,
             CEF},
   Title = {Elemental spectrum of a mouse obtained via neutron
             stimulation},
   Journal = {Proceedings of SPIE},
   Volume = {6510},
   Number = {PART 1},
   Year = {2007},
   url = {http://dx.doi.org/10.1117/12.713731},
   Abstract = {Several studies have shown that the concentration of certain
             elements may be a disease indicator. We are developing a
             spectroscopic imaging technique, Neutron Stimulated Emission
             Computed Tomography (NSECT), to non-invasively measure and
             image elemental concentrations within the body. The region
             of interest is interrogated via a beam of highenergy
             neutrons that excite elemental nuclei through inelastic
             scatter. These excited nuclei then relax by emitting
             characteristic gamma radiation. Acquiring the gamma energy
             spectrum in a tomographic geometry allows reconstruction of
             elemental concentration images. Our previous studies have
             demonstrated NSECT's ability to obtain spectra and images of
             known elements and phantoms, as well as, initial
             interrogations of biological tissue. Here, we describe the
             results obtained from NSECT interrogation of a fixed mouse
             specimen. The specimen was interrogated via a 5MeV neutron
             beam for 9.3 hours in order to ensure reasonable counting
             statistics. The gamma energy spectrum was obtained using two
             High-Purity Germanium (HPGe) clover detectors. A background
             spectrum was obtained by interrogating a specimen container
             containing 50mL of 0.9% NaCl solution. Several elements of
             biological interest including 12C, 40Ca, 31P, and 39K were
             identified with greater then 90% confidence. This
             interrogation demonstrates the feasibility of NSECT
             interrogation of small animals. Interrogation with a
             commercial neutron source that provides higher neutron flux
             and lower energy (∼2.5MeV) neutrons would reduce scanning
             time and eliminate background from certain
             elements.},
   Doi = {10.1117/12.713731},
   Key = {fds319533}
}

@article{fds319534,
   Author = {Sharma, AC and Kapadia, AJ and Harrawood, BP and Tourassi,
             GD},
   Title = {Optimization of a rotating modulation collimator for Neutron
             Stimulated Emission Computed Tomography (NSECT)
             imaging},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Volume = {5},
   Pages = {3812-3815},
   Year = {2007},
   url = {http://dx.doi.org/10.1109/NSSMIC.2007.4436951},
   Abstract = {A high-energy gamma camera design is being developed for use
             with Neutron Simulated Emission Computed Tomography (NSECT).
             NSECT is a spectroscopic imaging technique that measures
             elemental concentrations in vivo through neutron
             interrogation and collection of the subsequent prompt
             characteristic gamma emission. NSECT operates in an energy
             range above that of typical nuclear medicine gamma cameras
             (0.3 - 2 MeV), and requires high-resolution gamma
             spectroscopy. We are developing a camera using a rotating
             modulation collimator (RMC) placed in front of a High Purity
             Germanium (HPGe) detector. The RMC consists of a pair of
             parallel slat collimators rotating in unison and as it
             rotates it modulates the number of incident gammas. Counting
             the number of incident gammas at each angle provides spatial
             information and allows reconstruction of images. There are
             six parameters in the camera system that can be optimized to
             improve image quality. A preliminary experiment was
             performed to determine the six parameters' relationship to
             each other and to image quality. Four subsequent experiments
             were performed based on the preliminary data to optimize the
             camera configuration. Results of these experiments found a
             tradeoff between system efficiency and spatial resolution,
             much like that for high-energy gamma collimation for
             standard gamma cameras. Point source reconstructions are
             provided to illustrate this tradeoff. © 2007
             IEEE.},
   Doi = {10.1109/NSSMIC.2007.4436951},
   Key = {fds319534}
}

@article{fds319535,
   Author = {Kapadia, AJ and Sharma, AC and Harrawood, BP and Tourassi,
             GD},
   Title = {GEANT4 simulation of an NSECT system for iron overload
             detection},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Volume = {6},
   Pages = {4604-4607},
   Year = {2007},
   url = {http://dx.doi.org/10.1109/NSSMIC.2007.4437134},
   Abstract = {Hemochromatosis (iron overload in liver) is a condition that
             causes serious consequences for the patient through an
             increase in the body's iron stores. Diagnosis of the excess
             iron, which is often stored in the liver, requires an
             invasive biopsy. We are developing neutron stimulated
             emission computed tomography (NSECT) as a non-invasive
             alternative to measure liver iron concentration to diagnose
             hemochromatosis. This measurement is performed using an
             incident neutron beam that scatters inelastically with iron
             nuclei in the liver, causing them to emit characteristic
             gamma-rays. An energy-sensitive gamma-ray detector is used
             to detect these gamma-rays and quantify the iron in the
             liver. Preliminary experiments have demonstrated an
             implementation of NSECT to quantify concentrations of iron
             and potassium in bovine liver tissue. Due to the prohibitive
             nature of these experiments, it is not feasible to perform
             system evaluation and optimization at each step using a
             nuclear accelerator. Here we describe a GEANT4 simulation of
             NSECT as a feasible alternative to perform system evaluation
             for iron overload diagnosis using computing resources only.
             The simulation model uses a 5 MeV neutron beam to scan a
             human liver phantom with induced iron overload. The liver is
             modeled as a composite shape combining a half-cylinder and a
             polyhedron, and is housed in a human torso filled with
             water. Gamma-ray spectra are generated to show element
             concentration within the liver. To determine the lower limit
             of iron overload detection, the concentration of iron in the
             liver is reduced from an initial high value, and the p-value
             of detecting peaks corresponding to iron is calculated at
             each step. The lower limit of detection is defined as the
             concentration at which the p-value of peak detection exceeds
             0.05. The limit of iron overload detection from this
             simulation was found to be 4 mg/g, which represents a
             clinically relevant value for iron overload. © 2007
             IEEE.},
   Doi = {10.1109/NSSMIC.2007.4437134},
   Key = {fds319535}
}

@article{fds319530,
   Author = {Sharma, AC and Tourassi, GD and Kapadia, AJ and Harrawood, BP and Bender, JE and Crowell, AS and Kiser, MR and Howell, CR and Jr,
             CEF},
   Title = {Design and development of a high-energy gamma camera for use
             with NSECT imaging: Feasibility for breast
             imaging},
   Journal = {IEEE Transactions on Nuclear Science},
   Volume = {54},
   Number = {5},
   Pages = {1498-1505},
   Year = {2007},
   url = {http://dx.doi.org/10.1109/TNS.2007.906058},
   Abstract = {A new spectroscopic imaging technique, Neutron Stimulated
             Emission Computed Tomography (NSECT), is currently being
             developed to non-invasively and non-destructively measure
             and image elemental concentrations within the body. NSECT
             has potential for use in breast imaging as several studies
             have shown a link between elemental concentration and tumor
             status. In NSECT, a region of interest is illuminated with a
             high-energy (3-5 MeV) beam of neutrons that scatter
             inelastically with elemental nuclei within the body. The
             characteristic gamma rays that are emitted as the excited
             nuclei relax allow the identification of elements and the
             formation of elemental composition images. This imaging
             technique requires high-resolution and high-energy gamma
             spectroscopy; thereby eliminating current scintillation
             crystal based position sensitive gamma cameras. Instead, we
             propose to adapt high-energy gamma imaging techniques used
             in space-based imaging. A High Purity Germanium (HPGe)
             detector provides high-resolution energy spectra while a
             rotating modulation collimator (RMC) placed in front of the
             detector modulates the incoming signal to provide spatial
             information. Counting the number of gamma events at each
             collimator rotation angle allows for reconstruction of
             images. Herein we report on the design and testing of a
             prototype RMC, a Monte Carlo simulation of this camera, and
             the use of this simulation tool to access the feasibility of
             imaging a breast with such a camera. The prototype RMC was
             tested with a 22Na point source and verified that the RMC
             modulates the gamma rays in a predictable manner. The Monte
             Carlo simulation accurately modeled this behavior. Other
             simulations were used to accurately reconstruct images of a
             point source located within a 10 cm cube, suggesting NSECT's
             potential as a breast imaging method. © 2007
             IEEE.},
   Doi = {10.1109/TNS.2007.906058},
   Key = {fds319530}
}

@article{fds319531,
   Author = {Kapadia, AJ and Sharma, AC and Tourassi, GD and Bender, JE and Crowell,
             AS and Kiser, MR and Howell, CR and Jr, CEF},
   Title = {Non-invasive estimation of potassium (39K) in Bovine Liver
             using Neutron Stimulated Emission Computed Tomography
             (NSECT)},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Volume = {4},
   Pages = {2076-2078},
   Year = {2007},
   url = {http://dx.doi.org/10.1109/NSSMIC.2006.354322},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             being developed as a non-invasive technique to measure
             element concentration in in-vivo tissue at molecular levels.
             We have developed a system that performs this task using an
             incident neutron beam that scatters inelastically with an
             atomic nucleus causing it to emit a characteristic gamma
             photon. An energy-sensitive gamma detector is used to detect
             this energy and identify the target atom. Here we describe
             an experiment to determine the concentration of natural
             potassium (39K) in bovine liver without the need for a
             biopsy. A 5 MeV neutron beam was used to scan a known
             quantity of bovine liver to obtain a gamma spectrum showing
             element concentration in the liver. An aqueous KCl solution
             calibration sample was then scanned to establish a ratio of
             potassium concentration to gamma counts for the experimental
             setup. Counts from gamma peaks corresponding to excited
             states in 39K were summed and compared with counts from the
             known calibration sample, to give the concentration of 39K
             in the liver. A high purity germanium (HPGe) clover detector
             was used to measure the emitted gamma energy. The results
             were validated through neutron activation analysis (NAA) of
             the liver sample. The concentration of 39K reported by NSECT
             was found to be within 13% of the NAA result, clearly
             demonstrating the ability of NSECT for non-invasive
             quantification of element concentration in tissue. © 2006
             IEEE.},
   Doi = {10.1109/NSSMIC.2006.354322},
   Key = {fds319531}
}

@article{fds319532,
   Author = {Sharma, AC and Tourassi, GD and Kapadia, AJ and Harrawood, BP and Bender, JE and Crowell, AS and Kiser, MR and Howell, CR and Jr,
             CEF},
   Title = {Design and construction of a prototype rotation modulation
             collimator for near-field high-energy spectroscopic gamma
             imaging},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Volume = {4},
   Pages = {2021-2024},
   Year = {2007},
   url = {http://dx.doi.org/10.1109/NSSMIC.2006.354310},
   Abstract = {Neutron Stimulated Emission Computed Tomography (NSECT) is
             being developed for in vivo measurement of the concentration
             and location of biologically relevant elements. NSECT is a
             spectroscopic imaging technique whereby the body is
             illuminated via high-energy neutrons that excite elemental
             nuclei that then relax through characteristic gamma
             radiation. This imaging technique requires high-resolution
             spectroscopy, thereby eliminating the use conventional
             scintillation gamma cameras. Consequently, high-purity
             germanium (HPGe) semi-conductor detectors are utilized,
             providing no spatial information. To obtain 2D elemental
             concentration images, we are adapting high-energy solar
             spectroscopy technology. A rotating modulation collimator
             (RMC) consisting of two parallel-slat collimators is placed
             in front of the detector to modulate the incoming signal in
             a manner predicted by its geometry. Reconstruction of 2D
             images is feasible by counting the number of incident gammas
             at each rotation angle. The challenge is to identify a RMC
             geometry that allows this method to work in the near-field
             environment, which has far fewer assumptions and
             simplifications than the infinite focus of solar imaging.
             Herein we describe construction of a prototype RMC and
             experiments conducted with a radioactive 22Na point source.
             These experiments verified that the RMC modulates the signal
             in manner consistent with its geometric and physical
             properties. © 2006 IEEE.},
   Doi = {10.1109/NSSMIC.2006.354310},
   Key = {fds319532}
}

@article{fds319529,
   Author = {Jr, CEF and Sharma, AC and Bender, JE and Kapadia, AJ and Xia, JQ and Harrawood, BP and Tourassi, GD and Lo, JY and Kiser, MR and Crowell, AS and Pedroni, RS and Macri, RA and Tajima, S and Howell,
             CR},
   Title = {Neutron stimulated emission computed tomography: Background
             corrections},
   Journal = {Nuclear Instruments and Methods in Physics Research Section
             B: Beam Interactions with Materials and Atoms},
   Volume = {254},
   Number = {2},
   Pages = {329-336},
   Year = {2007},
   url = {http://dx.doi.org/10.1016/j.nimb.2006.11.098},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             an imaging technique that provides an in-vivo tomographic
             spectroscopic image of the distribution of elements in a
             body. To achieve this, a neutron beam illuminates the body.
             Nuclei in the body along the path of the beam are stimulated
             by inelastic scattering of the neutrons in the beam and emit
             characteristic gamma photons whose unique energy identifies
             the element. The emitted gammas are collected in a
             spectrometer and form a projection intensity for each
             spectral line at the projection orientation of the neutron
             beam. Rotating and translating either the body or the beam
             will allow a tomographic projection set to be acquired.
             Images are reconstructed to represent the spatial
             distribution of elements in the body. Critical to this
             process is the appropriate removal of background gamma
             events from the spectrum. Here we demonstrate the
             equivalence of two background correction techniques and
             discuss the appropriate application of each. © 2006
             Elsevier B.V. All rights reserved.},
   Doi = {10.1016/j.nimb.2006.11.098},
   Key = {fds319529}
}

@article{fds319536,
   Author = {Floyd, CE and Bender, JE and Sharma, AC and Kapadia, A and Xia, J and Harrawood, B and Tourassi, GD and Lo, JY and Crowell, A and Howell,
             C},
   Title = {Introduction to neutron stimulated emission computed
             tomography.},
   Journal = {Physics in Medicine and Biology},
   Volume = {51},
   Number = {14},
   Pages = {3375-3390},
   Year = {2006},
   Month = {July},
   ISSN = {0031-9155},
   url = {http://dx.doi.org/10.1088/0031-9155/51/14/006},
   Keywords = {Gamma Rays • Humans • Imaging, Three-Dimensional
             • Neoplasms • Neutrons* • Phantoms, Imaging
             • Radiographic Image Interpretation, Computer-Assisted
             • Scattering, Radiation • Spectrometry, Gamma
             • Tissue Distribution • Tomography,
             Emission-Computed • methods • methods* •
             radiotherapy*},
   Abstract = {Neutron stimulated emission computed tomography (NSECT) is
             presented as a new technique for in vivo tomographic
             spectroscopic imaging. A full implementation of NSECT is
             intended to provide an elemental spectrum of the body or
             part of the body being interrogated at each voxel of a
             three-dimensional computed tomographic image. An external
             neutron beam illuminates the sample and some of these
             neutrons scatter inelastically, producing characteristic
             gamma emission from the scattering nuclei. These
             characteristic gamma rays are acquired by a gamma
             spectrometer and the emitting nucleus is identified by the
             emitted gamma energy. The neutron beam is scanned over the
             body in a geometry that allows for tomographic
             reconstruction. Tomographic images of each element in the
             spectrum can be reconstructed to represent the spatial
             distribution of elements within the sample. Here we offer
             proof of concept for the NSECT method, present the first
             single projection spectra acquired from multi-element
             phantoms, and discuss potential biomedical
             applications.},
   Language = {eng},
   Doi = {10.1088/0031-9155/51/14/006},
   Key = {fds319536}
}

@article{fds159495,
   Author = {A.J. Kapadia},
   Title = {Floyd CE, Bender JE, Harrawood BP, Sharma AC, Kapadia AJ,
             Tourassi GD, Lo JY, and Howell CR. Breast cancer diagnosis
             using Neutron Stimulated Emission Computed Tomography: Dose
             and Count requirements. Proceedings of SPIE Symposium on
             Medical Imaging. 2006;6142:597-603.},
   Year = {2006},
   Key = {fds159495}
}

@article{fds159496,
   Author = {A.J. Kapadia},
   Title = {Bender JE, Floyd CE, Harrawood BP, Kapadia AJ, Sharma AC,
             and Jesneck JL. The effect of detector resolution for
             quantitative analysis of neutron stimulated emission
             computed tomography. Proceedings of SPIE Medical Imaging.
             2006;6142:1597-1605.},
   Year = {2006},
   Key = {fds159496}
}

@article{fds159497,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR,
             Crowell AS, Kiser MR, and Floyd CE. Neutron Spectroscopy of
             Mouse Using Neutron Stimulated Emission Computed Tomography
             (NSECT). Proceedings of IEEE Nuclear Science Symposium and
             Medical Imaging Conference. 2006;6:3546-3548.},
   Year = {2006},
   Key = {fds159497}
}

@article{fds159498,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR,
             Crowell AS, Kiser MR, and Floyd CE, "Non-Invasive Estimation
             of Potassium (39K) in Bovine Liver Using Neutron Stimulated
             Emission Computed Tomography (NSECT)," Proceedings of IEEE
             Nuclear Science Symposium, Medical Imaging Conference.
             2006;4:2076-2078.},
   Year = {2006},
   Key = {fds159498}
}

@article{fds159499,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Sharma AC, Tourassi GD, Bender JE, Howell CR,
             Crowell AS, Kiser MR, and Floyd CE, "Neutron Stimulated
             Emission Computed Tomography (NSECT) for Early Detection of
             Breast Cancer," Proceedings of IEEE Nuclear Science
             Symposium and Medical Imaging Conference.
             2006;6:3928-3931.},
   Year = {2006},
   Key = {fds159499}
}

@article{fds159500,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Tourassi GD, Kapadia AJ, Harrawood BP, Bender JE,
             Crowell AS, Kiser MR, Howell CR, and Floyd CE. Design and
             Construction of a Prototype Rotation Modulation Collimator
             for near-Field High-Energy Spectroscopic Gamma Imaging.
             Proceedings of IEEE Nuclear Science Symposium and Medical
             Imaging Conference. 2006:4:2021-2024.},
   Year = {2006},
   Key = {fds159500}
}

@article{fds159501,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Tourassi GD, Kapadia AJ, Bender JE, Xia JQ,
             Harrawood BP, Crowell AS, Kiser MR, Howell CR, and Floyd CE.
             Development of a High-Energy Gamma Camera for Use with NSECT
             Imaging of the Breast. Proceedings of IEEE Nuclear Science
             Symposium and Medical Imaging Conference.
             2006;6:3925-3927.},
   Year = {2006},
   Key = {fds159501}
}

@article{fds159502,
   Author = {A.J. Kapadia},
   Title = {Sharma AC, Floyd CE, Harrawood BP, Tourassi GD, Kapadia AJ,
             Bender JE, Lo JY, and Howell CR. Rotating slat collimator
             design for high-energy near-field imaging. Proceedings of
             SPIE Medical Imaging. 2006;6142:405-413.},
   Year = {2006},
   Key = {fds159502}
}

@article{fds319541,
   Author = {Kapadia, AJ and Sharma, AC and Tourassi, GD and Bender, JE and Crowell,
             AS and Kiser, MR and Howell, CR and Jr, FCE and IEEE},
   Title = {Neutron Spectroscopy of Mouse Using Neutron Stimulated
             Emission Computed Tomography (NSECT)},
   Journal = {IEEE Conference Record - Nuclear Science Symposium & Medical
             Imaging Conference : IEEE Nuclear Science Symposium And
             Medical Imaging Conference. Proceedings},
   Pages = {3546-3548},
   Year = {2006},
   Key = {fds319541}
}

@article{fds319537,
   Author = {Jr, CEF and Bender, JE and Harrawood, B and Sharma, AC and Kapadia, A and Tourassi, GD and Lo, JY and Howell, C},
   Title = {Breast cancer diagnosis using neutron stimulated emission
             computed tomography: Dose and count requirements},
   Journal = {Proceedings of SPIE},
   Volume = {6142 II},
   Year = {2006},
   url = {http://dx.doi.org/10.1117/12.656045},
   Abstract = {Neutron Stimulated Emission Computed Tomography (NSECT) was
             evaluated as a potential technique for breast cancer
             diagnosis. NSECT can form a 3D tomographic image with an
             elemental (isotopic) spectrum provided at each reconstructed
             voxel. The target is illuminated (in vivo) by a neutron beam
             that scatters in-elastically producing characteristic gamma
             emission that is acquired tomographically with a
             spectrograph. Images are reconstructed of each element in
             the acquired spectrum. NSECT imaging was simulated for
             benign and malignant breast masses. A range of the number of
             incident neutrons was simulated from 19 million to 500k
             neutrons. Simulation included all known primary and
             secondary physical interactions in both the breast as well
             as in the spectrometer. Characteristic energy spectra were
             acquired by simulation and were analyzed for statistically
             significant differences between benign and malignant
             breasts. For 1 million incident neutrons, there were 61
             differences in the spectra that were statistically
             significant (p &lt; 0,05), Of these, 23 matched known
             characteristic emission from 6 elements that have been found
             in the breast (Br, Cs, K, Mn, Rb, Zn). The dose to two
             breasts was less than 3% of the dose of a 4 view screening
             mammogram, Increasing the dose to 52% of the mammogram (19
             million neutrons) provided 89 significant spectral
             differences that matched 30 known emissions from 7 elements
             that have been found in the breast (Br, Co, Cs, K, Mn, Rb,
             Zn). Decreasing the dose to 1.4% (500K neutrons) eliminated
             all statistically significant matches to known elements.
             This study suggests that NSECT may be a viable technique for
             detecting human breast cancer in vivo at a reduced dose
             compared to 4 view screening mammography.},
   Doi = {10.1117/12.656045},
   Key = {fds319537}
}

@article{fds319538,
   Author = {Sharma, A and Floyd, C and Harrawood, B and Tourassi, G and Kapadia, A and Bender, J and Lo, J and Howell, C},
   Title = {Rotating slat collimator design for high-energy near-field
             imaging},
   Journal = {Proceedings of SPIE},
   Volume = {6142 I},
   Year = {2006},
   url = {http://dx.doi.org/10.1117/12.653929},
   Abstract = {Certain elements (such as Fe, Cu, Zn, etc.) are vital to the
             body and an imbalance of such elements can either be a
             symptom or cause of certain pathologies. Neutron Stimulated
             Emission Computed Tomography (NSECT) is a spectroscopic
             imaging technique whereby the body is illuminated via a beam
             of neutrons causing elemental nuclei to become excited and
             emit characteristic gamma radiation. Acquiring the gamma
             energy spectra in a tomographic geometry allows
             reconstruction of elemental concentration images. Previously
             we have demonstrated the feasibility of NSECT using first
             generation CT approaches; while successful, the approach
             does not scale well and has limited resolution.
             Additionally, current gamma cameras operate in an energy
             range too low for NSECT imaging. However, the orbiting
             Reuven Ramaty High Energy Solar Spectroscopic Imager
             (RHESSI) captures and images gamma rays over the high-energy
             range equivalent to NSECT's (3 keV to 17 MeV) by utilizing
             Collimator-based Fourier transform imaging. A High Purity
             Germanium (HPGe) detector counts the number of energy events
             per unit of time, providing spectroscopic data. While a pair
             of rotating collimators placed in front of the detector
             modulates the number of gamma events, providing spatial
             information. Knowledge of the number of energy events at
             each discrete collimator angle allows for 2D image
             reconstruction. This method has proven successful at a focus
             of infinity in the RHESSI application. Our goal is to
             achieve similar results at a reasonable near-field focus.
             Here we describe the results of our simulations to implement
             a rotating modulation collimator (RMC) gamma imager for use
             in NSECT using simulations in Matlab. To determine feasible
             collimator setups and the stability of the inverse problem a
             Matlab environment was created that uses the geometry of the
             system to generate ID observation data from 2D images and
             then to reconstruct 2D images using the MLEM algorithm.
             Reasonable collimator geometries were determined, successful
             reconstruction was achieved and the inverse problem was
             found to be stable.},
   Doi = {10.1117/12.653929},
   Key = {fds319538}
}

@article{fds319539,
   Author = {Bender, JE and Floyd, CE and Harrawood, BP and Kapadia, AJ and Sharma,
             AC and Jesneck, JL},
   Title = {The effect of detector resolution for quantitative analysis
             of neutron stimulated emission computed tomography},
   Journal = {Proceedings of SPIE},
   Volume = {6142 III},
   Year = {2006},
   url = {http://dx.doi.org/10.1117/12.652812},
   Abstract = {Previous research has shown benign and cancerous tissues to
             have different chemical make-ups. To measure the elemental
             concentration of biological samples noninvasively, we used
             neutron stimulated emission computed tomography (NSECT).
             When an incident neutron scatters inelastically from an
             atomic nucleus, it emits characteristic gamma energies,
             allowing for measurement of the elemental concentration of
             biological samples. Thus NSECT has the potential to be a
             method for precancerous tissue detection. In Monte Carlo
             simulations, we bombarded both a benign and a malignant
             human breast with 50 million neutrons. The resulting photon
             spectra were blurred to model the detector resolutions and
             then analyzed for peak detection. This simulation study
             analyzed the characteristic spectra using three detectors of
             different resolutions: a High-Purity Germanium (HPGe)
             semiconductor, a Bismuth Germanate (BGO) scintillator, and a
             Sodium Iodide (NaI) scintillator. The effective energy
             resolutions of these detectors are 0.1%, 7%, and 12%,
             respectively. The detectability of element peaks in the
             breast model was greatly reduced when the blur increased
             from just 0.1% to 7%. These initial experiments are valuable
             in choosing optimal detectors for peak detection in further
             NSECT studies and indicate that high-resolution detectors,
             such as HPGe, are required for using spectral peak analysis
             for breast cancer prediction.},
   Doi = {10.1117/12.652812},
   Key = {fds319539}
}

@article{fds319540,
   Author = {Sharma, AC and Tourassi, GD and Kapadia, AJ and Bender, JE and Xia, JQ and Harrawood, BP and Crowell, AS and Kiser, MR and Howell, CR and Jr, FCE and IEEE},
   Title = {Development of a High-Energy Gamma Camera for use with NSECT
             Imaging of the Breast},
   Journal = {IEEE Conference Record - Nuclear Science Symposium & Medical
             Imaging Conference : IEEE Nuclear Science Symposium And
             Medical Imaging Conference. Proceedings},
   Pages = {3925-3927},
   Year = {2006},
   Key = {fds319540}
}

@article{fds319542,
   Author = {Kapadia, AJ and Sharma, AC and Tourassi, GD and Bender, JE and Crowell,
             AS and Kiser, MR and Howell, CR and Jr, FCE and IEEE},
   Title = {Neutron Stimulated Emission Computed Tomography (NSECT) for
             Early Detection of Breast Cancer},
   Journal = {IEEE Conference Record - Nuclear Science Symposium & Medical
             Imaging Conference : IEEE Nuclear Science Symposium And
             Medical Imaging Conference. Proceedings},
   Pages = {3928-3931},
   Year = {2006},
   url = {http://dx.doi.org/10.1109/NSSMIC.2006.353847},
   Doi = {10.1109/NSSMIC.2006.353847},
   Key = {fds319542}
}

@article{fds159493,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ and Floyd CE. An attenuation correction technique
             to correct for neutron and gamma attenuation in the
             reconstructed image of a neutron stimulated emission
             computed tomography (NSECT) system. Proceedings of SPIE
             Medical Imaging. 2005;5745:737-743.},
   Year = {2005},
   Key = {fds159493}
}

@article{fds159494,
   Author = {A.J. Kapadia},
   Title = {Kapadia AJ, Floyd CE, Bender JE, Howell CR, Crowell AS, and
             Kiser MR. Non-invasive quantification of iron 56-Fe in beef
             liver using neutron stimulated emission computed tomography.
             Proceedings of IEEE Nuclear Science Symposium and Medical
             Imaging Conference. 2005;4:2232-2234.},
   Year = {2005},
   Key = {fds159494}
}

@article{fds319544,
   Author = {Kapadia, AJ and Jr, CEF},
   Title = {An attenuation correction technique to correct for neutron
             and gamma attenuation in the reconstructed image of a
             neutron stimulated emission computed tomography (NSECT)
             system},
   Journal = {Proceedings of SPIE},
   Volume = {5745},
   Number = {II},
   Pages = {737-743},
   Year = {2005},
   url = {http://dx.doi.org/10.1117/12.596107},
   Abstract = {Neutron spectroscopy is being developed as a tomographic
             tool to measure trace element concentration in the body at
             molecular levels. We are developing a neutron stimulated
             emission computed tomography (NSECT) system using inelastic
             scattering of neutrons by target nuclei, to identify
             elements and their concentration in tissue. An incoming
             neutron scatters inelastically with an atomic nucleus, which
             emits a gamma photon of specific energy. This energy, which
             is detected by an energy-sensitive Gamma detector, is
             characteristic of the scattering nucleus. The neutron beam
             and gamma photons undergo considerable attenuation while
             passing through the body, causing a reduction in detected
             counts leading to inaccurate reconstruction. We describe a
             technique to correct for this attenuation as follows. The
             scanning geometry used for data acquisition is simulated.
             The lengths of attenuating material lying in the path of the
             neutron beam are calculated. Neutron attenuation is
             determined along this path, using attenuation coefficients
             for each element. Gamma attenuation is calculated similarly
             for the path between the point of gamma origin and the
             detector. A transmission profile is then determined for each
             projection, using the product of the neutron and gamma
             attenuations for every point along the projection. The
             inverse of the integral of this profile yields a correction
             factor. The experimental data is multiplied by the
             correction factors to yield attenuation corrected
             projections. After correction, the projection data is seen
             to represent the known elemental distribution more
             accurately. This correction technique improves the
             consistency of the projections, and leads to improved
             accuracy in the reconstructed NSECT images.},
   Doi = {10.1117/12.596107},
   Key = {fds319544}
}

@article{fds319543,
   Author = {Kapadia, AJ and Jr, CEF and Bender, JE and Howell, CR and Crowell, AS and Kiser, MR},
   Title = {Non-invasive quantification of iron56Fe in beef
             liver using neutron stimulated emission computed
             tomography},
   Journal = {IEEE Nuclear Science Symposium Conference
             Record},
   Volume = {4},
   Pages = {2232-2234},
   Year = {2005},
   url = {http://dx.doi.org/10.1109/NSSMIC.2005.1596778},
   Abstract = {Neutron spectroscopy is being developed as a noninvasive
             tool to measure element concentration in the body at
             molecular levels. We are developing a neutron stimulated
             emission computed tomography (NSECT) system to identify
             element concentrations in tissue, using inelastic scattering
             of neutrons by target nuclei. An incident neutron scatters
             inelastically with an atomic nucleus to emit a gamma photon
             whose energy is characteristic of the scattering nucleus.
             This energy is detected by an energy-sensitive gamma
             detector to identify the target atom. Here we describe an
             experiment to noninvasively determine the concentration of
             natural iron (56Fe) in beef liver. A 7.5 MeV neutron beam
             was used to scan a known quantity of solid iron and
             establish a ratio of iron concentration to gamma counts for
             the experimental setup. A known quantity of beef liver was
             then scanned using the same experimental setup, to obtain
             gamma spectra showing element concentrations in the liver.
             Counts from gamma peaks corresponding to excited states in
             iron were compared with counts from the known iron sample,
             to yield the iron concentration in the liver. A high purity
             germanium (HPGe) detector was used to measure the emitted
             gamma energy. Although the results obtained in this
             experiment are slightly higher than normal iron limits
             reported in various studies, they demonstrate the
             technique's ability to noninvasively quantify iron
             concentration in a biological organ. © 2005
             IEEE.},
   Doi = {10.1109/NSSMIC.2005.1596778},
   Key = {fds319543}
}

@article{fds159492,
   Author = {A.J. Kapadia},
   Title = {Floyd CE, Howell CR, Harrawood BP, Crowell AS, Kapadia AJ,
             Macri R, Xia JQ, Pedroni R, Bowsher J, Kiser MR, Tourassi
             GD, Tornow W, and Walter R. Neutron Stimulated Emission
             Computed Tomography of Stable Isotopes. Proceedings of SPIE
             Medical Imaging. 2004;5368:248-254.},
   Year = {2004},
   Key = {fds159492}
}

@article{fds319545,
   Author = {Jr, CEF and Howell, C and Harrawood, B and Crowell, A and Kapadia, A and Macri, R and Xia, J and Pedroni, R and Bowsher, J and Kiser, M and Tourassi, G and Tornow, W and Walter, R},
   Title = {Neutron stimulated emission computed tomography of stable
             isotopes},
   Journal = {Proceedings of SPIE - The International Society for Optical
             Engineering},
   Volume = {5368},
   Number = {1},
   Pages = {248-254},
   Year = {2004},
   url = {http://dx.doi.org/10.1117/12.535350},
   Abstract = {Here we report on the development of a new molecular imaging
             technique using inelastic scattering of fast neutrons.
             Earlier studies demonstrated a significant difference in
             trace element concentrations between benign and malignant
             tissue for several cancers including breast, lung, and
             colon. Unfortunately, the measurement techniques were not
             compatible with living organisms and this discovery did not
             translate into diagnostic techniques. Recently we have
             developed a tomographic approach to measuring the trace
             element concentrations using neutrons to stimulate
             characteristic gamma emission from atomic nuclei in the
             body. Spatial projections of the emitted energy spectra
             allow tomographic image reconstruction of the elemental
             concentrations. In preliminary experiments, spectra have
             been acquired using a 7.5MeV neutron beam incident on
             several multielement phantoms. These experiments demonstrate
             our ability to determine the presence of Oxygen, Carbon,
             Copper, Iron, and Calcium. We desribe the experimental
             technique and present acquired spectra.},
   Doi = {10.1117/12.535350},
   Key = {fds319545}
}