Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596209
M. Reinhard, I. Cornelius, D. Prokopovich, A. Wroe, A. Rosenfeld, V. Pisacane, J. Ziegler, M. Nelson, F. Cucinotta, M. Zaider, J. Dicello
The response of a solid state microdosimeter based on semiconductor on insulator (SOI) technology to a 238PuBe neutron source was investigated. Simulations of the device response using the GEANT4 Monte Carlo toolkit are also presented. The microdosimetric spectra was measured for lineal energies above 1 keV/mum. The possible application of the SOI microdosimeter for radiation protection applications in the form of a personnel microdosimeter is suggested
{"title":"Response of a SOI microdosimeter to a /sup 238/PuBe neutron source","authors":"M. Reinhard, I. Cornelius, D. Prokopovich, A. Wroe, A. Rosenfeld, V. Pisacane, J. Ziegler, M. Nelson, F. Cucinotta, M. Zaider, J. Dicello","doi":"10.1109/NSSMIC.2005.1596209","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596209","url":null,"abstract":"The response of a solid state microdosimeter based on semiconductor on insulator (SOI) technology to a 238PuBe neutron source was investigated. Simulations of the device response using the GEANT4 Monte Carlo toolkit are also presented. The microdosimetric spectra was measured for lineal energies above 1 keV/mum. The possible application of the SOI microdosimeter for radiation protection applications in the form of a personnel microdosimeter is suggested","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116200700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596621
Feng Zhang, Zhong He, Dan Xu, Ling-Jian Meng
An experimental small animal PET using two 3-D position sensitive CdZnTe detectors was developed and tested. Each 1.5/spl times/1.5/spl times/1 cm/sup 3/ CdZnTe detector employs 11 by 11 pixellated anodes wire-bonded to the VAS3.1/TAT3/MCR3 readout electronics. Each detector can obtain the deposited energy and 3-D coordinates for single-pixel and multiple-pixel events. Both systems achieved energy resolutions of better than 1.0% FWHM at 662 ReV for single-pixel events and better than 1.5% FWHM at 662 ReV for two-pixel events. The position resolution of each detector was estimated to be /spl sim/1.3/spl times/1.3/spl times/0.5 mm/sup 3/. Modifications to the firmware of the readout board and additions of custom-built circuitry enabled coincidence measurement between two 3-D CdZnTe detector systems using VAS3.1/TAT3/MCR3 readout systems. Spatial resolution improvements by using depth of interaction (DOI) and by identifying the first interaction using Compton scattering angle reconstruction are reported and discussed.
{"title":"Feasibility study of using two 3-D position sensitive CZT detectors for small animal PET","authors":"Feng Zhang, Zhong He, Dan Xu, Ling-Jian Meng","doi":"10.1109/NSSMIC.2005.1596621","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596621","url":null,"abstract":"An experimental small animal PET using two 3-D position sensitive CdZnTe detectors was developed and tested. Each 1.5/spl times/1.5/spl times/1 cm/sup 3/ CdZnTe detector employs 11 by 11 pixellated anodes wire-bonded to the VAS3.1/TAT3/MCR3 readout electronics. Each detector can obtain the deposited energy and 3-D coordinates for single-pixel and multiple-pixel events. Both systems achieved energy resolutions of better than 1.0% FWHM at 662 ReV for single-pixel events and better than 1.5% FWHM at 662 ReV for two-pixel events. The position resolution of each detector was estimated to be /spl sim/1.3/spl times/1.3/spl times/0.5 mm/sup 3/. Modifications to the firmware of the readout board and additions of custom-built circuitry enabled coincidence measurement between two 3-D CdZnTe detector systems using VAS3.1/TAT3/MCR3 readout systems. Spatial resolution improvements by using depth of interaction (DOI) and by identifying the first interaction using Compton scattering angle reconstruction are reported and discussed.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124871430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596636
R. Yao, S. Balakrishnan, S. Ambwani, V. Rathod, Y. Shao
With a half-live of 4.2 days, iodine-124 (124I) is suitable for studying antibodies and drug analogues in animals that have a biological half-live in days. The special challenges with 124 I imaging on animal PET are: 1) the high fraction of high-energy, non-annihilation gamma-rays that introduce true coincidences which elevate the image background activity, and 2) the significant degradation of spatial resolution due to the high positron energies. By simulations and experiments on an animal PET scanner, we characterized these two unique degradation factors and evaluated the corresponding correction methods. The preliminary results of applying non-annihilation true coincidence correction and using 124I specific point spread function in the system matrix of reconstruction algorithm showed improved contrast and resolution recovery. These findings indicate that higher-resolution, quantitative 1241 applications can be achieved
{"title":"Quantitative iodine-124 imaging on animal PET","authors":"R. Yao, S. Balakrishnan, S. Ambwani, V. Rathod, Y. Shao","doi":"10.1109/NSSMIC.2005.1596636","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596636","url":null,"abstract":"With a half-live of 4.2 days, iodine-124 (124I) is suitable for studying antibodies and drug analogues in animals that have a biological half-live in days. The special challenges with 124 I imaging on animal PET are: 1) the high fraction of high-energy, non-annihilation gamma-rays that introduce true coincidences which elevate the image background activity, and 2) the significant degradation of spatial resolution due to the high positron energies. By simulations and experiments on an animal PET scanner, we characterized these two unique degradation factors and evaluated the corresponding correction methods. The preliminary results of applying non-annihilation true coincidence correction and using 124I specific point spread function in the system matrix of reconstruction algorithm showed improved contrast and resolution recovery. These findings indicate that higher-resolution, quantitative 1241 applications can be achieved","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127073514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596208
C. Lacasta, J. Bernabeu, D. Burdette, E. Chesi, N. Clinthorne, Y. Dewaraja, K. Honscheid, H. Kagan, G. Llosá, M. Mikuž, P. Modesto, W. Rogers, A. Studen, P. Weilhammer, L. Zhang, D. Žontar
A first prototype of a Compton prostate probe has been built using a stack of five 4times1 cm2, 1 mm thick silicon pad detectors as a scatter detector, surrounded by three scintillation detectors in which the absorption of the scattered photons takes place. The silicon pad dimensions are 1.4times1.4 mm which provide the required spatial resolution. The energy resolution in the silicon sensors is about 1.4 keV FWHM as determined from several gamma sources. The results obtained validate the simulation predictions that foresee an improvement over current SPECT techniques by a factor 16-40 in sensitivity and 4-5 in spatial resolution simultaneously for an intra-rectal probe built employing this concept and placed at 2 cm from the prostate
{"title":"Results from a first prototype of a Compton prostate probe","authors":"C. Lacasta, J. Bernabeu, D. Burdette, E. Chesi, N. Clinthorne, Y. Dewaraja, K. Honscheid, H. Kagan, G. Llosá, M. Mikuž, P. Modesto, W. Rogers, A. Studen, P. Weilhammer, L. Zhang, D. Žontar","doi":"10.1109/NSSMIC.2005.1596208","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596208","url":null,"abstract":"A first prototype of a Compton prostate probe has been built using a stack of five 4times1 cm2, 1 mm thick silicon pad detectors as a scatter detector, surrounded by three scintillation detectors in which the absorption of the scattered photons takes place. The silicon pad dimensions are 1.4times1.4 mm which provide the required spatial resolution. The energy resolution in the silicon sensors is about 1.4 keV FWHM as determined from several gamma sources. The results obtained validate the simulation predictions that foresee an improvement over current SPECT techniques by a factor 16-40 in sensitivity and 4-5 in spatial resolution simultaneously for an intra-rectal probe built employing this concept and placed at 2 cm from the prostate","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"313 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130831754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596676
Chi Liu, L. Volokh, Xide Zhao, Jingyan Xu, Taek-Soo Lee, B. Tsui
The purpose of this study is to evaluate the performance of four block-iterative algorithms, ordered-subsets expectation-maximization (OS-EM), rescaled block-iterative EM (RBI-EM), modified row-action maximum likelihood algorithm (RAMLA) and rescaled block-iterative maximum a posteriori EM (RBI-MAP-EM), for In-111 ProstaScint/spl reg/ SPECT image reconstruction. The 3D NCAT phantom with realistic In-111 ProstaScint/spl reg/ activity distribution was used in the study. Noise-free and noisy projections of the phantom obtained using a medium-energy general-purpose (MEGP) collimator were generated using Monte Carlo simulation methods. For each algorithm, the projection data were reconstructed with the compensations for attenuation, collimator-detector response and scatter. Image quality was evaluated in terms of FWHM of a profile through a small blood vessel, normalized mean square error (NMSE), ensemble normalized standard deviation (NSDE) of a uniform region of interest (ROI) in the reconstructed image measured from 30 noise realizations, and regional NSD (NSDR) of an ROI measure from 1 noise realization. The results indicated that, RBI-EM has superior performance than that of OS-EM when less than 4 views per subset were used and similar performance when 4 or more views per subset were used. Modified RAMLA provides similar image quality with a slower convergence rate than that of OS-EM. Using well-chosen parameters, RBI-MAP-EM provides increased noise smoothing with less loss in resolution and error. We conclude that when compared with OS-EM, the RBI-EM and modified RAMLA have the same performance at a slower convergence rate, while the RBI-MAP-EM has superior performance and can potentially improve image quality.
{"title":"Performance evaluation of block-iterative algorithms for SPECT reconstruction","authors":"Chi Liu, L. Volokh, Xide Zhao, Jingyan Xu, Taek-Soo Lee, B. Tsui","doi":"10.1109/NSSMIC.2005.1596676","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596676","url":null,"abstract":"The purpose of this study is to evaluate the performance of four block-iterative algorithms, ordered-subsets expectation-maximization (OS-EM), rescaled block-iterative EM (RBI-EM), modified row-action maximum likelihood algorithm (RAMLA) and rescaled block-iterative maximum a posteriori EM (RBI-MAP-EM), for In-111 ProstaScint/spl reg/ SPECT image reconstruction. The 3D NCAT phantom with realistic In-111 ProstaScint/spl reg/ activity distribution was used in the study. Noise-free and noisy projections of the phantom obtained using a medium-energy general-purpose (MEGP) collimator were generated using Monte Carlo simulation methods. For each algorithm, the projection data were reconstructed with the compensations for attenuation, collimator-detector response and scatter. Image quality was evaluated in terms of FWHM of a profile through a small blood vessel, normalized mean square error (NMSE), ensemble normalized standard deviation (NSDE) of a uniform region of interest (ROI) in the reconstructed image measured from 30 noise realizations, and regional NSD (NSDR) of an ROI measure from 1 noise realization. The results indicated that, RBI-EM has superior performance than that of OS-EM when less than 4 views per subset were used and similar performance when 4 or more views per subset were used. Modified RAMLA provides similar image quality with a slower convergence rate than that of OS-EM. Using well-chosen parameters, RBI-MAP-EM provides increased noise smoothing with less loss in resolution and error. We conclude that when compared with OS-EM, the RBI-EM and modified RAMLA have the same performance at a slower convergence rate, while the RBI-MAP-EM has superior performance and can potentially improve image quality.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130411624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596860
J. Dey, T. Pan, M. Smyczynski, H. Pretorias, D. Choi, M. King
One of the factors limiting the diagnostic accuracy of cardiac SPECT perfusion imaging is the respiratory motion of the heart. Several authors have investigated the motion of heart due to respiration. In this work we have 4D-CT data for 7 patients, consisting of 10 respiration gated non-contrast CT datasets covering the heart region for each patient. We perform a segmentation and registration of the heart datasets in sequence to determine the gross rigid-body motion of the heart due to respiration. For each patient, we segment the heart with a prior shape with an initial pose on one coronal slice of one of the respiration stages, and then the algorithm tracks the object through the other coronal slices. The segmentation results for first stage of respiration are used to initiate the segmentation of the heart at second stage, and so on for the other stages of respiration. A 6-parameter rigid-body registration of the first stage of respiration to the 9 consequent stages estimates the gross motion of the heart. The results of tracking heart motion for the 7 patients indicate a SI axis translation with an (absolute) range of 2.6 to 10.7 mm and mean of 5.7 mm, and standard deviation of 3.7 mm, during expiration. Mean rotations of 3.5 deg about the AP-axis, and 1.2 deg about the RL axis were also observed
{"title":"Investigation of respiration motion of the heart based on semi-automated segmentation and modeling of respiratory-gated CT data","authors":"J. Dey, T. Pan, M. Smyczynski, H. Pretorias, D. Choi, M. King","doi":"10.1109/NSSMIC.2005.1596860","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596860","url":null,"abstract":"One of the factors limiting the diagnostic accuracy of cardiac SPECT perfusion imaging is the respiratory motion of the heart. Several authors have investigated the motion of heart due to respiration. In this work we have 4D-CT data for 7 patients, consisting of 10 respiration gated non-contrast CT datasets covering the heart region for each patient. We perform a segmentation and registration of the heart datasets in sequence to determine the gross rigid-body motion of the heart due to respiration. For each patient, we segment the heart with a prior shape with an initial pose on one coronal slice of one of the respiration stages, and then the algorithm tracks the object through the other coronal slices. The segmentation results for first stage of respiration are used to initiate the segmentation of the heart at second stage, and so on for the other stages of respiration. A 6-parameter rigid-body registration of the first stage of respiration to the 9 consequent stages estimates the gross motion of the heart. The results of tracking heart motion for the 7 patients indicate a SI axis translation with an (absolute) range of 2.6 to 10.7 mm and mean of 5.7 mm, and standard deviation of 3.7 mm, during expiration. Mean rotations of 3.5 deg about the AP-axis, and 1.2 deg about the RL axis were also observed","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"698 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125488846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596910
A. Simon, Elisena A. G. Seravalli, Roger W. Kreuger, Jeroen Hendrikse, E. Loeff, Ben J. M. Heijmen, C. E. W. V. Eijk
We report on the characterization of a gas detector, based on gas electron multipliers (GEMs), for use in intensity modulated radiation therapy (IMRT). The light emitted during the gas multiplication process in 1 atm Ar-CF4 (96-4) scintillating gas mixture has been studied as a function of applied voltages and treatment conditions such as beam time and photon energy
{"title":"A scintillating triple GEM beam monitor for radiation therapy","authors":"A. Simon, Elisena A. G. Seravalli, Roger W. Kreuger, Jeroen Hendrikse, E. Loeff, Ben J. M. Heijmen, C. E. W. V. Eijk","doi":"10.1109/NSSMIC.2005.1596910","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596910","url":null,"abstract":"We report on the characterization of a gas detector, based on gas electron multipliers (GEMs), for use in intensity modulated radiation therapy (IMRT). The light emitted during the gas multiplication process in 1 atm Ar-CF4 (96-4) scintillating gas mixture has been studied as a function of applied voltages and treatment conditions such as beam time and photon energy","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123831805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596923
R. Ramirez, W. Wong, Soonseok Kim, H. Baghaei, Hongdi Li, Yu Wang, Yuxuan Zhang, Shitao Liu, Jiguo Liu
We are developing very-high resolution detector blocks for animal PET applications. We studied different scintillating crystals materials, BGO, GSO, LSO, MLS, LGSO, and LYSO, to determine the most suitable material for a low cost and high-resolution detector. In this study, we measured and evaluated two different light-output data from individual crystal samples (two different sizes of needles): the scintillation light output received by the PMT as used in PET (LOPET) and the intrinsic light output (ILO). The ILO data, were measured with the largest side of crystal needles coupled to the PMT (crystal needles "lying down onto the PMT"), the LOPET data, were measured with the smallest crystal end coupled to the PMT as used in a PET detector (the crystal is "standing up" on the PMT). The pulse-height spectra for both ILO and LOPET were acquired for all the individual crystal samples, for deducing the percentages of light loss from self-absorption (LLSA) in the PET detector configuration, and energy resolution in both positions (ILO-ER and LOPET-ER). With these crystals, four detectors blocks were also developed, and we measured the overall light output and the position-decoding maps to gauge the decoding capability (DC) of the crystals. We also compared the visual color and clarity of individual crystals and detector blocks. For the two different sizes of the crystal samples that we received, we have the following finding: (a) For the 1.3times1.3times10 mm3 crystals "standing up" as used in a PET camera, GSO, MLS and LYSO, lost almost half of the light while LSO lost more than 2/3 thereby ended up with the same light output as GSO. The energy resolution of LSO and GSO are quite similar (16% and 15%); but the light absorption is significant higher in LSO (71%) in comparison to GSO (54%), MLS (52%) and LYSO (48%). (b) For the 2times2times10 mm3, the light loss from self-absorption (LLSA) was less than the 1.3 mm samples. MLS has the lowest self-absorption (26%), while GSO and LSO have the highest light loss. LGSO and LSO have the lowest LOPET for all the lutetium crystals tested. (c) From the position-decoding results from the detector blocks, LYSO, MLS and GSO provided better position-decoding resolution than the LSO. (d) For the visually comparison, LSO were visually much darker than the other lutetium crystals
{"title":"A comparison of BGO, GSO, MLS, LGSO, LYSO and LSO scintillation materials for high-spatial-resolution animal PET detectors","authors":"R. Ramirez, W. Wong, Soonseok Kim, H. Baghaei, Hongdi Li, Yu Wang, Yuxuan Zhang, Shitao Liu, Jiguo Liu","doi":"10.1109/NSSMIC.2005.1596923","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596923","url":null,"abstract":"We are developing very-high resolution detector blocks for animal PET applications. We studied different scintillating crystals materials, BGO, GSO, LSO, MLS, LGSO, and LYSO, to determine the most suitable material for a low cost and high-resolution detector. In this study, we measured and evaluated two different light-output data from individual crystal samples (two different sizes of needles): the scintillation light output received by the PMT as used in PET (LOPET) and the intrinsic light output (ILO). The ILO data, were measured with the largest side of crystal needles coupled to the PMT (crystal needles \"lying down onto the PMT\"), the LOPET data, were measured with the smallest crystal end coupled to the PMT as used in a PET detector (the crystal is \"standing up\" on the PMT). The pulse-height spectra for both ILO and LOPET were acquired for all the individual crystal samples, for deducing the percentages of light loss from self-absorption (LLSA) in the PET detector configuration, and energy resolution in both positions (ILO-ER and LOPET-ER). With these crystals, four detectors blocks were also developed, and we measured the overall light output and the position-decoding maps to gauge the decoding capability (DC) of the crystals. We also compared the visual color and clarity of individual crystals and detector blocks. For the two different sizes of the crystal samples that we received, we have the following finding: (a) For the 1.3times1.3times10 mm3 crystals \"standing up\" as used in a PET camera, GSO, MLS and LYSO, lost almost half of the light while LSO lost more than 2/3 thereby ended up with the same light output as GSO. The energy resolution of LSO and GSO are quite similar (16% and 15%); but the light absorption is significant higher in LSO (71%) in comparison to GSO (54%), MLS (52%) and LYSO (48%). (b) For the 2times2times10 mm3, the light loss from self-absorption (LLSA) was less than the 1.3 mm samples. MLS has the lowest self-absorption (26%), while GSO and LSO have the highest light loss. LGSO and LSO have the lowest LOPET for all the lutetium crystals tested. (c) From the position-decoding results from the detector blocks, LYSO, MLS and GSO provided better position-decoding resolution than the LSO. (d) For the visually comparison, LSO were visually much darker than the other lutetium crystals","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131172642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596711
D. Pal, Y. Tai, M. Janecek, Heyu Wu, A. O'Sullivan
Tai, et al. are developing insert devices for existing clinical PET scanners to improve the image resolution. Adding the insert inside the scanner leads to three types of coincidences: insert-insert, insert-scanner and scanner-scanner. The challenges in image reconstruction include development of a linear reconstruction algorithm for the insert-scanner coincidences, development of a linear reconstruction algorithm that incorporates all measurements, and development of an iterative (expectation-maximization) algorithm to form a maximum likelihood estimate of the image given all of the data. The data from the set of insert-insert coincidences and from the set of scanner-scanner coincidences each can be used in conventional linear reconstruction algorithms based on data from a ring of detectors. However, the geometry of an insert ring and a scanner ring together is analogous to the fan-beam geometry of fourth generation transmission tomography systems; this analogy leads to a new linear reconstruction algorithm for these data. The resulting algorithm was implemented on both simulated and experimental data, yielding promising results with few artifacts. Our development of an iterative algorithm is based on the standard expectation-maximization algorithm. The novelty of the iterative algorithm is in the incorporation of the details of the geometry, which is based in part on our characterization of the insert-scanner geometry.
{"title":"Linear and iterative reconstruction algorithms for a novel PET-insert scanner","authors":"D. Pal, Y. Tai, M. Janecek, Heyu Wu, A. O'Sullivan","doi":"10.1109/NSSMIC.2005.1596711","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596711","url":null,"abstract":"Tai, et al. are developing insert devices for existing clinical PET scanners to improve the image resolution. Adding the insert inside the scanner leads to three types of coincidences: insert-insert, insert-scanner and scanner-scanner. The challenges in image reconstruction include development of a linear reconstruction algorithm for the insert-scanner coincidences, development of a linear reconstruction algorithm that incorporates all measurements, and development of an iterative (expectation-maximization) algorithm to form a maximum likelihood estimate of the image given all of the data. The data from the set of insert-insert coincidences and from the set of scanner-scanner coincidences each can be used in conventional linear reconstruction algorithms based on data from a ring of detectors. However, the geometry of an insert ring and a scanner ring together is analogous to the fan-beam geometry of fourth generation transmission tomography systems; this analogy leads to a new linear reconstruction algorithm for these data. The resulting algorithm was implemented on both simulated and experimental data, yielding promising results with few artifacts. Our development of an iterative algorithm is based on the standard expectation-maximization algorithm. The novelty of the iterative algorithm is in the incorporation of the details of the geometry, which is based in part on our characterization of the insert-scanner geometry.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"23 03","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114114134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596303
W. Lee, D. Wehe
We report on a hybrid radiation imaging system that combines the advantages of a multi-aperture mechanical collimator with electronic collimation. The combination offers both efficiency and good angular resolution, and is unique since a single gamma ray can contribute information to both modalities simultaneously. The mechanically collimated camera is most effective for imaging lower energy photons while electronic collimation uncouples spatial resolution from efficiency for higher energies. Our proposed dual aperture gamma imager (DAGI) combines a high-resolution URA coded aperture with a Compton scatter camera to provide a broader range of energy response suitable for a wider range of industrial applications (50 keV-2 MeV). The primary detector is a large area LaCl/sub 3/:Ce scintillator coupled directly to a Hammamatsu PSPMT, chosen to provide portability, efficiency and energy resolution. A pixellated CsI(Na)/PSPMT combination serves as the secondary absorption detector. Point and ring shaped radiation sources (140, 364, 662 and 1275 keV) are simulated. The results show that DAGI can cover a broad energy range of radiation and the combined dual collimation image, using the maximum likelihood method for image reconstruction, yields better images than either a mechanical or electronic image at intermediate energies. The sensitivity loss of the Compton imager due to the introduction of the mechanical collimator is discussed.
{"title":"Simulation results of a dual aperture gamma ray imager","authors":"W. Lee, D. Wehe","doi":"10.1109/NSSMIC.2005.1596303","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596303","url":null,"abstract":"We report on a hybrid radiation imaging system that combines the advantages of a multi-aperture mechanical collimator with electronic collimation. The combination offers both efficiency and good angular resolution, and is unique since a single gamma ray can contribute information to both modalities simultaneously. The mechanically collimated camera is most effective for imaging lower energy photons while electronic collimation uncouples spatial resolution from efficiency for higher energies. Our proposed dual aperture gamma imager (DAGI) combines a high-resolution URA coded aperture with a Compton scatter camera to provide a broader range of energy response suitable for a wider range of industrial applications (50 keV-2 MeV). The primary detector is a large area LaCl/sub 3/:Ce scintillator coupled directly to a Hammamatsu PSPMT, chosen to provide portability, efficiency and energy resolution. A pixellated CsI(Na)/PSPMT combination serves as the secondary absorption detector. Point and ring shaped radiation sources (140, 364, 662 and 1275 keV) are simulated. The results show that DAGI can cover a broad energy range of radiation and the combined dual collimation image, using the maximum likelihood method for image reconstruction, yields better images than either a mechanical or electronic image at intermediate energies. The sensitivity loss of the Compton imager due to the introduction of the mechanical collimator is discussed.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117322972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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