Pub Date : 2000-10-15DOI: 10.1109/NSSMIC.2000.950089
J. Maltz
The clinical application of dynamic ECT reconstruction algorithms for inconsistent projection (IP) data has been beset with difficulties. These include poor scalability, numerical instability of algorithms, problems of non-uniqueness of solutions, the need to oversimplify tracer kinetics, and impractical computational burden. The authors present a stable, low computational cost reconstruction algorithm which is able to recover the tracer kinetics of several hundred image regions at realistic noise levels. Through optimal selection of a small set of non-negative basis functions to describe regional time-activity curves (TACs), the authors are able to solve for the first-order compartmental model kinetics of each region. A non-uniform resolution pixelization of image space is employed to obtain highest resolution in regions of interest. These spatial and temporal simplifications improve numerical conditioning, provide robustness against noise, and greatly decrease the computational burden of dynamic reconstruction. The authors apply this algorithm to IP phantom data whose source distribution, kinetics and count statistics are modeled after a clinical myocardial SPECT dataset. TACs of phantom regions are recovered to within a mean square error of 10%, an accuracy which proves sufficient to allow detection of a myocardial perfusion defect within healthy myocardial tissue.
{"title":"Optimal time-activity basis selection for exponential spectral analysis: application to the solution of large dynamic emission tomographic reconstruction problems","authors":"J. Maltz","doi":"10.1109/NSSMIC.2000.950089","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.950089","url":null,"abstract":"The clinical application of dynamic ECT reconstruction algorithms for inconsistent projection (IP) data has been beset with difficulties. These include poor scalability, numerical instability of algorithms, problems of non-uniqueness of solutions, the need to oversimplify tracer kinetics, and impractical computational burden. The authors present a stable, low computational cost reconstruction algorithm which is able to recover the tracer kinetics of several hundred image regions at realistic noise levels. Through optimal selection of a small set of non-negative basis functions to describe regional time-activity curves (TACs), the authors are able to solve for the first-order compartmental model kinetics of each region. A non-uniform resolution pixelization of image space is employed to obtain highest resolution in regions of interest. These spatial and temporal simplifications improve numerical conditioning, provide robustness against noise, and greatly decrease the computational burden of dynamic reconstruction. The authors apply this algorithm to IP phantom data whose source distribution, kinetics and count statistics are modeled after a clinical myocardial SPECT dataset. TACs of phantom regions are recovered to within a mean square error of 10%, an accuracy which proves sufficient to allow detection of a myocardial perfusion defect within healthy myocardial tissue.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114932661","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949310
Y. Dewaraja, Michael Ljungberg, Amitava Majumdar, Abhijit Bose, K. Koral
This paper reports the implementation of the SIMIND Monte Carlo code on a IBM SP2 distributed memory parallel computer. Basic aspects of running Monte Carlo particle transport calculations on parallel architectures are described. The authors' parallelization is based on equally partitioning photons among the processors and uses the Message Passing Interface (MPI) library for interprocessor communication and the Scalable Parallel Random Number Generator (SPRNG) to generate uncorrelated random number streams. These parallelization techniques are also applicable to other distributed memory architectures. A linear increase in computing speed with the number of processors is demonstrated for up to 32 processors. This speed-up is especially significant in Single Photon Emission Computed Tomography (SPECT) simulations involving higher energy photon emitters, where explicit modeling of the phantom and collimator is required. For /sup 131/I, the accuracy of the parallel code is demonstrated by comparing simulated and experimental SPECT images from a heart/thorax phantom. Clinically realistic SPECT simulations using the voxel-man phantom are carried out to assess scatter and attenuation correction.
{"title":"A parallel Monte Carlo code for planar and SPECT imaging: implementation, verification and applications in /sup 131/I SPECT","authors":"Y. Dewaraja, Michael Ljungberg, Amitava Majumdar, Abhijit Bose, K. Koral","doi":"10.1109/NSSMIC.2000.949310","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949310","url":null,"abstract":"This paper reports the implementation of the SIMIND Monte Carlo code on a IBM SP2 distributed memory parallel computer. Basic aspects of running Monte Carlo particle transport calculations on parallel architectures are described. The authors' parallelization is based on equally partitioning photons among the processors and uses the Message Passing Interface (MPI) library for interprocessor communication and the Scalable Parallel Random Number Generator (SPRNG) to generate uncorrelated random number streams. These parallelization techniques are also applicable to other distributed memory architectures. A linear increase in computing speed with the number of processors is demonstrated for up to 32 processors. This speed-up is especially significant in Single Photon Emission Computed Tomography (SPECT) simulations involving higher energy photon emitters, where explicit modeling of the phantom and collimator is required. For /sup 131/I, the accuracy of the parallel code is demonstrated by comparing simulated and experimental SPECT images from a heart/thorax phantom. Clinically realistic SPECT simulations using the voxel-man phantom are carried out to assess scatter and attenuation correction.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116941048","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949282
D. Broemmelsiek, R. Eckmann, M. Ispirian, J. McGill, S. Karabekyan, J. Rosen, R. Schwitters
The HERA-B RICH detector utilizes the Hamamatsu R5900 multianode photomultiplier. In order to increase the light collection efficiency, a novel scheme to optically magnify the photocathode is implemented. The design and development of these optics are presented here.
{"title":"Lens-based light-collectors for the HERA-B RICH","authors":"D. Broemmelsiek, R. Eckmann, M. Ispirian, J. McGill, S. Karabekyan, J. Rosen, R. Schwitters","doi":"10.1109/NSSMIC.2000.949282","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949282","url":null,"abstract":"The HERA-B RICH detector utilizes the Hamamatsu R5900 multianode photomultiplier. In order to increase the light collection efficiency, a novel scheme to optically magnify the photocathode is implemented. The design and development of these optics are presented here.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116472267","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949351
C. Kao, Chin-Tu Chen
In a recent study, the authors proposed a new PET design concept that integrates hardware design and data processing for improvement of PET technology. In particular, they the use of new-generation depth-of-interaction in hardware for generation of redundant, yet imperfect, information, together with sinogram restoration (SR) techniques in software that makes efficient use of the redundant information available for correction of data imperfection. The authors demonstrated that this design approach can be used to build PET systems of compact geometry that has the potential of offering high sensitivity, high resolution, and low cost. In this work, the authors continue their development by introducing a direct SR method specifically targeted for design of dedicated small-animal systems. Compared to iterative algorithms considered in the authors' previous study, this direct approach requires essentially no computation time, can be implemented in hardware/firmware, and may be suitable for on-the-fly processing of PET data. Performance of the direct method was evaluated by computer simulation studies. The authors' results indicate that, when scatter and randoms are excluded from simulated data, the proposed method can effectively correct for the parallax errors that exist in the raw data of a compact PET systems, thereby producing images of quality comparable to those generated by a conventional larger-ring system that employs conventional data processing. This observation, however, may be affected by the presence of scatter and randoms, an important issue to be addressed in the authors' future work.
{"title":"A direct sinogram-restoration method for fast image reconstruction in compact DOI-PET systems","authors":"C. Kao, Chin-Tu Chen","doi":"10.1109/NSSMIC.2000.949351","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949351","url":null,"abstract":"In a recent study, the authors proposed a new PET design concept that integrates hardware design and data processing for improvement of PET technology. In particular, they the use of new-generation depth-of-interaction in hardware for generation of redundant, yet imperfect, information, together with sinogram restoration (SR) techniques in software that makes efficient use of the redundant information available for correction of data imperfection. The authors demonstrated that this design approach can be used to build PET systems of compact geometry that has the potential of offering high sensitivity, high resolution, and low cost. In this work, the authors continue their development by introducing a direct SR method specifically targeted for design of dedicated small-animal systems. Compared to iterative algorithms considered in the authors' previous study, this direct approach requires essentially no computation time, can be implemented in hardware/firmware, and may be suitable for on-the-fly processing of PET data. Performance of the direct method was evaluated by computer simulation studies. The authors' results indicate that, when scatter and randoms are excluded from simulated data, the proposed method can effectively correct for the parallax errors that exist in the raw data of a compact PET systems, thereby producing images of quality comparable to those generated by a conventional larger-ring system that employs conventional data processing. This observation, however, may be affected by the presence of scatter and randoms, an important issue to be addressed in the authors' future work.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123676560","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949349
J. Seidel, J. Vaquero, I. Lee, M.V. Green
The authors are constructing a depth-of-interaction (DOI) capable small animal PET scanner that will consist of 18 LGSO/GSO DOI modules arranged around a 11.8 cm diameter ring. These 18 modules will be grouped together electronically by 3's forming 6 sectors. Two of these sectors; have been fabricated, placed opposite one another on the ring and operated in time coincidence with the data acquisition system to be used in the final device. Since a 2-sector partial ring provides the first opportunity to obtain experimental measurements of absolute central (/sup 18/F) point source sensitivity (ACPS), an important design parameter for this system, the authors sought to measure this quantity as a function of energy window at the earliest stage of construction. Measured ACPS values extrapolated to the full, 6-sector ring decreased as window width decreased: from 1034 cps/Ci or 2.8% (no energy window) to 594 cps/Ci or 1.6% (250-650 keV energy window) to 375 cps/Ci or 1.0% (400-650 keV energy window). These early results suggest that the final system will possess an ACPS substantially higher than several recently described small animal PET scanners.
{"title":"Experimental estimates of the absolute sensitivity of a small animal PET scanner with depth-of-interaction capability","authors":"J. Seidel, J. Vaquero, I. Lee, M.V. Green","doi":"10.1109/NSSMIC.2000.949349","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949349","url":null,"abstract":"The authors are constructing a depth-of-interaction (DOI) capable small animal PET scanner that will consist of 18 LGSO/GSO DOI modules arranged around a 11.8 cm diameter ring. These 18 modules will be grouped together electronically by 3's forming 6 sectors. Two of these sectors; have been fabricated, placed opposite one another on the ring and operated in time coincidence with the data acquisition system to be used in the final device. Since a 2-sector partial ring provides the first opportunity to obtain experimental measurements of absolute central (/sup 18/F) point source sensitivity (ACPS), an important design parameter for this system, the authors sought to measure this quantity as a function of energy window at the earliest stage of construction. Measured ACPS values extrapolated to the full, 6-sector ring decreased as window width decreased: from 1034 cps/Ci or 2.8% (no energy window) to 594 cps/Ci or 1.6% (250-650 keV energy window) to 375 cps/Ci or 1.0% (400-650 keV energy window). These early results suggest that the final system will possess an ACPS substantially higher than several recently described small animal PET scanners.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121898630","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949143
R. Glukhov, C. Pédrini, A. Vasil'ev
Ratio of fast-to-slow components in BaF/sub 2/ emission is studied theoretically as a function of particle type and energy. The investigation is based on the model of crossluminescence quenching due to interaction between excitations in the track region. It is shown that even weak interaction between excitations can quench crossluminescence. We simulate the evolution of spatial distribution of electronic excitations (electrons, valence and core holes, excitons) in the track region for various energy deposits per unit track length. The system of kinetic, equations includes transformation, recombination and space diffusion of electronic excitations with account for electric fields originated due to charge separation in the track region. The results of this simulation allow us to explain the decrease of fast-to-slow emission ratio with energy and type of incident particle (in raw electrons-pions-protons-alpha-particles).
{"title":"Track effects in BaF/sub 2/ scintillations","authors":"R. Glukhov, C. Pédrini, A. Vasil'ev","doi":"10.1109/NSSMIC.2000.949143","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949143","url":null,"abstract":"Ratio of fast-to-slow components in BaF/sub 2/ emission is studied theoretically as a function of particle type and energy. The investigation is based on the model of crossluminescence quenching due to interaction between excitations in the track region. It is shown that even weak interaction between excitations can quench crossluminescence. We simulate the evolution of spatial distribution of electronic excitations (electrons, valence and core holes, excitons) in the track region for various energy deposits per unit track length. The system of kinetic, equations includes transformation, recombination and space diffusion of electronic excitations with account for electric fields originated due to charge separation in the track region. The results of this simulation allow us to explain the decrease of fast-to-slow emission ratio with energy and type of incident particle (in raw electrons-pions-protons-alpha-particles).","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122001376","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949867
A. Pullia, E. Gatti
The principle of operation of ROTOR, a novel processor of nuclear signals, has been recently demonstrated. Nevertheless the prototype versions realised so far are affected by limiting factors which do not permit to fully exploit the potentiality of the ROTOR principle. For example presently the shape of the filter weight function is forced to be trapezoidal, which is not optimal for low-rate operation and/or when the 1/f noise of the preamplifier is not negligible. Furthermore a very precise timing must be supplied for proper operation. In this paper we suggest that these limitations can be overcome by (i) shrinking the analog pulses provided by the preamplifier, (ii) supplying them to the reference input of a DAC used as a multiplier, whose digital-input tracks the wanted weight function shape, (iii) integrating the signal at the DAC output. In this way on the one hand the weight function may be shaped so as to match the optimal profile, on the other hand precision is no more required in the gating intervals where the flat top and the shoulders of the weight function lay. Eventually the proposed solution is shown to be less sensitive to the parameter-matching accurateness of the used technology.
{"title":"How to optimize VLSI ROTOR processors","authors":"A. Pullia, E. Gatti","doi":"10.1109/NSSMIC.2000.949867","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949867","url":null,"abstract":"The principle of operation of ROTOR, a novel processor of nuclear signals, has been recently demonstrated. Nevertheless the prototype versions realised so far are affected by limiting factors which do not permit to fully exploit the potentiality of the ROTOR principle. For example presently the shape of the filter weight function is forced to be trapezoidal, which is not optimal for low-rate operation and/or when the 1/f noise of the preamplifier is not negligible. Furthermore a very precise timing must be supplied for proper operation. In this paper we suggest that these limitations can be overcome by (i) shrinking the analog pulses provided by the preamplifier, (ii) supplying them to the reference input of a DAC used as a multiplier, whose digital-input tracks the wanted weight function shape, (iii) integrating the signal at the DAC output. In this way on the one hand the weight function may be shaped so as to match the optimal profile, on the other hand precision is no more required in the gating intervals where the flat top and the shoulders of the weight function lay. Eventually the proposed solution is shown to be less sensitive to the parameter-matching accurateness of the used technology.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117199928","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949096
A. Perrot
LHC luminosity will reach 10/sup 34/ cm/sup -2/ s/sup -1/ but special runs at 10/sup 28/ cm/sup -2/ s/sup -1/ are foreseen. Thus a luminosity monitor must have a dynamic range of six orders of magnitude. A good tolerance to radiation is also required. A detector using both ionisation and secondary emission techniques has been studied in this context. Its design is based on monitors used previously at the CERN PS and SPS. Special attention was devoted to minimise leakage currents. Linearity in both Secondary Emission Counter (SEC) and Ionisation Chamber (IC) modes has been tested from /spl sim/10/sup 4/ incident particles to /spl sim/10/sup 8/ incident particles. SEC is linear above /spl sim/5.10/sup 6/ incident particles while IC is linear over the full studied range. However, because of the radiation environment at LHC, the SEC mode is much preferred at high intensity. A solution actually foreseen is to switch from IC to SEC mode when the intensity is around 5.10/sup 6/ incident particles per second corresponding to an LHC luminosity of 6.10/sup 30/ cm/sup -2/ s/sup -1/.
{"title":"A luminosity monitor for LHC","authors":"A. Perrot","doi":"10.1109/NSSMIC.2000.949096","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949096","url":null,"abstract":"LHC luminosity will reach 10/sup 34/ cm/sup -2/ s/sup -1/ but special runs at 10/sup 28/ cm/sup -2/ s/sup -1/ are foreseen. Thus a luminosity monitor must have a dynamic range of six orders of magnitude. A good tolerance to radiation is also required. A detector using both ionisation and secondary emission techniques has been studied in this context. Its design is based on monitors used previously at the CERN PS and SPS. Special attention was devoted to minimise leakage currents. Linearity in both Secondary Emission Counter (SEC) and Ionisation Chamber (IC) modes has been tested from /spl sim/10/sup 4/ incident particles to /spl sim/10/sup 8/ incident particles. SEC is linear above /spl sim/5.10/sup 6/ incident particles while IC is linear over the full studied range. However, because of the radiation environment at LHC, the SEC mode is much preferred at high intensity. A solution actually foreseen is to switch from IC to SEC mode when the intensity is around 5.10/sup 6/ incident particles per second corresponding to an LHC luminosity of 6.10/sup 30/ cm/sup -2/ s/sup -1/.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117231742","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949989
G. El Fakhri, S. Moore, P. Maksud
A new scatter correction method for Ga-67 based on artificial neural networks (ANN) with error backpropagation was designed and evaluated. The ANN consisted of a 37-node input layer (37 energy channels in the range 60-370 keV), an 18-node hidden layer, and a 3-node output layer to estimate the scatter-free distribution in the 93, 185 and 300 keV photopeaks. Two separate activity and attenuation distribution sets, based on a segmented realistic anthropomorphic torso phantom, were simulated. The first set was used for ANN learning and the second to evaluate the scatter correction. Our Monte Carlo simulation modeled all photon interactions in the patient, collimator and detector. Interactions simulated in the collimator included Compton and coherent scatter, and photoelectric absorption with forced production of lead K-shell X-rays. Ninety very-high-count projections were simulated and used as a basis for generating 15 Poisson noise realizations for each angle; noise levels were characteristic of 72-hour post-injection Ga-67 studies. The energy window images (WIN) used clinically were also generated for comparison. Bias and variance were computed with respect to the primary distributions over reconstructed volumes of interests in the lungs, abdomen and liver. ANN overall bias and precision in the abdomen were 5.8/spl infin/2.6% (93 keV), -0.1/spl plusmn/2.4% (185 keV) and -4.9/spl plusmn/1.8% (300 keV), and the bias in all structures was less than 19% as compared to 85% with WIN. ANN is an accurate and robust scatter correction method for Ga-67 studies.
{"title":"A new scatter compensation method for Ga-67 imaging using artificial neural networks","authors":"G. El Fakhri, S. Moore, P. Maksud","doi":"10.1109/NSSMIC.2000.949989","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949989","url":null,"abstract":"A new scatter correction method for Ga-67 based on artificial neural networks (ANN) with error backpropagation was designed and evaluated. The ANN consisted of a 37-node input layer (37 energy channels in the range 60-370 keV), an 18-node hidden layer, and a 3-node output layer to estimate the scatter-free distribution in the 93, 185 and 300 keV photopeaks. Two separate activity and attenuation distribution sets, based on a segmented realistic anthropomorphic torso phantom, were simulated. The first set was used for ANN learning and the second to evaluate the scatter correction. Our Monte Carlo simulation modeled all photon interactions in the patient, collimator and detector. Interactions simulated in the collimator included Compton and coherent scatter, and photoelectric absorption with forced production of lead K-shell X-rays. Ninety very-high-count projections were simulated and used as a basis for generating 15 Poisson noise realizations for each angle; noise levels were characteristic of 72-hour post-injection Ga-67 studies. The energy window images (WIN) used clinically were also generated for comparison. Bias and variance were computed with respect to the primary distributions over reconstructed volumes of interests in the lungs, abdomen and liver. ANN overall bias and precision in the abdomen were 5.8/spl infin/2.6% (93 keV), -0.1/spl plusmn/2.4% (185 keV) and -4.9/spl plusmn/1.8% (300 keV), and the bias in all structures was less than 19% as compared to 85% with WIN. ANN is an accurate and robust scatter correction method for Ga-67 studies.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124031206","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 : 2000-10-15DOI: 10.1109/NSSMIC.2000.949319
P. Antich, R. Parkey, N. Slavin, E. Tsyganov, A. Zinchenko
This study presents results of Monte Carlo simulations of a compact Compton camera design using the GEANT-based computer code. The proposed system is a sensitive SPECT device made of semiconductor detectors capable of providing angular resolutions of about 1 mrad. To accurately model the camera, the GEANT code was modified to take into account pre-collision motion of elections, the so-called Doppler effect. A new algorithm for three-dimensional image reconstruction based on clustering of individual events has been developed and proven on clustering of individual events has been developed and proven with Monte Carlo phantoms for a Compton camera and with phantoms and small animal studies for a PET machine.
{"title":"Compact Compton camera design: parameters and imaging algorithms","authors":"P. Antich, R. Parkey, N. Slavin, E. Tsyganov, A. Zinchenko","doi":"10.1109/NSSMIC.2000.949319","DOIUrl":"https://doi.org/10.1109/NSSMIC.2000.949319","url":null,"abstract":"This study presents results of Monte Carlo simulations of a compact Compton camera design using the GEANT-based computer code. The proposed system is a sensitive SPECT device made of semiconductor detectors capable of providing angular resolutions of about 1 mrad. To accurately model the camera, the GEANT code was modified to take into account pre-collision motion of elections, the so-called Doppler effect. A new algorithm for three-dimensional image reconstruction based on clustering of individual events has been developed and proven on clustering of individual events has been developed and proven with Monte Carlo phantoms for a Compton camera and with phantoms and small animal studies for a PET machine.","PeriodicalId":445100,"journal":{"name":"2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125862958","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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