Pub Date : 1995-10-21DOI: 10.1109/NSSMIC.1995.504237
A.M.L.S. Morgado, J. Simões, C. Correia
This paper presents simple circuits for baseline restoration based on a commercial current conveyor (CCII01). Tests were performed, on two circuits, with periodic trapezoidal shaped pulses in order to measure the baseline restoration for several pulse rates and restorer duty cycles. For the current conveyor based Robinson restorer, the peak shift was less than 10 mV, for duty cycles up to 60% at high pulse rates. Duty cycles up to 80% were also tested, being the maximum peak shift 21 mV. The peak shift for the current conveyor based Grubic restorer was also measured. The maximum value found was 30 mV at 82% duty cycle. Keeping the duty cycle below 60% improves greatly the restorer performance. The ability of both baseline restorer architectures to reject low frequency modulation is also measured, with good results on both circuits.
{"title":"Baseline restoration using current conveyors","authors":"A.M.L.S. Morgado, J. Simões, C. Correia","doi":"10.1109/NSSMIC.1995.504237","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504237","url":null,"abstract":"This paper presents simple circuits for baseline restoration based on a commercial current conveyor (CCII01). Tests were performed, on two circuits, with periodic trapezoidal shaped pulses in order to measure the baseline restoration for several pulse rates and restorer duty cycles. For the current conveyor based Robinson restorer, the peak shift was less than 10 mV, for duty cycles up to 60% at high pulse rates. Duty cycles up to 80% were also tested, being the maximum peak shift 21 mV. The peak shift for the current conveyor based Grubic restorer was also measured. The maximum value found was 30 mV at 82% duty cycle. Keeping the duty cycle below 60% improves greatly the restorer performance. The ability of both baseline restorer architectures to reject low frequency modulation is also measured, with good results on both circuits.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123105966","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.504244
W. Meyer
IEEE Standard 1057 has received final approval. This standard specifies performance parameters and their measurement techniques for digital waveform recorders. These parameters and test methods are also applicable to characterizing analog-to-digital converters, and this document can be used as an interim standard until a separate standard for ADC evaluation is completed. This presentation describes the major points of the standard and presents sample results from its procedures. A User's Guide and software toolkit are in preparation.
{"title":"An IEEE standard for waveform recorders","authors":"W. Meyer","doi":"10.1109/NSSMIC.1995.504244","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504244","url":null,"abstract":"IEEE Standard 1057 has received final approval. This standard specifies performance parameters and their measurement techniques for digital waveform recorders. These parameters and test methods are also applicable to characterizing analog-to-digital converters, and this document can be used as an interim standard until a separate standard for ADC evaluation is completed. This presentation describes the major points of the standard and presents sample results from its procedures. A User's Guide and software toolkit are in preparation.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"18 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114125364","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.510364
F. Lin, R. Breedon, B. Holbrook, W. Ko
A switched capacitor array (SCA) application specific integrated circuit is being developed for the front-end readout of the forward muon chambers for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider. The SCA design requires full analog wave sampling with 10-bit accuracy over a one volt range. The present SCA circuit was designed and simulated to approach these requirements. Several iterations of a prototype have been fabricated in the CMOS HP 1.2 /spl mu/m process. Test results are provided and major concerns related to SCA operation are discussed in detail. Suggested modifications for the next ASIC iteration are discussed.
针对大型强子对撞机紧凑型介子螺线管(CMS)实验中正向介子腔的前端读出，研制了一种开关电容阵列(SCA)专用集成电路。SCA设计要求在一伏特范围内具有10位精度的全模拟波采样。目前的SCA电路是为了满足这些要求而设计和仿真的。在CMOS HP 1.2 /spl mu/m工艺中制造了原型的几次迭代。提供了测试结果，并详细讨论了与SCA操作相关的主要关注点。讨论了下一个ASIC迭代的建议修改。
{"title":"A switched capacitor array as an analog pipeline for the CMS forward muon chamber readout","authors":"F. Lin, R. Breedon, B. Holbrook, W. Ko","doi":"10.1109/NSSMIC.1995.510364","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510364","url":null,"abstract":"A switched capacitor array (SCA) application specific integrated circuit is being developed for the front-end readout of the forward muon chambers for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider. The SCA design requires full analog wave sampling with 10-bit accuracy over a one volt range. The present SCA circuit was designed and simulated to approach these requirements. Several iterations of a prototype have been fabricated in the CMOS HP 1.2 /spl mu/m process. Test results are provided and major concerns related to SCA operation are discussed in detail. Suggested modifications for the next ASIC iteration are discussed.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115263908","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.500269
N. Mohsenian, H. Shahri, N. Nasrabadi
A new coding scheme based on the scalar-vector quantizer (SVQ) is developed for compression of medical images. SVQ is a fixed-rate encoder and its rate-distortion performance is close to that of optimal entropy-constrained scalar quantizers (ECSQ's) for memoryless sources. For a set of magnetic resonance (MR) images, coding results obtained from SVQ and ECSQ at low bit-rates are indistinguishable. Furthermore, the authors' encoded images are perceptually indistinguishable from the original, when displayed on a monitor. This makes the authors' SVQ based coder an attractive compression scheme for picture archiving and communication systems (PACS), currently under consideration for an all digital radiology environment in hospitals, where reliable transmission, storage, and high fidelity reconstruction of images are desired.
{"title":"Scalar-vector quantization of medical images","authors":"N. Mohsenian, H. Shahri, N. Nasrabadi","doi":"10.1109/NSSMIC.1995.500269","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500269","url":null,"abstract":"A new coding scheme based on the scalar-vector quantizer (SVQ) is developed for compression of medical images. SVQ is a fixed-rate encoder and its rate-distortion performance is close to that of optimal entropy-constrained scalar quantizers (ECSQ's) for memoryless sources. For a set of magnetic resonance (MR) images, coding results obtained from SVQ and ECSQ at low bit-rates are indistinguishable. Furthermore, the authors' encoded images are perceptually indistinguishable from the original, when displayed on a monitor. This makes the authors' SVQ based coder an attractive compression scheme for picture archiving and communication systems (PACS), currently under consideration for an all digital radiology environment in hospitals, where reliable transmission, storage, and high fidelity reconstruction of images are desired.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121647270","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.510409
B. Hussain, A. Behera, C. Beck, A. Alsammarae
A program is proposed for Life Cycle Management of major equipment used in the auxiliary distribution systems of nuclear generating plants, with a focus on power quality and power conditioning. Both reactive power compensation and control of power quality have a significant impact on the life cycle of major components used in the system. One key improvement results from reduced component operating temperatures. Systematic load reduction in the distribution system is also a viable approach to extend the life of the major equipment. This paper is limited to the Life Cycle Management of transformers, cables, breakers, motors, and solenoids.
{"title":"Life cycle management of auxiliary systems by power conditioning","authors":"B. Hussain, A. Behera, C. Beck, A. Alsammarae","doi":"10.1109/NSSMIC.1995.510409","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510409","url":null,"abstract":"A program is proposed for Life Cycle Management of major equipment used in the auxiliary distribution systems of nuclear generating plants, with a focus on power quality and power conditioning. Both reactive power compensation and control of power quality have a significant impact on the life cycle of major components used in the system. One key improvement results from reduced component operating temperatures. Systematic load reduction in the distribution system is also a viable approach to extend the life of the major equipment. This paper is limited to the Life Cycle Management of transformers, cables, breakers, motors, and solenoids.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"382 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121668775","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.504271
W. Hong, H. Cho, V. Perez-mendez, J. Kadyk, K. Luk
Thin (/spl sim/1000 A) semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to microstrip gas chambers in order to control gain instabilities due to charges in or on the substrate. The surface resistivity has been successfully controlled in the range of 10/sup 12//spl sim/10/sup 16/ /spl Omega///spl square/ by changing the relative amount of the carbon content and boron doping level. The light sensitivity, which is defined as the ratio of light-to-dark conductivity, was reduced to nearly unity by doping. Gas gains of /spl sim/2000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. Upon prolonged irradiation, the detector overcoated with a-Si:C:H aged more slowly by approximately an order of magnitude than the one without surface coating. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.
{"title":"Microstrip gas chambers fabrication based on amorphous silicon and its carbon alloy","authors":"W. Hong, H. Cho, V. Perez-mendez, J. Kadyk, K. Luk","doi":"10.1109/NSSMIC.1995.504271","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504271","url":null,"abstract":"Thin (/spl sim/1000 A) semiconducting films of hydrogenated amorphous silicon (a-Si:H) and its carbon alloy (a-Si:C:H) were applied to microstrip gas chambers in order to control gain instabilities due to charges in or on the substrate. The surface resistivity has been successfully controlled in the range of 10/sup 12//spl sim/10/sup 16/ /spl Omega///spl square/ by changing the relative amount of the carbon content and boron doping level. The light sensitivity, which is defined as the ratio of light-to-dark conductivity, was reduced to nearly unity by doping. Gas gains of /spl sim/2000 and energy resolution of 20% FWHM were achieved and the gain remained constant over a week of operation. Upon prolonged irradiation, the detector overcoated with a-Si:C:H aged more slowly by approximately an order of magnitude than the one without surface coating. A-Si:C:H film is an attractive alternative to ion-implanted or semiconducting glass due to the wide range of resistivities possible and the feasibility of making deposits over a large area at low cost.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"42 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121826430","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.504290
R. Redus, M. Squillante, J. Gordon, P. Bennett, G. Entine, G. Knoll, D. Wehe, S. Guru
A combined video and gamma ray imaging system has been developed to rapidly determine the location, distribution, and intensity of gamma ray sources. This instrument includes both a conventional video camera and a gamma ray imaging system, which is based upon a position sensitive photomultiplier tube, a scintillator, and a pinhole collimator. The gamma camera records the position and energy of each interaction, determining the energy spectrum and count rate from each direction. The design of the instrument and results of preliminary field tests will be presented. We have used a prototype of such an instrument in preliminary field tests to image radioactive sources with gamma ray energies between 120 keV and 2.4 MeV. This new system achieves an angular resolution for the nuclear image of 60 with an efficiency of 3/spl times/10/sup -6/ at 1 meter, a performance suitable for many nuclear applications. The sensitivity of the system is sufficiently high that, in a low background environment, a 1 mCi /sup 137/Cs source at 5 meters can be located in <30 seconds. Alternatively, higher spatial resolution can be attained at lower efficiency and longer imaging times.
{"title":"An imaging nuclear survey system","authors":"R. Redus, M. Squillante, J. Gordon, P. Bennett, G. Entine, G. Knoll, D. Wehe, S. Guru","doi":"10.1109/NSSMIC.1995.504290","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504290","url":null,"abstract":"A combined video and gamma ray imaging system has been developed to rapidly determine the location, distribution, and intensity of gamma ray sources. This instrument includes both a conventional video camera and a gamma ray imaging system, which is based upon a position sensitive photomultiplier tube, a scintillator, and a pinhole collimator. The gamma camera records the position and energy of each interaction, determining the energy spectrum and count rate from each direction. The design of the instrument and results of preliminary field tests will be presented. We have used a prototype of such an instrument in preliminary field tests to image radioactive sources with gamma ray energies between 120 keV and 2.4 MeV. This new system achieves an angular resolution for the nuclear image of 60 with an efficiency of 3/spl times/10/sup -6/ at 1 meter, a performance suitable for many nuclear applications. The sensitivity of the system is sufficiently high that, in a low background environment, a 1 mCi /sup 137/Cs source at 5 meters can be located in <30 seconds. Alternatively, higher spatial resolution can be attained at lower efficiency and longer imaging times.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121581243","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.500329
G. Royle, N.E. Royle, R. Pani, R. Speller
A realistic Monte Carlo computer model for designing and optimising gamma camera collimators has been used to design high resolution collimators which can accommodate the resolving potential of the small gamma camera. The performance of the collimator is a key factor in determining the overall imaging performance of the system. Three materials have been investigated; lead, tungsten and lead glass. The results demonstrate that tungsten is the preferred material, due to its attenuating properties. Furthermore, its other properties, such as strength, would allow thin, durable collimators to be constructed. Lead has a slight reduction in imaging performance and its malleability could prove problematic in thin septa construction. Lead glass was selected due to the relative ease of constructing very narrow septa. It has been shown to have potential, however the collimator performance is degraded compared with the other materials.
{"title":"Design of high resolution collimators for small gamma cameras","authors":"G. Royle, N.E. Royle, R. Pani, R. Speller","doi":"10.1109/NSSMIC.1995.500329","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500329","url":null,"abstract":"A realistic Monte Carlo computer model for designing and optimising gamma camera collimators has been used to design high resolution collimators which can accommodate the resolving potential of the small gamma camera. The performance of the collimator is a key factor in determining the overall imaging performance of the system. Three materials have been investigated; lead, tungsten and lead glass. The results demonstrate that tungsten is the preferred material, due to its attenuating properties. Furthermore, its other properties, such as strength, would allow thin, durable collimators to be constructed. Lead has a slight reduction in imaging performance and its malleability could prove problematic in thin septa construction. Lead glass was selected due to the relative ease of constructing very narrow septa. It has been shown to have potential, however the collimator performance is degraded compared with the other materials.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125627595","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.510481
V. Di Lecce, E. Di Sciascio, A.R. Manni
This work presents the parallelization of Three-Dimensional PET Backprojection Filtering reconstruction with reference to an implementation on a multiprocessor architecture organized in cluster mode. The authors took as reference a 24 rings, 784 detectors per ring, scanner, and a corresponding volume of interest of 128*128*47. The multiprocessor architecture is based on six commercial digital signal processors connected to an interface processor and global memory on a shared bus and together via their port links. In the Three-Dimensional backprojection stage the volume of interest data are stored within processors local memories, and are accessible from other processors. LORs data are dynamically scheduled onto the processors providing a good load balance and a low communication overhead. The Three-Dimensional filtering has been considered in the frequency domain using Fast Fourier Transform techniques on an enlarged array of samples in order to take into account border artefacts drawbacks. The Backprojection Filtering reconstruction time for a 3-D acquisition on this apparatus takes, according to the authors' simulations, approximately five minutes.
{"title":"Parallelization of 3-D PET BpjF reconstruction on a DSP cluster","authors":"V. Di Lecce, E. Di Sciascio, A.R. Manni","doi":"10.1109/NSSMIC.1995.510481","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510481","url":null,"abstract":"This work presents the parallelization of Three-Dimensional PET Backprojection Filtering reconstruction with reference to an implementation on a multiprocessor architecture organized in cluster mode. The authors took as reference a 24 rings, 784 detectors per ring, scanner, and a corresponding volume of interest of 128*128*47. The multiprocessor architecture is based on six commercial digital signal processors connected to an interface processor and global memory on a shared bus and together via their port links. In the Three-Dimensional backprojection stage the volume of interest data are stored within processors local memories, and are accessible from other processors. LORs data are dynamically scheduled onto the processors providing a good load balance and a low communication overhead. The Three-Dimensional filtering has been considered in the frequency domain using Fast Fourier Transform techniques on an enlarged array of samples in order to take into account border artefacts drawbacks. The Backprojection Filtering reconstruction time for a 3-D acquisition on this apparatus takes, according to the authors' simulations, approximately five minutes.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"25 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113959539","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 : 1995-10-21DOI: 10.1109/NSSMIC.1995.510459
Huili Wang, R. Jaszczak, R. Coleman
Collimator and acquisition parameters including focal lengths, radius-of-rotation, and mechanical shifts are important for image reconstruction but often partly unknown. Determination of the unknown parameters based on the projections of a point source at various projection angles has been studied for fan beam and cone beam collimators. The authors extend these previous approaches of parameter determination to astigmatic collimation. For the astigmatic parameter determination, the authors' study focuses on two fundamental issues: (1) Can parameters be uniquely determined by using radioactive point sources, and (2) what is the condition for accurate determination of the parameters? Algebraic analysis as well as Monte Carlo simulation are employed to address these issues. Results of the analysis and simulation show that if the locations of the point sources used for parameter determination are unknown, the coordinate of the point source position along the axis-of-rotation and the component of the mechanical shift in the same direction cannot be uniquely determined. More importantly, determining a relatively small mechanical shift along the axis-of-rotation is difficult. Accurate a priori knowledge about the axial component of the point source position is important for an accurate estimate of the axial mechanical shift. In addition, the authors' Monte Carlo study shows that the accuracy of parameter determination is improved as the distance between the point source and the origin of the underlying Cartesian coordinate system for image reconstruction is increased.
{"title":"Determination of collimator and acquisition parameters for astigmatic SPECT imaging","authors":"Huili Wang, R. Jaszczak, R. Coleman","doi":"10.1109/NSSMIC.1995.510459","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510459","url":null,"abstract":"Collimator and acquisition parameters including focal lengths, radius-of-rotation, and mechanical shifts are important for image reconstruction but often partly unknown. Determination of the unknown parameters based on the projections of a point source at various projection angles has been studied for fan beam and cone beam collimators. The authors extend these previous approaches of parameter determination to astigmatic collimation. For the astigmatic parameter determination, the authors' study focuses on two fundamental issues: (1) Can parameters be uniquely determined by using radioactive point sources, and (2) what is the condition for accurate determination of the parameters? Algebraic analysis as well as Monte Carlo simulation are employed to address these issues. Results of the analysis and simulation show that if the locations of the point sources used for parameter determination are unknown, the coordinate of the point source position along the axis-of-rotation and the component of the mechanical shift in the same direction cannot be uniquely determined. More importantly, determining a relatively small mechanical shift along the axis-of-rotation is difficult. Accurate a priori knowledge about the axial component of the point source position is important for an accurate estimate of the axial mechanical shift. In addition, the authors' Monte Carlo study shows that the accuracy of parameter determination is improved as the distance between the point source and the origin of the underlying Cartesian coordinate system for image reconstruction is increased.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"228 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122648155","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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