Pub Date : 1995-10-21DOI: 10.1109/NSSMIC.1995.504279
M. Hazumi, T. Kawasaki, K. Senyo, Y. Nagashima, K. Yamamoto, K. Yamamura, T. Tsuboyama, J. Haba, H. Ikeda, H. Iwasaki, T. Matsuda, H. Ozaki, M. Tanaka, Y. Yamada, S. Okuno, S. Avrillon, Y. Asano, S. Mori, C. Fukunaga, T. Hirose, H. Miyata, K. Miyano, E. Banas, A. Bozek, Z. Natkaniec, H. Palka, M. Różańska, K. Rybicki
For the development of the silicon micro strip detector with the pitch of the readout strips as large as 250 /spl mu/m on ohmic side, we made samples with different structures. Charge collection was evaluated to optimize the width of implant strips, aluminum read-out strips, and/or the read-out scheme among strips.
{"title":"Evaluation of silicon micro strip detectors with large read-out pitch","authors":"M. Hazumi, T. Kawasaki, K. Senyo, Y. Nagashima, K. Yamamoto, K. Yamamura, T. Tsuboyama, J. Haba, H. Ikeda, H. Iwasaki, T. Matsuda, H. Ozaki, M. Tanaka, Y. Yamada, S. Okuno, S. Avrillon, Y. Asano, S. Mori, C. Fukunaga, T. Hirose, H. Miyata, K. Miyano, E. Banas, A. Bozek, Z. Natkaniec, H. Palka, M. Różańska, K. Rybicki","doi":"10.1109/NSSMIC.1995.504279","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504279","url":null,"abstract":"For the development of the silicon micro strip detector with the pitch of the readout strips as large as 250 /spl mu/m on ohmic side, we made samples with different structures. Charge collection was evaluated to optimize the width of implant strips, aluminum read-out strips, and/or the read-out scheme among strips.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"52 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":"115680383","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.1995.510485
G. Chinn, S. Huang
The realizable advantages from statistical reconstruction of positron emission tomography (PET) images remains an unsettled issue. Different iterative reconstruction schemes and convergence effects can lead to different levels of regularization in images. To assess the performance, an analytic approach was used to examine the noise levels of weighted least squares (WLS) and least squares (LS) image reconstruction under the same regularization. For certain non-trivial conditions on the error covariance (weighting) matrix, it was shown that WLS is equivalent to LS reconstruction in a mean square error sense, even when the sinogram noise is not uniform. Also, an approach was proposed for matching the regularization between WLS and LS iterative reconstruction. Computer simulations showed that WLS leads to only a marginally small reduction in noise compared to LS reconstruction at the same resolution.
{"title":"A comparison of WLS and LS reconstruction for PET","authors":"G. Chinn, S. Huang","doi":"10.1109/NSSMIC.1995.510485","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510485","url":null,"abstract":"The realizable advantages from statistical reconstruction of positron emission tomography (PET) images remains an unsettled issue. Different iterative reconstruction schemes and convergence effects can lead to different levels of regularization in images. To assess the performance, an analytic approach was used to examine the noise levels of weighted least squares (WLS) and least squares (LS) image reconstruction under the same regularization. For certain non-trivial conditions on the error covariance (weighting) matrix, it was shown that WLS is equivalent to LS reconstruction in a mean square error sense, even when the sinogram noise is not uniform. Also, an approach was proposed for matching the regularization between WLS and LS iterative reconstruction. Computer simulations showed that WLS leads to only a marginally small reduction in noise compared to LS reconstruction at the same resolution.","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":"115904078","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.1995.504325
M. Keller, A. Stellberger, K. Meier, K. Schmitt, A. Holscher
In this paper results from a prototype calorimeter built in connection with the development of a new calorimeter for the H1 detector at the HERA collider are reported. The prototype was constructed as a lead-fibre calorimeter where the fibers were read out with an array of discrete photodiodes connected to conventional preamplifiers built with discrete electronics. Furthermore the first steps towards the design of the final detector setup are described. In particular the development of the integrated readout electronics for the calorimeter is considered.
{"title":"Parallel readout of a photodiode array in a scintillating fibre calorimeter","authors":"M. Keller, A. Stellberger, K. Meier, K. Schmitt, A. Holscher","doi":"10.1109/NSSMIC.1995.504325","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504325","url":null,"abstract":"In this paper results from a prototype calorimeter built in connection with the development of a new calorimeter for the H1 detector at the HERA collider are reported. The prototype was constructed as a lead-fibre calorimeter where the fibers were read out with an array of discrete photodiodes connected to conventional preamplifiers built with discrete electronics. Furthermore the first steps towards the design of the final detector setup are described. In particular the development of the integrated readout electronics for the calorimeter is considered.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"5 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":"124222274","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.1995.510401
J. McKisson, D. Henderson, K.E. Neelands, P. Haskins
Continued research and development efforts are being pursued to improve accuracy, minimize costly overestimates, and increase analysis throughput for non-destructive analysis (NDA) of radioactive waste containers. An imaging detector capable of locating and identifying source distributions in a waste container can improve the estimates obtained from an NDA system. This paper presents the approach taken to data handling and analysis for a simulation-based system design study. Simulations were first performed to sample a large, multiparameter design space and were then refined to focus on candidate geometries that proved to have acceptable performance. To handle the anticipated volume of data and to allow efficient search and analysis, a system was devised to organize the simulation and analysis effort, track data files, and construct a data base. Data were evaluated to determine functional relationships between design parameters and performance. A set of performance metrics were developed and applied to compare the results of the simulations.
{"title":"Design study simulations of a Compton camera for radioactive waste container imaging","authors":"J. McKisson, D. Henderson, K.E. Neelands, P. Haskins","doi":"10.1109/NSSMIC.1995.510401","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510401","url":null,"abstract":"Continued research and development efforts are being pursued to improve accuracy, minimize costly overestimates, and increase analysis throughput for non-destructive analysis (NDA) of radioactive waste containers. An imaging detector capable of locating and identifying source distributions in a waste container can improve the estimates obtained from an NDA system. This paper presents the approach taken to data handling and analysis for a simulation-based system design study. Simulations were first performed to sample a large, multiparameter design space and were then refined to focus on candidate geometries that proved to have acceptable performance. To handle the anticipated volume of data and to allow efficient search and analysis, a system was devised to organize the simulation and analysis effort, track data files, and construct a data base. Data were evaluated to determine functional relationships between design parameters and performance. A set of performance metrics were developed and applied to compare the results of the simulations.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"11 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":"114442225","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.1995.510495
J. Anderson, B. Mair, Murali Rao, C.-H. Wu
In this paper, the authors present a reconstruction algorithm for positron emission tomography that minimizes a weighted least-squares (WLS) objective function. The weights are based on the covariance matrix of the model error and depend on the unknown parameters. The algorithm guarantees nonnegative estimates, and in simulation studies it converged faster and had significantly better resolution and contrast than the ML-EM algorithm. Although simulations suggest that the proposed algorithm is globally convergent, a proof of convergence has not been found yet. Nevertheless, the authors are able to show that it produces estimates that decrease the objective function monotonically with increasing iterations.
{"title":"A weighted least-squares method for PET","authors":"J. Anderson, B. Mair, Murali Rao, C.-H. Wu","doi":"10.1109/NSSMIC.1995.510495","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510495","url":null,"abstract":"In this paper, the authors present a reconstruction algorithm for positron emission tomography that minimizes a weighted least-squares (WLS) objective function. The weights are based on the covariance matrix of the model error and depend on the unknown parameters. The algorithm guarantees nonnegative estimates, and in simulation studies it converged faster and had significantly better resolution and contrast than the ML-EM algorithm. Although simulations suggest that the proposed algorithm is globally convergent, a proof of convergence has not been found yet. Nevertheless, the authors are able to show that it produces estimates that decrease the objective function monotonically with increasing iterations.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"112 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":"114484487","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.1995.510490
K. Erlandsson, S. Strand
A 3D reconstruction method originally developed by the authors for 3D scanners has now been implemented for handling data from a 2D scanner. The scanner consists of 4 detector rings and gives 7 simultaneous planes including cross-planes. The axial sampling is improved by moving the patient couch. This will halve the plane separation, but there will be cross-talk between the planes. The axial sensitivity profile for each plane is, for the direct planes, fairly independent of radial position, but varies significantly for the cross-planes. The authors' 3D reconstruction technique is based on 2D reconstruction of transaxial planes and deconvolution of a position dependent axial spread function. The authors have tested two different methods for the deconvolution step; the iterative Landweber method and singular value decomposition. Evaluations were made with Monte Carlo simulations and phantom studies. The result of 3D reconstruction an improved axial resolution at the cost of a higher noise level. Iterative deconvolution gives the best compromise between resolution and noise.
{"title":"Improved axial resolution in 2D PET with 3D reconstruction","authors":"K. Erlandsson, S. Strand","doi":"10.1109/NSSMIC.1995.510490","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510490","url":null,"abstract":"A 3D reconstruction method originally developed by the authors for 3D scanners has now been implemented for handling data from a 2D scanner. The scanner consists of 4 detector rings and gives 7 simultaneous planes including cross-planes. The axial sampling is improved by moving the patient couch. This will halve the plane separation, but there will be cross-talk between the planes. The axial sensitivity profile for each plane is, for the direct planes, fairly independent of radial position, but varies significantly for the cross-planes. The authors' 3D reconstruction technique is based on 2D reconstruction of transaxial planes and deconvolution of a position dependent axial spread function. The authors have tested two different methods for the deconvolution step; the iterative Landweber method and singular value decomposition. Evaluations were made with Monte Carlo simulations and phantom studies. The result of 3D reconstruction an improved axial resolution at the cost of a higher noise level. Iterative deconvolution gives the best compromise between resolution and noise.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"133 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":"114652803","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.1995.501935
P. Durrant, A. Truman, C. Datema, D. Ramsden
The application of newly emerging multi-pixel Hybrid Photodiode tubes as the basis for a compact clinical gamma camera is proposed. The characteristics of this camera system are discussed and an optimised design presented. Compared to existing clinical gamma cameras, this system is expected to offer an improved spatial resolution without a significant deterioration in the detection efficiency and energy resolution. A comparison is made of multi-pixel Hybrid Photodiodes and Position Sensitive Photomultiplier Tubes.
{"title":"A Gamma Camera Probe with Hybrid Photodiode Readout","authors":"P. Durrant, A. Truman, C. Datema, D. Ramsden","doi":"10.1109/NSSMIC.1995.501935","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.501935","url":null,"abstract":"The application of newly emerging multi-pixel Hybrid Photodiode tubes as the basis for a compact clinical gamma camera is proposed. The characteristics of this camera system are discussed and an optimised design presented. Compared to existing clinical gamma cameras, this system is expected to offer an improved spatial resolution without a significant deterioration in the detection efficiency and energy resolution. A comparison is made of multi-pixel Hybrid Photodiodes and Position Sensitive Photomultiplier Tubes.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"545 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":"116376319","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.1995.500309
T. Ono, K. Ogawa
Describes a new segmentation method using an artificial neural network for brain magnetic resonance (MR) images. In the proposed method, the authors spread an MR image circularly to recognize several regions in the brain. In the spread image, the cerebral regions including white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) align in layers from bottom to top. The above regions are segment by the following procedures: First, the contour of the whole cerebral region including CSF is detected from the spread image by using a Gaussian filter and a differential operator. The region outside the contour is then eliminated. Cerebral regions WM, GM, and CSF are eliminated by an artificial neural network which has three layers. The inputs of the neural network are a pixel value and its normalized vertical and horizontal locations in the spread image. The proposed method was examined using the T2-weighted images, and it was able to segment WM, GM, and CSF regions accurately.
{"title":"Image segmentation using circularly spread MR images","authors":"T. Ono, K. Ogawa","doi":"10.1109/NSSMIC.1995.500309","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500309","url":null,"abstract":"Describes a new segmentation method using an artificial neural network for brain magnetic resonance (MR) images. In the proposed method, the authors spread an MR image circularly to recognize several regions in the brain. In the spread image, the cerebral regions including white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) align in layers from bottom to top. The above regions are segment by the following procedures: First, the contour of the whole cerebral region including CSF is detected from the spread image by using a Gaussian filter and a differential operator. The region outside the contour is then eliminated. Cerebral regions WM, GM, and CSF are eliminated by an artificial neural network which has three layers. The inputs of the neural network are a pixel value and its normalized vertical and horizontal locations in the spread image. The proposed method was examined using the T2-weighted images, and it was able to segment WM, GM, and CSF regions accurately.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"109 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":"122095614","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.1995.510498
Kewei Chen, E. Reiman, M. Lawson, L. Yun, D. Bandy, Anita Palant
While positron emission tomographic (PET) measurements of regional cerebral blood flow (CBF) can be used to map regions of the brain that are involved in normal and pathological human behaviors, measurements in the anteromedial temporal lobe can be confounded by the combined effects of radiotracer activity in neighboring arteries and partial volume averaging. The authors now describe two alternative methods for addressing this potential confound. One method utilizes the early frames of a dynamic PET study, while the other method utilizes a coregistered magnetic resonance image (MRI) to characterize the vascular region-of-interest (ROI). Both methods subsequently assign a common value to each pixel in the vascular ROI. To simulate the vascular artifact, four dynamically acquired PET, O-15 water scans in the same subject during the same behavioral state were used to compute 4 vascular images (0-60 s after radiotracer administration) which included vascular activity and 4 control images (20-80 s after radiotracer administration) which did not. t-score maps were used to characterize regional blood flow differences related to vascular activity before and after the application of each vascular artifact-correction method. Both methods eliminated the observed differences in vascular activity, as well as the vascular artifact observed in the anteromedial temporal lobes.
{"title":"Methods for the correction of vascular artifacts in PET O-15 water brain mapping studies","authors":"Kewei Chen, E. Reiman, M. Lawson, L. Yun, D. Bandy, Anita Palant","doi":"10.1109/NSSMIC.1995.510498","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510498","url":null,"abstract":"While positron emission tomographic (PET) measurements of regional cerebral blood flow (CBF) can be used to map regions of the brain that are involved in normal and pathological human behaviors, measurements in the anteromedial temporal lobe can be confounded by the combined effects of radiotracer activity in neighboring arteries and partial volume averaging. The authors now describe two alternative methods for addressing this potential confound. One method utilizes the early frames of a dynamic PET study, while the other method utilizes a coregistered magnetic resonance image (MRI) to characterize the vascular region-of-interest (ROI). Both methods subsequently assign a common value to each pixel in the vascular ROI. To simulate the vascular artifact, four dynamically acquired PET, O-15 water scans in the same subject during the same behavioral state were used to compute 4 vascular images (0-60 s after radiotracer administration) which included vascular activity and 4 control images (20-80 s after radiotracer administration) which did not. t-score maps were used to characterize regional blood flow differences related to vascular activity before and after the application of each vascular artifact-correction method. Both methods eliminated the observed differences in vascular activity, as well as the vascular artifact observed in the anteromedial temporal lobes.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"2 6 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":"116861937","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.1995.501933
Craig S. Levin, L. R. MacDonald, M. Tornai, Edward J. Hoffman, J. Park
The authors are developing a 1-2 cm/sup 2/ area camera for imaging the distribution of beta-emitting radiopharmaceuticals at the surface of tissue exposed during surgery. The front end consists of a very thin continuous or segmented scintillator sensitive to betas (positrons or electrons) of a few hundred keV, yet insensitive to gamma rays. The light from the scintillator is piped through clear fibers to the photon detector (PD). This approach requires that a sufficient number of scintillation photons be transported from the scintillator, through the fibers to the PD. The scintillator, reflector, surface treatments, geometry, fiber light guides, and optical couplings must be optimized. The authors report here on efforts made to optimize the light collection from <3 mm thick plastic and CaF/sub 2/(Eu) scintillators into clear fibers using experimental measurements and computer simulations. The authors measured that with a 1.25 cm diameter, 0.5 mm thick optimized CaF/sub 2/(Eu) disk coupled to a 5 cm long bundle of clear optical fibers, on average, /spl sim/250 photoelectrons are produced at a PMT photocathode for a /sup 204/Tl beta flood source (E/sub max/=763 keV). This corresponds to a sufficient number of photoelectrons for <1 mm resolution imaging capabilities for the proposed camera.
{"title":"OPTIMIZING LIGHT COLLECTION FROM THIN SCINTILLATORS USED IN A BETA-RAY CAMERA FOR SURGICAL USE","authors":"Craig S. Levin, L. R. MacDonald, M. Tornai, Edward J. Hoffman, J. Park","doi":"10.1109/NSSMIC.1995.501933","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.501933","url":null,"abstract":"The authors are developing a 1-2 cm/sup 2/ area camera for imaging the distribution of beta-emitting radiopharmaceuticals at the surface of tissue exposed during surgery. The front end consists of a very thin continuous or segmented scintillator sensitive to betas (positrons or electrons) of a few hundred keV, yet insensitive to gamma rays. The light from the scintillator is piped through clear fibers to the photon detector (PD). This approach requires that a sufficient number of scintillation photons be transported from the scintillator, through the fibers to the PD. The scintillator, reflector, surface treatments, geometry, fiber light guides, and optical couplings must be optimized. The authors report here on efforts made to optimize the light collection from <3 mm thick plastic and CaF/sub 2/(Eu) scintillators into clear fibers using experimental measurements and computer simulations. The authors measured that with a 1.25 cm diameter, 0.5 mm thick optimized CaF/sub 2/(Eu) disk coupled to a 5 cm long bundle of clear optical fibers, on average, /spl sim/250 photoelectrons are produced at a PMT photocathode for a /sup 204/Tl beta flood source (E/sub max/=763 keV). This corresponds to a sufficient number of photoelectrons for <1 mm resolution imaging capabilities for the proposed camera.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"110 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":"117186917","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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