Pub Date : 1995-10-21DOI: 10.1109/NSSMIC.1995.504293
M. Reginatto, P. Shebell, K. M. Miller
An important requirement in surveying for residual radioactivity is the detection of localized areas of elevated contamination, sometimes referred to as hot spots. In the present work we have developed a computer code that searches for distributions of surface activity (possibly many) that are consistent with a series of in situ measurements on a grid indicating the possible presence of hot spots. The algorithm makes use of a maximum entropy deconvolution of the data, followed by further analysis. The algorithm is quite general and could be modified for use in other types of measurements. Properties of the algorithm are demonstrated using data from actual field measurements.
{"title":"An application of the maximum entropy method for assessments of residual radioactivity at contaminated sites","authors":"M. Reginatto, P. Shebell, K. M. Miller","doi":"10.1109/NSSMIC.1995.504293","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504293","url":null,"abstract":"An important requirement in surveying for residual radioactivity is the detection of localized areas of elevated contamination, sometimes referred to as hot spots. In the present work we have developed a computer code that searches for distributions of surface activity (possibly many) that are consistent with a series of in situ measurements on a grid indicating the possible presence of hot spots. The algorithm makes use of a maximum entropy deconvolution of the data, followed by further analysis. The algorithm is quite general and could be modified for use in other types of measurements. Properties of the algorithm are demonstrated using data from actual field measurements.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"7 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":"130211577","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.1995.504224
H. Crawley, R. Mckay, W. Meyer, E. Rosenberg, W. D. Thomas
We have used IEEE Trial Use Standard 1057 since 1989 for testing and evaluating analog-to-digital converters for use in high energy physics experiments. This standard primarily covers waveform digitizers, such as digital oscilloscopes, but much of it is applicable to testing ADCs. Using DC levels and sine, triangle, and specialized waveforms, we measure parameters such as integral and differential nonlinearity, number of effective bits, word error rate, short term settling time, and overvoltage recovery. We summarize the tests performed and describe our experience in using the standard.
{"title":"Using IEEE standard 1057 for testing analog-to-digital converters","authors":"H. Crawley, R. Mckay, W. Meyer, E. Rosenberg, W. D. Thomas","doi":"10.1109/NSSMIC.1995.504224","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504224","url":null,"abstract":"We have used IEEE Trial Use Standard 1057 since 1989 for testing and evaluating analog-to-digital converters for use in high energy physics experiments. This standard primarily covers waveform digitizers, such as digital oscilloscopes, but much of it is applicable to testing ADCs. Using DC levels and sine, triangle, and specialized waveforms, we measure parameters such as integral and differential nonlinearity, number of effective bits, word error rate, short term settling time, and overvoltage recovery. We summarize the tests performed and describe our experience in using the standard.","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":"130632890","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.1995.510444
D. Bailey, T. Jones
Calibration for 3D PET using a uniform cylinder and cross-calibration with aliquots requires correction for scatter and attenuation. Thus the accuracy of the calibration is dependent on the scatter correction method, and on the applicability of the scatter correction for different regions of the body. A method has been developed which provides a calibration which does not require correction for scatter or attenuation, making it generally applicable and independent of the scatter correction. The method has been previously described for measurement of the absolute sensitivity of tomographic devices. This approach has been extended to give a calibration of the PET camera 'in air' in units of kBq/pixel. The reconstructed images are multiplied by this factor to give accurate activity concentrations, after attenuation and scatter correction. The method has been used with a fully 3D filtered-backprojection (reprojection) algorithm and iterative convolution-subtraction scatter correction on data from an ECAT 953B. Using this method 3D PET images have been calibrated to within 5% accuracy, but this is highly dependent on the accuracy of the scatter correction. The method described here is practical and provides a means of calibrating a 3D PET system without needing correction for scatter or attenuation of the calibration data.
{"title":"A method for calibrating 3D PET without scatter correction","authors":"D. Bailey, T. Jones","doi":"10.1109/NSSMIC.1995.510444","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510444","url":null,"abstract":"Calibration for 3D PET using a uniform cylinder and cross-calibration with aliquots requires correction for scatter and attenuation. Thus the accuracy of the calibration is dependent on the scatter correction method, and on the applicability of the scatter correction for different regions of the body. A method has been developed which provides a calibration which does not require correction for scatter or attenuation, making it generally applicable and independent of the scatter correction. The method has been previously described for measurement of the absolute sensitivity of tomographic devices. This approach has been extended to give a calibration of the PET camera 'in air' in units of kBq/pixel. The reconstructed images are multiplied by this factor to give accurate activity concentrations, after attenuation and scatter correction. The method has been used with a fully 3D filtered-backprojection (reprojection) algorithm and iterative convolution-subtraction scatter correction on data from an ECAT 953B. Using this method 3D PET images have been calibrated to within 5% accuracy, but this is highly dependent on the accuracy of the scatter correction. The method described here is practical and provides a means of calibrating a 3D PET system without needing correction for scatter or attenuation of the calibration data.","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":"130641291","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.1995.510497
P. H. Pretorius, Matt A. King, S. Glick, Tin-Su Pan, D. Luo
The determination of quantitative parameters such as the maximum and total counts in a volume are influenced by the partial volume effect. The magnitude of this effect varies with the non-stationary spatial resolution inherent in SPECT imaging compared to the size and shape of the object, and the relative concentration of the object to its background. The objective of this investigation was to determine if the FDR (Frequency Distance Relationship) restoration filtering can reduce the impact of distance dependent spatial resolution on the quantitation of activity. An analytical projector which incorporates attenuation and distance dependent blurring was used to simulate small hot spherical objects in an cylindrical attenuator as imaged with a LEUHR collimator. FDR restoration filtering regularized using different Gaussian and parametric Wiener filters, was employed after attenuation correction with Bellini's method. Projections were also processed using Bellini's attenuation correction method followed by filtered backprojection and 3D Butterworth filtering with different cut-off frequencies. CCR's (Center Count Ratios) and TCR's (Total Count Ratios) were determined as the observed counts over true counts. Results show that after FDR restoration the CCR and TCR become approximately position invariant. However, when regularizing the FDR inverse filter with a Gaussian function, CCR's become highly unstable as the standard deviation (/spl sigma/) decreased below that at the center of rotation. The use of the Gaussian and parametric Wiener filters to regularize FDR filtering introduce noise in the CCR's but improve recovery of TCR's over that of the center of rotation.
{"title":"Reducing the effect of non-stationary resolution on activity quantitation with the frequency distance relationship in SPECT","authors":"P. H. Pretorius, Matt A. King, S. Glick, Tin-Su Pan, D. Luo","doi":"10.1109/NSSMIC.1995.510497","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510497","url":null,"abstract":"The determination of quantitative parameters such as the maximum and total counts in a volume are influenced by the partial volume effect. The magnitude of this effect varies with the non-stationary spatial resolution inherent in SPECT imaging compared to the size and shape of the object, and the relative concentration of the object to its background. The objective of this investigation was to determine if the FDR (Frequency Distance Relationship) restoration filtering can reduce the impact of distance dependent spatial resolution on the quantitation of activity. An analytical projector which incorporates attenuation and distance dependent blurring was used to simulate small hot spherical objects in an cylindrical attenuator as imaged with a LEUHR collimator. FDR restoration filtering regularized using different Gaussian and parametric Wiener filters, was employed after attenuation correction with Bellini's method. Projections were also processed using Bellini's attenuation correction method followed by filtered backprojection and 3D Butterworth filtering with different cut-off frequencies. CCR's (Center Count Ratios) and TCR's (Total Count Ratios) were determined as the observed counts over true counts. Results show that after FDR restoration the CCR and TCR become approximately position invariant. However, when regularizing the FDR inverse filter with a Gaussian function, CCR's become highly unstable as the standard deviation (/spl sigma/) decreased below that at the center of rotation. The use of the Gaussian and parametric Wiener filters to regularize FDR filtering introduce noise in the CCR's but improve recovery of TCR's over that of the center of rotation.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"14 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":"131938493","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.1995.510482
B. Mair, M. Rao, J. Anderson
The authors introduce a refined version of the mathematical model introduced by Shepp and Vardi (1982) for positron emission tomography. This model replaces the finite-dimensional Shepp-Vardi linear system by a nonstandard integral equation in which the data-space is finite-dimensional, but the unknown emission intensities are represented by a mathematical measure on the region of interest. As in the finite-dimensional model, the authors obtain an iterative procedure which generates a sequence of functions. Such a functional iteration has already been proposed by other researchers for solving a general class of linear inverse problems. However, unlike the finite-dimensional version, to date, the convergence of this infinite-dimensional version has not been established. This paper discusses issues relating to computer data simulation and present examples which suggest that this refined model should eventually lead to more accurate reconstruction algorithms. The authors also present a mathematical approach for proving convergence.
{"title":"A refined mathematical model for positron emission tomography","authors":"B. Mair, M. Rao, J. Anderson","doi":"10.1109/NSSMIC.1995.510482","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510482","url":null,"abstract":"The authors introduce a refined version of the mathematical model introduced by Shepp and Vardi (1982) for positron emission tomography. This model replaces the finite-dimensional Shepp-Vardi linear system by a nonstandard integral equation in which the data-space is finite-dimensional, but the unknown emission intensities are represented by a mathematical measure on the region of interest. As in the finite-dimensional model, the authors obtain an iterative procedure which generates a sequence of functions. Such a functional iteration has already been proposed by other researchers for solving a general class of linear inverse problems. However, unlike the finite-dimensional version, to date, the convergence of this infinite-dimensional version has not been established. This paper discusses issues relating to computer data simulation and present examples which suggest that this refined model should eventually lead to more accurate reconstruction algorithms. The authors also present a mathematical approach for proving convergence.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"22 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":"132322806","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.1995.500270
L. Shao, J. Karp
A modified convolution-subtraction (CS) scatter correction technique in 3D PET imaging has been proposed and evaluated. It can compensate for the shortcomings with the conventional CS techniques, which are commonly used in 2D PET data. The shortcomings include requiring the position-dependent scatter-kernel calibration, the non-standard convolution and long processing time. The modified CS technique assumes that the position-dependent scatter response function (SRF) can be modeled by a product of an average SRF, an adjustable parameter and a relative scatter fraction function. The relative scatter fraction function is a function of source position. The technique was applied to both simulated and measured data. The preliminary results indicate that the modified CS scattering correction technique is practical and robust to the sizes of objects. It provides more accurate scatter estimates than the conventional CS techniques, especially for highly nonuniform distributed sources.
{"title":"Modified convolution-subtraction scattering correction technique for 3D PET","authors":"L. Shao, J. Karp","doi":"10.1109/NSSMIC.1995.500270","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500270","url":null,"abstract":"A modified convolution-subtraction (CS) scatter correction technique in 3D PET imaging has been proposed and evaluated. It can compensate for the shortcomings with the conventional CS techniques, which are commonly used in 2D PET data. The shortcomings include requiring the position-dependent scatter-kernel calibration, the non-standard convolution and long processing time. The modified CS technique assumes that the position-dependent scatter response function (SRF) can be modeled by a product of an average SRF, an adjustable parameter and a relative scatter fraction function. The relative scatter fraction function is a function of source position. The technique was applied to both simulated and measured data. The preliminary results indicate that the modified CS scattering correction technique is practical and robust to the sizes of objects. It provides more accurate scatter estimates than the conventional CS techniques, especially for highly nonuniform distributed sources.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"54 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":"128802115","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.1995.500317
M. Smith, R. Jaszczak, H. Wang, J. Li
The potential use of lead and tungsten pinhole inserts for high resolution SPECT imaging of intratumor activity in I-131 radioimmunotherapy is investigated using experimental point source measurements, and raytracing and Monte Carlo simulations. I-131 imaging is challenging because the primary photon emission is at 364 keV and penetration through the insert near the pinhole aperture is significant. Point source response functions (PSRFs) for Pb and W pinhole inserts are measured and are modeled using raytracing simulations. More accurate simulation of the PSRFs may require the modeling of scatter within the pinhole insert and of higher energy emissions at 637 and 723 keV. A numerical study of geometrically identical pinhole inserts made of Pb and W shows narrower point source response functions for the W insert due to reduced penetration. Monte Carlo modeling was used to compare these inserts for SPECT pinhole imaging of 3 cm diameter tumors with a central core and 3-5 mm thick shells. The shell:core activity concentration ratio was 5:1. The tumor shells are resolved for the W insert but not for the Pb insert. As a result, shell:core activity ratios are more accurate with the use of the W pinhole insert. Experimental SPECT acquisitions are needed to confirm the potential advantages of a W insert over a Pb insert suggested by this study.
{"title":"Application of lead and tungsten pinhole inserts to I-131 SPECT tumor imaging: a Monte Carlo investigation","authors":"M. Smith, R. Jaszczak, H. Wang, J. Li","doi":"10.1109/NSSMIC.1995.500317","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500317","url":null,"abstract":"The potential use of lead and tungsten pinhole inserts for high resolution SPECT imaging of intratumor activity in I-131 radioimmunotherapy is investigated using experimental point source measurements, and raytracing and Monte Carlo simulations. I-131 imaging is challenging because the primary photon emission is at 364 keV and penetration through the insert near the pinhole aperture is significant. Point source response functions (PSRFs) for Pb and W pinhole inserts are measured and are modeled using raytracing simulations. More accurate simulation of the PSRFs may require the modeling of scatter within the pinhole insert and of higher energy emissions at 637 and 723 keV. A numerical study of geometrically identical pinhole inserts made of Pb and W shows narrower point source response functions for the W insert due to reduced penetration. Monte Carlo modeling was used to compare these inserts for SPECT pinhole imaging of 3 cm diameter tumors with a central core and 3-5 mm thick shells. The shell:core activity concentration ratio was 5:1. The tumor shells are resolved for the W insert but not for the Pb insert. As a result, shell:core activity ratios are more accurate with the use of the W pinhole insert. Experimental SPECT acquisitions are needed to confirm the potential advantages of a W insert over a Pb insert suggested by this study.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"1 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":"128833605","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.1995.510429
W. Wong, J. Uribe, WeiZhao Lu, Guoji Hu, K. Hicks
A prototype PET camera has been designed and is being constructed to test the concept, and develop the engineering design and production methodology for a variable field PET camera. The long term goal of the design is to develop a lower cost, high resolution PET camera. The camera has eight detector heads which form a closely packed octagon detector ring with an average diameter of 44 cm for brain/breast and animal model imaging. The heads can be translated radially to a maximum ring diameter of 70 cm for whole body imaging. In the larger diameter modes, the camera rotates 45/spl deg/ during imaging. The camera heads can be set to intermediate positions to fit the camera to the subject size to maximize detection sensitivity and sampling uniformity. The detector design implemented is the quadrant sharing photomultiplier (PMT) design using circular 19 mm PMT. The camera images 27 slices simultaneously. The BGO detector pitch size is 27/spl times/2.7 mm. Preliminary simulation studies have been performed to evaluate the resolution, sensitivity, and sampling uniformity.
{"title":"Design of a variable field prototype PET camera","authors":"W. Wong, J. Uribe, WeiZhao Lu, Guoji Hu, K. Hicks","doi":"10.1109/NSSMIC.1995.510429","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510429","url":null,"abstract":"A prototype PET camera has been designed and is being constructed to test the concept, and develop the engineering design and production methodology for a variable field PET camera. The long term goal of the design is to develop a lower cost, high resolution PET camera. The camera has eight detector heads which form a closely packed octagon detector ring with an average diameter of 44 cm for brain/breast and animal model imaging. The heads can be translated radially to a maximum ring diameter of 70 cm for whole body imaging. In the larger diameter modes, the camera rotates 45/spl deg/ during imaging. The camera heads can be set to intermediate positions to fit the camera to the subject size to maximize detection sensitivity and sampling uniformity. The detector design implemented is the quadrant sharing photomultiplier (PMT) design using circular 19 mm PMT. The camera images 27 slices simultaneously. The BGO detector pitch size is 27/spl times/2.7 mm. Preliminary simulation studies have been performed to evaluate the resolution, sensitivity, and sampling uniformity.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"81 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":"125486038","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.1995.501915
X. Pan, C. Metz, C.-T. Chen
An infinite class of closed-form methods was developed by the authors in 1994 for image reconstruction in 2D SPECT with uniform attenuation. In the work reported here, the authors extended their approach to develop a class of closed-form methods that compensate for the effects of both photon attenuation and distance-dependent spatial resolution in 2D SPECT. These methods, which are characterized by an index n that can be assigned any real number, are exact in the absence of noise but propagate noise differently. The authors implemented this class of methods for SPECT image reconstruction in both computer-simulation and real-data studies. The results demonstrate that this class of methods corrects effectively for the aforementioned effects. Extensive computer simulation studies indicate that the method obtained with n=2, which the authors had proved to be the optimal choice of n in 2D SPECT when only attenuation is present, also provides the smallest global image variance among the methods in the class when compensation for both uniform attenuation and distance-dependent spatial resolution is performed.
{"title":"A class of analytical methods that compensate for attenuation and spatially-variant resolution in 2D SPECT","authors":"X. Pan, C. Metz, C.-T. Chen","doi":"10.1109/NSSMIC.1995.501915","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.501915","url":null,"abstract":"An infinite class of closed-form methods was developed by the authors in 1994 for image reconstruction in 2D SPECT with uniform attenuation. In the work reported here, the authors extended their approach to develop a class of closed-form methods that compensate for the effects of both photon attenuation and distance-dependent spatial resolution in 2D SPECT. These methods, which are characterized by an index n that can be assigned any real number, are exact in the absence of noise but propagate noise differently. The authors implemented this class of methods for SPECT image reconstruction in both computer-simulation and real-data studies. The results demonstrate that this class of methods corrects effectively for the aforementioned effects. Extensive computer simulation studies indicate that the method obtained with n=2, which the authors had proved to be the optimal choice of n in 2D SPECT when only attenuation is present, also provides the smallest global image variance among the methods in the class when compensation for both uniform attenuation and distance-dependent spatial resolution is performed.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"36 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":"126687577","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.1995.504216
T. Tamura, H. Sugeno, H. Sakurai, M. Noma, S. Gunji, Gertenbort
An application of a microstrip gas proportional counter to a X-ray polarimeter was investigated. Primary electron clouds produced by photoelectric absorption extend to the direction of electric vector of incident polarized X-ray and the direction of electron clouds to the microstrip plate (MS plate) affects the rise time of signal from MSGC. By using a test counter which mounted a MS plate, the characteristics of the rise time distributions of pulses from MSGC were investigated. The difference of the rise times between X-rays of /sup 55/Fe and /sup 241/Am sources was 71 nsec in Xe+methane (10%) with 0.4 atm. It reflects the difference of length of the trajectory between 5.9 keV X-rays and 29.8 keV photoelectrons ejected by photoabsorption. The detection of the rise time due to MSGC is available to a X-ray polarimeter.
{"title":"An application of microstrip gas proportional counter for a X-ray polarimeter","authors":"T. Tamura, H. Sugeno, H. Sakurai, M. Noma, S. Gunji, Gertenbort","doi":"10.1109/NSSMIC.1995.504216","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504216","url":null,"abstract":"An application of a microstrip gas proportional counter to a X-ray polarimeter was investigated. Primary electron clouds produced by photoelectric absorption extend to the direction of electric vector of incident polarized X-ray and the direction of electron clouds to the microstrip plate (MS plate) affects the rise time of signal from MSGC. By using a test counter which mounted a MS plate, the characteristics of the rise time distributions of pulses from MSGC were investigated. The difference of the rise times between X-rays of /sup 55/Fe and /sup 241/Am sources was 71 nsec in Xe+methane (10%) with 0.4 atm. It reflects the difference of length of the trajectory between 5.9 keV X-rays and 29.8 keV photoelectrons ejected by photoabsorption. The detection of the rise time due to MSGC is available to a X-ray polarimeter.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"56 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":"123166350","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：