Pub Date : 1995-10-21DOI: 10.1109/NSSMIC.1995.504236
J. Millaud, D. Nygren
We describe an electronic architecture for two-dimensional pixel arrays that permits very large increases in rate capability for event- or data-driven applications relative to conventional x-y architectures. The column architecture also permits more efficient use of silicon area in applications requiring local buffering, frameless data acquisition, and it avoids entirely the problem of ambiguities that may arise in conventional approaches. Two examples of active implementation are described: high energy physics and protein crystallography.
{"title":"The column architecture-a novel architecture for event driven 2D pixel imagers","authors":"J. Millaud, D. Nygren","doi":"10.1109/NSSMIC.1995.504236","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504236","url":null,"abstract":"We describe an electronic architecture for two-dimensional pixel arrays that permits very large increases in rate capability for event- or data-driven applications relative to conventional x-y architectures. The column architecture also permits more efficient use of silicon area in applications requiring local buffering, frameless data acquisition, and it avoids entirely the problem of ambiguities that may arise in conventional approaches. Two examples of active implementation are described: high energy physics and protein crystallography.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"46 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":"126808233","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.1995.504167
S. Siegel, R. Silverman, Y. Shao, S. Cherry
Three simple charge division circuits were assembled, and tested, as 2-D readouts for multi-channel photomultiplier tubes (MC-PMT). They were evaluated with an 8/spl times/8 array of individual scintillators (2/spl times/2/spl times/10 mm BGO) coupled to a 64 channel MC-PMT (Philips XP1722) via 25 cm long, 2 mm diameter, double clad, optical fibers (Kuraray). This type of /spl gamma/-ray imaging detector has many potential applications in medical and industrial imaging. Independent channel readout allows for the discrimination of scatter within the array, and higher count rates, but it requires an excessive amount of supporting electronics. This is specially true for multi-array imaging systems with hundreds, or thousands, of channels. In this study, the number of channels being read out was reduced from 64 to 4. This was achieved by the use of simple resistor networks which take advantage of the discretized nature of the scintillator array, the low crosstalk of the MC-PMT and low input impedance current-sensitive preamplifiers. For each circuit, the scintillator identification accuracy was compared. The identification accuracy as a function of deposited energy was also determined by exposure to various /spl gamma/ emitters. It was found that the preamplifier circuit noise contributed the most to the degradation of the detector's spatial response so several low noise op amps were evaluated. It was also determined that keeping the preamplifier input impedance small was necessary for accurate positioning. The timing resolution of the detector was slightly degraded by the readout circuit.
{"title":"Simple charge division readouts for imaging scintillator arrays using a multi-channel PMT","authors":"S. Siegel, R. Silverman, Y. Shao, S. Cherry","doi":"10.1109/NSSMIC.1995.504167","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504167","url":null,"abstract":"Three simple charge division circuits were assembled, and tested, as 2-D readouts for multi-channel photomultiplier tubes (MC-PMT). They were evaluated with an 8/spl times/8 array of individual scintillators (2/spl times/2/spl times/10 mm BGO) coupled to a 64 channel MC-PMT (Philips XP1722) via 25 cm long, 2 mm diameter, double clad, optical fibers (Kuraray). This type of /spl gamma/-ray imaging detector has many potential applications in medical and industrial imaging. Independent channel readout allows for the discrimination of scatter within the array, and higher count rates, but it requires an excessive amount of supporting electronics. This is specially true for multi-array imaging systems with hundreds, or thousands, of channels. In this study, the number of channels being read out was reduced from 64 to 4. This was achieved by the use of simple resistor networks which take advantage of the discretized nature of the scintillator array, the low crosstalk of the MC-PMT and low input impedance current-sensitive preamplifiers. For each circuit, the scintillator identification accuracy was compared. The identification accuracy as a function of deposited energy was also determined by exposure to various /spl gamma/ emitters. It was found that the preamplifier circuit noise contributed the most to the degradation of the detector's spatial response so several low noise op amps were evaluated. It was also determined that keeping the preamplifier input impedance small was necessary for accurate positioning. The timing resolution of the detector was slightly degraded by the readout circuit.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"100 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":"115549604","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.1995.500320
C. J. Leliveld, J. Maas, V. Bom, C. V. van Eijk
In this study, the authors present Monte Carlo (MC) simulation results for the intensity and angular distribution of scattered radiation from cylindrical absorbers. For coherent scattering the authors have taken into account the effects of interference by using new molecular form factor data for the AAPM plastic materials and water. The form factor data were compiled from X-ray diffraction measurements. The new data have been implemented in the authors' Electron Gamma Shower (EGS4) Monte Carlo system. The hybrid MC simulation results show a significant influence on the intensity and the angular distribution of coherently scattered photons. It is concluded that MC calculations are significantly in error when interference effects are ignored in the model for coherent scattering. Especially for simulation studies of scattered radiation in collimated geometries, where small angle scattering will prevail, the coherent scatter contribution is highly overestimated when conventional form factor data are used.
{"title":"Monte Carlo modeling of coherent scattering: influence of interference","authors":"C. J. Leliveld, J. Maas, V. Bom, C. V. van Eijk","doi":"10.1109/NSSMIC.1995.500320","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500320","url":null,"abstract":"In this study, the authors present Monte Carlo (MC) simulation results for the intensity and angular distribution of scattered radiation from cylindrical absorbers. For coherent scattering the authors have taken into account the effects of interference by using new molecular form factor data for the AAPM plastic materials and water. The form factor data were compiled from X-ray diffraction measurements. The new data have been implemented in the authors' Electron Gamma Shower (EGS4) Monte Carlo system. The hybrid MC simulation results show a significant influence on the intensity and the angular distribution of coherently scattered photons. It is concluded that MC calculations are significantly in error when interference effects are ignored in the model for coherent scattering. Especially for simulation studies of scattered radiation in collimated geometries, where small angle scattering will prevail, the coherent scatter contribution is highly overestimated when conventional form factor data are used.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"26 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":"116188085","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.1995.500273
T. Hebert, W. Moore, R. Dhekne, P. Ford, J. Wendt, P. Murphy
The design of automated computer algorithms for delineating the left and right ventricular regions within gated 3-D reconstructions of the cardiac blood pool is investigated. Due to patient functional abnormalities, limited resolution, and noise, certain spatial and temporal features of the cardiac blood pool that one would anticipate finding in every study are not present in certain frames or with certain patients. Therefore, the labeling of the chambers of the cardiac blood pool requires an algorithm that only relies upon features present in all patients. We examine a sequential algorithm wherein the limiting factor in the accuracy and reliability of the algorithm is that of locating the atrio-ventricular valve planes.
{"title":"Design of automated algorithms for analyzing gated SPECT cardiac blood pool images","authors":"T. Hebert, W. Moore, R. Dhekne, P. Ford, J. Wendt, P. Murphy","doi":"10.1109/NSSMIC.1995.500273","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500273","url":null,"abstract":"The design of automated computer algorithms for delineating the left and right ventricular regions within gated 3-D reconstructions of the cardiac blood pool is investigated. Due to patient functional abnormalities, limited resolution, and noise, certain spatial and temporal features of the cardiac blood pool that one would anticipate finding in every study are not present in certain frames or with certain patients. Therefore, the labeling of the chambers of the cardiac blood pool requires an algorithm that only relies upon features present in all patients. We examine a sequential algorithm wherein the limiting factor in the accuracy and reliability of the algorithm is that of locating the atrio-ventricular valve planes.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"58 3 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":"116519747","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.1995.510417
J. C. Stewart, R. C. Wilson
The use of commercially available digital computer systems and components in safety critical systems (nuclear power plant, military, and commercial applications) is increasing rapidly. Commercial dedication (the process of assuring that a commercial grade item will perform its intended safety function) has demonstrated benefits in cost savings and a wide base of user experience, however, care must be taken to avoid difficulties with some aspects of the dedication process such as access to vendor development information, configuration management, long term support, and system integration.
{"title":"A NRC perspective on the revised 10 CFR part 21 rule for the procurement of commercial digital computer systems for use in safety system applications in nuclear power facilities","authors":"J. C. Stewart, R. C. Wilson","doi":"10.1109/NSSMIC.1995.510417","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510417","url":null,"abstract":"The use of commercially available digital computer systems and components in safety critical systems (nuclear power plant, military, and commercial applications) is increasing rapidly. Commercial dedication (the process of assuring that a commercial grade item will perform its intended safety function) has demonstrated benefits in cost savings and a wide base of user experience, however, care must be taken to avoid difficulties with some aspects of the dedication process such as access to vendor development information, configuration management, long term support, and system integration.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"51 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":"122644604","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.1995.500301
L. Arata, P. H. Pretorius, M. King
Organ motion during SPECT acquisition can cause artifacts in the reconstructed slices which may affect the clinical interpretation. A new algorithm is presented which corrects for translational organ motion in SPECT projection data and thus reduces the resulting artifacts. The projection data is first reconstructed and then reprojected to the original angles. These reprojection data provide a template for comparison with the true projection data to estimate motion. An organ of interest is selected interactively using a count threshold on the reconstructed slices. From this, regions of interest are reprojected and used to limit the region of comparison and improve efficiency. Parabolic interpolation is used to interpolate fractional shifts. The algorithm corrects for translational motion in the projection data along both X and Y axes. The algorithm was evaluated using point sources in air with physical motion induced during acquisition and artificially induced motion using Monte Carlo simulated MCAT phantom data. Results show that the FWHM's and FWTM's of corrected point source data compare favorably with point source data without motion induced. Polar maps of the MCAT phantom clearly show the improvement after the correction was implemented. Further validation and clinical testing are in progress.
{"title":"Correction of organ motion in SPECT using reprojection data","authors":"L. Arata, P. H. Pretorius, M. King","doi":"10.1109/NSSMIC.1995.500301","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500301","url":null,"abstract":"Organ motion during SPECT acquisition can cause artifacts in the reconstructed slices which may affect the clinical interpretation. A new algorithm is presented which corrects for translational organ motion in SPECT projection data and thus reduces the resulting artifacts. The projection data is first reconstructed and then reprojected to the original angles. These reprojection data provide a template for comparison with the true projection data to estimate motion. An organ of interest is selected interactively using a count threshold on the reconstructed slices. From this, regions of interest are reprojected and used to limit the region of comparison and improve efficiency. Parabolic interpolation is used to interpolate fractional shifts. The algorithm corrects for translational motion in the projection data along both X and Y axes. The algorithm was evaluated using point sources in air with physical motion induced during acquisition and artificially induced motion using Monte Carlo simulated MCAT phantom data. Results show that the FWHM's and FWTM's of corrected point source data compare favorably with point source data without motion induced. Polar maps of the MCAT phantom clearly show the improvement after the correction was implemented. Further validation and clinical testing are in progress.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"23 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":"122988114","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.1995.510372
F. Pengg, M. Campbell, E. Heijne, W. Snoeys
Pixel detector readout cells have been designed in the radiation hard DMILL technology and their characteristics evaluated before and after irradiation to 14 Mrad. The test chip consists of two blocks of six readout cells each. Two different charge amplifiers are implemented, one of them using a capacitive feedback loop, the other the fast signal charge transfer to a high impedance integrating node. The measurements give the following results: the equivalent noise charge is 110e/sup -/ RMS (150e/sup -/ RMS after irradiation); at a threshold of 5000e/sup -/ (4000e(/sup -/)) the threshold variation is 300e/sup -/ RMS (250e/sup -/ RMS) and the time walk is 40 ns (40 ns). The use of this SOI technology for monolithic integration of electronics and detector in one substrate is under investigation.
{"title":"Pixel frontend electronics in a radiation hard technology for hybrid and monolithic applications","authors":"F. Pengg, M. Campbell, E. Heijne, W. Snoeys","doi":"10.1109/NSSMIC.1995.510372","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510372","url":null,"abstract":"Pixel detector readout cells have been designed in the radiation hard DMILL technology and their characteristics evaluated before and after irradiation to 14 Mrad. The test chip consists of two blocks of six readout cells each. Two different charge amplifiers are implemented, one of them using a capacitive feedback loop, the other the fast signal charge transfer to a high impedance integrating node. The measurements give the following results: the equivalent noise charge is 110e/sup -/ RMS (150e/sup -/ RMS after irradiation); at a threshold of 5000e/sup -/ (4000e(/sup -/)) the threshold variation is 300e/sup -/ RMS (250e/sup -/ RMS) and the time walk is 40 ns (40 ns). The use of this SOI technology for monolithic integration of electronics and detector in one substrate is under investigation.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"34 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":"114297341","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.1995.510365
A. Foland, J. Alexander
After exposure to X-rays and UV light, we have observed induced leakage currents in silicon microstrip detectors designed for CLEO III. UV measurements have shown that the damage is confined to the Si-SiO/sub 2/ interfacial area. The damage is manifested only as a leakage current without additional 1/f noise or significant changes to detector parameters. The scaled damage rate is measured to be 5/spl plusmn/1 nA/cm/sup 2//kRad for 20 keV X-rays.
{"title":"Radiation-induced surface leakage currents in silicon microstrip detectors","authors":"A. Foland, J. Alexander","doi":"10.1109/NSSMIC.1995.510365","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510365","url":null,"abstract":"After exposure to X-rays and UV light, we have observed induced leakage currents in silicon microstrip detectors designed for CLEO III. UV measurements have shown that the damage is confined to the Si-SiO/sub 2/ interfacial area. The damage is manifested only as a leakage current without additional 1/f noise or significant changes to detector parameters. The scaled damage rate is measured to be 5/spl plusmn/1 nA/cm/sup 2//kRad for 20 keV X-rays.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"40 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":"114513792","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.1995.500254
R. Lecomte, J. Cadorette, S. Rodrigue, D. Lapointe, D. Rouleau, M. Bentourkia, R. Yao, P. Msaki, G. Schmutz
The design features and engineering constraints of a PET system based on avalanche photodiode (APD) detectors have been described in a previous report. Here, the authors present the initial results obtained with the Sherbrooke APD-PET scanner, a very high spatial resolution device designed for dynamic imaging of small and medium-sized laboratory animals such as rats, cats, rabbits and small monkeys. Its physical performance have been evaluated in terms of resolution, sensitivity, count rate, random and scatter fractions, and activity recovery as a function of object size. The capabilities of the scanner for biomedical research applications have been demonstrated using phantom and animal studies.
{"title":"Initial results from the Sherbrooke avalanche photodiode PET scanner","authors":"R. Lecomte, J. Cadorette, S. Rodrigue, D. Lapointe, D. Rouleau, M. Bentourkia, R. Yao, P. Msaki, G. Schmutz","doi":"10.1109/NSSMIC.1995.500254","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.500254","url":null,"abstract":"The design features and engineering constraints of a PET system based on avalanche photodiode (APD) detectors have been described in a previous report. Here, the authors present the initial results obtained with the Sherbrooke APD-PET scanner, a very high spatial resolution device designed for dynamic imaging of small and medium-sized laboratory animals such as rats, cats, rabbits and small monkeys. Its physical performance have been evaluated in terms of resolution, sensitivity, count rate, random and scatter fractions, and activity recovery as a function of object size. The capabilities of the scanner for biomedical research applications have been demonstrated using phantom and animal studies.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"3 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":"129501338","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.1995.510437
M. Dahlbom, A. Chatziioannou, C. Hoh
By acquiring whole body data at a large number of small axial positions, each equal to the transaxial plane separation, one can achieve a significant improvement in image quality. This improvement is attributed to the uniform axial sensitivity achieved by allowing each detector plane measure each axial data point. By moving the bed in a true continuous motion, instead of in discrete steps, one can achieve additional improvements in image quality by eliminating artifacts due to under-sampling in the axial direction. To investigate the properties of the continuous axial sampling, measurements and simulations of an ECAT EXACT HR PET system were performed. The axial resolution of this system is 3.5 mm at the center of the FOV and the axial sampling is approximately 3.1 mm. This system clearly undersamples axially and sampling artifacts were also seen in a hot spot phantom and bar patterns, imaged in the axial direction. By moving the bed continuously and sort the data into smaller bins (<1.6 mm) these sampling artifacts were virtually eliminated. Images acquired at a high sampling frequency had better image contrast and noise characteristics after spatial filtering compared to images with the same total number of counts but acquired at a low spatial frequency.
{"title":"Resolution characterization of continuous axial sampling in whole body PET","authors":"M. Dahlbom, A. Chatziioannou, C. Hoh","doi":"10.1109/NSSMIC.1995.510437","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510437","url":null,"abstract":"By acquiring whole body data at a large number of small axial positions, each equal to the transaxial plane separation, one can achieve a significant improvement in image quality. This improvement is attributed to the uniform axial sensitivity achieved by allowing each detector plane measure each axial data point. By moving the bed in a true continuous motion, instead of in discrete steps, one can achieve additional improvements in image quality by eliminating artifacts due to under-sampling in the axial direction. To investigate the properties of the continuous axial sampling, measurements and simulations of an ECAT EXACT HR PET system were performed. The axial resolution of this system is 3.5 mm at the center of the FOV and the axial sampling is approximately 3.1 mm. This system clearly undersamples axially and sampling artifacts were also seen in a hot spot phantom and bar patterns, imaged in the axial direction. By moving the bed continuously and sort the data into smaller bins (<1.6 mm) these sampling artifacts were virtually eliminated. Images acquired at a high sampling frequency had better image contrast and noise characteristics after spatial filtering compared to images with the same total number of counts but acquired at a low spatial frequency.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"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":"129830329","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：