Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551334
C.-H. Wang, S.-M. Liu, Y.-S Teng
We have developed a trigger multiplexer module for the Cylindrical Drift Chamber (CDC) detector for use in the future Belle II experiment. To fully use the existing crate, the module is VME based, capable of handling input lOOGbps and output 40Gbps with optical fiber connections. To lower the cost and the schools infrastructure consideration, the module is designed with the Altera Arria II chip with Aurora protocol. The first prototype modules have been made and the data-link tests between CDC front-end and trigger main module have been performed. Results will be presented and discussed here.
{"title":"The design of high speed trigger multiplexer module for the Belle II Cylindrical Drift Chamber detector","authors":"C.-H. Wang, S.-M. Liu, Y.-S Teng","doi":"10.1109/NSSMIC.2012.6551334","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551334","url":null,"abstract":"We have developed a trigger multiplexer module for the Cylindrical Drift Chamber (CDC) detector for use in the future Belle II experiment. To fully use the existing crate, the module is VME based, capable of handling input lOOGbps and output 40Gbps with optical fiber connections. To lower the cost and the schools infrastructure consideration, the module is designed with the Altera Arria II chip with Aurora protocol. The first prototype modules have been made and the data-link tests between CDC front-end and trigger main module have been performed. Results will be presented and discussed here.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127214859","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551802
M. Rozler, W. Chang
The current trend toward SPECT systems dedicated to imaging specific organs has created new pressures to improve gamma camera performance. A number of designs rely on projection minification to increase system sensitivity by acquiring multiple non-overlapping simultaneous views, placing stringent requirements on detector intrinsic spatial resolution (ISR). Curved detector geometries require modular assemblies, making monolithic slab detectors impractical due to their large dead areas at the edges. Previously, we described a modular detector based on a scintillator block comprised of 2.75 × 2.75 × 10 mm3 NaI(Tl) pixels in a 3 × 3 mm pitch and decoded by an array of 51 mm diameter single-anode PMTs. The event positioning accuracy of the curved detector, averaged over its entire area, exceeds that of a hypothetical monolithic slab detector with 2.75 mm ISR. To reduce the pixel size/pitch and thus increase linear sampling in the transaxial dimension (the dimension along which the detector is curved and minification is applied), we introduce scintillation light output modulation between neighboring pixels. A series of narrow absorbing stripes is applied at the exit surface of every other pixel column, producing a modulation in light output between adjacent pixels and allowing the use of energy discrimination to more effectively assign events to the correct pixel. Compared to the 3×3 mm pitch modules, our new detector, with 2.25 × 2.75 × 10 mm3 NaI(Tl) pixels (2.5 × 3 mm pitch), achieves the same event positioning performance in terms of the average event positioning error, while yielding 10.3% energy resolution. This translates to an improvement in linear sampling, without any loss in positioning accuracy (and, thus, effective spatial resolution), a mod
{"title":"A cost-effective high-resolution modular pixelated clinical SPECT detector based on small NaI (Tl) pixels with medium-size single-anode PMTs, utilizing spatial modulation of scintillation light output","authors":"M. Rozler, W. Chang","doi":"10.1109/NSSMIC.2012.6551802","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551802","url":null,"abstract":"The current trend toward SPECT systems dedicated to imaging specific organs has created new pressures to improve gamma camera performance. A number of designs rely on projection minification to increase system sensitivity by acquiring multiple non-overlapping simultaneous views, placing stringent requirements on detector intrinsic spatial resolution (ISR). Curved detector geometries require modular assemblies, making monolithic slab detectors impractical due to their large dead areas at the edges. Previously, we described a modular detector based on a scintillator block comprised of 2.75 × 2.75 × 10 mm3 NaI(Tl) pixels in a 3 × 3 mm pitch and decoded by an array of 51 mm diameter single-anode PMTs. The event positioning accuracy of the curved detector, averaged over its entire area, exceeds that of a hypothetical monolithic slab detector with 2.75 mm ISR. To reduce the pixel size/pitch and thus increase linear sampling in the transaxial dimension (the dimension along which the detector is curved and minification is applied), we introduce scintillation light output modulation between neighboring pixels. A series of narrow absorbing stripes is applied at the exit surface of every other pixel column, producing a modulation in light output between adjacent pixels and allowing the use of energy discrimination to more effectively assign events to the correct pixel. Compared to the 3×3 mm pitch modules, our new detector, with 2.25 × 2.75 × 10 mm3 NaI(Tl) pixels (2.5 × 3 mm pitch), achieves the same event positioning performance in terms of the average event positioning error, while yielding 10.3% energy resolution. This translates to an improvement in linear sampling, without any loss in positioning accuracy (and, thus, effective spatial resolution), a mod","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127273403","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551048
Xingming Fan, Yi Wang, Xuewu Wang, M. Zeng, Z. Zeng, Ziran Zhao, Jianping Cheng
In order to achieve sub-millimeter position resolution for tracking cosmic ray muon for building muon tomography system, a prototype of MRPC with narrow strips readout is designed and assembled. The width of readout pitch of the module is 2.54mm. Experiments by cosmic rays and X-rays have been carried out. After the calibration for each channel, the position is reconstructed by charge distribution across strips using central gravity. The results shows that the time resolution is about 50ps and the spatial resolution can reach 0.36mm. By this detector, we can not only get the muon track, but also get the muon momentum, which will provide more information for image reconstruction.
{"title":"High position resolution MRPC developed for muon tomography","authors":"Xingming Fan, Yi Wang, Xuewu Wang, M. Zeng, Z. Zeng, Ziran Zhao, Jianping Cheng","doi":"10.1109/NSSMIC.2012.6551048","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551048","url":null,"abstract":"In order to achieve sub-millimeter position resolution for tracking cosmic ray muon for building muon tomography system, a prototype of MRPC with narrow strips readout is designed and assembled. The width of readout pitch of the module is 2.54mm. Experiments by cosmic rays and X-rays have been carried out. After the calibration for each channel, the position is reconstructed by charge distribution across strips using central gravity. The results shows that the time resolution is about 50ps and the spatial resolution can reach 0.36mm. By this detector, we can not only get the muon track, but also get the muon momentum, which will provide more information for image reconstruction.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124913355","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551099
J. Jakubek, S. Pospíšil, J. Vacík, D. Vavřík
Fossil specimen with age in the scale of several billions years can be found hidden in chalk sediments where only a small amount of carbon remains from plant cells embedded in the form of thin interlayers. For their study it is desired to identify such fossils nondestructively. In this work we investigate the possibility to image the tiny carbon structures inside of the relatively high Z mineral material using thermal neutrons. Both micro metric scale spatial resolution and detectability of micrograms of carbon are required for the detection and visualization of microfossils.
{"title":"High resolution neutron imaging of microfossils","authors":"J. Jakubek, S. Pospíšil, J. Vacík, D. Vavřík","doi":"10.1109/NSSMIC.2012.6551099","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551099","url":null,"abstract":"Fossil specimen with age in the scale of several billions years can be found hidden in chalk sediments where only a small amount of carbon remains from plant cells embedded in the form of thin interlayers. For their study it is desired to identify such fossils nondestructively. In this work we investigate the possibility to image the tiny carbon structures inside of the relatively high Z mineral material using thermal neutrons. Both micro metric scale spatial resolution and detectability of micrograms of carbon are required for the detection and visualization of microfossils.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124920746","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551178
K. Gamage, M. Joyce, G. Taylor
In this paper we discuss the possibility of locating a neutron source in space using a scanning-based method, relative to the three-dimensional location of the detector. The scanning system comprises an organic liquid scintillator detector, a tungsten collimator and adjustable equatorial mount. The detector output is connected to a bespoke fast digitiser (Hybrid Instruments Ltd., UK) which streams digital samples to a personal computer. A neutron source has been attached to a vertical wall and the data have been collected in two stages. In the first case, the scanning system was placed a couple of metres away from the wall and, in the second case it moved few centimetres from the previous location, parallel to the wall. In each case data were collected from a grid of measurement points (set of azimuth angles for set of elevation angles) which covered the source on the wall. The discrimination of fast neutrons and gamma rays, detected by organic liquid scintillator detector, is carried out on the basis of pulse gradient analysis. Images are then produced in terms of the angular distribution of events for total counts, gamma rays and neutrons for both cases. The three-dimensional location of the neutron source can be obtained by considering the relative separation of the centres of the corresponding images of angular distribution of events. The measurements have been made at the National Physical Laboratory, Teddington, Middlesex, UK.
{"title":"Investigation of three-dimensional localisation of neutron sources using parallel axis imaging","authors":"K. Gamage, M. Joyce, G. Taylor","doi":"10.1109/NSSMIC.2012.6551178","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551178","url":null,"abstract":"In this paper we discuss the possibility of locating a neutron source in space using a scanning-based method, relative to the three-dimensional location of the detector. The scanning system comprises an organic liquid scintillator detector, a tungsten collimator and adjustable equatorial mount. The detector output is connected to a bespoke fast digitiser (Hybrid Instruments Ltd., UK) which streams digital samples to a personal computer. A neutron source has been attached to a vertical wall and the data have been collected in two stages. In the first case, the scanning system was placed a couple of metres away from the wall and, in the second case it moved few centimetres from the previous location, parallel to the wall. In each case data were collected from a grid of measurement points (set of azimuth angles for set of elevation angles) which covered the source on the wall. The discrimination of fast neutrons and gamma rays, detected by organic liquid scintillator detector, is carried out on the basis of pulse gradient analysis. Images are then produced in terms of the angular distribution of events for total counts, gamma rays and neutrons for both cases. The three-dimensional location of the neutron source can be obtained by considering the relative separation of the centres of the corresponding images of angular distribution of events. The measurements have been made at the National Physical Laboratory, Teddington, Middlesex, UK.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125877645","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551729
A. Ros, R. Aliaga, V. Herrero-Bosch, J. Monzó, Antonio J. González, R. Colom, F. Mora, J. Benlloch
Scintillator based photodetectors tend to increase the number of output signals in order to improve spatial and energy resolutions. AMIC architecture was introduced in previous works as an alternative to traditional charge division front-ends. This novel architecture not only allowed to reduce the number of signals to be acquired but also provided more information about the light distribution on the photodetector surface. Another key feature of this new approach lies in its ability to manage any number of inputs, thus offering an expandable solution for photodetectors with a large number of output signals. The underlying idea in AMIC architecture is to calculate the moments of the detected light distribution in an analog fashion. Due to the additive nature of the moment calculation, the operation can be carried out on a single device or split it into several devices, adding the partial results afterwards. A new integrated front-end device AMIC2GR has been developed which improves several features of the original AMIC architecture. A new preamplifier configuration extends the maximum capacitive load thus allowing compatibility with many types of photomultipliers including SiPM without loss of performance. In order to test the expandability of AMIC architecture using the new AMIC2GR, a front end with 4 devices has been developed. Measurements with a 256-SiPM array were made. Furthermore, a new calibration method (Edna Calibration Method) to compensate gain and detector module differences was developed and tested. AMIC2GR allows to calibrate each SiPM individually to obtain better spatial resolution and homogeneity.
{"title":"Expandable programmable integrated front-end for scintillator based photodetectors","authors":"A. Ros, R. Aliaga, V. Herrero-Bosch, J. Monzó, Antonio J. González, R. Colom, F. Mora, J. Benlloch","doi":"10.1109/NSSMIC.2012.6551729","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551729","url":null,"abstract":"Scintillator based photodetectors tend to increase the number of output signals in order to improve spatial and energy resolutions. AMIC architecture was introduced in previous works as an alternative to traditional charge division front-ends. This novel architecture not only allowed to reduce the number of signals to be acquired but also provided more information about the light distribution on the photodetector surface. Another key feature of this new approach lies in its ability to manage any number of inputs, thus offering an expandable solution for photodetectors with a large number of output signals. The underlying idea in AMIC architecture is to calculate the moments of the detected light distribution in an analog fashion. Due to the additive nature of the moment calculation, the operation can be carried out on a single device or split it into several devices, adding the partial results afterwards. A new integrated front-end device AMIC2GR has been developed which improves several features of the original AMIC architecture. A new preamplifier configuration extends the maximum capacitive load thus allowing compatibility with many types of photomultipliers including SiPM without loss of performance. In order to test the expandability of AMIC architecture using the new AMIC2GR, a front end with 4 devices has been developed. Measurements with a 256-SiPM array were made. Furthermore, a new calibration method (Edna Calibration Method) to compensate gain and detector module differences was developed and tested. AMIC2GR allows to calibrate each SiPM individually to obtain better spatial resolution and homogeneity.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126189506","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551628
B. Weissler, P. Gebhardt, M. Zinke, F. Kiessling, V. Schulz
Improving PET performance towards higher resolution and better sensitivity resulted in a continuous trend - especially in solid state PET and PET/MR - of an increasing number of channels to be read out by the detector electronics. Building complete PET systems with these detectors calls for a modular and self-triggered architecture with distributed processing power that is already in the detector module able to condense the data stream to corrected and gated singles.
{"title":"An MR-compatible singles detection and processing unit for simultaneous preclinical PET/MR","authors":"B. Weissler, P. Gebhardt, M. Zinke, F. Kiessling, V. Schulz","doi":"10.1109/NSSMIC.2012.6551628","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551628","url":null,"abstract":"Improving PET performance towards higher resolution and better sensitivity resulted in a continuous trend - especially in solid state PET and PET/MR - of an increasing number of channels to be read out by the detector electronics. Building complete PET systems with these detectors calls for a modular and self-triggered architecture with distributed processing power that is already in the detector module able to condense the data stream to corrected and gated singles.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125507257","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551587
M. Erbe, T. Sattel, Tobias Knopp, T. Buzug
Magnetic particle imaging (MPI) is a novel functional imaging modality capable of detecting a distribution of superparamagnetic iron oxide (SPIO) tracer material in-vivo in 3D and real-time. Conventional MPI uses a sensitive spot method to scan the region of interest. To increase the sensitivity, however, an alternative encoding scheme using a line detection method was introduced. To provide the magnetic fields needed for dynamic line scanning in MPI a very efficient imager with respect to power consumption is needed. At the same time, the imager needs to provide a high magnetic field quality to ensure that no artifacts are introduced using efficient Radon-based reconstruction methods arising for a line encoding scheme. In this work, the most efficient dynamic FFL scanner design is presented, which outperforms all formerly introduced scanners with respect to magnetic field quality as well as electrical power consumption.
{"title":"Enhancing the efficiency of a field free line scanning device for magnetic particle imaging","authors":"M. Erbe, T. Sattel, Tobias Knopp, T. Buzug","doi":"10.1109/NSSMIC.2012.6551587","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551587","url":null,"abstract":"Magnetic particle imaging (MPI) is a novel functional imaging modality capable of detecting a distribution of superparamagnetic iron oxide (SPIO) tracer material in-vivo in 3D and real-time. Conventional MPI uses a sensitive spot method to scan the region of interest. To increase the sensitivity, however, an alternative encoding scheme using a line detection method was introduced. To provide the magnetic fields needed for dynamic line scanning in MPI a very efficient imager with respect to power consumption is needed. At the same time, the imager needs to provide a high magnetic field quality to ensure that no artifacts are introduced using efficient Radon-based reconstruction methods arising for a line encoding scheme. In this work, the most efficient dynamic FFL scanner design is presented, which outperforms all formerly introduced scanners with respect to magnetic field quality as well as electrical power consumption.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125691532","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551594
A. Turco, I. Valastyán, M. Colarieti-Tosti
By means of computer simulations, scatter fraction, spatial resolution and sensitivity of two 10-detector-module small-animal PET (r77-miniPET and r106-miniPET), are analyzed and compared to the performance of the 12-detector-module PET scanner miniPET II [1]. All simulations have been performed with the well validated Geant4 Application for Emission Tomography (GATE) [2]. Sensitivity and scatter fraction speak in favor of the 10-module scanner: a clear improvement in count rate and scatter fraction was found. Moreover, steeper slopes of noise equivalent count rate curves at low levels of activity was found. Spatial resolution instead was found to be better in the 12-module scanner. The encouraging results here presented particularly refer to r77-miniPET: all things considered, the 10-detector design behaves better than miniPET II if there are no gaps between detector modules. Preliminary trials performed with 8 detector modules in a ring are even more encouraging and need further assessment.
{"title":"Modular miniPET: A comparison between 10 and 12 detector modules","authors":"A. Turco, I. Valastyán, M. Colarieti-Tosti","doi":"10.1109/NSSMIC.2012.6551594","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551594","url":null,"abstract":"By means of computer simulations, scatter fraction, spatial resolution and sensitivity of two 10-detector-module small-animal PET (r77-miniPET and r106-miniPET), are analyzed and compared to the performance of the 12-detector-module PET scanner miniPET II [1]. All simulations have been performed with the well validated Geant4 Application for Emission Tomography (GATE) [2]. Sensitivity and scatter fraction speak in favor of the 10-module scanner: a clear improvement in count rate and scatter fraction was found. Moreover, steeper slopes of noise equivalent count rate curves at low levels of activity was found. Spatial resolution instead was found to be better in the 12-module scanner. The encouraging results here presented particularly refer to r77-miniPET: all things considered, the 10-detector design behaves better than miniPET II if there are no gaps between detector modules. Preliminary trials performed with 8 detector modules in a ring are even more encouraging and need further assessment.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114888768","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 : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551572
M. Magdics, László Szirmay-Kalos, B. Tóth, Tamás Umenhoffer
In tomography reconstruction, the relationship between the finite-element representation of the objective function and the expected number of hits in detectors - or in other words, the particle transport - is described by the system matrix. With the evolution of high-performance hardware, precise on-the-fly estimation of the system matrix becomes more and more feasible, which allows the use of patient-dependent data and makes it unnecessary to deal with the compression of enormous matrices. On-the-fly system matrix generation requires the online approximation of high dimensional integrals, which is usually attacked by Monte Carlo quadrature and importance sampling. Determining the number of samples used by the estimators belongs to the classical tradeoff problem between accuracy and computational time. However, the approximation error mainly comes from the measurement noise and high frequency components of the measured object that cannot be captured using a given sample density. In this paper, we propose the application of filtered sampling for the forward projection step of iterative ML-EM based PET reconstruction to decrease the variance of the integrand and thus to reduce the error of integral estimation for a given set of samples. The input of the forward projection is filtered using a low-pass filter, which reduces noise and increases the probability that samples do not miss high frequency peaks - e.g. a point source. The iteration thus converges to a modified fixed point, from which the original function can be extracted by applying the same filter. The presented model is built into the TeraTomo™ system.
{"title":"Filtered sampling for PET","authors":"M. Magdics, László Szirmay-Kalos, B. Tóth, Tamás Umenhoffer","doi":"10.1109/NSSMIC.2012.6551572","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551572","url":null,"abstract":"In tomography reconstruction, the relationship between the finite-element representation of the objective function and the expected number of hits in detectors - or in other words, the particle transport - is described by the system matrix. With the evolution of high-performance hardware, precise on-the-fly estimation of the system matrix becomes more and more feasible, which allows the use of patient-dependent data and makes it unnecessary to deal with the compression of enormous matrices. On-the-fly system matrix generation requires the online approximation of high dimensional integrals, which is usually attacked by Monte Carlo quadrature and importance sampling. Determining the number of samples used by the estimators belongs to the classical tradeoff problem between accuracy and computational time. However, the approximation error mainly comes from the measurement noise and high frequency components of the measured object that cannot be captured using a given sample density. In this paper, we propose the application of filtered sampling for the forward projection step of iterative ML-EM based PET reconstruction to decrease the variance of the integrand and thus to reduce the error of integral estimation for a given set of samples. The input of the forward projection is filtered using a low-pass filter, which reduces noise and increases the probability that samples do not miss high frequency peaks - e.g. a point source. The iteration thus converges to a modified fixed point, from which the original function can be extracted by applying the same filter. The presented model is built into the TeraTomo™ system.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"371 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115180783","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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