Pub Date : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874498
L. Marchini, A. Zappettini, M. Zha, N. Zambelli, A. Bolotnikov, G. Camarda, R. James
Cadmium Zinc Telluride (CZT) is one of the most exploited materials for x-ray and gamma ray radiation detection. Nevertheless CZT ingots are still affected by many defects, the most common features are Te inclusions, dislocations and grain boundaries. In this work the results of many investigation techniques are put together and compared in order to have a better understanding of the role of each defect in the degradation of the detector performances. A CZT ingot grown by low pressure Bridgman technique in IMEM Institute, Parma, was analyzed. The material was studied by means of the IR microscopy, for the identification of Te inclusions and then studied with the use of the synchrotron light source (NSLS National Synchrotron Light Source) for the analysis of the crystalline structure and uniformity of the x-ray response.
碲化镉锌(CZT)是x射线和伽马射线辐射探测中开发最多的材料之一。尽管如此，CZT铸锭仍然存在许多缺陷，最常见的是夹杂物、位错和晶界。在这项工作中，将许多研究技术的结果放在一起并进行比较，以便更好地理解每个缺陷在探测器性能退化中的作用。对帕尔马IMEM研究所用低压布里奇曼法生长的CZT钢锭进行了分析。采用红外显微镜对材料进行了研究，鉴定了Te夹杂物，然后使用同步加速器光源(NSLS National synchrotron light source)对材料进行了晶体结构和x射线响应均匀性分析。
{"title":"Crystal defects and charge collection in CZT x-ray and gamma detectors","authors":"L. Marchini, A. Zappettini, M. Zha, N. Zambelli, A. Bolotnikov, G. Camarda, R. James","doi":"10.1109/NSSMIC.2010.5874498","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874498","url":null,"abstract":"Cadmium Zinc Telluride (CZT) is one of the most exploited materials for x-ray and gamma ray radiation detection. Nevertheless CZT ingots are still affected by many defects, the most common features are Te inclusions, dislocations and grain boundaries. In this work the results of many investigation techniques are put together and compared in order to have a better understanding of the role of each defect in the degradation of the detector performances. A CZT ingot grown by low pressure Bridgman technique in IMEM Institute, Parma, was analyzed. The material was studied by means of the IR microscopy, for the identification of Te inclusions and then studied with the use of the synchrotron light source (NSLS National Synchrotron Light Source) for the analysis of the crystalline structure and uniformity of the x-ray response.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"32 1","pages":"3674-3677"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84414988","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874251
B. Feng, Shikui Yan, Mu Chen, D. Austin, Junjun Deng, R. Mintzer
A previously developed method derives co-registration parameters from PET and CT images of a four-point-source calibration phantom by manually adjusting the offsets and orientation of the CT image to achieve alignment with the PET image in a graphic viewer. This manual process is tedious and can be inaccurate, especially when rotational offsets exist. An automated segmentation method has been developed, based on thresholding and application of constraints on the sizes of point sources in the images. After point sources are identified on PET and CT images, co-registration is performed using an analytic rigid-body registration algorithm which is based on singular value decomposition and minimization of the co-registration error. The co-registration parameters thus derived can then be applied to co-register other PET and CT images from the same system. Twenty PET-CT images of the calibration phantom at various locations and/or orientations were obtained on a Siemens Inveon® Multi-Modality scanner. We tested the use of from 1 to 10 data sets to derive the co-registration parameters, and found that the co-registration accuracy improves with increasing number of data sets until it stabilizes. Co-registration of PET-CT images with an accuracy of 0.33±0.11 mm has been achieved by this method on the Inveon Multi-Modality scanner.
{"title":"Automated least-squares calibration of the coregistration parameters for a micro PET-CT system","authors":"B. Feng, Shikui Yan, Mu Chen, D. Austin, Junjun Deng, R. Mintzer","doi":"10.1109/NSSMIC.2010.5874251","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874251","url":null,"abstract":"A previously developed method derives co-registration parameters from PET and CT images of a four-point-source calibration phantom by manually adjusting the offsets and orientation of the CT image to achieve alignment with the PET image in a graphic viewer. This manual process is tedious and can be inaccurate, especially when rotational offsets exist. An automated segmentation method has been developed, based on thresholding and application of constraints on the sizes of point sources in the images. After point sources are identified on PET and CT images, co-registration is performed using an analytic rigid-body registration algorithm which is based on singular value decomposition and minimization of the co-registration error. The co-registration parameters thus derived can then be applied to co-register other PET and CT images from the same system. Twenty PET-CT images of the calibration phantom at various locations and/or orientations were obtained on a Siemens Inveon® Multi-Modality scanner. We tested the use of from 1 to 10 data sets to derive the co-registration parameters, and found that the co-registration accuracy improves with increasing number of data sets until it stabilizes. Co-registration of PET-CT images with an accuracy of 0.33±0.11 mm has been achieved by this method on the Inveon Multi-Modality scanner.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"39 1","pages":"2568-2572"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85059926","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874378
Hongdi Li, Chao Wang, S. An, H. Baghaei, Yuxuan Zhang, Shitao Liu, R. Ramirez, W. Wong
Photo-sensor sharing (multiple blocks or crystals) can achieve high-resolution position-sensitive detectors but it also increases the dead time and pileups for scintillation event detection. Several methods such as pulse-clipping and HYPER (high-yield-pileup-event-recovery) have been introduced to minimize the dead time and pileups with a trade-off of less scintillation light collection. However, collecting smaller number photoelectrons would increase the statistical error, which in a turn will decrease the decoding resolution. In this study, instead of applying the HYPER method to 3 Anger-signal (X, Y and E) simultaneously, we use an individual dynamic approach for each photo-sensor to maximize the scintillation light collection while it still has a capability of rejecting pileups. The photo-electron collection for one photo-sensor involving a current event decoding will not be disturbed until a new event is detected that also requires this photo-sensor for position-decoding. If a new event comes from an adjacent detector block only sharing one photo-sensor currently involving the previous event decoding, it may only disturb the light collection of this sharing photo-senor; hence only one photo-sensor creates a poor statistical error and the rest photo-sensors can still collect a large number of photo electrons with good statistics for the previous event to achieve a good decoding resolution. This paper compares the decoding results using pulse clipping and this new proposed fully dynamic approach at various count-rates for a regular position-sensitive block detector and a PMT-quadrant-sharing (PQS) block detector. To study the decoding resolution at various high count-rates, a pulse waveform library was built by recording a large number of pulses by a digital oscilloscope from a detector test-bench at a low count-rate first and then boost to different high count-rates by software generated Poisson event time sequence. The result shows this fully dynamic approach reduces the dead space of PQS detectors by x2.25 without increasing the statistical noise.
{"title":"Improvement of dead time and decoding resolution for position-sensitive detectors using a fully dynamic approach of light collection","authors":"Hongdi Li, Chao Wang, S. An, H. Baghaei, Yuxuan Zhang, Shitao Liu, R. Ramirez, W. Wong","doi":"10.1109/NSSMIC.2010.5874378","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874378","url":null,"abstract":"Photo-sensor sharing (multiple blocks or crystals) can achieve high-resolution position-sensitive detectors but it also increases the dead time and pileups for scintillation event detection. Several methods such as pulse-clipping and HYPER (high-yield-pileup-event-recovery) have been introduced to minimize the dead time and pileups with a trade-off of less scintillation light collection. However, collecting smaller number photoelectrons would increase the statistical error, which in a turn will decrease the decoding resolution. In this study, instead of applying the HYPER method to 3 Anger-signal (X, Y and E) simultaneously, we use an individual dynamic approach for each photo-sensor to maximize the scintillation light collection while it still has a capability of rejecting pileups. The photo-electron collection for one photo-sensor involving a current event decoding will not be disturbed until a new event is detected that also requires this photo-sensor for position-decoding. If a new event comes from an adjacent detector block only sharing one photo-sensor currently involving the previous event decoding, it may only disturb the light collection of this sharing photo-senor; hence only one photo-sensor creates a poor statistical error and the rest photo-sensors can still collect a large number of photo electrons with good statistics for the previous event to achieve a good decoding resolution. This paper compares the decoding results using pulse clipping and this new proposed fully dynamic approach at various count-rates for a regular position-sensitive block detector and a PMT-quadrant-sharing (PQS) block detector. To study the decoding resolution at various high count-rates, a pulse waveform library was built by recording a large number of pulses by a digital oscilloscope from a detector test-bench at a low count-rate first and then boost to different high count-rates by software generated Poisson event time sequence. The result shows this fully dynamic approach reduces the dead space of PQS detectors by x2.25 without increasing the statistical noise.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"12 1","pages":"3133-3136"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85212369","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874368
F. Beekman, D. Schaart, H. T. van Dam, S. Seifert, R. Vinke, P. Dendooven, H. Lohner
Several improvements of the k-nearest neighbor (k-NN) method for the determination of the entry point (x, y) of a gamma photon in a monolithic scintillator PET detector have been investigated with the aim to obtain better spatial resolution and/or to enable faster detector calibration by reducing the amount of required reference data and by allowing for calibrating with a line source. These methods were tested on a dataset measured with a SiPM-array-based monolithic LYSO detector. It appears that ∼10% to ∼25% better spatial resolution can be obtained compared to the standard approach. Moreover, some of the improved methods using two orders of magnitude less reference data, yield essentially the same spatial resolution as the standard method, which reduces the time needed for calibration as well as entry point computation. Finally, line source calibration is shown to be possible with some of the methods, yielding better results than the standard method and allowing much faster and easier collection of the reference data.
{"title":"An improved nearest neighbor method for the estimation of the gamma photon entry point in monolithic scintillator detectors for PET","authors":"F. Beekman, D. Schaart, H. T. van Dam, S. Seifert, R. Vinke, P. Dendooven, H. Lohner","doi":"10.1109/NSSMIC.2010.5874368","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874368","url":null,"abstract":"Several improvements of the k-nearest neighbor (k-NN) method for the determination of the entry point (x, y) of a gamma photon in a monolithic scintillator PET detector have been investigated with the aim to obtain better spatial resolution and/or to enable faster detector calibration by reducing the amount of required reference data and by allowing for calibrating with a line source. These methods were tested on a dataset measured with a SiPM-array-based monolithic LYSO detector. It appears that ∼10% to ∼25% better spatial resolution can be obtained compared to the standard approach. Moreover, some of the improved methods using two orders of magnitude less reference data, yield essentially the same spatial resolution as the standard method, which reduces the time needed for calibration as well as entry point computation. Finally, line source calibration is shown to be possible with some of the methods, yielding better results than the standard method and allowing much faster and easier collection of the reference data.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"6 1","pages":"3088-3092"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85237084","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873952
O. Rubsamen, U. Pietsch, H. Schenk, A. Walenta
A simulation software has been developed to predict the spatial resolution of a gas detector for x-ray applications, including the range of photoelectrons, fluorescence photons and Auger electrons as well as the broadening by diffusion in the gas mixture. Gas properties (drift velocity, characteristic energy, diffusion) are evaluated over a wide range of the reduced field (0–2) kV/(cm∗ bar) by a Monte Carlo approach. Possible mixtures to be simulated are (Ar, Kr or Xe) + CH4 in any proportion. Results of the properties for common gas mixtures as measured are shown to be in good agreement with the calculated results.
{"title":"Simulation of gas properties in various mixtures for high resolution position sensitive gas detectors","authors":"O. Rubsamen, U. Pietsch, H. Schenk, A. Walenta","doi":"10.1109/NSSMIC.2010.5873952","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5873952","url":null,"abstract":"A simulation software has been developed to predict the spatial resolution of a gas detector for x-ray applications, including the range of photoelectrons, fluorescence photons and Auger electrons as well as the broadening by diffusion in the gas mixture. Gas properties (drift velocity, characteristic energy, diffusion) are evaluated over a wide range of the reduced field (0–2) kV/(cm∗ bar) by a Monte Carlo approach. Possible mixtures to be simulated are (Ar, Kr or Xe) + CH4 in any proportion. Results of the properties for common gas mixtures as measured are shown to be in good agreement with the calculated results.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"107 1","pages":"1173-1177"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85588928","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874299
J. Dey
SPECT is primarily used in the clinic for cardiac myocardial perfusion imaging (MPI). However, for SPECT, sensitivity is impaired due to the need for collimation. System resolution is poor as well. In this work we demonstrate the advantages of curved detector over a flat detector on a pinhole for cardiac applications using ray-tracing simulations and comparing to independently obtained theoretical derivations. For the flat detector we use parameters close to what we would expect the new multi-pinhole GE Discovery system. We show that using a paraboloid detector we can obtain sensitivity gains as much as ∼2.25 for similar resolutions as a flat detector by opening the pinhole diameter more or we could obtain a better resolution system (∼30% better on the average) by keeping same pinhole opening. Thus far we compared the effect of pinhole and have not included the intrinsic resolution yet.
{"title":"High performance cardiac SPECT camera: Resolution and sensitivity simulations","authors":"J. Dey","doi":"10.1109/NSSMIC.2010.5874299","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874299","url":null,"abstract":"SPECT is primarily used in the clinic for cardiac myocardial perfusion imaging (MPI). However, for SPECT, sensitivity is impaired due to the need for collimation. System resolution is poor as well. In this work we demonstrate the advantages of curved detector over a flat detector on a pinhole for cardiac applications using ray-tracing simulations and comparing to independently obtained theoretical derivations. For the flat detector we use parameters close to what we would expect the new multi-pinhole GE Discovery system. We show that using a paraboloid detector we can obtain sensitivity gains as much as ∼2.25 for similar resolutions as a flat detector by opening the pinhole diameter more or we could obtain a better resolution system (∼30% better on the average) by keeping same pinhole opening. Thus far we compared the effect of pinhole and have not included the intrinsic resolution yet.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"11 1","pages":"2777-2787"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85875286","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874179
E. Hansis, J. Bredno, D. Sowards-Emmerd, L. Shao
Circular cone-beam computed tomography (CBCT) with a tangentially offset flat-panel X-ray detector offers a large CT field-of-view (FoV) with a relatively small detector. It is used in practice, e.g., for target imaging in image-guided radiotherapy or for localization and attenuation correction in SPECT/CT imaging. The X-ray projections, acquired on a circular source trajectory, each cover roughly half the CT FoV; a central overlap region is imaged by all projections. Offset-detector CBCT reconstruction requires special algorithms. For large detector offsets, previously proposed filtered-backprojection methods can lead to shading artifacts, specifically left/right intensity imbalance. Here, we propose using iterative reconstruction for offset-detector CBCT. To handle the special acquisition geometry, known iterative reconstruction algorithms are modified in terms of axial truncation compensation, redundancy weighting, and algorithm initialization. An efficient implementation using a graphics processing unit (GPU) delivers clinically feasible reconstruction times. Results from patient and phantom studies are presented, showing a clear reduction of artifacts and improvement in image quality.
{"title":"Iterative reconstruction for circular cone-beam CT with an offset flat-panel detector","authors":"E. Hansis, J. Bredno, D. Sowards-Emmerd, L. Shao","doi":"10.1109/NSSMIC.2010.5874179","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874179","url":null,"abstract":"Circular cone-beam computed tomography (CBCT) with a tangentially offset flat-panel X-ray detector offers a large CT field-of-view (FoV) with a relatively small detector. It is used in practice, e.g., for target imaging in image-guided radiotherapy or for localization and attenuation correction in SPECT/CT imaging. The X-ray projections, acquired on a circular source trajectory, each cover roughly half the CT FoV; a central overlap region is imaged by all projections. Offset-detector CBCT reconstruction requires special algorithms. For large detector offsets, previously proposed filtered-backprojection methods can lead to shading artifacts, specifically left/right intensity imbalance. Here, we propose using iterative reconstruction for offset-detector CBCT. To handle the special acquisition geometry, known iterative reconstruction algorithms are modified in terms of axial truncation compensation, redundancy weighting, and algorithm initialization. An efficient implementation using a graphics processing unit (GPU) delivers clinically feasible reconstruction times. Results from patient and phantom studies are presented, showing a clear reduction of artifacts and improvement in image quality.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"4 1","pages":"2228-2231"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86016212","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874222
J. Scheins, L. Tellmann, C. Weirich, E. R. Kops, H. Herzog
Fully 3D PET image reconstruction for large detector systems still remains a challenging computational task due to the tremendous number of Lines-of-Response. The reconstruction software PRESTO (PET REconstruction Software TOolkit) allows to use accurate geometrical weighting schemes for the forward/backward projection, e.g. Volume-of-Intersection, while using all measured LORs separately. PRESTO exploits matrix redundancies to realise a strongly compressed, memory-resident system matrix. In this way, the needed time to calculate matrix weights no longer influences the reconstruction time. Nevertheless, in the first implementation the addressing of matrix weights, projection values and voxel values in disfavoured memory access patterns caused severe computational inefficiencies due to the limited memory bandwidth. In this work, the image data and projection data in memory as well as the order of mathematical operations have been re-organised to provide an optimal merit for the Single Instruction Multiple Data (SIMD) approach. A global speedup factor of 15 for has been achieved while obtaining identical results.
{"title":"Ultra fast 3-D PET image reconstruction using highly compressed, memory-resident system matrices with optimised SIMD access patterns","authors":"J. Scheins, L. Tellmann, C. Weirich, E. R. Kops, H. Herzog","doi":"10.1109/NSSMIC.2010.5874222","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874222","url":null,"abstract":"Fully 3D PET image reconstruction for large detector systems still remains a challenging computational task due to the tremendous number of Lines-of-Response. The reconstruction software PRESTO (PET REconstruction Software TOolkit) allows to use accurate geometrical weighting schemes for the forward/backward projection, e.g. Volume-of-Intersection, while using all measured LORs separately. PRESTO exploits matrix redundancies to realise a strongly compressed, memory-resident system matrix. In this way, the needed time to calculate matrix weights no longer influences the reconstruction time. Nevertheless, in the first implementation the addressing of matrix weights, projection values and voxel values in disfavoured memory access patterns caused severe computational inefficiencies due to the limited memory bandwidth. In this work, the image data and projection data in memory as well as the order of mathematical operations have been re-organised to provide an optimal merit for the Single Instruction Multiple Data (SIMD) approach. A global speedup factor of 15 for has been achieved while obtaining identical results.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"9 1","pages":"2420-2422"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76818478","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5874342
J. Verhaeghe, P. Gravel, A. Reader
Task-based selection of image reconstruction methodology in emission tomography is a critically important step when designing a PET protocol. This work concerns optimizing performance for a range of quantification tasks: finding the radioactivity concentration for different sizes of region of interest (ROI) and different group sizes. It is shown that there is a tremendous impact of ROI and group size on the quantitative performance of different algorithms which should be considered when selecting reconstruction parameters. Therefore, a study-specific and space-variant selection rule is proposed that selects a close to optimal estimate from a series of parameter estimates obtained by filtered backprojection (FBP) and different OSEM reconstructions. The optimality criterion is to minimize the approximative mean squared error (MSE), which is estimated from the limited data at hand (single- or multi-subject) using the bootstrap resampling technique. The proposed approach is appropriate for single voxel estimates and ROI estimates in single-and multi-subject studies. An extensive multi-try simulation study using a 2D numerical phantom and relevant count levels shows that the proposed selection rule can produce quantitative estimates that are close to the estimates that minimise the true MSE (that can only normally be obtained from many independent Monte-Carlo realisations with knowledge of the ground truth). This indicates that with the selection rule a truly task-based quantitative parameter estimation is possible not only avoiding the critical step of specifying reconstruction parameters such as OSEM iteration number or the choice between FBP and OSEM, but also providing a close to optimal estimate of the parameter.
{"title":"Quantification task-optimized estimates from OSEM and FBP reconstructions in single- and multi-subject studies","authors":"J. Verhaeghe, P. Gravel, A. Reader","doi":"10.1109/NSSMIC.2010.5874342","DOIUrl":"https://doi.org/10.1109/NSSMIC.2010.5874342","url":null,"abstract":"Task-based selection of image reconstruction methodology in emission tomography is a critically important step when designing a PET protocol. This work concerns optimizing performance for a range of quantification tasks: finding the radioactivity concentration for different sizes of region of interest (ROI) and different group sizes. It is shown that there is a tremendous impact of ROI and group size on the quantitative performance of different algorithms which should be considered when selecting reconstruction parameters. Therefore, a study-specific and space-variant selection rule is proposed that selects a close to optimal estimate from a series of parameter estimates obtained by filtered backprojection (FBP) and different OSEM reconstructions. The optimality criterion is to minimize the approximative mean squared error (MSE), which is estimated from the limited data at hand (single- or multi-subject) using the bootstrap resampling technique. The proposed approach is appropriate for single voxel estimates and ROI estimates in single-and multi-subject studies. An extensive multi-try simulation study using a 2D numerical phantom and relevant count levels shows that the proposed selection rule can produce quantitative estimates that are close to the estimates that minimise the true MSE (that can only normally be obtained from many independent Monte-Carlo realisations with knowledge of the ground truth). This indicates that with the selection rule a truly task-based quantitative parameter estimation is possible not only avoiding the critical step of specifying reconstruction parameters such as OSEM iteration number or the choice between FBP and OSEM, but also providing a close to optimal estimate of the parameter.","PeriodicalId":13048,"journal":{"name":"IEEE Nuclear Science Symposuim & Medical Imaging Conference","volume":"25 1","pages":"2977-2981"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76930761","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 : 2010-10-01DOI: 10.1109/NSSMIC.2010.5873987
A. Pullia, F. Zocca, M. Citterio
We studied the feasibility of monolithic silicon-germanium front-ends for cryogenic semiconductor detectors. In this framework we designed and simulated a low-noise Charge Sensitive Preamplifier for High Purity Germanium detectors using the Austria Micro System S35 silicon-germanium technology. The preamplifier uses two silicon-germanium Hetero-junction Bipolar Transistors, a few silicon Metal-Oxide-Silicon Field-Effect Transistors, and an external silicon Junction Field-Effect Transistor. It is designed for gamma-ray spectroscopy performance at liquid-argon temperature, and exploits the full functionality at cryogenic temperatures of silicon-germanium Bipolar Transistors. Single-channel and four-channel versions are being realized.
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