Pub Date : 1993-10-31DOI: 10.1109/NSSMIC.1993.701863
A. Chugo, K. Ogawa
{"title":"A Proposal Of Accurate Scatter Correction Method Considering Energy Spectra Of Scattered Photons In Single Photon Emission CT","authors":"A. Chugo, K. Ogawa","doi":"10.1109/NSSMIC.1993.701863","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701863","url":null,"abstract":"","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130113152","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.701867
L. Shao, J. Karp, R. Freifelder
Most current energy spectrum based scattering correction techniques in PET suffer from source distribution dependencies. As an alternative method to compensate for these problems, we propose a composite dual energy window (CDW) scattering correction technique, which is based on using the scatter kernels from both the scatter and the photopeak windows. The CDW technique can be broken down to two steps: convolution and energy window correction. In the convolution part, we can obtain the first order scatter projections for both the photopeak and scatter windows by using the calibrated scatter kernels. Then we find the object dependent scatter ratio by dividing the convolution-estimated scatter projections. By this simple division, the overestimation of scatters during convolution is mostly canceled out. In the second step, we simply use the measured scatter profiles in the scatter window and the estimated scatter ratio to obtain the scatter projection in the photopeak window. The CDW technique is evaluated with a Monte Carlo simulation program which simulates the UGM PENN-PET scanner. The results indicate that this technique is better than both the deconvolution-subtraction with one iteration and dual window scattering correction techniques.
{"title":"Composite Dual Window Scattering Correction Technique In PET","authors":"L. Shao, J. Karp, R. Freifelder","doi":"10.1109/NSSMIC.1993.701867","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701867","url":null,"abstract":"Most current energy spectrum based scattering correction techniques in PET suffer from source distribution dependencies. As an alternative method to compensate for these problems, we propose a composite dual energy window (CDW) scattering correction technique, which is based on using the scatter kernels from both the scatter and the photopeak windows. The CDW technique can be broken down to two steps: convolution and energy window correction. In the convolution part, we can obtain the first order scatter projections for both the photopeak and scatter windows by using the calibrated scatter kernels. Then we find the object dependent scatter ratio by dividing the convolution-estimated scatter projections. By this simple division, the overestimation of scatters during convolution is mostly canceled out. In the second step, we simply use the measured scatter profiles in the scatter window and the estimated scatter ratio to obtain the scatter projection in the photopeak window. The CDW technique is evaluated with a Monte Carlo simulation program which simulates the UGM PENN-PET scanner. The results indicate that this technique is better than both the deconvolution-subtraction with one iteration and dual window scattering correction techniques.","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126914261","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373585
H. Haneishi, Y. Miyake
A method for geometrical compensation of distortion of endoscope images is proposed. A model for distortion compensation is built based on a circularly symmetric assumption of distortion, and model parameters are estimated from a distorted image of a grid pattern which consists of several straight lines. Experimental results that demonstrated the effectiveness of this method are shown.<>
{"title":"Distortion compensation of electronic endoscope image","authors":"H. Haneishi, Y. Miyake","doi":"10.1109/NSSMIC.1993.373585","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373585","url":null,"abstract":"A method for geometrical compensation of distortion of endoscope images is proposed. A model for distortion compensation is built based on a circularly symmetric assumption of distortion, and model parameters are estimated from a distorted image of a grid pattern which consists of several straight lines. Experimental results that demonstrated the effectiveness of this method are shown.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131418646","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373624
J. Fessler, A. Hero
The classical expectation-maximization (EM) algorithm for image reconstruction suffers from particularly slow convergence when additive background effects such as accidental coincidences and scatter are included. In addition, when smoothness penalties are included in the objective function, the M-step of the EM algorithm becomes intractable due to parameter coupling. The authors describe the space-alternating generalized EM (SAGE) algorithm, in which the parameters are updated sequentially using a sequence of small "hidden" data spaces rather than one large complete-data space. The sequential update decouples the M-step, so the maximization can typically be performed analytically. By choosing hidden-data spaces with considerably less Fisher information than the conventional complete-data space for Poisson data, the authors obtain significant improvements in convergence rate. This acceleration is due to statistical considerations, not to numerical overrelaxation methods, so monotonic increases in the objective function and global convergence are guaranteed. Due to the space constraints, the authors focus on the unpenalized case in this summary, and they eliminate derivations that are similar to those in Lange and Carson, J. Comput. Assist. Tomography, vol. 8, no. 2, p.306-16 (1984).<>
经典的期望最大化(EM)图像重建算法在考虑意外巧合和散射等附加背景效应时收敛速度特别慢。此外，当目标函数中包含平滑惩罚时，EM算法的m步由于参数耦合而变得难以处理。作者描述了空间交替广义电磁(SAGE)算法，该算法使用一系列小的“隐藏”数据空间而不是一个大的完整数据空间来顺序更新参数。顺序更新解耦了m步，因此通常可以解析地执行最大化。通过为泊松数据选择具有比传统完整数据空间少得多的Fisher信息的隐藏数据空间，作者获得了显著的收敛速度改进。这种加速是由于统计上的考虑，而不是数值上的过度松弛方法，因此保证了目标函数的单调增长和全局收敛。由于篇幅限制，作者在本总结中将重点放在未受处罚的情况上，并删除了与Lange和Carson, J. Comput中类似的推导。协助。断层摄影，第8卷，第8期。2，第306-16页(1984)。
{"title":"New complete-data spaces and faster algorithms for penalized-likelihood emission tomography","authors":"J. Fessler, A. Hero","doi":"10.1109/NSSMIC.1993.373624","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373624","url":null,"abstract":"The classical expectation-maximization (EM) algorithm for image reconstruction suffers from particularly slow convergence when additive background effects such as accidental coincidences and scatter are included. In addition, when smoothness penalties are included in the objective function, the M-step of the EM algorithm becomes intractable due to parameter coupling. The authors describe the space-alternating generalized EM (SAGE) algorithm, in which the parameters are updated sequentially using a sequence of small \"hidden\" data spaces rather than one large complete-data space. The sequential update decouples the M-step, so the maximization can typically be performed analytically. By choosing hidden-data spaces with considerably less Fisher information than the conventional complete-data space for Poisson data, the authors obtain significant improvements in convergence rate. This acceleration is due to statistical considerations, not to numerical overrelaxation methods, so monotonic increases in the objective function and global convergence are guaranteed. Due to the space constraints, the authors focus on the unpenalized case in this summary, and they eliminate derivations that are similar to those in Lange and Carson, J. Comput. Assist. Tomography, vol. 8, no. 2, p.306-16 (1984).<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133010647","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373590
D. McDaniel, B. D. Johnston, D.C. Wack, J.J. Williams
Spatial resolution performance measurements of PET scanners are sensitive to the long tails of the angular distribution of the annihilation radiation, to a degree not previously appreciated. The non-Gaussian nature of the positron range, angular distribution of annihilation radiation, and scatter-induced spatial distribution of scintillator energy deposition prevents simple (e.g. quadrature-based arguments) methods of performance estimation, and requires full numerical convolution of the 3D spatial profiles. The authors have developed a Monte Carlo simulation of 511 keV gamma ray interactions with scintillator crystals to model the spatial distributions obtained in projection measurements of annihilation radiation from point sources. The authors find good agreement between the simulations and experimental results obtained with BGO-based crystals, both for optically-isolated crystals embedded in a crystal matrix, and for a conventional, Anger-based BGO block detector. There is approximately a 0.3 mm difference in the coincidence response function FWHM between 4 mm isolated and Anger crystals which is reproduced by the Monte Carlo calculations.<>
{"title":"Simulation and measurement of spatial resolution in detection of annihilation radiation with BGO crystals","authors":"D. McDaniel, B. D. Johnston, D.C. Wack, J.J. Williams","doi":"10.1109/NSSMIC.1993.373590","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373590","url":null,"abstract":"Spatial resolution performance measurements of PET scanners are sensitive to the long tails of the angular distribution of the annihilation radiation, to a degree not previously appreciated. The non-Gaussian nature of the positron range, angular distribution of annihilation radiation, and scatter-induced spatial distribution of scintillator energy deposition prevents simple (e.g. quadrature-based arguments) methods of performance estimation, and requires full numerical convolution of the 3D spatial profiles. The authors have developed a Monte Carlo simulation of 511 keV gamma ray interactions with scintillator crystals to model the spatial distributions obtained in projection measurements of annihilation radiation from point sources. The authors find good agreement between the simulations and experimental results obtained with BGO-based crystals, both for optically-isolated crystals embedded in a crystal matrix, and for a conventional, Anger-based BGO block detector. There is approximately a 0.3 mm difference in the coincidence response function FWHM between 4 mm isolated and Anger crystals which is reproduced by the Monte Carlo calculations.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"24 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113959732","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.701745
P. Dorenbos, J. D. de Haas, C. V. van Eijk, C. Melcher, J. Schweitzer
The absolute light yield of cerium doped lutetium oxyorthosilicate Lu/sub 2/SiO/sub 5/:Ce/sup 3+/ (LSO:Ce) scintillation crystals is presented. From 60 keV to above 1 MeV the light output increases linearly with the gamma-ray energy and is about 67% of that of NaI(Tl/sup +/). However, a nonlinear response is observed for X-ray energies between 5 and 60 keV. For comparison, we also studied the light yield of a Gd/sub 2/SiO/sub 5/:Ce/sup 3+/ crystal and a CsI:Tl crystal as a function of excitation energy. >
{"title":"Non-linear Response In The Scintillation Yield Of Lu/sub 2/ SiO/sub 5/ O:Ce/sup 3+/","authors":"P. Dorenbos, J. D. de Haas, C. V. van Eijk, C. Melcher, J. Schweitzer","doi":"10.1109/NSSMIC.1993.701745","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701745","url":null,"abstract":"The absolute light yield of cerium doped lutetium oxyorthosilicate Lu/sub 2/SiO/sub 5/:Ce/sup 3+/ (LSO:Ce) scintillation crystals is presented. From 60 keV to above 1 MeV the light output increases linearly with the gamma-ray energy and is about 67% of that of NaI(Tl/sup +/). However, a nonlinear response is observed for X-ray energies between 5 and 60 keV. For comparison, we also studied the light yield of a Gd/sub 2/SiO/sub 5/:Ce/sup 3+/ crystal and a CsI:Tl crystal as a function of excitation energy. >","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"261 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123023528","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373541
M. Bentourkia, P. Msaki, J. Cadorette, R. Lecomte
High resolution images in PET based on small individual detectors are obtained at the cost of poor sensitivity and significant scatter in the detectors. These drawbacks can be partially overcome by acquiring low-energy events and by using more efficient energy-dependent scatter correction methods. The feasibility of multispectral scatter correction was assessed by analyzing projection response functions measured in several energy windows to extract scatter components. While the fraction of well-positioned events drops from 90% in the photopeak region to less than 20% in the lower windows, the detector scatter fraction increases from 5% to 60% in the same range. By independent restoration of the latter component in every energy window, nearly 90% of all detected events can be recovered. Multispectral acquisition, therefore, is a promising approach for recovering sensitivity without loss of resolution in high resolution PET.<>
{"title":"Assessment of scatter components in multispectral PET imaging","authors":"M. Bentourkia, P. Msaki, J. Cadorette, R. Lecomte","doi":"10.1109/NSSMIC.1993.373541","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373541","url":null,"abstract":"High resolution images in PET based on small individual detectors are obtained at the cost of poor sensitivity and significant scatter in the detectors. These drawbacks can be partially overcome by acquiring low-energy events and by using more efficient energy-dependent scatter correction methods. The feasibility of multispectral scatter correction was assessed by analyzing projection response functions measured in several energy windows to extract scatter components. While the fraction of well-positioned events drops from 90% in the photopeak region to less than 20% in the lower windows, the detector scatter fraction increases from 5% to 60% in the same range. By independent restoration of the latter component in every energy window, nearly 90% of all detected events can be recovered. Multispectral acquisition, therefore, is a promising approach for recovering sensitivity without loss of resolution in high resolution PET.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129345930","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373563
Guang Deng, L. Cahill
Gaussian filtering has been intensively studied in image processing and computer vision. Using a Gaussian filter for noise suppression, the noise is smoothed out, at the same time the signal is also distorted. The use of a Gaussian filter as pre-processing for edge detection will also give rise to edge position displacement, edges vanishing, and phantom edges. Here, the authors first review various techniques for these problems. They then propose an adaptive Gaussian filtering algorithm in which the filter variance is adapted to both the noise characteristics and the local variance of the signal.<>
{"title":"An adaptive Gaussian filter for noise reduction and edge detection","authors":"Guang Deng, L. Cahill","doi":"10.1109/NSSMIC.1993.373563","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373563","url":null,"abstract":"Gaussian filtering has been intensively studied in image processing and computer vision. Using a Gaussian filter for noise suppression, the noise is smoothed out, at the same time the signal is also distorted. The use of a Gaussian filter as pre-processing for edge detection will also give rise to edge position displacement, edges vanishing, and phantom edges. Here, the authors first review various techniques for these problems. They then propose an adaptive Gaussian filtering algorithm in which the filter variance is adapted to both the noise characteristics and the local variance of the signal.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128717923","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373561
S. Manglos, T. M. Young
A new method is presented for tomographic image reconstruction, called "Intrinsic Transmission SPECT" or just "IntraSPECT". It simultaneously reconstructs both the attenuation map (/spl mu/) and an attenuation-compensated activity map (A), using only the SPECT projections. A modified ART-algorithm (ART-IntraSPECT) was developed and tested with a simulated thorax. The /spl mu/-image reconstructed with ART-IntraSPECT clearly exhibited all relevant anatomical structure, such as lungs and spine vs soft tissue. However, both A and /spl mu/-images were quantitatively inaccurate. The accuracy was considerably improved by applying reasonable tissue-type constraints to the /spl mu/-image.<>
{"title":"Constrained IntraSPECT reconstruction from SPECT projections","authors":"S. Manglos, T. M. Young","doi":"10.1109/NSSMIC.1993.373561","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373561","url":null,"abstract":"A new method is presented for tomographic image reconstruction, called \"Intrinsic Transmission SPECT\" or just \"IntraSPECT\". It simultaneously reconstructs both the attenuation map (/spl mu/) and an attenuation-compensated activity map (A), using only the SPECT projections. A modified ART-algorithm (ART-IntraSPECT) was developed and tested with a simulated thorax. The /spl mu/-image reconstructed with ART-IntraSPECT clearly exhibited all relevant anatomical structure, such as lungs and spine vs soft tissue. However, both A and /spl mu/-images were quantitatively inaccurate. The accuracy was considerably improved by applying reasonable tissue-type constraints to the /spl mu/-image.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129389906","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 : 1993-10-31DOI: 10.1109/NSSMIC.1993.373565
K. Derby
The author describes the design of a head coil for use in MRI. The current in the coil is distributed over multiple coupled resonators to achieve both high sensitivity and field uniformity over a large volume. This coupled resonator coil had better uniformity than a saddle coil in all directions. Compared to a birdcage coil, it had similar uniformity in transaxial sections near and inferior to center, and better uniformity in transaxial sections superior to center. The coupled resonator coil was more uniform than the birdcage coil in sagittal sections.<>
{"title":"A multiloop coupled resonator coil design for MRI","authors":"K. Derby","doi":"10.1109/NSSMIC.1993.373565","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373565","url":null,"abstract":"The author describes the design of a head coil for use in MRI. The current in the coil is distributed over multiple coupled resonators to achieve both high sensitivity and field uniformity over a large volume. This coupled resonator coil had better uniformity than a saddle coil in all directions. Compared to a birdcage coil, it had similar uniformity in transaxial sections near and inferior to center, and better uniformity in transaxial sections superior to center. The coupled resonator coil was more uniform than the birdcage coil in sagittal sections.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"640 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116412428","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：