Pub Date : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352652
H. Takahashi, N. Shaaban, Q.W. Wang, J. Yeom, M. Nakazawa
Signal processing for compound semiconductor detectors is one of the main issues for expanding use of moderate grade detectors. Although a peak performance is obtained for the best detector, depending on the process difficulty, many detectors are classified into counter grade or less. If optimum signal processing for such moderate grade detectors is developed, compound semiconductor detectors can be applied to many different fields in radiation measurements. We have taken a very flexible digitizing approach to achieve this aim and now we are trying to develop a dedicated ASIC which includes multiple preamplifiers, variable gain amplifiers, and fast digitizers in one chip. Genetic algorithm is an adaptive optimization technique which can be used in many fields. In this paper we describe an adaptive signal processing method with genetic algorithm for a fast digitizer ASIC.
{"title":"Adaptive signal processing with genetic algorithm optimum filter for fast digitizer ASIC","authors":"H. Takahashi, N. Shaaban, Q.W. Wang, J. Yeom, M. Nakazawa","doi":"10.1109/NSSMIC.2003.1352652","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352652","url":null,"abstract":"Signal processing for compound semiconductor detectors is one of the main issues for expanding use of moderate grade detectors. Although a peak performance is obtained for the best detector, depending on the process difficulty, many detectors are classified into counter grade or less. If optimum signal processing for such moderate grade detectors is developed, compound semiconductor detectors can be applied to many different fields in radiation measurements. We have taken a very flexible digitizing approach to achieve this aim and now we are trying to develop a dedicated ASIC which includes multiple preamplifiers, variable gain amplifiers, and fast digitizers in one chip. Genetic algorithm is an adaptive optimization technique which can be used in many fields. In this paper we describe an adaptive signal processing method with genetic algorithm for a fast digitizer ASIC.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114934859","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1351875
K. Borozdin, G. Hogan, C. Morris, W. Priedhorsky, A. Saunders, L. Schultz, M. E. Teasdale
We have proposed a new method for nuclear material contraband detection based on cosmic ray muon radiography. The method is safe, because it does not include the generation of any artificial radiation, but uses naturally produced high-energy muons. Results obtained with our prototype experiment, and from simulations demonstrate the feasibility of the method for the detection of high-Z materials hidden inside different types of ordinary cargo. Detector technology for muon detection is mature and enables cost-effective design for a muon radiography apparatus. Image reconstruction is not trivial and may be done in various ways. We developed the PoCA algorithm for image reconstruction and the MC (muon crossing) algorithm for the detection of high-Z material. Our simulations of a full-scale muon radiography system suggest high efficiency of detection in 1 minute of exposure with a low number of false positives for a 20 kg of uranium hidden inside 11 tons of uniformly distributed iron.
{"title":"Scattering muon radiography and its application to the detection of high-Z materials","authors":"K. Borozdin, G. Hogan, C. Morris, W. Priedhorsky, A. Saunders, L. Schultz, M. E. Teasdale","doi":"10.1109/NSSMIC.2003.1351875","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1351875","url":null,"abstract":"We have proposed a new method for nuclear material contraband detection based on cosmic ray muon radiography. The method is safe, because it does not include the generation of any artificial radiation, but uses naturally produced high-energy muons. Results obtained with our prototype experiment, and from simulations demonstrate the feasibility of the method for the detection of high-Z materials hidden inside different types of ordinary cargo. Detector technology for muon detection is mature and enables cost-effective design for a muon radiography apparatus. Image reconstruction is not trivial and may be done in various ways. We developed the PoCA algorithm for image reconstruction and the MC (muon crossing) algorithm for the detection of high-Z material. Our simulations of a full-scale muon radiography system suggest high efficiency of detection in 1 minute of exposure with a low number of false positives for a 20 kg of uranium hidden inside 11 tons of uniformly distributed iron.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122902251","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352487
Yu. Chin-Lung, Sung-Cheng Huang, M. Dahlbom, M. Bergsneider
Subject movement leads to misalignment between transmission and emission PET scans acquired at different times. This leads to inaccurate attenuation correction and causes errors in PET images. We propose a new method, which seeks to minimize the variance of the total counts of attenuation corrected emission sinogram among all projection angles. The underlying basis of the method is that if the transmission and emission scans are aligned, the total counts (after attenuation correction) at different projection angles should be equal (i.e., with zero variance). Therefore, by adjusting the spatial transformation parameters between the transmission and emission images to minimize such a variance as a cost function, the two scans would be aligned. The effectiveness of this method is demonstrated in two-dimensional situations with computer simulated data and with a physical phantom PET study.
{"title":"Alignment of transmission and emission scans of PET to correct for subject movement using a sinogram consistency criterion","authors":"Yu. Chin-Lung, Sung-Cheng Huang, M. Dahlbom, M. Bergsneider","doi":"10.1109/NSSMIC.2003.1352487","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352487","url":null,"abstract":"Subject movement leads to misalignment between transmission and emission PET scans acquired at different times. This leads to inaccurate attenuation correction and causes errors in PET images. We propose a new method, which seeks to minimize the variance of the total counts of attenuation corrected emission sinogram among all projection angles. The underlying basis of the method is that if the transmission and emission scans are aligned, the total counts (after attenuation correction) at different projection angles should be equal (i.e., with zero variance). Therefore, by adjusting the spatial transformation parameters between the transmission and emission images to minimize such a variance as a cost function, the two scans would be aligned. The effectiveness of this method is demonstrated in two-dimensional situations with computer simulated data and with a physical phantom PET study.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129732552","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352426
M. Magadán-Méndez, A. Kivimáki, U. Ruotsalainen
The aim of this study was to improve detection of different heart tissues, and specially their boundaries, in H/sub 2//sup 1 5/O PET (positron emission tomography) heart images. This problem was considered as a blind source separation problem. In order to solve it we applied ICA (independent component analysis) on dynamic image data and measured projection profiles (sinograms). The testing was based on two kinds of data: a simple dynamic numerical phantom and human heart data acquired during resting state. The sensitivity of ICA to noise was examined on phantom data, where ICA seemed to be less sensitive to noise on sinogram data than on image data. On cardiac rest data, the results were in line with the results on phantom data.
{"title":"ICA separation of functional components from dynamic cardiac PET data","authors":"M. Magadán-Méndez, A. Kivimáki, U. Ruotsalainen","doi":"10.1109/NSSMIC.2003.1352426","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352426","url":null,"abstract":"The aim of this study was to improve detection of different heart tissues, and specially their boundaries, in H/sub 2//sup 1 5/O PET (positron emission tomography) heart images. This problem was considered as a blind source separation problem. In order to solve it we applied ICA (independent component analysis) on dynamic image data and measured projection profiles (sinograms). The testing was based on two kinds of data: a simple dynamic numerical phantom and human heart data acquired during resting state. The sensitivity of ICA to noise was examined on phantom data, where ICA seemed to be less sensitive to noise on sinogram data than on image data. On cardiac rest data, the results were in line with the results on phantom data.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128304360","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}
G. Gullberg, R. Huesman, D. G. Ghosh Roy, J. Qi, B. Reutter
In dynamic cardiac SPECT estimates of kinetic parameters of a one-compartment perfusion model are usually obtained in a two step process: 1) first a MAP iterative algorithm, which properly models the Poisson statistics and the physics of the data acquisition, reconstructs a sequence of dynamic reconstructions, 2) then kinetic parameters are estimated from time activity curves generated from the dynamic reconstructions. This paper provides a method for calculating the covariance matrix of the kinetic parameters, which are determined using weighted least squares fitting that incorporates the estimated variance and covariance of the dynamic reconstructions. Sequential tomographic projections are reconstructed into a sequence of transaxial reconstructions for each transaxial slice using for each reconstruction in the time sequence the fixed-point solution to the MAP reconstruction. Time-activity curves for a sum of activity in a blood region inside the left ventricle and a sum in a cardiac tissue region, for the variance of the two estimates of the sum, and for the covariance between the two ROI estimates are generated at convergence. A one-compartment model is fit to the tissue activity curves assuming a noisy blood input function to give weighted least squares estimates of blood volume fraction, wash-in and wash-out rate constants specifying the kinetics for the left ventricular myocardium. Numerical methods are used to calculate the second derivative of the chi-square criterion to obtain estimates of the covariance matrix for the weighted least square parameter estimates. Even though the method requires one matrix inverse for each time interval of tomographic acquisition, efficient estimates of the tissue kinetic parameters in a dynamic cardiac SPECT study can be obtained with present day desk-top computers.
{"title":"Estimation of the parameter covariance matrix for a one-compartment cardiac perfusion model estimated from a dynamic sequence reconstructed using MAP iterative reconstruction algorithms","authors":"G. Gullberg, R. Huesman, D. G. Ghosh Roy, J. Qi, B. Reutter","doi":"10.2172/928329","DOIUrl":"https://doi.org/10.2172/928329","url":null,"abstract":"In dynamic cardiac SPECT estimates of kinetic parameters of a one-compartment perfusion model are usually obtained in a two step process: 1) first a MAP iterative algorithm, which properly models the Poisson statistics and the physics of the data acquisition, reconstructs a sequence of dynamic reconstructions, 2) then kinetic parameters are estimated from time activity curves generated from the dynamic reconstructions. This paper provides a method for calculating the covariance matrix of the kinetic parameters, which are determined using weighted least squares fitting that incorporates the estimated variance and covariance of the dynamic reconstructions. Sequential tomographic projections are reconstructed into a sequence of transaxial reconstructions for each transaxial slice using for each reconstruction in the time sequence the fixed-point solution to the MAP reconstruction. Time-activity curves for a sum of activity in a blood region inside the left ventricle and a sum in a cardiac tissue region, for the variance of the two estimates of the sum, and for the covariance between the two ROI estimates are generated at convergence. A one-compartment model is fit to the tissue activity curves assuming a noisy blood input function to give weighted least squares estimates of blood volume fraction, wash-in and wash-out rate constants specifying the kinetics for the left ventricular myocardium. Numerical methods are used to calculate the second derivative of the chi-square criterion to obtain estimates of the covariance matrix for the weighted least square parameter estimates. Even though the method requires one matrix inverse for each time interval of tomographic acquisition, efficient estimates of the tissue kinetic parameters in a dynamic cardiac SPECT study can be obtained with present day desk-top computers.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128501927","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352402
C. Groiselle, Y. D’Asseler, H. Gifford, S. Glick
This study investigated whether list-mode PET data generated using the bootstrap method can be used to predict lesion detectability as assessed by the channelized Hotelling observer (CHO). A Monte-Carlo simulator was used to generate 2D PET list-mode data set acquisitions of a disk object. One of these list-mode sets was then used to create an ensemble of bootstrap list-mode sets. A randomly positioned signal (lesion) was introduced into half of the list-mode sets to create an ensemble of signal-present and signal-absent list-mode sets. These sets were then reconstructed using the OSEM list-mode algorithm. The CHO was computed from the ensemble of reconstructed images generated from the bootstrap data sets as well as from independent noisy data sets. The F-test and the student t-test found no significant difference (confidence level 5%) in the areas under the LROC curve generated using the independent noisy list-mode sets and the bootstrap list-mode sets for clinical count levels. It is also shown how bootstrap images can be used to implement a patient-specific, CHO-based stopping-rule criterion for ordered-subset expectation-maximization (OSEM) list-mode iterative reconstruction. An example of applying the CHO-based stopping-rule criterion for list-mode reconstruction of the MCAT phantom showed an optimal detectability index at iterations 7 using 2 subsets respectively. Results from this study suggest that the bootstrap approach can be used to conduct numerical observer studies with more realistic backgrounds by generating them from a patient study (with the introduction of simulated lesions), and allows the possibility of applying a patient-specific, CHO-based stopping-rule criterion for list-mode iterative reconstruction.
{"title":"Performance evaluation of the channelized Hotelling observer using bootstrap list-mode PET studies","authors":"C. Groiselle, Y. D’Asseler, H. Gifford, S. Glick","doi":"10.1109/NSSMIC.2003.1352402","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352402","url":null,"abstract":"This study investigated whether list-mode PET data generated using the bootstrap method can be used to predict lesion detectability as assessed by the channelized Hotelling observer (CHO). A Monte-Carlo simulator was used to generate 2D PET list-mode data set acquisitions of a disk object. One of these list-mode sets was then used to create an ensemble of bootstrap list-mode sets. A randomly positioned signal (lesion) was introduced into half of the list-mode sets to create an ensemble of signal-present and signal-absent list-mode sets. These sets were then reconstructed using the OSEM list-mode algorithm. The CHO was computed from the ensemble of reconstructed images generated from the bootstrap data sets as well as from independent noisy data sets. The F-test and the student t-test found no significant difference (confidence level 5%) in the areas under the LROC curve generated using the independent noisy list-mode sets and the bootstrap list-mode sets for clinical count levels. It is also shown how bootstrap images can be used to implement a patient-specific, CHO-based stopping-rule criterion for ordered-subset expectation-maximization (OSEM) list-mode iterative reconstruction. An example of applying the CHO-based stopping-rule criterion for list-mode reconstruction of the MCAT phantom showed an optimal detectability index at iterations 7 using 2 subsets respectively. Results from this study suggest that the bootstrap approach can be used to conduct numerical observer studies with more realistic backgrounds by generating them from a patient study (with the introduction of simulated lesions), and allows the possibility of applying a patient-specific, CHO-based stopping-rule criterion for list-mode iterative reconstruction.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128359727","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1351961
K. H. Kim, G. Cho
In this paper, we presented the effect of direct X-ray after scintillator on the CMOS APS imager using modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). 50 kVp of X-ray tube voltage at the SID of 300 mm were set with continuous made micro-focus X-ray machine on the assumption for industrial application such as PCB inspection. Lanex screen coupled CMOS APS imager was irradiated for long-term. From the experimental results, MTF and also DQE were degraded exponentially because of reduction of dynamic range caused by dark current or dark signal increase. For a given scintillator and an exposure condition, the degradation of image performance can be expected in case that the CMOS APS be used as a basic sensor array.
{"title":"The effect of direct x-ray on CMOS APS imager for industrial application","authors":"K. H. Kim, G. Cho","doi":"10.1109/NSSMIC.2003.1351961","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1351961","url":null,"abstract":"In this paper, we presented the effect of direct X-ray after scintillator on the CMOS APS imager using modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). 50 kVp of X-ray tube voltage at the SID of 300 mm were set with continuous made micro-focus X-ray machine on the assumption for industrial application such as PCB inspection. Lanex screen coupled CMOS APS imager was irradiated for long-term. From the experimental results, MTF and also DQE were degraded exponentially because of reduction of dynamic range caused by dark current or dark signal increase. For a given scintillator and an exposure condition, the degradation of image performance can be expected in case that the CMOS APS be used as a basic sensor array.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"02 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128618139","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352680
G. Jellison
It is well-known that internal electric fields can alter the refractive index of certain materials via the Pockels effect. Using the traditional crossed polarizer configuration, this effect has been used to explore internal electric fields in several materials of interest as potential room temperature nuclear detectors. Recently we have shown that the two-modulator generalized ellipsometer (2-MGE) can be configured in the transmission mode, where it measures the retardation, the direction of the principal axis, the diattenuation, and the polarization factor. Therefore, the transmission 2-MGE provides more information and is more accurate than the crossed polarizer configuration. Utilizing various optical schemes, one can sequentially "map" these parameters for a sample. Examples of electric-field-induced birefringence are presented for crystals of LiNbO/sub 3/ and CZT.
{"title":"Electric field-induced birefringence measurements in nuclear detector materials using transmission two-modulator generalized ellipsometry (2-MGE)","authors":"G. Jellison","doi":"10.1109/NSSMIC.2003.1352680","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352680","url":null,"abstract":"It is well-known that internal electric fields can alter the refractive index of certain materials via the Pockels effect. Using the traditional crossed polarizer configuration, this effect has been used to explore internal electric fields in several materials of interest as potential room temperature nuclear detectors. Recently we have shown that the two-modulator generalized ellipsometer (2-MGE) can be configured in the transmission mode, where it measures the retardation, the direction of the principal axis, the diattenuation, and the polarization factor. Therefore, the transmission 2-MGE provides more information and is more accurate than the crossed polarizer configuration. Utilizing various optical schemes, one can sequentially \"map\" these parameters for a sample. Examples of electric-field-induced birefringence are presented for crystals of LiNbO/sub 3/ and CZT.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124572700","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}
The main objective of this work is to evaluate the absorbed doses in the fingers of PET physicians derived from the administration of /sup 18/FDG, using the Geant3 Monte Carlo code. A comparison is made with data obtained with thermoluminiscent dosimeters. The administration of a PET radiopharmaceutical such as /sup 18/FDG presents a radiation hazard to the hands and fingers. One motivation for this study is the increased use of PET imaging in nuclear medicine that was not followed by a parallel development in the respective dose measurements and optimisation. Considering a workload of 10 patients per week, each medical doctor receives finger doses 3 times lower than the weekly skin dose limit with the fingers in the active volume and 10 times lower if they are in the rear end of the syringe. In the calculations it is assumed that a typical administered activity is 0.185 GBq with a finger-syringe contact time of 10 s. Monte Carlo calculations were performed for different kinds of syringes and different injected volumes. We have also calculated finger doses as a function of the wall thickness for three kinds of wall materials. Results show a slight dose reduction when the polypropylene syringe is replaced by a pyrex one and could be used to derive guidelines for the handling of syringes containing the most used PET radiopharmaceuticals.
{"title":"Finger doses received during /sup 18/FDG injections calculated with Monte Carlo simulations","authors":"C. Cordeiro, A. Maio, L. González, A. Gomes","doi":"10.1109/TNS.2004.832574","DOIUrl":"https://doi.org/10.1109/TNS.2004.832574","url":null,"abstract":"The main objective of this work is to evaluate the absorbed doses in the fingers of PET physicians derived from the administration of /sup 18/FDG, using the Geant3 Monte Carlo code. A comparison is made with data obtained with thermoluminiscent dosimeters. The administration of a PET radiopharmaceutical such as /sup 18/FDG presents a radiation hazard to the hands and fingers. One motivation for this study is the increased use of PET imaging in nuclear medicine that was not followed by a parallel development in the respective dose measurements and optimisation. Considering a workload of 10 patients per week, each medical doctor receives finger doses 3 times lower than the weekly skin dose limit with the fingers in the active volume and 10 times lower if they are in the rear end of the syringe. In the calculations it is assumed that a typical administered activity is 0.185 GBq with a finger-syringe contact time of 10 s. Monte Carlo calculations were performed for different kinds of syringes and different injected volumes. We have also calculated finger doses as a function of the wall thickness for three kinds of wall materials. Results show a slight dose reduction when the polypropylene syringe is replaced by a pyrex one and could be used to derive guidelines for the handling of syringes containing the most used PET radiopharmaceuticals.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124627172","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 : 2003-10-19DOI: 10.1109/NSSMIC.2003.1352564
M. Koole, S. Staelens, S. Vandenberghe, Y. D’Asseler, R. Van de Walle, I. Lemahieu
A theoretical formulation of the effective point spread function of a slat collimator on a strip detector has been derived. The used technique is based on the geometric response function of a single gap and it accurately describes the performance of the collimation system. Valuable conclusions on the sensitivity and the spatial resolution of the imaging system could be made. We found that the sensitivity was dependent on the angle of incidence and on the distance to the detector. The spatial resolution was constant in a plane at a fixed distance to the detector. These results were confirmed by the appropriate Monte Carlo simulations. The presented formulation of the geometric response function will be useful with iterative reconstruction algorithms.
{"title":"Analytical model for Solstice detector response","authors":"M. Koole, S. Staelens, S. Vandenberghe, Y. D’Asseler, R. Van de Walle, I. Lemahieu","doi":"10.1109/NSSMIC.2003.1352564","DOIUrl":"https://doi.org/10.1109/NSSMIC.2003.1352564","url":null,"abstract":"A theoretical formulation of the effective point spread function of a slat collimator on a strip detector has been derived. The used technique is based on the geometric response function of a single gap and it accurately describes the performance of the collimation system. Valuable conclusions on the sensitivity and the spatial resolution of the imaging system could be made. We found that the sensitivity was dependent on the angle of incidence and on the distance to the detector. The spatial resolution was constant in a plane at a fixed distance to the detector. These results were confirmed by the appropriate Monte Carlo simulations. The presented formulation of the geometric response function will be useful with iterative reconstruction algorithms.","PeriodicalId":186175,"journal":{"name":"2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129490428","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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