1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record最新文献

{"title":"Evaluation of factor analysis accuracy for myocardial perfusion in PET studies","authors":"M. Grégoire, F. Frouin, F. Lavenne, O. de Dreuille, M. Janier, R. Di Paola, L. Cinotti","doi":"10.1109/NSSMIC.1995.501911","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.501911","url":null,"abstract":"Factor Analysis of Medical Image Sequences (FAMIS) estimates kinetics (factors) and corresponding spatial regions (factor images) from dynamic studies, taking into account statistical noise and spillover effects. Factor images obtained from /sup 15/O-water clinical cardiac PET studies are less noisy than conventional subtraction images, and factors match physiologic kinetics. Here, the authors studied FAMIS accuracy and precision depending on the application context. FAMIS was evaluated through kinetics parameters quantification. Numerical simulations and phantom experiments were carried out using a typical left ventricular pattern. This object was simulated in 2D with 3 noise levels and 2 kinds of kinetics: mono-exponentials which correspond to natural tracer decay, and tissue perfusion kinetics obtained with a realistic vascular input function. Mono-exponentials association was adapted to phantom experiments while perfusion kinetics represented clinical cardiac studies. In both phantom experiments and simulations, the inner chamber was filled with /sup 15/O-water and the myocardial space with Carbon-11. The different noise levels which were studied corresponded to ideal, normal and low quality scans. Using the factors estimated by FAMIS, decay constants and an index of flow (k1) were estimated by fitting or modelling. Relative bias to the true value and standard deviation were then estimated, and spatial correlation between factor images and original spatial pattern was computed. Factor images spatial correlation was very good, despite of large overlapping pattern. Oxygen-15 decay constant was assessed from factor with a small relative bias, for all noise levels and trixel sizes. However, Carbon-11 extraction was very sensitive to both noise and spillover in phantom and simulations. A reasonable bias was only achieved by including a spillover term which accounted for an overcorrection. On the contrary, factors associated to perfusion were well extracted and k1 parameter was recovered with a low relative bias (r.b.<6%), except for the higher noise level. It was already shown that FAMIS performances depend on the overlap of the spatial structures. This study demonstrates that factor analysis without a priori information performances depend on kinetics shape. Moreover, in the context of cardiac /sup 15/O-water perfusion studies, FAMIS should provide accurate quantification.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"102-103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117142430","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}

{"title":"Comparison of energy window choice and parameter implementation in dual energy window scatter correction performance in 3D PET","authors":"V. Sossi, J. S. Barney, T. Oakes, T. Ruth","doi":"10.1109/NSSMIC.1995.510447","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510447","url":null,"abstract":"The authors have investigated the relevance of the energy window choice in the dual energy window (DEW) scatter correction method (Grootoenk et al., 1991). This method depends strongly on the difference between 2 parameters that need to be estimated from phantom studies, the ratio (R/sub unsc/) between the true events in the low energy window (LEW) and high energy window (HEW), and the equivalent ratio for the scattered events (R/sub sc/). The transaxial distribution of the R/sub unsc/ is relatively flat regardless of the energy window selection. However, the energy window choice considerably influences the transaxial distribution of R/sub sc/. Since the DEW scatter correction method does not make use of convolution techniques, spatial variations of parameters are expected to lead to nonuniformities in scatter corrected images. The authors have investigated the DEW scatter correction accuracy and uniformity as a function of energy window choice and determination of R/sub sc/. Based on stability considerations 2 sets of energy windows have been selected for study, 100-350-850 keV and 250-380-850 keV. Three methods to implement the R/sub sc/ values in the scatter correction estimate have been used: an array containing the transaxial distribution of R/sub sc/; a constant value obtained by averaging R/sub sc/, over the central 20 cm diameter region; and a constant value corresponding to the central R/sub sc/ value. The use of constant values for R/sub sc/ improved image uniformity for both sets of energy windows from within 30% obtained when the array for R/sub sc/ was used, to about 15%. The uniformity was estimated over a 20 cm diameter region. Scatter correction accuracy as determined from uniform phantom and cold spot studies was comparable in all cases. No significant difference in transaxial or axial image uniformity was observed between data obtained with the 2 sets of energy windows and normalized with the present normalization algorithm. Likewise the accuracy obtained in both cases was comparable, indicating that the implementation method of the R/sub sc/ is a more important factor in the DEW scatter correction method performance than the selection of energy windows.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116079971","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}

{"title":"Semi-insulating bulk GaAs thermal neutron imaging arrays","authors":"D. Mcgregor, J. T. Lindsay, C. Brannon, R. Olsen","doi":"10.1109/NSSMIC.1995.504252","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504252","url":null,"abstract":"Prototype thermal neutron imaging arrays have been fabricated from semi-insulating (SI) bulk GaAs. The arrays are 1 mm square Schottky diodes arranged in a 5/spl times/5 matrix. GaAs Schottky barrier radiation detectors are relatively radiation hard and can withstand higher neutron exposure fields than MOS based Si diode imaging arrays. The devices use boron-10 to convert incident thermal neutrons to energetic Li ions and alpha particles. The truncated field effect observed with SI bulk GaAs detectors produces high and low field regions in the device. Electron-hole pairs produced in the active (or high field) region of the device contribute to the observed induced charge, whereas electron-hole pairs produced in the low field region contribute very little to the induced charge. The effect is manipulated to reduce the background gamma ray interaction rate in the devices. Preliminary results show no indication of device degradation after exposure to a total thermal neutron fluence of 1.73/spl times/10/sup 13/ n/cm/sup 2/. Images have been formed of 1, 1.5, and 2 mm holes and crosses from 2 mm thick Cd templates.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115417896","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}

{"title":"Compton scatter and X-ray crosstalk and the use of very thin inter-crystal septa in high resolution PET detectors","authors":"Craig S. Levin, M. Tornai, Simon R. Cherry, L. R. MacDonald, Edward J. Hoffman","doi":"10.1109/NSSMIC.1995.510442","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510442","url":null,"abstract":"To improve spatial resolution, PET systems are being developed with finer detector elements. Unfortunately, using smaller crystal sizes increases inter-crystal Compton scatter and bismuth X-ray and (to a lesser degree) electron escape crosstalk, causing positioning errors that lead to degradation of image contrast. The authors investigated the use of extremely thin (/spl les/300 /spl mu/m) lead strips for passive shielding of this inter-crystal crosstalk. Using annihilation photons and small (2 and 3 mm wide) BGO crystals in coincidence, crosstalk studies were performed with either two small adjacent crystals (1-D) or one crystal inside a volume of BGO (2-D). The fraction of Compton scattered events from one crystal into an adjacent one was reduced, on average, by a factor of 3.2 (2.2) in the 1-D experiment and by a factor of 3.0 (2.1) in 2-D, with a 300 (150) /spl mu/m thick lead strip in between the crystals and a 300-700 keV energy window in both crystals. The authors could not measure a reduction in bismuth X-ray crosstalk with the use of lead septa because of the production of lead X-rays. The width of the coincident point spread function was not significantly different for the 1- and 2-D studies, with or without the different thickness septa in place. These results indicate that intercrystal crosstalk does not affect the positioning resolution. A simple insertion of very thin lead strips may significantly reduce the inter-crystal scattering crosstalk of a high resolution PET system, thereby ultimately improving image contrast, without introducing a dead area.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123431544","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}

{"title":"Development of high-pressure Xe ionization detectors for hard X-ray and low energy gamma-ray astronomy","authors":"A. Bolotnikov, B. Ramsey","doi":"10.1109/NSSMIC.1995.504221","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504221","url":null,"abstract":"A purification system, purity and density monitors, and the design of a high-pressure Xe cylindrical ionization chamber have been tested as apart of a development of high-pressure Xe detectors for X-ray and gamma-ray astronomy. Preliminary results from the high-pressure Xe cylindrical ionization chamber confirms advantages of such detectors for hard X-rays and low energy gamma-rays.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124451738","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}

{"title":"Preliminary results from a novel CCD-based imaging system for biomedical applications","authors":"J. MacDonald, K. Wells, R. Ott","doi":"10.1109/NSSMIC.1995.501922","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.501922","url":null,"abstract":"A digital autoradiography system, incorporating a cooled scientific charge coupled device (CCD) is in development at the Physics Department of the Institute of Cancer Research (ICR). The ICR system is designed to image /spl beta/-particles and low energy X-rays from radiolabelled biological tissue samples, utilising direct irradiation of the CCD. This prototype system displays position resolution of 30 /spl mu/m over an area of /spl sim/4 cm/sup 2/. System response is linear over a dynamic range of at least 10/sup 4/, with signal to noise ratio approaching 300. The different components of system noise are discussed,along with the optimisation of integration times to minimise their effect. The potential application of the system to \"multimodality\" imaging-the automatic registration of optical and radionuclide images of a stained tissue sample-is discussed.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123122523","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}

{"title":"An efficient linogram sampling method for cone-beam reconstruction","authors":"H. Kudo, T. Saito","doi":"10.1109/NSSMIC.1995.510469","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510469","url":null,"abstract":"We propose efficient 2-D and 3-D linogram methods for image reconstruction from Radon data. Furthermore, we use these methods to accelerate Grangeat's cone-beam reconstruction algorithm.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121660115","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}

{"title":"A prototype data acquisition system for the BELLE vertex detector","authors":"T. Nobori, T. Uchida, C. Fukunaga, M. Tanaka, H. Ikeda","doi":"10.1109/NSSMIC.1995.504265","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504265","url":null,"abstract":"A prototype data acquisition (DAQ) system for the BELLE silicon vertex detector has been constructed. We measured its performance using a test board for front-end readout system emulation. While signals are generated in a test module, the process sequence of interrupt, data transfer, digitization are set up as a design which we will adopt in the final production. In this report we discuss the detail of the DAQ system and its data processing capability. We then conclude that the prototype system is satisfied with the requirement initially given to the system construction.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126425769","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}

{"title":"A 48/spl times/48 CdZnTe array with multiplexer readout","authors":"D. G. Marks, H. B. Barber, H. Barrett, E. Dereniak, J. Eskin, K. Matherson, J. Woolfenden, E. Young, F. Augustine, W. Hamiltons, J. Venzon, B. Apotovsky, F. P. Dotys","doi":"10.1109/NSSMIC.1995.510377","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.510377","url":null,"abstract":"We report results of gamma-ray imaging and energy-resolution tests of a 48/spl times/48 CdZnTe array. Our detectors have 125 /spl mu/m square pixel electrodes produced by photolithography and are indium-bump-bonded to multiplexer readout circuit. Using a collimated beam of 140 keV gamma rays of 120 /spl mu/m diameter centered on one pixel, we found that the majority of events produced significant charge deposition in nearby pixels. Charge and energy are transported out of the pixel by charge diffusion, photoelectron range, Compton scattering, and escape of K X-rays. These effects also distort single-pixel spectra, although photopeaks are still discernible at 140 keV. When signals from neighboring pixels are summed together to correct for this charge spreading, an energy resolution of 10 keV is obtained at 140 keV. Corrections will be simpler and energy resolution should be better for the 380 /spl mu/m pixels of the 64/spl times/64 CdZnTe arrays we are constructing for an ultra-high-resolution brain imager.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129978166","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}

{"title":"Performance comparison of near-optimum digital pulse processors in high resolution X-ray spectroscopy","authors":"Angelo Geraci, M. Zambusi, G. Ripamonti","doi":"10.1109/NSSMIC.1995.504164","DOIUrl":"https://doi.org/10.1109/NSSMIC.1995.504164","url":null,"abstract":"Digital filtering has a high potential in nuclear spectroscopy due to its adaptivity, easiness of calibration etc., but also because it can synthesise filters close to the theoretical optimum. This works is a cross-comparison of a traditional analog processing system and two near-optimum digital processing methods for what concerns energy resolution. The samples are obtained by digitising the signal pulse as it appears at the output of a proper analog conditioning circuit. Both digital techniques take advantage of the possibility of synthesising the best possible weighting function with respect to the actual noise conditions. A noticeable improvement of more than 10% in energy resolution has been achieved with both systems with respect to state-of-the-art systems based on analog circuitry. In particular, the two digital processors are shown to be the best choice respectively for on-line use with critical ballistic deficit conditions and for very high resolution spectroscopy systems ultimately limited by 1/f noise.","PeriodicalId":409998,"journal":{"name":"1995 IEEE Nuclear Science Symposium and Medical Imaging Conference Record","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129403146","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}