Pub Date : 1993-10-31DOI: 10.1109/NSSMIC.1993.701803
R. Brill
This paper discusses the status of NRC in setting acceptance criteria for high integrity digital systems and the research to support the development of these criteria. Design and evaluation of high integrity digital systems must include consideration of hardware, software, and human factors as they relate to safety. Two of the NRC sponsored research projects are discussed. The first project is "Risk Impact of New Technologies", which has two objectives which are: (1) to demonstrate the feasibility of techniques for assessing how digital technology in instrumentation and control is expected to change human actions and error rates, system unavailability, and core damage frequency; and ( 2 ) to improve methods for analyzing this human performance in PRA's. The second project is "Integration of Research to Develop the Technical Basis for Software Regulatory Positions" which is to provide the technical basis for developing software acceptance criteria and identify areas where further research is required.
{"title":"High Integrity Digital Systems And Nuclear Safety","authors":"R. Brill","doi":"10.1109/NSSMIC.1993.701803","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701803","url":null,"abstract":"This paper discusses the status of NRC in setting acceptance criteria for high integrity digital systems and the research to support the development of these criteria. Design and evaluation of high integrity digital systems must include consideration of hardware, software, and human factors as they relate to safety. Two of the NRC sponsored research projects are discussed. The first project is \"Risk Impact of New Technologies\", which has two objectives which are: (1) to demonstrate the feasibility of techniques for assessing how digital technology in instrumentation and control is expected to change human actions and error rates, system unavailability, and core damage frequency; and ( 2 ) to improve methods for analyzing this human performance in PRA's. The second project is \"Integration of Research to Develop the Technical Basis for Software Regulatory Positions\" which is to provide the technical basis for developing software acceptance criteria and identify areas where further research is required.","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"9 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120993459","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.1993.373525
R. Smith, J. Karp
Quantitative, low noise, measured attenuation correction has been established for the PENN PET 240H Volume Imaging Camera. This is achieved, without septa, using a narrow energy (450-570 keV) and sinogram position (2 cm wide mask) gate to minimize scatter contamination. Twelve minute transmission acquisitions with a 0.5 mCi rod source are adequate for this purpose. Post injection transmission scans (with emission activity in the FOV) suffer from emission contamination simulating transmitted gamma ray flux. This emission contamination may be measured by performing a transmission acquisition without a transmission source. This contamination is then subtracted from the measured post injection transmission scan. Emission activity within the FOV adds to detector deadtime so that more counts are lost than are added by the emission activity counts accepted into the transmission position gate. Thus there is a net loss of scan statistics when compared to pre-injection transmission scanning. Removal of emission contamination and compensation for this excess deadtime results in corrected attenuation coefficients. For residual activity levels typical of FDG whole-body cancer and cardiac studies the post injection measurements are within 4% of pre-injection values. This method is under refinement to correct for attenuation with higher levels of activity in the FOV.<>
建立了PENN PET 240H体像相机的定量、低噪声、实测衰减校正方法。这是实现的，没有隔膜，使用窄能量(450- 570kev)和sinogram位置(2厘米宽掩膜)栅极，以尽量减少散射污染。12分钟传输采集与0.5 mCi棒源是足够的，用于此目的。注射后透射扫描(视场内具有发射活动)受到模拟透射伽马射线通量的发射污染的影响。这种排放污染可以通过在没有传输源的情况下进行传输采集来测量。然后从测量的注射后传输扫描中减去这种污染。视场内的发射活动增加了探测器的死区时间，因此丢失的计数比接收到传输位置门的发射活动计数所增加的计数要多。因此，与注射前传输扫描相比，存在扫描统计数据的净损失。去除排放污染并补偿这一过量死区时间可得到校正的衰减系数。对于典型的FDG全身癌症和心脏研究的残留活性水平，注射后测量值在注射前值的4%以内。该方法正在改进中，以纠正视场中较高活动水平的衰减。
{"title":"Post injection transmission scanning in a volume imaging PET camera","authors":"R. Smith, J. Karp","doi":"10.1109/NSSMIC.1993.373525","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373525","url":null,"abstract":"Quantitative, low noise, measured attenuation correction has been established for the PENN PET 240H Volume Imaging Camera. This is achieved, without septa, using a narrow energy (450-570 keV) and sinogram position (2 cm wide mask) gate to minimize scatter contamination. Twelve minute transmission acquisitions with a 0.5 mCi rod source are adequate for this purpose. Post injection transmission scans (with emission activity in the FOV) suffer from emission contamination simulating transmitted gamma ray flux. This emission contamination may be measured by performing a transmission acquisition without a transmission source. This contamination is then subtracted from the measured post injection transmission scan. Emission activity within the FOV adds to detector deadtime so that more counts are lost than are added by the emission activity counts accepted into the transmission position gate. Thus there is a net loss of scan statistics when compared to pre-injection transmission scanning. Removal of emission contamination and compensation for this excess deadtime results in corrected attenuation coefficients. For residual activity levels typical of FDG whole-body cancer and cardiac studies the post injection measurements are within 4% of pre-injection values. This method is under refinement to correct for attenuation with higher levels of activity in the FOV.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"3 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":"125352313","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.1993.373588
Joaquim Teixeira de Assis, T. Lopes, J.L. Rodridgues
A microtomographic system has been assembled using a real time microfocus radiography system and a image digitizer schedule. The aim of this system was in data acquisition time; that was hardly reduced compared with traditional microtomographic systems that employ conventional X-ray sources and detectors. Several microtomographies were carried out using the same type of samples used in the traditional systems, to compare the performance of the authors' system (spatial resolution, density resolution and image quality).<>
{"title":"Microtomography using microfocus radiography system","authors":"Joaquim Teixeira de Assis, T. Lopes, J.L. Rodridgues","doi":"10.1109/NSSMIC.1993.373588","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373588","url":null,"abstract":"A microtomographic system has been assembled using a real time microfocus radiography system and a image digitizer schedule. The aim of this system was in data acquisition time; that was hardly reduced compared with traditional microtomographic systems that employ conventional X-ray sources and detectors. Several microtomographies were carried out using the same type of samples used in the traditional systems, to compare the performance of the authors' system (spatial resolution, density resolution and image quality).<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"18 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":"117351812","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.1993.373634
L. Eriksson
A simple model to describe data losses in PET cameras is presented. The model is not intended to be used primarily for dead time corrections in existing scanners, even if this may be possible. Instead the model is intended to be used for data simulations in order to determine the figures of merits of future camera systems based on data handling state-of-art solutions. The model assumes the data loss to be factorized into two components, one describing the detector or block-detector performance and the other the remaining data handling such as coincidence determinations, data transfer and data storage. Two modern positron camera systems have been investigated in terms of this model. These are the new Siemens-CTI systems, Ecat Exact and Ecat Exact HR, both with an axial field-of-view (FOV) covering around 15 cm. They both have retractable septa and can acquire data from the whole volume within the FOV and can reconstruct volume image data. An example is given how to use the model for live time calculations in a futuristic large axial FOV cylindrical system.<>
{"title":"A simple data loss model for positron camera systems","authors":"L. Eriksson","doi":"10.1109/NSSMIC.1993.373634","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373634","url":null,"abstract":"A simple model to describe data losses in PET cameras is presented. The model is not intended to be used primarily for dead time corrections in existing scanners, even if this may be possible. Instead the model is intended to be used for data simulations in order to determine the figures of merits of future camera systems based on data handling state-of-art solutions. The model assumes the data loss to be factorized into two components, one describing the detector or block-detector performance and the other the remaining data handling such as coincidence determinations, data transfer and data storage. Two modern positron camera systems have been investigated in terms of this model. These are the new Siemens-CTI systems, Ecat Exact and Ecat Exact HR, both with an axial field-of-view (FOV) covering around 15 cm. They both have retractable septa and can acquire data from the whole volume within the FOV and can reconstruct volume image data. An example is given how to use the model for live time calculations in a futuristic large axial FOV cylindrical system.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"104 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":"127992748","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.1993.701675
W. Madigan
The response functions of nuclear tools for well logging are generally characterized by means of measurements made in calibrated test formations. Numerical simulations of the tool performance can be used to extend these characterizations to conditions which are inconvenient or costly to reproduce in the laboratory. The simulations reported here were performed to determine the response of a commercial spectral density tool in a heavy mud cake environment.
{"title":"Monte Carlo Simulation Of Pulse Height Spectra In Nuclear Logging Density Tools","authors":"W. Madigan","doi":"10.1109/NSSMIC.1993.701675","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701675","url":null,"abstract":"The response functions of nuclear tools for well logging are generally characterized by means of measurements made in calibrated test formations. Numerical simulations of the tool performance can be used to extend these characterizations to conditions which are inconvenient or costly to reproduce in the laboratory. The simulations reported here were performed to determine the response of a commercial spectral density tool in a heavy mud cake environment.","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"29 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":"132298964","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.1993.373629
G. L. Zeng, Y. Hsieh, G. Gullberg
The authors propose and implement a rotating-and-squashing projector-backprojector pair for fan-beam and cone-beam iterative algorithms. The motivation of their investigation is to significantly reduce both computation time and reconstruction artifacts when implementing attenuation, geometric and scatter correction models. At each projection angle, the authors' projector/backprojector first rotates the image volume so that the front face of the volume is parallel to the detector, then squashes the image volume so that the fan-beam and cone-beam rays are converted into parallel rays. In the authors' implementation, these two steps are combined and they only interpolate the voxel values once. The projection operation is achieved by a simple summation, and the backprojection operation is achieved by copying the projection array to the image volume. Another advantage of this projector/backprojector is that the system point response function can be deconvolved via the fast Fourier transform using the shift-invariant property of the point response function when the voxel-to-detector distance is constant. At each projection angle, the authors rotate and squash the image volume using interpolations. This causes smoothing of the image. However, this smoothing can be modeled as a point spread function and be deconvolved. The fan-beam and cone-beam rotating-and-squashing projector/backprojector have been implemented on a SPECT system for the EM-ML algorithm.<>
{"title":"A rotating and squashing projector-backprojector pair for fan-beam and cone-beam iterative algorithms","authors":"G. L. Zeng, Y. Hsieh, G. Gullberg","doi":"10.1109/NSSMIC.1993.373629","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373629","url":null,"abstract":"The authors propose and implement a rotating-and-squashing projector-backprojector pair for fan-beam and cone-beam iterative algorithms. The motivation of their investigation is to significantly reduce both computation time and reconstruction artifacts when implementing attenuation, geometric and scatter correction models. At each projection angle, the authors' projector/backprojector first rotates the image volume so that the front face of the volume is parallel to the detector, then squashes the image volume so that the fan-beam and cone-beam rays are converted into parallel rays. In the authors' implementation, these two steps are combined and they only interpolate the voxel values once. The projection operation is achieved by a simple summation, and the backprojection operation is achieved by copying the projection array to the image volume. Another advantage of this projector/backprojector is that the system point response function can be deconvolved via the fast Fourier transform using the shift-invariant property of the point response function when the voxel-to-detector distance is constant. At each projection angle, the authors rotate and squash the image volume using interpolations. This causes smoothing of the image. However, this smoothing can be modeled as a point spread function and be deconvolved. The fan-beam and cone-beam rotating-and-squashing projector/backprojector have been implemented on a SPECT system for the EM-ML algorithm.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"28 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":"130653500","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.1993.373518
M. Usman, A. Hero, J. Fessler, W. Rogers
The authors quantify fundamental bias-variance tradeoffs for the image reconstruction problem in radio-pharmaceutical tomography using Cramer-Rao (CR) bound analysis. The image reconstruction problem is very often biased and the classical or the unbiased CR bound on the mean square error performance of the estimator can not be used. The authors use a recently developed "uniform" CR bound which applies to biased estimators whose bias gradient satisfies a user specified length constraint. The authors demonstrate the use of the "uniform" CR bound for a simple SPECT system using several different examples.<>
{"title":"Bias-variance tradeoffs analysis using uniform CR bound for a SPECT system","authors":"M. Usman, A. Hero, J. Fessler, W. Rogers","doi":"10.1109/NSSMIC.1993.373518","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373518","url":null,"abstract":"The authors quantify fundamental bias-variance tradeoffs for the image reconstruction problem in radio-pharmaceutical tomography using Cramer-Rao (CR) bound analysis. The image reconstruction problem is very often biased and the classical or the unbiased CR bound on the mean square error performance of the estimator can not be used. The authors use a recently developed \"uniform\" CR bound which applies to biased estimators whose bias gradient satisfies a user specified length constraint. The authors demonstrate the use of the \"uniform\" CR bound for a simple SPECT system using several different examples.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"1 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":"130747736","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.1993.373606
L. Thurfjell, C. Bohm
The interpretation of functional neuroimaging data can in many cases be facilitated by comparisons with simulated data corresponding to the measuring situation. A computerized brain atlas is used to provide information regarding the spatial extent of the object being imaged. This knowledge combined with information about the resolution of the imaging device expressed as point spread functions is used to calculate a simulated image of the object. This image can be regarded as a generalized region of interest (ROI) containing information of the object as viewed by the specific instrument. Generalized ROIs are used to automatically determine boundaries of ordinary ROIs and to provide recovery coefficients to compensate for partial volume effects. Simulations can also be used to generate three-dimensional data sets where different uptake levels have been assigned to different anatomical structures.<>
{"title":"Atlas generated generalized ROIs for use in functional neuroimaging","authors":"L. Thurfjell, C. Bohm","doi":"10.1109/NSSMIC.1993.373606","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373606","url":null,"abstract":"The interpretation of functional neuroimaging data can in many cases be facilitated by comparisons with simulated data corresponding to the measuring situation. A computerized brain atlas is used to provide information regarding the spatial extent of the object being imaged. This knowledge combined with information about the resolution of the imaging device expressed as point spread functions is used to calculate a simulated image of the object. This image can be regarded as a generalized region of interest (ROI) containing information of the object as viewed by the specific instrument. Generalized ROIs are used to automatically determine boundaries of ordinary ROIs and to provide recovery coefficients to compensate for partial volume effects. Simulations can also be used to generate three-dimensional data sets where different uptake levels have been assigned to different anatomical structures.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"12 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":"117211019","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.1993.701843
M. Figueiredo, J. Leitão
AbatTactAccurate and fully automatic assessment of artery dimensions in angiograms has been sought as a diagnostic tool, in particular for coronary heart disease. We propose a new technique to estimate vessel borders in angiographic images. Unlike in previous approaches, the obtained edge estimates are unbiased, this being of primordial importance since quantitative analysis is the goal. Another important feature of the proposed estimator is that no constant background is assumed, making it well suited for noxisubtracted angiograms. The key aspect of our approach is that the smoothness constraint is not used to smooth or i n some other way modify the estimates directly derived from the image (which would introduce bias) but rather elect (without modifying) candidate estimates. As a result, tlie selected points, if correct, are unbiased estimates. Even at low contrast segments and in tlie vicinity of artifacts, the true border points still correspond to (possibly faint) local maxima of the edge operator, wliicli can be correctly chosen if the surrounding context is taken into account. Robustness against unknown background is provided by tlie use a morphological edge detector rather than some linear operator such as a matched filter wliicli assumes flat background.
{"title":"An Unbiased Technique For Automatic Estimation Of Vessel Contours In Angiograms","authors":"M. Figueiredo, J. Leitão","doi":"10.1109/NSSMIC.1993.701843","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701843","url":null,"abstract":"AbatTactAccurate and fully automatic assessment of artery dimensions in angiograms has been sought as a diagnostic tool, in particular for coronary heart disease. We propose a new technique to estimate vessel borders in angiographic images. Unlike in previous approaches, the obtained edge estimates are unbiased, this being of primordial importance since quantitative analysis is the goal. Another important feature of the proposed estimator is that no constant background is assumed, making it well suited for noxisubtracted angiograms. The key aspect of our approach is that the smoothness constraint is not used to smooth or i n some other way modify the estimates directly derived from the image (which would introduce bias) but rather elect (without modifying) candidate estimates. As a result, tlie selected points, if correct, are unbiased estimates. Even at low contrast segments and in tlie vicinity of artifacts, the true border points still correspond to (possibly faint) local maxima of the edge operator, wliicli can be correctly chosen if the surrounding context is taken into account. Robustness against unknown background is provided by tlie use a morphological edge detector rather than some linear operator such as a matched filter wliicli assumes flat background.","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"107 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":"117224504","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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