Pub Date : 1993-10-31DOI: 10.1109/NSSMIC.1993.701640
H. Suzuki, T. Tombrello, C. Melcher, J. Schweitzer
The scintillation decay of cerium-doped gadolinium oxyorthosilicate Gd/sub 2/(SiO/sub 4/)O:Ce is lengthened by the energy transfer from Gd to Ce. To investigate the role of the Gd in the scintillation processes, the Gd was partially replaced by optically inactive rare earth elements, Y and Lu, and the effective transfer rates from Gd to Ce were measured as a function of Gd and Ce concentrations using UV- and gamma-ray excitations. The data clearly indicate the dilution of the Gd by the Y and the Lu further lengthens the migration time through the Gd in the energy transfer process from Gd to Ce. >
{"title":"Energy Transfer Mechanism In Gd/sub 2/(SiO/sub 4/)O:Ce Scintillators","authors":"H. Suzuki, T. Tombrello, C. Melcher, J. Schweitzer","doi":"10.1109/NSSMIC.1993.701640","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701640","url":null,"abstract":"The scintillation decay of cerium-doped gadolinium oxyorthosilicate Gd/sub 2/(SiO/sub 4/)O:Ce is lengthened by the energy transfer from Gd to Ce. To investigate the role of the Gd in the scintillation processes, the Gd was partially replaced by optically inactive rare earth elements, Y and Lu, and the effective transfer rates from Gd to Ce were measured as a function of Gd and Ce concentrations using UV- and gamma-ray excitations. The data clearly indicate the dilution of the Gd by the Y and the Lu further lengthens the migration time through the Gd in the energy transfer process from Gd to Ce. >","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"2197 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":"130131926","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.1993.701675
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.1993.373614
M. Dahlbom, P. Cutler, W. Digby, W. K. Luk, J. Reed
Whole body PET images suffers by relatively high noise levels due to inherent poor counting statistics in the emission data. It is therefore important to optimize the acquisition parameters to minimize any additional noise contamination. It has previously been shown that using a continuous or redundant acquisition scheme, improvements in noise characteristics and image quality are seen. In this work the continuous sampling is further characterized and compared to the conventional step and shoot acquisition. The main sources of noise contamination using conventional sampling is due to the normalization procedure which is applied to the emission data. By using continuous sampling and using a common normalization for all planes, the statistical noise in the normalization is improved by factor close to the number of planes in the scanner. The continuous sampling showed to be less sensitive to small patient movements (<5 mm) compared to conventional scanning. Previously reported problems of data handling have been resolved by rewriting the acquisition firmware to allow on-line addition of the redundant sampled data in hardware.<>
{"title":"Characterization of sampling schemes for whole body PET imaging","authors":"M. Dahlbom, P. Cutler, W. Digby, W. K. Luk, J. Reed","doi":"10.1109/NSSMIC.1993.373614","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373614","url":null,"abstract":"Whole body PET images suffers by relatively high noise levels due to inherent poor counting statistics in the emission data. It is therefore important to optimize the acquisition parameters to minimize any additional noise contamination. It has previously been shown that using a continuous or redundant acquisition scheme, improvements in noise characteristics and image quality are seen. In this work the continuous sampling is further characterized and compared to the conventional step and shoot acquisition. The main sources of noise contamination using conventional sampling is due to the normalization procedure which is applied to the emission data. By using continuous sampling and using a common normalization for all planes, the statistical noise in the normalization is improved by factor close to the number of planes in the scanner. The continuous sampling showed to be less sensitive to small patient movements (<5 mm) compared to conventional scanning. Previously reported problems of data handling have been resolved by rewriting the acquisition firmware to allow on-line addition of the redundant sampled data in hardware.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"35 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":"132717292","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.1993.701800
C. Thibault, G. L. Hanna
DISCUSSION Since the construction of most nuclear power generating stations, engineering thermoplastics have replaced many original materials of construction, manufacturer designs have changed significantly and product specifications have evolved to reflect modem product requirements. Whereas many material changes provide improved thermal stability, most manufacturing changes add difficulty to the qualification process. An additional set of hurdles is established by the changes in applicable industry standards such as UL and NEMA. The following discussion focuses on the influence of design and standard changes on the qualification of replacement and retrofit items. Although the paper presents motor control center (MCC) and circuit breakers as examples of the necessary qualification analysis and test programs, most other Class 1E equipment have experienced similar changes.
{"title":"Qualification Of Modern Electrical Products To Original Plant Specifications","authors":"C. Thibault, G. L. Hanna","doi":"10.1109/NSSMIC.1993.701800","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701800","url":null,"abstract":"DISCUSSION Since the construction of most nuclear power generating stations, engineering thermoplastics have replaced many original materials of construction, manufacturer designs have changed significantly and product specifications have evolved to reflect modem product requirements. Whereas many material changes provide improved thermal stability, most manufacturing changes add difficulty to the qualification process. An additional set of hurdles is established by the changes in applicable industry standards such as UL and NEMA. The following discussion focuses on the influence of design and standard changes on the qualification of replacement and retrofit items. Although the paper presents motor control center (MCC) and circuit breakers as examples of the necessary qualification analysis and test programs, most other Class 1E equipment have experienced similar changes.","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":"132885264","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.1993.373522
S. Glick, D. de Vries, Matt A. King
A non-iterative SPECT reconstruction method is presented which consists of pre-processing the projection data for compensation of scatter, attenuation and the detector response prior to ramp filtered backprojection. Scatter is compensated for using the dual-photopeak window (DPW) method, attenuation is compensated for using Bellini's method, and compensation for the non-stationary detector response and noise suppression is performed with a frequency distance principle (FDP) Wiener filter. This approach was compared to a number of different processing methods using a Monte Carlo simulation study of an anthropomorphic digitized phantom of the liver and spleen. Compared to Butterworth smoothing, the DPW/FDP Wiener filtering method can provide a substantial increase in contrast with a noise increase ranging from minimal to moderate depending on the cut-off frequency of the Butterworth filter.<>
{"title":"Distance-dependent restoration filtering of dual photopeak window scatter compensated SPECT images","authors":"S. Glick, D. de Vries, Matt A. King","doi":"10.1109/NSSMIC.1993.373522","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.373522","url":null,"abstract":"A non-iterative SPECT reconstruction method is presented which consists of pre-processing the projection data for compensation of scatter, attenuation and the detector response prior to ramp filtered backprojection. Scatter is compensated for using the dual-photopeak window (DPW) method, attenuation is compensated for using Bellini's method, and compensation for the non-stationary detector response and noise suppression is performed with a frequency distance principle (FDP) Wiener filter. This approach was compared to a number of different processing methods using a Monte Carlo simulation study of an anthropomorphic digitized phantom of the liver and spleen. Compared to Butterworth smoothing, the DPW/FDP Wiener filtering method can provide a substantial increase in contrast with a noise increase ranging from minimal to moderate depending on the cut-off frequency of the Butterworth filter.<<ETX>>","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"166 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":"122408072","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.1993.701803
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.1993.701843
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}
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.1993.701838
A. Wahle, E. Wellnhofer, I. Mugaragu, H. U. Sauer, H. Oswald, E. Fleck
Quantitative evaluations on coronary vessel systems are of increasing importance in cardio-vascular diagnosis, therapy planning and surgical verification. Local evaluations, like stenosis analysis, are already available with sufficient accuracy. On the other hand, global evaluations on vessel segments or vessel subsystems are not yet common. Especially for the &agnosis of diffuse coronary artery diseases, we combined a 3-D reconstruction system operating on biplane angiogram with a length/volume calculation. The 3-D reconstruction results in a 3-D model of the coronary vessel system, consisting of the vessel skeleton and a discrete number of contours. To obtain a most accurate model, we focussed on exact geometry determination. Several algorithms for calculating missing geometric parameters and correcting remaining geometry errors were implemented and verified. The length/volume evaluation can be performed either on single vessel segments, on a set of segments, or on sub-trees. A volume model based on generalized elliptical conic sections is created for the selected segments. Volumes and lengths (measured along the vessel course) of those elements are summed up. In this way, the morphological parameters of a vessel subsystem can be set in relation to the parameters of the supplying segment proximal to it. These relations allow objective assessments of diffuse coronary artery diseases. sional measures defined on sets of sub-trees was selected and tested clinically. IT. 3-D RECONSTRUCTION A . Imaging Geometry and Point Reconstruction Standard biplane angiographic equipment consists of two x-ray systems having a common coordinate system [l]. In conventional methods, a fixed rotational origin of both systems is assumed where the projection axes intersect, the isocenter. For volume measurements, we need a very high reconstruction accuracy, because linear reconstruction errors raise to the third power. The classic isocenvic model could not satisfy this requirement: there is neither a stable isocenter, nor is there an adequate way to determine the required distances manually [21. In our geometric model, we use a variable iso-axis instead of a fixed isocenter. The distance of the projection axes creates a unique iso-axis orthogonal to both of them (fig. 2). The locations of x-ray sources and image intensifiers are determined in terms of distances to this iso-axis. The origin of the world coordinate system is defined as the weighted middle of the projection axes distance on the iso-axis. The angulation is obtained conventionally as a sequence of rotations, con-
{"title":"Quantitative Volume Analysis Of Coronary Vessel Systems By 3-D Reconstruction From Biplane Angiograms","authors":"A. Wahle, E. Wellnhofer, I. Mugaragu, H. U. Sauer, H. Oswald, E. Fleck","doi":"10.1109/NSSMIC.1993.701838","DOIUrl":"https://doi.org/10.1109/NSSMIC.1993.701838","url":null,"abstract":"Quantitative evaluations on coronary vessel systems are of increasing importance in cardio-vascular diagnosis, therapy planning and surgical verification. Local evaluations, like stenosis analysis, are already available with sufficient accuracy. On the other hand, global evaluations on vessel segments or vessel subsystems are not yet common. Especially for the &agnosis of diffuse coronary artery diseases, we combined a 3-D reconstruction system operating on biplane angiogram with a length/volume calculation. The 3-D reconstruction results in a 3-D model of the coronary vessel system, consisting of the vessel skeleton and a discrete number of contours. To obtain a most accurate model, we focussed on exact geometry determination. Several algorithms for calculating missing geometric parameters and correcting remaining geometry errors were implemented and verified. The length/volume evaluation can be performed either on single vessel segments, on a set of segments, or on sub-trees. A volume model based on generalized elliptical conic sections is created for the selected segments. Volumes and lengths (measured along the vessel course) of those elements are summed up. In this way, the morphological parameters of a vessel subsystem can be set in relation to the parameters of the supplying segment proximal to it. These relations allow objective assessments of diffuse coronary artery diseases. sional measures defined on sets of sub-trees was selected and tested clinically. IT. 3-D RECONSTRUCTION A . Imaging Geometry and Point Reconstruction Standard biplane angiographic equipment consists of two x-ray systems having a common coordinate system [l]. In conventional methods, a fixed rotational origin of both systems is assumed where the projection axes intersect, the isocenter. For volume measurements, we need a very high reconstruction accuracy, because linear reconstruction errors raise to the third power. The classic isocenvic model could not satisfy this requirement: there is neither a stable isocenter, nor is there an adequate way to determine the required distances manually [21. In our geometric model, we use a variable iso-axis instead of a fixed isocenter. The distance of the projection axes creates a unique iso-axis orthogonal to both of them (fig. 2). The locations of x-ray sources and image intensifiers are determined in terms of distances to this iso-axis. The origin of the world coordinate system is defined as the weighted middle of the projection axes distance on the iso-axis. The angulation is obtained conventionally as a sequence of rotations, con-","PeriodicalId":287813,"journal":{"name":"1993 IEEE Conference Record Nuclear Science Symposium and Medical Imaging Conference","volume":"4 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":"115717238","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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