Pub Date : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596897
T. Benson, J. Gregor
Three-dimensional iterative reconstruction of high-resolution computed tomography data poses significant difficulties due to the associated computational burden. In previous work, we have shown that implementing distributed computing techniques in addition to ordered subsets is an effective approach to decreasing the total reconstruction run-time. However, we also established that interprocessor communication accounts for a considerable portion of the total run-time. In this work, we first analyze the simultaneous iterative reconstruction technique (SIRT) to establish its convergence. We then modify the SIRT algorithm in order to substantially decrease the interprocessor communication requirements, and thus the final run-time, while maintaining convergence. We include error reduction statistics and timing results gathered from a reconstruction of a mouse data set to demonstrate the advantages of the modified SIRT algorithm
{"title":"Modified simultaneous iterative reconstruction technique for faster parallel computation","authors":"T. Benson, J. Gregor","doi":"10.1109/NSSMIC.2005.1596897","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596897","url":null,"abstract":"Three-dimensional iterative reconstruction of high-resolution computed tomography data poses significant difficulties due to the associated computational burden. In previous work, we have shown that implementing distributed computing techniques in addition to ordered subsets is an effective approach to decreasing the total reconstruction run-time. However, we also established that interprocessor communication accounts for a considerable portion of the total run-time. In this work, we first analyze the simultaneous iterative reconstruction technique (SIRT) to establish its convergence. We then modify the SIRT algorithm in order to substantially decrease the interprocessor communication requirements, and thus the final run-time, while maintaining convergence. We include error reduction statistics and timing results gathered from a reconstruction of a mouse data set to demonstrate the advantages of the modified SIRT algorithm","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129543647","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596869
Feng Qiao, T. Pan, J.W. Clark, O. Mawlawi
Respiratory motion of the patient can cause image blur and inaccurate radioactivity quantification in PET imaging. Gated PET acquisition freezes the motion but suffers in image quality due to insufficient photon statistics. We present in this paper a novel approach that incorporates motion information into the reconstruction process and reconstruct the motion-free image with all data acquired. Computer simulation and phantom study showed good motion compensation capability of this algorithm, with no obvious motion artifacts visible on the reconstructed image
{"title":"Compensating respiratory motion in PET image reconstruction using 4D PET/CT","authors":"Feng Qiao, T. Pan, J.W. Clark, O. Mawlawi","doi":"10.1109/NSSMIC.2005.1596869","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596869","url":null,"abstract":"Respiratory motion of the patient can cause image blur and inaccurate radioactivity quantification in PET imaging. Gated PET acquisition freezes the motion but suffers in image quality due to insufficient photon statistics. We present in this paper a novel approach that incorporates motion information into the reconstruction process and reconstruct the motion-free image with all data acquired. Computer simulation and phantom study showed good motion compensation capability of this algorithm, with no obvious motion artifacts visible on the reconstructed image","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127939144","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596798
J. Brankov, G. Khelashvili, D. Chapman, M. Anastasio, Yongyi Yang, Z. Zhong, M. Wernick
We have recently proposed a new X-ray imaging method, called multiple-image radiography (MIR), which simultaneously produces images of absorption, refraction, and ultra-small-angle scatter, while rejecting higher-angle scatter. This paper presents a theoretical model of the relevant X-ray propagation mechanisms, thereby explaining why MIR works. Specifically, beam propagation is computed through a stratified scattering medium in an ultra-small-angle regime. This analysis demonstrates that the MIR images are linear with object thickness, which is a requirement for computed tomography by standard reconstruction methods.
{"title":"Physical model of image formation in multiple-image radiography","authors":"J. Brankov, G. Khelashvili, D. Chapman, M. Anastasio, Yongyi Yang, Z. Zhong, M. Wernick","doi":"10.1109/NSSMIC.2005.1596798","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596798","url":null,"abstract":"We have recently proposed a new X-ray imaging method, called multiple-image radiography (MIR), which simultaneously produces images of absorption, refraction, and ultra-small-angle scatter, while rejecting higher-angle scatter. This paper presents a theoretical model of the relevant X-ray propagation mechanisms, thereby explaining why MIR works. Specifically, beam propagation is computed through a stratified scattering medium in an ultra-small-angle regime. This analysis demonstrates that the MIR images are linear with object thickness, which is a requirement for computed tomography by standard reconstruction methods.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130475720","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596747
E. Quan, D. Lalush
We study reconstruction methods and resolution effects in a proposed multi-source X-ray micro-computed tomography (CT) system. The proposed device is based on dense arrays of microfabricated field-emission X-ray sources which are individually addressable. The proposed system has two 10 cm linear arrays of X-ray sources, each with 50 sources spaced at 2 mm. The two source arrays form two contiguous sides of a square, and two 10 cm area detectors form the other two sides of the square. We estimate that this results in an effective field of view of a 3.2 cm diameter cylinder, suitable for a mouse. No motion of source or subject is needed; simply flashing the individual sources creates angular sampling for tomography, though it is a limited-angle problem. We demonstrate implementations of two iterative reconstruction techniques, block-iterative transmission (BIT) and ordered-subsets convex (OSC). Using data simulated from a realistic mouse phantom, we study the reconstruction quantitative accuracy, point spread functions and noise responses at several locations in the field of view. We demonstrate that the reconstructions are quantitatively accurate and mostly free from disturbing artifacts, while the point spread functions in this geometry are anisotropic and spatially-varying. The OSC algorithm converges faster, showing better resolution yet worse noise performance than BIT after five iterations. We conclude that the proposed geometry is viable for fast, high-resolution and motion-free imaging
{"title":"Resolution effects in a dense linear source array X-ray micro-tomograph","authors":"E. Quan, D. Lalush","doi":"10.1109/NSSMIC.2005.1596747","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596747","url":null,"abstract":"We study reconstruction methods and resolution effects in a proposed multi-source X-ray micro-computed tomography (CT) system. The proposed device is based on dense arrays of microfabricated field-emission X-ray sources which are individually addressable. The proposed system has two 10 cm linear arrays of X-ray sources, each with 50 sources spaced at 2 mm. The two source arrays form two contiguous sides of a square, and two 10 cm area detectors form the other two sides of the square. We estimate that this results in an effective field of view of a 3.2 cm diameter cylinder, suitable for a mouse. No motion of source or subject is needed; simply flashing the individual sources creates angular sampling for tomography, though it is a limited-angle problem. We demonstrate implementations of two iterative reconstruction techniques, block-iterative transmission (BIT) and ordered-subsets convex (OSC). Using data simulated from a realistic mouse phantom, we study the reconstruction quantitative accuracy, point spread functions and noise responses at several locations in the field of view. We demonstrate that the reconstructions are quantitatively accurate and mostly free from disturbing artifacts, while the point spread functions in this geometry are anisotropic and spatially-varying. The OSC algorithm converges faster, showing better resolution yet worse noise performance than BIT after five iterations. We conclude that the proposed geometry is viable for fast, high-resolution and motion-free imaging","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124582004","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596646
K. Gilland, B. Tsui, G. Gullberg
This study compared parallel-hole (PH), fan-beam (FB) and cone-beam (CB) collimation acquisition methods for myocardial perfusion, 99mTc-sestamibi myocardial SPECT imaging. For the task of myocardial defect detection, the channelized Hotelling observer (CHO) was used to compute the area under the ROC curve (AUC) in simulated SPECT images acquired using one of the following 5 single-detector acquisition methods: parallel-hole with 360deg acquisition (PH360), parallel-hole with 180deg acquisition (PH180), fan-beam with 360deg acquisition (FB360), fan-beam with 225deg acquisition (FB225), or cone-beam with 360deg acquisition (CB360). Unlike previous studies comparing PH, FB and CB, this study simulated a population of phantoms with variations in anatomy, defects and 99mTc-sestamibi uptake, as seen in actual cardiac SPECT patient images. Monte Carlo simulations were used to generate low noise projection data. Data were scaled to the same total scan time and to clinical count levels before adding Poisson noise. They were reconstructed using iterative OSEM with attenuation correction at various parameter settings. A single short axis (SA) slice was extracted, low-pass filtered at various cutoff frequencies and then rescaled to integer pixel values ranging from 0-255. For each acquisition method, OSEM parameter setting and filter cutoff, the AUC was estimated from 720 images. At the optimum parameter settings, the CB360 method yielded the highest AUC, followed by FB360, FB225, PH180 and PH360. The difference in AUC between the CB360 method and the other methods was statistically significant (p<0.05)
{"title":"A channelized Hotelling observer study comparing cone-beam, fan-beam and parallel-hole collimation in /sup 99m/Tc-sestamibi myocardial SPECT with a heterogeneous phantom population","authors":"K. Gilland, B. Tsui, G. Gullberg","doi":"10.1109/NSSMIC.2005.1596646","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596646","url":null,"abstract":"This study compared parallel-hole (PH), fan-beam (FB) and cone-beam (CB) collimation acquisition methods for myocardial perfusion, 99mTc-sestamibi myocardial SPECT imaging. For the task of myocardial defect detection, the channelized Hotelling observer (CHO) was used to compute the area under the ROC curve (AUC) in simulated SPECT images acquired using one of the following 5 single-detector acquisition methods: parallel-hole with 360deg acquisition (PH360), parallel-hole with 180deg acquisition (PH180), fan-beam with 360deg acquisition (FB360), fan-beam with 225deg acquisition (FB225), or cone-beam with 360deg acquisition (CB360). Unlike previous studies comparing PH, FB and CB, this study simulated a population of phantoms with variations in anatomy, defects and 99mTc-sestamibi uptake, as seen in actual cardiac SPECT patient images. Monte Carlo simulations were used to generate low noise projection data. Data were scaled to the same total scan time and to clinical count levels before adding Poisson noise. They were reconstructed using iterative OSEM with attenuation correction at various parameter settings. A single short axis (SA) slice was extracted, low-pass filtered at various cutoff frequencies and then rescaled to integer pixel values ranging from 0-255. For each acquisition method, OSEM parameter setting and filter cutoff, the AUC was estimated from 720 images. At the optimum parameter settings, the CB360 method yielded the highest AUC, followed by FB360, FB225, PH180 and PH360. The difference in AUC between the CB360 method and the other methods was statistically significant (p<0.05)","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121571733","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596865
D. Xia, Y. Zou, Lifeng Yu, E. Sidky, Xiaochuan Pan
Progress in developing CT image reconstruction algorithms has been rapid in recent years. Some algorithms have been proposed to reconstruct exact ROI images from data that are less than the short scan data. These algorithms allow a reduction of the scanning effort and the radiation dose delivered to the patient. It is important to investigate the noise properties within reconstructed ROI images by use of these new algorithms because they are directly related to the accuracy of disease diagnosis. In this work, we study the noise properties of three reduced scan algorithms: BPF, MDFBP, and FBP
{"title":"Noise properties of the chord-based algorithms for reduced scans","authors":"D. Xia, Y. Zou, Lifeng Yu, E. Sidky, Xiaochuan Pan","doi":"10.1109/NSSMIC.2005.1596865","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596865","url":null,"abstract":"Progress in developing CT image reconstruction algorithms has been rapid in recent years. Some algorithms have been proposed to reconstruct exact ROI images from data that are less than the short scan data. These algorithms allow a reduction of the scanning effort and the radiation dose delivered to the patient. It is important to investigate the noise properties within reconstructed ROI images by use of these new algorithms because they are directly related to the accuracy of disease diagnosis. In this work, we study the noise properties of three reduced scan algorithms: BPF, MDFBP, and FBP","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116852237","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596630
H. de Jong, L. Perk, G. Visser, R. Boellaard, G. V. van Dongen, A. Lammertsma
In this study the imaging characteristics influencing the quantitative accuracy of 68Ga, 124I and 89 Zr were determined and compared to those of 18F using a 3D high resolution PET (high resolution research tomograph, HRRT) scanner. Although there were large discrepancies found in the sensitivity of these isotopes, which can be explained by their positron abundancy, none of the assessed imaging characteristic prevents the isotopes for usage in (high resolution) quantitative PET imaging. Care has to be taken, however, that accurate correction methods are used for dead time, background and scatter, and partial volume
本研究利用三维高分辨率PET (high resolution research tomograph, HRRT)扫描仪确定了影响68Ga、124I和89zr定量精度的成像特性，并与18F进行了比较。虽然在这些同位素的灵敏度上发现了很大的差异，这可以用它们的正电子丰度来解释，但没有任何评估的成像特征阻止同位素用于(高分辨率)定量PET成像。但是，必须注意对死区时间、背景和散射以及部分体积使用精确的校正方法
{"title":"High resolution PET imaging characteristics of /sup 68/Ga, /sup 124/I and /sup 89/Zr compared to /sup 18/F","authors":"H. de Jong, L. Perk, G. Visser, R. Boellaard, G. V. van Dongen, A. Lammertsma","doi":"10.1109/NSSMIC.2005.1596630","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596630","url":null,"abstract":"In this study the imaging characteristics influencing the quantitative accuracy of 68Ga, 124I and 89 Zr were determined and compared to those of 18F using a 3D high resolution PET (high resolution research tomograph, HRRT) scanner. Although there were large discrepancies found in the sensitivity of these isotopes, which can be explained by their positron abundancy, none of the assessed imaging characteristic prevents the isotopes for usage in (high resolution) quantitative PET imaging. Care has to be taken, however, that accurate correction methods are used for dead time, background and scatter, and partial volume","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115356730","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596432
S. Kopp, B. Baller, S. Childress, R. Ford, D. Harris, D. Indurthy, C. Kendziora, C. Moore, Z. Pavlovic, M. Proga, G. Tassotto, R. Zwaska
We present recent beam data from a new design of a profile monitor for proton beams at Fermilab. The monitors, consisting of grids of segmented Ti foils 5 /spl mu/m thick, are secondary-electron emission monitors (SEM's). We review data on the device's precision on beam centroid position, beam width, and on beam loss associated with the SEM material placed in the beam.
{"title":"Segmented foil SEM grids for high-intensity proton beams at Fermilab","authors":"S. Kopp, B. Baller, S. Childress, R. Ford, D. Harris, D. Indurthy, C. Kendziora, C. Moore, Z. Pavlovic, M. Proga, G. Tassotto, R. Zwaska","doi":"10.1109/NSSMIC.2005.1596432","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596432","url":null,"abstract":"We present recent beam data from a new design of a profile monitor for proton beams at Fermilab. The monitors, consisting of grids of segmented Ti foils 5 /spl mu/m thick, are secondary-electron emission monitors (SEM's). We review data on the device's precision on beam centroid position, beam width, and on beam loss associated with the SEM material placed in the beam.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121696612","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596867
S. Huh, D. Burdette, E. Chesi, K. Honscheid, H. Kagan, C. Lacasta, G. Llosá, M. Mikuž, S. Park, W. Rogers, A. Studen, P. Weilhammer, N. Clinthorne
A pixelated silicon positron sensitive imaging probe is under development to precisely localize superficially located tumors accumulating 18F-FDG. 18F-FDG has been a radioisotope of interest mainly because of the high uptake in tumors and the relatively short positron range. Silicon detectors have generally low detection efficiency for high energy photons and can be used for positron detection. We present a pixelated silicon positron sensitive imaging probe that has the 1.4-by-1.4-by-1.0 mm pixel size with equivalent electronic noise of ~1.2 keV FWHM. The small pixel size leads to the high spatial resolution. Probe movement in conjunction with appropriate reconstruction will allow sub-pixel resolution to be achieved. In addition the high energy resolution makes it possible to get depth information from the spectrum of deposited beta energies. We discuss data from Monte Carlo simulations, which will be useful for predicting performance of various configurations of completed devices. Also we report preliminary data from a simple experimental setup
{"title":"A pixelated silicon positron sensitive imaging probe","authors":"S. Huh, D. Burdette, E. Chesi, K. Honscheid, H. Kagan, C. Lacasta, G. Llosá, M. Mikuž, S. Park, W. Rogers, A. Studen, P. Weilhammer, N. Clinthorne","doi":"10.1109/NSSMIC.2005.1596867","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596867","url":null,"abstract":"A pixelated silicon positron sensitive imaging probe is under development to precisely localize superficially located tumors accumulating 18F-FDG. 18F-FDG has been a radioisotope of interest mainly because of the high uptake in tumors and the relatively short positron range. Silicon detectors have generally low detection efficiency for high energy photons and can be used for positron detection. We present a pixelated silicon positron sensitive imaging probe that has the 1.4-by-1.4-by-1.0 mm pixel size with equivalent electronic noise of ~1.2 keV FWHM. The small pixel size leads to the high spatial resolution. Probe movement in conjunction with appropriate reconstruction will allow sub-pixel resolution to be achieved. In addition the high energy resolution makes it possible to get depth information from the spectrum of deposited beta energies. We discuss data from Monte Carlo simulations, which will be useful for predicting performance of various configurations of completed devices. Also we report preliminary data from a simple experimental setup","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115255536","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 : 2005-12-01DOI: 10.1109/NSSMIC.2005.1596797
S.A. Sawyer, E. Frey
Accurate physical measurement of system geometric misalignments is difficult, so an accurate method of estimating the geometric parameters is needed. Several methods have been proposed that involve measuring projections of spheres at multiple projection views. For high resolution microCT systems, the estimation accuracy of the projected position of the sphere center is a critical factor in determining the geometric parameter accuracy. We have investigated several methods for improving the sphere center estimation. We simulated spheres of varying diameters and used several methods to estimate the positions of the projected sphere centers. The estimated center positions served as the input to methods for estimating the geometric parameters in order to assess the effect on geometric parameter accuracy. The center estimation methods investigated included computing the centroid and fitting the projection with a Gaussian or the analytic equation for the cone beam projection of a sphere. We found that the differences between the true and estimated projected center positions were smaller when fitted with the sphere's projection equation. In addition, using smaller spheres resulted in improved estimate accuracy. Using a phantom consisting of three 1 mm diameter spheres and with curve fitting to estimate the position of the spherical center, we were are able to obtain artifact-free reconstructions for a 42 /spl mu/m pixel size on our prototype physical microCT system.
{"title":"Practical improvement of geometric parameter estimation for cone beam microCT imaging","authors":"S.A. Sawyer, E. Frey","doi":"10.1109/NSSMIC.2005.1596797","DOIUrl":"https://doi.org/10.1109/NSSMIC.2005.1596797","url":null,"abstract":"Accurate physical measurement of system geometric misalignments is difficult, so an accurate method of estimating the geometric parameters is needed. Several methods have been proposed that involve measuring projections of spheres at multiple projection views. For high resolution microCT systems, the estimation accuracy of the projected position of the sphere center is a critical factor in determining the geometric parameter accuracy. We have investigated several methods for improving the sphere center estimation. We simulated spheres of varying diameters and used several methods to estimate the positions of the projected sphere centers. The estimated center positions served as the input to methods for estimating the geometric parameters in order to assess the effect on geometric parameter accuracy. The center estimation methods investigated included computing the centroid and fitting the projection with a Gaussian or the analytic equation for the cone beam projection of a sphere. We found that the differences between the true and estimated projected center positions were smaller when fitted with the sphere's projection equation. In addition, using smaller spheres resulted in improved estimate accuracy. Using a phantom consisting of three 1 mm diameter spheres and with curve fitting to estimate the position of the spherical center, we were are able to obtain artifact-free reconstructions for a 42 /spl mu/m pixel size on our prototype physical microCT system.","PeriodicalId":105619,"journal":{"name":"IEEE Nuclear Science Symposium Conference Record, 2005","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121221870","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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