An investigation into the use of scattered photons to improve 2D Position Emission Tomography (PET) functional imaging quality

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dc.contributor.authorSun, Hongyan
dc.contributor.examiningcommitteeGoertzen, Andrew (Physics & Astronomy) Lin, Francis (Physics & Astronomy) Sherif, Sherif (Electrical & Computer Engineering) Lecomte, Roger (Université de Sherbrooke)en_US
dc.contributor.supervisorPistorius, Stephen (Physics & Astronomy)en_US
dc.date.accessioned2016-01-12T17:15:11Z
dc.date.available2016-01-12T17:15:11Z
dc.date.issued2013en_US
dc.date.issued2014en_US
dc.date.issued2015en_US
dc.date.issued2012en_US
dc.degree.disciplinePhysics and Astronomyen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractPositron emission tomography (PET) is a powerful metabolic imaging modality, which is designed to detect two anti-parallel 511 keV photons origniating from a positron-electron annihilation. However, it is possible that one or both of the annihilation photons undergo a Compton scattering in the object. This is more serious for a scanner operated in 3D mode or with large patients, where the scatter fraction can be as high as 40-60%. When one or both photons are scattered, the line of response (LOR) defined by connecting the two relevant detectors no longer passes through the annihilation position. Thus, scattered coincidences degrade image contrast and compromise quantitative accuracy. Various scatter correction methods have been proposed but most of them are based on estimating and subtracting the scatter from the measured data or incorporating it into an iterative reconstruction algorithm. By accurately measuring the scattered photon energy and taking advantage of the kinematics of Compton scattering, two circular arcs (TCA) in 2D can be identified, which describe the locus of all the possible scattering positions and encompass the point of annihilation. In the limiting case where the scattering angle approaches zero, the TCA approach the LOR for true coincidences. Based on this knowledge, a Generalized Scatter (GS) reconstruction algorithm has been developed in this thesis, which can use both true and scattered coincidences to extract the activity distribution in a consistent way. The annihilation position within the TCA can be further confined by adding a patient outline as a constraint into the GS algorithm. An attenuation correction method for the scattered coincidences was also developed in order to remove the imaging artifacts. A geometrical model that characterizes the different probabilities of the annihilation positions within the TCA was also proposed. This can speed up image convergence and improve reconstructed image quality. Finally, the GS algorithm has been adapted to deal with non-ideal energy resolutions. In summary, an algorithm that implicitly incorporates scattered coincidences into the image reconstruction has been developed. Our results demonstrate that this eliminates the need for scatter correction and can improve system sensitivity and image quality.en_US
dc.description.noteFebruary 2016en_US
dc.identifier.citationH. Sun and S. Pistorius, “Evaluation of the Feasibility and Quantitative Accuracy of a Generalized Scatter 2D PET Reconstruction Method,” ISRN Biomedical Imaging, 2013.en_US
dc.identifier.citationH. Sun and S. Pistorius, “Evaluation of Image Quality Improvements When Adding Patient Outline Constraints into a Generalized Scatter PET Reconstruction Algorithm,” ISRN Biomedical Imaging, 2013.en_US
dc.identifier.citationStephen Pistorius, Hongyan Sun, “Systems and Methods for Improving the Quality of Images in a PET Scan,” (Note: the activity distribution reconstruction using scattered coincidences in PET) PCT Publication No.: WO2013177661A1, Date of Publication: Dec 05, 2013 United States Patent Granted, No.: US-8866087, Date of Publication: Jun 12, 2014.en_US
dc.identifier.citationStephen Pistorius, Hongyan Sun, “Systems and Methods for Improving the Quality of Images in a PET Scan,” (Note: the electron density reconstruction using scattered coincidences in PET) United States Patent Pending, No.: US20140374607A1, Date of Publication: Dec 25, 2014.en_US
dc.identifier.citationH. Sun, M. Teimoorisichani, B. McIntosh, G. Zhang, H. Ingleby, A. Goertzen, S. Pistorius, “Simultaneous estimation of the radioactivity distribution and electron density map from scattered coincidences in PET: A project overview”, 2015 World Congress on Medical Physics and Biomedical Engineering, Toronto, Canada, June 7-12, 2015.en_US
dc.identifier.citationH. Sun, S. Pistorius, “Extracting PET activity distribution from scattered coincidences for non-ideal energy resolutions by modeling the probabilities of annihilation positions within a generalized scattering reconstruction algorithm”, 2015 World Congress on Medical Physics and Biomedical Engineering, Toronto, Canada, June 7-12, 2015.en_US
dc.identifier.citationH. Sun, G. Zhang, S. Pistorius, “Turning Noise into Numbers: An investigation into the use of scattered photons to improve PET imaging quality”, 2015 Canadian Radiation Protection Association Conference, Winnipeg, Canada, 2015.en_US
dc.identifier.citationG. Zhang, H. Sun, S. Pistorius, “Electron Density Reconstruction from Scattered Coincidences for Attenuation Correction in Positron Emission Tomography”, The 2015 Fully 3D Reconstruction Meeting, Seattle, Washington, Newport, RI, USA June 1‐4, 2015.en_US
dc.identifier.citationH. Sun, S. Pistorius, “A Generalized Scatter Reconstruction Algorithm for Limited Energy Resolution PET Detectors,” IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS-MIC), Seattle, Washington, Nov 8-15, 2014.en_US
dc.identifier.citationH. Sun, S. Pistorius, “Characterization the annihilation position distribution within a geometrical model associated with scattered coincidences in PET,” IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS-MIC), Seattle, Washington, Nov 8-15, 2014.en_US
dc.identifier.citationG. Zhang, H. Sun, S. Pistorius, “Feasibility of Scatter Based Electron Density Reconstruction for Attenuation Correction in Positron Emission Tomography,” IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS-MIC), Seattle, Washington, Nov 8-15, 2014.en_US
dc.identifier.citationH. Sun, S. Pistorius, “Simultaneous reconstruction of both true and scattered coincidences using a Generalized Scatter reconstruction algorithm in PET,” The Canadian Organization of Medical Physicists (COMP) 60th Annual Scientific Meeting, Banff, Canada, July 9-12, 2014.en_US
dc.identifier.citationH. Sun, S. Pistorius, “Attenuation Correction for a Generalized Scatter Reconstruction Algorithm in PET,” IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS-MIC), Seoul, South Korea, Oct27-Nov2, 2013en_US
dc.identifier.citationH. Sun, S. Pistorius, “Improvements in Image Quality When Using Patient Outline Constraints with a Generalized Scatter PET Reconstruction Algorithm,” IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS-MIC), Anaheim, CA, USA, October 29- November 3, 2012.en_US
dc.identifier.citationH. Sun, S. Pistorius, “A Novel Scatter Enhanced PET Reconstruction Algorithm,” 2012 World Congress on Medical Physics and Biomedical Engineering, Beijing, China, May 26-31, 2012.en_US
dc.identifier.urihttp://hdl.handle.net/1993/31031
dc.language.isoengen_US
dc.publisherHindawi Publishing Corporationen_US
dc.publisherUnited States Patent and Trademark Officeen_US
dc.publisherWorld Congress on Medical Physics and Biomedical Engineeringen_US
dc.publisherCanadian Radiation Protection Associationen_US
dc.publisherFully 3D Reconstruction Meetingen_US
dc.publisherIEEE Nuclear Science Symposium & Medical Imaging Conferenceen_US
dc.publisherThe Canadian Organization of Medical Physicistsen_US
dc.rightsopen accessen_US
dc.subjectpositron emission tomographyen_US
dc.subjectscattered coincidencesen_US
dc.subjectactivity reconstructionen_US
dc.subjectelectron density mapen_US
dc.subjectscattering reconstructionen_US
dc.titleAn investigation into the use of scattered photons to improve 2D Position Emission Tomography (PET) functional imaging qualityen_US
dc.typedoctoral thesisen_US
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