{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/104899"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/104899","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Penalized maximum likelihood method for reducing limited-angle artifacts in image reconstructions for a dual-panel high-spatial-resolution pet system","abstract":"Whole-body positron emission tomography (PET) system has limited spatial resolution for imaging human head and neck cancer (HNC) due to the small size of lymph nodes. We are developing a dual-panel high-spatial-resolution PET system for better imaging HNC. The PET system is designed as a dual-panel geometry to consider the patient’s comfort, but the limited angular coverage of the imaging plane leads to distortions in reconstructed images. In this work, we study a penalized maximum likelihood (PML) image reconstruction method for reducing the limited-angle artifacts arising from the insufficient angular sampling. A prior image is pre-reconstructed from a whole-body low-spatial-resolution PET scan. A PML image reconstruction is then performed with a regularization term that penalizes the dissimilarity between the prior image and the image to be reconstructed for the dual-panel PET scan. An update equation with guaranteed monotonic convergence is derived for the PML reconstruction where a resolution model is incorporated into the regularization term. We conduct computer simulations of PET scans of a cylindrical phantom with hot spheres to evaluate the performance of the PML reconstruction method. Our Results show that the deformation of the background and 6-mm and 8-mm diameter hot spheres in the PML reconstruction of the phantom is eliminated with the regularization strength γ being 0.02 or larger, while the deformation of 3-mm and 4-mm diameter spheres is not completely eliminated. The PML reconstruction with an appropriate γ achieves higher contrast recovery coefficient (CRC) of hot spheres than the prior image and can resolve small features like the 3-mm and 4-mm diameter hot spheres which are not resolvable in the prior image. The method proposed in this work makes the dual-panel high-spatial-resolution PET system promising for imaging HNC.","abstract_html":"Whole-body positron emission tomography (PET) system has limited spatial resolution for imaging human head and neck cancer (HNC) due to the small size of lymph nodes. We are developing a dual-panel high-spatial-resolution PET system for better imaging HNC. The PET system is designed as a dual-panel geometry to consider the patient’s comfort, but the limited angular coverage of the imaging plane leads to distortions in reconstructed images. In this work, we study a penalized maximum likelihood (PML) image reconstruction method for reducing the limited-angle artifacts arising from the insufficient angular sampling. A prior image is pre-reconstructed from a whole-body low-spatial-resolution PET scan. A PML image reconstruction is then performed with a regularization term that penalizes the dissimilarity between the prior image and the image to be reconstructed for the dual-panel PET scan. An update equation with guaranteed monotonic convergence is derived for the PML reconstruction where a resolution model is incorporated into the regularization term. We conduct computer simulations of PET scans of a cylindrical phantom with hot spheres to evaluate the performance of the PML reconstruction method. Our Results show that the deformation of the background and 6-mm and 8-mm diameter hot spheres in the PML reconstruction of the phantom is eliminated with the regularization strength γ being 0.02 or larger, while the deformation of 3-mm and 4-mm diameter spheres is not completely eliminated. The PML reconstruction with an appropriate γ achieves higher contrast recovery coefficient (CRC) of hot spheres than the prior image and can resolve small features like the 3-mm and 4-mm diameter hot spheres which are not resolvable in the prior image. The method proposed in this work makes the dual-panel high-spatial-resolution PET system promising for imaging HNC.","abstract_has_math":false,"creators":["Zhang, Hengquan"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Nuclear, Plasma, Radiolgc Engr","degree_department":null,"school":null,"contributors":["Abbaszadeh, Shiva","Meng, Ling Jian"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-08-23T20:00:11Z","date_published":"2019-08-23T20:00:11Z","updated_at":"2026-07-22T22:24:42Z","subjects":["Limited-angle artifacts","Positron emission tomography","Penalized maximum-likelihood image reconstruction"],"languages":["en"],"rights":["Copyright 2019 Hengquan Zhang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/104899","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Abbaszadeh, Shiva","Meng, Ling Jian"]},{"key":"dc:creator","label":"Author","values":["Zhang, Hengquan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-08-23T20:00:11Z","2019-04-23","2019-05"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear, Plasma, Radiolgc Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Limited-angle artifacts","Positron emission tomography","Penalized maximum-likelihood image reconstruction"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2019 Hengquan Zhang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/104899"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Whole-body positron emission tomography (PET) system has limited spatial resolution for imaging human head and neck cancer (HNC) due to the small size of lymph nodes. We are developing a dual-panel high-spatial-resolution PET system for better imaging HNC. The PET system is designed as a dual-panel geometry to consider the patient’s comfort, but the limited angular coverage of the imaging plane leads to distortions in reconstructed images. In this work, we study a penalized maximum likelihood (PML) image reconstruction method for reducing the limited-angle artifacts arising from the insufficient angular sampling. A prior image is pre-reconstructed from a whole-body low-spatial-resolution PET scan. A PML image reconstruction is then performed with a regularization term that penalizes the dissimilarity between the prior image and the image to be reconstructed for the dual-panel PET scan. An update equation with guaranteed monotonic convergence is derived for the PML reconstruction where a resolution model is incorporated into the regularization term. We conduct computer simulations of PET scans of a cylindrical phantom with hot spheres to evaluate the performance of the PML reconstruction method. Our Results show that the deformation of the background and 6-mm and 8-mm diameter hot spheres in the PML reconstruction of the phantom is eliminated with the regularization strength γ being 0.02 or larger, while the deformation of 3-mm and 4-mm diameter spheres is not completely eliminated. The PML reconstruction with an appropriate γ achieves higher contrast recovery coefficient (CRC) of hot spheres than the prior image and can resolve small features like the 3-mm and 4-mm diameter hot spheres which are not resolvable in the prior image. The method proposed in this work makes the dual-panel high-spatial-resolution PET system promising for imaging HNC.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-08-22 without embargo terms","The student, Hengquan Zhang, accepted the attached license on 2019-04-22 at 13:51.","The student, Hengquan Zhang, submitted this Thesis for approval on 2019-04-22 at 13:57.","This Thesis was approved for publication on 2019-04-23 at 16:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13820 on 2019-08-22 at 14:45:31","Made available in DSpace on 2019-08-23T20:00:11Z (GMT). No. of bitstreams: 2 ZHANG-THESIS-2019.pdf: 1966984 bytes, checksum: 00c0456530fe0035b7679f37b781d211 (MD5) LICENSE.txt: 4211 bytes, checksum: 90e6d623e6059beffe775f5e0b225c3a (MD5) Previous issue date: 2019-04-23"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Penalized maximum likelihood method for reducing limited-angle artifacts in image reconstructions for a dual-panel high-spatial-resolution pet system"]}]}],"canonical_facts":{"dc:contributor":["Abbaszadeh, Shiva","Meng, Ling Jian"],"dc:creator":["Zhang, Hengquan"],"dc:date":["2019-08-23T20:00:11Z","2019-04-23","2019-05"],"dc:description":["Whole-body positron emission tomography (PET) system has limited spatial resolution for imaging human head and neck cancer (HNC) due to the small size of lymph nodes. We are developing a dual-panel high-spatial-resolution PET system for better imaging HNC. The PET system is designed as a dual-panel geometry to consider the patient’s comfort, but the limited angular coverage of the imaging plane leads to distortions in reconstructed images. In this work, we study a penalized maximum likelihood (PML) image reconstruction method for reducing the limited-angle artifacts arising from the insufficient angular sampling. A prior image is pre-reconstructed from a whole-body low-spatial-resolution PET scan. A PML image reconstruction is then performed with a regularization term that penalizes the dissimilarity between the prior image and the image to be reconstructed for the dual-panel PET scan. An update equation with guaranteed monotonic convergence is derived for the PML reconstruction where a resolution model is incorporated into the regularization term. We conduct computer simulations of PET scans of a cylindrical phantom with hot spheres to evaluate the performance of the PML reconstruction method. Our Results show that the deformation of the background and 6-mm and 8-mm diameter hot spheres in the PML reconstruction of the phantom is eliminated with the regularization strength γ being 0.02 or larger, while the deformation of 3-mm and 4-mm diameter spheres is not completely eliminated. The PML reconstruction with an appropriate γ achieves higher contrast recovery coefficient (CRC) of hot spheres than the prior image and can resolve small features like the 3-mm and 4-mm diameter hot spheres which are not resolvable in the prior image. The method proposed in this work makes the dual-panel high-spatial-resolution PET system promising for imaging HNC.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-08-22 without embargo terms","The student, Hengquan Zhang, accepted the attached license on 2019-04-22 at 13:51.","The student, Hengquan Zhang, submitted this Thesis for approval on 2019-04-22 at 13:57.","This Thesis was approved for publication on 2019-04-23 at 16:38.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13820 on 2019-08-22 at 14:45:31","Made available in DSpace on 2019-08-23T20:00:11Z (GMT). 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