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Abbaszadeh, Shiva Meng, Ling Jian Zhang, Hengquan 2019-08-23T20:00:11Z 2019-08-23T20:00:11Z 2019-04-23 2019-05 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 application/pdf http://hdl.handle.net/2142/104899 en Copyright 2019 Hengquan Zhang Limited-angle artifacts Positron emission tomography Penalized maximum-likelihood image reconstruction Penalized maximum likelihood method for reducing limited-angle artifacts in image reconstructions for a dual-panel high-spatial-resolution pet system text text Nuclear, Plasma, & Rad Engr Nuclear, Plasma, Radiolgc Engr University of Illinois at Urbana-Champaign Thesis M.S.