title: Transaxial system models for jPET-D4 image reconstruction.
abstract: A high-performance brain PET scanner, jPET-D4, which provides four-layer depth-of-interaction (DOI) information, is being developed to achieve not only high spatial resolution, but also high scanner sensitivity. One technical issue to be dealt with is the data dimensions which increase in proportion to the square of the number of DOI layers. It is, therefore, difficult to apply algebraic or statistical image reconstruction methods directly to DOI-PET, though they improve image quality through accurate system modelling. The process that requires the most computational time and storage space is the calculation of the huge number of system matrix elements. The DOI compression (DOIC) method, which we have previously proposed, reduces data dimensions by a factor of 1/5. In this paper, we propose a transaxial imaging system model optimized for jPET-D4 with the DOIC method. The proposed model assumes that detector response functions (DRFs) are uniform along line-of-responses (LORs). Then each element of the system matrix is calculated as the summed intersection lengths between a pixel and sub-LORs weighted by a value from the DRF look-up-table. 2D numerical simulation results showed that the proposed model cut the calculation time by a factor of several hundred while keeping image quality, compared with the accurate system model. A 3D image reconstruction with the on-the-fly calculation of the system matrix is within the practical limitations by incorporating the proposed model and the DOIC method with one-pass accelerated iterative methods.
authors.affiliation: National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. taiga@nirs.go.jp
authors.forename: Taiga
authors.initials: T
authors.lastname: Yamaya
authors.forename: Naoki
authors.initials: N
authors.lastname: Hagiwara
authors.forename: Takashi
authors.initials: T
authors.lastname: Obi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Nagaaki
authors.initials: N
authors.lastname: Ohyama
authors.forename: Keishi
authors.initials: K
authors.lastname: Kitamura
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Haneishi
authors.forename: Eiji
authors.initials: E
authors.lastname: Yoshida
authors.forename: Naoko
authors.initials: N
authors.lastname: Inadama
authors.forename: Hideo
authors.initials: H
authors.lastname: Murayama
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging; D003198:Computer Simulation; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D016012:Poisson Distribution; D049268:Positron-Emission Tomography / Q000379:methods*; D013997:Time Factors