title: Enhanced 3D PET OSEM reconstruction using inter-update Metz filtering.
abstract: We present an enhancement of the OSEM (ordered set expectation maximization) algorithm for 3D PET reconstruction, which we call the inter-update Metz filtered OSEM (IMF-OSEM). The IMF-OSEM algorithm incorporates filtering action into the image updating process in order to improve the quality of the reconstruction. With this technique, the multiplicative correction image--ordinarily used to update image estimates in plain OSEM--is applied to a Metz-filtered version of the image estimate at certain intervals. In addition, we present a software implementation that employs several high-speed features to accelerate reconstruction. These features include, firstly, forward and back projection functions which make full use of symmetry as well as a fast incremental computation technique. Secondly, the software has the capability of running in parallel mode on several processors. The parallelization approach employed yields a significant speed-up, which is nearly independent of the amount of data. Together, these features lead to reasonable reconstruction times even when using large image arrays and non-axially compressed projection data. The performance of IMF-OSEM was tested on phantom data acquired on the GE Advance scanner. Our results demonstrate that an appropriate choice of Metz filter parameters can improve the contrast-noise balance of certain regions of interest relative to both plain and post-filtered OSEM, and to the GE commercial reprojection algorithm software.
authors.affiliation: MINERVA Optimization Center, Technion, Haifa, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Jacobson
authors.forename: R
authors.initials: R
authors.lastname: Levkovitz
authors.forename: A
authors.initials: A
authors.lastname: Ben-Tal
authors.forename: K
authors.initials: K
authors.lastname: Thielemans
authors.forename: T
authors.initials: T
authors.lastname: Spinks
authors.forename: D
authors.initials: D
authors.lastname: Belluzzo
authors.forename: E
authors.initials: E
authors.lastname: Pagani
authors.forename: V
authors.initials: V
authors.lastname: Bettinardi
authors.forename: M C
authors.initials: MC
authors.lastname: Gilardi
authors.forename: A
authors.initials: A
authors.lastname: Zverovich
authors.forename: G
authors.initials: G
authors.lastname: Mitra
mesh_terms: D000465:Algorithms; D055592:Biophysical Phenomena; D001703:Biophysics; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D019047:Phantoms, Imaging; D012984:Software; D014055:Tomography, Emission-Computed / Q000295:instrumentation* / Q000379:methods*