title: Three-dimensional maximum-likelihood reconstruction for an electronically collimated single-photon-emission imaging system.
abstract: A three-dimensional maximum-likelihood reconstruction method is presented for a prototype electronically collimated single-photon-emission system. The electronically collimated system uses a gamma camera fronted by an array of germanium detectors to detect gamma-ray emissions from a distributed radioisotope source. In this paper we demonstrate that optimal iterative three-dimensional reconstruction approaches can be feasibly applied to emission imaging systems that have highly complex spatial sampling patterns and that generate extremely large numbers of data values. A probabilistic factorization of the system matrix that reduces the computation by several orders of magnitude is derived. We demonstrate a dramatic increase in the convergence speed of the expectation maximization algorithm by sequentially iterating over particular subsets of the data. This result is also applicable to other emission imaging systems.
authors.affiliation: Department of Electrical Engineering, University of Houston, Texas 77204-4793.
authors.forename: T
authors.initials: T
authors.lastname: Hebert
authors.forename: R
authors.initials: R
authors.lastname: Leahy
authors.forename: M
authors.initials: M
authors.lastname: Singh
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008433:Mathematics; D015899:Tomography, Emission-Computed, Single-Photon