We propose a stopping criterion for the EM-MLE algorithm for PET, based on the properties of the multiplicative correction factors (Delta) x applied to the image vector after each iteration. The criterion is based on the relationship between the image quality descriptors and the statistical properties of the updating coefficients. Our study was performed with Monte Carlo-generated projections initially for an ideal scanner and noise-free case, in order to study the properties of the algorithm. It was then extended to include realistic data from the Hoffman brain phantom, by detailed Monte Carlo simulation of scattering, absorption, random and multiple coincidences, including a Monte Carlo simulation of the transmission scan for attenuation correction. The criterion has been applied to reconstructions from real data from the CTI-831 NeuroPET scanner. The stopping criterion as well as results from reconstructions of measured projection data are discussed.

Date Published: 16 April 1996
PDF: 12 pages
Proc. SPIE 2710, Medical Imaging 1996: Image Processing, (16 April 1996); doi: 10.1117/12.237917

Published in SPIE Proceedings Vol. 2710:
Medical Imaging 1996: Image Processing
Murray H. Loew; Kenneth M. Hanson, Editor(s)