title: Noise and edge artifacts in maximum-likelihood reconstructions for emission tomography.
abstract: Images produced in emission tomography with the expectation-maximization algorithm have been observed to become more noisy and to have large distortions near edges as iterations proceed and the images converge towards the maximum-likelihood estimate. It is our conclusion that these artifacts are fundamental to reconstructions based on maximum-likelihood estimation as it has been applied usually; they are not due to the use of the expectation-maximization algorithm, which is but one numerical approach for finding the maximum-likelihood estimate. In this paper, we develop a mathematical approach for suppressing both the noise and edge artifacts by modifying the maximum-likelihood approach to include constraints which the estimate must satisfy.
authors.forename: D L
authors.initials: DL
authors.lastname: Snyder
authors.forename: M I
authors.initials: MI
authors.lastname: Miller
authors.forename: L J
authors.initials: LJ
authors.lastname: Thomas
authors.forename: D G
authors.initials: DG
authors.lastname: Politte