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 maxi-mum-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.
Original language | English |
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Pages (from-to) | 228-238 |
Number of pages | 11 |
Journal | IEEE Transactions on Medical Imaging |
Volume | 6 |
Issue number | 3 |
DOIs | |
State | Published - Sep 1987 |