On convergence analysis of an accelerated EM algorithm for SPECT imaging

The EM algorithm is an effective reconstruction method for SPECT, because it can incorporate various physical factors into reconstruction. However, the convergence rate is very slow. One of the accelerated means is increasing the iterative step length. Though it can speed up the iterative process, whether the modified algorithm will converge is still a question worth with in-depth exploration. In this article, we propose a modified accelerating algorithm and study its convergence characteristics in the modified iterative algorithm, and we also present a few numerical experiments.