An EM algorithm for dynamic SPECT

In this paper me present two variants of the EM algorithm for dynamic SPECT imaging. A version based on compartmental modeling which fits a sum of exp onentials and a more general approach allowing for arbitrary decaying activ ities. The underlying probabilistic models are discussed and the incomplete and complete data spaces are shown to be physically meaningful, We indicat e that the second method, leading to a convex program in the M step, is eas ier to treat numerically and we present a possible numerical approach. Some preliminary numerical tests indicating the feasibility of the method are i ncluded.