The design and implementation of COSEM, an iterative algorithm for fully 3-D listmode data

In this paper,we present coincidence-list-ordered sets expectation-maximiza tion (COSEM), an algorithm for iterative image reconstruction directly from list-mode coincidence acquisition data, The COSEM algorithm is based on th e ordered sets EM: algorithm for binned data but has several extensions tha t makes it suitable for rotating two planar detector tomographs. We develop the COSEM algorithm and extend it to include analytic calculation of detec tion probability, noise reducing iterative filtering schemes, and on-the-fl y attenuation correction methods. me present an adaptation of COSEM to the Varicam\VG camera and show results from clinical and phantom studies.