Correction for the random coincidences in dual-head gamma camera imaging

Planar large field-of-view gamma camera detectors in coincidence imaging ar e characterized by a high singles count rate, leading to a high acquired ra ndom coincidence rate. We propose and compare two methods to correct the ra ndom coincidences that account for the variation of the random count rate d uring the detector rotation. One method consists of using a uniform distrib ution for the random coincidences (UD) and the other is based on the single photon distribution (SPD) on each detector. Unlike the UD method, the SPD method accounts for the variation of the spatial distribution of the random coincidences. The UD method leads to an underestimation of the random coin cidences inside the object and an overestimation outside the object. The di stribution of the random coincidences is better estimated with the SPD meth od, which allows one to recover contrast values closer to those expected wi thout randoms background.