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

Planar large field-of-view gamma camera detectors in coincidence imaging are characterized by a high singles count rate, leading to a high acquired random coincidence rate. We propose and compare two methods to correct the random coincidences that account for the variation of the random count rate during the detector rotation. One method consists of using a uniform distribution 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 coincidences inside the object and an overestimation outside the object. The distribution of the random coincidences is better estimated with the SPD method, which allows one to recover contrast values closer to those expected without randoms background.