Fig. 1
From: Physics of pure and non-pure positron emitters for PET: a review and a discussion
Three mechanisms associated with prompt gamma spurious coincidences: a 124I has a prompt gamma of energy within or close to the PET energy window (603 keV); b 68Ga has a prompt gamma of energy that can enter the PET energy window if it undergoes Compton scatter (1077 keV); and c 76Br has several high-energy gammas that can reach the detectors and generate e +/e − pairs