LabPET inter-crystal scatter study using GATE

Using GATE, the Geant4 application for tomographic emission, the inter-crystal scatter (ICS) in the LabPET scanner has been characterized with respect to detection efficiency and quantification, for different energy thresholds and gamma ray incidence angles. Simulations have shown that for a direct angle of incidence and an energy threshold of 350 keV, the number of the ICS events is estimated to be 8% of the total recorded events. By lowering the energy threshold from 350 keV to 0 keV, the detection efficiency of the primary events increases by nearly a factor of 3; however at 0 keV the number of the ICS events is estimated to be 26% of the total recorded events and their distribution is expanded over the whole scanner. Finally, it has been shown that for all thresholds oblique angles of incidence have a negligible effect on the fraction of the ICS events but may change their spatial distribution.