Impact of intercrystal crosstalk on depth-of-interaction information in PET detectors

We have investigated the impact of intercrystal crosstalk on the spatial resolution of whole body PET detectors with different depth-of-interaction (DOI) readout schemes by validated Monte Carlo simulations. Both discrete and continuous readout schemes were analyzed. Detectors made of materials with different stopping power (LYSO, LaBr₃) and different crystals sizes were modeled. The results show a similar improvement for the FWHM of the resolution across the field of view for all investigated methods. For the FWTM of the resolution especially the discrete approach using two offset layers of crystals suffers from intercrystal scatter. Continuous DOI readout shows the best results for the FWTM. Since the accuracy of continuous DOI information can be gradually increased, it has the potential to outperform discrete DOI readout using two layers of scintillator crystals. We show examples of experimental DOI extraction for the discrete approach using two offset layers and continuous DOI readout with monolithic crystals.