Improving PET Sensitivity and Resolution by Photon Interaction Sequence Timing Discrimination

Detectors for current PET scanners are based on the detection of the photoelectric energy peak while information from Compton scattering is being rejected. If an event involves multiple Compton scattering and the total energy deposited lays within the photoelectric peak, then a energy-weighted average is given for the interaction point. This technique introduces blurring in the image reconstruction process. We show that one can drastically improve the quality of the final reconstructed image, by precisely knowing the coordinates of the first interaction point. Compton events are rich source of information and one can also use them in order to discard random, single or even patient scattered events by means of reconstructing the Compton cones and require them to be compatible (Compton cones for photons that come from the same event must intersect in a line of response). In order to fully benefit experimentally from Compton events using monolithic scintillators a multi layer configuration is needed.