Discrimination of inter-crystal scattering events by signal processing for the X'tal cube PET detector

In this study, we proposed a method to discriminate the ICS events and showed its feasibilit y by the following method. For each 96 MPPC, we measured the mean and standard deviation of the peak in the pulse height distribution obtained by the photoabsorption events in a scintillator pixel. Every time a newly detected event was identified as the segment, we monitored the reduced chi-square v alue that was calculated with the pulse height and the prepared mean and the standard deviation for each 96 MPPC. Since the pulse height caused by the photoabsorption event resulted in a small reduced chi-square value, we could eliminate the ICS events by setting a threshold on the reduced chi-squar e value. We carried out both a Monte Carlo simulation and a scanning experiment. By the simulation, we confirmed that the threshold of the reduced chi square significantly discriminated the ICS event. We obtained the response function by a scanning experiment with a 0.2 mm slit beam of 511 keV gam ma-ray. The standard deviation of the response function was improved from 1.6 to 1.06 mm by eliminating the ICS events. The proposed method could significantly eliminate the ICS events and retain the true events.

Source: Radiological Physics and Technology - October 2, 2023 Category: Physics Source Type: research