SiPM signal readout for inter-crystal scatter event identification in PET detectors.

In this study, we propose a novel silicon photomultiplier (SiPM) readout method to identify ICS events in one-to-one coupled PET detectors with a reduced number of data acquisition channels. For concept verification, we assembled a PET detector that consists of a 16-channel SiPM array and 4×4 lutetium oxyorthosilicate (LSO) array with a 3.2-mm crystal pitch. The proposed SiPM readout scheme serializes the 16 SiPM anode signals into four pulse train outputs encoded with four increasing time-delays in steps of 250-ns intervals. A Sum signal of the 16 SiPM anodes provides the timing information for time-of-flight measurement and a trigger signal for coincidence detection. A time-over-threshold (TOT) method was applied for obtaining the energy information followed by a subsequent TOT-to-energy calibration. We successfully identified the ICS events and determined their interacted positions and deposited energies by analyzing the digital pulses from the four pulse train output channels. The occurrence rate of ICS events was 10.85% for the 4×4 PET detector module with 3.2-mm-pitch LSO crystals. The PET detector yielded an energy resolution of 10.9±0.6% and coincidence timing resolution of 285±12 ps FWHM. We expect that the proposed method can be a useful solution for alleviating the readout burden of SiPM-based PET scanners with ICS event identification capability.
PMID: 32702670 [PubMed - as supplied by publisher]

Source: Physics in Medicine and Biology - July 22, 2020 Category: Physics Authors: Park H, Lee JS Tags: Phys Med Biol Source Type: research