High spatial resolution dual-ended readout PET detector based on continuous resistive layer silicon photomultiplier

Continuous resistive layer position-sensitive silicon photomultiplier (CRL PS-SiPM) is a class of position-sensitive SiPMs developed for the readout of fine-pitch scintillator crystal arrays. This study aimed to evaluate the performance of dual-ended readout positron emission tomography (PET) detectors based on CRL PS-SiPMs and 0.5 mm pitch LYSO arrays.

A dual-ended readout detector was constructed by coupling two CRL PS-SiPMs to both ends of a 10 × 10 array of polished LYSO elements, each measuring 0.44 × 0.44 × 20 mm³. Each CRL PS-SiPM had an active area of 6.24 × 6.24 mm² and was fabricated using 20 µm microcells. Detector performance, including flood histogram quality, energy resolution, and coincidence timing resolution, was characterized at bias voltages ranging from 30.0 to 33.0 V in 0.5 V increments, and at 3 °C, 14 °C, and 24 °C. Depth-of-interaction (DOI) resolution was evaluated at the optimal bias voltage determined from the flood histogram and at all three temperatures.

Temperature had a negligible effect on detector performance, indicating that CRL PS-SiPMs are practical photodetector candidates for high spatial resolution PET scanners. All LYSO crystals were clearly resolved in the flood histograms. At 24 °C and a bias voltage of 32.5 V, which provided the best flood histogram, the average energy resolution, coincidence timing resolution, and DOI resolution across all crystals were 22.7 ± 3.4%, 1152 ± 43 ps, and 1.78 ± 0.20 mm, respectively.

These results demonstrate that CRL PS-SiPMs are promising photodetectors for high spatial resolution PET applications, particularly for systems requiring detectors with sub-millimeter pitch scintillator crystal arrays and DOI capability.