PET Detectors Based on Multi-Resolution SiPM Arrays.

Almost all high spatial resolution positron emission tomography (PET) detectors based on pixelated scintillator arrays utilize crystal arrays with smaller pitches than photodetector arrays, leading to challenges in resolving edge crystals. To address this issue, this paper introduces a novel multi-resolution silicon photomultiplier (SiPM) array design aimed at decreasing the number of readout channels required while maintaining the crystal resolvability of the detector, especially for edge crystals. The performance of a pseudo 9 × 9 multi-resolution SiPM array, consisting of 6.47 × 6.47 mm, 6.47 × 3.07 mm, and 3.07 × 3.07 mm SiPMs, was compared to those of a pseudo 8 × 8 SiPM array with a 6.8 mm pitch, and a 16 × 16 SiPM array with a 3.4 mm pitch using a 36 × 36 LYSO array with a pitch of 1.5 mm. The large-size pseudo SiPMs were implemented by digitally grouping multiple 3.07 × 3.07 mm SiPMs. The flood histograms show that the edge crystal resolvability of the pseudo 9 × 9 multi-resolution SiPM array is comparable to that of the 16 × 16 SiPM array and is significantly better than that of the 8 × 8 SiPM array.