1 mm isotropic detector resolution achieved by X´tal cube detector

The X´tal cube is our new PET detector which is composed of a segmented crystal block and multi-pixel photon counters (MPPCs). It detects scintillation photons in three dimensions by arranging MPPCs on multiple surfaces of the crystal block. It is possible to collect scintillation photons efficiently for higher energy, spatial, and timing resolution. We have previously reported that 3 mm isotropic spatial resolution was obtained using the X´tal cube. In this study, we achieved 1 mm isotropic spatial resolution. The developed X´tal cube detector was composed of 1.0 × 1.0 × 1.0 mm³ LYSO crystals, which were structured into 16 × 16 × 16 arrays. Each surface of the crystal block was covered with 4×4 MPPCs with 3.0 mm × 3.0 mm sensitive area. We evaluated crystal identification and energy performance, and the results showed that the X´tal cube has the expected 1 mm isotropic spatial resolution.