Performance of high-resolution PET detectors consisting of long GAGG slabs with different reflectors

In this work, the performance of two semi-monolithic scintillator detectors composed of GAGG slabs was investigated for the first time. The detector using the ESR reflector achieved similar y-position and DOI resolutions, slightly better energy resolution, and a poorer flood histogram compared to the detector using the BaSO₄ reflector. Both detectors clearly identified all scintilator slabs with a thickness of 0.96 mm, achieved y-position resolutions of ~ 1.6 mm, DOI resolutions of ~ 2.3 mm, and energy resolutions of ~ 15%. These detectors are suitable for developing small-animal and high-resolution organ-specific PET scanners.