Characterization of 0.5-mm lutetium oxyorthosilicate detector arrays for high-resolution PET applications

We previously built a high-resolution PET scanner (PawPET) using 8 mm thick Lutetium Oxyorthosilicate (LSO) detectors, but it suffers from poor sensitivity. From our prior work we know that unpolished 0.5 mm pitch arrays with Toray reflector are challenging to decode at depths greater than 8 mm. We hypothesize that decoding will improve by polishing the crystal surfaces. We also know that polished arrays with ESR reflector have poor depth encoding performance when the crystal pitch is 1 mm or greater. We hypothesize that light loss will increase with 0.5 mm pitch crystal to the extent that useful depth encoding information can be extracted. In this work, we investigate the performance of two 12 mm thick, 0.5 mm pitch LSO arrays with different surface treatment and reflector materials using single-ended and hybrid dual-ended readout methods. These detectors may serve to improve sensitivity for our high resolution PET applications. We evaluated depth dependence of photopeak position, depth dependence of flood histogram quality, energy resolution and spatial resolution.