Optimization of a partially segmented block detector for MR-compatible small animal PET

In recent years, there has been an increasing interest in the magnetic resonance (MR)-compatible positron emission tomography (PET) scanners for both clinical and preclinical practice. The aim of this study was to design a novel PET detector module using a segmented block crystal readout with an array of multi-pixel photon counters (MPPCs). A 16.5×16.5×10.0 mm3 LSO block was segmented into an 11×11 array, and reflective material was used to fill in the cuts to optically isolate the elements. The block was attached to a 4×4 MPPC array (Hamamatsu S11064) of 3.0×3.0 mm2 detectors to give a total effective area of 144 mm2. To visualize all the individual detector elements in this 11×11 detector module, the depth of the cuts was optimized by DETECT2000 simulations. The depth of the cuts determines the spread of scintillation light onto the MPPC array. The accuracy of positioning was evaluated by varying the depth of the cuts from 0.0 to 10.0 mm in steps of 0.5 mm. A spatial resolution of 1.5 mm was achieved using the optimized partially segmented block detector. The simulation results of this study can be used effectively as a guide for parameter optimization for the development of a partially segmented block detector for high-resolution MR-compatible PET scanners.