Evaluation of high-resolution and depth-encoding PET detector modules based on single-ended readout with TOFPET2 ASIC

Purpose We developed a low-complexity, high-resolution depth-of-interaction (DOI) capable positron emission tomography (PET) detector and tested its performance to prove that it can be applied to practical PET instruments.
Methods The detector module consists of a 24 × 24 LYSO crystal matrix, each with dimension of 1.04 × 1.04 × 15mm³, optically coupled to an 8 × 8 SiPM photo-sensor array with TOFPET2 ASIC single-ended readout. By only adding a light guide at the top of the crystal to reflect scintillation light back to the SiPM array, the continuous DOI information is extracted using a light sharing and redirection encoding method without adding system complexity.
Results The crystal array with 9-to-1 coupling between scintillators and photo-sensors can be clearly separated in the flood image. The other detector performance in terms of DOI resolution, energy resolution and coincidence time resolution are measured on average as 4.1 mm, 15.0% and 432 ps, respectively.
Conclusion The test results confirm that the light sharing and redirection DOI encoding method can provide reasonably high DOI resolution without deteriorating other performance, even for highly pixelated PET detectors readout with commercially available ASIC chip. It has great potential for applications in future pre-clinical and organ-dedicated PET scanners.