A high resolution event positioning circuit and data acquisition system for pre-clinical PET

Functional and anatomic imaging of small animals using PET combined with MRI has been reported to be a valuable tool in the preclinical research. The purpose of this study was to develop high resolution MR compatible PET detector along with event positioning circuit (EPC) and data acquisition system (DAQ) for small animal PET. PET detector modules consisted of a 8 × 8 array of 1.5 × 1.5 × 6 mm³ LYSO, 12.6 × 12.6 × 0.7 mm³ light guide and 4 × 4 array of 3 × 3 mm² MPPC. EPC was developed using Anger positioning algorithm hybriding with position decoder circuit (PDC). DAQ was developed to process the EPC outputs using a TDC, 4-channel ADCs and a 2 GB SDRAM. The flood histogram was obtained to evaluate the capability of discriminating the 64 crystal pixels, and to estimate the energy resolutions of each crystal pixel. Phantom image was obtained with a pair of detector modules and rotating imaging object. Flood histogram showed that all 64 crystals could be resolved. The average energy resolution at 511 keV was ~13.2%. Phantom image could be resolved down to a diameter of 2 mm. The results of this study demonstrate that our developed PET detector, EPC and DAQ presented in this study provided high performance PET parameters and could be utilized for the development of high resolution small animal PET.