Initial Performance Evaluation of a Compact Add-on PET Scanner for Small Animal PET/CT/RT: A Rotating Dual Detector Panel Study

The objective of this study was to evaluate the data acquisition, process and imaging performance with two PET detector panels for assessing the potential imaging performance of the PET to be with 12 such detector panels. Each detector panel (DP) consistes of four 15×15 arrays of 1×1×20 mm³ LYSO scintillators, with the two array ends optically coupled to four size-matching 8×8 arrays of 2×2 mm² SiPMs. A compact 96-channel signal readout and processing electronics based on FPGA-controlled charge integration and fast linear discharging QDC was developed for acquiring coincidence events. In the experiment setup , two constructed detector panels were placed on a rotating stage for imaging study, with a 150 mm crystal-to-crystal distance; the effective field of view (FOV) by the two rotating panels was 35mm in diameter; a Na-22 point source was placed within the FOV; coincidence data were acquired from six different angles over 180^o, with a 30^o interval between angular positions and a 30 seconds acquisition at each angle. Coincidence data were recorded in list-mode and reconstructed offline with MLEM algorithm. The measured mean image resolution (FWHM) was 0.79 mm over 30 images of the poin soure at different positions over the FOV. In addition, the coincidence intrinsic detector spatial resolution was 1.03 mm measured from the coincidence counts distribution of crystal pairs with the point at different positions over the FOV. In summary, the initial dual detector panel based imaging study shows expected good image resolution and the performance at system acquisition level, which projects good system and imaging performance of the full PET that is under construction. More evaluation studies, including a hot-rod small phantom iamge and potentially full PET system capabitlily, will be presented in the conference.