Performance evaluation of neuro-PET using silicon photomultipliers

Recently, we have developed the second prototype Silicon photomultiplier (SiPM) based positron emission tomography (PET) scanner for human brain imaging. The PET system was comprised of detector block which consisted of 4×4 SiPMs and 4×4 Lutetium Yttrium Orthosilicate arrays, charge signal transmission method, high density position decoder circuit and FPGA-embedded ADC boards. The purpose of this study was to evaluate the performance of the newly developed neuro-PET system. The energy resolution, timing resolution, spatial resolution, sensitivity, stability of the photo-peak position and count rate performance were measured. Tomographic image of 3D Hoffman brain phantom was also acquired to evaluate imaging capability of the neuro-PET. The average energy and timing resolutions measured for 511keV gamma rays were 17±0.1% and 3±0.3ns, respectively. Spatial resolution and sensitivity at the center of field of view (FOV) were 3.1mm and 0.8%, respectively. The average scatter fraction was 0.4 with an energy window of 350–650keV. The maximum true count rate and maximum NECR were measured as 43.3kcps and 6.5kcps at an activity concentration of 16.7kBq/ml and 5.5kBq/ml, respectively. Long-term stability results show that there was no significant change in the photo-peak position, energy resolution and count rate for 60 days. Phantom imaging studies were performed and they demonstrated the feasibility for high quality brain imaging. The performance tests and imaging results indicate that the newly developed PET is useful for brain imaging studies, if the axial FOV is extended to improve the system sensitivity.