Initial implementation of LYSO-PSPMT block detector with an all digital DAQ system

An all-digital positron emission tomography (PET) scanner for imaging small animals has been developed at Huazhong University of Science and Technology (HUST). The implementation of block detector with position sensitive photomultiplier (PSPMT) and multi-voltage threshold (MVT) technology is presented in this paper. The detector comprises 12 basic detector modules (BDMs), which can be used to construct various types of PET scanner architecture due to the modularized design. Each BDM is composed of a detector unit (DU) and a digital processing unit (DPU). The scintillation pulses are obtained in DU, from which the time, energy and position can be derived and processed in DPU by using digital signal processing (DSP) algorithm. Then coincidence data and list-mode data can be obtained in soft singles processing unit (SSPU). We arrange two BDMs as a dual-head PET scanner to evaluate the system. Our results show that the average energy resolution is ~14%@511 keV full-width-at-half-maximum (FWHM) and the coincidence time determination is ~1.38 ns FWHM. Moreover, the reconstructed image of a homemade micro-Derenzo phantom shows that the rods with a diameter of 1.6 mm can be clearly distinguished. The results are promising and demonstrate the potentials of the alldigital PET system.