Design and Evaluation of a Prototype Portable Panel PET Imaging System

Positron Emission Tomography (PET) is a nuclear imaging modality used in clinical diagnostics and biomedical research to show metabolic processes in an organism. Movable PET has great significance for the practical application of tumor diagnosis. In this paper, we propose a panel PET imaging system with high portability, and further evaluate a virtual-pinhole PET (VP-PET) system with higher spatial resolution. To evaluate the resolution of the PET prototype, we build a rotation stage coupled with two PET detector modules. PET detectors are composed of 12 × 12 LYSO crystals and Position Sensitive Photomultiplier Tubes (PSPMT). The central position of the two coincidence detectors is consistent with the rotation center, where a 22Na point source with a 3 mm diameter and an activity of 1 μCi is placed. The stage rotates several times on the horizontal plane, which enables signal acquisition within the range of 360°. A TCA DAQ system from Natuq is used for signal waveform acquisition, and FPGA algorithm programming is performed. After removing the coincidence detection data of repeated angles, the filtered back-projection (FBP) algorithm is used to reconstruct the 22Na point source image. Since the pixel size of the LYSO crystal directly affects the spatial resolution of the PET system, we set experiments of five types of LYSO crystals with pixels from 0.9mm to 2.0mm on VP-PET geometry. Meanwhile, the relationship between the spatial resolution of VP-PET with the pixel size of LYSO crystal is compared and analyzed in the experiments. In addition, in the Geant4 simulation, the two-dimensional image reconstruction of MRI glioma phantom is carried out by the panel PET system, which further proves that the VP-PET system has accurate spatial resolution and high sensitivity.