Design, optimization and prototype testing of a double-stack MRPC detector for positron emission tomography (PET)

Abstract

In this work, the performance of an RPC detector with a 70%Ar-30%CO2 gas mixture for a PET imaging system is investigated. A detailed GEANT4 simulation was performed to improve the detection efficiency by optimizing the thickness and material of the resistive components, the number of gas gaps and selecting an appropriate design and structure of the MRPC detectors. In previous studies, for the detection of gammas by MRPC detectors, a high atomic number (Z) converter such as Pb was suggested. However, in this study, by simulating some commercial glasses for MRPC detectors, it was found that, with a suitable design and using glasses with low-Z materials, without any separate converter, similar detection efficiencies and better spatial resolution are accessible. To achieve similar detection efficiency, the low-Z glasses, require a higher number of gas gaps. This complexity in fabrication of a real detector may be overcome in the future by using cost-effective 3D printing methods. With the proposed design, all double-stack structures have lower detection efficiency for low energy gammas, which is an advantage for rejecting Compton gammas. To verify the simulation results, a 5-layer double-stack MRPC detector was constructed and tested. The experimental detection efficiency of the proposed detector extracted by the coincidence method is 1.46%, which, with an error of less than 3.3%, is in good agreement with the simulation (1.51%). The measured count rate is around 17% larger than the ones estimated by the coincidence method, which is attributed to some spurious pulses generated in the RPC detector.