149 / 2023-04-14 20:43:26

Simulation of Spatial Resolution and Detection Efficiency of Lens-coupled Scintillator for Intense Pulsed Gamma-Ray Imaging System Using Geant4

lens-coupled scintillator,spatial resolution,detection efficiency,Geant4

The intense pulsed gamma-ray imaging system mainly comprising tungsten pinhole collimator, lens-coupled LYSO scintillator, MCP image intensifier and CCD camera is used for radiation image diagnostics. The aim of this study is to investigate the influence of the Geant4 physical model, the scintillator thickness and the lens F-number on spatial resolution and detection efficiency of the lens-coupled scintillator, and to suggest the best combination of parameters. The accuracy comparison between different Geant4 physical models was carried out on the average number and length of collisions of secondary electrons in LYSO scintillator. For a 10 um discretization accuracy requirement, the results indicate that the G4EmStandardPhysics_option4 physical model with 5 um G4StepLimiter gives a sufficient accuracy. Based on this physical model, the transport of the gamma-rays, secondary electrons and photons are simulated simultaneously by changing the scintillator thickness and the lens F-number, and the intensity distribution of photons received by the lens is recorded. The simulation results show that decreasing the scintillator thickness can significantly improve the spatial resolution while has relatively little effect on the detection efficiency, and decreasing the lens F-number can significantly increase the detection efficiency while has relatively little effect on the spatial resolution. This indicates that there is an optimal combination of parameters for the spatial resolution and detection efficiency required by the imaging system, and the optimal curve is given. The results of this paper are instructive for the design of intense pulsed gamma-ray imaging system.