A method for reducing gamma-ray coded-aperture imaging artifacts based on Compton sequence reconstruction

Gamma-ray coded-aperture imaging technology has important applications in nuclear safety monitoring, the decommissioning of nuclear facilities, and the transportation of spent fuel. However, the Compton scattering effect occurs when gamma rays interact with the detector, leading to a large number of random artifacts in the reconstructed images. These artifacts degrade the quality of coded-aperture imaging. In this paper, a coded-aperture imaging method based on Compton sequence reconstruction was proposed to reduce artifacts in image reconstruction. Additionally, the energy discrimination method suitable for Compton two-event sequence reconstruction was improved, and a probability method was proposed for Compton multi-event sequence reconstruction. Through simulations, the improved energy discrimination method was validated for its enhancement in the accuracy rate of sequence reconstruction. The probability method was compared with the conventional minimum squared difference (MSD) and deterministic methods, confirming that the probability method achieved the best sequence reconstruction results and accurately identified the full-energy event. In single-source and multi-source imaging experiments, the proposed image reconstruction method was compared with the conventional maximum likelihood expectation maximization (MLEM) algorithm and the mask and anti-mask coded functions (MACF) algorithm. The results demonstrated that the probability method combined with the MACF algorithm effectively reduced random artifacts and thickness artifacts in the reconstructed images, significantly improving imaging quality.