Effect of collimator thickness on the imaging performance of coded-aperture gamma camera

The coded-aperture gamma camera has significant applications in the fields of space exploration, nuclear security, nuclear industry, and nuclear medicine. The coded-aperture collimator is a key component for modulating gamma rays, and its parameters are important factors to optimize the performance of gamma cameras. In this paper, the impact of collimator thickness on the fully coded field of view and angular resolution was determined through Monte Carlo simulation and experimental verification. By introducing the equivalent thickness, the conventional calculation formulas were modified to improve the calculation accuracy. In addition, the variation in the reconstructed image quality with the collimator thickness was quantitatively evaluated by the contrast-to-noise ratio and normalized mean squared error, thereby establishing the relationship between the gamma-ray transmittance and the imaging quality. The results indicate that for medium- and high-energy gamma rays, the optimal imaging quality is achieved when the gamma-ray transmittance corresponding to collimator thicknesses ranges from 12% to 16%. These research findings provide reference standards for the design of coded-aperture collimators to meet the requirements of different applications.