A simplified numerical model for Compton cameras efficiency and spatial resolution estimation

Background and objective: One of the main advantages of Compton Cameras (CC) with respect to mechanically collimated gamma cameras is a potentially higher efficiency, which is a key feature for imaging devices developed for applications such as emission tomography in nuclear medicine or radioactive environmental monitoring. Several Monte Carlo (MC) simulation toolkits are available to study the optimal detector configuration with good accuracy but generally low computational efficiency. Methods: Here, we propose a simplified numerical model of the classical two-tier CC for multi-parameter optimization via stochastic simulations. Designed as a user-friendly, low-cost alternative to traditional Monte Carlo tools, it helps estimate system efficiency and reduce the need for extensive simulations. The model calculates scatter and absorber efficiencies, both geometrical and intrinsic, based on inputs that include detector dimensions, distances, material density, and cross-sections, and outputs partial and total detection efficiencies. Results: The impact of the principal geometrical and physical parameters on the total efficiency has been analyzed for a heterogeneous CC for hadron therapy featuring GAGG and LYSO scintillators as scatter and absorber detectors, respectively. The results were validated through ANTS2 simulation package (Morozov et al., 2016) and a GATE (Allison et al., 2016) simulated data of a CC available in literature (Barrientos et al., 2023), showing good agreement, confirming the model's reliability. Conclusion: The developed tool estimates the impact of various parameters on system efficiency in just a few minutes per CC configuration, significantly faster than conventional Monte Carlo simulations, which typically take several hours.