Analytical methods for system matrix calculation and spatial resolution evaluation of DC-SPECT system

Objective. To develop and evaluate an analytical method for calculating the system matrix of a dynamic cardiac single photon emission computed tomography (DC-SPECT) system, eliminating the need for computationally intensive Monte Carlo (MC) simulations. Approach. An analytical model was proposed for system matrix generation, incorporating solid angle calculations adapted for square-shaped pinhole collimators. The resulting sensitivity maps were validated against MC simulation results. Image reconstructions using the proposed analytical model were compared to those using an MC-simulated system matrix. Additionally, the overall system performance, including sensitivity and spatial resolution, was assessed using MC simulations. Main results. The analytical sensitivity map showed good agreement with MC-based results. Reconstructed images using the analytical model preserved key features but showed reduced performance compared to MC-based reconstructions. MC simulations of DC-SPECT demonstrated a spatial resolution of 5.5 mm for hot regions and 6.0 mm for cold regions, with an overall system sensitivity of 0.07% over a 15 cm diameter spherical field of view. Significance. The proposed analytical method offers a fast and practical alternative to MC-based system matrix generation, enabling efficient system design and prototyping. While its use in clinical image reconstruction requires further evaluation, the model provides a promising tool for accelerating the development of next-generation DC-SPECT systems.