Impact of Collimator Material on Spatial Resolution and Sensitivity in Semiconductor-Based Imaging Systems: A Monte Carlo Evaluation

Abstract

Background: In gamma cameras, there is significant interest in developing novel devices that employ a semiconductor detector. The most significant quality control parameter for assessing the performance of gamma cameras with parallel-hole collimating is the spatial resolution. Acceptable spatial resolution is due to the high absorption and stopping power of collimator materials, while they may lead to a reduction in sensitivity in the same condition. Thus, a comparison between sensitivity and spatial resolution is crucial in nuclear medicine imaging devices. Aims and Objectives: This work aimed to compare spatial resolutions using pixellated parallel-hole collimators with lead and tungsten at equal sensitivity to assess the camera’s performance. Materials and Methods: The overall imaging system was simulated using a Geant4 Application for Tomographic Emission simulation tool. Furthermore, source-to-detector distance effects on image performance and spatial resolution were evaluated using a simulated hot-rod phantom. The full width at half maximum (FWHM) and the full width at tenth maximum (FWTM) stand for the spatial resolution. Results: The averages of measured FWHM using lead at equivalent sensitivities were 3.28% greater than that of tungsten. Furthermore, the averages of measured FWTM of lead at equivalent sensitivities were 7.99% greater than those obtained with tungsten. Conclusion: The results demonstrated that at a specific sensitivity, lead provides better spatial resolution than tungsten.