PERTANIKA JOURNAL OF SCIENCE AND TECHNOLOGY

Monte Carlo (MC) simulations in single-photon emission computed tomography (SPECT) are invaluable for enhancing activity quantification in patients, thereby facilitating an accurate estimate of the absorbed dose for every organ. The validation of MC results against experimental data is essential to ensure their reliability. This study focuses on lutetium-177 (¹⁷⁷Lu) SPECT imaging modeling using the Monte Carlo N-Particle Transport, version 5 (MCNP5) code. The objective was to validate the MC code for ¹⁷⁷Lu SPECT by comparing simulated and experimental data on system sensitivity, image quality, intensity profiles, and energy resolution. The gamma camera was modeled based on the GE HealthCare Discovery nuclear medicine/computed tomography (NM/CT) 670 Pro, with a medium energy general purpose (MEGP) collimator. MC simulations accounted for the SPECT scanner’s physical specifications, Gaussian energy blurring, and corrections for scatter and attenuation. Post-simulation analysis was performed in the Matrix Laboratory (MATLAB) software, with comparisons made under identical geometrical configurations for experimental and simulated data. The results revealed a strong agreement between simulated and experimental data. System sensitivities varied by only 3.34%, while the structural similarity index metric (SSIM) value of 0.9348 demonstrated a high level of similarity. The energy resolutions for 113 and 208 keV were 16.28 and 15.69%, respectively. Additionally, high correlation coefficients across spheres further validated the accuracy of the MC model. These remarkable agreements confirm the accuracy and precision of the MCNP5-based ¹⁷⁷Lu SPECT imaging simulations. In conclusion, the validated MCNP5 model of the gamma camera provides a foundation for future research into ¹⁷⁷Lu SPECT imaging and quantification.