Energy Window and Collimator Optimization in Lutetium-177 Single-photon Emission Computed Tomography Imaging using Monte Carlo Simulation

INTRODUCTION: In lutetium-177 (Lu-177) single-photon emission computed tomography (SPECT) imaging, the accuracy of activity quantification is degraded by penetrated and scattered photons. We assessed the scattered photon fractions in order to determine the optimal situation and development of correction method. This study proposes to compare the image quality that can be achieved by three collimators. MATERIALS AND METHODS: Siemens Medical System Symbia fitted with high-energy (HE), medium-energy (ME), and low-energy high-resolution collimators was simulated using the SIMIND Monte Carlo code simulation code. Counts were collected in three different main-energy window widths (20%, 15%, and 10%) for Lu-177 point source. Primary and scattered point spread functions and also geometric, penetration, scattering were drawn and analyzed. RESULTS: In Lu-177 imaging, a 20% of main-energy window and ME collimator were found to be optimal. HE collimator can be used when the resolution is not required. CONCLUSION: These results provide the optimal energy window and collimator in Lu-177 SPECT imaging and will help the quantification of Lu-177.