Determination of the Energy Windows for the Triple Energy Window Scatter Correction Method in Gadolinium-159 Single Photon Emission Computed Tomography Using Monte Carlo Simulation

Introduction: In radionuclide imaging, object scatter is one of the major factors leading to image quality degradation. Therefore, the correction of scattered photons might have a great impact on improving the image quality. Regarding this, the present study aimed to determine the main and sub-energy windows for triple energy window (TEW) scatter correction method using the SIMIND Monte Carlo simulation code in Gadolinium-159 (Gd-159) imaging. Material and Methods: The energy window was set for various main energy window widths (i.e., 10%, 15%, and 20%) and sub-energy window widths (i.e., 3 and 6 keV). Siemens Medical System Symbia fitted with a high-energy collimator was used with Gd-159 point source positioned at seven locations inside the cylindrical water phantom. A comparison was made between the true primary to total ratio (calculated by SIMIND) and the primary to total ratio estimated using TEW method. Results: The findings of this study showed that 20% of the main energy windows with 3 and 6 keV sub-energy windows were optimal for the implementation of the TEW method in Gd-159. Conclusion: According to the results, the optimal energy windows for Gd-159 scintigraphy were the sub-energy windows of 3 and 6 keV. These findings could be helpful in the quantification of Gd-159 imaging.