Comparing the Performance of Scatter Correction Methods in Cardiac SPECT Imaging with Technetium-99m and Thallium-201 Radioisotopes.

Purpose: This study aims to evaluate the performance of dual-energy window (DEW) and triple-energy window (TEW) scatter correction methods in cardiac SPECT imaging with technetium-99m (Tc-99m) and thallium-201 (Tl-201) radioisotopes.

Materials and methods: The SIMIND Monte Carlo program was used to simulate the imaging system and produce the required projections. Two phantoms, including the simple cardiac phantom and the NCAT phantom, were used to evaluate the scatter correction methods. The simulations were repeated 5 times for each phantom and finally, the mean values obtained from these 5 tests were used in the analysis of the results.

Results: The obtained results from this study show that in the case of both investigated phantoms, the use of correction methods leads to improve the contrast of the images obtained from Tc-99m and Tl-201 radioisotopes. In the case of the simple cardiac phantom, the use of DEW and TEW correction methods leads to a relative increase in image contrast of about 23.88% and 12.23% for ^99mTc radioisotope and about 29.19% and 20.98% for ²⁰¹Tl radioisotope, respectively. This relative increase in the case of the NCAT phantom is about 22.48% and 19.43% for ^99mTc radioisotope and about 27.74% and 24.74% for ²⁰¹Tl radioisotope, respectively.

Conclusion: According to the obtained results, despite the higher contrast of the noncorrected images of ^99mTc radioisotope, the relative increase in contrast of the corrected images of ²⁰¹Tl radioisotope is more than that of ^99mTc radioisotope. Furthermore, for both radioisotopes, the relative increase related to the DEW method is higher than the TEW method.