Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification: a Monte Carlo study

Abstract Purpose The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well image corrections incorporated in iterative reconstruction process. These factors can be investigated optimised using Monte Carlo simulations. This study aimed to evaluate quantification 123 I with low-energy high resolution (LEHR) medium-energy (ME) collimators 131 high-energy (HE) collimator. Methods Simulated projection images were reconstructed OS-EM algorithm, which was number updates, appropriate scatter, attenuation collimator detector response (CDR), including septal scatter penetration compensation. An calibration factor (CF) determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere (cold) air point-like source), volume interest (VOI) diameters. Recovery curves constructed recovery coefficients correct partial effects (PVEs). method evaluated spheres voxel-based digital patient phantoms. Results optimal updates 60 all combinations. CF point a VOI diameter equal physical size plus 3.0-cm margin selected, geometries. spheres’ errors phantoms less than 3.2% 5.4%, respectively, Conclusion showed that 6.0% could attained, combinations, if for; attenuation, CDR (including penetration) PVEs are performed. LEHR ME accuracies compared when applied. useful departments perform studies may not have access collimators.