In this work, GATE Monte Carlo code and its variance reduction techniques were evaluated to calculate S values of organs from the International Commission on Radiological Protection (ICRP) report 110 male phantom for the lutetium-177, iodine-131, yttrium-90, and radium-223 radionuclides. 
GATE
Simulation of ICRP 107 spectra-based source proved to be about 5 times more efficient when compared to a decay simulation using \verb|G4RadioactiveDecay| (Geant4-based radioactive decay processes). 
Geant4
The results are compared with the data from the OpenDose collaboration.



OpenDose