Evaluation and comparison of GEANT4-DNA and MCDS codes for the estimation of relative biological effectiveness relevant to the Auger electrons emitted from Iodine radioisotopes

In current study, the relative biological effectiveness (RBE) values relevant to the various Iodine radioisotopes, have been assessed to compare the performance of the MCSD and GEANT4-DNA Monte Carlo codes at low energy regions. After the calculation of the Auger electrons energy spectrum, obtained from the Iodine radioisotopes including 123I, 124I, and 125I through the GEANT4 Monte Carlo code, the calculation of the RBE values was performed through the GEANT4-DNA extension by considering the B-DNA model. In addition, the RBE values were also estimated by the MCDS code in completely aerobic conditions. The results of this study showed that employing the GEANT4-DNA-option4 physics by GEANT4-DNA extension in the physical stage provides near results in comparison with MCDS code for the radiobiological assessments and RBE estimation. The obtained highest difference values in this study were related to the use of GEANT4-DNA-option2 physics which varies from 22.30% to 24.60% for the studied radioisotopes. Since double strand damages along the DNA molecule can eventually lead to the cell death, and due to the appropriable agreement between the calculated results of RBEDSB values through the MCDS and GEANT4-DNA codes, it can be deduced that the MCDS code provides accurate results for the radiation induced DNA damage.