Calculation of direct and indirect damages of Auger electron-emitting radionuclides based on the atomic geometric model: A simulation study using Geant4-DNA toolkit

This study represents the detailed calculation of damage by Auger electrons of radionuclides 99 m T c , 111 I n , 125 I and 123 I to DNA molecules at cellular scales, using Geant4-DNA toolkit. The average number of breaks in DNA are shown as a function of distance from the center of the DNA axis to position of Auger electron decay and compared with results obtained for different models of DNA used by others. The highest damage occurs for electrons with energies below 1 keV, and in proximity of DNA molecule. The calculation of DSB yield per Gy per Dalton is carried out for above radionuclides. The most considerable damage occurs when the distance between an Auger electron-emitting atom and DNA is about 2.5 nm, and 50% decreases happen when the distance is about 3.5 to 4 nm. DSB yield are comparable with other experimental and simulation data, and show a good agreement between our results and other works.