The Effect Of In-111 Radionuclide Distance And Auger Electron Energy On Direct Induction Of Dna Double-Strand Breaks: A Monte Carlo Study Using Geant4 Toolkit

Purpose: In this study, the effect of In-111 position and Auger electron energy on direct induction of DSBs was investigated.Materials and methods: The Geant4-DNA simulation toolkit was applied using a simple B-DNA form extracted from PDBlib library. First, the simulation was performed for electrons with energies of In-111 and equal emission probabilities to find the most effective electron energies. Then, In-111 Auger electrons' actual spectrum was considered and their contribution in DSB induction analysed.Results: The results showed that the most effective electron energy is 183eV, but due to the higher emission probability of 350eV electrons, most of the DSBs were induced by the latter electrons. Also, it was observed that most of the DSBs are induced by electrons emitted within 4nm of the central axis of the DNA and were mainly due to breaks with <4base pairs distance in opposing strands. Whilst, when In-111 atoms are very close to the DNA, 1.3 DSBs have been obtained per decay of In-111 atoms.Conclusions: The results show that the most effective Auger electrons are the 350eV electrons from In-111 atoms with <4nm distance from the central axis of the DNA which induce approximate to 1.3DSBs per decay when bound to the DNA. This value seems reasonable when compared with the reported experimental data.