Modeling the distribution of deposited energy by alpha particles from Radon 223 decay and its effect on DNA

The ionizing radiations, through physical and chemical processes, lead to simple and complex single- and double- strand breaks, as well as base lesions to the DNA. In this study, taking into account all the physical and chemical processes involved in the interaction of ionizing radiation with matter, the initial damage induced to DNA was evaluated for 5.7 MeV alpha-rays from Radon 223 isotope. The probability of damage types was calculated in terms of the energy deposition and the probability of direct and indirect damage was investigated as a function of the number of breaks. The results show that, for low deposited energies, the probability of single-strand breaks is more than double-strand breaks. As the amount of the deposited energy increases, this pattern is reversed and the probability of various types of double-strand breaks dominates. The yield of double-strand breaks in the DNA segments, as a main target in radiotherapy, was calculated by the method of energy deposition in DNA samples and compared with previous works. Our results are in good agreement with experimental results.