Track structure of proton and α particle in water and DNA damage spectrum

The Monte Carlo track structure model MOCA15 of the proton and α particle in water has been extended. In the simulation, the energy range of proton and α particle is 0.3-5 MeV/u. The cutoff energy of secondary energy electron is 1 eV. Tracks were analyzed to provide confirmation on the reliability of the code and the information on physical parameters, such as range, radial dose profiles. Model calculation shows the good agreement with the experimental data. A simple fast algorithm to simulate DNA damages spectrum produced by ionizing radiation was used. This algorithm captures the major trends in the DNA damage spectrum predicted using detailed track-structure simulations. This method is fast and can be generalized easily. The parameters used in the damage simulation algorithm are provided for proton and alpha particle. This work is systematic. (author)