Abstract
Spatial distribution of Energy deposition by ionizing radiation is thought to strongly affect on the initial DNA damage spectrum and biological consequences. In particular, the serious biological effect observed after irradiation of heavy ions has been suggested to be due to formation of clustered-DNA-damage which may be difficult to be repaired. However, it is difficult to detect such kind of damages experimentally. The purpose of our study is to estimate the yields and the configuration of radiation-induced DNA damages and further to relate the estimated clustered DNA damage with biological consequences. We have developed the Monte Carlo simulation code system to estimate radiation-induced DNA damage spectrum which starts from detailed track structure by considering the direct and indirect actions in cellular environment for X-rays and heavy ions. In our presentation, the calculated DNA damage spectrum for heavy ions as C ions will be shown. Analysis on the contribution of energy deposition pattern, higher-order structure of DNA, direct and indirect action to the DNA damage spectrum will be also shown. The damage spectrum as a function of LET will be discussed with comparison with experimental data on LET-RBE relationship of cell death.
