RESUMO
Objective:To obtain the relative biological effectiveness (RBE) of DNA double strand breaks (DSB) clusters by tracing the mechanism of radiated DNA damage, and explore the relationship among the biological effectiveness of DNA damage, chromosomal aberrations and germ cell death.Methods:Taking low-energy electrons, protons, and α particles as the research objects, this study simulated the process that cell nuclei were exposed to particle radiation using a radiation-related physicochemical model. On the ground of the DSB density-based spatial clustering of applications with noise (DBSCAN) algorithm, the DSB cluster classification method was improved to weaken the connection between the DSBs and the random distribution assumptions of energy depositions during the simulation. In this manner, the DSB clusters can be much closer to a non-random distribution. Furthermore, this study obtained the yields of DSB clusters and proposed a method to calculate the RBE values of DSB clusters.Results:The calculated RBE value (12.29) of DSB clusters of 2 MeV α particles was similar to the experimental RBE values of chromosomal fragments (15.3±5.9) and cell survival (14.7±5.1).Conclusions:After high-LET ionizing radiation, unlike the single DSB, the RBE of DSB clusters was similar to that of chromosomal aberration and cell survival.