摘要: In biological processes after energy deposition of radiation in cells, DNA damage occurs at first to produce chromosomal breaks and then appear many cell responses. Reproductive interphase death causes inactivation cancer tissue. Traditional target theory linear quadratic model are used explain mechanism treatment prediction. There factors modify the efficiency radiobiological effects such as oxygen other chemical substances well physical distribution radiation. For high-LET radiations, relative effectiveness is most important factor on therapy enhancement ratio.