Non-Target-Effect Model Of Ionizing Radiation-induced Tumor Prevalence And Its Application

Space radiation is one of the main factors threatening the health of astronauts in long-term space missions.Space radiation is carcinogenic.NASA defines cancer risk as one of four Type ? radiation risks.Before human beings carry out long-term space missions,it is necessary to estimate the carcinogenic risk from space radiation as accurately as possible.However,there is a great uncertainty(up to 400?600%)by using traditional methods to assess the space radiation risk of astronauts.An important reason for such great uncertainty is the lack of systematic research on the non-target effect of heavy ion radiation.Therefore,a suitable biophysical model which can use the data obtained in ground-based simulation experiments to assess space radiation risk is urgently needed.In this paper,in order to solve this problem,a new cancer risk assessment model is established and the related application research is carried out.Considering the original process of interaction between ionizing radiation and organisms,a NTE model of tumor prevalence was established whose cell survival rate followed the single-target multi-hits model.Based on the origin C platform of the origin lab software,the model parameters could be determined by fitting the experimental data of the Harderian tumor of B6CF1 mice.On this basis,the ?2-test was used to evaluate the correlation between the model and the experimental data,and the ?2 and P values of the different models were calculated.The results show that the model established in this paper is more relevant to experimental data.Then,we calculated the relative biological effect(RBE)of the model,and found that the RBE gradually decreased with increasing dose,showing obvious low dose radiation sensitivity.All the results showed that the established NTE model is suitable for describing the radiation biological effects of low-dose space radiation.Further,we used the space radiation field models in the OMERE software to simulate the space radiation environment in different shield depth of the proposed Chinese space station,and calculated a series of radiation protection doses,such as adsorbed dose and dose equivalent accepted by different astronauts' organs.Finally,based on the effective dose calculated here,the cancer risk of astronauts working in the Chinese space station for 180 days is estimated by using the tumor incidence model established in this paper.