Abstract
Epidemiological approach in radiation risk analysis uses operational model such as a regression model which explicitly describes the risk as a function of radiation dose and other observable factors, while leaving the biological relationship as a black box. Needless to say, this approach is very useful for estimating the risk of radiation exposure with a dose of certain range. However, for the problems such as extrapolation of the dose-response relationship to lower dose range, risk transfer, and estimation of the dose-response function and latency period, it will be necessary to consider in the black box a system including interactions between molecules, cells and tissues, and take systems radiation biology approach. The dynamics in such a system may be described by a system of stochastic differential equations and their solutions may be obtained by simulation.
