  We propose Radiation Exposure Theory (RET), a mathematical framework to
estimate biological damage caused by irradiation. This is an extension of LDM
model which was proposed in the paper [Y. Manabe et al.: J. Phys. Soc. Jpn. 81,
104004(2012)]. The theory is based on physical protocol, 'a stimulus and its
response'. It takes account of considerable response including mutation, cell
death caused by outer stimulus, as well as biological functions such as
proliferation, apoptosis and repair. By taking account of biological issues,
namely a variety of preventable effects, which is characteristic feature of
living object. RET can explain various data which simple LNT does not
reproduce. As one of the characteristic features of RET, we propose a scaling
law, namely all the data point with different dose rate irradiation are
predicted to lie on the universal line if the variables, the biological damage
function as a function of time development after artificial irradiation starts
are converted to renormalized ones. The above scaling law can be compared with
experimental data. We adopt the accumulated experiments performed by so-called
mega mouse projects. It is found that their data points are converted into a
universal scaling function and are in reasonably agreement with the prediction
of RET.
