The effects of small doses of ionizing radiation

Energy deposition in cells exposed to ionizing radiation occurs through the agency of individual charged particles. At low doses the number of these particles is of the order of 1. One may then expect comparatively simple inactivation dynamics, and, in particular, the relative biological effectiveness (RBE) should become a simple function of the absorbed dose either of the radiations under comparison. Experimental data on the dose dependence of RBE are consistent with the assumption that the dose-effect relation is linear for neutrons of high LET (energies of the order of 1 MeV) and quadratic for X- and gamma -rays.