[Quantitative description of the process of radiation inactivation of cells. VI. Calculation of the modifications in the dose survival relationship of eukaryotic cells].

The parameters of dose-survival relation in terms of cytogenetic action of radiation are directly connected with real characteristics of experimental survival curves: initial slope, final slope, and threshold. A system for estimation of the elementary modification is suggested. 9 elementary modifications are interpreted in terms of the suggested model which enables to analyse complex kinds of modification. Intermolecular DNA links are considered responsible for non-zero initial slope of survival curve. The final slope of survival curve is determined by double-strand DNA breaks which are due to both the size of target and the efficiency of repair at the hit -- primary lesion stage (on molecular level). Threshold of the sruvival curves is determined by the competition of recovery after primary lesion and the fixation of lethals (assymmetrical chromosome exchanges -- cytogenetic level).