A systemic model describing the major radiobiological effects of various types of radiation is proposed. The model base lines were substantiated, and general mathematical equations for cell survival developed. The model takes into consideration such physical and biological factors as linear energy transfer, ion track structure, and structural and functional organization of interphase chromatin. This paper presents the basic assumptions made and general equations for the cell killing.
A general equation for mammalian cell survival has been derived in the previous paper. This paper presents the results of comparison of theoretical evaluations with survival data available from the literature, including different cell lines, variations in linear energy transfer, dose rate and dose fractionation effects and the effects of ultrasoft X-rays and superheavy ions. Merits and demerits of the model are considered in comparison with other models of radiation-induced killing of mammalian cells published in the literature.
The question of radiobiological substantiation of successive and simultaneous action of radiation of different quality on biological objects is important in connection with the use in radiation therapy of mixed radiation with high and low energy transfer per unit length. For this, it is necessary to understand the depth mechanisms of the damaging effect of mixed radiation in order to predict the consequences of such irradiation. It is important to assess the risk to personnel servicing different radiation sources and to the population. A large number of works on this problem have now been published [1 -13], but thus far not only is there no clear understanding of the mechanism and a quantitative description of the effect of combined radiation but the terminology is inconsistent. Thus, the following classification of effects due to combined action of radiation of different quality is given in ICRP No. 30 [1].Independent action --the dose-effect dependence for radiation x does not change in the presence of radiation y. It follows that the cell survival S satisfies S(v + x) = S(y)S(x).Additive effect --the dose-effect dependence for which an additional effect caused by radiation x is added to the effect due to radiation y as if the effect of y is caused by a biologically equivalent dose x e, i.e.
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