[A method for determining the biological effectiveness of ionizing irradiation by evaluation of mitotic depression of Ehrlich-ascites-tumour cells (author's transl)].

In the present paper there are given the conditions for evaluating the biological effectiveness of Co60-gamma-irradiation by determination of mitotic depression at a defined time after irradiation. Using the model of Ehrlich-ascites-tumour of mice the mitotic index was determined four days after inoculation and one hour after irradiation for doses of 50, 100, 200 and 300 rad. The dose-effect curve- show in the given range of doses an unambiguous dependence of the mitotic depression on the applied dose which can be clearly represented semilogarithmically by regression analysis in an analytical manner. Hence, this dependence may be useful for comparative studies of biological effectiveness of radiation with different LET.