Microdosimetric approach to determination of the radiation quality factor

Permissible levels of strongly ionizing emissions are based on regulated quality coefficients lacking radiobiological substantiation and must, apparently, be revised. The substantiated quality coefficients are to be determined by the coefficients of relative biological effectiveness (RBE) of strongly ionizing emissions at maximum permissible doses. Such information is not obtainable by means of radiobiological experiments. In the present study the microdosimetric concept of dual radiation effect modified by the author is used. The necessary equation parameters are obtained on the basis of the published data on survival of human kidney cells at medium and big doses. At low mitotic index the maximum expected RBE values reach 800 for linear transmission of 100 keV/um radiation energy. In the case when the cell division is intensive the value does not exceed 40