[The lethal and mutagenic actions of radiations with different LETs on mammalian cells]

Inactivation and induction of mutations in the HGPRT locus in Chinese hamster cells after irradiation with accelerated heavy ions in the LET range of 20 to 367 keV/micron were studied. In both cases, inactivation and induction of mutations, the LET dependence of RBE is described by a curve with a local maximum in the range of 80 to 100 keV/micron. The maximum RBE value for the mutagenic action is almost twice as high as that for inactivation. However, the RBE coefficients of the mutation induction criterion for a certain level of cell-survival is lower significantly and tend to decrease with an increase in inactivation. The obtained data show that the mutagenic effects, induction of chromosome aberrations, and deaths have their origins in the same kind of primary damages, i.e., double-strand breaks of DNA.