THEORY OF MUTATION-INDUCTION BY ACCELERATED VERY HEAVY-IONS IN CELLS

Stochastic effects of ionising radiation in humans are related to muta tion induction in cells. Therefore experimental data on mutation induc tion represents one of the endpoints used for the estimation of risk i n radiation protection. Only very rough estimates can be made owing to the fact that a suitable theoretical approach does not exist. A simpl e method is proposed for the evaluation of the efficiency of mutation induction by accelerated very heavy ions in mammalian cells. The appro ach is based on the calculation of the fraction of energy deposited by accelerated particles in indirect collisions (hits) in the cells. Two different modes of particle mutagenic action can be distinguished. de lta ray mutagenesis is related to those particles that preferentially kill the cells in direct hits. Track-core mutagenesis arises from dire ct hits and is observed for lighter ions or ions with very high energy (LET less than or equal to 500 keV.mu m(-1)). Available experimental data agree reasonably well with the results based on theory.