Modeling the biological effectiveness of high-LET radiation

Reevaluation of neutron exposures to atomic bomb survivors has greatly reduced the significance of that data base for estimating the relative biological effectiveness of radiations with high linear energy transfer (LET). Consequently, greater emphasis is being given to animal data and mechanistic studies at the cellular and molecular level in assessing the role of radiation quality in the health effects of low-level radiation exposure. We are investigating the spatial patterns of energy deposited in DNA by ionizing radiation and their influence on cell killing and mutation induction. Our basic hypothesis is that high ionization density increases the probability that radiation-induced DNA damage will be unrepairable or misrepaired. This paper discusses the use of computer simulation to investigate damage induced in DNA by the decay of incorporated 125I.