Modelling of initial events and chemical behaviour of species induced in DNA units by Auger electrons from 125I, 123I and carbon.

Auger electron spectra for 123I and 125I generated by Monte Carlo calculation and Auger electrons emitted from carbon after photoelectric effect on its K-shell as well as two DNA models (linear plasmid and nucleosome model) based on x-ray diffraction experiments have been used to simulate the behaviour of all species and radicals created during the physical and the chemical phase of the Auger's transport. By introducing appropriate assumptions for the induction of strand breaks the number of these breaks can also be determined and correlated to experimentally found numbers of lethal events. Efficiency differences between the iodine nuclides themselves and in comparison with the rather monoenergetic Auger electrons from carbon are shown with regard to the direct and indirect effects on the two DNA models. The characteristic products in the physical, chemical and biochemical phase are compared with corresponding results from the literature for low-LET radiation.