Track Structure, Target Structure and Radiation Effectiveness

Abstract

Abstract A track structure model based on energy deposition in water is used to investigate the dependence of the response of a typical 'single hit' detector and a biological effect, the induction of double strand breaks, on the type and energy of the radiation. In making the calculations for a single hit detector, it is assumed that an energy deposition event within a small sphere around the target causes the effect. For the induction of DNA double strand breaks it is assumed that two energy deposition events along the same track are necessary, one occurring in each of two small spheres at a distance of 1.2 nm from each other to simulate the two strands of the DNA helix. The calculations show that for a series of different particles, a series of differing curves of effectiveness relative to stopping power are found. These differing curves offer an explanation for the differences in effectiveness of two different particles having the same stopping power.