3. Biological effects of ionizing radiation

3.1 Mechanisms leading to cellular damage

The broad spectrum of DNA damage induced by radiation is the end result of physical and physico-chemical phenomena, which occur either directly or indirectly. Energy deposition on the DNA-protein complex represents a direct interaction between the particle and the DNA molecule. The indirect effect relates to radiolysis of the few water molecules in the immediate vicinity of the DNA. The free radicals produced by ionization of these water molecules transfer their energy to the nearby cellular environment, producing modifications in the macromolecular assembly of proteins and DNA.

Whether the effects are direct or indirect, their probability increases with the dose and volume of the target