4. Effects of ionizing radiation

When ionizing radiation interacts with matter, it causes ionization and excitations that can alter the structure of the material. In the case of living matter, the effects induced vary according to dose, dose rate, type of radiation and the radiosensitivity of irradiated tissue.

The mechanisms of action and reaction are complex at the cellular level, but in general, ionizing radiation induces the creation of free radicals that are toxic (because they are highly oxidizing, and therefore highly reactive) for cells and their constituent elements, in particular the DNA molecule. Damage can be repairable, permanent or lead to mutations.

A distinction is made between deterministic (or non-stochastic) effects, which are observed in an obligatory manner as a function of doses received above threshold values (of the order of a gray), and stochastic...