The human body is made up of cells that are able to reproduce. Reproduction is a continual process in all living organisms. Ionising radiation that penetrates a cell can affect this process of reproduction by causing abnormal chemical reactions. Some of these reactions can lead to the death of the cell and others to its survival in a modified form (mutation).
The effects of ionising radiation vary depending on the dose received and the source, method and target of the exposure.
Depending on the dose received during exposure to ionising radiation, there are two types of biological effects: acute or deterministic effects and long-term or probabilistic/stochastic effects.