Ionizing radiation

Ionizing radiation is a collective term for multiple types of radiation (including X-rays, alpha radiation, beta radiation and gamma radiation). These various types have one property in common, which is that they can ‘ionize’ matter.


Explanation: radiation contains so much energy that it can release a negatively charged electron from the outer shell of an atom. The atom then looses its neutral charge and gets a positive charge – an ion is formed. When ionizing radiation comes in contact with living tissue, it can cause biologic effects, leading to tissue damage. Humans are exposed to ionizing radiation from natural sources and artificial sources (e.g. X-ray). This is explained further in the Artificial radiation sources & natural background radiation section. For your convenience, in the remainder of this course the word ‘radiation’ is understood to be ionizing radiation.