Ionizing radiation is of high energy, capable to penetrate into the matter, to produce ionization of the atoms, to break chemical bonds and cause harm in living matter.
The ionization of an atom is a phenomenon following the interaction of high energy radiation with matter. Ionization means that an electron is ejected from the atomic orbit, leading to theproduction of a pair of opposite charged ions.
The most known types of radiation are the X-rays, produced by the radiological equipment used in medicine, and the radiation α, β and γ, produced by the unstable nuclei of the atoms.The ionizing radiation is penetrating, depending on their type and energy.
The alpha particles can be blocked by a sheet of paper, the beta particles by a few millimeters of plexiglass, while the high energy gamma radiation requires dense materials to be attenuated (e.g. lead, concrete).
The energy transferred to the mass, per mass unit, is called absorbed dose. The probability of affecting the human health is directly related to the absorbed dose.