irradiation

Irradiation is the exposure of matter to radiation, typically ionizing radiation such as photons (gamma and X-rays) or particles (alpha, beta, neutrons). The term can refer to the process of exposing an object to radiation for a purpose or to the resulting condition of that object. Ionizing radiation deposits energy in tissues and materials, causing chemical changes and, at sufficient doses, biological damage.

Common types of irradiation include gamma irradiation from radioactive sources, X-rays from machines, electron beams, neutrons, and alpha or beta particles from radioactive decay. Sources are natural (cosmic rays, terrestrial radiation, radon) and artificial (medical X-ray devices, nuclear reactors, particle accelerators). The effect depends on dose, dose rate, radiation quality, and the exposed material.

Dose is measured as absorbed dose in grays (Gy); biologically weighted doses are expressed as sieverts (Sv). Protection follows ALARA principles, uses shielding, containment, distance, and exposure monitoring. Side effects range from no immediate harm at low doses to deterministic effects like skin burns or radiation sickness at high doses; long-term risks include cancer and genetic effects.

Applications are diverse. In medicine, irradiation treats cancer and sterilizes equipment; diagnostic imaging uses ionizing radiation. In industry, irradiation sterilizes medical supplies and food to extend shelf life or kill pests, and may modify polymers. Safety and regulatory frameworks are established by national authorities and international bodies such as the IAEA.