Radioactive source

A radioactive source or radiation source is a sample of a radionuclide, usually contained within a radiation-resistant container. It emits ionizing radiation (one or more of gamma rays, alpha particles, beta particles, and neutron radiation), which can be used in medicine for radiation therapy and in industry for industrial radiography, food irradiation, sterilization, disinfestation, crosslinking, and more. Radionuclides are chosen according to the type and character of the radiation they emit, intensity of emission, and the half-life of their decay. Common source radionuclides include cobalt-60, iridium-192, and strontium-90. The activity of a radioactive source is typically measured in Curies, despite NIST strongly advising the use of the Becquerel. A radioactive source typically lasts for between 5 and 15 years before its activity drops below useful levels.