Cobalt therapy is the medical use of gamma rays from the radioisotope cobalt - 60 to treat cancer.
Cobalt - 60, the radioactive isotope of cobalt used in medicine and is the longest-lived isotope of cobalt.
In the 1950s, cobalt - 60 was widely used in external beam radiotherapy (teletherapy) machines, which produced a beam of gamma rays which was directed into the patient's body to kill tumor tissue.
In medicine, it is used to treat cancer and to sterilize medical equipment.
Other uses: it is used in the inspection of materials to reveal internal structure, flaws, or foreign objects and in the sterilization of food.