Cobalt therapy
![Patient receiving cobalt-60 therapy in an early teletherapy machine, probably early 1950s. The cobalt is in the radiation head (top center), which produces a beam of gamma rays which penetrate the patient's body and strike the tumor. Radiation passing through the patient is absorbed by the lead shield opposite. During therapy, the head unit rotates slowly around the patient to reduce the radiation dose to healthy tissue.](/Images/godic/202501/05/Nci-vol-1819-300_cobalt_60_therapy2157.jpg")
![The first cobalt machine in Italy, installed in Borgo Valsugana in 1953.](/Images/godic/202501/05/Eldorado_A2157.jpeg")
Cobalt therapy or cobalt-60 therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer. Beginning 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. Because these "cobalt machines" were expensive and required specialist support they were often housed in cobalt units. Cobalt therapy was a revolutionary advance in radiotherapy in the post-World War 2 period but is now being replaced by other technologies such as linear accelerators.