Cobalt-60, gamma radiation emitter

Radioisotopes are also used in radiation therapy to treat cancer. The goal in radiation therapy is to kill malignant cells, while protecting healthy tissue from radiation effects. Radioisotopes such as yttrium-90, a beta emitter, may be placed directly in the tumor. Alternatively, the diseased tissue may be subjected to beams of gamma radiation. Cobalt-60 used in radiation therapy is prepared by a series of transmutations ... 

Teletherapy is radiation treatment where the radiation source is not in direct contact with the tumour to be treated. The radiation used for the treatment can be of different types and energies and originate from different sources. Gamma-emitting radioactive sources such as cobalt-60 are often used, because they are convenient, need virtually no maintenance, and are almost ideal gamma emitters. Many of these sources are in use for cancer treatment. 

Check Sources. The following isotopes have been used by the military as check sources Cobalt-60, Krypton-85, Strontium-90, Barium-133, Cesium-137, Lead-210, Radium-226, Thorium-232, Uranium-238, and Plutonium-239. As such, they are normally found as sealed sources associated with radiation detection instrumentation or in a calibration lab, and would take some serious effort to release to the environment. Sealed sources represent an external exposure hazard only (unless they are physically destroyed). One other item that should be considered with respect to sealed source beta emitters is that they are often associated with lower energy. The other sources are gamma emitters, with the exception of the Am-Be source that produces neutrons. The gamma emitters will expose the whole body externally, as will the neutron source. The sealed sources will be detected in most cases using the AN/PDR-77 with the beta/gamma probe. 

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