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Cobalt 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.
The dose is fractionated to about 2 Gy per day for curative treatment, which allows normal tissues to undergo repair, allowing them to tolerate a higher dose than would otherwise be expected. The dose to the targeted tissue mass must be averaged over the entire body mass, most of which receives negligible radiation, to arrive at a whole-body ...
A typical cobalt-60 capsule, comprising: (A) An international standard source holder (usually lead), (B) a retaining ring, and (C) a teletherapy "source" composed of (D) two nested stainless steel canisters welded to two (E) stainless steel lids surrounding an (F) internal shield (usually uranium metal or a tungsten alloy) that protects a (G) cylinder of radioactive source material.
It is estimated that almost 80 percent of people received a dose less than 500 mrem (equivalent to 5 mSv); 18 percent, between 0.5 and 25 rems (5–25 mSv); and only two percent (about 80 people) received doses greater than 25 rems (250 mSv). Of these, five people received a dose between 300 and 700 rems (3–7 Sv) over a period of two months. [3]
Cobalt-60 (60 Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. [ 3 ] [ 4 ] : 39 It is produced artificially in nuclear reactors . Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59
Cobalt-60 (60 Co) is a synthetic radioactive isotope of cobalt, with a half-life of 5.27 years, and emits highly penetrating gamma rays. It is commonly used as a radiation source for radiotherapy and equipment sterilization in hospital settings, and also has industrial uses.
Sample of cobalt-60 that emits 1 μCi (microcurie) of radioactivity; i.e. 37,000 decays per second. The curie (symbol Ci ) is a non- SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was to be named in honour of Pierre Curie , [ 1 ] but was considered at least by some to be in honour of Marie ...
Early on it was found that X-rays, gamma rays, and beta radiation were essentially equivalent for all cell types. Therefore, the standard radiation type X is generally an X-ray beam with 250 keV photons or cobalt-60 gamma rays. As a result, the relative biological effectiveness of beta and photon radiation is essentially 1.