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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 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.
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.
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 ...
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]
1982 – Cobalt-60 (possibly from a radiotherapy source) became recycled into steel rebar and used in the construction of buildings in northern Taiwan, principally in Taipei, from 1982 through 1984. Over 200 residential and other buildings were found to have been built using the material. [ 19 ]
For an exposure of 1 roentgen by gamma rays with an energy of 1 MeV, the dose in air will be 0.877 rad, the dose in water will be 0.975 rad, the dose in silicon will be 0.877 rad, and the dose in averaged human tissue will be 1 rad. [10] "rad" stands for radiation absorbed dose. [4]
This reaction has a half-life of about 5.27 years, and due to the availability of cobalt-59 (100% of its natural abundance), this neutron bombarded isotope of cobalt is a valuable source of nuclear radiation (namely gamma radiation) for radiotherapy. [1] 59 27 Co + 1 0 n → 60 27 Co