Radioiodine

n. radioactive isotope of iodine (Chemistry)

Iodine-131 (131I), also called radioiodine, is a radioisotope of iodine.131I decays with a half-life of 8.0197 days with beta and gamma emissions. This nuclide of iodine atom has 78 neutrons in nucleus, the stable nuclide 127I has 74 neutrons. On decaying, 131I transforms into ¹³¹Xe: 131I is a fission product with a yield of 2.8336%, and was released in nuclear weapons tests and the Chernobyl accident. However, the short half-life means it is not present in cooled spent nuclear fuel, unlike iodine-129.
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A radioactive isotope of iodine. (An isotope is an alternate version of a chemical element that has a different atomic mass). Radioiodine can be used in diagnostic tests as well as in radiotherapy of the thyroid. For hyperthyroidism, radioiodine is administered in capsule form on a one-time basis. It directly radiates thyroid tissues thereby destroying them. It takes 8-12 weeks for the thyroid to become euthyroid (normal) after treatment. The majority of patients undergoing this treatment eventually become hypothyroid, which is easily treated using thyroid hormones (levothyroxine). Radioiodine is contraindicated during pregnancy and breast feeding.

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