Radioiodine is defined as a radioactive isotope of the chemical element Iodine. Although there are at least 37 different Iodine radioisotopes, only four of them are used as tracers or therapeutic agents in medicine; these are 123-I, 124-I, 125-I, and 131-I, with the latter being the most common in clinical practice. Essentially all industrial production of radioiodine isotopes involves four aforementioned radionuclides.
History of radioiodine production and usage
The first radioiodine was produced by Enrico Fermi in 1934. It was Iodine-128, which prompted additional experiments in France and the United States. Karl Compton and the thyroid group from the Massachusetts Institute of Technology and Massachusetts General …show more content…
The target material for irradiation is either TeO2 or Te-metal, depending on whether a wet chemical separation or a dry distillation method is used.
Iodine-131 is commercially available in dilute sodium hydroxide solution with high radiochemical purity. In certain solutions a specific reducing agent needs to be added to preserve the isotope in the form of iodide; howerver, its use may interfere when employing Iodine-131 for labelling organic compounds.
Iodine-125 is also a reactor-produced radionuclide that allso follows the (n, gamma) reaction on Xenon-124. Iodine-125 is commerically available in dilute sodium hydroxide solution with high chemical and radiochemical purity. Its radioactive concentration lies at 4 to 11 GBq/ml.
Cyclotron produced radioiodines
Iodine-123 represents widely used cyclotron-produced radioisotope for single-photon emission computed tomography (SPECT). Nuclear reaction which yields Iodine-123 directly via proton bombardment of tellurium targets in a cyclotron with subsequent separation of this radioiodine from the irradiated target represents most commonly utilized