The isotope 131I is still occasionally used for purely diagnostic (i.e., imaging) work, due to its low expense compared to other iodine radioisotopes. However, since the other 90% of radiation (beta radiation) causes tissue damage without contributing to any ability to see or "image" the isotope, other less-damaging radioisotopes of iodine such as iodine-123 (see isotopes of iodine) are preferred in situations when only nuclear imaging is required. Iodine-131 can be "seen" by nuclear medicine imaging techniques (e.g., gamma cameras) whenever it is given for therapeutic use, since about 10% of its energy and radiation dose is via gamma radiation. Thus, iodine-131 is increasingly less employed in small doses in medical use (especially in children), but increasingly is used only in large and maximal treatment doses, as a way of killing targeted tissues. Likewise, most studies of very-high-dose 131I for treatment of Graves' disease have failed to find any increase in thyroid cancer, even though there is linear increase in thyroid cancer risk with 131I absorption at moderate doses. For example, children treated with moderate dose of 131I for thyroid adenomas had a detectable increase in thyroid cancer, but children treated with a much higher dose did not. For this reason, high doses of the isotope are sometimes less dangerous than low doses, since they tend to kill thyroid tissues that would otherwise become cancerous as a result of the radiation. 131I is also a major fission product of uranium-233, produced from thorium.ĭue to its mode of beta decay, iodine-131 causes mutation and death in cells that it penetrates, and other cells up to several millimeters away. See fission product yield for a comparison with other radioactive fission products. This is because 131I is a major fission product of uranium and plutonium, comprising nearly 3% of the total products of fission (by weight). It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis. It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production. It has a radioactive decay half-life of about eight days. Iodine-131 ( 131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. Isotope of iodine Iodine-131, 131I General
0 kommentar(er)
