Radioisotopes iodine

Strickert, R., Friedman, A. M., and Fried, S., "The Sorption of Technetium and Iodine Radioisotopes by Various Minerals," Nuclear Technology, in press (1978). 

Commonly used radiopharmaceuticals are carbon 14 (ti/2 30 years), cobalt 57 (ti/2 271 days), cobalt-58 (ti/2 70.8 days), gold-198 (ti/2 2.7 days), iodine-123 (ti/2 12.3 hours), iodine-125 O1/2 60 hours), iodine-131 (ti/2 8.04 days), and tritium (ti/2 12.3 years). The iodine radioisotope is used to study thyroid function and is used in the treatment of hyperthyroidism and thyroid carcinoma. Various monoclonal antibodies labeled with iodine-171 are used for the detection of malignant neoplasms. Genetic damage is a dangerous side effect of radioactive isotopes prior to and during the reproductive period. Exposure to large doses leads to leukopenia, anemia, skin inflammation, radiation sickness, and neoplasm. 

Isotope Exchange Reactions In isotope exchange reactions, isotopes of the same elements having different mass numbers replace one or more atoms in a molecule. Examples are labelling of iodide-containing material with iodine radioisotopes. Since the radiolabeled and parent molecules are identical except for the isotope effect, they are expected to have the same biological and chemical properties. 

Strickert R., Friedman A. M., and Fried S. (1980) The sorption of technetium and iodine radioisotopes by various minerals. Nuclear Technol. 49, 253-266. 

Table 2.3 Nuclear reactions and parameters of iodine radioisotopes used in neutron activation anaiysis...

For routine labeling of radiopharmaceuticals, the most convenient procedures are recommended because time is a factor barely available for chemists, especially from the physician s point of view. Needless to state, the physical half-life of the more exotic iodine radioisotopes requires similar efforts. Thus, simple pipetting steps are mandatory for the preparation to fulfill the requirements speed and radiation protection. In addition, pipetting steps can be automated and help to optimize the latter aspect. 

Thirty isotopes are recognized. Only one stable isotope, 1271 is found in nature. The artificial radioisotope 1311, with a half-life of 8 days, has been used in treating the thyroid gland. The most common compounds are the iodides of sodium and potassium (KI) and the iodates (KIOs). Lack of iodine is the cause of goiter. 

Many of the uranium fission fragments are radioactive. Of special interest are technetium-99 [14133-76-7] and iodine-129 [15046-84-1] having half-Hves of 2.13 X 10 yr and 1.7 x 10 yr, respectively. Data on all isotopes are found in Reference 6 (see also Radioisotopes). 

The nuclear explosions that devastated Hiroshima and Nagasaki killed 100,000 to 200,000 people instantaneously. Probably an equal number died later, victims of the radiation released in those explosions. Millions of people were exposed to the radioactivity released by the accident at the Chernobyl nuclear power plant. The full health effects of that accident may never be known, but 31 people died of radiation sickness within a few weeks of the accident, and more than 2000 people have developed thyroid cancer through exposure to radioactive iodine released in the accident. Even low levels of radiation can cause health problems. For this reason, workers in facilities that use radioisotopes monitor their exposure to radiation continually, and they must be rotated to other duties if their total exposure exceeds prescribed levels. 

The utilization of radioisotopes in the field of nuclear medicine has been promoted for various purposes. Among them, diagnostic applications have had much success during the past two decades. Technetium-99m, thallium-210 and iodine-123, for example, have been used as radioisotopes for imaging studies. 

Triiodothyronine is not classified as a thyroid inhibitor it is an amino acid derivative of thyronine and results from the oxidative coupling of monoiodotyrosyl and diiodotyrosyl residues. Iodine 131, the most often used radioisotope of I, is rapidly absorbed by the thyroid and is deposited in follicular colloid. Prom the site of its deposition, Bll causes fibrosis of the thyroid subsequent to pyknosis and necrosis of the follicular cells. 

Iodine-131-labeled Lipiodol, a polyiodinated poppy seed oil which becomes particulate on dispersion in aqueous media, has been used for some time in treatment of hepatocellular carcinoma by arterial injection. This targeting approach has been coupled with the superior radioactivity properties of rhenium radioisotopes by exploiting the lipid solubility of... 

The isotope iodine-131 is an artificial radioisotope of iodine used as a tracer in biomedical research and as a treatment for thyroid disease. 1-131 has a half-hfe of about eight days, which means it will be eliminated from the body in several weeks. 

It has limited use in medicine as a radioactive source. It concentrates in the thyroid gland just like iodine, which makes it a useful radioisotope tracer. 

Several clinical trials have evaluated (or continue to evaluate) monoclonal antibodies to which a radioactive tag has been conjugated. These are usually employed as potential anti-cancer agents. The rationale is selective delivery of the radioactivity directly to the tumour site. Most of the radioisotopes being evaluated are /i-emitters these include I and I (iodine), Re and Re (rhenium) and (yttrium). The medium-energy radioactivity these emit is capable of penetrating... 

An allied application of radiolabelled anti-tumour monoclonal antibodies is that of diagnostic imaging (immunoscintigraphy). In this case, the radioisotope employed must be a y-emitter (such that the radioactivity can penetrate outward through the body for detection purposes). Although various radioisotopes of iodine have been evaluated, (technetium) is the one... 

Radioactive labels are -emitters selected on the basis of half-lives, the energies emitted, decay products, ease of labeling, availability and expense. Iodine isotopes 121,123, and 124, Indium 111, and Technetium 99 are the labels most widely used. The short half-lives of these labels (hours to days) means that radioimaging reagents are prepared immediately prior to treatment. Radioimaging of diseased tissue also provides useful information on the design of therapies that localize radioisotopes or toxins at tumor sites for therapy. 

Medical x-rays provided one of the first applications of radioisotopes. In 1914, the wounded from World War 1 were pouring into Paris hospitals. Marie Curie converted a Renault car into the first mobile radiological unit and drove it from hospital to hospital. Radioisotopes are now widely used in medicine to diagnose, study, and treat illness. A physician can determine, for example, how and at what rate the thyroid gland takes up iodine by using iodine-131 as a radioactive tracer and cobalt-60 is used to kill rapidly growing cancer cells. 

Like all first-order processes, radioactive decay is characterized by a half-life, f]/2, the time required for the number of radioactive nuclei in a sample to drop to half its initial value (Section 12.5). For example, the half-life of iodine-131, a radioisotope used in thyroid testing, is 8.02 days. If today you have 1.000 g of I, then 8.02 days from now you will have only 0.500 g of remaining because one-half of the sample will have decayed (by beta emission), yielding 0.500 g of MXe. After 8.02 more days (16.04 total), only 0.250 g of will remain after a further 8.02 days (24.06 total), only 0.125 g will remain and so on. Each passage of a half-life causes the decay of one-half of whatever sample remains, as shown graphically by the curve in Figure 22.2. The half-life is the same no matter what the size of the sample, the temperature, or any other external condition. 

In a RIA, the antibodies or antigen are labeled with a radioisotope such as iodine 125 or 131, tritium, or carbon-14. There are two types of RIA a liquid-... 

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