Iodine-131, medical applications

Although the fission products could be recovered as byproducts from the waste from spent nuclear reactor fuel, special-purpose neutron irradiation of highly enriched uranium (isotopically separated uranium-235) followed by chemical separation is the normal production method. The major products, molybdenum-99 and iodine-131 with fission yields of 6.1 and 6.7 percent, respectively, have important medical applications. Mo-99,... 

Other accelerator-produced radionuclides are also used in nuclear medicine (Table 19.2). One of the most important radionuclides in this group is This radioisotope of iodine has more favourable properties than it emits only y radiation and its relatively short half-life is more appropriate for medical application. Its production is described in section 12.1. Suitable accelerators for the generation of protons of relatively high energy, and transport facilities, are needed. 

Iodine was discovered in 1811 by French chemist Bernard Courtois (1777—1838). The element occurs primarily in seawater and in solids formed when seawater evaporates. Its single most important property may be the ability to kill germs. It is used in antiseptics, germicides (products that kill germs), and other medical applications. However, it has a great many other important commercial applications. 

A number of iodine isotopes are used commercially. In medical applications, these isotopes are injected into the body or given to the patient through the mouth. The isotopes then travel through the body in the bloodstream. As they travel, they give off radiation. That radiation can be detected by using X-ray film. A medical specialist can tell how well the body is functioning by observing the pattern of radiation. 

Iodine-12 3 concentrates in the thyroid gland, liver, and certain parts of the brain. This radioisotope is used to monitor goiter and other thyroid problems, as well as liver and brain tumors. One of the most useful radioisotopes in medical applications in recent years is an isotope of technetium, an element that does not occur naturally on earth. This isotope, 99m P(, jg produced by the decay of Mo. 

Nuclear properties of major iodine isotopes in medical applications are presented. 

Except for and other isotopes of iodine occur in the thyroid and urine only for a short time, due to their short half life (<60 days). 8j and are very seldom used for medical purposes except for the use of in the very early period of medical applications of radioisotopes (Becker and Sawin, 1996). and... 

PoIy(N-vinylpyrrolidinone) (PNVP) has been used in medical applications for many years. Its history can be traced back to the Second World War where in its un-crosslinked form it was used as a blood plasma expander (I). This un-crosslinked PNVP when added to iodine forms a complex, in solution this complex is better known as Povidone-iodine or by its trade name Betadine , a surgical antiseptic. PNVP is also used as a binder in many pharmaceutical tablets as low molecular weight PNVP can be removed from the body by the kidneys. These polymers have also been investigated for use as wound dressings, drug... 

Lithium-iodine (Li-Ij) batteries were specifically designed and developed for medical applications. These batteries consistently demonstrated the best performance and suitability, particularly for pacemakers, over a period exceeding 25 years. This particular battery is high in energy density but low in power level. Li-Ij is a low-conductivity solid-state electrolyte, which limits the current to a few microamperes. According to the manufactures, an operational life ranging from 7 to 12 years for this battery has been demonstrated in the field. The battery suppliers claim that these batteries could be used in other applications, such as watches and memory-retention devices. 

Another case-positive cell type has been used for medical applications. This unit is very similar to the other case-positive designs, but the cathode is not poured into the battery can. The iodine and P2VP are pelletized and then pressed onto the central anode assembly. After the pressing operation, the entire unit is slipped into a nickel can. An exploded view of this cell is shown in Fig. 15.10. 

Another possibility of medical application of the polyhedral boron hydrides is X-ray contrasting imaging. Highly iodinated molecules have application in medicine as X-ray contrast agents due to the opacity of the iodine atoms to low energy X-rays [262]. Even with the recent phenomenal growth of MRI and ultrasoimd procedures. X-ray imaging studies... 

Because of its medical applications, iodine-123 has been the most extensively investigated iodine isotope from the preparative viewpoint. Both direct and Indirect methods of preparation have been developed, the reactions for the best methods being ... 

Thyroid dysfunction is a fairly common disorder to be found in clinical practice. The thyroid synthesizes two hormones, triiodothyronine (T ) and thyroxine (T4), dipeptides containing 3 and 4 atoms of iodine respectively in each molecule. The thyroid stimulates cell metabolism of most tissues, might cause hypermetabolism symptoms loss of weight in spite of increased appetite, palpitations, tremor of the fingers, anxiety, heat intolerance. The hormone activity is mainly carried out by T3. Most of it derives by monodeiodination from T4 that is secreted directly by the thyroid. Both hormones in the blood are bound to plasma proteins. In the development of medical applications of microcalorimetry, among the first pathological conditions to be studied were thyroid dysfunctions. 

Polyether compounds form stable adducts with iodine, a property which has led to their use as iodophores for bactericides on human and animal skin. For medical applications, iodide concentration is kept low, since the triiodide ion has little disinfecting activity compared to iodine. By contrast, iodine-based analytical methods for surfactant determination are usually conducted in the presence of a large excess of pxjtassium iodide. The likely mechanism consists of the K" -p)olyether complex associating with the large, lipophilic, triiodide anion. The absorbance maximum of the complex is shifted from that of triiodide... 

In the case of primary batteries it is most important to consider the intended purpose. Miniaturizable low power batteries of great reliability find important apph-cations in measurement devices (e.g. clocks), circuits and heart pacemakers. One system which refers to the last mentioned, medical application and which is now classic, is the Li-l2 battery. Here the iodine is introduced as an electronically conducting charge transfer complex (e.g. as polyvinylpyridine) [672]. This does reduce the chemical potential of iodine and, hence, the cell voltage but guarantees a sufficient electronic conductivity and improves the handling properties. The key is that... 

Li2S204 being the SEI component at the Li anode and the solid discharge product at the carbon cathode. The Li—SOCI2 and Li—SO2 systems have excellent operational characteristics in a temperature range from —40 to 60 °C (SOCI2) or 80 °C (SO2). Typical applications are military, security, transponder, and car electronics. Primary lithium cells have also various medical uses. The lithium—silver—vanadium oxide system finds application in heart defibrillators. The lithium—iodine system with a lithium iodide solid electrolyte is the preferred pacemaker cell. 

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. 

The lithium/iodine-poly-(2-vinyl pyridine) system has some unique properties. Its major application is in implantable medical devices such as cardiac pacemakers, which operate at a thermostatted 37°C [28], The reaction is... 

XRF is not a new method since the first measurements of stable iodine in the thyroid by Hoffer et al. (1968), the use of XRF has spread to include several other elements in medical apphcations, as well as applications in occupational and environmental surveillance. Today, XRF is primarily used as a nondestructive method for investigation of metals, minerals, environmental samples, food constituents, and body fluids. Examples of in vivo XRF elemental analysis are measurements of lead in bone (Ahlgren and Mattsson, 1979 Somervaille et al., 1985 Todd and Chettle, 1994) and studies on cadmium, mercury, gold, and platinum (Ahlgren and Mattsson, 1981 Borjesson et al, 1993, 1995), but the method is not, to our knowledge, used clinically as a tool in the routine assessment of thyroid function. Some in vivo applications of the method are listed in Table 3.1. 

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