Uses of technetium

Among the technetium isotopes, only Tc, a pure emitter ( ,nax=0.29 McV) with a half-life of 213 000 a, can be obtained (Sect. 5.1) in amounts adequate for studying the technical applicability of the element and its compounds. However, the widespread use of technetium is necessarily restricted by its radioactivity. The application of the metastable isotope Tc in nuclear medicine has quite superior significance and will be described in detail in Part B. 

---

The use of technetium-99m (half-life = 6.006 h) in diagnostic medicine , particularly for brain and heart imaging " , has became widespread since the availability of macroscopic quantities of the long-lived technetium-99 isotope from fission products (half-life =2.13 X 10 yr, weak j8"-emiter, = 0.292 MeV, = 85keV. Normal glassware... 

Uchida T, Nemoto T, Yui T et al (1979) Use of technetium-99m as a radioactive label to study migratory patterns of leukocytes. J Nucl Med 20 1197-2000 Vallabhajosula S, Machac J, Goldsmith SJ et al (1986) Indium platelet kinetics in normal human subjects tropolone versus oxine methods. J Nucl Med 27 1669-1674... 

Voeller GR, Bunch G, Britt LG (1991) Use of technetium-labeled red blood cell scintigraphy in the detection and management of gastrointestinal hemorrhage. Surgery 110 799-804... 

A variety of radiotracers are used in clinical work, the most used isotopes being technetium-99m, iodine-131, tantalum-201, xenon-133, and indium-113m. The use of technetium, Tc, dominates, since it can be made to react with many substances having specific biological behavior. Tc is obtained from an isotope generator, which is based on the radioactive decay of radioactive molybdenum, Mo. Pharmaceuticals containing Tc are usually introduced by intravenous injection. Some radiopharmaceuticals may also be introduced orally, e.g., for those containing iodine this is the common procedure. 

Complexes of the diphosphonic acid (12.125b) with y-ray-emitting isotopes of technetium are useful for medical diagnostic work since they concentrate in the bone. The use of technetium diphosphonate complexes for bone imaging (MRl below) has revolutionised bone-scanning techniques. Technetium pyrophosphate complexes are less satisfactory since the P-O-P linkages are liable to hydrolysis by body enzymes [11,12]. 

From the Nuclear Reactor to the Human Body - The Medical Uses of Technetium... 

Technetium-99m coordination compounds are used very widely as noniavasive imaging tools (35) (see Imaging technology Radioactive tracers). Different coordination species concentrate ia different organs. Several of the [Tc O(chelate)2] types have been used. In fact, the large majority of nuclear medicine scans ia the United States are of technetium-99m complexes. Moreover, chiral transition-metal complexes have been used to probe nucleic acid stmcture (see Nucleic acids). For example, the two chiral isomers of tris(1,10-phenanthroline)mthenium (IT) [24162-09-2] (14) iateract differentiy with DNA. These compounds are enantioselective and provide an addition tool for DNA stmctural iaterpretation (36). 

Technetium-99m (the m signifies a metastable, or moderately stable, species) is generated in nuclear reactors and shipped to hospitals for use in medical imaging. The radioisotope has a half-life of 6.01 h. If a 165-mg sample of technetium-99m is shipped from a nuclear reactor to a hospital 125 kilometers away in a truck that averages 50.0 kmh. what mass of technetium-99m will remain when it arrives at the hospital ... 

C22-0120. Technetium has no stabie isotopes. Which nuciide of this eiement wouid you predict to be neariy stabie (Make use of Figures 22-5 and. )... 

Lloyd JR, J Ridley, T Khizniak, NN Lyalikova, LE Macaskie (1999) Reduction of technetium by Desulfo-vibrio desulfuricans biocatalyst characterization and use in a flowthrough bioreactor. Appl Environ Microbiol 65 2691-2696. 

ICP-MS (inductively coupled plasma mass spectrometry) is frequently used for determining ultratrace amounts of technetium [9]. In spite of the high cost of the equipment, this detection method is far superior to other radiometric methods as regards sensitivity. When a double focussing high-resolution system is used (HR-ICP-MS) and an ultrasonic nebulizer is introduced [10], the detection limit is in the order 0.002 mBq. The ICP-MS method has been successfully applied to the determination of environmental "Tc as well as to other long-lived radionuclides of neptunium and plutonium in the environment. 

Transfer of technetium from seawater to animals has been studied by laboratory experiments using 95mTc, The advantages of 95mTc over "Tc are 95mTc emits y-rays, thus whole-body counting techniques can be used, and it has a sufficiently high specific activity because of its relatively short half life (61 d). 

Until the mid 1970s, technetium(V) had been widely ignored and its chemistry misinterpreted. Then, the development of the chemistry of technetium(V) was prompted by the trends and needs of nuclear medicine, which predominantly uses technetium-99m radiopharmaceuticals for a broad range of diagnostics. 

Another type of ligand is the monoanionic, tridentate oxygen donor [(C5H4R)Co-(P(0)R R")3] (Lor), which has been used to prepare the complexes of technetium [37] and rhenium [38] [M03L] and [MOX2L] (X Cl, Br). These complexes are stable in organic solvents but hydrolyse slowly in water. In order to evaluate their usefulness in radioimmunotherapy, the corresponding compounds were also prepared with radioactive rhenium isotopes. 

---