Molybdenum-Technetium generator

Briner WH, Harris CC (1974) Radionuclide contamination of eluates from fission-product molybdenum-technetium generators. J Nucl Med 15 466-467 Council of Europe (2005 a) Sodium pertechnetatel Tc] injection (fission). Monograph No. 124. 

Radiopharmaceuticals containing c produced from molybdenum-technetium generators represent an additional somce of c to the environment. The... 

Most radioisotopes used in nuclear medicine are artificial. They are produced in nuclear reactors (e.g. Sr, Co), cyclotrons (e.g. C, F) or specialized generators such as a molybdenum-technetium generator. The metastable radioisotope ""Tc has a half-life of 6 hours and is important for medical imaging. It is a decay product of Mo - 2.8 days), which is itself man-made, being produced in a nuclear reactor. The radioactive decay of Mo to Tc and the much longer lived Tc is summarized below ... 

Rhenium (75) was discovered in 1925 by Ida Tacke and Walter Noddack as the last naturally occurring element. The first artificially produced element was identified by Emilio G. Segre in 1937. Ernest Lawrence detected technetium in a molybdenum sample, which he had bombarded in his cyclotron. All elements discovered since then have been generated artificially. 

It was the first new element to be produced artificially from another element experimentally in a laboratory. Today, all technetium is produced mostly in the nuclear reactors of electrical generation power plants. Molybdenum-98 is bombarded with neutrons, which then becomes molybdenum-99 when it captures a neutron. Since Mo-99 has a short half-life of about 66 hours, it decays into Tc-99 by beta decay. 

Heavy elements can also be produced in particle accelerators, which accelerate ions to high speeds, causing collisions that generate the new elements. Technetium, for example, is not found in nature but was first produced in 1937 when high-energy deuterons were directed at a molybdenum source ... 

A technetium-99m generator contains radioactive molybdenum-99 that decays to form technetium-99m. Hospitals can use the generator to produce and extract the short-lived technetium-99m just before it is needed in diagnostic techniques. ... 

A common example is technetium-99m. It has a half-life of only six hours. It is prepared in a small generator, often housed in a hospital s radiology laboratory (Figure 10.7). The generator contains radioactive molybdate ion (MoO/ ). Molybdenum-99 is more stable than technetium-99m it has a half-life of 67 hours. 

Non-radioactive chemicals are supplied as kits to be reconstituted with the radioactive eluate from a radionuclide generator such as a Molybdenum-d9/Technetium-99m generator at the hospital. These kits must conform to the requirements of pharmaceuticals as listed in the chapter on guidelines for small volume parenterals. 

At the same time that new instruments, such as the Anger camera, were being invented, chemists were developing technetium-99m labeled tracers, based on the reduction of sodium pertechnetate to technetium-tin complexes, the latter being a more useful diemical form for labeling molecules. Radionuclide generators in which molybdenum-99 decayed to technetium-99m made radiotracers readily available in nuclear medicine clinics in hospitals. One after the other new tests were invented and soon put into clinical practice. 

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. 

The most important pharmaceutical radionuclide produced by a nuclear reactor is molybdenum. This element is the mother radionuclide in a Mo/ " Tc-generator (see Sect. 15.6.4). During separation in this generator sodium "technetium pertechnetate is formed. Tc-pertechnetate is the most frequently used radiochemical for coupling to a pharmaceutical ligand in the preparation of diagnostic radiopharmaceuticals. 

Many radiology laboratories have small generators containing molybdenum-99, which decays to the technetium-99m radioisotope. 

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