Technetium-99m generator

Figure 7.10 Technetium-99m generator. (Adapted from references 88 and 89.)...

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. ... 

Boyd RE (1973) Recent developments in generators of " Tc (IAEA-SM-171/94) In Radiopharmaceuticals labelled compounds 1973. IAEA Vienna, pp 3-26 Boyd RE (1982) Technetium-99m generators - the available options. Int J Appl Radiat Isot 33 801-810... 

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. 

Clean-room assembly of technetium-99m generators. [ Mo04] is adsorbed on alumina in a cold kit generator, and radioactive decay produces [ c04P. 

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 ... 

Chan, H-K., Daviskas, E., Eberl, S., Robinson, M., Bautovich, G., and Young, I.H., Deposition of aqueous aerosol of technetium-99m diethylenetriamine pentaacetic acid generated and delivered by a novel system (AERx) in healthy subjects, Eur. J. Nucl. Med., 26 320-327 (1999). 

The field of nuclear medicine has grown tremendously in the last two decades largely as a result of the development of the Mo-99/Tc-99m generator system. The ready availability of Tc-99m created a mushrooming interest in nuclear medicine clinical and research activity. Technetium-99m in a variety of forms is annually used in millions of nuclear medicine procedures performed worldwide. During recent years there has been a significant increase in interest in very short-lived (<30 min)... 

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. 

In 1965, Richards and his collaborators at Brookhaven National Laboratories (N.Y.) have introduced the Mo/ Tc generator for clinical application (Richards 1966). This radionuclide system made technetium-99m available for clinical research and has stimulated the development of the first labeled compounds, which had a considerable impact on radiochemistry and nuclear medicine (Andros et al. 1965 Harper et al. 1966 McAfee et al. 1964a, b Stern et al. 1965, 1966). In the years to follow, diagnostic nuclear medicine procedures based on " Tc pharmaceuticals increased to approximately 85%. The reasons for this rapid growth were the ideal nuclear properties of techne-tium-99m, its availability worldwide as a radionuclide generator system, and the development of new labeling techniques. 

Peacock RD (1966) The chemistry of technetium and rhenium. Elsevier, London Perrier C, Segre E (1937) Radioactive isotopes of element 43. Nature 140 193-194 Perrier C, Segre E (1947) Technetium the element of atomic munber 43. Natiu"e 159 24 (Letter) Richards P (1966) Nuclide generators. In Radioactive pharmaceuticals. USAEC symposiiun series, no. 6, (CONF-651111), Oak Ridge, Term., pp 155-163 Rimmer J (1982) Radiopharmaceutical composition based on technetium-99m and the reagent for making it. Eur Patent Appl EP 78,642... 

Molinski VJ (1982) A review of " Tc-generator technology. Int J Appl Radial Isot 33 811-820 Nordic Council on Medicines (1989) Nordic guidelines. Radiopharmacy - preparation and control of radiopharmaceuticals in hospitals. NLN Publication No. 26, Uppsala Ponto JA, Swanson DP, Freitas JE (1987) Clinical manifestations of radio-pharmaceutical formida-tion problems. In Hladik WB 111, Saha GB, Study KT (eds) Essentials of nuclear medicine science. Williams Wilkins, Baltimore, pp 270-274 Richards P (1966) Nuclide generators. In Radioactive pharmaceuticals. USAEC Symposimn Series, No. 6, (CONE-651 111). Oak Ridge, Tennessee, pp 155-163 Richards P, O Brien MJ (1969) Rapid determination of Mo in separated " Tc. J Nucl Med 10 517 Richards P, Tucker WD, Srivastava SC (1982) Technetium-99m an historical perspective. Int J Appl Radial Isot 33 793-800... 

Technetium-99m ( Tc) is widely used in radiopharmaceutical preparations due to its excellent physical and chemical properties. In fact, more than 80% of all radiopharmaceuticals used in diagnostic nuclear medicine are based on this short-lived radionuclide, which is obtained by elution of a Mo/ Tc generator system that is available in any radiopharmacy and nuclear medicine facility. 

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. 

Hexamethylpropyleneamine oxime (HMPAO) stereoisomers and their technetium-99m complexes were resolved on a 40°C Chiralcel OD column [614]. The d- and /-uncomplexed isomers were separated in 20 min using a 97/3 hexane/IPA (0.01% diethylamine) mobile phase. The ""Tc complexes were also resolved but with an 85/15 hexane/IPA mobile phase. Temperature increases from 20°C to 40°C greatly improved peak shape and resolution. A table of resolution for the Tc complexes of meso-, d- and /-HMPAO was generated for 90/10 to 0/100 hexane/IPA mobile phases. Retention times for 65/35 to 85/15 hexane/IPA were also tabulated. For all these mobile phases the retention times were under 15 min. 

A list of radionuchdes commonly used for SPECT imaging is presented in Table 3.1. Technetium-99m ( Tc) and thaUium-201 ( T1) are generator produced, whereas galhum-67 ( Ga), indium-111 (" ln), and iodine-123 ( 1) are cyclotron produced (8). is a monovalent cationic metal that is used for cardiac imaging as a chloride salt. Ga is used in the form of Ga-citrate for imaging tumors and sites of inflammation. Both of these are commercially available for clinical use. In is used for imaging many different biological processes... 

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

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