Technetium-99m generator

Image:Technetium Generator.jpg A technetium-99m generator, or colloquially a technetium cow is a device used to extract the metastable isotope ^99mTc of technetiumfrom a source of decaying molybdenum-99. ⁹⁹Mo has a half-lifeof 66 hours and can be easily transported over long distances to hospitals where its decay product technetium-99m (with an inconvenient half-life of only 6 hours) is extracted and used for a variety of nuclear medicinediagnostic procedures.

Mechanism

The half-life of the mother nuclide (Mo) is much longer than that of the daughter nuclide (Tc). 50% of equilibrium activity is reached within one daughter half-life, 75% within two daughter half-lives. Hence, removing the daughter nuclide from the generator ("milking" the generator) is reasonably done every 6 hours or, at most, twice daily in a Mo-99/Tc-99m generator. Most commercial Mo-99/Tc-99m generators use column chromatography, in which Mo-99 is adsorbed onto alumina. Pulling normal saline through the column of immobilized Mo-99 elutes the soluble Tc-99m, resulting in a saline solution containing the Tc-99m which is then added to an appropriate concentration to the organ-specific pharmaceutical to be used. The Isotope can also be used without pharmaceutical tagging for specific procedures requiring only the Tc-99m as the primary radiopharmaceutical. The useful life of a Mo-99/Tc-99m generator is about 3 half lifes or approximately one week. Hence, any clinical nuclear medicine units purchase at least one such generator per week or order several in a staggered fashion.

^{99Mo is obtained by the neutronactivation (n? reaction) of 98Mo in a high neutron flux reactor. As an alternative method an enriched uraniumtarget can be irradated with neutronsto form 99Mo as a fission product[1].}

External links

• Brookhaven National Laboratory site on the history of the technetium cow.

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It uses material from the http://en.wikipedia.org/wiki/Technetium-99m+generator Wikipedia article Technetium-99m generator.