Technetium-99m generator

You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.

A technetium-99m generator, or colloquially a technetium cow is a device used to extract the metastable isotope ^99mTc of technetium from a source of decaying molybdenum-99. ⁹⁹Mo has a half-life of 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 for transport) is extracted and used for a variety of nuclear medicine diagnostic procedures, where its low half-life is very useful.

Mechanism

The half-life of the mother nuclide (⁹⁹Mo) is much longer than that of the daughter nuclide (^99mTc). 50% of equilibrium activity is reached within one daughter half-life, 75% within two daughter half-lives. Hence, removing the daughter nuclide (elution process) from the generator ("milking" the cow) is reasonably done every 6 hours or, at most, twice daily in a ⁹⁹Mo/^99mTc generator. Most commercial ⁹⁹Mo/^99mTc generators use column chromatography, in which ⁹⁹Mo is adsorbed onto acid alumina (Al₂O₃). Pulling normal saline solution through the column of immobilized ⁹⁹Mo elutes the soluble ^99mTc, resulting in a saline solution containing the ^99mTc 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 ^99mTc as the primary radiopharmaceutical. The useful life of a ⁹⁹Mo/^99mTc generator is about 3 parent half lives, 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 can be obtained by the neutron activation (n,γ reaction) of ⁹⁸Mo in a high neutron flux reactor. The most used method requires a uranium target with high enriched uranium (up to 90% ²³⁵U) or low enriched uranium (less than 20% ²³⁵U). The target should be irradiated with neutrons to form ⁹⁹Mo as a fission product [1].

External links

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

Template:Nuclear-stubde:Technetium-99m Generator