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(Technetium Tc 99m Generator)
For the Production of Sodium Pertechnetate Tc 99m Injection
The Ultra-TechneKow™ DTE Generator is prepared with fission-produced molybdenum Mo-99 adsorbed onto alumina column shielded by lead, tungsten, or depleted uranium. This generator provides a closed system for the production of sterile metastable technetium Tc-99m, which is produced by the decay of molybdenum Mo-99. Sterile, nonpyrogenic isotonic solutions of Sodium Pertechnetate Tc 99m can be obtained conveniently by periodic aseptic elution of the generator. These solutions should be clear, colorless, and free from any particulate matter.
The carrier-free solution may be used as is, or diluted to the proper concentration. Over the life of the generator, an elution will contain an amount of technetium Tc-99m in direct proportion to the quantity of Mo-99 decay since the previous elution of the generator. The quantity of Tc-99m in the eluate is determined by quantity of Mo-99 on the column and the elapsed time between elutions.
Each eluate of the generator should not contain more than the USP limit of 0.15 kilobecquerel molybdenum Mo-99 per megabecquerel technetium Tc-99m (0.15 microcurie Mo-99 per millicurie Tc-99m) per administered dose at the time of administration and an aluminum ion concentration of not more than 10 micrograms per milliliter of the generator eluate, both of which must be determined by the user before administration.
Since the eluate does not contain an antimicrobial agent, it should not be used after 12 hours from the time of generator elution.
Technetium Tc-99m decays by isomeric transition with a physical half-life of 6 hours. The principal photon that is useful for detection and imaging studies is listed in Table 1.
Table 1: Principal Radiation Emission Data
|Radiation||Mean Percent Per Disintegration||Energy (keV)|
The specific gamma ray constant for technetium Tc-99m is 0.795 R/hr-mCi at 1 cm. The first half-value layer is 0.023 cm of lead (Pb). A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of Pb is shown in Table 2. For example, the use of 0.27 cm thickness of Pb will attenuate the radiation emitted by a factor of about 1000.
Table 2: Radiation Attenuation by Lead Shielding
|Shield Thickness (Pb) cm||Coefficient of Attenuation|
Molybdenum Mo-99 decays to technetium Tc-99m with a molybdenum Mo-99 half-life of 2.75 days, or 66 hours. The physical decay characteristics of molybdenum Mo-99 are such that only 88.6% of the decaying molybdenum Mo-99 atoms form technetium Tc-99m. Generator elutions may be made at any time, but the amount of technetium Tc-99m available will depend on the interval measured from the last elution. Approximately 47% of the maximum available technetium Tc-99m is reached after 6 hours and 95% after 23 hours. To correct for physical decay of molybdenum Mo-99 and technetium Tc-99m, the fractions that remain at selected intervals of time are shown in Tables 3 and 4.
Table 3: Physical Decay Chart, Molybdenum Mo-99,
Half-Life 66 Hours
|Days||Percent Remaining||Days||Percent Remaining|
Table 4: Physical Decay Chart; Technetium Tc-99m,
Half-Life 6 Hours
|Hours||Percent Remaining||Hours||Percent Remaining|
|* Calibration Time|
Last reviewed on RxList: 3/3/2014
This monograph has been modified to include the generic and brand name in many instances.
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