EFFECTIVE METHOD TO MINIMIZE MOLYBDENUM CONTENT OF 99MOLYBDENUM-99mTECHNETIUM GENERATOR ELUATE

Abstract

99mTc is the work horse of every nuclear medicine department. It is obtained by the elution of a 99Molybdenum-99mTechnetium (99Mo-99mTc) generator. Molybdenum-99 (t1/2 = 66 h) decays by beta emission to 99mTc (87%) and 99Tc (13%), emitting photons of 740 and 778 keV.1 Ideally, 99mTc eluates contain no radionuclide impurity. However, as a consequence of generator aging or possible occurrence of a mechanical defect, 99Mo may also be extracted from the column during this elution process (Molybdenum breakthrough), becoming a contaminant in the eluate to be administered to the patient. The presence of 99Mo in the radiopharmaceutical solution injected in the patient represents an unnecessary radiation dose to the patients; the dose coefficient for 99Mo is about 50 times higher than that of 99mTc. The International Atomic Energy Agency (IAEA) safety standard recommends that any eluate containing more than 0.15 uCi of Mo- 99 / mCi of Tc-99m should no be injected to human.2 In the USA, a licensee is also required to perform the test and retain records in accordance with 10CFR35.204. Molybdenum break through (MBT) must also be determined at least for the first elution of a particular generator.3, 4