The pair 99Mo (t½= 66 h)/99mTc (t½= 6 h) represents a transient equilibrium system. The radiochemical general design of a 99Mo/99mTc generator is to absorb 99Mo as polymolybdate on alumina columns of e.g., 7 cm length and 1 cm diameter. The 99mTc generated is eluted by, e.g., 10 ml of saline. The 99Mo remains on the column due to formation of heteropolymolybdate structure with the alumina matrix. It separates 99mTc in the chemical form of 99mTc-pertechnetate TcO4– . If not used directly for molecular imaging of the thyroid function (see below), the generator eluate is directly added to a vial containing a lyophilized labeling kit with the appropriate labeling precursor to more or less instantaneously yield a 99mTc-radiopharmaceutical. Different elution vials (evacuated and sterile) are commercially available.
Scheme of the 99Mo/99mTc generator system (left) and picture of the Mallinckrodt 99Mo/99mTc generator Ultra-Technekow™ (right).
Ready-to-use sterile, evacuated vials (TechneVial™, Mallinckrodt) for elution of the 99Mo/99mTc generator.
