NUCLEAR PHARMACY The Relationship Between Elution Time and Eluate Volume Using the Ultra-TechneKowt DTE Technetium-99m Generator

Objective: The new Ultra-TechneKowt Dry Ship Top Elute 99mTc generator (UTKt-DTE generator; Mallinckrodt Medical, Inc., St. Louis, MO) was devised to facilitate fractionated elution with an ergonomically designed elution shield. Fractionation is accomplished traditionally by visually observing the eluted volume through 2 layers of leaded glass windows located in a lighted elution shield and generator auxiliary shield. The goal of our study was to use elution time to determine the endpoint for obtaining the required volume of 99mTc-eluate from a UTK-DTE generator. Methods: After triplicate elution at several predetermined elution times, the initial weight of the evacuated collecting vial was subtracted from the total weight after elution to determine the elution volume. Results: A quadratic relationship was established between the eluate volume (v, mL) and elution time (t, s) (v 5 0.3594 1 0.1889 t – 0.0009 t2). This equation is suitable for use with the 10-mL elution vial. This formula may not be accurate for the first elution since the UTK-DTE generator is a dry-column generator when shipped. The following elution times were calculated for some commonly eluted volumes: 2 mL (9 s), 4 mL (22 s), 5 mL (28 s), 7 mL (45 s), and 10 mL (88 s). Conclusion: Our calculated elution time method can be used to predict the eluate volume from a UTK-DTE generator.