Long-Term Retrospective Evaluation of Radiochemical Yield Reproducibility of ⁶⁸Ga-Radiopharmaceuticals Using an SiO₂-Based ⁶⁸Ge/⁶⁸Ga Generator.

Abstract

BackgroundThe radiosynthesis of gallium-68 radiopharmaceuticals is influenced by the bifunctional chelating agents (BFCAs) used for chelation. The reaction parameters such as reagent concentration, pH, temperature and reaction time need to be carefully optimized for each targeting molecule to get the highest radiochemical yields. The parent radionuclide ⁶⁸Ge used for the preparation of the generator has half-life of 271 days and hence the ⁶⁸Ge/⁶⁸Ga generator is often used up to a year by which time the ⁶⁸Ge activity is ~ 40% of the load. However, the influence of generator aging on radiochemical yields have not been systematically reported, particularly with respect to different chelating agents in acetate buffer system.ResultsThe clinical doses of [⁶⁸Ga]Ga-HBEDCC-PSMA-11, [⁶⁸Ga]Ga-DOTA-TATE, and [⁶⁸Ga]Ga-DOTA-Exendin-4 were prepared using an SiO₂ organic matrix-based generator supplied by Isotope Technologies Garching (ITG) in a semi-automated module with a fluidic system. Three generators were used during the course of the study and the radiochemical yields were monitored till the end of the generator life. Fluctuations in radiochemical yields were observed as the generator aged in the radiosynthesis of [⁶⁸Ga]Ga-DOTA-TATE and [⁶⁸Ga]Ga-DOTA-Exendin-4 whereas it was unaffected with [⁶⁸Ga]Ga-HBEDCC-PSMA-11.ConclusionsThe radiochemical yields are influenced as the generator ages, however, the extent of influence will depend on the chelating agent and buffer systems used for making the targeting molecule.