A processing method of generator-produced Ga-68 for radiopharmaceutical labeling

Objectives The Ga68 generator is one of the most important sources for preparing radiopharmaceuticals for clinical PET. It produces the Ga68 from Ge68 generator. However, the available impurities such as stable Zn generated by the decay of Ga68, Ti as a constituent of the column material, and Fe as a general impurity are not necessary for the synthesis of Ga68 labeled radiopharmaceuticals.The present procedure purifies initial Ga68 generator eluates chemically for the syntheses of Ga68 labelled radiopharmaceuticals.

Methods We have developed an efficient route for the processing of generator-derived Ga68 eluates. Purification of the initial generator eluate are performed using a miniaturized column with organic cation-exchanger resin(50WX4 @ BioRad) and 9N hydrochloric acid eluent for Ga68 ion adsorbed, and to use the 2N hydrochloric acid eluent for Ga68 ion deadsorbed. The purified fraction was used for the labeling of nanomolar amounts of DOTA-petide derivatives.

Results Using the generator post-eluate processing system, 95% of the initially eluated Ga68 activity was obtained within 5min as a 0.5 mL volume of a 2N hydrochloric acid. The initial amount of Ge-68, Zn, Ti, and Fe ions all were reduced by factors of 10⁵.

Conclusions Processing on a organic cation-exchanger resin in 9N/2N hydrochloric acid represents an efficient strategy for the purification of generator-derived Ga68 eluates. Thus, it is being successfully used in clinical validations for the use of automatic synthesizer ,and might contribute to the new direction for clinical PET from Ga-68 generator. The purified ionic Ga68 obtained in this way has been used to label several radiopharmaceuticals.