Rapid Ge-68 breakthrough testing for 68Ge/68Ga portable generators

Objectives 68Ge/68Ga generators are a promising addition to the molecular imaging clinic. They are portable and offer years of useful life, delivering tracers for high resolution PET imaging to locations far from cyclotrons. Labels for 68Ga are already in use, and their repertoire and applications are expanding. 68Ga is being used clinically in Europe and parts of Asia, but its implementation in the USA is restricted to research and animal use because of safety concerns related to possible 68Ge breakthrough. The methods for ensuring safety in 99Mo/99Tc and 82Sr/82Rb generator elutions (i.e., activity while shielding the daughter nucleotide’s weaker radiation) are not applicable for 68Ge/68Ga generator elutions.

Methods The portable chemical analysis system uses electrophoresis to separate Ge4+ and Ga3+ ions and quantify their existence through sensitive capacitative conductivity monitoring. This monitoring method can detect minute quantities in minutes, which would otherwise take hours of radioactive count collection.

Results Initial results show 95% reliability in detecting Ge-68 at the nanomolar level.

Conclusions We have developed a prototype portable chemical analysis system to rapidly measure the amount of Ge-68 breakthrough in each elution from 68Ge/68Ga generators.