Title:Generator Breakthrough and Radionuclidic Purification in Automated Synthesis of 68Ga-DOTANOC
Volume: 6
Issue: 2
Author(s): Francesca Belosi, Gianfranco Cicoria, Filippo Lodi, Claudio Malizia, Stefano Fanti, Stefano Boschi and Mario Marengo
Affiliation:
Keywords:
68Ga, radionuclide generator, radionuclidic purity.
Abstract: 68Ga labeled radiopharmaceuticals, like 68Ga-DOATNOC and other similar peptides, are gaining relevance in
PET-CT, thanks to relatively easy local generator production, that do not requires an installed cyclotron. However, generator
produced 68Ga is typically of suboptimal purity, mainly due to the breakthrough of the parent radionuclide 68Ge.
Modern automated synthesis modules adopt both fractionation methods and purification methods in order to get rid of
68Ge breakthrough. Purification methods are mainly based on based on cationic prepurification even if anionic purification
has been adopted as well.
This work studies the efficacy of cationic prepurification using commercial STRATA-X-C, as well as distribution of the
68Ge contaminant during all steps of the synthesis of labeled peptides. Generator waste, STRATA-X-C purification cartridge,
synthesis waste and the final product are quantitatively analyzed by means of high resolution gamma ray spectrometry.
Our results show that current method of purification is highly effective; initial 68Ge breakthrough of the order of 1 kBq is
decreased by a factor greater than 100, with removal of about 61% of the contaminant 68Ge in the first purification passage;
this allow an efficient labeling, since removal of the remaining impurity happens during chelation in the reactor vessel.
In conclusion, the synthesis with modular automated system resulted to reliably produce 68Ga-DOTANOC, with limited if
any user intervention. 68Ge content in the final formulation results lower than 2x10-7%, avoiding unjustified patient irradiation
due to radionuclidic impurities and satisfying quality prerequisites for radiopharmaceutical preparations.
