Experience of non metallic silica based ⁶⁸Ge/⁶⁸Ga ITG generator: ⁶⁸Ga labelled radiopharmaceuticals

Continuous development of ⁶⁸Ge/⁶⁸Ga generator system open a new era in development of ⁶⁸Ga labelled radiopharmaceuticals. Earlier generator system used metallic column made up of alumina, TiO₂, SnO₂ and pyrogallolformaldehyde organic resin as an adsorbent. ITG developed new generator system which uses non-metallic silica based column and 0.05M HCL as eluate. Non-metallic column yields Ga (III) in pure ionic form which further improves final yield of labelled product. Hence, we have evaluated labelling efficiency of ⁶⁸Ga labelled radiopharmaceuticals using ITG ⁶⁸Ge/⁶⁸Ga generator system. We assessed the labelling performance of two ITG ⁶⁸Ge/⁶⁸Ga generator systems of 30mci each. ITG provided self-shielded iQS fluidic module for labelling purpose. First generator was replaced after six month of installation. We performed 33 labelling procedure for ⁶⁸Ga-DOTANOC and 10 for PSMA using first generator. After inception of second generator since July 2015, we labelled ⁶⁸Ga –PSMA (n = 30) and ⁶⁸Ga-DOTANOC (n = 13). 25 μgm of peptide (DOTANOC Acetate) and 900μl of 0.25M sodium acetate was used for labelling with ⁶⁸Ga. For ⁶⁸Ga-PSMA labelling 5 μgm of peptide (DKFZ-PSMA- 11) and 1ml of 0.25M sodium acetate buffer was used. Elution was done with 0.05M HCL. After heating for 10 min at 100℃ labelled ⁶⁸Ga-DOTANOC product was passed through C8 cartridge and ⁶⁸Ga-PSMA through C18 cartridge. Labelled product was extracted with 50% ethanol as an eluent. Waste and product got collected in separate vials. pH of labelled product was measured. Radiochemical purity of ⁶⁸Ga-DOTANOC was determined by ITLC method using 0.1M tri-sodium acetate as a solvent. Radiochemical stability was evaluated after 2-3 hrs. Results and We calculated labelling efficiency of ⁶⁸Ga labelled product using both generators. Using first generator labelling efficiency of ⁶⁸Ga-DOTANOC was 71% (n = 24, SDEV=0.065, pH=5.5).Low yield was reported nine times (40-55%). Low yield of ⁶⁸Ga-PSMA was 45-60% (n = 3). Labelling efficiency of ⁶⁸Ga-PSMA was 79 % (n = 7, SDEV=0.072, pH=5.5). Radiochemical purity was >93%. RCP was >90% after 3 hrs. (author)