⁶⁸Ga Generator Integrated System: Elution–Purification–Concentration Integration

Abstract

A ⁶⁸Ge/⁶⁸Ga generator combined with an automated ⁶⁸Ga eluate purification–concentration unit [radioisotope generator integrated system (RADIGIS)], specially designed for ⁶⁸Ga processing (RADIGIS-⁶⁸Ga), was developed. The high-stability sorbents of a nanocrystalline structure Zr-Ti ceramic matrix were used for immobilizing the ⁶⁸Ge, and the ⁶⁸Ga was eluted from the sorbent column with 3.5 mL 0.05–0.1 M HCl solution following an optimized ⁶⁸Ga-elution schedule. The ⁶⁸Ge breakthrough <10⁻³% and no ⁶⁸Ge zone spreading/drift found in PET imaging of the ⁶⁸Ga generator column prove the excellent performance of the sorbents. ⁶⁸Ga eluate was purified on a small column of salt-form ion exchange resin using an aqueous alcohol solution mixture of hydrochloric and ascorbic acids, and halide salts. An alkali solution was used for stripping ⁶⁸Ga from the ion exchange resin column to obtain a purified ⁶⁸Ga solution, which is conditioned with acidic solution to obtain a final ⁶⁸Ga product in either 0.75 mL 0.5 M NaCl solution of pH 3–4 or 0.5 M sodium acetate or citrate solution of pH 5. The ⁶⁸Ge content in purified ⁶⁸Ga solution was <10⁻⁶%. An insignificant metallic contamination including ⁶⁸Zn found in the ⁶⁸Ga solution and its alkalinity–acidity were evaluated with respect to ⁶⁸Ga radiolabeling efficacy for DOTATATE and DOTATOC ligands. Quality control protocols were also developed to evaluate the quality of ⁶⁸Ga solution.