Detailed evaluation of different 68Ge/68Ga generators: an attempt toward achieving efficient 68Ga radiopharmacy

The present study is aimed at carrying out a comparative performance evaluation of different types of Ge-68/Ga-68 generators to identify the best choice for use in Ga-68-radiopharmacy. Over the 1year period of evaluation, the elution yields from the CeO2-based and SiO2-based Ge-68/Ga-68 generators remained almost consistent, in contrast to the sharp decrease observed in the elution yields from TiO2 and SnO2-based generators. The level of Ge-68 impurity in Ga-68 eluates from the CeO2 and SiO2-based Ge-68/Ga-68 generator was always <10(-3)%, while this level increased from 10(-3)% to 10(-1)% in case of TiO2 and SnO2-based generators. The level of chemical impurities in Ga-68 eluates from CeO2 and SiO2-based Ge-68/Ga-68 generators was negligibly low (<0.1ppm) in contrast to the significantly higher level (1-20ppm) of such impurities in eluates from other two generators. As demonstrated by radiolabeling studies carried out using DOTA-coupled dimeric cyclic RGD peptide derivative (DOTA-RGD(2)), CeO2-PAN and SiO2-based generators are directly amenable for radiopharmaceutical preparation, whereas the other generators can be only used after post-elution purification of Ga-68 eluates. Clinically relevant dose of Ga-68-DOTA-RGD(2) was prepared in a hospital radiopharmacy for non-invasive visualization of tumors in breast cancer patients using positron emission tomography.