Production of Ga-68 with a General Electric PETtrace cyclotron by liquid target

Purpose: In recent years the use of Ga-68 (t(1/2)= 67.84 min, beta(+): 88.88%) for the labelling of different PET radiopharmaceuticals has significantly increased. This work aims to evaluate the feasibility of the production of Ga-68 via the Zn-68(p, n) Ga-68 reaction by proton irradiation of an enriched zinc solution, using a biomedical cyclotron, in order to satisfy its increasing demand. Methods: Irradiations of 1.7M solution of Zn-68(NO3)(2) in 0.2 N HNO3 were conducted with a GE PETtrace cyclotron using a slightly modified version of the liquid target used for the production of fluorine-18. The proton beam energy was degraded to 12 MeV, in order to minimize the production of Ga-67 through the Zn-68(p, 2n) Ga-67 reaction. The product's activity was measured using a calibrated activity meter and a High Purity Germanium gamma-ray detector. Results: The saturation yield of Ga-68 amounts to (330 +/- 20) MBq/mu A, corresponding to a produced activity of Ga-68 at the EOB of (4.3 +/- 0.3) GBq in a typical production run at 46 mu A for 32 min. The radionuclidic purity of the Ga-68 in the final product, after the separation, is within the limits of the European Pharmacopoeia (> 99.9%) up to 3 h after the EOB. Radiochemical separation up to a yield not lower than 75% was obtained using an automated purification module. The enriched material recovery efficiency resulted higher than 80-90%. Conclusions: In summary, this approach provides clinically relevant amounts of Ga-68 by cyclotron irradiation of a liquid target, as a competitive alternative to the current production through the Ge-68/Ga-68 generators.