Fine Tuning 68Ga Production with a Liquid Target: Effect of Solution Composition and Irradiation Parameters
Mukesh K Pandey1, John P. Byrne2 and Nicholas R. Schmit1, Timothy R DeGrado1
1Department of Radiology, Mayo Clinic Rochester, MN USA 2Brigham and Women’s Hospital Boston MA USA
Oral Presentation
Two pending international patents in this research space.
With the goal of optimizing 68Ga production yields using a liquid target, the relationship of 68Zn nitrate concentration, nitric acid concentration, and proton irradiation parameters (beam current and irradiation time) to 68Ga saturation yield were investigated. The Brigham-Mayo liquid target-2 (BMLT-2)1 was employed on a 16 MeV PETtrace cyclotron with beam energy degradation to ~14 MeV by a 0.2mm aluminum foil. Varying molar concentrations of 68Zn-nitrate (0.5 M and 1.0 M,) in 0.8 and 1.5N nitric acid were prepared and irradiated at 30, 40, 45 and 50 µA beam currents at 30 and 60 min time points. The unprocessed 68Ga production (EOB) and saturation yields were evaluated across the varied conditions. For select conditions, 68Ga- isotope was purified using the in-house developed hydroxamate resin as described previously by Pandey et al.2-4 and optimized for further application. Of the conditions tested, the maximum 68Ga production yield was 7037.4 MBq (EOB) obtained for irradiation of 1 M 68Zn nitrate in 0.8 N nitric acid at 45 µA for 60 min. The results show that 68Ga production yield is dependent on a complex interaction of irradiation parameters that include 68Zn nitrate concentration, normality of nitric acid, beam current and irradiation time.
Some interesting in target chemistry taking place here but the data raise more question than answers.
Good discussions should follow.