Optimization of production yields, radionuclidic purity and hotcell shielding of SPECT and PET radionuclides produced by proton irradiation in variable energy 30 MeV cyclotrons—Part 67Ga

Optimization of the production parameters (incident and exit proton energy, thickness of the 68Zn target layer, decay time to start chemical processing of an irradiated target after the end of bombardment) and of the thickness of the lead shield of the processing hotcell for the cyclotron production of 67Ga by the 68Zn(p,2n) threshold reaction are accomplished by powerful divide et impera and binary search algorithms with the Pharmacopoeia radionuclidic purity of the 67Ga-citrate radiopharmaceutical at a reference time and the locally accepted dose rate level for the controlled area as boundary conditions. Two sets of equations are presented (one associated with the maximum production rate, the other with the use of a minimum target layer thickness) that allow the expression of the optimized production parameters, the radionuclide yields satisfying the Pharmacopoeia requirements at the start of distribution and the necessary shielding as a function of the required activity at the start of distribution and of the maximum allowable beam current on target.