Excitation functions of proton induced reactions on cobalt: Production of no-carrier added nickel-57, a positron emitting label for doxorubicin

Abstract

Excitation functions were measured, by the stacked-foil technique, for the 59Co(p, 3n) 57Ni and 59Co(p, 4n) 56Ni nuclear reactions from threshold up to 60 MeV. The excitation function for the 59Co(p, 3n) 57Ni reaction shows a maximum cross section of 13.8±1.5 mb at 38 MeV. The optimum energy range for production of 57Ni was found to be 41 → 26 MeV resulting in an experimental thick target yield of 19.3 MBq/μAh) (522 μCi/μAh). The level of the 56Ni impurity is only 0.21% at EOB giving a 57Ni product of 99.7% radionuclide purity at the time of use (24 h post EOB). Cross section data for the production of 56Ni, 56Co, 57Co, 58Co, 52Mn, 54Mn and 51Cr are also presented. A radiochemical procedure, based on cation-exchange chromatography, for the separation of radionickel from an activated cobalt target and other radiochemical and chemical impurities, has been developed. The 57Ni activity was eluted, using 2 M HCl from a Dowex-50W × 8(H +) column, in a 95% radiochemical yield (15 mL). The 57Ni has been used to label the anti-cancer drug, doxorubicin, thereby providing the means for pharmacokinetic and pharmacodynamic studies of this compound using positron emission tomography. The labelling has been optimized to give a radiochemical yield of >94%.