Development of a large scale production of 67Cu from 68Zn at the high energy proton accelerator: Closing the 68Zn cycle

A number of research irradiations of Zn-68 was carried out at Brookhaven Linac Isotope Producer aiming to develop a practical approach to produce the radioisotope Cu-67 through the high energy Zn-68(p,2p)Cu-67 reaction. Disks of enriched zinc were prepared by electrodeposition of Zn-68 on aluminum or titanium substrate and isolated in the aluminum capsule for irradition. Irradiations were carried out with 128, 105 and 92 MeV protons for at least 24 h. After irradiation the disk was chemically processed to measure production yield and specific activity of Cu-67 and to reclaim the target material. The recovered Zn-68 was irradiated and processed again. The chemical procedure comprised BioRad cation exchange, Chelex-100 and anion exchange columns. Reduction of the oxidation degree of copper allowed for more efficient Cu/Coan separation on the anion exchange column. No radionuclides other than copper isotopes were detected in the final product. The chemical yield of 67Cu reached 92-95% under remote handling conditions in a hot box. Production yield of Cu-67 averaged 29.2 mu Ci/[mu A - h x g Zn-68] (1.08 MBq/[mu A-h x g Zn-68]) in 24 h irradiations. The best specific activity achieved was 18.6 mCi/mu g (688.2 MBq/mu g). (C) 2011 Elsevier Ltd. All rights reserved.