Endocrine Abstracts

We developed an improved process for producing high quality ⁶⁷Cu using an electron accelerator instead of a high energy proton accelerator. The beta/gamma emitting radioisotope ⁶⁷Cu was created using the (g,p) reaction on isotopically enriched ⁶⁸Zn target (nominally 40 g, 98% enrichment). The high energy photons were produced by bremsstrahlung conversion of electrons from a 45 MeV electron LINAC. A specially designed water cooled converter, end station and target were built and utilized for the transmutation. An additional system was designed and constructed for remote removal of the activated target. Following transmutation, the ⁶⁷Cu was separated from the isotopically enriched ⁶⁸Zn target using a two-step process: physical separation using low pressure evaporation/sublimation (<0.001 mbar, 600°C) and purification using anion exchange column chromatography (DOWEX 1X8, 200 mesh). The specific activity of the final product was determined using an ICP-MS and an HPGe detector. Radiolabeling was performed using ⁶⁷Cu produced from the process combined with multi-element standards (to measure sensitivity of chelate bonding to non-copper metals) and DOTA, CoSAR, NOTA and NODAGA chelates. We achieved a production yield >50 uCi g⁻¹.kW^-1.hr⁻¹ with a ⁶⁷Cu specific activity >20 Ci/mg. ICP-MS data indicated an average of <10 ng total Cu/mCi consistent with radiolabeled yields of 100% pmole chelate to total moles copper. The product is being produced and shipped to customers on demand, and at lower cost than proton accelerator produced isotope.