Practical production of 61Cu using natural Co target and its simple purification with a chelating resin for 61Cu-ATSM

Copper-61 (T-1/2 = 3.41 h) produced via the Co-59(alpha, 2n)Cu-61 nuclear reaction using natural Co target was isolated from the irradiated target by two methods developed here and applied for preparation of (Cu-61-ATSM) (Cu-61-diacetyl-bis(N-4-methylthiosemicarbazone)), known as an imaging agent of hypoxic tissue. A commercially available cobalt disk (thickness: 125 mum) was irradiated with 40 MeV (37.9 MeV on target) a particles, then treated with conc. HNO3, and the Cu-61 was separated by two different methods, i.e. a two column method using a cation and an anion exchange column; and a one Column method using a column packed with chelating resin, Chelex 100. Both separation methods gave satisfactory results, though the latter method was superior because of the simplicity of the apparatus, the separation procedure and somewhat shorter processing time. Around 1.1 GBq of 61Cu(2+) were obtained with >95% yield (decay corrected) from Co target at 10 I-LA for 1 h irradiation, and with the radionuclidic purity of >98% (EOS). The only radionuclidic impurity in the isolated Cu-61(2+) solution was identified to be Cu-60 at EOS but no radionuclidic impurity was observed after 50 hours. The solution of Cu-61-ATSM was prepared in >85% radiochemical yield with >95% radiochemical purity.