Cyclotron production of $61Cu$ using natural Zn & enriched $64Zn$ targets

Copper-61 (⁠$61Cu$⁠) shares with $64Cu$ certain advantages for PET diagnostic imaging, but has a shorter half-life (3.4hr vs. 12.7hr) and a greater probability of positron production per disintegration (61% vs. 17.9%). One important application is for in vivo imaging of hypoxic tissue. In this study $61Cu$ was produced using the $64Zn(p,α)61Cu$ reaction on natural Zn or enriched $64Zn$ targets. The enriched $64Zn$ (99.82%) was electroplated onto high purity gold or silver foils or onto thin Al discs. A typical target bombardment used 30μA; at 11.7, 14.5 or 17.6MeV over 30-60min. The $61Cu$ (radiochemical purity of >95%) was separated using a combination of cation and anion exchange columns. The $64Zn$ target material was recovered after each run, for re-use. In a direct comparison with enriched $64Zn$-target results, $61Cu$ production using the cheaper ^natZn target proved to be an effective alternative.