Development of a high performance zinc-62/copper-62 radionuclide generator for positron emission tomography.

Clinical utilisation of positron emission tomography could be enhanced by the availability of short-lived radionuclides derived from generator systems. The zinc-62/copper-62 combination is one such system which could be used as a source for a number of copper-62 radiopharmaceuticals. We have developed and optimised a high activity (5.6 GBq, 150 mCi) zinc-62/copper-62 generator to provide 62Cu in a form that is suitable for direct labelling of pyruvaldehyde-bis-(N4-methylthiosemicarbazone)-copper(II), Cu(PTSM). The distribution coefficients of Zn(II) and Cu(II) between anion-exchange resin and various hydrochloric acid/organic solvent mixtures were measured. Based on these measurements a generator eluent of 0.3 M HCl/40% ethanol provided 62Cu in greater than 90% yield in a 3-ml volume. A very low 62Zn breakthrough of less than 3 x 10(-7)% was achieved. Copper-PTSM was successfully labelled with the no-carrier-added 62Cu eluent directly from the generator with 94% radiochemical yield.