Separation of radioactive terbium from massive Gd targets for medical use

Methods for chemical separation of terbium from gadolinium and dysprosium have been investigated using proton activated gadolinium, as well as gadolinium–terbium mixture matrix. Terbium radioisotopes can be effectively separated from large amount (> 100 mg) gadolinium on an analytical column. In reactors inactive dysprosium also forms in the activated Gd matrix, considerably decreasing the chemical purity of the labelled radiopharmaceutical. A semi-preparative column method was therefore developed to separate terbium at the same time both from the dysprosium and the gadolinium target material.