Terbium is a unique element, as it provides a quadruplet of radionuclides suited for diagnostics and therapy in nuclear medicine. Much success has been gained from the PSI-ISOLDE collaboration, with the collection and purification of 149Tb (α-emitter, T1/2 = 4.1 h), used for preclinical therapy studies and PET imaging, and 152Tb (β+-emitter, T1/2 = 17.5 h), for preclinical and clinical PET imaging, respectively. Mass-separated beams of 149Tb and 152Tb, respectively, were implanted at ISOLDE-CERN into Zn-coated Au foils. With 1.5 hours of collection and 2 hours decay of co-implanted activities, up to 200 MBq 149Tb could be transported to PSI. Collections of 152Tb lasted 4 to 6 hours and up to 600 MBq 152Tb could be shipped to PSI. Both the means of collection at ISOLDE/CERN, as well as the chemical separation have been updated over the years, with the most significant upgrades taking place in 2017. At PSI, the chemical separation system was performed using a new set up and manipulators in a hot cell. The foil containing the Tb nuclide was extracted from the Zn foils by dissolving them in HNO3/NH4NO3. The dissolved nuclides were loaded on to a macroporous strongly acidic cation exchange resin and Tb nuclide eluted using dilute α-hydroxyisobutyric acid (α-HIBA). As an addition, the product eluent was passed through a second resin column, to ensure formulation of the product in chloride form. 152Tb was directly employed for radiolabeling of PSMA-617. PET/CT scans were performed with PC-3 PIP (PSMA-positive) tumor-bearing mice at different time points after injection of 152Tb-PSMA-617. The successful experimental runs with the updated system have prepared the collaboration well for proposed extended preclinical imaging and therapy experiments in future.

Use of 149Tb and 152Tb in preclinical and clinical investigations: Its mass separation and subsequent application for imaging and therapy

255th National Meeting (2018)

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