Practical Aspects of ¹⁶¹Tb Production

Area of Science:

• Nuclear chemistry and radiopharmaceutical production
• Theranostic radionuclide development

Background:

• Terbium-161 (Tb-161) is a promising theranostic radionuclide with favorable decay characteristics for targeted therapy.
• Its chemical similarity to Lutetium-177 (Lu-177) positions it as a potential alternative for clinical applications.
• Tb-161 emits conversion and Auger electrons, enhancing localized therapeutic effects.

Purpose of the Study:

• To describe the preparation of no-carrier-added Terbium-161 (Tb-161) suitable for preclinical and early clinical studies.
• To provide practical insights and address challenges in Tb-161 production and purification.
• To assess the quality and specific activity of the produced Tb-161 for radiopharmaceutical development.

Main Methods:

• Neutron irradiation of highly enriched Gadolinium-160 (Gd-160) targets.
• Separation and purification of Tb-161 using cation exchange chromatography (Dowex 50 W × 8).
• Characterization using gamma-ray spectrometry and ICP-MS for purity and specific activity determination; DOTA labeling assay performed.

Main Results:

• Production of 1.3-23.7 GBq of Tb-161 from enriched Gd-160 targets.
• High separation yields (85-99%) and activities (9.9-22.1 GBq) achieved.
• Highest specific activity of 4.1 GBq/μg (of Tb) obtained; successful DOTA radiolabeling demonstrated.

Conclusions:

• Reproducible laboratory-scale production of no-carrier-added Tb-161 is feasible using enriched Gd-160 targets and cation exchange chromatography.
• The method yields significant activity levels suitable for preclinical and clinical investigations.
• Practical aspects of lanthanoid separation are highlighted, offering valuable insights for radiochemists.