Electrochemical oxidation of terbium towards the purification of the medical Tb-161 isotope

SCK•CEN Mentor

Geboes Bart, bgeboes@sckcen.be, +32 (0)14 33 82 08

Expert group

Radiochemistry

SCK•CEN Co-mentor

Arman Meryem , marman@sckcen.be , +32 (0)14 33 31 09

Introduction

Radionuclides are being used for diagnostic and therapeutic purposes in nuclear medicine for various applications. Among them, there is an interest in terbium (Tb) since it offers 4 clinically interesting isotopes having complementary characteristics. In particular 161Tb (t1/2 = 6.9 days, Ebeta max = 593 keV) is showing similar properties with 177Lu (t1/2 = 6.6 days, Ebeta max = 497 keV) which is today already used in radiopharmaceuticals to treat neuroendocrine tumors.

Carrier-free 161Tb can be produced via neutron irradiation of highly enriched gadolinium (160Gd) targets in the Belgian Reactor 2 (BR2) at SCK CEN. In this process, neutron capture of the 160Gd target yields the short-lived intermediate 161Gd which will form the 161Tb isotope via subsequent β-decay. Furthermore, part of the produced 161Tb will decay to the stable 161Dy. Therefore in order to be used in radiopharmaceuticals, isolation of Tb is needed from a Gd matrix containing other lanthanide impurities.

Objective

The similar chemical properties of lanthanides allow for similar radiolabeling approaches in radiopharmaceutical production. On the other hand, this characteristic inhibits the easy separation of neighboring lanthanides. Therefore, to achieve an efficient separation and isolation of 161Tb the strategy will be changing the chemical properties of Tb(III) by oxidizing it to Tb(IV) as a preparative step.

The objective of this master thesis project is to gain fundamental insight in the redox chemistry of Tb and broaden the limited knowledge on the Tb(IV) stabilization. Due to the high chemical stability of Tb(III) and to avoid contamination via strong oxidation agents, electrochemical methods (chronoamperometry, cyclic voltammetry) will be applied to perform the oxidation. To further analyze the oxidation efficiency and stability due to a variety of parameters (solvent, supporting electrolyte, pH…), analytical methods such as UV-Vis spectroscopy and ICP-MS will be used.

The minimum diploma level of the candidate needs to be

Academic bachelor

The candidate needs to have a background in

Chemistry