Determination of 161Tb half-life by three measurement methods

M Teresa Durán; Frédéric Juget; Youcef Nedjadi; François Bochud; Pascal V Grundler; Nadezda Gracheva; Cristina Müller; Zeynep Talip; Nicholas P van der Meulen; Claude Bailat

doi:10.1016/j.apradiso.2020.109085

Determination of ¹⁶¹Tb half-life by three measurement methods

Appl Radiat Isot. 2020 May:159:109085. doi: 10.1016/j.apradiso.2020.109085. Epub 2020 Feb 19.

Affiliations

¹ Institute of Radiation Physics, Lausanne, Switzerland. Electronic address: teresa.duran@chuv.ch.
² Institute of Radiation Physics, Lausanne, Switzerland.
³ Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Switzerland.
⁴ Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Switzerland; Laboratory of Radiochemistry, Paul Scherrer Institute, Villigen-PSI, Switzerland.

PMID: 32250758
DOI: 10.1016/j.apradiso.2020.109085

Abstract

The radiolanthanide ¹⁶¹Tb is being studied as an alternative to ¹⁷⁷Lu for targeted radionuclide tumor therapy. Both β^--particle emitters show similar chemical behavior and decay characteristics, but ¹⁶¹Tb delivers additional conversion and Auger electron emissions that may enhance the therapeutic efficacy. In this study, the half-life of ¹⁶¹Tb was determined by a combination of three independent measurement systems: reference ionization chamber (CIR, chambre d'ionization de référence), portable ionization chamber (TCIR) and a CeBr₃ γ-emission detector with digital electronics. The half-life determined for ¹⁶¹Tb is 6.953(2) days, showing a significant improvement in the uncertainty, which is one order of magnitude lower, with a deviation of 0.91% from the last nuclear data reference value. The previous large uncertainty of the half-life had a direct impact on activity measurements. Now it is no more an obstacle to a primary standardization.

Keywords: (161)Tb; Digital electronics; Half-life; Ionization chamber; Standardization.