A bilateral comparison between LNHB and PTB to determine the activity concentration of the same 125I solution

Karsten Kossert; Christophe Bobin; Vanessa Chisté; Carole Fréchou; Valérie Lourenço; Ole Nähle; Benoit Sabot; Cheick Thiam

doi:10.1016/j.apradiso.2023.110947

A bilateral comparison between LNHB and PTB to determine the activity concentration of the same ¹²⁵I solution

Appl Radiat Isot. 2023 Oct:200:110947. doi: 10.1016/j.apradiso.2023.110947. Epub 2023 Jul 16.

Authors

Karsten Kossert¹, Christophe Bobin², Vanessa Chisté², Carole Fréchou², Valérie Lourenço², Ole Nähle³, Benoit Sabot², Cheick Thiam²

Affiliations

¹ Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany. Electronic address: karsten.kossert@ptb.de.
² Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), F-91120, Palaiseau, France.
³ Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.

PMID: 37467537
DOI: 10.1016/j.apradiso.2023.110947

Abstract

A bilateral comparison to determine the activity concentration of the same ¹²⁵I solution was organized. As electron-capture radionuclide with a rather high atomic number, ¹²⁵I must be regarded as difficult to measure. The situation is partly exacerbated by the fact that some established standardization methods, like photon-photon coincidence counting, can no longer be applied due to the unavailability of appropriate equipment and expertise. One aim of this work is to compare modern liquid scintillation counting methods for the standardization of ¹²⁵I. Both participating metrology institutes have used their custom-built triple-to-double-coincidence ratio (TDCR) counters and the determined activity concentrations are in excellent agreement even though the ways to analyze the data and to compute counting efficiencies were widely independent. The results also agree with the outcome of 4π-γ counting that was carried out at LNHB. In both laboratories, the measurements were complemented by measurements with several secondary standardization methods which even allow to establish a link to the CCRI(II)-K2.I-125(2) comparison started in 2004. A good agreement between the TDCR results and the key comparison reference value of the 2004/2005 comparison was obtained.

Keywords: (125)I; 4π-γ counting; Activity standardization; International comparison; Liquid scintillation counting; TDCR.