Since 1981, three national metrology institutes (NMI) and two other laboratories have submitted nine samples of known activity of ¹²³I to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures. The activities ranged from about 1.8 MBq to 84 MBq. The degrees of equivalence between each equivalent activity measured in the SIR and the key comparison reference value (KCRV) have been calculated and the results are given in the form of a matrix for three NMIs and an international laboratory. A graphical presentation is also given.

The results of a EUROMET comparison, identifier EUROMET.RI(II)-K2.I-123 held in 1983 that have been approved for provisional equivalence for this radionuclide, have been linked to the SIR results. This has enabled two other NMIs to have their results in the key comparison database.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), comparison identifier BIPM.RI(II)-K1.I-123, according to the provisions of the Mutual Recognition Arrangement (MRA).