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Results of an International Comparison of Activity Measurements of 68Ge



Jeffrey T. Cessna, Ryan P. Fitzgerald, Brian E. Zimmerman, Lizbeth Laureano-Perez, Denis E. Bergeron


An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 1200 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)β-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11) kBq·g-1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6 mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence.
Applied Radiation and Isotopes


International comparison, Equivalence, Germanium-68, Gallium-68


Cessna, J. , Fitzgerald, R. , Zimmerman, B. , Laureano-Perez, L. and Bergeron, D. (2017), Results of an International Comparison of Activity Measurements of 68Ge, Applied Radiation and Isotopes, [online], (Accessed April 17, 2024)
Created November 7, 2017, Updated November 10, 2018