Standardization of 89Sr at the National Office of Measures

Strontium-89 is an important radiotherapy nuclide in bone palliation. The standardization of 89Sr has been performed at the National Office of Measures (OMH) within the frame of the BIPM CCRI(II)-K2.Sr-89 key comparison. The activity concentration of the 89Sr solution was measured by two different methods. The conventional 4πβ counting technique was used with two proportional counting measurement systems. The 4πβ–γ-coincidence efficiency tracing method was used with a 4πβ–γ-coincidence measurement system using 24Na as the tracer radionuclide. The β efficiencies of each of these counting techniques were nearly 100%. The combined uncertainties of the activity concentration determined by these absolute methods are 0.3%. The general agreement of results between the two methods was 0.5%. The measurement equipment, evaluation methods and results of activity concentration measurements with their uncertainty budgets are reported.