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Published on: June 6, 2018
Primary standardization of 224Ra activity by liquid scintillation counting
Elisa Napoli1, Jeffrey T Cessna2, Ryan Fitzgerald2
1Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899-8462, USA; Oncoinvent AS, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
None:
A standard for activity of 224Ra in secular equilibrium with its progeny has been developed, based on triple-to-double coincidence ratio (TDCR) liquid scintillation (LS) counting. The standard was confirmed by efficiency tracing and 4παβ(LS)-γ(NaI(Tl)) anticoincidence counting, as well as by 4πγ ionization chamber and NaI(Tl) measurements. Secondary standard ionization chambers were calibrated with an expanded uncertainty of 0.62% (k = 2). Calibration settings were also determined for a 5 mL flame-sealed ampoule on several commercial reentrant ionization chambers (dose calibrators).
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