Activity standard and calibrations for 227Th with ingrowing progeny

Denis E Bergeron; Jeffrey T Cessna; Brittany A Broder; Leticia Pibida; Ryan P Fitzgerald; Morgan DiGiorgio; Elisa Napoli; Brian E Zimmerman

doi:10.1016/j.apradiso.2024.111326

Activity standard and calibrations for ²²⁷Th with ingrowing progeny

Appl Radiat Isot. 2024 Jul:209:111326. doi: 10.1016/j.apradiso.2024.111326. Epub 2024 Apr 20.

Authors

Denis E Bergeron¹, Jeffrey T Cessna², Brittany A Broder², Leticia Pibida², Ryan P Fitzgerald², Morgan DiGiorgio², Elisa Napoli³, Brian E Zimmerman²

Affiliations

¹ Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. Electronic address: denis.bergeron@nist.gov.
² Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
³ Bayer Pharmaceuticals, Oslo, Norway.

PMID: 38701595
DOI: 10.1016/j.apradiso.2024.111326

Abstract

Thorium-227 was separated from its progeny and standardized for activity by the triple-to-double coincidence ratio (TDCR) method of liquid scintillation counting. Confirmatory liquid scintillation-based measurements were made using efficiency tracing with ³H and live-timed anticoincidence counting (LTAC). The separation time and the efficiency of the separation were confirmed by gamma-ray spectrometry. Calibrations for reentrant pressurized ionization chambers, including commercial radionuclide calibrators, and a well-type NaI(Tl) detector are discussed.

Keywords: Administered activity; Decay chain; Decay data; Dose calibrator; Gamma counter; Half-life; Precision medicine; Primary standard; Progeny ingrowth; Ra-223; Targeted alpha therapy; Th-227.

Published by Elsevier Ltd.