title: (Mis)use of (133)Ba as a calibration surrogate for (131)I in clinical activity calibrators.
abstract: Using NIST-calibrated solutions of (131)Ba and (131)I in the 5mL NIST ampoule geometry, measurements were made in three NIST-maintained Capintec activity calibrators and the NIST Vinten 671 ionization chamber to evaluate the suitability of using (133)Ba as a calibration surrogate for (131)I. For the Capintec calibrators, the (133)Ba response was a factor of about 300% higher than that of the same amount of (131)I. For the Vinten 671, the Ba-133 response was about 7% higher than that of (131)I. These results demonstrate that (133)Ba is a poor surrogate for (131)I. New calibration factors for these radionuclides in the ampoule geometry for the Vinten 671 and Capintec activity calibrators were also determined.
authors.affiliation: Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8462, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Zimmerman
authors.affiliation: Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-8462, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Bergeron
mesh_terms: D001465:Barium Radioisotopes / Q000032:analysis* / Q000592:standards*; D002138:Calibration / Q000592:standards*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007457:Iodine Radioisotopes / Q000032:analysis* / Q000592:standards*; D000072232:Radiation Dosimeters / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States
chemical_list: D001465:Barium Radioisotopes; D007457:Iodine Radioisotopes
keywords: Activity calibrators; Barium-133; Iodine-131; Ionization chambers