Dose calibrator manufacturer-dependent bias in assays of ¹²³I.
Calibration factors for commercial ionization chambers (i.e. dose calibrators) were determined for a solution of (123)I; the activity was based on the 1976 NBS standard. A link between the NIST standard and the International Reference System (SIR) was established. The two major U.S. dose calibrator manufacturers recommend oppositely biased calibration factors, giving a spread of 11.3% in measured activities. With modern quantitative imaging techniques capable of ≤10% accuracy, this bias for a SPECT nuclide is highly significant.
Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8462, Gaithersburg, MD 20899-8462, USA. Electronic address: denis.bergeron@nist.gov.
Denis E
DE
Bergeron
Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8462, Gaithersburg, MD 20899-8462, USA.
Jeffrey T
JT
Cessna
Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8462, Gaithersburg, MD 20899-8462, USA.
Daniel B
DB
Golas
Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8462, Gaithersburg, MD 20899-8462, USA.
Rheannan K
RK
Young
Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8462, Gaithersburg, MD 20899-8462, USA.
Brian E
BE
Zimmerman
Dose calibrator; I-123; Ionization chamber; Quantitative imaging; Secondary standard