Comparison of the NIST and BIPM Standards for Air Kerma in Medium-Energy X-Rays.
A comparison has been made of the air-kerma standards for medium-energy x-rays of the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and three NIST reference-class transfer ionization chamber standards. Reference beam qualities in the range from 100 kV to 250 kV were used. The results show the standards to be in reasonable agreement within the combined standard uncertainty of the comparison of 0.37 %, although a significant trend with radiation quality is observed and the possible sources discussed.
Bureau International des Poids et Mesures, F-92312 Sèvres Cedex, France.
D T
DT
Burns
National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.
M
M
O'Brien
air kerma; free-air ionization chamber; medium-energy x-rays; primary standard; reference radiation qualities; x-ray calibration