Comparison of air kerma standards for medium-energy x radiation between the MKEH and the IAEA

A comparison of the air kerma standards for medium-energy x radiation was performed between the MKEH and the IAEA. Two reference class ionization chambers of the IAEA, traceable to the PTB with volumes 1000 cm(3) and 100 cm(3), and the ISO 4037 N-40, N-60, N-120 and N-300 standard beam qualities were selected for the comparison. The calibration coefficients, N-K, were determined for both chambers at the MKEH in August 2011 and before and after this at the IAEA Dosimetry Laboratory. The comparison ratio of the calibration coefficients normalized to the previous comparison results of the PTB and MKEH primary air kerma standards were in the range from 0.989 to 0.994 for the beam qualities used. The relative expanded ( k = 2) uncertainty for each of these ratios is around 2 %.