The APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K3 key comparison of measurement of air kerma for medium-energy x-rays (100 kV to 250 kV) between 2000 and 2003. In total, 11 institutes took part in the comparison, among which 8 were APMP member laboratories. Two commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. All the participants established the 100 kV, 135 kV, 180 kV and 250 kV x-ray beam qualities equivalent to those of the BIPM. T he results showed that the maximum difference between the participants and the BIPM in the medium-energy x-ray range, evaluated using the comparison data of the linking laboratories ARPANSA and PTB, is less than 1.4 %. The degrees of equivalence between the participants are presented and this comparison confirms the calibration capabilities of the participating laboratories.

The APMP.RI(I)-K1 key comparison of the measurement standards of air kerma for 60Co gamma-rays was undertaken by the APMP/TCRI Dosimetry Working Group between 2004 and 2006, coordinated by the Korean Research Institute of Standards and Science (KRISS). In total, 10 institutes took part in the comparison, among which 7 were APMP member laboratories. Three Farmer-type commercial cavity chambers were used as transfer chambers and circulated among the participants. All the participants carried out their measurements according to the guidelines for the comparison established by the KRISS with the cooperation of the ARPANSA. For each transfer chamber, an NMI calibration coefficient was obtained and a ratio derived by dividing by the average result from the linking laboratories, ARPANSA and NMIJ. The APMP comparison reference value for each chamber was calculated as the mean of the NMI-determined calibration coefficients divided by the average result from the linking laboratories. The results showed that the maximum difference between the APMP linked ratio of a participating NMI and the APMP reference value was 1.76%.The measured ratios of the calibration coefficient RNMI, BIPM between the participating NMI and the BIPM via the link laboratories for the transfer chambers were obtained. The maximum expanded uncertainty of RNMI, BIPM for any participating laboratory was 2.0%.The degree of equivalence of each participating laboratory with respect to the key comparison reference value was also evaluated. The expanded uncertainty of the difference between the results ranged from 0.5% to 1.2%. The pair-wise degree of equivalence between each pair of laboratories was also obtained and the largest difference of the expanded uncertainty of the difference for any pair-wise degree of equivalence was within the expanded uncertainty of the measurement for the pair of laboratories.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The results of a regional supplementary comparison of air kerma standards from eight standards laboratories are presented. The three transfer ionisation chambers (two model Exradin A4 chambers and one Exradin A5 chamber manufactured by Standard Imaging, Inc, Middleton, MI, USA) were measured at each laboratory over the period 2013 to 2016. Air kerma calibration coefficients for the transfer instruments were compared for the ISO 4037 narrow- and wide-spectrum series of x-ray beams, in the range from 30 kV to 300 kV. Results from the five primary standard and three secondary standard laboratories were obtained. For each radiation quality, the results were expressed as the ratio of the laboratory to the comparison reference value, which was the average of three laboratories selected for this purpose before the comparison began. The A5 transfer standard was also compared for air kerma at protection-level 137Cs gamma rays. Laboratories reported their conversion coefficients for ambient dose equivalent, H*(10), and so the comparison also served as an indirect test of this quantity. Overall, the laboratories were in general agreement within the expanded uncertainties claimed by the laboratories. The comparison is designated APMP.RI(I)-S3 under the international arrangements for comparisons conducted to support the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).