Comparisons of air kerma and absorbed dose to water standards in Co-60 radiation beams for radiotherapy

The air kerma and absorbed dose to water standards for 60Co radiotherapy beams of 6 EURAMET NMIs were compared by circulating 2 transfer standards. The schedule for the measurements lasted from March 2013 to February 2015. The participants determined the calibration coefficients for the 2 transfer standards in both radiation quantities mentioned above. The comparison results are given in terms of air kerma and absorbed dose to water for both transfer standards as the ratio of the participants' calibration coefficients to the respective average values over all participants. Two participating NMIs, BEV and METAS, measured the transfer standards twice and three times, respectively. Hence, submeans were calculated and propagated as their respective repeated measurements are correlated. The results are also linked to the BIPM.RI(I)-K1 and BIPM.RI(I)-K4 key comparisons through the linking laboratories BEV, LNE-LNHB and VSL for the air kerma and BEV, LNE-LNHB and METAS for the absorbed dose to water standards. 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).