CIPM MRA COMPARISON REPORTS

The APMP/TCRI Dosimetry Working Group initiated the APMP.RI(I)-K7 key comparison of the air kerma standards for mammography X-rays, measurements took place between 2020 and 2023. In total, five institutes took part in the comparison. Two ionization chambers were used as transfer standards circulated among the participants. The results showed that the maximum difference between the participants and the Bureau International des Poids et Mesures (BIPM), evaluated using the comparison data of the linking laboratories of the National Institute of Metrology of China (NIM) and the National Metrology Institute of Japan (NMIJ), was less than 14.8 parts in 10³ within the expanded uncertainty. This comparison supports the equivalence of the calibration capabilities of the participating laboratories.