Activity measurements of the radionuclide 99mTc for the NMIJ, Japan, in the ongoing comparison BIPM.RI(II)-K4.Tc-99m

In September 2011, the third comparison of activity measurements of 99mTc using the Transfer Instrument of the International Reference System (SIRTI) took place at the National Metrology Institute of Japan (NMIJ). An ampoule containing about 38 kBq of 99mTc traceable to the NMIJ primary standard was measured in the SIRTI for more than three half-lives. No 99Mo impurity had been identified in the solution. The comparison, identifier BIPM.RI(II)-K4.Tc-99m, is linked to the BIPM.RI(II)-K1.Tc-99m comparison and the degrees of equivalence with the key comparison reference value and between the present NMIJ result, the other K4 participants and the six participants in the K1 comparison have been evaluated. World-wide consistency of activity measurements of 99mTc is demonstrated. (authors)