Comparison of radioactivity measurements with radionuclide calibrators in the Republic of Korea

Recognizing the importance of comparisons of radionuclide calibrators in nuclear medicine and the need to provide access to activity standards that are traceable to the international measurement system, the Korea Food & Drug Administration (KFDA) as a national secondary standard dosimetry laboratory (SSDL), started a comparison program in 2002. The first two comparisons were conducted with 131I (71 participants) and 99mTc (72 participants). The results indicated that only 61% of reported activities for 131I and 65% for 99mTc were within ±5% of the correct value. These numbers increased to 84% for 131I and 83% for 99mTc when a ±10% limit was applied. Follow-up action on those calibrators with results outside the ±10% limits only produced a small improvement. There was also a marked difference in performance between the various calibrator types used. The results have shown that such comparisons are necessary to improve the quality of the measurements and to identify those radionuclide calibrators that are not functioning correctly.