National programme for the reliability of ionizing radiation measurements based on inter-laboratory comparisons (ILCs): ILC n°2 ‘radiopharmaceutical activities’

A national Inter-Laboratory Comparisons (ILCs) programme was organized in Italy in 2022 by the Italian National Institute of Ionizing Radiation Metrology (INMRI), belonging to ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development), under the auspices of the Ministry of Enterprises and Made in Italy (Mimit ex MiSe). Within this ILCs programme, six inter-laboratory comparisons were organized, including the ILC-2 which focused on activity measurements carried out with radionuclide calibrators commonly used in the nuclear medicine departments of the participants.

The focus was on three short-lived radionuclides - ^99mTc, ¹⁸F, ¹⁷⁷Lu - commonly employed in nuclear medicine for both diagnostic and therapeutic purposes. All presented results were compared with the reference values provided by ENEA-INMRI to ensure the traceability of measurements to the national primary activity standards. The observed deviation from the reference values of the measured activity were mainly within $\pm$ 10% (100% for ¹⁸F, 91.7% for ^99mTc, 100% for ¹⁷⁷Lu). The E_n statistical estimator was used to assess the participants’ ability to estimate uncertainty in the provided activity values. The obtained values revealed that, in certain instances, the involved laboratories did not achieve the correct results for E_n (with failure rates of 22.7%, 16.7%, 12.5% for ¹⁸F, ^99mTc, ¹⁷⁷Lu, respectively), despite deviations from the reference values falling within the $\pm$ 10%. The aim of ILC-2 was to harmonize the activity measurements in the country within the field of nuclear medicine for the specific radionuclides studied and enhance the measurement capabilities of the participants.