Ensuring the traceability of measurements of radiopharmaceutical activity in Brazil

The National Laboratory for Metrology of Ionizing Radiation (LNMRI) as Institution responsible for the maintenance, dissemination and traceability of the measurement of the standards of Ionizing Radiation in Brazil has since 1997 promoted a quality assurance program for the measurement of radionuclide activity with Nuclear Medical Services (NMS) for traceability of their measurements to national and international standards. In this work, results of the consistency and performance of comparisons of LNMRI, Radiopharmaceutical Producing Centers (RPC) and Radionuclide Metrology Laboratories (RML) with NMS are presented. In order to meet the requirements of ANVISA's RDC-No 63/2009, that the activities of the radiopharmaceuticals distributed by the RPC, Centralized Radiopharmacies and Hospital Radiopharmacies must be traceable to the National Authority, it has been demonstrated, contrary to Art. 35, paragraph 2, that there is no impossibility quoted in that to contact the LNMRI. For this, comparisons of measurements with CNEN's RPC (CDTN, CRCN-NE, IEN and IPEN) were performed. All of them produced and measured ¹⁸F sources, with 1.8289h, half-life, and they sent to the LNMRI who measured them at the same day. The results were evaluated according to ISO/IEC 17043 and CNEN 3.05 standard. Three of the four RPC had all the results in agreement. The RPC with non-conforming results repeated the ¹⁸F measurements, and corrected the errors. A comparison was also made between LNMRI and SMN to measure the activity of radiopharmaceuticals containing ¹³¹I and ⁹⁰Y, most used in therapy in Latin America (ARCAL), IPEN prepared and distributed sources of this comparison for several Brazilian states. The results were consistent for 91% of ¹³¹I and 33% of ⁹⁰Y. The relationship between LNMRI (reference), IPEN (preparation, measurement and sending of samples) and SMN (participants) showed that it is possible to obtain results quickly and accurately when evaluating traceability in our continental country. The ¹³¹I and ⁹⁰Y were calibrated by the CIEMAT-NIST method, being ⁹⁰Y was calibrated for the first time in LNMRI. The results of reference measurements of LNMRI (for Brazilian NMS) in relation to the National Atomic Energy Commission of Argentina-CNEA (southern countries of LA) and the Isotopes Center of Cuba-CENTIS (northern countries of LA) were equivalent to 0.9% for ¹³¹I. For the ⁹⁰Y the three references were equivalent in 12.7%; and between LNMRI and CENTIS only, the equivalence was 2.4%. Finally, it was proposed: 1) dynamic protocol of quality control of activimeters, calculation of activity and uncertainties, to provide traceability to activity measurements in Nuclear Medicine network in Brazil; 2) updating course to harmonize these measurement practices. (author)