Traceability and quality assurance in measurements of radionuclides used in nuclear medicine

The Laboratorio Nacional de Metrologia da Radiacoes Ionizantes (LNMRI), accredited by Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (INMETRO), is the national institute responsible by the maintenance, dissemination and traceability of the radioactivity standards and measurements in the whole country. In this sense, radionuclide measurements carried out in Brazilian hospitals for medical application of diagnose and therapy must be traceable to the standards and measurement systems set up LNMRI. In this work is presented a quality assurance program for the performance of such measurements made in the hospitals with instruments named radionuclide calibrator or activity meter. The performance is evaluated in the intercomparison runs by means of comparatives measures between hospitals and LNMRI, under the statistic point of view and the compliment of regulatory authorities norms. Performance of activity meters for 131I, 99mTc and 123 I were evaluated. These radionuclides have been standardized by absolute methods and the results adopted as the reference value for the intercomparisons and also to establish the national reference system based on a 4 π γ ionization chamber. Some considerations on the diagnostic reference level in nuclear medicine were evaluated by facing the activities administered in the Brazilian hospitals in relation to the levels recommended by international organizations such as International Atomic Energy Agency (IAEA). (author)