The Brazilian panorama for the calibration of Y-90 microspheres

The combination therapy approaches are gaining popularity, particularly the radiopharmaceutical therapy with external radiotherapy, immunotherapy or both. Radioembolization using Yttrium-90 Microspheres, SIR-Spheres and TheraSphere, has been used clinically in the treatment of locally advanced and unresectable Hepatic Carcinomas. According to the literature, the standardization of microspheres is not yet well established. In view of the practice of 90Y in therapies in Brazil, it is essential to develop solid standards for its measurement, in order to verify the absorbed radiation dose and its administration to the patient. This paper proposes a study of the existing standardization infrastructure for 90Y microspheres through a literature review and analysis of the measuring instruments available at the National Laboratory for Ionizing Radiation Metrology, a general analysis was made of the spectrometry and calibration methods available in Brazil, specifically at LNMRI, evaluating those suitable for use in the standardization of Yttrium microspheres. The results showed that in the period between 2000 and 2024 90Y was widely cited in treatment by radioembolization with microspheres, qualitative and quantitative evaluation of the activity quantity in PET/CT scans and its metrological characterization involving proficiency tests, study of impurities, standardization by primary and secondary methods