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Entre los objetivos en los tratamientos con esferas marcadas con ytrio-90 figura demostrar que se consigue la dosis tumoricida y que se evitan dosis hepatotóxicas, así como que no existe deposición extrahepática. Utilizamos diferentes cantidades de ytrio y un maniquí NEMA NU2-2007 para comprobar si el tomógrafo mantiene una respuesta que permita hacer cálculos dosimétricos reales. El tomógrafo Gemini responde de manera lineal en un rango amplio de actividades con una R2 = 0,9983. La capacidad de detección del equipo PET nos permite realizar estudios de cuerpo estándar con finalidad dosimétrica con tiempos de 5 min por BED, que además hacen posible verificar la ausencia de deposición extrahepática de cantidades significativas de esferas de ytrio-90. Among the objectives in treatments with yttrium-90 spheres is to demonstrate that the tumoricidal dose is achieved and that hepatotoxic doses are avoided, as well as that there is no extrahepatic deposition. We use different amounts of yttrium-90 resin micro-spheres and a NEMA NU2-2007 phantom to check if the scanner maintains a response that allows real dosimetric calculations. The Gemini tomograph responds linearly in a wide range of activities with R2 = 0.9983. The detection capacity of the PET equipment allows us to carry out standard body studies with dosimetric purposes with times of five minutes per BED. It also make possible to verify the absence of extrahepatic deposition of significant amounts of yttrium 90 spheres. [ABSTRACT FROM AUTHOR]

Abstract: 90Y microspheres are important therapeutic radiopharmaceuticals used in the treatment of liver cancer through a process known as selective internal radiation therapy. SIR-spheres® is a radiopharmaceutical product that is comprised of 90Y microspheres suspended in sterile, pyrogen-free water for injection into patients. It is necessary to establish for the SIR-spheres® production the capability of accurately measuring the activity of this product to a traceable national measurement standard. An activity standard for SIR-spheres® was developed from a standard for 90Y solution, employing a highly quantifiable chemical digestion process. Calibration factors for the manufacturer''s ionisation chambers were determined for 1 and 5ml of the SIR-spheres® product placed in Wheaton vials, for both 34% and 44% of 90Y microsphere concentration. [Copyright &y& Elsevier]