Production and Optimization of Yttrium-90 Citrate Via Neutron Activation for Radiosynovectomy
Abstract
Purpose
Radiosynovectomy (RSV) is a minimally invasive therapeutic option for the treatment of chronic synovitis, with yttrium-90 (⁹⁰Y) being particularly suitable for large joints such as the knee. In Brazil, national production of therapeutic radiopharmaceuticals remains limited by challenges related to availability, standardization, and technological autonomy. This work aims to develop and optimize a national route for the production of yttrium-90 citrate for RSV applications at IPEN-Brazil.
Methods
The strategy comprises two parallel approaches: non-radioactive chemical synthesis and radionuclide production via neutron activation. Yttrium citrate is synthesized at room temperature using high-purity yttrium oxide and concentrated citric acid in a minimal solvent volume (approximately two drops of water), with ~20 mg of yttrium, focusing on solution stability and colloidal behavior. Colloidal particle size is evaluated by dynamic light scattering (DLS), targeting future adjustment to the RSV-appropriate range (2–10 µm). In parallel, yttrium oxide is neutron-irradiated in the IEA-R1 research reactor to produce ⁹⁰Y, with radioactive activity measured using a well-type ionization chamber (Capintec).
Results
Neutron irradiation of yttrium oxide resulted in the production of yttrium-90 with an activity of approximately 2 mCi, with demonstrated feasibility to increase this value up to 5 mCi, which is considered ideal for knee joint treatments. The chemical synthesis approach yielded an initially stable yttrium citrate solution suitable for subsequent studies, while DLS analyses indicate that precise control of colloidal particle size is still under development.
Conclusion
This work represents an original contribution within the IPEN-Brazil context by establishing, in parallel, the chemical and nuclear foundations required for national production of yttrium-90 citrate for radiosynovectomy. The combination of a stable yttrium citrate solution and satisfactory radionuclide production constitutes a key step toward future optimization of colloidal size and clinical application.