Background ⁹⁰Y is one of the radioisotopes used extensively for therapy due to its favourable nuclear characteristics. Particles and colloids incorporating ⁹⁰Y are being used for radiation synovectomy, especially in European countries.

Methods In our present work, ⁹⁰Y phosphate particles were prepared and evaluated for use in radiation synovectomy. The radioactive particles were prepared by reacting carrier added ⁹⁰YCl₃ with phosphoric acid.

Results The radiolabelling yield obtained was >95%. The particles were found to be stable in saline for up to 7 days of study at 37^oC. Particle size analysis of inactive yttrium phosphate showed that most of the particles were in the size range of 2–20 μm. Biodistribution studies carried out by intra-articular injection of the particles into the knee joints of rats showed that B 99% of the particles were retained in the joints with negligible radioactivity in the major organs even at 48h post-injection. Scintigraphic studies in rabbit showed that >99% of the radioactive particles were retained in the knee joint even at 96h post injection. No significant radioactivity above background was detected in the blood.

Conclusion The promising results warrant further studies on ⁹⁰Y phosphate particles for use in radiation synovectomy.