Preparation and studies with 90Y-labelled particles for use in radiation synovectomy

90Y-FHMA (Ferric hydroxide macroaggregates) and 90Y-HA (hydroxyapatite) were prepared in >95% yield using 90Y from an in-house 90Sr–90Y generator. Most of the particles ranged from 5 to 20 μm in diameter and retained radiochemical purity >95% in human serum for at least 7 days at 37°C. Gamma camera imaging of normal rabbits after intraarticulation of the particles showed complete retention of activity within the knee cavity with no measurable radioactivity leaching out of the joints over a 96 hour period.