Preparation and in vitro stability of (n,γ) yttrium-90 hydroxyapatite

Yttrium-90, produced by irradiating Y2O3 (15 mg) in the Pakistan Research Reactor (PARR-I) at a flux of ∼1.5×1014 neutrons/cm2/s, was used to prepare yttrium-90 hydroxyapatite particles for radiosynovectomy applications. The irradiated material was dissolved in concentrated hydrochloric acid, evaporated and taken up in distilled water. The 120 h irradiation resulted in the production of ∼12 GBq (324 mCi) of 90Y at the end of irradiation (EOI) and the corresponding specific activity was ∼1017 GBq/g of yttrium. Hydroxyapatite (HA) particles were synthesized by an already reported method. Labeling of HA particles with 90Y was studied without a transchelating agent. Labeling yields of ∼100% could be achieved with 40 mg of HA and 0.4 mg of 90Y. In vitro studies showed <2% loss of 90Y activity in normal saline and 1% human serum albumin solution over a period of 8 days. The high labeling yield, good stability and ease of preparation of the 90Y-HA particles indicate that these particles may find wide application in radiation synovectomy.