The development of dysprosium-165 hydroxide macroaggregates for radiation synovectomy

Abstract

The development of a dysprosium-165 product Dy-HMA which is suitable for the radiation synovectomy of arthritic joints is described. Dysprosium-165 is a short-lived (t 1 /2 = 139 min) β-emitter produced by the neutron irradiation of natural dysprosium. Dy-HMA is a suspension of macroaggregated hydroxide particles in saline with the majority of particles in the 3-5 um range. Studies in rabbits have demonstrated minimal leakage following the intra-articular injection of a knee joint. At 24 hours the accumulation in the liver is about 0.003% of the injected dose and there is considerably less in other organs and tissue. The use of Dy-HMA has considerable advantages over the presently used yttrium-90 products. The undesired leakage to and subsequent irradiation of other organs is considerably reduced. The period of hospitalisation is reduced from four days to one and the production of 165 Dy in Australia will overcome the difficulties of supply 90Y from overseas.