Preparation of Holmium-166 Labelled Macroaggregates for radionuclide synovectomy.

BACKGROUND: Radionuclide synovectomy (radiation synovectomy) is an alternative method that cures patients with rheumatoid arthritis diseases without surgery. During treatment, the suspension of the 166 Ho-macroaggregates radioactive particles ( 166 Ho-MA) is administrated via intra-articular injection into the target joint to destroy the inflamed synovium. MATERIAL AND METHODS: The isotope of 166 Ho (E β max = 1.84 MeV, T ½ = 26.8 hr) was prepared by the 165 Ho(n, γ) 166 Ho reaction in the LWR-15 nuclear reactor (8–10 MW) using approximate neutron flux 10 14 cm-2s-1. RESULTS: The particles of Ho-Macroaggregates with suitable dimension 1–20 μm and the mean diameter of 8.5 μm were prepared. High in-vitro stability was obtained after incubation of neutron-irradiated Ho-Macroaggregates in saline solution (0.9% NaCl). The in-vivo stability on rats was verified as well. CONCLUSIONS: High in-vivo and in-vitro stability as well as supporting gamma radiation of Ho-166 make the Macroaggregates a prospective agent for radionuclide synovectomy. The method of preparation is relatively easy and allows for the production of particles of a suitable dimension with a sufficient amount of radioactivity of Ho-166 for the treatment of the rheumatoid arthritis.