radiosynoviorthesis; radionuclide synovectomy; holmium-166; 166Ho-boro-macroaggregates; therapeutic effects; chronic synovitis

166Ho is a beta-emitter with a mean penetration in the soft tissue of 2.2 mm and gamma-photons 81keV and 1380keV. In this paper, we present our experiences with preparation of 166Ho-macroaggregates (166Ho-MA) for radiosynoviorhesis. Ho-MA were prepared by reacting the aqueous solution of holmium nitrate pentahydrate with sodium borohydride solution in 0.2 M NaOH. After centrifugation, washing, and drying at 105°C, final fineness of 1-15 micrometers was attained using a homogenizer working at 70,000 rpm. Neutron activation was carried out in screwed titanium ampules in a nuclear reactor at the neutron flux 10E12-10E14 neutrons.cm-24.s-1. The irradiated samples were allowed to cool 24 hours before further manipulation. 166Ho-MA were clinically tested on 20 patients suffering from gonarthrosis, rheumatoid arthritis, psoriatic arthritis, and gout arthropathy. 166Ho-MA are currently produced under GMP and production facility allows producing radioactivity for 6 patients within one production run.