Chromosome damage after intra-articular injections of radioactive yttrium. Effect of immobilization on the biological dose.

Favourable results have been obtained in the treatment of persistent joint effusion with radioactive agents (e.g. Ansell, Crook, Mallard, and Bywaters, 1963; Virkkunen, Krusius, and Heiskanen, 1967; Delbarre, Cayla, Roucayrol, Menkes, Aignan, and Ingrand, 1970; Oka, Rekonen, Ruotsi, and Seppalii, 1971). The future of this kind of radiotherapy is largely dependent on whether the ionizing radiation has side-effects. Chromosome damage in patients who had received intra-articular injections of radioactive gold ('98Au) has recently been reported (Stevenson, Bedford, Hill, and Hill, 1971a). At present radioactive yttrium (90Y) is displacing 19"Au as an agent for radiation synovectomy. In radiophysical characteristics 90Y is clearly superior to '98Au. It emits only beta-rays with a high maximum energy (2.25 MeV) and a maximum range in the tissue of 11 mm. (average 4 mm.). The corresponding figures for 198Au indicate that it is much less effective. The two isotopes have the same half-life, 2-7 days.