The Osteosarcomogenic Effectiveness of the Short-Lived 224 Ra Compared with That of the Long-Lived 226 Ra in Mice

Abstract

MijLLER, W. A., AND Luz, A. The Osteosarcomogenic Effectiveness of the Short-Lived 224Ra Compared with That of the Long-Lived 226Ra in Mice. Radiat. Res. 70, 444-448 (1977). 224Ra was applied with one single injection or with repeated injections (twice weekly over various time periods, up to 36 weeks). In general the bone tumor incidence increased with dose but with the restriction that the maximum instantaneous dose rate be not too high. The 1080-rad total skeletal dose thus resulted in a bone tumor incidence between 15 and 90% depending on the length of the injection spans. These results were compared with the effect of singly injected long-lived 5Ra, using data by M. Finkel et al. (1). It was observed that the specific bone tumor production by EsRa, expressed as incidence per unit of total accumulated skeletal dose, was steadily diminished with an increase of the dose. As a consequence, we found that mice after a single injection of the long-lived 22Ra within the tested dose range had in general a considerably lower bone tumor incidence than those mice having received comparable skeletal doses through repeated injections of the short-lived H4Ra over a longer period.