Model for the occurrence of bone tumors in beagles

A three-stage model for the induction of bone tumors in beagles from single injections of 239Pu is presented. The model involves branching with one or two initiation steps controlled by radiation. It was applied to six groups of animals with graded injection levels between 0.38 and 33.6 kBq/kg bodymass, assuming an endosteal dose rate constant in time and proportional to the injected activity. The density of osteosarcoma survival times is Weibull with shape factor three and the scale factor being a function of the injected activity. The fraction of animals with bone tumors can be predicted using the survivor function of the controls, but some systematic deviations occur between calculations and observed fractions in an intermediate dosage range. It is shown that for low levels of 239Pu the fraction of animals with tumors is proportional to the injected amount of plutonium.