Radiation Dose-Time Relations for Induction of Bone Tumors in the Dog and Skin Tumors in the Rat

There are two mutually exclusive routes of tumor induction by radiation both in rat skin from brief doses of external β-radiation and in dog bone from ²³⁹ Pu,²²⁶ Ra,²²⁸ Ra , or228 Th injected at age 500 days. In the one process oncogenesis occurs directly on attainment of high radiation dose. In the other process oncogenesis follows a long latent period which is initiated by lower dose. Subsequent development time is the same in both cases. With protracted dosage the latent period is initiated at relatively low dose, but if exposure is continued the high-dose process will supersede the low if the high-dose threshold is exceeded during the latent period. Otherwise the low-dose process will govern. For those radioelements in the dog yielding relatively constant dose rates the data are represented fairly closely by the equations S-T=K/d or S-T=0.2K/d+1200 in which S is survival time in days, K is...