One hundred percent tumor induction in mouse skin after repeated beta irradiation in a limited dose range.

Repeated beta irradiation of the backs of mice three times a week with radiation doses of 250 to 1180 cGy per exposure induced 100% incidence of tumors. The incidence of skin tumors appeared to be determined by the total number of repeated exposures in this dose range. An abrupt delay in tumor emergence was observed when the radiation dose was reduced from 250 to 150 cGy per exposure, indicating the existence of a critical threshold. Mouse skin resembles human skin rather than rat skin in its response to radiation.