Effect of Fractionation of Radiation Dose on Callus Formation at Site of Fracture

Abstract

The effect of radiation on callus formation was studied in mice whose femora had been fractured after irradiation of the leg and thigh. The end point was the CID50 or dose which produced a specified inhibition of callus formation in half of the subjects. CID50 was 1,750 rads, 2,270 rads, 3,020 rads, and 3,600 rads for radiation given in 1-, 2-, 5-, or lO-dose fractions. The CID50 was 2,270, 2,420, and 2,470 rads for time intervals between Dose 1(1,000 rads) and Dose 2 on one, seven, and twenty-eight days respectively.