Dosage data for 4,000,000 volt x rays.

Depth dose data and isodose curves for normal and oblique incidence have been measured for radiation from a 4 MeV linear accelerator. The results confirm and extend published data at this energy. The forward direction of scatter and relative amounts of primary and secondary which compose the dose at any point are such that a simple Inverse Square Law correction applies, both when the F.S.D. is changed and when oblique incidence occurs.