Spectral Distribution of Scattered Radiation from a Kilocurie Cobalt 60 Unit

The spectral distribution of scattered radiation from a cobalt 60 therapy unit has been calculated. Spectra are given for once- and multiply-scattered radiation from the cobalt metal source and from the tapered sides of a lead collimator. Calculations of the attenuation of the cobalt beam including the scattered components are in good agreement with experimental data.