A 50 Curie Cobalt 60 Teletherapy Unit

The conversion of a 5 g radium beam unit to one containing 50 c of 60Co is described. The conversion necessitated a number of modifications to the existing unit and additional protective devices. The distribution of the radiation in a phantom is described and also the build-up of ionization in the first few millimetres below the surface. Dose distributions for typical treatments are shown and the volume dose obtained using such a unit is discussed.