CUMULATIVE NORMAL-DISTRIBUTION MODEL FOR SIMULATION OF ELECTRON-BEAM PROFILES

A mathematical model for the electron beam profile has been developed using parameters of the cumulative normal distribution. The central feature of this model involved the derivation of an expression for penumbra width, w, as a function of depth and energy. The value of w was used in a derived analytical function to find σ, the parameter that uniquely defines the shape of the cumulative normal distribution. There was excellent agreement with measured beam profiles produced by a Varian Clinac 18 electron linear accelerator, thereby allowing us to use this model to generate isodose curves of considerable accuracy. © 1979.