title: Description of the uncollimated electron beam in air by means of a directional pencil beam model.
abstract: The dose distribution of an uncollimated electron beam in air, described by phi(theta x, x, z), is shown to be mathematically equivalent to a directional pencil beam model. In this model the multiple scattering theory of Fermi is assumed. After implementation of the model by using a computer program, dose distributions of electron fields of various shapes were calculated and compared with dose distributions obtained by experiment. In general, the distributions appear to agree well, but in some situations noticeable differences can be observed, which is probably due to the fact that large-angle scattered electrons are not considered in this model.
mesh_terms: D000388:Air; D004583:Electrons; D008962:Models, Theoretical; D011874:Radiometry; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D012542:Scattering, Radiation