Measurements and calculations of the influence of thin inhomogeneities on charged particle beams

The predictions of an analytic technique for calculating fluence and dose distributions beneath thin inhomogeneities are presented for a number of structures, including a rectangular cavity or bar, a cylinder, a disk, and an angled or diffuse edge. Experiments with both electrons and protons for several geometries are presented and compared with predictions based on this technique. We offer some clinical guidelines for avoiding large perturbations due to scattering effects.