[Fast electron beams in radiotherapy. Physico-dosimetric basis]

The author starting from the electron beams production describes their interaction with matter in terms of stopping and diffusion. The "dose" and its spatial distribution is considered the physical parameter more suitable to describe the electron beams characteristics. Particularly, it is outlined that the experimental depth penetration curve of dose in water, can provide the parameter evaluation useful to characterize the electron beams both qualitatively and quantitatively, i.e.: beam dimensions at the entrance surface; mean energy Eo; maximum dose (Dmax) depth, R100; surface dose, Ds (% Dmax); depth of 50% of Dmax, R50; practical range, Rp; therapeutic range, R85. The operative steps are described as referred to the National Protocol of Standardization (basic dosimetry).