Dose distribution of therapeutic electron beams and automation of treatment planning

Until the present time, there has been no mathematical evaluation of the therapeutic electron beams in tissue material. Electron treatments are becoming universally applied from betatrons and linear accelerators. There is, therefore, a need for dosimetric programming of hospital computers for electron treatment planning such as those used in photon beam dosimetry. In this study, we have developed a theoretical model for dose calculation in a clinical therapeutic electron beam (Osman, 1972 and 1973). On the basis of this proposed theory, one can predict dose profiles at any source to skin distance "SSD"' and at any depth in tissue "X". Our theoretical model is based on considering the clinical broad electron beam used in radiation therapy as being made up of an infinite number of identical and initially parallel pencil beam components, each of minute width, to which the existing theories (Lewis, 1950; Attix et al., 1968) on electron multiple scattering, in the concerned medium apply. Dose profiles in tissue, as obtained from this model, could provide useful information as input data for routine programs of treatment planning with high energy electron beams, using mini-computers. Further, it is also possible to account for any body inhomogeneity such as subcutaneous fat, lung, air volumes, body cavities, fluids and bone from the basic parameters of these media.