Physical aspects of radiotherapy using fast electrons

The application of fast electrons in cancer radiotherapy is discussed from the physical point of view, and the various processes of interactions in matter are outlined. The concept of dose calculation and dose distribution is explained by means of the energy absorption, which is a prime criterion for assessing the desired biological effect. Experimentally selected dose problems which may occur due to inhomogeneities in the irradiated material serve as an example to demonstrate measured transverse dose distributions. The distorting effect, as a consequence of inhomogeneities of higher order, is shown by dose calculations for the irradiation of the femur. A statistical evaluation of irradiation treatments carried out in a therapeutical center contributes to a critical assessment of selection of equipment for the various medical purposes. (orig.)