[Postoperative moving field therapy of the thoracic wall with high energy electrons]

With regard to the moving field irradiation of the thoracic wall with electrons, the dependence of the surface dose from the depth of the rotation axis, which had been determined theoretically and under simplifying hypotheses, is checked by phantom measurements. There is conformity between measurement and calculation if the moving field irradiation extends over an angular dimension which contains also fully the contribution of the electrons scattered in the collimated region. The consequences for the shielding of the environment of the irradiated region are discussed. The admissible deviations of the thorax from a circular cylindric form for given maximum dose differences can be taken from the calculations. A nearly constant surface dose can be reached despite differences of the thorax form, if the scattering of electrons perpendicular to the rotation axis comes from divergency centres whose distance from the rotation axis corresponds to the double length of the average thorax radius.