**Figure 2.**

*(a) Dependency of the dose uniformity K in water parallelepiped with the density ranging from 0.3 g/cm<sup>3</sup> to 1.6 g/cm<sup>3</sup> on the electron energy and the function approximating the calculated dependency (green line); (b) Dependency of Lopt on the electron energy for irradiated water parallelepiped with the different density and the functions approximating the calculated dependencies (solid lines).*

