[en] There is provided an electron accelerator for the production of x-rays, comprising an electron beam; a target exposed to the electron beam for the production of x-ray deceleration radiation in a beam cone; a a collimator behind the target in the direction of the beam and having a fixed dimension passageway sufficient for a beam cone adjusted to maximum dimensions; adjustable x-ray aperture plates behind the collimator in the direction of the beam; an electron absorber behind the target made of a material of an atomic number which is lower than that of copper; and an additional electron absorber positioned in the collimator and having outer dimensions corresponding to inner dimentsions of the passageway of the collimator. (auth)