Fig. 3

Beam spectra of a tungsten target X-ray source with an X-ray exit window made of 300 μm Beryllium simulated by TASMIP software [45]. a at different tube voltages 50 kV, 75 kV, 90 kV (A continuous distribution of energies composed of Bremsstrahlung photons and discrete lines of characteristic radiation [for tungsten 58 and 69 keV] can be seen. The maximal photon energy of the beam spectrum is determined by the tube voltage. This maximal energy though is hardly represented by photons, while most of the photons are at roughly one third of this peak energy); b at tube voltages of 50/75 kV filtered with either aluminum, copper or tin of varying thicknesses (see legend); c at varying tube voltages 60, 65, 70, 75 kV filtered with a Thoraeus compound filter of Sn 0.25 mm, Cu 0.5 mm, Al 0.5 mm