T.O. 33B-1-16-406.5.2 RealLifeAbsorbers.In industrial applications test specimens are being bombarded by the radiation photons which are absorbed andscattered, and in the process electrons are ejected from the atoms of the test material. These absorbers are not ideal;they do not act as an ideal absorber in that they do not attenuate radiation in accordance with theoretical physics.Electrons degenerated scattered photons, characteristic radiation from the test material, and some of the primary beamis all present on the film side of the test object simultaneously. The classical attenuation equation does not consider allthese various components, so it is not strictly applicable in actual radiographic practices.6.5.3 WhiteSpectrum.Radiation generated by an X-ray tube contains various energies and therefore is referred to as white radiation (seeFigure 6-17). The X-rays are a continuous spectrum and the beam is selectively attenuated as it passes through anabsorber. The low energy radiation is highly absorbed by the first few layers of the absorber medium and the spectraldistribution is altered by this selective absorption. Thus, as the white radiation is being absorbed by an absorber it morenearly approaches monochromatic radiation. Figure 6-17 shows a semi-logarithmic graph of the absorption of amonochromatic beam and a multi-energy beam of white radiation. For approximate estimations of effective X-rayattenuation coefficients, it may be assumed that the average energy of an X-ray beam is about 50 percent of the peakoperating kilovoltage for glass window tubes and 30 percent for beryllium window X-ray tubes.Figure 6-17. Absorption Curves of Monochromatic and Multi-Energy Radiation.
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
