ABSTRACT
The explosion of scientific and clinical works immediately after Conrad Roentgen’s discovery was an indicator for the huge lack of knowledge about the interior morphology of patients. “More light” were supposedly Johann Wolfgang von Goethe’s last words. This is what Roentgen has generated. X-ray photons interact with tissue, fat, bone, water, or air. They are either extinguished or scattered out of the initial direction, or generate secondary photons depending on the elementary composition of the object and the material density. In all these cases, photons disappear from the primary beam. Usually, only a small fraction in the order of a percent will reach the detector. The classic electromagnetic picture of electromagnetic waves and/or the quantum mechanical photon picture will be used—whichever suits best and delivers the most accurate results as well as intuitive understanding for the given situation. Loosely bound electrons have binding energies much below the energy of incoming X-ray photons.
