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Basic Radiation Physics

Course Number: 570


Electric current provides power for the x-ray tube. The low voltage circuit that connects to the cathode, allows generation of electrons through thermionic emission. The high voltage circuit accelerates the electrons from the cathode to the tungsten target. When the electrons hit the target, their kinetic energy is transformed in its majority to heat, and a tiny fraction converts into an x-ray. The main controls of the x-ray tube are the kilovoltage that controls the quality of the beam, the milli-amperage and exposure time control the quantity of the beam. The distance between the source of the x-ray and the target controls the beam intensity. The radiographic image reflects the differential densities of the absorber (e.g., oral tissues).