Animation of the production of X-rays by a clinical X-ray machine. Inside the machine, the X-ray generator comprises a vacuum tube, in which a very high voltage is esablished between a cathode (glowing yellow) and an anode target. Electrons (blue) are generated, and stream across the vacuum gap and strike the anode, generating high-energy X-rays (yellow). The inset shows the physics of this reaction. The anode is made of tungsten, the metal with the highest melting point, as the target area becomes extremely hot. When the high-energy electrons hit the anode, they interact with the tungsten atoms, which slows them down and alters their course. The deceleration of the electrons causes them to emit an X-ray photon (yellow wave). The emission of radiation due to the deceleration of a charged particle is known as bremsstrahlung. The more the electron is decelerated, the higher the energy of the resulting X-ray, as shown by the three interactions here. The range of frequencies of the X-rays depends on the accelerating voltage, which can be precisely controlled. The X-rays are emitted in a perpendicular direction to their path, and the generator is arranged so that these pass down through the patient being X-rayed. The X-rays pass through most body structures, and a detector generates an image that can be used to diagnose medical conditions. A chest X-ray is seen on the monitor at the end of the clip.