X-ray production

X-rays are produced due to sudden deceleration of fast-moving electrons when they collide and interact with the target anode. In this process of deceleration, more than 99% of the electron energy is converted into heat and less than 1% of energy is converted into x-rays.



The cathode is the negative terminal of an x-ray tube. It is a tungsten filament and when current flows through it, the filament is heated and emits its surface electrons by a process called thermionic emission.


High voltage, in the kilovolt range (1000 volts), is applied between the cathode and anode. This causes electrons to move towards the positive terminal of the tube at a velocity of half the velocity of light.


The positive terminal of the tube. It is made of a tungsten disc in ordinary diagnostic x-ray tubes, and molybdenum in mammography x-ray tubes. Fast-moving electrons interact with the anode in following ways: 

  • interaction with K-shell electron: causes the production of characteristic radiation
  • interaction with nucleus: causes bremsstrahlung radiation
  • interaction with outer shell electrons: causes line spectrum
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Article information

rID: 25428
Section: Physics
Tag: refs
Synonyms or Alternate Spellings:

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Cases and figures

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    Figure 1: bremsstrahlung radiation
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    Figure 2: characteristic radiation
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