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Basic Radiation Physics

Course Number: 570

How Does the X-ray Tube Operate?

When we turn on the x-ray tube, we activate the low voltage circuit; this will preheat the filament to a specific temperature to generate electrons through thermionic emission. The number of electrons generated is proportional to the temperature of the filament.1,5,10,11 When the timer is activated, the high voltage circuit is also activated, and the electrons at the filament will start traveling at high speed towards the target. The higher is the voltage between the cathode and the anode, the faster the electrons will travel.6,7,9,11,12 The number of electrons traveling from the cathode to the anode is called the tube current.7,9 The maximum energy output of the x-ray tube is called the kilovolt peak or kVp.1,2,3,4