Introduction to X-Ray Production (How are X-Rays Created)

The number and energy of X-rays produced are controlled by the operator using milliampere (mA), kilovoltage peak (kVp), and exposure time. Increasing mA or exposure time increases the total number of X-rays (intensity/quantity). Increasing kVp increases both the energy (quality) and the total number of X-rays produced.

X-rays are not mythical; they are real and require a specific production process involving three key elements: a source of electrons, a method to rapidly accelerate these electrons, and a way to rapidly decelerate them. All these steps occur within the X-ray tube.

Electrons are generated at the cathode filament of the X-ray tube through thermionic emission. A current heats the filament, causing electrons to be released and form an electron cloud, similar to how an incandescent light bulb filament produces light.

The second step is to accelerate these electrons, imbuing them with high kinetic energy. This is achieved by applying a kilovoltage peak (kVp) which creates a strong negative charge at the filament and a positive charge at the anode, propelling the electrons across the tube towards the anode.

Finally, the highly energetic electrons are decelerated by slamming into the anode. This rapid deceleration converts their energy into heat and, crucially, into X-rays.