RadioGraphics, Vol 17, 967-984, Copyright © 1997 by Radiological Society of North America
The AAPM/RSNA physics tutorial for residents. X-ray production
CH McCollough
Department of Diagnostic Radiology, Mayo Clinic Rochester, MN 55905, USA.
X-rays are produced when highly energetic electrons interact with matter
and convert their kinetic energy into electromagnetic radiation. The two
unique mechanisms by which x-rays are produced are called the
bremsstrahlung and characteristic processes. Bremsstrahlung x-rays produce
a continuous x-ray spectrum, whereas characteristic x-rays are produced at
specific narrow bands of energies. Many technical parameters of the x-ray
production equipment affect the magnitude and shape of the x-ray spectrum.
The quantity of x-rays produced varies proportionally to the tube potential
squared, tube current, exposure time, and atomic number of the anode
material and is inversely proportional to the distance squared. x-ray
quantity is also affected by the voltage waveform (generator type) and tube
filtration. The shape of the x-ray spectrum is affected by the atomic
number of the anode material, tube potential, filtration, and voltage
waveform.
