Beam Quality, Quantity and X-ray Properties

What x-rays are

X-rays are electromagnetic energy, so they travel in straight lines at the speed of light and carry no charge. Because they are neutral, magnetic and electric fields cannot bend them, and no lens can focus them. They are invisible, they ionize matter, they make some crystals fluoresce, which is how indirect detectors work, and they cause chemical and biologic changes. Wavelength and frequency are inversely related, and energy rises with frequency. A short wavelength means a high-frequency, high-energy, more penetrating photon. The beam is polyenergetic: it holds a spread of energies from near zero up to a maximum in keV equal to the kVp. The average energy is roughly one third to one half of that peak.