The Theory of Nothing

How do X-rays work?

How do X-rays work?

Many of you might have had X-rays in a hospital emergency room to see if you broke something or to see if your lungs were clear of any infections, or you've had X-ray images of your teeth in a dentist's office. This essay will explore what X-rays are and what they do to you.

X-rays are a form of electromagnetic radiation that is in the frequency range of the spectrum below ultraviolet light but higher than gamma rays. There are soft X-rays in the 1 keV (one thousand electron volts) and then there are hard X-rays in the 10 keV to 100 keV range. An electron volt is the amount of energy gained or lost by a single electron moving across one volt.

Surprisingly, hard X-rays are favored over soft X-rays for medical purposes. This is because soft X-rays are absorbed by the body and are not useful for imaging.

X-rays are powerful and have enough energy to ionize atoms and break molecules thereby causing tissue damage. X-rays are used to see through things like the human body, determine the compositions of metal in an alloy, make a total scan of the human body, and kill cancer cells. The main thing to remember is that X-ray exposure can be dangerous.

So, how do they get away with X-ray exposing people as a means of diagnosing injuries or disease? The secret to this is to limit the exposure, which with the introduction of digital imaging is much easier than it used to be. The science of Radiology has improved to the point that X-rays are much safer, especially with the use of the new Computer-assisted Tomography, better know as a CAT-scan. During a CAT-scan, the body is scanned by a thin beam of X-rays to make a total 3-dimensional image of the body, showing bones, blood vessels and any possible tumors.

When X-rays were first used for medical imagery using film, many times the exposures were too high and caused unintentional cancers. At one time (most of you are probably too young to remember this), shoe departments in stores used an X-ray fluorescent machine to see how shoes fit. The X-ray tube was in the bottom of the machine under the place where the subject stood. The machine's X-ray image focused on a fluorescent screen, which functioned much as a TV screen. Eventually, the people in the store that worked with these machines got sick or developed cancers, which caused the banning of these crazy devices.

X-rays imaging is naturally high definition because of the X-ray wavelength, which is in the 0.01 to 10-nanometer range. A nanometer is one billionth of a meter. This small wavelength is capable of making very high definition imagery.

Astronomy uses X-ray detection from outer space sources to see things that ordinary light can't see. Many astronomical objects emit X-rays, including pulsars, quasars, supernovae, and black holes.

X-rays are produced by electron bombardment of a metal target made from tungsten, an alloy of rhenium or molybdenum in a vacuum. If the electron is energetic enough it will knock an orbital electron out of the inner electron shell of a metal atom and a higher energy level electron will take its place, emitting an X-ray photon as a result. That's the way it works.

Thanks for reading.