X-rays are a form of electromagnetic radiation. They have wavelengths shorter than those of visible or ultraviolet light, and the photons have higher energies. Scientists have been studying x-rays since the late 1880’s. It was the German Physicist Wilhelm Conrad Röntgen who gave them the name x-rays in 1895. X-rays are actually particles of light that travel with a very small wavelength and a very high frequency. Because of this x-rays can transfer a lot of energy and can pass directly through some types matter.

An x-ray image of Wilhelm Röntgen’s wife’s hand.

After seeing Röntgen’s x-ray photographs, doctors around the world quickly saw the medical possibilities of this new technology and began to build their own x-ray machines. On February 7, 1896, the first medical x-ray in Canada was taken in Montreal by Professor John Cox to find a bullet in a man’s leg.

As you can see from the x-ray photograph on the right, x-rays have enough energy to pass through the soft tissues of the body but not enough to pass through bone or metal. If you have ever had a medical or dental x-ray, you were exposed to a level of ionizing radiation that is judged to be safe given the benefit to your health offered by the procedure.

X-rays are now used in a variety of applications such as x-ray astronomy, material testing, luggage inspection at air ports and examining microscopic objects.