One of the most important advances in medical science in the late nineteenth century was made not in a hospital but in a German university physics lab by Wilhelm Röntgen, who, in 1895, produced and detected electromagnetic radiation in a wavelength range known as X-rays. These are a form of ionising radiation – radiation that has enough energy to eject electrons from atoms and so produce ions. X-rays are produced by accelerating electrons at metal targets. The type of metal involved depends on what application the X-ray is being used for. When an electron hits the metal, it slows down rapidly, and the energy produced causes an electron to be knocked out from the metal atom and this releases X-rays. The medical applications of x-rays were very quickly realized after Röntgen’s initial discovery. Today, medical x-ray images are created electronically using digital systems to diagnose illnesses and injuries. During this type of medical imaging procedure, an x-ray machine is used to take pictures of the inside of the body. The x-rays pass through various parts of the body to produce images of tissues, organs, and bones. Röntgen’s discovery earned him the first ever Nobel Prize in Physics in 1901.
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X-rays (as part of the electromagnetic spectrum) are introduced in our 1st year physics course B27FF Waves and Matter and then encountered again at various points throughout the Heriot-Watt degree programme – in the 3rd year course B29SS Solid State Physics, for example, where the phenomenon of X-ray diffraction (as famously used to determine the structure of important biomolecules such as DNA and haemoglobin) is considered in detail.