Radiography – the use of electromagnetic radiation such as X-rays – is a way of examining objects without damaging or destroying them. Developed for medical diagnosis, radiography is now widely used to look at archaeological objects, including human remains.

X-ray

When X-rays are directed at an object, some are absorbed and some pass through the object to form an image on photographic film placed on the other side. Some substances absorb more radiation than others, and more rays will be absorbed by thick materials than thin, creating lighter and darker areas on the photographic film. In the case of human remains, X-rays can be used to show any damage to the skeleton, giving clues to how the person lived and died.

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CT (or CAT) scans

While X-rays provide a flat, two-dimensional picture, CT or CAT (Computerised Axial Tomography) scanning gives a three-dimensional image. X-rays are directed at an object from all sides to create images of a series of 'slices' through it. A computer is used to combine these slices to generate a three-dimensional reconstruction of the object. A detailed picture can therefore be obtained of the whole object or any aspect of it.

Used in medicine to diagnose cancer and other conditions that affect soft tissue, CT scanning is proving to be an increasingly valuable archaeological tool. It was used to examine the remains of the baby ice mummy found in Greenland and also in the exhumation of Tutankhamun's mummy in 2005.

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X-ray shots of a bog body

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