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Computed Tomography (CT)

Collections Conservation Tabs

Computed Tomography (CT) is a very useful technique for non-destructively examining the interior of museum objects in three dimensions.  A regular X-radiograph provides a picture of the interior of an object projected onto a flat plane (the film, phosphor plate, or digital detector).  These projection X-radiographs can be difficult to interpret, particularly when the object is made of many pieces with similar x-ray attenuation or when features in the object overlap.  Computed tomography requires taking a series of X-radiographs from different angles around an object and then mathematically reconstructing the volume which would have caused this series of projections to appear.  Medical CT scanners, like the one shown in the image above, provide a convenient way of CT scanning many of the objects from the Anthropology collections. 

The results of CT scanning are usually delivered as a series of grayscale images of evenly spaced 'slices' through the object.  The lighter grays represent more attenuating material and the draker grays represent less attenuating material.  The stack of slices can be rendered in three dimensions and areas with similar X-ray attenuation can be segmented out and/or false-colored for further study.  Click on the images below for examples of the use of CT scanning in examining museum objects.


Mummified 'bovid', Egypt, Ptolemaic Era (330-32 BCE)


Polychrome wood statue, Japan, c. 18th CE