X-ray radiography is a non-destructive type of imaging used in modern medicine to examine fractures and other injuries in both humans and animals. Its application to art objects can reveal cracks, foreign or spurious material, and restorations invisible to the naked eye.
On the Nasca drum, the X-rays showed dramatic areas of fracturing where the ceramic had been shattered, perhaps by a blow from the excavator's pick. Filled-in pieces were revealed as lighter areas, and a totally extraneous modern tack appeared. Finally, it was clear that the surface layers varied in thickness and consistency over the surface of the drum, and that they appeared to be of different composition from the underlying ceramic.
Next, computerized axial tomography (CAT scanning) was performed. This type of non-destructive imaging, also widely applied in modern medicine for soft-tissue injuries, produces axial cross-sections of an object, or "slices."
The CAT scans confirmed the information obtained from direct radiography, but offered little new information about the surface layering due to the thinness of the layers on the drum and the resolution of the available machine. They did, however, confirm the presence of heavy restoration of different thicknesses in different areas.
