Computed Tomography (CT) Helps Unlock the Secrets of the Past

In 2012, Berlin conservator Katrin Lück brought a tiny, severely corroded lead scroll to GE’s Technical Solutions Center in the town of Wunstorf in northern Germany.

Lück believed that the precious, 1,600-year-old artifact, which measured just 3.6 centimeters long and 1.5 centimeters wide, contained scriptures in Mandaic — the language of an ancient gnostic religion dating back to Christ’s birth. She wanted to read the verse, but unrolling the scroll would destroy it.

So she turned to technology. At GE’s lab, the company’s largest facility exploring industrial uses of computed tomography (CT), she used an industrial-grade CT scanner to help virtually “unroll” the scroll and decipher the characters contained in 41 lines of Mandaic writing.

Top and above: After using the CT scanner and software from Volume Graphics to create a virtual image of the scroll, Lück “unwrapped” it inside the computer and decrypted the text. (See also video below.) Image credit: Volume Graphics GmbH, Heidelberg, Germany.

 

 

Ordinary medical CT scanners typically use low-energy X-rays to see inside the body. They enable doctors to image organs from several angles to create detailed 3D visualizations. But the industrial CT scanners built in Wunstorf are even more powerful. GE originally developed them to examine and measure aerospace and automotive parts, and CT customers use them to peer through metal and hunt for defects in turbine blades, 3D-printed parts and other high-tech components.

Unlike CT scanners found in hospitals, the industrial version can snuggle up to the studied specimen and reconstruct it in three dimensions in much greater resolution. Industrial X-ray tubes also generate more penetration power for dense or metal objects. As a result, GE’s industrial CT machines can see details up to several hundred times smaller than medical CT scanners can detect, says Dirk Neuber, a spokesperson for GE Oil & Gas’ Digital Solutions product company.

Karen Lück with the Mandaic scroll in front of an industrial-grade GE CT scanner. Image credit: GE Oil & Gas Digital Solutions

This ability has made it a favorite tool for any modern-day Indiana Jones. In 2011, for example, a team of German construction workers were leveling a field for the development of new homes in Visbek, a small town in northern Germany known for an ancient abbey that helped spread Christianity throughout the surrounding Saxon lands.

The routine job turned into an adventure when they uncovered an ancient burial plot. Amid the remains was a remnant of what appeared to be a rusty weapon, possibly a sword. Archaeologists dug out the block of soil surrounding the piece of metal and coated it in plaster to save it in situ for examination and conservation.

Next, they took the find to Wunstorf, where scans revealed a 2.5-foot-long medieval sword with ornamental rivets dating to the eighth century. The sword probably had belonged to a wealthy Saxon.

Archaeologists dug out the block of soil surrounding the piece of metal and coated it in plaster to save it in situ for examination and conservation. Image credit: GE Oil & Gas Digital Solutions

The machine also delivered an unexpected bonus — a companion dagger revealing that the Saxon warrior has been buried with a small personal arsenal. “CT is not only a great tool to examine what hidden features to expect, but also to document the whole archaeological object as it was, before preparation and conservation starts, sometimes turning fragile organic remains like textiles or wood into dust when being touched,” Neuber says.

Scientists have used medical CT scanners and X-ray machines to learn the secrets of Egyptian mummies for decades. But industrial CT technology promises a whole new level of much more detailed discovery. Says Neuber: “They’ve seen things no archaeologist has ever seen before.”

A complete CT scan of the Visbek sword. Image credit: Lower Saxony State Service for Cultural Heritage, Hannover, Germany.

 

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