Conservators at the Phoebe A. Hearst Museum at UC Berkeley are in the midst of reviewing CT images of a pair of crocodile mummies, which were scanned at Stanford last week.
The crocodiles, a wrapped mummy with a painted mask and an unwrapped mummy with a pack of offspring on its back, are part of a larger museum collection of Egyptian objects excavated in the early 1900s that will be on exhibit next month. Below is a photo of the wrapped mummy being prepped for scanning.
The mummies were first scanned at Stanford Medicine Imaging Center and then again at the School of Medicine's Radiological Sciences Laboratory. Stanford physicist Rebecca Fahrig, PhD, explains why this approach was selected:
The scanner in my lab provides much higher resolution than the clinical CT scanner, on the order of 200 microns instead of 600 microns from the clinical scanner. It is possible to see smaller things using these C-arm CT images than using the clinical CT scanner. The system also provides another advantage - during the scanning process we get to see very high-resolution projection (or 2-D) images of the object being scanned. During the scanning of one of the crocodiles, we noticed something in the projection images from the C-arm system that we had not seen in the clinical CT images - a fish hook. We were then able to do a very high-resolution reconstruction of the fish hook, and see details about the shape and construction of the hook.
Here's a closer look at the wrapped mummy prior to it being scanned:
Imaging the mummies required several scans because the C-arm CT scanner in Fahrig's lab can only image about 14 inches a time, and the crocodiles were very large. The mummy pictured below, for example, is over seven feet long. For that reason, numerous scans were taken of each mummy and the data from each scan was reconstructed into a three-dimensional volume. Then the volumes were stitched together into a single data set covering the whole crocodile.
As Fahrig scanned the mummies, the museum staff examined preliminary images for new clues about the contents of the mummies and their construction.
The initial scans offered some new insights, but, overall, the images generated more questions than answers. With respect to the wrapped mummy, Allison Lewis, a Kress Conservation Fellow at the museum, says:
We could immediately see that there is an intact crocodile skull in the
mask, but that the body section contains a disorganized jumble of bones and
bone fragments, at least some of which appear to be crocodilian. Sorting
out the mass of bones remains to be done. We hope to be able to tell if
more than one crocodile was incorporated into the mummy, since a very
crocodile-esque mandible fragment suggests the presence of at least one
more, and if other animal remains are present.
The same technology used to image the crocodile mummies was also used last August to scan a 2,500 year-old mummy priest, which is currently on display at the Legion of Honor in San Francisco.