https://egyptmanchester.wordpress.com/2015/10/03/animal-mummies-5-seeing-inside-the-wrappings/
Animal Mummies #5: Seeing inside the wrappings
A Liverpool kitty in the CT-scanner
X-rays have been used as a method by which to see inside bodies since they were discovered by Wilhelm Rontgen in 1895. Some of the first ‘patients’ to be studied in this way were Egyptian animal mummies
which were not able to be damaged by the somewhat unknown effects of
radiation. Since this time, radiography has become increasingly
invaluable in clinical practice on living humans and animals, but it has
become one of the primary research techniques to investigate the contents of wrapped mummy bundles, preventing the need to unwrap, and ultimately destroy them.
Radiography has been widely used at the
University of Manchester since the 1970s to study the mummy collections.
From these early stages when plain film X-rays were the main method,
the technology involved in radiography has developed quickly and we are
now able to use much more advanced technologies to gain a better
understanding of mummies and how they were made. Although CT scans have
been around since 1979, their routine use on mummies has really occurred
since 2000. Advances made since 2005 with the introduction of fully
digitised methods have reduced the complexity of the X-ray and CT
process and have made it much easier to share results with fellow
researchers around the world.
Inside a kestrel mummy
As part of the Ancient Egyptian Bio Bank project,
over 300 animal mummies have been studied through a collaborative
partnership with the Central Manchester NHS Trust. The Trust have
allowed access to radiography facilities and experienced staff outside
of clinic hours to enable this work to take place. In fact, the mummies
always attract a lot of attention when they go to the hospital with
patients and staff alike taking a keen interest in the rather unusual
patients! We tend to study mummies in groups of around 20 mummies at a
time, simply because it is logistically difficult to deal with more than
this in one session. We always have experienced conservators and
curators on hand to ensure that the mummies are kept safe during the
process. Most mummies do not need to be handled at the hospital at all
as they can be scanned in their protective boxes which minimises the
dangers of handling and keeps movement to a minimum.
During
their visit to the hospital, all mummies are given a full investigation
using X-rays and they also receive a full body CT scan. X-rays are
taken in two opposing angles to ensure that we obtain the maximum amount
of information about each specimen. In some cases, the contents are
lying at an unusual angle within the bundle which means that further
images are required taken at oblique angles to capture any missing
information. X-rays have the advantage of giving
excellent spatial resolution of the contents, but they do suffer from
magnification and superimposition of structures which can
make interpretation difficult. The advantage of a CT scan is that
images are obtained from multiple directions which eliminates these
issues and allows for direct measurement of bones
and increases our chances of identifying anomalies. The data obtained
through the CT process to 3D print anomalies from inside mummies, giving
the ability to handle them directly and compare them to skeletal
collections. CT has proved successful in
identifying non-skeletal material within mummy bundles such as
egg-shell, feather and reeds which often don’t show well on X-ray.
Clinical
radiography is limited by the radiation doses allowed by the equipment.
For mummies which reveal interesting anomalies, it is sometimes
possible to use industrial CT (micro-CT) where higher radiation is used
to obtain better resolution. Some mummies which have appeared ‘empty’
when scanned at the hospital, have revealed skeletal contents when
scanned using this technique. This battery of radiographic techniques
provides the best available method to see inside mummies non-invasively.
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