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Figure 1: The coffin of Tjentmutengebtiu |
In their efforts to reconstruct the past, archaeologists often have to destroy what they seek to study. This is especially true of those studying ancient Egyptian mummies. In the past, to fully study mummies recovered from ancient tombs it was necessary to open the coffin, destroying any artwork covering it. Often the mummies are covered in incredibly detailed death masks (such as that found with Tutankhamen) which must be removed. In order to examine the actual body it is necessary to remove the bandaging used in the embalming process, and so the mummy is irreversibly damaged in the process. Dr Stephen Hughes of the Queensland University of Technology has demonstrated that the use of commonly used medical imaging techniques makes it possible to examine the mummy, without needing to even open the coffin. This work also has applications in forensic investigations.
In the early 90's Dr Hughes, then living in the UK, heard a radio program detailing the process of unwrapping mummies so that further examination could occur. At the time Dr Hughes was doing clinical work involving CT (computed tomography) scans, and thought that CT imaging could possibly be used to image a mummy without the need to remove it from its coffin and then remove its bandaging.
The British Museum in London contains a collection of around 80 Egyptian mummies. CT imaging detects soft tissue as well as bone - thus the mummy used for this study was chosen because it dated from the 22nd dynasty (c. 770 BC) - a time when the embalming process is considered to have reached its pinnacle - and so the mummy would be in the best state of preservation. The hieroglyphics on the coffin (shown in Figure 1) state that the mummy contained within was a priestess named Tjenmutengebtiu, aged between 25 and 40 when she died. Tjenmutengebtiu, or Jeni as the researchers called her, arrived at the British Museum in 1891, and was first X-rayed in the 1960's.
CT imaging
In 1991, over a number of nights, Jeni's coffin was removed from her display case, taken to St Thomas' Hospital in London and scanned on an X-ray CT scanner. As well as scans of the whole body, 115 CT images were acquired of Jeni's head. Each image represented a slice 2mm thick, with an image size of 512×512 pixels. In the mid 1990's Dr Hughes published a number of papers, detailing the results of the analysis of these scans. He and his colleagues were able to determine a number of details, such as the way in which the brain was removed, the composition of the false eyes inserted to make the dried corpse seem more lifelike, and a closer approximation of the age at which Jeni died, based on the amount of bone mineral in her lumbar spine.
When Dr Hughes came to QUT in the late 90's, he brought with him the original X-ray CT scans. These images were transferred onto the Silicon Graphics supercomputer then in use by the High Performance Computing and Research Support group at QUT. The reconstructions were performed by Mark Barry using a software package called AVS/Express. This program enables a surface to be extracted from the data. A number representing the desired level of detail - e.g. skin or bone - can be entered into the program, which then shows that surface. The images below show the different level of detail that can be displayed.
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| Figure 2: Image showing skin layer (isovalue 1000). | Figure 3: Image showing skull (isovalue 1400). |
The program also allows the user to create animations. Two animations created for this project may be downloaded below. The first show the isovalue changing from 1000 (representing the skin layer) to 1400 (representing the skull). The second shows Jeni's skull rotating.
- Skin to skull Quicktime animation, showing the transformation from skin layer (isovalue 1000) to skull (isovalue 1400): small (4.3MB) large (11.3MB)
- Rotating skull Quicktime animation: small (2.7MB) large (7.2MB)
Geographical Origin
Morphometric analysis of the skull was carried out using a computer program called CRANID, developed by Emeritus Professor Robert Wright, formerly of the Department of Anatomy and Physiology at the University of Sydney. Typically the program requires 29 measurements of the skull being examined to be entered - these measurements are normally taken from a real skull using callipers. However in this case, measurements were made on the virtual skull, reconstructed from the CT images. Six views of Jeni's skull were generated, as shown in the figures below. Using these images, 27 measurements (2 fewer than required but still enough to produce good results) of the skull were taken. The program then compared these measurements to similar measurements taken from a sample of 2,802 people from around the world, in order to calculate the probability of belonging to one geographical group compared to another.
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| Figure 4: Images used to provide cranial measurements for input into CRANID. | ||
These calculations found there was a 52.9% chance that Jeni was an Egyptian female from the 26-30 dynasty (slightly more recent than the 22nd dynasty in which Jeni lived).
The entirety of this research was performed using the computer model of Jeni's skull. Ordinarily to accomplish this analysis it is necessary to take measurements from the actual skull - in this case that would mean first opening the cartonnage surrounding the mummy, destroying much of the artwork covering the cartonnage in the process. It would then be necessary to remove the bandages from Jeni's face, and then to actually remove the skin from her face. This is obviously a very destructive process, and so this technology represents a non-invasive method of obtaining information about a mummy without destroying it.
Other applications
This technology has a possible application as a method of virtual autopsy - this is particularly useful in cases where conventional autopsies cannot be performed for religious reasons. It may also be of use in forensic science - for instance, determining the origin of badly decomposed or burnt bodies in order to reconstruct the faces for identification.
For further information visit the Computer Reconstruction of an Egyptian Mummy page on QUT's HPC website.
Contact
Dr Stephen Hughes
School of Physical and Chemical Sciences,
Queensland University of Technology
Publications
S. Hughes, R. Wright and M. Barry, "Virtual reconstruction and morphological analysis of the cranium of an ancient Egyptian mummy", Australas Phys Eng Sci Med., 2005 28(2):122-7.
Written by T. Curtis, November 2006.