Medical Visualization: Egyptology in 3D
A revealing high-resolution look at a 2300-year-old mummy
Renderings of the Champollion mummy in VGStudio Max 2.0 reveal the mummy’s physiology through transparentized wrapping layers
Dr. Phillipe Pomar is a professor of maxillofacial prosthetics at the University of Toulouse in southern France. You might think of that as his day job. Pomar also focuses his professional skills on his lifelong passion: the glories of ancient Egypt — its culture, its art, its artifacts, and, of course, its mummies.
“They have always fascinated me,” says Pomar. No doubt. He has degrees in both anthropology and Egyptology and leads a research initiative of the Centre National de la Récherche Scientifique in the study of mummies from the dynastic period.
For Egyptologists like Pomar, the desire to know more about mummies was always frustrated by the careful work of their embalmers. Exposing the mummy did reveal some of its secrets — but at a cost. The intrusion robbed the mummy of its pristine, undisturbed dignity. The juxtaposition of its layers was disturbed, and could not be restored. X-ray images were of only limited help in visualizing the body.
Today mummies are scanned and visualized as three-dimensional models in a non-invasive process that reveals and transparentizes all the layers applied in the mummification ritual as well as all the biological tissues that lie within them. Startling 3D images from mummy scannings have been widely publicized to a fascinated public. But Pomar and his colleagues have taken the visualization of mummies — and of live patients — to a totally new level.
Pomar is one of three co-founders of MAAT3D, a French organization of scientists, doctors, educators, 3D visualization specialists, and PhD students that scan biological objects — typically with a computerized tomography (CT) medical scanner — and create 3D visualizations with a richness of detail that has never been seen before. They do most of their work for museums, scanning mummies to create animated visualizations for presentation to the public. Their work has given them remarkable insight into mummification techniques.
“We’re looking at the ways mummification evolved across the dynasties,” says Pomar. “We want to understand how Egyptian knowledge of anatomy grew over the years. We’re also looking for pathologies, which are revealed by the skeleton.”
This visualization technology, perfected on mummies, is also being applied to the living — patients who need reconstructive facial and dental surgery. It is also proving to be the ultimate medium for medical illustration.
The Mystery Man of Champollion: An Anonymous Celebrity
The most recent anthropology project for the MAAT3D team is the visualization of a mummy belonging to the Henri Martin Museum in Cahols, France. The mummy has been loaned for display to the Champollion Museum in Figeac. Jean-Francois Champollion, for whom the museum is named, would have been delighted with this work: in 1822, he announced to the Académie des Inscriptions et Belles-Lettres that he had identified the alphabet of the phonetic hieroglyphs used in Egyptian inscriptions. His work is considered by many to be the starting point of Egyptological discovery.
The Champollion mummy itself is a mystery wrapped in a mystery. It is clear that it is of a man about 45 years old and 63 inches (1.6 meters) tall who lived between 332 and 30 B.C.E, in the heyday of the Ptolemaic pharaohs. But nobody knows when or where it was discovered or how it found its way to France. The most credible guess is that it was a prize of war, arriving in France aboard a ship of the French fleet with a returning member of Napoleon’s Expedition about 1801. The museum ultimately received it as a gift.
Nor is it known how or why this man died. His identity is a mystery; there are no inscriptions on his funerary wrappings that give us a clue. He was not a royal or even a VIP. But he is receiving royal treatment today from MAAT3D, and is destined to become a celebrity. MAAT3D scanned the mummy with a Phillips MX 8000 CT Scanner at the Figeac Hospital at a resolution of 0.3mm per slice, generating more than 7000 scan slices and a world of detail about the mystery man.
“Other mummies have been scanned,” says MAAT3D co-founder Benjamin Moreno, a 3D imaging specialist. “What sets this project apart is the 3D renderings. Nobody has seen this kind of quality before.”
At its formation in 2005, the MAAT3D team began creating visualizations from medical scans using OsiriX, an open-source imaging application, but they needed a different ray tracing engine with features such as shadowing for the museum-quality presentations they planned to create. They investigated VGStudio Max, a visualization and analysis software system developed by Volume Graphics GmbH. MAAT3D now creates its visualizations using VGStudio Max 2.0, which includes a powerful new rendering engine.
“VGStudio Max 2.0 is superb for our purposes,” says Moreno. “There’s no need for translators; we can import DICOM data directly and do many more things with it on the Mac than we can on a classic CT workstation. And you can see details with VG 2.0 that you can’t see with other software applications.”
The VGStudio Max 2.0 release introduced new technology, such as shadowing, which gives MAAT3D a better impression of volume and better control of colors. From an Egyptology standpoint, its most interesting feature is the ability to visually extract and separate structures. It enables the team to make the mummy’s cartonnage and wrappings transparent, yet visible, to provide a clear three-dimensional view of the body inside. MAAT3D does all this visualization exclusively on the Mac.
“Volume Graphics runs on multiple platforms, so we had a hardware choice to make,” says Moreno. “For us, the biggest single advantage of the Mac is the sheer stability of Mac OS X. It gives us more time to do our work, instead of coping with the bugs and restarts we get on other platforms. It’s also easier to work with. And Mac workstations are less expensive than others such as Dell. Putting price, efficiency, and stability together, we came up with the Mac.
“The Mac platform is an all-in-one solution for us. We create VG models on it, then use it for video and movie postproduction for museum presentations that will eventually be presented on iPods. VGStudio Max exports our visualizations directly as QuickTime movies. We use all the tools of the Final Cut Pro Suite to produce animations, including Final Cut Pro, DVD Studio Pro, and Motion 2. We also use Shake for special effects content creation.”
When Moreno and his colleagues moved from the Power Mac G5 to the Intel-based Mac Pro, their visualizations suddenly went from hurry-up-and-wait to real time. “We typically waited 20 seconds for a rendering on the G5,” says Moreno. “But with the Xeon processors the Mac Pro can visualize a 4.5GB dataset in real time. Scanner datasets keep growing, and with Leopard we can address a larger memory allocation. Its full 64-bit OS enables us to run applications that address massive amounts of memory, so we can visualize very large datasets. It used to take an SGI workstation, or the equivalent, to do this work. But now anyone will be able to access these big datasets with [Mac OS X] Leopard on a Mac.”
MAAT3D is working with Toulouse III University to apply VGStudio Max 2.0’s rendering power to Phillipe Pomar’s medical specialty: reconstructive facial surgery and the design of prostheses that improve the appearance and functionality of patients.
“The purpose of our work is develop ways to design prostheses more effectively using digital techniques,” says Julien Arrué, a PhD student in dentistry who is also an imaging specialist and the third co-founder of MAAT3D. “The old way is to take an impression of the patient’s face with dental materials, make a wax mold of the impression, and finally produce a silicon prosthesis. The patient may have to make four visits to the hospital, and sit with these materials on his face for up to 15 minutes at a time. In the process the molds and the prosthesis may not retain their original shape. The result may not be a good fit.”
MAAT3D does a better job by starting with CT scan slices of the patient’s head and reconstructing the skull and soft tissues in VGStudio Max, which accepts large datasets in DICOM, JPEG, and a variety of other formats. They design a prosthesis over the VG model, create a mold, and use it to make a silicone prosthesis in a process that ensures a good fit. Elapsed time: an hour or less.
This isn’t a clinical procedure yet; MAAT3D is working with a number of patients while awaiting approvals from regulatory authorities. But the concept is full of promise.
In the meantime, the number of high-resolution medical scanners available at universities and hospitals keeps on growing, and so do the resolution and quality of their images. Scientists and physicians no longer need big-budget workstations to turn these images into powerful 3D visualizations; the affordable Mac platform has brought them within economic reach, and will undoubtedly make a significant contribution to research and health care.
As for the mysterious Champollion mummy, his museum debut as an animated, translucent presence from another age is bound to inform and fascinate his audience. That will happen when the renovated Champollion Museum reopens later in 2007 and visitors are greeted by MAAT3D’s dazzling animations.
Fuente con fotos:
Fuente de referencia: EEF List