Popular Mechanics - July 29, 2013 - Joe Pappalardo -- Weapons maim the heads and faces of soldiers in cruel ways. Because of this, facial reconstruction is as old as the ancient Egyptians, who fashioned cosmetic noses that could be lashed on to the faces of wounded warriors.
Today, the problem persists, but modern medicine has an array of scanning equipment and digital processing tools that bring a high-tech edge to craniofacial prostheses. "We switched from doing things as artists to doing things as technicians," says Capt. Gerald Grant, the director of craniofacial imaging research for Naval Postgraduate Dental School. Grant heads an effort at Walter Reed National Military Medical Center in Bethesda, Md., to bring 3D imaging to cranial and facial prosthetics, helping to create implants that fit perfectly into a patient's face and restore his or her appearance to close to what it was.
Doctors use a type of scan called cone beam computed tomography (CBCT) to capture 3D images of skulls and jaws. The CBCT scanner circles the patient's head and captures hundreds of images, which are processed into models and schematics of the patient. These models can produce built-to-order implants made of titanium or polymethyl methacrylate.
Surgeons and implantmakers examine the CT scans in an immersive environment before surgery, forming a plan for the operation, which reduces the patient's time on the table. The implants are made with guides that help during surgery, including features as simple as dotted lines on the material and as elaborate as metal edges that ensure a perfect fit.
Still, there is another big challenge for Grant's team: fine-turning the prosthesis so that the wounded soldier looks as close as possible to the way he or she did before the injury. "We use posttraumatic scans, so we know what they look like after they've been injured," Grant says. "A lot of times, if someone has an injury on the left side (of their face) we can mirror the right side, overlay it, and rebuild. When people have midfacial fractures, you can't really do that."
The solution: Scan the troops before they are wounded. Grant and his team want to figure out the logistics and methods that would be needed to make a scan of all incoming troops. The studies seem promising: In one recent test, newly recruited Marines were scanned with a CBCT head-capture machine. The process took only 12 seconds per soldier. Each branch of the military will have to decide whether to adopt the technique.
Grant and his team of military doctors are currently evaluating new software that can create better 3D visualization, including holographic images that float in front of the user's face, which doctors could examine and manipulate as if they were real objects. "A lot of this is emerging technology, and it's not geared to medicine but for engineering and entertainment," Grant says. "We have to adapt the software to see if it can do what we want it to do."
One of the vendors being evaluated by the military for holographic scans is zSpace, whose developers designed their system to work with most off-the-shelf computers, transforming "a PC into a virtual holographic computing system." PopMech got a hands-on demonstration of zSpace during a recent visit they made to the magazine's office in New York. They brought their own 3D-compatible screen and ran software that enabled editors to manipulate images floating in midair.
Sensors in the screen's corners determine the location of the tip of a stylus, which has its own accelerometer. Two cameras mounted long the top edge link up with sensors in the glasses to keep track of your face's orientation, which is important in creating seamless images, even when the user's head moves. Using the buttons on the stylus, users with no training were able to carve up sections of a human brain, removing parts to explore the organ's inner depths and zooming in with no loss of resolution. Another program displayed molecules, which we were able to manipulate and then examine, in simulated microcosmic flight, from various 3D perspectives.
Military doctors are only one interested customer of this emerging technology, once reserved for ship and aircraft engineers. It could be used to create high-fidelity holographic cadavers for med students or for the mapping of cities for the military and other U.S. government customers.