Published April 18, 2006
Volume 14, Number 4

Dr. Horst Bruning is Adding New Dimensions to Medical Imaging

By Jay Hipps

The place where science and technology meet is comfortable ground for  Dr. Horst Bruning, president and CEO of Exxim Computing Corporation.  Dr. Bruning, whose PhD is in physics, first became interested in the  subject during a year as a high school exchange student in New York.

“There was a very good physics teacher there. I liked the guy and he  made it exciting to look into physics. It explains it all, right?  These physics books, like A Short History of Nearly Everything,  they’re popular books, and they’re basically the physicist’s view of  the world—things which you observe, and you try to explain them using  the language of math, so it’s reproducible.

“Our scientific approach through observations, that’s what I kind of  liked, because it makes you feel like you have a solid foundation—you  can come back to it and it will be reproducible every time. Today,  the scientific methodology has been expanded into genetics and these  modern bioscience/life science industries. But physics is kind of at  the basis of it.”

After completing an undergraduate degree in his native Germany, he  worked at CERN in Geneva, Switzerland, the world’s largest particle  physics laboratory. He supported the lab’s quest to discover new subatomic particles. “There was a time there in the 70s where there  were lots of new particles coming up, like every month a new one, and  the experimental work that we did there had to do with particle  detectors. I was an experimental physicist building these detectors  to find pi mesons and psi bosons and things like that, calculating  their energy and their charge and these things.”

He earned his PhD then and decided to apply this technology to  “something useful,” as he puts it. “Maybe particle physics is useful  in the long run, but not directly.” He took a job at Siemens Central  Research and Siemens Medical, building x-ray detectors and getting  into the more computer-driven world of computer tomography (the  building of images detected by x-rays, ultrasound, or other means  using computers).

“I used the physics background to go into electrical engineering and  software and imaging applications, but other physicists stay in the  scientific realm and do cosmology or things like that. The  mathematics is very similar but I am more applications-driven; I want  to build machines which are out there in the field and help people  and can be sold and turned into a business. I’m an applied physicist.”

He contributed to computed tomography (CT) scanners (originally  known as CAT scanners, an acronym for computed axial tomography) at  Siemens and at Imatron in South San Francisco. Aside from finding  that he enjoyed his work, he made another important discovery: he  wanted to live in the Bay Area. “I went back to Germany and kind of  didn’t like it anymore—too much rain! California is like a diode— people come here but they hate to go the other way.”

He returned to the area to work at Invision, a security scanner  company that was just recently bought out by GE, and continued his  work on CT technology and visualization at TeraRecon in San Mateo  before founding Exxim—the name comes from “extreme x-ray imaging for  the XXI century”—in 2002.

“You see opportunities and when you are in a company, you try to do  it within the company, obviously, but sometimes it’s not possible  because it doesn’t fit the business plan of that particular company.  If you feel strong enough about it and you really want to do it,  there’s only one way: to do it yourself and start a new company. I  think this is how many of the new small companies here in the area  have come up. People had an idea, wanted to realize it, couldn’t do  it in the environment they were in, and started by themselves. There  are lots and lots of very small companies like this, five-person  companies that do really interesting high-tech stuff.”

There’s no shortage of really interesting stuff going on at Exxim.  While CT scanners typically take two-dimensional images of a cross- section of a person, animal, or object—usually referred to as a  “slice”—the latest scanners use a wide area detector to scan an  entire three-dimensional volume, which has been given the name “cone- beam tomography.” Exxim’s primary product in this area is COBRA,  software that takes the raw data output by a cone-beam CT scanner and  reconstructs it into a “volume output image,” which is essentially a  navigable, color 3-D image.

“We’ve found some very interesting applications for this. One  application was almost unexpected for us—it’s in dental x-ray  imaging. Dental offices use a lot of x-rays and normally you have  these little films that you stick in your mouth. Today, they have  these small digital reception device detectors that you can stick in  there, but basically you get one bite wing, as they call it,  radiograph. Now you can have an area detector x-ray so as you go  around the head of the patient, you get a three-dimensional image of  the jaws and the teeth. The images are fantastic.

“People use this imaging technique to assess the quality of the jaw  bone for an implant. Many people get implants today as opposed to a  bridge or something to replace lost teeth and the bone needs to have  a certain quality—they drill a metal screw in the bone, so the bone  needs to be strong enough to withstand that, and also you don’t want  to screw into the nerve and do damage. So you can assess the whole  geometry of the jaws and the facial bones. That’s an enormously fast- growing market, and these people use our software.”

Exxim’s technology is also being used in scanning small animals, such  as mice, which are used in research settings at pharmaceutical  institutes and universities. “You can scan the volume of the mouse  rapidly with these volume scanners.” This allows researchers to  follow internal changes in the animal’s anatomy, which is useful in  research in research for new treatments for tumors, among other things.

Another new application for Exxim’s technology is a security  application for detecting bombs in luggage. “In one single scan, you  can scan a whole bag in volume and find hidden explosives in there.  There’s still some work to be done, though.”

Dr. Bruning also continues to utilize his expertise in building  detectors in a project he is working on with Real-Time Radiography,  an Israeli company out of the Jerusalem Technology Park which is  making a new material to convert the incoming x-rays into electrical  signals more efficiently than it’s done today. While current  technology relies on light generated by the x-rays interaction with a  compound like cesium oxide, the new technology uses mercuric iodide,  a heavy compound which generates electrical charges when exposed to x- rays rather than light. This allows for images with greater  sensitivity and detail. “It gives you a bigger signal and you can  make the images using a lower dose of x-rays.” A product using  Exxim’s detector developed in conjunction with Real-Time Radiography  is expected to be on the market about two years from now.


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