Start-up firm develops holographic scan display

September 3, 1992

Imagine this scene in the not-too-distant future: A radiologisttakes a film of a magnetic resonance angiogram of the brain andslaps it onto a light box hanging on a wall. The box appears indistinguishablefrom other such devices, except that its surface

Imagine this scene in the not-too-distant future: A radiologisttakes a film of a magnetic resonance angiogram of the brain andslaps it onto a light box hanging on a wall. The box appears indistinguishablefrom other such devices, except that its surface is black insteadof white. And when the box is switched on, a three-dimensional,volumetric image of a human brain leaps into the room and is suspendedin mid-air, ready for diagnosis.

The stuff of science fiction? Not for Voxel, a Laguna Hills,CA, start-up company working to apply holographic technology tomedical imaging. Initially developed by two astronomers, Voxel'spatented holograms could replace slices as the primary way inwhich imaging scans are viewed, according to Dr. Allan M. Wolfe,Voxel president.

"The reason we look at slices today is that we have noother way to look at the data," Wolfe said. "I thinkthat if this (technology) is as good as we believe it to be, overtime the standard presentation will be the volumetric presentation."

Voxel's technology takes scan slices from CT, MR or other modalitiesand layers them, one atop the other, on holographic film. Whenthat film is displayed on a special light box, or Voxbox, a 3-Dgray-scale holographic image is created.

That image is superior to 3-D computer reconstructions, accordingto Wolfe. Computer reconstructions are actually 2-D simulationsof 3-D volumes and use only a small fraction of actual data collectedby scans.

"In our system, the data are the data," Wolfe said."We don't have to change anything to give a volumetric picture."

CONVENTIONAL HOLOGRAMS ARE CREATED by splitting a laser beam intwo. One part of the beam is shone directly onto the holographicfilm, while the other part is reflected off the object being holographedand onto the film. The process is similar to that of photographicfilm, except that the laser beams contain information about thedistance of the object from the observer--information missingin a photo.

The breakthrough that enabled the development of the Voxelsystem was made by two astronomers working at London Universityin the 1980s. While trying to develop a way to determine the shapeof a distant celestial body, they stumbled on a technique thatpacked over a hundred exposures onto the emulsion of holographicfilm. Conventional wisdom at the time held that holographic emulsioncould hold only four exposures, which limited the type of imagesthat could be reconstructed.

The astronomers decided that medical imaging would be the bestway to commercialize the technology because of the similaritybetween CT and MRI scan slices and the layering of multiple holographicexposures on film. The use of a light box to display a hologramis also similar to the way in which radiographic film is viewed.

In Voxel's process, a slice from a CT or MRI scan is projectedonto a screen and a hologram is made. The screen is then movedback a distance corresponding to the gap between slices and asecond hologram is made of the next slice. This continues untilall the slices of a scan are recorded.

Wolfe sees a number of applications for Voxel's holograms,particularly in neural imaging. MRA looks promising, as well asradiation therapy planning. Multimodality imaging of the sametarget is also possible, simply by layering holographic exposuresfrom CT and MRI slices on top of each other.

Holographic MRA is the focus at Redwood City MRI in RedwoodCity, CA, one of Voxel's 12 test sites. Dr. Murray Solomon hasbeen working with the technology for five years and sees a brightfuture for it.

"These images are really pristine," Solomon said."It's an angiogram sitting in space."

Redwood City MRI sends data from its MRI scans via courierto Voxel, where a holographic camera creates a hologram from thedata. The film is sent back to Redwood City, where it is displayedon a Voxbox at the center.

As most radiologists would desire a quicker turnaround fortheir scans, Wolfe anticipates developing and marketing the holographiccameras to individual radiology facilities at a price tag of about$100,000. The Voxboxes on which holograms are displayed cost about$500.

Voxel could have a product to market within two years, accordingto Wolfe. Most major obstacles to commercializing the technologyhave been overcome, although Voxel is not certain whether Foodand Drug Administration approval would be required.

If it does reach the market, Voxel's technology will be wellreceived by radiologists, according to Solomon.

"Today with MRI, we can do a scan with 150 slices,"Solomon said. "How does someone process mentally 150 slices?This is a 3-D life-size image. You look once and it's all there."