DURHAM, N.C. - Engineers at Duke University have demonstrated a prototype X-ray scanning machine that reveals not just the shape of an object but its molecular composition. With unprecedented resolution and accuracy, the technology could revolutionize a wide range of fields such as cancer surgery, pathology, drug inspection and geology.
Many of the ideas behind the prototype were originally conceived in the pursuit of performing better bomb detection for aviation security. In the new paper, published online May 19 in the journal Scientific Reports, the researchers adapted the technology for several targeted scientific and medical applications.
"Whether you're trying to spot a bomb in a bag or a tumor in a body, the physics is more or less the same," said Joel Greenberg, associate research professor of electrical and computer engineering and faculty of the medical physics program. "But from an engineering point of view, the constraints on the two are very different. We built this smaller, higher-resolution device to demonstrate that our approach could be used for a number of different applications."
The technology is a hybrid X-ray system that combines conventional X-ray transmission radiography with X-ray diffraction tomography. The former involves measuring the X-rays that pass straight through an object. The latter involves gathering deflection angle and wavelength information from X-rays that have scattered (or bounced) off of an object, which provide a sort of "fingerprint" unique to that material's atomic structure.
One of the hurdles to adopting this technology is that the scattered X-ray signal is typically very weak and complex. This results in very few X-rays reaching the detector with each image captured, which leads to long delays while the scanner gathers enough data for the job at hand.
The Duke team's approach uses a coded aperture, a sort of pierced shield that allows X-rays travelling at many different angles to pass through its holes. The trick is in knowing the exact pattern being used to block the X-rays, which a computer can then use to process the larger, more complex signal. This allows the researchers to gather enough deflected X-rays to ID the material in a shorter time span.
In the paper, the researchers developed a new method for creating high-quality, 3D coded apertures, designed a new machine end-to-end with a user interface and compact footprint, and built a prototype using off-the-shelf components regularly used in medical imaging.
