Traditional X-rays generally cannot image the body’s soft tissues, except with the use of contrast-enhancing agents that must be swallowed or injected, and their resolution is limited. But a new approach developed by researchers at MIT and Massachusetts General Hospital could enable the most detailed images ever, including clear views of soft tissue, without any need for contrast agents.
They say that the new technology “could make X-rays ubiquitous, because of its higher resolution, the fact that the dose would be smaller and the hardware smaller, cheaper, and more capable than current X-rays,” says Luis Velásquez-García, a principal research scientist at MIT’s Microsystems Technology Laboratories.
While conventional X-ray systems show little or no structure in most soft tissues, the new system would show these in great detail, including the body’s major organ systems. A test the team performed with an eye from a cadaver using X-rays from a particle accelerator clearly shows all the structures, the lens, and the cornea, the team says.
The key is to produce coherent beams of X-rays from an array of micron-sized point sources, instead of a spread from a single, large point as in conventional systems, they explain. The team’s approach includes developing hardware that is an innovative application of batch microfabrication processes used to make microchips for computers and electronic devices.
Using these methods, alternating between depositing layers of material and selectively etching the material away, the MIT researchers have produced a nanostructured surface with an array of tiny tips, each of which can emit a beam of electrons. These, in turn, pass through a microstructured plate that emits a beam of X-rays.
Using the first version of the cathode, the team was able to capture high-resolution absorption images of samples where fine soft-tissue structures are clearly visible. The resulting coherent beam of X-rays from the optimized cathode chip would be equivalent to something that can now be produced only by “incredibly expensive” systems at linear particle accelerators, they say. The new system could potentially improve the resolution of X-ray imagery by a factor of 100 with hardware that costs orders of magnitude less.
The test device the team built is housed in an 8-inch metal cube, about the size of a shoebox.