Diagnosing a number of important medical conditions would be easier and less expensive if X-ray imaging techniques offered improved resolution.  In patients suspected of having breast cancer, for example, around one million unnecessary biopsies are performed each year because of inconclusive imaging.  Atherosclerotic coronary artery plaque, a major cause of heart attacks, is also difficult to monitor using today’s imaging techniques, which only provide resolution at the hundred-micron scale.  New technologies are on the horizons, however, and Dr. Rajiv Gupta of MIT hopes that his laboratory will soon be able to produce an X-ray imaging system capable of achieving one-micron resolution using clinically acceptable doses of radiation.

Most X-ray systems in use today detect X-rays using a layer of scintillating crystals in front of a photodetector.  The scintillating crystals, when hit by an X-ray, release visible light in all directions, and some of this light is subsequently detected by the photodetector.  When the layer of scintillating crystals is thick, not many X-ray photons are needed to produce an image, but the image’s resolution will be low because of light scattering within the crystal layer.  When the layer of scintillating crystals is thin, the resolution will be high, but many X-ray photons will be needed to produce an image.  Thus, traditional X-ray techniques are limited by a tradeoff between resolution and the dose of radiation. 

Dr. Gupta has proposed a new method of X-ray imaging designed to reduce light scattering without requiring more photons.  His technique involves scintillating nano-crystals embedded in optical fibers.  A material that absorbs X-rays and reflects light will surround each fiber.  Light produced by a scintillating crystal within a fiber will not scatter and will be transmitted to a detector at the bottom of the fiber.  Techniques already exist to make bundles of optical fibers with individual diameters of less than one micron, and Dr. Gupta’s laboratory has come up with a way to embed nano-crystal particles within the fibers.  One final challenge to be overcome before the new imaging technique can be tested is that of optimizing the density at which the fibers will be doped with crystal particles.  At higher crystal densities, more light is produced, but the fibers become more turbid.  If the X-ray detection strategy being developed in Gupta’s laboratory achieves it theoretical potential, it could revolutionize X-ray imaging in today’s healthcare system.                 

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