Scientists have essentially reengineered the X-ray to deliver 2D and 3D images of soft biological tissues! The Optical Society of America believes that the newly developed phase-sensitive X-ray device “could help usher in a new kind of medical imaging for clinics and hospitals.” Here’s how it works, taken from the press release:
Optics researchers have long known that x-rays have the potential to make detailed images of soft biological tissue through a technique known as “phase” imaging. X-rays, a form of electromagnetic wave like light, can be visualized as a series of peaks and valleys like a water wave. When an x-ray encounters the boundary of two types of material, such as normal tissue and cancerous tissue, it will undergo a “phase shift”: the peak of the wave will move backward by a small amount relative to the position where it would be if there were no sample in the beam. By measuring the phase shifts as x-rays pass through the boundaries of different kinds of tissue, researchers can obtain detailed pictures of soft biological tissue.
In a demonstration that could bring this approach much closer to medical applications, a new phase-based imaging device combines three desirable attributes–compact size (only a few centimeters in length), large field of view (up to 20×20 cm 2), and the ability to use x-rays over a broad spectrum of energies. Crucially, the design uses a pair of gratings–each a thin slab of material with narrow, closely spaced parallel lines etched deeply into them, like little slits carved into the inch marks of a ruler.
In the setup, a stream of x-rays passes through the object to be imaged and it undergoes a series of phase shifts, which distorts the stream in a precise way. The distorted x-ray stream then passes through the first grating and is diffracted; the grating slices the x-ray stream into multiple waves that combine and interfere to produce a series of fringes (bright and dark stripes). The second grating extracts from this pattern precise information on the inner details of the object (see accompanying article for more information).
Using this technique, the researchers imaged a small spider, revealing internal structures that would be difficult to image with any other method.