Sharp set

An adaptation of conventional X-ray technology could offer detailed, sharp images of different tissues using low doses of radiation.

X-rays have been a standard part of the armoury of medical diagnosis for more than a century. However, the technique is limited — good for looking at bones but, without a contrast agent, less useful for differentiating between the various soft tissues of the body.

In conventional X-rays, the radiation is shone through the body, with a photographic film on the other side. The tissues absorb the X-rays to various degrees — bones absorb most of the radiation, while muscle, fat, tendons and so on let most pass straight through.

But rather than considering how the waves are absorbed as they pass through the body, researchers from the Paul Scherrer Institute in Villigen, Switzerland are looking at how much they are refracted. This phenomenon is caused by the waves slowing down as they pass through a material, and this slowing manifests itself as a phase shift — a difference in the relative positions of the peaks and troughs in the waves before and after they have passed through the body. This is relatively easy to detect.