PSI's imaging takes X-rays to the next level

Researchers at the Paul Scherrer Institute (PSI) in Switzerland have devised a way to make traditional X-ray imaging significantly more sensitive and to incorporate the new technology into current medical imaging equipment. Their research advance diagnostic imaging rapidly. The group is now seeking commercial investment to take their project forward.

The technique is a type of phase-contrast microscopy that has been in use at large-scale X-ray synchrotron facilities for a number of years but, until now, has been too costly and inefficient for medical applications. The new PSI technique could be taken from laboratory to hospital as a simple add-on component to the equipment that is currently used.

Traditional techniques create an image from the level of X-rays absorbed by different materials. This is useful for imaging dense body matter like bone, which has high absorbance. Tissues with a low absorbance, however, create low-contrast images in which it is difficult to reproduce fine details.

The basis of this new technology is that X-rays undergo a phase shift when they pass through matter – that is, waves are deflected by the tissue. Phase-shift microscopy measures these changes to give a more detailed image.

Previous phase-sensitive imaging has required the use of very powerful sources of X-rays, for example from synchrotrons, to produce collimated X-rays, which are almost like lasers. These methods are costly and inefficient in that they only use a very narrow bandwidth of the X-ray.  

The new PSI technique uses an interferometer, a mask that can be placed over the X-ray source to measure phase shift signals by translating them into changes in the transmission.  The interferometer is made of two gratings of material (usually silicon wafers) with fine grooves etched into them. Deflected rays pass through these grooves and to a detector. As this device can be fitted in front of the detector, current hospital X-rays could be easily adapted to offer this type of phase contrast imaging.

Diagnostic imaging would particularly benefit as Franz Pfeiffer from PSI explained: “Because of the size of the field of view that can currently be imaged, we are close to being able to use this application for mammography. We are also developing the technology to expand the field of view to a size for diagnostics such as X-ray chest radiography or angiography.”

PSI is also working to develop the technique for inspection technology, to improve security scanning.