Terahertz radiation: On your medicine's secret service
Dübendorf, St. Gallen und Thun, 26.11.2019 - Whether a wound heals well under a bandage cannot be seen from the outside. Empa research-ers are now enabling a view through the bandage à la James Bond. The refined application of terahertz radiation could promote the analysis of multi-layered tissues in the medical field and be used for wound treatment or the diagnostics of blood vessel plaque.
An evening at the casino, the spy in the tuxedo pulls the latest gadget out of his pocket: blue-tinted specs. And with a look through the spy glasses, James Bond effortlessly sees through the casino vil-lains' clothes and identifies their weapons under their jackets in "The World Is Not Enough". But not only fictional figures like Bond's creative quartermaster Q are interested in the "X-ray view". In reality, the view through the fabric is already being used, for example for security checks at the airport using so-called body scanners. Empa researchers are developing new methods that allow a close look at a wound, for example, without having to remove the dressing, so that the unobstructed view of hid-den objects can also be used in biomedicine. However, this does not involve the use of ionizing electromagnetic radiation, as is the case with X-ray examinations by doctors, but rather terahertz radiation in the wavelength range from 0.1 to 1 millime-ter. Thus the waves range between warming infrared and radio waves and are not harmful to a per-son's health. Transparent textiles The team led by Peter Zolliker and Erwin Hack from the "Laboratory for Transport at Nanoscale Inter-faces" in Dübendorf has now completed a project funded by the Swiss National Science Foundation (SNF*) in which terahertz radiation is not only intended to detect concealed objects, but also to deter-mine the interaction between the hidden target object and the visible surface. This further development of terahertz technology can in future be used, for example, for the gentle observation of wounds that are securely wrapped in a dressing. On the one hand, the patient is not exposed to the risk of infection and the fragile healing tissue is not damaged by too frequent removal of a dressing. On the other hand, the monitoring of complex wounds, like burns or chronic skin damage, is necessary and contrib-utes to personalized medical treatment. However, terahertz rays, for which a large number of materials such as textiles, plastics, paper and wood are transparent, allow non-contact inspection. "Until now, the image resolution of terahertz systems has been rather poor," explains Empa researcher Lorenzo Valza-nia. In addition, the effect of textiles on the skin has not yet been directly observable. Sharpening down to the nanometer range If, of course, the interaction of textile and skin is to be determined, the properties of the covering mate-rial must also be taken into account in the image reconstruction of the skin surface. For this purpose, Valzania has developed a new phase determination technique with which the desired object and the covering textile can be detected by means of transmission geometry. Among other things, a continuous wave gas laser as the source of the Terrahertz radiation and a surface detector that records the result-ing diffraction patterns are required. With the help of a special phase determination algorithm, a co-herent, three-dimensional reconstruction of both structures can be created, since the algorithm allows the separation of the radiographic functions of the two objects. The process is comparable to collect-ing and separating paper at the office printer when several print jobs are mixed and end up in the out-put tray. While body scanners at the airport have a resolution in the millimeter range, Empa researchers have optimized it in their experiments down to two tenths of a millimeter. Further sharpening down to the nanometer range is to follow soon. In the future, blood, skin profile and textiles should be easily distin-guishable. Other biomedical applications include oncological imaging diagnostics without the use of contrast media and non-invasive analysis of blood vessels with suspicious plaque.
Address for enquiries
Dr. Peter Zolliker
Transport at Nanoscale Interfaces
Tel. +41 58 765 45 08
Peter.Zolliker@empa.ch
Dr. Erwin Hack
Transport at Nanoscale Interfaces
Tel. +41 58 765 4273
Erwin.Hack@empa.ch
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Federal Laboratory for Materials Testing and Research
http://www.empa.ch
