Doctors may soon have a new diagnostic technique, which penetrates just a few millimetres below the skin, an area of the body that other procedures like X-rays can’t easily image.
The scanning technology is based on T-rays, short for terahertz rays. This is a type of radiation similar to X-rays and light, but with frequencies around a million million cycles per second (the prefix tera- refers to a factor of 10 to the power of 12). These rays lie in the region between infra-red and microwave radio frequencies, a region that’s sometimes called quasi-optics. It’s a type of radiation that has been hard to generate in the past, but a team at the Toshiba Cambridge Research Laboratory has recently found a relatively simple way, by firing a laser at a semiconductor crystal.
T-rays are sensitive to very small changes in the composition of the materials they pass through, so they’re excellent for imaging. They also have the highly desirable property that they don’t damage living tissues. It’s likely that the first medical application will be to image skin cancers prior to surgery.
Various reports suggest that T-rays’ time is coming — they’re also being investigated for many other purposes. Because they penetrate clothing, security experts hope that T-rays will prove useful in airport scanners — to show up concealed weapons, for example. They may help to create ever-more-detailed semiconductor displays. And astronomers hope that they may reveal details of comets and other astronomical bodies.
Recent breakthroughs — combined with a range of potential applications stretching from diagnosing cancer to detecting dangerous flaws in space shuttle components — are moving T-rays out of the world of academic curiosity toward the mainstream.
U.S. News & World Report, 28 July 2003
T-rays could also be used for real-time imaging during surgery, to highlight tumour cells the surgeon has missed.
New Scientist, 30 Aug. 2003