A MODEL of the way terahertz radiation interacts with skin has explained why it is so good for spotting skin cancer.
T-rays have a frequency between the infrared and microwave ranges, and they can penetrate the top few millimetres of skin, the region where skin cancers grow. Clinical trials of a scanner that uses T-rays to map the extent of skin cancers are already under way at Addenbrooke’s Hospital in Cambridge, UK, and the preliminary results are very promising – cancerous tissue stands out clearly (¿ìè¶ÌÊÓƵ, 30 August 2003, p 11).
But why? The company developing the scanner, TeraView, also in Cambridge, had been at a loss to explain the mechanism. Now its researchers have published a pair of papers suggesting that water is responsible. A team including Emma Pickwell has worked out equations that describe how water absorbs T-rays (Applied Physics Letters, vol 84, p 2190).
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The researchers have also shown that this model can be applied to skin (Physics in Medicine and Biology, vol 49, p 1597). The model predicts that differences in the water content of healthy skin and tumours provide the contrast seen in the trials.