Safe X rays
Reseachers at Toshiba's laboratory are developing a safer alternative to X-rays. This new approach called terahertz pulse imaging (tpi) relies on terahertz pulses, also known as millimetre waves, which lie between the infrared and microwave frequencies on the electromagnetic spectrum. Unlike X-rays, tpi is non-ionising - it is not energetic enough to knock electrons out of their shells, so it should be safer for medical imaging. Also, the power levels needed to build an image are lower than the background terahertz radiation we encounter everyday, says project leader Don Arnone ( New Scientist , Vol 162, No 2192).