Terahertz radiation, or T-rays,occur at a frequency of around a trillion hertz, between microwaves andinfrared on the electromagnetic spectrum. Unlike X-rays, T-rays arenonionizing, so they don't carry a cancer risk. They can penetrateclothing, packaging and a few millimeters into the human body, makingthem ideal for security screening and medical applications such asskin-cancer and tooth-cavity detection. Until now, they've beendifficult to generate, but Harvard researchers recently filed for apatent on the first room-temperature source of coherent T-rays, andscientists at Argonne National Laboratory are developing a portableT-ray generator. Lower-resolution passive detection systems that pickup natural T-ray emissions are already on the market: The Wayne CountySheriff's Office, in Detroit, is testing a scanner built by Britishcompany ThruVision to screen anyone entering its criminal courts.

Source: popularmechanics.comAdded: 19 December 2008