A new scanner using T-rays, a form of electromagnetic radiation believed to be harmless is being developed by the US Department of Energy in conjunction with researchers in Turkey and Japan.
The T-rays – terahertz radiation – are produced using special, high-temperature superconducting crystals in a compact device. T-rays are part of the electromagnetic spectrum that lies between microwaves on the low end and infrared radiation at the high end.
Unlike conventional X-rays, which can cause cell damage, T-rays do not have enough energy to damage skin cells, but is effective at penetrating many common materials like leather, fabric, cardboard, and paper and are sensitive to characteristics of many types of chemicals. They cannot, however penetrate through metals or water.