The same imaging technology used at airport security checkpoints could also help us find melanomas that we can't see yet, according to research presented at the American Chemical Society's fall 2013 meeting. The technology uses terahertz rays (T-rays), which are the wavelengths between microwaves and the infrared rays that we feel as heat. In contrast to X-rays, T-rays are not ionizing and so are much safer, penetrating only a few millimeters into the skin. Melanomas start in the deepest part of the skin's outer layer, long before they appear on the surface as mole-like growths. Early results suggest that dermatologists could use T-rays to diagnose melanomas that are just beginning to form.