The system, built by Boston company Perceptive, uses a hand-held 3D volumetric scanner, which builds a detailed 3D model of the mouth, including the teeth, gums and even nerves under the tooth surface, using optical coherence tomography, or OCT...This cuts harmful X-Ray radiation out of the process, as OCT uses nothing more than light beams to build its volumetric models, which come out at high resolution, with cavities automatically detected at an accuracy rate around 90%.