CBCT is the abbreviation of Cone beam CT, i.e. Cone beam CT, as the name suggests, is a cone beam projection computerized reconstructive tomography (CT) imaging equipment, which is based on the principle that the X-ray generator makes circular DR (digital projection) around the projector with a low amount of rays (usually the bulb current is about 10 mA). Then the data obtained in the "intersection" after digital projection around the projector for many times (180 times-360 times, depending on the product) are "reconstructed" in the computer to obtain three-dimensional images. The principle of CBCT data acquisition and traditional sector scanning CT is completely different, while the principle of the algorithm of the later computer reconstruction is similar.