Etymology: L, classicus + Gk, tome, section, graphein, to record
a method that moves the x-ray source and the x-ray plate during an exposure to produce an image in which all but a particular plane is blurred out. This allows an approximate isolation of the image of a detail, which might otherwise be obscured by overlying or underlying structures. This technique is especially valuable in visualizing air-filled structures such as the lungs and paranasal sinuses. See also computed tomography.