When a full slice is completed, the image is stored and the motorized bed is moved forward incrementally into the gantry. The thickness of the tissue represented in each image slice can vary depending on the CT machine used, but usually ranges from 1-10 millimeters. As the x-rays leave the patient, they are picked up by the detectors and transmitted to a computer.Įach time the x-ray source completes one full rotation, the CT computer uses sophisticated mathematical techniques to construct a two-dimensional image slice of the patient. Instead of film, CT scanners use special digital x-ray detectors, which are located directly opposite the x-ray source. During a CT scan, the patient lies on a bed that slowly moves through the gantry while the x-ray tube rotates around the patient, shooting narrow beams of x-rays through the body.
Unlike a conventional x-ray-which uses a fixed x-ray tube-a CT scanner uses a motorized x-ray source that rotates around the circular opening of a donut-shaped structure called a gantry.
