How Does the Computed Tomography Scan Work?

X-rays are rays of electromagnetic radiation. During a CT body scan, the patient lies still on a table. The table is rolled into a CT scanner, the machine that creates the CT images. The CT scanner contains a gantry, a rotating frame that contains the x-ray tubes, x-ray detectors, and a large opening into which the patient can be inserted. During the CT scan, the gantry rotates, and the x-ray tube moves around the patient's body to produce the required images.

One rotation takes about one second. Several x-ray beams pass through the body at various angles. As the beams pass through, different tissues absorb different amounts of radiation. Special sensors measure the amount of radiation absorbed by different tissues. The data is then sent to a special computer, which uses the “snapshots” to form three-dimensional cross-sectional images of the scanned areas. These cross-sections are called tomograms.

The patient is alone in the room throughout the procedure; however, an x-ray technologist will monitor the whole procedure. An intercom inside the scanner allows the patient and the technologist to communicate throughout the CT body scan.