A computed tomography (CT) scan, also known as a computed/computerized axial tomography (CAT) scan, is an advanced medical imaging method that combines X-ray and computer technology to create detailed, cross-sectional pictures of the body. During a CT scan, multiple images are taken, resulting in a higher level of radiation exposure than a single X-ray. However, unlike a two-dimensional X-ray, CT offers a sometimes necessary three-dimensional view inside the body.
How is a CT scan performed?
You will be asked to lie on a narrow table that slides into the center of the CT scanner. Depending on the study being done, you may need to lie on your stomach, back or side.
Once inside the scanner, the machine’s X-ray beam rotates around you. With newer “spiral” scanners, the exam can be performed in one continuous motion.
Small detectors inside the scanner measure the amount of X-rays that make it through the part of the body being studied. Then, a computer processes this information to create several individual images, called slices. For a more detailed look inside the body, the individual slices can be stacked together to create three-dimensional models of organs.
During the exam you must be still, and you may be told to hold your breath for short periods of time, because movement can cause blurred images. Generally, complete scans take only a few minutes, while the newest multi-detector scanners can image your entire body, head to toe, in less than 30 seconds.
Why is the test performed?
CT is often used to:
- Evaluate the brain after an accident or internal hemorrhaging
- Evaluate complex fractures, especially around joints
- Detect changes in the lungs
- Diagnose muscle and bone disorders, such as bone tumors and fractures
- Pinpoint the location of a tumor, infection or blood clot
- Guide procedures such as surgery or biopsy
- Detect and determine states of diseases, such as cancer
- Detect internal injuries and internal bleeding
- Diagnose abdominal disease
- Diagnose sinus disease and look for narrowing or obstruction in the sinus drainage pathway