A CT scan (or cat scan) is an abbreviation of Computerised Tomography. CT scans show cross sectional images of soft tissues (muscles, tendons, ligaments, cartilage etc) as well as bone and calcific deposits.
What is a CT scan?
A CT scanner is a special type of X-ray which uses multiple beams, rather than just the singular one seen in X-rays. The scanner rotates around the patient to give a clearer view of what is happening internally. The beam passes through the body part being scanned and the strength of the beam on the other side is measured. In dense tissue such as bone, the strength of the beam received is less and so it appears white on the film. Less tense tissue (soft tissues) appear less clearly, as a pale shadow.
CT scans are far more detailed than X-rays. Whilst a 2D image is produced by older machines, newer technology has allowed for 3D images.
What is a CT Scan used for?
CT scanners were originally used for imaging the brain, but now they are used for just about any part of the body. They are especially good at picking up tumors, bleeding in the brain, aneurysms, lung disease and internal injuries such as lacerations of the kidneys or spleen.
They are also used for bony injuries, especially in the spine. You may be offered a CT scan for suspected small fractures in complex regions such as the ankle, foot or pelvis.
What happens during a scan?
If the scan is of the abdomen, you may be asked not to eat anything for 6 hours. You may also be given a special drink which contains an X-ray dye to help make your intestines clearer on the scan. For other areas, you may be injected with a dye.
The CT scanner looks like a round tunnel. The patient (or just the body part being scanned) is moved backwards and forwards within the tunnel, until all necessary pictures and angles are taken.
Whilst a CT scan is safe and the patient is not at any risk, the multiple X-rays and so exposure to radiation, mean that a CT scan should only be requested for good reason and should not be undertaken repeatedly.