CT Scan (Computed Tomography)
What is a Computerized Tomography scan?
A computerized tomography (CT) scan is a radiological technique that creates cross-sectional images or slices of selected parts of the inside of the body using a series of X-ray beams taken from different angles.
CT scans produce a more detailed image than an X-ray which uses just one radiation beam taken at one angle. A CT scan can be used to visualize almost all parts of the body and is used by doctors to diagnose disease and injury, and to monitor patient’s treatment progress.
How is a CT scan performed?
To undergo a CT scan, you lie down on a motorized examination table which slides into a big CT scanning machine. Depending on the views needed by the doctor, you might lie on the table face down or face up. No piece of jewellery nor metallic object would be allowed on you because they may distort the image produced.
You would be told to lie as still as possible to ensure the images produced are clear and undistorted. Although the radiographer performing the scanning would be in a different room, communication with you is ensured using the intercom.
If you are a child, your parent is asked to stay nearby to allay your anxiety. However the parent will have to wear a lead apron to prevent exposure to radiation.
How it works
As your body moves through the CT machine, the scanner emits a series of narrow radiation beams through the parts of your body. The X-ray beams course through different parts of the body with different densities and the information is transmitted to a computer which, in turn, creates a 3-D cross-sectional picture of that part of the body.
For special images, you may need to drink a contrast material or dye or have it injected into your blood vessels, or passed through your rectum to enhance the images of these respective parts. This form of CT scan is called a Contrast CT scan.
Why is a CT scan done?
The ability of a CT scan to give clear and detailed images of body structures makes it the preferred way of diagnosing cancer. The images from a CT scan can reveal the exact location of a tumour, its size, and extent of damage done to tissues around it.
A CT scan is also used to diagnose disease of muscle and bone such as fractures and tumours. A CT scan is also effective at detecting internal injuries and internal bleeding.
What Risks are associated with a CT scan?
Although with CT scanning, there is an exposure to ionizing radiation more than what is emitted by a plain X-ray, the radiation is not sufficient enough to cause any adverse effects. Generally, the benefits of a CT scan outweigh its detriments. Moreover, there are newer and faster CT scanning machines that use much less radiation than previous ones.
For contrast CT scanning, you might develop allergic reactions to the contrast material. This reaction may range from mild to life-threatening.
Furthermore, since exposure to radiation may cause certain problems in a foetus, CT scan is not recommended for pregnant women.