A scan that uses X-ray and a computer to create detailed images of inside your body.
What is a CT scan?
A computed tomography (CT) scan uses X-ray and computer software to create detailed images of inside your body. It is sometimes also known as a CAT scan.
CT scans are used to diagnose and monitor many different conditions, including cancer, damage to bones and stroke.
A CT scanner is a ring-shaped machine that produces a fan-shaped beam of X-rays. The tube rotates around your body as you lie flat, creating images that are cross sections of your body. The computer joins the images together to create a 3-D view of inside your body.
How is a CT scan carried out?
Your scan will be carried out by a radiographer, a health professional trained to do imaging procedures. They'll explain what will happen and answer any questions you may have.
You may need to have an injection of a special dye called contrast medium. This helps to show up certain organs or blood vessels more clearly. The contrast is injected into a vein, usually in your hand or arm. This can cause a warm, flushing feeling but this passes quickly.
During the scan, you'll lie on a table that moves backwards or forwards slowly.
The radiographer may ask you to breathe in, breathe out and/or hold your breath during the scan. For the rest of the time, you must lie very still.
You'll be in the scanner for between 5 and 15 minutes.
How to prepare for your CT scan
If you need to do anything to prepare, you'll be told when your appointment is made. You should continue to take any prescribed medication as usual.
If you get claustrophobic, make sure you let your doctor or radiographer know beforehand. We'll do everything we can to make you as comfortable as possible during the scan. You may be able to have a sedative to help you relax if necessary.
Depending on the area of your body being scanned, you may need to change into a hospital gown and remove jewellery, piercings, hair accessories, hearing aids, watches and dentures.
What happens after your CT scan?
You can go home after your scan when you feel ready. If you've been injected with a contrast medium, you should wait at least 15 minutes before leaving the department.
A radiologist will look at your scans and write a report. This will be sent to the doctor who referred you for the scan, usually within 24 to 48 hours. They will discuss the results with you at your next appointment.
What are the alternatives?
Your consultant will explain your options and let you know which procedure is most suitable for you.
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