CT scan
When CT scans are used
CT scans can produce detailed images of many structures inside the body, including the internal organs, blood vessels and bones.
They can be used to:
- diagnose conditions – including damage to bones, injuries to internal organs, problems with blood flow, strokes and cancer
- guide further tests or treatments – for example, CT scans can help to determine the location, size and shape of a tumour before having radiotherapy, or allow a doctor to take a needle biopsy (where a small tissue sample is removed using a needle) or drain an abscess
- monitor conditions – including checking the size of tumours during and after cancer treatment
CT scans wouldn't normally be used to check for problems if you don't have any symptoms (known as screening). This is because the benefits of screening may not outweigh the risks, particularly if it leads to unnecessary testing and anxiety.
Medically Reviewed by a doctor on 21 Dec 2018
Introduction
A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body.  CT scans are sometimes referred to as CAT scans or computed tomography scans.
When CT scans are used
CT scans can produce detailed images of many structures inside the body, including the internal organs, blood vessels and bones. They can be used to: diagnose conditions – including damage
Preparing for a CT scan
Your appointment letter will mention anything you need to do to prepare for your scan. You may be advised to avoid eating anything for several hours before your appointment, to help ensure t
Before having a CT scan
Before having the scan, you may be given a special dye called a contrast to help improve the quality of the images. This may be swallowed in the form of a drink, passed into your bottom
What happens during a CT scan
During the scan, you'll usually lie on your back on a flat bed that passes into the CT scanner. The scanner consists of a ring that rotates around a small section of your body as you pass th
What happens afterwards
You shouldn't experience any after effects from a CT scan and can usually go home soon afterwards. You can eat and drink, go to work and drive as normal. If a contrast was used, you may be a
Are CT scans safe?
CT scans are quick, painless and generally safe. However, there's a small risk you could have an allergic reaction to the contrast dye used and you will be exposed to X-ray radiation. T
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