Imaging
CT Scan
A CT scan uses X-rays and a computer to build detailed cross-section images of the body. It is fast and excellent for injuries, bleeding and many internal problems.
Quick answer
CT Scan: what it is and what the results mean
A computed tomography (CT) scan takes many X-ray images from different angles and combines them into detailed "slice" pictures of the inside of the body.
- Why it is done: CT scans are used in emergencies (such as suspected stroke, serious injury or internal bleeding) and to investigate the chest, abdomen and many organs, and to look for and monitor cancers.
- Understanding results: A radiologist reviews the detailed images and reports to your doctor.
What it is
A computed tomography (CT) scan takes many X-ray images from different angles and combines them into detailed "slice" pictures of the inside of the body.
Why it is done
CT scans are used in emergencies (such as suspected stroke, serious injury or internal bleeding) and to investigate the chest, abdomen and many organs, and to look for and monitor cancers.
What to expect
You lie on a table that moves through a large ring-shaped scanner. It is painless and usually takes a few minutes. Sometimes a "contrast dye" is given by injection or drink to show certain structures more clearly.
Understanding the results
A radiologist reviews the detailed images and reports to your doctor. CT is quick and shows bones, blood vessels and soft tissues well.
Good to know
Risks and limitations
A CT scan uses more radiation than a plain X-ray, so it is used when the benefit justifies it. Contrast dye is usually safe but occasionally causes reactions. Tell staff if you are or might be pregnant, or have kidney problems or allergies.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
CT Scan: frequently asked questions
What is the difference between a CT and an MRI scan?
A CT scan uses X-rays and is fast, making it ideal in emergencies; an MRI uses magnets and radio waves (no radiation) and shows soft tissues in great detail but takes longer. The choice depends on what is being looked at.
Is a CT scan safe?
CT scans use more radiation than plain X-rays but are used when the information they give clearly outweighs the small risk. Tell staff if you could be pregnant.
Related tests
Other imaging investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Royal College of Radiologists / relevant professional body
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