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Information for patients who are having a CT scan

Patient information A-Z

This information is for all patients undergoing CT examinations

A CT scanner uses x-rays to obtain images which will help the doctors plan your future treatment. The CT room is spacious. You will be lying on a couch which moves through a large hole in the middle of the scanner. Most of the time you can see out of either one side or the other, and the radiographer will be able to speak to you via an intercom.

It is important to tell us if:

  • you are pregnant
  • you are claustrophobic
  • you have kidney problems
  • you are unable to lie flat
  • you weigh 125kg or more
  • are difficult to cannulate

Preparing for your scan

  • Eat and drink normally before and after your scan unless the appointment letter gives you specific instructions.
  • You may be asked to arrive up to an hour before the scan to allow time for you to drink fluid if you are having a oral contrast test.
  • Take all prescribed medications on the day of your scan as usual, unless otherwise instructed on your appointment letter.
  • Let us know in advance if you need additional assistance because of mobility issues.

What will happen on the day of the scan?

  • This will depend on what type of scan you are having. A radiographer will explain the procedure to you before your scan.
  • Many CT examinations involve having a dye injection (contrast) to increase the quality of information obtained from the scan.
  • A small cannula may be inserted into a vein in your arm. Contrast will be injected through this. It contains iodine and is not radioactive.
  • The injection usually causes nothing more than a warm feeling passing around your body.
  • Most scans last 15 to 20 minutes.
  • You may be given breathing instructions to follow during your scan.

How long will I be in the department?

This will depend on what type of scan you are having but expect to be with us between one and two hours. This includes preparation, explanation, scan and post-scan procedures. The CT department is located on Level 2 (ground floor) in the outpatient department near oncology.

What happens after my scan?

  • Most people will be free to go home.
  • You may eat and drink as normal.
  • Continue to drink plenty of fluids for the remainder of the day, especially if you have been given an injection.

Can I bring someone with me?

You can bring a relative or friend but they will have to wait in the waiting room during the scan.


CT scans can give doctors information to help them diagnose a variety of conditions. The scans can help to confirm or rule out a suspected diagnosis, or occasionally identify a condition that was not even suspected.

Unlike other imaging methods, a CT scan can give a detailed view of lots of different tissue types in the body, including lungs, bones, soft tissues and blood vessels.


  • The scan involves exposure to radiation in the form of x-rays. However, the amount you are exposed to during the scan is very small.
  • If you have an injection you may get a warm flush feeling, a sensation of ‘passing water’, and a metallic taste in your mouth.
  • Very rarely there may be bruising at the site of the injection.

When will I get my results?

  • The radiographer will check that all the images have been obtained but will not be able to give you the result at that time.
  • The radiologist will report on the scan and send a detailed result to the doctor who referred you.
  • The results will then be discussed with you at your next clinic appointment.


Thanks to the Royal College of Radiologists and NHS Choices.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151