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CT Scan – Patient Information

This page contains information for a CT scan. Please contact us with any further questions prior to your examination.

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What is a CT scan?

CT (computerised tomography) uses X-rays to create cross sectional images of the body. The images obtained in CT are more detailed than X-ray images and they show soft tissue, blood vessels and bone.

What are the benefits of a CT scan?

The CT scanner looks like a large doughnut, but it is not enclosed. You will be lying flat on a motorised couch and it will move into the centre of the scanner until the body part that is being scanned is within the ring. The X-ray machine sends thin beams of X-rays through the body which are picked up by X-ray detectors.

During the scan, you may be asked to breathe in and hold your breath for a few moments; this will prevent blurring whilst the pictures are being taken.

The radiographer performing your scan will position you, explain the procedure and answer any questions you may have. Once the radiographer has positioned you they will leave the room but you can communicate with them through an intercom and they can see you through a glass window.

For certain body parts, you may need to be given a contrast dye injection as part of the scan. The dye may give you a “metallic taste” at the back of the tongue, a “hot flush” and a warm sensation in your bladder that may make you feel like you are passing water (wet yourself) – you won’t, it’s just a sensation. This sensation should pass in a few minutes.

Once the scan is finished, the radiographer will briefly check to make sure the images are good quality. The radiographer will usually not be able to give you any results on the day of the scan but they will be can reassure you that appropriate images have been obtained.

How long will the scan take?

Typically it will take 10-20 mins depending on which body part is being scanned. We will try and keep to your appointment time but if we are delayed we will let you know.

Why should I have a CT scan?

Your doctor has decided that this is the best option to find the cause of your problem and help direct you to the best treatment.

Are there any alternatives?

Your doctor feels that a CT scan is the best option for you. Other tests may not provide the same level of detail.

Asking for your consent

The radiographer will ask you if you are happy for the scan to go ahead (verbal consent) and may only involve the radiographer checking that you are booked for the correct scan. If you do not wish to have the scan or are undecided, please tell the radiographer. It is your decision and you can change your mind at any time. Please remember to ask the radiographer any questions you have at any time.

Are there any risks?

CT scans use radiation, the same as X-rays but the radiation used is very small and the benefits outweigh the risks. Anyone of child bearing age (12-55 years old) will need to confirm that there is no possibility of pregnancy, due to the radiation exposure during the examination.

There is a very small chance that patients may have an allergic reaction to the contrast dye (as it contains iodine) if given. The radiographer will check if you have had previous reactions.

There is a small risk that the injection of contrast can leak out under the skin instead of in the vein. If this happens then further advice will be given by the radiographer.

If you think you may have had an allergic reaction to CT contrast in the past or you think you might be pregnant, please inform your doctor or email

How do I prepare for the scan?

In many cases you do not need to do anything to prepare. If you need a contrast injection we may ask you to fast for 4-6 hours. If you are taking any medication, please continue to. If we do need you to prepare, we will explain this when we confirm your appointment.

When will I get the results?

The results will be sent to your referring doctor. Our reporting turnaround time is five working days, but 90% of reports reach the consultant within 24hrs.

Contact us

Please contact the Imaging team about any general concerns on 0207 467 4317. However, if you experience any symptoms of concern please contact your GP or go to your local Emergency Department (A&E).

Your comments and concerns

If you have any questions or concerns about your medicines, please speak to the staff caring for you. For support or advice please speak to your consultant or the Imaging department on 0207 467 4317.

Language and accessible support services

If you need an interpreter or information about your care in a different language or format, please get in touch.

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