Having a Computerised Tomography (CT) scan

Your doctor has arranged for you to have a CT scan at The Clatterbridge Cancer Centre and this leaflet will explain the following:

  • What is a Computerised Tomography (CT) scan?
  • Why do I need a CT scan?
  • How do we share your images?
  • Can I bring a relative or friend?
  • What clothing should I wear?
  • Can I take my prescribed medications as usual?
  • Are there any risks?
  • What is the preparation for a CT scan?
  • What happens at the hospital before the scan?
  • Will I need an injection?
  • What happens during the scan?
  • What happens after the scan?
  • When will I get the results?

Urgent alert

Please contact Radiology on 0151 556 5052:

  • If you are or think you might be pregnant or are breastfeeding
  • If you weigh more than 225kg or 35 stone
  • If you have any questions please do not hesitate to contact the department on the above number

It is a type of scan that uses x-rays to obtain detailed images of the body in ‘slice sections’ (cross sections). These images are examined by a Radiologist (a doctor who specialises in reading x-ray images) which can be used for diagnosing and assessing medical conditions.  

The CT scanner is an open ring-like structure which resembles a giant doughnut (as shown in the picture), rather than a tunnel. The CT table is relatively comfortable and the noise levels from the equipment are low.

Diagnostic Radiographers will perform your CT scan and Imaging Assistants will assist during your visit.

A CT scan helps your doctor to diagnose and assess your condition and to assess your progress during and after treatment.

Radiographer in burgundy scrubs sitting at desk with control panel and displays from CT scanner

The Clatterbridge Cancer Centre works closely with other organisations for support with patient care. This may mean that your images may be shared with other Trusts.  

Anonymised patient information and images are used for training, teaching and research purposes within this Trust, which is committed to the continuing professional development of staff and to protecting the privacy and confidentiality of its patients.

If you would prefer not to have your images used for these purposes, please notify the staff member performing the examination. This will not have any detrimental impact on the level of care you are provided.

Yes, but try and limit it to one person due to space limitations in the waiting room. Please do not bring a dependant (such as a child), as there will not be staff available to look after them.

For reasons of safety they will not be allowed to accompany you into the CT scan room.

If you wish to wear loose-fitting clothing with no metal zips, buttons or bra clips, we would try and perform the scan without you needing to get changed. If this is not possible you may be asked to change into a hospital gown. Alternatively we may ask you to move clothing with any metal out of the area we are scanning, but will ensure that you are covered up. 

Yes, you can take all your usual medicines.

The examination involves exposure to x-rays – a scan can be thought of as many individual x-rays taken at speed around the body and images processed by special IT systems – and the amount of ionising radiation is kept to a minimum by sophisticated dose controls on the scanner. 

Every patient’s case will have been reviewed individually to ensure that the net benefits (i.e. diagnostic information) outweigh the risks.

CT radiation doses at The Clatterbridge Cancer Centre are similar to background ionising radiation that we are all exposed to over 1-5 years, depending on the scan type and body part.

The contrast injection you may have contains iodine, which can cause an allergic reaction in a few people. You should tell the Radiographers if you have had an allergic reaction to iodine or contrast dye in the past or if you have any other allergies.

Rarely, for those who have an injection, the contrast can leak outside the vein and cause temporary swelling and discomfort in the arm. This is unlikely to happen but if it does we will give you further instructions and advice on the day of your scan.

If your scan includes the liver and/or abdomen, please do not eat for four hours prior to your scan, but you can drink normally. This will be detailed on your appointment letter.

Diabetic patients can eat very light food, such as clear soup, if necessary, before attending.

If you are having a scan for a different area, such as your head, you can eat and drink normally.

If you are having a CT scan of your head, there is a possibility that you may not be able to drive home, so please bring someone with you who can drive.

Your appointment letter will give your appointment time (the time you should attend the Radiology Department). The length of time you will be on the scanner depends on the area of the body you are having scanned, but it is usually between 10 and 20 minutes.  

For scans which include your abdomen and/or pelvis you will need to be in the department longer than this as you may need to have water before the scan which you will need to drink over 15 or 30 minutes. You will be given instructions for this on the day of your scan.

However, you may be in the department longer if we need to see emergency patients. We will do our best to keep you informed of any delays.

When you arrive in the department you will be greeted by the reception staff.  

If you are having a scan to include your abdomen and/or pelvis, you may need to have water before the scan which you will need to drink over 15 or 30 minutes and you will be given instructions for this on the day.

You are likely to require an injection of a contrast (x-ray dye) which is placed into a vein in the arm by inserting a cannula or ‘tube’ which is usually done in a cannulation room before you go into the scan room. This contrast highlights the blood vessels and body organs more clearly on the x-ray images.

If you have a PICC or Portacath in your arm, we will use this if we can, and you will not need to have a cannula in your arm.

If you need to have an injection we will ask you about any medical history of diabetes, asthma or kidney problems and questions about allergies. There are quite a lot of questions we need to ask which are to make sure it is safe for you to have the contrast.

CT scanner couch staff and patient.jpgIn the scan room the Radiographers will explain the CT scan to you and what to expect. You can ask any questions you may have.

You will be asked to lie on the scanner table and staff will make you as comfortable as possible at all times. If there is metal on part of your clothing which we can move out of the area you are having scanned, the Radiographer will do this and cover this area.  
If you require an injection, the Radiographer will attach the line from the contrast injector to your cannula, PICC or Port. 

We will ask you to put your arms on a rest above your head (if you are able) and we will do a test injection (of saline) with your arms in the position we will be doing your scan. Let staff know if you feel pain in your arm when we do this test injection.

We will also tell you what to expect during the injection of contrast: generally a metallic taste in the mouth, a warm sensation throughout the body and some patients experience a sensation that they want to pass water (you won’t), both which last about 30 seconds.

Staff will then leave the room, but they can see and hear you at all times via a connecting window and intercom.

The scanning table will move you slowly through the scanner and you may be asked to hold your breath, only for a few seconds, as it takes the images. We understand that some people have difficulty holding their breath – please tell us at the time if this is a problem for you.  

The scanner will make a noise but it will not touch you and you will not feel anything (except what is mentioned above if you have the injection).

The Radiographer will let you know when the table is about to move and when the injection will start. Please let staff know if you experience any discomfort in your arm during the injection.

Once the CT scan is finished, the Radiographer will check the images for diagnostic quality before you leave the room.

If you have not had an injection of the CT contrast, you will be able to go home immediately after your scan. 

If you have had an injection of contrast you will be asked to slightly increase your fluid intake for the next couple of days (to help ‘flush’ the injection out of your system).

We will then ask you to wait in the waiting room with the cannula still in your arm for about 30 minutes after the injection and give you an information slip about what the injection is and what to look out for if you don’t feel well (if this happens, tell a member of staff straight away). It will also give you the time that we should remove your cannula.

Once the cannula has been removed you can go home as the CT scan itself has no side-effects, so you will not feel any different. However, driving is NOT recommended for at least ONE HOUR after the injection, so it is important to consider this when organising your transport to the hospital. 

CT radiologist reporting.jpgAfter you leave the department, a Radiologist will look at the CT images and write a report.  

Your hospital consultant or doctor from Outpatients should have the report available at your next outpatient appointment.  

If you don’t have another outpatient appointment and do not hear anything about the results within three weeks, we suggest you telephone your Consultant’s secretary for advice letting them know when you had your scan.

For general information you can contact the Cancer Information and Support team:

Please note that we scan patients who have been referred for investigation for a range of conditions, not only for cancer.

Find more information about CT scans from Macmillan Cancer Support.