CT scan (computerised tomography)

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

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What is a CT scan?

CT stands for "computerised tomography".  CT scans are sometimes called CAT scans. 

The CT scanner is a large doughnut shaped x-ray machine.  It is used to see internal structures of the body in great detail. The images are displayed as thin slices of the body on a computer screen (much like the slices of a sliced loaf of bread.) Your child will be exposed to some X-Ray radiation during the procedure. Please consult your doctor if you have any concerns.

Preparing your child for a CT scan

There is great benefit in taking some time to explain the CT scan to your child before coming to the scan room. Following is a list of helpful information, to discuss with your child:

  • the scan usually only takes a few minutes
  • the scan is painless
  • It is very important that the child remains still for the scan
  • parent / carer can stay with the child during the scan (unless pregnant )
  • an injection may sometimes be required
  • the scanner makes a soft fan like noise, with some clicking as the pictures are taken.
  • a breath hold will be needed for chest and abdominal scans 

Medical Preparation              

Some CT scans will require no preparation. Others may require your child to fast for 2 hours. This is in case your child needs a contrast injection, which may make your child feel queasy on a full stomach.  CT scans of the abdomen will require your child to drink an oral contrast.

If your Doctor has decided your child will need sedating or general anaesthesia in order to lie still enough for the scan, you will be given special instructions.

What is intravenous (IV) contrast?

IV contrast is a clear liquid that shows on the CT images. It is very helpful in clearly visualising the blood vessels and is very important in some CT scan examinations. The IV contrast is given via injection into a vein mostly found in the patient’s arm.

In addition you many be asked certain questions about allergies, or may be asked in some hospitals to fill in a questionnaire.

What is oral contrast?

Oral contrast is a drink your child will need to have before a CT scan of the Abdomen. It is used to tell the bowel apart from other abdominal structures that lie very close to the bowel. The oral contrast is very safe and does not require a formal consent.

Important safety considerations

Please inform the scan room staff if your child has any allergies, asthma, or kidney problems.

There is a small chance of an allergic reaction to the IV contrast. For this reason the parent/guardian will be asked to sign a consent form. Please ask any questions concerning the contrast before you sign. Also be sure to mention any known allergies.

As a parent/guardian who may be pregnant, you will not be able to stay with your child. It is advisable to bring someone else who is not pregnant to stay with your child.


  • Your child will feel more comfortable if a parent or carer can stay with them during the examination.
  • Women who are pregnant should not stay in the room while the x-rays are being taken.
The Children's Hospital at Westmead
Sydney Children's Hospital, Randwick
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