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 your child stays still for the scan
  • parent / carer can stay with the child during the scan (unless pregnant )
  • an injection may sometimes be needed
  • the scanner makes a soft fan like noise, with some clicking as the pictures are taken.
  • your child maybe asked to hold their breath for a few seconds if they are having chest and abdominal scans

Medical preparation                       

The way your child needs to prepare for the scan will vary depending on what type of scan you are having. Your child:

  • may not need to do anything to prepare for their CT scan.
  • may need to fast for 2 hours before their scan if they are having a contrast injection. This can make your child feel queasy on a full stomach. 
  • may need to drink an oral contrast if they are having a CT scan of the abdomen.
  • may need sedation or general anaesthesia so they lie still enough for the scan. If your doctor has decided that your child needs this, 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 organs in the body and is very important in some CT scan examinations. A cannula may be required as the IV contrast is given via injection into a vein mostly found in the patient’s arm.

If a cannula is required a topical anaesthetic or numbing cream can be applied to make the arm or hand numb. This cream takes about 30minutes to work so you will need to arrive 30minutes early for your appointment if this is required.

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 need a formal consent. 

Important safety considerations

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 about the contrast before you sign.

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

Patients who have had IV contrast will be required to wait in the department for 15 minutes following the scan to ensure that no allergic reaction occurs.


Your child will feel more comfortable if a parent or carer can stay with them during the examination.

If you are or 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.

Women who are pregnant should not stay in the room while the scans is being done. 

The Children's Hospital at Westmead
Sydney Children's Hospital, Randwick
Hunter New England Kids Health

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