Kids Health Info

CT scan

  • CT stands for computed tomography, and is also sometimes called a CAT scan. The CT scanner uses X-rays to create cross-sectional images of all or a part of the body. A CT scan can be done on any area of the body.

    Why does my child need a CT scan?

    Your child may need a CT scan for many different reasons, for example, to:

    • look at the shape or structure of parts of the body (anatomy)
    • check for any signs of disease
    • help plan follow-up treatment after a procedure
    • help with planning before an operation.

    What to expect with a CT scan

    Before a CT scan

    Preparation for a CT scan depends on the body area that is being scanned.

    If your child is having an abdominal scan, they may need to drink an oral contrast one hour before the scan. This is a drink that helps the radiologist to see the stomach and intestines more clearly.

    Sometimes your child may need to have a contrast injection, which shows blood vessels more clearly and gives information about the blood supply and health of the organs in the body.

    Contrast fluid is given through a small IV (intravenous, or a drip) line, which is inserted into a vein. An anaesthetic cream can be used to reduce the discomfort of the IV needle. The cream takes at least 30 minutes to take effect. Please ask about this when making the appointment.

    Because every child is different, the radiologist may need to decide either before or immediately after the CT scan that your child needs IV or oral contrast. As a precaution, most children need to fast (have nothing to eat or drink) before the CT scan. You will be given instructions about fasting requirements.

    During the CT scan

    A CT scan is not painful. The CT scanner is a big open doughnut-shaped machine. Your child will lie down on a table, which moves through the middle of the machine at least twice during the scan. The CT scanner takes all of its pictures as the table is moving.

    Your child will need to keep very still for the pictures and sometimes hold their breath; usually this is for less than 10 seconds. Generally, the CT scan takes about 10–15 minutes in total.

    After the CT scan

    If your child has not had IV contrast, sedation or general anaesthetic, you will be able to leave straight after the CT scan.

    If IV contrast was needed, your child will be observed for 10 minutes after the CT scan. It is very rare for a child to have an allergic reaction to the contrast, but if a reaction does occur staff are well trained to manage any adverse events associated with contrast.

    A radiologist will send the report to your referring doctor, usually within a week. If the results are needed earlier your doctor can phone the radiologist.  If you have any questions about the results of your scan, speak to your doctor.

    CT scan with sedation

    If your child is unable to remain still or they are very anxious or distressed and can't be calmed down, they may need sedation before their scan. See our fact sheet Sedation for procedures.

    Whether or not your child needs sedation depends on their age and individual circumstances. Your child will be assessed to ensure that the sedation is suitable for them.

    You will be given fasting instructions to follow before the scan. After the scan, your child will be required to remain under the care of the department nurse until they have recovered properly. 

    CT scan with general anaesthetic

    Some CT scans need to be performed under a general anaesthetic. This is rare, but may be required if your child cannot use sedation.

    Your child will need to fast before the general anaesthetic; you will be given instructions about this.

    After the scan, you will need to wait until your child is fully awake and staff say it is OK to go home. Do not worry if your child feels sick or vomits once or twice after leaving hospital. If your child continues to vomit, please call your child's anaesthetist or your nearest hospital emergency department.

    Key points to remember  

    • CT scans use X-rays to create cross-sectional images of the body.
    • Some children need to take a contrast drink or have IV contrast to make parts of the body show up more clearly.
    • Your child will lie on a scanning table and has to keep very still during the procedure.
    • Sometimes, CT scans need to be performed while your child is under sedation or general anaesthetic.

    For more information

    Common questions our doctors are asked

    My child is very anxious about medical procedures and I am worried he won't stay still for the CT scan. How can I help him?

    Show him our videos of children having CT scans at The Royal Children's Hospital (RCH). It will help him to know what to expect. You can also download our Okee in Medical Imaging app, which includes games and information especially designed to help children feel more comfortable about having medical imaging done at the RCH, and includes fun training on how to keep still. To get some ideas of how to talk to your child about the scan before you come to hospital, see our fact sheet Reducing your child's discomfort during procedures.

    Are CT scans safe for children?

    CT scans do involve exposure to radiation, similar to the exposure you get from having an X-ray (though a larger amount). A CT is only performed when absolutely necessary, as determined by your child's doctor. Other than the radiation exposure, it is perfectly safe for children.

    Are there any side effects of contrast?

    In rare cases, contrast can cause reactions in children. About one child in 1000 might get a rash, hives, or an irritated mouth or throat. If this happens, your child might need to stay in the hospital a few hours longer and may need some extra medicine (e.g. antihistamines). Very rarely, your child may have a serious and life-threatening reaction and will need to be admitted to hospital for treatment.

    These are allergic reactions that cannot be predicted unless a previous reaction has been experienced. Staff can safely manage any side effects or reactions that may occur.

    Developed by The Royal Children's Hospital Medical Imaging and Day Surgery departments. We acknowledge the input of RCH consumers and carers.

    Reviewed October 2018.

    Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit

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This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital, Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.