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Whether your child needs an X-ray, a CT scan, an ultrasound or an MRI will depend on the child’s clinical situation. Sometimes imaging may not be necessary, so knowing your options can help you in discussions with your health professional.
Medical imaging is a useful tool to help make or confirm a diagnosis, or guide treatment decisions. However, it should only be considered if the benefits to your child are likely to outweigh the radiation risks or other potentially harmful effects.
In some cases imaging may not be needed. A diagnosis can often be made on the basis of your child’s medical history, their symptoms and a clinical examination.
For instance, plain X-ray and CT scans typically won’t help diagnose or change the treatment plan for a range of soft tissue injuries – including some common ankle and knee injuries and many cases of acute low back pain. However, imaging can be helpful if the doctor suspects a broken bone or serious joint injury that may require surgery or another intervention.
Your child’s doctor may suggest a 'wait-and-see' approach for a period of time before going ahead with an imaging test. In some cases this can avoid the need for any imaging and reduce risks like radiation. A doctor may also be able to use the results of previous imaging or other investigations to assist with a diagnosis or treatment plan.
Your child's doctor should work with you and the imaging specialist to help determine whether imaging is required and, if so, which type is most suitable.
Ask questions if you are unsure about anything. Make sure you understand the options so that you make the best decision for your child.
Imaging may also result in out-of-pocket expenses. You should ask the radiology practice beforehand whether there will be any cost to you.
Plain X-rays are often the first imaging type used when investigating a range of conditions, including certain traumatic joint and bone injuries. Depending on the results, a doctor may then request an additional type of imaging for your child, such as a CT scan, ultrasound or MRI.
CT is often the most appropriate imaging choice for investigating chest and abdomen problems – and may provide essential information that other types of imaging could miss.
A CT scan can be particularly useful for various situations managed in hospital emergency departments. However, it does involve higher doses of radiation than other types of imaging.
What you need to know about CT scans for children – this fact sheet summarises key information for parents and caregivers of children who need CT scans, including how to prepare your child for a CT scan.
In some cases, MRI can provide similar diagnostic information to CT. MRI does not use ionising radiation and so is often preferred to a CT scan for anyone under the age of 20.
While MRI avoids the risks associated with radiation, it should only be used after weighing up the risks and benefits, just the same as other types of imaging. There may be situations where a CT scan will still be preferable because of the condition suspected and the type of image required.
MRI does have some disadvantages. For example, your child may need to be sedated or undergo anaesthesia during an MRI, as the procedure can be lengthy and noisy and your child must remain motionless throughout. It can also cause some adults and children to feel anxious or claustrophobic.
Ultrasound is another imaging type that does not use ionising radiation. It can be used to examine various parts of the body including the abdomen, kidneys, muscles, bones and joints, testes, and the thyroid gland.
In some cases, ultrasound may be used instead of CT, such as when investigating possible appendicitis. But as with MRI, ultrasounds also have disadvantages that need consideration.
For example, the quality and interpretation of an image is highly dependent on the skill of the person doing the ultrasound. Sound waves used in ultrasound can't see through calcified parts of the body such as bones, which can also affect image quality. A CT scan may be more accurate in certain situations.
One of the factors to consider when choosing the type of imaging is the amount of radiation exposure to a child.
High-energy, radioactive particles or rays (known as ionising radiation) are used in plain X-ray, CT scans and nuclear medicine imaging.
CT scans use higher amounts of radiation than plain X-ray, particularly when examining the head, chest or abdomen. MRI and ultrasound use no ionising radiation.
The amount of radiation in an X-ray or CT scan is relatively small considering our constant exposure to 'background' radiation in the environment throughout our life. Because children's bodies are still developing, radiation risks are greater in children than in adults.
While an association between cancer risk and exposure to radiation from medical imaging exists, each decision to undertake a CT scan needs to be considered on its own merit. If the benefit of an imaging test exceeds its risks, then it is warranted regardless prior medical imaging radiation exposure.
This does not mean that previous medical imaging is not considered. It can be useful to your doctor, and potentially might make further imaging unnecessary. Always bring past medical imaging when you visit the doctor about related problems.
Studies on radiation and cancer have estimated that the risks are relatively small. For instance, a UK study estimated that for every 10,000 head CT scans done before the age of 10, there was 1 extra case each of leukaemia and brain tumour 10 years after the first exposure. People who had greater exposures to radiation had a higher risk.
Similar findings were reported in an Australian study investigating the risk of any cancer after a CT scan in childhood or adolescence (up to age 19).
Many parents are understandably concerned about imaging for their child. But there are steps you can take to minimise the associated risks.
Ask the imaging specialist, technologist (radiographer) or other health professional at the imaging practice how they will minimise your child’s risk from radiation exposure or other possible harms from the imaging test.
Many imaging practices have protocols and scanners that reduce or ‘child-size’ radiation doses. Some practices may, however, be more tailored to adults or may not use modern scanners or imaging techniques, so check if you’re unsure.
It’s also a good idea to check that the practice has staff trained in all aspects of imaging (including sedation or anaesthesia) and in imaging children.
Ideally, plain X-ray and CT scans should be limited to the area being examined. Protecting other parts of the body that may get exposed is important, especially those that are very susceptible to harm from radiation, such as the testes, ovaries and thyroid gland.
Your child should be covered as much as possible, but sometimes a shield can interfere with the image and won’t always be used. Don’t hesitate to ask about a shield if you’re unsure or concerned about your child’s exposure.
Ensure you are also given protective clothing (such as a gown or apron) if you are with your child during the procedure, and let imaging staff know if you are or may be pregnant.
Imaging can be stressful for children and they may have trouble keeping still. This is important because movement can blur or disrupt images, especially with MRI. Your child may also need more than one imaging test, for example, when imaging different sides of a body part.
Helping your child stay calm and still may reduce the need for sedation or anaesthesia or for a repeat test in order to get a clearer image. Distraction using toys, books, music, or movies may be helpful during some imaging procedures where these can be used.
Training scanners may be used for some children to help them prepare for procedures such as MRI. You can also arrange imaging at a time when your child is likely to be most relaxed or asleep, such as after feeding.
Children may become more stressed about imaging if they see you are anxious about it as well. In this situation, it may be best to have another parent or family member with the child during imaging.
What you need to know about CT scans for children this summarises key information for parents and caregivers of children who need a CT scan, including how to prepare your child for a CT scan.
