Children are more sensitive to radiation than adults, so imaging is chosen and dosed carefully. Where they can answer the question, radiation-free scans (ultrasound and MRI) are preferred. When X-ray or CT is needed, the dose is scaled down to the child's size, and modern scanners reduce it further. The benefit of the right diagnosis is weighed against a very small risk.
Key takeaways
- Children are more sensitive to radiation, so tests are chosen with extra care.
- Ultrasound and MRI (no radiation) are preferred where they can answer the question.
- When X-ray or CT is needed, the dose is scaled to the child's size.
- Modern CT scanners can significantly reduce a child's dose.
Children are more sensitive to ionising radiation than adults — their tissues are growing and dividing more rapidly, and they have longer lives ahead in which any effect could appear.[2] For that reason, imaging in children is chosen and dosed with particular care.
Radiation-free first
Wherever a radiation-free scan can answer the question, it’s preferred. Ultrasound is often ideal for children — quick, painless and radiation-free. MRI also uses no radiation, and children can usually be scanned without sedation from about age 6–7; younger children may need sedation to stay still.[2][3]
When X-ray or CT is needed
Sometimes an X-ray or CT genuinely gives the best answer — for example after an injury. When that’s the case:[1]
- The radiation dose is scaled down to the child’s body size — smaller bodies need less radiation to make the image.
- Modern CT scanners can significantly reduce the dose for small patients; it’s important a modern scanner is used and the settings adjusted for children.
- Only the area that needs to be scanned is exposed.
The very small risk is weighed against the real benefit of getting the right diagnosis quickly. (Doses for children vary a lot with size, so figures for adults don’t apply directly.)[1]
Helping your child through a scan
A calm, prepared child copes better. Explaining in simple terms what will happen, and that it won’t hurt (for X-ray, CT, ultrasound and MRI), helps a lot. For MRI, the scanner is noisy and enclosed, so older children are told about the sounds in advance; headphones or a movie, and sedation if needed, are available.[3]
Frequently asked questions
Is a CT scan safe for my child?
A CT uses radiation, so it’s used when it’s the best test for the problem. The dose is scaled to your child’s size and kept as low as possible, and the benefit of the diagnosis is weighed against a very small risk. Where a radiation-free test will do, it’s preferred.[1]
Will my child need sedation for an MRI?
Often not from about age 6–7, when many children can stay still for the scan. Younger children may need sedation; the department will advise.[3]
Are children’s scans read differently?
Yes — many are interpreted by radiologists with paediatric experience, since children’s anatomy and conditions differ from adults’. Larger centres often have dedicated paediatric imaging.[2]
Sources
- RadiologyInfo.org (RSNA & ACR) — Radiation Dose (pediatric note) — www.radiologyinfo.org/en/info/safety-xray
- RANZCR / InsideRadiology — Radiation risk of medical imaging — www.insideradiology.com.au/radiation-risk/
- RANZCR / InsideRadiology — Magnetic resonance imaging (MRI) — www.insideradiology.com.au/mri-hp/
