[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Radiology](https://durgical.com/en/radiology/) › [Children](https://durgical.com/en/radiology/areas/peds/) › Imaging children: less radiation, more ultrasound

# Imaging children: less radiation, more ultrasound

- Modality

Children are more sensitive to radiation and have a long life ahead, so we use ultrasound or MRI when they answer the question and keep X-ray and CT doses low.

Updated Nov 13, 2026

## Key points

- Children have higher lifetime radiation risk: justify and optimise (ALARA).
- Ultrasound first whenever it can answer the question.
- CT protocols must be child-size; avoid multiphase scans.
- MRI: no radiation, but may need sedation.

On this page

- The basics Key points
- What it is
- Key facts
- How the image is made
- What it is good for
- Limitations and risks
- Next step
- Memory aid
- Elsewhere in DurgiPedia

- Study Test yourself

- Connections Connections

## What it is

Imaging a child is not imaging a small adult. Growing tissues are more sensitive to ionising radiation and a child has decades ahead in which a radiation-induced cancer could appear, so the lifetime risk from the same exposure is higher than in an adult. The guiding principles are justification (will the result change management?) and optimisation (ALARA: as low as reasonably achievable). In practice this means choosing ultrasound first whenever it can answer the question: children are slim, have little fat and many organs are close to the skin, so ultrasound images are often excellent. X-ray settings and CT protocols are adjusted to the child's size, the scanned area is kept as short as possible and repeat or multiphase scans are avoided. MRI has no radiation but is long, noisy and needs stillness, so young children may need sedation or general anaesthesia, which carry their own risk. Explaining the study to the child and parents, staying with them when safe and using simple immobilisation are part of a good examination.

## Key facts

- A chest X-ray gives roughly the same radiation as a few days of natural background radiation.
- A CT scan gives the equivalent of months to a few years of background radiation, depending on the area scanned.
- Comparison views of the normal side are not routine; take them only when they will change the reading.
- Lead shielding of the gonads is no longer routine in many centres because it can hide anatomy and trigger repeat exposures; follow local policy.

## How the image is made

- Ultrasound: sound waves, no radiation; small bodies and thin walls give clear images of the abdomen, hips, brain through the open fontanelle and the spinal canal in young infants.
- Radiography: low radiation; settings are set to the child's size and only the views that answer the question are taken.
- CT: much more radiation than a radiograph; child-size protocols and a tight scan range keep the exposure as low as possible.
- MRI: no radiation, excellent soft-tissue detail, but long scan times and a need to lie still; feed-and-wrap in young infants, sedation or anaesthesia in some children.
- Fluoroscopy: real-time X-ray (contrast studies, enema reduction); short screening time and the last-image-hold function reduce exposure.

## What it is good for

- Ultrasound first: intussusception, pyloric stenosis, appendicitis in many children, hip effusion and developmental dysplasia of the hip, neonatal brain.
- Radiographs: chest infections, suspected fractures, swallowed radio-opaque objects, the skeletal survey when abuse is suspected.
- CT: severe trauma, suspected intracranial bleeding, complicated infections when ultrasound and MRI cannot answer in time.
- MRI: brain and spine, tumours, bone infection and joint problems when time allows.

## Limitations and risks

- The individual risk from one well-justified study is small; the risk of missing a diagnosis is often larger. Do not refuse a needed CT out of fear.
- Adult CT protocols used on a child give a needlessly high exposure; make sure the scanner is set for paediatric patients.
- Ultrasound depends on the operator: a negative scan by an inexperienced operator does not rule out disease.
- Sedation for MRI has risks of its own (airway, breathing) and needs a trained team and monitoring.
- A frightened, moving child produces blurred images and repeat exposures; preparation and explanation save radiation.

## Next step

- Ask first whether ultrasound or MRI can answer the clinical question before ordering CT.
- Write the clinical question, age and weight on the request so the radiographer can set the right protocol.
- Check whether recent studies already exist, here or elsewhere, to avoid repeating them.
- Call the radiologist when unsure which study to order or when the child needs sedation to be imaged.

## Memory aid

Image Gently: justify, use ultrasound or MRI if they answer, and size the dose to the child.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is the lifetime cancer risk from the same CT higher in a child than in an adult?

Growing tissues are more radiosensitive and the child has many more years ahead in which a radiation-induced cancer could appear.

## What two principles govern every study that uses ionising radiation?

Justification (the result will change management) and optimisation (ALARA: as low as reasonably achievable).

## Why does ultrasound often work better in children than in adults?

Children are slim with little fat and their organs lie close to the skin, so the sound beam reaches them easily and gives clear images.

## What is the main drawback of MRI in young children?

It is long and needs stillness, so many young children need sedation or general anaesthesia, which carry their own risks.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/radiology/imaging-children-less-radiation-more-ultrasound/)

## Elsewhere in DurgiPedia

- [Pediatric history: perinatal, growth, development and vaccines](https://durgical.com/en/clinical-exam/pediatric-history-perinatal-growth-development-and-vaccines/)
- [Vital signs in children: how they change with age](https://durgical.com/en/clinical-exam/vital-signs-in-children-how-they-change-with-age/)

## Connections

## Related 8

- [Radiation in medical imaging: risk, ALARA and pregnancy](https://durgical.com/en/radiology/radiation-in-medical-imaging-risk-alara-and-pregnancy/)
- [Ultrasound: echogenicity, probes, Doppler and artefacts](https://durgical.com/en/radiology/ultrasound-echogenicity-probes-doppler-and-artefacts/)
- [The child's chest X-ray: thymus, foreign body, croup and epiglottitis](https://durgical.com/en/radiology/the-child-s-chest-x-ray-thymus-foreign-body-croup-and-epiglottitis/)
- [Fractures in children: buckle, greenstick and the growth plate (Salter–Harris)](https://durgical.com/en/radiology/fractures-in-children-buckle-greenstick-and-the-growth-plate/)
- [MRI safety: implants, metal and gadolinium](https://durgical.com/en/radiology/mri-safety-implants-metal-and-gadolinium/)
- [Imaging in suspected appendicitis](https://durgical.com/en/radiology/imaging-in-suspected-appendicitis/)
- [Choosing the right study: appropriateness and incidental findings](https://durgical.com/en/radiology/choosing-the-right-study-appropriateness-and-incidental-findings/)
- [Requesting a study and reading the report](https://durgical.com/en/radiology/requesting-a-study-and-reading-the-report/)

## Related conditions 2

- [Intussusception (children)](https://durgical.com/en/conditions/intussusception/)
- [Infantile hypertrophic pyloric stenosis](https://durgical.com/en/conditions/infantile-hypertrophic-pyloric-stenosis/)

[← All of radiology](https://durgical.com/en/radiology/)

Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.

Sources: [Radiation Safety in Medical Imaging](https://www.ncbi.nlm.nih.gov/books/NBK557499/) (StatPearls (NCBI Bookshelf), 2023); [Radiology Patient Safety and Communication](https://www.ncbi.nlm.nih.gov/books/NBK567713/) (StatPearls (NCBI Bookshelf), 2026).

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Representative model, for educational purposes only.

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