Paediatric Imaging Referrals: A Guide for GPs

Children are not small adults when it comes to imaging. Their tissues are more radiosensitive, they have more years of life ahead in which a radiation-induced malignancy could develop, and the same scanner settings deliver a relatively higher effective dose to a smaller body.

This underpins the ALARA principle - As Low As Reasonably Achievable - and international campaigns such as Image Gently, which promote child-specific protocols and the substitution of non-ionising modalities wherever diagnostically adequate.

For the referring GP, the practical translation is a consistent hierarchy: prefer ultrasound and MRI where they can answer the question; use X-ray judiciously; and reserve CT for situations where it genuinely changes management and no radiation-free alternative suffices. None of this means withholding necessary imaging - an indicated CT should never be delayed by dose anxiety - but it does mean pausing on the modality choice before writing the referral.

Ultrasound is the workhorse of paediatric imaging: no radiation, no sedation, and generally well tolerated. Children are also excellent ultrasound subjects - less overlying tissue means better image quality than in many adults.

Common presentations where ultrasound is an appropriate first-line request include:

• Abdominal pain - including suspected appendicitis, where ultrasound is the recommended initial study in children, and suspected intussusception in infants • Pyloric stenosis in vomiting infants • Scrotal pain and swelling - noting that suspected torsion is a surgical emergency where imaging must not delay referral • Neck lumps and lymphadenopathy • Hip effusion in the limping child (alongside X-ray where indicated) • Developmental dysplasia of the hip screening in young infants • Renal tract assessment after urinary tract infection, where guidelines recommend it

If ultrasound is inconclusive, it can be followed by targeted MRI or, where justified, CT - often with the question considerably narrowed.

CT remains irreplaceable in specific paediatric scenarios, and an indicated CT should be requested without hesitation:

• Significant head trauma meeting clinical decision-rule criteria - validated tools such as PECARN help identify which children need CT and which can be safely observed • Major trauma assessment • Suspected complex bony injury where X-ray is insufficient for surgical planning • Some chest and airway indications where MRI is impractical

Two practical points. First, most of these presentations belong in an emergency department rather than a community radiology clinic - if you are considering CT for head trauma, the child usually needs ED assessment, not an outpatient referral. Second, when community CT is appropriate, note the child's age and weight on the referral; paediatric dose-reduction protocols depend on it, and clinics experienced with children will tailor the acquisition accordingly.

MRI is radiation-free and superb for neurological, musculoskeletal and abdominal questions in children - but it demands stillness in a noisy, confined scanner for 20 to 60 minutes, which is beyond many young children.

As a rough guide, children over about six or seven can often manage an awake MRI with good preparation, particularly with child-friendly measures such as watching a movie in the scanner, a parent in the room, and a practised, unhurried radiography team. Younger children, and older children with anxiety, autism or developmental differences, may need sedation or a general anaesthetic - which typically means referral to a paediatric centre or a facility with paediatric anaesthetic support, and a longer wait.

Before referring, it is worth asking the family how the child manages confined spaces and lying still, flagging any likely need for sedation on the referral, and considering whether feed-and-wrap techniques (for young infants) or a mock-scanner preparation program is available locally.

A prepared family markedly improves the chance of a successful scan and reduces repeat appointments:

• Explain the test in concrete, child-appropriate terms - what the room looks like, the sounds the machine makes, how long it takes • Encourage parents to be honest rather than dismissive - "it's noisy but it doesn't hurt" works better than "it's nothing" • For MRI, mention the noise and the need to stay still; many clinics allow a parent to stay in the room • For ultrasound, note any fasting or full-bladder requirements the clinic specifies • Suggest bringing a comfort item, and booking at a time of day when the child is usually settled • Direct families to resources - our guide on preparing your child for a scan is written for parents and covers each modality

A sentence on the referral such as "first imaging experience, anxious child" prompts clinics to allow extra time.

Not every community radiology practice images children regularly, and the difference shows. When choosing where to send a paediatric referral, factors worth weighing include:

• Whether the clinic routinely performs the study in the child's age group - sonographer and radiographer experience with children matters as much as equipment • Paediatric dose-reduction protocols for X-ray and CT • Whether reporting radiologists have paediatric experience for complex studies • Practical friendliness - appointment flexibility, tolerance for a wriggly patient, parents allowed in the room • For MRI, whether awake-child strategies are offered or whether sedation cases are redirected to a paediatric centre

For complex or very young patients, a dedicated paediatric imaging service or hospital department is often the better pathway despite longer waits. Directories such as Radly let families compare clinics, and a phone call to the clinic before referring resolves most uncertainty. Consult current RANZCR and paediatric guidelines for specific decisions.