What are the indications and criteria for performing a computed tomography (CT) scan in children (0‑18 years), including red‑flag head trauma, suspected intracranial pathology not assessable by magnetic resonance imaging (MRI), severe abdominal or thoracic trauma, radiopaque foreign bodies, complex congenital anomalies, and oncologic staging?

Pediatric CT Scan Criteria

CT imaging in children should be reserved for specific high-risk clinical scenarios where the immediate diagnostic benefit substantially outweighs the long-term radiation risk, guided by validated clinical decision rules and strict adherence to pediatric-specific, reduced-dose protocols. 1

Head Trauma: Risk-Stratified Approach

High-Risk Features (CT Mandatory)

Obtain immediate non-contrast head CT when any of the following are present, as the risk of clinically important traumatic brain injury is approximately 4.3%: 1

• Glasgow Coma Scale (GCS) ≤14 or altered mental status 2, 1
• Signs of basilar skull fracture 2, 1
• Palpable skull fracture (in children <2 years) 1
• Post-traumatic seizures 1

Intermediate-Risk Features (CT vs. Observation)

Consider CT or clinical observation for children with GCS 15 and normal mental status who have any of: 1

• Vomiting 1
• Severe or worsening headache 1
• Loss of consciousness >5 seconds 1
• High-impact mechanism of injury 1
• Non-frontal scalp hematoma (in children <2 years) 1

The risk of clinically important injury in this group is approximately 0.8%. 1 Every additional hour of emergency department observation decreases CT utilization without delaying diagnosis of significant traumatic brain injury. 1, 3

Very Low-Risk (CT Not Indicated)

Do not obtain CT in children who meet all of the following PECARN low-risk criteria, as the risk of clinically important injury is <0.02%: 1

• GCS 15 with normal mental status 1
• No loss of consciousness (or ≤5 seconds in children <2 years) 1
• No vomiting 1
• No severe mechanism of injury 1
• No severe headache 1
• No signs of basilar skull fracture 1
• Acting normally per parents (in children <2 years) 1

Suspected Physical Abuse

Non-contrast head CT is mandatory when evaluating suspected abusive head trauma with any of: 2

• Neurologic abnormalities 4
• Complex skull fractures 4
• Apnea 4
• Multiple fractures 4
• Facial injuries 4

Do not apply PECARN decision rules to children with suspected abuse, as this population was excluded from validation studies. 3, 4 Contrast-enhanced CT of chest, abdomen, and pelvis is indicated when clinical signs suggest visceral injury. 4

Thoracic and Abdominal Trauma

• CT chest with IV contrast is appropriate for suspected bronchopleural fistula, lung abscess, or recurrent localized pneumonia. 4
• CT chest without contrast is more sensitive than radiography for detecting rib fractures (radiographs miss ~40% of fractures detected by CT), but should be used as an adjunct rather than first-line due to sedation requirements in young children. 2
• Contrast-enhanced CT of abdomen/pelvis is indicated when clinical signs suggest intra-abdominal visceral injury. 4

Spine Trauma

• Plain radiographs are the initial study for suspected pediatric spine trauma. 2
• CT cervical spine is superior to radiographs in high-risk patients but should not replace screening radiographs in children at low risk for cervical spine injury. 2
• Normal variants in children <8 years (pseudosubluxation C2-C3, absence of lordosis, widened atlantodental interval) can adversely affect CT interpretation accuracy. 2
• MRI is superior to CT for detecting cartilaginous injuries and ligamentous disruption not visualized on radiographs or CT. 2

Headache

• MRI without contrast is the preferred modality for evaluating secondary headaches in children, as it avoids radiation and provides superior soft-tissue detail. 2
• CT without contrast may be appropriate only when MRI is unavailable or contraindicated, particularly in emergency settings. 2
• CT angiography (CTA) is indicated if acute stroke or arterial dissection is suspected, though MRI/MRA remains preferred. 2
• CT venography (CTV) is an alternative to MR venography for suspected venous sinus thrombosis or pseudotumor cerebri syndrome. 2

Critical Radiation Safety Principles

Radiation Risks in Children

Children face substantially higher lifetime cancer risk from CT radiation than adults due to: 1, 3

• Greater radiosensitivity of rapidly dividing cells 3
• Smaller body size resulting in higher organ-specific doses 3
• Longer life expectancy for radiation-induced cancers to develop 1, 3
• Increased risk of brain tumors, leukemia, and cataracts 1, 3

Dose Optimization Strategies

All facilities imaging children must implement: 3

• Pediatric-specific, size-adjusted, reduced-dose CT protocols following ALARA principles 1, 3
• Ultra-low-dose protocols that reduce radiation by ~20% without compromising diagnostic quality 3, 4
• Multiplanar and 3D reconstructions to increase sensitivity for fractures and hemorrhages 1

Alternative Imaging When Appropriate

• Prioritize ultrasonography as first-line imaging whenever clinically appropriate (e.g., appendicitis evaluation). 3
• Use MRI for follow-up imaging when cross-sectional imaging is needed. 3

Common Pitfalls to Avoid

• Never obtain routine "pan-scan" whole-body CT in pediatric trauma patients; use selective region-specific scanning based on clinical prediction models, as pan-scans deliver 3-4× the radiation without outcome benefit. 3, 4
• Do not substitute skull radiographs for indicated head CT—skull X-rays miss up to 50% of intracranial injuries and provide no information about brain parenchyma. 1, 4
• Avoid CT obtained at referring facilities before transfer without consultation with the receiving pediatric trauma center, as this leads to duplicate studies and excess radiation. 4
• Do not compromise diagnostic image quality in pursuit of dose reduction—optimization means achieving adequate quality at the lowest feasible dose, not dose reduction at any cost. 3, 4
• Never delay imaging when high-risk features are present; prolonged observation is appropriate only for intermediate-risk patients. 1

Informed Decision-Making

Discuss both the immediate injury risk and long-term radiation risk with patients and families to support informed decision-making, acknowledging that the immediate 4.3% risk of clinically important injury in high-risk patients far outweighs the minute lifetime cancer risk from a single CT scan. 1, 5