Skull X-Ray

Plain skull radiography has a limited and declining role because CT is superior for both intracranial injury and fracture detection. It retains value for assessing bony lesions, certain craniofacial abnormalities, suspected non-accidental injury as part of a skeletal survey, foreign bodies and shunt/device surveys. Interpretation requires familiarity with normal sutures and vascular grooves, which are commonly mistaken for fractures.

Indications

Suspected metabolic or destructive bone lesions of the calvarium (myeloma, metastasis, Paget disease)
Skeletal survey for suspected non-accidental injury in children
Assessment of craniofacial dysostoses and congenital anomalies
Localisation of radiopaque foreign bodies
Survey of ventriculoperitoneal shunt tubing and cranial hardware
Suspected skull fracture only where CT is unavailable (CT strongly preferred)
Evaluation of the sella turcica and skull base in selected pituitary or endocrine cases

Contraindications & Cautions

No absolute contraindications
CT is preferred for head trauma; do not use skull radiographs to exclude intracranial injury
Pregnancy: negligible fetal dose but justify and shield
Low radiation dose (~0.07 mSv) but includes radiosensitive lens of the eye - collimate and apply ALARA
Avoid in acute head injury where CT is indicated by clinical decision rules

Patient Preparation

Remove hairpins, earrings, dentures, hearing aids and other radiopaque items
No fasting or sedation routinely required (sedation occasionally needed in young children)
Position the head accurately using the orbitomeatal baseline for standard projections
Explain the breath-hold and need for immobility to avoid motion blur
Immobilise infants appropriately for a skeletal survey
Confirm pregnancy status where relevant

Technique & Parameters

Standard projections: PA (or AP) and lateral views
Towne (AP axial) projection demonstrates the occipital bone and foramen magnum
Waters (occipitomental) projection demonstrates the facial bones and paranasal sinuses
70-80 kVp with a grid; fine detail with the head immobilised
Both lateral sides may be imaged in a skeletal survey; symmetrical positioning is essential
Submentovertical and other specialised views occasionally used for the skull base
CT with bone windows is the definitive study for fractures and skull-base assessment

Systematic Review

Assess adequacy and positioning symmetry
Trace the calvarial cortical tables (inner and outer) for lucency or destruction
Identify normal sutures (coronal, sagittal, lambdoid) and vascular grooves to avoid mistaking them for fractures
Evaluate the skull base, sella turcica size and cortex, and petrous bones
Assess the diploic space and any focal lytic or sclerotic lesion
Check for pineal or other physiological calcification and any midline shift of calcified structures
Review facial bones and sinuses on Waters view; occiput on Towne view
Look for foreign bodies, air (pneumocephalus) and device/shunt positions

Key Findings & Significance

A lucent line that is sharp, non-branching and does not follow a sutural course suggests a fracture, while branching, corticated lines are usually vascular grooves or sutures
Multiple well-defined 'punched-out' lucencies suggest multiple myeloma or metastases
Mixed lytic and sclerotic thickened calvarium with a 'cotton wool' appearance suggests Paget disease
A 'hair-on-end' diploic appearance suggests chronic haemolytic anaemia
Enlargement or erosion of the sella turcica suggests a pituitary mass
Widened sutures (sutural diastasis) in a child may indicate raised intracranial pressure
A depressed fragment produces a double density of overlapping bone
Displaced radiopaque foreign body localised on orthogonal views

Differential Considerations

Lucent calvarial lesion: metastasis, myeloma, epidermoid, eosinophilic granuloma, arachnoid granulation, surgical defect
Sclerotic calvarial lesion: osteoma, fibrous dysplasia, Paget disease, sclerotic metastasis, meningioma-related hyperostosis
Lucent line: fracture, suture, vascular groove, venous lakes
Generalised calvarial thickening: Paget disease, chronic anaemia, acromegaly, fibrous dysplasia, phenytoin therapy
Enlarged sella: pituitary adenoma, empty sella, raised intracranial pressure, craniopharyngioma
Intracranial calcification: physiological (pineal, choroid plexus), tumour, old infection, vascular
Multiple wormian bones: osteogenesis imperfecta, cleidocranial dysostosis, hypothyroidism

Pearls & Pitfalls

Do not use skull radiographs to exclude intracranial haemorrhage - CT is required; a normal skull film does not exclude significant brain injury
Sutures and vascular grooves are the commonest mimics of fracture; fractures are lucent, sharp, straight and non-branching without corticated margins
A fracture crossing the middle meningeal artery groove raises concern for extradural haematoma - proceed to CT
Arachnoid granulations and venous lakes are well-corticated lucencies that should not be called lytic lesions
In suspected non-accidental injury, correlate with the full skeletal survey and clinical context
The lens of the eye is radiosensitive - collimate carefully
Correlate any suspected fracture or lesion with cross-sectional imaging

Structured Report

State projections obtained and adequacy
Report calvarial integrity, sutures, skull base and sella
Describe any lucent or sclerotic lesion with size, margin and distribution
Distinguish fracture from vascular groove/suture and state the reasoning
Note foreign bodies, devices, shunt tubing and calcifications
Impression: summarise findings and recommend CT for suspected fracture, intracranial injury or lesion characterisation

References

ACR Appropriateness Criteria: Head Trauma
Royal College of Radiologists iRefer guidelines
NICE Head Injury Guideline (assessment and early management)
Osborn AG. Osborn's Brain: Imaging, Pathology, and Anatomy, Elsevier
Grainger & Allison's Diagnostic Radiology, Elsevier

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

Skull X-Ray

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References