Interpret a paediatric chest radiograph — OSCE

Candidate brief

You have this station to interpret a paediatric chest radiograph systematically. Perform the technical-quality check before reading the fields, apply the ABCDEFGH systematic review, recognise the named radiographic signs, and discuss the radiation-aware principle that governs whether the film should have been requested. Treat the film as one piece of information that must be read with the clinical picture, never instead of it. [1] [2]

Key teaching and management objectives

Begin with the technical-quality check, asking five explicit questions. Projection: is the film PA, AP, or lateral? Position: erect or supine? Rotation: are the medial ends of the clavicles symmetric and equidistant from the spinous processes — if not, the heart and mediastinum are unreliable. Inspiration: do at least nine posterior ribs cross the diaphragm at the midclavicular line — fewer indicates under-inflation, which falsely enlarges the heart. Penetration: is the thoracic spine just visible through the cardiac shadow? A film that fails any of these is flagged as limited, and the key findings are interpreted with that limitation stated. [1] [2]

Next, apply the ABCDEFGH systematic review: airway (trachea midline), bones (ribs, clavicles, spine; posterior rib fractures in suspected non-accidental injury), cardiac (size, shape, borders, the silhouette sign), diaphragm (sharp, right higher than left, angles clear), effusions (dependent spaces, behind the heart), fields (aeration, consolidation, air-trapping, side with side), gastric and gadgets (every tube and line, position confirmed), and hilum and mediastinum (symmetric hila, normal thymus recognised). [1]

Recognise the named radiographic signs: the silhouette sign (localises disease by the border it erases), the air bronchogram (confirms alveolar disease), the meniscus sign (a pleural effusion), the deep sulcus sign (a pneumothorax on a supine film), the spine sign (retrocardiac lower-lobe consolidation), and the sail sign (the normal thymus). Recognise the normal paediatric thymus as the sharp, angular right upper mediastinal opacity in the infant that changes shape with respiration and is not a mass. [1] [3]

Close with the radiation-aware principle. The film is requested only when it will change management, under the principle of justification and ALARA. The effective dose of a paediatric CXR is approximately 0.02 mSv, equivalent to a few days of natural background radiation; children are more radiosensitive than adults per unit dose because of their longer remaining life expectancy and higher proportion of dividing cells. The systematic review confirmed that the prevalence of radiographic pneumonia in wheezing children is low, and routine films are not indicated in uncomplicated bronchiolitis and wheeze. [4]

Marking domains

• Technical-quality check (4 marks). Names and applies all five components (projection, position, rotation, inspiration, penetration); identifies the reliable marker of rotation (asymmetric clavicles) and of a poor inspiration (fewer than nine posterior ribs); flags a limited film appropriately.
• Systematic ABCDEFGH review (4 marks). Applies the method zone by zone; names what is looked for in each; reads the tubes and lines before the lung fields in the intensive-care context; guards against satisfaction of search.
• Recognition of paediatric-specific normal and named signs (3 marks). Recognises the normal thymus and the sail sign; names the silhouette sign, air bronchogram, meniscus sign, deep sulcus sign, and spine sign; states the normal infant cardiothoracic ratio (up to 0.60) and why it differs from the adult.
• Synthesis with the clinical picture (2 marks). States that the film is read with the child, not instead of the child; recognises that a normal film never overrides an unwell child.
• Radiation-aware principle (2 marks). Quotes the approximate effective dose (0.02 mSv); explains justification and ALARA and why children are more radiosensitive; states when a chest film is not indicated. [1] [4]