Paeds · investigations-procedures-and-technology
Chest radiograph interpretation in children
Also known as Chest X-ray · CXR · Paediatric chest film · Chest radiograph · Plain chest imaging · AP chest film
Fellowship guide to interpreting the paediatric chest radiograph. Covers why the child's chest film differs from the adult's — the thymus that reshapes the mediastinum, the cartilaginous skeleton, the projection and inspiration that change everything — the structured technical-quality check that must precede any reading, the ABCDEFGH systematic approach applied zone by zone, the normal cardiothoracic ratio and how rotation and poor inspiration falsely enlarge the heart, the neonatal chest film with its lines and tubes, the radiographic signs of pneumonia, foreign-body aspiration, heart failure and the common pitfalls, and the radiation-aware ALARA principle that governs when a film is justified at all.
On this page
Related topics
Study tools
Your progress
Saved on this device.
Practise this topic
Target exams
Red flags
- Reading the lung fields before checking technical quality — patient rotation and a poor inspiration together produce a widened mediastinum, crowded ribs and a falsely enlarged heart, and they are the commonest reason a child is overdiagnosed with cardiomegaly or a mediastinal mass
- Calling the normal paediatric thymus a mediastinal mass or lobar pneumonia — the thymus produces the characteristic sail sign in the right upper mediastinum and the wavy inferior border, and mistaking it for pathology triggers unnecessary further imaging and anxiety
- Missing the endotracheal tube sitting in the right main bronchus or above the clavicles — a tube that is too low over-expands and eventually collapses the left lung, and a tube that is too high fails to ventilate; the tip must sit midway between the clavicles and the carina
- Reading a unilateral hyperlucent lung as normal in a coughing child — an inspiratory film can miss an inhaled foreign body, which requires a lateral decubitus film or an expiratory film to show air-trapping on the affected side
- Treating the chest radiograph as the diagnosis rather than one piece of information that must be read with the clinical picture — the film is a two-dimensional projection of a moving three-dimensional structure, and over-reliance on it without the child in front of you produces both false positives and false negatives
Life stages
Care settings
Clinical exam formats
Board mappings
- Investigations and procedures
- Interpret a paediatric chest radiograph systematically
- Recognition of technical-quality pitfalls and when a film is inadequate
- Current 2026 PREP curriculum — Learning goal 11: Investigations and procedures
- Renewed curriculum for first-year trainees from 2027 — Learning goal 11: Investigations and procedures
- Confident systematic interpretation of paediatric chest radiographs across settings
- Written Examination
- Clinical Applications
- Respiratory and cardiac presentations requiring chest radiograph interpretation
- Short Cases
- Radiology interpretation stations
- Communication and patient-safety scenarios around imaging
- 11. Investigating and managing paediatric presentations
- Level 2: Interprets common investigations including the chest radiograph with appropriate supervision
- Patient safety: radiation-aware imaging and recognition of pitfalls
- Applied Knowledge in Practice (AKP)
- Foundations of Practice (FOP)
- Radiology: systematic interpretation of the paediatric chest radiograph
- Clinical
- Radiology interpretation scenarios
- Safe, radiation-aware imaging requests and consent
- General Pediatrics Content Outline — Radiology: chest radiograph interpretation
- General Pediatrics Content Outline — Respiratory and cardiac diagnoses
- General Pediatrics EPA: Interpret a paediatric chest radiograph
- Patient Care 2: Diagnostic interpretation
- Medical Knowledge 1: Clinical knowledge
- Systems-Based Practice: radiation-aware, value-based imaging
- Medical Expert
- Scholar
- Pediatrics: Core EPA — Interpret common paediatric imaging including the chest radiograph
Overview & Definition
Picture the febrile two-year-old with a grunting respiration, the neonate on continuous positive airway pressure whose oxygen need has crept up, or the five-year-old with a wheeze that does not resolve. In each, the chest radiograph is the first and often the only imaging investigation the team will order, and the question that matters is not "what does the film show" but "what does the film show in this child, taken this way". That is the territory this page owns. [1] [2]
A chest radiograph (CXR, chest X-ray) is a two-dimensional projection radiograph of the thorax in which a beam of X-rays passes through the chest and is differentially absorbed by the tissues, producing a shadow image on a digital detector. Dense tissues such as bone absorb most photons and appear white, while air-filled lung absorbs few and appears black, and soft tissues occupy the grey spectrum in between. The standard view in a cooperative older child is the pa posterolateral (PA) film taken erect in full inspiration with the X-ray beam travelling from posterior to anterior; the anteroposterior (AP) film is taken the other way and is the default in the sick, supine or young child who cannot stand or cooperate; a lateral film is added when localisation or a question about the mediastinum or spine is needed. [4] [6]
What makes the paediatric chest film a distinct skill from adult radiography is a set of developmental differences and a set of technical realities. The thymus is large in the infant and young child and reshapes the mediastinal contour, producing the sail sign that is normal and not a mass. The skeleton is largely cartilaginous, so the costophrenic angles and rib detail behave differently and a posterior rib fracture is easily missed. The heart sits more horizontally and the normal cardiothoracic ratio in an infant is up to 0.60, falling toward the adult value of 0.55 by around five years. Most films in the unwell child are AP, supine, and in less than full inspiration, and all three of those artefacts enlarge the apparent heart and crowd the lung fields. The fellowship skill being tested is reading the technical quality first, then applying a systematic method, then folding in the clinical picture. [1] [3]
References12ShowHide
- [1]Bramson RT, Griscom NT, Cleveland RH Interpretation of chest radiographs in infants with cough and fever Radiology, 2005.PMID 15983074
- [2]Shah SN, Bachur RG, Simel DL, et al Does This Child Have Pneumonia?: The Rational Clinical Examination Systematic Review JAMA, 2017.PMID 28763554
- [3]Marais J, Venkatakrishna SSB, Calle-Toro JS, et al Patient rotation chest X-rays and the consequences of misinterpretation in paediatric radiology Paediatr Respir Rev, 2023.PMID 37244797
- [4]Barnes N, Pilling DW Interpretation of the neonatal chest X-ray Hosp Med, 1999.PMID 10707187
- [5]Wee T, Lee AF, Nadel H, et al The paediatric thymus: recognising normal and ectopic thymic tissue Clin Radiol, 2021.PMID 33762135
- [6]Rosendahl K Pediatric chest and hand radiographs revisited Acta Radiol, 2005.PMID 16134306
- [7]Pitcher RD, Beningfield SJ, Zar HJ The chest X-ray features of chronic respiratory disease in HIV-infected children--a review Paediatr Respir Rev, 2015.PMID 25736908
- [8]Connolly B, Racadio J, Towbin R Practice of ALARA in the pediatric interventional suite Pediatr Radiol, 2006.PMID 16862417
- [9]Strauss KJ, Goske MJ Estimated pediatric radiation dose during CT Pediatr Radiol, 2011.PMID 21847725
- [10]Shah SN, Monuteaux MC, Neuman MI Prevalence and predictors of radiographic pneumonia in children with wheeze: A systematic review and meta-analysis Acad Emerg Med, 2024.PMID 39189186
- [11]Chaudhary S, Jeevika, Jha S The Cardiothoracic Ratio on Trial Acad Radiol, 2025.PMID 40947292
- [12]Sehgal A, Singh V, Chandra J, et al Foreign body aspiration Indian Pediatr, 2002.PMID 12466569