Chest x-ray

Interpretation

Assess Quality

• May be PA (preferred, taken at a standard 1.8 m distance) or AP (done for patients who are unable to go to imaging department or to position for PA)
  • PA will magnify the mediastinum
  • AP more often done at an upward angle, which can blunt the left dome of the diaphram
• Inspiration: at least 6 anterior ribs should be above the left dome of the diaphragm
  • Shallow inspiration can result in enlarged cardiac diameter, crowding of lung vessels, and basal atelectasis
• Rotation: spine of the vertebral bodies should be midline between the heads of the clavicles
  • Can make one lung appear lighter/darker compared to the other
  • PA rotated right can result in prominent aortic arch on the right, simulating mediastinal mass
  • AP rotated left can also make aortic arch more prominent

Assess Pathology

• Cardiothoracic ratio: should be less than 50% on a PA x-ray
  • If greater, it suggests cardiomegaly
• Domes of the diaphragm: they should be clear and well-defined
  • If obscured, it could suggest pathology of the adjacent lung
• Heart borders: they should be clear and well-defined
  • If obscured, it could suggest pathology of the adjacent lung
• Hila: should be similar density bilaterally, with left hilum at the same level as the right hilum or slightly higher
• Bones
• Overlooked sites: lung apex, superimposed on the heart, around each hilum, under the diaphragm