Reading a chest X-ray

Understanding X-Rays

• X-rays are high-energy photons that penetrate body tissues, allowing visualization of internal structures.

• They behave similarly to visible light, having reduced penetration in denser materials.

• Conventional X-rays display white bones on a black background, resembling photographic negatives:

  • Dark areas (e.g., lungs) represent regions where more photons penetrate.

  • Bright white areas show dense bones that block photons.

Checklist for Analyzing Chest X-Rays (A to G)

A: Assessment

• Begin with patient and exam data verification to avoid errors and ensure the correct study is being examined.

• Assess image quality:

  • Check for proper patient rotation by ensuring medial ends of spinous processes are equidistant from vertebral body borders.

  • Evaluate inspiration quality; the film should show at least the 10th or 11th ribs for full lung expansion.

  • Ensure exposure is adequate; adjust brightness to visualize fine lung markings clearly.

• Check for air in unintended locations (e.g., pneumothorax, pneumomediastinum). This is crucial for diagnosing surgical emergencies relative to air presence.

B: Bones

• Inspect both clavicles and all 12 pairs of ribs for:

  • Fractures

  • Deformities

  • Missing bones

• Examine body wall and soft tissues for swelling, masses, or irregularities; often overlooked.

C: Cardiac Silhouette and Size

• Assess the cardiac silhouette:

  • Features include the right atrium, left ventricle, and atrial appendage.

  • Orientation: Right atrium appears on the left side of the X-ray; left ventricle is on the right.

• Normal heart size should be less than 50% of the rib cage's greatest diameter; larger sizes may indicate pathology.

D: Diaphragms

• Diaphragms should be symmetric, with appropriate contour.

• In lateral views:

  • Estimate that a normal hemidiaphragm is 1.5 centimeters above the line connecting costophrenic and sternophrenic angles.

E: Equipment and Effusions

• Note the placement of lines, tubes, and wires associated with life support:

  • Endotracheal tubes should be centered in the trachea, at least 2 cm from the tracheal bifurcation.

  • Nasogastric tubes should be positioned within the stomach.

• Check for pleural effusion:

  • Fluid at costophrenic angles indicates blunting, affecting diagnostic interpretation.

F: Lung Fields

• Lung fields should appear symmetric with the absence of:

  • Haziness

  • White dots or blotches

• Use frontal and lateral X-rays to localize abnormalities:

  • Example: A nodular mass in the left lung's anterior segment can often be confirmed with CT scans.

G: Great Vessels

• Evaluate positioning and size of the great vessels:

  • Key structures: superior and inferior vena cava, ascending aorta, aortic arch, pulmonary artery, descending aorta.

• Orientation: Aortic arch should be positioned highest on the left side; other heart structures should be correctly aligned.

• Deviations may indicate underlying congenital issues or disease.

Recap of ABCDEFG Checkpoints

1. A: Assessment of data, quality, and identifying air abnormalities.

2. B: Bones in the body wall condition.

3. C: Cardiac silhouette measurement and size assessment.

4. D: Diaphragm evaluation for symmetry and flatness.

5. E: Check equipment placement and effusions.

6. F: Analysis of lung fields for symmetry and abnormalities.

7. G: Assessment of the great vessels' position and size.