Overview
This lecture covers the basics of interpreting normal versus abnormal chest x-rays, with a focus on identifying signs of emphysema.
Elements of a Quality Chest X-Ray
- A quality chest x-ray must have proper exposure, showing the vertebral column faintly visible behind the heart.
- Check patient rotation by confirming clavicle heads are symmetrical at the cervical vertebrae and equal costophrenic angles.
- Ensure it is an inspiratory film by counting nine or more visible ribs within the lung fields.
Normal Chest X-Ray Findings
- Lung fields should appear well-aerated with peripheral lung markings and no areas of abnormal radiolucency.
- Diaphragms should be dome-shaped and costophrenic angles appear sharp.
- Heart size should be less than 50% of the thoracic cavity width.
- The right hemidiaphragm is slightly higher than the left due to liver position.
Abnormal Chest X-Ray: Emphysema
- Lungs appear long, skinny, and hyperlucent due to increased air content (hyperinflation).
- Increased intercostal spacing is seen as ribs are spread further apart.
- Diaphragms are flattened or depressed rather than dome-shaped.
- The heart (cardiac silhouette) appears elongated and narrow ("bicycle seat" appearance).
- All these changes indicate chronic air trapping and lung overinflation typical of emphysema, an obstructive lung disease.
Key Terms & Definitions
- Exposure — The visibility of the vertebral column behind the heart, indicating proper x-ray intensity.
- Rotation — Patient alignment; checked via symmetrical clavicles and costophrenic angles.
- Inspiratory Film — X-ray taken during deep breath showing ≥9 ribs to ensure full lung inflation.
- Intercostal Spacing — The space between ribs, increased in hyperinflated lungs.
- Radiolucency — Appearance of dark (black) areas on x-ray indicating air.
- Costophrenic Angle — The angle between the diaphragm and the chest wall, should be sharp in normal x-rays.
- Cardiac Silhouette — The outline of the heart on a chest x-ray.
- Emphysema — Chronic obstructive lung disease characterized by alveolar destruction and air trapping.
Action Items / Next Steps
- Memorize the three quality elements of chest x-rays: exposure, rotation, and inspiration.
- Learn to identify emphysema-related findings on chest x-rays.
- Review any provided cheat sheets or radiographic interpretation guides.