Module 1: Chest Radiology

Introduction to Chest X-Ray Viewing

1. First, inspect the BONY FRAMEWORK of the chest
   You should be able to count and number the ribs, inspect the capulae, humeri and shoulders, and clavicles, and seethe diaphragms overlying the posterior aspects of the 10th or 11th ribs (in a normal adult)> The spine and sternum are generally difficult to visualize in detail on standard PA films due to overlying shadows.

2. Next, inspect the soft the SOFT TISSUES that overlie the thoracic cage
   Note the breast shadows,supraclavicular areas, axillae, and tissues along the sides of the chest.

3. Examine the LUNG FIELDS and HILA
   The hilum ("lung root") is the shadow of pulmonary artery and vein adjacent the heart shadow.
   Normal lung markings are the linear and fine nodular shadows of pulmonary vessels.
   Abnormalities in the lung fields are marked by excessive radiolucency, excessive radiopacity, or opacified areas.

4. Next, examine the DIAPHRAGM and PLEURAL SURFACES
   Diaphragmatic images in the lung bases are dense, radiopaque shadowsmade principally by the liver on the left and the spleen on the right.
   The normal pleura is not visible on the chest x-ray, except where two layers come together to form the interlobar fissures.

5. Finally, examine the MEDIASTINUM and and HEART
   Displacement of the mediastinum is an important clue to disease in on or the other hemithorax.
   On the PA chest film, the normal right heart and mediastinal border is made up (from bottom to top) of the 1) inferior vena cava; 2) the right atrium; 3)ascending aorta; and 4) superior vena cava. The normal left heart and mediastinal border consists (from bottom to top) of the 1) left ventricle; 2) left atrium; 3)pulmonary artery; 4) aortic arch; and 5) subclavian artery and vein.

Pitfalls to Chest X-Ray Interpretation: Beware the Poor Quality Film

1. Poor inspiration results in high diaphragms and crowding of normal lung markings.

2. Over- or under-penetration of the x-ray beam can obliterat or exaggerate important findings. On a properly-penetrated PA chest rafiograph, one can just make out the thoracic vertebrae overlying the image of the heart.

3. Rotation from the true perpendicular on the PA chest film distorts normal structures. Check proper orientation by noting equal distances from the vertebral spines to the medial ends of the clavicles.

Prepared by Dr. Christopher H Fanta
Squire, LF. Fundamentals of Roentgenology. Cambridge, MA: Harvard University Press, 1964.

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