Chest Radiography: Clinical Protocols and Anatomy

Common Pulmonary Pathologies

• Bronchiectasis: Permanent, abnormal dilation of bronchi.
• Cystic Fibrosis: Genetic disease causing thick, sticky mucus buildup in the lungs and digestive tract.
• Emphysema: Alveolar distention; trapped air.
• Pleural Effusion: Excess fluid accumulation between the two pleural layers surrounding the lungs.
• Pneumonia: Inflammation of the lung; most frequent.
• Pulmonary Edema: Abnormal buildup of fluid in the air sacs of the lungs.
• Pulmonary Embolism: Blood clot in the main pulmonary artery or its branches, originating elsewhere in the body.
• ARDS (Acute Respiratory Distress Syndrome): Severe lung syndrome caused by direct or indirect issues, characterized by inflammation, impaired gas exchange, and potential organ failure.
• Hyaline Membrane Disease: Syndrome in premature infants caused by surfactant deficiency and structural lung immaturity.

Chest Radiography Positioning Protocols

Chest PA Projection (Frontal Erect)

• IR: 14x17" LW; Top 1.5–2" above shoulders.
• Position: Erect with backs of hands on hips.
• CR: T7, perpendicular to IR.
• Technique: 110–125 kVp; AEC: Outer cells; 72" SID; Grid.
• Respiration: Suspended upon 2nd full inspiration.

Lateral Projection (Left Lateral Erect)

• IR: 14x17" LW; Top 1.5–2" above shoulders.
• Position: Erect with hands above head or on armrest.
• CR: T7, perpendicular to IR.
• Technique: 110–125 kVp; AEC: Center cell; 72" SID; Grid.
• Respiration: Suspended upon 2nd full inspiration.

AP Decubitus Projection

• Position: Left/right lateral recumbence; arms above head; MSP perpendicular to IR.
• CR: T7, perpendicular to IR.
• Technique: 110–120 kVp; AEC: Outer cells; 72" SID; Grid.

AP Lordotic Projection

• Position: Standing 1' from IR, leaning back; hands on hips.
• CR: Mid-sternum, perpendicular to IR (15–20° cephalic angle for AP Axial).
• Technique: 100–120 kVp; 72" SID; Grid.

Oblique Projections

• Posterior Oblique: Erect, facing bucky; MCP 45° to IR; arm of interest raised.
• Anterior Oblique: Erect, back to bucky; MCP 45° to IR; arm of interest raised.

Soft Tissue Neck Projections

• Lateral: Erect; chin elevated; CR at C6-C7; 80 kVp; 72" SID.
• AP: Erect; head/shoulders on IR; CR at T1; 75–80 kVp; 40" SID.

Radiographic Quality and Technique

Degree of Inspiration

Proper inspiration causes the diaphragm to move down, visualizing lower lung fields. A minimum of 10 posterior ribs must be visible on a PA projection. Practice with the patient prior to exposure.

Erect Chest Radiographs

Erect positioning is preferred to drop the diaphragm, demonstrate air-fluid levels, and prevent engorgement of pulmonary vessels. A 72-inch SID is required to minimize heart magnification.

Common Errors

• Motion from breathing or movement.
• Rotation on PA or lateral radiographs.
• Chin not extended enough (superimposition).
• Arms not positioned high enough for lateral projections.

Anatomy and Landmarks

Bony Thorax

Includes the sternum (manubrium, body, xiphoid), 12 pairs of ribs, 12 thoracic vertebrae, clavicles, and scapulae.

Respiratory System

Air travels through the pharynx, larynx, trachea, bronchi, and bronchioles to the alveoli for gas exchange. The carina is the bifurcation of the trachea; foreign bodies are more likely to lodge in the right bronchus due to its vertical orientation.

Mediastinum

The space between the lungs containing the heart, great vessels (aorta, SVC, IVC, pulmonary arteries/veins), and esophagus.

Lung Anatomy

The right lung has 3 lobes; the left has 2. The pleura is a double-walled membrane (visceral and parietal) surrounding the lungs.

Topographic Landmarks

• Vertebra Prominens: Level with C7-T1; used for PA chest positioning.
• Angular/Manubrial Notch: Level with T2-T3; used for AP chest positioning.
• Xiphoid Process: Level with T9-T10.