Chest Radiography (CXR)

• Chest radiography (CXR) is a widely used diagnostic imaging technique
• X-rays are used to create images of the chest, including the heart, lungs, blood vessels, airways, and bones of the chest and spine

Indications

• CXR is performed for a variety of indications
• It's used to diagnose and monitor lung conditions such as pneumonia, heart failure, emphysema, lung cancer, and other chest-related diseases or conditions
• Persistent cough, shortness of breath, chest pain, fever, or injury to the chest are common reasons for ordering a CXR

Technique

• A CXR machine emits a small dose of radiation that passes through the chest
• Structures in the chest absorb the X-rays differently depending on their density
• Bones absorb more X-rays and appear white, while air absorbs the least and appears black
• A detector on the other side of the chest captures the X-rays and creates an image
• Standard CXR views include posteroanterior (PA) and lateral projections

Posteroanterior (PA) View

• Patient stands facing the detector
• X-ray beam enters from the back (posterior) and exits through the front (anterior)
• Provides a clear view of the lungs and mediastinum
• Heart size is more accurately assessed in the PA view

Lateral View

• Patient stands with their side against the detector
• X-ray beam enters from the side
• Helps to visualize structures that may be hidden on the PA view, such as behind the heart or near the spine
• Lung lesions can be localized or the presence of fluid can be confirmed using this technique

Interpretation

• CXR interpretation requires a systematic approach
• Assessment of the technical quality of the image is important
• Check for proper positioning, penetration, and inspiration
• Evaluate the lungs for any abnormalities such as opacities, nodules, or consolidation
• Assess the size and shape of the heart and mediastinum
• Look for signs of fluid accumulation in the pleural space (pleural effusion)
• Examine the bones for fractures or other abnormalities

Advantages

• Widely available and relatively inexpensive
• Quick and easy to perform
• Provides valuable information about the chest
• Lower radiation dose compared to other imaging modalities, such as CT scans

Limitations

• Limited ability to detect small or subtle abnormalities
• Overlapping structures can obscure findings
• Cannot differentiate between certain types of lung lesions
• Ionizing radiation exposure

Findings

Pneumonia

• Appears as an area of consolidation (increased density) in the lung
• May be localized to a specific lobe (lobar pneumonia) or scattered throughout the lungs (bronchopneumonia)
• Air bronchograms (air-filled bronchi surrounded by consolidation) may be visible

Heart Failure

• Can cause cardiomegaly (enlarged heart)
• Pulmonary edema (fluid in the lungs) may be seen as increased interstitial markings, Kerley B lines, or alveolar edema
• Pleural effusions may also be present

Emphysema

• Characterized by hyperinflation of the lungs
• Flattened diaphragm
• Increased retrosternal airspace
• Bullae (air-filled spaces) may be visible

Lung Cancer

• Can present as a solitary nodule, mass, or consolidation
• Hilar enlargement (enlarged lymph nodes in the hilum of the lung) may be present
• Pleural effusions may also occur

Pleural Effusion

• Appears as a fluid collection in the pleural space
• Blunting of the costophrenic angle (the angle between the ribs and diaphragm)
• Meniscus sign (curved upper border of the fluid)
• Large effusions can cause mediastinal shift (displacement of the mediastinum to the opposite side)

Pneumothorax

• Presence of air in the pleural space
• Absence of lung markings in the affected area
• Visceral pleural line (a thin white line representing the edge of the collapsed lung)
• Tension pneumothorax can cause mediastinal shift and compression of the heart and great vessels

Consolidation

• Refers to the replacement of air in the alveoli with fluid, pus, blood, or cells
• Appears as an area of increased density on CXR
• Common causes include pneumonia, pulmonary edema, and lung cancer

Nodules and Masses

• Nodules are small, well-defined lesions, typically less than 3 cm in diameter
• Masses are larger lesions, typically greater than 3 cm in diameter
• Can be benign or malignant
• Further evaluation with CT scan or biopsy may be necessary

Atelectasis

• Refers to the collapse of lung tissue
• Can be caused by obstruction of the airway, compression of the lung, or loss of surfactant
• Appears as an area of increased density with volume loss
• May be associated with mediastinal shift and elevation of the hemidiaphragm

Interstitial Lung Disease

• Affects the tissue and space around the air sacs of the lungs
• Increased interstitial markings (fine lines and dots)
• Honeycombing (small, cystic spaces)
• Ground-glass opacities (hazy areas of increased density)

Mediastinal Masses

• Abnormal growth in the mediastinum
• Can be difficult to diagnose on CXR alone
• Further evaluation with CT scan or MRI may be necessary

Rib Fractures

• Broken bones in the ribcage
• Sharp edges or discontinuities in the bone
• Often caused by trauma or injury
• Can be associated with pneumothorax or hemothorax