What is the proper procedure for interpreting x-rays (radiographs)?

How to Read X-Rays: A Systematic Approach

Use a structured, systematic review method when interpreting radiographs, examining each anatomical region sequentially to minimize perceptual errors, which are the most common cause of missed diagnoses and litigation in radiology. 1, 2

Systematic Review Framework

The interpretation of x-rays requires a methodical approach that examines all anatomical structures in a predetermined sequence. This systematic method reduces the risk of "failure to detect" errors, which represent the most frequent interpretive mistakes in radiology. 2

For Chest X-Rays Specifically:

Start with the mediastinum and central structures:

• Assess tracheal position and patency, looking for deviation that might indicate mass effect or pneumothorax 1
• Evaluate mediastinal contours and width—a widened mediastinum (>8 cm on PA view) may indicate aortic injury, dissection, or lymphadenopathy 1
• Check cardiac size and silhouette, with cardiothoracic ratio >0.5 indicating cardiomegaly 1
• Look for pneumomediastinum, indicated by air tracking along mediastinal structures 1

Examine lung fields systematically:

• Compare side-to-side for focal opacities or consolidation 1
• Evaluate interstitial patterns (reticular, nodular, or reticulonodular) 1
• Assess for pneumothorax by identifying a visible pleural line with absence of lung markings peripherally 1
• Look for pleural effusion, indicated by meniscus sign and blunting of costophrenic angles 1
• Check for pleural thickening or plaques, which may suggest asbestos exposure 1

Evaluate bones and soft tissues:

• Examine ribs, clavicles, scapulae, and vertebrae for fractures or lesions 1
• Check for soft tissue abnormalities such as subcutaneous emphysema or masses 1
• Assess diaphragm contours and position for signs of injury or disease 1

Critical Considerations in Specific Clinical Contexts

In trauma patients, prioritize:

• Widened mediastinum (potential aortic injury) 1
• Rib fractures (associated with underlying pulmonary contusion) 1
• Pneumothorax or hemothorax 1

In suspected pulmonary embolism:

• Look for Westermark sign (focal oligemia) and Hampton's hump (wedge-shaped peripheral opacity) 1
• Note that a normal chest x-ray actually increases suspicion for PE in patients with acute dyspnea and hypoxemia 1

Technical Optimization for Image Acquisition

Minimize radiation exposure while maintaining diagnostic quality:

• Use optimal beam collimation to limit x-ray beam size to the minimum area needed 3
• Position the x-ray source and image receptor optimally—minimize distance from patient to detector, maximize distance from x-ray tube to patient 3
• Use the least degree of image magnification required for accurate interpretation 3
• Minimize beam-on time and only irradiate when actively viewing the monitor 3
• Record estimated dose delivered to the patient for quality monitoring 3

Important Limitations and Pitfalls

Recognize the inherent limitations of plain radiography:

• Chest x-rays have lower sensitivity compared to CT for many conditions 1
• Up to 50% of pneumothoraces, pulmonary contusions, and rib fractures may be missed on standard AP radiographs 1
• Advanced imaging (CT or MRI) should be obtained for definitive diagnosis when clinical suspicion remains high despite normal or equivocal radiographs 1

Common interpretive errors:

• Senior radiologists achieve significantly higher accuracy than non-specialists, with specialists (radiologists and respiratory medicine physicians) scoring significantly better than general clinicians 4
• Perceptual errors from "failure to detect" are the most common cause of missed diagnoses 2
• All chest x-rays should be reviewed by a senior clinician early during hospital admission and formally reported by a radiologist at the earliest opportunity 4

Training and Competency Development

Structured learning improves interpretation skills:

• Systematic teaching on x-ray interpretation should be provided to newly qualified doctors 4
• E-learning resources combined with traditional teaching methods are more effective than either approach alone for developing radiological interpretation skills 5, 6
• Perceptual learning methods and targeted interventions can enhance expertise and reduce medical error 2

Clinical correlation is essential:

• Adequate clinical information is critical for accurate interpretation—lack of clinical context may negatively affect the ability to determine whether a finding is important 7
• Communication between radiologists and referring clinicians should be timely and readily accessible 7