Chest X-ray Technique and Views

Chest X-ray Technique

• X-rays are a type of electromagnetic radiation that can pass through the body, allowing visualization of internal structures.
• The image is formed based on the different absorption of X-rays by different tissues like bone, lung, and air.

X-ray Views

• PA (Posteroanterior) View: Standard view for adults, taken with patient facing the image receptor.
  • Full lung fields should be visible.
  • Scapulae should be away from the lung fields.
  • Clavicles should be symmetrical and equidistant from the vertebral column.
  • Adequate inspiration should show 6th anterior ribs or 10 posterior ribs.
• AP (Anteroposterior) View: Used for patients who cannot cooperate for PA view.
  • Heart appears magnified compared to PA view.
  • Scapulae are usually visible in the lung fields.
• Lateral View: Used in conjunction with PA, allowing visualization behind the heart and diaphragm.
  • The patient's side being examined is in contact with the image receptor.
• Apical/Lordotic View: Used to visualize the lung apices.
  • Clavicles should be above the lung fields.
  • Shows the apices of the lungs.

Radiation Safety

• Ionizing Radiation Risks: Can have deterministic (dose-dependent) and stochastic (non-dose dependent) effects.
• Deterministic Effects: Occur after exceeding a threshold dose. Examples include cataracts, erythema, and radiation-induced cell death.
• Stochastic Effects: Not dependent on dose, cause DNA damage leading to cancer or genetic defects.
• CXR Radiation Dose: A single PA view has an average effective dose of 0.02 mSv, equivalent to 4 days of background radiation.
• Patient Safety:
  • Justify examinations with clinical summary.
  • Confirm patient identity.
  • Use correct technique and preparation to avoid repeats.
  • Collimate and shield to minimize radiation exposure.
• Healthcare Worker Safety:
  • Limit access to radiation areas.
  • Use shielding like lead aprons and barriers.
  • Monitor radiation exposure for workers.
• Pregnancy Safety:
  • Inquire about pregnancy status.
  • Use dose-reduction strategies if necessary.
  • Shield the abdomen with lead aprons.
  • Minimize exposure time and number of views.
• ALARA Principle: As Low As Reasonably Achievable. This principle should guide all radiation safety practices.

Quality of Chest X-ray

• Evaluate technical quality before interpretation.
• Patient Details: Verify patient identity (name, date, facility).
• View: Confirm the positioning (PA, AP, lateral).
• Key Quality Assessment Factors:
  • Rotation: Clavicular heads should be equidistant from the spinous processes.
  • Inspiration: Diaphragm should be at the level of 8th–10th posterior rib or 5–6th anterior rib.
  • Penetration: 4 lower thoracic vertebrae should be visible through the heart, left hemidiaphragm should be visible at the spine.
• Assessing Quality of CXR:
  • Clavicles: Medial ends should be equidistant from the spinous processes.
  • Spinous Processes: Should be between the clavicular heads.
  • Vertebrae: Bodies should be visible.
  • Ribs: Posterior ribs well visualized in PA view, anterior ribs well visualized in AP view.

Inspiration Assessment

• CXR should be taken with full inspiration.
• Inspiration Adequacy: Count ribs to the diaphragm, 8th–10th rib posteriorly or 5–6th rib anteriorly.
• Hyper-Expansion: Flattened hemidiaphragms can indicate hyperinflation.

Penetration Assessment

• Normal Penetration: 4 lower thoracic vertebrae visible through the heart, left hemidiaphragm visible at the spine.
• Under Exposure: Structures appear darker (radiopaque), may lead to overcalling findings.
• Over Exposure: Structures appear lighter (radiolucent), may miss findings.

Other Factors Affecting X-ray Quality

• Scapulae: Should be away from the lung fields in PA view, visible within the lung fields in AP view.
• Gastric Bubble: Should be well visualized in PA view, not well visualized in AP view.
• Technical Considerations:
  • Ensure correct X-ray technique and positioning.
  • Optimal exposure factors and beam energy.