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Procedure for performing a chest x-ray

Patient Preparation and Positioning

The patient should be positioned upright, either standing or sitting, to obtain optimal lung expansion and clear visualization of thoracic structures. The standard views are posteroanterior (PA) and lateral projections. For PA view, the patient's chest is placed against the image receptor, with shoulders rolled forward to move scapulae laterally. The lateral view requires the patient to stand with the side of the chest against the receptor, arms raised or positioned to avoid superimposition over the lungs. Proper positioning ensures minimal distortion and accurate anatomical representation.

Technical Factors and Equipment Settings

X-ray tube should be positioned at a standard distance, typically 180 cm (72 inches) from the patient, to reduce magnification of the heart and mediastinum. Exposure factors (kVp and mAs) must be adjusted according to the patient's body habitus to optimize image quality while minimizing radiation dose. A high kilovoltage (usually 110-130 kVp) is preferred for chest imaging to penetrate thoracic structures effectively and produce adequate contrast.

Image Quality Considerations

The chest X-ray must demonstrate full inspiration, ideally showing 9-10 posterior ribs above the diaphragm, to ensure lung expansion is sufficient for diagnostic accuracy. The image should be free from motion blur, with sharp lung markings and clear visualization of the diaphragm, heart, and bony thorax. Proper collimation should be applied to restrict the X-ray field to the area of interest, reducing patient exposure and improving image contrast.

Special Considerations

Artifacts such as jewelry, clothing, or medical devices should be removed or repositioned to avoid obscuring anatomy. In cases where patients cannot stand, anteroposterior (AP) supine or semi-erect views may be performed, acknowledging that these may alter the appearance of mediastinal structures and heart size due to magnification. Metal objects in the chest region can affect image quality and should be noted during interpretation.

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