Plain radiography

The chest radiograph (CXR) is used for the initial assessment of the lungs, mediastinum and bones.

• Posteroanterior (PA) view – patient upright, on full inspiration with the scapulae moved laterally, so that the lungs are not obscured (Fig. 6.1)

• Lateral view (Fig. 6.2)

• Anteroposterior (AP) view – patient either supine or sitting; on this view there is magnification of the heart and mediastinum and the clavicles obscure the lung apices

• Apical lordotic view – the X-ray beam is angled superiorly 15–20° so the clavicles and first ribs are projected above the lung apices

• Expiration films are used to assess air trapping.

Cross-sectional imaging

Computed tomography (CT)

CT provides improved spatial resolution because of lack of overlap of structures. The use of intravenous contrast medium improves the demonstration of vessels.

Multidetector CT produces excellent multi planar reformats and other post-processing can be undertaken.

The data are viewed at different windows and levels for air and soft tissue.

Air-containing structures:

• WW 1500 HU

• WL –600 HU.

Soft tissues and vessels:

• WW 300–500 HU

• WL 30–50 HU.

High-resolution CT (HRCT) is used mainly to assess diffuse lung disease. Thin sections minimize partial volume effects and the high-resolution reconstruction algorithm provides edge enhancement.