Plain radiography

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

• Posteroanterior (PA) view – patient upright, on fullinspiration with the scapulae moved laterally, so that the lungs are notobscured (Fig. 6.1)

• Lateral view (Fig. 6.2)

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

• Apical lordotic view – the X-ray beam is angled superiorly15–20° so the clavicles and first ribs are projected abovethe 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 ofstructures. The use of intravenous contrast medium improves thedemonstration 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 diffuselung disease. Thin sections minimize partial volume effects andthe high-resolution reconstruction algorithm provides edgeenhancement.