Published on 01/04/2015 by admin

Filed under Radiology

Last modified 01/04/2015

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The chest X-ray (CXR)

A comprehensive description of the information that can be provided by the CXR requires a textbook all of its own.

Our companion book The Chest X-Ray : A Survival Guide1 will assist you to get the very best from this, the commonest radiological investigation in an Emergency Department (ED).

In this chapter we focus on the ten most common clinical questions that are asked of a CXR in the ED.

The standard radiographs

PA CXR. A lateral CXR in selected cases.

Normal anatomy

Frontal CXR—the lungs

Frontal CXR—cardiothoracic ratio

Most normal hearts have a cardiothoracic ratio (CTR) of less than 50% when assessed on a PA chest radiograph obtained in full inspiration2.

Cardiac silhouette. The left and right borders of the heart are well defined by the surrounding air in the lungs.

Lateral CXR—the lobes of the lung

The two fissures in the right lung divide the lung into three lobes.

The single fissure in the left lung divides the lung into two lobes.

The oblique fissure on each side is propeller shaped and consequently we only, and very occasionally, see a part of a fissure on a normal lateral CXR.

On the other hand, we will see most of the horizontal fissure on the lateral CXR because it is straight. We will often see this fissure on the frontal CXR for the same reason.


Analysis: the checklists

The frontal CXR

Four steps underpin accurate analysis.