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Chest radiograph zones

Last revised by Dr Daniel J Bell on 02 Aug 2021

The chest radiograph zones are useful when describing the location of pathology on a frontal chest radiograph.

The chest radiograph is a 2D representation of a 3D structure. Since the interfaces between the lobes are oriented obliquely, it is often not possible to determine which lobe pathology is located in or whether it is located anteriorly or posteriorly. Hence, describing the location of pathology using the four-zone technique is helpful:

It is recommended to use the zones loosely while reporting as the distinctions are arbitrary and do not correspond to anatomic structures 1.

Additional lung regions or zones that may be referred to on chest radiography include:

  • retrocardiac zone: behind the heart bilaterally
  • retrodiaphragmatic: behind the hemidiaphragms bilaterally

However, using the zonal terminology for the location of findings on chest CT is generally discouraged, as a more precise lobar +/- segmental site, can usually be provided.

See also

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Cases and figures

  • Figure 1: normal CXR
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  • Figure 2: apical zone
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  • Figure 3: upper zone
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  • Figure 4: mid zone
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  • Figure 5: lower zone
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