Chest radiograph zones

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:

• apical zone: above the clavicles
• upper zone: below the clavicles and above the cardiac sillhouette
• mid zone: the level of the hilar structures
• lower zone: the bases

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: right and left behind the heart
• retrodiaphragmatic: right and left behind the hemidiaphragms 

See also

• bronchopulmonary segmental anatomy