Unilateral hypertranslucent hemithorax

Last revised by Mohammad Taghi Niknejad on 30 Aug 2022

Unilateral hypertranslucent hemithorax has many potential causes. It may be the result of rotation away from an optimal position or because of pathology.


A unilateral hypertranslucent hemithorax may be caused by the positioning of the patient. Rotation away from the radiation beam alters the attenuation of the beam differently on either side of the thorax. The rotated side has shorter tissue distance which increases the x-ray transmission that passes through it. When the patient is turned to the right, the right side will be hypertranslucent. 

Rarely, grid cutoff may also mimic a unilateral hypertranslucency.


Where rotation is not thought to be the cause of the differential transradiancy, it may be useful to consider the potential causes by the structures they involve, in the order in which the radiation beam hit them. The age of the patient is also a factor that should be considered.

A helpful mnemonic is SAFEPOEM.

Chest wall defects - muscle abnormalities
Pleura and pleural space
Pulmonary (ventilation)
Vascular (perfusion)
See also

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: mastectomy
    Drag here to reorder.
  • Case 2: compensatory hyperinflation
    Drag here to reorder.
  • Case 3: pneumothorax
    Drag here to reorder.
  • Case 4: Poland syndrome
    Drag here to reorder.
  • Case 5: Heimlich valve and hemopneumothorax
    Drag here to reorder.
  • Case 6: re-expansion pulmonary edema
    Drag here to reorder.
  • Case 7: Swyer-James syndrome
    Drag here to reorder.
  • Case 8: pneumothorax
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.