<prompt> Increased radiolucency of one sided hemithorax may be caused by all exceptObstructive EmphysemaPneumothoraxExpiratory filmPatient rotation  <response>: C i.e. Expiratory film How can a normal expiratory film leads to increased radiolucency of hemithorax? So the answer is very obvious. Ted Radiolucency of one side means there is UL lung pathology. Obst. Emphysema UL Pneumothorax may lead to UL lung collapse radiolucency. Patient rotation may also lead to false impression of UL radiolucency. But expiration film in normal conditions may never be a cause of this. Causes of UL Radiolucent Hemithorax Always remember that decreased 11L lung mass as in pulmonary agenesis pulmonary hypoplasia, collapse pneumonectomy are the causes of UL radiodense hemithorax with IL mediastinal displacement. 