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  Anteroposterior, inspired.
  Original image.
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  Lateral, inspired.
  Original image.
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  Anteroposterior, expired.

These are two X-rays taken at the same time of a 31 year old woman who had a port inserted for chemotherapy against breast cancer (hence, both breasts have been surgically removed). During inspiration, only subtle pneumothorax is seen in the apical part of the left thoracic cavity. It can practically be diagnosed only by the absence of vascularity in the most apical lung segment. It is seen more clearly posteriorly on lateral X-ray. During expiration, the pneumothorax takes up approximately 50% of the cavity.