This appearance is termed a complete 'white out' due to the whole of one side of the thoracic cavity is opacified.

If one receives a radiograph of this nature some practical points to consider

- are there any prior radiographs it was evident on - it might be a pneumonectomy from years ago. 

- are there any changes to the thoracic cage to suggest a thoracotomy to indicate a pneumonectomy

- which direction has the trachea gone.  Pulled towards suggests a pneumonectomy or total lung collapse, pushed suggests a large effusion or rarely a huge thoracic mass.

Typically if new a CT is performed and reveals all.

Check out the position of the trachea on the range of pathologies here.