What are the findings on lateral projection?
On lateral projection the right hemidiaphragmatic outline is lost posteriorly and the lower thoracic ribs appear denser than normal (they are usually more radiolucent than the upper vertebrae).
Is the film well centered? How do you assess this?
Yes. Look at the spinous processes. They should be equidistant from the pedicles, the medial ends of the clavicles and the anterior ends of the ribs.
Chest x-ray demonstrates complete collapse of the right lower lobe, with obliteration of the silhouette of the right hemidiaphragm on both PA and lateral projections. There is shift of the mediastinum and trachea to the right, and elevation of the hemithorax.