On a normal lateral chest film the silhouette of the left diaphragm 2- can be seen from posterior up to where it is bordered by the heart, which has the same density (blue arrow). One should be able to follow the contour of the right diaphragm -1- from posterior all the way to anterior, because it is only bordered by the lung. Here we cannot follow the contour of the right diaphragm all the way to posterior, which indicates that there is something of water-density in the right lower lobe (red arrow). #Clinical #Radiology #CXR #Pneumonia #RLL #Lateral #SilhouetteSign #RadiologyAssistant
