Usually wavy contour. Bilobed but not always symmetrical. Heart - water dense seen usually with apex to left. Aortic knob may be seen through thymus on left. Pulmonary vessels - hila seen best on lateral.
Vessels extend to mid lung, tapering gradually.
Lungs - uniformly aerated. Appear black on most films. Upper thoracic vertebral bodies, scapulae, and clavicles seen well. Diaphragms - right and left equal. Usually seen at level of 9-10 ribs.