Why is a right anterior oblique (RAO) projection of the sternum typically performed?

The right anterior oblique (RAO) projection of the sternum is typically performed because it places the sternum over the uniform density of the heart. This positioning is particularly advantageous in radiography because it helps to minimize the amount of superimposition from surrounding structures, which can obscure the detail of the sternum.

In the RAO position, the sternum is angled in such a way that it provides a projection where it is more clearly delineated against the soft tissue density of the heart. This technique reduces the visual interference from the surrounding thoracic structures, allowing for a more accurate assessment of the sternum's anatomy. The uniform density of the heart helps create contrast that improves the visibility of the sternum, aiding in diagnostic evaluations for potential fractures or abnormalities.

While other positions and projections have their own benefits (such as visualization of lung fields or widening the field of view), they do not specifically address the clarity of the sternum in relation to the heart's density. Therefore, the RAO projection is preferred for its effectiveness in highlighting the sternum against the backdrop of the heart, enhancing clarity and diagnostic utility.