Where is CR directed for the upright, PA projection of the chest?

In the upright posterior-anterior (PA) projection of the chest, the central ray (CR) is directed at the level of T7, which is an important anatomical landmark for accurately capturing the thoracic structures. T7 corresponds to the inferior margin of the scapula in a healthy adult, and this positioning ensures that the entire lung field is included in the image, while minimizing artifacts and obstructions.

Positioning the CR at T7 allows for optimal visualization of the lungs, heart, trachea, and other mediastinal structures. This area is also where the lungs naturally extend to during a full inhalation, thus providing a clear and representative view of the anatomy of interest. Effective placement of the CR is vital for high-quality radiographic imaging, and T7 is well established as the standard location for this procedure in upright chest radiography.