Sternum and SC joints

RAO sternum

The sternum lies over the spine on a straight PA, so it is taken as a PA oblique, an RAO. Turn the patient 15 to 20 degrees, right side down, prone or erect. The RAO projects the sternum just left of the spine, over the even background of the heart. A large, deep chest needs less rotation, about 15 degrees, and a thin chest needs more, about 20 degrees. Center the CR perpendicular to the middle of the sternum, about 1 inch left of the spinous processes, midway between the jugular notch and the xiphoid. Use at least 40 inches and a breathing technique, low mA and a long exposure time of 1 to 3 seconds, while the patient breathes gently, so the ribs and lung markings blur.