Question

A patient arrives at the emergency room following a motor vehicle accident and is complaining of pain in the mid-chest region. The emergency room physician orders a sternum x-ray but the patient must remain supine on the cart due to a possible spinal injury. What is the correct angle for the central ray to obtain the equivalent of an RAO sternum projection?

1) CR angled 15 to 20 degrees across the left side of the patient
2) CR angled 15 to 20 degrees across the right side of the patient
3) CR angled 30 to 40 degrees across the left side of the patient
4) CR angled 30 to 40 degrees across the right side of the patient

Answer 1

The correct angle for the central ray to obtain an RAO sternum projection while the patient is supine is 15 to 20 degrees across the left side of the patient.

Step-by-step explanation:

To obtain the equivalent of an RAO sternum projection with the patient in a supine position due to a possible spinal injury, the proper angle for the central ray (CR) is option 1: the CR angled 15 to 20 degrees across the left side of the patient. This angulation helps project the sternum clear of the shadow of the thoracic spine, providing a clearer image of the sternal structure for diagnostic purposes. Considering the sternum's anatomy, the appropriate CR angle is essential to visualize the area of interest - from the manubrium, through the sternal angle and the body, down to the xiphoid process. This approach takes into account the attachment of the second ribs to the sternal angle, the classification of the ribs, and the articulation with the thoracic vertebrae as described in the provided references.