For an AP projection of the thoracic spine, where should the central ray be directed?

• A. 2 inches above the clavicle
• B. Midway between the xiphoid and the jugular notch
• C. At the level of T7
• D. At the inferior margin of the diaphram

Answer: (B)

Center the central ray at the level of T7. A reliable way to locate that is by drawing a horizontal plane midway between the jugular notch and the xiphoid process; that point corresponds roughly to the thoracic level of T7. Directing the beam there centers the mid-thoracic spine in the image, allowing the vertebral bodies and intervertebral spaces to be well visualized while avoiding obscuration from the shoulders or diaphragm. This placement is preferred over directing too high (which misses lower thoracic vertebrae) or too low (which could obscure upper thoracic anatomy or involve the diaphragm). Have the patient take a full inspiration and hold to help depress the diaphragms and improve visualization.