Where is the central ray directed for a lateral Thoracic spine radiograph?

• A. T7
• B. T12
• C. C7
• D. L1

Answer: (A)

Centering the beam at T7 for a lateral thoracic spine study places the exposure through the mid-thoracic region, which is the area of interest. T7 roughly corresponds to the inferior angle of the scapula, providing a reliable external landmark to position the patient so the entire thoracic spine is included with minimal magnification. Directing the CR there also helps ensure the beam passes through the midline of the thorax and the spine is captured without excessive rotation. If you aimed higher, toward C7, you’d miss much of the thoracic vertebrae; aiming lower, toward T12 or L1, would miss the upper thoracic region and fail to visualize the full thoracic spine. The ray should be perpendicular to the IR to maintain proper image geometry.