Scientific research has established normal spinal configurations and normals for X-rays. An X-ray series should include an A.P. (or frontal) X-ray and a Lateral (or from the side) X-ray.
The A.P. should show a spine that is straight, without curves or deviations, and the center of the head should be positioned directly above the sacrum. The pelvis should be symmetrical. The top of the legs should be even.
The lateral should show four curves; the sacral, lumbar, thoracic and cervical curves. The sacral base angle should be between 34° and 42°. The C7 angle should be between 0-7°. The cervical curve angle should be between 34° and 43°. The lumbar curve angle should be between 35° and 47°. The head should be centered directly above the body.