Final answer:
The distance difference between the left and right pedicles to the spinous process in an AP Lumbar projection is likely caused by over-rotation.
Step-by-step explanation:
The distance from the left pedicles to the spinous process is narrower than the same distance from the right pedicles to the spinous process in an AP Lumbar projection. This can be caused by over-rotation. When there is over-rotation, the vertebrae are turned more than they should be, resulting in a difference in the width between the left and right sides. It is important to properly position the patient and ensure correct alignment to avoid over-rotation.