Where should the central ray be directed for a lateral lumbar X-ray?

For a lateral lumbar X-ray, the central ray should be directed approximately 1 inch above the iliac crest. This is because the lumbar vertebrae typically lie just below this landmark, and placing the central ray at this height ensures that the X-ray field encompasses the majority of the lumbar spine's anatomy, including the vertebral bodies and intervertebral spaces. It optimally positions the X-ray beam to capture a clear image of the area of interest, while also allowing for adequate visualization of any potential pathologies present in the lumbar region.

The selection of this positioning is particularly important as it helps to minimize distortion and scatter, maximizing image quality for diagnostic purposes. Proper alignment based on anatomical landmarks like the iliac crest is a key principle in radiographic positioning, ensuring consistent and accurate results.