What anatomical landmark is used to identify the location for the central ray in lateral sacrum projection?

The identification of the sacral landmark for centering the central ray during a lateral sacrum projection is crucial for obtaining accurate imaging. The posterior superior iliac spines (PSIS) serve as the primary anatomical reference point in this projection. When positioning the patient, the PSIS can be palpated and located on each side of the lower back, serving as a reliable guide because it aligns with the sacral region of the spine.

Positioning the central ray at the level of the PSIS ensures that it intersects the sacrum appropriately, facilitating a clear view and accurate assessment of the sacral structures on the X-ray. This approach helps radiographers produce images that can highlight any potential issues within the sacral area effectively. Other landmarks, such as the sacral foramina, SI joint, and iliac crest, are useful in other radiographic procedures but are not recommended for centering the lateral sacrum projection, as they may not align optimally with the sacrum itself.