Where does the central ray enter for a submentovertex (SMV) projection?

The correct entry point for the central ray in a submentovertex (SMV) projection is at the midsagittal plane of the throat. This positioning is essential for capturing a clear view of the cranial base and the maxillary sinuses. The SMV projection aims to demonstrate the relationship of the mandible to the cranial base, thus requiring the central ray to enter at this specific anatomical landmark to achieve an optimal imaging perspective.

Positioning the central ray at the midsagittal plane of the throat helps ensure that the image is free of distortion, providing an accurate representation of the structures being examined. This entry point allows for a proper angle that effectively portrays the anatomy of the skull, especially for evaluating potential pathologies involving the sphenoid and ethmoid sinuses, along with the mandible.

Options referencing other entry points do not align with the standard technique for SMV projections, as they would not adequately capture the necessary anatomical details intended in this specific imaging procedure. Aiming the central ray at other locations could also lead to oblique angles that obscure vital structures.