CR should enter directly through which anatomical structure in SMV projection?

CR should enter directly through which anatomical structure in SMV projection?

• A. Nasion
• B. Sella turcica
• C. Glabella
• D. Zygomatic arch

Answer: (B)

In this projection the central ray is aimed along the midline of the skull to traverse the cranial base, so it passes through the sella turcica. Positioning is done with the head extended so that the infraorbitomeatal line is perpendicular to the image receptor, and the CR is directed perpendicular to that line, entering from under the chin and traveling upward to exit at the vertex. This alignment centers the beam through the midline structures of the skull base, including the sella turcica, which provides a symmetrical view of the cranial base and zygomatic arches. Entering through nasion, glabella, or the zygomatic arch would misalign the beam relative to the midline and distort the projection, reducing symmetry and obscuring the intended anatomy.

In this projection the central ray is aimed along the midline of the skull to traverse the cranial base, so it passes through the sella turcica. Positioning is done with the head extended so that the infraorbitomeatal line is perpendicular to the image receptor, and the CR is directed perpendicular to that line, entering from under the chin and traveling upward to exit at the vertex. This alignment centers the beam through the midline structures of the skull base, including the sella turcica, which provides a symmetrical view of the cranial base and zygomatic arches.

Entering through nasion, glabella, or the zygomatic arch would misalign the beam relative to the midline and distort the projection, reducing symmetry and obscuring the intended anatomy.