In SMV projection, the central ray is directed through which landmark?

In SMV projection, the central ray is directed through which landmark?

• A. Mastoid tip
• B. Frontal bone
• C. Sella turcica
• D. Nasion

Answer: (C)

In SMV projection, the central ray is directed through the sella turcica. This basal view is taken with the head hyperextended so the vertex is up, and the beam is positioned to pass through the midline structure of the skull base. Directing the central ray through the sella turcica centers the exposure on the skull base, giving a symmetric, undistorted view of the cranial base and zygomatic arches while allowing the mandibular condyles and other basal structures to be seen clearly. The other landmarks—mastoids, frontal bone, or nasion—do not align with the required central path for this projection, so using them would shift the beam and reduce image quality.

In SMV projection, the central ray is directed through the sella turcica. This basal view is taken with the head hyperextended so the vertex is up, and the beam is positioned to pass through the midline structure of the skull base. Directing the central ray through the sella turcica centers the exposure on the skull base, giving a symmetric, undistorted view of the cranial base and zygomatic arches while allowing the mandibular condyles and other basal structures to be seen clearly. The other landmarks—mastoids, frontal bone, or nasion—do not align with the required central path for this projection, so using them would shift the beam and reduce image quality.