Which of the following is correct for an AP projection of the upper airway?

For an anteroposterior (AP) projection of the upper airway, positioning is crucial to achieve a clear and diagnostic image. When the acanthiomeatal line is positioned perpendicular to the image receptor, it helps align the structures of the upper airway appropriately. This alignment minimizes distortion and ensures that critical anatomical parts, such as the nasal cavity, oropharynx, and larynx, are visualized correctly.

Maintaining the correct positioning requires that the patient’s head is positioned so that the acanthiomeatal line, which is an imaginary line drawn from the acanthion (the junction of the nose and upper lip) to the midpoint of the orbit (the eye socket), is vertical. This orientation ensures that the upper airway structures are clearly depicted without overlap or misalignment.

The other options relate to different anatomical orientations or projections that do not apply to the specific requirements of the AP projection for the upper airway. For example, aligning the orbitomeatal line perpendicular is typically associated with lateral projections. Meanwhile, placing the midsagittal plane parallel to the image receptor would alter the required perspective for an AP view, potentially leading to inaccuracies in the representation of the upper airway. Lastly, ensuring the glabella (the smooth