Final answer:
The infraorbital meatal line (IOML) is used as a reference line positioned perpendicular to the image receptor during a lateral view of the sinuses, ensuring proper head extension.
Step-by-step explanation:
The reference line positioned perpendicular to the front edge of the image receptor (IR) when performing a lateral view of the sinuses is typically the infraorbital meatal line (IOML). To ensure proper extension of the head, the patient's skull is aligned such that the IOML is perpendicular to the IR. The orbitomeatal line (OML) is also used sometimes, requiring the head to be extended slightly more. Proper patient positioning and alignment are crucial for optimal imaging of the sinus anatomy, including the frontal sinus, maxillary sinus, sphenoid sinus, ethmoid air cells, and bony structures like the superior nuchal line, superior orbital fissure, and hard palate.