Examples for clinical target volume (CTV) delineation (nerves at risk are shown in yellow, CTVs in red)
3a-CTV encompassing the supraorbital nerve (V1) which courses in the roof of the orbit (superior to the superior rectus muscle), major branches of V1, the skin innervated by V1 and the cavernous sinus.
3b-CTV encompassing the infraorbital nerve (V2) in the infraorbital canal, the skin innervated by V2 and the cavernous sinus
3c, d-CTV encompassing preauricular skin, CN VII, the Auriculotemporal nerve (ATN), V3 and cavernous sinus. The volume named “cochlea” (3c) contains both a target (CN VII), and the organ at risk. The course of the Greater superficial petrosal nerve (GSPN) is indicated by broken line.