Dose plan of gamma knife radiosurgery by three-dimensional CISS images localized on MRI and CT under stereotactic conditions for trigeminal neuralgia. CISS = Interference in steady state; MRI = Magnetic resonance imaging; CT = Computed tomography. The cisternal portion of the trigeminal nerve, close to the Gasserian ganglion, was irradiated by a maximum dose of 85 Gy, using a single 4 mm collimator (yellow circle showing 90% isodose line and green circle showing 16 Gy isodose).