Imaging of the treatment plan. The dose planning is displayed in axial CISS images fused with computed tomography (CT) bony window ( A ), axial CT bony window ( B ), coronal CISS images fused with CT bony window ( C ), and sagittal CISS images fused with CT bony window ( D ). Following Leksell G frame application under local anesthesia, an MRI and a CT scan were performed for stereotactic purposes. The MRI included a high-resolution, 0.5 mm ³ T2 CISS sequence and a 3D T1 MPR sequence on a 1.5 T Siemens MR machine. A single 4-mm isocenter was positioned 7–8 mm anterior to the nerve emergence from the pons (retrogasserian target) on the cisternal portion of the right trigeminal nerve. A dose of 90 Gy was prescribed at the 100% isodose point. The treatment time was 55 minutes, which translates to a biologically effective dose (BED) of 2390 Gy2.47. CISS, Constructive interference in steady state; MPR, multiplanar reformation.