Brainscan version 5

Thin-sliced CT and high-resolution MRI imaging with 1.0 mm in slice thickness and gadolinium contrast were employed for contouring the gross target volume (GTV). CT to MRI fusion was used to eliminate the potential distortion of MRI images. GTV was calculated using the iPlan Radiotherapy Planning Software (iPlan RT Image 3.0.1, Brainlab, Germany). The Novalis treatment system (Brainlab, Heimstetten, Germany) along with the software Brainscan, version 5.31 (Brainlab, Germany) was used to design the treatment plan. The use of precise micro-multileaf collimators in the Novalis system is able to shape the dose and minimize exposure of surrounding normal tissues by a single isocenter. A 100% isodose line was employed to cover the target.
During treatment, the patients were immobilized with a Brainlab thermoplastic fixation mask and an oral bite. A stereoscopic X-ray system combined with an infrared position tracking system was used to ensure the correct position.
Oral dexamethasone (0.5 mg 4-times-a-day for 3 consecutive days in SSRS and 7 consecutive days in FSRT) was given to the patients from the first day of treatment to prevent acute toxic effects induced by radiosurgery.

One-millimeter-thick slices obtained through enhanced computed tomography (CT) and T1-weighted with contrast, T2-weighted, and/or Fluid-attenuated inversion recovery (Flair) magnetic resonance imaging (MRI) (1.5 tesla, Optima^TM MR450w GEM, GE healthcare, Chicago, IL, USA) from the vertex of the skull to the foramen magnum, scanned without a gap, were transferred through the network to the software Brainscan, version 5.31 (Brainlab, Munich, Germany) for treatment planning. The gross target volume (GTV) was calculated using the iPlan Radiotherapy Planning Software (iPlan RT Image 3.0.1, Brainlab, Munich, Germany). SRS was conducted using the Novalis treatment system (Brainlab, Heimstetten, Germany). The dose applied to the periphery of the tumor ranged from 1500 to 2250 centigray (cGy), and a 100% isodose line was employed to encompass the tumor margin (Figure 1).

Patients were immobilized in a thermoplastic flat shell (Klarity) with infrared markers for image guidance. Contrast-enhanced computed tomography (CT) images were acquired with a Light Speed RT instrument (GE Healthcare) at a slice thickness of 1.25 mm. Treatment plans were developed with BrainSCAN version 5.3.1 (BrainLAB), iPlan RT Dose version 4.5.1 (BrainLAB), or Eclipse version 8.6 (Varian Medical Systems). Contrast-enhanced CT images were fused with contrast-enhanced magnetic resonance imaging (MRI) images on a radiotherapy planning system.
Thirty-five patients underwent radiotherapy using the Novalis system with 6-MV linear accelerator, m3 micro-multileaf collimator, the ExacTrac X-ray system, and the Robotic Tilt Motion mounted on the Exact Couch top (BrainLAB). Five patients were treated with the Vero4DRT (Hitachi, Ltd.), and one patient was treated with the Clinac iX (Varian Medical Systems).
Gross tumor volume (GTV) was defined as the volume of the tumor on contrast-enhanced T1-weighted MRI. The clinical target volume (CTV) was defined as the GTV with a thickened dural tail. The planning target volume (PTV) was defined as the CTV plus a 1–2-mm margin in all directions. CFSRT was performed using multiple dynamic conformal arc therapy (DCAT) or by intensity-modulated radiotherapy (IMRT). The PTV was covered by 90% of the prescribed dose in both the DCAT and IMRT plans.