Radiotherapy must begin within 4 weeks after surgery. One treatment of 2.0 Gy will be given daily, 5 days per week, (over six weeks) for a total of 60.0 Gy. All portals shall be treated during each treatment session. Doses are specified as the target dose, which shall be to the center of the target volume.

Localization, Simulation, and Immobilization

The patient shall be treated in the supine or other appropriate position for the location of the lesion. A head-holding device that is transparent to x-rays must ensure adequate immobilization during therapy and ensure reproducibility. The target volume for both the initial volume and the conedown volume shall be based on the preoperative CT/MRI. The initial target volume shall include the contrast-enhancing lesion and surrounding edema (if it exists) demonstrated on CT/MRI plus a 2.0 centimeter margin. If no surrounding edema is present, the initial target volume should include the contrast-enhancing lesion plus a 2.5 centimeter margin.

This initial target volume will be treated to 46.0 Gy in 23 fractions, 2.0 Gy per fraction. After 46 Gy, the conedown target volume should include the contrast-enhancing lesion (without edema) on the pre-surgery CT/MRI scan plus a 2.5 centimeter margin. The conedown volume will be treated to an additional 14.0 Gy in 7 fractions, 2.0 Gy per fraction. This will bring the total target dose to 60 Gy in 30 fractions.

Dose Limitations to Critical Structures

The lens and cervical spine must be shielded from the direct beam at all times. When possible to do without shielding gross tumor, attempts should be made to limit the dose to the optic chiasm to 60 Gy, the retina of at least one eye (but preferably both) to 50 Gy, and the brain stem to 60 Gy. When the optic chiasm must be included in the full dose, there may be a finite unknown risk of developing blindness.