Table 2 Informal range modulation guidelines employed in our clinic

Single beam being employed for more than a few fractions.

Three ranges rather than two are used.

1. Full posterior fossa boost with full cochlear sparing.

2. Boost for germinoma after whole ventricular radiation often via a posterior beam.

Three or more main angles are being used and the patient is awake meaing six possible fields may need to be delivered.

One of two ranges for each beam angle is treated per day with care to avoid coincidental beam ends. Ranges alternate each day.

1. Brain tumors.

2. Pelvic tumors.

3. Spine tumors in some cases.

Base of skull tumors.

The patient has had prior radiation.

We will sometimes use three ranges rather than two when super critical structures are involved.

1. Ependymoma retreatment with the brainstem.

2. Salvage glioma cases with beams ending in eloquent brain.

3. Retreatment patients with a distant history of radiation necrosis with new cancer in similar locations.

Two or more beams end in the same point or points.

Beams are split into range mod pairs and care is used to look at each end point set for each day to avoid overlaps.

1. Fourth ventricular ependymoma.

2. Vertex beams use can hide this issue and great care is used in plan review to look for “in corner” doses.