Radiotherapy for high-grade glioma and glioblastoma, usually after surgery: IMRT or VMAT over six weeks with chemotherapy, or a shorter course for older or less fit patients. The main planning problems are an infiltrative target defined on MRI and small, serial organs — the brainstem, optic chiasm and optic nerves — sitting close to it.
The standard course for glioblastoma is 60 Gy in 30 fractions with temozolomide during and after radiotherapy, from the Stupp trial. For older or less fit patients, shorter courses are common: 40.05 Gy in 15 fractions, used with temozolomide in the Perry trial, and 25 Gy in 5 fractions, compared with 40 Gy in 15 in the IAEA trial.
The target can be treated as one volume to the full dose, as in the ESTRO-EANO guideline, or in two phases — a larger first volume that includes surrounding T2/FLAIR change, then a cone-down to the resection cavity and enhancing tumor — as in many US cooperative-group trials. Your protocol sets which, and the dose to each phase.
Organ limits change with the schedule, so the constraint table below has one column for the standard course and one for the short courses.
Treatment runs for three to six weeks near several small, dose-limiting structures, so setup and image fusion carry a lot of weight.
Supine with the head neutral in a thermoplastic mask, a neck support or vacuum bag, and arms by the sides.
The brainstem, optic chiasm and cochleae often sit within a centimeter or two of the target, so the head must return to the same position every day. Some patients find the mask difficult; anxiety is worth planning for at simulation.
A thin-slice CT covering the whole head, typically from the vertex to the upper cervical spine. IV contrast is considered when MRI can't be done.
The CT gives the electron density for dose calculation and the anatomy that the MRI is registered to. Thin slices help small structures such as the optic nerves, chiasm and cochleae.
Image fusion aligns an outside scan with the planning CT so the target can be drawn using information the CT doesn't show. For glioma this is pre- and post-operative MRI — contrast-enhanced T1 and T2/FLAIR — registered to the planning CT. One template also recommends fusing PET/CT when it is available.
The tumor, the resection cavity and the surrounding T2/FLAIR change are defined on MRI, not CT. Fusion is usually a rigid registration of the whole brain; checking it at the skull base and around the target matters, because every contour depends on it. Swelling and cavity shrinkage after surgery can change the anatomy, so a recent scan is preferred. One template asks that the fusion be done by a physicist, or a dosimetrist under a physicist's supervision, and reviewed by the physician.
Daily kV imaging or cone-beam CT matched to bone is recommended.
The skull gives a reliable match, and daily imaging is what allows small margins and PRVs around the optic structures and brainstem.
What each volume represents. Expansions and dose levels come only from your protocol.
After resection: the surgical cavity plus any residual enhancing tumor on post-contrast T1. After biopsy only: the enhancing tumor.
Post-operative MRI separates residual tumor from blood products and surgical change. Pre-operative imaging shows where the tumor was, which helps when the cavity has collapsed or shifted.
An expansion of the GTV for infiltrating tumor, edited back at anatomical barriers such as the skull, falx and tentorium, and extended along white-matter tracts where spread is likely.
Gliomas infiltrate beyond what imaging shows. Whether T2/FLAIR change is included depends on whether it looks like tumor infiltration or edema — the main difference between approaches, and a decision for the physician.
The CTV expanded for setup uncertainty.
Where the PTV overlaps the brainstem or optic structures, the protocol's priorities decide whether coverage or the organ limit gives way — often handled with a separate evaluation or reduced-dose PTV.
Expansions of the brainstem, optic chiasm, optic nerves and spinal cord. Concept page →
These serial structures have maximum-dose limits close to the prescription, so a PRV gives a buffer for setup error. Protocols often give one limit for the organ and a slightly higher one for its PRV.
Click an organ for its anatomy, why it matters and contouring resources. Superscripts link to the study behind each value.
| Organ | 60 Gy / 30 fxStandard course | 40.05 Gy / 15 fxShort course; also 34 Gy / 10 fx and 25 Gy / 5 fx |
|---|---|---|
| BrainConsider reducing low and intermediate dose to the normal brain. |
| — |
| BrainstemNot applicable when the tumor involves the brainstem. |
| |
| Optic Chiasm & Optic NervesChiasm and each optic nerve. Neuropathy risk rises above 55–60 Gy. |
| |
| Spinal Cord |
| |
| CochleaKeep as low as possible to reduce hearing loss. | — | |
| Globes (Eyes) |
| — |
| LensUp to 20 Gy to the front of the eye may be accepted in selected cases. |
|
|
| HippocampusWhere possible, spare the hippocampus opposite the tumor. Not applicable when it is involved. |
| — |
| Pituitary GlandInclude the pituitary stalk. |
| — |
Values quoted from eviQ 409 (last reviewed 28 March 2024; review due 30 June 2026) and eviQ 410 (last reviewed 28 March 2024; review due 30 June 2026), checked by DoseLab on 2026-09-25. Verify against your protocol, institutional policy and physician directive before clinical use.
Search all CNS / brain constraints in the Constraint Finder →
Phase 3 trial showing that temozolomide given with and after radiotherapy (60 Gy in 30 fractions) improved survival in glioblastoma compared with radiotherapy alone. Citation checked against Crossref.
Phase 3 trial in patients 65 or older with glioblastoma: 40 Gy in 15 fractions with temozolomide improved survival compared with the same radiotherapy alone. Citation checked against Crossref.
IAEA randomized trial in elderly and/or frail patients with glioblastoma comparing 25 Gy in 5 fractions with 40 Gy in 15 fractions; survival was similar. Citation checked against Crossref.
ESTRO-EANO guideline for glioblastoma radiotherapy: target volume definition (a single CTV around the resection cavity and residual tumor), dose and fractionation, and planning details. Citation checked against Crossref; content not yet reviewed by DoseLab.
European Particle Therapy Network consensus on dose constraints for brain and skull-base organs at risk in conventionally fractionated treatment, written in EQD2 with the endpoint behind each limit. Citation checked against Crossref; content not yet reviewed by DoseLab.
The European Particle Therapy Network contouring atlas for brain organs at risk on CT and MRI, with anatomical descriptions and boundaries. Citation checked against Crossref.
Illustrated delineation guidance and dose constraints for brain organs at risk in adults and children. Citation checked against Crossref; content not yet reviewed by DoseLab.
The brainstem chapter of the 2010 QUANTEC supplement, reviewing dose–volume data for brainstem injury. Citation checked against Crossref; content not yet reviewed by DoseLab.
The optic nerve and chiasm chapter of the 2010 QUANTEC supplement. Citation checked against Crossref; content not yet reviewed by DoseLab.
Endorsed eviQ protocol for glioblastoma (IDH-wildtype, CNS WHO grade 4): 60 Gy in 30 fractions with IMRT or VMAT and concurrent chemotherapy. Its organs-at-risk table covers the brain, brainstem, optic chiasm and nerves, cochlea, globes, retina, lens, hippocampus, inner ear, lacrimal gland, pituitary and spinal cord, with PRV limits for the brainstem, optic structures and cord. DoseLab's glioma table reproduces selected values with the primary source eviQ credits for each. Its review was due 30 June 2026, so a newer version may appear.
Endorsed eviQ protocol for short-course radiotherapy of grade 3–4 astrocytoma and glioblastoma in older or less fit patients: 40.05 Gy in 15 fractions, 34 Gy in 10 fractions or 25 Gy in 5 fractions, with or without chemotherapy. Its organ table keeps the brainstem, optic structures, retina and cord below the prescription dose and gives a lens limit. Its review was due 30 June 2026.