| Schedule | Constraint | Source |
|---|---|---|
| 60 Gy / 30 fx Standard course | Limit hotspots >60 Gy | eviQ 409 |
Consider reducing low and intermediate dose to the normal brain.
Quoted from eviQ 409, checked 2026-09-25. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 1 fx 15–24 Gy | V12 Gy 5, 10, >15 cc: about 10%, 15%, 20% risk of symptomatic necrosis | HyTEC brain (Milano 2021) |
| 3 fx 24–30 Gy | V20 Gy <20 cc | HyTEC brain (Milano 2021) |
| 5 fx 25–35 Gy | V24 Gy <20 cc | HyTEC brain (Milano 2021) |
Brain including all targets, summed over the course. Under 20 cc: <10% risk of necrosis or edema.
Quoted from HyTEC brain (Milano 2021), checked 2026-09-25. Full table with references →
The brain parenchyma inside the skull: the cerebral hemispheres, the cerebellum and the brainstem. Several small structures within it — the brainstem, optic chiasm, hippocampi and pituitary — are contoured and evaluated separately.
The brain controls thought, memory, speech, movement, sensation and vision.
The main late risk of high dose to normal brain is radionecrosis. After radiosurgery that risk tracks the volume of brain receiving a moderate dose — V12 Gy for a single fraction, V20 Gy for three fractions and V24 Gy for five in the HyTEC brain report — which is why a steep dose fall-off around each target matters so much in SRS planning (see the gradient index). With multiple metastases, the low doses from each target add up. In conventionally fractionated glioma treatment the concern is hotspots above the prescription in normal brain, and the volume of brain receiving low and intermediate doses.
The EPTN 2018 atlas contours the brain including the cerebellum, the cerebrospinal fluid and small brain vessels, and excluding the brainstem and the large venous sinuses (sigmoid, transverse and superior sagittal). It also leaves out the carotid canals and cavernous sinuses in the middle cranial fossa, which are easiest to see on contrast-enhanced T1 MRI. It recommends a CT brain window (WW/WL 350/40), or a planning-system auto-contour that is checked afterwards. A "supratentorial brain" structure is the brain minus the cerebellum.
Brouwer 2015 also excludes the brainstem but suggests CT bone settings, so the two atlases differ slightly in detail.
"Brain" is defined differently between sources, and the definition changes the number. HyTEC's V12 Gy, V20 Gy and V24 Gy include the target volumes; other sources subtract the GTV or PTV. Check the definition used by the source behind your limit, and name the structure so the difference is obvious (AAPM TG-263 gives standard names).
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.
Consensus CT delineation guidelines for head and neck organs at risk from eight cooperative groups, with anatomical descriptions and example images. Citation checked against Crossref; content not yet reviewed by DoseLab.
Recommendations for standardized naming of targets, organs at risk and dose-volume metrics. Section 9 sets out the DVH-metric nomenclature DoseLab follows: Vx (volume receiving at least dose x), Dx (minimum dose to the hottest sub-volume x), CVx and DCx (the "cold" complements), output units in square brackets (Gy or % of prescription; cc or % of the structure), and an EQD2Gy unit with the α/β written in parentheses — for example D90%(10)[EQD2Gy]. Section 10 asks that DVH metrics say whether a lower-dose PTV is segmented (excludes the higher-dose PTV) or not. Read in the AAPM report PDF.