| Schedule | Constraint | Source |
|---|---|---|
| 40.05 Gy / 15 fx or 42.56 Gy / 16 fx | V16 Gy <15% | RTOG 1005 |
| V4 Gy <50% | RTOG 1005 | |
| 26 Gy / 5 fx FAST-Forward | V8 Gy <15% | FAST-Forward |
Tangents: central lung distance <3 cm, ideally ≤2 cm.
Quoted from eviQ 3650, checked 2026-09-23. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| All schedules 40.05 Gy/15 fx · 30 Gy/5 fx · 26 Gy/5 fx | V30% ≤10% (ideal), ≤15% (acceptable) | ASTRO PBI 2023 |
Quoted from eviQ 3658, checked 2026-09-23. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 50 Gy / 25 fx | V20 Gy ≤15% (ideal), ≤20% (acceptable) | RTOG 1005 |
| V5 Gy ≤50% (ideal) | RTOG 1005 | |
| 26 Gy / 5 fx FAST-Forward | V8 Gy <15% | FAST-Forward |
25 fx limits are from a whole-breast tangent trial. With nodes, V20 Gy <30% applies — see the regional nodal page.
Quoted from RTOG 1005 and eviQ 1925, checked 2026-09-23. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 45–50 Gy / 25 fx 1.8–2 Gy per fraction | V20 Gy <30% | Yim 2015 |
| V5 Gy <70% | NSABP B-51 | |
| 40 Gy / 15 fx | V17 Gy <35% (combined plans) | SKAGEN Trial 1 |
15 fx: dose from the breast or chest wall and nodal plans combined.
Quoted from eviQ 1924, checked 2026-09-23. Full table with references →
The lung on the same side as the treated breast or chest wall. Its anterior surface sits directly under the chest wall, so a thin strip of lung is inside almost every tangential field.
Radiation pneumonitis and fibrosis are the concern, and the lung behaves as a parallel organ — so breast lung limits are written as Vx metrics: how much of the lung receives a given dose. The limits loosen when nodes are treated because the supraclavicular and internal mammary fields add lung volume, and they differ with fractionation, so each schedule has its own values.
For tangents, there is also a geometric check: the central lung distance — how deep the field edge reaches into lung on the central axis — rather than a dose metric.
Contour the whole ipsilateral lung (auto-thresholding does most of it); breast lung limits apply to the single lung, not both lungs combined. The Kong thoracic atlas covers lung contouring.
A thoracic organ-at-risk contouring atlas with discussion of dose limits, covering the lung, proximal bronchial tree, esophagus, spinal cord, ribs and brachial plexus. A published letter in response discusses esophageal delineation.