| Schedule | Constraint | Source |
|---|---|---|
| 45–50.4 Gy / 25–28 fx Pelvis ± nodal boost | Max <48 Gy | EMBRACE II |
When the para-aortic nodes are treated.
Quoted from EMBRACE II, checked 2026-09-30. Full table with references →
The spinal cord runs within the vertebral (spinal) canal from the medulla oblongata at the foramen magnum down to the conus medullaris in the upper lumbar spine. It is surrounded by cerebrospinal fluid and the thecal sac, all enclosed by the bony canal.
The spinal cord carries signals between the brain and the body — for movement, feeling and reflexes.
The cord behaves as a serial organ: damage to a short segment can interrupt function below it. Radiation myelopathy is rare but severe and irreversible, so cord limits are usually expressed as a maximum or near-maximum dose rather than a mean. In lung SBRT the cord is seldom close to a peripheral tumor, but paraspinal and posterior tumors can bring it into play, and it is routinely evaluated in conventionally fractionated thoracic plans. In breast treatment it matters only when the supraclavicular nodes are treated, and the cord would not be expected to come near its limit. In head and neck treatment the cord runs directly behind the neck targets along the whole length of the field, so it is evaluated in every plan, usually together with a planning risk volume. In brain treatment the upper cord matters for posterior fossa targets and for the lower edge of whole-brain and glioma fields; radiosurgery sources define it as the whole bony canal. In GI treatment the cord is evaluated for esophageal and pancreatic plans, where posterior beams pass close to it, and for liver SBRT near the spine.
In cervical cancer the cord is evaluated only when the para-aortic nodes are treated; pelvic fields stay below it.
Sources differ on what is contoured: some define the cord itself, others use the bony spinal canal as a reproducible surrogate. A constraint only makes sense when applied to the structure it was written for — check the definition in the source behind the limit you are using. For example, the contouring-instructions column in Timmerman 2022 Tables 8–11 describes its cord structure, and the Kong thoracic atlas below covers the cord for chest cases. Many clinics also add a PRV — whether and how is protocol- and institution-specific.
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.