| Schedule | Constraint | Source |
|---|---|---|
| 60 Gy / 30 fx Standard course | Max <10 Gy (ideal) | Scoccianti 2015 |
| 40.05 Gy / 15 fx Short course; also 34 Gy / 10 fx and 25 Gy / 5 fx | Max <10 Gy | Scoccianti 2015 |
Up to 20 Gy to the front of the eye may be accepted in selected cases.
Quoted from eviQ 409 and eviQ 410, checked 2026-09-25. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 1 fx 15–24 Gy | As low as reasonably achievable | eviQ 3253 |
| 3 fx 24–30 Gy | As low as reasonably achievable | eviQ 3253 |
| 5 fx 25–35 Gy | As low as reasonably achievable | eviQ 3253 |
Quoted from eviQ 3253, checked 2026-09-25. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 30 Gy / 10 fx or 20 Gy / 5 fx | Max ≤6 Gy (ideal) | eviQ 1251 |
Target coverage should not be compromised to meet this.
Quoted from eviQ 1251, checked 2026-09-25. Full table with references →
| Schedule | Constraint | Source |
|---|---|---|
| 30 Gy / 10 fx NRG CC001 | Max ≤5 Gy (ideal) | eviQ 3882 |
Target coverage should not be compromised to meet this.
Quoted from eviQ 3882, checked 2026-09-25. Full table with references →
The transparent lens of each eye, behind the iris.
The clear lens behind the iris focuses light onto the retina. Clouding of the lens is a cataract.
The lens is one of the most radiosensitive tissues in the body: modest doses can cause cataract. Its limits are low compared with other head and neck organs, and they matter for nasopharynx, sinonasal and orbital targets. In whole-brain treatment the lateral beams run just behind the eyes, so beam divergence toward the lenses is a routine planning check.
The EPTN 2018 atlas describes the lens as a clearly visible, biconvex structure up to 10 mm across, between the vitreous and the iris, which is easy to contour on CT. It notes that the lens can move during treatment unless the patient is told where to look.
Brouwer 2015 does not contour the lens on its own — it is included in the anterior segment of the eyeball.
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.