TABLE 2.

OAR dose constraints from literature review

Dose Constraint Criteria	OAR	Assumptions	Dose limits	Reference
Absolute dose limits	Cord	Assuming 50% recovery if retreatment ≥12 months	Keep cumulative BED 135 Gy2	[57, 58, 59]
	Brainstem	Assuming 50% recovery if retreatment ≥12 months	Cumulative Dmax <79 Gy Cumulative D1% ≤78 Gy	[57, 58, 59]
	Chiasm	Assuming 50% recovery if retreatment ≥12 months	Cumulative Dmax ≤78 Gy	[57, 58, 59]
Desirable dose limits	Optic nerve	Assuming 50% recovery if retreatment ≥12 months	Cumulative Dmax ≤78 Gy To consent for loss of vision with patient	[57, 58, 59]
	Carotid	Cumulative EQD2 ≤120 Gy	Avoid 1.5 Gy b.i.d if CCRT	[59, 62, 63]
	Temporal lobe		Cumulative D1cc ≤84.5 Gy	[57, 59, 61]

Abbreviations: EQD2: Equivalent dose in 2 Gray fractions, Dmax: Maximum dose received by an organ at risk, BED: Biological Equivalent Dose, D1%: Highest dose received by 1% of the organ at risk, D1cc: Highest dose received by 1cc of the organ at risk, b.i.d: Twice daily