Table 1. Dose constraints for the prescription dose of 70 Gy delivered in 10 fractions.

Critical structures	Maximum tolerated dose (Gy)
Spinal Cord*	28
Esophagus	44
Major airway	49
Heart	49
Brachial plexus	38.5
Major vessels	49
Stomach	44
Total lung †
V20	20
MLD	9.5

^*30 Gy acceptable in selected cases.

^†Total lung volume = total volume of both lungs minus that of the GTV.

V₂₀ is the % of the volume receiving 20 Gy. MLD: mean lung dose.