Table 3. Dose constraints for the critical structures and target volumes.

Structure	Dose restriction
PTV coverage
Maximum dose	<110% prescribed dose
Coverage	V100% ≥95% PTV
OARs
Left lens & right lens planning risk organ volume (PRV)	Max dose <9 Gy
Optic chiasm	Max dose <50 Gy or V54 <1%
Left optic nerve & right optic nerve	Max dose <50 Gy or V54 <1%
Pituitary	Max dose <50 Gy
Brainstem	Max dose <54 Gy
Spinal cord	Max dose <45 Gy
Esophagus	V50 <50%
Heart	V30 <40%
Left lung & right lung	V20 <20%
Liver	V30 <40%
Left kidney & right kidney	V25 <30%
Bowel	Max dose <45 Gy

PTV, planning target volume.