Table 3.

The comparison of plan quality using dose‐volume‐histogram (DVH) indices.

DVH index	VMAT	IMPT	P‐value
CTVhigh ${\text{D}}_{2{\text{cm}}^3}$ (normalized)	105%	104%	0.071
CTVhigh D5%–D95% (normalized)	4.0%	3.5%	0.12
CTVlow D95% (normalized)	103%	101%	0.11
Liver V30Gy[RBE] (%)	8.05%	3.97%	0.0023
Liver Dmean (Gy[RBE])	15.27	2.58	<0.0001
Lung Dmean (Gy[RBE])	8.55	3.73	<0.0001
Lung V5Gy[RBE] (%)	48.11%	15.61%	<0.0001
Lung V20Gy[RBE] (%)	10.32%	8.57%	0.50
Heart Dmean (Gy[RBE])	21.94	7.63	<0.0001
Heart V20Gy[RBE] (%)	51.06%	15.61%	<0.0001
Heart V30Gy[RBE] (%)	18.52%	11.48%	0.061
Heart V40Gy[RBE] (%)	8.38%	6.31%	0.21
Cord Dmax (Gy[RBE])	36.00	38.92	0.38
Cord ${\text{D}}_{0.03{\text{cm}}^3}$ (Gy[RBE])	35.05	37.49	0.48
Kidney V18Gy[RBE] (%)	3.88%	0.41%	0.27
Stomach V45Gy[RBE] (cm3)	79.92	45.71	0.093

CTV, clinical target volume; IMPT, intensity‐modulated proton therapy; VMAT, volumetric‐modulated arc therapy.

Bold values represent significant difference between IMPT and VMAT DVH indices.