Table 2.

Summary of the comparison results for the OARs.

OAR\Endpoint (NTCP parameters)	Constraints	Parameter	7F‐IMRT	DA‐VMAT	p‐value
Brain stem\necrosis (7, 3, 65, 3)	${\mathrm{D}}_{max}\le 54\text{Gy}$	${\mathrm{D}}_{max}$	$52.5\pm 2.0\hspace{0.17em}(49.9–55.7)$	$50.3\pm 1.4\hspace{0.17em}(47.7–51.9)$	$<0.05$
		EUD	$31.9\pm 1.1\hspace{0.17em}(29.7–32.7)$	$32.7\pm 3.0\hspace{0.17em}(27.1–35.6)$	n/s
		NTCP	$0.0\pm 0.0\hspace{0.17em}(0.0–0.0)$	$0.0\pm 0.0\hspace{0.17em}(0.0–0.0)$	n/s
Spinal cord\myelitis (7.4, 4, 66.5, 3)	${\mathrm{D}}_{max}\le 45\text{Gy}$	${\mathrm{D}}_{max}$	$40.1\pm 0.9\hspace{0.17em}(38.8–41.6)$	$43.7\pm 1.6$(40.8–45.9)	$<0.05$
		EUD	$21.9\pm 2.4\hspace{0.17em}(18.5–24.3)$	$23.9\pm 3.8\hspace{0.17em}(18.9–28.0)$	n/s
		NTCP	$0.0\pm 0.0\hspace{0.17em}(0.0–0.0)$	$0.0\pm 0.0\hspace{0.17em}(0.0–0.0)$	n/s
Lt parotid gland\xerostomia (1, 2.2, 28.4, 8)	${\mathrm{D}}_{mean}\le 26\text{Gy}$	${\mathrm{D}}_{mean}$	$33.5\pm 0.6\hspace{0.17em}(32.6–34.8)$	$31.1\pm 1.3\hspace{0.17em}(28.9–34.0)$	$<0.05$
	${\mathrm{V}}_{30}\le 50\%$	${\mathrm{V}}_{30}$	$39.1\pm 3.5\hspace{0.17em}(34.6–45.8)$	$36.6\pm 3.4\hspace{0.17em}(30.5–42.6)$	$<0.05$
		EUD	$27.2\pm 0.5\hspace{0.17em}(26.8–27.9)$	$25.9\pm 1.0\hspace{0.17em}(24.5–27.4)$	$<0.05$
		NTCP	$39.4\pm 4.1\hspace{0.17em}(33.2–45.7)$	$31.2\pm 5.2\hspace{0.17em}(24.0–40.0)$	$<0.05$
Rt parotid gland\xerostomia (1, 2.2, 28.4, 8)	${\mathrm{D}}_{mean}\le 26\text{Gy}$	${\mathrm{D}}_{mean}$	$32.1\pm 2.1\hspace{0.17em}(28.8–37.4)$	$30.1\pm 2.0\hspace{0.17em}(27.3–34.1)$	$<0.05$
	${\mathrm{V}}_{30}\le 50\%$	${\mathrm{V}}_{30}$	$41.8\pm 3.1\hspace{0.17em}(37.3–47.8)$	$34.6\pm 2.9\hspace{0.17em}(29.5–39.7)$	$<0.05$
		EUD	$26.0\pm 2.5\hspace{0.17em}(23.0–28.6)$	$25.5\pm 2.4\hspace{0.17em}(21.7–28.9)$	n/s
		NTCP	$33.1\pm 8.2\hspace{0.17em}(14.0–45.0)$	$31.3\pm 8.3\hspace{0.17em}(9.0–42.0)$	n/s
Lt lens\cataract (3, 1, 18, 7)	${\mathrm{D}}_{max}\le 10\text{Gy}$	${\mathrm{D}}_{max}$	$8.0\pm 2.9\hspace{0.17em}(3.5–14.6)$	$7.6\pm 2.6\hspace{0.17em}(3.1–12.5)$	n/s
		EUD	$5.5\pm 1.9\hspace{0.17em}(2.2–7.5)$	$4.6\pm 2.1\hspace{0.17em}(1.8–6.9)$	n/s
		NTCP	$1.3\pm 1.2\hspace{0.17em}(0.04–2.7)$	$0.8\pm 0.8\hspace{0.17em}(0.01–1.9)$	n/s
Rt lens\cataract (3, 1, 18, 7)	${\mathrm{D}}_{max}\le 10\text{Gy}$	${\mathrm{D}}_{max}$	$7.6\pm 2.9\hspace{0.17em}(3.8–12.4)$	$8.1\pm 2.9\hspace{0.17em}(3.4–14.5)$	n/s
		EUD	$5.3\pm 1.8\hspace{0.17em}(2.1–7.7)$	$5.1\pm 2.5\hspace{0.17em}(2.0–7.8)$	n/s
		NTCP	$1.1\pm 1.0\hspace{0.17em}(0.04–2.8)$	$1.3\pm 1.3\hspace{0.17em}(0.01–2.8)$	n/s
Left side eye	${\mathrm{D}}_{max}\le 45\text{Gy}$	${\mathrm{D}}_{max}$	$24.7\pm 7.4$(16.7–40.7)	$24.0\pm 6.8\hspace{0.17em}(15.2–37.8)$	n/s
Right side eye	${\mathrm{D}}_{max}\le 45\text{Gy}$	${\mathrm{D}}_{max}$	$22.6\pm 5.0\hspace{0.17em}(15.0–32.6)$	$22.0\pm 6.3\hspace{0.17em}(12.8–34.2)$	n/s
Chiasm	${\mathrm{D}}_{max}\le 54\text{Gy}$	${\mathrm{D}}_{max}$	$54.8\pm 17.2\hspace{0.17em}(25.5–71.4)$	$52.7\pm 15.7\hspace{0.17em}(32.0–70.1)$	n/s
Mandible	${\mathrm{D}}_{1\text{cc}}\le 75\text{Gy}$	${\mathrm{D}}_{1\text{cc}}$	$68.6\pm 5.6\hspace{0.17em}(58.3–74.0)$	$66.7\pm 4.6\hspace{0.17em}(56.3–70.1)$	n/s
Oral cavity	${\mathrm{D}}_{mean}\le 40\text{Gy}$	${\mathrm{D}}_{mean}$	$49.2\pm 7.3\hspace{0.17em}(40.4–60.3)$	$51.0\pm 3.8\hspace{0.17em}(43.2–58.3)$	n/s
Healthy tissue	ALAP	${\mathrm{D}}_{mean}$	$33.3\pm 3.1\hspace{0.17em}(27.4–37.8)$	$31.7\pm 4.0\hspace{0.17em}(26.3–38.6)$	n/s
		DoseInt	$133.7\pm 22.1\hspace{0.17em}(102.9–159.8)$	$128.0\pm 25.7\hspace{0.17em}(97.1–159.6)$	$<0.05$

Abbreviations: OAR: organ at risk; IMRT: intensity‐modulated radiotherapy; 7F‐IMRT: 7‐field fixed‐beam IMRT; DA‐VMAT: dual arcs with the SmartArc technique; Lt: left side; Rt: right side; Oral cavity: excluding planning target volume (PTV); DoseInt: Integral Dose [${10}^3$ Gy·Litre]; EUD: equivalent uniform dose; NTCP: normal tissue complication probability (%), NTCP parameters used are listed in the parenthesis: $(\mathrm{a},{\gamma }_{50},{\text{TD}}_{50},\alpha /\beta );{\mathrm{D}}_{max}$; ${\mathrm{D}}_{max}$ : values were the maximal doses for a fixed volume fraction (V); ${\mathrm{D}}_{mean}$ : values were the mean doses for a fixed volume fraction (V); ${\mathrm{V}}_{30}$: volume receiving 30 Gy for the 50% of parotid; n/s: not statistically significant; statistical significance $(p<0.05)$ is reported from a paired two‐side Wilcoxon signed‐rank test; numbers in fields were shown in the format of $mean\pm \text{standard}\hspace{0.17em}\text{deviation}$ (range); ALAP: as low as possible.