Dosimetric comparison between VMAT plans using the fast-rotating O-ring linac with dual-layer stacked MLC and helical tomotherapy for nasopharyngeal carcinoma

Table 4 Comparison of normal tissue complication

Parameters	HT	HL_2arc	HL_4arc	P^a
Parameters	Median (IQR)			HT vs. HL_2arc	HT vs. HL_4arc	HL_2arc vs. HL_4arc
Esophagus	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	–	–	–
Parotid glands	24.82 (20.15, 29.66)	25.92 (21.11, 33.71)	22.45 (18.87, 27.87)	0.24	0.02	0.00
Oral cavity	6.18 (2.81, 11.15)	4.48 (1.63, 12.80)	5.06 (1.74, 9.06)	> 0.99	0.01	0.13
Spinal cord	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.13	0.54	0.08
Brain Stem	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.00 (0.00, 0.00)	0.68	0.08	> 0.99

HT, helical tomotherapy; HL_2arc, halcyon two arc; HL_4arc, halcyon four arc; IQR, interquartile range (Q1, Q3)
^aThe Wilcoxon signed rank test was used by the Bonferroni correction for multiple testing

ISSN: 1748-717X