Single arc volumetric-modulated arc therapy is sufficient for nasopharyngeal carcinoma: a dosimetric comparison with dual arc VMAT and dynamic MLC and step-and-shoot intensity-modulated radiotherapy

Table 4 Comparison of delivery efficiency in all four radiotherapy plan groups

	VMAT1	VMAT2	dIMRT	ssIMRT	p _GLM-u	p _{VMAT1 -VMAT2}	p _{VMAT1 -dIMRT}	p _{VMAT1 -ssIMRT}	p _{VMAT2 -dIMRT}	p _{VMAT2 -ssIMRT}	p _{dIMRT -ssIMRT}
MUs	1232.1 ± 146.2	1349.9 ± 133.8	1292.2 ± 120.7	1090.2 ± 91.1	<0.001	0.001	0.067	<0.001	0.079	<0.001	<0.001
Time (min)	2.7 ± 0.2	3.9 ± 0.3	5.7 ± 0.2	14.1 ± 1.0	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
Mean dose rate (MU/min)	494.0 ± 38.6	379.6 ± 30.1	249.8 ± 17.9	86.6 ± 5.1	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
Control points	161.4 ± 13.1	187.0 ± 30.9	126.6 ± 10.2	138.0 ± 10.4	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.223
plan calculation time (hour)	5.6 ± 1.4	4.8 ± 1.2	0.8 ± 0.3	0.8 ± 0.4	<0.001	0.092	<0.001	<0.001	<0.001	<0.001	0.945

GLM-u: general linear model-univariate; VMAT1: single arc VMAT, VMAT2: dual arc VMAT; dIMRT: dynamic MLC IMRT; ssIMRT: step-and-shoot IMRT. “Bold numbers” means that p value has a statistically significance.

ISSN: 1748-717X