Table 2.

Dose to avoidance structures using volumetric-modulated arc therapy (VMAT) vs split-field intensity-modulated radiation therapy (SF-IMRT). There was a statistically significant decrease in maximum (max) dose to the arytenoids and mean dose to the oesophagus. The two techniques were otherwise equivalent

Avoidance structure	VMAT	SF-IMRT	p-values
Glottic larynx	20.1 Gy (mean)	19.5 Gy (mean)	0.65
Supraglottic larynx	39.6 Gy (mean)	40.9 Gy (mean)	0.67
Pharyngeal constrictors	46.6 Gy (mean)	46.9 Gy (mean)	0.50
Brachial plexus	64.2 Gy (max)	67.2 Gy (max)	0.37a
	15.2% (V60)	12.8% (V60)	0.64
Arytenoids	23.8 Gy (max)	46.7 Gy (max)	<0.001
Oesophagus	24.6 Gy (mean)	39.7 Gy (mean)	<0.001

V₆₀, volume receiving over 60 Gy.

p-values are in bold when p < 0.05.

^aDenotes statistically significant calculations at a biologically equivalent dose in 2 Gy fraction were performed.