Table 3.
Dose to elective nodal levels with volumetric-modulated arc therapy (VMAT) vs split-field intensity-modulated radiation therapy (SF-IMRT), specific to targets in the low neck. VMAT had improved coverage of CTV50 and PTV50, while PTV60 had better coverage of PTV60 but not CTV60
| Target structure | Parameter | VMAT (mean ± SEM) | SF-IMRT (mean ± SEM) | Number | p-values |
|---|---|---|---|---|---|
| CTV50 low–intermediate low neck (50 Gy/25 fraction equivalent) | V100 | 99.3 ± 0.2% | 91.5 ± 2.4% | 10 | 0.011 |
| PTV50 low–intermediate low neck (50 Gy/25 fraction equivalent) | V100 | 95.6 ± 0.8% | 86.0 ± 3.3% | 10 | 0.029 |
| PTV50 | CI | 0.990 ± 0.003 | 0.969 ± 0.011 | 10 | 0.003 |
| PTV50 | DHI | 21.9 ± 1.8 | 27.7 ± 2.7 | 10 | 0.148 |
| CTV60 high–intermediate low neck (60 Gy/30 fraction equivalent) | V100 | 98.5 ± 0.8% | 97.9 ± 1.3% | 3 | 0.304 |
| PTV60 high–intermediate low neck (60 Gy/30 fraction equivalent) | V100 | 94.6 ± 0.8% | 96.9 ± 1.4% | 3 | 0.029 |
| PTV60 | CI | 0.992 ± 0.002 | 0.995 ± 0.004 | 3 | 0.446 |
| PTV60 | DHI | 22.2 ± 1.5 | 19.4 ± 6.1 | 3 | 0.692 |
CI, conformality index; CTV, clinical target volumes; DHI, dose homogeneity index; PTV, planning target volumes; SEM, standard error of the mean; V100, volume receiving 100% of prescription dose.
(±) denotes standard error of the mean.
p-values are in bold when p < 0.05.