Table 5.
Comparison of doses to other critical structures (Gy)
| Structure | Dose–volume index | Intensity-modulated radiation therapy (mean ± SD) | SmartArc-based volumetric modulated arc therapy (mean ± SD) | p-value |
|---|---|---|---|---|
| Brain stem | D2% | 53.6 ± 0.7 | 52.2 ± 1.7 | <0.001 |
| Dmax1% | 51.2 ± 1.6 | 49.8 ± 2.4 | <0.001 | |
| Spinal cord | D2% | 43.8 ± 1.6 | 42.2 ± 1.9 | <0.001 |
| Dmax1% | 41.6 ± 1.2 | 40.3 ± 1.4 | <0.001 | |
| Temporal lobe | Dmax1% | 60.0 ± 4.5 | 58.5 ± 4.9 | <0.001 |
| Parotid-R | Dmean | 30.9 ± 5.6 | 26.1 ± 3.4 | <0.001 |
| V20 Gy (%) | 65.3 ± 1.1 | 46.3 ± 1.2 | <0.001 | |
| V30 Gy (%) | 43.4 ± 1.9 | 31.8 ± 1.4 | <0.001 | |
| Parotid-L | Dmean | 31.1 ± 5.9 | 26.3 ± 3.8 | <0.001 |
| V20 Gy (%) | 65.7 ± 1.1 | 47.7 ± 1.1 | <0.001 | |
| V30 Gy (%) | 44.8 ± 1.8 | 32.8 ± 1.1 | <0.001 | |
| Optical nerve-R | D2% | 37.7 ± 10.4 | 36.7 ± 11.8 | 0.39 |
| Dmean | 20.6 ± 7.5 | 19.9 ± 7.7 | 0.41 | |
| Optical nerve-L | D2% | 36.7 ± 10.4 | 34.7 ± 12.1 | 0.14 |
| Dmean | 19.6 ± 8.6 | 18.9 ± 6.9 | 0.49 | |
| Lens-R | D2% | 5.9 ± 0.8 | 6.0 ± 0.7 | 0.84 |
| Lens-L | D2% | 5.4 ± 0.7 | 5.3 ± 0.5 | 0.76 |
| Chiasm | D2% | 40.6 ± 8.5 | 38.5 ± 8.9 | 0.19 |
D2%, near maximum dose; Dmax1%, maximum dose encompassing 1% of the organ at risk volume; Dmean, mean dose; L, left; R, right; SD, standard deviation; V20 Gy, volume receiving at least 20 Gy; V30 Gy, volume receiving at least 30 Gy.