Table 1.
The dosimetric parameters in the original plan and plans with head tilt of ±5°.
| (A) Original plan a | (B) Plan with head tilt of + 5° | (C) Plan with head tilt of − 5° | Freidman test | Wilcoxon signed rank test with Bonferroni's correction | |||
|---|---|---|---|---|---|---|---|
| p‐value |
p‐value (A) vs (B) |
p‐value (A) vs (C) |
|||||
| PTV | Maximum dose [Gy] | 26.7 ± 17.5 | 26.7 ± 29.4 | 26.7 ± 17.7 | 0.47 | – | – |
| D98% [Gy] | 24.8 ± 0.2 | 24.7 ± 0.2 | 24.7 ± 0.2 | 0.23 | – | – | |
| HI [%] | 6.5 ± 1.4 | 7.3 ± 2.0 | 7.0 ± 1.2 | 0.49 | – | – | |
| CI | 0.8 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 0.65 | – | – | |
| Lens | Maximum dose [Gy] | 10.5 ± 2.0 | 8.5 ± 2.3 | 12.2 ± 2.0 | <0.05 | <0.05 | <0.05 |
| Mean dose [Gy] | 4.2 ± 0.6 | 3.6 ± 0.6 | 4.7 ± 0.6 | <0.05 | <0.05 | <0.05 | |
| V5Gy [%] | 19.8 ± 11.8 | 11.4 ± 10.7 | 30.9 ± 14.0 | <0.05 | <0.05 | <0.05 | |
| V10Gy [%] | 0.5 ± 0.9 | 0.2 ± 0.4 | 4.4 ± 9.1 | <0.05 | 0.30 | 0.10 | |
| Bilateral parotid glands | Mean dose [Gy] | 7.4 ± 1.8 | 8.2 ± 2.2 | 6.8 ± 1.5 | <0.05 | <0.05 | <0.05 |
| Median dose [Gy] | 5.6 ± 2.6 | 6.4 ± 3.0 | 5.2 ± 2.3 | <0.05 | <0.05 | <0.05 | |
| V5Gy [%] | 50.9 ± 9.1 | 53.7 ± 10.0 | 49.7 ± 8.9 | <0.05 | <0.05 | <0.05 | |
| V10Gy [%] | 34.5 ± 9.3 | 37.5 ± 9.7 | 32.9 ± 8.8 | <0.05 | <0.05 | <0.05 | |
PTV, planning target volume; D98%, the dose to volume of 98%; HI, homogeneity index; CI, conformity index; VXXGy, the volume receiving at least XX Gy.
a
Mean virtual orbitomeatal plane angle: 16 ± 2°.