Background
Materials and methods
Patient selection and contouring
OARs | Dose constraints |
---|---|
Brain stem | Max dose <54 Gy |
Spinal cord | Max dose <45 Gy |
Parotid glands | Mean dose < 26 Gy or V30 < 50% in one gland at least |
Chiasm | Max dose <50 Gy or V54 < 1% |
Optic nerves | Max dose <50 Gy or V54 < 1% |
Lens | Max dose <10 Gy |
Larynx | Mean dose < 45 Gy |
Oral cavity | Mean dose <45 Gy |
Planning technique
dIMRT and ssIMRT
VMAT
Dose-volume histograms (DVHs) and dose comparisons
Statistical analysis
Results
PTV coverage
VMAT1 | VMAT2 | dIMRT | ssIMRT |
p
GLM-u
|
p
VMAT1
|
p
VMAT1
|
p
VMAT1
|
p
VMAT2
|
p
VMAT2
|
p
dIMRT
| ||
---|---|---|---|---|---|---|---|---|---|---|---|---|
-VMAT2
|
-dIMRT
|
-ssIMRT
|
-dIMRT
|
-ssIMRT
|
-ssIMRT
| |||||||
PTV72.6 | HI | 0.07 ± 0.01 | 0.07 ± 0.01 | 0.09 ± 0.01 | 0.09 ± 0.01 |
<0.001
| 0.510 |
<0.001
|
<0.001
|
<0.001
|
<0.001
| 0.653 |
CI | 0.57 ± 0.09 | 0.57 ± 0.08 | 0.49 ± 0.07 | 0.50 ± 0.07 |
<0.001
| 0.955 |
<0.001
|
<0.001
|
<0.001
|
<0.001
| 0.355 | |
D2% | 75.43 ± 0.76 | 75.40 ± 0.89 | 76.30 ± 0.86 | 76.57 ± 0.66 | 0.472 | |||||||
D50% | 72.64 ± 0.03 | 72.68 ± 0.03 | 72.93 ± 0.11 | 72.80 ± 0.10 | 0.588 | |||||||
D95% | 70.55 ± 0.24 | 70.69 ± 0.30 | 70.18 ± 0.17 | 70.10 ± 0.23 | 0.464 | |||||||
D98% | 70.01 ± 0.45 | 70.15 ± 0.57 | 70.01 ± 0.44 | 70.02 ± 0.40 | 0.742 | |||||||
PTV63.6 | HI | 0.21 ± 0.02 | 0.21 ± 0.02 | 0.23 ± 0.02 | 0.23 ± 0.02 |
<0.001
| 0.427 |
<0.001
|
<0.001
|
<0.001
|
<0.001
| 0.614 |
CI | 0.76 ± 0.03 | 0.76 ± 0.04 | 0.73 ± 0.03 | 0.73 ± 0.04 |
0.001
| 0.448 |
0.003
|
0.001
|
<0.001
|
<0.001
| 0.605 | |
D2% | 72.45 ± 1.11 | 72.42 ± 1.26 | 72.89 ± 1.16 | 73.20 ± 0.79 |
0.005
| 0.904 | 0.174 |
0.003
| 0.157 |
0.002
| 0.204 | |
D50% | 64.14 ± 0.28 | 63.64 ± 0.11 | 63.99 ± 0.19 | 63.83 ± 0.17 | 0.236 | |||||||
D95% | 60.42 ± 0.18 | 60.44 ± 0.12 | 60.20 ± 0.17 | 60.17 ± 0.27 | 0.715 | |||||||
D98% | 58.49 ± 0.32 | 58.83 ± 0.39 | 57.99 ± 0.50 | 58.55 ± 0.41 |
<0.001
|
0.007
|
<0.001
| 0.651 |
<0.001
|
0.021
|
<0.001
|
Dose to the OARs
VMAT1 | VMAT2 | dIMRT | ssIMRT |
p
GLM-u
|
p
VMAT1
|
p
VMAT1
|
p
VMAT1
|
p
VMAT2
|
p
VMAT2
|
p
dIMRT
| ||
---|---|---|---|---|---|---|---|---|---|---|---|---|
-VMAT2
|
-dIMRT
|
-ssIMRT
|
-dIMRT
|
-ssIMRT
|
-ssIMRT
| |||||||
Brain stem | D2% | 41.21 ± 0.92 | 41.94 ± 0.42 | 42.56 ± 0.48 | 46.32 ± 0.44 |
0.024
| 0.679 | 0.444 |
0.005
| 0.724 |
0.015
|
0.036
|
Dmean | 24.02 ± 2.58 | 23.46 ± 3.97 | 24.85 ± 3.86 | 27.51 ± 0.41 |
<0.001
| 0.326 | 0.056 |
<0.001
| 0.117 |
<0.001
|
<0.001
| |
Spinal-cord | D2% | 35.15 ± 1.75 | 32.59 ± 2.91 | 33.60 ± 2.67 | 28.66 ± 3.02 |
<0.001
|
0.001
| 0.073 |
<0.001
| 0.160 |
<0.001
|
<0.001
|
Dmean | 26.26 ± 2.66 | 23.46 ± 2.74 | 25.01 ± 2.79 | 22.3 ± 3.52 |
<0.001
|
<0.001
| 0.055 |
<0.001
|
0.017
| 0.071 |
0.001
| |
Chiasm | Dmax | 47.51 ± 4.52 | 47.89 ± 5.01 | 47.17 ± 5.83 | 48.23 ± 6.32 | 0.600 | ||||||
Dmean | 34.44 ± 6.88 | 36.38 ± 5.79 | 35.30 ± 5.46 | 36.37 ± 7.30 |
0.013
|
0.033
| 0.427 |
0.023
| 0.330 | 0.988 | 0.337 | |
Optic N L | Dmax | 43.73 ± 10.41 | 46.20 ± 9.77 | 44.13 ± 9.52 | 45.11 ± 10.00 | 0.177 | ||||||
Dmean | 24.17 ± 9.69 | 26.17 ± 9.69 | 24.40 ± 8.29 | 26.22 ± 9.24 |
0.022
|
0.021
| 0.787 |
0.018
| 0.07 | 0.955 | 0.065 | |
Optic N R | Dmax | 43.30 ± 11.85 | 44.88 ± 9.57 | 42.04 ± 10.18 | 44.84 ± 8.91 |
0.048
| 0.177 | 0.278 | 0.188 |
0.017
| 0.971 |
0.018
|
Dmean | 25.04 ± 9.69 | 25.66 ± 9.53 | 23.92 ± 8.74 | 26.04 ± 9.15 | 0.076 | |||||||
Lens L | Dmean | 3.86 ± 1.35 | 4.13 ± 1.49 | 4.18 ± 1.38 | 5.18 ± 1.53 |
<0.001
| 0.111 | 0.06 |
<0.001
| 0.767 |
<0.001
|
<0.001
|
Lens R | Dmean | 3.71 ± 1.05 | 4.35 ± 1.7 | 4.21 ± 1.21 | 5.22 ± 1.38 |
<0.001
|
0.004
|
0.022
|
<0.001
| 0.535 |
<0.001
|
<0.001
|
Parotid L | D50% | 28.45 ± 4.20 | 27.04 ± 4.99 | 23.89 ± 4.05 | 26.73 ± 4.09 |
<0.001
| 0.064 |
<0.001
|
0.025
|
<0.001
| 0.682 |
<0.001
|
Dmean | 32.20 ± 3.30 | 31.57 ± 3.86 | 29.01 ± 3.31 | 31.48 ± 3.21 |
<0.001
| 0.223 |
<0.001
| 0.165 |
<0.001
| 0.863 |
<0.001
| |
Parotid R | D50% | 31.73 ± 5.88 | 28.18 ± 5.38 | 25.42 ± 5.53 | 27.07 ± 3.79 |
<0.001
|
0.001
|
<0.001
|
<0.001
|
0.008
| 0.273 | 0.104 |
Dmean | 34.14 ± 3.56 | 32.47 ± 3.83 | 30.11 ± 3.93 | 31.65 ± 3.08 |
<0.001
| 0.085 |
<0.001
|
0.001
|
0.001
| 0.238 | 0.097 | |
Oral cavity | Dmean | 40.35 ± 4.77 | 36.99 ± 6.18 | 41.42 ± 6.77 | 43.21 ± 5.60 |
<0.001
|
<0.001
| 0.230 |
0.002
|
<0.001
|
<0.001
|
0.049
|
Larynx | Dmean | 37.67 ± 4.13 | 35.17 ± 4.55 | 35.86 ± 3.05 | 34.76 ± 3.82 |
<0.001
|
0.001
|
0.003
|
<0.001
| 0.249 | 0.395 |
0.048
|
Delivery efficiency and dose verification
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 |