|
Parameters
|
Conventional IMRT
|
MCO IMRT
|
Difference
|
p
-value
|
|---|
|
Dose-volume values (Gy)
| | | | |
|
PTV (boost) D98%
|
66.4 ± 2.1
|
66.9 ± 1.1
|
−0.5 ± 0.5
|
0.03
|
|
PTV (boost)
|
70.2 ± 0.5
|
70.1 ± 0.3
|
0.2 ± 0.1
|
0.33
|
|
PTV (boost) D2%
|
73 ± 1.2
|
72.4 ± 0.7
|
0.6 ± 0.3
|
0.04
|
|
PTV (prophylactic) D98%
|
52 ± 0.7
|
52.5 ± 1.2
|
−0.4 ± 0.3
|
0.07
|
|
PTV (prophylactic)
|
54.6 ± 0.5
|
54.8 ± 1.0
|
−0.2 ± 0.2
|
0.53
|
|
Integral dose
|
13.9 ± 4.5
|
12.9 ± 4.0
|
0.9 ± 1.4
|
<0.001
|
|
Ring 1 cm around PTV
|
46.2 ± 2.6
|
45.0 ± 2.2
|
1.1 ± 0.8
|
0.008
|
|
Ring 6 cm around PTV
|
16.9 ± 3.2
|
15.0 ± 2.5
|
1.9 ± 0.9
|
<0.001
|
|
Spinal cord (D1%)
|
45.3 ± 3.9
|
44.1 ± 4.4
|
1.2 ± 1.3
|
0.17
|
|
Brain D1%
|
27.8 ± 14.5
|
27.5 ± 16.1
|
0.2 ± 4.8
|
0.31
|
|
Parotid gland (contra)
|
28.1 ± 11.8
|
23.0 ± 11.2
|
5.1 ± 8.1
|
<0.002
|
|
Parotid gland (ipsi)
|
39.1 ± 11.7
|
36.0 ± 11.1
|
3.0 ± 11.9
|
0.02
|
|
Superior PCM
|
58.8 ± 9.5
|
58.9 ± 10.2
|
−0.1 ± 3.1
|
0.91
|
|
Middle PCM
|
55.3 ± 14.0
|
56.3 ± 12.1
|
−1.0 ± 4.1
|
0.79
|
|
Inferior PCM
|
51.2 ± 16.8
|
52.2 ± 15.9
|
−1.0 ± 5.2
|
0.46
|
|
Supraglottic larynx
|
55.5 ± 15.3
|
57.3 ± 13.7
|
−1.9 ± 4.6
|
0.02
|
|
Esophagus inlet muscle
|
44.8 ± 12.2
|
44.1 ± 11.0
|
0.7 ± 3.7
|
0.28
|
|
Cricopharyngeus
|
48.6 ± 13.8
|
48.5 ± 13.6
|
0.1 ± 4.3
|
0.73
|
|
NTCP values (%)
| | | | |
|
Xerostomia [contra]
|
27.1 ± 20.9
|
18.7 ± 19.2
|
8.4 ± 7.4
|
<0.003
|
|
Xerostomia [ipsi]
|
48.2 ± 25.8
|
41.8 ± 24.0
|
6.4 ± 14.3
|
0.03
|
|
Dysphagia
|
35.4 ± 14.7
|
36.9 ± 14.7
|
−1.5 ± 4.7
|
0.11
|
|
Plan evaluation
| | | | |
|
CI 95% (PTV boost)
|
1.30 ± 0.12
|
1.28 ± 0.07
|
0.02 ± 0.03
|
0.98
|
|
CI 95% (PTV prophylactic)
|
1.54 ± 0.15
|
1.55 ± 0.13
|
−0.02 0.04
|
0.65
|
|
Monitor Units (#)
|
590 ± 135
|
672 ± 157
|
−82 ± 46
|
0.02
|
|
Total planning time (min)
|
205
|
43 ± 12
|
162
|
-
|
-
Abbreviations: PTV planning target volume, PCM pharyngeal constrictor muscle, NTCP normal tissue complication probability, CI 95% conformity index of 95% isodose with PTV. Items with statistically significant differences (structure related: p < 0.003 else: p < 0.05) in bold.
