Table 1 The mean and standard deviation of D_w and D_m in dose-volume indices calculated with Monte Carlo for 10 NPC IMRT cases

PTV70

D_98%

70.7 ± 0.6

70.2 ± 0.3

0.7 ± 0.5

0.002

D_50%

74.3 ± 0.5

73.6 ± 0.3

0.9 ± 0.4

<  0.001

D_2%

78.2 ± 1.5

76.7 ± 1.0

1.9 ± 1.1

0.001

PTV66

D_98%

64.6 ± 2.1

65.0 ± 2.2

−0.6 ± 0.4

0.002

D_50%

69.0 ± 0.6

69.0 ± 0.6

0.1 ± 0.3

0.923

D_2%

72.4 ± 1.2

72.1 ± 1.5

0.4 ± 1.0

0.235

PTV60

D_98%

63.2 ± 1.1

62.7 ± 1.0

0.7 ± 0.5

0.001

D_50%

71.7 ± 0.9

71.1 ± 0.9

0.9 ± 0.3

<  0.001

D_2%

77.4 ± 1.3

76.1 ± 0.9

1.7 ± 1.0

<  0.001

PTV54

D_98%

56.4 ± 0.7

56.6 ± 0.5

0.2 ± 0.4

0.144

D_50%

65.0 ± 1.2

64.7 ± 1.2

0.6 ± 0.3

<  0.001

D_2%

76.1 ± 1.2

75.1 ± 0.9

1.3 ± 0.7

<  0.001

Spinal Cord

D_50%

34.0 ± 1.6

33.9 ± 1.7

0.5 ± 0.3

<  0.001

D_2%

39.6 ± 1.2

39.2 ± 1.2

0.8 ± 0.3

<  0.001

Brain Stem

D_50%

38.2 ± 2.3

38.1 ± 2.2

0.4 ± 0.3

0.002

D_2%

57.3 ± 6.8

57.1 ± 6.8

0.3 ± 0.2

<  0.001

Parotids

D_50%

40.9 ± 7.1

41.0 ± 7.0

−0.1 ± 0.6

0.901

D_2%

69.3 ± 1.6

69.2 ± 1.6

0.2 ± 0.3

0.136

Lens

D_50%

4.4 ± 1.9

4.4 ± 1.9

0.7 ± 0.9

0.019

D_2%

6.2 ± 2.8

6.2 ± 2.8

0.2 ± 0.6

0.082

Optic nerves

D_50%

35.9 ± 21.4

35.5 ± 21.5

1.6 ± 4.4

0.097

D_2%

54.1 ± 23.7

53.7 ± 23.4

0.4 ± 0.8

0.078

TM-Joints

D_50%

44.2 ± 6.4

42.0 ± 6.0

5.1 ± 0.7

<  0.001

D_2%

67.2 ± 4.3

64.6 ± 4.2

4.5 ± 1.2

<  0.001

Mid-Ears

D_50%

43.3 ± 4.1

42.4 ± 3.7

2.1 ± 1.7

0.009

D_2%

64.2 ± 4.8

62.0 ± 5.0

3.4 ± 1.7

<  0.001

Mandibles

D_50%

49.5 ± 6.8

46.8 ± 7.2

5.5 ± 1.8

<  0.001

D_2%

67.4 ± 4.4

64.2 ± 4.7

4.8 ± 1.5

<  0.001

Temporal lobe

D_50%

16.8 ± 7.3

16.7 ± 7.3

0.6 ± 0.7

0.003

D_2%

64.2 ± 6.0

63.6 ± 6.0

0.9 ± 0.3

<  0.001

Tongue

D_50%

47.7 ± 6.7

47.4 ± 6.7

0.6 ± 0.3

<  0.001

D_2%

65.3 ± 5.3

65.2 ± 5.5

0.2 ± 0.6

0.340