Percent depth dose (%)

Field size (cm²)

5 cm

10 cm

20 cm

Cone diameter (mm)

5 cm

10 cm

20 cm

0.6 × 0.6

74.4

50.9

25.2

4

73.2

50.1

24.6

1 × 1

76.6

53.1

26.6

5

74.1

50.9

25.3

2 × 2

78.8

55.0

27.8

7.5

75.5

52.1

25.9

3 × 3

80.5

56.6

28.7

10

76.4

52.6

26.4

4 × 4

81.3

58.0

29.8

12.5

77.1

53.1

26.7

5 × 5

81.9

59.1

30.6

15

77.5

53.7

26.9

6 × 6

82.8

60.1

31.5

17.5

78.1

54.1

27.0

8 × 8

83.7

61.8

33.1

10 × 10

84.4

63.2

34.4

15 × 15

85.1

65.0

36.5

20 × 20

85.7

66.1

37.9

30 × 30

86.0

67.1

39.4

40 × 40

86.2

67.7

40.2

Lateral distance (mm) between 20% and 80% isodose curves at a depth of 10 cm*

Field size (cm²)

Cross-plane

In-plane

Cone diameter (mm)

Cross-plane

In-plane

0.6 × 0.6

2.3

2.8

4

1.36

1.34

1 × 1

2.6

3.1

5

1.43

1.45

2 × 2

2.8

3.4

7.5

1.59

1.56

3 × 3

3.0/4.9†

3.6/5.3†

10

1.70

1.68

4 × 4

5.1

5.6

12.5

1.78

1.77

5 × 5

5.4

5.9

15

1.84

1.80

6 × 6

5.7

6.2

17.5

1.88

1.84

8 × 8

6.3

6.8

10 × 10

7.3

7.8

15 × 15

13.4

14.0

20 × 20

29.3

29.7

30 × 30

73.8

74.0

40 × 40

124.2

124.5