Table 1 Comparison of different interlacing minibeam modes with 2-Gaussian approximation.

From: Optimizing proton minibeam radiotherapy by interlacing and heterogeneous tumor dose on the basis of calculated clonogenic cell survival

MB mode

ctc [mm]

fD

1 cm

Dmin = 10 Gy

9 cm

Dmin = 10 Gy

1 cm

Dmin = 35 Gy

9 cm

Dmin = 35 Gy

S [%]

deff,10%[mm]

deff,50%[mm]

S [%]

deff,10%[mm]

deff,50%[mm]

S [%]

deff,10%[mm]

deff,50%[mm]

S [%]

deff,10% [mm]

2-dir Broadbeam

–

1.00

20

–

–

7

–

–

 ~ 0

–

–

 ~ 0

–

4-dir Broadbeam

–

1.00

50

–

–

25

–

–

4

–

–

 ~ 0

–

2-dir pencil hom

3.5

1.00

87

1.1

1.3

7

–

–

84

1.3

1.5

 ~ 0

–

2-dir planar hom

3.8

1.00

73

0.7

0.9

7

–

–

67

0.9

1.1

 ~ 0

–

4-dir planar hom

4.0

1.00

78

0.7

0.9

25

–

–

71

0.9

1.1

 ~ 0

–

2-dir pencil hetero (opt)

10.0

1.70

98

1.4

1.5

32

6.7

8.6

97

1.6

1.7

4

9.8

2-dir planar hetero (opt)

15.0

1.50

91

1.0

1.1

37

5.7

7.7

90

1.3

1.4

8

8.5

4-dir planar hetero (opt)

20.4

1.21

94

0.9

1.1

47

4.7

7.1

93

1.1

1.3

11

8.1

  1. For each minibeam mode, the homogeneous tumor irradiation and the optimum heterogeneous tumor irradiation is presented. The mean cell survival (S) and biologically effective beam size (deff) for Dmin = 10 and Dmin = 35 Gy (minimum) tumor dose are given for 1 cm and 9 cm depth. The survival fractions of 10% or 50% are taken for determination of the effective beam sizes deff,10% and deff,50%. Values marked by a dash (–) cannot be determined.
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