Table 2 Textural features calculated from fluence maps of volumetric modulated arc therapy (VMAT) plans with various treatment sites

Textural feature

d

H&N (N = 40)

Prostate (PP) (N = 40)

Prostate (BP) (N = 40)

Liver (N = 11)

Spine (N = 9)

ASM (✕10^− 3)

1

1.06 ± 0.33

1.66 ± 0.31

2.12 ± 0.34

1.34 ± 0.39

1.58 ± 0.32

5

0.82 ± 0.23

1.94 ± 0.38

2.55 ± 0.54

1.32 ± 0.63

1.61 ± 0.59

10

0.97 ± 0.37

2.98 ± 0.86

6.37 ± 2.92

1.91 ± 1.46

2.34 ± 1.09

IDM

1

0.30 ± 0.04

0.25 ± 0.02

0.23 ± 0.02

0.28 ± 0.03

0.28 ± 0.04

5

0.16 ± 0.02

0.11 ± 0.01

0.10 ± 0.01

0.13 ± 0.02

0.13 ± 0.02

10

0.12 ± 0.01

0.08 ± 0.01

0.07 ± 0.01

0.10 ± 0.01

0.10 ± 0.01

Contrast (✕10³)

1

0.11 ± 0.04

0.30 ± 0.08

0.51 ± 0.11

0.20 ± 0.11

0.20 ± 0.07

5

0.41 ± 0.13

1.30 ± 0.35

1.44 ± 0.32

0.89 ± 0.33

0.78 ± 0.11

10

0.62 ± 0.19

2.28 ± 0.63

3.03 ± 0.57

1.46 ± 0.54

1.25 ± 0.28

Variance (✕10)

1

3.84 ± 0.50

4.50 ± 0.55

5.04 ± 0.34

4.92 ± 0.37

4.42 ± 0.31

5

3.98 ± 0.52

5.13 ± 0.59

5.17 ± 0.40

5.09 ± 0.42

4.51 ± 0.35

10

4.01 ± 0.54

5.14 ± 0.63

5.60 ± 0.54

5.15 ± 0.41

4.64 ± 0.38

Correlation

1

0.93 ± 0.02

0.88 ± 0.03

0.80 ± 0.04

0.92 ± 0.05

0.90 ± 0.03

5

0.76 ± 0.07

0.54 ± 0.09

0.48 ± 0.08

0.67 ± 0.12

0.62 ± 0.06

10

0.64 ± 0.10

0.24 ± 0.15

0.11 ± 0.14

0.46 ± 0.21

0.45 ± 0.06

Entropy

1

3.21 ± 0.09

2.91 ± 0.06

2.76 ± 0.07

3.06 ± 0.15

3.00 ± 0.14

5

3.33 ± 0.08

2.85 ± 0.07

2.68 ± 0.09

3.10 ± 0.23

3.02 ± 0.22

10

3.31 ± 0.09

2.67 ± 0.11

2.36 ± 0.18

3.00 ± 0.33

2.88 ± 0.30

d

Lung SABR (N = 20)

Spine SABR (N = 20)

Liver SABR (N = 20)

Brain (N = 20)

H&N (N = 20)

ASM (✕10^− 3)

1

2.38 ± 0.99

1.46 ± 0.34

1.78 ± 0.62

1.51 ± 0.50

1.00 ± 0.29

5

3.02 ± 2.00

1.60 ± 0.58

1.94 ± 0.89

1.33 ± 0.60

0.63 ± 0.14

10

5.47 ± 4.24

2.05 ± 0.79

3.12 ± 2.11

1.72 ± 1.13

0.70 ± 0.18

IDM

1

0.22 ± 0.03

0.25 ± 0.02

0.26 ± 0.03

0.30 ± 0.04

0.31 ± 0.03

5

0.09 ± 0.02

0.11 ± 0.01

0.11 ± 0.02

0.13 ± 0.03

0.17 ± 0.02

10

0.10 ± 0.16

0.08 ± 0.01

0.08 ± 0.02

0.09 ± 0.02

0.13 ± 0.02

Contrast (✕10³)

1

0.43 ± 0.20

0.19 ± 0.04

0.22 ± 0.08

0.18 ± 0.12

0.09 ± 0.02

5

1.65 ± 0.39

1.04 ± 0.22

1.18 ± 0.39

1.05 ± 0.50

0.36 ± 0.13

10

2.86 ± 1.14

1.52 ± 0.37

1.97 ± 0.91

1.71 ± 0.84

0.53 ± 0.19

Variance (✕10)

1

4.83 ± 0.32

4.43 ± 0.32

4.58 ± 0.39

4.94 ± 0.32

3.77 ± 0.37

5

5.02 ± 0.32

4.60 ± 0.32

4.75 ± 0.40

5.15 ± 0.33

3.87 ± 0.39

10

5.24 ± 1.02

4.62 ± 0.30

4.85 ± 0.42

5.24 ± 0.38

3.90 ± 0.40

Correlation

1

0.82 ± 0.08

0.90 ± 0.03

0.90 ± 0.03

0.92 ± 0.05

0.94 ± 0.02

5

0.34 ± 0.15

0.52 ± 0.09

0.50 ± 0.12

0.61 ± 0.18

0.77 ± 0.08

10

0.04 ± 0.19

0.30 ± 0.14

0.23 ± 0.22

0.39 ± 0.26

0.66 ± 0.12

Entropy

1

2.71 ± 0.19

3.01 ± 0.11

2.89 ± 0.19

3.03 ± 0.17

3.25 ± 0.07

5

2.65 ± 0.25

3.01 ± 0.15

2.88 ± 0.24

3.10 ± 0.24

3.42 ± 0.06

10

2.39 ± 0.52

2.92 ± 0.17

2.74 ± 0.32

3.04 ± 0.30

3.43 ± 0.06