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Table 4 Reductions in normal tissue dose volume parameters using online CBCT image guidance and ABC for SBRT of three GTV (16 cc) location

From: Hypofractionated radiotherapy for lung tumors with online cone beam CT guidance and active breathing control

Normal tissue parameter

Dose absolute reduction value

Dose reduction %

 

PTV1

PTV2

PTV3

from PTV1

to PTV2

from PTV1

to PTV3

from PTV2 to PTV3

Mean lung dose(Gy)

      

central location

5.42

2.42

2.91

55.4

46.3

9.1

peripheral location

5.05

2.47

3.22

51.1

36.3

14.8

inferior lobe of lung

11.46

6.07

7.47

47.0

34.8

12.2

Lung V20 (%)

      

central location

11

2.5

3.7

77.3

66.7

10.6

peripheral location

8

2.5

4

68.8

50.0

18.8

inferior lobe of lung

21

10

12

52.4

42.9

9.5

Spinal cord Maximum dose(Gy)

      

central location

59.34

24.64

26.58

58.5

55.2

3.3

peripheral location

6.91

5.99

6.32

13.3

8.4

4.9

inferior lobe of lung

22.50

18.67

20.00

17.0

11.1

5.9

  1. Abbreviations: PTV1 = precorrection margins with ABC; PTV2 = postcorrection margins with ABC; PTV3 = posttreatment residual margin with ABC+CBCT-correction; V20 = volume of both lungs receiving ≥ 20 Gy.