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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.