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. Author manuscript; available in PMC: 2022 Sep 8.
Published in final edited form as: Int J Radiat Oncol Biol Phys. 2018 Nov 26;110(1):172–187. doi: 10.1016/j.ijrobp.2018.11.028

Figure 1. Variance in normal lung definition and examples of its effect on lung dose volume histograms (DVH).

Figure 1.

DVH vary with the kind of target subtracted from the lung. Panel A shows an axial slice with PTV contour in red and GTV in green; panel B shows DVH for ipsilateral lung with either PTV (purple line) or GTV (blue line) subtracted and bilateral lung with either PTV (red line) or GTV (green line) subtracted Panels C and D show mean doses and V20 for 10 patients for bilateral lung with either GTV or PTV subtracted. GTV= Gross Tumor Volume. IGTV=internal GTV, i.e. composite GTV of all phases of 4DCT. IGTV=ITV when CTV margin is zero. PTV = Planning Target Volume.