Fig. 3From: Efficacy of virtual block objects in reducing the lung dose in helical tomotherapy planning for cervical oesophageal cancer: a planning studyComparison of the dose-volume histogram of non-block and block planning. Although the V20 values of the lungs were comparable, with approximately 15% between the plans, V5 and V10 of the block plans were much lower than those in the non-block plan (black arrow).V20, the lung volume receiving 20Â Gy; V5, the lung volume receiving 5Â Gy; V10, the lung volume receiving 10Â GyBack to article page