Structure Metric Volume Accepted variation PTV V40Gy ≥95% ≥90% minimum dose 0.03 cm3 ≥46 Gy (92%) ≥45 Gy (90%) maximum dose 0.03 cm3 ≤60 Gy (120%) ≤62.5 Gy (125%) Lung (minus GTV) V20Gy ≤10% ≤15%   Mean dose ≤8 Gy ≤10 Gy Spinal cord 0.03 cm3 ≤15 Gy ≤22 Gy Heart / Pericardium 15 cm3 ≤32 Gy ≤36 Gy Esophagus 0.03 cm3 ≤27 Gy ≤30 Gy   Mean dose ≤18 Gy ≤20 Gy Brachial plexus nerve 0.03 cm3 ≤24 Gy ≤30 Gy

*Abbreviations: PTV: Planning Tumor Volume; GTV: Gross Tumor Volume

Table 2: Vero stereotactic body radiation therapy lung treatment planning constraints.