Fig. 4

Example of lung volume changes over time after SABR to a right upper lobe tumor (Patient 1) and a right lower lobe tumor (Patient 2). Coronal (patient 1) and sagittal (patient 2) slices through the target volumes are shown. Gross tumor volumes are outlined in red and the 20 (purple), 40 (blue), 60 (green), 80 (pink), 100 Gy (orange) biologically effective dose (BED₃) isodose volumes are outlined. Treated lobe volume (yellow) and adjacent lobe volume (blue) (both as % of total lung volume [TLV]) change relative to pretreatment volumes on serial diagnostic CT imaging, demonstrating progressive treated lobe volume reduction and adjacent lobe compensatory expansion