Fig. 2

Comparative treatment plans for MRI-guided radiotherapy using breath-hold versus a standard free-breathing internal target volume (ITV)-based approach for a central tumor in a patient with interstitial lung disease. Panel a shows the ITV (7.8 cc) for a RapidArc (volumetric modulated arc therapy) plan, to which a 5 mm margin was added to derive a planning target volume (PTV, 26 cc); panel b the corresponding dose color-wash for an 8 fraction stereotactic ablative radiotherapy scheme to 60 Gy. Treatment was delivered using on-line MRI guided breath-hold on the MRIdian in which the target was the gross tumor volume (6.9 cc, Panel c), to which a 3 mm setup PTV margin was added (PTV 13.6 cc). Panel d shows the MRIdian dose color-wash, and Panel e the dose volume histograms for the adjacent aorta for both plans