Fig. 1.

Breath-hold 3-dimensional (3D) magnetic resonance (MR) images of the first five patients treated with single-fraction lung stereotactic ablative radiotherapy using MR-guidance. The 3DMR scan is acquired on the MR-linac during a 17-second breath-hold, using a TrueFISP sequence with 1.6 mm × 1.6 mm × 3.0 mm resolution. Using the stereotactic MR-guided adaptive radiation therapy approach, one fraction of 34 Gy is delivered to the planning target volume (red), which is created by adding a 5 mm isotropic margin to the breath-hold gross tumor volume (purple). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)