This is a great question and one that does not yet have a clear answer from SBRT toxicity outcomes data. Practically, I think we start with contouring the nearby coronaries (which is not such an easy task to broadly implement from a workflow standpoint!) and evaluating the low to moderate isodose li...

ALARA while keeping the R50 & D2cm as compact and symmetric as possible. I keep the PTV overlap with LAD <105%. I never reduce the PTV less than 5 mm, unless the tumor can be tracked during the entire beam-on time with MRgRT (3 mm).