Would you consider prone SBRT (with solid image guidance techniques) if bowel is lying on a target, for instance bowel surrounding an oligometastatic lymph node or next to a kidney tumor?

I have done this, but rarely do. Patient setup uncertainty tends to increase in the prone position, thereby increasing the required PTV margin. This may limit the anatomical benefit of performing treatment in the prone position. However, if it works there can be great value in moving a radiosensitive structure like bowel away from the target (PMID 24674365). In the right situation, this may be similarly effective.