What marginal SRS dose do you prescribe for brain metastases 2 cm or smaller?

Many gamma knife centers have gotten away from the 24 Gy marginal dose based on rates of treatment related imaging changes/radiation necrosis. At Yale, we use 22 Gy as our "top" dose. We have an ongoing prospective phase I/II trial investigating dose selection for gamma knife based on a grid of dose...

We have not used 24 Gy for small lesions. Rather, 20 Gy is what we have used by default. Can we go up to 22 Gy or more, certainly yes but I would rather see data comparing that versus 20 Gy before changing doses.