Do you add a margin when treating brain metastases with SRS?

This is debatable. We use the Gamma Knife Perfexion system (with Leksell head frame) and we do not add margins when treating brain metastases. Some institutions feel more comfortable using 1-2 mm margins when using a LINAC based SRS and mask for immobilization. However, some institutions also feel c...

I was trained using the Gamma Knife Perfexion system at which time no PTV expansions were used. I have since been treating SRS using a LINAC-based frameless system. I find that I base my PTV expansion on the slice thickness of my planning MRI, which is usually around 1.25mm. Again, I agree with @Dr....