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Do you add a margin when treating brain metastases with SRS?
While the Duke randomized study found similar rates of control with 1mm v. 3mm margins and higher radionecrosis with 3mm, it did not look at treating with no margin. Does margin size depend on modality (gamma knife v. linac or cyberknife) and dose fall-off?
Answer from: Radiation Oncologist at Academic Institution
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 i...
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Answer from: Radiation Oncologist at Community Practice
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,...