Modeling Gamma Knife Radiosurgical Toxicity for Multiple Brain Metastases.

•We investigated predictors of GK SRS radiotoxicity (i.e., V12) in brain metastases.•Single/distributed GK SRS was used to treat 1217 brain metastases in 245 patients.•Tumor surface area was found to be the most accurate univariate predictor of V12.•A power-law model with only preplan variables accounts for 90% of variance in V12.•This model helps provide safe dose escalation strategies without planning software.