Illustrative example: rapidly growing recurrent BM post-radiosurgery. A Surveillance MRI of a patient with stage IV NSCLC taken 8 months after resection of a right frontal mass followed by radiosurgery to the resection cavity. B Rapid enlargement of the right frontal lesion approximately 1 month after the initial MRI. C Post-op T1 MRI with contrast and CT image registration displaying the GammaTile placement in the resection cavities after resection of both lesions with isodose lines (color-coded numbers represent isodoses in centigray = cGy). D 14 months follow-up MRI post-GT placement showing no evidence of local recurrence or adverse radiation effect.