Hi GeneD. A lot of variables can play into how a person is impacted by targeted radiation for metastasis to the brain - everything from type of cancer, the extent of the metastasis, to simply the individual. This article gives an overview of radiation treatment to the brain for lung cancer, including some information on side effects: http://oncolex.org/Prosedyrer/TREATMENT/RadiationTherapy/Lung_Brain?lg=procedure#:~:text=General,non%2Dsmall%20cell%20lung%20cancer. Your doctor should be able to provide additional information, more attuned to your specific case. Please know that many here understand what you are going through and that this community is here for you. Best, Richard (LungCancer.net Team)