My Husband Had A Shut Revision That Did Not Bring

My husband had a shut revision that did not bring him back fully. As he started to get better he would have these declines. After a number of incidents I took him to a hospital and they seem to think that he is suffering from radiation damage in the brain. My problem with that is that the radiation was done 34 years ago. Is it possible to have radiation damage appear after that length of time, and what can be done about it if so?