A method for the treatment of a person suffering from neurodegenerative disease such as Alzheimer's, Parkinson's, or Huntington's disease by treating the patient's brain, over the span of one year or less with a plurality of doses of ionizing radiation, each dose being more than 2.5 mJ/kg but less than 150 mJ/kg with the total dose being more than 10 mJ/kg but less than 400 mJ/kg.
