Diagnosis of delayed cerebral radiation necrosis following proton beam therapy.

A 27-year-old man developed delayed cerebral radiation necrosis following proton beam therapy to an arteriovenous malformation. Neuroimaging with technetium 99m diethylenetriamine penta-acetic acid and positron emission tomographic scanning with fludeoxyglucose F 18 aided in his evaluation. Significant improvement of his neurologic deficits resulted from corticosteroid therapy. Clinical resolution was corroborated by serial computed tomographic scans demonstrating regression of the abnormality (a mass lesion). Various facets of radiation injury are discussed, including pathogenesis, risk factors, diagnosis, and therapy.