Uses of therapeutic x rays in medicine.

Treatment of diseases with x rays began within months of Roentgen's discovery, and within four years x rays were being used successfully for the treatment of skin cancers. Deep-seated cancers began to be treated successfully in the 1920's with the advent of "deep" x-ray units and, especially, once supervoltage therapy machines became available in the 1930's. The 1940's and 1950's saw significant growth of megavoltage therapy, initially with Van de Graaff generators and betatrons, and later with linear accelerators. Linear accelerators became popular during the 1960's and 1970's and, by the 1980's they began to replace 60Co units as the most common form of treatment machine. With high-energy linear accelerators, computerized treatment planning, and ingenious fractionation schemes, modern radiotherapy has become a vital component of cancer treatment.