LOW ENERGY ELECTRON BEAM RADIATION SYSTEM THAT GENERATES ELECTRON BEAMS WITH PRECISELY CONTROLLED AND ADJUSTABLE PENETRATION DEPTH USEFUL FOR THERAPEUTIC APPLICATIONS

The present invention provides electron beam therapies with improved feedback control that delivers controlled and adjustable doses of electron beam radiation to variable shallow depths with little radiation exposure to both nearby tissues and tissues below the target. In order to control radiation to accurately penetrate to shallow depths and to allow the radiation to be adjusted to other depth settings in very small or even continuous increments, the present invention senses a plurality of different electron beam characteristics and then uses these to derive a composite characteristic, or analog, of the electron beam energy. The composite analog provides a strong correlation to energy that allows this precision. In another aspect, the present invention relates to implementing this feedback control by adjusting power levels used to establish the electron beam. In other embodiments, feedback control adjusts absorbing components with variable electron beam absorption depending on how such components are presented to the electron beam.