An apparatus using charged particles for irradiation of a tumor of a patient, comprising a synchrotron configured to provide control of an energy and an intensity of an extracted beam, wherein the control of the energy and the control of the intensity occurs during extraction, the synchrotron comprising: a beam extraction path, the path sequentially comprising: a radio-frequency cavity system comprising a first pair of blades (1212, 1214); an extraction foil having a thickness of about thirty to one-hundred microns and consisting essentially of atoms having six or fewer protons; a second pair of blades (1214, 1216); and an extraction magnet; wherein the synchrotron is configured to control an acceleration period for accelerating the charged particles, and a timing of the charged particles striking the extraction foil in the acceleration period so as to control the energy of the extracted beam, wherein the radio-frequency cavity system is configured to apply a radio-frequency across the first pair of blades (1212, 1214) for altering a trajectory of the charged particles through the extraction foil yielding reduced energy charged particles, and wherein the second pair of blades (1214, 1216) is arranged so that the reduced energy charged particles pass through the second pair of blades (1214, 1216), the second pair of blades (1214, 1216) being configured to have a direct current voltage of at least five hundred volts applied across the second pair of blades (1214, 1216) to extract the reduced energy charged particles through the extraction magnet out of the synchrotron, and wherein the synchrotron is configured to provide a feedback control of the intensity of the extracted beam, to control the radio-frequency cavity system, the feedback control using a current generated by the charged particles transmitting through the extraction foil as an indicator of charged particle intensity. a beam extraction path, the path sequentially comprising: a radio-frequency cavity system comprising a first pair of blades (1212, 1214); an extraction foil having a thickness of about thirty to one-hundred microns and consisting essentially of atoms having six or fewer protons; a second pair of blades (1214, 1216); and an extraction magnet; a radio-frequency cavity system comprising a first pair of blades (1212, 1214); an extraction foil having a thickness of about thirty to one-hundred microns and consisting essentially of atoms having six or fewer protons; a second pair of blades (1214, 1216); and an extraction magnet; wherein the synchrotron is configured to control an acceleration period for accelerating the charged particles, and a timing of the charged particles striking the extraction foil in the acceleration period so as to control the energy of the extracted beam, wherein the radio-frequency cavity system is configured to apply a radio-frequency across the first pair of blades (1212, 1214) for altering a trajectory of the charged particles through the extraction foil yielding reduced energy charged particles, and wherein the second pair of blades (1214, 1216) is arranged so that the reduced energy charged particles pass through the second pair of blades (1214, 1216), the second pair of blades (1214, 1216) being configured to have a direct current voltage of at least five hundred volts applied across the second pair of blades (1214, 1216) to extract the reduced energy charged particles through the extraction magnet out of the synchrotron, and wherein the synchrotron is configured to provide a feedback control of the intensity of the extracted beam, to control the radio-frequency cavity system, the feedback control using a current generated by the charged particles transmitting through the extraction foil as an indicator of charged particle intensity.