Radiation device using a beam of charged particles

A device for generating accelerated electron beams for use in radiotherapy was developed, which gives a uniform beam with well-defined dimensions and energy, and which is readily centered in relation to the target or zone to be treated. The beam is not contaminated by parasitic photons. The device comprises a source of charged particles as a function of their energy, systems for measuring the dose level and for determining the centering, uniformity and directivity of the radiation beam, and a collimating system. The beam is focussed with a magnetic doublet, comprising an entry quadrupolar electromagnet and an exit quadrupolar electromagnet. A beam-centering corrector is arranged between the entry and exit quadrupolar electromagnets. The deflector comprises astigmatic and achromatic magnet deflector having three electromagnets which permit the indicdent beam to be deflected through an angle in a given plane. The selector is a metal screen with a variable aperture positioned between the first and second electromagnets at the energy focus of the first electromagnet. (DN)