US 4,112,306 A · Neutron irradiation therapy machine

Abstract

In a neutron irradiation therapy machine for treating patients with a beam of high energy neutrons, a gantry is provided which supports a non-superconducting cyclotron proton accelerator and target for generating a neutron beam and which permits rotation of the accelerator and neutron beam around an axis of revolution coaxial with a patient treatment zone. A counter-weight is carried from the gantry in a diametrically opposed relation to the cyclotron and behind the support bearing for counter-weighting the cyclotron and its associated equipment rotationally and longitudinally. The cyclotron includes an enclosing magnetic return yoke having a re-entrant portion in axial alignment with the magnetic poles of the cyclotron for reducing the weight of the yoke. The enclosing magnetic return yoke, and any additional surrounding material such as boron loaded polyethylene and lead, provide radiation shielding to protect the patient. An alternative patient table is coaxially mounted of the gantry and supported from a rotor portion thereof via a bearing assembly so that the rotor rotates around the stationary patient table. A neutron beam stopper is carried from the rotator of the gantry in axial alignment with the neutron beam and diametrically opposed to the cyclotron for absorbing neutrons passing through the patient treatment zone. Evacuable radio frequency transmission lines are provided for feeding RF power to the cyclotron and which pass through the yoke and are connected in gas communication with a vacuum pump for evacuating the cyclotron via the intermediary of the RF transmission lines. The cyclotron accelerates a beam of charge particles, such as protons, to relatively high energy, as of 30 MeV, to bombard a target formed of first and second materials. The first target material has a relatively high yield for high energy neutrons at proton energies in excess of 15 MeV, whereas a second portion of the target has a low yield for neutrons at proton energies less than 15 MeV, for stopping the protons. Tungsten shielding elements are disposed surrounding the neutron producing target and other regions for attenuation of neutrons falling outside of the desired neutron beam lobe. An adjustable and rotatable neutron beam collimator is arranged for varying the orientation and cross sectional dimensions of the neutron beam as applied to the patient treatment zone.

Claims26

Dependent claims

In a neutron irradiation therapy machine for treating patients with a beam of neutrons:

cyclotron means for accelerating protons to a high energy and for bombarding a target to generate a beam of high energy neutrons to be applied to the patient, said cyclotron means having magnet means for generating a magnetic field for interaction with the protons, said magnet means including a pair of pole portions spaced apart to define a magnetic gap therebetween and within which the magnetic field of said magnet means produces a force on said protons, said magnet means having a yoke means of ferromagnetic material interconnecting said pair of pole portions for providing a relatively low reluctance magnetic flux path for returning the magnetic flux to the respective pole portions, magnetomotive force generating mean coupled in magnetic flux exchanging relation with said pole portions for generating a magnetomotive force and for exciting said magnetic pole portions to opposite magnetic polarities,
proton source means for supplying protons to the region between said pole portions to be accelerated to an energy in excess of 15 MeV, and
gantry means for pivoting said cyclotron about a patient treatment region,
neutron filter means disposed in the neutron beam between the target and the patient treatment region for attenuating relatively low energy neutrons of the beam.

1 more element

In a neutron irradiation therapy machine for treating patients with a beam of neutrons:

cyclotron means for accelerating charged particles to a high energy and for bombarding a target to generate a beam of high energy neutrons to be applied to the patient, said cyclotron means having magnet means for generating a magnetic field for interaction with the charged particles, said magnet means including a pair of pole portions spaced apart to define a magnetic gap therebetween and within which the magnetic field of said magnet means produces a force on said charged particles, said magnet means having a yoke means of ferromagnetic material interconnecting said pair of pole portions for providing a relatively low reluctance magnetic flux path for returning the magnetic flux to the respective pole portions, non-superconducting magnetomotive force generating means coupled in magnetic flux exchanging relation with said pole portions for generating a magnetomotive force and for exciting said magnetic pole portions to opposite magnetic polarities, said magnetic yoke means generally enveloping said pole portions,
gantry means for pivoting said cyclotron about an axis of revolution, said gantry means including a bearing structure having, a fixed stator portion and a rotor portion coupled to said cyclotron means for rotationally supporting said cyclotron means as said cyclotron means moves about said axis of revolution, support means for fixedly supporting said stator portion from a platform,
patient table means supportively mounted from said rotor portion and extending generally parallel to said axis of revolution, and a second bearing structure rotationally supporting said patient table means from said rotor and permitting movement of said cyclotron about said patient table while retaining the position of said patient table fixed.

In a neutron irradiation therapy machine for treating patients with a beam of neutrons:

cyclotron means for accelerating charged particles to a high energy and for bombarding a target to generate a beam of high energy neutrons to be applied to the patient, said cyclotron means having magnet means for generating a magnetic field for interaction with the charged particles in said cyclotron means, said magnet means including a pair of pole portions spaced apart to define a magnetic gap therebetween and within which the magnetic field of said magnet means produces a force on said charged particles, said magnet means having a yoke means of ferromagnetic material interconnecting said pair of pole portions for providing a relatively low reluctance magnetic flux path for returning the magnetic flux to the respective pole portions, magnetomotive force generating means coupled in magnetic flux exchanging relation with said pole portions for generating a magnetomotive force and for exciting said magnetic pole portions to opposite magnetic polarities, said yoke means generally enveloping said pole portions, said cyclotron means including envelope means for defining an evacuable envelope within which said charged particles are accelerated, electrode means within said envelope to be excited with radio frequency power to produce a radio frequency electric field within said envelope for acting on said charged particles for acceleration thereof to high velocity, radio frequency transmission line means having an evacuable portion passing through said envelope means for transmitting radio frequency power from a source disposed external of said magnet means to said electrode means for excitation thereof, means for coupling a vacuum pump in gas communication with the interior of said envelope means via the intermediary of at least a portion of said evacuable radio frequency transmission line means for evacuation of said envelope means via at least a portion of said evacuable radio frequency transmission line means.

In a neutron irradiation therapy machine for treating patients with a beam of neutrons:

cyclotron means for accelerating charged particles to a high energy and for bombarding a target to generate a beam of high energy neutrons to be applied to the patient, said cyclotron means having magnet means for generating a magnetic field for interaction with the charged particles, said magnet means including a pair of pole portions spaced apart to define a magnetic gap therebetween and within which the magnetic field of said magnet means produces a force on said charged particles, said magnet means including a yoke means of ferromagnetic material interconnecting said pair of pole portions for providing a relatively low reluctance magnetic flux path for returning the magnetic flux to the respective pole portions, magnetomotive force generating means coupled in magnetic flux exchanging relation with said pole portions for generating a magnetomotive force and for exciting said magnetic pole portions to opposite magnetic polarities, said yoke means generally enveloping said pole portions,
collimator means disposed in the neutron beam path downbeam from said target for collimating the beam of neutrons to be applied to the patient treatment zone;
said collimator means including a neutron absorbing means having a neutron beam passageway therein, and means for varying the size of said neutron beam passageway for varying the cross sectional area of the neutron beam as applied to the patient treatment zone.

Dependencies are inferred from the claim text.

Neutron irradiation therapy machine

Life of this patent

Neutron irradiation therapy machine

Life of this patent

Abstract

Claims26