Hitachi, Ltd.

Hitachi High-tech Corporation

Takamichi Aoki

Takayoshi Seki

Fuutarou Ebina

Yuto Nakashima

Masumi Umezawa

Hideaki Nishiuchi

Shigemitsu Hara

Kazuo Hiramoto

Takamitsu Hae

Fumiaki Noda

Kazuyoshi Saitou

Toru Umekawa

Chishin Hori

Futaro Ebina

Nishiuchi Hideaki

Ebina Fuutarou

Hara Shigemitsu

Umezawa Masumi

Seki Takayoshi

As the ion beam is accelerated, the radii of the closed orbits gradually increase, and the centers thereof move in a direction approaching the peripheral edge portion along a predetermined radial direction of the cavity, and upon reversing the direction of movement, move further toward the center of the cavity. The intensity distribution in the orbital plane of the main magnetic field is designed to realize the foregoing feature. Thus, an accelerator is provided that is compact and that enables the energy of an extracted beam to be changed, that enhances the efficiency of beam injection into the accelerator from an external ion source, and that improves a dose rate of the resulting extracted ion beam.

Accelerator and particle therapy system

Provided is a variable energy and miniaturized accelerator. It is impossible to change the energy of the extraction beam in the related cyclotron or to miniaturize an accelerator in the related synchrotron. The accelerator includes a pair of magnets which form a magnetic field therebetween; an ion source which injects ions between the magnets; an acceleration electrode which accelerates the ions; and a beam extraction path which extracts the ions to the outside. A plurality of ring-shaped beam closed orbits formed by the pair of magnets, in which the ions of different energies respectively circulate, are aggregated on one side. The frequency of the radiofrequency electric field fed to the ions by the acceleration electrode is modulated by the beam closed orbits.

Circular accelerator

In a circular accelerator that applies a radiofrequency wave in a main magnetic field to accelerate charged particle beam while increasing an orbit radius, another radiofrequency wave with a frequency different from the radiofrequency wave used for acceleration is applied to the charged particle beam in order to extract the charged particle beam. Thereby, in the circular accelerator that accelerates charged particle beam while increasing an orbit radius by applying a radiofrequency wave in a main magnetic field, the high precision control on extraction of the charged particle beam from the circular accelerator is achieved.

Circular accelerator, particle therapy system with circular accelerator, and method of operating circular accelerator

An accelerator includes: a plurality of ion sources, andthat generate a plurality of different types of ions; an electromagnetthat generates a magnetic field; and a high frequency cavitythat generates a high frequency electric field. The center of an orbit of the ion is eccentric with acceleration, the magnetic field generated by the electromagnetis a magnetic field distribution that decreases outward in a radial direction of the orbit, the high frequency cavityaccelerates the ion up to a predetermined energy by the high frequency electric field adjusted to an orbital frequency in response to a nuclide of the incident ion, and a frequency of the high frequency electric field changes following an energy of the ion. Accordingly, it is possible to provide an accelerator and a particle therapy system capable shortening an irradiation time with a small size.

A magnet device that includes upper and lower disk-shaped return yokes, a pair of upper magnetic pole and lower magnetic pole respectively fixed to a disk-shaped surface of the upper return yoke and a disk-shaped surface of the lower return yoke, in which a space to circulate and accelerate an ion beam is formed between the upper magnetic pole and the lower magnetic pole. The upper magnetic pole and the lower magnetic pole have a plurality of concave and convex parts along a track along which the ion beam circulates, are plane-symmetrical with respect to a horizontal symmetry plane formed by the track along which an ion beam circulates, and are plane-symmetrical to one of the vertical planes vertical to the horizontal symmetry plane. Also, the magnetic pole intervals between the concave parts of the upper magnetic pole and the lower magnetic pole are different from each other.

Particle beam accelerator and particle beam therapy apparatus

A particle irradiation system includes three or more scanning magnets that scan a beam in a vertical direction (first direction) or a horizontal direction (second direction) perpendicular to each other. The three or more scanning magnets are configured such that the scanning magnets and the scanning magnets for scanning in the same direction between the vertical direction or the horizontal direction, are disposed in series on a progressing direction axis of a beam, and a volume of a magnetic field feeding region decreases as the scanning magnet is installed at a position farther from an isocenter on the progressing direction axis.

Particle irradiation system and particle therapy system

Conventional cyclotrons have been incapable of changing energy of a beam to be extracted. Conventional synchrotrons have been difficult to output beams in a continuous manner. An accelerator has a dense region dense region in which orbits of different energies densely gather as a result of using a radiofrequency electric field to accelerate an ion orbiting in an isochronous magnetic field in order to cause a beam orbit to be displaced in a specific direction with increasing acceleration, and a sparse region in which orbits of different energies are sparsely discrete from each other. The accelerator has a feature that a magnetic field has a magnetic field gradient in a radial direction of a beam orbit in the dense region, and a product of a gradient of magnetic field gradient and a beam size passing through the dense region becomes smaller than the magnetic field gradient.

Ion beams are efficiently extracted with an accelerator that includes a circular vacuum container including a pair of circular return yokes facing each other. Six magnetic poles are radially disposed from the injection electrode at the periphery thereof in the return yoke. Six recessions are disposed alternately with the respective magnetic poles in the circumferential direction of the return yoke. In the vacuum container, a concentric trajectory region, in which multiple beam turning trajectories centered around the injection electrode are present, is formed, and an eccentric trajectory region, in which multiple beam turning trajectories eccentric from the injection electrode are present, is formed around the region. In the eccentric trajectory region, the beam turning trajectories are dense between the injection electrode and the inlet of the beam extraction path. Gaps between the beam turning trajectories are wide in a direction 180&#xb0; opposite to the inlet of the beam extraction path.

Accelerator and particle beam irradiation system

A particle therapy system capable of reducing the installation area and also suppressing a variation in the irradiation beam position is provided. A synchrotron generates a charged particle beam, and a beam delivery system irradiates an irradiation target with a charged particle beam extracted from the synchrotron thereby forming a radiation field. A rotating gantry is provided with the beam delivery system and is rotatable around the irradiation target. Dispersion measuring devices, each of which measures the dispersion of the charged particle beam at the position of the irradiation target at a plurality of rotation angles of the rotating gantry, are also provided. The orbit center of the charged particle beam extracted from the synchrotron and the rotation axis of the rotating gantry are located on substantially the same straight line.

Particle therapy system

An acceleratorincludes a circular vacuum container including circular return yokesA,B. An injection electrodeis disposed closer to an inlet of a beam extraction pathin the return yokeB than a central axis C of the vacuum container. Magnetic polesA toF are radially disposed from the injection electrodeat the periphery of the injection electrodein the return yokeB. RecessionsA toF are disposed alternately with the magnetic polesA toF in the circumferential direction of the return yokeB. In the vacuum container, a concentric trajectory region, in which multiple beam turning trajectories centered around the injection electrodeare present, is formed, and an eccentric trajectory region, in which multiple beam turning trajectories eccentric from the injection electrodeare present, is formed around the region.

The accelerator includes a circular vacuum container which contains a circular return yoke. With respect to the central axis of the vacuum container, an incidence electrode is arranged towards the entrance of a beam emission path inside of the return yoke. Inside of the return yoke, electrodes are arranged radially from the incidence electrode in the periphery of the incidence electrode. Recesses are arranged alternately with the electrodes in the circumferential direction of the return yoke. In the vacuum container, an orbit-concentric region is formed in which multiple beam orbits centered on the incidence electrode are present, and, in the periphery of said region, an orbit-eccentric area is formed in which multiple beam orbits eccentric to the incidence electrode are present. In the orbit-eccentric region, the beam orbits between the incidence electrode and the entrance to the beam emission path are denser.

Provided is a bed positioning system for a radiation therapy system capable of capturing X-ray transparent images and CT images by rotating an X-ray tube and an X-ray detector around a subject on a bed, comprising: a transparent image registration system which generates a subtraction image from a first X-ray transparent image captured by the X-ray tube and the X-ray detector and a digitally reconstructed radiograph generated from a treatment plan CT image, corrects the first X-ray transparent image by use of a correction image generated by processing the subtraction image in a previously specified direction, and compares the first X-ray transparent image after the correction and the digitally reconstructed radiograph to determine a movement amount of the bed.

Growing community of inventors

Tokyo, Japan

Takamichi Aoki