Hitachi, Ltd.

Hitachi High-tech Corporation

Yuto Nakashima

Takamichi Aoki

Fuutarou Ebina

Takayoshi Seki

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

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 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.

Growing community of inventors

Tokyo, Japan

Yuto Nakashima