In a magnetic device 1, on faces opposite to a middle plane 2 between an upper magnetic pole 8 and a lower magnetic pole 9, recesses 21a, 21b, 21c, and 21d and projections 22a, 22b, 22c, and 22d are alternately placed along a beam circling direction. In the projections 22a, 22b, 22c, and 22d, angle widths θ of the projections 22a, 22b, 22c, and 22d when viewed from the center O1 of a beam closed orbit is narrowed as beam energy is increased. On the outer circumferential region of the recess 21a on the upper magnetic pole 8 and the lower magnetic pole 9, the inlet of an extraction channel 1019 that extracts a beam accelerated to a predetermined energy to outside an accelerator 1004 is provided.

In a magnetic device 1, on faces opposite to a middle plane 2 between an upper magnetic pole 8 and a lower magnetic pole 9, recesses 21a, 21b, 21c, and 21d and projections 22a, 22b, 22c, and 22d are alternately placed along a beam circling direction. In the projections 22a, 22b, 22c, and 22d, angle widths θ of the projections 22a, 22b, 22c, and 22d when viewed from the center O1 of a beam closed orbit is narrowed as beam energy is increased. On the outer circumferential region of the recess 21a on the upper magnetic pole 8 and the lower magnetic pole 9, the inlet of an extraction channel 1019 that extracts a beam accelerated to a predetermined energy to outside an accelerator 1004 is provided.

A synchrocyclotron for extracting charged particles accelerated to an extraction energy includes a magnetic unit comprising N valley sectors and N hill sectors, and configured for creating z-component of a main magnetic characterized by a radial tune of the successive orbits. The synchrocyclotron includes a first instability coil unit and a second instability coil unit configured for creating a field bump of amplitude increasing radially. The amplitude of the field bump may be varied to reach the value of the offset amplitude at the average instability onset radius. The offset amplitude may be the minimal amplitude of the field bump at the average instability onset radius required for sufficiently offsetting the center of the orbit of average instability onset radius to generate a resonance instability to extract the beam of charged particle at the average instability onset radius.

A synchrocyclotron for extracting charged particles accelerated to an extraction energy includes a magnetic unit comprising N valley sectors and N hill sectors, and configured for creating z-component of a main magnetic characterized by a radial tune of the successive orbits. The synchrocyclotron includes a first instability coil unit and a second instability coil unit configured for creating a field bump of amplitude increasing radially. The amplitude of the field bump may be varied to reach the value of the offset amplitude at the average instability onset radius. The offset amplitude may be the minimal amplitude of the field bump at the average instability onset radius required for sufficiently offsetting the center of the orbit of average instability onset radius to generate a resonance instability to extract the beam of charged particle at the average instability onset radius.

An example method includes: receiving, from a treatment planning process, information that is based on a dose distribution for an irradiation target; and performing at least one of the following operations: moving structures to trim spots of a particle beam so that the spots of the particle beam approximate pre-trimmed spots for which characteristics are obtained based on the information received; moving structures to produce a trimming curve for a layer of an irradiation target based on a specification of a trimming curve for the layer included in the information received; moving structures to produce a single trimming curve for all radiation fields of an irradiation target based on specifications of the single trimming curve included in the information received; or moving structures based on configuration information for the structures in the information received.

An example method includes: receiving, from a treatment planning process, information that is based on a dose distribution for an irradiation target; and performing at least one of the following operations: moving structures to trim spots of a particle beam so that the spots of the particle beam approximate pre-trimmed spots for which characteristics are obtained based on the information received; moving structures to produce a trimming curve for a layer of an irradiation target based on a specification of a trimming curve for the layer included in the information received; moving structures to produce a single trimming curve for all radiation fields of an irradiation target based on specifications of the single trimming curve included in the information received; or moving structures based on configuration information for the structures in the information received.

A synchrocyclotron for extracting charged particles accelerated to an extraction energy includes a magnetic unit comprising N valley sectors and N hill sectors, and configured for creating z-component of a main magnetic characterized by a radial tune of the successive orbits. The synchrocyclotron includes a first instability coil unit and a second instability coil unit configured for creating a field bump of amplitude increasing radially. The amplitude of the field bump may be varied to reach the value of the offset amplitude at the average instability onset radius. The offset amplitude may be the minimal amplitude of the field bump at the average instability onset radius required for sufficiently offsetting the center of the orbit of average instability onset radius to generate a resonance instability to extract the beam of charged particle at the average instability onset radius.

A synchrocyclotron for extracting charged particles accelerated to an extraction energy includes a magnetic unit comprising N valley sectors and N hill sectors, and configured for creating z-component of a main magnetic characterized by a radial tune of the successive orbits. The synchrocyclotron includes a first instability coil unit and a second instability coil unit configured for creating a field bump of amplitude increasing radially. The amplitude of the field bump may be varied to reach the value of the offset amplitude at the average instability onset radius. The offset amplitude may be the minimal amplitude of the field bump at the average instability onset radius required for sufficiently offsetting the center of the orbit of average instability onset radius to generate a resonance instability to extract the beam of charged particle at the average instability onset radius.

An accelerator includes: a plurality of ion sources 221, 222, and 233 that generate a plurality of different types of ions; an electromagnet 11 that generates a magnetic field; and a high frequency cavity 21 that generates a high frequency electric field. The center of an orbit of the ion is eccentric with acceleration, the magnetic field generated by the electromagnet 11 is a magnetic field distribution that decreases outward in a radial direction of the orbit, the high frequency cavity 21 accelerates 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.

An accelerator includes: a plurality of ion sources 221, 222, and 233 that generate a plurality of different types of ions; an electromagnet 11 that generates a magnetic field; and a high frequency cavity 21 that generates a high frequency electric field. The center of an orbit of the ion is eccentric with acceleration, the magnetic field generated by the electromagnet 11 is a magnetic field distribution that decreases outward in a radial direction of the orbit, the high frequency cavity 21 accelerates 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.