In an example, a synchrocyclotron includes a particle source to provide pulses of ionized plasma to a cavity; a voltage source to provide a radio frequency (RF) voltage to the cavity to accelerate particles from the plasma column outwardly; and an extraction channel to receive a beam of particles from the cavity for output from the particle accelerator. The particle source is configured to control pulse widths of the ionized plasma in order to control an intensity of the beam of particles. This example synchrocyclotron may include one or more of the following features, either alone or in combination.

An example particle therapy system includes a gantry having a beamline structure configured to direct a particle beam that is monoenergetic from an output of a particle accelerator towards an irradiation target, where the beamline structure includes magnetic bending elements to bend the particle beam along a length of the beamline structure; and an energy degrader downstream of the beamline structure relative to the particle accelerator, where the energy degrader is configured and controllable to change an energy of the particle beam prior to at least part of the particle beam reaching the irradiation target.

An example particle therapy system includes a gantry having a beamline structure configured to direct a particle beam that is monoenergetic from an output of a particle accelerator towards an irradiation target, where the beamline structure includes magnetic bending elements to bend the particle beam along a length of the beamline structure; and an energy degrader downstream of the beamline structure relative to the particle accelerator, where the energy degrader is configured and controllable to change an energy of the particle beam prior to at least part of the particle beam reaching the irradiation target.

An example particle therapy system includes: a particle accelerator to output a beam of charged particles; and a scanning system to scan the beam across at least part of an irradiation target. An example scanning system includes: a scanning magnet to move the beam during scanning; and a control system (i) to control the scanning magnet to produce uninterrupted movement of the beam over at least part of a depth-wise layer of the irradiation target so as to deliver doses of charged particles to the irradiation target; and (ii) to determine, in synchronism with delivery of a dose, information identifying the dose actually delivered at different positions along the depth-wise layer.

An example particle therapy system includes: a particle accelerator to output a beam of charged particles; and a scanning system to scan the beam across at least part of an irradiation target. An example scanning system includes: a scanning magnet to move the beam during scanning; and a control system (i) to control the scanning magnet to produce uninterrupted movement of the beam over at least part of a depth-wise layer of the irradiation target so as to deliver doses of charged particles to the irradiation target; and (ii) to determine, in synchronism with delivery of a dose, information identifying the dose actually delivered at different positions along the depth-wise layer.

A disturbance magnetic field region provided in an outer peripheral portion of a main magnetic field region of an accelerator has a peeler region in which a strength of a magnetic field decreases toward an outside, a regenerator region in which the strength of the magnetic field increases toward the outside, and a substantially flat region in which the strength of the magnetic field is larger than the strength of the magnetic field of the peeler region and smaller than the strength of the magnetic field of the regenerator region.

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.

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.

An object of the present invention is to speed up an operation of extracting an ion beam from an accelerator. An accelerator 100 includes an upper magnetic pole 8 and a lower magnetic pole 9 sandwiching an ion circulation space 10 in which ions circulate. At least one of the upper magnetic pole 8 and the lower magnetic pole 9 is formed such that a magnetic pole interval between the upper magnetic pole 8 and the lower magnetic pole 9 varies when the ion circulation space 10 is viewed along an ion beam trajectory. That is, a wide interval region 11 having a larger magnetic pole interval than a peripheral region is formed in a region closer to a center point of the ion circulation space 10 than a center point of the ion beam trajectory.

An object of the present invention is to speed up an operation of extracting an ion beam from an accelerator. An accelerator 100 includes an upper magnetic pole 8 and a lower magnetic pole 9 sandwiching an ion circulation space 10 in which ions circulate. At least one of the upper magnetic pole 8 and the lower magnetic pole 9 is formed such that a magnetic pole interval between the upper magnetic pole 8 and the lower magnetic pole 9 varies when the ion circulation space 10 is viewed along an ion beam trajectory. That is, a wide interval region 11 having a larger magnetic pole interval than a peripheral region is formed in a region closer to a center point of the ion circulation space 10 than a center point of the ion beam trajectory.