Energy-adjustable separation fan-shaped isochronous particle cyclotron

Abstract

An energy-adjustable separated fan-shaped isochronous particle cyclotron comprises an injector (1) with adjustable energy and adjustable frequency, a radial particle beam injection system (2), 2N (N is greater than or equal to 2) fan-shaped bending magnets (3) with adjustable average magnetic field intensity and adjustable magnetic field gradient, and 2M (M is greater than or equal to 1) resonant acceleration mechanisms (4) with adjustable acceleration frequency. And a particle beam extraction system (5) and other parts for ensuring the operation of the accelerator. The separation fan-shaped isochronous particle cyclotron meeting the conditions can realize the adjustable energy of the extracted particle beam D (400).

Description

Technical Field

[0001] "An energy-adjustable separated sector isochronous particle cyclotron" is specially made for tumor radiotherapy. The accelerated particles are the particles required for radiotherapy, such as protons or carbon ions. Background Art

[0002] The particle accelerators currently used for tumor radiotherapy mainly include cyclotrons and synchrotrons. In comparison, the cyclotron beam is continuous and has high beam intensity, but the particle energy is not adjustable; the synchrotron beam is discontinuous and has low beam intensity, but the particle energy is adjustable. Generally speaking, if a cyclotron accelerator wants to achieve energy adjustment, an external de-energizer is required. After passing through the de-energizer, the particle energy decreases, but the beam intensity also decreases. In order to achieve energy adjustment without reducing the beam intensity of the cyclotron accelerator, many scientific and technological workers have explored, such as accelerating H - ions, stripping H at different gyration radii - The extranuclear electrons of the ions are converted into protons and are led out after changing their trajectory; for example, particle beams are led out at different radii of the particle cyclotron. The present invention explores a new type of cyclotron accelerator, which can achieve energy adjustment without reducing the beam intensity under the following conditions: 1. The energy and frequency of the injector are adjustable; 2. The magnetic field strength and magnetic field gradient of the cyclotron are adjustable; 3. The frequency of the resonant acceleration mechanism is adjustable. The present invention plans to use an isochronous cyclotron accelerator because the energy of particles used in radiotherapy is very high, such as proton energy must reach 230MeV, while the classical cyclotron accelerator can only accelerate protons to more than twenty MeV. The present invention plans to use a separated sector cyclotron accelerator because radial injection can be used to improve injection efficiency and thus increase beam intensity. Summary of the invention

[0003] The present invention transforms the operation mechanism of the traditional isochronous cyclotron, and by means of the structural features of the separated sector cyclotron, adopts a radial injection method, and realizes the energy adjustment of particles without changing the electrical properties of the accelerated particles, the particle beam extraction radius, or reducing the beam intensity. The specific invention contents are as follows: The starting end of an energy-adjustable separated sector isochronous particle cyclotron accelerator is an injector, which provides a particle beam A with adjustable energy and frequency.

[0004] Furthermore, a radial particle beam injection system is provided to receive the particle beam A provided by the injector.

[0005] Furthermore, 2N (N≧2) axially symmetrically arranged fan-shaped bending magnets are set to receive the particle beam B provided by the radial injection system and bend the accelerated particle beam C. It is required that the average magnetic field strength between the upper and lower poles of the fan-shaped bending magnets is adjustable, and the magnetic field gradient from the position of the small radius bending beam CA to the position of the large radius bending beam CB is adjustable.

[0006] Furthermore, 2M (M≧1) resonant acceleration mechanisms are provided and axially symmetrically installed between the separated sector-shaped bending magnets, responsible for accelerating the particle beam C rotating between the upper and lower magnetic poles of the separated sector-shaped bending magnets. The acceleration frequency of the resonant acceleration mechanism is required to be adjustable.

[0007] Furthermore, a particle beam extraction system is provided to extract the large-radius bent beam CB.

[0008] Furthermore, other components that ensure the operation of the accelerator are configured.

[0009] The separated sector isochronous particle cyclotron accelerator that meets the above conditions can realize the adjustable energy of the particle beam D provided by the particle beam extraction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 , Plan view of the energy-adjustable separation sector isochronous particle cyclotron Figure 2 , Plan view of radial particle beam injection system Symbols in the figure: 1. Injector, 1-1. Ion source, 1-2. Tandem electrostatic accelerator, 1-3. Buncher 2. Radial particle beam injection system, 2-1. Bending magnet, 2-2. Electrostatic deflector A 3. 2N axially symmetrically arranged fan-shaped bending magnets, 3-1. Upper and lower magnetic poles 4. 2M resonant acceleration mechanisms 5. Particle beam extraction system, 5-1. Electrostatic deflector B 100. Particle beam A provided by the injector, 200. Particle beam B running in the radial particle beam injection system, 300. Particle beam C swirling in 2N separate sector-shaped bending magnets, 301. Small radius bending particle beam CA, 302. Large radius bending particle beam CB, 400. Particle beam D provided by the particle beam extraction system DETAILED DESCRIPTION

[0011] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Without violating the scope of the present invention, the present invention is not limited by the specific embodiments disclosed below.

[0012] This embodiment is a separation sector isochronous particle cyclotron accelerator with adjustable energy.

[0013] like Figure 1 As shown, this embodiment includes an injector 1, which provides a particle beam A100 with adjustable energy and adjustable frequency.

[0014] The injector 1 described in this embodiment has multiple options, provided that the energy and frequency of the particle beam A100 provided by it are adjustable, and this patent does not limit it.

[0015] Figure 1 The injector 1 shown includes, from left to right, a negative ion source 1-1, a tandem electrostatic accelerator 1-2 and a buncher 1-3, wherein the tandem electrostatic accelerator 1-2 can provide a continuous positive ion beam A100 of different energies; the buncher 1-3 can realize a bunching function at different frequencies.

[0016] like Figure 1 and Figure 2 As shown, this embodiment also includes a radial particle beam injection system 2, which receives the particle beam A100 provided by the injector 1 and keeps the trajectory of the particle beam B200 running in the injection system 2 unchanged.

[0017] The radial particle beam injection system 2 is mainly composed of a bending magnet 2-1 and an electrostatic deflector A2-2, and the specific combination thereof is not limited in this patent.

[0018] Since the energy of the ion beam A100 provided by the injector 1 is adjustable, the electric field strength of the electrostatic deflector A2-2 and the magnetic field strength of the bending magnet 2-1 need to be adjusted accordingly to keep the trajectory of the particle beam B200 running in the injection system 2 unchanged.

[0019] like Figure 1 As shown, this embodiment further includes 2N (N≧2) axially symmetrically arranged fan-shaped bending magnets 3, which receive the particle beam B200 provided by the radial injection system 2 and bend the accelerated particle beam C300.

[0020] The average magnetic field strength between the upper and lower magnetic poles 3-1 of the sector-shaped bending magnet 3 is adjustable, and the magnetic field gradient from the position of the small radius bending particle beam CA301 to the position of the large radius bending particle beam CB302 is adjustable.

[0021] Each sector-shaped bending magnet 3 includes a magnetic pole 3-1, an excitation coil and a magnetic yoke. For simplicity, Figure 1 The magnetic pole 3-1 represents the separated sector-shaped bending magnet 3.

[0022] Magnetic pole 3-1 is divided into upper and lower magnetic poles, in order to see the small radius bending particle beam CA301, the large radius bending particle beam CB302 and the rotating particle beam C300, Figure 1 A magnetic pole 3-1 above a separated sector-shaped bending magnet 3 is hidden.

[0023] from Figure 1 It can also be seen in the figure that, among the 2N separated sector-shaped bending magnets 3, the particle beam B200 provided by the radial injection system 2 is received at the position of the small radius bending particle beam CA301 of one sector-shaped bending magnet 3.

[0024] like Figure 1 As shown, this embodiment also includes 2M (M≧1) resonant acceleration mechanisms 4, which are axially symmetrically installed between the separated sector-shaped bending magnets 3 and are responsible for accelerating the particle beam C300 rotating between the upper and lower magnetic poles 3-1 of the separated sector-shaped bending magnets 3. The acceleration frequency of the resonant acceleration mechanism 4 is adjustable.

[0025] Figure 1 The rotating particle beam C300 shown is separated for the convenience of drawing. In fact, the rotating particle beams C300 of each circle are connected end to end, and the circumference gradually increases. The inner circle particle beam C300 is connected to the small radius bent beam CA301, and the outer circle particle beam C300 is connected to the large radius bent beam CB302.

[0026] like Figure 1 As shown, this embodiment further includes a particle beam extraction system 5, which is responsible for extracting the large-radius bent beam CB302 and keeping the trajectory of the particle beam D400 running in the particle beam extraction system 5 unchanged; The particle beam extraction system 5 mainly includes an electrostatic deflector B5-1, a bending magnet and a focusing magnet, etc. For the sake of simplicity, Figure 1 The electrostatic deflector B5-1 is used to represent the particle beam extraction system 5.

[0027] In addition to the above components, this embodiment also includes other components to ensure the operation of the accelerator. The cyclotron is a very complex system. For the convenience of patent description, only the components related to the patent description are listed. Other components mainly include beam transport related components, high-frequency power source, vacuum system, cooling device, beam detection system and control system. These components are indispensable to ensure the operation of the cyclotron and are summarized as "other components".

[0028] The separated sector isochronous particle cyclotron accelerator that meets the above conditions can achieve adjustable energy of the particle beam D400 provided by the particle beam extraction system 5 .

[0029] In view of the fact that the energy of the particle beam D400 finally provided is adjustable, the electric field strength of the electrostatic deflector B5-1 must also be adjusted accordingly to ensure that the trajectory of the particle beam D400 remains unchanged.

[0030] The working principle of this embodiment is described below.

[0031] 1. Known conditions 1) Select the particle to be accelerated. Once the accelerated particle is selected, its charge number (q) and rest energy (ε0) are known. The following is an example of a proton; 2) The small radius bend for receiving the proton beam is r, and the large radius bend for extracting the proton beam is R; 3) The energy modulation range of the accelerated protons, assuming that the maximum energy of the proton beam D400 is 230 MeV, denoted as W 230 , the minimum energy is 70MeV, denoted as W 70 ; 4) Assume that the harmonic number h=1, that is, the acceleration frequency f of the resonant acceleration mechanism 4 D is equal to the cyclotron frequency f of the particle.

[0032] 2. Related parameters when the proton beam D400 is at maximum energy 1) From the large turning radius R, W 230 , the charge number of the proton (q=1) and the rest energy (ε0=938 MeV), the magnetic field strength B at the large radius bend R can be calculated 230 .

[0033] 2) By R, W 230 and ε0, the cyclotron frequency f of the proton can be calculated 230 .

[0034] 3) By f 230 , small radius bend r and ε0, the energy w of the proton beam B200 received at the small radius bend r can be calculated 230 .

[0035] 4) By small radius bend r, w 230 , q and ε0, the magnetic field strength b at the small radius bend r can be calculated 230 .

[0036] 5) According to the above method, by changing the particle beam cyclotron radius between r~R, the magnetic field strength at different cyclotron points can be calculated, and then the average magnetic field strength B of the sector magnet can be calculated. 230平均 and the gradient of the magnetic field change from the small turning radius r to the large turning radius R dB / dr 230 .

[0037] 3. Related parameters when proton beam D400 is at minimum energy 1) From the large turning radius R, W 70 , the charge number (q) and the rest energy (ε0) of the proton, the magnetic field strength B at the large radius bend R can be calculated 70 .

[0038] 2) By R, W 70 and ε0, the cyclotron frequency f of the proton can be calculated 70 .

[0039] 3) By f 70 , small radius bend r and ε0, the energy w of the proton beam B200 received at the small radius bend r can be calculated 70 .

[0040] 4) By small radius bend r, w 70 , q and ε0, the magnetic field strength b at the small radius bend r can be calculated 70 .

[0041] 5) According to the above method, by changing the particle beam cyclotron radius between r~R, the magnetic field strength at different cyclotron points can be calculated, and then the average magnetic field strength B of the sector magnet can be calculated. 70平均 and the gradient of the magnetic field change from the small turning radius r to the large turning radius R dB / dr 70 .

[0042] 4. Conclusion When the proton beam energy provided by this embodiment is W 230 Changes to W 70 hour, 1) The magnetic field strength at the large radius R is given by B 230 Change to B 70 ; 2) The magnetic field strength at r in the small meridian is given by b 230 Become b 70 ; 3) The average magnetic field strength is given by B 230平均 Change to B 70平均 , which requires that the average magnetic field strength be adjustable; 4) From small radius r to large radius R, the magnetic field gradient is dB / dr 230 Convert to dB / dr 70 , which requires that the magnetic field gradient be adjustable; 5) The cyclotron frequency of the particle (i.e. the acceleration frequency of the resonant acceleration mechanism 4) is given by f 230 becomes f 70 , which requires that the acceleration frequency of the resonant acceleration mechanism 4 be adjustable; 6) The energy of the particle beam received by the small body at r is determined by w 230 becomes w 70 ; 7) Based on 5) and 6), it is required that the proton beam A100 provided by the injector 1 has an energy of w 230 ~w 70 Adjustable between f 230 ~f 70 Adjustable between; 8) Based on 1) to 7), the proton beam D400 provided by the beam extraction system 5 can be realized with an energy of W 230 ~ W 70Adjustable between.

Claims

1. An energy-adjustable separated sector isochronous particle cyclotron accelerator comprising: An injector (1) providing a particle beam A (100) with adjustable energy and adjustable frequency; A radial particle beam injection system (2) receives a particle beam A (100) provided by an injector (1) and keeps the trajectory of a particle beam B (200) running in the injection system (2) unchanged; 2N (N≧2) axially symmetrically arranged fan-shaped bending magnets (3) receive a particle beam B (200) provided by a radial injection system (2) and bend an accelerated particle beam C (300); the average magnetic field strength between the upper and lower magnetic poles (3-1) of the fan-shaped bending magnet (3) is adjustable, and the magnetic field gradient from a position of a small radius bending beam CA (301) to a position of a large radius bending beam CB (302) is adjustable; 2M (M≧1) resonant acceleration mechanisms (4) are axially symmetrically mounted between the separated sector-shaped bending magnets (3) and are responsible for accelerating the particle beam C (300) rotating between the upper and lower magnetic poles (3-1) of the separated sector-shaped bending magnets (3). The acceleration frequency of the resonant acceleration mechanism (4) is adjustable; A particle beam extraction system (5) is responsible for extracting the large-radius bent beam CB (302) and keeping the trajectory of the particle beam D (400) running in the particle beam extraction system (5) unchanged.

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