JP6385625B1 - Accelerator and particle beam therapy system - Google Patents

Abstract

Provided is an accelerator equipped with a rotating capacitor capable of performing frequency modulation of a high-frequency electric field corresponding to different emission energy for each rotation direction. The accelerator supplies an acceleration electrode (4) for accelerating charged particles, an acceleration cavity (5) for supplying electric power to the acceleration electrode (4) and generating a high-frequency electric field, and a rotation for modulating the resonance frequency of the acceleration cavity (5). A capacitor (10). The rotating capacitor (10) rotates both in the forward direction and in the reverse direction, and takes a time change in capacitance that differs depending on the rotation direction. Frequency modulation is performed in such a manner that the change in capacitance with time in each rotation direction corresponds to different emission energy.

Description

  The present invention relates to an accelerator including a rotating condenser and a particle beam therapy system.

  In recent years, particle beam therapy in which a tumor is irradiated with a particle beam such as a proton beam or a carbon beam has attracted attention. In particle beam therapy, an accelerator that accelerates charged particles to high energy is used to generate a particle beam. The accelerator forms a high-frequency electric field synchronized with the circulating frequency of the charged particles, and accelerates the charged particles to a predetermined energy. In order to accelerate the charged particles to a predetermined energy, it is necessary to perform frequency modulation of the high-frequency electric field so as to match the frequency of the charged particles. Therefore, an accelerator equipped with a rotating capacitor that performs frequency modulation of a high-frequency electric field has been developed. Patent Document 1 discloses an accelerator including a rotating condenser capable of suppressing eddy currents and reducing heat generation.

JP 2013-157556 A

  However, in order to accelerate charged particles to a predetermined energy, it is necessary to perform frequency modulation suitable for the magnitude of energy, and conventional rotary capacitors perform frequency modulation of the high-frequency electric field corresponding to different energies. There was a problem that it was difficult.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an accelerator including a rotating capacitor capable of performing frequency modulation of a high-frequency electric field corresponding to different energy of charged particles. And Moreover, it aims at providing the particle beam therapy apparatus provided with the accelerator.

  The accelerator according to the present invention is opposed to an acceleration electrode that accelerates charged particles, an acceleration cavity that supplies electric power to the acceleration electrode and generates a high-frequency electric field, a rotating electrode that rotates in both forward and reverse directions, and the rotating electrode. The fixed electrode is arranged in such a manner that the frequency modulation of the high-frequency electric field corresponding to the first emission energy of the charged particles is performed by the forward rotation, and the second emission energy of the charged particles is adjusted by the reverse rotation. And a rotating capacitor that performs frequency modulation of the high-frequency electric field.

  The particle beam therapy system according to the present invention includes an accelerator having a rotating capacitor that performs frequency modulation in accordance with the output energy for each of the forward and reverse rotation directions, and beam transport for transporting the particle beam emitted by the accelerator. And an irradiation unit for forming the particle beam supplied from the beam transport unit into an irradiation field and irradiating the irradiated object.

  According to the accelerator according to the present invention, it is possible to efficiently emit particle beams having different energies by including a rotating capacitor that performs frequency modulation of a high-frequency electric field corresponding to different emission energies for each rotation direction. . Moreover, according to the particle beam therapy system according to the present invention, it is possible to irradiate a particle beam having an energy suitable for each tumor type and position by providing an accelerator capable of emitting a particle beam having a different energy.

1 is a schematic plan cross-sectional view of an accelerator according to Embodiment 1 of the present invention. It is a schematic sectional side view of the accelerator which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the rotary capacitor which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the rotating electrode which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the fixed electrode which concerns on Embodiment 1 of this invention. It is a related figure which shows the change of the electrostatic capacitance with respect to the rotation angle of the rotary capacitor which concerns on Embodiment 1 of this invention. It is a relationship figure which shows the time change of the electrostatic capacitance of the rotary capacitor which concerns on Embodiment 1 of this invention. It is process drawing which shows an example of the process of determining the shape of the rotation capacitor which concerns on Embodiment 1 of this invention. It is a relationship figure which shows the relationship between the orbit radius and magnetic field intensity which concern on Embodiment 1 of this invention. It is a relationship diagram which shows the relationship between the acceleration time which concerns on Embodiment 1 of this invention, and a circulation frequency. It is a relationship diagram which shows the relationship between the acceleration time which concerns on Embodiment 1 of this invention, and an electrostatic capacitance. It is explanatory drawing for demonstrating the rotary capacitor which concerns on Embodiment 1 of this invention. It is a relationship figure which shows the relationship between the acceleration time which concerns on Embodiment 1 of this invention, and the time change rate of an opposing area. It is a schematic block diagram which shows the fixed electrode which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the rotating electrode which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the fixed electrode which concerns on Embodiment 1 of this invention. It is a schematic block diagram of the accelerator which concerns on Embodiment 2 of this invention. It is a schematic block diagram which shows the time change of the electrostatic capacitance of the rotary capacitor which concerns on Embodiment 2 of this invention. It is a schematic block diagram of the particle beam therapy apparatus which concerns on Embodiment 3 of this invention.

  Embodiments according to the present invention will be described with reference to the drawings. Hereinafter, a synchrocyclotron (hereinafter simply referred to as an accelerator) will be described as an example of the accelerator.

Embodiment 1 FIG.
FIG. 1 is a schematic plan sectional view of an accelerator according to Embodiment 1 for carrying out the present invention. FIG. 2 is a schematic cross-sectional side view of the accelerator according to Embodiment 1 for carrying out the present invention. As shown in FIGS. 1 and 2, the accelerator 1 includes a pair of coils 2 a and 2 b, a pair of magnetic poles 3 a and 3 b, an acceleration electrode 4, an acceleration cavity 5, an exit duct 6, and a rotating capacitor 10. Prepare.

  The accelerator 1 generates a magnetic field between the magnetic poles 3a and 3b that are spaced apart from each other when a current is applied to the coils 2a and 2b. Further, a high frequency electric field is generated by supplying high frequency power to the acceleration electrode 4 through the acceleration cavity 5. Due to the generated magnetic field, charged particles made incident from the ion source 7 (not shown) circulate around the magnetic poles 3a and 3b in a spiral orbit 8. Each time the charged particles pass through the gap 41 of the accelerating electrode 4, the charged particles are accelerated by a high-frequency electric field synchronized with the circulating frequency of the charged particles to increase energy. As the energy of the charged particles increases, the radius of the orbit 8 gradually increases, and when the charged particles reach a predetermined energy, they are emitted from the emission duct 6 as a particle beam.

  The acceleration cavity 5 has an inner conductor 5a and a cylindrical outer conductor 5b arranged coaxially. The inner conductor 5 a is electrically connected to the acceleration electrode 4 and supplies high-frequency power from a high-frequency power source 9 (not shown) to the acceleration electrode 4. The accelerating cavity 5 has a specific resonance frequency, and generates a high-frequency electric field corresponding to the resonance frequency by supplying high-frequency power to the acceleration electrode 4. The resonance frequency fr of the acceleration cavity 5 is determined by the equation (1) by the inductance L and the capacitance C of the acceleration cavity 5.

・・・式（１）

... Formula (1)

  As the charged particles are accelerated, the mass increases due to the relativistic effect, and the circulation frequency decreases. The acceleration cavity 5 decreases the resonance frequency by increasing the electrostatic capacity by the rotating capacitor 10 in accordance with the decrease in the circulation frequency.

  The rotating capacitor 10 includes a rotating electrode 11, a fixed electrode 12, and a rotating shaft 13. The rotating electrode 11 is electrically connected to the inner conductor 5a of the acceleration cavity 5, and the fixed electrode 12 is electrically connected to the outer conductor 5b. The rotating capacitor 10 has at least one set of the rotating electrode 11 and the fixed electrode 12 and is alternately stacked in the axial direction of the rotating shaft 13. The rotating capacitor 10 periodically changes the capacitance so as to obtain the resonance frequency of the accelerating cavity 5 synchronized with the circulating frequency of the charged particles by continuously rotating the rotating electrode 11 at a high speed.

  FIG. 3 is a schematic configuration diagram of the rotating capacitor according to the first embodiment for carrying out the present invention. FIG. 3 shows the rotating condenser as viewed from the AA 'plane of FIGS. As shown in FIG. 3, each of the rotating electrode 11 and the fixed electrode 12 has at least one blade and is disposed to face each other. The rotary electrode 11 is driven by a motor 14 and continuously rotates at a high speed in both the forward direction 15 and the reverse direction 16 via the rotary shaft 13. The rotation direction and rotation speed of the motor 14 are controlled by a signal from a control unit (not shown).

  FIG. 4 is a schematic configuration diagram of the rotating electrode of the rotating capacitor according to the first embodiment for carrying out the present invention. As shown in FIG. 4, the rotating electrode 11 is provided so as to extend radially outward from the rotating shaft 13 in the radial direction. The blades of the rotary electrode 11 are formed so as to be asymmetric with respect to a central axis 113 (hereinafter simply referred to as a central axis) that passes through the center position of the distal end portion 112 radially outward from the rotation center 111. For example, the side 11a extending radially inward from one end of the tip 112 of the blade is formed to bend toward the other side 11b facing each other.

  FIG. 5 is a schematic configuration diagram of the fixed electrode of the rotating capacitor according to the first embodiment for carrying out the present invention. As shown in FIG. 5, the fixed electrode 12 has, for example, a circular outer periphery concentric with the rotation center 111 and is provided so as to extend radially inward from the outer periphery. The blade of the fixed electrode 12 has a tip 121 that forms part of the outer periphery, and side sides 12 a and 12 b that extend radially inward from both ends of the tip 121.

  Here, FIGS. 3, 4, and 5 show examples in which the blades of the rotating electrode 11 and the fixed electrode 12 are four, but the number of blades may be changed as appropriate.

  FIG. 6 is a relationship diagram showing the relationship between the rotation angle and the capacitance of the rotating capacitor according to the first embodiment for carrying out the present invention. Here, it is assumed that each of the rotating electrode 11 and the fixed electrode 12 is composed of one blade. Further, when rotating in the forward direction 15, the rotation angle is between the side 11 a and 11 b facing the blades of the rotating electrode 11, the side 11 a on the positive side in the rotation direction, and the side 12 a and 12 b facing the fixed electrode 12. The position at which the side 12b on the negative side in the rotational direction begins to overlap is defined as 0 degrees as a reference.

  As shown in FIG. 6, in the rotating capacitor 10, as the rotation angle increases, the facing area between the blades of the rotating electrode 11 and the fixed electrode 12 increases, and the capacitance increases accordingly. For example, the electrostatic capacitance of the rotating capacitor 10 is maximized at the rotation angle θ1 and decreases as the facing area decreases. Rotation in which the side 11b on the negative side in the rotation direction, the side 12a, 12b on the fixed electrode 12 facing each other, and the side 12a on the positive side in the rotation direction are out of the sides 11a and 11b facing the blades of the rotation electrode 11. The electrostatic capacitance is minimized at the angle θ2.

  FIG. 7 (a) shows a change in capacitance with time when the rotating capacitor according to Embodiment 1 for carrying out the present invention is rotated once in the forward direction at a predetermined rotational speed. FIG. 7B shows the change in capacitance with time when the rotating capacitor according to the first embodiment for carrying out the present invention is rotated once in the reverse direction at the same rotational speed as in FIG. 7A. It is. As shown in FIGS. 7A and 7B, the rotating capacitor 11 is formed asymmetrically with respect to the central axis 113, so that the rotating capacitor 10 has a forward direction 15 and a reverse direction 16. It is possible to take time changes of different capacitances. As a result, it is possible to perform frequency modulation by making the time changes of the capacitances different in the forward direction 15 and the reverse direction 16 correspond to different emission energies.

  When the charged particles are emitted with the emission energy E1, the accelerator 1 rotates the rotating capacitor 10 in the forward direction 15 to increase the capacitance from the time t1 when the charged particles are incident to the time t2 when the charged particles are emitted, thereby performing frequency modulation of the high-frequency electric field. . When the charged particles are emitted with the emission energy E2, the accelerator 1 rotates the rotating capacitor 10 in the reverse direction 16 to increase the capacitance from the charged particle incident time t′1 to the outgoing time t′2. Performs frequency modulation of the high-frequency electric field.

  In this way, the rotating condenser 10 rotates in the forward direction 15 and the reverse direction 16 and takes time change of the electrostatic capacity according to the different output energy for each rotation direction, so that the accelerator 1 has a particle beam with different output energy. Can be efficiently emitted.

  Next, an example of a method for determining the shape of the rotating capacitor 10 so as to change the capacitance with time corresponding to different output energy for each rotation direction will be described. FIG. 8 is a process diagram showing an example of a process for determining the shape of the rotating capacitor according to the first embodiment for carrying out the present invention. For example, it is assumed that the rotating capacitor 10 takes a time-varying capacitance suitable for rotation in the forward direction 15 to output energy 215 MeV and rotation in the reverse direction 16 to output energy 160 MeV, respectively (step S1).

  Assuming that the maximum magnetic field strength of the accelerator 1 is 6T, a magnetic field distribution with respect to the orbit radius is determined for each emission energy (step S2). The magnetic field strength of the accelerator 1 is distributed so as to decrease as the orbit radius increases based on the principle of weak convergence in order to stably accelerate charged particles. FIG. 9 shows the magnetic field strength with respect to the orbit radius according to the first embodiment for carrying out the present invention. As shown in FIG. 9, the magnetic field strength with respect to the orbit radius is set to be smaller for the outgoing energy 160 MeV than for the outgoing energy 215 MeV. The magnetic field strength is adjusted by, for example, a current applied to the coils 2a and 2b.

  From the set magnetic field distribution, the orbital frequency with respect to the acceleration time is calculated (step S3). Here, the acceleration time is the time taken for charged particles to enter and exit from the accelerator 1. When the charged particle is a proton and the orbit radius at the initial stage of acceleration is r, the orbital frequency of the charged particle at the acceleration time T is determined by the equations (2) to (6).

・・・式（２）

・・・式（３）

・・・式（４）

・・・式（５）

・・・式（６）

... Formula (2)

... Formula (3)

... Formula (4)

... Formula (5)

... Formula (6)

Where E is the energy of the charged particles, dE is the energy that increases with each round, M ₀ is the mass of the charged particles in the early stage of acceleration, B (r) is the magnetic field strength in the early stage of acceleration, and B (r ′) is the orbital radius. The magnetic field strength at r ′, E (r ′) is the energy of the charged particle at the orbit radius r ′, f (r ′) is the orbiting frequency at the orbit radius r ′, and t (r ′) is the orbiting period at the orbit radius r ′. , T (r ′) is the acceleration time at the orbit radius r ′.

  Based on r as the orbit radius in the initial stage of acceleration, the energy E of the charged particles is calculated from the equation (2). The orbit radius r 'is calculated based on the energy E of the charged particles that increases from the equation (3). An orbital frequency f (r ') at the orbit radius r' is obtained from the equation (4). The time required for one round is calculated from equation (5). The time T (r ') with respect to the orbit radius r' from the initial stage of acceleration is calculated from the equations (4) and (6). In this way, the circulation frequency at the acceleration time T can be obtained.

  FIG. 10 shows the orbital frequency with respect to the acceleration time according to Embodiment 1 for carrying out the present invention. As shown in FIG. 10, when the emission energy of charged particles is 215 MeV, the orbital frequency is 89 MHz at the beginning of acceleration, 67 MHz at the time of emission, and the necessary frequency modulation width is 22 Hz. When the emission energy is 160 MeV, the circulation frequency is 78 MHz at the initial stage of acceleration, 62 MHz at the time of emission, and the necessary frequency modulation width is 16 MHz.

  The electrostatic capacity with respect to the acceleration time is calculated from the circulation frequency with respect to the calculated acceleration time and the equation (1) (step S4). FIG. 11 shows the capacitance with respect to the acceleration time according to Embodiment 1 for carrying out the present invention. As shown in FIG. 11, the rotating capacitor 10 accelerates the capacitance so that when rotating in the forward direction 15, frequency modulation of 22 Hz is performed, and when rotating in the reverse direction 16, frequency modulation of 16 MHz is performed. Increase against.

From the capacitance with respect to the calculated acceleration time, the time change rate of the facing area of the rotating electrode 11 and the fixed electrode 12 of the rotating capacitor 10 with respect to the acceleration time is calculated (step S5). Here, as shown in FIG. 12, the rotational speed of the rotating capacitor 10 is 7500 rpm, the number of layers of the rotating electrode 11 and the stationary electrode 12 in the direction of the rotational axis is five, the number of blades is four, the rotating electrode 11 and the stationary electrode, respectively. The electrode interval of 12 is 2 mm. The capacitance of the rotating condenser 10 C is facing area S of the rotating electrode 11 and the fixed electrode 12, the inter-electrode distance d, a dielectric constant epsilon ₀ of the vacuum is determined from the equation (7).

・・・式（７）

... Formula (7)

  From the equation (7), the capacitance with respect to the acceleration time shown in FIG. 11 can be expressed by the time change rate of the facing area with respect to the acceleration time. FIG. 13 is a time change rate of the facing area with respect to the acceleration time of the rotating capacitor according to the first embodiment for carrying out the present invention.

  Based on the time change rate of the facing area with respect to the acceleration time shown in FIG. 13, the shapes of the rotating electrode 11 and the fixed electrode 12 are determined (step S6).

  As an example, as shown in FIG. 14, the blade of the fixed electrode 12 is symmetric with respect to the central axis 123 passing through the center position of the tip 121 of the blade of the fixed electrode 12 from the rotation center 111 of the rotating electrode 11. The shape of the rotating electrode 11 is determined. When the fixed electrode 12 is symmetric with respect to the central axis 123, the time change rate dS / dt of the facing area S is the length l from the rotation center 111 of the rotating electrode 11 to the tip 112 of the blade of the rotating electrode 11, It is determined from equation (8) at the rotational speed ω.

・・・式（８）

... Formula (8)

  From equation (8), the length from the rotation center 111 to the tip 112 of the rotating electrode 11 can be determined from the time change rate of the facing area. FIG. 15A is a schematic configuration diagram showing an example of a rotating electrode according to Embodiment 1 for carrying out the present invention. FIG. 15B is a schematic configuration diagram showing an example of the shape of one blade of the rotating electrode according to Embodiment 1 for carrying out the present invention. As shown in FIGS. 15 (a) and 15 (b), the rotating electrode 11 has a rotation direction so that the length from the rotation center 111 to the tip 112 satisfies the time change rate of the facing area with respect to the acceleration time. The shape changes.

  The blade tip 112 of the rotating electrode 11 is curved radially inward with respect to the central axis 113 so as to be asymmetric. The rotating electrode 11 is curved so that, for example, the tip 112a on one side with respect to the central axis 113 satisfies the time change rate of the facing area of the emission energy 215MeV. Further, the tip 112b on the other side with respect to the central axis 113 is curved so as to satisfy the time change rate of the facing area of the emission energy 160 MeV.

  By forming the rotating electrode 11 in this way, the accelerator 1 rotates the rotating electrode 11 in the forward direction 15 when emitting a particle beam of 215 MeV, so that one side of the rotating electrode 11 with respect to the central axis 113 is rotated. When a 160 MeV particle beam is emitted by performing frequency modulation using the front end portion 112a, the rotating electrode 11 is rotated in the reverse direction 16, and the front end portion 112b on the other side with respect to the central axis 113 is used. It becomes possible to perform frequency modulation.

  Here, the fixed electrode 12 is symmetric with respect to the central axis 123 and the rotating electrode 11 is asymmetric with respect to the central axis 113, but the blade shape of the rotating electrode 11 is symmetric and the blade shape of the fixed electrode 12 is asymmetric. Also good. FIG. 16A is a schematic configuration diagram showing an example of a fixed electrode according to Embodiment 1 for carrying out the present invention. FIG.16 (b) is a schematic block diagram which shows an example of the shape of one blade | wing of the fixed electrode which concerns on Embodiment 1 for implementing this invention. As shown in FIGS. 16 (a) and 16 (b), the fixed electrode 12 has a length from the rotation center 111 of the rotating electrode 11 to the inner peripheral portion 122 of the fixed electrode 12 that is the time of the facing area with respect to the acceleration time. The shape changes with respect to the rotation direction so as to satisfy the rate of change.

  For example, the inner peripheral portion 122 of the blade of the fixed electrode 12 is curved outward in the radial direction so as to be asymmetric with respect to the central axis 123. For example, the fixed electrode 12 is curved so that the inner peripheral portion 122a on one side with respect to the central axis 123 satisfies the time change rate of the facing area of the emission energy 215MeV. Further, the inner peripheral portion 122b on the other side with respect to the central axis 123 is curved so as to satisfy the emission energy 160 MeV.

  By forming the fixed electrode 12 in this way, when the accelerator 1 emits a particle beam of 215 MeV, the accelerator 1 rotates the rotating electrode 11 in the forward direction 15 to one side with respect to the central axis 123 of the fixed electrode 12. When the frequency modulation is performed by using the inner peripheral portion 122a of the laser beam and the particle beam of 160 MeV is emitted, the rotating electrode 11 is rotated in the reverse direction 16 and the inner peripheral portion 122b on the other side with respect to the central axis 123 is used. Thus, frequency modulation can be performed.

  Here, although the example in which the rotating electrode 11 or the fixed electrode 12 is symmetric with respect to the central axes 113 and 123 is shown, the rotating capacitor 10 changes the capacitance with time according to the output energy that differs in each rotation direction. The rotating electrode 11 and the fixed electrode 12 may be asymmetric with respect to the central axes 113 and 123, respectively.

  As described above, the accelerator 1 according to the present embodiment rotates in the forward direction 15 and the reverse direction 16 and rotates in such a manner that the capacitance changes with time in response to different emission energy of charged particles in each rotation direction. The capacitor 10 is provided. With this configuration, the accelerator 1 can efficiently generate particle beams having different energies.

  In addition, it is more preferable that the shape of the rotating electrode 11 of the rotating capacitor 10 is formed so that mechanical stability against high-speed rotation is taken into consideration. For example, the rotation angle θ1 until the capacitance shown in FIG. 6 reaches the maximum, and the angle θ2−θ1 formed by the rotation angle θ1 that maximizes the capacitance and the rotation angle θ2 that minimizes the capacitance. The difference is formed such that 0 <| θ2-1 | / θ1 | ≦ 10%. Thereby, in order to modulate the resonance frequency of the accelerating cavity 5, even when the rotating electrode 11 is rotated at a high speed of, for example, 1000 rpm or more, it is possible to perform rotation while maintaining stability.

Embodiment 2. FIG.
An accelerator 1 according to Embodiment 2 for carrying out the present invention will be described. Here, the description which overlaps with the accelerator 1 which concerns on Embodiment 1 is simplified or abbreviate | omitted suitably. In the present embodiment, the incident control device 17 is further provided in the configuration of the first embodiment.

  FIG. 17 is a schematic configuration diagram of an accelerator according to Embodiment 2 for carrying out the present invention. The incident control device 17 controls the timing at which charged particles are incident on the accelerator 1 from the ion source 7. The incident control device 17 outputs, for example, a signal for entering charged particles to the ion source 7 so that the capacitance increases from incident to emission of charged particles by detecting the capacitance of the rotating capacitor 10. .

  18 (a) and 18 (b) are relationships showing changes in capacitance with time when the rotating capacitor according to the second embodiment for carrying out the present invention is rotated in the forward direction and the reverse direction, respectively. FIG. As shown in FIG. 18A, when the rotating condenser 10 continuously rotates in the forward direction 15 according to the emission energy E1, the electrostatic capacity of the rotating condenser 10 corresponds to the electrostatic frequency corresponding to the initial rotation frequency. Whenever the capacity C1 is reached, a signal A for entering charged particles is output. Further, as shown in FIG. 18B, when the rotating condenser 10 continuously rotates in the reverse direction 16 according to the emission energy E2, the capacitance of the rotating condenser 10 corresponds to the circulation frequency at the initial stage of acceleration. Each time the capacitance C2 is reached, a signal A for entering charged particles is output. As described above, the incident control device 17 causes the charged particles to periodically enter the accelerator 1 at a timing suitable for acceleration according to the emission energy for each rotation direction.

  Here, as an example of the method for setting the incident timing, an example in which the electrostatic capacitance of the rotating capacitor 10 is detected has been shown. In addition, the rotation angle of the rotating capacitor 10, the electrostatic capacitance of the accelerating cavity 5, and the resonance frequency of the accelerating cavity 5 are shown. Etc. may be detected.

  Even in such a configuration, as in the first embodiment, the accelerator 1 includes the rotating capacitor 10 that performs frequency modulation in accordance with the emission energy of the charged particles for each rotation direction, and emits particle beams having different energies. Can be made. Furthermore, in the present embodiment, the configuration including the incident control device 17 allows charged particles to be periodically incident at a timing suitable for acceleration according to the magnitude of the output energy, and particle beams having different energies. Can be emitted more efficiently. Further, pulsed charged particles can be continuously incident at a timing suitable for acceleration, and a sufficient dose of particle beam can be generated.

Embodiment 3 FIG.
A particle beam therapy system 100 according to Embodiment 3 for carrying out the present invention will be described. In the present embodiment, the accelerator 1 according to the first or second embodiment is configured to be applied to the particle beam therapy system 100. The description overlapping with the accelerator 1 according to the first and second embodiments is appropriately simplified or omitted.

  FIG. 19 is a schematic configuration diagram of a particle beam therapy system according to Embodiment 3 for carrying out the present invention. As shown in FIG. 19, the particle beam therapy system 100 forms an accelerator 1, a beam transport unit 20 that transports the particle beam emitted by the accelerator 1, and a particle beam supplied from the beam transport unit 20 in an irradiation field. And an irradiation unit 30 for irradiating the irradiated object.

  The accelerator 1 is supplied with high frequency power from a high frequency power source 9 and forms a high frequency electric field therein. The accelerator 1 determines the rotation direction of the rotating capacitor 10 according to predetermined emission energy, and modulates the frequency of the high-frequency electric field. Charged particles incident from the ion source 7 are accelerated to a predetermined energy by a high-frequency electric field that is frequency-modulated by the rotating condenser 10 and are emitted as a particle beam.

  The particle beam emitted by the accelerator 1 is emitted to the beam transport unit 20. The beam transport unit 20 includes a vacuum duct serving as a particle beam transport path and a deflection electromagnet that deflects the beam trajectory of the particle beam to a predetermined angle. The irradiation unit 30 shapes the particle beam supplied from the beam transport unit 20 into an irradiation field corresponding to the size and depth of the tumor to be treated, and irradiates the irradiated object.

  According to the particle beam therapy system 100 according to the present embodiment, treatment is provided by including the accelerator 1 having the rotating capacitor 10 that performs frequency modulation according to the emission energy for each of the forward direction 15 and the reverse direction 16 in the rotational direction. Depending on the size and depth of the tumor, it is possible to efficiently irradiate a particle beam with suitable energy. By adopting a configuration that allows the accelerator 1 to emit particle beams of different energies, energy waste is reduced and particles are efficiently generated compared to when the high-energy particle beam once generated is forcibly reduced outside the accelerator 1. Can be irradiated. Furthermore, the amount of radiation exposure to the patient can be reduced, and the burden on the patient can be reduced.

  In the first to third embodiments, a synchrocyclotron has been described as an example of the accelerator 1, but other circular accelerators may be used.

DESCRIPTION OF SYMBOLS 1 Accelerator, 2a, 2b coil, 3a, 3b Magnetic pole, 4 Acceleration electrode, 5 Acceleration cavity, 6 Outlet duct, 7 Ion source, 8 orbit, 9 High frequency power supply, 10 Rotation capacitor, 11 Rotation electrode, 12 Fixed electrode, 13 Rotation axis, 14 motor, 15 forward direction, 16 reverse direction, 111 center of rotation, 112 tip, 113 center axis, 121 tip, 122 inner circumference, 123 center axis, 17 incident control device, 100 particle beam therapy device, 20
Beam transport section 30, irradiation section.

Claims (5)

An acceleration electrode for accelerating charged particles;
An accelerating cavity for supplying electric power to the accelerating electrode and generating a high-frequency electric field;
The high-frequency electric field having a rotating electrode rotating in both the forward direction and the reverse direction, and a fixed electrode arranged to face the rotating electrode, and corresponding to the first emission energy of the charged particles by the rotation in the forward direction And a rotating capacitor that performs frequency modulation of the high-frequency electric field according to second emission energy of the charged particles by rotating in the reverse direction. The rotating electrode of the rotating capacitor has at least one blade, and is formed asymmetrically with respect to a central axis passing from a rotation center to a center position of a tip portion of the blade of the rotating electrode. The accelerator according to claim 1. The fixed electrode of the rotating capacitor has at least one blade, and is formed asymmetrically with respect to a central axis passing from the rotation center to a center position of a tip portion of the blade of the fixed electrode. The accelerator according to claim 1 or 2. An incident control device is provided that detects at least one of a capacitance, a rotation angle, a capacitance of the acceleration cavity, and a resonance frequency of the rotating capacitor, and controls an incident timing of the charged particles. Item 4. The accelerator according to any one of items 1 to 3. The accelerator according to any one of claims 1 to 4, comprising the rotating condenser that performs frequency modulation in accordance with emission energy for each of the forward and reverse rotation directions;
A beam transport unit for transporting the particle beam emitted by the accelerator;
A particle beam therapy system comprising: an irradiation unit configured to form the particle beam supplied from the beam transport unit into an irradiation field and irradiate an irradiated object.

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