JP2018094147A - Charged-particle beam therapy apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged-particle beam therapy apparatus capable of enlarging a beam size of a charged-particle beam, while suppressing lowering of a dose.SOLUTION: A charged-particle beam therapy apparatus 1 includes: a first attenuation part 21 that causes a charged-particle beam B exited from an accelerator 3 to enter so as to lower energy of the charged-particle beam B; and an electric field generation part 23 that causes the charged-particle beam B passing through the first attenuation part 21 to enter so as to continuously generate a high-frequency electric field and converge the charged-particle beam B. Consequently, the charged-particle beam B once passing through the first attenuation part 21 is converged in the beam size by passing through the electric field generation part 23.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a charged particle beam therapy apparatus.

  Conventionally, for example, an apparatus described in Patent Document 1 is known as a charged particle beam therapy apparatus that performs treatment by irradiating a patient's affected part with a charged particle beam. In the charged particle beam treatment apparatus described in Patent Document 1, a charged particle beam accelerated by an accelerator is incident on an attenuation unit (degrader) to attenuate energy, and then is irradiated to an irradiated object.

JP2015-181655A

  Here, in the charged particle beam therapy system as described above, when the charged particle beam passes through the attenuation portion, the charged particle beam (beam) diverges to increase the beam size. Therefore, when it is required to perform irradiation with high accuracy, the beam size can be adjusted by cutting a part of the charged particle beam by using a collimator or the like. However, when such measures are taken, there arises a problem that the dose of charged particle beams decreases.

  Therefore, an object of the present invention is to provide a charged particle beam therapy apparatus that can suppress an increase in the beam size of a charged particle beam while suppressing a decrease in dose.

  In order to solve the above-described problems, a charged particle beam therapy system according to the present invention accelerates a charged particle and emits a charged particle beam having a preset energy, and enters the charged particle beam emitted from the accelerator. Thus, the charged particle beam is generated by causing the first attenuating unit to reduce the energy of the charged particle beam and the charged particle beam that has passed through the first attenuating unit to continuously generate a high-frequency electric field. An electric field generation unit for convergence; and an irradiation unit for irradiating an irradiated body with a charged particle beam emitted from the electric field generation unit.

  The charged particle beam therapy system according to the present invention makes the charged particle beam emitted from the accelerator incident, and thereby the first attenuation unit that reduces the energy of the charged particle beam and the charge that has passed through the first attenuation unit. An electric field generating unit that converges the charged particle beam by providing a particle beam and continuously generating a high-frequency electric field is provided. Therefore, once the charged particle beam that has passed through the first attenuation unit passes through the electric field generation unit, the beam size is converged. Therefore, it is possible to suppress an increase in the beam size of the charged particle beam while suppressing a decrease in dose due to blocking a part with a collimator or the like on the tip side of the irradiation unit.

  In addition, a second attenuating unit may be further provided between the electric field generating unit and the irradiating unit to reduce the energy of the charged particle beam by making the charged particle beam emitted from the electric field generating unit incident. . With such a configuration, the energy of the charged particle beam emitted from the electric field generation unit can be finely adjusted.

  The first attenuation unit reduces the energy of the charged particle beam with a single energy decrease amount or with an energy decrease amount that can be adjusted in a plurality of stages, and the second attenuation unit includes the first attenuation unit The energy of the charged particle beam may be reduced by an energy reduction amount that can be adjusted in multiple steps as compared with the attenuation unit. With such a configuration, the energy of the charged particle beam is reduced to such an extent that the first attenuation unit can be incident on the electric field generation unit, and the charged particles are reduced in a multistage energy decrease amount in the second attenuation unit. Fine adjustment of the line energy is possible.

  ADVANTAGE OF THE INVENTION According to this invention, the expansion of the beam size of a charged particle beam can be suppressed, suppressing the fall of a dose.

1 is a schematic configuration diagram of a charged particle beam therapy system according to an embodiment of the present invention. It is a schematic block diagram of the irradiation part vicinity of the charged particle beam therapy apparatus of FIG. It is a figure which shows the layer set with respect to the tumor. It is a schematic block diagram which shows the structure of an energy adjustment part. It is a schematic block diagram which shows an example of a structure of an electric field production | generation part. It is a schematic block diagram which shows an example of a structure of an electric field production | generation part. It is a schematic diagram regarding the convergence of a charged particle beam. It is a schematic block diagram which shows the structure of the energy adjustment part which concerns on a modification. It is a schematic block diagram which shows the structure of the energy adjustment part which concerns on a modification.

  Hereinafter, a charged particle beam therapy system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, a charged particle beam therapy apparatus 1 according to an embodiment of the present invention is an apparatus used for cancer treatment or the like by radiation therapy, and charged particles generated by an ion source (not shown). An accelerator 3 that emits the charged particle beam as a charged particle beam, an irradiation unit 2 that irradiates the irradiated object with the charged particle beam, and a beam transport line 41 that transports the charged particle beam emitted from the accelerator 3 to the irradiation unit 2. And an energy adjusting unit 20 provided between the accelerator 3 and the irradiation unit 2 on the beam transport line 41. The irradiation unit 2 is attached to a rotating gantry 5 provided so as to surround the treatment table 4. The irradiation unit 2 can be rotated around the treatment table 4 by a rotating gantry 5.

  FIG. 2 is a schematic configuration diagram in the vicinity of the irradiation unit of the charged particle beam therapy system of FIG. In the following description, the terms “X direction”, “Y direction”, and “Z direction” will be used. The “Z direction” is a direction in which the base axis AX of the charged particle beam B extends, and is a depth direction of irradiation of the charged particle beam B. The “base axis AX” is an irradiation axis of the charged particle beam B when it is not deflected by a scanning electromagnet 6 described later. FIG. 2 shows a state in which the charged particle beam B is irradiated along the base axis AX. The “X direction” is one direction in a plane orthogonal to the Z direction. The “Y direction” is a direction orthogonal to the X direction in a plane orthogonal to the Z direction.

  First, a schematic configuration of the charged particle beam therapy apparatus 1 according to the present embodiment will be described with reference to FIG. In the following description, a case where the charged particle beam therapy system 1 is an irradiation apparatus related to the scanning method will be described. The scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, or the like may be employed. Furthermore, the irradiation method of the charged particle beam therapy system 1 is not limited to the scanning method, and any irradiation method such as a wobbler method, a broad beam method, and an active substance irradiation method may be adopted. As shown in FIG. 2, the charged particle beam therapy system 1 includes an accelerator 3, an irradiation unit 2, a beam transport line 41, and a control unit 7.

  The accelerator 3 is a device that accelerates charged particles and emits a charged particle beam B having a preset energy. Examples of the accelerator 3 include a cyclotron, a synchrotron, a synchrocyclotron, a linac, and the like. In addition, when employ | adopting the cyclotron which radiate | emits the charged particle beam B with single energy as the accelerator 3, the effect of employ | adopting the energy adjustment part 20 becomes more remarkable. The accelerator 3 is connected to the control unit 7 and the supplied current is controlled. The charged particle beam B generated by the accelerator 3 is transported to the irradiation nozzle 9 by the beam transport line 41. The beam transport line 41 connects the accelerator 3, the energy adjustment unit 20, and the irradiation unit 2, and transports the charged particle beam emitted from the accelerator 3 and energy-adjusted by the energy adjustment unit 20 to the irradiation unit 2. To do.

  The charged particle beam treatment apparatus 1 further includes a beam chopper 16 that is disposed in the accelerator 3 and that blocks the charged particle beam B emitted from the ion source. In the operating state (ON) of the beam chopper 16, the charged particle beam B emitted from the ion source is blocked and is not emitted from the accelerator 3. When the beam chopper 16 is stopped (OFF), the charged particle beam B emitted from the ion source is emitted from the accelerator 3 without being blocked. The operation state and the stop state of the beam chopper 16 are switched by a beam chopper switch (not shown). A means other than a beam chopper may be used as a means for switching between irradiation and non-irradiation of charged particle beams. For example, a shutter may be provided in the beam transport line, and the charged particle beam may be blocked by the shutter. Alternatively, the charged particle beam may be emitted from the accelerator 3 only when the charged particle beam is irradiated using a deflector (electromagnet) provided in the accelerator 3.

  The irradiation unit 2 irradiates the tumor (irradiated body) 14 in the body of the patient 15 with the charged particle beam B. The charged particle beam B is obtained by accelerating charged particles at high speed, and examples thereof include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. Specifically, the irradiation unit 2 is an apparatus that irradiates the tumor 14 with a charged particle beam B emitted from an accelerator 3 that accelerates charged particles generated by an ion source (not shown) and transported by a beam transport line 41. . The irradiation unit 2 includes a scanning electromagnet (scanning unit) 6, a quadrupole electromagnet 8, a profile monitor 11, a dose monitor 12, flatness monitors 13 a and 13 b, and a degrader 30. The scanning electromagnet 6, the monitors 11, 12, 13 a, 13 b, the quadrupole electromagnet 8, and the degrader 30 are accommodated in the irradiation nozzle 9.

  The scanning electromagnet 6 includes an X-direction scanning electromagnet 6a and a Y-direction scanning electromagnet 6b. The X-direction scanning electromagnet 6a and the Y-direction scanning electromagnet 6b are each composed of a pair of electromagnets, change the magnetic field between the pair of electromagnets according to the current supplied from the control unit 7, and pass between the electromagnets. Scan line B. The X direction scanning electromagnet 6a scans the charged particle beam B in the X direction, and the Y direction scanning electromagnet 6b scans the charged particle beam B in the Y direction. These scanning electromagnets 6 are arranged in this order on the base axis AX and downstream of the accelerator 3 from the charged particle beam B.

  The quadrupole electromagnet 8 includes an X-direction quadrupole electromagnet 8a and a Y-direction quadrupole electromagnet 8b. The X-direction quadrupole electromagnet 8 a and the Y-direction quadrupole electromagnet 8 b converge and focus the charged particle beam B according to the current supplied from the control unit 7. The X direction quadrupole electromagnet 8a converges the charged particle beam B in the X direction, and the Y direction quadrupole electromagnet 8b converges the charged particle beam B in the Y direction. The beam size of the charged particle beam B can be changed by changing the current supplied to the quadrupole electromagnet 8 to change the aperture amount (convergence amount). The quadrupole electromagnet 8 is disposed in this order on the base axis AX and between the accelerator 3 and the scanning electromagnet 6. The beam size is the size of the charged particle beam B on the XY plane. The beam shape is the shape of the charged particle beam B on the XY plane.

  The profile monitor 11 detects the beam shape and position of the charged particle beam B for alignment at the time of initial setting. The profile monitor 11 is disposed on the base axis AX and between the quadrupole electromagnet 8 and the scanning electromagnet 6. The dose monitor 12 detects the intensity of the charged particle beam B. The dose monitor 12 is disposed downstream of the scanning electromagnet 6 on the base axis AX. The flatness monitors 13a and 13b detect and monitor the beam shape and position of the charged particle beam B. The flatness monitors 13 a and 13 b are arranged on the base axis AX and downstream of the charged particle beam B from the dose monitor 12. Each monitor 11, 12, 13 a, 13 b outputs the detected detection result to the control unit 7.

  The degrader 30 finely adjusts the energy of the charged particle beam B by reducing the energy of the charged particle beam B passing therethrough. In the present embodiment, the degrader 30 is provided at the distal end portion 9 a of the irradiation nozzle 9. The tip 9a of the irradiation nozzle 9 is the end on the downstream side of the charged particle beam B. The degrader 30 in the irradiation nozzle 9 can be omitted.

  The control part 7 is comprised by CPU, ROM, RAM, etc., for example. The control unit 7 controls the accelerator 3, the scanning electromagnet 6, and the quadrupole electromagnet 8 based on the detection results output from the monitors 11, 12, 13a, and 13b. Moreover, in this embodiment, the control part 7 feeds back the detection result of each monitor 11, 12, 13a, 13b, and controls the quadrupole electromagnet 8 so that the beam size of the charged particle beam B becomes constant. .

  The control unit 7 of the charged particle beam therapy apparatus 1 is connected to a treatment planning apparatus 100 that performs a treatment plan for charged particle beam therapy. The treatment planning apparatus 100 measures the tumor 14 of the patient 15 by CT or the like before the treatment, and plans a dose distribution (a dose distribution of a charged particle beam to be irradiated) at each position of the tumor 14. Specifically, the treatment planning apparatus 100 creates a treatment plan map for the tumor 14. The treatment planning apparatus 100 transmits the created treatment plan map to the control unit 7.

  When charged particle beam irradiation is performed by the scanning method, the tumor 14 is virtually divided into a plurality of layers in the Z direction, and the charged particle beam is scanned and irradiated in one layer. Then, after the irradiation of the charged particle beam in the one layer is completed, the charged particle beam is irradiated in the next adjacent layer.

  When the charged particle beam therapy apparatus 1 shown in FIG. 2 irradiates the charged particle beam B by the scanning method, the quadrupole electromagnet 8 is turned on (ON) so that the passing charged particle beam B converges.

  Subsequently, a charged particle beam B is emitted from the accelerator 3. Further, the range of the charged particle beam B is adjusted by adjusting the charged particle beam B emitted from the accelerator 3 by the energy adjusting unit 20. The emitted charged particle beam B is scanned under the control of the scanning electromagnet 6. Thereby, the charged particle beam B is irradiated while being scanned within the irradiation range in one layer set in the Z direction with respect to the tumor 14. When the irradiation of one layer is completed, the charged particle beam B is irradiated to the next layer.

  The charged particle beam irradiation image of the scanning electromagnet 6 according to control of the control part 7 is demonstrated with reference to Fig.3 (a) and (b). 3A shows an irradiation object virtually sliced into a plurality of layers in the depth direction, and FIG. 3B shows a scanning image of a charged particle beam in one layer viewed from the depth direction. , Respectively.

As shown in FIG. 3A, the irradiated object is virtually sliced into a plurality of layers in the irradiation depth direction, and in this example, from the deep layer (the range of the charged particle beam B is long). In order, the layer is virtually sliced into a layer L ₁ , a layer L ₂ ,... A layer L _n−1 , a layer L _n , a layer L _{n + 1} , a layer L _N−1 , a layer L _N, and an N layer. Further, as shown in FIG. 3 (b), the charged particle beam B is irradiated to a plurality of irradiation spots of the layer L _n while drawing the beam trajectory TL. That is, the irradiation nozzle 9 controlled by the control unit 7 moves on the beam trajectory TL.

  Next, with reference to FIG. 4, the structure of the energy adjustment part 20 with which the charged particle beam therapy apparatus 1 which concerns on this embodiment is provided is demonstrated. The energy adjustment unit 20 includes a first attenuation unit 21, a collimator 22, and an electric field generation unit 23 from the upstream accelerator 3 side.

  The first attenuation unit 21 is a member that reduces the energy of the charged particle beam B by causing the charged particle beam B emitted from the accelerator 3 to enter. The first attenuation unit 21 is a member that can perform rough adjustment of the range of the charged particle beam B on the upstream side of the electric field generation unit 23.

  The collimator 22 is a member that blocks an unnecessary portion that has spread due to diffusion in the charged particle beam B that has passed through the first attenuation unit 21 and adjusts the charged particle beam B to have a certain shape and beam size. The collimator 22 has a through-hole, and by passing the through-hole through the charged particle beam B, the diffused portion of the charged particle beam B is blocked at the edge of the through-hole, and a necessary portion is removed. The light can be emitted to the electric field generation unit 23 side.

  The electric field generation unit 23 causes the charged particle beam B that has passed through the first attenuation unit 21 to enter, and continuously generates a high-frequency electric field, thereby converging the charged particle beam B. Further, the electric field generating unit 23 can accelerate or decelerate charged particles constituting the charged particle beam B. The electric field generator 23 can converge the charged particle beam B in either the acceleration mode or the deceleration mode. When the beam size of the charged particle beam B is reduced using an electromagnet, the charged particle beam B is reduced only in one axial direction as shown in FIGS. 7B and 7C when viewed from the front. . On the other hand, when the beam size is reduced by converging the charged particle beam B by the electric field generation unit 23, the entire beam can be reduced as shown in FIG. Further, the electric field generation unit 23 can adjust the range of the charged particle beam B by adjusting the energy of the charged particle beam B. That is, the electric field generation unit 23 adjusts the maximum reachable depth of the charged particle beam B in the patient 15.

  As the electric field generation unit 23 as described above, a linear accelerator (linac) capable of generating a convergence force can be used. Examples of linear accelerators that can generate a convergence force include RFQ (Radio Frequency Quadrupole), DTL (Drift Tube Linear accelerator), and the like.

  Here, a configuration when an RFQ type linear accelerator is employed as the electric field generation unit 23 will be described. As shown in FIG. 4, the electric field generating unit 23 configured as an RFQ type linear accelerator includes a conductive outer cylinder part 24 closed at both ends by plates, and a beam along the central axis of the conductive outer cylinder part 24. An axis is defined. A beam passage hole 24a is provided in the center of the plates at both ends. Further, in the conductive outer cylinder portion 24, four conductive wing portions 25 are arranged at an angular interval of 90 ° so as to surround the beam axis.

  On the beam axis side of each wing portion 25, a waveform is formed along the beam axis. As shown in FIG. 4, this waveform has the same phase at the wings at positions facing each other, that is, at a position 180 degrees apart. On the other hand, the waveforms in the wings adjacent to each other have a phase difference of 180 °. When high-frequency power having a predetermined frequency is introduced into the cavity constituted by the conductive outer cylinder portion 24 and the wing portion 25 described above, a high-frequency voltage having the same phase is applied to the two wing portions 25 facing each other. High-frequency voltages having opposite phases are applied to the wing portion 25, and a quadrupole accelerated focusing electric field is formed along the beam axis. In such an electric field generation part 23, the wing | blade part 25 which forms an electric field has a waveform shape. Therefore, the electric field formed by the corrugated wing portion 25 includes a component in which a converging force toward the beam axis acts on the particles constituting the charged particle beam B. With respect to the electrodes orthogonal to each other, if a pair of electrodes on the X axis on one side is “crest” in a certain cross section, a pair of electrodes on the other Y axis is “valley”. In a phase where an electric field stands from the valley to the mountain, a converging force acts in the Y-axis direction.

  In addition, a configuration when a DTL linear accelerator is employed as the electric field generation unit 23 will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, the electric field generator 23 has a conductive outer cylinder 36. An electric field is generated inside the conductive outer cylinder portion 36 along the central axis by a high-frequency electric power. The direction of this electric field is reversed every half cycle, as shown in FIGS. 5 (a) and 5 (b). When the electric field is directed in the traveling direction (the state shown in FIG. 5A), the charged particles P constituting the charged particle beam B are accelerated. On the other hand, when the electric field is directed to the opposite side of the traveling direction (the state shown in FIG. 5B), the charged particles P are decelerated. Accordingly, the position and length of the tube 37 are set so that the charged particles P are arranged in the tube 37 when the electric field is directed to the opposite side of the traveling direction. However, as the acceleration of the charged particles P proceeds, the length of the tube 37 and the size of the gap increase, so that the structure of the electric field generating unit 23 is switched to the structure of a coupled cavity accelerator as shown in FIG.

  As shown in FIG. 6, similarly to FIGS. 1 and 3, a conductive outer cylinder portion (not shown) whose both ends are closed by plates is provided, and a beam passage hole is provided in the center portion of the plates at both ends. Yes. A pair of conductive metal plates (not shown) protrude in the beam axis direction from positions facing each other in the conductive outer cylinder, and stems 32 are alternately attached to the conductive metal plates. ing. Furthermore, these stems 32 are electrically connected to electrodes (drift tubes) 31A to 31C, respectively. When high-frequency power having a predetermined frequency is introduced into a cavity constituted by the conductive outer cylinder portion, the electrodes 31A to 31C, the conductive metal plate, and the stem 32, FIGS. 6 (a), 6 (c), ( As shown in e), a high frequency voltage is applied between adjacent electrodes, and the ion beam on the beam axis is sequentially accelerated.

  In the electric field generation unit 23 as described above, as shown in FIGS. 6A and 6B, when the charged particle P is disposed at the end portion in the traveling direction of the electrode 31A, the electrode 31A and the electrode When the polarity of 31C is positive and the polarity of electrode 31B is negative, an electric field that curves so as to protrude toward the beam axis from electrode 31A and electrode 31C toward electrode 31B is formed. Therefore, a converging force toward the beam axis acts on the charged particles P. Next, as shown in FIGS. 6B and 6C, when the charged particles P are arranged in the space between the electrodes 31A and 31B, the polarities of the electrodes 31A to 31C are 0. Become. In this case, no force acts on the charged particles P. Next, as shown in FIGS. 6 (e) and 6 (f), when the charged particles P are arranged at the end opposite to the traveling direction of the electrode 31B, the polarities of the electrodes 31A and 31C are changed. When the polarity of the electrode 31B is negative and the polarity is positive, an electric field that is curved so as to protrude from the electrode 31B toward the electrode 31A and the electrode 31C toward the beam axis is formed. Therefore, a converging force toward the beam axis acts on the charged particles P.

  Next, operations and effects of the charged particle beam therapy system 1 according to this embodiment will be described.

  The charged particle beam therapy system 1 according to this embodiment includes a first attenuation unit 21 that reduces the energy of the charged particle beam B by causing the charged particle beam B emitted from the accelerator 3 to enter, An electric field generation unit 23 that converges the charged particle beam B by causing the charged particle beam B that has passed through the attenuation unit 21 to enter and continuously generating a high-frequency electric field is provided. Therefore, once the charged particle beam B that has passed through the first attenuation unit 21 passes through the electric field generation unit 23, the beam size is converged. Therefore, it is possible to suppress an increase in the beam size of the charged particle beam while suppressing a decrease in dose due to a part of the irradiation unit 2 being blocked by a collimator or the like.

  Since the beam size is likely to increase in the low energy region, it is possible to recover the emittance in the low energy region by employing the charged particle beam therapy system 1 according to the present embodiment. In addition, since the beam size of the charged particle beam B can be converged while suppressing a decrease in dose, high-intensity charged particle beam therapy can be performed.

  The present invention is not limited to the embodiment described above.

  For example, you may employ | adopt the energy adjustment part 120 as shown in FIG. The energy adjustment unit 120 includes a second attenuation unit 124 between the electric field generation unit 23 and the irradiation unit 2 (here, a position adjacent to the electric field generation unit 23 on the downstream side). Since the electric field generation unit 23 here can enter only the charged particle beam B having a constant energy, the first attenuation unit 121 reduces the energy of the charged particle beam B by a single energy reduction amount. On the other hand, the second attenuation unit 124 can adjust the amount of energy decrease in a plurality of stages. That is, the energy of the charged particle beam can be reduced with an energy reduction amount that can be adjusted in multiple steps as compared with the first attenuation unit 121. Since the incident surface of the second attenuation unit 124 is a surface inclined with respect to the charged particle beam B, the amount of energy decrease can be continuously adjusted. With such a configuration, the charged particle beam B is attenuated to a certain level of energy by the first attenuation unit 121 and then converged by the electric field generation unit 23 to recover the beam quality, and further, the second attenuation unit. The energy can be finely adjusted at 124.

  In addition, when the electric field generating unit 223 can enter the charged particle beam B related to a plurality of energies, an energy adjusting unit 220 as shown in FIG. 9 may be employed. In this case, the first attenuation unit 221 provided on the upstream side of the electric field generation unit 223 can reduce the energy of the charged particle beam B with an energy reduction amount that can be adjusted in a plurality of stages (here, three stages). it can. Since the incident surface of the second attenuation unit 224 is a surface inclined with respect to the charged particle beam B, the amount of energy reduction can be adjusted continuously. Therefore, the second attenuation unit 224 can reduce the energy of the charged particle beam with an energy reduction amount that can be adjusted in multiple steps as compared with the first attenuation unit 221. With such a configuration, the charged particle beam B is attenuated by the first attenuation unit 221 to an energy that the electric field generation unit 223 can accelerate and decelerate, and then converged by the electric field generation unit 223, whereby the beam quality is recovered. Further, the second attenuation unit 224 can finely adjust the energy. As described above, the energy of the charged particle beam B can be finely adjusted by the second attenuation unit 224 with multistage energy reduction.

  Moreover, the structure of the irradiation part 2 is not limited to what is shown in FIG. 2, It can change suitably.

  DESCRIPTION OF SYMBOLS 1 ... Charged particle beam therapy apparatus, 2 ... Irradiation part, 3 ... Accelerator, 14 ... Tumor (irradiated body), 21, 121, 221 ... 1st attenuation part, 23, 223 ... Electric field generation part, 41 ... Beam transport Lines 124, 224 ... second attenuation part.

Claims (3)

An accelerator for accelerating charged particles and emitting a charged particle beam having a preset energy;
A first attenuation unit that reduces the energy of the charged particle beam by making the charged particle beam emitted from the accelerator incident;
An electric field generating unit that converges the charged particle beam by causing the charged particle beam that has passed through the first attenuation unit to enter and continuously generating a high-frequency electric field;
A charged particle beam therapy apparatus comprising: an irradiation unit that irradiates an irradiated body with the charged particle beam emitted from the electric field generation unit.   A second attenuating unit that is provided between the electric field generating unit and the irradiating unit and reduces the energy of the charged particle beam by allowing the charged particle beam emitted from the electric field generating unit to enter; The charged particle beam therapy apparatus according to claim 1. The first attenuation unit reduces the energy of the charged particle beam by a single energy decrease amount or an energy decrease amount that can be adjusted in a plurality of stages.
The charged particle beam therapy apparatus according to claim 2, wherein the second attenuation unit reduces the energy of the charged particle beam by an energy decrease amount that can be adjusted in multiple steps as compared with the first attenuation unit.

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