Charged particle beam irradiation device

Abstract

An object of the present invention is to provide a charged particle beam irradiation apparatus capable of shortening the irradiation time of a charged particle beam. A charged particle beam irradiation apparatus (1) that irradiates a charged particle beam (B), the charged particle beam irradiation apparatus (1) includes: an accelerator (2) that accelerates charged particles to generate a charged particle beam (B); an irradiation unit (3) having a gantry (5) capable of rotating around a rotation axis and irradiating the charged particle beam (B) generated by the accelerator (2); and a transmission unit (4) having an energy attenuator (43) provided outside the irradiation unit (3) and reducing the energy of the charged particle beam (B) generated by the accelerator (2), and transmitting the charged particle beam (B) generated by the accelerator (2) to the irradiation unit (3), the transmission unit (4) transmitting the charged particle beam (B) having the energy distribution of the charged particle beam (B) whose energy is reduced by the energy attenuator (43) to the irradiation unit (3).

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2020-060893 filed on March 30, 2020. The entire content of the Japanese application is incorporated herein by reference.

[0002] The present invention relates to a charged particle beam irradiation device. Background Art

[0003] As a charged particle beam irradiation device, for example, a charged particle beam irradiation device shown in Patent Document 1 is known. The charged particle beam irradiation device includes: an accelerator that accelerates charged particles to generate a charged particle beam; an irradiation unit that has a rotating unit that can rotate around a rotation axis and irradiates the charged particle beam generated by the accelerator; and a transport unit that transports the charged particle beam from the accelerator to the irradiation unit. The charged particle beam irradiation device shown in Patent Document 1 Figure 4 has an energy selection unit (ESS: Energy Selection System) for selecting the energy of the charged particle beam above the irradiation unit. The selection unit of Patent Document 1 has: an attenuator that reduces the energy of the charged particle beam; a pair of deflection electromagnets and slits for restricting the momentum width of the charged particle beam; and a collimator.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-163229

[0005] Here, in the structure shown in Patent Document 1 Figure 4 the Bragg peak of the charged particle beam becomes narrow due to the slit. Therefore, the number of charged particle beam energies required to form the Bragg peak increases, and the number of times of switching the energy of the charged particle beam increases, resulting in a problem that the irradiation time of the charged particle beam becomes long. Summary of the Invention

[0006] Therefore, an object of the present invention is to provide a charged particle beam irradiation device capable of shortening the irradiation time of the charged particle beam.

[0007] The charged particle beam irradiation device according to the present invention is a charged particle beam that irradiates a charged particle beam, and includes: an accelerator that accelerates charged particles to generate a charged particle beam; an irradiation unit that irradiates the charged particle beam generated by the accelerator; and a transport unit that has an attenuator provided outside the irradiation unit and reduces the energy of the charged particle beam generated by the accelerator, and transports the charged particle beam generated by the accelerator to the irradiation unit, and the transport unit transports the charged particle beam having the energy distribution of the charged particle beam whose energy has been reduced by the attenuator to the irradiation unit.

[0008] In the charged particle beam irradiation apparatus according to the present invention, an attenuator that reduces the energy of the charged particle beam is disposed on a transport section outside the irradiation section. The transport section transports the charged particle beam having an energy distribution of the charged particle beam whose energy has been reduced by the attenuator to the irradiation section. Thereby, the transport section can transport the charged particle beam from the attenuator to the irradiation section without providing a selection section that selects a specific range of energy from the energy of the charged particle beam. Therefore, compared with the case where a selection section is provided, the Bragg peak of the charged particle beam becomes broader, the number of charged particle beam energies required for forming the Bragg peak is reduced, and the number of times of switching the energy of the charged particle beam is reduced. Based on the above, the irradiation time of the charged particle beam can be shortened.

[0009] In the charged particle beam irradiation apparatus according to the present invention, the transport section may have a collimator that is provided between the attenuator and the irradiation section and adjusts the shape, size, and divergence of the charged particle beam. In this case, the collimator can adjust the shape and divergence of the charged particle beam that has passed through the attenuator, and can transport the charged particle beam from the attenuator to the irradiation section while maintaining the energy distribution of the charged particle beam.

[0010] In the charged particle beam irradiation apparatus according to the present invention, the transport section may have an aperture through which the charged particle beam whose energy has been reduced by the attenuator can pass. In this case, the transport section can transport the charged particle beam from the attenuator to the irradiation section while maintaining the energy distribution of the charged particle beam without selecting a specific range of energy for the charged particle beam.

[0011] In the charged particle beam irradiation apparatus according to the present invention, the attenuator may reduce the energy of the charged particle beam generated by the accelerator so that the momentum spread of the charged particle beam is less than 6%. The more the attenuator reduces the energy of the charged particle beam, the more significantly the energy distribution of the charged particle beam spreads. The attenuator suppresses the spread of the energy distribution of the charged particle beam by making the momentum spread of the charged particle beam less than 6%. At this time, the transport section can transport the charged particle beam from the attenuator to the irradiation section while maintaining the energy distribution of the charged particle beam without selecting a specific range of energy for the charged particle beam.

[0012] In the charged particle beam irradiation apparatus according to the present invention, the irradiation section may further have a scanning electromagnet that scans the charged particle beam, a channel through which the charged particle beam scanned by the scanning electromagnet passes, and a monitor that detects the charged particle beam that has passed through the channel, and the inside of the channel may be exposed to the atmosphere. In this case, the beam of the charged particle beam passing through the channel from the scanning electromagnet toward the monitor is scattered by the atmosphere (air) inside the channel. Thereby, it is possible to suppress the symmetry of the cross-sectional shape of the beam of the charged particle beam from being broken. Therefore, the irradiation section can irradiate the beam of the charged particle beam to an appropriate range.

[0013] In the charged particle beam irradiation apparatus according to the present invention, the transport section may include a sextupole magnet or a deflection magnet with a sextupole component that bunches the charged particle beam to adjust the momentum spread of the charged particle beam. In this case, the transport section can shape the charged particle beam according to the energy distribution of the charged particle beam passing therethrough, and can appropriately transport the charged particle beam from the accelerator to the irradiation section.

[0014] Advantages of the Invention

[0015] According to the present invention, there is provided a charged particle beam irradiation apparatus capable of shortening the irradiation time of the charged particle beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a top view layout diagram of a charged particle beam irradiation apparatus according to an embodiment of the present invention.

[0017] Figure 2 is Figure 1 a schematic structural diagram near the irradiation section of the charged particle beam irradiation apparatus.

[0018] Figure 3 is a diagram showing the layers set for a tumor.

[0019] Figure 4 is a schematic diagram for explaining the central axis of the irradiation section.

[0020] Figure 5 is a graph showing the energy distribution of the charged particle beam generated in a charged particle beam irradiation apparatus according to an embodiment of the present invention.

[0021] Figure 6 In (a), it is a schematic structural diagram of a convex deflection magnet with a sextupole component in the transport section of a charged particle beam irradiation apparatus according to an embodiment of the present invention. Figure 6 In (b), it is a schematic structural diagram of a concave deflection magnet with a sextupole component in the transport section of a charged particle beam irradiation apparatus according to an embodiment of the present invention. Figure 6 In (c), it is a schematic structural diagram of a deflection magnet with a sextupole component having an auxiliary coil in the transport section of a charged particle beam irradiation apparatus according to an embodiment of the present invention.

[0022] Figure 7 is an enlarged view showing the structure of the selection section provided in the transport section of the charged particle beam irradiation apparatus according to Comparative Example 1.

[0023] Figure 8 In (a), it is a graph showing the Bragg peak of the charged particle beam emitted from a charged particle beam irradiation apparatus according to an embodiment of the present invention. Figure 8The chart of (b) shows the Bragg peak of the charged particle beam emitted from the charged particle beam irradiation device involved in Comparative Example 1.

[0024] In the figure: 1 - charged particle beam irradiation device, 2 - accelerator, 3 - irradiation unit, 4 - transmission unit, 5 - gantry (an example of a rotating unit), 8 - deflection electromagnet (an example of a sextupole magnet or a deflection magnet with a sextupole component), 10 - scanning electromagnet, 11 - channel, 12 - dose monitor (an example of a monitor), 13a, 13b - position monitor (an example of a monitor), 43 - energy attenuator (an example of an attenuator), 44 - collimator, B, B1, B2, B3, B4, B5 - charged particle beams. Detailed implementation manners

[0025] Hereinafter, preferred implementation manners of the charged particle beam irradiation device according to the present invention will be described with reference to the accompanying drawings. In addition, in the description of the drawings, the same reference numerals are assigned to the same components, and repeated descriptions are omitted. In the present implementation manner, the case where the charged particle beam irradiation device is a charged particle beam therapy device will be described. The charged particle beam therapy device is, for example, applicable to cancer treatment and is a device that irradiates a charged particle beam such as a proton beam to a tumor (irradiation target) in a patient's body.

[0026] The schematic structure of the charged particle beam irradiation device of the present implementation manner will be described. Figure 1 is a layout view when observing the charged particle beam irradiation device according to an implementation manner of the present invention from above. As Figure 1 shown, the charged particle beam irradiation device 1 includes: an accelerator 2 that generates a charged particle beam; a rotatable irradiation unit 3 that irradiates a charged particle beam to a patient 15 on a treatment table 16 from an arbitrary direction; and a transmission unit 4 that transmits the charged particle beam generated by the accelerator 2 to the irradiation unit 3. Moreover, each device of the charged particle beam irradiation device 1 is provided, for example, in a room of a single-story building 6.

[0027] The irradiation unit 3 is mounted on a gantry 5 (an example of a rotating unit) provided so as to surround the treatment table 16. The irradiation unit 3 can be rotated around the treatment table 16 by the gantry 5. The gantry 5 can rotate around a rotation axis. The transmission unit 4 has: an external path 4A that transmits the charged particle beam from the accelerator 2 to the gantry 5; and an internal path 4B that transmits the charged particle beam to the irradiation unit 3 within the gantry 5. The external path 4A enters the gantry 5 from the rear end side of the gantry 5. Moreover, in the internal path 4B, after changing the orbit of the charged particle beam to the outer peripheral side by the deflection electromagnet 7, the orbit of the charged particle beam is greatly bent by the deflection electromagnet 8 (an example of a sextupole magnet or a deflection magnet with a sextupole component) and enters the irradiation unit 3 from the outer peripheral side.

[0028] Figure 2 isFigure 1 Schematic structural diagram near the irradiation unit of the charged particle beam irradiation device. In the following description, the terms "X-axis direction", "Y-axis direction", and "Z-axis direction" are used. The "X-axis direction" is the direction along the base axis AX of the irradiation unit 3 and is the irradiation depth direction of the charged particle beam B. Details of the "base axis AX" will be described later. In Figure 2 , the state of irradiating the charged particle beam B along the base axis AX is shown. The "Y-axis direction" is one direction in the plane orthogonal to the X-axis direction. The "Z-axis direction" is the direction orthogonal to the Y-axis direction in the plane orthogonal to the X-axis direction.

[0029] Reference Figure 1 And Figure 2 The detailed structure of the charged particle beam irradiation device 1 according to the present embodiment will be described. The charged particle beam irradiation device 1 is an irradiation device related to the scanning method. In addition, the scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, etc. can be adopted. The charged particle beam irradiation device 1 includes, in addition to the accelerator 2, the irradiation unit 3, and the transfer unit 4, a control unit 80 and a treatment planning device 90.

[0030] The accelerator 2 is a device that accelerates charged particles to generate a charged particle beam B with a preset energy. The charged particle beam B generated by the accelerator 2 is guided to the irradiation unit 3 through the orbit formed by the transfer unit 4. As the accelerator 2, for example, a cyclotron, a synchrocyclotron, a linear accelerator (Linac), etc. can be cited. As the accelerator 2 in the present embodiment, a cyclotron that emits a charged particle beam B with a preset energy is adopted. The accelerator 2 includes: a vacuum container 21 that accelerates ions (charged particles) while rotating on an acceleration plane inside, and an ion source (not shown) that supplies ions into the vacuum container 21. The vacuum container 21 is connected to the external path 4A of the transfer unit 4. The charged particle beam B rotating inside the vacuum container 21 is output from the rotation orbit by the deflector 22 and supplied to the external path 4A of the transfer unit 4. In addition, the acceleration plane of the accelerator 2 spreads in the horizontal direction (X-axis direction and Y-axis direction). The center of the acceleration plane is set as the center point CP2 (reference Figure 1 ). The center line extending in the Z-axis direction of the vacuum container 21 passes through the center point CP2. The accelerator 2 is connected to the control unit 80 and controls the supplied current.

[0031] As Figure 1As shown, the transport section 4 has an energy attenuator 43 (an example of an attenuator) provided outside the irradiation section 3 to reduce the energy of the charged particle beam B generated by the accelerator 2, and transports the charged particle beam B generated by the accelerator 2 to the irradiation section 3. Further, the transport section 4 has a collimator 44 provided between the energy attenuator 43 and the irradiation section 3 to adjust the shape, size, and divergence of the charged particle beam B. The external path 4A of the transport section 4 successively includes a quadrupole electromagnet 41, a steering electromagnet 42, an energy attenuator 43, a collimator 44, a quadrupole electromagnet 41, and a beam stopper 45 from the upstream side. The quadrupole electromagnet 41 is an electromagnet for focusing the charged particle beam B to trim the shape of the charged particle beam. The steering electromagnet 42 is an electromagnet for correcting the orbit of the charged particle beam. The energy attenuator 43 is a mechanism for reducing the energy of the charged particle beam as a whole to adjust the range. The collimator 44 shapes the shape of the charged particle beam to adjust the size (dimension) of the charged particle beam to adjust the divergence of the charged particle beam. The beam stopper 45 is a mechanism for switching between the emission and stop of the charged particle beam. As described above, the internal path 4B of the transport section 4 has deflection electromagnets 7 and 8.

[0032] The irradiation section 3 irradiates the charged particle beam B generated by the accelerator 2. Specifically, as Figure 2 shown, the irradiation section 3 irradiates the tumor (the irradiated object) 14 in the patient 15 with the charged particle beam B. The charged particle beam B is formed by accelerating charged particles to a high speed, and examples thereof include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. Specifically, the irradiation section 3 is a device that irradiates the tumor 14 with the charged particle beam B emitted from the accelerator 2 that accelerates charged particles generated by an ion source (not shown) and transported by the transport section 4. The irradiation section 3 includes a scanning electromagnet 10, a channel 11, a dose monitor 12 (an example of a monitor), position monitors 13a and 13b (an example of a monitor), a collimator 17, and a snort degrader 30. The scanning electromagnet 10, the channel 11, each of the monitors 12, 13a, and 13b, the collimator 17, and the snort degrader 30 are accommodated in an irradiation nozzle 9 as a housing. Thus, the irradiation section 3 is constituted by housing each main component in the irradiation nozzle 9. Further, in addition to the above-described components, a hexapole magnet or a deflection magnet with a hexapole component and a profile monitor may be provided upstream of the scanning electromagnet 10. Also, the dose monitor 12 and the position monitors 13a and 13b may be omitted.

[0033] The scanning electromagnet 10 includes a Y-axis direction scanning electromagnet 10a and a Z-axis direction scanning electromagnet 10b. The Y-axis direction scanning electromagnet 10a and the Z-axis direction scanning electromagnet 10b are each composed of a pair of electromagnets. The magnetic field between the pair of electromagnets changes corresponding to the current supplied from the control unit 80, and scans the charged particle beam B passing between the electromagnets. Through the scanning electromagnet 10, the Y-axis direction scanning electromagnet 10a scans the charged particle beam B in the Y-axis direction, and the Z-axis direction scanning electromagnet 10b scans the charged particle beam B in the Z-axis direction. These scanning electromagnets 10 are sequentially arranged on the base axis AX and at a position downstream of the accelerator 2 with respect to the charged particle beam B. In addition, the scanning electromagnet 10 scans the charged particle beam B in such a manner that the charged particle beam B is irradiated on a scanning path pre-planned in the treatment planning device 90.

[0034] The channel 11 is arranged on the base axis AX and on the downstream side with respect to the scanning electromagnet 10. The channel 11 guides the charged particle beam B scanned by the scanning electromagnet 10 to the dose monitor 12 arranged downstream with respect to the channel 11. The channel 11 is, for example, in the shape of a frustum of a cone that spreads from the upstream to the downstream of the base axis AX. The channel 11 penetrates along the base axis AX. The inside of the channel 11 is exposed to the atmosphere. That is, the channel 11 contains the atmosphere (air) inside it. The atmosphere (air) contains, for example, nitrogen and oxygen. The inside of the channel 11 is, for example, exposed to the atmosphere. At this time, the entire inside of the irradiation nozzle 9 may be exposed to the atmosphere, or it may be configured such that only the inside of the channel 11 is exposed to the atmosphere.

[0035] The dose monitor 12 is arranged on the base axis AX and on the downstream side with respect to the channel 11. The position monitors 13a and 13b detect and monitor the beam shape and position of the charged particle beam B. The position monitors 13a and 13b are arranged on the base axis AX and at a position downstream of the dose monitor 12 with respect to the charged particle beam B. Each of the monitors 12, 13a, and 13b outputs the detected detection result to the control unit 80.

[0036] The nasal attenuator 30 reduces the energy of the passing charged particle beam B to displace the range of the charged particle beam B. In the present embodiment, the nasal attenuator 30 is provided at the front end portion 9a of the irradiation nozzle 9. In addition, the front end portion 9a of the irradiation nozzle 9 is the end portion on the downstream side of the charged particle beam B. The water equivalent thickness of the nasal attenuator 30 is, for example, about 10 cm.

[0037] The collimator 17 is a component provided at a position at least downstream of the scanning electromagnet 10 with respect to the charged particle beam B, and shields a part of the charged particle beam B and allows a part to pass through. Here, the collimator 17 is provided on the downstream side of the position monitors 13a and 13b. The collimator 17 is connected to a collimator drive unit 18 that moves the collimator 17.

[0038] The control unit 80 is constituted by, for example, a CPU, a ROM, a RAM, etc. The control unit 80 controls the accelerator 2, the scanning electromagnet 10, and the collimator driver 18 based on the detection results output from the monitors 12, 13a, and 13b.

[0039] Furthermore, the control unit 80 of the charged particle beam irradiation device 1 is connected to a treatment planning device 90 that performs a treatment plan for charged particle beam therapy. The treatment planning device 90 measures the tumor 14 of the patient 15 by CT or the like before treatment, and plans the dose distribution (dose distribution of the charged particle beam to be irradiated) at each position of the tumor 14. Specifically, the treatment planning device 90 creates a treatment plan map for the tumor 14. The treatment planning device 90 sends the created treatment plan map to the control unit 80. In the treatment plan map created by the treatment planning device 90, it is planned what kind of scanning path the charged particle beam B draws.

[0040] When the charged particle beam B is irradiated by the scanning method, the tumor 14 is virtually divided into a plurality of layers along the X-axis direction, and the charged particle beam is scanned and irradiated in one layer along the scanning path specified in the treatment plan. Then, after the irradiation of the charged particle beam B in the one layer is completed, the irradiation of the charged particle beam B in the next adjacent layer is performed.

[0041] When irradiation with a charged particle beam based on a scanning method is performed, first, a charged particle beam B is emitted from the accelerator 2. The emitted charged particle beam B is scanned along a scanning path specified in the treatment plan by the control of the scanning electromagnet 10. Thus, the charged particle beam B is scanned within an irradiation range in a layer set along the Z-axis direction while irradiating the tumor 14. When irradiation of one layer is completed, the charged particle beam B is irradiated to the next layer.

[0042] refer to Figure 3 (a) and (b) illustrate charged particle beam irradiation images of the scanning electromagnet 10 corresponding to the control of the control unit 80. Figure 3 This is a diagram showing the layers set for the tumor. Figure 3 (a) shows an irradiated object virtually cut into a plurality of layers in the depth direction, Figure 3 (b) shows a scanning image of a charged particle beam in one layer observed from the depth direction.

[0043] like Figure 3 As shown in (a), the irradiated body is virtually cut into multiple layers in the depth direction of irradiation. In this example, the irradiated body is virtually cut into layers L1, L2, ..., L3 in sequence from the deeper layer (the longer range of the charged particle beam B). n-1 , layer L n , layer L n+1, … layer L N-1 , layer L N N layers such as that. And, as shown in (b) of Figure 3 , when the charged particle beam B is continuously irradiated (line scan or raster scan) while tracing a beam orbit along the scan path TL, it is continuously irradiated along the scan path TL of layer L n . When spot scanning, it is irradiated to a plurality of irradiation points of layer L n . The charged particle beam B is irradiated along a scan path TL1 extending in the Z-axis direction, is slightly displaced in the Y-axis direction along the scan path TL2, and is irradiated along an adjacent scan path TL1. Thus, the charged particle beam B emitted from the irradiation unit 3 controlled by the control unit 80 moves on the scan path TL.

[0044] Figure 4 is a schematic diagram for explaining the base axis of the irradiation unit. Refer to Figure 4 to explain the "base axis AX" of the irradiation unit 3. The base axis AX is a virtual reference line that serves as a reference when the irradiation unit 3 irradiates the charged particle beam B. When making a scan pattern during treatment planning by the treatment planning device 90, treatment planning is also performed with the base axis AX as a reference. For example, when setting the layer shown in (a) of Figure 3 , each layer is set as a plane perpendicular to the base axis AX. And when setting the movement amount in the Y-axis direction and the movement amount in the Z-axis direction, the position of the base axis AX is also used as a reference. As shown in (a) of Figure 4 , the base axis AX is orthogonal to the center line CL of the gantry 5 and passes through the center line CL. The base axis AX passes through the isocenter AC on the center line CL of the gantry 5. As shown in (b) of Figure 4 , when the gantry 5 is rotated to rotate the irradiation unit 3 around the isocenter AC, the base axis AX passes through the isocenter AC on the gantry 5 regardless of the position of the irradiation unit 3. In addition, the XYZ coordinate system is a relative coordinate system that changes according to the orientation of the base axis AX. In Figure 4 , the XYZ coordinate system in the state where the base axis AX extends in the vertical direction is shown. And in the above-mentioned Figure 1 , in order to show the state of the irradiation unit 3, the state where the base axis AX extends in the horizontal direction is shown. Therefore, in Figure 1 , the XYZ coordinate system corresponding to this state is shown.

[0045] Next, refer to Figure 5 to explain the energy distribution of the charged particle beam B irradiated in the charged particle beam irradiation device 1 according to the present embodiment.

[0046] Figure 5 is a graph showing the energy distribution of the charged particle beam generated in the charged particle beam irradiation device according to an embodiment of the present invention.Figure 5 The vertical axis of the chart shown represents the existence probability, and the horizontal axis represents the magnitude of the amount of exercise. The charged particle beam B1 generated in the accelerator 2 in the charged particle beam B is, for example, about 230 MeV. In the energy distribution of the charged particle beam B1, the spread of the amount of exercise is small. That is, the existence probability of the charged particle beam B1 having an amount of exercise deviated from the average value of the amount of exercise of the charged particle beam B1 is significantly smaller than the existence probability of the charged particle beam B1 near the average value of the amount of exercise of the charged particle beam B1. Here, a large spread of the amount of exercise means a small existence probability at the average value of the amount of exercise, and a large existence probability of charged particle beams having various amounts of exercise. In the charged particle beam irradiation apparatus 1 of the present embodiment, the charged particle beam B2 obtained by reducing the energy of the charged particle beam B1 emitted from the accelerator 2 using the energy attenuator 43 has a larger spread of the amount of exercise than the charged particle beam B1 due to the energy reduction. As the spread of the amount of exercise of the charged particle beam B2, for example, the amount of exercise dispersion of the charged particle beam B2 is less than 6%. And the amount of exercise dispersion of the charged particle beam B2 can be 5% or less, or can be 4% or less, 3% or less, or 2% or less. At this time, the charged particle beam B2 is, for example, 110 MeV. In addition, the amount of exercise dispersion is a value of the amount of exercise dispersion corresponding to the energy of the charged particle beam B.

[0047] The transport unit 4 transports the charged particle beam B2 having the energy distribution of the charged particle beam B2 whose energy has been reduced by the energy attenuator 43 to the irradiation unit 3. Specifically, no component for adjusting the energy distribution such as an amount of exercise analysis slit (for example, Figure 7 the amount of exercise analysis slit 157 shown) is provided at any part of the external path 4A and the internal path 4B of the transport unit 4. In addition, the charged particle beam B2 is first affected by the energy distribution in the nasal attenuator 30 in the irradiation unit 3 after passing through the energy attenuator 43. Therefore, no component that affects the energy distribution such as an amount of exercise analysis slit is provided on the path upstream of the nasal attenuator 30 in the irradiation unit 3. In addition, when the transport unit 4 has a multi-stage energy attenuator 43, the transport unit 4 maintains the energy distribution of the charged particle beam B2 that has passed through the energy attenuator 43 arranged on the most downstream side.

[0048] The greater the spread of the momentum of the charged particle beam B (the smaller the energy), the larger the beam diameter of the charged particle beam B passing through the transport section 4. Therefore, the beam diameter of the charged particle beam B2 is larger than that of the charged particle beam B1. The transport section 4 has an aperture through which the charged particle beam B2 whose energy has been reduced by the energy attenuator 43 can pass. The transport section 4 has an aperture through which the charged particle beam B2 can pass at least downstream of the energy attenuator 43. Thus, the transport section 4 can transmit the charged particle beam B2 from the accelerator 2 toward the gantry 5 without selecting the energy of the charged particle beam B2. At this time, the charged particle beam irradiation apparatus 1 can, for example, cause the external path 4A of the transport section 4 to extend linearly from the accelerator 2 toward the gantry 5.

[0049] Since the spread of the momentum of the charged particle beam B2 in the transport section 4 is greater than the spread of the momentum of the charged particle beam B1 and the orbit is slightly different according to the momentum, the cross-sectional shape of the beam of the charged particle beam B2 may become asymmetric. To ensure symmetry in the cross-sectional shape of the beam of the charged particle beam B2, in addition to the collimator 44 that adjusts the shape, size, and divergence of the charged particle beam B2, the transport section 4 also has a sextupole magnet or a deflection magnet with a sextupole component that bunches the charged particle beam B2 to trim the shape of the charged particle beam B2. For example, the deflection electromagnet 8 provided on the internal path 4B of the transport section 4 is a deflection magnet with a sextupole component.

[0050] As Figure 6 shown, various shapes can be adopted for the deflection electromagnet 8 to generate a sextupole component. Figure 6 of (a), Figure 6 of (b), and Figure 6 of (c) are schematic cross-sectional views in a cross-section orthogonal to the path of the charged particle beam B2. Figure 6 Of (a) is a schematic structural diagram of a convex deflection magnet with a sextupole component in the transport section of the charged particle beam irradiation apparatus according to an embodiment of the present invention. As Figure 6 shown in (a), the deflection electromagnet 8 has, for example, a shape that bulges convexly toward the space through which the charged particle beam B2 passes. Figure 6 Of (b) is a schematic structural diagram of a concave deflection magnet with a sextupole component in the transport section of the charged particle beam irradiation apparatus according to an embodiment of the present invention. As Figure 6 shown in (b), the deflection electromagnet 8 can have, for example, a shape that depresses concavely toward the space through which the charged particle beam B2 passes. Figure 6 Of (c) is a schematic structural diagram of a deflection magnet with a sextupole component having an auxiliary coil in the transport section of the charged particle beam irradiation apparatus according to an embodiment of the present invention. As Figure 6As shown in (c) of FIG. 8 , the deflection electromagnet 8 may have an auxiliary coil 8 a in the space through which the charged particle beam B2 passes, for example.

[0051] As described above, by using the deflection electromagnet 8 as a deflection magnet with a sextupole component, different orbits can be corrected according to the amount of motion, thereby ensuring the symmetry of the cross-sectional shape of the charged particle beam B2. The transmission unit 4 can trim the shape of the charged particle beam B2 according to the energy distribution of the charged particle beam B2 passing through, and can appropriately transmit the charged particle beam B2 from the accelerator 2 to the irradiation unit 3. In the transmission unit 4, the deflection electromagnet 7 can also be a sextupole magnet or a deflection magnet with a sextupole component.

[0052] The charged particle beam B2 reaching the irradiation section 3 from the transmission section 4 is scattered by passing through the channel 11 exposed to the atmosphere (including air inside). Compared with a state in which the interior of the channel is in a vacuum state or a state filled with a rare gas and does not contain air, the charged particle beam B2 is further scattered by being exposed to the atmosphere (including air) through the channel 11, and the symmetry of the cross-sectional shape of the beam of the charged particle beam B2 can be ensured.

[0053] Next, the effects of the charged particle beam irradiation device 1 according to the present embodiment will be described in comparison with the charged particle beam irradiation device 100 according to Comparative Example 1. In Comparative Example 1, the functions of devices having the same names but different reference numerals are the same as those of the embodiment.

[0054] Figure 7 This is an enlarged view showing the structure of the selection unit of the transmission unit provided in the charged particle beam irradiation device involved in Comparative Example 1. The selection unit 150 is a mechanism called ESS (Energy Selection System). For example, unlike a structure in which a part of ESS is mounted on the upper side of the irradiation unit 103, all the components of the selection unit 150 are arranged in the space where the accelerator 102 is arranged across the indoor shielding wall. The components of the selection unit 150 are not arranged in the space where the irradiation unit 103 and the rack 105 are arranged.

[0055] The detailed structure of the selection unit 150 provided in the transport unit 104 will be described. In addition, each component of the selection unit 150 is provided in the transport pipe 145 that constitutes the transport unit 104. The selection unit 150 provided in the first straight section 141 successively includes a quadrupole electromagnet 151, a steering electromagnet 152, an energy attenuator 153, a quadrupole electromagnet 151, a collimator 154, and a beam stopper 155 from the upstream side. The quadrupole electromagnet 151 is an electromagnet for bunching a charged particle beam and shaping the charged particle beam. The steering electromagnet 152 is an electromagnet for correcting the orbit of the charged particle beam. The energy attenuator 153 is a mechanism for reducing the energy of the charged particle beam as a whole and adjusting the range. For example, the energy attenuator 153 reduces the charged particle beam B1 emitted from the accelerator 102 to a charged particle beam B3 of 70 MeV (reference Figure 5 ). At this time, since the energy of the charged particle beam B3 decreases, the spread of the momentum becomes larger compared to the charged particle beams B1 and B2. As the spread of the momentum of the charged particle beam B3, for example, the momentum of the charged particle beam B3 is scattered by 6% or more. The collimator 154 adjusts the shape, size, and divergence of the charged particle beam. The collimator 154 shapes the shape of the charged particle beam to adjust the size (dimension) of the charged particle beam and thereby adjusts the divergence of the charged particle beam. The beam stopper 155 is a mechanism for switching between the emission and stop of the charged particle beam.

[0056] The selection unit 150 provided in the curved section 143 successively includes a deflection electromagnet 156A, a quadrupole electromagnet 151, a momentum analysis slit 157, a quadrupole electromagnet 151, and a deflection electromagnet 156B from the upstream side. A plurality of quadrupole electromagnets 151 can be respectively provided before and after the momentum analysis slit 157. The deflection electromagnet 156A is an electromagnet for bending the orbit of the charged particle beam transmitted from the first straight section 141. The degree of bending of the charged particle beam varies according to the energy. Therefore, by bending the charged particle beam with the deflection electromagnet 156A and passing it through the momentum analysis slit 157, a charged particle beam with a desired energy can be selected. At a position downstream of the energy attenuator 153 in the transport unit 104, the charged particle beam B3 transmitted to the momentum analysis slit 157 passes through the momentum analysis slit 157 and becomes a state in which the energy outside the region near the peak in the energy distribution of the charged particle beam B3 is cut (reference Figure 5 region E1). That is, the charged particle beam B3 passes through the momentum analysis slit 157 and becomes a charged particle beam within the range of the region E1 in the energy distribution (hereinafter referred to as the charged particle beam B4), and is transmitted downstream.

[0057] Then, the deflection electromagnet 156B bends the orbit so that the charged particle beam B4 with a selected energy is directed toward the second straight section 142. The curved section 143 has only two sets of deflection electromagnets 156A and 156B, and no other sets of deflection electromagnets are provided between the deflection electromagnets 156A and 156B. In addition, when the deflection electromagnets are continuously arranged, they are regarded as a set of deflection electromagnets. That is, when the deflection electromagnet 156A is divided into a plurality of continuous deflection electromagnets, they are regarded as a set of deflection electromagnets. The region between the deflection electromagnets 156A and 156B in the curved section 143 becomes a straight section extending linearly, but this straight section is shorter than the first straight section 141.

[0058] The selection unit 150 provided in the second straight section 142 includes a quadrupole electromagnet 151 and a steering electromagnet 152 in order from the upstream side. In addition, the components of the selection unit 150 are not provided in the portion of the second straight section 142 buried in the indoor shielding wall. In the charged particle beam irradiation apparatus 100 of Comparative Example 1, the inside of the channel is vacuum, and the water equivalent thickness of the nasal attenuator is about 4 cm. Based on the above, in the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam B1 generated by the accelerator 102 passes through the energy attenuator 153 and its energy is reduced to become the charged particle beam B3. In the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam B3 passes through the momentum analysis slit 157 and becomes the charged particle beam B4 whose energy distribution is limited within the range of the region E1. In the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam B4 is transmitted to the nasal attenuator.

[0059] In the charged particle beam irradiation apparatus 100 of Comparative Example 1, in order to select the charged particle beam with a desired energy, the transmission unit 104 needs to have the curved section 143. Since the transmission unit 104 extends over a large range, in the charged particle beam irradiation apparatus 100 of Comparative Example 1, there is a problem that the installation area of the equipment for arranging the accelerator 102, the irradiation unit 103, and the transmission unit 104 becomes large. On the contrary, in the charged particle beam irradiation apparatus 1 of the present embodiment, since the selection unit 150 is not provided in the transmission unit 4, the shape can be freely changed according to the environment where the transmission unit 4 is arranged. For example, the transmission unit 4 can be made linear. Thus, compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam irradiation apparatus 1 of the present embodiment can more appropriately reduce the installation area. The charged particle beam irradiation apparatus 1 can miniaturize the entire apparatus and reduce the installation area.

[0060] Next, use Figure 8 to illustrate the case of shortening the irradiation time. Figure 8 (a) is a graph showing the Bragg peak of the charged particle beam emitted from the charged particle beam irradiation apparatus according to an embodiment of the present invention. Figure 8(b) is a graph showing the Bragg peak of the charged particle beam emitted from the charged particle beam irradiation apparatus according to Comparative Example 1. That is, Figure 8 (b) is a graph showing the Bragg peak of a charged particle beam having an energy lower than the energy of the charged particle beam emitted from the charged particle beam irradiation apparatus 1 of the present embodiment. Figure 8 (a) and Figure 8 For each of the graphs of (b), the vertical axis represents the dose and the horizontal axis represents the in-vivo depth. As Figure 8 (a) and Figure 8 (b) show, the irradiated object (tumor 14) is a part located inside the patient 15. In the charged particle beam irradiation apparatus 1 of the present embodiment and the charged particle beam irradiation apparatus of the modified example, an extended Bragg peak is formed by irradiating a plurality of charged particle beams B having Bragg peaks showing peaks at various in-vivo depths. Here, the Bragg peak is a characteristic of a charged particle beam that stops after releasing the maximum radiation dose at a specific depth corresponding to the incident energy, and the extended Bragg peak means that the Bragg peaks corresponding to a plurality of different energies are adjusted to coincide along the depth direction of the irradiated object to give a desired dose to the irradiated object.

[0061] Compared with the charged particle beam B4 of Comparative Example 1, the amount of movement dispersion of each charged particle beam B of the charged particle beam B2 of the present embodiment is larger (the energy width is larger). Therefore, the Bragg peak of the charged particle beam B2 of the present embodiment becomes broader than the Bragg peak of the charged particle beam B4 of Comparative Example 1. Therefore, compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam irradiation apparatus 1 of the present embodiment can more reduce the number of energies of the charged particle beam B having a Bragg peak required to form the same extended Bragg peak. Thus, compared with the control unit of the charged particle beam irradiation apparatus 100 of Comparative Example 1, the control unit 80 of the charged particle beam irradiation apparatus 1 switches the energy of the charged particle beam B less frequently. Compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam irradiation apparatus 1 can more shorten the irradiation time of the charged particle beam B.

[0062] Here, in the charged particle beam irradiation device 100 of Comparative Example 1, the following case is considered: instead of the charged particle beam B3, the charged particle beam after passing through the energy attenuator 153 is set to a charged particle beam of the same energy as the charged particle beam B2 in the charged particle beam irradiation device 1 of the present embodiment. This charged particle beam irradiation device is used as the charged particle beam irradiation device of Comparative Example 2, and the water equivalent thickness of the nasal attenuator is appropriately changed. In this case, the charged particle beam B2 after passing through the energy attenuator of Comparative Example 2 passes through the momentum analysis slit and becomes the charged particle beam B5 whose energy distribution is limited to the range of the region E1. Therefore, compared with the charged particle beam B5 in the irradiation section, the momentum of the charged particle beam B2 in the irradiation section 3 of the charged particle beam irradiation device 1 of the present embodiment is more diffuse. Compared with the Bragg peak of the charged particle beam B5 in the charged particle beam irradiation device of Comparative Example 2, the Bragg peak of the charged particle beam B2 in the charged particle beam irradiation device 1 of the present embodiment becomes thicker. Therefore, the charged particle beam irradiation device 1 of the present embodiment, which is not provided with the motion amount analysis slit 157 , can further shorten the irradiation time of the charged particle beam B compared to the charged particle beam irradiation device of Comparative Example 2.

[0063] As described above, the transmission unit 4 of the charged particle beam irradiation device 1 involved in the present embodiment can transmit the charged particle beam B2 from the energy attenuator 43 to the irradiation unit 3 without providing a momentum analysis slit for selecting a specific range of energy from the energy of the charged particle beam B2. Therefore, the Bragg peak of the charged particle beam B2 of the present embodiment becomes thicker, especially compared with the charged particle beams B4 and B5 when the momentum analysis slit is provided (Comparative Examples 1 and 2). Therefore, in the charged particle beam irradiation device 1, the amount of energy of the charged particle beam B required for the formation of the enlarged Bragg peak is reduced, and the number of times the energy of the charged particle beam B is switched is reduced. Based on the above, the charged particle beam irradiation device 1 can shorten the irradiation time of the charged particle beam B.

[0064] Furthermore, the charged particle beam irradiation device 1 according to the present embodiment is not provided with a momentum analysis slit in the gantry 5 as in Patent Document 1. When the momentum analysis slit is housed in the gantry, an unnecessary neutron beam is generated from the proton beam stopped in the momentum analysis slit, and therefore it is considered that an unnecessary neutron dose irradiated to the patient increases. However, the charged particle beam irradiation device 1 according to the present embodiment does not have a momentum analysis slit, and thus it is possible to suppress the generation of unnecessary neutron beams.

[0065] Further, in the charged particle beam irradiation apparatus 1 according to the present embodiment, the collimator 44 can adjust the shape, size, and divergence of the charged particle beam B that has passed through the energy attenuator 43, and can transmit the charged particle beam B from the energy attenuator 43 to the irradiation unit 3 while maintaining the energy distribution of the charged particle beam B. At this time, since the shape, size, and divergence of the charged particle beam B are adjusted by the collimator 44, the charged particle beam B can pass through the inside of the channel 11 without contacting, for example, the channel 11 of the irradiation unit 3 that is further downstream than the collimator 44.

[0066] Further, in the charged particle beam irradiation apparatus 1 according to the present embodiment, the transmission unit 4 has an aperture through which the charged particle beam B2 can pass. Therefore, the transmission unit 4 can transmit the charged particle beam B2 from the energy attenuator 43 to the irradiation unit 3 while maintaining the energy distribution of the charged particle beam B2 without selecting a specific range of energy for the charged particle beam B2.

[0067] Compared with the nasal attenuator of the charged particle beam irradiation apparatus 100 of Comparative Example 1, the water equivalent thickness of the nasal attenuator 30 of the charged particle beam irradiation apparatus 1 according to the present embodiment is greater. This is because the energy of the charged particle beam B2 is greater than that of the charged particle beam B4, and thus the tumor 14 (the irradiated object) located in the shallow part of the patient 15 can be irradiated.

[0068] In the charged particle beam irradiation apparatus 1 of the present embodiment, the energy attenuator 43 can more effectively suppress the spread of the energy distribution of the charged particle beam B2 compared to the charged particle beam B3 by making the momentum dispersion of the charged particle beam B2 less than 6%. Here, in the charged particle beam irradiation apparatus 1 of the present embodiment, consider the following situation: Instead of the charged particle beam B2, the charged particle beam of the irradiation unit 3 is set to a charged particle beam having the same energy as the charged particle beam B3 upstream of the momentum analysis slit 157 in the charged particle beam irradiation apparatus 100 of Comparative Example 1. This charged particle beam irradiation apparatus is used as a charged particle beam irradiation apparatus of a modified example (another embodiment of the present invention), and the water equivalent thickness of the nasal attenuator is appropriately changed. As described above, the momentum dispersion of the charged particle beam B3 is 6% or more. In this case, the charged particle beam B3, which has a greater momentum dispersion than the charged particle beam B2, that is, the charged particle beam B3 having a larger beam diameter than the charged particle beam B2, passes through the transfer unit. Therefore, when the charged particle beam B3 is used, it is necessary to increase the diameter of the transfer unit more than in the case of the charged particle beam B2. And, when the charged particle beam B3, which has a larger beam diameter than the charged particle beam B2, comes into contact with the deflection electromagnet or the channel of the irradiation unit downstream of the transfer unit and disappears, the charged particle beam irradiation apparatus of the modified example may become radioactive or may increase the unnecessary radiation dose. When the charged particle beam B3 is used, in order to suppress this possibility, it is necessary to more fully increase the channels and deflection electromagnets, etc. of the charged particle beam irradiation apparatus of the modified example than in the case of the charged particle beam B2.

[0069] Based on the above, in the charged particle beam irradiation apparatus 1 of the present embodiment, by setting the charged particle beam B downstream of the energy attenuator 43 to the charged particle beam B2 with a momentum dispersion of less than 6%, compared with the charged particle beam irradiation apparatus of the modified example, it is possible to more effectively suppress the enlargement of the equipment and appropriately reduce the installation area. Also, compared with the charged particle beam irradiation apparatus of the modified example, the charged particle beam irradiation apparatus 1 of the present embodiment can more effectively suppress the enlargement of the equipment while suppressing the radioactivity of the equipment and unnecessary radiation dose.

[0070] In addition, in the charged particle beam irradiation apparatus according to the modified example, there is no need to provide the selection unit 150 in the transport unit. Therefore, compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the shape corresponding to the environment in which the transport unit 4 is disposed can be changed more freely. For example, in the charged particle beam irradiation apparatus according to the modified example, the transport unit 4 can also be formed in a linear shape. Thus, compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam irradiation apparatus according to the modified example can more appropriately reduce the installation area. Further, the Bragg peak of the charged particle beam B3 in the irradiation unit of the charged particle beam irradiation apparatus according to the modified example becomes broader than the Bragg peak of the charged particle beam B4 in the irradiation unit of Comparative Example 1. Thus, compared with the charged particle beam irradiation apparatus 100 of Comparative Example 1, the charged particle beam irradiation apparatus according to the modified example can more effectively shorten the irradiation time of the charged particle beam B.

[0071] Here, as an example, the ranges of the charged particle beams B (proton beams) having different energies are summarized. The range of the 60 MeV charged particle beam B is 3 cm, the range of the 70 MeV charged particle beam B is 4 cm, and the range of the 110 MeV charged particle beam B is 9 cm. When the charged particle beam B is incident on water, the beam diameters of the charged particle beams B (proton beams) having different energies at a water depth of 4 cm are exemplified. The 60 MeV charged particle beam B does not reach a water depth of 4 cm. The beam diameter of the 70 MeV charged particle beam B at a water depth of 4 cm is 10 mm. When the water equivalent thickness of the nasal attenuator 30 is set to 5 cm, the beam diameter of the 110 MeV charged particle beam B at a water depth of 4 cm is 7 mm.

[0072] Next, when the charged particle beam B is incident on water, the beam diameters of the charged particle beams B (proton beams) having different energies at a water depth of 2 cm are exemplified. When the water equivalent thickness of the nasal attenuator is set to 1 cm, the beam diameter of the 60 MeV charged particle beam B at a water depth of 2 cm can be 11 mm. When the water equivalent thickness of the nasal attenuator is set to 2 cm, the beam diameter of the 70 MeV charged particle beam B at a water depth of 2 cm is 10 mm. When the water equivalent thickness of the nasal attenuator 30 is set to 7 cm, the beam diameter of the 110 MeV charged particle beam B at a water depth of 2 cm is 7 mm. By changing the thickness of the nasal attenuator 30 according to the energy of the charged particle beam B, the water depth with respect to the charged particle beam B can be made uniform.

[0073] Based on the above results, in the charged particle beam B having multiple different energies, when the water equivalent thickness of the nasal attenuator 30 is appropriately set for the charged particle beam B of 110 MeV, the beam size at the same water depth becomes the smallest. Thus, when the object to be irradiated with the charged particle beam B2 is located in the shallow region, compared with the charged particle beam B (e.g., 70 MeV) having an energy lower than that of the charged particle beam B2, the beam diameter of the beam emitted under the condition that the nasal attenuator 30 is combined with the charged particle beam B2 having an energy of 80 MeV or more and 150 MeV or less becomes smaller. Therefore, when the tumor 14 (the object to be irradiated) of the patient 15 is located in the shallow region, the charged particle beam irradiation device 1 can irradiate, for example, the charged particle beam B2 having an energy of 80 MeV or more and 150 MeV or less according to the position, size, or shape of the tumor 14. In addition, when the tumor 14 (the object to be irradiated) is located in the shallow region, the charged particle beam irradiation device 1 can, for example, irradiate the charged particle beam B2 having an energy of 90 MeV or more and 150 MeV or less, can also irradiate the charged particle beam B2 having an energy of 100 MeV or more and 150 MeV or less, and can also irradiate the charged particle beam B2 having an energy of 110 MeV or more and 150 MeV or less. And, in cases where the tumor 14 (the object to be irradiated) is located in the deep region or the like, the charged particle beam irradiation device 1 can, for example, irradiate the charged particle beam B2 having an energy of 150 MeV or more.

[0074] Moreover, compared with the case where the energy is reduced from the charged particle beam B1 to the charged particle beam B3 in the transmission unit of the modified example, the energy ratio of reducing the energy from the charged particle beam B1 to the charged particle beam B2 in the transmission unit 4 of the present embodiment is smaller. Therefore, in the present embodiment, compared with the energy transmission efficiency of the modified example, the energy transmission efficiency during the transmission of the charged particle beam B in the transmission unit 4 from the accelerator 2 to the irradiation unit 3 becomes higher. In the present embodiment, compared with the beam current at the isocenter of the modified example, the beam current at the isocenter AC in the gantry 5 increases, and thus the irradiation time for the tumor 14 (the object to be irradiated) of the patient 15 can be shortened.

[0075] Unlike the charged particle beam B4 of Comparative Example 1 and the charged particle beam B5 of Comparative Example 2, the charged particle beam B2 of the charged particle beam irradiation device 1 of the present embodiment does not perform energy selection in the momentum analysis slit 157, so it may not be possible to ensure the symmetry of the cross-sectional shape of the beam in the irradiation unit 3. However, the charged particle beam B2 scatters due to the atmosphere (air) inside the channel 11 when passing through the channel 11 of the irradiation unit 3. Thus, even when the charged particle beam irradiation device 1 does not have a momentum analysis slit (selection unit), the symmetry of the cross-sectional shape of the beam of the charged particle beam B2 can be ensured. Therefore, the irradiation unit 3 can irradiate the beam of the charged particle beam B2 to an appropriate range.

[0076] The internal path 4B of the transport section 4 has a deflection magnet (deflection electromagnet 8) with a sextupole component that bunches the charged particle beam B2 and trims the shape of the charged particle beam B2. Therefore, in the internal path 4B of the transport section 4, the shape of the charged particle beam B2 can be trimmed according to the energy distribution of the passing charged particle beam B2, and the charged particle beam B2 can be appropriately transported from the accelerator 2 to the irradiation section 3.

[0077] The present invention is not limited to the above-described embodiments.

[0078] For example, the energy attenuator 43 can reduce the energy of the charged particle beam B generated by the accelerator so that the momentum spread of the charged particle beam B becomes 6% or more. At this time, each part of the transport section 4 has an aperture through which the charged particle beam B can pass. The collimator 44 may not be provided between the energy attenuator 43 and the irradiation section 3. At this time, each part of the transport section 4 has an aperture through which the charged particle beam B can pass. The inside of the passage 11 may be a vacuum, or a rare gas may be filled inside the passage 11. The rare gas is, for example, argon. The deflection electromagnet 8 located on the internal path 4B of the transport section 4 may not be a sextupole magnet or a deflection magnet with a sextupole component.

[0079] Moreover, the structure of the building 6 and the layout of each component can be appropriately changed without departing from the gist of the present invention.

Claims

1. A charged particle beam irradiation apparatus that irradiates a charged particle beam, the charged particle beam irradiation apparatus comprising: an accelerator that accelerates charged particles to generate the charged particle beam; an irradiation unit that can rotate by a gantry and irradiates the charged particle beam generated by the accelerator; and a transport unit that has an attenuator disposed outside the irradiation unit and that reduces the energy of the charged particle beam generated by the accelerator, and a collimator disposed between the attenuator and the irradiation unit and that adjusts the shape, size, and divergence of the charged particle beam, and transports the charged particle beam generated by the accelerator to the irradiation unit, the transport unit having an aperture through which the charged particle beam whose energy has been reduced by the attenuator and whose shape, size, and divergence have been adjusted by the collimator can pass while maintaining the state of the energy distribution between the collimator and the irradiation unit, in the transport unit, no component for selecting a charged particle beam having a desired energy is provided between the collimator and the irradiation unit, and the path for transporting the charged particle beam from the accelerator to the gantry extends linearly.

2. The charged particle beam irradiation apparatus according to claim 1, wherein the irradiation unit further has a scanning electromagnet that scans the charged particle beam, a channel through which the charged particle beam scanned by the scanning electromagnet passes, and a monitor that detects the charged particle beam that has passed through the channel, the inside of the channel is exposed to the atmosphere.

3. The charged particle beam irradiation apparatus according to claim 1, wherein the attenuator reduces the energy of the charged particle beam generated by the accelerator so that the dispersion of the momentum of the charged particle beam is less than 6%.

4. The charged particle beam irradiation apparatus according to any one of claims 1 to 3, wherein the transport unit has a sextupole magnet or a deflection magnet having a sextupole component that bunches the charged particle beam and trims the shape of the charged particle beam.

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