Particle beam therapy apparatus and electromagnet

Abstract

The invention provides a particle beam therapy device and an electromagnet capable of improving the performance of the electromagnet for deflecting a particle beam. In an accelerator (100), an electromagnet (1) is provided with: coils (2A, 2B) that generate a magnetic field that deflects a particle beam (B); and a magnetic body (3) disposed in an opening on the inner peripheral side of the coils (2A, 2B). The electromagnet (1) is capable of deflecting the particle beam (B) by the magnetic field of the coils (2A, 2B) with the magnetic body (3) as the magnetic pole. Here, the magnetic body (3) may have a predetermined reference surface (SF), and also have protruding portions (12A, 12B) protruding from the reference surface (SF). At this time, the effective magnetic pole length can be extended by an amount that the protruding portions (12A, 12B) protrude from the reference surface (SF). As a result, the performance of the electromagnet (1) that deflects the particle beam (B) can be improved.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2023-177377 filed on October 13, 2023. The entire contents of the Japanese Patent Application are incorporated herein by reference. Technical Field

[0002] The invention relates to a particle beam therapeutic device and an electromagnet. Background Art

[0003] Conventionally, as a particle beam therapy apparatus for treating an affected part of a patient by irradiating it with a particle beam, for example, there is known an apparatus described in Patent Document 1. In the particle beam therapy apparatus described in Patent Document 1, a particle beam is irradiated from an irradiation unit.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-209372

[0005] In the particle beam therapy device described above, an electromagnet is used to deflect the particle beam. This electromagnet includes a coil that generates a magnetic field to deflect the particle beam and a magnetic body disposed at an opening on the inner circumference of the coil. This electromagnet is also required to have further improved performance. Summary of the invention

[0006] Therefore, an object of the present invention is to provide a particle beam therapy apparatus and an electromagnet capable of improving the performance of an electromagnet for deflecting a particle beam.

[0007] A particle beam therapy device according to one embodiment of the present invention irradiates a particle beam to an irradiated body. The particle beam therapy device may include an electromagnet for deflecting the particle beam. The electromagnet includes: a coil that generates a magnetic field that deflects the particle beam; and a magnetic body that is arranged at an opening on the inner circumference of the coil, the magnetic body having a predetermined reference plane and a protrusion that protrudes from the reference plane.

[0008] In a particle beam therapy device, an electromagnet has a coil that generates a magnetic field that deflects a particle beam and a magnetic body disposed at an opening on the inner circumference of the coil. The electromagnet can use the magnetic body as a magnetic pole and deflect the particle beam through the magnetic field of the coil. Here, the magnetic body can have a predetermined reference plane and a protrusion protruding from the reference plane. At this time, the effective magnetic pole length can be extended by the amount of the protrusion protruding from the reference plane. Thus, the performance of the electromagnet that deflects the particle beam can be improved.

[0009] The magnetic body may include an axially extending yoke portion extending along the beam axis of the particle beam, the reference plane being set at the axial yoke end face of the yoke portion, and the protrusion protruding axially from the yoke end face. In this case, the effective magnetic pole length can be easily extended by simply adding the protrusion to the yoke end face.

[0010] The coil has a coil end portion arranged on the outside of the yoke end face in the axial direction, and when viewed from the thickness direction of the coil, the protrusion can overlap with the coil end portion. The coil end portion arranged on the outside of the yoke end face is the portion that occupies the space in the electromagnet. In the case where a protrusion overlapping with such a yoke end face is provided, the overlapping portion can lengthen the effective magnetic pole length, while not increasing the occupied space. Therefore, the increase in the occupied space can be suppressed while improving the performance of the electromagnet.

[0011] The coil may have a curved portion that is curved in a direction intersecting the axial direction on the outer side of the yoke end face in the axial direction, and an opening is formed in the curved portion between the beam axis and the coil end, and the protrusion is arranged in the opening. When the curved portion is provided on the coil, the opening is formed as a dead zone. In contrast, by arranging the protrusion in the opening that becomes the dead zone, the dead zone can be effectively used to extend the effective magnetic pole length.

[0012] The coil may have a rectangular ring shape with the length direction in the axial direction. In the coil having such a shape, there is a coil end disposed outside the end surface of the yoke at the end in the length direction. By arranging the protrusion to overlap with such a coil end, the increase in the occupied space can be suppressed while improving the performance of the electromagnet.

[0013] The coil end may have an end surface disposed at the end in the axial direction, and the protrusion may protrude to the end surface side of the coil end. In this case, the effective magnetic pole length of the protrusion may be extended as much as possible within a range that does not increase the occupied space.

[0014] An electromagnet according to one embodiment of the present invention deflects a particle beam and includes: a coil that generates a magnetic field that deflects the particle beam; and a magnetic body disposed at an opening on the inner circumference side of the coil, the magnetic body having a predetermined reference plane and a protrusion protruding from the reference plane.

[0015] This electromagnet can also provide the same effects as those of the above-mentioned particle beam therapy system.

[0016] According to the present invention, a particle beam therapy device and an electromagnet capable of improving the performance of an electromagnet for deflecting a particle beam are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram showing the structure of a particle beam therapy apparatus according to one embodiment of the present invention.

[0018] Figure 2 This is a diagram showing a schematic structure of an accelerator.

[0019] Figure 3 It is a three-dimensional diagram of an electromagnet.

[0020] Figure 4 This is a top view of the electromagnet as viewed from the Y-axis direction.

[0021] Figure 5 is along Figure 4 A cross-sectional view taken along line VV is shown.

[0022] Figure 6 This is the front view of the electromagnet when viewed from the Z-axis direction.

[0023] Figure 7 It is a three-dimensional diagram of an electromagnet.

[0024] Figure 8 This is a top view of the electromagnet as viewed from the Y-axis direction.

[0025] Fig. 9 is along Figure 8 A cross-sectional view taken along line IX-IX is shown.

[0026] Fig.10 A calculation example confirming the magnetic pole extension effect produced by providing the protrusion is shown.

[0027] In the figure: 1-electromagnet, 2A, 2B-coil, 6-coil end, 3-magnetic body, 11-yoke part, 11a, 11b-yoke end surface, 12A, 12B-protrusion, 101-particle beam therapy device, SF-reference plane. DETAILED DESCRIPTION

[0028] Hereinafter, an accelerator 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 repeated descriptions are omitted.

[0029] Figure 1 1 is a schematic diagram showing a particle beam therapy device 101 according to an embodiment of the present invention. The particle beam therapy device 101 is a system used in cancer treatment based on radiotherapy, etc. The particle beam therapy device 101 includes: an accelerator 100 that accelerates charged particles generated in an ion source device and emits them as a particle beam; an irradiation unit 102 that irradiates the particle beam to an irradiated object; and a transport path 131 that transports the particle beam emitted from the accelerator 100 to the irradiation unit 102. The irradiation unit 102 is mounted on a rotating gantry 105 that is arranged to surround a treatment table 104. The rotating gantry 105 can rotate the irradiation unit 102 around the treatment table 104.

[0030] The accelerator 100 is a device that accelerates charged particles to emit a particle beam of a preset intensity. Examples of the accelerator 100 include a cyclotron accelerator and a synchrocyclotron accelerator. The particle beam B generated in the accelerator 100 is transported to the irradiation unit 102 via a transport path 131 .

[0031] The irradiation unit 102 irradiates a tumor (irradiated body) 114 in the patient 115 with a particle beam. A particle beam is a particle beam that accelerates 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 unit 102 is a device that irradiates a particle beam B on the tumor 114. The particle beam B is emitted from an accelerator 100 and transported to the irradiation unit 102 through a transport path 131. The accelerator 100 accelerates charged particles generated in an ion source (not shown). In addition, the irradiation unit 102 irradiates the particle beam B based on a scanning method. In addition, the scanning method is not particularly limited, and line scanning, raster scanning, point scanning, etc. may be used. Furthermore, the irradiation method of the irradiation unit 102 is not limited to the scanning method.

[0032] The irradiation unit 102 includes a scanning electromagnet 150 and various monitors 151. As the scanning electromagnet 150, an X-axis scanning electromagnet 150X and a Y-axis scanning electromagnet 150Y are used. The X-axis scanning electromagnet 150X and the Y-axis scanning electromagnet 150Y are composed of an electromagnet 1, and the magnetic field of the electromagnet 1 is changed according to the current supplied from the control unit 7, so that the particle beam passing through the electromagnet 1 is scanned. The X-axis scanning electromagnet 150X scans the particle beam along the X-axis direction, and the Y-axis scanning electromagnet 150Y scans the particle beam along the Y-axis direction. In addition, the scanning electromagnet 150 scans the particle beam B in a manner of irradiating the particle beam B according to the scanning pattern pre-planned by the treatment planning device.

[0033] The transport path 131 connects the accelerator 100 and the emission port of the irradiation unit 102, and transports the particle beam emitted from the accelerator 100 to the irradiation unit 102. The transport path 131 has a beam adjustment unit 130 that adjusts the beam size, beam position, beam symmetry, and transmission efficiency of the particle beam. The beam adjustment unit 130 includes a plurality of electromagnets. The beam adjustment unit 130 includes a quadrupole electromagnet that adjusts the beam size and a deflection electromagnet that adjusts the beam position.

[0034] The electromagnet 1 described below can be applied to the scanning electromagnet 150 of the particle beam therapy system 101. However, in the particle beam therapy system 101, the electromagnet 1 described below can be used as long as it is an electromagnet that changes a particle beam.

[0035] Figure 2: is a schematic diagram showing the structure of the accelerator 100. The accelerator 100 is a device that accelerates charged particles to emit a particle beam B of a predetermined intensity. Examples of the accelerator 100 include a cyclotron, a synchrotron, and a synchrocyclotron. Figure 2 In (a), a case where a cyclotron 110 is used as the accelerator 100 is illustrated. The cyclotron 110 has an acceleration space clamped by a pair of magnetic poles in a vacuum container 111. Coils are arranged around the magnetic poles, and a magnetic field is formed between the magnetic poles. The cyclotron 110 generates an electric field for accelerating charged particles in the acceleration space by Dee electrodes. As a result, the cyclotron 110 causes the charged particles to spirally rotate and accelerate in the acceleration space to generate a particle beam B. The cyclotron 110 deflects the particle beam B by the electromagnet 1 so that the particle beam B is emitted from the ejection port 112. In the cyclotron 110, the electromagnet 1 is used to deflect the accelerated particle beam B.

[0036] Figure 2 In (b), a case where a synchrotron 120 is used as the accelerator 100 is illustrated. In the synchrotron 120, the accelerated particles are incident into a ring-shaped orbit 121, and are deflected by an electromagnet 1 while being rotated in the orbit 121, thereby being accelerated in an acceleration cavity 122. The synchrotron 120 emits a sufficiently accelerated particle beam B from an emission port 123. In the synchrotron 120, an electromagnet 1 is used to deflect the particle beam B on the orbit for acceleration.

[0037] Next, refer to Figure 3 to Figure 6 , the structure of the electromagnet 1 is described. Figure 3 It is a three-dimensional diagram of the electromagnet 1. Figure 4 This is a plan view of the electromagnet 1 as viewed from the Y-axis direction. Figure 5 is along Figure 4 A cross-sectional view taken along line VV is shown. Figure 6 This is the front view of the electromagnet 1 when viewed from the Z-axis direction. In addition, for the convenience of explanation, XYZ coordinates are set. The Z-axis direction is set to be parallel to the axis extending from the beam axis CL of the particle beam B. In addition, in the following description, the beam axis CL is the axis when it is not deflected by the electromagnet 1. The X-axis direction is the direction orthogonal to the Z-axis direction. The Y-axis direction is the direction orthogonal to the X-axis direction and the Z-axis direction. Figure 3 As shown, the electromagnet 1 includes coils 2A and 2B and a magnetic body 3 .

[0038] The coils 2A and 2B generate a magnetic field that deflects the particle beam B. The coils 2A and 2B are arranged to face each other in a state of being separated from each other in the Y-axis direction. The coil 2A is arranged on the positive side in the Y-axis direction. The coil 2B is arranged on the negative side in the Y-axis direction. The beam axis CL of the particle beam B is set in the space sandwiched between the coils 2A and 2B (see also Figure 5 ). In this space, the beam axis CL is arranged at the center in the X-axis direction.

[0039] Coils 2A and 2B are saddle-shaped coils. Coils 2A and 2B are formed by forming a rectangular ring-shaped racetrack-shaped coil (as described later) with its length in the Z-axis direction. Figure 7 The coils 2A and 2B are formed by bending the two ends in the length direction. The coils 2A and 2B are formed by winding a conductive wire multiple times. The coils 2A and 2B have a pair of coil side ends 4, 4 extending in the length direction (i.e., the Z-axis direction) and a pair of coil ends 6, 6 at both end sides in the Z-axis direction. The coil side ends 4, 4 are separated from each other in the X-axis direction and extend in parallel in the Z-axis direction. An opening portion SP1 is formed between the coil side ends 4, 4 that passes through in the Y-axis direction (also refer to Figure 5 ). The coil ends 6, 6 are separated from each other in the Z-axis direction and extend in parallel in the X-axis direction.

[0040] Furthermore, the coils 2A and 2B have bent portions 8 and 8 bent toward a direction intersecting the axial direction (i.e., the Y-axis direction) at both end sides in the Z-axis direction. The bent portions 8 and 8 of the coil 2A are bent toward the positive side in the Y-axis direction. The bent portion 8 has a pair of coil side ends 9 and 9 and the aforementioned coil end 6. The coil side ends 9 and 9 extend from the ends in the Z-axis direction of the aforementioned coil side ends 4 and 4 toward the positive side in the Y-axis direction. The corner between the coil side ends 9 and 9 and the coil side ends 4 and 4 is bent. The inner peripheral surface 9a of the corner is bent in a manner of standing up toward the positive side in the Y-axis direction (refer to Figure 5 The positive ends of the coil side ends 9, 9 in the Y-axis direction are connected to each other through the coil end 6. By adopting this structure, an opening SP2 is formed between the beam axis CL and the coil end 6 in the curved portion 8 (see also Figure 5 ). The opening portion SP2 is formed between a pair of coil side ends 9, 9. The opening portion SP2 is a space connected to the opening portion SP1 between the coil side ends 4, 4. In addition, the bent portions 8, 8 of the coil 2B are bent toward the negative side in the Y-axis direction. The coil 2B has the same structure as the coil 2A except that the bending directions of the bent portions 8, 8 are different.

[0041] The magnetic body 3 is a member disposed in the openings SP1 and SP2 on the inner peripheral side of the coils 2A and 2B. The magnetic body 3 includes a yoke portion 11 .

[0042] The yoke 11 extends in the axial direction along the beam axis CL of the particle beam B. The yoke 11 has a rectangular ring shape when viewed from the Z-axis direction. The yoke 11 has end walls 21A and 21B extending in the X-axis direction and connecting walls 23A and 23B extending in the Y-axis direction.

[0043] The end wall portion 21A is arranged on the positive side in the Y-axis direction relative to the coil 2A. The end wall portion 21B is arranged on the negative side in the Y-axis direction relative to the coil 2B. The end wall portions 21A and 21B are configured to extend outwardly to the positive and negative sides in the X-axis direction more than the coils 2A and 2B. The connecting wall portion 23A extends in the Y-axis direction in a manner connecting the ends on the positive side in the X-axis direction of the end walls 21A and 21B to each other. The connecting wall portion 23A is arranged on the positive side in the X-axis direction of the coils 2A and 2B. The connecting wall portion 23B extends in the Y-axis direction in a manner connecting the ends on the negative side in the X-axis direction of the end walls 21A and 21B to each other. The connecting wall portion 23B is arranged on the negative side in the X-axis direction of the coils 2A and 2B.

[0044] like Figure 6 As shown, the end wall portion 21A has an inner peripheral surface 21a on the inner peripheral side in the Y-axis direction (i.e., the negative side in the Y-axis direction). The main surface 4a on the positive side in the Y-axis direction of the coil side end portion 4 of the coil 2A is configured to contact the inner peripheral surface 21a of the end wall portion 21A. The yoke portion 11 has a leg portion 26 extending from the inner peripheral surface 21a toward the negative side in the Y-axis direction and entering the opening portion SP1 of the coil 2A. In addition, as shown Figure 5 As shown, in this embodiment, the protrusion amount of the positive side portion in the Z-axis direction of the leg portion 26 toward the negative side in the Y-axis direction is greater than that of the negative side portion. Therefore, the surface 26a on the negative side in the Y-axis direction of the leg portion 26 is inclined toward the positive side in the Y-axis direction as it moves from the negative side in the Z-axis direction toward the positive side.

[0045] like Figure 3 As shown, the yoke portion 11 has yoke end faces 11a and 11b in the Z-axis direction (see also Figure 4 and Figure 5 ). The yoke portion 11 has yoke end faces 11c and 11d in the Y-axis direction. The yoke portion 11 has yoke end faces 11e and 11f in the X-axis direction. The yoke end face 11a is formed on the positive side in the Z-axis direction. The yoke end face 11b is formed on the negative side in the Z-axis direction. The yoke end faces 11a and 11b are end faces in the Z-axis direction of the end wall portions 21A and 21B and the connecting wall portions 23A and 23B. The yoke end face 11c is formed on the positive side in the Y-axis direction. The yoke end face 11d is formed on the negative side in the Y-axis direction. The yoke end face 11e is formed on the positive side in the X-axis direction. The yoke end face 11f is formed on the negative side in the X-axis direction. These yoke end faces 11a to 11f are faces that determine the outer shape of the yoke portion 11.

[0046] The two ends of the coils 2A and 2B in the Z-axis direction are arranged outside the yoke end faces 11a and 11b in the Z-axis direction. Specifically, the bent portion 8 of the coils 2A and 2B is arranged outside the yoke end faces 11a and 11b in the Z-axis direction. The coil side end 4 of the coils 2A and 2B is arranged substantially entirely between the yoke end faces 11a and 11b.

[0047] Here, the magnetic body 3 has a predetermined reference plane SF. The reference plane SF is a plane that determines the outer shape of the yoke portion 11. The reference plane SF is a plane that interferes with the parts of the coils 2A and 2B when the volume of the yoke portion 11 is increased by shifting the reference plane SF as a whole in a direction orthogonal to the reference plane SF, thereby limiting the above-mentioned shift. In the present embodiment, the reference plane SF is set at the yoke end faces 11a and 11b in the Z-axis direction of the yoke portion 11. Figure 5 As shown, when the yoke end face 11a is to be offset as a whole to the positive side in the Z-axis direction, it will interfere with the inner peripheral surface 9a of the corner. Therefore, the offset of the yoke end face 11a to the positive side in the Z-axis direction is restricted. Similarly, the offset of the yoke end face 11b to the negative side in the Z-axis direction is also restricted. In addition, regarding the yoke end faces 11c to 11f in the plane that determines the outer shape of the yoke part 11, when the yoke end faces 11c to 11f are offset as a whole to the outside, the yoke end faces 11c to 11f will not interfere with the coils 2A and 2B and can be offset, so they do not belong to the reference plane SF.

[0048] like Figure 3 and Figure 4 As shown, the magnetic body 3 has a pair of protrusions 12A, 12A protruding from the above-mentioned reference plane SF relative to the coil 2A. The protrusions 12A, 12A protrude outward from the yoke end faces 11a, 11b in the Z-axis direction. The magnetic body 3 has a pair of protrusions 12B, 12B protruding from the above-mentioned reference plane SF relative to the coil 2B. The protrusions 12B, 12B protrude outward from the yoke end faces 11a, 11b in the Z-axis direction.

[0049] In this embodiment, the protrusions 12A and 12B are arranged at the openings SP2 in the bent portions 8 of the coils 2A and 2B. Figure 4 As shown, when viewed from the thickness direction (Y-axis direction) of the coils 2A and 2B, the protrusions 12A and 12B overlap with the coil end portions 6 of the coils 2A and 2B.

[0050] like Figure 6As shown, the outer shape of the protrusion 12A when viewed from the Z-axis direction may have a shape corresponding to the shape of the inner circumference of the curved portion 8. However, the shape of the protrusion 12A is not particularly limited. Furthermore, the size of the gap GP1 between the outer shape of the protrusion 12A and the inner circumference of the curved portion 8 is not particularly limited, and they may be in contact with each other. The end of the negative side of the protrusion 12A in the Y-axis direction may reach the position of the surface 26a of the leg portion 26, but may also be configured at a position separated from the surface 26a. In addition, as Figure 5 As shown, the protrusion 12A on the positive side in the Z-axis direction may be smaller in the Y-axis direction than the protrusion 12A on the negative side in the Z-axis direction. However, the protrusions 12A, 12A on both sides may have the same size.

[0051] like Figure 5 As shown, the coil end 6 has an end face 6a arranged at the end in the Z-axis direction. The protrusion 12A can protrude to the end face 6a side of the coil end 6. The end face 12a of the protrusion 12A is arranged near the end face 6a of the coil end 6 in the Z-axis direction. The end face 12a of the protrusion 12A preferably does not protrude from the end face 6a of the coil end 6. However, the position of the end face 12a of the protrusion 12A is not particularly limited as long as the protrusion 12A is located at a position overlapping with the coil end 6. In addition, the protrusions 12B, 12B have the same structure as the protrusions 12A, 12A.

[0052] In addition, the magnetic body 3 can be formed by stacking a plurality of magnetic pole steel plates, for example. A magnetic pole steel plate corresponding to the shape of the yoke portion 11 when viewed from the Z-axis direction is prepared, and a plurality of magnetic pole steel plates are stacked to form the yoke portion 11. A magnetic pole steel plate corresponding to the shape of the protrusions 12A and 12B when viewed from the Z-axis direction is prepared, and a plurality of magnetic pole steel plates are stacked to form a block of the protrusions 12A and 12B. Next, the block of the protrusions 12A and 12B is fixed to the yoke portion 11 to form the magnetic body 3. In addition, the manufacturing method of the magnetic body 3 is not particularly limited, and the magnetic material can be processed into the shape of the magnetic body 3, or blocks of various parts can be formed and assembled.

[0053] Next, the effects of the particle beam therapy apparatus 101 and the electromagnet 1 according to the present embodiment will be described.

[0054] In the particle beam therapy device 101, the electromagnet 1 has coils 2A and 2B that generate a magnetic field that deflects the particle beam B, and a magnetic body 3 disposed at an opening on the inner circumference side of the coils 2A and 2B. The electromagnet 1 can deflect the particle beam B by the magnetic field of the coils 2A and 2B using the magnetic body 3 as a magnetic pole. Here, the magnetic body 3 can have a predetermined reference plane SF, and can have protrusions 12A and 12B protruding from the reference plane SF. At this time, the effective magnetic pole length can be extended by the amount of the protrusions 12A and 12B protruding from the reference plane SF. Thus, the performance of the electromagnet 1 that deflects the particle beam B can be improved.

[0055] The magnetic body 3 may include an axially extending yoke portion 11 extending along the beam axis CL of the particle beam B, the reference plane SF being set at the yoke end faces 11a and 11b in the axial direction of the yoke portion 11, and the protrusions 12A and 12B protruding in the axial direction from the yoke end faces 11a and 11b. In this case, the effective magnetic pole length can be easily extended by simply adding the protrusions 12A and 12B to the yoke end faces 11a and 11b.

[0056] The coils 2A and 2B have coil ends 6 disposed on the outside of the yoke end faces 11a and 11b in the axial direction, and the protrusions 12A and 12B can overlap with the coil ends 6 when viewed from the thickness direction of the coils 2A and 2B. The coil ends 6 disposed on the outside of the yoke end faces 11a and 11b are the parts that occupy the space in the electromagnet 1. When the protrusions 12A and 12B that overlap with the yoke end faces 11a and 11b are provided, the overlapping parts can lengthen the effective magnetic pole length without increasing the occupied space. Therefore, the performance of the electromagnet 1 can be improved while suppressing the increase in the occupied space.

[0057] The coils 2A and 2B have a curved portion 8 that is curved in a direction intersecting the axial direction on the outer side in the axial direction than the yoke end faces 11a and 11b. In the curved portion 8, an opening SP2 is formed between the beam axis CL and the coil end 6, and the protrusions 12A and 12B can be arranged at the opening SP2. When the curved portion 8 is provided on the coils 2A and 2B, the opening SP2 forms a dead zone. As a result of in-depth research conducted by the inventors, it was found that the performance can be greatly improved by simply adopting a structure that extends the magnetic component to the dead zone. Therefore, by configuring the protrusions 12A and 12B at the opening SP2 that becomes the dead zone, the dead zone can be effectively used to extend the effective magnetic pole length. For example, Fig.10 Calculation examples showing the effect of extending the magnetic poles by providing the protrusions 12A and 12B are shown in FIG. Figure 3 The structure of the protrusions 12A and 12B is not provided. Fig.10 As shown, the EFL product of the embodiment is greatly improved compared with the comparative example.

[0058] The coil end 6 has an axially distal end surface 6a, and the projections 12A and 12B may project to the end surface 6a side of the coil end 6. In this case, the effective magnetic pole length of the projections 12A and 12B can be extended as much as possible without increasing the occupied space.

[0059] As described above, since the performance of the electromagnet 1 can be improved without increasing the space occupied, there is no need to enlarge the electromagnet 1 in order to obtain the desired performance. Alternatively, the same performance as before can be obtained in a smaller space than before. Thus, the miniaturization of the electromagnet 1 can be achieved. In addition, in the case of a small electromagnet 1, the amount of coils 2A and 2B protruding from the yoke portion 11 in the entire electromagnet will be relatively large. In this way, the length of the magnetic pole that can be extended at the protruding portions 12A and 12B becomes relatively large. Therefore, the above-mentioned effect is more significant in the small electromagnet 1.

[0060] The electromagnet 1 is an electromagnet 1 for deflecting a particle beam B, and comprises coils 2A and 2B for generating a magnetic field for deflecting the particle beam B, and a magnetic body 3 having an opening SP2 arranged on the inner circumference side of the coils 2A and 2B, wherein the magnetic body 3 has a predetermined reference plane SF and protrusions 12A and 12B protruding from the reference plane SF.

[0061] According to the electromagnet 1 , the same operational effects as those of the above-mentioned particle beam therapy apparatus 101 can be obtained.

[0062] The present invention is not limited to the above-mentioned embodiments.

[0063] For example, you can also use Figure 7 to Figure 9 The electromagnet 1 shown in FIG. 1 is a modified example. In this modified example, the coils 2A and 2B have a rectangular ring shape (track shape) with the length direction in the Z-axis direction. In this case, the coils 2A and 2B do not have the bent portion 8, and are formed into a flat plate shape. Figure 8 As shown, the coil ends 6 of the coils 2A and 2B are arranged outside the yoke end faces 11 a and 11 b of the yoke portion 11 .

[0064] like Fig. 9 As shown, the leg portion 26 of the magnetic body 3 is inserted into the opening SP1 of the coil 2A. The surface 26a of the leg portion 26 is arranged on the negative side of the Y-axis direction relative to the coil 2A. The protrusion 12A protrudes from the reference plane SF (i.e., the yoke end surface 11b) to the negative side in the Z-axis direction at a position closer to the negative side in the Y-axis direction than the coil 2A. As a result, Figure 8 As shown, when viewed from the thickness direction (Y-axis direction) of the coil 2A, the protrusions 12A and 12B are arranged so as to overlap with the coil end 6 .

[0065] exist Figure 3In the illustrated embodiment, the bent portion 8 is bent at 90° relative to the coil side end portion 4. However, the angle of the bent portion 8 is not particularly limited, and it may be bent at an angle less than 90°. In this case, an opening portion SP2 is also formed, so a protrusion may be arranged in the opening portion SP2.

[0066] The coils 2A and 2B may have a rectangular ring shape with the length direction in the axial direction. In the coils 2A and 2B having such a shape, there are coil ends 6 disposed outside the yoke end faces 11a and 11b at the ends in the length direction. By arranging the protrusions 12A and 12B to overlap with such coil ends 6, the performance of the electromagnet 1 can be improved while suppressing the increase in the occupied space.

Claims

1. A particle beam therapy device for irradiating a body with a particle beam, wherein: The particle beam therapy device includes an electromagnet for deflecting the particle beam. The electromagnet has: a coil for generating a magnetic field for deflecting the particle beam; and A magnetic body is arranged at an opening on the inner circumference side of the coil, The magnetic body has a predetermined reference surface and has a protruding portion protruding from the reference surface.

2. The particle beam therapy device according to claim 1, characterized in that: The magnetic body has a yoke portion extending in the axial direction and extending along the beam axis of the particle beam. The reference surface is set at a yoke end surface of the yoke portion in the axial direction. The protrusion protrudes from the yoke end surface in the axial direction.

3. The particle beam therapy device according to claim 2, characterized in that: The coil has a coil end portion arranged on the outer side of the yoke end surface in the axial direction. The protrusion overlaps with the coil end when viewed in the thickness direction of the coil.

4. The particle beam therapy device according to claim 3, characterized in that: The coil has a bent portion bent in a direction intersecting the axial direction on the outer side of the yoke end surface in the axial direction, and an opening is formed in the bent portion between the beam axis and the coil end. The protrusion is disposed at the opening.

5. The particle beam therapy device according to claim 3, characterized in that: The coil has a rectangular ring shape with a length direction in the axial direction.

6. The particle beam therapy device according to claim 3, characterized in that: The coil end has an end surface disposed at the end in the axial direction. The protrusion protrudes to the end surface side of the coil end.

7. An electromagnet for deflecting a particle beam, the electromagnet comprising: a coil for generating a magnetic field for deflecting the particle beam; and A magnetic body is arranged at an opening on the inner circumference side of the coil, The magnetic body has a predetermined reference surface and has a protruding portion protruding from the reference surface.

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