Electromagnetic device and particle beam irradiation device
The electromagnet device with main and complementary coils addresses the challenge of continuous irradiation angles in particle beam therapy, enabling efficient and precise beam control with reduced leakage fields.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KK TOSHIBA
- Filing Date
- 2024-12-11
- Publication Date
- 2026-06-23
AI Technical Summary
Particle beam irradiation devices using divided electromagnets face challenges in achieving continuous irradiation angles due to limitations in beam trajectory control, resulting in incomplete coverage of the isocenter.
An electromagnet device with a configuration of first and second main coils and complementary coils, generating magnetic fields to guide particle beams in arc shapes, allowing continuous irradiation angles by selectively exciting coils based on the irradiation angle, minimizing magnetic field leakage and optimizing coil layout.
Enables continuous angle irradiation of particle beams using divided electromagnets, reducing leakage fields and enhancing design flexibility, suitable for precise particle beam therapy with reduced patient burden.
Smart Images
Figure 2026101724000001_ABST
Abstract
Description
[Technical Field]
[0001] Embodiments of the present invention relate to an electromagnet device for controlling the trajectory of a particle beam and a particle beam irradiation device using the same. [Background technology]
[0002] Particle beam irradiation devices require a large rotating gantry that rotates around the isocenter in order to irradiate the isocenter with particle beams at a continuous angle. On the other hand, there are also known techniques that irradiate the isocenter with particle beams at a continuous angle by deflecting the trajectory of the particle beams, without using such a rotating gantry. [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2021-159267 [Overview of the project] [Problems that the invention aims to solve]
[0004] The particle beam irradiation device described above, which achieves a continuous irradiation angle simply by deflecting the trajectory, requires a configuration in which the electromagnets are divided in order to reduce stored energy and leakage magnetic field. However, there was a problem in that the combination of divided electromagnets resulted in angles (particle beam trajectories) where the particle beam could not be irradiated onto the isocenter.
[0005] Embodiments of the present invention have been made in consideration of these circumstances, and aim to provide an electromagnet device and a particle beam irradiation device that use divided electromagnets to irradiate particle beams at a continuous angle. [Means for solving the problem]
[0006] In the electromagnet device according to the embodiment, a first main coil that is disposed close to a reference line where the isocenter intersects, generates a magnetic field that guides the trajectory of a particle beam that is linearly incident on the reference line at a predetermined inclination angle in an arc shape, and the emitted particle beam travels straight and irradiates the isocenter within a first angular range; a second main coil that is disposed close to the first main coil on the side opposite to the reference line, generates a magnetic field that guides the linearly incident particle beam in an arc shape, and the emitted particle beam travels straight and irradiates the isocenter within a second angular range; and a first complementary coil that is disposed on the incident or emitting side of the main coil, generates a magnetic field that guides the incident particle beam in an arc shape, and the emitted particle beam travels straight and irradiates the isocenter within a first blank range that is not covered by the first angular range and the second angular range.
Advantages of the Invention
[0007] According to an embodiment of the present invention, there are provided an electromagnet device and a particle beam irradiation device that use divided electromagnets and irradiate a particle beam at continuous angles.
Brief Description of the Drawings
[0008] [Figure 1] (A)(B)(C) An explanatory diagram showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device according to the first embodiment of the present invention. [Figure 2] An explanatory diagram showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device according to the second embodiment of the present invention. [Figure 3] (A) A cross-sectional view of the main coil in the electromagnet device according to the first and second embodiments, (B) a cross-sectional view of the same complementary coil. [Figure 4] A block diagram of a control unit that supplies an excitation current to the coil in the electromagnet device according to the first and second embodiments. [Figure 5] An explanatory diagram (part 1) showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device according to the third embodiment. [Figure 6] An explanatory diagram (part 2) showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device according to the third embodiment. [Figure 7] An explanatory diagram (part 3) showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device of the third embodiment. [Figure 8] An explanatory diagram (part 4) showing the relationship between the excited coil and the trajectory of the particle beam in the electromagnet device of the third embodiment. [Figure 9] A diagram showing the configuration of a particle beam irradiation apparatus according to an embodiment of the present invention. [Modes for carrying out the invention]
[0009] (First Embodiment) Hereinafter, embodiments of the present invention will be described based on the attached drawings. Figures 1(A), (B), and (C) show the electromagnet device 10A(10) of the first embodiment of the present invention, with excited coils P(P1,P2), Q a# and the orbit R(R) of particle beam 17 A ,R B ,R C This is an explanatory diagram showing the relationship between the two components. Thus, the electromagnet device 10A of the first embodiment comprises a first main coil P1, a second main coil P2, and a first complementary coil Q a# It is equipped with the following features.
[0010] As shown in Figure 1(A), the first main coil P1 is positioned close to the reference line 16 where the isocenters 15 intersect. The first main coil P1 then controls the trajectory R of the particle beam 17 that is incident linearly on the reference line 16 at a predetermined inclination angle φ. A A magnetic field B1 (Figure 3(A)) is generated that guides the particle beam in an arc shape. The particle beam 17 emitted from the first main coil P1 then travels in a straight line and irradiates the isocenter 15 in a first angular range (0 < θ < θ1).
[0011] As shown in Figure 1(B), the second main coil P2 is positioned close to the first main coil P1 on the opposite side of the reference line 16. The second main coil P2 generates a magnetic field B2 (Figure 3(A)) that guides the linearly incident particle beam 17 into an arc shape. The particle beam 17 emitted from the second main coil P2 travels in a straight line and irradiates the isocenter 15 in the second angular range (θ1+δ1<θ<θ2).
[0012] As shown in FIG. 1(C), the first complementary coil Q a# is arranged on the incident side of the second main coil P2. And the first complementary coil Q a# generates a magnetic field B a (FIG. 3(B)) that guides the incident particle beam 17 in an arc shape. And the particle beam 17 emitted from the first complementary coil Q a# travels straight and irradiates the isocenter 15 in a first blank range (θ1 < θ < θ1 + δ1) that is not covered in the first angular range (0 < θ < θ1) and the second angular range (θ1 + δ1 < θ < θ2).
[0013] All the main coils P (P1, P2) and all the complementary coils Q are arranged adjacent to each other in the X - Y plane such that the magnetic field direction is along the Z - axis in the figure. Here, when the reference line 16 is taken as the X - axis and the inclination angle φ at the deflection starting point 18 of the particle beam 17 is set to zero, the rectangular coordinates are set so that the particle beam 17 enters the isocenter 15.
[0014] And the range of the inclination angle φ is set such that the particle beam 17 output from the deflection starting point 18 can enter the first main coil P1, the second main coil P2, and the first complementary coil Q a# . Also, the inclination angle φ is uniquely determined by setting the irradiation angle θ to the isocenter 15. The particle beam 17 that draws a linear trajectory R at a predetermined inclination angle φ is deflected by the Lorentz force applied by the magnetic field B generated by the coils P, Q corresponding to this inclination angle φ, draws an arc trajectory in the X - Y plane, and converges to the isocenter 15.
[0015] Thus, when obtaining a desired irradiation angle θ, only one of the main coils P (P1, P2) and the complementary coil Q arranged in the passing region of the particle beam 17 is excited, and the other coils are not excited. By doing so, the magnetic field generation region can be minimized, and the leakage magnetic field from the coils P, Q can also be reduced.
[0016] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 2. Figure 2 shows the excited coil Q in the electromagnet device 10B(10) of the second embodiment of the present invention. a$ This is an explanatory diagram showing the relationship between the orbit R of particle beam 17. Note that in Figure 2, parts with the same configuration or function as those in Figure 1 are indicated by the same reference numerals, and redundant explanations are omitted.
[0017] Thus, the electromagnet device 10B of the second embodiment is the first complementary coil Q that was placed on the incident side in the first embodiment. a# Instead, a first complementary coil Q is placed on the output side of the first main coil P1. a$ This is arranged to increase the design versatility of the coil layout of the electromagnet device 10.
[0018] Figure 3(A) is a cross-sectional view of the main coils P(P1, P2) in the electromagnet devices 10(10A, 10B) according to the first and second embodiments. Figure 3(B) is a cross-sectional view of the complementary coil Q in the electromagnet devices 10(10A, 10B) according to the first and second embodiments. These main coils P and complementary coil Q may be normal conducting coils or superconducting coils. When superconducting coils are used for the main coils P and complementary coil Q, they are housed in a cryostat whose interior is kept at an extremely low temperature.
[0019] As shown in Figure 3, each of the main coil P(P1, P2) and the complementary coil Q is configured with magnetic poles consisting of two windings facing each other at a constant magnetic pole spacing d. In electromagnets, setting a narrower magnetic pole spacing d allows for more efficient generation of the magnetic field B. For this reason, it is desirable that the magnetic pole spacing d be narrow enough to have the necessary margin relative to the diameter size of the particle beam 17. For this reason, in the electromagnet device 10, it is desirable that the magnetic pole spacing d of the main coil P(P1, P2) and the complementary coil Q be sufficiently narrow to correspond to the diameter size of the particle beam 17 and be configured to be the same for all of them.
[0020] Furthermore, each of the main coils P(P1,P2) and the complementary coil Q has wire wound around a high-permeability yoke (iron core, etc.), and a high-intensity magnetic field B can be generated in the gap between the opposing yokes. The higher the intensity of these magnetic fields B, the smaller the radius of the circular trajectory of the particle beam 17 can be, and the smaller the area of the main coils P(P1,P2) and the complementary coil Q can be. Therefore, if the main coils P(P1,P2) and the complementary coil Q are made of superconducting coils, the intensity of the magnetic field B can be further increased, and the area can be further reduced.
[0021] Figure 4 is a block diagram of the control unit 20 that supplies excitation current to coils P1, P2, and Q in the electromagnet devices 10 (10A, 10B) according to the first and second embodiments. The control unit 20 includes a power supply 21 that outputs power, and a supply unit 22 that selects and supplies excitation current, with power adjusted according to the irradiation angle θ, to one of the corresponding coils P1, P2, and Q.
[0022] There are two main methods for adjusting the power to the excitation current in the supply unit 22. The first is to form a main coil P (P1, P2) and a complementary coil Q that are responsible for the angular range of the irradiation angle θ, so that the excitation current controlled by the control unit 20 remains constant (unchanged) regardless of the set value of the irradiation angle θ to the isocenter 15.
[0023] In other words, under the condition that the strength of the magnetic field B is constant, the shapes of coils P and Q are designed such that, with respect to the irradiation angle θ of the angular range they are responsible for, the tangent from the incident end of the arc-shaped trajectory R in each coil P and Q intersects the deflection starting point 18, and the tangent at the exit end intersects the isocenter 15.
[0024] The second method for adjusting the excitation current is that the control unit 20 changes the excitation current of the main coil P (P1, P2) and the complementary coil Q, depending on the set value of the irradiation angle θ to the isocenter 15. In this case, since the strength of the magnetic field B changes in accordance with the irradiation angle θ, the coils P and Q can be designed in any shape.
[0025] In this second method of adjusting the excitation current, the supply unit 22 further has the function of adjusting the amount of excitation current supplied to each of the coils P1, P2, and Q according to the irradiation angle θ of the particle beam 17. In this way, the control unit 20 can variably supply the excitation current to each of the coils P1, P2, and Q in accordance with the set value of the irradiation angle θ. In other words, by making the strength of the magnetic field B through which the particle beam 17 passes differ according to the irradiation angle θ, the curvature of the arc-shaped trajectory Q in each of the coils P1, P2, and Q can be set arbitrarily. This contributes to improving the design freedom of the main coils P(P1, P2) and the complementary coil Q.
[0026] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Figures 5 to 8. Figures 5 to 8 show the excited coil P(P3, P4) and the trajectory R(R) of the particle beam 17 in the electromagnet device 10C(10) of the third embodiment. D ,R E ,R F ,R G This is an explanatory diagram showing the relationship with ). Thus, the electromagnet device 10C of the third embodiment has the configuration of the first embodiment described above, plus a third main coil P3, a fourth main coil P4, and a second complementary coil Q. b# And the third complementary coil Q c$ The configuration further includes the addition of the above. Note that parts in Figures 5 to 8 that have the same configuration or function as those in Figures 1 and 2 are indicated by the same reference numerals, and redundant explanations are omitted.
[0027] As shown in Figure 5, the third main coil P3 is positioned on the opposite side from the first main coil P1 and close to the second main coil P2. The third main coil P3 generates a magnetic field B that guides the trajectory R of the linearly incident particle beam 17 into an arc shape. The particle beam 17 emitted from the third main coil P3 travels in a straight line and irradiates the isocenter 15 in the third angular range (θ2 + δ2 < θ < θ3).
[0028] As shown in Figure 6, the fourth main coil P4 is located on the opposite side of the second main coil P2 and close to the third main coil P3. The fourth main coil P4 generates a magnetic field B that guides the trajectory R of the linearly incident particle beam 17 into an arc shape. The particle beam 17 emitted from the fourth main coil P4 travels in a straight line and irradiates the isocenter 15 in the fourth angular range (θ3 + δ3 < θ < θ4).
[0029] As shown in Figure 7, the second complementary coil Q b# It is located on the incident side of the fourth main coil P4. And the second complementary coil Q b# This generates a magnetic field B that guides the incident particle beam 17 in an arc shape. Then the second complementary coil Q b# The particle beam 17 emitted from the device travels in a straight line and irradiates the isocenter 15 in the second blank area (θ2 < θ < θ2 + δ2). This second blank area (θ2 < θ < θ2 + δ2) is an area not covered by the second angular area (θ1 + δ1 < θ < θ2) and the third angular area (θ2 + δ2 < θ < θ3).
[0030] As shown in Figure 8, the third complementary coil Q c$ It is located on the exit side of the third main coil P3. And the third complementary coil Q c$ This generates a magnetic field B that guides the incident particle beam 17 in an arc shape. Then the third complementary coil Q c$ The particle beam 17 emitted from the device travels in a straight line and irradiates the isocenter 15 in the third blank area (θ3 < θ < θ3 + δ3). This third blank area (θ3 < θ < θ3 + δ3) is an area not covered by the third angular area (θ2 + δ2 < θ < θ3) and the fourth angular area (θ3 + δ3 < θ < θ4).
[0031] Referring to Figures 5 to 8, the second embodiment shows a configuration in which two main coils P3 and P4 are added to the two main coils P1 and P2 of the first embodiment. However, there is no limit to the number of additional main coils P from the configuration of the first embodiment, and the number of additional main coils P and their corresponding complementary coils Q can be generalized as follows, with m (m=1,2…M) being a natural number.
[0032] That is, the m+2th main coil P m+2 This is the mth main coil P m On the opposite side is the (m+1)th main coil P m+1 It is positioned in close proximity to the m+2th main coil P. m+2 This generates a magnetic field B that guides the orbit R of the linearly incident particle beam 17 into an arc shape. Then the m+2 main coil P m+2 The particle beam 17 emitted from the source travels in a straight line and passes through the isocenter 15 within the m+2 angular range (θ m+1 +δ m+1 <θ<θ m+2 Irradiate with )
[0033] Furthermore, the (m+1)th complementary coil Q is positioned on the incident or exit side of the main coil P. The (m+1)th complementary coil Q generates a magnetic field B that guides the incident particle beam 17 in an arc shape. The particle beam 17 exiting from the (m+1)th complementary coil Q travels in a straight line and passes through the isocenter 15 in the (m+1)th blank area (θ m+1 <θ<θ m+1 +δ m+1 Irradiate in this (m+1) blank area (θ). m+1 <θ<θ m+1 +δ m+1 ) is the m+1th angular range (θ m +δ m <θ<θ m+1 ) and m+2 angle range (θ m+1 +δ m+1 <θ<θ m+2 This is an area not covered by ).
[0034] In this way, by stacking the main coil P and the complementary coil Q in multiple stages to form the electromagnet device 10C(10), the maximum value of the irradiation angle θ to the isocenter 15 can be brought close to 90°.
[0035] Figure 9 is a diagram showing the configuration of a particle beam irradiation apparatus 30 according to an embodiment of the present invention. Particle beam therapy is performed to treat malignant tumors such as cancer by irradiating them with a particle beam 17 accelerated to high energy. With this particle beam therapy, it is possible to destroy only the diseased tissue with pinpoint accuracy without damaging normal tissue, so the burden on the patient is less than with surgical or chemical treatments, and it is also possible to expect earlier social reintegration after treatment.
[0036] The electromagnet device 10D used in the particle beam irradiation device 30 consists of two pairs of electromagnet devices 10 (10A~10C) from the first embodiment (Figure 1), the second embodiment (Figure 2), or the third embodiment (Figure 5), arranged symmetrically with respect to the reference line 16 as the central axis. The magnetic field directions of the coils located symmetrically across the reference line 16 are opposite to each other.
[0037] In Figure 9, the isocenter 15 is set as the origin of the coordinate axes, the reference line 16 is the X-axis, the direction of the magnetic field B generated by coils P and Q is the Z-axis, and the direction perpendicular to the X-axis and Z-axis is the Y-axis.
[0038] In treatment using particle beam 17, a mobile bed (not shown) is set up so that the target (lesion tissue) of the patient, who is lying on their side along the Z-axis, coincides with the isocenter 15. Then, as necessary, the mobile bed is moved in the direction along each axis or in the rotational direction of the Y-axis to irradiate the patient with the particle beam 17. In treatment using particle beam 17, a mobile bed (not shown) is set up so that the target (lesion tissue) of the patient, who is lying on their side along the Z-axis, coincides with the isocenter 15. Then, as necessary, the mobile bed is moved in the direction along each axis or in the rotational direction of the Y-axis to irradiate the patient with the particle beam 17.
[0039] The particle beam irradiation apparatus 30 comprises an ion source 33 that generates a particle beam 17, an accelerator 31 that accelerates the particle beam 17 to generate a high-energy particle beam 17, a beam transport path 32 that transports the particle beam 17 extracted from the accelerator 31, and an electromagnet device 10 that deflects the particle beam 17. Furthermore, a bed (not shown) is provided to support the target to which the particle beam 17 is irradiated so that it is located in the isocenter 15.
[0040] The accelerator 31 is broadly classified into a linear accelerator 35 and a circular accelerator 36. The particle beam 17 generated in the ion source 33 is accelerated stepwise in the linear accelerator 35 and the circular accelerator 36 to become the particle beam 17. Then, the particle beam 17 that has circled the circular accelerator 36 and reached the required energy level for irradiation has its direction of travel changed from its orbit and is extracted into the beam transport path 32.
[0041] The particle beams 17 generated by the ion source 33 include carbon, helium, oxygen, neon, silicon, and argon. Examples of ion sources 33 include high-frequency (including microwave) irradiation types such as ECR (Electron Cyclotron Resonance) ion sources and PIG (Penning Ionization Gauge) ion sources, as well as laser irradiation types. However, the ion source 33 is not limited to these; any ion source capable of efficiently generating the particle beams 17 may be used as appropriate.
[0042] The linear accelerator 35 arranges multiple accelerating electric fields, each with opposing electric field components, in a straight line, and repeatedly reverses the direction of the electric field at a high frequency, thereby accelerating the particle beam 17 passing through the accelerating electric field in only one direction. Specifically, the linear accelerator 35 consists of a radio frequency quadrupole (RFQ) linear accelerator and a drift tube linear accelerator (DTL).
[0043] The circular accelerator 36 is a synchrotron or cyclotron, and consists of a high-frequency accelerating cavity 39 that accelerates the particle beam 17 incident from the linear accelerator 35 using high-frequency power, multiple deflection magnets 38 that bend the particle beam 17 with a magnetic field to put it into orbit, multiple quadrupole magnets 37 that generate a magnetic field that diverges and converges the orbiting particle beam 17 to keep it in orbit, and an emitter 34 that emits the particle beam 17 from the circular accelerator 36 into the beam transport path 32.
[0044] The circular accelerator 36, configured in this way, can accelerate the particle beam 17, which is injected from the linear accelerator 35 at low energy, to 70-80% of the speed of light while orbiting it, thereby increasing its energy to high levels.
[0045] According to at least one embodiment of the electromagnet device described above, by arranging a complementary coil on the incident or exit side of the main coil, it becomes possible to provide an electromagnet device that can irradiate particle beams at a continuous angle using divided electromagnets.
[0046] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]
[0047] 10(10A,10B,10C,10D,10E)...Electromagnet device, 11...Magnetic field region, 15...Isocenter, 16...Reference line, 17...Particle beam, 18...Bending origin, 20...Control unit, 21...Power supply, 22...Supply unit, 30...Particle beam irradiation device, 31...Accelerator, 32...Beam transport path, 33...Ion source, 34...Exiter, 35...Linear accelerator, 36...Circular accelerator, 37...Quadrupole electromagnet, 38...Bending electromagnet, 39...High-frequency accelerating cavity, B...Magnetic field, d...Pole spacing, P...Main coil, P1(P)...First main coil, P2(P)...Second main coil, Q...Complementary coil, R...Orbit, θ...Irradiation angle, φ...Inclination angle.
Claims
1. A first main coil is positioned close to a reference line where the isocenters intersect, and generates a magnetic field that guides the trajectory of a particle beam incident linearly with respect to the reference line at a predetermined inclination angle in an arc shape, so that the emitted particle beam travels in a straight line and irradiates the isocenter within a first angular range. A second main coil is positioned on the opposite side of the reference line and close to the first main coil, generating a magnetic field that guides the linearly incident particle beam in an arc shape, so that the emitted particle beam travels in a straight line and irradiates the isocenter in a second angular range, An electromagnet device comprising: a first complementary coil positioned on the incident or exit side of the main coil, which generates a magnetic field that guides the incident particle beam in an arc shape, and which causes the exited particle beam to travel in a straight line and irradiate the isocenter in a first blank area not covered by the first and second angular ranges.
2. In the electromagnet device according to claim 1, The m+2 main coil is positioned on the opposite side of the m-th main coil (m = 1, 2...M) and close to the m+1th main coil, generating a magnetic field that guides the trajectory of the linearly incident particle beam into an arc shape, and the emitted particle beam travels in a straight line and irradiates the isocenter within the m+2 angle range, An electromagnet device comprising: an m+1 complementary coil positioned on the incident or exit side of the main coil, which generates a magnetic field that guides the incident particle beam in an arc shape, and causes the exited particle beam to travel in a straight line and irradiate the isocenter in an m+1 angular range and an m+1 blank range not covered by the m+2 angular range.
3. In the electromagnet device according to claim 1 or claim 2, An electromagnet device consisting of two pairs, arranged symmetrically with respect to the aforementioned reference line as the central axis.
4. In the electromagnet device according to claim 1 or claim 2, An electromagnet device that changes the excitation current of the main coil and the complementary coil, respectively, in relation to the irradiation angle to the isocenter.
5. In the electromagnet device according to claim 1 or claim 2, An electromagnet device in which the main coil and the complementary coil are formed such that the excitation current remains constant with respect to the irradiation angle to the isocenter.
6. In the electromagnet device according to claim 1 or claim 2, An electromagnet device in which the magnetic pole spacing of the main coil and the complementary coil that generate the magnetic field is all the same.
7. The electromagnet device according to claim 3, An ion source that generates particle beams, An accelerator that accelerates the aforementioned particle beam to a high energy, A beam transport path for transporting the particle beam extracted from the accelerator, A particle beam irradiation apparatus comprising: a support unit that supports a target to be irradiated by the particle beam so that it is positioned at the isocenter.