Particle beam therapy apparatus, deflection magnet apparatus, and particle beam adjustment method

Abstract

To provide a particle beam therapy apparatus, a deflection magnet apparatus, and a particle beam adjustment method capable of effectively obtaining deflection force regardless of the deflection direction of a particle beam B.SOLUTION: According to a particle beam therapy apparatus 1, a deflection magnet 45 that deflects a particle beam B in a transport section 20 is rotatable about a beam axis CL of the particle beam B. In this case, the deflection magnet 45 can be rotated about the beam axis CL in accordance with the desired deflection direction of the particle beam B. Therefore, the direction in which the deflection force of the deflection magnet 45 can be effectively obtained can be aligned with the desired deflection direction of the particle beam B. Accordingly, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam B.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a particle beam therapy apparatus, a deflection magnet apparatus, and a particle beam adjustment method.

Background Art

[0002] Conventionally, as a particle beam therapy apparatus for treating a patient's affected part by irradiating the affected part with a particle beam, for example, the apparatus described in Patent Document 1 is known. In the particle beam therapy apparatus described in Patent Document 1, the particle beam is irradiated from an irradiation unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the particle beam therapy apparatus has a transport unit that transports the particle beam from an accelerator to an irradiation unit. For such a transport unit, a deflection magnet apparatus for deflecting the particle beam is provided. Here, the deflection magnet apparatus may have a deflection magnet that is adjusted in the X-axis direction and a deflection magnet that is adjusted in the Y-axis direction. By superimposing the deflection forces by such two-axis deflection magnets, the particle beam is deflected and adjusted in a desired direction. However, in a conventional particle beam therapy apparatus, depending on the deflection angle, the deflection force related to the superposition may become small. Therefore, there are cases where an effective deflection force cannot be obtained depending on the angle.

[0005] Therefore, an object of the present invention is to provide a particle beam therapy apparatus, a deflection magnet apparatus, and a particle beam adjustment method that can effectively obtain a deflection force regardless of the deflection direction of the particle beam.

Means for Solving the Problems

[0006] A particle beam therapy apparatus according to an aspect of the present invention includes an irradiation unit that irradiates a subject with a particle beam, a transport unit that transports the particle beam, and a deflection magnet device having a deflection magnet that deflects the particle beam of the transport unit. The deflection magnet is rotatable around the beam axis of the particle beam.

[0007] According to the particle beam therapy apparatus, the deflection magnet that deflects the particle beam of the transport unit is rotatable around the beam axis of the particle beam. In this case, the deflection magnet can be rotated around the beam axis in accordance with the desired deflection direction of the particle beam. Therefore, the direction in which the deflection force of the deflection magnet can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam.

[0008] The deflection magnet device may have a pair of deflection magnets, and the pair of deflection magnets may be rotatable around the beam axis of the particle beam while being fixed to each other in the rotation direction. When the deflection forces of the pair of deflection magnets are superimposed, an angle at which the deflection force related to the superposition can be ensured to be large and an angle at which the deflection force becomes small are formed. By rotating the pair of deflection magnets around the beam axis of the particle beam, the direction in which a large deflection force can be ensured can be aligned with respect to the desired deflection direction of the particle beam. Therefore, the deflection force of the pair of deflection magnets can be ensured to be large regardless of the direction of the particle beam deflection around the beam axis. Here, since the pair of deflection magnets are fixed to each other in the rotation direction, the rotation angle can be adjusted more easily compared to the case where the rotation angles of the pair of deflection magnets are adjusted individually.

[0009] The deflection magnet device has a pair of deflection magnets, and one of the pair of deflection magnets may be rotatable around the beam axis of the particle beam in a state independent of the other. When the deflection forces of the pair of deflection magnets are superimposed, an angle at which the deflection force related to the superposition can be ensured to be large and an angle at which the deflection force becomes small can be formed. By rotating the pair of deflection magnets around the beam axis of the particle beam, it is possible to align the direction in which a large deflection force can be ensured with respect to the desired deflection direction of the particle beam. Therefore, regardless of the direction of the deflection of the particle beam around the beam axis, the deflection force of the pair of deflection magnets can be ensured to be large. Here, when the deflection force of one deflection magnet and the deflection force of the other deflection magnet are superimposed, there is a direction component in which the deflection forces of both cancel each other out. On the other hand, one of the pair of deflection magnets is rotatable around the beam axis of the particle beam in a state independent of the other. Therefore, the relative rotation angle of the mutual deflection magnets can be adjusted so that the direction components that cancel each other out are reduced. Thereby, the energy for the deflection magnet device can be effectively utilized.

[0010] The deflection magnet device has one deflection magnet, and the one deflection magnet may be rotatable around the beam axis of the particle beam. In this case, the number of magnets of the deflection magnet device can be reduced.

[0011] The particle beam treatment device may include an adjustment mechanism for adjusting the rotation angle of the deflection magnet with respect to the beam axis. In this case, by using the adjustment mechanism, the rotation angle of the deflection magnet can be easily and accurately adjusted.

[0012] The adjustment mechanism may include a drive unit for rotating the deflection magnet with respect to the beam axis. In this case, the rotation angle of the deflection magnet can be adjusted without manual operation by an operator.

[0013] The beam axis extends in the horizontal direction, and the direction of the magnetic field of the deflection magnet may be inclined with respect to the vertical direction.

[0014] The particle beam therapy apparatus further includes a control unit that controls the deflection magnet device. The control unit may perform a first adjustment of the particle beam by rotating the deflection magnet. In this case, the control unit can roughly adjust the direction of the deflection force by rotating the deflection magnet itself.

[0015] The control unit may perform a second adjustment of the particle beam by electrically controlling the deflection magnet. In this case, the control unit can finely adjust the direction of the deflection force.

[0016] The deflection magnet device has a pair of deflection magnets. In the first adjustment, the control unit may relatively rotate each deflection magnet. In this case, the control unit can also adjust the angle between the pair of deflection magnets in the first adjustment.

[0017] A deflection magnet device according to one aspect of the present invention is a deflection magnet device including a deflection magnet that deflects a particle beam, and the deflection magnet may be rotatable around the beam axis of the particle beam.

[0018] According to the deflection magnet device, by providing it at a location where the particle beam passes, the particle beam can be deflected in a desired direction. At this time, the deflection magnet can be rotated around the beam axis in accordance with the desired deflection direction of the particle beam. Therefore, the direction in which the deflection force of the deflection magnet can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam.

[0019] A particle beam adjustment method according to one aspect of the present invention is a particle beam adjustment method provided for a transport unit that transports a particle beam and adjusts a deflection magnet that deflects the particle beam of the transport unit, and adjusts the particle beam by rotating the deflection magnet around the beam axis of the particle beam.

[0020] According to the particle beam adjustment method, by providing a deflection magnet at the location where the particle beam passes, the particle beam can be deflected in a desired direction. At this time, the deflection magnet is rotated around the beam axis in accordance with the desired deflection direction of the particle beam. Therefore, the direction in which the deflection force of the deflection magnet can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam.

Effects of the Invention

[0021] According to the present invention, it is possible to provide a particle beam therapy apparatus, a deflection magnet apparatus, and a particle beam adjustment method capable of effectively obtaining a deflection force regardless of the deflection direction of the particle beam.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0023] Hereinafter, a particle beam therapy apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0024] FIG. 1 is a schematic configuration diagram showing a particle beam therapy apparatus 1 according to an embodiment of the present invention. The particle beam therapy apparatus 1 is a system used for cancer treatment and the like by radiation therapy. The particle beam therapy apparatus 1 may be an irradiation apparatus according to a scanning method. The scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, or the like may be adopted. The particle beam therapy apparatus 1 includes an accelerator 3 that accelerates charged particles generated by an ion source device and emits them as a particle beam, an irradiation unit 2 that irradiates the particle beam to a patient 15, and a transport unit 20 that transports the particle beam emitted from the accelerator 3 to the irradiation unit 2. The irradiation unit 2 is attached to a rotating gantry 17 provided so as to surround a treatment table 6. The irradiation unit 2 is rotatable around the treatment table 6 on which the patient 15 is placed, with the central axis as the rotation center by the rotating gantry 17.

[0025] The accelerator 3 is a device that accelerates charged particles and emits a particle beam B having a preset energy. Examples of the accelerator 3 include a cyclotron, a synchrocyclotron, and the like. The particle beam B generated by the accelerator 3 is transported to the irradiation unit 2 by the transport unit 20. The transport unit 20 connects the accelerator 3 and the irradiation unit 2 and transports the particle beam B emitted from the accelerator 3 to the irradiation unit 2. The detailed configuration of the transport unit 20 will be described later.

[0026] The irradiation unit 2 irradiates a tumor in the body of the patient 15 with a particle beam. The particle beam is obtained by accelerating charged particles at high speed, and examples thereof include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. Specifically, the irradiation unit 2 is a device that irradiates a tumor with a particle beam emitted from an accelerator 3 that accelerates charged particles generated by an ion source (not shown) and transported by the transport unit 20. The irradiation unit 2 has a scanning electromagnet. The irradiation unit 2 may further include a quadrupole electromagnet, a monitor, a degrader, and the like. The scanning electromagnet changes the magnetic field between a pair of electromagnets according to the current supplied from the control unit and scans the particle beam passing between the electromagnets. The scanning electromagnet scans the particle beam B so that the particle beam is irradiated in a scan pattern planned in advance by a treatment planning device.

[0027] The control unit 7 (see FIG. 2) is composed of, for example, a CPU, a ROM, a RAM, etc. Based on the detection results output from each monitor, this control unit 7 controls the accelerator 3, the transport unit 20, the irradiation unit 2, etc.

[0028] Moreover, the control unit 7 of the particle beam therapy apparatus 1 is connected to a treatment planning apparatus that performs a treatment plan for particle beam therapy. The treatment planning apparatus measures the tumor of the patient 15 with a CT or the like before treatment, and plans the dose distribution (the dose distribution of the particle beam to be irradiated) at each position of the tumor. Specifically, the treatment planning apparatus creates a scan pattern for the tumor. The treatment planning apparatus transmits the created scan pattern to the control unit 7. In the scan pattern created by the treatment planning apparatus, it is planned how the particle beam draws what kind of scanning path at what kind of scanning speed.

[0029] When performing irradiation of the particle beam by the scanning method, the tumor is virtually divided into a plurality of layers, and in one layer, the particle beam is scanned and irradiated according to the scanning path determined in the treatment plan. And after the irradiation of the particle beam in the one layer is completed, the irradiation of the particle beam in the next adjacent layer is performed.

[0030] The transport unit 20 has a beam duct 21 (transport unit) that transports the particle beam B and a plurality of electromagnets. The transport unit 20 includes a BTS (Beam Transport System) system 20A, an ESS (Enery Selection System) system 20B, and a GTS (Gantry Transport System) system 20C. The BTS system 20A is a system that transports the particle beam B. The ESS system 20B is a system that selects the energy of the particle beam B. The GTS system 20C is a transport system of the particle beam B in the rotating gantry 17. The transport unit 20 includes a deflection magnet device 30 in each system.

[0031] The components in each system will be described. However, the components shown in FIG. 1 are merely examples and may be changed as appropriate. The BTS system 20A mainly includes a deflection magnet device 30A and converging electromagnets 31, 31. The deflection magnet device 30A has a deflection magnet 40. The deflection magnet 40 is an electromagnet that deflects the particle beam transported in the beam duct 21. In the present embodiment, the deflection magnet device 30A includes a pair of deflection magnets 40, enabling the adjustment of the particle beam in two axes. However, as will be described later, the deflection magnet device 30A may have one deflection magnet 40. The converging electromagnet 31 is an electromagnet that converges the particle beam.

[0032] The ESS system 20B includes a degrader 32 and a collimator device 33. The degrader 32 reduces the energy of the passing particle beam B and adjusts the range of the particle beam B. The collimator device 33 is a member that collimates the particle beam.

[0033] The GTS system 20C includes converging electromagnets 31, a deflection magnet device 30B, converging electromagnets 31, and a deflection magnet device 30C. The deflection magnet device 30B includes a deflection magnet 41 that bends the particle beam B passing through the ESS system 20B to the outer peripheral side in the rotating gantry 17. The deflection magnet device 30C includes a deflection magnet 42 that bends the particle beam from the outer peripheral side to the inner peripheral side irradiation portion 2 of the rotating gantry 17.

[0034] Here, the deflection magnets 41, 42 are electromagnets for bending the particle beam B to such an extent that it is necessary to change the angle of the beam duct 21. The deflection magnets 41, 42 can bend the particle beam B to a desired angle. On the other hand, the deflection magnet 40 deflects and adjusts the particle beam B within the range where the angle of the beam duct 21 can be maintained. Although not particularly limited, the angle range deflected by the deflection magnet 40 may be 45° or less, or 90° or less.

[0035] Next, with reference to FIGS. 2 and 3, the detailed configuration of the deflection magnet device 30 will be described. In the following description, the direction in which the particle beam B travels is defined as the Z-axis direction. The direction orthogonal to the Z-axis direction is defined as the X-axis direction, and the direction orthogonal to the Z-axis direction and the X-axis direction is defined as the Y-axis direction. The central axis of the beam duct is defined as the beam axis CL of the particle beam B. FIG. 2 is a schematic view of the deflection magnet device 30 as seen from the X-axis direction. The deflection magnet device 30 shown in FIG. 2 includes a deflection magnet 45A and a deflection magnet 45B. FIG. 3(a) is a view of the deflection magnet 45A as seen from the Z-axis direction. FIG. 3(b) is a view of the deflection magnet 45B as seen from the Z-axis direction. FIG. 3(c) is a diagram for explaining the deflection force by the deflection magnet 45A and the deflection force by the deflection magnet 45B. Note that the deflection magnets 45A and 45B shown in FIG. 3 are in the "reference posture". Note that the direction of the deflection force F due to the deflection action of the deflection magnets 45A and 45B is defined by the direction of the Lorentz force determined by the direction of the magnetic field on the beam axis CL and the direction of the particle beam B. Here, it is assumed that the particle beam B is traveling on the beam axis CL.

[0036] As shown in FIGS. 3(a) and 3(b), the deflection magnets 45A and 45B include magnetic poles 46 and coils 47. The magnetic poles 46 include a rectangular annular main body portion 48 surrounding the beam axis CL and a pair of protruding portions 49. The main body portion 48 is arranged such that its central axis coincides with the beam axis CL. As shown in FIG. 3(a), in the reference posture of the deflection magnet 45A, the pair of protruding portions 49 extend from the wall portion of the main body portion 48 facing the X-axis direction toward the beam axis CL. The pair of protruding portions 49 are arranged to face each other in the X-axis direction while sandwiching the beam duct 21 from both sides in the X-axis direction. Coils 47 are provided on each of the protruding portions 49. Thereby, in the reference posture, the deflection magnet 45A generates a magnetic field Ba in the X-axis direction. Thereby, the deflection magnet 45A generates a deflection force Fa in the Y-axis direction.

[0037] As shown in FIG. 3(b), in the reference posture of the deflection magnet 45B, the pair of protrusions 49 extend from the wall portion of the main body portion 48 facing the Y-axis direction toward the beam axis CL. The pair of protrusions 49 are arranged so as to face each other in the Y-axis direction with the beam duct 21 sandwiched from both sides in the Y-axis direction. A coil 47 is provided on each protrusion 49. Thereby, in the reference posture, the deflection magnet 45B generates a magnetic field Bb in the X-axis direction. Thereby, the deflection magnet 45B generates a deflection force Fb in the X-axis direction.

[0038] As shown in Fig. 3(c), in the reference posture, the deflection force Fa and the deflection force Fb are perpendicular to each other at 90°. When the magnitudes of the deflection forces Fa and Fb are equal, the resultant deflection force Ft obtained by superimposing the two acts in a direction making an angle of 45° with respect to the X-axis direction. In Fig. 3, the direction of the deflection force Fb is on the positive side of the X-axis direction, but it can be changed to the negative side of the X-axis direction by changing the direction of the current flowing through the coil 47. The direction of the deflection force Fa is on the positive side of the Y-axis direction, but it can be changed to the negative side of the Y-axis direction by changing the direction of the current flowing through the coil 47. Also, the magnitudes of the deflection forces Fa and Fb can be changed by adjusting the magnitude of the current flowing through the coil 47. The deflection magnet device 30 can adjust the magnitude and direction of the resultant deflection force Ft by adjusting the magnitudes and directions of the deflection forces Fa and Fb. The direction of the resultant deflection force Ft can be adjusted by 360° around the beam axis CL. However, when changing the direction of the resultant deflection force Ft while maintaining the reference posture, when the magnitudes of the deflection forces Fa and Fb are maximized, it becomes maximum when the angle θ1 is 45°, 135°, 225°, or 315°. In some cases, the resultant deflection force Ft at this time may be referred to as the "maximum deflection force Fmax". Note that the angle θ1 of the resultant deflection force Ft is an angle based on the positive side of the X-axis direction. When the resultant deflection force Ft is set to an angle other than the above angles, it is necessary to reduce either the deflection force Fa or Fb. Therefore, when the angle θ1 is other than the above angles, the magnitude of the resultant deflection force Ft is smaller than the magnitude of the maximum deflection force. When the angle θ1 is 0°, the deflection force Fa becomes 0, so the resultant deflection force Ft has only the magnitude of the deflection force Fb. When the angle θ1 is 90°, the deflection force Fb becomes 0, so the resultant deflection force Ft has only the magnitude of the deflection force Fa. Therefore, in the case of a structure (referred to as a comparative example) in which the angles of the deflection magnets 45A and 45B around the beam axis CL cannot be changed from the reference posture, outside of "angle θ1 = 45°, 135°, 225°, 315°", the maximum value of the resultant deflection force Ft becomes smaller than the maximum deflection force Fmax. Fig. 3(c) shows the adjustment range AE of the resultant deflection force Ft. Note that the adjustment range AE according to the comparative example is fixed around the beam axis CL.

[0039] In contrast, as shown in FIG. 4, in the deflection magnet device 30 according to the present embodiment, the deflection magnets 45A and 45B are rotatable around the beam axis CL of the particle beam B. The deflection magnets 45A and 45B rotate around the beam axis CL as the center of rotation. Thereby, the deflection magnets 45A and 45B can change the directions of the deflection forces Fa and Fb with respect to the reference posture.

[0040] As a configuration for rotating the deflection magnets 45A and 45B, the configuration shown in FIG. 4 may be adopted. As shown in FIGS. 4(a) and 4(b), the pair of deflection magnets 45A and 45B may be rotatable around the beam axis CL of the particle beam B while being fixed to each other in the rotation direction. That is, the pair of deflection magnets 45A and 45B rotate around the beam axis CL in an integrated state with each other. In this case, the direction and rotation angle of the rotation direction RDa of the deflection magnet 45A and the direction and rotation angle of the rotation direction RDb of the deflection magnet 45B are the same. The deflection force Fa by the deflection magnet 45A acts in a direction rotated by the rotation angle with respect to the Y-axis direction. The deflection force Fb by the deflection magnet 45B acts in a direction rotated by the rotation angle with respect to the X-axis direction. However, the relationship in which the deflection force Fa and the deflection force Fb are perpendicular to each other is maintained regardless of the rotation angle and direction.

[0041] The method for fixing the pair of deflection magnets 45A and 45B to each other in the rotation direction is not particularly limited. For example, the main body 48 of the deflection magnet 45A and the main body 48 of the deflection magnet 45B may be fixed to each other by a predetermined connecting member or the like. For example, the deflection magnets 45A and 45B may be fixed to a common base member. Alternatively, pins may be inserted into the main bodies 48 of the deflection magnets 45A and 45B for fixing.

[0042] In this case, as shown in Fig. 4(c), the direction of the deflecting force Fa can be changed by an angle θ2 from the Y-axis direction, and the direction of the deflecting force Fb can be changed by an angle θ2 from the X-axis direction. In this case, the maximum deflecting force Fmax can be generated at angles other than "angle θ1 = 45°". If the adjustment range of the rotation angle θ2 is at least 90°, by adjusting the directions of the deflecting forces Fa and Bb, the maximum deflecting force Fmax can be generated in the range of "angle θ1 = 0° to 360°". That is, the deflecting magnet device 30 can adjust the magnitude of the combined deflecting force Ft in the range of "0 to the maximum deflecting force Fmax" over the entire circumference around the beam axis CL. Therefore, the adjustment range AE is set not to be fixed around the beam axis CL but to rotate around the beam axis CL. However, when the adjustment range of the particle beam B is limited to a certain extent, the adjustment range of the rotation angle θ2 only needs to be greater than 0° and may be less than 90°.

[0043] As a configuration for rotating the deflecting magnets 45A and 45B, the configuration shown in Fig. 5 may be adopted. As shown in Figs. 5(a) and 5(b), one of the pair of deflecting magnets 45A and 45B is rotatable around the beam axis CL of the particle beam B in an independent state from the other. In the example shown in Figs. 5(a) and 5(b), the pair of deflecting magnets 45A and 45B are rotatable around the beam axis CL of the particle beam B in an independent state from each other. That is, the pair of deflecting magnets 45A and 45B rotate around the beam axis CL in a separated state from each other. In this case, the direction and rotation angle of the rotation direction RDa of the deflecting magnet 45A and the direction and rotation angle of the rotation direction RDb of the deflecting magnet 45B do not have to be the same. The deflecting force Fa by the deflecting magnet 45A acts in a direction rotated by the rotation angle with respect to the Y-axis direction. The deflecting force Fb by the deflecting magnet 45B acts in a direction rotated by the rotation angle with respect to the X-axis direction. Different from the structure of Fig. 4, the angle between the deflecting force Fa and the deflecting force Fb may be other than 90°.

[0044] In this case, as shown in Fig. 5(c), the direction of the deflecting force Fa can be changed by the rotation angle θ3 from the Y-axis direction, and the direction of the deflecting force Fb can be changed by the rotation angle θ4 from the X-axis direction. The rotation angle θ3 and the rotation angle θ4 may be different from each other. In this case, the maximum deflecting force Fmax can be generated at an angle other than "angle θ1 = 45°". If the adjustment ranges of the rotation angles θ3 and θ4 are at least 90°, by adjusting the directions of the deflecting forces Fa and Bb, the maximum deflecting force Fmax can be generated in the range of "angle θ1 = 0° to 360°". That is, the deflecting magnet device 30 can adjust the magnitude of the combined deflecting force Ft in the range of "0 to the maximum deflecting force Fmax" over the entire circumference around the beam axis CL. The adjustment range AE is not limited to a square as shown in Fig. 4(c), but can be any quadrilateral shape according to the directions of the deflecting forces Fa and Bb as shown in Fig. 5(c). However, when the adjustment range of the particle beam B is limited to a certain extent, the adjustment ranges of the rotation angles θ3 and θ4 only need to be greater than 0° and may be less than 90°.

[0045] Here, as shown in Fig. 3(c), the angles formed by the deflecting force Fa and the maximum deflecting force Fmax, and the angles formed by the deflecting force Fb and the maximum deflecting force Fmax are fixed at 45°. Therefore, among the deflecting force Fa and the deflecting force Fb, a component Floss that cancels each other out without contributing to the maximum deflecting force Fmax becomes large. This component Floss also occurs in the structure shown in Fig. 4. On the other hand, in the structure shown in Fig. 5, different from the structure of Fig. 4, the angle between the deflecting force Fa and the deflecting force Fb may be smaller than 90°. In this case, as shown in Fig. 5(c), the angles formed by the deflecting force Fa and the maximum deflecting force Fmax, and the angles formed by the deflecting force Fb and the maximum deflecting force Fmax can be made smaller than 45°. In this case, among the deflecting force Fa and the deflecting force Fb, the component Bloss that cancels each other out can be reduced, and the directional component contributing to the maximum deflecting force Fmax can be increased. Therefore, the deflecting magnet device 30 shown in Fig. 5 can increase the maximum deflecting force Fmax compared with the comparative example and the structure of Fig. 4.

[0046] In addition, when the direction of adjusting the particle beam B can be predicted in advance, there may be an operation of fixing one of the deflection magnets 45A and 45B and rotating the other. For example, when the deflection magnet device 30 is arranged near the exit of the accelerator 3, the vertical angle of the particle beam B does not deviate greatly, but may deviate greatly in the horizontal direction. In this case, the horizontal deflection magnet 45B may be fixed and the other deflection magnet 45A may be rotatable.

[0047] As shown in FIG. 6(a), the deflection magnet device 30 may have one deflection magnet 45C, and one deflection magnet 45C may be rotatable around the beam axis CL of the particle beam B. Even with one deflection magnet 45C, as the degree of freedom of the deflection force Fc for adjusting the particle beam B, the degrees of freedom of two axes (angle and magnitude) can be ensured. As shown in FIG. 6(b), the deflection magnet device 30 sets the maximum value of the deflection force Fc of one deflection magnet 45C as the maximum deflection force Fmax. The direction of the maximum deflection force Fmax can be deflected around the beam axis CL. Therefore, the adjustment range AE is circular.

[0048] In the deflection magnet device 30 shown in FIGS. 3 to 6, the direction in which the beam axis CL extends is not particularly limited, and it may extend in the horizontal direction, may extend in a direction inclined from the horizontal direction, or may extend in the vertical direction. When the beam axis CL extends in the horizontal direction, the Z-axis direction and the X-axis direction are the horizontal directions, and the Y-axis direction is the vertical direction. The direction of the magnetic field of the deflection magnet 45A in the comparative example (the direction of the magnetic field on the beam axis CL), that is, the opposing direction of the protruding portion 49, is the horizontal direction. Also, the direction of the magnetic field of the deflection magnet 45B, that is, the opposing direction of the protruding portion 49, is the vertical direction. On the other hand, as shown in FIGS. 4 to 6, when the deflection magnet 45B is adjusted by rotating it around the beam axis CL, the direction of the magnetic field of the deflection magnet 45B is arranged to be inclined with respect to the vertical direction. The direction of the magnetic field of the deflection magnet 45A is not perpendicular to the vertical direction (that is, the horizontal direction), but is arranged to be inclined with respect to the vertical direction.

[0049] Next, with reference to FIGS. 7 to 9, a mechanism for rotating the deflection magnet 45 will be described. Note that the following mechanism is applicable to any of the deflection magnets 45A, 45B, and 45C. As shown in FIGS. 7 to 9, the deflection magnet device 30 includes an adjustment mechanism 50 for adjusting the rotation angle of the deflection magnet 45 with respect to the beam axis CL.

[0050] FIG. 7 shows an example in the case where the Y-axis direction is the vertical direction. That is, it is assumed that gravity acts toward the negative side in the Y-axis direction. The adjustment mechanism 50 shown in FIG. 7(a) includes support portions 51A and 51B that support the deflection magnet 45 from below. The support portions 51A and 51B are arranged so as to be separated from each other in the X-axis direction, and support both end sides in the X-axis direction of the lower surface 45a of the deflection magnet 45. The support portions 51A and 51B have placement portions 51a on which the lower surface 45a of the deflection magnet 45 is placed. The adjustment mechanism 50 adjusts the rotation angle of the deflection magnet 45 by adjusting the height of the placement portion 51a of the support portion 51A and the height of the placement portion 51a of the support portion 51B. The adjustment mechanism 50 can set the deflection magnet 45 to the reference posture (see FIG. 3) by making the heights of the placement portions 51a of the support portions 51A and 51 the same. On the other hand, the adjustment mechanism 50 rotates the deflection magnet 45 and maintains the posture at the rotated position by providing a difference in the heights of the placement portions 51a of the support portions 51A and 51B.

[0051] The adjustment mechanism 50 shown in FIG. 7(b) has a base member 52 that extends parallel to the XZ plane below the deflection magnet 45, and spacers 53A and 53B that are arranged on the base member 52. The spacers 53A and 53B are arranged so as to be separated from each other in the X-axis direction, and support both end sides in the X-axis direction of the lower surface 45a of the deflection magnet 45. The adjustment mechanism 50 adjusts the rotation angle of the deflection magnet 45 by adjusting the thickness of the spacer 53A and the thickness of the spacer 53B. The adjustment mechanism 50 can set the deflection magnet 45 to the reference posture (see FIG. 3) by making the thicknesses of the spacers 53A and 53B the same. On the other hand, the adjustment mechanism 50 rotates the deflection magnet 45 and maintains the posture at the rotated position by providing a difference in the thicknesses of the spacers 53A and 53B.

[0052] As shown in Fig. 8(a), an adjustment mechanism 50 using a pin 54 may be adopted. As shown in Fig. 8(a), the adjustment mechanism 50 includes a receiving portion 56 provided on the negative side in the Y-axis direction of the deflection magnet 45 and a pin 54. A plurality of receiving holes 56a are formed in the receiving portion 56 at a predetermined pitch around the beam axis CL. The receiving holes 56a receive the pin 54. Note that the receiving holes 56a and the pin 54 extend in the Z-axis direction. In the adjustment mechanism 50, the deflection magnet 45 and the receiving portion 56 are rotated to a desired angle. At this time, the pin 54 is inserted into any one of the receiving holes 56a of the receiving portion 56. At this time, on the back side of the receiving hole 56a, it communicates with other receiving holes formed in other base members or the like. Therefore, when the pin 54 is inserted through the receiving hole 56a and other receiving holes, the pin 54 fixes the deflection magnet 45 together with the receiving portion 56 at the rotational position.

[0053] As shown in Fig. 8(b), an adjustment mechanism 50 using an engaging portion 57b may be adopted. As shown in Fig. 8(b), the adjustment mechanism 50 includes an engaging member 57 provided on the negative side in the Y-axis direction of the deflection magnet 45 and a support member 58. The engaging member 57 has a plurality of engaging portions 57a provided at a predetermined pitch around the beam axis CL at the end portion on the negative side in the Y-axis direction. The plurality of engaging portions 57a are formed by a repeating pattern of ridges and valleys. In the adjustment mechanism 50, the deflection magnet 45 and the engaging portion 57 are rotated to a desired angle. At this time, the support member 58 is engaged with any one of the engaging portions 57a of the engaging member 57. At this time, in a state where the engaging portion 57a is engaged with the support member 58 and supported, the deflection magnet 45 is fixed together with the engaging member 57 at the rotational position.

[0054] As shown in FIG. 9(a), an adjustment mechanism 50 using a gear 60 may be employed. As shown in FIG. 9(a), the adjustment mechanism 50 includes a gear 60 fixed to the deflection magnet 45 and a gear 61 meshing with the gear 60. The gear 62 is fixed to the rotating shaft 62 and rotates together with the rotating shaft 62. The adjustment mechanism 50 rotates the deflection magnet 45 via the gear 60 by rotating the gear 61. The gear 61 is stopped at a position where the deflection magnet 45 reaches a desired rotation angle. Thereby, the deflection magnet 45 is maintained in the posture at the rotation angle position. By using the gear 60 in this way, the rotation angle can be adjusted steplessly.

[0055] As shown in FIG. 9(b), an adjustment mechanism 50 using a pinion gear 63 may be employed. As shown in FIG. 9(b), the adjustment mechanism 50 includes a gear 60 fixed to the deflection magnet 45 and a pinion gear 63 meshing with the gear 60. The gear 62 is fixed to the rotating shaft 62 and rotates together with the rotating shaft 62. The adjustment mechanism 50 rotates the deflection magnet 45 via the gear 60 by moving the pinion gear 63 in the X-axis direction. The pinion gear 63 is stopped at a position where the deflection magnet 45 reaches a desired rotation angle. Thereby, the deflection magnet 45 is maintained in the posture at the rotation angle position. By using the gear 60 in this way, the rotation angle can be adjusted steplessly.

[0056] The adjustment mechanism 50 may include a drive unit 65 for rotating the deflection magnet 45 with respect to the beam axis CL. In the example shown in FIG. 9(a), the adjustment mechanism 50 may have a drive unit 65 such as a motor for rotating the rotating shaft 62. In the example shown in FIG. 9(b), the adjustment mechanism 50 may have a drive mechanism 64 for reciprocally moving the pinion gear 63 in the X-axis direction as the drive unit 65. Note that the gear 61 and the pinion gear 63 in FIG. 9(a) may be moved manually by an operator without depending on the drive unit 65. Note that the support portions 51A and 51B in FIG. 7(a) may be adjusted manually by an operator or may be adjusted by a drive unit. The operation of rotating the deflection magnet 45 and fixing it at the rotation angle as shown in FIGS. 7(b) and 8 may be performed manually by an operator or may be operated by a drive unit provided with a mechanism for operating it.

[0057] The adjustment of the deflection of the particle beam B by the deflection magnet device 30 may be performed by the control unit 7 (see FIG. 2). The control unit 7 can control the rotation angle of the deflection magnet 45 by controlling the aforementioned drive unit. The control unit 7 can perform two-stage adjustment on the structures shown in FIGS. 4 and 5. The control unit 7 performs the first adjustment of the particle beam B by rotating the deflection magnet 45. In the first adjustment, a rough adjustment for adjusting approximately the angle is performed. The control unit 7 performs the second adjustment of the particle beam B by electrically controlling the deflection magnet 45. In the second adjustment, the direction of the combined deflection force Ft is adjusted by adjusting the currents applied to the deflection magnets 45A and 45B. In the second adjustment, a fine adjustment is performed. In the structure shown in FIG. 6, the control unit 7 adjusts the direction of deflection by adjusting the rotation angle of the deflection magnet 45C. These adjustments may be manually performed by an operator without being controlled by the control unit 7.

[0058] Note that the configuration of the above-described deflection magnet device 30 only needs to be applied to at least one of the deflection magnet devices 30A, 30B, and 30C. In FIG. 1, a pair of deflection magnets 40 are shown for the deflection magnet device 30A, but the structure shown in FIG. 6 may be adopted to form one deflection magnet 40. Also, although one deflection magnet is shown for the deflection magnet devices 30B and 30C, the structures shown in FIGS. 4 and 5 may be adopted to form a pair of deflection magnets.

[0059] Next, the operations and effects of the particle beam therapy apparatus 1, the deflection magnet device 30, and the particle beam adjustment method according to the present embodiment will be described.

[0060] According to the particle beam therapy apparatus 1, the deflection magnet 45 that deflects the particle beam B of the transport unit 20 is rotatable around the beam axis CL of the particle beam B. In this case, the deflection magnet 45 can be rotated around the beam axis CL in accordance with the desired deflection direction of the particle beam B. Therefore, the direction in which the deflection force of the deflection magnet 45 can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam B. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam B. By obtaining an effective deflection force, it is also possible to obtain the desired performance even if the deflection magnet 45 is made smaller compared to the non-rotating deflection magnet device according to the comparative example. In this way, the cost can be reduced by making the deflection magnet 45 smaller. Further, when adjusting the rotation angle of the deflection magnet 45 itself, the number of steps of the adjustment work can be reduced compared to the case where the deflection direction is adjusted only by an electrical method, and thus the cost can also be reduced.

[0061] The deflection magnet device 30 has a pair of deflection magnets 45A and 45B, and the pair of deflection magnets 45A and 45B may be rotatable around the beam axis CL of the particle beam B while being fixed to each other in the rotation direction. When the deflection forces of the pair of deflection magnets 45A and 45B are superimposed, an angle at which the deflection force related to the superposition can be ensured to be large and an angle at which the deflection force becomes small can be formed. For example, as shown in FIG. 3(c), when the angle θ1 is 45°, the combined deflection force Ft can be the maximum deflection force Fmax, but when the angle θ1 is 0° or 90°, the combined deflection force Ft can only be obtained up to the magnitude of the deflection force of one. On the other hand, by rotating the pair of deflection magnets 45A and 45B around the beam axis CL of the particle beam B, the direction in which a large deflection force can be ensured (for example, the direction in which the maximum deflection force Fmax is obtained) can be aligned with respect to the desired deflection direction of the particle beam B. Therefore, the deflection force of the pair of deflection magnets 45A and 45B can be ensured to be large regardless of the direction of the deflection of the particle beam B around the beam axis CL. Here, since the pair of deflection magnets 45A and 45B are fixed to each other in the rotation direction, the rotation angle can be easily adjusted compared to the case where the rotation angles of the pair of deflection magnets 45A and 45B are adjusted individually.

[0062] The deflection magnet device 30 has a pair of deflection magnets 45A and 45B, and one of the pair of deflection magnets 45A and 45B may be rotatable around the beam axis of the particle beam in a state independent of the other. When the deflection forces of the pair of deflection magnets 45A and 45B are superposed, an angle at which the deflection force related to the superposition can be ensured to be large and an angle at which the deflection force becomes small can be formed. By rotating the pair of deflection magnets 45A and 45B around the beam axis of the particle beam, it is possible to align the direction in which a large deflection force can be ensured with respect to the desired deflection direction of the particle beam. Therefore, regardless of the direction of the deflection of the particle beam B around the beam axis CL, a large deflection force of the pair of deflection magnets 45A and 45B can be ensured. Here, when the deflection force of one deflection magnet 45A and the deflection force of the other deflection magnet 45B are superposed, there is a direction component in which the two deflection forces cancel each other out (see the component Bloss in FIG. 3(c)). On the other hand, one of the pair of deflection magnets 45A and 45B is rotatable around the beam axis CL of the particle beam B in a state independent of the other. Therefore, the relative rotation angle between the deflection magnets 45A and 45B can be adjusted so that the direction components that cancel each other out are reduced. Thereby, the energy for the deflection magnet device 30 can be effectively utilized.

[0063] The deflection magnet device 30 may have one deflection magnet 45C, and the one deflection magnet 45C may be rotatable around the beam axis CL of the particle beam B. In this case, the number of magnets of the deflection magnet device 30 can be reduced.

[0064] The particle beam treatment apparatus 1 may include an adjustment mechanism 50 for adjusting the rotation angle of the deflection magnet 45 with respect to the beam axis CL. In this case, by using the adjustment mechanism 50, the rotation angle of the deflection magnet 45 can be easily and accurately adjusted.

[0065] The adjustment mechanism 50 may include a drive unit 60 for rotating the deflection magnet 45 with respect to the beam axis CL. In this case, the rotation angle of the deflection magnet 45 can be adjusted without manual operation by an operator.

[0066] The beam axis CL extends in the horizontal direction, and the direction of the magnetic field of the deflection magnet 45 may be inclined with respect to the vertical direction.

[0067] The particle beam therapy apparatus 1 further includes a control unit 7 that controls the deflection magnet device 30. The control unit 7 may perform a first adjustment of the particle beam B by rotating the deflection magnet 45. In this case, the control unit 7 can roughly adjust the direction of the deflection force by rotating the deflection magnet 45 itself.

[0068] The control unit 7 may perform a second adjustment of the particle beam B by electrically controlling the deflection magnet 45. In this case, the control unit 7 can finely adjust the direction of the deflection force.

[0069] The deflection magnet device 30 has a pair of deflection magnets 45A and 45B. In the first adjustment, the control unit 7 may relatively rotate the respective deflection magnets 45A and 45B. In this case, the control unit 7 can also adjust the angle between the pair of deflection magnets 45A and 45B in the first adjustment.

[0070] The deflection magnet device 30 according to the present embodiment is a deflection magnet device 30 including a deflection magnet 45 that deflects the particle beam B, and the deflection magnet 45 may be rotatable around the beam axis CL of the particle beam B.

[0071] According to the deflection magnet device 30, by providing it at the location where the particle beam B passes, the particle beam B can be deflected in a desired direction. At this time, the deflection magnet 45 can be rotated around the beam axis CL in accordance with the desired deflection direction of the particle beam B. Therefore, the direction in which the deflection force of the deflection magnet 45 can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam B. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam B.

[0072] The particle beam adjustment method according to the present embodiment is a particle beam adjustment method for adjusting a deflection magnet that deflects the particle beam B, and adjusts the particle beam by rotating the deflection magnet around the beam axis of the particle beam.

[0073] According to the particle beam adjustment method, by providing the deflection magnet 45 at the location where the particle beam B passes through, the particle beam B can be deflected in a desired direction. At this time, the deflection magnet 45 is rotated around the beam axis CL in accordance with the desired deflection direction of the particle beam B. Therefore, the direction in which the deflection force of the deflection magnet can be effectively obtained can be aligned with respect to the desired deflection direction of the particle beam B. From the above, the deflection force can be effectively obtained regardless of the deflection direction of the particle beam B.

[0074] The present invention is not limited to the above-described embodiments.

[0075] In FIG. 1, a cyclotron is exemplified as the accelerator. However, the configuration of the present invention may be adopted for various accelerators such as a synchrocyclotron and a linear accelerator (linac).

[0076] In the above-described embodiment, the deflection magnet device 30 is applied to the transport unit of the particle beam therapy device, but the application destination is not particularly limited. For example, the deflection magnet device 30 may be applied to a high-energy accelerator. Also, the deflection magnet device 30 may be applied to an experimental facility for charged particle beams. Further, the deflection magnet device 30 may be applied to a magnetic separator.

Explanation of Reference Numerals

[0077] 1... Particle beam therapy device, 7... Control unit, 30, 30A, 30B, 30C, 30D, 30E, 30F, 30G... Deflection magnet device, 40, 41, 42, 45, 45A, 45B, 45C... Deflection magnet, 50... Adjustment mechanism, 60... Driving unit.

Claims

1. An irradiation unit that irradiates a subject with a particle beam, a transport unit that transports the particle beam, and a deflection magnet device having a deflection magnet that deflects the particle beam of the transport unit, wherein the deflection magnet is rotatable around the beam axis of the particle beam, a particle beam therapy apparatus.

2. The deflection magnet device has a pair of the deflection magnets, and the pair of the deflection magnets are rotatable around the beam axis of the particle beam while being fixed to each other in the rotation direction. The particle beam therapy apparatus according to Claim 1.

3. The deflection magnet device has a pair of the deflection magnets, and one of the pair of the deflection magnets is rotatable around the beam axis of the particle beam independently of the other. The particle beam therapy apparatus according to Claim 1.

4. The deflection magnet device has one of the deflection magnets, and the one deflection magnet is rotatable around the beam axis of the particle beam. The particle beam therapy apparatus according to Claim 1.

5. The particle beam therapy apparatus according to Claim 1, further comprising an adjustment mechanism that adjusts a rotation angle of the deflection magnet with respect to the beam axis.

6. The particle beam therapy apparatus according to Claim 5, wherein the adjustment mechanism includes a drive unit for rotating the deflection magnet with respect to the beam axis.

7. The particle beam therapy apparatus according to Claim 2 or 4, wherein the beam axis extends in a horizontal direction, and the direction of the magnetic field of the deflection magnet is inclined with respect to the vertical direction.

8. The particle beam therapy apparatus according to Claim 1, further comprising a control unit that controls the deflection magnet device, wherein the control unit performs a first adjustment of the particle beam by rotating the deflection magnet.

9. The particle beam therapy apparatus according to Claim 8, wherein the control unit performs a second adjustment of the particle beam by electrically controlling the deflection magnet.

10. The deflection magnet device has a pair of the deflection magnets, and in the first adjustment, the control unit relatively rotates each of the deflection magnets. The particle beam therapy apparatus according to Claim 8.

11. A deflection magnet device including a deflection magnet that deflects a particle beam, wherein the deflection magnet is rotatable around the beam axis of the particle beam. A deflection magnet device.

12. A particle beam adjustment method for adjusting a deflection magnet that deflects a particle beam, wherein the particle beam is adjusted by rotating the deflection magnet around the beam axis of the particle beam. A particle beam adjustment method.

Images