Charged particle beam irradiation device and charged particle beam therapy system

Abstract

To provide a charged particle beam irradiation device.SOLUTION: A charged particle beam irradiation device comprises: a beam transport system 30 having a plurality of beam paths for transporting a charged particle beam emitted from an accelerator 20 to a single isocenter O; and a shielding body 110 disposed on a first beam path among the plurality of beam paths to block the travel of the charged particle beam passing through the first beam path. The beam transport system 30 includes a distribution electromagnet 33 that deflects the charged particle beam and a focusing electromagnet 40 installed on the downstream side relative to the distribution electromagnet to focus the charged particle beam onto the isocenter. When the charged particle beam passes through the first beam path, the shielding body 110 retracts from the first beam path so that the charged particle beam can pass through.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charged particle beam irradiation device and a charged particle beam therapy system. [Background technology]

[0002] Conventionally, charged particle beams (also called "particle beams") accelerated to high energy have been used to treat cancer and other diseases. Particle beam therapy is used to treat malignant tumors by irradiating them with charged particle beams. When an object is irradiated with a charged particle beam, energy (dose) is transferred to the object along the path of the charged particle beam within the object. When a dose is concentrated in a limited area (target) inside an object, charged particles are The dose is controlled by irradiating the target with a charged particle beam from various directions so that the child beams overlap. It is done to improve concentration.

[0003] Patent Document 1 describes a method for deflecting a charged particle beam incident from a wide angle range and directing it to the isocenter. A charged particle beam irradiation device including a focusing electromagnet for focusing is disclosed. Patent Document 2 describes a method for selecting multiple independent beam paths within a treatment room. It is disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6364141 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-113118 Summary of the Invention [Problem to be solved by the invention]

[0005] In the same treatment room (in the case of Patent Document 1, the area where the beam travels downstream after the deflection origin Q) ) a charged particle beam irradiation device in which a plurality of beam paths for irradiating a charged particle beam exist within In this case, when a charged particle beam is irradiated through a predetermined beam path, 1. The charged particle beam may travel through an unintended beam path and be unintentionally irradiated onto the patient. There is a risk of injury.

[0006] In view of the above circumstances, the present invention provides a charged particle beam that prevents such unintentional irradiation. The object of the present invention is to provide a radiation irradiation device. [Means for solving the problem]

[0007] The present invention includes the following aspects [1] to [5]. [1] A charged particle beam irradiation device, The charged particle beam emitted from the accelerator (20) is transported to one isocenter (O). a beam transport system (30) having a plurality of beam paths; A light source is disposed on a first beam path among the plurality of beam paths, and passes through the first beam path. a shield (110) that blocks the passage of the charged particle beam; Equipped with The beam transport system (30) a deflection electromagnet (33) for deflecting the charged particle beam; A beam splitter is installed downstream of the splitting electromagnet and passes through the plurality of beam paths or A charged particle beam passing through one of the beam paths is focused at the isocenter. A focusing electromagnet (40) for focusing the beam Equipped with The first beam path is a path through which the charged particle beam passes when the deflecting electromagnet is not excited. a beam path that passes through the deflection electromagnet and is irradiated onto the isocenter, When the charged particle beam passes through the first beam path, the shield (110) , the charged particle beam is retracted from the first beam path to allow the charged particle beam to pass. Child beam irradiation device. [2] The shield is disposed downstream of the sorting electromagnet and upstream of the focusing electromagnet. Placed, The first beam path is a line passing through the deflection origin Q of the deflection electromagnet and the isocenter. The charged particle beam irradiation device described in [1] above. [3] A charged particle beam irradiation device, The charged particle beam emitted from the accelerator (20) is directed toward one isocenter (O). a beam transport system (30) having a plurality of beam paths for transporting; The irradiation nozzle (50) moves along a guide rail (55), and the guide rail The first and second nozzles are arranged to sandwich the irradiation nozzle (50) in the direction along the nozzle. Shields (110a, 110b) and Equipped with The beam transport system includes: a deflection electromagnet (33) for deflecting the charged particle beam; A charged particle beam passing through the plurality of beam paths is arranged downstream of the sorting electromagnet. a focusing electromagnet (40) for focusing the beam to the isocenter; Equipped with The first and second shields are detachably attached to the irradiation nozzle, and It moves according to the movement, but is fixed when it comes to a position on the first beam path of the guide rail. It is structured as follows: The first beam path is a path through which the charged particle beam passes when the deflecting electromagnet is not excited. The beam path that passes through the deflecting electromagnet and the focusing electromagnet and is irradiated onto the isocenter The charged particle beam irradiation device is a path. [4] the deflecting electromagnet deflects the charged particle beam at a deflection angle φ of 1 degree or more at a deflection starting point Q; the focusing electromagnet includes a pair of coils arranged on either side of a path of the charged particle beam; When a current is input to the coil pair, the charged particle beam moves in a direction perpendicular to the X-axis. The magnetic field is configured to generate an effective magnetic field region in the direction of the X-axis and Z-axis. The axis perpendicular to the Z axis is the Y axis, In the XY plane, The load is deflected at the deflection angle φ with respect to the X axis at the deflection starting point Q and enters the effective magnetic field region. The electron beam is deflected by the effective magnetic field region and directed to the isotropic plane at an irradiation angle θ with respect to the X axis. Irradiated to the center, Any point P2 on the boundary of the effective magnetic field region on the exit side of the charged particle beam is It is located at an equal distance r1 from the center. The point P1 on the boundary of the effective magnetic field region on the incident side of the charged particle beam and the point P2 are spaced apart by a radius It is on an arc with a central angle of r2 and (θ+φ), The distance R between the deflection origin Q and the point P1 is If the distance between the two is L, then the relation (4):

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[0008] [Figure 1]1 is a schematic configuration diagram of a charged particle beam irradiation device according to first and second embodiments of the present invention. [Figure 2A] 1 is a schematic configuration diagram of a charged particle beam irradiation system according to a first embodiment. [Figure 2B] FIG. 1 is an explanatory diagram relating to the prior art. [Figure 2C] 1 is a schematic configuration diagram of a charged particle beam irradiation system according to a first embodiment. [Figure 2D] 1 is a schematic configuration diagram of a charged particle beam irradiation system according to a first embodiment. [Figure 3] FIG. 10 is a schematic configuration diagram of a converging electromagnet according to a second embodiment. [Figure 4] FIG. 10 is a diagram for explaining the formation of an effective magnetic field region according to the second embodiment. [Figure 5] FIG. 10 is a schematic configuration diagram of a shielding mechanism according to a second embodiment. [Figure 6] 10A and 10B are diagrams for explaining the movement of a shield according to the second embodiment. [Figure 7] 10 is a flowchart of irradiation control of a charged particle beam irradiation apparatus according to a second embodiment. [Figure 8] FIG. 10 is a schematic configuration diagram of a charged particle beam irradiation system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is a schematic diagram of a charged particle beam irradiation device 10 according to the present invention. 1 is a diagram according to the first embodiment of the present invention, and shows the area in which the beam travels downstream of the deflection starting point Q. Within the chamber, multiple independent beam paths irradiate a charged particle beam to one isocenter O. FIG. 1(b) shows a second embodiment of the present invention. This is a diagram related to the beam path after the deflection starting point Q. A charged particle beam with multiple consecutive beam paths projecting a charged particle beam onto the center. It is a radiation device.

[0010] The charged particle beam irradiation device 10 according to one embodiment of the present invention is a device for irradiating charged particles emitted from an accelerator 20. A beam transport system having multiple beam paths for transporting a charged particle beam toward an isocenter O. a beam transport system 30 and a beam path locating on a first beam path of the beam transport system 30; a shielding mechanism that blocks (shields) the progress of the charged particle beam passing through the first beam path; 100 and a shield 110. When a charged particle beam is to pass through the first beam path, At this time, the shield 110 is moved from the first beam path to allow the charged particle beam to pass through. The first beam path is a path for charged particles when the polarizing electromagnet 33 is not excited. The beam passes through the deflection magnet 33 (or the deflection magnet 33 and the focusing magnet 40) and is then The first beam path is the beam path that is irradiated to the center O. That is, the first beam path is the beam path that is irradiated to the center O through the deflection magnet 33. It is on the line passing through the deflection origin Q and the isocenter O.

[0011] The charged particle beam irradiation device 10 includes a focusing electromagnet 40, an irradiation nozzle 50, and a control device 60. Furthermore, the charged particle beam therapy system according to one embodiment of the present invention further comprises an accelerating The apparatus includes a chamber 20 and a charged particle beam irradiation device 10.

[0012] The accelerator 20 is a device that generates a charged particle beam, and is, for example, a synchrotron, a cyclotron, or the like. The charged particle beam generated in the accelerator 20 is then transferred to the beam transporter. The beam is focused at the isocenter O through the transmission system 30 .

[0013] The beam transport system 30 includes a deflection magnet 33 for deflecting the charged particle beam, and a deflection magnet 3 3, and directs the charged particle beam through one of several beam paths. The beam transport system 30 also includes a focusing electromagnet 40 that focuses the beam to the source center O. One or more charged particle beam adjusting means 31, a vacuum duct 32, a fan-shaped vacuum duct 34, and The beam path may further include a vacuum duct 32 and an irradiation nozzle 50. The isocentesis magnet passes through the vacuum area in the dividing electromagnet 33 and the focusing electromagnet 40 and enters the atmosphere of the treatment room. This leads to Center O.

[0014] The control device 60 includes an irradiation control unit 62, a shield drive control unit 64, and a shield position detection unit 66. The control device 60 controls the irradiation information transmitted from the irradiation computer (not shown). The shield drive control unit 64 and the shield position detection unit control the devices related to irradiation according to the information. 66 moves the shield 110 to a predetermined position, and the control device 60 controls the position of the shield 110. The position of the charged particle beam is monitored and the emitted charged particle beam is controlled.

[0015] A first embodiment of the present invention will be described. Fig. 2A shows a particle beam therapy system having two treatment rooms. This is a schematic diagram of the facility. Each treatment room is equipped with a splitter magnet 33 (33A and 33B in the figure). The point is a single isocenter O (OA, OB in the figure) in the treatment room. 1 and 2A to 2C, the brackets after the symbols indicate The numbers inside (0A) mean zero amperes, and (0) means the charged particle beam from the 0 degree direction. It is attached to elements such as electromagnets used in irradiating the beam, and (90) indicates the charge from a 90-degree direction. It is attached to elements such as electromagnets used in particle beam irradiation, and (45) is from a 45-degree direction. It is attached to elements such as electromagnets used in irradiating a charged particle beam.

[0016] The charged particle beam extracted from the accelerator 20 and transported thereto is deflected at a deflection origin Q (QA in the figure). QB), the light is divided into two paths by the dividing electromagnet 33 (33A and 33B in the figure), and converges. The beam is irradiated from the intended irradiation angle by the flux electromagnet 40. That is, the deflection origin Q (Q- A, QB) for irradiation paths from 0 degrees, 45 degrees, and 90 degrees to the beam axis. For example, if the irradiation angle is set to 45 degrees in treatment room B, the beam is distributed to the distribution magnet 3. Pre-setting of excitation current value etc. for electromagnets including 3B and focusing electromagnet 40B (45) Once all the settings have been changed, the charged particle beam will begin to irradiate. The beam path of the beam transport system 30 shown by the thick arrow in FIG. 2A corresponds to the set path 220 (intended path). In this case, treatment room A is not selected, so the irradiation path is is not included.

[0017] 2B, when the shield 110 is not used, the sorting electromagnet 33 may not function unintentionally. For example, when the illumination angle is 45 degrees or 90 degrees, Even though it is selected, the excitation current to the dividing electromagnet 33B is 0A (zero amperes). Although a value other than 0A was specified, the excitation current of the sorting electromagnet 33B was unintentionally set to 0A. If this happens, the charged particle beam incident on the sorting electromagnet 33B will be polarized by the sorting electromagnet 33B. At this time, the beam transport shown in Figure 2B The charged particle beam travels through a first beam path 210 indicated by a thick arrow in the transmission system 30, and reaches an isocenter. This could result in unintentional irradiation of the target OB.

[0018] If the set path 220 is different from the first beam path 210, the charged particle beam is The condition for the beam to be emitted toward the target O is that a shield 110 is placed in the first beam path 210. On the other hand, when the set path 220 is the same path as the first beam path 210, Opening the beam path, i.e., retracting the shield 110 from the first beam path 210 The position of the shield 110 is monitored by the control device 60. For example, as shown in FIG. In this example, even though the irradiation angle was selected from 45 degrees in treatment room B, the Even if the excitation current of the 33B stone becomes 0A (zero amperes) unintentionally, The shield 110B blocks the charged particle beam traveling through the first beam path 210, and the isotropic beam This prevents the radio waves from reaching the center OB. Note that treatment room A is not selected, so the radio waves are blocked. The position of the shield 110A may or may not be included in the irradiation conditions of the treatment room B.

[0019] If the irradiation angle is set to 0 degrees, the set path 220 (intended irradiation path) is set to the first The beam path is the same as beam path 210. In this case, as shown in FIG. 2D, the shield 110B is By retreating from the set path 220 (first beam path 210), the beam can be moved to the isocenter OB. It is possible to irradiate

[0020] A second embodiment of the present invention will be described. The transport system 30 starts from the distribution electromagnet 33 and converges to one isocenter O in the treatment room. The beam path includes a plurality of continuous beam paths. By combining various excitation current values ​​of the two bending electromagnet power supplies, the desired irradiation angle can be obtained. 3 is a schematic diagram of the distributing electromagnet 33 and the converging electromagnet 40 in the second embodiment. is.

[0021] The beam transport system 30 is a system for transporting a plurality of beam paths generated by a distribution magnet 33 and a focusing magnet 40. As will be described later, the plurality of beam paths are formed by the charged particle beam splitter 33. and the irradiation angle θ of the charged particle beam by the focusing electromagnet 40.

[0022] The first beam path 210 among the multiple beam paths is a path in which the polarizing electromagnet 33 is unintentionally excited. If there is no beam, the charged particle beam will naturally proceed toward the isocenter O. More specifically, the first beam path 210 is a beam path in which the polarizing electromagnet 33 is excited. When the beam is not in operation, the beam of charged particles is directed through the focusing electromagnet 40 and the focusing electromagnet 33. The beam path is the beam that passes through the isocenter O and is irradiated onto the isocenter O. The path 210 is a path in which the polarizing electromagnet 33 is excited even though the polarizing electromagnet 33 is set to φ≠0 degrees and θ≠0 degrees. This is the beam path when the charged particle beam is not magnetized and travels at φ=0 degrees and θ=0 degrees. In addition, the set path 220 where φ=0 degrees and θ=0 degrees is the first path when φ≠0 degrees and θ≠0 degrees. The beam path is the same as path 210.

[0023] A charged particle beam is emitted from the accelerator 20 along a set path 220 toward the isocenter O. The condition is that a shield is placed in the first beam path 210. φ≠0 degrees and When irradiation at θ≠0 degrees is selected, the shield 110 is always in the first beam path 210. On the other hand, when irradiation at φ=0 degrees and θ=0 degrees is selected, Since the set path 220 is the same as the first beam path 210, the charged particle beam advances The shield 110 is retracted from the set path 220 (first beam path 210) so that the beam can be transmitted. At this time, the position of the shield 110 is monitored by the control device 60. If the shield 110 is moved out of position, the status of the shield 110 becomes indeterminate and the beam immediately It will be blocked.

[0024] The accelerator 20, the charged particle beam adjusting means 31, and the deflecting electromagnet 33 are connected to each other through a vacuum duct 32. The polarizing electromagnet 33 and the focusing electromagnet 40 are connected by a fan-shaped vacuum duct 34 shown in FIG. By making the shape of the fan-shaped vacuum duct 34 fan-shaped in the XY plane, Even if the charged particle beam is deflected at a deflection angle φ of 5 degrees or more, or 10 degrees or more, the true It can pass through empty ducts, can be made smaller than rectangular ducts, and requires less installation space.

[0025] The charged particle beam is generated in an upstream accelerator 20 and is then The charged particle beam travels through the vacuum ducts 32 and 34 and is adjusted by the charged particle beam adjusting means 31. Then, the beam is guided to the dividing electromagnet 33 and the converging electromagnet 40 .

[0026] The charged particle beam adjusting means 31 adjusts the beam shape and / or dose of the charged particle beam. a beam slit for adjusting the direction of the charged particle beam, an electromagnet for adjusting the direction of the charged particle beam, Quadrupole electromagnets for adjusting the beam shape and the beam position of the charged particle beam Steering electromagnets for fine adjustment are used as appropriate depending on the specifications.

[0027] The beam paths of the beam transport system 30 are controlled by the deflection angle φ of the deflecting magnet 33 and the focusing magnet 34. The deflection angle φ and the deflection angle θ of the charged particle beam are also affected by the optical elements. and the irradiation angle θ, and the beam shape of the charged particle beam at the isocenter O changes depending on the deflection angle The beam width may vary depending on the beam angle φ and the beam irradiation angle θ. The charged particle beam adjusting means 31 provided upstream of 0 is adjusted for each deflection angle φ and irradiation angle θ. Adjust and align the charged particle beam at the isocenter so that the beam shape is appropriate. It may be possible to do so.

[0028] The deflecting electromagnet 33 continuously deflects the charged particle beam at a deflection angle φ and transfers the charged particle beam to the focusing electromagnet 40. The focusing electromagnet 40 is configured to emit a charged particle beam at the isocenter. The irradiation angle θ of the charged particle beam directed toward O is continuously changed. Applicant's prior patents (Patent No. 6364141, Patent No. 6387476, and Patent No. 673 The contents of the above-mentioned patent application are incorporated herein by reference. An example of the magnet 40 will be described below.

[0029] The irradiation nozzle 50 is located inside a treatment room where treatment using a charged particle beam is performed, and The focusing electromagnet 40 generates an effective magnetic field in the shape of the exit side (boundary shape). The eye moves continuously along the guide rail 55 (FIG. 8). The charged particle beam heading toward the source center O passes through the irradiation nozzle 50. The direction, shape, energy, etc. of the charged particle beam are finely adjusted.

[0030] The irradiation nozzle 50 includes a scanning electromagnet (not shown), a beam monitor 51, and an energy modulation means. The scanning electromagnet adjusts the amount and direction of the current flowing through it to illuminate the object. The direction of the charged particle beam emitted from the injection nozzle 50 is finely adjusted to control the charged particle beam within a relatively narrow range. The beam monitor 51 monitors the charged particle beam. The energy modulation means measures the position and flatness of the beam and the dose monitor. The energy of the electron beam is adjusted to control the depth to which the charged particle beam reaches within the patient. The energy modulation means may be, for example, a range modulator, a scatterer, a ridge filter, a patient collimator, or the like. It may be a meter, a patient bolus, an applicator, or a combination thereof.

[0031] FIG. 3(a) is a schematic diagram of the converging electromagnet 40. The X-axis represents the direction of travel of the charged particle beam, and the X-axis represents the direction of convergence of the charged particle beam. The direction of the magnetic field generated by the magnet 40 is the Z axis, and the direction perpendicular to the X and Z axes is the Y axis. The electromagnet 40 deflects charged particles incident from a wide range of deflection angles φ with respect to the X axis in the XY plane. The beam is configured to converge at the isocenter O. In FIG. The irradiation nozzle 50 is omitted, and for the sake of simplicity, the isocenter O is set as the origin of the XYZ space. The point is the positive direction of the X axis, with the upstream side (accelerator side) being the positive direction of the X axis.

[0032] The deflection angle φ ranges from -90 degrees to less than +90 degrees, and is positive (+Y axis direction). The deflection angle range and the negative (-Y axis direction) deflection angle range can be different (asymmetric). For example, the maximum deflection angle on the plus side (φ=φMAX) can be set to 10 degrees, 15 degrees, 20 degrees, 25 degrees, or 30 degrees. 35 degrees, 40 degrees, 45 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 85 degrees The maximum deflection angle on the negative side (φ=-φMAX) is set to -10 degrees, -15 degrees, or -20 degrees. degrees, -25 degrees, -30 degrees, -35 degrees, -40 degrees, -45 degrees, -50 degrees, -60 degrees, -70 The angle may be any of -80 degrees, -85 degrees, or -80 degrees.

[0033] The focusing electromagnet 40 includes one or more coil pairs, which are arranged to direct the charged particle beam. The direction is perpendicular to the direction of the deflection angle φ of the charged particle beam (the Z-axis direction in the figure). A uniform magnetic field is generated (effective magnetic field regions 41a and 41b), and the path of the charged particle beam is sandwiched between the regions. The effective magnetic field region generated by one pair of coils of the focusing electromagnet 40 is shown in FIG. As shown in a), it has a crescent shape in the XY plane, the details of which will be described later. The gap between the opposing coil pairs through which the charged particle beam passes (distance in the Z-axis direction) is Since the area is sufficiently small compared to the area in which the charged particle beam spreads in the XY plane, The spread of the child beam in the Z-axis direction is not taken into consideration.

[0034] 3(b) is a cross-sectional view of the focusing electromagnet 40 taken along the line AA. The focusing electromagnet 40 is preferably The coils 44a and 44b are provided with at least two pairs of coils 44a and 44b. The magnetic poles 45a and 45b are respectively incorporated, and a yoke 46 is connected to the magnetic poles 45a and 45b. A power supply (electromagnet control unit 122, which will be described later) is connected to the converging electromagnet 40. A current (excitation current) is supplied from the power supply to the coil pair 44a and 44b, causing convergence. The electromagnet 40 is excited, and the effective magnetic field regions 41a and 41b (collectively referred to as the effective magnetic field regions 41) .) is formed.

[0035] The range of the effective magnetic field region 41a and the range of the effective magnetic field region 41b may be different. (Asymmetric). For example, the range of the deflection angle φ in the positive (+Y axis direction) and the negative (-Y axis direction) If the range of the deflection angle φ is asymmetric, the effective magnetic field regions 41a and 41b are also asymmetric accordingly. By forming the magnetic field in this manner, the unused effective magnetic field area can be reduced.

[0036] The deflection angle φ of the charged particle beam deflected by the deflecting electromagnet 33 and incident on the focusing electromagnet 40 The range is from the maximum positive deflection angle (φ=φmax) to the maximum negative deflection angle (φ=-φmax) The maximum deflection angle of plus is φmax, which is an angle of 10 degrees or more and less than 90 degrees. The maximum deflection angle of the eggplant, -φmax, is an angle between -90 degrees and -10 degrees. The irradiation angle θ is the angle of the path of the charged particle beam with respect to the X axis in the XY plane.

[0037] The charged particle beam incident in the positive deflection angle range (φ=0 to φmax) is deflected by the first coil. The beam is deflected by the effective magnetic field region 41a of the pair 44a, passes through the irradiation nozzle 50, and reaches the isocenter O. Charged particle beams incident in the negative deflection angle range (less than φ=0 to -φmax) The beam is deflected by the effective magnetic field region 41b of the second coil pair 44b and passes through the irradiation nozzle 50. The beam is irradiated at the isocenter O. The magnetic field directions of the effective magnetic field regions 41a and 41b are The deflection angles from the deflecting electromagnet 33 to the converging electromagnet 40 are opposite to each other. The charged particle beam incident on the effective magnetic field region 41a or 41b or both regions 41a , 41b and converges onto the isocenter O through the irradiation nozzle 50.

[0038] The deflection angle φ of the charged particle beam incident on the focusing electromagnet 40 is controlled by the deflecting electromagnet 33. The deflecting electromagnet 33 deflects the charged particle beam supplied from the accelerator (not shown) in the direction of travel ( A magnetic field is generated that is oriented in a direction perpendicular to the X-axis (Z-axis in the figure), and a charged particle beam passes through it. and a control unit for controlling the strength and direction of the magnetic field (both not shown). The distribution electromagnet 33 controls the strength and direction (Z-axis direction) of the magnetic field, and The charged particle beam is deflected at the deflection angle φ at the deflection starting point Q and collected. The beam is emitted to the flux electromagnet 40. Here, the deflection origin Q and the isocenter O are on the X axis.

[0039] Referring to FIG. 4, the formula for forming the effective magnetic field region 41a of the focusing electromagnet 40 will be described. In this embodiment, the deflection of the charged particle beam in the Z-axis direction is not taken into consideration. Next, the formation of the effective magnetic field region in the XY plane will be described. The effective magnetic field region 41a will be described below, but the same applies to the effective magnetic field region 41b, so the description will be omitted. Abbreviated.

[0040] First, the boundary of the effective magnetic field region 41a on the exit side 43 of the charged particle beam of the focusing electromagnet 40 is as follows: The range is determined to be at an equal distance r1 from the isocenter O. Next, The boundary of the effective magnetic field region 41a on the incident side 42 of the charged particle beam of the stone 40 is determined by the following relation ( Based on 1) to (5), a virtual deflection source located at a predetermined distance L from the isocenter O is The incident charged particle beam is deflected at a deflection angle φ at point Q and converges at the isocenter O. Here, the imaginary deflection origin Q is the center of the deflecting electromagnet 33, and the charged particle beam The point is that it is assumed that the ball receives a kick with a deflection angle φ over an extremely short distance.

[0041] The charged particle beam transported at the deflection angle φ is incident on the boundary of the effective magnetic field region 41a on the entrance side 42. It enters from an arbitrary point P1 on the top and performs a circular motion with a curvature radius r2 within the effective magnetic field region 41a (this The central angle at this time is (φ+θ). 2 and irradiates toward the isocenter O. In other words, points P1 and P2 are separated by a radius r 2 and is on an arc with a central angle of (φ+θ).

[0042] Assume an XY coordinate system with the isocenter O as the origin on the XY plane. If the angle between the line connecting P2 and the isocenter O and the X axis is defined as the irradiation angle θ, then the incident side 4 The coordinates (x, y) of point P1 in Fig. 2, the deflection angle φ, and the distance R between point Q and point P1 are expressed as follows: It can be calculated using equations (1) to (4).

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[0043] Here, a magnetic field with a uniform magnetic flux density B is generated in the effective magnetic field region 41a, and the charged particle beam Let the momentum of the electron be p (which roughly depends on the accelerator) and the charge be q. The deflected charge in the magnetic field is The radius of curvature r2 of the charged particle beam is expressed by equation (5).

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[0044] Based on the above-mentioned relations (1) to (5), the coil pair 44a and the magnetic pole 45a of the focusing electromagnet 40 By adjusting the shape and arrangement of the coil pair 44a and adjusting the current flowing through the coil pair 44a, the effective magnetic field region 4 That is, the shape of the boundary of the effective magnetic field region 41a on the exit side 43 can be adjusted. A boundary is defined so that the distance between any point P2 and the isocenter O is equal to r1. The magnetic flux density B in the effective magnetic field region 41a is adjusted to determine r2 from equation (5), and the effective magnetic field on the incident side 42 is The distance R between the point P1 on the boundary of the field region 41a and the deflection origin Q is set to satisfy the relationship of formula (4). The boundary of the effective magnetic field region 41a on the entrance side 42 is determined as follows. The deflection angle is φmax. Although not limited to this, the charged particle passing through the deflection starting point Q The beam is focused at the isocenter O without being deflected by the focusing electromagnet 40. By adjusting the positions of the deflection origin Q, the focusing electromagnet 40, and the isocenter O, the device configuration This is preferable because it makes the process simpler.

[0045] The boundary between the effective magnetic field regions 41a and 41b of the focusing electromagnet 40 obtained as described above is This is an ideal shape for focusing the particle beam at the isocenter O. In reality, Even if there is a deviation from this ideal shape or non-uniformity in the magnetic field distribution, the focusing electromagnet 40 The excitation amount (magnetic flux density B) is finely adjusted in advance for each deflection angle φ, and this information is sent to the power supply (for example, the irradiation The deflection angle φ and the current amount of the focusing electromagnet 40 are stored in the control unit 121. By controlling these, the charged particle beam can be deflected to match the isocenter O. In addition, if the non-uniformity of the magnetic field distribution can be predicted in advance, the focusing electromagnet 40 can be By correcting the shape and arrangement of the coil pairs 44a, 44b and the magnetic poles 45a, 45b, the charging It is also possible to fine-tune the trajectory of the particle beam.

[0046] The control device 60 is a computer equipped with a processing unit and a storage unit, and is a combination of hardware and software. The functional units realized in cooperation with the software include an irradiation control unit 62 and a shield drive control unit. 64, and a shield position detection unit 66. The irradiation control unit 62 controls the accelerator 20, the beam transport Each element of the system 30 (charged particle beam adjusting means 31, the deflecting electromagnet 33, the focusing electromagnet 40, and The shield drive control unit 64 controls the shield 110 of the shielding mechanism 100. The shield position detection unit 66 controls the movement of the shield 110, and determines the position of the shield 110. 62, the shield drive control unit 64, and the shield position detection unit 66 are configured as the same computer. The computer system may be configured as a single computer, or may be configured as separate computers.

[0047] 5 is a schematic diagram of the shielding mechanism 100. The shielding mechanism 100 is configured to A shield 110 for blocking the rows, a shaft 112 connected to the shield 110, and a shaft A fixed end 113 is provided with an opening through which the outlet 112 passes, and one end is connected to the fixed member 113 and the other end is connected to the fixed member 113. a biasing member 114 connected to the movable end 115, and a shaft 11 connected to the movable end 115. and a drive mechanism 117 for driving the drive shaft 6.

[0048] The shield 110 of the shielding mechanism 100 is disposed in the vacuum region of the beam transport line 30. For example, The shield 110 is disposed within the sectorial vacuum duct 34 .

[0049] The shield 110 blocks the charged particle beam with the maximum energy required for treatment. It is made of a material that can be used to block the spread of the charged particle beam in the YZ plane. For example, the energy of the charged particle beam is enough to penetrate deep into the patient's body (approximately 30 cm). It has enough energy to penetrate into tumors located in the brain. For electrons, it is about 230MeV, and for carbon beams, it is about 430MeV / u.

[0050] The material of the shield 110 is such that the shield 110 is resistant to irradiation of the charged particle beam. This can reduce the deterioration of the vacuum level in the vacuum area (for example, the fan-shaped vacuum duct 34) that is being Neutron rays, gamma rays, and secondary charged particles generated by the nuclear reaction between the charged particle beam and the shielding body 110 It is desirable to use a material that can reduce the radiation exposure of patients by using a superconducting magnet. When turning it into a stone, the vacuum chamber of the focusing electromagnet 40 is kept at an extremely low temperature of a few K (Kelvin). Therefore, the gas release rate from the surface of the material of the shield 110 is extremely low, and the material has a low emissivity. (For example, a material that does not contain oxygen) is preferable. These include oxygen-free copper and SUS, which have high water equivalent thickness.

[0051] The shape of the shield 110 is determined based on the beam size of the charged particle beam, the trajectory error on the beam path, and It is desirable to make it larger than the beam size, taking into consideration the beam energy and other factors. , except when the first beam path is irradiated with a charged particle beam, the shield 110 is Since it will be placed in the path at all times, it will not interfere with the charged particle beam passing through another beam path. Make it large enough so that it doesn't get in the way.

[0052] The biasing member 114 is configured to bias the shield 110 so that the shield 110 is in the first position when no external force is applied to the shield 110. The shaft 112 is biased so as to be positioned on the arm path 210, for example, by a The driving mechanism 117 is, for example, an air compressor and The driving mechanism 117 receives a control signal from the shield driving control unit 64. The shaft 116 is driven (pulled) to move the movable end 115 and the biasing member 114. By stretching and moving the shaft 112, the shield 110 is moved. The motion control unit 64 removes the stress applied by the driving mechanism 117, so that the shield 110 acts as a biasing member. 114 and returns to its inserted position on the first beam path 210.

[0053] The shield position detection unit 66 receives a drive signal from the shield drive control unit 64 and / or detects the position of the shield. In response to a signal from a sensor attached to the shield 110, the shield 110 moves in the first beam path. It is determined whether the sensor is positioned on 210. The sensor may be either a contact or non-contact type. As an example of a mechanism for monitoring the retracted position, the insertion and retracted position of the shield 110 is monitored by a limit switch (not shown). The switch is detected by a rail (not shown) that guides the extension and contraction of the biasing member 114. ) on the first beam path 210. The movable end is located at an insertion position (IN) and a retracted position (OUT) from the first beam path 210. 115 is provided with a position detection bar (not shown), and the position detection bar is connected to the IN switch or the OUT switch. By contacting the switch, the position of the shield 110 is detected. If not, the state is indeterminate.

[0054] The movement of the shield 110 will be explained using FIG. 6. FIG. 6(a) shows the movement of the shield 110 in the beam transport system 30. Among the multiple beam paths, the path 220 with φ≠0 degrees and θ≠0 degrees passes through the isocenter O At this time, the deflecting electromagnet 33 and the focusing electromagnet 40 (effective The magnetic field region 41a) is energized, and the shield 110 is driven by the application of a stress by the driving mechanism 117. The beam is not received and is inserted onto the first beam path 210.

[0055] FIG. 6(c) shows the beam path of the beam transport system 30 at φ=0 degrees and θ=0 degrees. A charged particle beam is drawn that passes through a set path 220 and is irradiated onto the isocenter O. The focusing electromagnet 33 and the focusing electromagnet 40 (effective magnetic field region 41a) are at 0 A, and the set path 220 The beam passes through the deflection electromagnet 33 (more specifically, the deflection origin Q) and the focusing electromagnet 40, and reaches the isocenter. In this case, the charged particle beam is irradiated along the set path 220 (the The shield 110 is biased by a drive mechanism 117 so that the beam 110 can pass through the beam path 210. Upon receiving the voltage, the beam retracts from the set path 220 (first beam path 210).

[0056] The charged particle beam is guided to the isocenter O through a beam path other than the first beam path 210. In the case of irradiation, that is, the charged particle beam passes through a set path 220 where φ≠0 degrees and θ≠0. When the beam is irradiated, the shield 110 is inserted on the first beam path 210. The position detection unit 66 determines whether the shielding object is in the target position. The irradiation control unit 62 determines whether the shielding object is in the target position. and irradiates the charged particle beam through a beam path other than the first beam path 210. On the other hand, when the charged particle beam is irradiated to the isocenter O through the first beam path 210, In this case, the charged particle beam is irradiated along the set path 220 where φ=0 degrees and θ=0. In this case, the shield 110 has moved to a position away from the set path 220 (first beam path). The shielding object position detection unit 66 determines whether the shielding object position is correct or not, and the irradiation control unit 62 determines whether the shielding object position is correct or not by the shielding object position detection unit 66. In response to the determination result, the charged particle beam is irradiated through the set path 220 (first beam path). Do the following.

[0057] In this way, if the control device 60 malfunctions or an unstable control state occurs, the sorting electromagnet 33 is not excited and the charged particle beam is not deflected in the intended direction at the deflection starting point Q (deflection Even if the angle φ is 0 degrees, the shield 110 prevents the charged particle beam from passing through the first beam path 210. Therefore, irradiation of the isocenter O is prevented (FIG. 6(b)).

[0058] The deflection electromagnet 33 is not necessarily excited unintentionally (deflection angle φ=0 degrees), and the deflection electromagnet When the deflection by the magnet 33 does not reach the intended angle (irradiation angle) (deflection angle φ<irradiation angle) , the shield 110 is inserted into the beam path so as to block the charged particle beam. In addition, the shielding mechanism 100 may be provided with a plurality of shields 110. The probability that one or both of the sorting electromagnet 33 and the focusing electromagnet 40 will perform an unintended operation is Empirically check the high beam paths and place a shield 110 on each of these beam paths. It may be configured as follows.

[0059] 7 is a flowchart of the irradiation control of the charged particle beam. The energy of the particle beam, the excitation of the electromagnet power supply that specifies the set path 220 of the charged particle beam Irradiation information such as current value, irradiation pattern, deflection angle φ, and irradiation angle θ is stored in a separate computer (not 1, the data is received from the network (step S1).

[0060] The irradiation control unit 62 controls the charged particle beam to travel along the specified set path 220 to the isocenter. Each of the electromagnet group including the focusing electromagnet 40 and the dividing electromagnet 33 is irradiated with O. The irradiation control unit 62 transmits the set value of the excitation current to the power supply (not shown) (step S2). The irradiation nozzle 50 is arranged so that the electron beam passes through the irradiation nozzle 50 and is irradiated onto the isocenter O. Move 50 (step S3).

[0061] The irradiation control unit 62 determines whether the beam travels along the specified set path 220 at φ=0 degrees and θ=0 degrees. It is determined whether the beam path is the first beam path, that is, the first beam path 210 (step S4).

[0062] If the specified set path 220 is the first beam path 210 (Yes in step S4), ), that is, when the excitation current of the sorting electromagnet 33 is set to 0 A, the irradiation control unit 62 The shielding body 110 is retracted from the set path 220 (first beam path 210) by the body drive control unit 64. In response to this, the shield drive control unit 64 moves the shield 110 along the set path 22 0 (first beam path 210) (step S5). If the shield 1 is at a position retracted from the set path 220 (first beam path 210) at the time of the The shield position detection unit 66 detects that the shield 110 is in the retracted position. and sends the information to the irradiation control unit 62.

[0063] If the specified set path 220 is not the first beam path 210 (No in step S4), ), the irradiation control unit 62 controls the shield drive control unit 64 to control the shield 110 to the first beam path 210 In response to this, the shield drive control unit 64 moves the shield 110 to the first biplane. The shield 110 is inserted onto the beam path 210 (step S6). When the shield 110 is inserted on the path 210, the shield 110 does not move. 6 detects that the shield 110 is positioned on the first beam path 210 and uses the information to control irradiation. Send to Gobe 62.

[0064] The irradiation control unit 62 detects the position of the shield 110 based on the information from the shield position detection unit 66. Similarly, when it is determined that all devices related to irradiation are set up, irradiation is started. The control unit 62 sends a request for extraction of the charged particle beam to the accelerator control unit 63, and the signal triggers Then, the accelerator control unit 63 issues a signal permitting the extraction of the charged particle beam, and the charged particle beam is extracted. Then, the isocenter O is irradiated with the charged particle beam (step S7).

[0065] During irradiation, the shielding body position detection unit 66 detects the position of the irradiating body 110 at regular time intervals to control the irradiation. The position is transmitted to the irradiation control unit 62, and the irradiation control unit 62 monitors the position (step S8). If there is no change in the placement position of 110, irradiation continues as is (Yes in step S8). ) When the dose based on the irradiation information is reached (Step 9), irradiation is complete. For example, when the set path 220 is the first beam path 210 (φ=0 degrees and θ=0 degrees), the retraction When the beam path 220 is moved from the position or when the set path 220 is not the first beam path 210 (φ ≠0 degrees and θ ≠ 0 degrees), when the shield 110 is moved from the insertion position, the shield 110 is in an unstable state (state (No at step S8). If an unstable state is detected, it is notified to the interlock control (not shown), The accelerator control unit 63 immediately shuts off the charged particle beam (step S10).

[0066] In the charged particle beam irradiation apparatus 10 of this embodiment, the charged particle beam is irradiated through a first beam path 210. Since the shield 110 is always positioned on the first beam path except when the first beam passes through the This prevents unintentional irradiation of the isocenter O with the charged particle beam through the beam path. Here, the first beam path 210 is a path through which the charged particle beam passes when the deflecting electromagnet 33 is not excited. The beam passes through the deflecting electromagnet 33 and / or the focusing electromagnet 40 and is irradiated onto the isocenter O. Preferably, the first beam path 210 is a beam path in which the polarizing electromagnet 33 is not excited. When the charged particle beam passes through the deflecting electromagnet 33 and / or the focusing electromagnet 40, the isotropic The shield 110 is the beam path irradiated to the center O of the beam transport system 30. It can be installed in the airspace, and the size of the device can be reduced. The shield 110 does not contain oxygen in its material. If the shielding body 110 is made of a material (for example, oxygen-free copper), a nuclear reaction between the shielding body 110 and the charged particle beam occurs. The generation of secondary particles (secondary charged particles, neutrons, gamma rays, and / or photons) caused by This can reduce the effects of radiation exposure on the operator and the deterioration of the degree of vacuum due to gas generation from the shield 110.

[0067] In the charged particle beam irradiation system 10 according to another embodiment of the present invention, a plurality of shields 110 ( The beam transport system 30 includes a first shield 110a and a second shield 110b. It is not located in the airspace, but can move along the guide rail 55 along which the irradiation nozzle 50 moves. The guide rail 55 is provided in accordance with the patent 63874, which is incorporated by reference. As described in No. 76, the effective magnetic field areas 41a and 41b of the focusing electromagnet 40 are formed along the shape of the exit side. It is set up as follows.

[0068] FIG. 8 is a schematic diagram of a third example of the charged particle beam irradiation system 10 according to this embodiment. Two shields 110a and 110b are provided on a guide rail 55 along which the irradiation nozzle 50 moves. and arranged so as to sandwich the irradiation nozzle 50 in the direction along the guide rail 55. The upper side facing the paper surface is designated as shielding body 110a, and the lower side is designated as shielding body 110b.

[0069] The shields 110a and 110b are movable along the guide rails 55. The shields 110a and 110b are attached to the irradiation nozzle 50 by a means (for example, a magnetic a magnet, electromagnet, or detachable engaging means, and the shield However, the shielding body 110a or the shielding body 110b moves. When the roller 55 is positioned on the first beam path 210, it is latched in place. It is configured so that the shields 110a and 110b remain in that position. The shielding member is provided with a drive unit, and is self-propelled along the guide rail 55 under the control of the shielding member drive control unit 64. It may be configured so that

[0070] The charged particle beam passes through a set path 220 (first beam path 210) at φ=0 degrees and θ=0 degrees. When the radiation is irradiated to the isocenter O through the shields 110a and 110b (FIG. 8(a)), It is disposed near the irradiation nozzle 50.

[0071] The charged particle beam passes through the effective magnetic field region 41a along a set path 220 to the isocenter O. When the beam is irradiated from the first beam path 210 (FIG. 8(b)), the shield 110b is placed on the first beam path 210. The shield 110a is latched and moves together with the irradiation nozzle 50. When a charged particle beam is irradiated along a beam path passing through a, the shield 110b is The sensor 210 remains fixed on the track 210.

[0072] On the other hand, the charged particle beam passes through the set path 220 passing through the effective magnetic field region 41b. When the target O is irradiated (FIG. 8(c)), the shield 110a is disposed on the first beam path 210. The shield 110b is placed and latched, and moves together with the irradiation nozzle 50. When the charged particle beam is irradiated along a beam path passing through the region 41b, the shield 110a is the first beam. The arm remains fixed on the arm path 210.

[0073] In this way, similar to the above embodiment, in this embodiment, the angle is set to φ=0 degrees and θ=0 degrees or less. The charged particle beam is guided to the eye via an outer set path 220 (a beam path other than the first beam path 210). Even if the splitting electromagnet 33 is not excited unintentionally when irradiating the source center O, Since the shield 110a or the shield 110b is always disposed on the first beam path 210, Therefore, unintentional irradiation with the charged particle beam is prevented.

[0074] The dimensions, materials, shapes, relative positions of components, etc. described above are to be understood as being within the scope of the present invention. The specific terms and embodiments used in the description may vary depending on the structure of the device or various conditions. The present invention is not intended to be limited to the above, and those skilled in the art will recognize that other equivalent components may be used. The above-described embodiment may be modified and changed without departing from the spirit or scope of the present invention. Furthermore, features described in relation to one embodiment of the invention may be used interchangeably, even if explicitly stated. It is possible to use the present invention in combination with other embodiments, even if not described above. [Explanation of symbols]

[0075] 10. Charged particle beam irradiation equipment 20 Accelerator 30 Beam Transport System 31 Charged particle beam adjustment means 32 Vacuum Duct 33 Bending electromagnet 34 Fan-shaped vacuum duct 40 Converging electromagnet 50 irradiation nozzle 55 guide rail 100 Shielding mechanism 110(110A, 110B) Shield 110a, 110b First and second shields

Claims

1. 1. A charged particle beam irradiation system, comprising: A charged particle beam emitted from an accelerator (20) is transported to one isocenter (O). a beam transport system (30) having a plurality of beam paths; A light source is disposed on a first beam path among the plurality of beam paths, and passes through the first beam path. a shield (110) that blocks the passage of the charged particle beam; Equipped with The beam transport system (30) a deflecting electromagnet (33) for deflecting the charged particle beam; A beam splitter is installed downstream of the splitting electromagnet and passes through the plurality of beam paths or The charged particle beam passing through one of the beam paths is focused at the isocenter. A focusing electromagnet (40) for converging the beams; Equipped with The first beam path is a path along which the charged particle beam passes when the deflecting electromagnet is not excited. a beam path that passes through the deflection electromagnet and is irradiated onto the isocenter, The charged particle beam irradiation system further includes a set path through which the charged particle beam passes. an irradiation control unit that controls the sorting electromagnets and the converging electromagnets based on irradiation information; When the set path is not the first beam path, the shield is located on the first beam path. If it is determined that the charged particle beam is not present, irradiation of the charged particle beam is not permitted. Irradiation system.

2. The shield is disposed downstream of the sorting electromagnet and upstream of the focusing electromagnet. Placed, The first beam path is a line passing through the deflection origin Q of the deflection electromagnet and the isocenter. The charged particle beam irradiation system of claim 1 .

3. 1. A charged particle beam irradiation system, comprising: The charged particle beam emitted from the accelerator (20) is directed toward one isocenter (O). a beam transport system (30) having a plurality of beam paths for transporting; The irradiation nozzle (50) moves along a guide rail (55), and the guide rail The first and second nozzles are arranged to sandwich the irradiation nozzle (50) in the direction along the nozzle. Shields (110a, 110b) Equipped with The beam transport system includes: a deflecting electromagnet (33) for deflecting the charged particle beam; A charged particle beam passing through the plurality of beam paths is arranged downstream of the sorting electromagnet. a focusing electromagnet (40) for focusing the beam to the isocenter; Equipped with The charged particle beam irradiation system further includes a set path through which the charged particle beam passes. an irradiation control unit that controls the sorting electromagnets and the converging electromagnets based on irradiation information; The first and second shields are detachably attached to the irradiation nozzle, When the guide rail reaches a position on the first beam path, configured to be fixed on the beam path; The first beam path is a path along which the charged particle beam passes when the deflecting electromagnet is not excited. The beam path that passes through the deflecting electromagnet and the focusing electromagnet and is irradiated onto the isocenter It is a road, When the set path is not the first beam path, one of the first and second shields is in front. If it is not determined that the charged particle beam is on the first beam path, irradiation of the charged particle beam is not permitted. The charged particle beam irradiation system.

4. the deflecting electromagnet deflects the charged particle beam at a deflection angle φ of 1 degree or more at a deflection starting point Q; the focusing electromagnet includes a pair of coils arranged on either side of a path of the charged particle beam; When a current is input to the coil pair, the coils are oriented in a direction perpendicular to the direction of travel of the charged particle beam (X axis). The magnetic field is configured to generate an effective magnetic field region in which the magnetic field is oriented in the X-axis and Z-axis directions. The axis perpendicular to the Z axis is the Y axis, In the XY plane, The load is deflected at the deflection angle φ with respect to the X axis at the deflection starting point Q and enters the effective magnetic field region. The electron beam is deflected by the effective magnetic field region and directed to the isotropic plane at an irradiation angle θ relative to the X axis. Irradiated to the center, Any point P2 on the boundary of the effective magnetic field region on the exit side of the charged particle beam is Equal distance from the center １ Located at The point P1 and the point P2 on the boundary of the effective magnetic field region on the incident side of the charged particle beam are spaced apart by a radius r ２ and on an arc with a central angle of (θ+φ), The distance R between the deflection origin Q and the point P1 is If the distance between the two points is L, then the relation (4): [Equation 1] 4. The charged particle beam irradiation system according to claim 1, wherein the above condition is satisfied.

5. The charged particle beam according to any one of claims 1 to 3, comprising an accelerator for generating the charged particle beam. Beam therapy system.

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