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 treatment system.

Background Art

[0002] Conventionally, particle beam therapy has been performed in which a charged particle beam (also referred to as a "particle beam") accelerated to high energy is irradiated onto cancer or any malignant tumor to treat the malignant tumor. When a charged particle beam is irradiated onto an object, energy (dose) is imparted to the object along the path of the charged particle beam within the object. When dose is imparted concentratedly to a limited region (target) inside the object, the concentration of the dose is enhanced by irradiating the charged particle beam from various directions so that the charged particle beam overlaps the target.

[0003] Patent Document 1 discloses a charged particle beam irradiation device provided with a converging electromagnet that deflects a charged particle beam incident from a wide angular range and converges it to an isocenter. Patent Document 2 discloses selecting a plurality of independent beam paths in the beam path in the treatment room.

[0004]

Prior Art Documents

Patent Documents

Patent Document 1

[0005]

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the same treatment room (in Patent Document 1, the area where the beam travels downstream from the deflection starting point Q) ​A charged particle beam irradiation device has multiple beam paths for irradiating charged particle beams within it. In this case, when irradiating with a charged particle beam through a predetermined beam path, 1. A charged particle beam travels along an unintended beam path and is unintentionally irradiated to a patient. There is a risk of that happening.

[0006] In view of these circumstances, the present invention provides a charged particle beam that prevents such unintended irradiation. The objective is to provide an irradiation device. [Means for solving the problem]

[0007] The present invention includes the following embodiments [1] to [5]. [1] A charged particle beam irradiation device, The charged particle beam emitted from the accelerator (20) is transported to a single isocenter (O). A beam transport system (30) having multiple beam paths, It is positioned on the 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 passing charged particle beam and Equipped with, The beam transport system (30) is A deflection electromagnet (33) that deflects a charged particle beam, It is installed downstream of the aforementioned distribution electromagnet and passes through the multiple beam paths or the multiple beam paths. The charged particle beam passing through one of the beam paths is brought into the isocenter. A converging electromagnet (40) and Equipped with, The first beam path is such that when the distribution electromagnet is not excited, the charged particle beam This is a beam path that passes through the distribution electromagnet and irradiates the isocenter, When the charged particle beam is passed through the first beam path, the shielding body (110) A charged particle beam irradiation device that retreats from the first beam path so that the charged particle beam can pass through. 〔2〕 The shielding body is located downstream of the beam splitting electromagnet and upstream of the focusing electromagnet, and is arranged. The first beam path is on the line passing through the deflection starting point Q of the beam splitting electromagnet and the isocenter. The charged particle beam irradiation device according to 〔1〕. 〔3〕 A charged particle beam irradiation device, having a beam transport system (30) that transports a charged particle beam emitted from an accelerator (20) toward a single isocenter (O), and first and second shielding bodies (110a, 110b) that move along a guide rail (55) along which an irradiation nozzle (50) moves and are arranged so as to sandwich the irradiation nozzle (50) in the direction along the guide rail. and includes. The beam transport system includes a beam splitting electromagnet (33) that deflects a charged particle beam, and a focusing electromagnet (40) that is installed downstream of the beam splitting electromagnet and converges the charged particle beam passing through the plurality of beam paths toward the isocenter. and includes. The first and second shielding bodies are detachably attached to the irradiation nozzle and move as the irradiation nozzle moves, but are fixed when they come to the position on the first beam path of the guide rail. It is configured as such. The first beam path is a beam path through which a charged particle beam passes through the beam splitting electromagnet and the focusing electromagnet and is irradiated to the isocenter when the beam splitting electromagnet is not excited. The charged particle beam irradiation device. 〔4〕 The deflector electromagnet deflects the charged particle beam at a deflection angle φ of 1 degree or more at the deflection starting point Q, The focusing electromagnet includes a pair of coils arranged so as to sandwich the path of the charged particle beam, When a current is input to the pair of coils, an effective magnetic field region is configured to be generated in a direction (Z-axis) orthogonal to the traveling direction (X-axis) of the charged particle beam. Here, an axis orthogonal to the X-axis and the Z-axis is defined as the Y-axis, In the XY plane, at the deflection starting point Q, it is deflected at a deflection angle φ with respect to the X-axis and enters the effective magnetic field region. The charged particle beam is deflected by the effective magnetic field region and irradiated onto the isocenter at an irradiation angle θ with respect to the X-axis, Any point P2 on the boundary on the emission side of the charged particle beam in the effective magnetic field region is at a position equidistant r1 from the isocenter, A point P1 on the boundary on the incident side of the charged particle beam in the effective magnetic field region and the point P2 are on an arc with a radius r2 and a central angle (θ + φ), When the distance R between the deflection starting point Q and the point P1 is set to L, which is the distance between the deflection starting point Q and the isocenter, the relational expression (4): is satisfied. The charged particle beam irradiation device according to any one of [1] to [3].

Equation

Brief Description of Drawings

[0008] [Figure 1] ​​​​This is a schematic diagram of a charged particle beam irradiation apparatus according to the first and second embodiments of the present invention. [Figure 2A] This is a schematic diagram of a charged particle beam irradiation apparatus according to the first embodiment. [Figure 2B] This is an explanatory diagram of the conventional technology. [Figure 2C] This is a schematic diagram of a charged particle beam irradiation apparatus according to the first embodiment. [Figure 2D] This is a schematic diagram of a charged particle beam irradiation apparatus according to the first embodiment. [Figure 3] This is a schematic diagram of the convergent electromagnet according to the second embodiment. [Figure 4] This figure illustrates the formation of the effective magnetic field region according to the second embodiment. [Figure 5] This is a schematic diagram of the shielding mechanism according to the second embodiment. [Figure 6] This is a diagram illustrating the movement of the shielding body according to the second embodiment. [Figure 7] This is a flowchart of the irradiation control of the charged particle beam irradiation apparatus according to the second embodiment. [Figure 8] This is a schematic diagram of a charged particle beam irradiation apparatus according to the third embodiment. [Modes for carrying out the invention]

[0009] Figure 1 is a schematic diagram of the charged particle beam irradiation apparatus 10 according to the present invention. Figure 1(a) This is a diagram of the first embodiment of the present invention, showing the area downstream from the deflection starting point Q where the beam is propagating. Within A, there are multiple independent beampaths that irradiate a single isocenter O with a charged particle beam. This is a charged particle beam irradiation device in which such a device exists. Also, Figure 1(b) shows the second embodiment of the present invention. This is a diagram relating to the area where the beam propagates downstream from the deflection starting point Q, and one isosceles There are multiple continuous beam paths that irradiate the center O with a charged particle beam. It is an irradiation device.

[0010] A charged particle beam irradiation device 10 according to one embodiment of the present invention is used to irradiate charged particles emitted from an accelerator 20 A beam transport system having multiple beam paths that transport a charged particle beam toward the isocenter O. The transmission system 30 is located on the first beam path among the multiple beam paths of the beam transport system 30. A shielding mechanism that blocks (shiels) the progression of the charged particle beam as it passes through the first beam path. It is equipped with 100 shielding bodies 110. To pass a charged particle beam through the first beam path In this case, the shielding body 110 moves off the first beam path to allow the charged particle beam to pass through. (Evacuate). The first beam path is when the distribution electromagnet 33 is not excited, charged particles The beam passes through the distribution electromagnet 33 (or the distribution electromagnet 33 and the focusing electromagnet 40), and isosceles This is the beam path irradiated onto center O. That is, the first beam path is the distribution electromagnet 33 It lies on a 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. It further includes the following. In addition, the charged particle beam therapy system according to one embodiment of the present invention is accelerated It includes a device 20 and a charged particle beam irradiation device 10.

[0012] The accelerator 20 is a device that generates charged particle beams, such as a synchrotron or a cyclonic accelerator. It is a rotron, or linear accelerator. The charged particle beam generated in accelerator 20 is transported by the beam transport The signal is focused to the isocenter O via transmission system 30.

[0013] The beam transport system 30 includes a distribution electromagnet 33 that deflects the charged particle beam, and distribution electromagnet 3 Located downstream of 3, it directs the charged particle beam through one of several beam paths. It includes a focusing electromagnet 40 that focuses the beam towards the center O. Furthermore, the beam transport system 30 includes: One or more charged particle beam adjusting means 31, vacuum duct 32, fan-shaped vacuum duct 34, and A beam irradiation nozzle 50 may be further included. The entire beam path is within the vacuum duct 32. The isosceles gases, which pass through the vacuum regions within the distribution electromagnet 33 and the focusing electromagnet 40, into the atmosphere of the treatment room. This leads to Inter 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. It consists of the following. The control device 60 receives irradiation information transmitted by the irradiation computer (not shown). In accordance with the report, the equipment involved in irradiation is controlled. Shielding drive control unit 64 and shielding position detection unit 66 moves the shielding body 110 to a predetermined position, and the control device 60 moves the shielding body 110 It monitors the position and controls the emission of the charged particle beam.

[0015] A first embodiment of the present invention will be described. Figure 2A shows a particle beam therapy room with two treatment rooms. This is a schematic diagram of the facility. Each treatment room is equipped with a distribution electromagnet 33 (33A, 33B in the diagram). Considering a point, multiple isocenters converge on one isocenter O (OA, OB in the diagram) within the treatment room. It has a vertical beam path. Note that in Figures 1 and 2A-C, the parentheses after the reference numerals Regarding the numbers inside, (0A) means zero amperes, and (0) represents charged particles from the 0-degree direction. (90) is attached to elements such as electromagnets used when irradiating with a beam, and the charge is from the 90-degree direction. (45) is attached to elements such as electromagnets used when irradiating with a particle beam, and is from the 45-degree direction. These are attached to elements such as electromagnets used when irradiating with a charged particle beam.

[0016] The charged particle beam emitted from accelerator 20 and transported is deflected at the starting point Q (QA in the figure). QB) The distribution electromagnets 33 (33A, 33B in the figure) divide the traffic into two paths, and The beam is emitted from the intended irradiation angle by the bundle of electromagnets 40. That is, the deflection starting point Q (Q- in the figure) In A and QB), the irradiation paths are from 0, 45, and 90 degrees relative to the beam propagation axis. They are distributed. For example, if the irradiation angle is selected at 45 degrees in treatment room B, distribution electromagnet 3 The electromagnets, including 3B and the convergence electromagnet 40B (45), have their excitation current values ​​and other settings changed in advance. This is done. Once all settings have been switched, the irradiation of the charged particle beam will begin. The beam path of the beam transport system 30 shown in Figure 2A is the set path 220 (intended This is the irradiation path. Note that in this case, treatment room A is not selected, so the irradiation path is It is not included.

[0017] Using Figure 2B, when the shielding body 110 is not used, the distribution electromagnet 33 does not function unintentionally. Let's explain the problems that arise when the irradiation angle is 45 degrees or 90 degrees. Despite being selected, that is, the excitation current to the distribution electromagnet 33B is set to 0A (zero amperes). Despite being instructed to use a value other than the specified one, the excitation current of the distribution electromagnet 33B unintentionally became 0A. If this happens, the charged particle beam incident on the distribution electromagnet 33B will be deflected by the distribution electromagnet 33B. The beam is not directed and proceeds along an irradiation path in the 0-degree direction. At this time, the beam transport shown in Figure 2B The charged particle beam travels along the first beam path 210, indicated by the thick arrow line in transmission system 30, and isospheric Unintended illumination of the turret's out-of-bounds area occurs.

[0018] If the configured path 220 is different from the first beam path 210, the charged particle beam is isospheric The conditions for being ejected towards Ter O are that the shielding body 110 is placed in the first beam path 210. This is the case. On the other hand, if the configured path 220 is the same path as the first beam path 210, Opening the beam path, that is, the shielding body 110 moves away from the first beam path 210. This is a condition. The position of the shielding body 110 is monitored by the control device 60. For example, as shown in Figure 2C. In this example, even though an irradiation angle of 45 degrees was selected in treatment room B, the electromagnetic distribution was dispersive. Even if the excitation current of transistor 33B unintentionally becomes 0A (zero amperes) The shield 110B blocks the charged particle beam traveling along the first beam path 210, and isolates the beam. This prevents the device from reaching Center OB. Note that treatment room A is not selected, therefore, it is blocked. The position of the shield 110A may or may not be included in the irradiation conditions for treatment room B.

[0019] If the irradiation angle is selected to be 0 degrees, the set path 220 (intended irradiation path) is the first This will be the same path as beam path 210. In this case, as shown in Figure 2D, shielding 110B By evacuating from the designated path 220 (first beam path 210), the isocenter OB is reached. This makes irradiation possible.

[0020] A second embodiment relating to the present invention will be described. The beam of the charged particle beam irradiation device 10 The transport system 30 starts from the distribution electromagnet 33 and converges to one isocenter O in the treatment room. It has multiple continuous beam paths. At least the distribution electromagnet 33 and the focusing electromagnet 40 By various combinations of excitation current values ​​of the two deflection electromagnet power supplies, the desired irradiation angle can be achieved. You can select this. Figure 3 is a schematic diagram of the distribution electromagnet 33 and the converging electromagnet 40 in the second embodiment. That is the case.

[0021] The beam transport system 30 generates multiple beam diameters using the distribution electromagnet 33 and the focusing electromagnet 40. The path includes multiple beam paths, which, as described later, are used to distribute charged particle beams using the distribution electromagnet 33. It varies depending on the deflection angle φ and the irradiation angle θ of the charged particle beam by the focusing electromagnet 40.

[0022] Of the multiple beam paths, the first beam path 210 was unintentionally energized by the distribution electromagnet 33. If not present, the charged particle beam will naturally propagate towards the isocenter O. This is the beam path. More specifically, the first beam path 210 is when the distribution electromagnet 33 is excited. When they are not present (not functioning), the charged particle beam is directed by the distribution electromagnet 33 and the focusing electromagnet 40 This is the beam path that passes through and irradiates the isocenter O. In Figure 4, the first beam In path 210, despite being set to φ≠0 degrees and θ≠0 degrees, the distribution electromagnet 33 is excited. This is the beam path when a charged particle beam is not magnetized and travels at φ=0 degrees and θ=0 degrees. Furthermore, the setting path 220 where φ=0 degrees and θ=0 degrees is the first path when φ≠0 degrees and θ≠0 degrees. This will have the same beam path as path 210.

[0023] A charged particle beam is emitted from accelerator 20 towards isocenter O via the set path 220. The given condition is that a shielding body is placed in the first beam path 210. φ≠0 degrees and When irradiation at θ≠0 degrees is selected, the shielding 110 is always placed in the first beam path 210. It is positioned to block the light. On the other hand, when irradiation with φ=0 degrees and θ=0 degrees is selected, Therefore, since the set path 220 is the same path as the first beam path 210, the charged particle beam will proceed To enable this, the shielding body 110 is moved out of the configured path 220 (first beam path 210). At this time, the position of the shielding body 110 is monitored by the control device 60. If it moves out of its designated position, the status of the shield 110 becomes uncertain, and the beam immediately It will be blocked.

[0024] The accelerator 20, the charged particle beam adjustment means 31, and the distribution electromagnet 33 are located in the vacuum duct 32. The distribution electromagnet 33 and the focusing electromagnet 40 are connected by the fan-shaped vacuum duct 34 shown in Figure 1. It is continued. By making the shape of the fan-shaped vacuum duct 34 in the XY plane fan-shaped, it is possible to achieve a degree of 1 degree or less. Furthermore, even if a 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, is smaller than rectangular ones, and reduces the installation space required.

[0025] The charged particle beam is generated in the upstream accelerator 20, and to avoid (or reduce) attenuation For this purpose, it proceeds through the vacuum ducts 32 and 34, and is adjusted by the charged particle beam adjustment means 31. The energy is then guided to the distribution electromagnet 33 and the converging electromagnet 40.

[0026] The charged particle beam adjustment 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, and charged particles Quadrupole electromagnets for adjusting the beam shape of the beam, and the beam position of the charged particle beam. Steering electromagnets and other components are used as appropriate, depending on the specifications, to fine-tune the steering.

[0027] Multiple beam paths in the beam transport system 30 are determined by the deflection angle φ and focusing electromagnetic field of the distribution electromagnet 33. It varies depending on the irradiation angle θ by Stone 40. The optical elements that the charged particle beam is affected by also vary depending on the deflection angle φ. The beam shape of the charged particle beam at the isocenter O changes depending on the irradiation angle θ. It may vary depending on φ and the irradiation angle θ. To address this variation, for example, a focusing electromagnet 4 The charged particle beam adjustment means 31, located upstream of 0, is adjusted for each deflection angle φ and irradiation angle θ. Adjust the beam shape of the charged particle beam at the isocenter O to be appropriate. You may do so.

[0028] The distribution electromagnet 33 continuously deflects the charged particle beam at a deflection angle φ and loads the particle beam onto the focusing electromagnet 40. It is configured to emit an electric particle beam. The focusing electromagnet 40 is an isocenter The system is configured to continuously change the irradiation angle θ of the charged particle beam directed towards O. Prior patents by the applicant (Patent No. 6364141, Patent No. 6387476, and Patent No. 673 The contents of Patent No. 4610 are incorporated herein by reference. Distribution electromagnet 33 and convergence electromagnet An example of magnet 40 is described below.

[0029] The irradiation nozzle 50 is located in the treatment room where treatment using a charged particle beam is performed, and is in the XY plane. In the area where the focusing electromagnet 40 generates an effective magnetic field region, the shape of the exit side (boundary shape) is aligned with the shape of the exit side. It moves continuously along the id rail 55 (Figure 8). From the exit side of the effective magnetic field region, the eye The charged particle beam directed towards center O passes through the irradiation nozzle 50, and the irradiation nozzle 50 The direction, shape, and energy 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 modulator. It is equipped with a stage (not shown). The scanning electromagnet adjusts the amount and direction of the current flowing through it to illuminate The direction of the charged particle beam emitted from the nozzle 50 is finely adjusted, and the charged particle beam is charged within a relatively narrow range. The beam monitor 51 enables scanning of the charged particle beam. The system observes and measures the dose, beam position, and flatness. The energy modulation means uses charged particles. The energy of the particle beam is adjusted to control the depth to which the charged particle beam reaches the patient. Energy modulation means include, for example, range modulators, scatterers, ridge filters, patient coagulation. This includes a meter, patient bolus, applicator, or a combination of these.

[0031] Figure 3(a) is a schematic diagram of the focusing electromagnet 40. It differs for each deflection angle φ and convergence angle θ. Multiple beam paths are also depicted. Here, the direction of propagation of the charged particle beam is the X-axis, and the focusing current is drawn. The direction of the magnetic field generated by magnet 40 is defined as the Z-axis, the X-axis, and the direction perpendicular to the Z-axis as the Y-axis. The electromagnet 40 receives 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 be focused towards the isocenter O. Note that in Figure 4, The irradiation nozzle 50 is omitted, and for the sake of simplicity, the isocenter O is the origin of the XYZ space. The point is defined as a point, with the upstream side (accelerator side) as the positive direction of the X-axis.

[0032] The deflection angle φ ranges from greater than -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 may be different (asymmetrical). Example For example, the maximum deflection angle on the positive side (φ=φMAX) is 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees Among degrees 35, 40, 45, 50, 60, 70, 80, and 85 degrees Alternatively, the maximum deflection angle on the negative side (φ=-φMAX) can be set to -10 degrees, -15 degrees, and -20 degrees. degree, -25 degree, -30 degree, -35 degree, -40 degree, -45 degree, -50 degree, -60 degree, -70 degree It may be any of degrees, -80 degrees, or -85 degrees.

[0033] The focusing electromagnet 40 comprises one or more pairs of coils, which are used to guide the charged particle beam. The direction is perpendicular to the direction of the beam's deflection angle φ (Z-axis direction in the diagram). A uniform magnetic field is generated (effective magnetic field regions 41a, 41b), and the path of the charged particle beam is flanked by it. It is positioned as shown in Figure 3. The effective magnetic field region generated by one pair of coils of the converging electromagnet 40 is shown in Figure 3. As shown in a), it has a crescent shape in the XY plane, and its details will be described later. The gap between opposing coil pairs through which the charged particle beam passes is (distance in the Z-axis direction), Because it is sufficiently small compared to the range over which the charged particle beam spreads in the XY plane, here we have charged particles The spread of the sub-beam in the Z-axis direction is not considered.

[0034] Figure 3(b) is a cross-sectional view of the focusing electromagnet 40 along line AA. The focusing electromagnet 40 is preferably It comprises at least two sets of coil pairs 44a and 44b. Inside coils 44a and 44b Each incorporates magnetic poles 45a and 45b, and yokes 46 are connected to magnetic poles 45a and 45b. The converging electromagnet 40 is connected to a power supply unit (electromagnet control unit 122, described later). Then, 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 region 41) are formed. .) is formed.

[0035] Note that 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 range of the negative (-Y axis direction) If the range of the deflection angle φ is asymmetrical, then the effective magnetic field regions 41a and 41b will also be asymmetrical accordingly. By forming it in this way, the unused effective magnetic field region can be reduced.

[0036] The deflection angle φ of the charged particle beam, which is deflected by the distribution electromagnet 33 and incident on the converging electromagnet 40. The range is from the maximum positive deflection angle (φ=φmax) to the maximum negative deflection angle (φ=-φmax). The range is such that the maximum positive deflection angle φmax is an angle between 10 degrees and less than 90 degrees, and the negative range is such that the maximum positive deflection angle φmax is an angle between 10 degrees and less than 90 degrees. The maximum deflection angle of the eggplant, -φmax, is an angle greater than -90 degrees and less than or equal to -10 degrees. The deflection angle φ is described below. The irradiation angle θ is the angle of the path of the charged particle beam relative to the X-axis in the XY plane.

[0037] A charged particle beam incident in the positive deflection angle range (φ=0 to φmax) is directed to the first coil. The energy is deflected by the effective magnetic field region 41a opposite to 44a, passes through the irradiation nozzle 50, and reaches the isocenter O It is irradiated. Charged particles are incident within a negative deflection angle range (φ=less than 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 isocenter O is irradiated. The direction of the magnetic field in the effective magnetic field region 41a and the effective magnetic field region 41b The directions are opposite to each other. Furthermore, the focusing electromagnet 40 is located at a deflection angle φ=0 from the distribution electromagnet 33. The charged particle beam incident on the field is in either the effective magnetic field region 41a, 41b, or both regions 41a. The light passes between 41b and converges on 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 distribution electromagnet 33. The distribution electromagnet 33 directs the direction of travel of the charged particle beam supplied from the accelerator (not shown). A magnetic field is generated that is perpendicular to the X-axis (in the diagram) and directed towards the Z-axis (in the diagram), and a charged particle beam passes through it. It comprises an electromagnet that deflects the magnetic field and a control unit that controls the strength and direction of the magnetic field (neither is shown in the diagram). (Diagram) The distribution electromagnet 33 controls the strength and direction (Z-axis direction) of the magnetic field, thereby controlling the XY plane. The charged particle beam is deflected, and the deflected charged particle beam at the deflection starting point Q with a deflection angle φ is collected. The beam is emitted from the bundle of electromagnets 40. Here, the deflection origin Q and the isocenter O are on the X-axis.

[0039] Referring to Figure 4, the formula for forming the effective magnetic field region 41a of the converging electromagnet 40 is as follows: I will explain this. Note that in this embodiment, the deflection of the charged particle beam in the Z-axis direction is not considered. Next, we will explain the formation of the effective magnetic field region in the XY plane. Effective magnetic field region of the focusing electromagnet 40 We will now explain region 41a, but the same applies to the effective magnetic field region 41b, so we will omit the explanation. To abbreviate.

[0040] First, the boundary of the effective magnetic field region 41a on the discharge side 43 of the charged particle beam of the focusing electromagnet 40 is, The range is determined to be equidistant r1 from the isocenter O. Next, the convergent electromagnetic The boundary of the effective magnetic field region 41a on the incident side 42 of the charged particle beam of stone 40 is given by the relation described later ( Based on 1) to (5), a hypothetical deflection event occurs at a predetermined distance L from the isocenter O. The incident charged particle beam is deflected at point Q with a deflection angle φ and then converges at the isocenter O. It can be determined as follows. Here, the hypothetical deflection starting point Q is the center of the distribution electromagnet 33 and the charged particle beam This point assumes that Mu receives a kick with a deflection angle φ over an extremely short distance.

[0041] The charged particle beam, transported at a deflection angle φ, reaches the boundary of the effective magnetic field region 41a on the incident side 42. Entering from any point P1 above, perform circular motion with radius of curvature r2 within the effective magnetic field region 41a (this The central angle at this time is (φ+θ). ) Point P on the boundary of the effective magnetic field region 41a on the output side 43. It exits from point 2 and is directed towards the isocenter O. In other words, point P1 and point P2 are within radius r. It lies on the arc of a circle with a central angle of (φ+θ).

[0042] We assume an XY coordinate system with the isocenter O as the origin in the XY plane. Point 43 on the exit side. 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), deflection angle φ, and distance R between point Q and point P1 in 2 are related to the following: It can be found from equations (1) to (4).

number

[0043] Here, a magnetic field with a uniform magnetic flux density B is generated in the effective magnetic field region 41a, and charged particles B If the momentum of the particle is p (approximately dependent on the accelerator) and the charge is q, then the force deflected in a magnetic field is... The radius of curvature r² of the electric particle beam is given by equation (5).

number

[0044] Based on the above relational equations (1) to (5), the coil pair 44a and magnetic pole 45a of the converging electromagnet 40 By adjusting the shape and arrangement and adjusting the current flowing through the coil pair 44a, the effective magnetic field region 4 The shape of the boundary of 1a can be adjusted. That is, on the boundary of the effective magnetic field region 41a on the output side 43 A boundary is defined such that the distance between any point P2 and the isocenter O is equidistant 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 determined. The distance R between point P1 on the boundary of field region 41a and the deflection starting point Q is given by equation (4). Next, the boundary of the effective magnetic field region 41a on the incident side 42 is determined. The maximum value of φ in equation (3) is the maximum The deflection angle becomes φmax. Note that this is not limited to charged particles passing through the deflection origin Q. The beam will converge to the isocenter O even without being deflected by the focusing electromagnet 40. By adjusting the arrangement of the deflection starting point Q, the converging electromagnet 40, and the isocenter O, the device configuration This is preferable because it makes things simpler.

[0045] The boundary between the effective magnetic field regions 41a and 41b of the converging electromagnet 40, as determined above, is the charge This is the ideal shape for focusing a particle beam onto the isocenter O. However, in reality, Even if there are deviations 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 transmitted to the power supply unit (e.g., irradiation). The control unit 121) stores the data so that the deflection angle φ and the current amount of the converging electromagnet 40 are linked. By controlling them, the charged particle beam can be deflected to align with the isocenter O. This can be done. Also, if the non-uniformity of the magnetic field distribution can be predicted in advance, the focusing electromagnet 40 By correcting the shape and arrangement of the coil pairs 44a and 44b and the magnetic poles 45a and 45b, the charge It is also possible to fine-tune the trajectory of the particle beam.

[0046] The control device 60 is a computer equipped with an arithmetic processing unit and a memory unit, and is made of hardware and software. Functional units realized through collaboration with software include the irradiation control unit 62 and the shielding drive control unit. The irradiation control unit 62 includes 64 and a shielding position detection unit 66. The irradiation control unit 62 controls the accelerator 20 and beam transport. Each element of system 30 (charged particle beam adjustment means 31, distribution electromagnet 33, focusing electromagnet 40, and The irradiation nozzle 50) is controlled. The shield drive control unit 64 controls the shield 110 of the shielding mechanism 100. The movement is controlled, and the shield position detection unit 66 determines the position of the shield 110. Irradiation control unit 62, the shield drive control unit 64, and the shield position detection unit 66 are configured as the same computer. They may be configured as separate computers, or they may be configured as individual computers.

[0047] Figure 5 is a schematic diagram of the shielding mechanism 100. The shielding mechanism 100 is designed to block the progress of the charged particle beam. A shielding body 110 that blocks the row, a shaft 112 connected to the shielding body 110, and a shaft A fixed end 113 is provided with an opening through which the to 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 It includes a drive mechanism 117 that drives 6.

[0048] The shielding body 110 of the shielding mechanism 100 is placed within the vacuum region of the beam transport system 30. For example, The shielding body 110 is placed inside the fan-shaped vacuum duct 34.

[0049] The shielding 110 blocks the charged particle beam that has the maximum energy required for treatment. It is made of a material that can be compressed, and can sufficiently block the spread of charged particle beams relative to the YZ plane. It has a shape that allows it to penetrate deep into the patient's body (about 30 cm). For example, the energy of the charged particle beam penetrates deep into the patient's body (about 30 cm). It has sufficient energy to penetrate to tumors located in areas equivalent to the thickness of water. For a wire, it's around 230 MeV, and for a carbon wire, it's about 430 MeV / u.

[0050] The material of the shielding body 110 is such that even when irradiated with a charged particle beam, the shielding body 110 remains in place. This reduces the deterioration of the vacuum level in the vacuum region (for example, the fan-shaped vacuum duct 34), and also reduces the load Neutrons, gamma rays, and secondary charged particles are produced by the nuclear reaction between the electric particle beam and the shield 110. A material that can reduce the effects of radiation exposure on patients is desirable. The focusing electromagnet 40 is made of a superconducting electromagnetic material. When creating a stone, the vacuum chamber of the focusing electromagnet 40 is kept at an extremely low temperature of a few Kelvin (K). Therefore, the gas emission rate from the material surface of the shielding body 110 is extremely low, and the material has a low emissivity. (For example, a material that does not contain oxygen) is preferable. An example of the material for the shielding body 110 is an electronically tight material. These include oxygen-free copper and stainless steel with a high degree of purity (high water equivalent thickness).

[0051] The shape of the shielding body 110 is determined by the beam size of the charged particle beam, the trajectory error on the beam path, and Considering factors such as beam energy, it is desirable to make it larger than the beam size. Except when irradiating with a charged particle beam in the first beam path, the shielding body 110 is... Because it will be constantly positioned in the path, it will interfere with charged particle beams passing through other beam paths. Make it a size that won't cause problems.

[0052] When no external force is applied to the shielding body 110, the biasing member 114 causes the shielding body 110 to be in the first position. The shaft 112 is biased so that it is positioned on the path 210, for example, These are seals and magnetic seals (Figure 6(a)). The drive mechanism 117 is, for example, an air compressor and It is equipped with a compression cylinder and the like. The drive mechanism 117 receives control signals from the shield drive control unit 64. Then, the shaft 116 is driven (pulled), and the movable end 115 moves the biasing member 114 By extending and moving the shaft 112, the shielding body 110 is moved. The motion control unit 64 removes the stress applied by the drive mechanism 117, thereby making the shielding body 110 a biasing member. Moved by 114, it returns to its insertion position on the first beam path 210.

[0053] The shielding position detection unit 66 receives a drive signal from the shielding drive control unit 64 and / or the shielding position detection unit 66. Upon receiving a signal from a sensor attached to the shielding body 110, the shielding body 110 moves to the first beam path. Determine whether it is located on 210 or not. The sensor can be either contact or non-contact. Insertion and Retraction As an example of a monitoring mechanism for the escape position, the insertion and retraction position of the shielding body 110 is controlled by a limit switch (not shown). The switch is detected by a rail (not shown) that guides the extension and retraction of the biasing member 114. (As shown) It is provided on the above, etc., and the movable end 115 stops at the position (on the first beam path 210) It is positioned at the insertion position (IN) and the retraction position (OUT) from the first beam path 210. 115 is equipped with a position detection bar (not shown), and the position detection bar acts as an IN switch or an OUT switch. The position of the shielding body 110 is detected by contact with the switch. Contact with both switches If not done, the state becomes undefined.

[0054] The movement of the shielding body 110 will be explained using Figure 6. Figure 6(a) shows the multiple beam transport system 30. Of the several beam paths, the set path 220, where φ≠0 degrees and θ≠0 degrees, passes through the isocenter O The charged particle beam irradiated onto the object is drawn. At this time, the distribution electromagnet 33 and the focusing electromagnet 40 (effective) The magnetic field region 41a) is energized, and the shielding body 110 receives stress applied by the drive mechanism 117. It is not received and is inserted onto the first beam path 210.

[0055] Figure 6(c) shows one of the multiple beam paths of the beam transport system 30 where φ=0 degrees and θ=0 degrees. The diagram shows a charged particle beam irradiated onto the isocenter O via the set path 220. The sub-electromagnet 33 and the converging electromagnet 40 (effective magnetic field region 41a) are 0A, and the set path 220 The signal passes through the distribution electromagnet 33 (more specifically, the deflection origin Q) and the focusing electromagnet 40, and isospheric This is the beam path irradiated onto TER O. In this case, the charged particle beam follows the set path 220 (the To allow the beam path (210) to pass through, the shielding body 110 is subjected to stress by the drive mechanism 117. Upon receiving the applied signal, it moves away from the configured path 220 (first beam path 210).

[0056] The charged particle beam is directed to the isocenter O via beampaths other than the first beampath 210. When irradiated, that is, when the charged particle beam passes through the set path 220 where φ≠0 degrees and θ≠0 When irradiated, the shielding body 110 is inserted on the first beam path 210. The position detection unit 66 makes a determination, and the irradiation control unit 62 determines the result of the determination by the shielding body position detection unit 66. Following this, charged particle beams are irradiated through beam paths other than the first beam path 210. On the other hand, in the field where a charged particle beam is irradiated to the isocenter O through the first beam path 210 In other words, the charged particle beam is irradiated through a set path 220 where φ=0 degrees and θ=0. In this case, the shielding body 110 moved to a position away from the set path 220 (first beam path). The shielding position detection unit 66 determines the position and the irradiation control unit 62 Based on the judgment result, the charged particle beam is irradiated through the set path 220 (first beam path). To do so.

[0057] Thus, the distribution electromagnet 33 may malfunction due to the control device 60, the occurrence of an unstable control state, etc. If the magnet is not excited and the charged particle beam is not deflected in the intended direction at the deflection starting point Q (deflection Even at an angle φ=0 degrees, the shielding body 110 prevents the charged particle beam from passing through the first beam path 210. This prevents irradiation of the isocenter O (Figure 6(b)).

[0058] Furthermore, this applies not only when the distribution electromagnet 33 is not unintentionally excited (deflection angle φ = 0 degrees), but also when the distribution electric If the deflection by magnet 33 does not reach the intended angle (irradiation angle) (deflection angle φ < irradiation angle) The insertion position of the shielding body 110 is such that it blocks the charged particle beam passing through that beam path. The shielding mechanism 100 may be configured to include multiple shielding bodies 110. The probability that one or both of the distribution electromagnet 33 and the converging electromagnet 40 will perform an unintended action is Empirically, the most effective beam paths are identified, and shielding devices 110 are placed along each of these beam paths. The configuration is also acceptable.

[0059] Figure 7 is a flowchart of the irradiation control of a charged particle beam. The irradiation control unit 62 controls the charged Excitation of the electromagnet power supply, specifying the energy of the particle beam and the setting 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 another computer (in Receive from (as shown in the diagram) (Step S1).

[0060] The irradiation control unit 62 determines that the charged particle beam passes through the designated set path 220 to the isocenter. Each of the electromagnet group, including the distribution electromagnet 33 and the focusing electromagnet 40, is directed so as to irradiate O. The set value of the excitation current is transmitted to the power supply (not shown) (step S2). The irradiation control unit 62 load The irradiation nozzle 50 is used to irradiate the isocenter O with an electric particle beam. Move 50 (step S3).

[0061] The irradiation control unit 62 detects when the designated set path 220 is progressing with φ=0 degrees and θ=0 degrees. It is determined whether it is a path, i.e., the first beam path 210 (step S4).

[0062] If the specified configuration path 220 is the first beam path 210 (Yes in step S4) ), that is, when the excitation current of the distribution electromagnet 33 is set to 0A, the irradiation control unit 62 shields The body drive control unit 64 indicates that the shielding body 110 has moved away from the set path 220 (first beam path 210). A command is sent to cause the shielding body drive control unit 64 to set the shielding body 110 to the set path 22 Move it away from 0 (first beam path 210) (step S5). Note that shielding 110 is If the shielding body is located in a position away from the set path 220 (first beam path 210), then shielding body 1 There is no movement of 10. The shield position detection unit 66 detects that the shield 110 is in the retracted position. The system outputs this information and sends it to the irradiation control unit 62.

[0063] If the specified setting path 220 is not the first beam path 210 (No in step S4) ), the irradiation control unit 62 instructs the shield drive control unit 64 that the shield 110 moves to the first beam path 210 A command is sent to insert upwards, and in response, the shielding drive control unit 64 moves the shielding 110 to the first position. Insert it onto the beam path 210 (step S6). Note that the shielding body 110 is already on the first beam If inserted on the path 210, there is no movement of the shielding body 110. Shielding body position detection unit 6 6 detects that the shielding body 110 is located on the first beam path 210 and uses that information to control irradiation. Send to Department 62.

[0064] The irradiation control unit 62, based on information from the shielding position detection unit 66, determines that the shielding 110 is designated as If it is determined that it is in the correct position, and similarly if all devices involved in irradiation are determined to be set up, then irradiation will begin. The control unit 62 sends a charged particle beam emission request to the accelerator control unit 63, and the signal triggers Next, the accelerator control unit 63's charged particle beam emission permission signal is activated, and the charged particle beam is emitted. Then, the isocenter O is irradiated with a charged particle beam (step S7).

[0065] During irradiation, the shielding position detection unit 66 controls the position of the irradiating body 110 at regular time intervals. The signal is transmitted to the control unit 62, and the irradiation control unit 62 monitors the position (step S8). Shielding If there is no change in the position of 110, irradiation will continue as is (Yes in step S8). ). When the dose to be irradiated based on the irradiation information is reached (step 9), the irradiation is considered complete. Example For example, when the set path 220 is the first beam path 210 (φ=0 degrees and θ=0 degrees), evacuate. If the position has moved, or if the set path 220 is not the first beam path 210 (φ If the shielding body 110 moves from its insertion position (where ≠0 degrees and θ≠0 degrees), the shielding body 110 will be in an undefined state (S No. at step S8. When an undefined state is detected, the interlock control (not shown) is notified. The accelerator control unit 63 immediately shuts off the charged particle beam (step S10).

[0066] The charged particle beam irradiation apparatus 10 of this embodiment has a charged particle beam that passes through a first beam path 210 Except when passing through, the shielding body 110 is always located on the first beam path, therefore the first beam This prevents unintended irradiation of the isocenter O with a charged particle beam through the path. Here, the first beam path 210 is used when the distribution electromagnet 33 is not excited, and charged particles are transmitted. The beam passes through the distribution electromagnet 33 and / or the focusing electromagnet 40 and is irradiated onto the isocenter O. This is a beam path. Preferably, the first beam path 210 is such that the distribution electromagnet 33 is not excited. At that time, the charged particle beam passes through the distribution electromagnet 33 and / or the focusing electromagnet 40, This is the beam path that is directed to center O. Also, the shielding body 110 is the true beam transport system 30 It can be installed within the airspace, reducing the need for larger equipment. The shielding body 110 does not contain oxygen in its material. If it is made of a material (e.g., oxygen-free copper), nuclear reaction between the shield 110 and the charged particle beam. The resulting secondary particles (secondary charged particles, neutrons, gamma rays, and / or photons) can cause illness. This reduces the effects of radiation exposure on the person and the deterioration of the vacuum due to gas generation from the shielding 110.

[0067] In another embodiment of the present invention, the charged particle beam irradiation apparatus 10 includes a plurality of shielding bodies 110( The system comprises a first shielding body 110a and a second shielding body 110b, which are the true beam transport system 30 It is not located in the airspace, but is movable along the guide rail 55 on which the irradiation nozzle 50 moves. It is installed in the following. The guide rail 55 is incorporated by reference in Patent 63874 As described in issue 76, the shape of the output side of the effective magnetic field regions 41a and 41b of the converging electromagnet 40 follows It is provided as such.

[0068] Figure 8 is a schematic diagram of a third embodiment of the charged particle beam irradiation apparatus 10 according to this embodiment. Two shielding bodies 110a and 110b are installed on the guide rail 55 on which the irradiation nozzle 50 moves. They are positioned so as to sandwich the irradiation nozzle 50 in a direction along the guide rail 55. The upper side facing the paper is designated as shielding element 110a, and the lower side as shielding element 110b.

[0069] The shielding bodies 110a and 110b are movable along the guide rail 55. The shielding bodies 110a and 110b are means (for example, magnetic) that are detachably attached to the irradiation nozzle 50. A shielding mechanism (such as a stone, electromagnet, or detachable engaging means) is provided, and moves in accordance with the movement of the irradiation nozzle 50. 110a and 110b also move. However, shielding 110a or shielding 110b is guideless When beam 55 reaches a position on the first beam path 210, it is latched and fixed in that position. It is configured to remain in that position. Note that the shielding bodies 110a and 110b are motors, etc. Equipped with a drive device, it moves along the guide rail 55 under the control of the shielding drive control unit 64. It may be configured in this way.

[0070] The charged particle beam follows a set path 220 (first beam path 210) with φ=0 and θ=0. When the light passes through and irradiates the isocenter O (Figure 8(a)), shielding bodies 110a and 110b It is positioned near the irradiation nozzle 50.

[0071] The charged particle beam passes through the set path 220 through the effective magnetic field region 41a to the isocenter O When irradiated (Figure 8(b)), the shielding body 110b is positioned on the first beam path 210. The latch is fixed, and the shield 110a moves together with the irradiation nozzle 50. Effective magnetic field region 41 When a charged particle beam is irradiated through a beam path, the shield 110b is the first beam path It remains fixed on road 210.

[0072] On the other hand, the charged particle beam passes through the set path 220 through the effective magnetic field region 41b and isospheric When irradiated to the terminal O (Figure 8(c)), the shielding body 110a is positioned on the first beam path 210. The shielding body 110b is positioned and latched into place, and moves together with the irradiation nozzle 50. Effective magnetic field area When irradiating with a charged particle beam through a beam path passing through region 41b, the shield 110a is first beam It remains fixed on the route 210.

[0073] Thus, similar to the above embodiment, in this embodiment as well, φ=0 degrees and θ=0 degrees The charged particle beam is directed to the external setting path 220 (a beam path other than the first beam path 210). Even if the distribution electromagnet 33 does not unintentionally energize when irradiating the center O, Since shielding body 110a or shielding body 110b is always positioned on the first beam path 210, This prevents unintended irradiation with charged particle beams.

[0074] The dimensions, materials, shapes, relative positions of components, etc., described above apply to the present invention. The structure of the device or various conditions may be modified. Specific terms and embodiments used in the description. It is not intended to be limited to this, and those skilled in the art can use other equivalent components. The above embodiments can be modified in any way without departing from the spirit or scope of the present invention. Furthermore, it is also possible to express the features described in relation to one embodiment of the present invention, even if clearly Even if not mentioned above, it is possible to use it in combination with other embodiments. [Explanation of Symbols]

[0075] 10 Charged particle beam irradiation device 20 Accelerator 30 Beam Transport System 31 Charged particle beam adjustment means 32 Vacuum duct 33 Distribution electromagnet 34 Fan-shaped vacuum duct 40. Focusing electromagnet 50 irradiation nozzles 55 Guide rails 100 Shielding mechanism 110(110A, 110B) Shield 110a, 110b First and second shielding bodies

Claims

1. A charged particle beam irradiation system, The charged particle beam emitted from the accelerator (20) is transported to one isocenter (O). A beam transport system (30) having multiple beam paths, It is positioned on the first beam path among the plurality of beam paths, and passes through the first beam path. A shield (110) that blocks the progress of the passing charged particle beam and Equipped with, The beam transport system (30) is A distribution electromagnet (33) that deflects a charged particle beam, It is installed downstream of the aforementioned distribution electromagnet and passes through the multiple beam paths or the multiple beam paths. The charged particle beam passing through one of the beam paths is brought into the isocenter. A converging electromagnet (40) and Equipped with, The first beam path is such that when the distribution electromagnet is not excited, the charged particle beam This is a beam path that passes through the distribution electromagnet and irradiates the isocenter, The charged particle beam irradiation system further includes a set path through which the charged particle beam passes. The system includes an irradiation control unit that controls the distribution electromagnet and the focusing electromagnet based on irradiation information, If the setting path is not the first beam path, the shielding body is on the first beam path If it is not determined that the charged particle beam is present, irradiation with the charged particle beam is not permitted. Irradiation system.

2. The shielding body is located downstream of the distribution electromagnet and upstream of the converging electromagnet. Placed, The first beam path is a line passing through the deflection origin Q of the distribution electromagnet and the isocenter. The charged particle beam irradiation system described above, according to claim 1.

3. A charged particle beam irradiation system, A charged particle beam emitted from the accelerator (20) is directed towards one isocenter (O). A beam transport system (30) having multiple beam paths for transport, The irradiation nozzle (50) moves along the guide rail (55) on which it moves, The first and second are arranged so as to sandwich the irradiation nozzle (50) in a direction along the line Shielding (110a, 110b) and Equipped with, The aforementioned beam transport system is A distribution electromagnet (33) that deflects a charged particle beam, A charged particle beam is installed downstream of the aforementioned distribution electromagnet and passes through the plurality of beam paths. A focusing electromagnet (40) that focuses the energy towards the isocenter and Equipped with, The charged particle beam irradiation system further includes a set path through which the charged particle beam passes. The system includes an irradiation control unit that controls the distribution electromagnet and the focusing electromagnet based on irradiation information, The first and second shields are detachably attached to the irradiation nozzle, and the irradiation nozzle It moves in accordance with the movement, but when it comes to a position on the first beam path of the guide rail, the first It is configured to be fixed on the beam path, The first beam path is such that when the distribution electromagnet is not excited, the charged particle beam The beam diameter that passes through the distribution electromagnet and the focusing electromagnet and irradiates the isocenter It is a road, If the aforementioned setting path is not the first beam path, then one of the first and second shielding bodies is in front If it is determined that the object is not on the first beam path, irradiation with a charged particle beam is not permitted. The charged particle beam irradiation system.

4. The aforementioned distribution electromagnet deflects the charged particle beam at a deflection angle φ of 1 degree or more at the deflection starting point Q. The aforementioned focusing electromagnet comprises a pair of coils arranged to straddle the path of the charged particle beam, When current is input to the aforementioned pair of coils, they are perpendicular to the direction of propagation (X-axis) of the charged particle beam. It is configured to generate an effective magnetic field region where the magnetic field is oriented in the direction of the X-axis and The axis perpendicular to the Z-axis is defined as the Y-axis. In the XY plane, A load is deflected at the deflection starting point Q with a deflection angle φ with respect to the X axis and is incident on the effective magnetic field region. The electron particle beam is deflected by the effective magnetic field region, and the irradiation angle θ with respect to the X axis is The light was directed at the center, Any point P2 on the exit side boundary of the charged particle beam in the effective magnetic field region is the iso Equidistant from the center r １ It is located in the following position: Points P1 and P2 on the incident side boundary of the charged particle beam in the effective magnetic field region are, r ２ and lie on the arc of a circle with central angle (θ + φ), The distance R between the deflection starting point Q and the point P1 is the distance between the deflection starting point Q and the isocenter Let L be the distance between - and -. Then, equation (4): [Math 1] A charged particle beam irradiation system according to any one of claims 1 to 3, which satisfies the requirements.

5. Charged particle according to any one of claims 1 to 3, comprising an accelerator that generates a charged particle beam. Beam therapy system.

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