Particle beam irradiation system and particle beam irradiation method

Abstract

To reduce a total weight of a distributing electromagnet for deflecting an electric charge particle beam incident on an irradiation device body in a slit-type irradiation device.SOLUTION: A particle beam irradiation system 1 includes: a first distributing electromagnet 91 that is provided in a connection portion between a vacuum duct 8 and an extension duct 93 and deflects a heavy corpuscular ray B within a range of a first angle θ1 with a reference track K when a track of the heavy corpuscular ray B is not deflected as an original line; and at least one second distributing electromagnet 92 that is provided in a downstream side from the first distributing electromagnet 91 and further deflects the heavy corpuscular ray B that is deflected by the first distributing electromagnet 91 within a range of a second angle θ2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to particle beam irradiation technology. [Background technology]

[0002] Particle beam irradiation technology has been known for treating patients by irradiating the affected area with a charged particle beam. In particular, a charged particle beam irradiation system (slit-type irradiation system) has been proposed that can irradiate the charged particle beam at any angle toward the isocenter where the patient is placed, without using mechanical elements such as a rotating gantry. Such a charged particle beam irradiation system is equipped with a deflection magnet device that deflects the charged particle beam at any deflection angle during transportation from the accelerator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6364141 [Patent Document 2] Patent No. 6387476 [Patent Document 3] Patent No. 6775860 [Patent Document 4] Patent No. 6734610 Summary of the Invention [Problem to be solved by the invention]

[0004] The deflection electromagnet device included in a charged particle beam irradiation device (slit-type irradiation device) must deflect the charged particle beam with a larger deflection amplitude than a typical bending electromagnet, which results in an increase in size and weight. In particular, the manufacturing cost, transportation, and assembly of the deflection electromagnet device and its power supply become difficult, and the inductance also increases, which increases the generated voltage, making excitation and demagnetization difficult and increasing the cost of the power supply used for excitation. Furthermore, when heavy ion beams are used as charged particle beams, they are more difficult to bend than proton beams, so an even larger deflection electromagnet device must be used.

[0005] The embodiment of the present invention has been made in consideration of the above circumstances, and aims to reduce the total weight of the deflecting electromagnets used to deflect the charged particle beam incident on the irradiation device main body in a slit-type irradiation device. [Means for solving the problem]

[0006] A particle beam irradiation system according to an embodiment of the present invention includes: an expansion duct connected to a vacuum duct of a beam transport device that guides a heavy particle beam accelerated by an accelerator, the expansion duct expanding in a fan shape with a connection point with the vacuum duct as an apex; an irradiation device main body connected to the expanded part of the expansion duct, deflecting the heavy particle beam incident from the expansion duct and emitting the heavy particle beam at an arbitrary angle toward an isocenter from a slit extending in a circumferential direction around an isocenter where an irradiation target of the heavy particle beam is located; a first deflecting electromagnet provided at the connection point between the vacuum duct and the expansion duct, deflecting the heavy particle beam within a first angle range with a reference trajectory when the trajectory of the heavy particle beam is not deflected as an original line; and at least one second deflecting electromagnet provided downstream of the first deflecting electromagnet, further deflecting the heavy particle beam deflected by the first deflecting electromagnet within a second angle range. [Effects of the Invention]

[0007] According to the embodiment of the present invention, in a slit-type irradiation device, the total weight of the deflecting electromagnets for deflecting the charged particle beam incident on the irradiation device main body can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an overall configuration diagram showing a particle beam irradiation system. [Figure 2] FIG. 2 is a side view showing a slit-type irradiation device. [Figure 3] FIG. [Figure 4] FIG. 3 is a perspective view showing a first biasing electromagnet and a second biasing electromagnet. [Figure 5] FIG. [Figure 6] Graph showing the angular change of the beam orbit caused by the biasing magnet. [Figure 7] Graph showing the angular change of the beam orbit due to the biasing electromagnet and the effective magnetic field area. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a particle beam irradiation system and a particle beam irradiation method will be described in detail with reference to the drawings.

[0010] Reference numeral 1 in Fig. 1 denotes a particle beam irradiation system according to this embodiment. This particle beam irradiation system 1 is a so-called heavy ion cancer treatment device that irradiates a charged particle beam B, which is a beam using carbon ions as therapeutic radiation, onto a lesion tissue (cancer) of a patient P as an irradiation target to perform treatment. A particle beam irradiation method is carried out using this particle beam irradiation system 1.

[0011] Radiation therapy technology using the particle beam irradiation system 1 is called particle beam cancer therapy technology. This technology uses carbon ions to pinpoint cancer lesions (affected areas), damaging them while minimizing damage to normal cells. Charged particle beam B is defined as a beam using elements heavier than helium atoms.

[0012] Although the present embodiment exemplifies the charged particle beam B as a heavy particle beam using carbon, other embodiments are also possible. For example, the charged particle beam B may use helium, oxygen, or neon.

[0013] Cancer treatment using charged particle beam B has a higher ability to kill cancer lesions compared to conventional cancer treatments using X-rays, gamma rays, or proton beams, and has the characteristic that the radiation dose is weak on the surface of the patient P's body and peaks at the cancer lesion. Therefore, the number of irradiations and side effects can be reduced, and the treatment period can be shortened.

[0014] For example, when the charged particle beam B passes through the body of the patient P, it loses kinetic energy and decreases in speed, and is subjected to resistance that is approximately inversely proportional to the square of the speed, causing it to suddenly stop when it has slowed down to a certain speed. This stopping point of the charged particle beam B is called the Bragg peak, and high energy is emitted from it. The particle beam irradiation system 1 can annihilate only the diseased tissue while minimizing damage to normal tissue by aligning this Bragg peak with the position of the diseased tissue (affected area) of the patient P.

[0015] The particle beam irradiation system 1 includes an ion generator 2, an accelerator 3, a beam transport device 4, and a slit-type irradiation device 5.

[0016] The ion generator 2 has an ion source of carbon ions, which are charged particles, and generates a charged particle beam B from these carbon ions. The accelerator 3 accelerates the charged particle beam B generated by the ion generator 2. The accelerator 3 includes a linear accelerator and a circular accelerator. Here, the charged particle beam B is accelerated to approximately 70% of the speed of light while circulating the circular accelerator approximately one million times. Then, the charged particle beam B accelerated by the circular accelerator is transported to a slit-type irradiation device 5 by a beam transport device 4.

[0017] The ion generator 2, accelerator 3, and beam transport device 4 are provided with a vacuum duct 8 (beam pipe) that extends integrally and has a vacuum inside. The charged particle beam B travels through the vacuum duct 8. The vacuum duct 8 forms a transport path that guides the charged particle beam B from the ion generator 2 to the slit-type irradiation device 5. In other words, the inside of the vacuum duct 8 is a sealed continuous space with a sufficient degree of vacuum to allow the charged particle beam B to pass through.

[0018] Next, the slit-type irradiation device 5 will be described with reference to Fig. 2 and Fig. 3. The right side of Fig. 2 will be described as the front side (forward side) of the slit-type irradiation device 5. If the direction in which the vacuum duct 8 of the beam transport device 4 extends and the direction in which the charged particle beam B comes is defined as the Z direction, the vertical direction on the page perpendicular to this will be defined as the X direction, and the direction perpendicular to these will be defined as the Y direction. The X direction will be described as the vertical direction, and the Y and Z directions will be horizontal directions.

[0019] First, an expansion duct 93 that expands in a triangular shape (fan shape) in side view is connected to the tip of the vacuum duct 8 of the beam transport device 4. This expansion duct 93 expands in the X direction from the tip of the vacuum duct 8 of the beam transport device 4. An irradiation device main body 94 (housing) is connected to the expanded tip of this expansion duct 93. The irradiation device main body 94 has a vertically long rectangular shape (box shape) in side view. The inside of the expansion duct 93 and the irradiation device main body 94 is an enclosed space with a sufficient degree of vacuum that is continuous with the vacuum duct 8 of the beam transport device 4.

[0020] Inside the irradiation device main body 94, there are provided a plurality of electromagnet groups 95 (FIG. 3) each consisting of a plurality of bending electromagnets (not shown) in order to deflect the charged particle beam B incident from a wide angle range and converge it onto an isocenter C. These electromagnet groups 95 generate an effective magnetic field region R (FIG. 2). The isocenter C is set as the position where the charged particle beam B is irradiated most concentratedly, and the affected area of ​​the patient P is positioned at this isocenter C.

[0021] For example, a pair of electromagnet groups 95 are provided in the Y direction inside the irradiation device main body 94. Two sets of electromagnet groups 95 are arranged side by side in the X direction. One set of electromagnet groups 95 generates one effective magnetic field region R. In the example of Fig. 2, two sets of electromagnet groups 95, one above the other, can generate two effective magnetic field regions R.

[0022] The effective magnetic field region R is generated to have a crescent shape in a side view. The trajectory of the charged particle beam B can be controlled by controlling the strength of the effective magnetic field region R. The charged particle beam B can be irradiated at any angle around the isocenter C. For example, if the inclination of the reference trajectory K when the trajectory of the charged particle beam B is not deflected is set to 0 degrees, the extraction angle of the charged particle beam B can be changed over a predetermined angle range (+θ degrees to -θ degrees) around the isocenter C.

[0023] The reference trajectory K is a trajectory in which the charged particle beam B flies straight from the vacuum duct 8 toward the isocenter C. When the effective magnetic field region R is not generated, the charged particle beam B flies straight from the vacuum duct 8 to the isocenter C.

[0024] In the example of Figure 2, the two upper and lower effective magnetic field regions R have the same shape and the same strength. In other words, effective magnetic field regions R that are symmetrical between the top and bottom are generated, but other configurations are also possible. For example, the effective magnetic field region R may be asymmetric between the top and bottom. In other words, the two upper and lower effective magnetic field regions R may have different shapes and strengths. Furthermore, a configuration in which one effective magnetic field region R is generated at either the top or bottom may be possible. Note that the center of the range of the angle of the charged particle beam B that changes in the circumferential direction around the isocenter C may be shifted from the reference trajectory K of the charged particle beam B.

[0025] The patient P is placed on a movable stage 11. This movable stage 11 is supported by a movable arm 12 and moves with the patient P placed thereon, so that the affected area of ​​the patient P is positioned at the isocenter C. By moving this movable stage 11, the patient P can be moved to the irradiation position of the charged particle beam B and aligned. Therefore, the charged particle beam B can be irradiated to the lesion tissue of the patient P with optimum accuracy.

[0026] The front side of the irradiation device main body 94 forms a recess 96 that is recessed in a semicircular shape in side view. An isocenter C is set at the center of the semicircle of this recess 96, and the patient P is placed at this isocenter C. Here, the movable stage 11 can be used to position the patient P at the isocenter C by having the patient P enter the recess 96 on the front side of the irradiation device main body 94. For example, the movable stage 11 carrying the patient P can be entered from the front direction of the slit-type irradiation device 5 (the direction of the white arrow D in FIG. 2). In this way, the patient P can be entered from an appropriate direction and placed at the isocenter C.

[0027] A slit 97 (FIG. 3) is formed on the front side of the irradiation device main body 94, and the slit 97 extends in the circumferential direction around the isocenter C where the patient P is placed. For example, a vertically long slit 97 is formed. The slit-type irradiation device 5 emits the charged particle beam B from the slit 97 toward the isocenter C at an arbitrary angle. The slit 97 is closed with an ultra-heat-resistant and ultra-cold-resistant polyimide film, and a vacuum is maintained inside the irradiation device main body 94 in a state where the charged particle beam B can pass through.

[0028] An irradiation nozzle 10 capable of changing the irradiation direction of the charged particle beam B relative to the isocenter C is provided near the slit-type irradiation device 5. This irradiation nozzle 10 is equipped with a ridge filter, a position monitor, a dose monitor, and a scanning electromagnet. In this way, the irradiation nozzle 10 is equipped with a number of devices.

[0029] The irradiation nozzle 10 moves in a circumferential direction at positions equidistant from the isocenter C, where the patient P is placed, around the isocenter C. Although not shown in the figures, the particle beam irradiation system 1 includes a moving device for moving the irradiation nozzle 10 in the circumferential direction.

[0030] For example, when the inclination of the reference trajectory K of the charged particle beam B is 0 degrees, the irradiation nozzle 10 can be moved over a predetermined angular range (+θ degrees to −θ degrees). For example, the irradiation nozzle 10 can be rotated by a predetermined angle in one direction and the other direction in the circumferential direction.

[0031] The irradiation nozzle 10 moves in a side view so as to follow the shape (boundary shape) of the exit side of the effective magnetic field region R. The charged particle beam B traveling from the exit side of the effective magnetic field region R toward the isocenter C passes through the irradiation nozzle 10, and the traveling direction of the charged particle beam B is finely adjusted by the irradiation nozzle 10.

[0032] 2 and 3, for ease of understanding, the Z direction of the slit-type irradiation device 5 is shown aligned with the horizontal direction. However, when the slit-type irradiation device 5 is actually installed, the entire slit-type irradiation device 5 is tilted. In other words, the irradiation device main body 94 is installed on the floor with the longitudinal direction (X direction) of the irradiation device main body 94 tilted.

[0033] For example, the upper part of the irradiation device main body 94 is tilted so as to face the patient P. The irradiation range of the charged particle beam B is a range of any angle centered on the isocenter C, but by tilting the slit-type irradiation device 5, the charged particle beam B can be irradiated from directly above the patient P. In this way, the range of angles at which the charged particle beam B is irradiated onto the patient P, who is the irradiation target of the charged particle beam B, becomes practical. Note that the upper part of the irradiation device main body 94 may be tilted so as to face away from the patient P. Also, the slit-type irradiation device 5 may be installed on the floor without being tilted.

[0034] 2, the expansion duct 93 is connected to the vacuum duct 8 and spreads out in a fan shape with the connection part with the vacuum duct 8 as the apex. The irradiation device main body 94 is connected to the spread part of the expansion duct 93.

[0035] A first sorting electromagnet 91 is provided at the connection between the vacuum duct 8 and the expansion duct 93. Furthermore, two second sorting electromagnets 92, one above the other, are provided downstream of the first sorting electromagnet 91 and upstream of the irradiation device main body 94. In other words, the second sorting electromagnets 92 are provided between the first sorting electromagnet 91 and the irradiation device main body 94, in at least a partial range on the passage path of the charged particle beam B.

[0036] The first deflecting electromagnet 91 is a bending electromagnet that deflects the charged particle beam B within a range of a first angle θ1 ( FIG. 6 ), with the connection point between the vacuum duct 8 and the expansion duct 93 as the origin and with a reference trajectory K when the trajectory of the charged particle beam B is not deflected as the original line (initial line). The second deflecting electromagnet 92 is a bending electromagnet that further deflects the charged particle beam B deflected by the first deflecting electromagnet 91 within a range of a second angle θ2. The first deflecting electromagnet 91 and the second deflecting electromagnet 92 deflect the trajectory of the charged particle beam B entering the irradiation device main body 94.

[0037] In this embodiment, the total weight of one first distribution electromagnet 91 and two second distribution electromagnets 92 is lighter than the weight of a single large distribution electromagnet in the past. Furthermore, the first distribution electromagnet 91 and the second distribution electromagnet 92 have each been made smaller. This simplifies the manufacturing costs, transportation, and assembly of the first distribution electromagnet 91, the second distribution electromagnet 92, and their power supplies, and also reduces inductance, thereby reducing the generated voltage and facilitating excitation and demagnetization. Furthermore, the cost of the power supply used for excitation can be reduced. Furthermore, a wide deflection angle can be obtained in a small magnetic field area.

[0038] In addition, the charged particle beam B in this embodiment is a heavy particle beam. In this way, even when a heavy particle beam, which is less likely to bend than a proton beam, is used, a small-sized deflecting electromagnet will suffice.

[0039] An example of the first polarizing electromagnet 91 and the second polarizing electromagnet 92 is shown in Fig. 4. In the example of Fig. 4, the vacuum duct 8 and the expansion duct 93 are omitted from the illustration to facilitate understanding.

[0040] The first distribution electromagnet 91 includes one first core 91A and two first coils 91B. In a cross section seen from the Z direction, the first core 91A has a rectangular shape surrounding the vacuum duct 8. The two first coils 91B are provided within the first core 91A and are provided on both sides of the vacuum duct 8 so as to sandwich the vacuum duct 8 in the Y direction.

[0041] The two upper and lower second distribution electromagnets 92 have the same configuration, but are upside down. Each second distribution electromagnet 92 includes one second iron core 92A and two second coils 92B. The second iron core 92A is U-shaped in cross section when viewed from the Z direction, with the edge of the expansion duct 93 sandwiched between them in the Y direction. The two second coils 92B are provided within the second iron core 92A and on both sides of the edge of the expansion duct 93, with the edge of the expansion duct 93 sandwiched between them in the Y direction.

[0042] 2, the two second deflecting electromagnets 92 are provided at positions that are symmetrical with respect to the reference orbit K. In this way, the range of angles over which the charged particle beam B can be deflected can be widened.

[0043] The first and second polarizing electromagnets 91 and 92 are made of normal conducting magnets. On the other hand, the multiple bending electromagnets included in the electromagnet group 95 (FIG. 3) mounted on the irradiation device main body 94 are made of superconducting magnets. In this way, by making the first and second polarizing electromagnets 91 and 92 out of normal conducting magnets, the first and second polarizing electromagnets 91 and 92 can be manufactured at low cost. On the other hand, by making the electromagnet group 95 out of superconducting magnets, the irradiation device main body 94 can be made smaller.

[0044] The first and second distribution electromagnets 91 and 92 are provided in the atmosphere (air) outside the vacuum duct 8 and the expansion duct 93. On the other hand, the electromagnet group 95 (FIG. 3) is provided in the vacuum inside the irradiation device main body 94, and is cooled by a predetermined coolant.

[0045] 6 shows an example of the trajectory of the charged particle beam B deflected by the first deflection electromagnet 91 and the second deflection electromagnet 92. The upper and lower second deflection electromagnets 92 have the same configuration, only the upper second deflection electromagnet 92 is shown as an example.

[0046] Here, the range of deflection possible by the first deflection electromagnet 91 is defined as a first angle θ1, and the range of deflection possible by the second deflection electromagnet 92 is defined as a second angle θ2. For example, if the maximum deflection angle within the range of the first angle θ1 is 20 degrees and the maximum deflection angle within the range of the second angle θ2 is 10 degrees, the maximum deflection angle within the range of the deflection angle θ3 obtained by adding these angles together is 30 degrees. In other words, the charged particle beam B can be deflected over a range from 0 degrees to 30 degrees. Here, the charged particle beam B is deflected using only the first deflection electromagnet 91 from 0 degrees to 20 degrees. Furthermore, the charged particle beam B is deflected using both the first deflection electromagnet 91 and the second deflection electromagnet 92 from 20 degrees to 30 degrees.

[0047] The range of the first angle θ1 and the range of the second angle θ2 may partially overlap. For example, the maximum deflection angle within the range of the first angle θ1 may be 20 degrees, and the maximum deflection angle within the range of the second angle θ2 may be 10 degrees, with the range of the first angle θ1 and the range of the second angle θ2 overlapping by approximately 5 degrees. The maximum deflection angle within the range of the allocation angle θ3, which is the sum of these, may be 25 degrees.

[0048] 5 shows an effective magnetic field region R generated by one set of electromagnet group 95 (FIG. 3). The upper and lower sets of electromagnet group 95 have the same configuration, only the upper set of electromagnet group 95 is shown as an example.

[0049] The electromagnet group 95 can generate five magnetic fields, from a first magnetic field M1 to a fifth magnetic field M5. Starting with the first magnetic field M1, which has the smallest deflection angle, the second magnetic field M2, the third magnetic field M3, the fourth magnetic field M4, and the fifth magnetic field M5 are generated in that order. The electromagnet group 95 is made up of a plurality of deflection electromagnets corresponding to each of the first magnetic field M1 to the fifth magnetic field M5.

[0050] The electromagnet group 95 generates one of the first magnetic field M1 to the fifth magnetic field M5 depending on the angle of the charged particle beam B incident on the effective magnetic field region R. Then, the charged particle beam B is irradiated from the effective magnetic field region R toward the isocenter C where the patient P is placed. For example, the irradiation angle θ4 of the charged particle beam B is within the range of 0 to 40 degrees.

[0051] FIG. 7 shows the angular change of the trajectory of the charged particle beam B caused by the first and second deflection electromagnets 91 and 92, and the angular change of the trajectory of the charged particle beam B caused by the electromagnet group 95 (FIG. 3).

[0052] For example, the maximum deflection angle within the range of the distribution angle θ3 by the first distribution electromagnet 91 and the second distribution electromagnet 92 is 30 degrees. The maximum irradiation angle within the range of the irradiation angle θ4 by the electromagnet group 95 (FIG. 3) is 40 degrees. In other words, the range of the distribution angle θ3 that can be deflected by the first distribution electromagnet 91 and the second distribution electromagnet 92 is narrower than the range of the irradiation angle θ4 that can be deflected by the electromagnet group 95 (FIG. 3) mounted on the irradiation device main body 94. The distance L1 from the position P0 of the first distribution electromagnet 91 to the position P1 of the irradiation device main body 94 is longer than the distance L2 from the position P1 of the irradiation device main body 94 to the position P2 of the isocenter C (patient P).

[0053] The first and second sorting electromagnets 91 and 92, which are arranged in the backyard out of sight of the patient P, can be arranged in a large space, so that a long distance L1 to the irradiation device main body 94 can be ensured. Therefore, even if the deflection-capable sorting angle θ3 is reduced, a sufficient swing width can be ensured, and the first and second sorting electromagnets 91 and 92 can be made smaller. Furthermore, by shortening the distance L2 from the irradiation device main body 94 to the patient P, the flight distance of the charged particle beam B in the atmosphere (air) can be shortened. Furthermore, the irradiation device main body 94, which is located close to the patient P, can irradiate the charged particle beam B from a wide range around the patient P, so that the range of the irradiation angle θ4 becomes practical.

[0054] In the above-described embodiment, the slit-type irradiation device 5 is provided with two second dividing electromagnets 92, one at the top and one at the bottom, but other embodiments are also possible. For example, the slit-type irradiation device 5 may be provided with either one of the upper and lower second dividing electromagnets 92.

[0055] Furthermore, although the above-described embodiment is an aspect in which the slit-type irradiation device 5 is provided with the first deflection electromagnet 91 and the second deflection electromagnet 92, other aspects are also possible. For example, the slit-type irradiation device 5 may be provided with a third deflection electromagnet that further deflects the charged particle beam B deflected by the second deflection electromagnet 92 within a third angle range. This third deflection electromagnet is provided downstream of the second deflection electromagnet 92 and upstream of the irradiation device main body 94.

[0056] According to the embodiment described above, the slit-type irradiation device 5 is provided with the first deflection electromagnet 91 and the second deflection electromagnet 92, so that the total weight of the deflection electromagnets for deflecting the charged particle beam B incident on the irradiation device main body 94 can be reduced.

[0057] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and modifications thereof are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0058] 1...particle beam irradiation system, 2...ion generator, 3...accelerator, 4...beam transport device, 5...slit-type irradiation device, 8...vacuum duct, 10...irradiation nozzle, 11...movable stage, 12...movable arm, 91...first deflection electromagnet, 91A...first iron core, 91B...first coil, 92...second deflection electromagnet, 92A...second iron core, 92B...second coil, 93...expansion duct, 94...irradiation device main body, 95...electromagnet group, 96...recess, 97...slit, B...charged particle beam, C...isocenter, D...white arrow, K...reference trajectory, M1...first magnetic field, M2...second magnetic field, M3...third magnetic field, M4...fourth magnetic field, M5...fifth magnetic field, P...patient, R...effective magnetic field region.

Claims

1. an expansion duct connected to a vacuum duct of a beam transport device that guides a heavy particle beam accelerated by an accelerator, the expansion duct expanding in a fan shape with a connection point with the vacuum duct as an apex; an irradiation device main body connected to the expanded portion of the expansion duct, deflecting the heavy ion beam incident from the expansion duct, and emitting the heavy ion beam at an arbitrary angle toward an isocenter from a slit extending in a circumferential direction around an isocenter where an irradiation target of the heavy ion beam is located; a first deflecting electromagnet provided at the connection portion between the vacuum duct and the expansion duct, the first deflecting electromagnet deflecting the heavy particle beam within a first angle range with a reference trajectory when the trajectory of the heavy particle beam is not deflected as an original line; at least one second deflection electromagnet provided downstream of the first deflection electromagnet and configured to further deflect the heavy particle beam deflected by the first deflection electromagnet within a second angle range; Equipped with Particle beam irradiation system.

2. At least two of the second polarizing electromagnets are provided at positions symmetrical with respect to the reference orbit. The particle beam irradiation system according to claim 1 .

3. a range of angles that can be deflected by the first deflecting electromagnet and the second deflecting electromagnet is narrower than a range of angles that can be deflected by the irradiation device main body; 3. The particle beam irradiation system according to claim 1.

4. the first and second deflecting electromagnets are composed of normal conducting magnets, and the deflecting electromagnets included in the irradiation device main body are composed of superconducting magnets; 3. The particle beam irradiation system according to claim 1.

5. an expansion duct connected to a vacuum duct of a beam transport device that guides a heavy particle beam accelerated by an accelerator, the expansion duct expanding in a fan shape with a connection point with the vacuum duct as an apex; an irradiation device main body connected to the expanded portion of the expansion duct, deflecting the heavy ion beam incident from the expansion duct, and emitting the heavy ion beam at an arbitrary angle toward an isocenter from a slit extending in a circumferential direction around an isocenter where an irradiation target of the heavy ion beam is located; a first dividing electromagnet provided at the connection portion between the vacuum duct and the expansion duct; at least one second sorting electromagnet provided downstream of the first sorting electromagnet; This is a method using the first deflecting electromagnet deflects the heavy particle beam within a first angle range with a reference trajectory when the trajectory of the heavy particle beam is not deflected as an original trajectory, the second deflecting electromagnet further deflects the heavy particle beam deflected by the first deflecting electromagnet within a second angle range. Particle beam irradiation method.

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