Heavy particle beam irradiation device and treatment system

Abstract

To provide a heavy particle beam irradiation device capable of adjusting an irradiation angle to a target in a wide range while being oriented to reducing an area of a uniform magnetic field forming region.SOLUTION: A heavy particle beam irradiation device 10 includes: a first emission port 31 for emitting a heavy particle beam 18 with a positive direction irradiation angle 17a with respect to a reference line 16 by a first deflection angle 21; a first magnetic field region 11 for generating magnetic fields 25 and 26 in directions reverse to each other sandwiching a straight line connecting the first emission port 31 and an isocenter 15, imparting a circular arc locus to the heavy particle beam 18, and converging the heavy particle beam to the isocenter 15; a second emission port 32 for emitting the heavy particle beam 18 with a negative direction irradiation angle with respect to the reference line 16 by a second deflection angle; and a second magnetic field region 12 for generating magnetic fields 27 and 28 in directions reverse to each other sandwiching a straight line connecting the second emission port 32 and the isocenter 15, imparting a circular arc locus to the heavy particle beam 18 emitted by the second deflection angle 22, and converging the heavy particle beam to the isocenter 15.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a technique for irradiating a target with heavy particle beams from a plurality of directions.

Background Art

[0002] Heavy particle beams accelerated to high energy are irradiated onto malignant tumors such as cancer and used for the treatment of such malignant tumors. According to this treatment method, damage to normal tissues can be avoided, and only the lesion tissue can be pinpointed and killed. Therefore, compared with surgical and chemical treatments, the burden on patients is less, and early social rehabilitation after treatment can also be expected.

[0003] In the early days, a fixed method in which the irradiation part of the heavy particle beam was fixed so that the target (lesion tissue) was irradiated from only one direction was the mainstream. In recent years, a method has been adopted in which heavy particle beams are irradiated onto the target from a plurality of directions so as to overlap, suppressing the exposure of normal tissues and concentrating a large dose on the lesion tissue for more effective treatment.

[0004] As a method of irradiating a target with heavy particle beams from a plurality of directions, a system in which a plurality of fixed irradiation ports are provided in a treatment room is known. In addition, a system is also known in which the target itself is rotated so that the heavy particle beam emitted from one fixed irradiation port is irradiated onto the target from a plurality of directions. In addition, a system is also known in which one fixed irradiation port is provided on a rotating gantry and the heavy particle beam is irradiated onto the target from a plurality of directions by changing the rotation angle. Furthermore, a system is also known in which, without rotating the target itself and without using a rotating gantry, the heavy particle beam is deflected by a control electromagnet and irradiated onto the target from an arbitrary angle.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In the case of an irradiation device using a control electromagnet as described above, it is necessary to be able to continuously irradiate an isocenter with a heavy particle beam at a predetermined irradiation angle. For this reason, it is necessary to uniformize the magnetic field formed in the orbital region of the heavy particle beam to be deflected. Further, in order to widen the effective range of the irradiation angle to the target, it is necessary to set a wide orbital region for applying a uniform magnetic field to the heavy particle beam. However, when trying to form a uniform magnetic field in a wide orbital region, the stored energy of the control electromagnet increases, and the voltage between terminals increases, etc., increasing the difficulty in handling.

[0007] Embodiments of the present invention have been made in consideration of such circumstances, and an object is to provide an irradiation device for a heavy particle beam that can adjust the irradiation angle to the target over a wide range while aiming to reduce the area of the region where a uniform magnetic field is formed. [Means for Solving the Problems]

[0008] In the heavy particle beam irradiation apparatus according to the embodiment, a first emission port that emits a heavy particle beam having an irradiation angle in the positive direction with respect to a reference line including the isocenter at an arbitrary first deflection angle, and a magnetic field in opposite directions with respect to the straight line connecting the first emission port and the isocenter. A first magnetic field region that generates an arc trajectory to the heavy particle beam emitted at an arbitrary first deflection angle and converges it to the isocenter, and a second emission port that emits the heavy particle beam having an irradiation angle in the negative direction with respect to the reference line at an arbitrary second deflection angle, and a magnetic field in opposite directions with respect to the straight line connecting the second emission port and the isocenter. A second magnetic field region that generates an arc trajectory to the heavy particle beam emitted at an arbitrary second deflection angle and converges it to the isocenter.

Effects of the Invention

[0009] According to the embodiment of the present invention, there is provided a heavy particle beam irradiation apparatus capable of widely adjusting the irradiation angle to a target while aiming to reduce the area of the region where a uniform magnetic field is formed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0011] (First Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of a heavy particle beam irradiation apparatus 10A (10) (hereinafter simply referred to as "irradiation apparatus 10") according to a first embodiment. FIG. 2 is a cross-sectional view of a first magnetic field region 11 and a second magnetic field region 12.

[0012] Thus, the heavy particle beam irradiation apparatus 10 includes a first emission port 31 that emits a heavy particle beam 18 having a positive irradiation angle 17a with respect to a reference line 16 including an isocenter 15 at an arbitrary first deflection angle 21, and magnetic fields 25 and 26 that are opposite to each other across a straight line connecting the first emission port 31 and the isocenter 15, and a first magnetic field region 11 that imparts an arc trajectory to the heavy particle beam 18 emitted at an arbitrary first deflection angle 21 and converges it to the isocenter 15.

[0013] Furthermore, the heavy particle beam irradiation apparatus 10 includes a second emission port 32 that emits a heavy particle beam 18 having a negative irradiation angle 17b (FIG. 3) with respect to the reference line 16 at an arbitrary second deflection angle 22 (FIG. 3), and magnetic fields 27 and 28 that are opposite to each other across a straight line connecting the second emission port 32 and the isocenter 15, and a second magnetic field region 12 that imparts an arc trajectory to the heavy particle beam 18 emitted at an arbitrary second deflection angle 22 and converges it to the isocenter 15.

[0014] In FIG. 1, taking the isocenter 15 as the origin of the coordinate axes, the reference line 16 as the X-axis, the directions of the magnetic fields 25, 26, 27, and 28 generated by the first magnetic field region 11 and the second magnetic field region 12 as the Z-axis, and the direction orthogonal to the X-axis and the Z-axis as the Y-axis. In the treatment using the heavy particle beam 18, a moving bed (not shown) is set so that the target (lesion tissue) of the patient lying horizontally along the Z-axis direction coincides with the isocenter 15. Then, if necessary, the moving bed is moved in the directions along each axis or in the rotational direction of the Y-axis to irradiate the heavy particle beam 18.

[0015] When the first deflection angle 21 is set to zero, the first output port 31 is mechanically adjusted so that the heavy particle beam 18 enters the isocenter 15. The range of the first deflection angle 21 is set to a range in which the heavy particle beam 18 output from the first output port 31 can enter the first magnetic field region 11. The heavy particle beam 18 describes an arc trajectory in the X-Y plane due to the Lorentz force applied in the first magnetic field region 11 and converges to the isocenter 15.

[0016] The second output port 32 is arranged at a symmetric position with respect to the reference line 16 in the X-Y plane with respect to the first output port 31. The configuration of the second output port 32 other than that is the same as that of the first output port 31 by changing the first deflection angle 21 to the second deflection angle 22 and the first magnetic field region 11 to the second magnetic field region 12.

[0017] As shown in FIG. 2, the first magnetic field region 11 is composed of an electromagnet 45 that generates a magnetic field 25 in a direction that applies a Lorentz force directed inward to the passing heavy particle beam 18, and an electromagnet 46 that generates a magnetic field 26 in the opposite direction. These electromagnets 45 and 46 each consist of a pair of coils and are arranged on both sides of a straight line connecting the first output port 31 and the isocenter 15. Thereby, the heavy particle beam 18 incident on the first magnetic field region 11 from the first output port 31 describes an arc trajectory and converges to the isocenter 15.

[0018] Similarly, the second magnetic field region 12 is composed of an electromagnet 48 that generates a magnetic field 28 in a direction that applies a Lorentz force directed inward to the passing heavy particle beam 18, and an electromagnet 47 that generates a magnetic field 27 in the opposite direction. These electromagnets 47 and 48 each consist of a pair of coils and are arranged on both sides of a straight line connecting the second output port 32 and the isocenter 15. Thereby, the heavy particle beam 18 incident on the second magnetic field region 12 from the second output port 32 describes an arc trajectory and converges to the isocenter 15.

[0019] Each of the electromagnets 45, 46, 47, and 48 has a coil wound around a high-permeability yoke (such as an iron core), and can generate high-intensity magnetic fields 25, 26, 27, and 28 in the gaps between the opposing yokes. The higher the intensity of these magnetic fields 25, 26, 27, and 28, the smaller the radius of the arc trajectory of the heavy particle beam 18 can be, and the smaller the areas of the first magnetic field region 11 and the second magnetic field region 12 can be.

[0020] Therefore, if the electromagnets 45, 46, 47, and 48 are made of superconducting coils, the magnetic fields 25, 26, 27, and 28 can be made even stronger, and the areas of the first magnetic field region 11 and the second magnetic field region 12 can be made even smaller. Also, although each of the electromagnets 45, 46, 47, and 48 is illustrated as being symmetric in plan view, it may be asymmetric regardless of the symmetry of each of the first deflection angle 21 and the second deflection angle 22. Thereby, unused regions can be omitted to form the first magnetic field region 11 and the second magnetic field region 12, and manufacturing costs and power consumption can be reduced.

[0021] The ranges of each of the first deflection angle 21 and the second deflection angle 22 are defined as φmin ≦ φ ≦ φmax, the maximum deflection angle φmax is from 10 degrees to 90 degrees, and the minimum deflection angle φmin is from -90 degrees to -10 degrees. These first deflection angle 21, second deflection angle 22, and irradiation angles 17 (17a, 17b) are defined in the XY plane with the isocenter 15 as the origin.

[0022] In this way, in the embodiment, the heavy particle beam 18 is incident on the isocenter 15 from two directions of the first emission port 31 and the second emission port 32. Further, the first deflection angle 21 and the second deflection angle 22 of the heavy particle beam 18 are adjusted at each of the first emission port 31 and the second emission port 32. Thereby, even when the irradiation angles 17 (17a, 17b) of the heavy particle beam 18 with respect to the isocenter 15 are set as wide as ±90 degrees as shown in FIG. 1, it is not necessary to increase the overall area by forming the first magnetic field region 11 and the second magnetic field region 12 which are divided to have magnetic fields 25, 26, 27, and 28 in opposite directions.

[0023] Generally, when the area of the magnetic field region is large, the stored energy of the electromagnet increases, and as a result, the inductance increases, leading to an increase in the voltage between the terminals of the electromagnet, making it difficult to handle. In the present embodiment, since the areas of the first magnetic field region 11 and the second magnetic field region 12 are sufficiently narrow, they are easy to handle.

[0024] The nozzle 29 moves according to the irradiation angles 17 (17a, 17b) and passes the heavy particle beam 18 toward the isocenter 15. The inside of this nozzle 29 is maintained in a vacuum state, suppressing beam loss due to scattering until immediately before the isocenter 15. Further, the nozzle 29 also has a function of adjusting so that the generation region of the dose peak of the heavy particle beam 18 coincides with the three-dimensional shape of the tumor (target). Note that, as the adjustment method of the heavy particle beam 18, there are an expanded beam method and a scanning method. The expanded beam method is a method of three-dimensionally expanding the heavy particle beam 18 with a scatterer or a ridge filter and shaping the beam with a compensation filter or a collimator dedicatedly created for each target. The scanning method is a method of scanning the trajectory of the heavy particle beam 18 according to the shape of the tumor.

[0025] Furthermore, the nozzle 29 may be provided with a range shifter for adjusting the maximum depth until the heavy particle beam 18 reaches the target. This range shifter adjusts the attenuation amount of the energy necessary and sufficient for the heavy particle beam 18 to reach the target by adjusting the thickness of the acrylic plate.

[0026] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic diagram of a heavy particle beam irradiation apparatus 10B (10) (hereinafter simply referred to as "irradiation apparatus 10") according to the second embodiment. The irradiation apparatus 10B of the second embodiment has a first emission port (not shown), a first magnetic field region 11, a second emission port 32, and a second magnetic field region 12, which are common to the above-described first embodiment. In FIG. 3, parts having the same configuration or function as those in FIG. 1 are denoted by the same reference numerals, and redundant descriptions are omitted.

[0027] In the irradiation device 10B of the second embodiment, the magnetic fields 25, 26, 27, 28 in the same direction in each of the first magnetic field region 11 and the second magnetic field region 12 are formed by adjacently arranging a plurality of electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b so as to divide each region (shown as being divided into two in the figure).

[0028] Thereby, when obtaining the desired irradiation angles 17 (17a, 17b), only one electromagnet arranged in the passage region of the heavy particle beam 18 is excited, and the electromagnets in other regions are not excited. When the heavy particle beam 18 passes through the regions of a plurality of electromagnets (such as when passing directly above the adjacent boundary), only two adjacent electromagnets need to be excited. By doing so, it is possible to minimize the region where the magnetic field is generated. In addition, the inductance per electromagnet 35 can be reduced, the leakage magnetic field from the electromagnet can also be reduced, and the influence on the patient (target) arranged at the isocenter 15 can be minimized.

[0029] And these electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b are formed such that the inductances of the coils are equal. When dividing the regions of the first magnetic field region 11 and the second magnetic field region 12, the inductances of the coils can be made equal by making the areas of the respective regions equal. Thereby, the power supply connected to the electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b can be simplified, the number of power supplies used can be reduced, the number of electromagnets corresponding to each can be increased, and power supply management becomes easy. Although an example of dividing the regions of the first magnetic field region 11 and the second magnetic field region 12 into two each is shown, they may be divided into three or more.

[0030] FIG. 4 is a block diagram of a control unit 30 that controls currents supplied to electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b that form a first magnetic field region 11 and a second magnetic field region 12. This control unit 30 has a function of switching the current supply to the electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b according to the irradiation angles 17 (17a, 17b). Note that this control unit 30 can also be applied to electromagnets 45, 46, 47, 48 that do not divide the magnetic field in the same direction in each of the first magnetic field region 11 and the second magnetic field region 12 as shown in FIG. 2.

[0031] The control unit 30 includes a power supply 51 (51a, 51b) that generates power and a switch 52 that switches the electromagnets 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b to which power is supplied. Note that one power supply 51 has a capacity sufficient to excite one electromagnet. When exciting one electromagnet, only one of the power supplies 51a operates, and the other power supply 51b acts as a backup. When it is necessary to excite two electromagnets, the two power supplies 51a and 51b supply power simultaneously.

[0032] When the irradiation angles 17 (17a, 17b) with respect to the isocenter 15 are determined, one (or two in some cases) electromagnet to be excited is selected. When scanning the irradiation angle 17 of the heavy particle beam 18, the electromagnet to be excited is switched by the switch 52. By selectively exciting the electromagnets in this way, generation of unnecessary magnetic fields can be suppressed and energy consumption can be reduced. In addition, the capacity of the power supply 51 to be installed can be reduced.

[0033] FIG. 5 is a schematic diagram of a treatment system 40 according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an irradiation device 10 for a heavy particle beam incorporated in the treatment system 40. As described above, the treatment system 40 includes an ion source 53 that generates heavy particles, an accelerator 20 that accelerates these heavy particles to generate a high-energy heavy particle beam 18, a beam transport path 49 that transports the heavy particle beam 18 extracted from the accelerator 20, an irradiation device 10 for the heavy particle beam 18, and a bed (not shown) that supports a target irradiated with the heavy particle beam 18 so as to be located at the isocenter 15.

[0034] The accelerator 20 is roughly classified into a linear accelerator 55 and a circular accelerator 56. The heavy particles generated by the ion source 53 are gradually accelerated by the linear accelerator 55 and the circular accelerator 56 to become the heavy particle beam 18. Then, the heavy particle beam 18 that has orbited the circular accelerator 56 and reached the irradiation required energy level has its traveling direction changed from the orbit and is extracted into the beam transport path 49.

[0035] Examples of the heavy particles generated by the ion source 53 include carbon, helium, oxygen, neon, silicon, argon, etc. Examples of the ion source 53 include high-frequency (including microwaves) irradiation types such as an ECR (Electron Cyclotron Resonance) ion source and a PIG (Penning Ionization Gauge) ion source, as well as a laser irradiation type ion source. Note that the ion source 53 is not limited to these, and any ion source that can efficiently generate heavy particles can be appropriately adopted.

[0036] The linear accelerator 55 arranges a plurality of accelerating electric fields having opposite electric field components adjacent to each other in a straight line, repeatedly reverses the electric field direction at a high-frequency, and always accelerates the heavy particles passing through the accelerating electric field in only one direction. Specifically, the linear accelerator 55 is composed of a radio frequency quadrupole (RFQ) linear accelerator and a drift tube linac (DTL).

[0037] The circular accelerator 56 is a synchrotron, a cyclotron, or the like, and includes a high-frequency acceleration cavity 59 that accelerates the heavy particle beam 18 incident from the linear accelerator 55 by high-frequency power, a plurality of deflection electromagnets 58 that bend the heavy particle beam 18 by a magnetic field and place it on a circular orbit, a plurality of quadrupole electromagnets 57 that generate a magnetic field for diverging and converging the circulating heavy particle beam 18 and retaining it within the circular orbit, and an emitter 54 that emits the heavy particle beam 18 from the circular accelerator 56 to the beam transport path 49.

[0038] The circular accelerator 56 configured as described above can accelerate the heavy particle beam 18 incident from the linear accelerator 55 at a low energy to a high energy by accelerating it up to 70 - 80% of the speed of light while circulating it.

[0039] As shown in FIG. 6, the orbit of the heavy particle beam 18 that has passed through the beam splitter 19 is redirected to either the first branch path 41 or the second branch path 42. The beam splitter 19 is composed of an electromagnet and induces the heavy particle beam 18 to the first branch path 41 or the second branch path 42 by changing the magnitude and direction of the excitation current.

[0040] Quadrupole electromagnets 57 and deflection electromagnets 58 are also provided in the first branch path 41 and the second branch path 42, and the orbit of the heavy particle beam 18 is bent so as to face the direction of the isocenter 15. In this way, the heavy particle beam 18 extracted from the accelerator 20 and transported in the beam transport path 49 is emitted from the first emission port 31 and the second emission port 32 after being split by the beam splitter 19.

[0041] Then, the heavy particle beam 18 emitted from the first emission port 31 and the second emission port 32 is irradiated onto the isocenter 15 at an arbitrary irradiation angle 17 (17a, 17b). Thereby, the dose concentration on the target located at the isocenter 15 can be increased, and treatment with less side effects that suppresses the exposure of normal tissues becomes possible.

[0042] Note that the present invention is not limited to the configurations shown in FIGS. 5 and 6, and the heavy particle beams 18 emitted from the first emission port 31 and the second emission port 32 may be generated by separate accelerators, respectively.

[0043] According to the heavy particle beam irradiation device of at least one of the embodiments described above, a first magnetic field region divided to generate magnetic fields in opposite directions to each other, and a second magnetic field region similarly divided to generate magnetic fields in opposite directions to each other are provided, and by imparting an arc trajectory to the heavy particle beam and converging it to the isocenter, while aiming to reduce the area of the uniform magnetic field formation region, a heavy particle beam irradiation device capable of adjusting the irradiation angle to the target over a wide range is provided.

[0044] Although some 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, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0045] 10(10A, 10B) … Heavy particle beam irradiation device, 11 … First magnetic field region, 12 … Second magnetic field region, 15 … Isocenter, 16 … Reference line, 17(17a, 17b) … Irradiation angle, 18 … Heavy particle beam, 19 … Beam splitter, 20 … Accelerator, 21 … First deflection angle, 22 … Second deflection angle, 25, 26, 27, 28 … Magnetic field, 29 … Nozzle, 30 … Control unit, 31 … First emission port, 32 … Second emission port, 35a, 35b, 36a, 36b, 37a, 37b, 38a, 38b … Electromagnet, 40 … Treatment system, 41 … First branch path, 42 … Second branch path, 45, 46, 47, 48 … Electromagnet, 49 … Beam transport path, 51(51a, 51b) … Power supply, 52 … Switch, 53 … Ion source, 54 … Emitter, 55 … Linear accelerator, 56 … Circular accelerator, 57 … Quadrupole electromagnet, 58 … Deflection electromagnet, 59 … High-frequency acceleration cavity.

Claims

1. A first emission port that emits a heavy particle beam having an irradiation angle in the positive direction with respect to a reference line including an isocenter at an arbitrary first deflection angle, A first magnetic field region that generates magnetic fields in opposite directions with respect to a straight line connecting the first emission port and the isocenter, and imparts an arc trajectory to the heavy particle beam emitted at the arbitrary first deflection angle and converges it to the isocenter, A second emission port that emits the heavy particle beam having an irradiation angle in the negative direction with respect to the reference line at an arbitrary second deflection angle, A second magnetic field region that generates magnetic fields in opposite directions with respect to a straight line connecting the second emission port and the isocenter, and imparts an arc trajectory to the heavy particle beam emitted at the arbitrary second deflection angle and converges it to the isocenter, and an irradiation device for a heavy particle beam comprising the same.

2. In the irradiation device for a heavy particle beam according to Claim 1, The heavy particle beam emitted from the first emission port and the second emission port is a heavy particle beam that is sorted by a splitter after being taken out from an accelerator.

3. In the irradiation device for a heavy particle beam according to Claim 1, The heavy particle beam emitted from the first emission port and the second emission port is a heavy particle beam generated by separate accelerators respectively.

4. In the irradiation device for a heavy particle beam according to any one of Claims 1 to 3, An irradiation device for a heavy particle beam comprising a nozzle that moves according to the irradiation angle and allows the heavy particle beam to pass therethrough toward the isocenter.

5. In the irradiation device for a heavy particle beam according to any one of Claims 1 to 3, In the irradiation device for a heavy particle beam, magnetic fields in the same direction in each of the first magnetic field region and the second magnetic field region are formed by adjacently arranging a plurality of electromagnets so as to divide each region.

6. In the irradiation device for a heavy particle beam according to Claim 5, In the irradiation device for a heavy particle beam, each of the electromagnets is formed such that the inductance of the coil is equal.

7. In the irradiation device for a heavy particle beam according to Claim 5, An irradiation device for a heavy particle beam that switches the electromagnets that supply current according to the irradiation angle.

8. An irradiation device for a heavy particle beam according to any one of Claims 1 to 3, An ion source that generates heavy particles, An accelerator that accelerates the heavy particles to generate a heavy particle beam having high energy, A beam transport path for transporting the heavy particle beam extracted from the accelerator, A treatment system comprising a bed that supports a target irradiated with the heavy particle beam so as to be located at the isocenter.

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