CN109224318B

CN109224318B - Charged particle beam therapy device

Info

Publication number: CN109224318B
Application number: CN201710560075.9A
Authority: CN
Inventors: 上口长昭
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2017-07-11
Filing date: 2017-07-11
Publication date: 2021-06-18
Anticipated expiration: 2037-07-11
Also published as: CN109224318A

Abstract

The invention provides a charged particle beam treatment device. In a charged particle beam therapy device for performing scanning irradiation, the dose distribution of a charged particle beam at the peripheral portion of an irradiation region is improved while preventing an increase in the size of an irradiation nozzle. A multi-leaf collimator (30) of a charged particle beam therapy device (1) has a pair of blade groups (31, 32) that are provided so as to face each other with a reference axis (A) of a charged particle beam therebetween, and the blade groups (31, 32) have: a plurality of blades (41) which are arranged in parallel in the X direction, can independently advance and retreat in the Y direction, and blocks charged particle beams; and a blade drive unit (43) that advances and retracts the blades (41) in the Y direction, wherein the length of at least a part of the plurality of blades (41) in the Y direction is shorter than half of the length in the Y direction of the maximum scanning range.

Description

Charged particle beam therapy device

Technical Field

The invention relates to a charged particle beam treatment device.

Background

There is known a charged particle beam therapy system that performs therapy by irradiating a charged particle beam to an irradiation object, the charged particle beam therapy system including an irradiation nozzle for irradiating the charged particle beam and a multi-leaf collimator provided therein (for example, patent document 1). The multi-leaf collimator includes a pair of leaf groups including a plurality of leaves, and the shape of an opening between the pair of leaf groups is adjusted to an irradiation region of the charged particle beam by moving the leaves.

Patent document 1: japanese patent laid-open No. 2014-176546

In a charged particle beam therapy system that performs so-called scanning irradiation of a charged particle beam to an irradiation object in accordance with a predetermined scanning pattern, it is considered to apply a multi-leaf collimator for the main purpose of improving the dose distribution in the peripheral portion of an irradiation region, rather than for the main purpose of specifying the shape of the irradiation region. That is, it is considered that a multi-leaf collimator is applied to the peripheral portion of the irradiation region for the main purpose of rapidly reducing the dose, not gently reducing the dose. However, if the multi-blade collimator described in patent document 1 is applied to a charged particle beam therapy apparatus that performs scanning irradiation, it is necessary to secure a space for moving blades included in a pair of blade groups in an irradiation nozzle, which may lead to an increase in size of the irradiation nozzle.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a charged particle beam therapy system capable of improving the dose distribution of a charged particle beam in the peripheral portion of an irradiation region while preventing an increase in size of an irradiation nozzle in a charged particle beam therapy system that performs scanning irradiation.

In order to achieve the above object, a charged particle beam therapy system according to the present invention irradiates a charged particle beam to an irradiation object, and includes: an accelerator that generates and emits the charged particle beam; an irradiation nozzle configured to irradiate the charged particle beam to an irradiation target; and a transmission line that connects the accelerator and the irradiation nozzle and transmits the charged particle beam, wherein an axis orthogonal to a reference axis when the charged particle beam is irradiated is defined as a 1 st axis, and an axis orthogonal to the reference axis and the 1 st axis is defined as a 2 nd axis, and the irradiation nozzle includes: a scanning unit capable of scanning the charged particle beam in a direction along the 1 st axis and a direction along the 2 nd axis within a preset maximum scanning range; and a multi-leaf collimator that is provided downstream of the scanning unit and that defines a shape of an irradiation field when the charged particle beam is irradiated on the irradiation target, the multi-leaf collimator including a pair of leaf groups that are provided to face each other with the reference axis therebetween, the leaf groups including: a plurality of blades which are arranged in parallel in the direction along the 1 st axis, can independently advance and retreat in the direction along the 2 nd axis, and block the charged particle beam; and a blade driving unit configured to move the blades back and forth in the direction along the 2 nd axis, wherein at least some of the blades have a length in the direction along the 2 nd axis shorter than half of a length in the direction along the 2 nd axis of the maximum scanning range.

In the above charged particle beam therapy system, since the charged particle beam scanned by the scanning unit is irradiated to the irradiation object via the multi-leaf collimator, the dose distribution of the charged particle beam at the peripheral edge of the irradiation region is improved. And, a length in a direction along the 2 nd axis of at least a part of the plurality of leaves of the multi-leaf collimator is shorter than a half of a length in a direction along the 2 nd axis of the maximum scanning range. Therefore, the space for advancing and retracting the blades in the direction of the 2 nd axis can be reduced, and therefore, the multi-blade collimator can be downsized, and the dose distribution of the charged particle beam can be improved while preventing the increase in size of the irradiation nozzle.

Here, the charged particle beam therapy system can be configured as follows: the scanning apparatus further includes a pair of stoppers provided on both ends of the blade group in the direction along the 1 st axis, and having a length in the direction along the 2 nd axis equal to or greater than a length in the direction along the 2 nd axis of the maximum scanning range, and configured to block the charged particle beam.

As described above, by further providing a pair of stoppers, the dose distribution can be improved even on both end sides of the blade group.

The charged particle beam therapy system can be configured as follows: the blade group includes a support portion that supports the blade, and the blade is swingable about an axis along the 1 st axis with respect to the support portion.

With the above configuration, the angle of the blade can be changed according to the irradiation direction of the charged particle beam, and the effect of improving the dose distribution can be further improved.

Effects of the invention

According to the present invention, there can be provided a charged particle beam therapy system that performs scanning irradiation, which can improve the dose distribution of a charged particle beam in the peripheral portion of an irradiation region while preventing an increase in the size of an irradiation nozzle.

Drawings

Fig. 1 is a schematic configuration diagram of a charged particle beam therapy system according to an embodiment.

Fig. 2 is a schematic perspective view of a multi-leaf collimator.

Fig. 3 is a top view of the main part of a multi-leaf collimator.

Fig. 4 is a view from IV-IV of fig. 3.

Fig. 5 is a diagram showing a modification of the blade member.

Fig. 6 is a diagram showing a modification of the blade member.

In the figure: 1-charged particle beam therapy device, 11-accelerator, 12-irradiation nozzle (irradiation section), 13-beam delivery line, 30-multi-leaf collimator, 31, 32-leaf set, 35, 36-stop block, 37, 38-stop drive section, 40-leaf member, 41-leaf, 42-support section, 43-leaf drive section

Detailed Description

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. For convenience of explanation, the XYZ rectangular coordinate system is shown in each figure. In the XYZ rectangular coordinate system, the extending direction of the Z axis is taken as the extending direction of the reference axis a of the irradiation direction of the charged particle beam, the extending direction of the X axis (1 st axis) is taken as the direction perpendicular to the Z axis, and the extending direction of the Y axis (2 nd axis) is taken as the direction perpendicular to the Z axis and the X axis, and the following description will be given. The reference axis a in the irradiation direction of the charged particle beam is an axis through which the beam center of the charged particle beam passes when the charged particle beam is irradiated without being deflected in the irradiation nozzle 12 as shown in fig. 3 and 4.

As shown in fig. 1, a charged particle beam therapy apparatus 1 is used for cancer therapy or the like by radiotherapy, and includes: an accelerator 11 that accelerates charged particles generated by an ion source (not shown) and emits the accelerated charged particles as a charged particle beam; an irradiation nozzle 12 (irradiation unit) for irradiating a charged particle beam to an irradiation object; a beam transport line 13 (transport line) for transporting the charged particle beam emitted from the accelerator 11 to the irradiation nozzle 12; an energy degrader (energy adjustment unit) 18 that is provided in the beam transport path 13 and reduces the energy of the charged particle beam to adjust the range of the charged particle beam; and a plurality of electromagnets 25 provided on the beam transport path 13. In the present embodiment, a cyclotron is used as the accelerator 11, but the present invention is not limited to this, and other accelerators such as a synchrotron, a synchrocyclotron, and a linear accelerator may be used.

In the charged particle beam therapy system 1, a tumor (irradiation object) of a patient P on a treatment table 22 is irradiated with a charged particle beam emitted from an accelerator 11. The charged particle beam is a beam that accelerates charged particles at high speed, and examples thereof include a proton beam and a heavy particle (heavy ion) beam. The charged particle beam therapy system 1 according to the present embodiment is a system that performs irradiation of a charged particle beam by a so-called scanning method, virtually divides (slices) an irradiation object into a plurality of layers in a depth direction, and irradiates an irradiation range on the layers with the charged particle beam layer by layer (sliced plane).

Further, as an irradiation method by the scanning method, for example, spot scanning irradiation and raster scanning irradiation are given. The spot scanning irradiation is a method in which, when irradiation of one spot is completed within an irradiation range of one layer, irradiation of a primary beam (charged particle beam) is stopped, and irradiation of the next spot is performed after preparation for irradiation of the next spot is completed. In contrast, the raster scan irradiation is a method in which irradiation is continuously performed without stopping irradiation in the middle of irradiation range for one layer. In this way, since the raster scan irradiation continuously irradiates the irradiation field of one layer with a beam, the irradiation field is not constituted by a plurality of points unlike the spot scan irradiation. In the following, the irradiation by the raster scan irradiation is described as an example, but the present invention is not limited to this, and the irradiation may be performed by the spot scan irradiation.

The irradiation nozzle 12 is attached to the inside of a rotating gantry 23 that can rotate 360 degrees around the treatment table 22, and can be moved to an arbitrary rotational position by the rotating gantry 23. The irradiation nozzle 12 includes a converging electromagnet 19, a scanning electromagnet 21 (scanning unit), a guide tube 28, and a multi-leaf collimator 30. The scanning electromagnet 21 is provided in the irradiation nozzle 12. The scanning electromagnet 21 includes an X-direction scanning electromagnet that scans the charged particle beam in the X direction on a plane intersecting the irradiation direction (Z direction) of the charged particle beam, and a Y-direction scanning electromagnet that scans the charged particle beam in the Y direction intersecting the X direction on a plane intersecting the irradiation direction (Z direction) of the charged particle beam, and is capable of scanning in the X direction and the Y direction. Since the charged particle beam scanned by the scanning electromagnet 21 is deflected in the X direction and/or the Y direction, the diameter of the duct 28 on the downstream side of the scanning electromagnet is wider toward the downstream side. The guide duct 28 is filled with a gas for suppressing divergence of the charged particle beam passing therethrough, or is internally in a vacuum state.

The multileaf collimator 30 shapes the irradiation field of the charged particle beam in accordance with the shape of the tumor (irradiation target) of the patient P. A multi-leaf collimator 30 is provided in the vicinity of the lower end in the conduit 28 on the downstream side of the scanning electromagnet 21. The details of the multi-leaf collimator 30 will be described later.

The beam transport line 13 has a vacuum conduit 14 for the charged particle beam to pass through. The inside of the vacuum duct 14 is maintained in a vacuum state, and scattering of charged particles constituting a charged particle beam in transit by air or the like is suppressed.

The energy degrader 18 on the beam transport line 13 adjusts the range of the respective charged particle beam by reducing the energy of the passing charged particle beam. Since the depth from the body surface of the patient P to the tumor, which is the irradiation object, varies depending on the patient, it is necessary to adjust the depth of arrival, i.e., the range, of the charged particle beam when irradiating the patient P with the charged particle beam. The energy degrader 18 adjusts the energy of the charged particle beam emitted from the accelerator 11 at a predetermined energy so that the charged particle beam appropriately reaches the irradiation target located at a predetermined depth in the patient. The energy adjustment of the charged particle beam by the energy degrader 18 is performed for each layer virtually divided into the irradiation objects. In addition, although the energy degrader 18 is used to adjust the energy of the charged particle beam when the accelerator 11 is a cyclotron, the energy degrader 18 can be omitted because the energy of the charged particle beam can be easily adjusted when the accelerator 11 is a synchrotron.

The electromagnets 25 are provided in plural on the beam transport path 13, and adjust the charged particle beam so that the charged particle beam can be transported on the beam transport path 13 by a magnetic field. The electromagnet 25 includes a converging electromagnet 19 for converging the beam diameter of the charged particle beam being transported and a deflecting electromagnet 20 for deflecting the charged particle beam. In the following, the focusing electromagnet 19 and the deflecting electromagnet 20 may be referred to as an electromagnet 25 without distinction. The plurality of electromagnets 25 are provided on the downstream side of the degrader 18 in at least the beam transport path 13, but may be provided on the upstream side of the degrader 18 in order to converge the beam diameter of the charged particle beam before energy adjustment by the degrader 18. The total number of electromagnets 25 can be flexibly changed according to the length of the beam transmission line 13, and may be, for example, about 10 to 40.

An electromagnet power supply (not shown) for supplying a current for generating a magnetic field is connected to each electromagnet 25. The strength of the magnetic field of the corresponding electromagnet 25 is set by adjusting the current supplied to the electromagnet 25.

The arrangement of the degrader 18 and the electromagnet 25 in the beam transmission line 13 is not particularly limited.

Next, the multi-leaf collimator 30 provided in the irradiation nozzle 12 will be described with reference to fig. 2 to 4.

Fig. 2 is a schematic perspective view showing the multi-leaf collimator 30, fig. 3 is a plan view (view viewed from the Z direction) of the multi-leaf collimator 30, and fig. 4 is an IV-IV view of fig. 3.

The multi-leaf collimator 30 includes a pair of

leaf groups

31 and 32 facing each other in the Y direction, and a pair of

blocks

35 and 36 provided on both ends of the pair of

leaf groups

31 and 32 and facing each other in the X direction.

As shown in fig. 3, the pair of

blade groups

31 and 32 face each other in the Y direction with the reference axis a therebetween in an XY plane orthogonal to the reference axis a. Each of the pair of

blade groups

31 and 32 is composed of a blade member 40 including a plurality of blades 41 that can independently advance and retreat in the Y direction.

The blade member 40 includes a blade 41, a support portion 42 that supports the blade 41, and a blade driving portion 43 that moves the blade 41. The blade member 40 is disposed along the XY plane such that the blade 41 of the blade member 40 included in the blade group 31 and the blade 41 of the blade member 40 included in the blade group 32 face each other.

The blade 41 is a rectangular plate-like member extending in the Y direction. The blade 41 is a member for blocking the charged particle beam, and is therefore made of a material capable of blocking the charged particle beam. Examples of the material capable of blocking the charged particle beam include brass, copper, tantalum, molybdenum, and the like, but a brass blade having high blocking ability is preferable.

The width (length in the Z direction) of the blade 41 is set so that the charged particle beam can be blocked by the blade 41. Therefore, when the leaf 41 is made of brass with high blocking capability, the width of the leaf 41 can be reduced, and the multi-leaf collimator 30 can be miniaturized.

The length of the blade 41 (the length in the Y direction) is set according to the maximum scanning range of the charged particle beam. The maximum scanning range of the charged particle beam is a range in which deflection of the charged particle beam by the scanning electromagnet 21 can be controlled. The length of the blade 41 can be set to be shorter than 1/2, which is the length in the Y direction of the maximum scanning range of the charged particle beam. The lower limit of the length of the blade 41 is preferably about 4 times the beam diameter of the charged particle beam emitted from the irradiation nozzle 12. By setting the length of the blade 41 in the above range, the charged particle beam can be blocked reliably and the multi-leaf collimator 30 can be miniaturized.

The thickness (length in the X direction) of the blade 41 is not particularly limited, but by reducing the thickness of the blade 41, the irradiation field of the charged particle beam can be shaped more finely by the multi-leaf collimator 30.

The blade 41 may be provided with a hard coating layer (hard coating layer) on the surface thereof by electroless nickel plating. The method of forming the hard coat layer is not limited to electroless nickel plating, and various methods can be applied. The hard plating layer may be formed on a part of the surface of the blade 41 or may be formed on the entire surface.

The support portion 42 that supports the blade 41 is attached to one end portion of the blade 41 in the longitudinal direction and extends in the Y direction. The material of the support portion 42 is not particularly limited. The support portion 42 may support the blade 41 in a state where the blade 41 can advance and retreat in the Y direction. Such a structure may be, for example, a structure in which the support portion 42 itself is stretchable, or may be a rod-shaped member in which the support portion 42 itself is not stretchable.

The blade driving unit 43 is a driving mechanism for advancing and retreating the blade 41 in the Y direction. When the support portion 42 of the blade member 40 is configured to be extendable and retractable, the extension and retraction of the support portion 42 is changed by the driving of the blade driving portion 43, so that the advance and retraction of the blade 41 in the Y direction can be controlled. When the support portion 42 of the blade member 40 does not extend or contract, the support portion 42 is moved by the driving of the blade driving portion 43, and the advance and retreat of the blade 41 integrated with the support portion 42 in the Y direction can be controlled. Further, the blade driving unit 43 may directly move the blade 41. At this time, the supporting portion 42 is not provided, and the blade driving portion 43 is directly connected to the blade 41.

The pair of

blade groups

31 and 32 are arranged such that, when viewed in the Y direction, both ends in the X direction in the maximum scanning range of the charged particle beam overlap the plurality of blades 41 included in the

blade groups

31 and 32. Specifically, as shown in fig. 4, the plurality of blades 41 included in the

blade groups

31 and 32 are arranged so that the length of the

blade groups

31 and 32 in the X direction is larger than the length of the maximum scanning range F2 of the charged particle beam when viewed from the Y direction.

The pair of

stoppers

35 and 36 are columnar members extending in the Y direction. The pair of

stoppers

35 and 36 are opposed to each other in the X direction with the reference axis a therebetween, in an XY plane orthogonal to the reference axis a and above (above in the Z direction) the pair of

blade groups

31 and 32. That is, the stopper 35 is provided to connect one end portions of the

blade groups

31 and 32 to each other, and the stopper 36 is provided to connect the other end portions to each other.

The

stoppers

35 and 36 are members for blocking the charged particle beam, and are therefore made of a material capable of blocking the charged particle beam. Examples of the material capable of blocking the charged particle beam include brass, copper, tantalum, molybdenum, and the like, but a brass barrier block having high barrier ability is preferably used.

The height (length in the Z direction) of the

stoppers

35 and 36 is set so that the charged particle beams can be blocked by the

stoppers

35 and 36. Therefore, when the

blocks

35 and 36 are made of tungsten or tantalum having high blocking ability, the height of the

blocks

35 and 36 can be reduced, and the multileaf collimator 30 can be downsized.

The length (length in the Y direction) of the

blocks

35 and 36 can be equal to or longer than the length in the Y direction of the maximum scanning range of the charged particle beam. As shown in fig. 3, the

stoppers

35 and 36 are arranged so as to include the maximum scanning range F1 of the charged particle beam in all Y directions.

The widths (lengths in the X direction) of the

blocks

35 and 36 are not particularly limited, but are preferably about 4 times the beam diameter of the charged particle beam emitted from the irradiation nozzle 12. By setting the widths of the

stoppers

35 and 36 to the above ranges, the charged particle beam can be reliably blocked and the multi-leaf collimator 30 can be miniaturized.

Stopper driving portions

37 and 38 are connected to the

stoppers

35 and 36, respectively, and the

stoppers

37 and 38 can be driven to advance and retreat in the X direction of the

stoppers

35 and 36.

In the multi-leaf collimator 30, the plurality of leaves 41 included in the pair of

leaf groups

31 and 32 are advanced and retreated in the Y direction, and the pair of

stoppers

35 and 36 are advanced and retreated in the X direction, so that the opening T can be formed at the center (see fig. 3). The shape of the opening T is matched to the shape of the object to be irradiated, so that the irradiation region of the charged particle beam can be defined. The shape of the aperture T is set according to a splitting plane (layer) for irradiating the object with the charged particle beam.

In the charged particle beam therapy system 1 according to the present embodiment, the charged particle beam emitted from the accelerator 11 and transmitted through the beam transmission line 13 is deflected in a predetermined direction by the scanning electromagnet 21, passes through the opening T formed in the multi-leaf collimator 30, further defines an irradiation region, and is irradiated to the patient P.

Conventionally, a multi-leaf collimator is generally applied to a charged particle beam therapy system of a wide beam method (enlargement irradiation method). In a charged particle beam therapy system using a wide beam method, a charged particle beam having a beam diameter larger than an irradiation object is irradiated to a patient P by cutting out a charged particle beam having an irradiation field corresponding to the shape of the irradiation object by applying a multi-leaf collimator to the charged particle beam.

On the other hand, in a charged particle beam therapy system that performs scanning irradiation, since irradiation of a charged particle beam is performed according to a scanning pattern corresponding to an irradiation object, it is considered that a system for shaping an irradiation field such as a multileaf collimator is not necessary. However, it is known that, even in a charged particle beam therapy system that performs scanning irradiation, the penumbra (side penumbra) of the charged particle beam emitted from the irradiation nozzle is still to be improved. That is, it is desirable that the dose distribution of the beam emitted from the irradiation nozzle is the same, but it is considered that the dose distribution at the beam edge may decrease and the dose of the charged particle beam at the end of the irradiation region may smoothly decrease.

Therefore, in the charged particle beam therapy system 1 according to the present embodiment, since the blade 41 blocks the charged particle beam by applying the multi-blade collimator 30 in addition to the scanning irradiation of the charged particle beam, the dose distribution of the charged particle beam in the peripheral portion of the irradiation region can be particularly improved, and the dose in the peripheral portion can be drastically changed.

In the charged particle beam therapy system 1 according to the present embodiment, the length of the blade 41 of the multi-blade collimator 30 is shorter than the half length of the scanning range of the charged particle beam in the Y direction. This makes it possible to reduce the space occupied by the multi-leaf collimator 30 and to reduce the size of the whole charged particle beam therapy system 1.

In a charged particle beam therapy system using a wide beam method (enlargement irradiation method), since a multi-leaf collimator for forming a charged particle beam having a beam diameter larger than that of an irradiation object into an irradiation region corresponding to the irradiation object is used, it is necessary to prepare a leaf capable of blocking all the charged particle beams in advance, and it is necessary to lengthen the leaf. In this case, since it is necessary to provide a space for moving the blades outside the pair of blade groups, the space occupied by the multi-blade collimator increases in size. Therefore, the irradiation nozzle itself accommodating the multileaf collimator is also large-sized.

In contrast, in the charged particle beam therapy system 1 for performing scanning irradiation according to the present embodiment, the beam diameter of the charged particle beam is very small compared to the wide beam method, and the blade can be sufficiently reduced because the beam diameter is used to control the dose distribution of the charged particle beam in the peripheral portion of the irradiation target. Therefore, the space in which the vanes can be moved can also be made smaller, and therefore, the space occupied by the multi-vane collimator 30 can be made smaller, and the irradiation nozzle can also be made smaller.

Further, if the size of the leaf 41 of the multi-leaf collimator 30 is reduced, the leaf 41 is easily moved. Therefore, the blades 41 can be moved at high speed, and thus the opening T of the multi-leaf collimator 30 can be controlled at higher speed.

Further, if the support portion 42 of the blade member 40 is configured to be expandable and contractible, the amount of movement of the support portion 42 accompanying the movement of the blade member 40 can be reduced. Therefore, it is not necessary to secure a space necessary for the support portion 42 to move along with the movement of the leaf 41, and the space occupied by the multi-leaf collimator 30 can be further reduced in size.

In order to enhance the effect of improving the dose distribution of the charged particle beam by the blades 41 of the blade member 40, the blades 41 are preferably configured to be swingable about the X direction as an axis. In this regard, the description is made with reference to fig. 5.

Fig. 5 shows a configuration in which the blade 41 of the blade member 40 is rotated about the X direction along the YZ plane, and the end surface 41a is tilted by an angle α with respect to the direction (Z direction) in which the reference axis a extends. The end surface 41a is an end surface on the side facing the blade group. The angle α is set according to the irradiation direction of the charged particle beam.

In the charged particle beam therapy system 1 that performs scanning irradiation, since the charged particle beam is irradiated by deflecting the scanning electromagnet 21, the charged particle beam is irradiated in a state inclined from the reference axis a as the irradiation position of the charged particle beam is farther from the reference axis a. When the charged particle beam is irradiated in a state inclined with respect to the reference axis a in this manner, there is a possibility that the dose of the charged particle beam at the peripheral portion of the irradiation region is smoothly decreased. On the other hand, by configuring the blade 41 to be swingable about the axis extending in the X direction with respect to the support portion 42 and configuring the end surface of the blade 41 to be inclined in accordance with the inclination of the charged particle beam, scattering of the charged particle beam at the end of the blade 41 and the like can be suppressed, and the dose distribution of the charged particle beam can be further improved.

A method of configuring the blade 41 to be swingable about an axis extending in the X direction with respect to the support portion 42 is not particularly limited. For example, in the example of fig. 5, the number of the support portions 42 attached to the blade 41 is 2, and each is attached to be rotatable about the X direction with respect to the blade 41. With this configuration, the blade 41 can be swung about an axis extending in the X direction by making the amounts of movement of the 2 holding members in the Y direction different from each other.

Fig. 6 shows an example of a structure in which the support portion is extendable and retractable, and a blade member 40A in which the blade is swingable with respect to the support portion. Fig. 6(a) to 6(C) are views illustrating the structure of the blade member 40A, the expansion and contraction of the support portion 42A, and the swinging of the blade 41.

In the blade member 40A shown in fig. 6(a), the support portion 42A is formed of a plurality of

cylindrical members

421, 422, 423 and a rod-like member. These

cylindrical members

421, 422, 423 are connected so as to be slidable in the Y direction in this order, and the outer diameters of the cylindrical member 421 on the front end side (the blade 41 side), the cylindrical member 422 connected to the cylindrical member 421, and the cylindrical member 423 connected to the cylindrical member 422 are sequentially increased. The cylindrical member 421 can be accommodated inside the cylindrical member 422, and the cylindrical member 422 can be accommodated inside the cylindrical member 423. The cylindrical member 421 is attached to the blade 41 to be rotatable about an axis extending in the X direction. A rod-like member 425, for example, formed of a wire or the like, extending in the Y direction unlike the cylindrical member 421 is attached to the blade 41 so as to be rotatable about an axis extending in the X direction.

In the case of the blade member 40A, the blade 41 can be advanced and retreated in the Y direction by changing the relative positions of the

cylindrical members

421, 422, 423. For example, as shown in fig. 6(a), the

cylindrical members

421, 422, and 423 are sequentially extended in the Y direction, and the vane 41 is moved in the-Y direction. As shown in fig. 6(B), the

cylindrical members

421, 422 are accommodated in the cylindrical member 423, that is, the

cylindrical members

421, 422, 423 are overlapped with each other, and the vane 41 is moved in the + Y direction. Then, by changing the relative position of the rod-like member 425 with respect to the

cylindrical members

421, 422, and 423 in the Y direction, the blade 41 is swung about an axis extending in the X direction with respect to the support portion 42A as shown in fig. 6 (C).

In this manner, the configuration of the blade member 40A, particularly the configuration for controlling the advance and retreat of the blade 41 in the Y direction and the swing about the axis extending in the X direction, can be variously modified.

The present invention is not limited to the above embodiments. For example, the installation position of the multi-leaf collimator 30 is not limited as long as it is located downstream of the scanning electromagnet 21 in the irradiation nozzle 12.

The configuration of the multi-leaf collimator 30 can also be modified as appropriate. For example, the configuration in which the pair of

stoppers

35 and 36 are each constituted by one stopper has been described, but each of the

stoppers

35 and 36 may be constituted by a plurality of stoppers. Further, the shape of the blade 41 and the structure for advancing and retreating the blade in the Y direction can be appropriately changed. Further, the mechanism, arrangement, and the like of the blade driving section for advancing and retracting the blade can be appropriately changed.

Claims

1. A charged particle beam therapy device for irradiating a charged particle beam to an irradiation object, the charged particle beam therapy device comprising:

an accelerator that generates and emits the charged particle beam;

an irradiation nozzle configured to irradiate the charged particle beam to an irradiation target; and

a transmission line connecting the accelerator and the irradiation nozzle and transmitting the charged particle beam,

an axis orthogonal to a reference axis when the charged particle beam is irradiated is defined as a 1 st axis, an axis orthogonal to the reference axis and the 1 st axis is defined as a 2 nd axis,

the irradiation nozzle has:

a scanning unit capable of scanning the charged particle beam in a direction along the 1 st axis and a direction along the 2 nd axis within a preset maximum scanning range; and

a multi-leaf collimator provided downstream of the scanning unit and defining a shape of an irradiation region in which the charged particle beam is irradiated to the irradiation target,

the multi-leaf collimator includes a pair of leaf groups provided to face each other with the reference axis therebetween,

the blade group has:

a plurality of blades which are arranged in parallel in the direction along the 1 st axis, can independently advance and retreat in the direction along the 2 nd axis, and block the charged particle beam; and

a blade driving unit that moves the blade back and forth in the direction along the 2 nd axis,

a length of each of a plurality of the blades in a direction along the 2 nd axis of at least some of the plurality of the blades is shorter than a half of a length of the maximum scanning range in the direction along the 2 nd axis,

each of the plurality of blades is configured to independently swing about a 3 rd axis extending in the same direction as the 1 st axis.

2. The charged particle beam therapy apparatus according to claim 1, further comprising:

and a pair of stoppers that are provided on both end sides of the blade group in the direction along the 1 st axis, have a length in the direction along the 2 nd axis equal to or greater than a length in the direction along the 2 nd axis of the maximum scanning range, and block the charged particle beam.

3. Charged particle beam therapy device according to claim 1 or 2,

the blade group has a support portion that supports the blades,

the blade is configured to swing about an axis along the 1 st axis with respect to the support portion.