JP2011050660A - Particle beam medical treatment system and particle beam irradiation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology for making a non-circular beam approximate to a circular beam in irradiation using a particle beam having a small diameter. <P>SOLUTION: The particle beam medical treatment system includes: an accelerator accelerating a charged particle beam; a particle beam irradiating device irradiating a target region with the charged particle beam emitted from the accelerator; a beam transport system for connecting the accelerator to the particle beam irradiating device; and a scatterer having at least a first scattering member and a second scattering member formed of a material whose scattering angle of the charged particle beam is larger than that of the first scattering member, wherein the scatterer is disposed so that the major axis of the second scattering member crosses a region having a smaller beam diameter of the passing charged particle beam in a beam passing region of the beam transport system. Thus, the above problem is solved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a particle beam therapy system and a particle beam irradiation method, and more particularly to a particle beam therapy system suitable for forming a high-dose region in a dose distribution using a beam having a beam size ratio close to 1. The present invention relates to a particle beam irradiation method.

  The particle beam therapy system is one of the effective means of cancer treatment that irradiates the affected part of a patient with a charged particle beam such as a proton beam or a heavy particle beam (carbon beam, etc.), and is expected to be actively used in the future. . The particle beam therapy system is required to control the dose distribution of the affected area (target region) of a patient to a uniform or predetermined distribution.

  The formation of a dose distribution in the traveling direction (depth direction) of a charged particle beam is characterized by the fact that most of the energy is released immediately before the charged particle beam stops to form a dose distribution called a Bragg curve, and the Bragg curve. The position in the depth direction of the Bragg peak, which is the peak of, utilizes the characteristics that can be controlled by the magnitude of the energy of the charged particle beam incident on the body. In particle beam therapy, the energy of a charged particle beam is appropriately selected, and the charged particle beam is stopped in the vicinity of the affected area so that most of the energy is given to cancer cells in the affected area. Here, the width of the Bragg peak in the depth direction is several mm. Usually, the affected area has a greater thickness in the depth direction. In order to effectively irradiate a charged particle beam in the depth direction of the entire affected area in such an affected area, the high dose region (SOBP: Spread Out Bragg Peak) that spreads to the affected area in the depth direction and has high uniformity. Therefore, it is necessary to control the energy of the charged particle beam and the irradiation amount of the charged particle beam.

  For the formation of the dose distribution in the traveling direction (depth direction) of the charged particle beam, a method using a ridge filter, RMW (Range Modulation Wheel) or the like, or a method of changing the energy species of the charged particle beam emitted from the accelerator, It is known to form SOBP.

  As a method for uniformly controlling the dose distribution, on the surface perpendicular to the traveling direction of the charged particle beam (irradiation field surface), a method of expanding the charged particle beam using a scatterer, or a charged particle beam having a small beam diameter is used. There is a method of scanning the irradiation field surface by using.

JP 2007-37629 A

  In the particle beam therapy system, it is desirable to use a charged particle beam having a shape close to a circle on a plane (irradiation field plane) perpendicular to the traveling direction of the charged particle beam. The aspect ratio of the charged particle beam in the irradiation field plane is called the beam size ratio. The beam size ratio closer to 1 is closer to a circle, but the beam accelerated by the accelerator is not necessarily circular.

  Patent Document 1 discloses a particle beam treatment in which a first scatterer and a second scatterer that expand an irradiation range of a charged particle beam in a radial direction (a direction perpendicular to a beam traveling direction) are arranged in a particle beam irradiation apparatus. A system is disclosed. The first scatterer is made of a material having a large beam scattering amount of the charged particle beam, and expands the dose distribution in the beam radial direction into a normal distribution. The second scatterer includes a disk portion made of a material having a large beam scattering angle of the charged particle beam, and a ring portion made of a material having a small beam scattering angle of the charged particle beam. It has a double ring structure. Such a second scatterer has a function of uniformly expanding the dose distribution in the beam diameter direction of the charged particle beam that has passed through the first scatterer.

  On the other hand, in the irradiation method in which the irradiation field surface is scanned using a charged particle beam having a small beam diameter, if the beam size ratio deviates greatly from 1, the irradiation spot position is adjusted on the irradiation field surface from the viewpoint of forming a dose distribution. It was found that it was necessary to obtain dose uniformity. When the beam size ratio fluctuates, it is necessary to adjust the irradiation spot position according to the size of the beam size ratio, which is a big problem. Therefore, in order to make the dose distribution in the irradiation field uniform or predetermined, the beam shape of the charged particle beam needs to be circular (a beam having a beam size ratio close to 1).

  When the beam size ratio of the charged particle beam deviates greatly from 1, it is possible to adjust the shape of the charged particle beam (close to a circle) by using an electromagnet device of a beam transport system. However, in the case of a particle beam therapy system including a rotating gantry, the electromagnet apparatus needs to adjust the shape of the charged particle beam for each rotation angle of the rotating gantry, and such adjustment requires much more labor. In order to save labor, it is important to make the beam size ratio close to 1 in order to reduce the adjustment of the beam size regardless of the rotation angle of the rotating gantry. In particular, it is important to develop means for bringing the beam shape of a charged particle beam having a small beam diameter closer to a circle.

The present inventors have made various studies on a method of adjusting a beam shape by installing a scatterer on the beam trajectory of a charged particle beam. The scatterer imparts an isotropic scattering angle to the charged particle beam. In the case of a particle having a large scattering angle, even if the beam shape before passing through the scatterer is non-circular, it approaches a circular shape after scattering. When a flat plate is used as the scatterer, scattering occurs isotropically, and therefore, a scattering angle is given to both the non-circular major axis and minor axis. For this reason, in order to make a non-circular beam close to a circle, it is necessary to increase the scattering angle so as to fill the difference between the long axis and the short axis. In this case, the major axis of the non-circular beam also has a larger diameter, which is not suitable for irradiation that uses a beam having a small diameter. Conversely, if the scattering angle is kept small, the approach to the circular shape is poor and the non-circular shape remains.
An object of the present invention is to provide a particle beam treatment system and a particle beam irradiation method for making a beam shape close to a circle in a plane perpendicular to the traveling direction of a charged particle beam in irradiation using a charged particle beam having a small beam diameter. is there.

  (1) To achieve the above object, the present invention provides an accelerator for accelerating a charged particle beam, a particle beam irradiation apparatus for irradiating a target region with a charged particle beam emitted from the accelerator, an accelerator, and particle beam irradiation. A beam transport system connecting the apparatus, a scatterer having a plurality of scattering members having different scattering angles, and a beam passing region of the beam transport system, wherein a region where the beam diameter of the charged particle beam passing through is short is a second scattering member By providing a scatterer control device that arranges the scatterer so that the long axis of the non-circular beam crosses, a non-circular beam shape is formed into a circular shape so as to form a high-dose area of the affected part size at the affected part position. .

  (2) In the above (1), preferably, a central control device for obtaining a beam shape of the charged particle beam before passing through the scatterer and outputting a movement command signal regarding the arrangement position and rotation angle of the scatterer is provided, The body control device can obtain a charged particle beam having a desired beam shape by moving and rotating the scatterer based on the movement command signal from the central control device.

  (3) In the above (1), preferably, the target region is irradiated with the particle beam by scanning the particle beam with a scanning electromagnet.

  (4) In the above (1), preferably, the plurality of scattering members having different scattering angles are a first scattering member and a second scattering member composed of a substance having a scattering angle of a charged particle beam larger than that of the first scattering member. At least a member, and the scatterer has a configuration in which the second scattering member is disposed between the plurality of first scattering members, and the water-equivalent flight of the charged particle beam that has passed through the first scattering member and the second scattering member. The scatterer control device arranges the scatterer at a position where the charged particle beam passes through the first scattering member and the second scattering member.

  (5) In the above (4), preferably, the width in the minor axis direction of the second scattering member is smaller than the length in the major axis direction of the beam diameter before passing through the scatterer, and the major axis of the second scattering member. The width in the direction is configured to be larger than the length in the minor axis direction of the beam diameter before passing through the scatterer.

  (6) In the above (1), (2), and (3), preferably, the scatterer has a configuration in which a plurality of first scattering members and second scattering members are alternately arranged, and the first scattering member and the second scattering member. The scatterer control device has a thickness such that the water equivalent range of the charged particle beam that has passed through the member is the same, and the scatterer control device is configured to scatter the charged particle beam at a position where the charged particle beam passes through the first scattering member and the second scattering member. An anisotropic scatterer characterized in that the non-circular beam is made more circular by arranging the body is used.

  (7) In the above (6), preferably, the scatterer is provided with a plurality of second scattering members around the beam center, and the width and interval of the second scattering member are gradually reduced from the beam center to the end. The configuration is as follows.

  (8) In the above (1), (2), and (3), preferably, the scatterer is a first scattering member and a second scattering composed of a substance having a scattering angle of the charged particle beam larger than that of the first scattering member. And a support member that supports the first scattering member and the second scattering member, the first scattering member is disposed on one surface of the support member, and the first support member is disposed on the other surface of the support member. The second support member is arranged so that a part thereof overlaps, and the charged particle beam having passed through the first scattering member and the second scattering member has a thickness such that the water equivalent range is the same, and is scattered. The body control device can make the non-circular beam more circular by arranging the scatterer at a position where the charged particle beam passes through the first scattering member and the second scattering member.

  (9) An accelerator that accelerates a charged particle beam, a particle beam irradiation device that irradiates a target region with a charged particle beam emitted from the accelerator, a beam transport system that connects the accelerator and the particle beam irradiation device, and scattering of the charged particle beam A plurality of scattering members having different angles are arranged, and as the distance from the center of the beam increases, a scattering member having a smaller scattering angle is arranged, and a beam passing region of the beam transport system in which the beam diameter of the charged particle beam passing through is short. By providing a scatterer control device that arranges the scatterer so that the long axis of the scattering member having the largest scattering angle among the scattering members crosses, the non-circular beam can be made more circular.

  (10) In the above (9), preferably, the scatterer has a thickness such that the water equivalent ranges of the charged particle beams that have passed through the plurality of scattering members having different scattering angles are the same.

  (11) An accelerator that accelerates the charged particle beam, a particle beam irradiation device that irradiates the target region with the charged particle beam emitted from the accelerator, a beam transport system that connects the accelerator and the particle beam irradiation device, and first scattering And a scatterer having a second scattering member made of a material having a scattering angle of the member and the charged particle beam larger than that of the first scattering member, and a scatterer control device for arranging the scatterer in a beam passage region of the beam transport system. In the particle beam irradiation method of the particle beam therapy system, the scatterer control device arranges the scatterer so that the long axis of the second scattering member crosses the region where the beam diameter of the charged particle beam is short. The charged particle beam that has passed is transported to a particle beam irradiation device, and the transported charged particle beam is deflected by a scanning electromagnet in the particle beam irradiation device and emitted, so that a high-dose region is irradiated on the target region. It was to be formed.

  By such a method, the beam shape whose beam size ratio is greatly deviated from 1 can be made into a nearly circular shape, so there is no need to adjust every gantry rotation angle, and dose distribution is independent of the gantry angle. Uniformity can be easily formed.

  According to the present invention, since the beam shape of the charged particle beam can be made close to a circle, there is no need to adjust the beam shape for each rotation angle of the rotating gantry, and the desired shape can be obtained without depending on the rotating angle of the rotating gantry. The dose distribution can be obtained.

1 is a system configuration diagram of a particle beam therapy system according to a first embodiment of the present invention. It is a block diagram of the particle beam irradiation apparatus used for the particle beam therapy system by the 1st Embodiment of this invention. It is the figure which showed the structure of the scatterer by the 1st Embodiment of this invention. It is explanatory drawing of the scatterer by the 1st Embodiment of this invention. It is explanatory drawing of the scatterer by the 1st Embodiment of this invention. It is the figure which showed the structure of the scatterer by other embodiment of this invention. It is the figure which showed the structure of the scatterer by other embodiment of this invention. It is the figure which showed the structure of the scatterer by other embodiment of this invention.

  In a particle beam therapy system consisting of a particle beam irradiation device that irradiates a target region with a particle beam, an accelerator, and a transport system that connects them, the scattering angle is adjusted so that the water equivalent range is the same. A material with a large scattering angle arranged in a band is made shorter than the length in the long axis direction of the non-circular beam, and the material in the long axis direction of a material with a large scattering angle is arranged in a band shape. Using an anisotropic scatterer whose length is longer than the length of the non-circular beam in the short axis direction, the width of the non-circular beam in the short axis direction is greatly enlarged to make the non-circular beam shape a circular shape, A high-dose area having an affected part size at the affected part position is formed.

  The configuration and operation of the particle beam therapy system according to the first embodiment of the present invention will be described with reference to FIGS.

  First, the configuration of the particle beam therapy system 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a system configuration diagram of a particle beam therapy system 100 according to the first embodiment.

  The particle beam therapy system 100 of the present embodiment includes a pre-stage accelerator (for example, a linear accelerator) 1, a circular accelerator (for example, a synchrotron) 2, a beam transport system 3, a rotating gantry 4, a particle beam irradiation apparatus 5, a control apparatus 6, and A patient support device 8 is provided.

  The front stage accelerator 1 is connected to an ion source (not shown) and a synchrotron 2. The synchrotron 2 includes a high-frequency accelerating cavity 30 that is a beam accelerator, a high-frequency applying device 31, an output deflector 32, a quadrupole electromagnet 33, and a deflecting electromagnet 34. An exit deflector 32 is connected to the beam transport system 3.

The beam transport system 3 includes a scatterer 14, a beam path 35, a quadrupole electromagnet 36 and a deflection electromagnet 37. A scatterer 14, a quadrupole electromagnet 36, and a deflection electromagnet 37 are arranged along the beam path 35. The scatterer 14 is connected to the scatterer control unit 15 via the scatterer driving device 24.
The particle beam irradiation device 5 is installed in the rotating gantry 4 in the rotating gantry 4 including the inverted U-shaped beam path 35 which is a part of the beam transport system 3. By rotating the rotating gantry 4, the irradiation direction of the charged particle beam to the patient 7 can be changed. A beam transport system 3 connects the synchrotron 2 and the particle beam irradiation apparatus 5.

  The internal structure of the particle beam irradiation apparatus 5 is demonstrated using FIG. FIG. 2 is a configuration diagram of the particle beam irradiation apparatus 5 used in the particle beam therapy system 100. The particle beam irradiation apparatus 5 has a casing (not shown). This casing is attached to the rotating gantry. Inside the casing, a beam profile monitor 12, a scanning electromagnet 13, a dose monitor 17, a block collimator 18, and a multi-leaf collimator 19 are arranged on the beam path (beam axis) from the upstream side in the beam traveling direction of the charged particle beam. ing. The beam profile monitor 12 is a monitor for confirming whether a charged particle beam incident on the particle beam irradiation device 5 from the beam path 35 through the beam transport system 3 is located on the beam axis. The scanning electromagnet 13 deflects and scans the charged particle beam that passes therethrough. The scanning electromagnet 13 is for deflecting the charged particle beam in directions (X direction, Y direction) orthogonal to each other on a plane perpendicular to the beam axis, for example, and moving the irradiation position in the X direction and the Y direction. The dose monitor 17 is a monitor that detects the dose of the charged particle beam incident on the particle beam irradiation apparatus 5. The block collimator 18 has an opening for shaping the irradiation field shape of the charged particle beam on a plane perpendicular to the beam axis, and shields the charged particle beam outside the opening. The multi-leaf collimator 19 has a large number of thin plates that shield the charged particle beam, and moves the thin plate into a plane perpendicular to the beam axis so that the region through which the charged particle beam passes has an arbitrary shape (of the patient 7). The shape of the affected part). Reference numeral 20 denotes an isocenter which is a center for applying a charged particle beam to the patient 7.

  As shown in FIG. 1, the control device 6 includes an accelerator / transport system control unit 9, an irradiation device control unit 10, a scatterer control unit 15, and a central control unit 11. The central controller 11 is connected to the accelerator / transport system controller 9, the irradiation device controller 10, and the scatterer controller 15, and outputs command signals to these controllers. The central control unit 11 is connected to the beam transport system 3, the treatment planning device 25, and the display device 26. The accelerator / transport system control unit 9 is connected to the front stage accelerator 1, the synchrotron 2 and the beam transport system 3. Based on the command signal from the central control unit 11, the front stage accelerator 1, the synchrotron 2 and the beam transport system 3 are connected. Control. The irradiation device controller 10 is connected to the particle beam irradiation device 5 and controls each device in the particle beam irradiation device 5 based on a command signal from the central control device 11. The irradiation device control unit 10 has a function of adjusting the power supplied to the scanning electromagnet 13 disposed in the particle beam irradiation device 5 to form a scanning magnetic field to adjust the scanning amount of the charged particle beam. The scatterer control unit 15 is connected to the scatterer driving device 24. The scatterer control unit 15 selects a desired scatterer 14 from a plurality of scatterers based on a command signal from the central control device 11, and the selected scatterer 14 is arranged on the beam trajectory. In this manner, the drive command signal is output to the scatterer driving device 24.

  The treatment planning device 25 obtains treatment plan information based on patient information (position and size of affected area, irradiation direction of charged particle beam, maximum irradiation depth, etc.) input in advance by a doctor. This treatment plan information includes the beam energy of the charged particle beam, the range of the charged particle beam, the SOBP width, the irradiation field diameter, the installation position of the patient support device 8, and the like. The treatment planning device 25 stores this treatment plan information in a storage device (not shown) in the treatment planning device 25 and also stores it in a storage device (not shown) in the central control unit 11.

  The central control unit 11 reads, from the storage device in the central control unit 11, for example, treatment plan information related to the patient 7 to be treated in accordance with patient identification information input from an input device such as a keyboard or a mouse. Based on this treatment plan information, the central control unit 11 controls control commands for the high-frequency accelerating cavity 30, the high-frequency applying device 31, the deflector 32 for extraction, the quadrupole electromagnet 33, and the deflecting electromagnet 34 that constitute the synchrotron 2 (accelerator control Command data), control command data (transport system control command data) for each device such as the quadrupole electromagnet 36 and the deflection electromagnet 37 constituting the beam transport system 3, and the scatterers 14 arranged on the beam trajectory of the beam transport system 3 Control command data (scattering body control command data) and control command data (irradiation device control command data) for each device such as the block collimator 18 and the multi-leaf collimator 19 constituting the particle beam irradiation device 5 are created. The accelerator control command data and the transport system control command data created in this way are output to the accelerator / transport system control unit 9, the scatterer control command data is output to the scatterer control unit 15, and the irradiation device control command data is It is output to the irradiation device control unit 10.

  The patient support device 8 carrying the patient 7 to be irradiated with the charged particle beam is moved and positioned under the particle beam irradiation device 5 so that the affected part is located on the extension line of the beam axis. The accelerator / transport system controller 9 having received the accelerator control command data and the transport system control command data from the central controller 11 excites the electromagnets of the synchrotron 2 and the beam transport system 3. In addition, the irradiation device control unit 10 that has input the irradiation device control command data arranges the block collimator 18 created in accordance with the shape of the affected part of the patient 7 to be treated on the beam trajectory. The thin plate is moved to form an opening so as to fit the affected area of the patient 7. When the preparation for emitting the charged particle beam is completed as described above, the doctor outputs a treatment start signal to the central control unit 11 from the operation panel of the control room.

  The central control unit 11 receiving the treatment start signal activates the ion source. Ions generated from the ion source (for example, proton ions, carbon ions, etc.) are accelerated by the front stage accelerator 1. The charged particle beam emitted from the front accelerator 1 is incident on the synchrotron 2. The charged particle beam is accelerated by being given energy by the high frequency power applied from the high frequency acceleration cavity 30 by the synchrotron 2.

  After the energy of the charged particle beam that circulates inside the synchrotron 2 is increased to the set energy, a high frequency is applied to the charged particle beam from the high frequency application device 31 for emission. The charged particle beam orbiting within the stability limit moves out of the stability limit by application of high frequency by the high frequency application device 31, and is emitted from the synchrotron 2 through the extraction deflector 32. When the charged particle beam is emitted, the current guided to the electromagnets such as the quadrupole electromagnet 33 and the deflection electromagnet 34 provided in the synchrotron 2 is held at the set value, and the stability limit is also kept almost constant. By stopping the application of the high-frequency power to the high-frequency application device 31, the emission of the charged particle beam from the synchrotron 2 is stopped.

  The charged particle beam emitted from the synchrotron 2 reaches the particle beam irradiation device 5 through the beam transport system 3. The irradiation device controller 10 controls the power supplied to the scanning electromagnet 13 in the particle beam irradiation device 5 to form a scanning magnetic field and scan the charged particle beam.

  As a method of irradiating the irradiation field perpendicular to the traveling direction of the charged particle beam, there is a method such as spot scanning or raster scanning of the particle beam using the scanning electromagnet 13.

  Next, the configuration of the scatterer 14 of the particle beam therapy system 100 according to the present embodiment will be described with reference to FIGS.

  The scatterer 14 will be described with reference to FIG. FIG. 3 shows an example of the scatterer 14. The scatterer 14 of this embodiment is an anisotropic scatterer, and two types of substances having different scattering angles are arranged, and the thickness is adjusted so that the range of water equivalent thickness is the same. The first scattering members 21a and 21b are made of a material having a small scattering angle, and the second scattering member 22 is made of a material having a large scattering angle. The first scattering members 21 a and 21 b are made of a material that is smaller than the scattering angle of the second scattering member 22. The second scattering member 22 is disposed between the first scattering member 21a and the first scattering member 21b. The anisotropic scatterer 14 is constructed so that the major axis direction of the second scattering member 22 is perpendicular to the major axis direction of the non-circular beam. It is desirable that the first scattering member 21 is smaller than the second scattering member 22 so that the scattering angle can be ignored. In this case, the role of the first scattering members 21 a and 21 b is to support the second scattering member 22. For example, the first scattering members 21a and 21b are made of ABS or aluminum, which is a kind of resin, as a material having a small scattering angle, and the second scattering member 22 is made of tungsten or the like as a material having a large scattering angle.

  The particle beam therapy system 100 of the present embodiment prepares a plurality of scatterers. Each scatterer has a configuration in which the second scattering member is sandwiched between the two first scattering members, as described above. The thicknesses of the first scattering member and the second scattering member are adjusted so that each scatterer has the same range of water equivalent thickness. The plurality of scatterers have a configuration in which the length (width) in the minor axis direction of the second scattering member is different. By preparing a plurality of scatterers having different widths of the second scattering member and arranging the scatterers on the beam trajectory in accordance with the beam size ratio of the charged particle beam, a charged particle beam having a nearly circular shape can be obtained. it can.

  A state in which the amount of scattering of the charged particle beam is made anisotropic using the difference in scattering angle between the first scattering member and the second scattering member will be described with reference to FIG. FIG. 4A is a view of the second scattering member 22 viewed from the long axis direction in the direction perpendicular to the beam axis. The charged particle beam that has passed through the second scattering member 22 is scattered, and the beam size expands in the Y-axis direction. FIG. 4B is a view of the second scattering member 22 viewed from the short axis direction in the direction perpendicular to the beam axis. The beam size of the charged particle beam incident on the scatterer 14 is larger than the width of the second scattering member 22 in the minor axis direction. The width of the second scattering member 22 in the minor axis direction needs to be configured to be smaller than the beam size of the incident charged particle beam. The charged particle beam that has passed through the second scattering member 22 is scattered and the spread of the beam increases. Since the charged particle beam that has passed through the first scattering members 21 a and 21 b has a small scattering angle, the beam size is smaller than that of the charged particle beam that has passed through the second scattering member 22. For this reason, there is almost no expansion of the beam size in the X-axis direction. As a result, the charged particle beam that has passed through the scatterer 14 has almost no beam expansion in the X direction, which is the major axis direction of the non-circular beam, and the beam expansion in the Y direction, which is the minor axis direction of the beam, increases. The beam shape approaches a circle.

  FIG. 5 shows the situation. FIG. 5 is a view as seen from the beam axis direction. FIG. 5A shows the beam shape of the charged particle beam before passing through the scatterer 14. The charged particle beam has a non-circular shape. FIG. 5B shows the beam shape of the charged particle beam after passing through the scatterer 14. In the non-circular beam of FIG. 5A, the major axis direction of the scatterer 14 is the same as the minor axis direction of the non-circular beam, and the charged particle beam is greatly scattered by the second scattering member 22, and the minor axis direction of the beam. The distance increases. On the other hand, since the end of the charged particle beam in the long axis direction passes through the first scattering member 21 made of a material having a small scattering angle, the scattering is small and the long axis direction distance of the charged particle beam is increased. Is small. As a result, even if the beam shape before passing through the scatterer 14 is non-circular, the beam shape approaches a circle by passing through the scatterer 14. Thus, the non-circular beam passes through the anisotropic scatterer 14 and approaches a circular shape.

The scattering angle is σ = √ (σ ₁ ² + σ ₂ ² ) using the original scattering angle σ _{1 of the} beam and the scattering angle σ ₂ of the scatterer. Is required. When the ratio of the X component and the Y component of the beam scattering angle before passing through the scatterer is (X ₁ ′, Y ₁ ′) = (1, 5), the scattering angle by the isotropic scatterer is, for example, (X _{If 2} ′, Y ₂ ′) = (5, 5) is used, the beam scattering angle after passing through the scatterer is (X ′, Y ′) = (5.1, 7.1), which is a non-circular shape. To a lesser extent, non-circularity remains. To further reduce the degree of non-circularity, the scattering angle can be increased, but the beam size increases. On the other hand, if, for example, (X ₂ ′, Y ₂ ′) = (5, 1) is used as the scattering angle by the anisotropic scatterer, the beam scattering angle after passing through the anisotropic scatterer is ( X ′, Y ′) = (5.1, 5.1), and it can be made closer to a circle without increasing the beam diameter.

  Next, the installation location and operation of the scatterer 14 will be described. The scatterer 14 needs to be installed on the synchrotron 2 side upstream of the scanning electromagnet 13 shown in FIG. 2 and on the downstream side of the output deflector 32 constituting the synchrotron 2. When the gantry rotation is performed, the scatterer 14 needs to be installed on the accelerator side upstream of the entrance of the rotating gantry 4 and on the downstream side of the output deflector 32 constituting the synchrotron 2. For example, as shown in FIG. 1, on the beam trajectory of the beam transport system 3, on the upstream side of the entrance portion of the rotating gantry 4, on the downstream side of the exit deflector 32 constituting the synchrotron 2, Is installed. The scatterer 14 is connected to the scatterer driving device 24 and the scatterer controller 15. The central control unit 11 receives excitation current information for a quadrupole electromagnet disposed in the beam transport system 3, and a rotation angle indicating the tilt of the charged particle beam (the tilt of the non-circular beam) in a plane perpendicular to the beam transport axis. Ask for information. Further, the central control unit 11 obtains the arrangement position and rotation angle of the scatterer 14 based on the rotation angle information, and sends the movement command signal related to the arrangement position of the scatterer 14 and the rotation command signal related to the rotation angle to the scatterer control unit 15. Output to. The scatterer control unit 15 moves and rotates the scatterer 14 based on the received movement command signal and rotation command signal. When the scatterer control unit 15 moves and rotates the scatterer 14, the scattering angle of the anisotropic scatterer increases in the minor axis direction of the charged particle beam, and the anisotropic scatterer increases in the major axis direction of the charged particle beam. The scatterer 14 can be arranged so that the scattering angle becomes smaller. By passing the charged particle beam through the scatterer 14 whose arrangement is adjusted in this way, the non-circular charged particle beam is shaped into a circle.

  In order to make the non-circular beam circular, it is necessary to adjust the magnetic field of the rotating gantry 4 for each rotation angle of the rotating gantry 4, but by installing the scatterer 14 on the upstream side of the rotating gantry 4, Since the shape can be made circular, it is not necessary to adjust the magnetic field of the rotating gantry 4 for each gantry rotation angle.

  Further, when the energy of the charged particle beam is different, the scattering angle of the charged particle beam when passing through the scatterer 14 is different. For this reason, when the energy of the charged particle beam accelerated by the synchrotron 2 is changed, it is necessary to change the type of the scatterer 14 installed on the beam trajectory. In a certain energy range, the same scatterer can be used. In the particle beam therapy system 100 of the present embodiment, a plurality of scatterers are prepared in advance and switched when the energy is changed. In order to switch the scatterer 14, a scatterer driving device 24 is installed.

  As described above, an irradiation apparatus of a particle beam therapy system using a charged particle beam has been shown. In addition to protons, there are also heavy particle beams such as carbon and helium, and this apparatus and this irradiation method can be applied.

  Hereinafter, a particle beam therapy system according to another embodiment of the present invention will be described.

  The particle beam therapy system 101 of the present embodiment has a configuration in which the scatterer 14 installed on the beam trajectory of the beam transport system 3 in the particle beam therapy system 100 of the first embodiment is replaced with a scatterer 14A.

The configuration of the scatterer 14A of this example will be described with reference to FIG. The scatterer 14A is an anisotropic scatterer, in which two kinds of substances having different scattering angles are arranged, and the thickness is adjusted so that the range of water equivalent thickness is the same. The first scattering members 21a, 21b and 21c are made of a material having a small scattering angle, and the second scattering members 22a, 22b, 22c and 22d are made of a material having a large scattering angle. The scattering angles of the first scattering members 21a, 21b, and 21c are smaller than the scattering angles of the second scattering members 22a, 22b, 22c, and 22d. The scatterer 14A is configured by arranging a plurality of examples of the first scattering member and the second scattering member. The first scattering member 21a is disposed between the second scattering member 22a and the second scattering member 22b, and the first scattering member 21b is disposed between the second scattering member 22b and the second scattering member 22c. That is, two scattering members (second scattering member and first scattering member) having different scattering angles are alternately arranged. The second scattering members 22a, 22b, 22c, and 22d are installed between the first scattering members 21a, 21b, and 21c so that the major axis directions of the second scattering members 22a, 22b, 22c, and 22d are perpendicular to the major axis direction of the non-circular beam. The first scattering angle members 21a, 21b, and 21c are preferably smaller than the second scattering members 22a, 22b, 22c, and 22d so that the scattering angle can be ignored.
In this case, the role of the first scattering member is to support the second scattering member. Each of the first scattering members 21a, 21b, and 21c is made of the same material, for example, ABS or aluminum that is a kind of resin. The second scattering members 22a, 22b, 22c, and 22d are made of the same material, for example, tungsten.

  Also in the particle beam therapy system 101 of the present embodiment, a plurality of scatterers 14A are prepared. Each scatterer has a configuration in which the first scattering members and the second scattering members are alternately arranged. The width of the first scattering members 21a, 21b, and 21c in the short axis direction, the second scattering members 22a, 22b, and 22c. , 22d have different widths in the minor axis direction. For example, the adjustment is made so that the width and interval of the second scattering member are gradually reduced. Thus, the beam size that has passed through the scatterer 14A can be adjusted by adjusting the width and interval of the second scattering member. In addition, the intensity distribution of the charged particle beam can be adjusted. Further, the second scattering members 22a, 22b, 22c, and 22d may be made of materials having different scattering angles.

  According to the present embodiment, since the beam shape whose beam size ratio is greatly deviated from 1 can be made to be a circular shape, there is no need to adjust every gantry rotation angle, and the dose is independent of the gantry angle. The distribution uniformity can be easily formed.

  According to the present embodiment, by arranging a plurality of substances having different scattering angles, a charged particle beam having a non-circular beam shape can be made more circular.

  A particle beam therapy system according to another embodiment of the present invention will be described. The particle beam therapy system 102 according to the present embodiment has a configuration in which the scatterer 14 installed on the beam trajectory of the beam transport system 3 in the particle beam therapy system 100 according to the first embodiment is replaced with a scatterer 14B.

  The structure of the scatterer 14B of a present Example is demonstrated using FIG. The scatterer 14B is an anisotropic scatterer, and two kinds of substances having different scattering angles are arranged. The first scattering members 21a and 21b are made of a material having a small scattering angle, and the second scattering member 22 is made of a material having a large scattering angle. The scattering angle of the first scattering members 21 a and 21 b is smaller than the scattering angle of the second scattering member 22. The first scattering members 21a and 21b and the second scattering member 22 have shapes having different thicknesses in the minor axis direction. The support member 23 is made of a material having a small scattering angle. The first scattering members 21a and 21b are arranged on one surface of the support member 23, and the second scattering member 22 is arranged on the other surface. The second scattering member 22 is sandwiched between the first scattering member 21a and the first scattering member 21b. The thicknesses (shapes) of the first scattering members 21a and 21b and the second scattering member 22 are adjusted so that the range of the water equivalent thickness is the same, and the thicknesses continuously change. With such a configuration, the scattering angle continuously changes at the connection portion of the first scattering member 21a and the second scattering member 22 and the connection portion of the first scattering member 21b and the second scattering member 22, so that it becomes more circular. A beam with a close shape is obtained.

  A plurality of scatterers 14B are also prepared in the particle beam therapy system 102 of the present embodiment. Each scatterer has a configuration in which the first scattering member 21a, 21b is disposed on one surface of the support member 23 and the second scattering member 22 is disposed on the other surface, as described above. The width in the minor axis direction of 21a and 21b and the width in the minor axis direction of the second scattering member 22 are different. Thus, the beam size that has passed through the scatterer 14B can be adjusted by adjusting the width and interval of the second scattering member. In addition, the intensity distribution of the charged particle beam can be adjusted.

  According to the present embodiment, since the beam shape whose beam size ratio is greatly deviated from 1 can be made to be a circular shape, there is no need to adjust every gantry rotation angle, and the dose is independent of the gantry angle. The distribution uniformity can be easily formed.

  According to the present embodiment, since the scattering member is arranged so that the scattering angle continuously changes, a charged particle beam having a shape closer to a circle can be obtained.

  A particle beam therapy system according to another embodiment of the present invention will be described. The particle beam therapy system 103 according to the present embodiment has a configuration in which the scatterer 14 installed on the beam trajectory of the beam transport system 3 is replaced with a scatterer 14C in the particle beam therapy system 100 according to the first embodiment.

  The configuration of the scatterer 14C of the present embodiment will be described with reference to FIG. The scatterer 14C is an anisotropic scatterer, and a plurality of substances having different scattering angles are arranged. The scattering member constituting the scatterer 14 is made of a material having a small scattering angle in the order of the second scattering member, the third scattering member, the fourth scattering member, and the fifth scattering member. The second scattering member, the third scattering member, the fourth scattering member, and the fifth scattering member have shapes having different thicknesses in the minor axis direction. The support member 23 is made of a material having a small scattering angle. The third scattering members 27a and 27b and the fifth scattering members 29a and 29b are arranged on one surface of the support member 23, and the second scattering member 22 and the fourth scattering members 28a and 28b are arranged on the other surface. The second scattering member 22 is disposed between the fourth scattering member 28a and the fourth scattering member 28b. The third scattering members 27a and 27b are disposed between the fifth scattering member 29a and the fifth scattering member 29b. The second scattering member 22 is positioned so as to overlap with the third scattering members 27a and 27b. The fourth scattering member 28a is disposed so as to overlap the third scattering member 27a and the fifth scattering member 29a. The fourth scattering member 28b is disposed so as to overlap the third scattering member 27b and the fifth scattering member 29b. The second scattering member 22 located at the beam center of the charged particle beam is made of a material having a larger scattering angle than the other scattering members, and the scattering angle gradually becomes smaller as the scattering member is located at the end of the beam. It is comprised so that. That is, in the scatterer 14 </ b> C, a scattering member in which the second scattering member 2 located near the center of the support member 23 has the largest scattering angle and the scattering angle gradually decreases toward the end of the support member 23 is arranged. The thicknesses (shapes) of the second scattering member, the third scattering member, the fourth scattering member, and the fifth scattering member are adjusted so that the range of the water equivalent thickness is the same, and the thickness continuously changes. To do. With such a configuration, the beam shape of the charged particle beam that has passed through the scatterer 14C can be made closer to a circle.

  Also in the particle beam therapy system 103 of the present embodiment, a plurality of scatterers 14C are prepared. As described above, each of the scatterers has the third scattering members 27a and 27b and the fifth scattering members 29a and 29b arranged on one surface of the support member 23, and the second scattering member 22 and the fourth scattering member on the other surface. The members 28a and 28b are arranged, but the second scattering member 22, the third scattering members 27a and 27b, the fourth scattering members 28a and 28b, and the fifth scattering members 29a and 29b have different widths in the short axis direction. . Thus, the adjustment of the beam size that has passed through the scatterer 14C can be adjusted by adjusting the width and interval of the scattering member. In addition, the intensity distribution of the charged particle beam can be adjusted.

  According to the present embodiment, since the beam shape whose beam size ratio is greatly deviated from 1 can be made to be a circular shape, there is no need to adjust every gantry rotation angle, and the dose is independent of the gantry angle. The distribution uniformity can be easily formed.

  In Examples 1-4, although the synchrotron was shown as the circular accelerator 2, the same effect can be acquired also when a cyclotron is employ | adopted.

1 Pre-stage accelerator 2 Circular accelerator (synchrotron)
3 Beam transport system 4 Rotating gantry 5 Particle beam irradiation device 6 Control device 7 Patient 8 Patient support device 9 Accelerator / transport system control unit 10 Irradiation device control unit 11 Central control unit 12 Beam profile monitor 13 Scanning electromagnet 14 Scattering body 15 Scattering body Control unit 17 Dose monitor 18 Block collimator 19 Multi-leaf collimator 20 Isocenter 21 First scattering member (substance with a small scattering angle)
22 Second scattering member (substance with large scattering angle)
23 support member 24 scatterer driving device 25 treatment planning device 26 display device 27 third scattering member 28 fourth scattering member 29 fifth scattering member 30 high-frequency acceleration cavity 31 high-frequency applying device 32 outgoing deflectors 33, 36 quadrupole electromagnet 34, 37 Bending Electromagnet 35 Beam Path 100 Particle Beam Therapy System

Claims (11)

An accelerator to accelerate the charged particle beam;
A particle beam irradiation apparatus for irradiating a target region with the charged particle beam emitted from the accelerator;
A beam transport system connecting the accelerator and the particle beam irradiation device;
A scatterer having at least a second scattering member made of a substance having a scattering angle of the first scattering member and the charged particle beam larger than that of the first scattering member;
A scatterer control device that arranges the scatterer so that a long axis of the second scattering member crosses a region where the beam diameter of the charged particle beam passing through the beam transport system is short; A particle beam therapy system characterized by that. A central control unit for obtaining a beam shape of the charged particle beam before passing through the scatterer, and outputting a movement command signal related to an arrangement position and a rotation angle of the scatterer;
2. The particle beam therapy system according to claim 1, wherein the scatterer control device moves and rotates the scatterer based on a movement command signal from the central control device.   The particle beam irradiation system according to claim 1, wherein the particle beam irradiation apparatus includes a scanning electromagnet that scans the charged particle beam. The scatterer has a configuration in which the second scattering member is disposed between the plurality of first scattering members, and is equivalent to the water equivalent of the charged particle beam that has passed through the first scattering member and the second scattering member. It has a thickness that makes the same range,
The said scatterer control apparatus arrange | positions the said scatterer in the position where the said charged particle beam passes a said 1st scattering member and a 2nd scattering member, The Claim 1 thru | or 3 characterized by the above-mentioned. Particle beam therapy system.   In the scatterer, the width in the minor axis direction of the second scattering member is smaller than the length in the major axis direction of the beam diameter before passing through the scatterer, and the width in the major axis direction of the second scattering member. The particle beam therapy system according to claim 4, wherein the beam diameter is larger than the length in the minor axis direction of the beam diameter before passing through the scatterer. The scatterer includes a plurality of first scattering members and a plurality of second scattering members, and the first scattering member and the second scattering member are alternately arranged, and the first scattering member and the second scattering member The charged particle beam having passed through the second scattering member has a thickness such that the water equivalent range is the same;
The said scatterer control apparatus arrange | positions the said scatterer in the position where the said charged particle beam passes a said 1st scattering member and a 2nd scattering member, The Claim 1 thru | or 3 characterized by the above-mentioned. Particle beam therapy system.   The scatterer has a configuration in which a plurality of the second scattering members are provided around the center of the beam, and the width and interval of the second scattering member are gradually reduced from the beam center to the end. The particle beam therapy system according to claim 6. The scatterer includes a support member that supports the first scattering member and the second scattering member, the first scattering member is disposed on one surface of the support member, and the other surface of the support member The second support member is arranged so that a part of the first support member overlaps, and the water equivalent range of the charged particle beam that has passed through the first scattering member and the second scattering member is the same. Has a thickness such that
The said scatterer control apparatus arrange | positions the said scatterer in the position where the said charged particle beam passes a said 1st scattering member and a 2nd scattering member, The Claim 1 thru | or 3 characterized by the above-mentioned. Particle beam therapy system. An accelerator to accelerate the charged particle beam;
A particle beam irradiation apparatus for irradiating a target region with the charged particle beam emitted from the accelerator;
A beam transport system connecting the accelerator and the particle beam irradiation device;
A plurality of scattering members having different scattering angles of the charged particle beam, and a scattering member having a smaller scattering angle as the distance from the center of the beam increases;
The scatterer is arranged such that the long axis of the scattering member having the largest scattering angle crosses the region where the beam diameter of the charged particle beam passing through the beam transport system is short. A particle beam therapy system comprising a scatterer control device to be arranged.   The particle beam therapy according to claim 9, wherein the scatterer has a thickness such that water-equivalent ranges of the charged particle beams having passed through a plurality of scattering members having different scattering angles are the same. system. An accelerator for accelerating a charged particle beam, a particle beam irradiation device for irradiating a target region with the charged particle beam emitted from the accelerator, a beam transport system connecting the accelerator and the particle beam irradiation device, and a first scattering member And a scatterer having a second scattering member made of a material having a scattering angle of the charged particle beam larger than that of the first scattering member, and a scatterer control device that arranges the scatterer in a beam passage region of a beam transport system A particle beam irradiation method for a particle beam therapy system comprising:
The scatterer control device arranges the scatterer such that a long axis of the second scattering member crosses a region where the beam diameter of the charged particle beam is short,
Transporting the charged particle beam that has passed through the scatterer to the particle beam irradiation device;
A particle beam irradiation method for a particle beam therapy system, characterized in that the transported charged particle beam is deflected and emitted by a scanning electromagnet disposed in the particle beam irradiation apparatus.

Images