JP2010220647A - Particle beam therapy apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle beam therapy apparatus capable of suppressing the uniformity deterioration of SOBP (Spread Out Bragg Peak) caused by gantry rotation. <P>SOLUTION: An irradiation field forming apparatus 13 for irradiating an irradiation object with a charged particle beam emitted from a charged particle beam generator 2 is provided with an RMW (Range Modulation Wheel) apparatus 20. The RMW 21 of the RMW apparatus 20 is movable within a plane orthogonal to the advancing direction of the charged particle beam. When a gantry angle is changed and a beam incidence shape to the RMW 21 is changed, a table 25 is moved by a control mechanism within the plane orthogonal to the beam advancing direction, the beam incidence position of the RMW 21 is changed, and the beam incidence shape to the RMW 21 is not changed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a particle beam therapy apparatus, and more particularly, to a particle beam therapy apparatus suitable for treatment by irradiating an affected area (cancer lesion) with an ion beam (charged particle beam) such as protons or carbon ions.

  A conventional particle beam therapy system includes an ion beam generator, an ion beam transport system, and an irradiation field forming device. The irradiation field forming device is installed in the rotating gantry. The ion beam generator includes a synchrotron (or cyclotron) as an accelerator. The ion beam accelerated to the set energy by the synchrotron reaches the irradiation field forming device through the ion beam transport system. The ion beam is irradiated to the affected part of the patient's cancer from the irradiation field forming device.

  The irradiation field forming apparatus is an apparatus that shapes the ion beam from the ion beam generator in accordance with the three-dimensional shape of the affected part that is the irradiation target, forms an irradiation field, and adjusts the irradiation dose in the irradiation field. In general, since the affected area has a three-dimensional shape, the irradiation field forming apparatus uses an ion beam traveling plane (hereinafter simply referred to as “depth direction”) and a plane orthogonal to the beam traveling direction ( In the following, it is necessary to spread the beam uniformly within the following (referred to simply as “lateral direction”).

  A double scatterer method is known as a method of expanding the beam in the lateral direction (see, for example, FIG. 11 of Patent Document 1 and FIG. 39 of Non-Patent Document 1). The double scatterer method uses two types of scatterers, a first scatterer and a second scatterer, to obtain an ion beam with a uniform irradiation dose distribution in the lateral direction and expanded in that direction. is there. The irradiation field forming device to which the double scatterer method is applied has a first scatterer and a second scatterer, and the first scatterer is arranged upstream of the second scatterer. The ion beam is spread in a normal distribution by scattering in the first scatterer, and then a uniform irradiation dose distribution is formed in the lateral direction by scattering in the second scatterer. In this way, the ion beam having a uniform irradiation dose distribution passes through a collimator installed in the irradiation field forming apparatus and is irradiated to the affected part.

  In an irradiation field forming apparatus using the double scatterer method, a Bragg peak expanding apparatus (SOBP apparatus) is used to form a uniform irradiation dose distribution (SOBP: Spread Out Bragg Peak) in the depth direction. As the SOBP device, a device using a ridge filter (for example, refer to FIG. 31 of page 2078 and FIG. 41 of page 2084 of Non-Patent Document 1) and a device using a range modulation wheel (RMW) ([Information 1] For example, see page 30 of FIG.

  The RMW is rotatably installed on the ion beam path in the irradiation field forming apparatus. The RMW has a plurality of wings (blades) extending in the radial direction from the rotating shaft, and single portions of the wings are connected by a cylindrical member. The cylindrical member is concentric with the rotation axis. Each wing has a plurality of stepped steps in the circumferential direction. When the ion beam passes through the rotating RMW, it passes through the stepped portion of the blade and loses energy according to the thickness of the stepped portion. Since the wing has a plurality of steps having different thicknesses, the ion beam has various energy components after passing through the RMW, and when viewed in time integration, they are superimposed, resulting in the depth direction. A uniform irradiation dose distribution (SOBP) is formed.

  When creating a uniform dose distribution in the depth direction using the RMW, the width of the SOBP can be adjusted by applying a beam only to a specific step among the steps of the RMW. For example, when the RMW is rotated and the ion beam is applied, if the beam is not applied to some thick stages and the beam is applied only to the other stages among the plurality of stages constituting the RMW, all the stages are applied. The width of the SOBP is shorter than when the beam is applied. The former does not include a beam that has passed through a thicker stage than the latter, that is, a beam that loses energy and has a shorter range when passing through the RMW. Therefore, an energy component that contributes to the shallow side of the SOBP is not included in the beam having various energies that forms the SOBP compared to the latter. As a result, the SOBP width is shorter than when the beam is applied to all the stages of the RMW. The above control is realized by monitoring the rotation angle of the RMW and turning on / off the ion beam only in a specific angle range.

JP 2004-69683 A Review of Scientific Instruments Vol. 64 No. 8 (August 1993), 2074-2086 (REVIEW OF SCIENTIFIC INSTRUMENTS VOLUME 64 NUMBER 8 (AUGUST 1993) P2079-2083)

  Here, the irradiation field forming device installed in the rotating gantry can irradiate the patient with the beam at an arbitrary angle. When the gantry rotates, when viewed from the irradiation field forming device, the optical system of the beam transport system rotates according to the rotation of the gantry, and as a result, the shape of the beam incident on the irradiation field forming device depends on the gantry angle. Will rotate. When the beam incident shape to the irradiation field forming apparatus rotates according to the gantry rotation angle, the incident beam shape to the RMW also rotates according to the gantry rotation angle. When the shape of the beam incident on the RMW is elliptical, when the beam shape rotates according to the gantry angle, when the beam is incident on the RMW, the major axis direction of the beam shape substantially coincides with the radial direction of the RMW, and the major axis In some cases, the direction substantially coincides with the circumferential direction of the RMW. Since the beam size occupied in the circumferential direction of the RMW differs between the two, the range of the RMW stage to which the beam hits changes. Therefore, when controlling to adjust the SOBP width by turning on / off the beam, even if both are turned on / off at the same timing, the range of the stage where the beam hits when the beam is turned on or off is different. The uniformity of SOBP deteriorates depending on the gantry angle.

  As a method for solving the above problem, it is conceivable to make the beam shape before gantry incidence substantially symmetric with respect to the beam center axis. In this case, even if the gantry rotates, the shape that is substantially symmetrical with respect to the beam axis rotates, so the shape of the beam incident on the RMW does not change. However, it is difficult to make the beam shape circular before the gantry is incident due to limitations of the ion beam generator and the beam transport system. It is possible to install an optical system (for example, a combination of multiple quadrupole electromagnets) that rotates the beam in the opposite direction by the same angle as the gantry rotation angle before entering the gantry. It is difficult because of restrictions. Although a method of changing the ON / OFF timing of the beam in accordance with the gantry rotation angle is also conceivable, it is not realistic to make such adjustment for all gantry angles and all SOBP widths.

  If the diameter of the RMW is increased and the circumferential width of the steps constituting the RMW is sufficiently larger than the spatial size of the beam, the difference in the shape of the incident beam on the RMW does not become a big problem. However, in actual treatment, it is necessary to change the energy of the ion beam and the size of the irradiation field according to the position and shape of the affected part, and it is necessary to replace the RMW accordingly, so it is easy to carry and replace There is a high need for a compact RMW. RMW with a large diameter makes replacement difficult and reduces the throughput of the treatment.

  An object of the present invention is to provide a particle beam therapy system capable of suppressing deterioration in uniformity of SOBP due to gantry rotation.

(1) In order to achieve the above object, a charged particle beam generator for generating a charged particle beam and a charged particle beam irradiation device for irradiating the affected part with the charged particle beam emitted from the charged particle beam generator are provided. The charged particle beam irradiation device is a particle beam therapy device having a range modulation wheel rotating device including a rotatable range modulation wheel through which the charged particle beam passes, wherein the range modulation wheel is a charged particle beam traveling device. It can move in a plane perpendicular to the direction.
With this configuration, it is possible to suppress the deterioration of the uniformity of SOBP due to the gantry rotation.

  (2) In the above (1), preferably, the charged particle beam generator includes a rotating gantry that changes an irradiation angle of the charged particle beam to the affected part, and the charged particle beam irradiation device changes an angle of the rotating gantry. However, control means for changing the charged particle beam passing position of the range modulation wheel according to the angle of the rotating gantry is provided so that the beam incident shape to the range modulation wheel does not change.

  (3) In the above (2), preferably, the control means controls ON / OFF of a charged particle beam generated from the charged particle beam generator according to a rotational position of the range modulation wheel. Is.

  (4) In the above (3), preferably, when the distance between the rotation center of the range modulation wheel and the passing position of the charged particle beam is Y1, the control means changes the angle of the rotating gantry by θ. In this case, the range modulation wheel moves −Y1 · sin θ in the X-axis direction and −Y1-Y1 · cos θ in the Y-axis direction in an XY plane orthogonal to the traveling direction of the charged particle beam. Further, the position of the range modulation wheel is controlled.

  (5) In the above (4), preferably, the range modulation wheel rotation device includes a first drive source that rotationally drives the range modulation wheel, and a second drive source that moves the range modulation wheel. The control means controls the position of the range modulation wheel by controlling the second drive source.

  (6) In the above (5), preferably, the second drive source drives the range modulation wheel in the X-axis direction within an XY plane orthogonal to the charged particle beam traveling direction. 1 motor and a second motor driven in the Y-axis direction.

  (7) In the above (5), preferably, the second drive source has the range modulation wheel centered on a charged particle beam passage position in an XY plane orthogonal to the charged particle beam traveling direction. Thus, the motor is configured to rotate.

  (8) In the above (3), preferably, the range modulation wheel extends in a radial direction from the center of rotation and is arranged stepwise in the circumferential direction, and includes a plurality of planar regions having different thicknesses of passage of the charged particle beam. The charged particle beam has an elliptical cross-sectional shape in a portion passing through the planar region of the range modulation wheel, and the control means is configured to change the angle of the rotating gantry even when the angle of the rotating gantry is changed. The charged particle beam passing position of the range modulation wheel is changed so that the positional relationship between the major axis direction of the beam and the radial direction of the range modulation wheel does not change.

  According to the present invention, deterioration in uniformity of SOBP due to gantry rotation can be suppressed.

Hereinafter, 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.
Initially, the whole structure of the particle beam therapy apparatus by this embodiment is demonstrated using FIG.
FIG. 1 is a system configuration diagram showing the overall configuration of the particle beam therapy system according to the first embodiment of the present invention.

  The particle beam therapy system 1 of this embodiment includes a charged particle beam generator 2 and an irradiation field forming device (charged particle beam irradiation device) 13 which is a charged particle beam irradiation device. The charged particle beam generator 2 includes an ion source (not shown), a pre-accelerator 3 and a synchrotron 4. Ions (for example, protons or carbon ions) generated in the ion source are accelerated by a front stage accelerator (for example, a linear accelerator) 3. The ion beam (charged particle beam) emitted from the front stage accelerator 3 is incident on the synchrotron 4. This ion beam is accelerated by the synchrotron 4 by being given energy by the high frequency power applied from the high frequency acceleration cavity 5. After the energy of the ion beam that circulates in the synchrotron 4 is increased to the set energy, a high frequency is applied from the high frequency application device 6 for extraction to the ion beam that circulates. The ion beam orbiting within the stability limit moves outside the stability limit by the application of this high frequency, and is emitted from the synchrotron 4 through the extraction deflector 7. When the ion beam is emitted, the current guided to the electromagnets such as the quadrupole electromagnet 8 and the deflection electromagnet 9 provided in the synchrotron 4 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 6, the extraction of the ion beam from the synchrotron 4 is stopped.

  The ion beam emitted from the synchrotron 4 reaches the irradiation field forming device 13 through the ion beam transport system 10. The inverted U-shaped part 11 and the irradiation field forming device 13 which are a part of the ion beam transport system 10 are installed in a rotatable rotating gantry 17. Irradiation is performed on the affected area of the patient 15 on the treatment table (bed) 14 from the irradiation field forming device 13.

  The treatment planning apparatus 100 formulates a treatment plan based on the position and size of the affected area. The treatment plan includes information such as the ion beam irradiation direction and dose. Information on the treatment plan is sent to the irradiation control device 110. The irradiation control device 110 controls each part of the particle beam therapy device 110 based on the treatment plan. Specifically, based on the information on the ion beam irradiation direction, the irradiation control device 110 uses the rotation drive device 120 to rotate the rotating gantry 17 to change the ion beam irradiation direction. The rotation angle of the rotating gantry 17 is, for example, 0 degrees to 360 degrees [information 2]. Further, the irradiation control device 110 controls on / off of the output deflector 7 based on the information of the irradiation amount.

  Further, in the present embodiment, the irradiation control device 110 controls the rotation angle of the rotating gantry 17 and the position where the ion beam of the RMW device (range modulation wheel rotating device) inside the irradiation field forming device 13 hits. [Detail 3] The detailed configuration of the RMW device (range modulation wheel rotating device) will be described later with reference to FIG. Further, the irradiation control device 110 controls on / off of the output deflector 7 in synchronization with the rotation angle of the RMW device (range modulation wheel rotation device).

Next, the configuration of the irradiation field forming apparatus 13 used in the particle beam therapy apparatus 1 according to the present embodiment will be described with reference to FIG.
FIG. 2 is a longitudinal sectional view showing a configuration of an irradiation field forming apparatus used in the particle beam therapy system according to the first embodiment of the present invention.

  The irradiation field forming device 13 has a casing 16 attached to the rotating gantry. In the casing 16, the first scatterer device 18, the RMW device (range modulation wheel rotating device) 20, and the second scatterer device 41 are arranged upstream from the irradiation field forming device 13 in the axial direction Z (ion beam traveling direction). A range adjusting device (for example, a range shifter) 45, a block collimator (first collimator) 50, a bolus 56, and a patient collimator (second collimator) 57 are sequentially arranged.

  The first scatterer 18 is a device that spreads the ion beam in a direction orthogonal to the ion beam traveling direction, and is installed in the casing 16 by a support member 19. The first scatterer 18 is generally made of a material having a high atomic number, such as lead or tungsten, which has a high ability to scatter an ion beam. The first scatterer 18 is disposed in the beam passage path 17 of the irradiation field forming device 13.

  The second scatterer device 41 is for making the ion beam spread in a substantially normal distribution in a direction orthogonal to the beam traveling direction by the first scatterer 18 into a uniform distribution in that direction. The second scatterer 41 is installed on a second scatterer table 42 fixed to the casing 16, and is arranged in the beam passage path 17 of the irradiation field forming device 13.

  The range adjusting device 45 has a function of adjusting the range of the ion beam in the patient undergoing treatment, and has a function of inserting and discharging a plurality of absorbers into the beam line. The block collimator 50 and the patient collimator 57 have a role of collimating unnecessary ion beams in the lateral direction, and the bolus 56 has a function of adjusting the range of the ion beam so as to match the shape of the affected area of the patient.

  The RMW device (range modulation wheel rotating device) 20 includes an RMW 21, a ball screw 22, a timing belt 23, a motor 24, a table 25, a table 26, a ball screw 27, and a rotating shaft 29. The detailed configuration thereof is shown in FIG. Will be described later.

Next, the configuration of the RMW device 20 used in the irradiation field forming device 13 of the particle beam therapy system 1 according to the present embodiment will be described with reference to FIGS.
FIG. 3 is a perspective view showing the configuration of the RMW of the RMW device used in the irradiation field forming device of the particle beam therapy system according to the first embodiment of the present invention. 4 and 5 are plan views showing the configuration of the RMW device used in the irradiation field forming device of the particle beam therapy system according to the first embodiment of the present invention. FIG. 4 shows the first position state, and FIG. 5 shows the second position state. FIG. 6 is an operation explanatory diagram of the RMW device used in the irradiation field forming device of the particle beam therapy system according to the first embodiment of the present invention.

  The RMW device 20 illustrated in FIG. 2 includes an RMW (range modulation wheel) 21.

  As shown in FIG. 3, the RMW 21 has a structure in which the rotation shaft 29 and the cylindrical member 30 are arranged concentrically. A plurality (three in this embodiment) of blades 31 attached to the rotating shaft 29 extend in the radial direction of the RMW 21. The outer end portions of these blades 31 are attached to the cylindrical member 30. The width of the blade 31 in the circumferential direction is wider at the end on the cylindrical member 30 side than at the end on the rotating shaft 29 side. Openings 32 (three places in the present embodiment) are formed between the blades 31 in the circumferential direction of the RMW 21. These openings 32 are wider in the circumferential direction at the end on the cylindrical member 30 side than on the end on the rotating shaft 29 side. Each blade 31 has a plurality of planar regions 33 (four steps of 33A, 33B, 33C, and 33D in this embodiment) arranged stepwise in the circumferential direction of the RMW 21, and in the direction of the ion beam axis Z. The thicknesses from the bottom surface of the RMW 21 to the planar regions 33 are different (the levels from the bottom surface of the RMW 21 to the planar regions 33 are different). The thickness of one plane region 33 is referred to as the thickness of the plane region portion. That is, in the blade 31, the thickness of each planar region portion increases from the opening 32 positioned on both sides of the blade 31 in the circumferential direction toward the blade top portion 33 </ b> A having the thickest thickness in the ion beam axis Z direction. The plane area 33 corresponds to a plane on which a foot is placed on a staircase, for example. Each planar region 33 extends from the rotation shaft 29 toward the cylindrical member 30. The width of each planar region 33 in the circumferential direction of the RMW 21 is also wider at the end on the cylindrical member 30 side than the end on the rotating shaft 29 side. In one RMW 21, there are three openings 32 positioned between the three blades 31. By rotating the RMW 21 during the irradiation of the ion beam, the ion beam loses energy according to the steps that pass through the RMW 21, and as a result, the ion beam has various energy components in the affected area, and these are temporally related. And a uniform dose distribution (SOBP) is formed in the depth direction.

  Next, the detailed configuration of the RMW device 20 will be described with reference to FIG. FIG. 4 shows the first position state.

  The RMW 21 is rotated during the ion beam irradiation in the direction of the arrow R1 by the rotating shaft 29, the timing belt 23, and the motor 24. The RMW 21, the rotating shaft 29, the timing belt 23, and the motor 24 are installed on the table 25. The table 25 has a structure that can be moved in the Y direction by a ball screw 22 rotated by a motor M1. The ball screw 22 is installed on a table 26, and the table 26 is structured to be movable in the X direction by a ball screw 27 rotated by a motor M2. The ball screw 27 is fixed to the casing 16 of the irradiation field forming device 13. With this structure, the RMW 21 can move in a plane (XY plane) orthogonal to the beam traveling direction, and the beam passing position 35A of the RMW 21 can be changed.

  Here, as shown in FIG. 4, it is assumed that the beam shape 35 when the ion beam is irradiated at a certain gantry angle has a shape in which the vertical direction is larger than the horizontal direction on the XY plane. In this case, the major axis direction of the beam shape 35 substantially coincides with the radial direction of the RMW 21. Here, as shown in FIGS. 6A and 6B, irradiation is performed to irradiate the beam to the opening 32 and the step 33D of the RMW 21, and turn off the beam at the step 33C, the step 33B, and the step 33A.

  At this time, the beam ON / OFF signal shown in FIG. 6B is generated by the irradiation controller 110 and sent to the deflector 7 of the charged particle beam generator 2. The charged particle beam generator 2 generates an ion beam at the beam ON timing of the beam ON / OFF signal 80 and does not generate an ion beam at the beam OFF timing. At the same time, the RMW device 20 has an interlock (not shown) that detects the rotation angle of the RMW 21 and checks whether the rotation position of the RMW 21 is synchronized with the beam ON / OFF signal. The motor 24 includes a rotation angle detection device (for example, a resolver) that detects a rotation angle. A beam shape 82 shown in FIG. 6C shows a beam shape when a beam incident on the RMW 21 is sampled at a certain time interval. The beam shape 81 shows the time integration of the beam shape 82.

  Next, the same irradiation is performed by changing the gantry angle. When the gantry is rotated, the beam incident shape to the gantry as viewed from the irradiation field forming device is rotated. Therefore, when the gantry is rotated 120 degrees, the beam shape incident on the RMW 21 is 120 degrees as shown by the beam 36 in FIG. Rotate. At this time, the major axis direction of the beam shape 36 does not match the radial direction of the RMW 21, and the beam size occupied in the circumferential direction of the RMW 21 is larger than that of the beam shape 35.

  Here, the beam shape 86 shown in FIG. 6D shows the beam shape when the beam incident on the RMW 21 is sampled at a certain time interval. The beam shape 85 shows the time integration of the beam shape 86. Compared with the beam shape 86, the beam shape 85 irradiates the beam to a wider step range of the RMW 21. Therefore, the uniformity of the SOBP generated by the beam shape 85 is worse than that of the SOBP generated by the beam shape 81.

  Therefore, in this embodiment, when the gantry angle is changed, as shown in FIG. 5, the table 26 and the table 27 are moved, the major axis direction of the beam shape 36 is matched with the radial direction of the RMW, and the circumferential direction of the RMW 21 The beam size occupied by is matched with that before the gantry rotation. By moving the table, the shape of the beam incident on the RMW 21 becomes the same as that before the gantry rotation, so the uniformity of the obtained SOBP does not deteriorate.

  The positions of the table 26 and the table 27 are determined in advance according to the gantry angle, and are controlled by the irradiation control device 110 to move according to the gantry angle. For example, the state shown in FIG. 4 is a state where the gantry angle is 0 degree. At this time, the beam passing position 35A of the RMW 21 in the (XY plane) is set to (0, 0). When the distance between the beam passing position 35A and the rotation center of the RMW 21 is Y1, the position of the rotation center of the RMW 21 is (0, −Y1).

  On the other hand, even when the gantry angle is changed by θ (120 degrees in the example of FIG. 5), the beam passage position 35A does not change from (0, 0). At that time, the position (X2, Y2) of the rotation center of the RMW 21 is (−Y1 · sin θ, −Y1 · cos θ). That is, when the gantry angle is changed by θ, the movement amounts of the table 26 and the table 27 are (0−Y1 · sin θ, −Y1−Y1 · cos θ).

  The major axis direction of the beam shape 36 can be aligned with the radial direction of the RMW also at the position 35B that is point-symmetric from the beam passage position 35A with respect to the rotation center position (X2, Y2) of the RMW 21. That is, when the gantry angle is changed by 120 degrees, the beam shape 36 can be changed even when the gantry angle is virtually changed by 300 degrees (120 degrees +180 degrees) (or when the gantry angle is changed by -60 degrees). The major axis direction can be matched with the radial direction of the RMW. In this case, the position (X2, Y2) of the rotation center of the RMW 21 when the gantry angle is changed by θ is (−Y1 · sin (θ + 180), −Y1 · cos (θ + 180)). The amount of movement is (0−Y1 · sin (θ + 180), −Y1−Y1 · cos (θ + 180)). In this example, the amount of movement in the Y direction can be halved compared to the case where the beam passing position 35A is set, but the amount of movement in the X direction is doubled. The gantry angle is 0 degree to 360 degrees [jo 4]. In the case of changing, the position of the RMW 21 can be moved on the assumption that it changes in a range of −90 degrees to 90 degrees.

  As described above, according to the present embodiment, the beam passing position of the RMW 21 can be arbitrarily changed even if the beam incident shape on the RMW 21 changes according to the gantry angle. The shape of the incident beam on the RMW 21 can be made constant, and deterioration of the uniformity of SOBP due to the gantry angle can be suppressed. Therefore, the quality of treatment can be improved.

  Next, the configuration and operation of the particle beam therapy system according to the second embodiment of the present invention will be described with reference to FIG. The overall configuration of the particle beam therapy system according to this embodiment is the same as that shown in FIG. The configuration of the irradiation field forming apparatus used in the particle beam therapy system according to the present embodiment is the same as that shown in FIG.

  FIG. 7 is a perspective view showing the configuration of the RMW of the RMW device used in the irradiation field forming device of the particle beam therapy system according to the second embodiment of the present invention.

  The particle beam therapy system of this embodiment differs from the particle beam therapy system 1 shown in FIGS. 1 and 2 in the configuration of the RMW device.

  The RMW 21A is mounted on the table 25 that can be rotated about the beam center 35A by the driven gear 37 and the driving gear 38. The driven gear 37 and the driving gear 38 are installed on a gantry 39, and the gantry 39 is installed on the casing 16. By rotating the table 25 in the direction of the arrow R2 by the motor M3 via the gears 37 and 38 according to the rotation of the gantry, it becomes possible to keep the beam incident shape on the RMW 21 constant regardless of the gantry angle. .

As described above, according to the present embodiment, the beam passing position of the RMW 21A can be arbitrarily changed even if the beam incident shape on the RMW 21 is changed according to the gantry angle. The shape of the incident beam on the RMW 21A can be made constant, and deterioration of the uniformity of SOBP due to the gantry angle can be suppressed. Therefore, the quality of treatment can be improved.

1 is a system configuration diagram showing the overall configuration of a particle beam therapy system according to a first embodiment of the present invention. 1 is a longitudinal sectional view showing a configuration of an irradiation field forming device used in a particle beam therapy system according to a first embodiment of the present invention. It is a perspective view which shows the structure of RMW of the RMW apparatus used for the irradiation field forming apparatus of the particle beam therapy system according to the first embodiment of the present invention. 1 is a plan view showing a configuration of an RMW device used in an irradiation field forming device of a particle beam therapy system according to a first embodiment of the present invention. 1 is a plan view showing a configuration of an RMW device used in an irradiation field forming device of a particle beam therapy system according to a first embodiment of the present invention. FIG. 6 is an operation explanatory diagram of the RMW device used in the irradiation field forming device of the particle beam therapy system according to the first embodiment of the present invention. It is a perspective view which shows the structure of RMW of the RMW apparatus used for the irradiation field formation apparatus of the particle beam therapy apparatus by the 2nd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 ... Particle beam therapy apparatus 2 ... Charged particle beam generator 3 ... Pre-stage accelerator 4 ... Synchrotron 5 ... High frequency acceleration cavity 6 ... High frequency application apparatus 7 ... Deflector 8 for extraction ... Quadrupole electromagnet 9 ... Deflection electromagnet 10 ... Ion beam transport system DESCRIPTION OF SYMBOLS 11 ... Reverse U-shaped part 13 ... Irradiation field forming apparatus 14 ... Treatment table 15 ... Patient 16 ... Casing 17 ... Beam path 18 ... First scatterer 19 ... First scatterer support member 20 ... RMW apparatus, 21 ... RMW
22, 27 ... Ball screw 23 ... Timing belt 24, M1, M2, M3 ... Motor 25, 26 ... Table 29 ... Rotating shaft 30 ... Cylindrical member 31 ... Blade 32 ... Openings 33A, 33B, 33C, 33D ... RMW stage 35 Beam shape 35A Beam passing position 36 Beam shape 37 Driven gear 38 Drive gear 39 Stand 41 Second scatterer 42 Second scatterer table 45 Range adjustment device 50 First block collimator 56 ... patient bolus 57 ... patient collimator 59 ... affected part 100 ... treatment planning device 110 ... irradiation control device 120 ... rotation drive device

Claims (8)

A charged particle beam generator for generating a charged particle beam;
A charged particle beam irradiation apparatus that irradiates an affected area with a charged particle beam emitted from the charged particle beam generator;
The charged particle beam irradiation apparatus is a particle beam therapy apparatus having a range modulation wheel rotating device including a rotatable range modulation wheel through which the charged particle beam passes,
The range modulation wheel is capable of moving in a plane perpendicular to the traveling direction of the charged particle beam. The particle beam therapy system according to claim 1, wherein
The charged particle beam generator comprises a rotating gantry that changes the irradiation angle of the charged particle beam to the affected area,
The charged particle beam irradiation device sets the charged particle beam passing position of the range modulation wheel to the angle of the rotating gantry so that the beam incident shape to the range modulation wheel does not change even if the angle of the rotating gantry changes. A particle beam therapy system comprising control means for changing in response. The particle beam therapy system according to claim 2, wherein
The particle beam therapy apparatus characterized in that the control means controls ON / OFF of a charged particle beam generated from the charged particle beam generator according to a rotational position of the range modulation wheel. The particle beam therapy system according to claim 3, wherein
When the distance between the rotation center of the range modulation wheel and the passing position of the charged particle beam is Y1, the control means moves the range modulation wheel to the charged particle beam when the angle of the rotating gantry changes θ. Control the position of the range modulation wheel so that it moves -Y1 · sin θ in the X-axis direction and -Y1-Y1 · cos θ in the Y-axis direction within an XY plane orthogonal to the traveling direction. A particle beam therapy system. The particle beam therapy system according to claim 4, wherein
The range modulation wheel rotating device includes a first drive source that rotationally drives the range modulation wheel;
A second drive source for moving the range modulation wheel,
The particle beam therapy apparatus, wherein the control means controls the second drive source to control the position of the range modulation wheel. The particle beam therapy system according to claim 5, wherein
The second driving source includes a first motor that drives the range modulation wheel in the X-axis direction and a first motor that drives the Y-axis direction in an XY plane orthogonal to the charged particle beam traveling direction. A particle beam therapy system comprising two motors. The particle beam therapy system according to claim 5, wherein
The second drive source includes a motor that rotates the range modulation wheel about a charged particle beam passing position in an XY plane orthogonal to the charged particle beam traveling direction. A particle beam therapy system. The particle beam therapy system according to claim 3, wherein
The range modulation wheel includes a plurality of planar regions that extend in the radial direction from the rotation center and are arranged stepwise in the circumferential direction, and the charged particle beam passage thicknesses are different from each other.
The charged particle beam has an elliptical cross-sectional shape in a portion passing through the planar region of the range modulation wheel,
The control means passes the charged particle beam through the range modulation wheel so that the positional relationship between the major axis direction of the charged particle beam and the radial direction of the range modulation wheel does not change even when the angle of the rotating gantry is changed. A particle beam therapy system characterized by changing a position.

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