Charged particle beam irradiation system

Abstract

A charged particle beam irradiation system capable of appropriately irradiating a charged particle beam to an irradiated body is provided. By adjusting penumbra of a charged particle beam (B) with a snorkel degrader (30), it is possible to suppress irradiation of the charged particle beam (B) to the outside of a tumor (14) when irradiation is performed to the vicinity of a boundary portion of the tumor (14) in an irradiation portion (2). Here, a holding portion (60) that holds the snorkel degrader (30) is provided to the irradiation portion (2). Therefore, it is possible to easily perform alignment between the charged particle beam (B) that is irradiated to the tumor (14) and the snorkel degrader (30). Therefore, in a state where the penumbra is adjusted at an appropriate position with the snorkel degrader (30), the irradiation portion (2) is capable of irradiating the charged particle beam (B) to the tumor (14). In the present embodiment, since it is only necessary to hold the snorkel degrader (30) to the holding portion (60), it is easy to perform alignment.

Description

TECHNICAL FIELD

[0001] This application claims priority based on Japanese Patent Application No. 2021-033429 filed on March 3, 2021. The entire contents of the Japanese application are incorporated herein by reference.

[0002] The present application relates to a charged particle beam irradiation system. BACKGROUND

[0003] In the past, as a charged particle beam irradiation system that performs treatment by irradiating a charged particle beam to a patient's affected part, for example, the device described in Patent Literature 1 is known. In the charged particle beam irradiation system described in Patent Literature 1, the irradiation section irradiates a charged particle beam by a scanning method. That is, the irradiation section irradiates while moving the irradiation position of the charged particle beam to the affected part by scanning with a scanning electromagnet.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2017-209372

[0005] Here, there is a problem that in the case where the irradiation section irradiates a charged particle beam by a scanning method, a treatment dose is applied to the outside of the irradiated body due to the large beam size of the charged particle beam or the like. Therefore, it is required to appropriately irradiate a charged particle beam to the irradiated body. SUMMARY

[0006] Therefore, an object of the present application is to provide a charged particle beam irradiation system that can appropriately irradiate a charged particle beam to an irradiated body.

[0007] To solve the above problem, the charged particle beam irradiation system according to the present application that irradiates an irradiated body in an object with a charged particle beam includes: an irradiation section that irradiates the irradiated body with the charged particle beam by scanning the charged particle beam with a scanning electromagnet; an adjustment member that adjusts a penumbra of the scanned charged particle beam; and a holding section that is provided to the irradiation section and holds the adjustment member.

[0008] The charged particle beam irradiation system according to the present application includes: an irradiation section that irradiates an irradiated body with a charged particle beam by scanning the charged particle beam with a scanning electromagnet; and an adjustment member that adjusts a penumbra of the charged particle beam. Therefore, by adjusting the penumbra of the charged particle beam with the adjustment member, it is possible to suppress the irradiation of the charged particle beam to the outside of the irradiated body when the irradiation section irradiates near the boundary of the irradiated body. Here, the holding section that holds the adjustment member is provided to the irradiation section. Therefore, in a state where the penumbra is adjusted at an appropriate position with the adjustment member, the irradiation section can irradiate the charged particle beam to the irradiated body. According to the above, the irradiation section can appropriately irradiate the charged particle beam to the irradiated body.

[0009] The holding portion can be provided at a front end portion of the irradiation portion. At this time, the adjustment member can adjust the penumbra at a position close to the object. Therefore, the charged particle beam is rapidly irradiated to the irradiated body before the spread of the beam is enlarged after the adjustment member adjusts the penumbra.

[0010] The adjustment member can have an adjustment level of the penumbra corresponding to a depth of the irradiated body in the object. At this time, the adjustment member can adjust the penumbra at the adjustment level of the penumbra corresponding to the depth of the irradiated body in the object.

[0011] The charged particle beam irradiation system can be configured to be able to select an adjustment level of the penumbra of the adjustment member according to a depth of the irradiated body in the object. At this time, the adjustment member can adjust the penumbra at an appropriate adjustment level of the penumbra according to the depth of the irradiated body in the object.

[0012] The charged particle beam irradiation system can be configured to be able to select an adjustment level of the penumbra of the adjustment member according to a distance of the object from the irradiation portion. At this time, the adjustment member can adjust the penumbra at an appropriate adjustment level of the penumbra according to the distance of the object from the irradiation portion.

[0013] The charged particle beam irradiation system can further have a detection portion that detects an adjustment member that is incorrectly arranged to the holding portion. At this time, adjustment of the penumbra by an adjustment member with an inappropriate adjustment level can be suppressed.

[0014] Effects of Invention

[0015] According to the present application, a charged particle beam irradiation system that can appropriately irradiate a charged particle beam to an irradiated body can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic configuration view of a charged particle beam irradiation system according to an embodiment of the present application.

[0017] Figure 2 is a schematic configuration view of a charged particle beam irradiation system according to an embodiment of the present application. Figure 1

[0018] Figure 3 is a view showing a layer set to a tumor.

[0019] Figure 4 is a schematic view showing a state in which a snout degrader is held by a holding portion.

[0020] Figure 5 is a graph showing a dose distribution when a charged particle beam is irradiated in a prescribed plane that is orthogonal to a base axis by a scanning method.

[0021] Figure 6 ​is a graph showing the results of simulation tests related to the relationship between the spread of the charged particle beam and the depth of the object.

[0022] Figure 7 is a graph showing the results of simulation tests related to the relationship between the spread of the charged particle beam and the depth of the object. Figure 6 is a graph showing the results of simulation tests related to the relationship between the spread of the charged particle beam and the depth of the object.

[0023] Figure 8 is a graph showing the results of simulation tests related to the relationship between the spread of the charged particle beam and the depth of the object. Figure 6 is a graph showing the results of simulation tests related to the relationship between the spread of the charged particle beam and the depth of the object.

[0024] Figure 9 is a block diagram showing the configuration for adjusting the level of the penumbra of the air layer.

[0025] Figure 10 is a process diagram showing the contents of the charged particle beam irradiation method according to an embodiment of the present application.

[0026] In the figure: 1 - charged particle beam irradiation system, 2 - irradiation section, 14 - tumor (irradiated body), 15 - patient (object), 30 - air layer (adjustment member), 50 - scanning electromagnet, 60 - holding section, 80 - detection section. DETAILED DESCRIPTION

[0027] Hereinafter, a charged particle beam irradiation system according to an embodiment of the present application will be described with reference to the drawings. In addition, in the description of the drawings, the same reference signs are assigned to the same elements, and repeated description will be omitted.

[0028] Figure 1 is a schematic configuration diagram of a charged particle beam irradiation system 1 according to an embodiment of the present application. The charged particle beam irradiation system 1 is a system for cancer treatment or the like based on radiation therapy. The charged particle beam irradiation system 1 includes an accelerator 3 that accelerates charged particles generated by an ion source device to be emitted as a charged particle beam, an irradiation section 2 that irradiates a charged particle beam to an irradiated body, and a beam transport line 21 that transports the charged particle beam emitted from the accelerator 3 to the irradiation section 2. The irradiation section 2 is installed to a rotating support 5 provided in a manner of surrounding a treatment table 4. The irradiation section 2 is rotatable around the treatment table 4 by the rotating support 5. Further, further detailed structures of the accelerator 3, the irradiation section 2, and the beam transport line 21 will be described later.

[0029] Figure 2 is Figure 1Fig. 1 is a schematic configuration diagram of the vicinity of an irradiation unit 2 of a charged particle beam irradiation system 1 according to the present embodiment. In the following description, the terms "X-axis direction", "Y-axis direction", and "Z-axis direction" are used. The "Z-axis direction" is the direction in which the base axis AX of the charged particle beam B extends, and is the depth direction of the irradiation of the charged particle beam B. In addition, the "base axis AX" is set as the irradiation axis of the charged particle beam B when not deflected by the later-described scanning electromagnet 50. In Figure 2 Fig. 1, a state in which the charged particle beam B is irradiated along the base axis AX is shown. The "X-axis direction" is one direction in a plane orthogonal to the Z-axis direction. The "Y-axis direction" is a direction orthogonal to the X-axis direction in a plane orthogonal to the Z-axis direction.

[0030] First, the schematic configuration of the charged particle beam irradiation system 1 according to the present embodiment will be described with reference to Figure 2 Fig. 1. The charged particle beam irradiation system 1 is an irradiation device related to a scanning method. In addition, the scanning method is not particularly limited, and line scanning, raster scanning, point scanning, or the like can be employed. As shown in Figure 2 Fig. 1, the charged particle beam irradiation system 1 includes an accelerator 3, the irradiation unit 2, a beam transport line 21, a control unit 7, a treatment planning device 90, and a storage unit 95.

[0031] The accelerator 3 is a device that accelerates charged particles and emits a charged particle beam B of a predetermined energy. As the accelerator 3, for example, a cyclotron, a synchrotron, a linear accelerator, or the like can be given. In addition, in the case where a cyclotron that emits a charged particle beam B of a predetermined energy is employed as the accelerator 3, by employing an energy adjusting unit, the energy of the charged particle beam transmitted to the irradiation unit 2 can be adjusted (reduced). The accelerator 3 is connected to the control unit 7, and the supplied current can be controlled. The charged particle beam B generated by the accelerator 3 is transmitted to the irradiation unit 2 through the beam transport line 21. The beam transport line 21 connects the accelerator 3 and the irradiation unit 2, and transmits the charged particle beam emitted from the accelerator 3 to the irradiation unit 2.

[0032] The beam transport line 21 has an energy adjustment device (ESS: Energy Selection System) that adjusts the energy of the charged particle beam B while transporting it. Among them, the beam transport line 21 has an energy degrader 20 near the exit of the accelerator 3. The energy degrader 20 is a means that adjusts the range of the charged particle beam B and adjusts the depth of arrival of the charged particle beam B in the body of the patient 15 (object). The energy degrader 20 adjusts the range by losing the energy of the charged particle beam B. The energy degrader 20 can adjust the range of the charged particle beam B by adjusting the thickness of the portion through which the charged particle beam B passes. In addition, the ESS suppresses energy fluctuations or beam size amplification (use of a collimator) generated in the beam transport line downstream of the ESS in addition to the energy loss in the energy degrader 20. The energy degrader 20 is, for example, composed of a material such as beryllium, carbon, or the like. The energy degrader 20 is disposed at a position on the upstream side (i.e., the accelerator 3 side) in the direction of travel of the charged particle beam B in the beam transport line 21. In the example shown, the energy degrader 20 is disposed immediately behind the accelerator 3 in the path on the more upstream side than the rotating stand 5, that is, at the most upstream side among the electromagnets and the like devices of the beam transport line 21. However, the position of the energy degrader 20 within the beam transport line 21 is not particularly limited. Figure 1

[0033] The irradiation section 2 irradiates the tumor (irradiated body) 14 in the body of the patient 15 (object) with the charged particle beam B. The charged particle beam B refers to a particle beam of a charged particle accelerated at high speed, and examples include a proton beam, a heavy particle (heavy ion) beam, an electron beam, and the like. Specifically, the irradiation section 2 is a device that irradiates the tumor 14 with the charged particle beam B emitted from the accelerator 3 that accelerates charged particles generated by an ion source (not shown) and transported through the beam transport line 21. The irradiation section 2 has a scanning electromagnet 50, a quadrupole electromagnet 8, a profile monitor 11, a dose monitor 12, position monitors 13a, 13b, a collimator 40, and a snorkel degrader 30 (adjusting means). The scanning electromagnet 50, each monitor 11, 12, 13a, 13b, the quadrupole electromagnet 8, and the snorkel degrader 30 are housed in the irradiation nozzle 9 as a housing body. In this way, the irradiation section 2 is configured by housing each main component in the irradiation nozzle 9. In addition, the quadrupole electromagnet 8, the profile monitor 11, the dose monitor 12, and the position monitors 13a, 13b can be omitted.

[0034] ​As the scanning electromagnet 50, an X-axis direction scanning electromagnet 50A and a Y-axis direction scanning electromagnet 50B are used. The X-axis direction scanning electromagnet 50A and the Y-axis direction scanning electromagnet 50B are each composed of a pair of electromagnets, and change the magnetic field between the pair of electromagnets according to the current supplied from the control section 7, to scan the charged particle beam B passing between the electromagnets. The X-axis direction scanning electromagnet 50A scans the charged particle beam B in the X-axis direction, and the Y-axis direction scanning electromagnet 50B scans the charged particle beam B in the Y-axis direction. These scanning electromagnets 50 are arranged in order on the base axis AX and are located more on the downstream side of the charged particle beam B than the accelerator 3. Further, the scanning electromagnets 50 scan the charged particle beam B so as to irradiate the charged particle beam B in a scanning pattern planned in advance by the treatment planning device 90. How to control the scanning electromagnets 50 is described later.

[0035] The quadrupole electromagnet 8 includes an X-axis direction quadrupole electromagnet 8a and a Y-axis direction quadrupole electromagnet 8b. The X-axis direction quadrupole electromagnet 8a and the Y-axis direction quadrupole electromagnet 8b reduce and converge the charged particle beam B according to the current supplied from the control section 7. The X-axis direction quadrupole electromagnet 8a converges the charged particle beam B in the X-axis direction, and the Y-axis direction quadrupole electromagnet 8b converges the charged particle beam B in the Y-axis direction. By changing the current supplied to the quadrupole electromagnet 8, the reduction amount (convergence amount) can be changed, and the beam size of the charged particle beam B can be changed. The quadrupole electromagnet 8 is arranged in order on the base axis AX and between the accelerator 3 and the scanning electromagnet 50. Further, the beam size refers to the size of the charged particle beam B in the XY plane. Also, the beam shape refers to the shape of the charged particle beam B in the XY plane.

[0036] For alignment at the time of initial setting, the profile monitor 11 detects the beam shape and position of the charged particle beam B. The profile monitor 11 is arranged at a position between the quadrupole electromagnet 8 and the scanning electromagnet 50 on the base axis AX. The dose monitor 12 detects the dose of the charged particle beam B. The dose monitor 12 is arranged on the downstream side of the scanning electromagnet 50 on the base axis AX. The position monitors 13a, 13b detect and monitor the beam shape and position of the charged particle beam B. The position monitors 13a, 13b are arranged on the base axis AX more on the downstream side of the charged particle beam B than the dose monitor 12. Each of the monitors 11, 12, 13a, 13b outputs the detected results to the control section 7.

[0037] The collimator 40 is provided at least more on the downstream side of the charged particle beam B than the scanning electromagnet 50, and is a member that shields a part of the charged particle beam B and allows a part to pass. Here, the collimator 40 is provided on the downstream side of the position monitors 13a, 13b. The collimator 40 is connected to a collimator drive section 51 that moves the collimator 40.

[0038] The vent tube energy degrader 30 reduces the energy of the charged particle beam B as it passes through, thereby adjusting the energy of the charged particle beam B. The vent tube energy degrader 30 is configured as an adjustment member for adjusting the penumbra of the charged particle beam B. In this embodiment, the vent tube energy degrader 30 is held by a holding portion 60 provided at the front end 9a of the irradiation nozzle 9. The front end 9a of the irradiation nozzle 9 refers to the downstream end of the charged particle beam B. A detailed description of the vent tube energy degrader 30 and the holding portion 60 will be provided later.

[0039] The control unit 7 is composed of, for example, a CPU, ROM, and RAM. The control unit 7 controls the thickness adjustment mechanism of the accelerator 3, the energy degrader 20, the scanning electromagnet 50, the quadrupole electromagnet 8, and the collimator drive unit 51 based on the detection results output from each of the monitors 11, 12, 13a, and 13b.

[0040] Furthermore, the control unit 7 of the charged particle beam irradiation system 1 is connected to a treatment planning device 90 for performing charged particle beam therapy and a storage unit 95 for storing various data. Before treatment, the treatment planning device 90 measures the tumor 14 of the patient 15 using methods such as CT scans and plans the dose distribution (dose distribution of the charged particle beam to be irradiated) at various locations of the tumor 14. Specifically, the treatment planning device 90 creates a scan pattern for the tumor 14. The treatment planning device 90 sends the created scan pattern to the control unit 7. In the scan pattern created by the treatment planning device 90, it plans the scan speed and the scan path drawn by the charged particle beam B.

[0041] In the case of irradiation using a scanning-based charged particle beam, the tumor 14 is hypothetically divided into multiple layers along the Z-axis. In each layer, the charged particle beam is scanned and irradiated in a manner that follows the scanning path determined in the treatment plan. Then, after the irradiation of the charged particle beam in that layer is completed, the irradiation of the charged particle beam B in the adjacent next layer is performed.

[0042] In the Figure 2 In the charged particle beam irradiation system 1 shown, when the charged particle beam B is irradiated by scanning method, the quadrupole electromagnet 8 is set to the working state (on) so that the charged particle beam B that has passed through converges.

[0043] Next, a charged particle beam B is emitted from accelerator 3. The emitted charged particle beam B is scanned according to the scanning pattern determined in the treatment plan, controlled by scanning electromagnet 50. Thus, the charged particle beam B is irradiated simultaneously with scanning within an irradiation range of one layer defined in the Z-axis direction of the tumor 14. Once irradiation of one layer is completed, the charged particle beam B is irradiated into the next layer.

[0044] refer to Figure 3 (a) andFigure 3 (b) The charged particle beam irradiation image of the scanning electromagnet 50 corresponding to the control of the control unit 7 will be explained. Figure 3 (a) shows an irradiated body hypothetically cut into multiple layers in the depth direction. Figure 3 (b) shows a scanned image of a beam of charged particles in a layer as viewed from the depth direction.

[0045] like Figure 3 As shown in (a), the irradiated object is imaginarily cut into multiple layers along the depth direction of the irradiation. In this example, it is imaginarily cut into layers L1, L2, ..., L1 sequentially from the deepest layer (with the longest range of the charged particle beam B). n-1 Layer L n Layer L n+1 ...layer L N-1 Layer L N These N layers. And, as... Figure 3 As shown in (b), regarding the charged particle beam B, while tracing the beam trajectory along the scanning path TL, under continuous irradiation (line scan or raster scan), the beam trajectory is traced along layer L. n The scanning path TL is continuously irradiated, and in the case of point scanning, layer L is irradiated at one time. n Multiple irradiation points. Regarding the charged particle beam B, it is irradiated along a scanning path TL1 extending in the X-axis direction, and then slightly displaced in the Y-axis direction along a scanning path TL2, irradiating along an adjacent scanning path TL1. Thus, the charged particle beam B emitted from the irradiation unit 2, controlled by the control unit 7, moves along the scanning path TL.

[0046] Next, refer to Figures 4-7 The vent pipe energy reducer 30 is described in detail. Figure 4 This is a schematic diagram showing the state in which the vent tube energy depressor 30 is held by the holding part 60. (Example) Figure 4 As shown, the ventilator de-energizer 30 is a component with a rectangular plate shape. The ventilator de-energizer 30 has a planar incident surface 30a and an exit surface 30b extending in a direction orthogonal to the base axis AX. The ventilator de-energizer 30 has a uniform thickness within the range scanned by the charged particle beam B, thus attenuating a fixed amount of energy. The energy adjustment amount of the charged particle beam B can be changed by altering the thickness, i.e., the dimension between the incident surface 30a and the exit surface 30b. Therefore, the ventilator de-energizer 30 can adjust the penumbra of the charged particle beam B by adjusting the magnification of the beam size. The ventilator de-energizer 30 is made of materials with a density close to water, such as polyethylene or acrylic acid. Furthermore, the ventilator de-energizer 30 is designed to adjust the expansion of the charged particle beam B.

[0047] The holding portion 60 is provided to the irradiation portion 2, and holds the snorkel reducer 30 on the irradiation portion 2 side. The holding portion 60 is provided to the front end portion 9a of the irradiation nozzle 9, and thus the snorkel reducer 30 is disposed on the downstream side of all the components disposed inside the irradiation nozzle 9, that is, on the side close to the patient 15. By being held by the holding portion 60, the snorkel reducer 30 is in a state of being disposed on the irradiation portion 2 side. The state of being disposed on the irradiation portion 2 side means, for example, a state in which the snorkel reducer 30 can move along with the movement of the irradiation portion 2, rather than a state in which the snorkel reducer is disposed around the patient 15 or mounted on the bed of the patient 15. The holding portion 60 can hold the snorkel reducer 30 on the irradiation portion 2 side while holding the snorkel reducer 30 at a position closest to the patient 15. In addition, the position closest to the patient 15 means, for example, a position at which the patient 15 and the snorkel reducer 30 are positioned at a distance of less than 30 cm. However, the distance of the snorkel reducer 30 from the patient 15 can be appropriately changed depending on the relationship with the surrounding environment or the like.

[0048] The holding portion 60 has a pair of side wall portions 61 that support the outer peripheral portion 30c of the snorkel reducer 30. The holding portion 60 has a pair of side wall portions 62 (see FIG. 8B) that face the other outer peripheral portion 30c. Figure 4 The side wall portions 61, 62 extend downward from the support portion 86. A wide-width member 87 is provided to the front end portion of the side wall portions 61, 62. In addition, the holding portion 60 can hold the snorkel reducer 30 having various thicknesses. For example, the holding portion 60 can hold the thin snorkel reducer 30A, and can also hold the thick snorkel reducer 30B. In the case of changing the thickness, the user takes out the thin snorkel reducer 30A from the holding portion 60, and holds the thick snorkel reducer 30B to the holding portion 60. In this way, the holding portion 60 is configured to be able to hold the snorkel reducer having various thicknesses, and thus can be said to have a structure that enables selection of the level of adjustment of the penumbra, that is, the thickness. In addition, the holding portion 60 can function as, for example, a filler holder used in the wobbling irradiation method. Thus, the holding portion 60 can hold the snorkel reducer 30 by the filler holder 66. In addition, the holding portion 60 can have a collimator holder 67 that holds the collimator on the lower side of the filler holder 66.

[0049] Here, the penumbra will be described with reference to Figure 5 . Figure 5 is a graph that shows the dose distribution when the charged particle beam B is irradiated in a prescribed plane that is perpendicular to the base axis AX by the scanning method. The horizontal axis shows the position in the prescribed direction of the prescribed plane, and the vertical axis shows the dose at each position. However, in order to facilitate understanding, Figure 5 , the graph shown in FIG. 8A is deformed and shown. Figure 5Chart G1 in the diagram represents the dose distribution of the charged particle beam B per scan. Multiple charts G1 are generated at various locations by scanning the charged particle beam B within a defined plane, with gradual offsets. The total dose distribution, when these charts G1 are superimposed, is represented by chart G2. Figure 5 The area denoted as W represents the baseline target width. The baseline target width W represents the width of the irradiated object within the plane. The width of the tumor 14 within the irradiation plane is used as the baseline target width W. Within the baseline target width W, a flat region FE is formed in Figure G2. The flat region FE is a region where the dose is approximately uniform, and where the dose difference falls within a specified range. The region further outward than the baseline target width W is called the penumbra P.

[0050] Here, the ventilator de-energizer 30 can suppress the amplification of the beam size of the charged particle beam B. Therefore, in suppressing the penumbra, the ventilator de-energizer 30 reduces the spread of the charged particle beam B (refer to Figure G1a). As a result, the dose distribution changes overall, and the spread of the charged particle beam B also decreases, thereby suppressing the penumbra P (refer to Figure G2a).

[0051] Figure 6 It is a graph showing the results of simulation experiments related to the relationship between the spread of the charged particle beam B and the depth of the object. Figure 6 The graph shown depicts the propagation of charged particle beam B in water when the ventilator 30 is set to an arbitrary thickness, calculated using Monte Carlo simulations at various thicknesses. The horizontal axis represents the distance from the surface of the water tank. This corresponds to the depth of tumor 14 from the surface of patient 15. The vertical axis represents the propagation of charged particle beam B, calculated using a Gaussian fitting method. Additionally, Figure 6 In this design, the distance between the ventilator de-energizer 30 and the water tank, i.e., the thickness of the air layer through which the charged particle beam B emitted from the ventilator de-energizer 30 passes, is set to 50 mm. This is equivalent to the distance between the ventilator de-energizer 30 and the surface of the patient's body 15.

[0052] like Figure 6 As shown, the greater the thickness of the airway de-energizer 30 in the superficial region, the more effectively the propagation of the charged particle beam B is suppressed. Conversely, the thinner the airway de-energizer 30 in the deep region, the more effectively the propagation of the charged particle beam B is suppressed. Based on these simulation results, the charged particle beam irradiation system 1 can be configured to select the adjustment level (here, thickness) of the penumbra of the airway de-energizer 30 according to the depth of the tumor 14 within the patient 15.

[0053] For example, if the tumor 14 is located in a superficial region E1a (less than 10 cm) within the body, a ventilator depressor 30 with a thickness of 13 cm can be selected. If the tumor 14 is located in a deep region E2a (10 cm or more) within the body, a ventilator depressor 30 with a thickness of 0 cm or 4 cm can be selected. Alternatively, if the tumor 14 is located in a superficial region E1b (less than 7 cm) within the body, a ventilator depressor 30 with a thickness of 12 cm can be selected. If the tumor 14 is located in a middle region E2b (7 cm or more but less than 12 cm) within the body, a ventilator depressor 30 with a thickness of 8 cm can be selected. Furthermore, if the tumor 14 is located in a deep region E3b (12 cm or more) within the body, a ventilator depressor 30 with a thickness of 0 cm or 4 cm can be selected.

[0054] Figure 7 and Figure 8 It means according to Figure 6 A graph showing the results of a simulation experiment with varying air layer thickness. Figure 7 This represents the results of a simulation test when the air layer thickness is 100 mm. Figure 8 This represents the results of a simulated test when the air layer thickness is 200 mm. For example... Figures 6-8 As shown, the depth of the ventilator 30 varies with the thickness of the air layer, and the relationship between the depth and the expansion of the charged particle beam B changes accordingly. Therefore, the charged particle beam irradiation system 1 can be configured to adjust the depth of the ventilator 30 and the expansion of the charged particle beam B based on the thickness of the air layer. Figure 2 The distance is used to select the adjustment level (i.e., thickness) of the penumbra of the vent tube deflector 30.

[0055] Next, refer to Figure 4 and Figure 9 The structure that allows for the selection of the adjustment level (i.e., thickness) of the penumbra of the vent tube de-energizer 30 is explained. Figure 9 This is a block diagram showing the structure used to select the adjustment level of the penumbra of the vent tube deflector 30. (Example) Figure 9 As shown, the charged particle beam irradiation system 1 includes the aforementioned control unit 7, output unit 76, reading unit 77, and identification information detection unit 78. Furthermore, the control unit 7 includes an information acquisition unit 70, a calculation unit 71, and a determination unit 72.

[0056] The information acquisition unit 70 acquires various information related to the irradiation of the charged particle beam B from the treatment planning device 90 and the storage unit 95. The information acquisition unit 70 is capable of acquiring information about the depth of the tumor 14 within the patient 15 and the distance between the patient 15 and the irradiation unit 2 (see reference) from the treatment plan generated by the treatment planning device 90. Figure 2The calculation unit 71 performs various calculations related to the selection of the penumbra adjustment level of the ventilation tube de-radiator 30. The calculation unit 71 calculates the distance information between the tumor 14 within the patient 15 and the distance between the patient 15 and the irradiation unit 2 (reference). Figure 2 The penumbra adjustment level, i.e., thickness, of the ventilator de-energizer 30 is selected by at least one of the distance information. The calculation unit 71 can, for example, compare with... Figures 6-8 The thickness of the ventilator depressor 30 is selected using the pre-prepared data and the acquired information. Alternatively, the calculation unit 71 can select an appropriate thickness of the ventilator depressor 30 by performing calculations based on the acquired information. However, the treatment planning device 90 can select an appropriate thickness of the ventilator depressor 30, in which case the information acquisition unit 70 acquires information about the thickness of the ventilator depressor 30. The determination unit 72 determines whether the correct ventilator depressor 30 is configured in the holding unit 60.

[0057] The output unit 76 outputs various information. The output unit 76 consists of a monitor, a speaker, etc. For example, the output unit 76 can output information about the thickness of the selected ventilator energy degrader 30 to the user. Thus, the user can configure the ventilator energy degrader 30 of the thickness selected by the control unit 7 in the holding unit 60.

[0058] Here, the reading unit 77, the identification information detection unit 78, and the determination unit 72 are configured as a detection unit 80 to detect that the vent tube de-energizer 30 is misconfigured relative to the holding unit 60.

[0059] Specifically, the reading unit 77 reads the thickness information assigned to each ventilator energy degrader 30 from the holding unit 81 (reference). Figure 4 (a) Reading thickness-related information. Regarding the thickness information holding unit 81, there are no particular limitations as long as it can hold thickness-related information; for example, it can be constructed from a barcode. In this case, the reading unit 77 is constructed from a barcode reader. Furthermore, the thickness information holding unit 81 can be constructed from a QR code (registered trademark), and the reading unit 77 can be constructed from a QR code reader. Alternatively, the thickness information holding unit 81 can be constructed from a magnetic information holding mechanism, and the reading unit 77 can be constructed from a device for reading that magnetic information.

[0060] The identification information detection unit 78 detects information that can identify the ventilator de-energizer 30 held by the holding unit 60. For example, the identification information detection unit 78 can detect signals from a predetermined detection mechanism provided on the holding unit 60 as identification information. When the ventilator de-energizer 30 is held by the holding unit 60, such a detection mechanism can send a signal indicating the thickness of the held ventilator de-energizer 30 to the identification information detection unit 78.

[0061] The determination section 72 determines whether the thickness selected by the calculation section 71 coincides with the thickness read by the reading section 77. In the case of non-coincidence, the determination section 72 outputs information on the case where the airway reducer 30 with an error is arranged through the output section 76. In the case of coincidence, the determination section 72 outputs information on the case where the airway reducer 30 with no error is arranged through the output section 76.

[0062] The determination section 72 compares the thickness information read by the reading section 77 with the thickness selected by the calculation section 71. At this time, the user can determine an error in advance by reading the thickness information by the reading section 77 before the airway reducer 30 is arranged in the holding section 60. Also, the determination section 72 determines the thickness of the airway reducer 30 held by the holding section 60 from the identification information detected by the identification information detection section 78, and compares the thickness with the thickness selected by the calculation section 71. At this time, the user can determine an error without the reading operation by the reading section 77.

[0063] Next, a charged particle beam irradiation method according to the present embodiment will be described with reference to Figure 10 Figure 10 is a process chart showing the contents of the charged particle beam irradiation method according to the present embodiment. As shown in Figure 10 , a process S10 of selecting the adjustment level (i.e., the thickness) of the penumbra of the airway reducer 30 according to at least one of the depth of the tumor 14 in the patient 15 and the distance between the patient 15 and the irradiation section 2 is executed. Next, a process S20 of arranging the airway reducer 30 selected in the process S10 in the holding section 60 is executed. Next, a process S30 of determining whether the airway reducer 30 with an error is arranged in the holding section 60 using the detection section 80 (see Figure 9 ) is executed. In addition, in the case of using the reading section 77, the process S30 of determination is executed in the stage before the process S20. Next, if the airway reducer 30 with no error is arranged, a process S40 of irradiating the tumor 14 with the charged particle beam B by the irradiation section 2 is executed.

[0064] Next, the effects of the charged particle beam irradiation system 1 and the charged particle beam irradiation method according to the present embodiment will be described.

[0065] ​The charged particle beam irradiation system 1 according to the present embodiment includes an irradiation unit 2 that irradiates a tumor 14 with a charged particle beam B by scanning the charged particle beam B with a scanning electromagnet 50, and a snorkel degrader 30 that adjusts penumbra of the charged particle beam B. Thus, by adjusting the penumbra of the charged particle beam B with the snorkel degrader 30, it is possible to suppress irradiation of the charged particle beam B to the outside of the tumor 14 when the irradiation unit 2 irradiates the tumor 14 near the boundary thereof. Here, a holding portion 60 that holds the snorkel degrader 30 is provided to the irradiation unit 2. Thus, it is possible to easily perform alignment between the charged particle beam B that irradiates the tumor 14 and the snorkel degrader 30. Thus, in a state where the penumbra is adjusted at an appropriate position with the snorkel degrader 30, the irradiation unit 2 can irradiate the tumor 14 with the charged particle beam B. For example, in a case where the snorkel degrader is provided on the side of a patient bed of the patient 15, a worker has to align the snorkel degrader while considering the positional relationship between the patient 15 and the irradiation unit 2, but since the patient 15 is difficult to see, there is a problem that it is difficult to perform the alignment. In this regard, in the present embodiment, since it is only necessary to hold the snorkel degrader 30 to the holding portion 60, it is easy to perform the alignment. According to the above, the irradiation unit 2 can appropriately irradiate the tumor 14 with the charged particle beam B.

[0066] The holding portion 60 can be provided to a front end portion 9a of the irradiation unit 2. At this time, the snorkel degrader 30 can adjust the penumbra at a position close to the patient 15. Thus, after the snorkel degrader 30 adjusts the penumbra, the charged particle beam B is rapidly irradiated to the tumor 14 before the spread becomes large.

[0067] The charged particle beam irradiation system 1 can be configured to be able to select the adjustment level of the penumbra of the snorkel degrader 30 according to the depth of the tumor 14 in the patient 15. At this time, the snorkel degrader 30 can adjust the penumbra at an appropriate adjustment level of the penumbra according to the depth of the tumor 14 in the patient 15.

[0068] The charged particle beam irradiation system 1 can be configured to be able to select the adjustment level of the penumbra of the snorkel degrader 30 according to the distance between the patient 15 and the irradiation unit 2. At this time, the snorkel degrader 30 can adjust the penumbra at an appropriate adjustment level of the penumbra according to the distance between the patient 15 and the irradiation unit 2.

[0069] The charged particle beam irradiation system 1 can further include a detection unit 80 that detects a snorkel degrader 30 that is arranged in error with respect to the holding portion 60. At this time, it is possible to suppress adjustment of the penumbra by the snorkel degrader 30 of an inappropriate adjustment level.

[0070] The charged particle beam irradiation method according to the present embodiment is a charged particle beam irradiation method of irradiating a tumor 14 in a patient 15 with a charged particle beam B, the charged particle beam irradiation method including: a step S10 of selecting an adjustment level of a penumbra of an air-tube degrader 30 that adjusts a penumbra of the charged particle beam B, in accordance with a depth of the tumor 14 in the patient 15; a step S20 of disposing the selected air-tube degrader 30 with respect to the charged particle beam B; and a step S40 of irradiating the tumor 14 with the charged particle beam B by scanning the charged particle beam B with a scanning electromagnet 50.

[0071] According to the charged particle beam irradiation method, the air-tube degrader 30 can adjust the penumbra at an appropriate adjustment level of the penumbra in accordance with the depth of the tumor 14 in the patient 15. According to the above, the charged particle beam B can be appropriately irradiated to the tumor 14.

[0072] In a large hospital where the number of patients is large, in the case of a case (for example, a head and neck case) that is treated using a low-energy proton beam, the efficiency of beam use in treatment becomes good in treatment using the adjustment member (air-tube degrader) as in the present embodiment. Since the amount of use of the proton beam is limited for each facility, if the efficiency is high, the number of patients treated can be increased compared to control under the conventional ESS.

[0073] The air-tube degrader 30 can have an adjustment level corresponding to the distance of the patient 15 and the irradiation unit 2. At this time, the air-tube degrader 30 can adjust the penumbra at an adjustment level of the penumbra corresponding to the distance of the patient 15 and the irradiation unit 2.

[0074] The charged particle beam irradiation method further includes a step S10 of selecting an adjustment level in accordance with a depth of a tumor 14 in a patient 15, and in a step S30 of disposing an air-tube degrader 30, the selected air-tube degrader 30 can be disposed. At this time, the air-tube degrader 30 can adjust the penumbra at an appropriate adjustment level of the penumbra in accordance with the depth of the tumor 14 in the patient 15.

[0075] The charged particle beam irradiation method further includes a step S10 of selecting an adjustment level in accordance with a distance of a patient 15 and an irradiation unit 2, and in a step S30 of disposing an air-tube degrader 30, the selected air-tube degrader 30 can be disposed. At this time, the air-tube degrader 30 can adjust the penumbra at an appropriate adjustment level of the penumbra in accordance with the distance of the patient 15 and the irradiation unit 2.

[0076] For example, a charged particle beam irradiation system having no snorkel degrader 30 at the front end 9a of the irradiation unit 2 is described as a comparative example. At this time, in the charged particle beam irradiation system, the energy of the charged particle beam B is controlled by an energy adjustment device (ESS: Energy Selection System) upstream of the beam transport line 21. The energy adjustment device needs to cause a large energy loss in the energy degrader 20 to change the depth of arrival of the charged particle beam B in the patient body. Therefore, the charged particle beam B has a spread in the direction of movement. The beam having a spread in the direction of movement is transported by the energy adjustment device, whereby as the charged particle beam B advances downstream of the beam transport line 21, the beam size is enlarged by diffusion, and the penumbra is also enlarged.

[0077] In this regard, in the charged particle beam irradiation system 1 according to the present embodiment, the snorkel degrader 30 adjusts the penumbra of the charged particle beam B immediately in front of the patient 15. Therefore, the energy loss in the energy degrader 20 on the upstream side is suppressed to be small, and the energy loss for the penumbra adjustment of the snorkel degrader 30 is increased, whereby the patient 15 can be irradiated in a state where the enlargement of the beam size is suppressed, and the penumbra can be suppressed. Also, since the thickness of the snorkel degrader 30 can be selected, the level of adjustment of the penumbra of the snorkel degrader 30 can be appropriately adjusted in accordance with the depth of the tumor 14 and the distance of the patient 15 from the irradiation unit 2.

[0078] The present application is not limited to the above-described embodiments.

[0079] For example, the snorkel degrader is exemplified as the adjustment member that adjusts the penumbra, but other members can be employed as long as they are members that can adjust the penumbra. For example, a collimator or a multi-leaf collimator can be provided at the position of the holding portion 60, i.e., the position immediately in front of the patient 15, and the multi-leaf collimator adjusts the penumbra. The multi-leaf collimator can adjust the penumbra by blocking the beam of the charged particle beam B at a position corresponding to the boundary of the tumor 14. The level of adjustment can be adjusted by the opening diameter. If the opening diameter is made large (i.e., a margin is provided to the outside diameter of the tumor), the penumbra portion is not blocked, and if the opening diameter is made small (adapted to the outside diameter of the tumor), the penumbra can be blocked. At this time, the penumbra is adjusted by the multi-leaf collimator at the position closest to the patient 15 (e.g., 30 cm or less), whereby the charged particle beam B can be irradiated to the tumor 14 before the beam size of the charged particle beam B is enlarged.

[0080] The position of the holding portion that holds the multi-leaf collimator does not necessarily have to be the front end of the irradiation unit, but can be inside the irradiation unit.

Claims

1. A charged particle beam irradiation system that irradiates a charged particle beam to an irradiated object in an object, the charged particle beam irradiation system comprising: an irradiation section that irradiates the charged particle beam to the irradiated object by scanning the charged particle beam with a scanning electromagnet; an adjustment member that adjusts a penumbra of the charged particle beam that is scanned; a holding section that is provided to the irradiation section and holds the adjustment member; an information acquisition section that acquires various information related to irradiation of the charged particle beam from a treatment planning device and a storage section; and a calculation section that selects a level of adjustment, i.e., a thickness, of a penumbra of a snorkel degrader in accordance with at least one of information of a depth of a tumor in a patient and information of a distance of the patient from the irradiation section, the charged particle beam irradiation system further comprising a detection section that detects whether the snorkel degrader that is incorrect is arranged with respect to the holding section.

2. The charged particle beam irradiation system according to claim 1, wherein the holding section is provided to a front end section of the irradiation section, the charged particle beam irradiation system further comprising a detection section that detects whether the adjustment member that is incorrect is arranged with respect to the holding section. ​ ​ ​ ​ ​ ​ ​ 3. The charged particle beam illumination system according to claim 1 or 2, wherein, ​

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