Particle beam therapy devices and accelerators

Abstract

The present invention provides a particle beam therapy device and an accelerator, which can adjust the intensity of the particle beam using an appropriate adjustment method while increasing the scanning speed of the particle beam. The accelerator (3) sets the parameters of the ion source device (60) based on at least one layer of the tumor (14) to adjust the intensity of the particle beam (B). At this time, when the maximum intensity of the particle beam (B) required in the layer to be irradiated is low, the ion source device (60) can generate particles in a state where the parameters are suppressed to cope with low intensity, for example, with reference to layers (L2) and (L3) of (a) of FIG. 7 . Thus, the parameters in the ion source device (60) can be suppressed to an appropriate size. Thus, the scanning speed of the particle beam (B) can be increased while adjusting the intensity of the particle beam (B) using an appropriate adjustment method.

Description

Technical Field

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2021-055419, filed on March 29, 2021. The entire contents of this Japanese patent application are incorporated herein by reference.

[0002] The invention relates to a particle beam therapeutic device and an accelerator. Background Art

[0003] Conventionally, particle beam therapy devices that treat a patient's affected area by irradiating it with a particle beam include, for example, the device described in Patent Document 1. In the particle beam therapy device described in Patent Document 1, a particle beam is irradiated from an irradiation unit using a scanning method. Specifically, the irradiation unit irradiates the affected area while moving the irradiation position of the particle beam using scanning electromagnets.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-209372

[0005] Here, when the irradiation unit utilizes a scanning method to irradiate the particle beam, in order to increase the dose at each irradiation location, the irradiation unit will extend the irradiation time at that location as a countermeasure. In contrast, in order to shorten the treatment time by irradiating at a higher scanning speed, the ion source parameters are sometimes set to the maximum, and the particle beam intensity is adjusted by using a damper to cut a portion of the particle beam. However, this method sometimes causes various problems such as the life of the particle generation unit being shortened due to the parameters of the particle generation unit becoming higher than necessary. Therefore, it is necessary to use appropriate methods to adjust the intensity of the particle beam. Summary of the Invention

[0006] Therefore, an object of the present invention is to provide a particle beam therapy apparatus and an accelerator capable of adjusting the intensity of a particle beam by using an appropriate adjustment method while increasing the scanning speed of the particle beam.

[0007] A particle beam therapy device according to one embodiment of the present invention is a device for irradiating an irradiated object with a particle beam. The device comprises: an accelerator for generating a particle beam within an acceleration space; and an irradiation unit for virtually dividing the irradiated object into multiple layers and irradiating the layers with the particle beam while scanning each layer using a scanning electromagnet. The accelerator comprises a particle generation unit for generating particles accelerated within the acceleration space. The accelerator sets parameters for the particle generation unit based on at least one layer of the irradiated object and adjusts the intensity of the particle beam according to the set parameters.

[0008] The accelerator sets parameters for a particle generation unit based on at least one layer of the irradiated object and adjusts the intensity of the particle beam according to the set parameters. In this case, if the maximum intensity of the particle beam required in the layer to be irradiated is low, the particle generation unit can generate particles while suppressing the parameters to cope with low intensities. This allows the parameters in the particle beam generation unit to be suppressed to an appropriate level. Furthermore, by adjusting the intensity of the particle beam to obtain energy corresponding to the irradiation position of the particle beam, the accelerator can obtain the desired dose through short-term irradiation, even without irradiating the irradiation position for a long time. This allows the particle beam's scanning speed to be increased while adjusting the intensity of the particle beam using appropriate adjustment methods.

[0009] The accelerator can set the parameters of the particle generation unit based on the maximum intensity for at least one slice. Because the adjustment unit adjusts the intensity by cutting a portion of the particle beam using a damper, it cannot adjust the intensity by increasing it. Therefore, by setting the parameters of the particle beam generation unit based on the maximum intensity for a slice, insufficient intensity of the output particle beam can be prevented.

[0010] The accelerator can set the parameters of the particle generation unit to produce an output with a predetermined intensity increased relative to the maximum intensity. In this case, even if the particle beam intensity falls below the predetermined value with the same parameters due to temporal changes in the particle generation unit, the intensity deficiency can be suppressed by presetting the parameters to produce a high output intensity.

[0011] In particle beam therapy systems, the accelerator includes an adjustment unit that adjusts the intensity of the particle beam by bending it with a deflector and cutting a portion of it with a damper within the acceleration chamber. By adjusting the amount of cutting to achieve an intensity appropriate for the particle beam's irradiation location, the adjustment unit can achieve the desired dose with a short irradiation time, even without irradiating the irradiation location for a long time.

[0012] The accelerator can adjust the intensity of the particle beam according to a pre-prepared data table. In this case, the accelerator can appropriately adjust the intensity of the particle beam while reducing the computational load.

[0013] The irradiation unit may include a detector for detecting the intensity of the particle beam, and the accelerator may provide feedback of the detection result of the detector to adjust the intensity of the particle beam. In this case, even if the intensity of the particle beam differs from the planned intensity, the intensity of the particle beam can be appropriately controlled based on the detection result of the detector.

[0014] An accelerator according to one embodiment of the present invention generates a particle beam for virtually dividing an irradiated object into multiple layers and irradiating each layer using a scanning method. The accelerator includes a particle generation unit that generates particles within an acceleration space, and parameters of the particle generation unit are set based on at least one layer of the irradiated object, and the intensity of the particle beam is adjusted according to the set parameters.

[0015] According to this accelerator, the same operational effects as those of the above-mentioned particle beam therapy system can be obtained.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a particle beam therapy apparatus and an accelerator capable of adjusting the intensity of a particle beam by an appropriate adjustment method and improving the scanning speed of the particle beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram schematically showing the configuration of a particle beam therapy system according to one embodiment of the present invention.

[0019] Figure 2 yes Figure 1 A schematic diagram of the structure of a particle beam therapy device near the irradiation part.

[0020] Figure 3 This is a diagram showing the layers set for tumors.

[0021] Figure 4 It is a schematic cross-sectional view of an accelerator according to an embodiment of the present invention.

[0022] Figure 5 It is a schematic plan view of an accelerator according to an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram showing a state in which a part of a particle beam is cut by a damper.

[0024] Figure 7 This is a graph showing the intensity of a particle beam that can be output by particles generated by an ion source device.

[0025] Figure 8 This is a diagram showing an image of a data table.

[0026] Figure 9 This is a flowchart showing the processing details in the particle beam therapy system.

[0027] Explanation of symbols

[0028] 1- Particle beam therapy device, 2- Irradiation unit, 3- Accelerator, 12- Dose monitor (detection unit), 60- Ion source device (particle generation unit), 63- Deflector, 64- Damper, 80- Adjustment unit. DETAILED DESCRIPTION

[0029] Hereinafter, a particle beam therapy system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0030] Figure 1 This is a schematic diagram showing the structure of a particle beam therapy device 1 according to one embodiment of the present invention. The particle beam therapy device 1 is a system used for cancer treatment, etc., using radiotherapy. The particle beam therapy device 1 includes: an accelerator 3 that accelerates charged particles generated in an ion source device and emits them as a particle beam; an irradiation unit 2 that irradiates an irradiated object with a particle beam; and a beam transmission line 21 that transmits the particle beam emitted from the accelerator 3 to the irradiation unit 2. The irradiation unit 2 is mounted on a rotating gantry 5 that is arranged to surround a treatment table 4. The irradiation unit 2 can rotate around the treatment table 4 via the rotating gantry 5. In addition, a more detailed structure of the accelerator 3, the irradiation unit 2, and the beam transmission line 21 will be described later.

[0031] Figure 2 yes Figure 1 Schematic diagram of the structure of the particle beam therapy device 1 near the irradiation part. In addition, in the following description, the terms "X-axis direction", "Y-axis direction" and "Z-axis direction" are used for description. "Z-axis direction" refers to the direction in which the base axis AX of the particle beam B extends, which is the irradiation depth direction of the particle beam B. In addition, "base axis AX" refers to the irradiation axis of the particle beam B when it is not deflected by the scanning electromagnet 50 described later. Figure 2 , the particle beam B is irradiated along the base axis AX. The "X-axis direction" refers to a direction in a plane perpendicular to the Z-axis direction. The "Y-axis direction" refers to a direction perpendicular to the X-axis direction in a plane perpendicular to the Z-axis direction.

[0032] First, refer to Figure 2 The general structure of the particle beam therapy device 1 involved in this embodiment is described. The particle beam therapy device 1 is an irradiation device involved in the scanning method. In addition, the scanning method is not particularly limited, and line scanning, raster scanning, point scanning, etc. can be used. Figure 2 As shown, the particle beam therapy system 1 includes an accelerator 3 , an irradiation unit 2 , a beam transport line 21 , a control unit 7 , a treatment planning device 90 , and a storage unit 95 .

[0033] The accelerator 3 is a device that accelerates charged particles to emit a particle beam B of a predetermined intensity. Examples of the accelerator 3 include a cyclotron accelerator and a synchrocyclotron accelerator. In addition, when a cyclotron accelerator that emits a particle beam B of a predetermined intensity is used as the accelerator 3, the energy adjustment unit 20 (see Figure 1), thereby adjusting (reducing) the energy of the particle beam sent to the irradiation unit 2. The accelerator 3 is connected to a control unit 7, which controls the current supplied. The particle beam B generated in the accelerator 3 is transmitted to the irradiation unit 2 via a beam transmission line 21. The beam transmission line 21 connects the accelerator 3, the energy adjustment unit 20, and the irradiation unit 2, thereby transmitting the particle beam emitted from the accelerator 3 to the irradiation unit 2.

[0034] The irradiation unit 2 irradiates a tumor (irradiated body) 14 in the body of a patient 15 with a particle beam B. Particle beam B is obtained by accelerating charged particles at high speed, and examples thereof include proton beams, heavy particle (heavy ion) beams, and electron beams. Specifically, the irradiation unit 2 is a device that irradiates the tumor 14 with a particle beam B emitted from an accelerator 3 that accelerates charged particles generated in an ion source (not shown) and transmitted through a beam transmission line 21. The irradiation unit 2 includes a scanning electromagnet 50, a quadrupole electromagnet 8, a profile monitor 11, a dose monitor 12, position monitors 13a, 13b, a collimator 40, and an energy degrader 30. The scanning electromagnet 50, the monitors 11, 12, 13a, 13b, the quadrupole electromagnet 8, and the energy degrader 30 are housed in an irradiation nozzle 9, which serves as a housing. In this manner, the irradiation unit 2 is constructed by housing the main components in the irradiation nozzle 9. In addition, the quadrupole electromagnet 8, the contour monitor 11, the dose monitor 12, the position monitors 13a and 13b, and the energy degrader 30 may be omitted.

[0035] The scanning electromagnets 50 include an X-axis scanning electromagnet 50A and a Y-axis scanning electromagnet 50B. Each of the X-axis scanning electromagnets 50A and the Y-axis scanning electromagnet 50B consists of a pair of electromagnets. The magnetic field between the pair of electromagnets is changed based on the current supplied by the control unit 7, thereby scanning the particle beam B passing between the electromagnets. The X-axis scanning electromagnet 50A scans the particle beam B along the X-axis direction, while the Y-axis scanning electromagnet 50B scans the particle beam B along the Y-axis direction. These scanning electromagnets 50 are sequentially arranged on the base axis AX and further downstream of the particle beam B than the accelerator 3. Furthermore, the scanning electromagnets 50 scan the particle beam B into a scanning pattern pre-planned by the treatment planning device 90 for irradiation. How the scanning electromagnets 50 are controlled will be described later.

[0036] 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 concentrate and converge the particle beam B according to the current supplied from the control unit 7. The X-axis direction quadrupole electromagnet 8a converges the particle beam B in the X-axis direction, and the Y-axis direction quadrupole electromagnet 8b converges the particle beam B in the Y-axis direction. By changing the current supplied to the quadrupole electromagnet 8, the concentration amount (convergence amount) can be changed, thereby changing the beam size of the particle beam B. The quadrupole electromagnet 8 is sequentially configured on the base axis AX and is sequentially configured between the accelerator 3 and the scanning electromagnet 50. In addition, beam size refers to the size of the particle beam B on the XY plane. And, beam shape refers to the shape of the particle beam B on the XY plane.

[0037] The profile monitor 11 detects the beam shape and position of the particle beam B for initial positioning. The profile monitor 11 is arranged on the base axis AX and between the quadrupole electromagnet 8 and the scanning electromagnet 50. The dose monitor 12 detects the dose of the particle beam B. The dose monitor 12 is arranged on the base axis AX and downstream of the scanning electromagnet 50. The position monitors 13a and 13b detect and monitor the beam shape and position of the particle beam B. The position monitors 13a and 13b are arranged on the base axis AX and downstream of the particle beam B relative to the dose monitor 12. Each monitor 11, 12, 13a, and 13b outputs the detection results to the control unit 7.

[0038] The energy degrader 30 reduces the intensity of the particle beam B passing therethrough to finely adjust the intensity of the particle beam B. In this embodiment, the energy degrader 30 is provided at the front end 9a of the irradiation nozzle 9. The front end 9a of the irradiation nozzle 9 is the downstream end of the particle beam B.

[0039] The collimator 40 is a component that is located at least downstream of the particle beam B relative to the scanning electromagnet 50 to shield a portion of the particle beam B while allowing a portion to pass through. Here, the collimator 40 is located downstream of the position monitors 13 a and 13 b. The collimator 40 is connected to a collimator driver 51 that moves the collimator 40.

[0040] The control unit 7 is composed of, for example, a CPU, ROM, and RAM, etc. The control unit 7 controls the accelerator 3, the scanning electromagnet 50, the quadrupole electromagnet 8, and the collimator driver 51 based on the detection results output from the monitors 11, 12, 13a, and 13b.

[0041] The control unit 7 of the particle beam therapy system 1 is connected to a treatment planning device 90 that performs particle beam therapy treatment planning, and a storage unit 95 that stores various data. Before treatment, the treatment planning device 90 measures the tumor 14 of the patient 15 using CT or other methods, and plans the dose distribution (the dose distribution of the particle beam to be irradiated) at various locations on the tumor 14. Specifically, the treatment planning device 90 creates a scan pattern for the tumor 14. The treatment planning device 90 transmits the created scan pattern to the control unit 7. The scan pattern created by the treatment planning device 90 specifies the scanning path that the particle beam B will follow at a specific scanning speed.

[0042] When particle beam irradiation is performed using a scanning method, the tumor 14 is virtually divided into multiple layers in the Z-axis direction, and the particle beam is irradiated in each layer using a scanning path specified in the treatment plan. After the particle beam irradiation of the single layer is completed, the particle beam B is irradiated in the next adjacent layer.

[0043] In passing Figure 2 When the particle beam therapy apparatus 1 shown performs irradiation with the particle beam B by a scanning method, the quadrupole electromagnet 8 is set to an operating state (ON) to converge the particle beam B that has passed therethrough.

[0044] Next, the accelerator 3 emits a particle beam B. The emitted particle beam B is scanned by the scanning electromagnet 50 in accordance with the scanning pattern specified in the treatment plan. Thus, the particle beam B is irradiated by scanning within the irradiation range of a single layer set in the Z-axis direction for the tumor 14. Once irradiation of one layer is completed, the particle beam B is irradiated to the next layer.

[0045] refer to Figure 3 (a) and Figure 3 (b) describes a particle beam irradiation image of the scanning electromagnet 50 corresponding to the control of the control unit 7. Figure 3 (a) shows an irradiated object virtually cut into multiple layers in the depth direction. Figure 3 (b) shows a scanning image of a particle beam of one layer observed from the depth direction.

[0046] like Figure 3 As shown in (a), the irradiated body is virtually cut into multiple layers in the irradiation depth direction. In this example, the layers are virtually cut into layers L1, L2, ..., L3 from deep to shallow (the range of the particle beam B is from long to short). n-1 , layer L n , layer L n+1 , ... layer L N-1 , layer L N These N layers. And, as Figure 3As shown in (b), when the particle beam B is continuously irradiated (line scanning or raster scanning) while drawing a beam trajectory along the scanning path TL, the particle beam B is continuously irradiated along the layer L n The scanning path TL is continuously irradiated, and the beam trajectory is drawn along the scanning path TL while performing point scanning. n The particle beam B irradiates along a scanning path TL1 extending in the X-axis direction, and after being slightly shifted in the Y-axis direction along a scanning path TL2, irradiates along an adjacent scanning path TL1. In this manner, the particle beam B emitted from the irradiation unit 2, controlled by the control unit 7, moves along the scanning path TL.

[0047] refer to Figure 4 and Figure 5 The accelerator 3 will be described in more detail. Figure 4 It is a schematic cross-sectional view of the accelerator 3 . Figure 5 3 is a schematic top view of the accelerator 3. The accelerator 3 is a device that generates a particle beam B by rotating charged particles around a central axis CL.

[0048] like Figure 4 and Figure 5 As shown, the accelerator 3 includes a magnetic core 10, an ion source device 60 (particle generation unit), a coil 61, a D-shaped electrode 62, a deflector 63, and a damper 64. The magnetic core 10 includes an upper magnetic pole 10a and a lower magnetic pole 10b that face each other in the direction of the central axis CL to form a main magnetic field, and a yoke 10c that magnetically connects the magnetic poles 10a and 10b. The magnetic poles 10a and 10b are located in a vacuum chamber (not shown) whose interior is evacuated.

[0049] The ion source device 60 is a device for generating charged particles such as ions. When the charged particles generated by the ion source device 60 reach the center of the accelerator 3 through the guide tube 60a, their direction is bent from the vertical direction to the horizontal direction by the inflector 60b located at the front end of the guide tube 60a. In addition, the conduction and disconnection of the particle beam B are controlled by a pair of electrodes 66 (refer to Figure 4 ) switch. Then, the particles are moved along the predetermined track plane MH (reference Figure 6 ) while drawing a circular orbit T (a spiral orbit from the central axis CL of the accelerator 3 toward the outside) and rotating, and is accelerated (refer to Figure 5 ). Thus, a particle beam B is generated. That is, the region between the magnetic poles 10a and 10b in the vacuum box functions as an acceleration space S for charged particles (refer to Figure 4 Then, the circular orbit T of the particle beam is fine-tuned by the deflector 67 and the magnetic channel 68, and the particle beam B is converged by the quadrupole magnet 69, and is ejected through the beam outlet 70 and introduced into the beam transmission pipeline 21 (refer to Figure 5 ). In addition, the ion source device 60 can also be arranged inside the accelerator 3. In this case, the inflection device 60b and the like are unnecessary. The ion source device 60 operates according to the parameters set by the ion source control unit 72.

[0050] like Figure 4 As shown, the coil 61 is used to form the main magnetic field. The coil 61 includes a first portion arranged to surround the outer circumference of the upper magnetic pole 10a and a second portion arranged to surround the outer circumference of the lower magnetic pole 10b. The first portion and the second portion are electrically connected in series.

[0051] The D-shaped electrode 62 is a fan-shaped electrode. The D-shaped electrode 62 is disposed between the magnetic pole 10a and the magnetic pole 10b, that is, within the acceleration space S. The D-shaped electrodes 62 are opposed to each other in the direction in which the central axis CL extends, sandwiching the orbital plane. The D-shaped electrode 62 is connected to a high-frequency power supply (not shown). The high-frequency power supply supplies high-frequency power to the D-shaped electrode 62 to generate an alternating electric field (high-frequency electric field) between the D-shaped electrodes 62, in which the period of the electric field alternates at a constant period. By synchronizing the time when charged particles pass between the D-shaped electrodes 62 with the period of the high-frequency electric field, charged particles can be accelerated each time they pass through the D-shaped electrode 62.

[0052] The deflector 63 is disposed at a different position in the circumferential direction from the D-shaped electrode 62. The damper 64 is disposed downstream of the deflector 63 in the direction of travel of the particle beam B. The deflector 63 is composed of a pair of electrodes that face each other in the direction in which the central axis CL extends, sandwiching the track surface. A power supply 71 is connected to the deflector 63 for applying a voltage to the pair of electrodes.

[0053] In accelerator 3, as Figure 6 As shown, the deflector 63 (reference Figure 5 ) bends the particle beam B upward from the orbiting position R1 to the orbiting positions R2 and R3, and cuts it with the damper 64. Thus, the deflector 63 and the damper 64 function as an adjustment unit 80 for adjusting the intensity of the particle beam B. The adjustment unit 80 adjusts the intensity of the particle beam B by bending the particle beam B with the deflector 63 and cutting a portion of the particle beam B with the damper 64 within the acceleration space S.

[0054] Here, the accelerator 3 is set based on at least one slice L of the tumor 14 n The ion source device 60 is configured to set parameters and adjust the intensity of the particle beam B according to the set parameters. That is, the accelerator 3 sets the intensity of the particle beam B based on at least one layer L of the tumor 14. n The parameters of the ion source device 60 are adjusted and the cutting amount of the particle beam B by the adjustment unit 80 is controlled, thereby adjusting the intensity of the particle beam B. In this embodiment, the accelerator 3 is set based on a layer L nThe parameters of the ion source device 60 are as follows. That is, the accelerator 3 is used for one layer L n Each of the parameters of the ion source device 60 is set.

[0055] The ion source control unit 72 controls each layer L n Set plasma parameters. Plasma parameters refer to parameters that determine the intensity of plasma when the ion source device 60 generates plasma to generate particles. Examples of plasma parameters include bias current, bias voltage, and cathode temperature. Thus, for example, Figure 7 As shown in (a), the intensity of the particle beam B that can be output by the particles generated by the ion source device 60 varies depending on the layer L. n It varies.

[0056] The ion source control unit 72 controls the ion source according to the n The maximum intensity of the ion source device 60 is used to set the parameters. Figure 7 In the slice L3 of (a), the maximum current value (maximum intensity) of the particle beam B in the slice is represented by “IG1.” This maximum current value IG1 is the maximum value in one slice L3 and is therefore lower than the maximum current value IG2 output by the accelerator 3 .

[0057] The ion source control unit 72 sets the parameters of the ion source device 60 so as to obtain the n The maximum current value (maximum intensity) increases the output of the specified current value. For example, Figure 7 In example (a), the ion source control unit 72 sets the plasma parameters to achieve an output equal to the maximum current value IG1 for a single layer L3 plus the additional current value M. Specifically, the ion source control unit 72 sets the plasma parameters to achieve an output 10% higher than the maximum current value IG1. The additional current value M is not limited to 10% and can be set, for example, within a range of 5 to 100%.

[0058] The accelerator 3 causes the adjustment unit 80 to adjust the n The particle beam B outputted by the plasma parameters determined as described above is controlled to adjust the intensity of the particle beam B. The power supply 71 is the target layer L n The initial value of the deflector voltage (chopping voltage) is set to the same as that for layer L. n Then, the power supply 71 adjusts the chopping voltage to a value corresponding to the current value of the first point in the layer L. n The weight of each point in the image is matched to obtain the current value for the next point. n During the irradiation of the particle beam B, the ion source control unit 72 keeps the plasma parameters constant. On the other hand, the power supply 71 controls the plasma parameters according to the layer L.n The chopping voltage is changed according to the irradiation position within the particle beam, and the amount of cutting of the particle beam B by the adjustment unit 80 is adjusted to obtain the particle beam B of the desired intensity. Figure 3 When the intensity of the particle beam B at the irradiation position P2 in (b) is higher than the intensity of the particle beam B at the irradiation position P1, the power supply 71 increases the chopping voltage so that the cutting amount of the particle beam B at the irradiation position P1 is greater than the cutting amount of the particle beam B at the irradiation position P2.

[0059] Here, the accelerator 3 controls the adjustment of the intensity of the particle beam B according to the data table prepared in advance, that is, controls the cutting amount of the adjustment unit 80. For example, Figure 8 The data table shown. When making this data table, the cathode temperature of the ion source device 60 is set to the cathode temperature that can output the maximum current. Then, without changing the cathode temperature, the bias current is set to a specified value, and the irradiation unit 2 is caused to irradiate the particle beam B. At this time, while changing the chopping voltage of the power supply 71, the particle beam B is irradiated, and various parameters are measured. As parameters to be measured, the "beam current", "beam position (or deflector correction amount)", and "beam size" of the particle beam B output from the accelerator 3 can be cited. The beam current is the intensity of the output particle beam B. The beam position refers to the position (deviation size) of the particle beam B at the accelerator exit. The position of the particle beam B can be measured using a beam monitor provided at the accelerator exit. The deflector correction amount refers to the size of the deviation correction amount when the position is adjusted from the beam position. The beam size refers to the diameter of the output particle beam B.

[0060] When the predetermined bias current and predetermined chopping voltage are set according to the measurement results obtained by the measurement as described above, a data table can be made regarding what parameters of the particle beam B can be obtained. In addition, in the data table, the parameters of the particle beam B for the intermediate bias current between the set value of a certain bias current and the set value of the adjacent bias current are supplemented by interpolation through calculation. Similarly, the parameters of the particle beam B for the intermediate chopping voltage between the set value of a certain chopping voltage and the set value of the adjacent chopping voltage are also supplemented by interpolation through calculation. This data table is stored in Figure 2 In the storage unit 95 shown. When the treatment planning device 90 creates a scanning pattern, the bias current in the ion source device 60 is set with reference to the maximum current value in each layer. In addition, the treatment planning device 90 understands what parameters of the particle beam B should be irradiated at each irradiation position of each layer, and determines the chopping voltage at each irradiation position by referring to the data table. For example, when the bias current of a certain layer is "A1", the treatment planning device 90 determines the corresponding chopping voltage by referring to the parameters of the particle beam B included in the "A1" row of the data table and referring to the parameters at each irradiation position (reference Figure 8). Thus, the treatment planning device 90 can determine the scanning pattern and the bias current and chopping voltage corresponding to the scanning pattern. When irradiating the particle beam B, the control unit 7 sends command values ​​to the power supply 71 and the ion source control unit 72, and sets the bias current and chopping voltage at the time corresponding to the generated scanning pattern.

[0061] In addition, even when a scanning pattern is created based on the data table as described above, the parameters of the particle beam B during actual irradiation may deviate from the planned parameters. For example, the irradiation unit 2 can grasp the deviation between the current value (intensity) of the particle beam B and the planned value by monitoring the current value (intensity) of the particle beam B using the dose monitor 12 (detection unit). When such a deviation is detected, the control unit 7 does not refer to the data table again to correct the chopping voltage, but instead feeds back the detection result of the detected deviation to the power supply 71 to control the adjustment of the intensity of the particle beam B, that is, to control the cutting amount of the particle beam B by the adjustment unit 80. However, when the detected deviation exceeds the specified amount, the data table is recreated by performing the above-mentioned measurement during maintenance, etc.

[0062] Next, refer to Figure 9 The following describes the processing contents when the irradiation unit 2 irradiates the tumor 14 with the particle beam B for treatment. This processing is executed by the control unit 7. Figure 9 Before the processing, the control unit 7 obtains the data of the treatment plan made in advance by the treatment planning device 90. First, the control unit 7 sets the parameters of the ion source device 60 for the layer to be irradiated (step S10). Next, the control unit 7 sets the initial value of the chopping voltage of the deflector 63 according to the current value (intensity) of the first point of the target layer (step S20). Then, the control unit 7 scans while irradiating the target layer with the particle beam B, and adjusts the cutting amount of the particle beam B by the adjustment unit 80 to adjust the intensity at each irradiation position (step S30). Next, the control unit 7 determines whether the scanning for the target layer has been completed (step S40). If it is determined that it has not been completed, the control unit 7 repeats step S30. If it is determined that it has been completed, the control unit 7 determines whether the scanning for all layers has been completed (step S50). If it is determined that it has not been completed, the control unit 7 switches the layer (step S60) and repeats the processing from step S10. On the other hand, if it is determined that the scanning of all layers has been completed, Figure 9 The indicated processing ends.

[0063] Next, the effects of the particle beam therapy system 1 and the accelerator 3 according to this embodiment will be described.

[0064] In the particle beam therapy apparatus 1, the accelerator 3 includes an adjustment unit 80 that adjusts the intensity of the particle beam B by bending the particle beam B using a deflector 63 and cutting a portion of the particle beam B using a damper 64 within the acceleration space S. Therefore, by adjusting the cutting amount to obtain an intensity corresponding to the irradiation position of the particle beam B, the adjustment unit 80 can achieve a desired dose with a short irradiation time, even without irradiating the irradiation position for a long time.

[0065] Here, reference Figure 7 (b) The parameters of the ion source device of the accelerator involved in the comparative example are described. In the comparative example, the parameters of the ion source device are set to be able to output the maximum current value IG2 as the output of the accelerator. Thus, for all layers, the output of the particle beam B becomes the maximum current value IG2. However, in the comparative example, since the ion source device is operated in a manner that can always obtain the maximum current value IG2, there is a problem that the maintenance cycle becomes shorter (for example, about two weeks). In addition, even if the damper 64 is used to cut the particle beam B with low intensity, the particle beam B with high current value will always be cut, so there will be a problem of splashing that affects the surrounding structures. In addition, the deflector 63 has to always bend the high-intensity particle beam B, so according to the intensity output, if the resolution of the setting voltage of the power supply of the deflector 63 is not good, it may be impossible to adjust the intensity with high precision. In addition, the ion source device may also become unstable.

[0066] In contrast, in this embodiment, the accelerator 3 sets the parameters of the ion source device 60 based on at least one layer of the tumor 14 to control the amount of cutting of the particle beam B by the adjustment unit 80, thereby adjusting the intensity of the particle beam B. In this case, when the maximum intensity of the particle beam B required in the layer to be irradiated is low, the ion source device 60 can generate particles in a state where the parameters are suppressed to correspond to the low intensity (for example, see Figure 7 (a) layers L2 and L3). Thus, the parameters in the ion source device 60 can be suppressed to appropriate values. Furthermore, the accelerator 3 adjusts the intensity of the particle beam B to obtain a dose corresponding to the irradiation position of the particle beam B. Thus, even without irradiating the irradiation position for a long time, the desired dose can be obtained through short irradiation. Thus, the intensity of the particle beam B can be adjusted using an appropriate adjustment method while increasing the scanning speed of the particle beam B.

[0067] The accelerator 3 can set the parameters of the ion source device 60 based on the maximum intensity for at least one slice. The adjustment unit 80 adjusts the intensity by cutting a portion of the particle beam B using the damper 64, so it cannot adjust the intensity by increasing it. Therefore, by setting the parameters of the ion source device 60 based on the maximum intensity for the slice, it is possible to prevent the intensity of the output particle beam from being insufficient.

[0068] The accelerator 3 can set the parameters of the ion source device 60 so as to obtain an output with the maximum intensity increased by a predetermined intensity. In this case, even if the intensity of the particle beam B during the damper cutting is unstable and falls below a predetermined value, the intensity deficiency can be suppressed by increasing the intensity in advance.

[0069] The accelerator 3 can adjust the intensity of the particle beam B based on a pre-prepared data table. In this case, the accelerator 3 can appropriately adjust the amount of cutting by the adjustment unit 80 while reducing the computational load.

[0070] The irradiation unit 2 may include a dose monitor 12 (detection unit) for detecting the intensity of the particle beam B. The accelerator 3 may feed back the detection result of the dose monitor 12 to adjust the intensity of the particle beam B. In this case, even if the intensity of the particle beam B is different from the planned intensity, the amount of ablation by the adjustment unit 80 can be appropriately controlled based on the detection result of the dose monitor 12.

[0071] The accelerator 3 involved in one scheme of the present embodiment is an accelerator 3 that generates a particle beam B for virtually dividing an irradiated object into multiple layers and irradiating each layer using a scanning method. It has an ion source device 60 that generates particles in an acceleration space, and sets parameters of the ion source device 60 based on at least one layer of the irradiated object, and adjusts the intensity of the particle beam B according to the set parameters.

[0072] According to this accelerator 3 , the same operational effects as those of the above-mentioned particle beam therapy system 1 can be obtained.

[0073] The present invention is not limited to the above-described embodiment.

[0074] For example, the parameters of the ion source device may not be set for each layer, that is, one parameter may be set uniformly for multiple layers.

[0075] exist Figure 4 and Figure 5 In the embodiment of the present invention, a cyclotron is exemplified as an accelerator. However, the structure of the present invention can be adopted for various accelerators such as a synchrocyclotron and a linear accelerator (linear accelerator).

Claims

1. A particle beam therapy device for irradiating a subject with a particle beam, comprising: an accelerator for generating the particle beam in an acceleration space; and an irradiation unit that virtually divides the irradiated object into multiple layers and irradiates the layer with the particle beam while scanning each layer using a scanning electromagnet; The accelerator has: a particle generating unit that generates the particles accelerated in the acceleration space using parameters based on at least one layer of the irradiated object; and The adjustment unit adjusts the intensity of the particle beam by bending the particle beam using a deflector and shielding a portion of the particle beam using a damper in the acceleration space.

2. The particle beam therapy device according to claim 1, wherein: The accelerator sets parameters of the particle generation unit according to a maximum intensity for at least one slice.

3. The particle beam therapy device according to claim 2, wherein: The accelerator sets parameters of the particle generation unit so as to obtain an output obtained by increasing the maximum intensity by a predetermined intensity.

4. The particle beam therapy device according to any one of claims 1 to 3, wherein: The accelerator adjusts the intensity of the particle beam according to a pre-prepared data table.

5. The particle beam therapy device according to any one of claims 1 to 3, wherein: The irradiation unit includes a detection unit for detecting the intensity of the particle beam. The accelerator feeds back the detection result of the detection unit to adjust the intensity of the particle beam.

6. An accelerator that generates a particle beam for virtually dividing an irradiated object into multiple layers and irradiating each layer using a scanning method, wherein: have: a particle generating unit that generates the particles accelerated in an acceleration space using parameters based on at least one layer of the irradiated object; as well as The adjustment unit adjusts the intensity of the particle beam by bending the particle beam using a deflector and shielding a portion of the particle beam using a damper in the acceleration space.

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