Particle beam therapy equipment and accelerators

Abstract

To provide a particle beam medical treatment device capable of increasing a scanning speed of particle beams while adjusting the intensity of the particle beams in an appropriate adjustment mode, and an accelerator.SOLUTION: An accelerator 3 sets a parameter of an ion source device 60 based on at least one layer of a tumor 14 and adjusts the intensity of particle beams B. In this case, the ion source device 60 can generate particle beams in a state in which it is suppressed to a parameter that can correspond to low intensity (refer to, e.g., a layer L2 and a layer L3 of Fig. 7(a)) in the case that the maximum intensity of particle beams B required in a layer to be an irradiation object is low. This can suppress a parameter of the ion source device 60 to an appropriate magnitude. Consequently, a scanning speed of the particle beams B can be increased while adjusting the intensity of the particle beams B in an appropriate adjustment mode.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a particle beam therapy system and an accelerator. [Background technology]

[0002] Conventionally, as a particle beam therapy device that performs treatment by irradiating an affected area of ​​a patient with a particle beam, for example, the device described in Patent Document 1 is known. In the particle beam therapy device described in Patent Document 1, the particle beam is irradiated from an irradiation unit by a scanning method. That is, the irradiation unit performs irradiation while moving the irradiation position of the particle beam with respect to the affected area by scanning with a scanning magnet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-209372 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when the irradiation unit irradiates the particle beam by the scanning method, the irradiation unit increases the dose at each irradiation position by lengthening the irradiation time at that position. In contrast, in order for the irradiation unit to irradiate at a high scanning speed and shorten the treatment time, the parameters of the ion source may be set to the maximum and a part of the particle beam may be cut off by a damper to adjust the intensity of the particle beam. However, in such a method, various problems may occur, such as the life of the particle generation unit being shortened, due to the parameters of the particle generation unit being higher than necessary. Therefore, it is required to adjust the intensity of the particle beam in an appropriate manner.

[0005] Therefore, an object of the present invention is to provide a particle beam therapy system and an accelerator that can increase the scanning speed of a particle beam while adjusting the intensity of the particle beam in an appropriate adjustment manner. [Means for solving the problem]

[0006] A particle beam therapy device according to one aspect of the present invention is a particle beam therapy device that irradiates an irradiated object with a particle beam, and includes an accelerator that generates the particle beam in an acceleration space, an irradiation unit that virtually divides the irradiated object into a plurality of layers and irradiates each layer while scanning the particle beam with a scanning electromagnet, and the accelerator includes a particle generation unit that generates particles to be accelerated in the acceleration space, and the accelerator sets parameters of the particle generation unit based on at least one layer of the irradiated object and adjusts the intensity of the particle beam based on the set parameters.

[0007] The accelerator sets parameters of the particle generator based on at least one layer of the irradiated object, and adjusts the intensity of the particle beam based on the set parameters. In this case, when the maximum intensity of the particle beam required in the layer to be irradiated is low, the particle generator can generate particles in a state where the parameters are suppressed to correspond to the low intensity. This makes it possible to suppress the parameters in the particle beam generator to an appropriate value. In addition, the accelerator adjusts the intensity of the particle beam so that energy according to the irradiation position of the particle beam is obtained, thereby making it possible to obtain a desired dose with a short irradiation without irradiating the irradiation position for a long time. As described above, the scanning speed of the particle beam can be increased while adjusting the intensity of the particle beam in an appropriate adjustment manner.

[0008] The accelerator may set parameters of the particle generator based on the maximum intensity for at least one layer. The adjustment unit adjusts the intensity by cutting off a part of the particle beam with a damper, and therefore cannot adjust the intensity in a direction to increase the intensity. Therefore, by setting parameters of the particle beam generator based on the maximum intensity for the layer, it is possible to prevent the intensity of the output particle beam from being insufficient.

[0009] The accelerator may set parameters of the particle generator so as to obtain an output with a predetermined intensity increased from the maximum intensity. In this case, even if the particle beam intensity becomes lower than expected due to the same parameters due to the change over time in the particle generator, the intensity shortage can be prevented by setting parameters that can output a high intensity in advance.

[0010] In the particle beam therapy device, the accelerator is provided with an adjustment unit that adjusts the intensity of the particle beam by bending the particle beam with a deflector and cutting a part of the particle beam with a damper in the acceleration space. Therefore, the adjustment unit adjusts the amount of cutting so that the intensity according to the irradiation position of the particle beam is obtained, and it becomes possible to obtain a desired dose with a short irradiation without performing a long irradiation to the irradiation position.

[0011] The accelerator may adjust the intensity of the particle beam based on a data table prepared in advance, in which case the accelerator can appropriately adjust the intensity of the particle beam while reducing the computation load.

[0012] The irradiation unit may have a detection unit that detects the intensity of the particle beam, and the accelerator may adjust the intensity of the particle beam by feeding back the detection result of the detection unit. In this case, even if the intensity of the particle beam is different from that planned, the intensity of the particle beam can be appropriately controlled based on the detection result of the detection unit.

[0013] An accelerator according to one aspect of the present invention is an accelerator that virtually divides an irradiated object into a plurality of layers and generates a particle beam for irradiating each layer by a scanning method, the accelerator comprising a particle generation unit that generates particles in an acceleration space, sets parameters of the particle generation unit based on at least one layer of the irradiated object, and adjusts the intensity of the particle beam based on the set parameters.

[0014] This accelerator can provide the same effects and advantages as the particle beam therapy device described above. Effect of the Invention

[0015] According to the present invention, it is possible to provide a particle beam therapy system and an accelerator that are capable of increasing the scanning speed of a particle beam while adjusting the intensity of the particle beam in an appropriate adjustment manner. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram showing a particle beam therapy device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic configuration diagram of the vicinity of an irradiation unit of the charged particle beam irradiation system of FIG. [Diagram 3] FIG. 13 shows layers set for a tumor. [Figure 4] 1 is a schematic cross-sectional view of an accelerator according to an embodiment of the present invention. [Diagram 5] 1 is a schematic plan view of an accelerator according to an embodiment of the present invention. [Figure 6] FIG. 13 is a schematic diagram showing how a part of a particle beam is cut off by a damper. [Figure 7] 4 is a graph showing the intensity of a particle beam that can be output by particles generated by an ion source device. [Figure 8] FIG. 13 is a diagram showing an image of a data table. [Figure 9] 4 is a flowchart showing processing steps performed in the particle beam therapy system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 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 given the same reference numerals, and duplicated explanations will be omitted.

[0018] FIG. 1 is a schematic diagram showing a particle beam therapy apparatus 1 according to an embodiment of the present invention. The particle beam therapy apparatus 1 is a system used for cancer treatment by radiation therapy. The particle beam therapy apparatus 1 includes an accelerator 3 that accelerates charged particles generated by an ion source device and emits the particles as a particle beam, an irradiation unit 2 that irradiates a subject with the particle beam, and a beam transport line 21 that transports the particle beam emitted from the accelerator 3 to the irradiation unit 2. The irradiation unit 2 is attached to a rotating gantry 5 that is provided so as to surround a treatment table 4. The irradiation unit 2 can be rotated around the treatment table 4 by the rotating gantry 5. The accelerator 3, the irradiation unit 2, and the beam transport line 21 will be described in more detail later.

[0019] FIG. 2 is a schematic diagram of the vicinity of the irradiation unit of the particle beam therapy device 1 of FIG. 1. 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 particle beam B extends, and is the depth direction of the irradiation of the particle beam B. The "base axis AX" is the irradiation axis of the particle beam B when it is not deflected by the scanning electromagnet 50 described later. FIG. 2 shows the state in which the particle beam B is irradiated along the base axis AX. The "X-axis direction" is one direction in a plane perpendicular to the Z-axis direction. The "Y-axis direction" is a direction perpendicular to the X-axis direction in a plane perpendicular to the Z-axis direction.

[0020] First, referring to Fig. 2, a schematic configuration of a particle beam therapy device 1 according to this embodiment will be described. The particle beam therapy device 1 is an irradiation device related to a scanning method. The scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, etc. may be adopted. As shown in Fig. 2, the particle beam therapy device 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.

[0021] The accelerator 3 is a device that accelerates charged particles and emits a particle beam B of a preset intensity. Examples of the accelerator 3 include a cyclotron and a synchrocyclotron. When a cyclotron that emits a particle beam B of a preset intensity is used as the accelerator 3, it is possible to adjust (reduce) the energy of the particle beam sent to the irradiation unit 2 by using an energy adjustment unit 20 (see FIG. 1). The accelerator 3 is connected to a control unit 7, and the current supplied thereto is controlled. The particle beam B generated by the accelerator 3 is transported to the irradiation unit 2 by a beam transport line 21. The beam transport line 21 connects the accelerator 3, the energy adjustment unit 20, and the irradiation unit 2, and transports the particle beam emitted from the accelerator 3 to the irradiation unit 2.

[0022] The irradiation unit 2 irradiates a tumor (irradiated object) 14 in the body of a patient 15 with a particle beam B. The particle beam B is a charged particle accelerated to a high speed, and examples of the particle beam B include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. Specifically, the irradiation unit 2 is a device that irradiates the tumor 14 with the particle beam B emitted from an accelerator 3 that accelerates charged particles generated by an ion source (not shown) and transported by a beam transport line 21. The irradiation unit 2 includes a scanning magnet 50, a quadrupole magnet 8, a profile monitor 11, a dose monitor 12, position monitors 13a and 13b, a collimator 40, and a degrader 30. The scanning magnet 50, the monitors 11, 12, 13a, and 13b, the quadrupole magnet 8, and the degrader 30 are accommodated in an irradiation nozzle 9 as a container. In this manner, the irradiation unit 2 is configured by accommodating each main component in the irradiation nozzle 9. The quadrupole electromagnet 8, the profile monitor 11, the dose monitor 12, the position monitors 13a and 13b, and the degrader 30 may be omitted.

[0023] The scanning magnets 50 include an X-axis scanning magnet 50A and a Y-axis scanning magnet 50B. Each of the X-axis scanning magnet 50A and the Y-axis scanning magnet 50B is composed of a pair of electromagnets (see FIG. 5), and changes the magnetic field between the pair of electromagnets according to the current supplied from the control unit 7 to scan the particle beam B passing between the electromagnets. The X-axis scanning magnet 50A scans the particle beam B in the X-axis direction, and the Y-axis scanning magnet 50B scans the particle beam B in the Y-axis direction. These scanning magnets 50 are arranged in this order on the base axis AX and downstream of the particle beam B from the accelerator 3. The scanning magnet 50 scans the particle beam B so that the particle beam B is irradiated in a scan pattern previously planned by the treatment planning device 90. How to control the scanning magnet 50 will be described later.

[0024] The quadrupole electromagnets 8 include an X-axis quadrupole electromagnet 8a and a Y-axis quadrupole electromagnet 8b. The X-axis quadrupole electromagnets 8a and the Y-axis quadrupole electromagnets 8b focus the particle beam B in response to a current supplied from the control unit 7. The X-axis quadrupole electromagnets 8a focus the particle beam B in the X-axis direction, and the Y-axis quadrupole electromagnets 8b focus the particle beam B in the Y-axis direction. The beam size of the particle beam B can be changed by changing the current supplied to the quadrupole electromagnets 8 to change the focus amount (convergence amount). The quadrupole electromagnets 8 are arranged in this order on the base axis AX between the accelerator 3 and the scanning electromagnet 50. The beam size is the size of the particle beam B in the XY plane. The beam shape is the shape of the particle beam B in the XY plane.

[0025] The profile monitor 11 detects the beam shape and position of the particle beam B for alignment during initial setting. The profile monitor 11 is disposed on the base axis AX 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 disposed on the base axis AX 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 disposed on the base axis AX downstream of the particle beam B from the dose monitor 12. Each of the monitors 11, 12, 13a, and 13b outputs the detection results to the control unit 7.

[0026] The degrader 30 reduces the intensity of the passing particle beam B to finely adjust the intensity of the particle beam B. In this embodiment, the degrader 30 is provided at the tip 9a of the irradiation nozzle 9. The tip 9a of the irradiation nozzle 9 is an end portion on the downstream side of the particle beam B.

[0027] The collimator 40 is a member provided at least downstream of the scanning electromagnet 50 in the particle beam B, and blocks a part of the particle beam B and allows a part of the particle beam B to pass through. Here, the collimator 40 is provided downstream of the position monitors 13a and 13b. The collimator 40 is connected to a collimator drive unit 51 that moves the collimator 40.

[0028] The control unit 7 is composed of, for example, a CPU, a ROM, a RAM, etc. The control unit 7 controls the accelerator 3, the scanning magnet 50, the quadrupole magnet 8, and the collimator driving unit 51 based on the detection results output from the monitors 11, 12, 13a, and 13b.

[0029] The control unit 7 of the particle beam therapy device 1 is also connected to a treatment planning device 90 that performs treatment planning for particle beam therapy, and a storage unit 95 that stores various data. The treatment planning device 90 measures the tumor 14 of the patient 15 using a CT or the like before treatment, and plans a dose distribution (dose distribution of the particle beam to be irradiated) at each position of 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 plans what kind of scan path and what kind of scan speed the particle beam B will trace.

[0030] When irradiating the tumor 14 with a particle beam by the scanning method, the tumor 14 is virtually divided into a plurality of layers in the Z-axis direction, and the particle beam is scanned and irradiated in one layer along a scanning path determined in a treatment plan. After the irradiation of the particle beam in the one layer is completed, the particle beam B is irradiated in the next adjacent layer.

[0031] When the particle beam B is irradiated by the scanning method using the particle beam therapy system 1 shown in FIG. 2, the quadrupole electromagnet 8 is activated (ON) so that the passing particle beam B is converged.

[0032] Next, particle beam B is emitted from accelerator 3. The emitted particle beam B is scanned according to a scan pattern defined in the treatment plan by the control of scanning electromagnet 50. As a result, particle beam B is irradiated while scanning within an irradiation range in one layer set in the Z-axis direction with respect to tumor 14. When irradiation of one layer is completed, particle beam B is irradiated to the next layer.

[0033] An image of particle beam irradiation by the scanning electromagnet 50 according to the control of the control unit 7 will be described with reference to Fig. 3(a) and (b). Fig. 3(a) shows an irradiation target virtually sliced ​​into multiple layers in the depth direction, and Fig. 3(b) shows a particle beam scanning image in one layer as viewed from the depth direction.

[0034] As shown in FIG. 3(a), the irradiated object is virtually sliced ​​into multiple layers in the irradiation depth direction. In this example, the layers are layer L1, layer L2, ... layer L1, in order from the deepest layer (where the range of particle beam B is long). n-1 , Layer L n , Layer L n+1 , …Layer L N-1 , Layer L N As shown in Fig. 3(b), the particle beam B is virtually sliced ​​into layers L and N while tracing a beam trajectory along a scanning path TL. In the case of continuous irradiation (line scanning or raster scanning), n In the case of spot scanning, the light is irradiated continuously along a scanning path TL of the layer L. n The particle beam B is irradiated to a plurality of irradiation spots. The particle beam B is irradiated along a scanning path TL1 extending in the X-axis direction, shifted slightly in the Y-axis direction along a scanning path TL2, and irradiated along the adjacent scanning path TL1. In this manner, the particle beam B emitted from the irradiation unit 2 controlled by the control unit 7 moves on the scanning path TL.

[0035] The accelerator 3 will be described in further detail with reference to Figures 4 and 5. Figure 4 is a schematic cross-sectional view of the accelerator 3. Figure 5 is a schematic plan 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.

[0036] 4 and 5, the accelerator 3 includes a core 10, an ion source device 60 (particle generation section), a coil 61, a dee electrode 62, a deflector 63, and a damper 64. The core 10 has an upper magnetic pole 10a and a lower magnetic pole 10b that face each other in the direction in which the central axis CL extends and form a main magnetic field, and a yoke portion 10c that magnetically connects the magnetic poles 10a and 10b. The magnetic poles 10a and 10b are located in a vacuum box (not shown) whose inside is evacuated.

[0037] The ion source device 60 is a device that generates 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 conduit 60a, the direction of the charged particles is bent from the vertical direction to the horizontal direction by the inflector 60b located at the tip of the conduit 60a. The particle beam B is turned on and off by a pair of electrodes 66 (see FIG. 4). Next, the particles are accelerated while rotating along a circular orbit T (a spiral orbit extending outward from the central axis CL of the accelerator 3) along a predetermined orbital plane MH (see FIG. 6) by the magnetic field formed by the core 10 and the coil 61 (see FIG. 5). This generates the particle beam B. That is, the region between the magnetic poles 10a and 10b in the vacuum box functions as an acceleration space S (see FIG. 4) for the charged particles. Thereafter, the circular orbit T of the particle beam is finely adjusted by a deflector 67 and a magnetic channel 68, and the particle beam B is focused by a quadrupole magnet 69 and emitted through a beam outlet 70, and introduced into the beam transport line 21 (see FIG. 5). The ion source device 60 may be disposed inside the accelerator 3. In this case, the inflector 60b and the like are not required. The ion source device 60 operates based on parameters set by an ion source control unit 72.

[0038] As shown in Fig. 4, the coil 61 is used to generate a main magnetic field. The coil 61 includes a first portion arranged to surround the outer periphery of the upper magnetic pole 10a and a second portion arranged to surround the outer periphery of the lower magnetic pole 10b. The first and second portions are electrically connected in series.

[0039] The Dee electrode 62 is an electrode having a sector shape. The Dee electrode 62 is disposed between the magnetic poles 10a and 10b, i.e., in the acceleration space S. The Dee electrodes 62 face each other in the direction in which the central axis CL extends so that the orbital plane is located between them. The Dee electrode 62 is connected to a high-frequency power source (not shown). The high-frequency power source supplies high-frequency power to the Dee electrodes 62 to generate an alternating electric field (high-frequency electric field) between the Dee electrodes 62, in which the period of the electric field alternates at a constant period. The charged particles are accelerated each time they pass through the Dee electrodes 62 by synchronizing the timing at which the charged particles pass between the Dee electrodes 62 with the period of the high-frequency electric field.

[0040] The deflector 63 is provided at a different position in the circumferential direction from the Dee electrode 62. The damper 64 is disposed downstream of the deflector 63 in the traveling direction of the particle beam B. The deflector 63 is configured by a pair of electrodes facing each other in the direction in which the central axis CL extends so as to sandwich the orbital plane, and a power source 71 that applies a voltage to the pair of electrodes is connected to the deflector 63.

[0041] In the accelerator 3, as shown in Fig. 6, the deflector 63 (see Fig. 5) bends the particle beam B upward from the rotation position R1 to rotation positions R2 and R3, and then the damper 64 cuts it off. In this manner, the deflector 63 and the damper 64 function as an adjustment unit 80 that adjusts the intensity of the particle beam B. The adjustment unit 80 adjusts the intensity of the particle beam B in the acceleration space S by bending the particle beam B with the deflector 63 and cutting off a part of the particle beam B with the damper 64.

[0042] Here, the accelerator 3 is located at least in one layer L of the tumor 14. n The parameters of the ion source device 60 are set based on the above, and the intensity of the particle beam B is adjusted based on the set parameters. n The parameters of the ion source device 60 based on the above are set, and the amount of the particle beam B cut by the adjustment unit 80 is controlled to adjust the intensity of the particle beam B. In this embodiment, the accelerator 3 is nThe parameters of the ion source device 60 are set based on the above. That is, the accelerator 3 is a layer L n The parameters of the ion source device 60 are set for each sample.

[0043] The ion source control unit 72 is a layer L n The plasma parameters are set for each layer L. The plasma parameters are parameters that determine the intensity of the plasma when the ion source device 60 generates plasma to generate particles. Examples of the plasma parameters include a bias current, a bias voltage, and a cathode temperature. As a result, the intensity of the particle beam B that can be output by the particles generated by the ion source device 60 is set for each layer L, as shown in FIG. 7(a), for example. n It's different every time.

[0044] The ion source control unit 72 is a layer L n The parameters of the ion source device 60 are set based on the maximum intensity for the layer L3. For example, in the layer L3 in FIG. 7(a), the maximum current value (maximum intensity) of the particle beam B in the layer is represented as "IG1". Since this maximum current value IG1 is the maximum value in one layer L3, it is lower than the maximum current value IG2 of the accelerator 3.

[0045] The ion source control unit 72 is a layer L n The parameters of the ion source device 60 are set so as to obtain an output obtained by increasing a predetermined current value with respect to the maximum current value (maximum intensity) for one layer L3. For example, in the example of FIG. 7(a), the ion source control unit 72 sets the plasma parameters so as to obtain an output obtained by adding an increased current value M to the maximum current value IG1 for one layer L3. Specifically, the ion source control unit 72 sets the plasma parameters so as to obtain an output 10% higher than the maximum current value IG1. Note that the increased current value M is not limited to 10% and may be set in the range of, for example, 5 to 100%.

[0046] Accelerator 3 is one layer L nThe power supply 71 controls the adjustment unit 80 to adjust the intensity of the particle beam B outputted to the target layer L according to the plasma parameters determined as described above. n The initial value of the deflector voltage (chopper voltage) in layer L n The power supply 71 is then set to a value corresponding to the current value for the first spot in layer L. n The chopper voltage is adjusted so that the current value corresponds to the weight of each spot in the layer L. n During irradiation of the particle beam B onto the layer L, the ion source control unit 72 keeps the plasma parameters constant. n According to the irradiation position in the image, the chopper voltage is changed to adjust the amount of particle beam B cut by the adjustment unit 80, and a particle beam B of a desired intensity is obtained. For example, in FIG. 3(b), when the intensity of particle beam B at irradiation position P2 is higher than the intensity of particle beam B at irradiation position P1, the power supply 71 increases the chopper voltage so that the amount of particle beam B cut at irradiation position P1 is larger than the amount of particle beam B cut at irradiation position P2.

[0047] Here, the accelerator 3 adjusts the intensity of the particle beam B, that is, controls the amount of cutting by the adjustment unit 80, based on a data table prepared in advance. For example, a data table as shown in FIG. 8 is prepared in advance. When creating the data table, the cathode temperature of the ion source device 60 is set to a cathode temperature that can output the maximum current. Next, the bias current is set to a predetermined value without changing the cathode temperature, and the irradiation unit 2 irradiates the particle beam B. At this time, the particle beam B is irradiated while changing the chopper voltage of the power supply 71, and each parameter is measured. The parameters to be measured include the "beam current", "beam position (or steerer correction amount)", and "beam size" of the particle beam B output from the accelerator 3. The beam current is the intensity of the particle beam B output. The beam position is the position (magnitude of deviation) of the particle beam B at the accelerator exit. The position of the particle beam B can be measured by a beam monitor provided at the accelerator exit. The steerer correction amount is the magnitude of the correction amount of deviation when the position is adjusted from the beam position. The beam size is the diameter of the output particle beam B.

[0048] Based on the measurement results of the above-mentioned measurement, a data table can be created showing what parameters of the particle beam B are obtained when a predetermined bias current and a predetermined chopper voltage are set. In the data table, the parameters of the particle beam B for a bias current that is intermediate between a certain bias current setting value and an adjacent bias current setting value are complemented by performing calculations and interpolation. Similarly, the parameters of the particle beam B for a chopper voltage that is intermediate between a certain chopper voltage and an adjacent chopper voltage setting value are complemented by performing calculations and interpolation. Such a data table is stored in the storage unit 95 shown in FIG. 2. When the treatment planning device 90 creates a scanning pattern, it sets the bias current in the ion source device 60 by referring to the maximum current value in each layer. In addition, the treatment planning device 90 grasps what parameters of the particle beam B should be irradiated at each irradiation position of each layer, and determines the chopper 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 checks the parameters of the particle beam B included in the row of "A1" in the data table against the parameters at each irradiation position, and determines the matching chopper voltage (see FIG. 8). This allows the treatment planning device 90 to determine a scanning pattern and a bias current and chopper voltage corresponding to the scanning pattern. When irradiating the particle beam B, the control unit 7 sends command values ​​to the power source 71 and the ion source control unit 72, and sets the bias current and chopper voltage at a timing according to the created scanning pattern.

[0049] Even if a scanning pattern is created according to the data table as described above, the parameters of the particle beam B in the actual irradiation may deviate from the planned ones. For example, the irradiation unit 2 can grasp the deviation from the planned value by monitoring the current value (intensity) of the particle beam B with the dose monitor 12 (detection unit). When the deviation is detected, the control unit 7 does not refer to the data table again to correct the chopper voltage, but feeds back the detection result of the detected deviation to the power supply 71 to adjust the intensity of the particle beam B, that is, to control the amount of the particle beam B cut by the adjustment unit 80. However, when the detected deviation exceeds a predetermined amount, the data table is remade by performing the above-mentioned measurement at the timing of maintenance or the like.

[0050] Next, referring to FIG. 9, the process contents when the irradiation unit 2 irradiates the tumor 14 with the particle beam B to perform treatment will be described. The process is executed by the control unit 7. Before performing the process of FIG. 9, the control unit 7 acquires data of the treatment plan created in advance by the treatment planning device 90. First, the control unit 7 sets parameters of the ion source device 60 for the layer to be irradiated (step S10). Next, the control unit 7 sets an initial value of the chopper voltage of the deflector 63 based on the current value (intensity) to the first spot of the target layer (step S20). Then, the control unit 7 performs scanning while irradiating the target layer with the particle beam B, and adjusts the amount of particle beam B cut by the adjustment unit 80 to adjust the intensity at each irradiation position (step S30). Next, the control unit 7 judges whether or not scanning for the target layer is completed (step S40). If it is judged that scanning is not completed, the control unit 7 repeats step S30. If it is judged that scanning is completed, the control unit 7 judges whether or not scanning for all layers is completed (step S50). If it is determined that scanning is not complete, the control unit 7 switches the layer (step S60) and repeats the process from step S10. On the other hand, if it is determined that scanning of all layers is complete, the process shown in FIG.

[0051] Next, the actions and effects of the particle beam therapy system 1 and the accelerator 3 according to this embodiment will be described.

[0052] In the particle beam therapy device 1, the accelerator 3 includes an adjustment unit 80 that adjusts the intensity of the particle beam B in the acceleration space S by bending the particle beam B with a deflector 63 and cutting off a part of the particle beam B with a damper 64. Therefore, the adjustment unit 80 adjusts the amount of cutting off so that the intensity according to the irradiation position of the particle beam B is obtained, thereby making it possible to obtain a desired dose with a short irradiation time without irradiating the irradiation position for a long time.

[0053] Here, the parameters of the ion source device of the accelerator according to the comparative example will be described with reference to FIG. 7(b). In the comparative example, the parameters of the ion source device are set so that the maximum current value IG2 can be output as the output of the accelerator. As a result, the output of the particle beam B becomes the maximum current value IG2 for all layers. However, in the comparative example, the ion source device is operated so that the maximum current value IG2 is always obtained, so there is a problem that the maintenance cycle is short (for example, about two weeks). In addition, even if the part where the intensity of the particle beam B is low is cut by the damper 64, the particle beam B with a high current value is always cut, so there is a problem that sputtering affects surrounding structures. In addition, since the deflector 63 must always bend the particle beam B with high intensity, depending on the output intensity, there is a possibility that the intensity cannot be adjusted with high accuracy unless the resolution of the set voltage of the power supply of the deflector 63 is good. In addition, there is a possibility that the ion source device becomes unstable.

[0054] In contrast, in this embodiment, the accelerator 3 sets parameters of the ion source device 60 based on at least one layer of the tumor 14, and controls the amount of particle beam B cut by the adjustment unit 80 to adjust 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 in which the parameters are suppressed to correspond to the low intensity (see, for example, layer L2 and layer L3 in FIG. 7(a)). This allows the parameters in the ion source device 60 to be suppressed to an appropriate magnitude. In addition, the accelerator 3 adjusts the intensity of the particle beam B so that a dose according to the irradiation position of the particle beam B is obtained, thereby making it possible to obtain a desired dose with a short irradiation without irradiating the irradiation position for a long time. As described above, the scanning speed of the particle beam B can be increased while adjusting the intensity of the particle beam B in an appropriate adjustment manner.

[0055] The accelerator 3 may set parameters of the ion source device 60 based on the maximum intensity for at least one layer. The adjustment unit 80 adjusts the intensity by cutting off a part of the particle beam B with the damper 64, and therefore cannot adjust by increasing the intensity. Therefore, by setting parameters of the ion source device 60 based on the maximum intensity for the layer, it is possible to prevent the intensity of the output particle beam from being insufficient.

[0056] The accelerator 3 may set parameters of the ion source device 60 so as to obtain an output with a predetermined increased intensity relative to the maximum intensity. In this case, even if the output of the particle beam B becomes unstable and the intensity of the particle beam B when being cut by the damper becomes lower than expected, the intensity can be prevented from becoming insufficient by increasing the intensity in advance.

[0057] The accelerator 3 may adjust the intensity of the particle beam B based on a data table prepared in advance. In this case, the accelerator 3 can appropriately adjust the amount of cutting by the adjustment unit 80 while reducing the load of calculation.

[0058] The irradiation unit 2 has a dose monitor 12 (detection unit) that detects the intensity of the particle beam B, and 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 that planned, the amount of cutting by the adjustment unit 80 can be appropriately controlled based on the detection result of the dose monitor 12.

[0059] The accelerator 3 according to one aspect of this embodiment is an accelerator 3 that virtually divides an irradiated object into a plurality of layers and generates a particle beam B for irradiating each layer by a scanning method, and is equipped with an ion source device 60 that generates particles in an acceleration space, 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 based on the set parameters.

[0060] According to this accelerator 3, it is possible to obtain the same functions and effects as those of the above-mentioned particle beam therapy system 1.

[0061] The present invention is not limited to the above-described embodiments.

[0062] For example, the parameters of the ion source device do not have to be set for each individual layer, but one parameter may be set collectively for a plurality of layers.

[0063] In Figs. 4 and 5, a cyclotron is shown as an example of the accelerator, but the configuration of the present invention may be adopted for various accelerators such as a synchrocyclotron or a linear accelerator (linac). [Explanation of symbols]

[0064] 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.

Claims

1. A particle beam therapy apparatus for irradiating a particle beam to an irradiation target, comprising: an accelerator that generates the particle beam in an acceleration space; an irradiation unit that virtually divides the irradiated object into a plurality of layers and irradiates each layer with the particle beam while scanning the layer with a scanning electromagnet; The accelerator comprises: a particle generator that generates the particles to be accelerated in the acceleration space by using a parameter based on a maximum intensity for at least one layer of the irradiated object; and an adjustment unit that adjusts an intensity of the particle beam by bending the particle beam with a deflector in the acceleration space, shielding a part of the particle beam with a damper, and allowing another part to pass through, thereby reducing the intensity of the particle beam.

2. The particle beam therapy system according to claim 1 , wherein the accelerator sets parameters of the particle generator so as to obtain an output having an intensity increased by a predetermined amount relative to the maximum intensity.

3. The particle beam therapy system according to claim 1 , wherein the accelerator adjusts an intensity of the particle beam based on a data table prepared in advance.

4. the irradiation unit has a detection unit that detects the intensity of the particle beam, 4. The particle beam therapy device according to claim 1, wherein the accelerator adjusts an intensity of the particle beam by feeding back a detection result of the detection unit.

5. An accelerator that virtually divides an irradiated object into a plurality of layers and generates a particle beam for irradiating each layer by a scanning method, a particle generator that generates the particles to be accelerated in an acceleration space by using a parameter based on a maximum intensity for at least one layer of the irradiated object; an adjustment unit that adjusts the intensity of the particle beam in the acceleration space by bending the particle beam with a deflector, blocking part of the particle beam with a damper, and allowing other parts to pass, thereby shaving off the particle beam; and an accelerator.

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