Charged particle beam therapy equipment

Abstract

To provide a charged particle beam treatment device capable of improving irradiation accuracy of a charged particle beam to an irradiated body.SOLUTION: A charged particle beam treatment device 1 includes a rotary gantry 5 that supports an irradiation unit 2 in a rotatable manner. Positional relationships between an isocenter AC of a charged particle beam and a tumor 14 deviate from positional relationships between an isocenter ACX in design and the tumor 14. To cope with this, the charged particle beam treatment device 1 includes a treatment table 4 that can adjust relative positional relationships between the tumor 14 and the charged particle beam, and a controller 53 for acquiring a correction amount set according to a rotation angle of the rotary gantry 5, and correcting the position of the treatment table 4 by the correction amount. Since the controller 53 corrects the position of the treatment table 4 by the correction amount according to the rotation angle, the deviation in the positional relationships between the isocenter AC of the charged particle beam and the tumor 14 can be suppressed.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Conventionally, as a charged particle beam therapy device that performs treatment by irradiating an affected area of ​​a patient with a charged particle beam, for example, the device described in Patent Document 1 is known. In the charged particle beam irradiation device described in Patent Document 1, a charged particle beam is irradiated from an irradiation unit to treat the affected area of ​​a patient on a treatment table. [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, the quality of treatment improves if the object to be irradiated is irradiated with a charged particle beam with high accuracy, and therefore there is a demand for improving the accuracy of irradiation of the object to be irradiated with the charged particle beam.

[0005] The present invention has been made to solve such problems, and has an object to provide a charged particle beam therapy apparatus capable of improving the accuracy of irradiating a charged particle beam onto an object to be irradiated. [Means for solving the problem]

[0006] The charged particle beam therapy device of the present invention is a charged particle beam therapy device that irradiates a charged particle beam to an irradiated body, and is equipped with an irradiation unit that irradiates the charged particle beam, a rotating gantry that rotatably supports the irradiation unit, an adjustment unit that can adjust the relative positional relationship between the irradiated body and the charged particle beam, and a correction unit that acquires a correction amount set according to the rotation angle of the rotating gantry and corrects the position of the adjustment unit using the correction amount.

[0007] The charged particle beam therapy device of the present invention has a rotating gantry that rotatably supports the irradiation unit. Therefore, the irradiation unit irradiates the irradiated object with the charged particle beam from an angle corresponding to the rotation angle of the rotating gantry. Here, the rotating gantry and the irradiation unit may bend. When such bending occurs, the actual isocenter of the charged particle beam may deviate from the designed position. In this case, the positional relationship between the isocenter of the charged particle beam and the irradiated object deviates from the designed one. In response to this, the charged particle beam therapy device includes an adjustment unit that can adjust the relative positional relationship between the irradiated object and the charged particle beam, and a correction unit that acquires a correction amount set according to the rotation angle of the rotating gantry and corrects the position of the adjustment unit by the correction amount. Therefore, the correction unit corrects the position of the adjustment unit by the correction amount corresponding to the rotation angle, thereby suppressing the deviation of the positional relationship between the isocenter of the charged particle beam and the irradiated object. As a result, the irradiation accuracy of the charged particle beam to the irradiated object can be improved.

[0008] The adjustment unit may be configured with a mechanism capable of correcting a position shift of the isocenter of the charged particle beam. Thereby, the correction unit corrects the position of the adjustment unit, thereby making it possible to correct the position shift of the isocenter of the charged particle beam.

[0009] The correction unit may perform the correction using a correction amount based on a measurement result obtained in advance, which makes it possible to set an appropriate correction amount based on the actual measurement result.

[0010] The rotating gantry may have a cantilever structure. In this case, the deflection of the rotating gantry increases, and the amount of deviation of the isocenter of the charged particle beam increases, so that the effect of the correction by the correction unit becomes more pronounced. Effect of the Invention

[0011] According to the present invention, it is possible to provide a charged particle beam therapy apparatus capable of improving the accuracy of irradiating a subject with a charged particle beam. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram showing a charged 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 therapy apparatus of FIG. [Diagram 3] FIG. 3(a) is a schematic side view of the rotating gantry, and FIG. 3(b) is a schematic front view of the rotating gantry. [Figure 4] FIG. 2 is a perspective view showing a configuration in the vicinity of an irradiation unit. [Diagram 5] FIG. 13 is a conceptual diagram showing the amount of deviation of an isocenter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a charged 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.

[0014] 1 is a schematic diagram showing a charged particle beam therapy apparatus 1 according to one embodiment of the present invention. The charged particle beam therapy apparatus 1 is an apparatus used for cancer treatment by radiation therapy, etc. The charged particle beam therapy apparatus 1 includes an accelerator 3 that accelerates charged particles generated by an ion source device and emits the charged particle beam, an irradiation unit 2 that irradiates an irradiated body with the charged particle beam, and a beam transport line 21 that transports the charged particle beam emitted from the accelerator 3 to the irradiation unit 2.

[0015] The irradiation unit 2 is attached to a rotating gantry 5 provided so as to surround the treatment table 4. The irradiation unit 2 is rotatable around the treatment table 4 by the rotating gantry 5. The beam transport line 21 enters the rotating gantry 5 from the rear end side. Then, the beam transport line 21 changes the trajectory of the charged particle beam to the outer periphery side by a bending electromagnet 22, and then the trajectory of the charged particle beam is largely bent by a bending electromagnet 23 to enter the irradiation unit 2 from the outer periphery side.

[0016] FIG. 2 is a schematic diagram of the vicinity of the irradiation unit of the charged particle beam therapy device 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 a direction along the basic axis AX of the irradiation unit 2, and is the depth direction of irradiation with the charged particle beam B. The details of the "basic axis AX" will be described later. FIG. 2 shows a state in which the charged particle beam B is irradiated along the basic axis AX. The "X-axis direction" is a 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.

[0017] First, referring to FIG. 2, a schematic configuration of the charged particle beam therapy device 1 according to the present embodiment will be described. The charged particle beam therapy device 1 shown in FIG. 2 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. In addition, the charged particle beam therapy device 1 is not limited to an irradiation device related to a scanning method, and irradiation devices related to various irradiation methods such as a wobbler method and a stacked conformal method can be adopted. As shown in FIG. 2, the charged particle beam therapy device 1 includes an accelerator 3, an irradiation unit 2, a beam transport line 21, and a control unit 7.

[0018] The accelerator 3 is a device that accelerates charged particles and emits a charged particle beam B with a preset energy. Examples of the accelerator 3 include a cyclotron, a synchrocyclotron, and a linac. The beam transport line 21 transports the charged particle beam emitted from the accelerator 3 to the irradiation unit 2.

[0019] The irradiation unit 2 irradiates a tumor (subject) 14 in the body of a patient 15 with a charged particle beam B. The charged particle beam B is a particle having an electric charge that is accelerated to a high speed, and examples of the charged 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 a charged particle beam B that is 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 electromagnet 6, a dose monitor 12, position monitors 13a and 13b, a collimator 40, and a degrader 30. The scanning electromagnet 6, the monitors 12, 13a, and 13b, and the degrader 30 are housed in an irradiation nozzle 9 as a housing. In this way, the irradiation unit 2 is configured by housing each main component in the irradiation nozzle 9. In addition to the above-mentioned elements, a quadrupole electromagnet and a profile monitor may be provided upstream of the scanning electromagnet 6. In addition, the dose monitor 12, the position monitors 13a and 13b, and the degrader 30 may be omitted. The scanning electromagnet 6 includes an X-axis scanning electromagnet 6a and a Y-axis scanning electromagnet 6b. The scanning electromagnet 6 scans the charged particle beam B so that the charged particle beam B is irradiated along a scanning path planned in advance by the treatment planning device 100.

[0020] The control unit 7 is composed of, for example, a CPU, a ROM, and a RAM. The control unit 7 controls the accelerator 3, the scanning magnet 6, and the collimator driving unit 41 based on the detection results output from the monitors 12, 13a, and 13b. Furthermore, the control unit 7 can also control the rotating gantry 5 and the treatment table 4 (see FIG. 3). The control unit 7 may be composed of a combination of multiple arithmetic devices.

[0021] Furthermore, the control unit 7 of the charged particle beam therapy device 1 is connected to a treatment planning device 100 that performs a treatment plan for the charged particle beam therapy. The treatment planning device 100 measures the tumor 14 of the patient 15 by CT or the like before treatment, and plans a dose distribution (a dose distribution of the charged particle beam to be irradiated) at each position of the tumor 14. Specifically, the treatment planning device 100 creates a treatment plan map for the tumor 14. The treatment planning device 100 transmits the created treatment plan map to the control unit 7. In the treatment plan map created by the treatment planning device 100, it is planned what kind of scanning path the charged particle beam B will trace.

[0022] Next, the configuration of the charged particle beam therapy device 1 will be described in more detail with reference to Fig. 3 and Fig. 4. Fig. 3(a) is a schematic side view of the rotating gantry 5, and Fig. 3(b) is a schematic front view of the rotating gantry 5. Fig. 4 is a perspective view showing the configuration in the vicinity of the irradiation unit 2. Note that the positional relationship of each component of the charged particle beam therapy device 1 shown in Fig. 3 is assumed to be an ideal state in which no bending or the like occurs in each component. In other words, Fig. 3 shows the design positional relationship of each component.

[0023] As shown in Fig. 3(a), the rotating gantry 5 is rotated by a motor (not shown), and the rotation is stopped by a brake device (not shown). In the following description, the front side means the side of the rotating gantry 5 on which the treatment table 4 (see Fig. 4) is installed and which is open so that patients can enter and exit, and the rear side means the side behind that.

[0024] The rotating gantry 5 is rotatable and includes, in order from the front side, a first cylindrical portion 34, a cone portion 35, and a second cylindrical portion 36. The first cylindrical portion 34, the cone portion 35, and the second cylindrical portion 36 are arranged coaxially with respect to the center line CL and fixed to each other. The irradiation portion 2 is arranged on the inner surface of the first cylindrical portion 34 and faces the axial direction of the first cylindrical portion 34. The second cylindrical portion 36 has a smaller diameter than the first cylindrical portion 34, and the cone portion 35 is formed in a cone shape so as to connect the first cylindrical portion 34 and the second cylindrical portion 36. The first cylindrical portion 34 on which the irradiation portion 2 is provided is supported by a support mechanism (not shown) via the cone portion 35 and the second cylindrical portion 36 on the back side. On the other hand, the front side of the first cylindrical portion 34 is open, and no support mechanism for supporting a load is provided. Therefore, the rotating gantry 5 has a cantilever structure supported only on the back side.

[0025] In the designed positional relationship, the base axis AX of the charged particle beam intersects with the center line CL. The base axis AX of the charged particle beam intersects with the center line CL regardless of the angle from which the irradiation unit 2 irradiates the charged particle beam (FIG. 3(b)). The base axis AX is a virtual reference line that serves as a reference when the irradiation unit 2 irradiates the charged particle beam. When the treatment planning device 100 creates a scanning pattern when making a treatment plan, the treatment plan is also made based on the base axis AX. When setting layers in the scanning pattern, each layer is a plane perpendicular to the base axis AX. In addition, when setting the amount of movement in the X-axis direction and the amount of movement in the Y-axis direction, the position of the base axis AX is also used as a reference. The isocenter AC is the part where the charged particle beam is irradiated most intensively. In the designed positional relationship, the isocenter AC is located at the intersection of the base axis AX of the charged particle beam and the center line CL.

[0026] As shown in Fig. 4, the treatment table 4 includes a placement section 4a and a support mechanism 4b. The placement section 4a is composed of a plate-shaped member on which the patient 15 is placed. The support mechanism 4b is a mechanism that movably supports the placement section 4a. The support mechanism 4b can move the placement section 4a back and forth, left and right, and up and down. The treatment table 4 functions as an adjustment section that can adjust the relative positional relationship between the patient 15 and the charged particle beam.

[0027] The control unit 7 includes a control device 51 that controls the rotating gantry 5, a control device 52 that controls the treatment table 4, a controller 53 that operates the control devices 51 and 52, and a storage unit 54 that stores various information. The controller 53 outputs control signals based on set values ​​to the control devices 51 and 52 so that treatment is performed according to the treatment plan map created by the treatment planning device 100. As a result, the control device 51 controls the rotation of the rotating gantry 5 to position the irradiation unit 2 at an angle determined by the treatment plan. In addition, the control device 52 drives and controls the treatment table 4 to position the placement unit 4a at a position determined by the treatment plan.

[0028] Here, since each component of the charged particle beam therapy device 1 is a heavy member, bending may occur. In this case, the position of the isocenter AC deviates from the designed position. The treatment planning device 100 sets the position of the placement part 4a of the treatment table 4 based on the designed (ideal) isocenter position. Therefore, if the position of the isocenter AC deviates from the designed position, the positional relationship between the placement part 4a of the treatment table 4 and the actual isocenter AC will be displaced.

[0029] Specifically, the left diagram of FIG. 5(a) shows the design isocenter ACX when the irradiation unit 2 is arranged directly above (rotation angle = 0°), while the right diagram shows the position of the actual isocenter AC. As shown in the right diagram of FIG. 5(a), the weight of the irradiation unit 2 causes the rotating gantry 5 to bend downward, so that the actual isocenter AC is shifted downward from the position of the design isocenter ACX by a shift amount SL1. The left diagram of FIG. 5(b) shows the design isocenter ACX when the irradiation unit 2 is arranged diagonally (rotation angle = 315°), while the right diagram shows the position of the actual isocenter AC. As shown in the right diagram of FIG. 5(b), the deflection of the rotating gantry 5 and the deflection of the irradiation unit 2 itself causes the actual isocenter AC to be shifted diagonally downward from the position of the design isocenter ACX by a shift amount SL2. In the following description, when it is referred to as "positional deviation of isocenter AC," it means that the position of the actual isocenter AC is shifted from the position of the design isocenter ACX by a shift amount SL2. Furthermore, the magnitude of deviation of the actual isocenter AC from the design isocenter ACX may simply be referred to as the "amount of deviation."

[0030] For the above-mentioned positional deviation of the isocenter AC, the controller 53 obtains a correction amount set according to the rotation angle of the rotating gantry 5, and functions as a correction unit that corrects the position of the placement part 4a of the treatment table 4 by the correction amount. At this time, the treatment table 4 functions as a mechanism that can correct the positional deviation of the isocenter AC of the charged particle beam.

[0031] The controller 53 acquires information on the rotation angle from the control device 51. Then, the controller 53 reads out a database of the correction amount for each rotation angle from the storage unit 54, and consults the acquired rotation angle with the database. As a result, the controller 53 acquires the correction amount according to the rotation angle of the rotating gantry 5. Therefore, the controller 53 outputs the acquired correction amount to the control device 52. As a result, the control device 52 moves the support unit 4a of the treatment table 4 by the amount of the correction amount in addition to the set value based on the treatment plan map.

[0032] Specifically, as shown in the right diagram of FIG. 5(a), as the isocenter AC shifts downward by the shift amount SL1, the placement part 4a of the treatment table 4 moves downward from the designed position by the correction amount AL1. As a result, the relative positional relationship between the actual isocenter AC and the placement part 4a of the treatment table 4 becomes equal to the relative positional relationship between the designed isocenter ACX and the placement part 4a of the treatment table 4 shown in the left diagram of FIG. 5(a). Also, as shown in the right diagram of FIG. 5(b), as the isocenter AC shifts obliquely downward by the shift amount SL2, the placement part 4a of the treatment table 4 moves obliquely downward from the designed position by the correction amount AL2. As a result, the relative positional relationship between the actual isocenter AC and the placement part 4a of the treatment table 4 becomes equal to the relative positional relationship between the designed isocenter ACX and the placement part 4a of the treatment table 4 shown in the left diagram of FIG. 5(b).

[0033] Here, the database of the correction amount for each rotation angle stored in the storage unit 54 is created based on the measurement results obtained in advance. The correction amount is set based on the measurement results by measuring the deviation amount of the isocenter AC at a certain rotation angle. Such a correction amount is measured and set for each rotation angle. As a result, a database of the correction amount for each rotation angle is created and stored in the storage unit 54. Therefore, the controller 53 can perform correction using the correction amount based on the measurement results obtained in advance. Note that the deflection amount and the like of each component of the charged particle beam therapy device 1 may change due to long-term use. As a result, the deviation amount of the isocenter AC may also change over the years of use. Therefore, the correction amount may be updated by measuring the deviation amount again at the timing of a periodic inspection of the charged particle beam therapy device 1.

[0034] Here, an example of a method for measuring the amount of deviation of the isocenter AC will be described. The measurement is performed using a charged particle beam measuring device such as XRV-100 (manufactured by Logos Systems). First, the rotation angle of the rotating gantry 5 is set to a predetermined value. The sensor of the measuring device is placed on the placement part 4a of the treatment table 4. Next, the placement part 4a is moved to the initial position ((X, Y, Z): (0 mm, -480 mm, 23 mm)). Next, the center position of the sensor of the measuring device is imaged by a DR (Digital Radiography) device 60, and the placement part 4a is moved based on the imaged result to align the center position of the sensor of the measuring device with the DR center position. The DR center position corresponds to the isocenter position in design. Then, the charged particle beam measuring software is started, and the charged particle beam is irradiated with a predetermined measurement plan and settings. As a main setting, irradiation with wobbling is performed with an energy of 190 MeV. After the irradiation is completed, beam position data where the charged particle beam is irradiated most intensively is output from the measurement software. Based on this beam position data and the design isocenter position data, the amount of deviation of the isocenter AC at a given rotation angle can be obtained. Also, based on the amount of deviation, the amount of correction of the mounting part 4a is calculated. In this way, the amount of correction corresponding to the given rotation angle is obtained. By performing the same measurement for each rotation angle, a database of the amount of correction for each rotation angle can be created.

[0035] Next, the actions and effects of the charged particle beam therapy system 1 according to this embodiment will be described.

[0036] The charged particle beam therapy device 1 according to the present embodiment has a rotating gantry 5 that rotatably supports the irradiation unit 2. Therefore, the irradiation unit 2 irradiates the tumor 14 with the charged particle beam from an angle corresponding to the rotation angle of the rotating gantry 5. Here, the rotating gantry 5 and the irradiation unit 2 may bend. When such bending occurs, as shown in the right diagram of FIG. 5(a)(b), the actual isocenter AC of the charged particle beam may deviate from the position of the designed isocenter ACX. In this case, the positional relationship between the isocenter AC of the charged particle beam and the tumor 14 deviates from the positional relationship between the isocenter ACX of the charged particle beam and the tumor 14. In response to this, the charged particle beam therapy device 1 includes a treatment table 4 that can adjust the relative positional relationship between the tumor 14 and the charged particle beam, and a controller 53 that acquires a correction amount set according to the rotation angle of the rotating gantry 5 and corrects the position of the treatment table 4 according to the correction amount. Therefore, the controller 53 corrects the position of the treatment table 4 by a correction amount according to the rotation angle, thereby suppressing deviation in the positional relationship between the isocenter AC of the charged particle beam and the tumor 14. As a result, the irradiation accuracy of the charged particle beam to the tumor 14 can be improved.

[0037] The adjustment unit may be configured by a treatment table that is a mechanism capable of correcting the positional deviation of the isocenter AC of the charged particle beam. As a result, the controller 53 corrects the position of the treatment table 4, thereby correcting the positional deviation of the isocenter AC of the charged particle beam.

[0038] The controller 53 may perform the correction using a correction amount based on previously acquired measurement results, which makes it possible to set an appropriate correction amount based on the actual measurement results.

[0039] The rotating gantry 5 may have a cantilever structure. In this case, the deflection of the rotating gantry 5 increases, and the amount of deviation of the isocenter AC of the charged particle beam increases, so that the effect of correction by the controller 53 becomes more pronounced.

[0040] The present invention is not limited to the above-described embodiments.

[0041] In the above embodiment, the treatment table 4 is used as the adjustment unit. However, the adjustment unit is not particularly limited as long as it is a mechanism capable of adjusting the relative positional relationship between the irradiated body and the charged particle beam. For example, the irradiation unit may be used as the adjustment unit. In this case, the angle and range of the charged particle beam may be corrected in the irradiation unit 2 to eliminate the positional deviation of the isocenter AC.

[0042] Although the rotating gantry has the structure shown in the above embodiment, the structure of the rotating gantry is not particularly limited and may be changed as appropriate. Furthermore, the rotating gantry is not limited to a cantilever structure and may be a double-supported rotating gantry.

[0043] In addition, the method of measuring the positional deviation of the isocenter AC described in the above embodiment is merely an example, and other measurement methods may be adopted as long as they are measurable. In addition, the correction amount does not have to be based on actual measurement, and may be set using simulation results, etc. [Explanation of symbols]

[0044] 1...charged particle beam therapy device, 2...irradiation unit, 4...treatment table (adjustment unit), 5...rotating gantry, 14...tumor (irradiated object), 53...controller (correction unit).

Claims

1. A charged particle beam therapy apparatus for irradiating a target body with a charged particle beam, comprising: an irradiation unit that irradiates the charged particle beam; a rotating gantry that rotatably supports the irradiation unit; an adjustment unit capable of adjusting a relative positional relationship between the irradiation target and the charged particle beam; a correction unit that corrects the position of the adjustment unit based on a correction amount that is set according to a rotation angle of the rotating gantry, the correction unit corrects the adjustment unit by using the correction amount acquired by referring to a database created based on previously acquired measurement results and the rotation angle; A charged particle beam therapy device, wherein the measurement result is a deviation amount of an actually measured isocenter position from a designed isocenter at a certain rotation angle.

2. The charged particle beam therapy device according to claim 1 , wherein the adjustment unit is configured by a mechanism capable of correcting a positional deviation of an isocenter of the charged particle beam.

3. The charged particle beam therapy system according to claim 1 , wherein the rotating gantry has a cantilever structure.

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