TW201943435A - Charged particle beam therapy device capable of stabilizing intensity of charged particle beam - Google Patents

Abstract

The present invention provides a charged particle beam therapy device capable of stabilizing the intensity of charged particle beam. The charged particle beam therapy device (1) of the present invention comprises: an ion source (10) for generating charged particles; an accelerator (3) for accelerating charged particles generated by the ion source (100) and emitting charged particle beam (B); an irradiation portion (2) for irradiating the charged particle beam (B) to the tumor of a patient (15); and a control portion (7) for controlling the ion source (10). The control portion (7) may memorize the operation parameters of the ion source (10) when the irradiation of the charged particle beam (B) to the tumor of the patient (15) is interrupted; and, when re-starting the irradiation of the charged particle beam (B) to the tumor of the patient (15), the control portion (7) may enable the ion source (10) operating according to the memorized operation parameters.

Description

Charged particle beam therapy device

This application claims priority based on Japanese Patent Application No. 2017-048881 filed on March 14, 2017. The entire contents of this application are incorporated herein by reference. The present invention relates to a charged particle beam therapy device.

Conventionally, there is known a charged particle beam treatment apparatus that performs treatment by irradiating an affected part of a patient with a charged particle beam. Patent Document 1 describes a charged particle beam generating device that scans a charged particle beam generated in an ion source and emitted from an accelerator using a scanning electromagnet and then irradiates a patient's affected part. (Prior Art Document) (Patent Document) Patent Document 1: Japanese Patent Application Laid-Open No. 2002-143328

(Problems to be Solved by the Present Invention) The position of an affected part irradiated with a charged particle beam may change depending on the patient's breathing. Therefore, in order to prevent the charged particle beam from being irradiated to a part other than the affected part, a method of irradiating the charged particle beam only at a specific timing of breathing may be used. However, in this method, while the irradiation of the charged particle beam to the affected part is stopped, the state of the interior of the accelerator (especially, the ion source) may change, and the intensity of the charged particle beam emitted from the accelerator may change when the irradiation is restarted. Unstable (strength overshoot). Therefore, a desired dose distribution cannot be obtained, and there is a possibility that the charged particle beam cannot be irradiated according to the treatment plan. The present invention was made in order to solve the above-mentioned problems, and an object thereof is to provide a charged particle beam therapy device capable of stabilizing the intensity of a charged particle beam. (Means to solve the problem) A charged particle beam therapy device according to one aspect of the present invention includes: an ion source that generates charged particles; an accelerator that accelerates the charged particles generated in the ion source and emits a charged particle beam; an irradiation unit, Irradiate the charged particle beam to the irradiated body; and the control unit controls the ion source, the control unit memorizes the operating parameter of the ion source when the irradiated body is irradiated with the charged particle beam, and restarts irradiation of the charged particle beam to the irradiated body The control unit makes the ion source work according to the memorized operating parameters.的 The control unit of the charged particle beam therapy device memorizes the operating parameters of the ion source when the charged particle beam is irradiated to the irradiated body. In addition, when the irradiation of the charged particle beam to the irradiated body is restarted, the control unit operates the ion source according to the memorized operating parameters. Thereby, while the irradiation of the charged particle beam is interrupted, even if the state of the ion source changes, the ion source can be controlled to have the same operating parameters as before the irradiation of the charged particle beam is interrupted. Therefore, it is possible to suppress the overshoot of the intensity of the charged particle beam and stabilize the intensity of the charged particle beam. The charged particle beam therapy device of the first aspect further includes an intensity measurement section that measures the intensity of the charged particle beam emitted from the accelerator, and the control section can also control the operation of the ion source based on the intensity of the charged particle beam measured by the intensity measurement section. According to this configuration, since the ion source can be controlled according to the intensity of the emitted charged particle beam, the intensity of the charged particle beam can be stabilized more effectively. (1) In a charged particle beam therapy apparatus of one form, the irradiation section may also continuously irradiate the charged particle beam along a preset track. According to this configuration, even when a so-called line scanning method that is susceptible to changes in the intensity of the charged particle beam is used, the intensity of the charged particle beam can be stabilized. (Effects of the Invention) According to the present invention, there is provided a charged particle beam treatment device capable of stabilizing the intensity of a charged particle beam.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In addition, in each drawing, the same or equivalent parts are denoted by the same reference numerals, and repeated descriptions are omitted. FIG. 1 is a diagram schematically showing a configuration of a charged particle beam therapy apparatus according to an embodiment. The charged particle beam treatment device 1 shown in FIG. 1 is a device used for cancer treatment and the like based on radiation therapy, and includes: an ion source 10 to generate charged particles; and an accelerator 3 to charge the particles generated in the ion source 10. Accelerating and emitting a charged particle beam; an irradiating unit 2 irradiates a charged particle beam to a tumor (irradiated body) of a patient 15; and a control unit 7 that controls the entire charged particle beam treatment apparatus 1. In addition, the charged particle beam treatment device 1 includes a beam transmission line 41 that transmits the charged particle beam emitted from the accelerator 3 to the irradiation unit 2; an intensity measuring unit 20 that measures the intensity of the charged particle beam emitted from the accelerator 3; and a respiratory synchronization system 40. The breathing of the patient 15 is detected; and the rotating support 5 is arranged to surround the treatment table 4. The irradiation unit 2 is attached to the rotating bracket 5. The control unit 7 includes a memory unit 60 that stores operating parameters of the ion source 10. FIG. 2 is a schematic configuration diagram of an irradiation unit and a control unit of the charged particle beam treatment apparatus of FIG. 1. In the following description, the terms "X direction", "Y direction", and "Z direction" are used for description. The “Z direction” means a direction in which the base axis AX of the charged particle beam B extends, and a depth direction of the irradiation of the charged particle beam B. The “base axis AX” refers to an irradiation axis of the charged particle beam B when it is not changed by a scanning electromagnet 6 described later. FIG. 2 shows a case where the charged particle beam B is irradiated along the base axis AX. "X direction" means a direction in a plane orthogonal to the Z direction. The "Y direction" means a direction orthogonal to the X direction in a plane orthogonal to the Z direction. First, referring to FIG. 1 and FIG. 2, a schematic configuration of a charged particle beam treatment apparatus 1 according to this embodiment will be described. The charged particle beam treatment device 1 is an irradiation device related to a scanning method. In addition, the scanning method is not particularly limited, and line scanning, raster scanning, and dot scanning can also be used. As shown in FIG. 2, the charged particle beam treatment apparatus 1 includes an accelerator 3, an irradiation unit 2, a beam transmission line 41, and a control unit 7. The accelerator 3 is a device that accelerates the charged particles generated in the ion source 10 and emits the charged particle beam B. Examples of the accelerator 3 include a gyro accelerator, a synchro accelerator, a synchro accelerator, and a linear accelerator. The accelerator 3 is connected to the control unit 7 and its operation is controlled by the control unit 7, thereby controlling the intensity of the emitted charged particle beam B. The charged particle beam B generated in the accelerator 3 is transmitted to the irradiation nozzle 9 through the beam transmission line 41. The beam transmission line 41 connects the accelerator 3 and the irradiation unit 2, and transmits a charged particle beam emitted from the accelerator 3 to the irradiation unit 2. In the present embodiment, the ion source 10 is provided outside the accelerator 3. However, the ion source 10 may be provided inside the accelerator 3. The charged particle beam therapy device 1 further includes a beam selector 16 provided in the accelerator 3 and cutting off the charged particle beam B emitted from the ion source 10. The beam selector 16 deviates from the acceleration orbit by biasing the charged particle beam B, and cuts off the charged particle beam B. In the operating state (ON) of the beam selector 16, the charged particle beam B emitted from the ion source 10 is cut off and is not emitted from the accelerator 3. When the beam selector 16 is stopped (OFF), the charged particle beam B emitted from the ion source 10 is emitted from the accelerator 3 without being cut off. The operating state and stopping state of the beam selector 16 are switched by a beam selector switch (not shown). In addition, as a method for switching the irradiation and non-irradiation of the charged particle beam, a member other than the beam selector may be used. For example, a shutter may be provided in the beam transmission line 41, and the shutter may be used to cut off the charged particle beam B. In this case, the shutter is intruded into the acceleration orbit of the charged particle beam B, and the charged particle beam B is cut off. Alternatively, the charged particle beam B may be emitted from the accelerator 3 only when the charged particle beam B is irradiated with a polarizing plate (electromagnet) provided in the accelerator 3. In addition, the charged particle beam B may be interrupted by stopping the power source of the ion source 10. The irradiation unit 2 is a person who irradiates a charged particle beam B to a tumor (irradiated body) 14 in a patient 15. The charged particle beam B refers to a person who accelerates charged particles at high speed, and examples thereof include a proton beam, a heavy particle (heavy ion) beam, and an electron beam. Specifically, the irradiation unit 2 is a device for irradiating the tumor 14 with a charged particle beam B. The charged particle beam B is emitted from an accelerator 3 that accelerates charged particles generated in an ion source (not shown) and uses the beam. The transmission line 41 transmits. The irradiation unit 2 includes a scanning electromagnet (scanning unit) 6, a quadrupole electromagnet 8, a profile monitor 11, a dose monitor 12, a flatness monitor 13a, 13b, and an energy reducer 30. The scanning electromagnet 6, the monitors 11, 12, 13a, 13b, the quadrupole electromagnet 8 and the energy reducer 30 are housed in the irradiation nozzle 9. The scanning electromagnet 6 includes an X-direction scanning electromagnet 6a and a Y-direction scanning electromagnet 6b. The X-direction scanning electromagnet 6a and the Y-direction scanning electromagnet 6b are each composed of a pair of electromagnets, and the magnetic field between the pair of electromagnets is changed in accordance with the current supplied from the control unit 7, and the scanning is performed between the electromagnets. Charged particle beam B. The X-direction scanning electromagnet 6a scans the charged particle beam B in the X direction, and the Y-direction scanning electromagnet 6b scans the charged particle beam B in the Y direction. The scanning electromagnets 6 are arranged on the base axis AX in this order on the downstream side of the charged particle beam B than the accelerator 3. The quadrupole electromagnet 8 includes an X-direction quadrupole electromagnet 8a and a Y-direction quadrupole electromagnet 8b. The X-direction quadrupole electromagnet 8 a and the Y-direction quadrupole electromagnet 8 b reduce the charged particle beam B according to a current supplied from the control unit 7 and converge the charged particle beam B. The X-direction quadrupole electromagnet 8a converges the charged particle beam B in the X direction, and the Y-direction quadrupole electromagnet 8b converges the charged particle beam B in the Y direction. By changing the current supplied to the quadrupole electromagnet 8 to change the reduction amount (convergence amount), the beam size of the charged particle beam B can be changed. The four-pole electromagnet 8 is arranged between the accelerator 3 and the scanning electromagnet 6 on the base axis AX in this order. The beam size refers to the size of the charged particle beam B on the XY plane. The beam shape refers to the shape of the charged particle beam B on the XY plane. For alignment during initial setting, the profile monitor 11 detects the beam shape and position of the charged particle beam B. The section monitor 11 is arranged between the quadrupole electromagnet 8 and the scanning electromagnet 6 on the base axis AX. The dose monitor 12 detects the intensity of the charged particle beam B, and sends a signal to the intensity measurement unit 20. The dose monitor 12 is disposed on the base axis AX on the downstream side of the scanning electromagnet 6. The flatness monitors 13a and 13b detect and monitor the beam shape and position of the charged particle beam B. The flatness monitors 13 a and 13 b are arranged on the base axis AX on the downstream side of the charged particle beam B than the dose monitor 12. Each of the monitors 11, 12, 13 a, and 13 b outputs the detected detection result to the control unit 7. The energy reducer 30 reduces the energy of the charged particle beam B passing therethrough to perform fine adjustment of the energy of the charged particle beam B. In the present embodiment, the energy reducer 30 is provided at the front end portion 9 a of the irradiation nozzle 9. The front end portion 9 a of the irradiation nozzle 9 refers to an end portion on the downstream side of the charged particle beam B. The energy reducer 30 in the irradiation nozzle 9 can also be omitted. The control unit 7 is configured by, for example, a CPU, a ROM, a RAM, and the like. The control unit 7 controls the accelerator 3, the scanning electromagnet 6, and the quadrupole electromagnet 8 based on the detection results output from the monitors 11, 12, 13a, and 13b. Further, in the present embodiment, the control unit 7 feeds back the detection results of the monitors 11, 12, 13a, 13b, and controls the quadrupole electromagnet 8 so that the beam size of the charged particle beam B becomes constant. In addition, the control unit 7 controls the operation of the ion source 10 based on the intensity of the charged particle beam B measured by the intensity measurement unit 20 so that the output of the ion source 10 becomes constant. The control unit 7 of the charged particle beam treatment apparatus 1 is connected to a treatment planning apparatus 100 that performs a treatment plan of the charged particle beam treatment apparatus. The treatment planning device 100 measures the tumor 14 of the patient 15 using CT or the like before treatment, and plans the dose distribution (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 table for the tumor 14. The treatment planning device 100 sends the created treatment plan to the control unit 7. When irradiation with a charged particle beam by a scanning method is performed, the tumor 14 is virtually divided into a plurality of layers in the Z direction, and the charged particle beam is scanned and irradiated on one layer. Then, after the irradiation of the charged particle beam of the one layer is completed, the irradiation of the charged particle beam of the next lower layer is performed. With the charged particle beam therapy device 1 shown in FIG. 2, when the charged particle beam B is irradiated by the scanning method, the quadrupole electromagnet 8 is set to the ON state so that the charged particle beam B passing therethrough is turned on. convergence. Next, ions are generated in the ion source 10. The ions generated in the ion source 10 are accelerated inside the accelerator 3 and emitted from the accelerator 3 as a charged particle beam B. The emitted charged particle beam B is scanned under the control of the scanning electromagnet 6. As a result, the charged particle beam B scans and irradiates the tumor 14 in the irradiation range of a layer set in the Z direction. When the irradiation to one layer is completed, the charged particle beam B is irradiated to the next layer. Referring to FIGS. 3 (a) and 3 (b), the image of the charged particle beam irradiation of the scanning electromagnet 6 according to the control of the control unit 7 will be described. Fig. 3 (a) shows an irradiated body virtually divided into a plurality of layers in the depth direction, and Fig. 3 (b) shows a scanned image of a charged particle beam of one layer viewed from the depth direction. As shown in FIG. 3 (a), the irradiated body is virtually divided into a plurality of layers in the depth direction of the irradiation. In this example, the deeper (longer range of the charged particle beam B) layers are sequentially virtualized. The ground is divided into layers L ₁ , L ₂ , ..., layer L _n-1 , layer L _n , layer L _{n + 1} , ... layer L _N-1 and layer L _N , that is, it is virtually divided into N layers. . As shown in FIG. 3 (b), the charged particle beam B irradiates a plurality of irradiation points of the layer Ln while drawing the beam track TL. That is, the charged particle beam B controlled by the control unit 7 moves on the beam track TL. Next, referring to FIG. 1 again, the respiratory synchronization system 40 and the control unit 7 will be described in detail. The breathing synchronization system 40 uses a sensor to detect the breathing of the patient 15 and generates a gate signal synchronized with the breathing of the patient 15. The gate signal can be generated, for example, by radiating laser light to the abdomen of the patient 15 and detecting a change in the expansion of the abdomen. The gate signal generated in the respiratory synchronization system 40 is output to the timing system 50. The timing system 50 determines whether the charged particle beam B should be irradiated based on the gate signal, and generates a pulse signal indicating the timing of irradiating the charged particle beam B. The pulse signal generated in the timing system 50 is output to the control unit 7. The control unit 7 switches the operating state and the stopped state of the beam selector 16 based on the pulse signal. This makes it possible to switch the irradiation state of the charged particle beam B to the tumor of the patient 15 and the interruption state of the irradiation of the charged particle beam B to the tumor of the patient 15 according to the breathing of the patient 15. Therefore, in order to suppress irradiation of the charged particle beam B to a portion other than the tumor, the charged particle beam B can be irradiated only at a specific timing of respiration. The memory unit 60 of the control unit 7 memorizes the operation parameters of the ion source 10 when the irradiation of the charged particle beam B to the tumor of the patient 15 is interrupted. When the irradiation of the charged particle beam B to the tumor of the patient 15 is resumed, the control unit 7 operates the ion source 10 using the operating parameters memorized by the memory unit 60. Examples of the operation parameters of the ion source 10 include a current and a voltage of an arc generated in a chimney of the ion source 10, and a current and a voltage flowing through a filament in the chimney. In the present embodiment, the memory unit 60 is provided outside the control unit 7, but the memory unit 60 may be provided integrally with the control unit 7. Next, an operation of the charged particle beam treatment apparatus 1 according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram for explaining the operation of the charged particle beam therapy device of the comparative example. FIG. 5 is a diagram for explaining the operation of the charged particle beam therapeutic apparatus according to this embodiment. (A), (b), and (c) of FIG. 4 and FIG. 5 respectively show the intensity of the charged particle beam, the intensity of the output of the ion source, and the timing signals. In the charged particle beam treatment device of the comparative example, initial parameters are set for the ion source, and feedback control is performed according to the intensity of the charged particle beam so that the output of the ion source is constant during irradiation of the charged particle beam on the tumor of the patient. However, since a dose monitor for detecting the intensity of the charged particle beam is provided in the irradiation section, the charged particle beam cannot be detected by the dose monitor while the irradiation of the charged particle beam is stopped. Therefore, during the period in which the irradiation of the charged particle beam is stopped, the feedback control is not performed, and the timing T of the irradiation of the charged particle beam is resumed, and the initial parameters are set again for the ion source. Therefore, as shown in FIG. 4 (b), the output of the ion source after timing T becomes unstable. As a result, as shown in FIG. 4 (a), the intensity of the charged particle beam may become unstable with respect to a desired intensity A, such as an intensity overshoot of the charged particle beam. On the other hand, in the charged particle beam therapy device 1 of this embodiment, the memory unit 60 of the control unit 7 memorizes the operating parameters of the ion source 10 when the irradiation of the charged particle beam B is interrupted, and restarts the irradiation of the charged particle beam B. At this time, the control unit 7 uses the operation parameters memorized by the memory unit 60 to make the ion source 10 work. Therefore, when the irradiation is restarted, the operating state of the ion source 10 is close to the state immediately before the stop. Therefore, as shown in FIG. 5 (b), the ion source 10 after the timing T of restarting the irradiation of the charged particle beam B can be realized. Output stabilization. In addition, the output of the ion source 10 after the timing T can be made close to the output of the ion source 10 before the irradiation of the charged particle beam B is interrupted. Therefore, as shown in FIG. 5 (a), the intensity of the charged particle beam B can be controlled to a value close to the desired intensity A, and stabilization can be achieved. As described above, the memory unit 60 of the control unit 7 of the charged particle beam therapy apparatus 1 memorizes the operating parameters of the ion source 10 when the irradiation of the charged particle beam B to the tumor (irradiated body) of the patient 15 is interrupted. When the irradiation of the charged particle beam B to the tumor (irradiated body) of the patient 15 is resumed (timing T), the control unit 7 uses the operation parameters memorized by the memory unit 60 to operate the ion source 10. Thereby, even when the state of the ion source 10 is changed during the interrupted irradiation of the charged particle beam B, the ion source 10 can be controlled to have the same operating parameters as before the irradiation of the charged particle beam B is interrupted. That is, when the irradiation is restarted, the operating state of the ion source 10 can be set to a state close to immediately before stopping. Therefore, it is possible to suppress overshoot and the like of the intensity of the charged particle beam B, thereby achieving stabilization of the intensity of the charged particle beam B. The charged particle beam therapy device 1 further includes an intensity measurement unit 20 that measures the intensity of the charged particle beam B emitted from the accelerator 3, and the control unit 7 controls the ion source based on the intensity of the charged particle beam B measured by the intensity measurement unit 20. 10 moves. Thereby, since the ion source 10 can be controlled according to the intensity of the emitted charged particle beam B, the intensity of the charged particle beam B can be stabilized more effectively. Further, in the charged particle beam treatment apparatus 1, the irradiation unit 2 continuously irradiates the charged particle beam B in accordance with a beam track TL set in advance. As described above, even when the so-called line scanning method that is easily affected by the change in the intensity of the charged particle beam B is used, the intensity of the charged particle beam B can be stabilized. As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various deformation | transformation can be employ | adopted. For example, in the above-mentioned embodiment, the irradiation unit 2 irradiates the charged particle beam B using a so-called line scanning method, but the irradiation unit 2 may irradiate the charged particle beam B using another irradiation method such as a so-called dot scanning method. Furthermore, in the above-mentioned embodiment, the intensity measurement unit 20 measures the intensity of the charged particle beam B based on the value measured by the dose monitor 12, but the position where the intensity of the charged particle beam B is measured is not particularly limited. For example, the intensity measurement unit 20 may measure the intensity of the charged particle beam B based on a value measured in the middle of the beam transmission line 41. Furthermore, in the above-mentioned embodiment, the case where the irradiation of the charged particle beam B is interrupted based on the breathing of the patient has been described as an example, but the structure of interrupting the irradiation of the charged particle beam B is not limited to the above. For example, it also includes a case where the irradiation of the charged particle beam B is stopped when a malfunction of the device or the like is detected in the charged particle beam treatment device 1. Furthermore, in the above embodiment, when the irradiation of the charged particle beam B to the tumor (irradiated body) of the patient 15 is resumed (timing T), the control unit 7 uses the operating parameters memorized by the memory unit 60 to operate the ion source 10, However, it is not limited to those that strictly coincide with the motion parameters memorized in the memory unit 60. For example, the ion source may be operated by using a value obtained by adding or subtracting a preset value of the operation parameter stored in the storage unit 60 or a value obtained by multiplying the operation parameter stored in the storage unit 60 by a predetermined coefficient. That is, when the irradiation with the charged particle beam B to the tumor (irradiated body) of the patient 15 is resumed (timing T), the control unit 7 operates the ion source 10 based on the operation parameters memorized by the memory unit 60.

1‧‧‧ Charged particle beam treatment device

2‧‧‧ Irradiation Department

3‧‧‧ accelerator

4‧‧‧Treatment Table

5‧‧‧ rotating bracket

6‧‧‧scanning electromagnet

7‧‧‧Control Department

8‧‧‧ Quadrupole Electromagnet

9‧‧‧ irradiation nozzle

10‧‧‧ ion source

11‧‧‧ Section Monitor

12‧‧‧ Dose Monitor

15‧‧‧patient

16‧‧‧ Beam Selector

20‧‧‧Intensity Measurement Department

30‧‧‧ Energy Reducer

40‧‧‧Respiratory synchronization system

41‧‧‧ Beam Transmission Line

50‧‧‧ timing system

60‧‧‧Memory Department

100‧‧‧ treatment plan device

B‧‧‧ charged particle beam

TL‧‧‧ Beam Orbit

FIG. 1 is a diagram schematically showing a charged particle beam therapeutic apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of an irradiation unit and a control unit of the charged particle beam treatment apparatus of FIG. 1. Fig. 3 is a diagram showing layers set for a tumor. FIG. 4 is a diagram for explaining the operation of the charged particle beam therapy device of the comparative example. FIG. 5 is a diagram for explaining the operation of the charged particle beam therapeutic apparatus according to this embodiment.

Claims (3)

A charged particle beam treatment device, comprising: a scandium ion source that generates charged particles; a scan accelerator that accelerates the charged particles generated in the ion source and emits a charged particle beam; a scan unit that irradiates the subject with the radiation A charged particle beam; and a control unit that controls the ion source, the control unit memorizes an operation parameter of the ion source when the irradiation of the charged particle beam with the irradiated body is interrupted, restarts irradiation of the charged particle with the irradiated body When the beam is emitted, the control unit makes the ion source operate according to the memorized operation parameters. The charged particle beam treatment device according to item 1 of the scope of the patent application, further comprising: an intensity measurement section that measures the intensity of the charged particle beam emitted from the accelerator; the control section according to the foregoing measured by the intensity measurement section The intensity of the charged particle beam controls the operation of the ion source. The charged particle beam treatment device according to item 1 or 2 of the scope of the patent application, wherein: the irradiation section continuously irradiates the charged particle beam along a preset track.