JP6815231B2 - Charged particle beam therapy device - Google Patents

Description

The present invention relates to a charged particle beam therapy device.

Conventionally, a charged particle beam therapy device that treats an affected part of a patient by irradiating it with a charged particle beam is known. Patent Document 1 describes a charged particle beam generator that irradiates an affected area of a patient after scanning a charged particle beam emitted from an accelerator generated in an ion source with a scanning electromagnet.

JP-A-2002-143328

By the way, the position of the affected area irradiated with the charged particle beam may change in conjunction with the patient's respiration. Therefore, in order to suppress the irradiation of the charged particle beam to the portion other than the affected part, a method of irradiating the charged particle beam only at a specific timing of respiration may be used. However, in such a method, the state inside the accelerator (particularly the ion source) changes while the irradiation of the affected part with the charged particle beam is stopped, and the intensity of the charged particle beam emitted from the accelerator when the irradiation is resumed is increased. It may become unstable (strength overshoots). Therefore, it is possible that the desired dose distribution cannot be obtained and the irradiation of the charged particle beam does not meet the treatment plan.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a charged particle beam therapy apparatus capable of stabilizing the intensity of a charged particle beam.

The charged particle beam therapy apparatus according to one embodiment of the present invention is irradiated with 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, and a charged particle beam. It includes an irradiation unit that irradiates the body and a control unit that controls the ion source, and the control unit stores the operation parameters of the ion source when the irradiation of the charged particle beam to the irradiated object is interrupted, and the control unit. Operates the ion source with the stored operating parameters when resuming the irradiation of the irradiated object with the charged particle beam.

The control unit of this charged particle beam therapy device stores the operation parameters of the ion source when the irradiation of the irradiated object with the charged particle beam is interrupted. Then, the control unit operates the ion source with the stored operation parameters when resuming the irradiation of the irradiated body with the charged particle beam. As a result, even if the state of the ion source changes while the irradiation of the charged particle beam is interrupted, the ion source can be controlled to the same operating parameters as immediately before the irradiation of the charged particle beam is interrupted. Therefore, it is possible to suppress overshoot of the intensity of the charged particle beam and stabilize the intensity of the charged particle beam.

The charged particle beam therapy device according to one form further includes an intensity measuring unit for measuring the intensity of the charged particle beam emitted from the accelerator, and the control unit is based on the intensity of the charged particle beam measured by the intensity measuring unit. The operation of the ion source may be controlled. According to this configuration, since the ion source can be controlled based on the intensity of the emitted charged particle beam, it is possible to more effectively stabilize the intensity of the charged particle beam.

In the charged particle beam therapy apparatus according to one embodiment, the irradiation unit may continuously irradiate the charged particle beam according to a predetermined trajectory. According to this configuration, it is possible to stabilize the intensity of the charged particle beam even when the so-called line scanning method, which is easily affected by the change in the intensity of the charged particle beam, is used.

According to the present invention, there is provided a charged particle beam therapy device capable of stabilizing the intensity of a charged particle beam.

It is a figure which shows schematicly the charged particle beam therapy apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the irradiation part and the control part of the charged particle beam therapy apparatus of FIG. It is a figure which shows the layer set for a tumor. It is a figure for demonstrating the operation of the charged particle beam therapy apparatus which concerns on a comparative example. It is a figure for demonstrating the operation of the charged particle beam therapy apparatus which concerns on this embodiment.

Hereinafter, various embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be 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 therapy device 1 shown in FIG. 1 is a device used for cancer treatment or the like by a radiation therapy method, and accelerates an ion source 10 that generates charged particles and a charged particle that is generated in the ion source 10. An accelerator 3 that emits a charged particle beam, an irradiation unit 2 that irradiates the tumor (irradiated body) of the patient 15 with the charged particle beam, and a control unit 7 that controls the entire charged particle beam therapy device 1 are provided. ing. Further, the charged particle beam therapy device 1 includes a beam transport line 41 that transports the charged particle beam emitted from the accelerator 3 to the irradiation unit 2, and an intensity measuring unit 20 that measures the intensity of the charged particle beam emitted from the accelerator 3. A respiratory synchronization system 40 for detecting the breathing of the patient 15 and a rotating gantry 5 provided so as to surround the treatment table 4 are provided. The irradiation unit 2 is attached to the rotating gantry 5. The control unit 7 has a storage unit 60 that stores the 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 therapy apparatus of FIG. In the following description, the terms "X direction", "Y direction", and "Z direction" will be used. The "Z direction" is a direction in which the base axis AX of the charged particle beam B extends, and is a depth direction of irradiation of the charged particle beam B. The "base axis AX" is the irradiation axis of the charged particle beam B when it is not changed by the scanning electromagnet 6 described later. FIG. 2 shows how the charged particle beam B is irradiated along the base axis AX. The "X direction" is one direction in a plane orthogonal to the Z direction. The "Y direction" is a direction orthogonal to the X direction in a plane orthogonal to the Z direction.

First, a schematic configuration of the charged particle beam therapy apparatus 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. The charged particle beam therapy device 1 is an irradiation device according to a scanning method. The scanning method is not particularly limited, and line scanning, raster scanning, spot scanning, or the like may 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 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 a charged particle beam B. Examples of the accelerator 3 include a cyclotron, a synchrotron, a synchrotron, a linac, and the like. The accelerator 3 is connected to the control unit 7, and the operation of the accelerator 3 is controlled by the control unit 7, so that the intensity of the emitted charged particle beam B is controlled. The charged particle beam B generated in the accelerator 3 is transported to the irradiation nozzle 9 by the beam transport line 41. The beam transport line 41 connects the accelerator 3 and the irradiation unit 2, and transports the 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, but the ion source 10 may be provided inside the accelerator 3.

The charged particle beam therapy device 1 is further provided with a beam chopper 16 which is arranged in the accelerator 3 and blocks the charged particle beam B emitted from the ion source 10. The beam chopper 16 blocks the charged particle beam B by deflecting the charged particle beam B and removing it from the acceleration orbit. In the operating state (ON) of the beam chopper 16, the charged particle beam B emitted from the ion source 10 is cut off, and the charged particle beam B is not emitted from the accelerator 3. In the stopped state (OFF) of the beam chopper 16, 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 the stopped state of the beam chopper 16 can be switched by a beam chopper switch (not shown). A device other than the beam chopper may be used as a means for switching between irradiation and non-irradiation of charged particle beams. For example, a shutter may be provided in the beam transport line 41, and the charged particle beam B may be blocked by the shutter. In this case, the charged particle beam B is blocked by invading the shutter into the acceleration orbit of the charged particle beam B. Alternatively, the charged particle beam B may be emitted from the accelerator 3 only when the charged particle beam B is irradiated using the deflector (electromagnet) provided in the accelerator 3. Further, the charged particle beam B may be cut off by stopping the power supply of the ion source 10.

The irradiation unit 2 irradiates the tumor (irradiated body) 14 in the body of the patient 15 with the charged particle beam B. The charged particle beam B is a high-speed acceleration of a charged particle, 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 that irradiates the tumor 14 with a charged 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 41. .. The irradiation unit 2 includes a scanning electromagnet (scanning unit) 6, a quadrupole electromagnet 8, a profile monitor 11, a dose monitor 12, flatness monitors 13a and 13b, and a degrader 30. The scanning electromagnet 6, the monitors 11, 12, 13a, 13b, the quadrupole electromagnet 8, and the degrader 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 according to the current supplied from the control unit 7, and charged particles passing between the electromagnets. Scan line 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. These scanning electromagnets 6 are arranged on the base axis AX in this order on the downstream side of the charged particle beam B with respect to 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 8a and the Y-direction quadrupole electromagnet 8b narrow and converge the charged particle beam B according to the current supplied from the control unit 7. 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. The beam size of the charged particle beam B can be changed by changing the amount of aperture (convergence amount) by changing the current supplied to the quadrupole electromagnet 8. The quadrupole electromagnet 8 is arranged on the base axis AX between the accelerator 3 and the scanning electromagnet 6 in this order. The beam size is the size of the charged particle beam B in the XY plane. The beam shape is the shape of the charged particle beam B in the XY plane.

The profile monitor 11 detects the beam shape and position of the charged particle beam B for alignment at the time of initial setting. The profile monitor 11 is arranged on the base axis AX between the quadrupole electromagnet 8 and the scanning electromagnet 6. The dose monitor 12 detects the intensity of the charged particle beam B and transmits a signal to the intensity measuring unit 20. The dose monitor 12 is arranged on the base axis AX and downstream 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 13a and 13b are arranged on the base axis AX and on the downstream side of the charged particle beam B with respect to the dose monitor 12. Each of the monitors 11, 12, 13a and 13b outputs the detected detection result to the control unit 7.

The degrader 30 reduces the energy of the passing charged particle beam B to fine-tune the energy of the charged particle beam B. In the present embodiment, the degrader 30 is provided at the tip 9a of the irradiation nozzle 9. The tip 9a of the irradiation nozzle 9 is the downstream end of the charged particle beam B. The degrader 30 in the irradiation nozzle 9 can be omitted.

The control unit 7 is composed of, 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 and 13b, and controls the quadrupole electromagnet 8 so that the beam size of the charged particle beam B becomes constant. .. Further, the control unit 7 controls the operation of the ion source 10 so that the output of the ion source 10 becomes constant based on the intensity of the charged particle beam B measured by the intensity measurement unit 20.

Further, the control unit 7 of the charged particle beam therapy device 1 is connected to the treatment planning device 100 that plans the treatment of the charged particle beam therapy device. The treatment planning device 100 measures the tumor 14 of the patient 15 by CT or the like before treatment, and plans the dose distribution (dose distribution of charged particle beams to be irradiated) at each position of the tumor 14. Specifically, the treatment planning device 100 creates a treatment planning map for the tumor 14. The treatment planning device 100 transmits the created treatment planning map to the control unit 7.

When irradiating a charged particle beam by the scanning method, the tumor 14 is virtually divided into a plurality of layers in the Z direction, and the charged particle beam is scanned and irradiated in one layer. Then, after the irradiation of the charged particle beam in the one layer is completed, the irradiation of the charged particle beam in the adjacent next layer is performed.

When the charged particle beam therapy device 1 shown in FIG. 2 irradiates the charged particle beam B by the scanning method, the quadrupole electromagnet 8 is set to the operating state (ON) so that the passing charged particle beam B converges.

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 charged particle beams 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 is irradiated to the tumor 14 while being scanned within the irradiation range in one layer set in the Z direction. When the irradiation of one layer is completed, the charged particle beam B is irradiated to the next layer.

The charged particle beam irradiation image of the scanning electromagnet 6 under the control of the control unit 7 will be described with reference to FIGS. 3A and 3B. FIG. 3 (a) shows an irradiated body virtually sliced into a plurality of layers in the depth direction, and FIG. 3 (b) shows a scanning image of a charged particle beam in one layer viewed from the depth direction. , Each is shown.

As shown in FIG. 3A, the irradiated body is virtually sliced into a plurality of layers in the irradiation depth direction, and in this example, from a deep layer (the range of the charged particle beam B is long). In order, the layers L ₁ , the layer L ₂ , ... the layer L _n-1 , the layer L _{n 1} , the layer L _{n + 1} , ... the layer L _N-1 , and the layers L _N and N are virtually sliced. Further, as shown in FIG. 3B, the charged particle beam B irradiates a plurality of irradiation spots of the layer Ln while drawing a beam trajectory TL. That is, the charged particle beam B controlled by the control unit 7 moves on the beam trajectory TL.

Next, the respiratory synchronization system 40 and the control unit 7 will be described in detail with reference to FIG. 1 again. The respiration synchronization system 40 detects the respiration of the patient 15 using a sensor and generates a gate signal synchronized with the respiration of the patient 15. The gate signal can be generated, for example, by irradiating the abdomen of the patient 15 with a laser beam to detect a change in abdominal bulge. The gate signal generated in the respiratory synchronization system 40 is output to the timing system 50. The timing system 50 determines whether or not to irradiate the charged particle beam B based on the gate signal, and generates a pulse signal indicating the timing of irradiating the charged particle beam B. The pulse signal generated by the timing system 50 is output to the control unit 7. The control unit 7 switches between the operating state and the stopped state of the beam chopper 16 based on the pulse signal. Thereby, it is possible to switch between an irradiation state in which the tumor of the patient 15 is irradiated with the charged particle beam B according to the breathing of the patient 15 and an interrupted state in which the irradiation of the tumor of the patient 15 with the charged particle beam B is interrupted. Therefore, in order to suppress the irradiation of the charged particle beam B to the portion other than the tumor, it is possible to irradiate the charged particle beam B only at a specific timing of respiration.

The storage unit 60 of the control unit 7 stores the operating parameters of the ion source 10 when the irradiation of the tumor of the patient 15 with the charged particle beam B is interrupted. Then, when the control unit 7 restarts the irradiation of the tumor of the patient 15 with the charged particle beam B, the control unit 7 operates the ion source 10 with the operation parameters stored in the storage unit 60. Examples of the operating parameters of the ion source 10 include the current and voltage of the arc generated in the chimni of the ion source 10, the current and voltage flowing through the filament in the chimni, and the like. Although the storage unit 60 is provided outside the control unit 7 in the present embodiment, the storage unit 60 may be provided integrally with the control unit 7.

Next, the operation of the charged particle beam therapy device 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 according to the comparative example. FIG. 5 is a diagram for explaining the operation of the charged particle beam therapy apparatus according to the present embodiment. 4 and 5 (a), (b), and (c) show the intensity of the charged particle beam, the intensity of the output of the ion source, and the timing signal, respectively. In the charged particle beam therapy device according to the comparative example, the initial parameters are set for the ion source, and the intensity of the charged particle beam is constant so that the output of the ion source is constant while the patient's tumor is irradiated with the charged particle beam. Feedback control is performed based on. However, since the dose monitor for detecting the intensity of the charged particle beam is provided in the irradiation unit, the charged particle beam cannot be detected by the dose monitor while the irradiation of the charged particle beam is stopped. Therefore, the feedback control is not performed while the irradiation of the charged particle beam is stopped, and the initial parameter is set to the ion source again at the timing T when the irradiation of the charged particle beam is restarted. Therefore, as shown in FIG. 4B, the output of the ion source after the timing T becomes unstable. As a result, as shown in FIG. 4A, the intensity of the charged particle beam may become unstable with respect to the desired intensity A, such as the intensity of the charged particle beam overshooting.

On the other hand, in the charged particle beam therapy apparatus 1 according to the present embodiment, the storage unit 60 of the control unit 7 stores the operation parameters of the ion source 10 when the irradiation of the charged particle beam B is interrupted, and the charged particle beam When resuming the irradiation of B, the control unit 7 operates the ion source 10 with the operation parameters stored in the storage unit 60. Therefore, when the irradiation is restarted, the operation of the ion source 10 becomes a state close to the state immediately before the stop, and as shown in FIG. 5 (b), after the timing T for restarting the irradiation of the charged particle beam B. The output of the ion source 10 can be stabilized. Further, the output of the ion source 10 after the timing T can be brought 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. 5A, it is possible to control the intensity of the charged particle beam B to a value close to the desired intensity A and stabilize it.

As described above, the storage unit 60 of the control unit 7 of the charged particle beam therapy device 1 has 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. Remember. Then, when the control unit 7 restarts the irradiation of the charged particle beam B to the tumor (irradiated body) of the patient 15 (timing T), the control unit 7 operates the ion source 10 with the operation parameters stored in the storage unit 60. .. As a result, even if the state of the ion source 10 changes while the irradiation of the charged particle beam B is interrupted, the ion source 10 is controlled to the same operating parameters as immediately before the irradiation of the charged particle beam B is interrupted. Can be done. That is, when the irradiation is restarted, the operation of the ion source 10 can be brought into a state close to the state immediately before the stop. Therefore, it is possible to suppress overshoot of the intensity of the charged particle beam B and stabilize the intensity of the charged particle beam B.

Further, the charged particle beam therapy device 1 further includes an intensity measuring unit 20 for measuring the intensity of the charged particle beam B emitted from the accelerator 3, and the control unit 7 further includes a charged particle beam B measured by the intensity measuring unit 20. The operation of the ion source 10 is controlled based on the intensity of. As a result, the ion source 10 can be controlled based on the intensity of the emitted charged particle beam B, so that the intensity of the charged particle beam B can be more effectively stabilized.

Further, in the charged particle beam therapy device 1, the irradiation unit 2 continuously irradiates the charged particle beam B according to a predetermined beam trajectory TL. As described above, it is possible to stabilize the intensity of the charged particle beam B even when the so-called line scanning method, which is easily affected by the change in the intensity of the charged particle beam B, is used.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be adopted. For example, in the above embodiment, the irradiation unit 2 irradiates the charged particle beam B by using the so-called line scanning method, but the irradiation unit 2 is charged by using another irradiation method such as the so-called spot scanning method. The particle beam B may be irradiated.

Further, in the above embodiment, the intensity measuring unit 20 measures the intensity of the charged particle beam B based on the value measured by the dose monitor 12, but the location where the intensity of the charged particle beam B is measured is particularly high. Not limited. For example, the intensity measuring unit 20 may measure the intensity of the charged particle beam B based on the value measured in the middle of the beam transport line 41.

Further, in the above embodiment, the case where the irradiation of the charged particle beam B is interrupted according to the respiration of the patient has been described as an example, but the configuration in which the irradiation of the charged particle beam B is interrupted is not limited to the above. For example, the case where the irradiation of the charged particle beam B is interrupted when a malfunction of the device is detected in the charged particle beam therapy device 1 is also included.

1 ... charged particle beam therapy device, 2 ... irradiation unit, 3 ... accelerator, 4 ... treatment table, 5 ... rotating gantry, 6 ... scanning electromagnet, 7 ... control unit, 8 ... quadrupole electromagnet, 9 ... irradiation nozzle, 10 ... ion Source, 11 ... Profile monitor, 12 ... Doze monitor, 15 ... Patient, 16 ... Beam chopper, 20 ... Intensity measuring unit, 30 ... Degrader, 40 ... Respiratory synchronization system, 41 ... Beam transport line, 50 ... Timing system, 60 ... Memory Department, 100 ... Treatment planning device, B ... Charged particle beam, TL ... Beam orbit.

Claims (3)

Ion sources that generate charged particles and
An accelerator that accelerates the charged particles generated in the ion source and emits a charged particle beam,
An irradiation unit that irradiates the irradiated body with the charged particle beam,
A control unit that controls the ion source is provided.
The control unit stores the operating parameters of the ion source when the irradiation of the charged particle beam to the irradiated body is interrupted.
The control unit is a charged particle beam therapy device that operates the ion source with the stored operation parameters when resuming irradiation of the irradiated body with the charged particle beam. Further provided with an intensity measuring unit for measuring the intensity of the charged particle beam emitted from the accelerator.
The charged particle beam therapy apparatus according to claim 1, wherein the control unit controls the operation of the ion source based on the intensity of the charged particle beam measured by the intensity measuring unit. The charged particle beam therapy apparatus according to claim 1 or 2, wherein the irradiation unit continuously irradiates the charged particle beam along a predetermined trajectory.

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