JP2018146265A - Electron beam irradiation device and method for operating electron beam irradiation device - Google Patents

Abstract

Beam irradiation for selectively applying large energy to an irradiated portion in an irradiation target is realized using an electron beam. An electron beam irradiation apparatus 100 irradiates an affected area T of a patient 10 with an electron beam E. The electron beam irradiation apparatus 100 includes a chirped electron beam source 1 and an electron beam phase rotator 2. The chirped electron beam source 1 generates an electron beam E having energy chirp. The electron beam phase rotator 2 adjusts the energy chirp of the electron beam E generated by the chirped electron beam source 1 so that a higher energy component is arranged behind the beam traveling direction. [Selection] Figure 1

Description

  The present invention relates to an electron beam irradiation apparatus and an operation method of the electron beam irradiation apparatus.

  Conventionally, for example, in radiation therapy, a particle beam irradiation apparatus that irradiates a diseased part of a patient's trunk (irradiated part in an irradiation target) with a particle beam such as a heavy particle beam or a proton beam is used. The particle beam has a Bragg peak characteristic in which the energy imparted to the medium material is inversely proportional to the velocity of the particle and is maximized at the moment when the particle stops. Therefore, in the particle beam irradiation apparatus, using this Bragg peak characteristic, a large energy is selectively given only to the affected part of the patient, and the treatment for destroying only the affected part by the beam irradiation is performed. As this type of technology, for example, Patent Document 1 described below describes a heavy particle beam therapy apparatus that irradiates an affected part of a patient with an ion beam.

Japanese Patent Laying-Open No. 2006-162692

  In the apparatus as described above, the energy of the particle beam is as high as several hundred MeV, and a large ring synchrotron accelerator or the like is required. Therefore, the apparatus becomes huge. Therefore, in recent years, an electron beam irradiation apparatus that irradiates an irradiated portion in an irradiation target with an electron beam has been developed. However, since the electron beam does not have a Bragg peak characteristic, it is difficult to selectively apply large energy only to the affected part of the patient's trunk by beam irradiation using the electron beam.

  It is an object of the present invention to provide an electron beam irradiation apparatus and an operation method of the electron beam irradiation apparatus capable of realizing beam irradiation for selectively applying large energy to an irradiated portion in an irradiation target using an electron beam. To do.

  An electron beam irradiation apparatus according to the present invention is an electron beam irradiation apparatus that irradiates an irradiated portion in an irradiation target with an electron beam, and generates an electron beam having an energy chirp and an electron beam source. A chirp adjusting unit that adjusts the energy chirp of the electron beam so that a higher energy component is arranged at the rear of the beam traveling direction.

  In this electron beam irradiation apparatus, the energy chirp of the generated electron beam is adjusted so that a higher energy component is arranged behind the beam traveling direction. The electron beam with the energy chirp adjusted in this way automatically has a pulse width that is gradually and gradually increased with the propagation to the irradiated portion in the irradiation target. Thereby, in spite of the beam irradiation using an electron beam, it becomes possible to increase the energy application of the irradiated part while suppressing the application of energy other than the irradiated part in the irradiation target. That is, it is possible to realize beam irradiation that selectively applies large energy to the irradiated portion in the irradiation target using the electron beam.

  The electron beam irradiation apparatus according to the present invention may further include an electron beam compression unit that adjusts the optical path of each energy component of the electron beam adjusted by the chirp adjustment unit and compresses the pulse width of the electron beam. Thereby, the compression point of the pulse width of the electron beam can be adjusted.

  An electron beam irradiation apparatus according to the present invention includes a detection unit that detects a position where the pulse width of an electron beam is compressed most within an irradiation target, and a controller that controls the electron beam compression unit according to a detection result of the detection unit. , May be further provided. In the electron beam irradiation apparatus according to the present invention, the controller feedback-controls the driving signal of the electron beam compression unit based on the detection result of the detection unit, and determines the position where the pulse width of the electron beam is compressed most, You may move within the area | region to include. In this case, for example, it is possible to effectively irradiate the irradiated portion over a wide range with the electron beam.

  In the electron beam irradiation apparatus according to the present invention, the electron beam source includes a laser plasma electron accelerator for accelerating the electron beam, and generates an electron beam having an energy chirp arranged in front of the beam traveling direction for higher energy components. The chirp adjusting unit may be an electron beam phase rotator that inverts the energy chirp of the electron beam generated by the electron beam source. With such a configuration, the above-described effect of realizing the beam irradiation that selectively applies large energy to the irradiated portion in the irradiation target by using the electron beam is specifically exhibited.

  An operation method of an electron beam irradiation apparatus according to the present invention is an operation method of an electron beam irradiation apparatus that irradiates an irradiated part in an irradiation target with an electron beam, and an electron beam having an energy chirp is generated by an electron beam source. An electron beam generating step, and a chirp adjusting step for adjusting the energy chirp of the electron beam generated in the electron beam generating step by a chirp adjusting unit so that a higher energy component is arranged behind the beam traveling direction. .

  Also in the operation method of this electron beam irradiation apparatus, in the same manner as the electron beam irradiation apparatus, despite the beam irradiation using the electron beam, the application of energy other than the irradiated portion is suppressed in the irradiation target, while the irradiation portion of the irradiated portion is suppressed. It becomes possible to increase energy provision. That is, it is possible to realize beam irradiation that selectively applies large energy to the irradiated portion in the irradiation target using the electron beam.

  The operation method of the electron beam irradiation apparatus according to the present invention is such that the electron beam compression unit compresses the pulse width of the electron beam by adjusting the optical path of each energy component of the electron beam adjusted in the chirp adjustment step by the electron beam compression unit. A step may be further provided. Thereby, for example, the compression point of the pulse width of the electron beam can be adjusted.

  The operation method of the electron beam irradiation apparatus according to the present invention includes a detection step for detecting the position where the pulse width of the electron beam is compressed most within the irradiation target, and controls the electron beam compression unit according to the detection result of the detection step. And a control step for performing. In the operation method of the electron beam irradiation apparatus according to the present invention, in the control step, the drive signal of the electron beam compression unit is feedback controlled based on the detection result of the detection step, and the position where the pulse width of the electron beam is compressed most, You may move within the area | region including a to-be-irradiated part. In this case, for example, it is possible to effectively irradiate the irradiated portion over a wide range with the electron beam.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the electron beam irradiation apparatus which can implement | achieve the beam irradiation which gives a big energy selectively to the to-be-irradiated part in irradiation object using an electron beam, and the operating method of an electron beam irradiation apparatus It becomes.

It is a schematic block diagram which shows the electron beam irradiation apparatus which concerns on one Embodiment. (A) is the schematic which shows an electron beam phase rotator. (B) is a schematic diagram showing an electron beam compressor. (A) is a figure which shows the pulse of the electron beam produced | generated with the chirp electron beam source. (B) is a figure which shows the pulse of the electron beam inverted by the electron beam phase rotator. (C) is a figure which shows the pulse of the electron beam compressed with the electron beam compressor. (D) is a figure which shows the pulse of the electron beam in the position of an affected part. It is a graph which shows the dose provision distribution of an electron beam.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a schematic configuration diagram showing an electron beam irradiation apparatus 100. As shown in FIG. 1, the electron beam irradiation apparatus 100 is an apparatus that irradiates an affected part (irradiated part) T in the body of a patient (irradiation target) 10 with an electron beam E. The electron beam irradiation apparatus 100 here is a cancer treatment apparatus used for cancer treatment by radiation, and the affected part T is a cancer cell located in the deep part of the trunk of the patient 10. That is, the irradiated part exists at a deep position (trunk) in the irradiation target. The electron beam irradiation apparatus 100 includes a chirped electron beam source 1, an electron beam phase rotator 2, an electron beam compressor 3, a beam compression point monitor (detection unit) 4, and a controller 5.

  The chirped electron beam source 1 is an electron beam source that generates and emits an electron beam E having an energy chirp. The chirped electron beam source 1 includes a laser plasma electron accelerator that accelerates an electron beam by laser plasma acceleration. As the laser plasma electron accelerator, for example, an apparatus including an optical waveguide forming apparatus that forms an optical waveguide for propagating a high-intensity laser pulse over a long distance by gas discharge in a discharge tube can be used. The electron beam E generated by the chirped electron beam source 1 has an energy chirp because the energy spectrum is expanded by the disruption of the plasma wave in the laser plasma electron accelerator.

  The energy chirp means a state in which the energy component of the electron beam E has a strong correlation with the beam traveling direction, and the energy component gradually changes from the front to the rear in the beam traveling direction of the electron beam E. Specifically, the electron beam E generated by the chirped electron beam source 1 is such that an energy chirp (in other words, a lower energy component (electron) is a beam with a higher energy component (electron) disposed in front of the beam traveling direction). Energy chirp arranged behind the traveling direction).

  The electron beam E generated by the chirped electron beam source 1 has a pulse width of several femtoseconds. The electron beam E generated by the chirped electron beam source 1 has energy that can pass through the patient 10 and reach the affected part T. Here, the electron beam E has an energy of several hundred MeV or more, specifically, an energy of 200 MeV or more.

  The electron beam phase rotator 2 is a chirp adjusting unit that rotates the electron beam E generated by the chirped electron beam source 1 spatially by 180 ° and inverts the energy chirp of the electron beam E. The electron beam phase rotator 2 is arranged so that the higher energy component is arranged behind the beam traveling direction (in other words, the lower energy component is arranged ahead of the beam traveling direction). Adjust the chirp. As the electron beam phase rotator 2, for example, an electronic bunch stretcher can be used.

  FIG. 2A is a configuration diagram illustrating an example of the electron beam phase rotator 2. As shown in FIG. 2A, the electron beam phase rotator 2 includes magnetic field forming units 2a, 2b, 2c, and 2d configured by dipole magnets. In the electron beam phase rotator 2, electrons move so as to form a semicircular orbit by the magnetic fields of the magnetic field forming units 2a, 2b, 2c, and 2d. At this time, electrons with high energy are difficult to bend, move like drawing a semicircle of a circle with a large radius, and the flight distance becomes long. In contrast, electrons with low energy tend to bend, move like drawing a semicircle of a circle with a small radius, and shorten the flight distance. Therefore, the electron beam E emitted from the electron beam phase rotator 2 has an energy chirp arranged at the rear of the beam traveling direction as the energy component increases.

  As shown in FIG. 1, the electron beam compressor 3 is an electron beam compression unit that compresses the pulse width of the electron beam E adjusted by the electron beam phase rotator 2. The electron beam compressor 3 adjusts the optical path of each energy component of the electron beam E adjusted by the electron beam phase rotator 2 to compress the pulse width of the electron beam E. The electron beam compressor 3 is controlled by the controller 5 to adjust the optical path of each energy component of the electron beam E so that the pulse width of the electron beam E is most compressed at the position of the affected part T. As the electron beam compressor 3, for example, an electronic bunch compressor can be used.

  FIG. 2B is a configuration diagram illustrating an example of the electron beam compressor 3. As shown in FIG. 2B, the electron beam compressor 3 includes electromagnets 3a, 3b, 3c, and 3d. In the electron beam compressor 3, the electrons move so as to form an arcuate orbit by the magnetic fields of the electromagnets 3a, 3b, 3c, and 3d. At this time, electrons with high energy have a short flight distance, whereas electrons with low energy have a long flight distance. Therefore, the electron beam compressor 3 controls each magnetic field of the electromagnets 3a, 3b, 3c, and 3d by controlling each drive current of the electromagnets 3a, 3b, 3c, and 3d by the controller 5. Thereby, the optical path of each energy component of the electron beam E is adjusted, and as shown in FIG. 1, the optical path distance L from the electron beam compressor 3 to the affected part T is set so that the pulse width of the electron beam E is the position of the affected part T. The most compressed distance.

  The beam compression point monitor 4 detects the compression point of the pulse width of the electron beam E in the body of the patient 10. The compression point is a position (distance) at which the pulse width of the electron beam E is compressed most. In the illustrated example, three beam compression point monitors 4 are arranged around the patient 10. The beam compression point monitor 4 outputs information (detection result) regarding the compression point of the electron beam E to the controller 5. The beam compression point monitor 4 is not particularly limited, and various known monitors can be employed.

  The controller 5 is composed of, for example, one or more computer devices. The controller 5 includes a CPU (Central Processing Unit) that is a processor, a RAM (Random Access Memory) that is a recording medium, a ROM (Read Only Memory), and the like. The controller 5 executes various controls by causing a program or the like to be read on hardware such as a CPU and a RAM. The controller 5 controls the electron beam compressor 3 according to the detection result of the beam compression point monitor 4. The controller 5 feedback-controls each drive current (drive signal) of the electromagnets 3a, 3b, 3c, and 3d of the electron beam compressor 3 based on the information about the compression point of the electron beam E output from the beam compression point monitor 4. . Thereby, the optical path distance L to the affected part T is adjusted so that the pulse width of the electron beam E is compressed most at the position of the affected part T. Here, the compression point of the electron beam E is moved within the region including the affected part T.

  Next, an electron beam irradiation method (operation method of the electron beam irradiation apparatus 100) by the electron beam irradiation apparatus 100 will be described. 3A to 3D are diagrams showing pulses of the electron beam E. FIG. In FIG. 3, the horizontal width represents the pulse width, and the vertical width represents the charge density. In FIG. 3, the pulses are shown separately for each energy component, and the darker the higher the energy component is.

  First, an electron beam E having energy chirp is generated by the chirped electron beam source 1 (electron beam generating step). As shown in FIG. 3A, the generated electron beam E has an energy chirp that is arranged in front of the beam traveling direction as the energy component becomes higher.

  Subsequently, the energy chirp of the electron beam E generated in the electron beam generation step is inverted by the electron beam phase rotator 2 (chirp adjustment step). As a result, as shown in FIG. 3B, the electron beam E has an energy chirp that is arranged behind the beam traveling direction as the energy component increases. In this state, in the process of propagation of the electron beam E, the rear high energy component catches up with the front low energy component, and the pulse width of the electron beam E is automatically compressed. When the pulse width is compressed, the charge density of the electron beam E increases and the internal electric field rises.

  Subsequently, the optical path of each energy component of the electron beam E is adjusted by the electron beam compressor 3, and the pulse width of the electron beam E is compressed by the electron beam compressor 3 as shown in FIG. Electron beam compression step). At this time, the compression point of the electron beam E in the body of the patient 10 is detected by the beam compression point monitor 4 (detection step). The controller 5 controls the electron beam compressor 3 according to the detection result of the beam compression point monitor 4 (control step). Specifically, the controller 5 feedback-controls each drive current of the electromagnets 3a, 3b, 3c, 3d (see FIG. 2B) of the electron beam compressor 3 based on the detection result of the beam compression point monitor 4. . Thereby, the compression point of the electron beam E is moved in the region including the affected part T. Specifically, as shown in FIG. 3 (d), the electron beam is moved so that the place (irradiation place) where the pulse width is most compressed moves within the region including the affected part T in the body of the patient 10. E is irradiated. In the present embodiment, the pulse width of the electron beam E is most compressed, so that the pulse width is the same as the pulse of the electron beam E generated by the chirped electron beam source 1 (see FIG. 3A) and has the same charge density. To return, the pulse width of the electron beam E is compressed.

  As described above, in the present embodiment, the energy chirp of the electron beam E generated by the chirped electron beam source 1 is adjusted by the electron beam phase rotator 2 so that the higher energy component is arranged behind the beam traveling direction. The electron beam whose energy chirp has been adjusted in this way is automatically and gradually compressed in pulse width as it reaches the affected part T in the patient 10, and the charge density increases. Thereby, in spite of the beam irradiation using the electron beam E, it is possible to suppress the energy application (energy deposit) other than the affected part T in the patient 10 while increasing the energy application of the affected part T.

  That is, according to the present embodiment, the energy-chirped electron beam E is controlled, the pulse width is gradually compressed during propagation of the electron beam E, and the affected part T is adjusted so that the pulse width is shortened. The charge density of the electron beam E can be increased. Beam irradiation that selectively applies a large amount of energy only to the affected part T, which is a local region inside the patient 10, can be realized using the electron beam E.

  FIG. 4 is a graph showing the dose distribution of the electron beam E. The vertical axis in the figure is the relative dose of the electron beam E, and the horizontal axis in the figure is the depth of the patient 10 from the electron beam incident surface. As shown in FIG. 4, in the depth region up to the affected area T, the relative dose of the electron beam E is maintained at a low level, whereas the relative position of the electron beam E at the depth position of the affected area T is maintained. Dose is increasing sharply. As described above, in the present embodiment, it is expected that irradiation similar to the Bragg peak characteristic of the hadron beam is performed with the electron beam, although the electron beam E is used.

  In this embodiment, the electron beam compressor 3 adjusts the optical path of each energy component of the electron beam E adjusted by the electron beam phase rotator 2 to compress the pulse width of the electron beam E. Thereby, the optical path distance L to the affected part T can be adjusted to the distance until the maximum compression of the electron beam E, that is, the compression point of the pulse width of the electron beam E can be adjusted. The pulse width of the electron beam E can be compressed most at the position of the affected part T.

  In the present embodiment, the position where the pulse width of the electron beam E is compressed most is moved within the region including the affected part T. Thereby, for example, it is possible to treat such that the portion (irradiation portion) where the pulse width is compressed most in one irradiation of the electron beam E moves in the affected area T over a wide range. The electron beam E can be effectively irradiated to the affected part T over a wide range.

  In the present embodiment, the chirped electron beam source 1 includes a laser plasma electron accelerator for accelerating the electron beam E, and generates an electron beam E having an energy chirp arranged in front of the beam traveling direction for higher energy components. . Then, the electron beam phase rotator 2 inverts the energy chirp of the generated electron beam E. With such a configuration, it is possible to specifically achieve the above-described effect of using the electron beam E to realize beam irradiation that selectively applies large energy to the affected part T in the patient 10.

  In this embodiment, since a laser plasma electron accelerator is used, a large facility such as a heavy particle beam accelerator is unnecessary, and the apparatus can be downsized. The electron beam irradiation apparatus 100 can be realized on a scale that can be introduced into the clinic.

[Modification]
As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment. For example, each numerical value in the above and the drawings may include errors in design, measurement, manufacturing, or the like.

  The above embodiment may further include a phantom (water cell) disposed on the optical path of the electron beam E between the electron beam phase rotator 2 and the patient 10 (preferably in front of the body of the patient 10). Good. This phantom functions as an electron beam compression unit, similar to the electron beam compressor 3, and can be adjusted so that the compression point of the electron beam E is the affected part T in the body of the patient 10. Moreover, in the said embodiment, although the electron beam E was irradiated to the affected part T in the patient's 10 body, as an irradiation object and an irradiated part, it is not specifically limited.

  DESCRIPTION OF SYMBOLS 1 ... Chirp electron beam source (electron beam source), 2 ... Electron beam phase rotator (chirp adjustment part), 3 ... Electron beam compressor (electron beam compression part), 4 ... Beam compression point monitor (detection part), 5 ... Controller: 10 ... Patient (irradiation target), 100 ... Electron beam irradiation device, E ... Electron beam, T ... Affected part (irradiated part).

Claims (9)

An electron beam irradiation apparatus for irradiating an irradiated portion in an irradiation target with an electron beam,
An electron beam source for generating the electron beam having energy chirp;
An electron beam irradiation apparatus, comprising: a chirp adjustment unit configured to adjust the energy chirp of the electron beam generated by the electron beam source so that a higher energy component is arranged behind the beam traveling direction.   The electron beam irradiation apparatus according to claim 1, further comprising an electron beam compression unit that adjusts an optical path of each energy component of the electron beam adjusted by the chirp adjustment unit and compresses a pulse width of the electron beam. A detection unit for detecting a position where the pulse width of the electron beam is compressed most in the irradiation target;
The electron beam irradiation apparatus according to claim 2, further comprising a controller that controls the electron beam compression unit according to a detection result of the detection unit.   The controller feedback-controls the drive signal of the electron beam compression unit based on the detection result of the detection unit, and moves the position where the pulse width of the electron beam is compressed most within the region including the irradiated portion. The electron beam irradiation apparatus according to claim 3. The electron beam source includes a laser plasma electron accelerator for accelerating the electron beam, and generates the electron beam having the energy chirp arranged in front of the beam traveling direction with a higher energy component,
The electron beam irradiation apparatus according to claim 1, wherein the chirp adjusting unit is an electron beam phase rotator that inverts the energy chirp of the electron beam generated by the electron beam source. An operation method of an electron beam irradiation apparatus for irradiating an irradiated portion in an irradiation target with an electron beam,
Generating an electron beam having energy chirp by an electron beam source;
A chirp adjustment step for adjusting the energy chirp of the electron beam generated in the electron beam generation step by a chirp adjustment unit so that a higher energy component is arranged behind the beam traveling direction. How the device works.   The electron beam compression unit according to claim 6, further comprising: an electron beam compression step of adjusting an optical path of each energy component of the electron beam adjusted in the chirp adjustment step by an electron beam compression unit to compress a pulse width of the electron beam. A method of operating the electron beam irradiation apparatus. A detection step of detecting a position where the pulse width of the electron beam is compressed most in the irradiation target;
The operation method of the electron beam irradiation apparatus according to claim 7, further comprising a control step of controlling the electron beam compression unit according to a detection result of the detection step.   In the control step, the drive signal of the electron beam compression unit is feedback controlled based on the detection result of the detection step, and the position where the pulse width of the electron beam is compressed most is moved within the region including the irradiated portion. The operation method of the electron beam irradiation apparatus according to claim 8.