JP2017224393A - Ion emitting device and particle beam treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion emitting device capable of reducing the capacity of a high-frequency power source while preventing electrical discharge inside a cylindrical part.SOLUTION: An ion emitting device according to an embodiment comprises: an ion source 1 for generating ions; and a front-stage linear accelerator 3 and a back-stage linear accelerator 4 for sequentially accelerating ion beams 22 derived from the ion source 1. The front-stage linear accelerator 3 and the back-stage linear accelerator 4 each have: a cylindrical part; and an electrode part arranged inside the cylindrical part. The cylindrical part of at least one of the front-stage linear accelerator 3 and the back-stage linear accelerator 4 is made of copper.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to an ion injection apparatus that injects and accelerates an ion beam, and a particle beam therapy apparatus using the ion injection apparatus.

  Generally, an ion injection device is installed in a heavy particle cancer treatment apparatus. This ion injection apparatus is an apparatus that accelerates an ion beam necessary for cancer treatment to an energy that can be incident on a synchrotron.

  Such an ion injector includes an ion source for generating ions, a low energy beam transport (hereinafter referred to as LEBT system equipment), and a radio frequency quadrupole (hereinafter referred to as a radio frequency quadrupole). , And RFQ), and a drift tube type linear accelerator (hereinafter referred to as DTL).

  In the RFQ, four copper (Cu) electrode portions are attached along the axial direction of a hollow portion in which a copper plating layer is formed on the inner peripheral surface of an iron tubular portion. In the DTL, a copper electrode part and a support part thereof are attached to a hollow part in which a copper plating layer is formed on the inner peripheral surface of an iron cylindrical part as in the RFQ. The cylindrical portion of the DTL is divided into two in the beam axis direction. Hereinafter, when these RFQ and DTL are described collectively, they are called linear accelerators.

  The linear accelerator is supplied with a high frequency power of several hundred kW at a peak value using a vacuum tube amplifier as a high frequency power source.

Y. Iwata et al. / Nuclear Instruments and Methods in Physics Research A572 (2007) 1007-1021

  As described above, the linear accelerator of the ion injection apparatus has a configuration in which a cylindrical portion is formed by applying a copper plating layer to iron, and an electrode portion is incorporated in a hollow portion in the cylindrical portion. In such a cylindrical portion, there has been a problem that discharge occurs due to, for example, a gas accumulated in the copper plating layer being released due to poor plating or aging.

  When the ion injection apparatus is applied to a heavy particle cancer treatment apparatus and a discharge such as that described above occurs, a recovery operation is required to interrupt the operation and remove the discharge generation site. In particular, interrupting the operation when the treatment is in progress increases the burden on the patient and decreases the operating rate of the treatment apparatus.

  In addition, since the cylindrical portion of the DTL is divided into two in the beam axis direction, the number of assembly parts increases, current loss occurs due to electrical resistance at the joint, and more high-frequency power than the ideal high-frequency calculated value. There was a problem that would be necessary. Therefore, if the necessary high frequency power increases, a high frequency power source having a large capacity is required, leading to an increase in initial investment. In addition, there is a problem that the operating cost due to the replacement of the high-frequency power supply, which is a consumable item, is increased.

  Furthermore, the conventional ion injection apparatus uses a vacuum tube amplifier as a high-frequency power source. This vacuum tube amplifier requires periodic replacement of the vacuum tube, and it is necessary to adjust various operation parameters after replacement or when there is a malfunction, resulting in poor maintenance.

  The problem to be solved by the present embodiment is to provide an ion injection device and a particle beam therapy device capable of preventing the occurrence of discharge in the cylindrical portion and reducing the capacity of the high-frequency power source.

  In order to solve the above problems, an ion injection apparatus according to the present embodiment includes an ion source that generates ions, and a front-stage linear accelerator and a rear-stage linear accelerator that sequentially accelerate an ion beam extracted from the ion source. The front-stage linear accelerator and the rear-stage linear accelerator each have a cylindrical portion and an electrode portion installed in the cylindrical portion, and the cylindrical shape of at least one of the front-stage linear accelerator and the rear-stage linear accelerator. The part is a copper product.

  The particle beam therapy system according to the present embodiment transports an ion source that generates ions, a front-stage linear accelerator and a rear-stage linear accelerator that sequentially accelerate an ion beam extracted from the ion source, and an ion beam of the rear-stage linear accelerator. A synchrotron that circulates the ion beam and accelerates it to a predetermined energy, an extraction device that extracts the ion beam accelerated by the synchrotron, and an irradiation that irradiates the irradiation target with the ion beam extracted by the extraction device Each of the front-stage linear accelerator and the rear-stage linear accelerator includes a cylindrical portion and an electrode portion installed in the cylindrical section, and at least of the front-stage linear accelerator and the rear-stage linear accelerator. One of the cylindrical portions is a copper product.

  According to this embodiment, it is possible to prevent the occurrence of discharge in the cylindrical portion and reduce the capacity of the high-frequency power source.

It is a block diagram which shows the particle beam therapy apparatus to which each embodiment is applied. It is a block diagram which shows the ion injection apparatus of 1st Embodiment. It is a schematic perspective view which shows RFQ of 1st Embodiment. It is a schematic perspective view which shows RFQ of the modification of 1st Embodiment. It is a schematic perspective view which shows DTL of 1st Embodiment. It is a schematic perspective view which shows DTL of the modification of 1st Embodiment. It is a block diagram which shows the ion injection apparatus of 2nd Embodiment.

  Hereinafter, an ion injection device and a particle beam therapy system according to the present embodiment will be described with reference to the drawings.

(Particle beam therapy system)
(Constitution)
FIG. 1 is a configuration diagram showing a particle beam therapy system to which each embodiment is applied.

  As shown in FIG. 1, the particle beam treatment apparatus is schematically composed of an ion injection device 20, a middle energy beam transport system (hereinafter referred to as MEBT system device) 6, a synchrotron 7, an extraction device 13, An irradiation device 19 is provided.

  The ion injection device 20, the MEBT system device 6, and the synchrotron 7 constitute the ion acceleration device of this embodiment. The ion injection device 20 includes an electron cyclotron resonance (ECR) ion source (hereinafter referred to as an ECR ion source) 1, an LEBT system device 2, an RFQ 3 as a pre-stage linear accelerator, and two or more as post-stage linear accelerators ( Each embodiment includes two) DTL 4, triple quadrupole electromagnet 5, and charge conversion device 21.

  The synchrotron 7 includes a deflection electromagnet 8, a quadrupole electromagnet 9, a hexapole electromagnet 10, a high-frequency acceleration cavity 11, and a bump electromagnet 12.

(Work)
Next, the operation of the particle beam therapy system will be described.

The ECR ion source 1 ionizes a gas to generate a plasma, extracts ions by an electric field, and the extraction current is a direct current. The ECR ion source 1 can generate multivalent ions, but the current amount of ions with high valence is small. Therefore, the ECR ion source 1 generates carbon tetravalent ions (C ⁴⁺ ) in order to secure an ion current amount necessary for cancer treatment. In addition to carbon tetravalent ions, cations such as He that can be generated by ECR and used for treatment are conceivable. It is also conceivable to generate carbon pentavalent ions or carbon hexavalent ions by increasing the frequency of the high frequency or by superconducting ECR method, laser ion source method or the like.

  Ions generated by the ECR ion source 1 are transported to the RFQ 3 and the two DTLs 4 installed on the downstream side while adjusting the beam characteristics with the LEBT system device 2. RFQ3 electrically focuses and accelerates the ion beam. The two DTLs 4 accelerate the ion beam electrically.

A triple quadrupole electromagnet 5 is installed between the RFQ 3 and the DTL 4 and between the two DTLs 4. These triple quadrupole electromagnets 5 converge the expanding ion beam. The ion beam emitted from the DTL 4 is converted from carbon tetravalent ions (C ⁴⁺ ) to carbon hexavalent ions (C ⁶⁺ ) by the charge conversion device 21, and transported to the synchrotron 7 via the MEBT system device 6.

  The synchrotron 7 orbits the ion beam many times to further accelerate to the energy required for cancer treatment. Specifically, the deflection electromagnet 8 creates a circular orbit. The quadrupole electromagnet 9 controls the convergence of the ion beam. The hexapole electromagnet 10 corrects chromaticity (chromatic aberration). The high frequency acceleration cavity 11 accelerates the ion beam.

  The ion beam accelerated to a sufficient energy by the synchrotron 7 is transported from the exit track 18 to an irradiation chamber (not shown) through the exit bump electromagnet 12 and the extraction device 13. An irradiation device 19 is installed in the irradiation chamber. This irradiation device 19 performs cancer treatment by irradiating an affected part of a patient who is an irradiation target with an ion beam.

(First Embodiment of Ion Injection Device)
FIG. 2 is a configuration diagram illustrating the ion injection device of the first embodiment. FIG. 3 is a schematic perspective view showing the RFQ of the first embodiment. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and a configuration different from that in FIG. 1 will be described.

  As shown in FIG. 2, a vacuum tube amplifier 15, which is a high-frequency power source, is connected to each of RFQ 3 and the two DTLs 4 via a waveguide 16. Each waveguide 16 supplies the high frequency power from the respective vacuum tube amplifier 15 to RFQ3 and two DTL4. That is, each vacuum tube amplifier 15 supplies RFQ3 and two DTL4 via the waveguide 16 with high frequency power of several hundred kW at a peak value.

  As shown in FIG. 3, the RFQ 3 is formed in a cylindrical shape so as to be a resonator, and two sets of the RFQ 3 are opposed to each other at a certain interval in the circumferential direction of the hollow portion in the cylindrical portion 31. The electrode part 32 to be provided. These four electrode portions 32 are formed so as to extend along the axial direction of the cylindrical portion 31. A high-frequency electric field for accelerating and focusing the ion beam 22 is formed in the space surrounded by the four electrode portions 32.

  In the present embodiment, the cylindrical portion 31 and the electrode portion 32 of the RFQ 3 are copper products such as oxygen-free copper. The cylindrical portion 31 and the electrode portion 32 are integrally molded products that are integrally formed in the axial direction of the ion beam 22. The cylindrical part 31 and the electrode part 32 are cut products such as cutting and cutting.

  FIG. 4 is a schematic perspective view showing an RFQ of a modification of the first embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the part which is the same as or corresponds to RFQ3 shown in FIG.

  As shown in FIG. 4, the modified RFQ 3 assembles the divided members 3 a and 3 b obtained by dividing the cylindrical portion 31 and the electrode portion 32 made of copper into two in the circumferential direction. In this case, the divided members 3a and 3b are vacuum-sealed by an O-ring (not shown) or the like.

  Thereby, although RFQ3 of a modification has a seam in the circumferential direction of the cylindrical part 31, it becomes an integral structure without a seam with respect to the axial direction of the ion beam 22. FIG. Here, the divided members 3a and 3b obtained by dividing the cylindrical portion 31 and the electrode portion 32 into two in the circumferential direction are cut and cut parts such as cut parts, and these cut parts are integrally assembled into a cylindrical shape. It is done.

  In addition, RFQ 3, after assembling the divided members 3 a and 3 b obtained by dividing the copper cylindrical portion 31 into two in the circumferential direction, is integrally assembled into a cylindrical shape, and then four copper electrode portions 32 are provided on the inner peripheral surface of the cylindrical portion 31. You may make it attach. Also in this case, the electrode part 32 is a cut product. Further, the cylindrical portion 31 and the electrode portion 32 are vacuum-sealed by an O-ring (not shown) or the like.

  In addition, although RFQ3 of the modification shown in FIG. 4 demonstrated the example divided into 2 in the circumferential direction, it may be 4 divisions or other multiple divisions.

  FIG. 5 is a schematic perspective view showing the DTL of the first embodiment.

  As shown in FIG. 5, the two DTLs 4 are a cylindrical part 41 formed in a cylindrical shape like RFQ 3, and an electrode integrated with a hollow part in the cylindrical part 41 with a certain interval in the axial direction. Part 42 and support part 43. As for two DTL4, the cylindrical part 41, the electrode part 42, and the support part 43 are copper products, such as oxygen-free copper, similarly to RFQ3. The cylindrical portion 41, the electrode portion 42, and the support portion 43 are an integrally molded product that is integrally formed in the axial direction of the ion beam 22. The cylindrical part 41, the electrode part 42, and the support part 43 are cutting products, such as cutting out and cutting out, respectively.

  FIG. 6 is a schematic perspective view showing a DTL according to a modification of the first embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the part which is the same as or corresponds to DTL4 shown in FIG.

  As shown in FIG. 6, the DTL 4 of the modified example is formed by integrally assembling the divided members 4 a and 4 b obtained by dividing the copper tubular portion 41 into two in the circumferential direction, and then on the inner peripheral surface of the tubular portion 41. The integrated electrode part 42 and support part 43 are attached. Also in this case, each member is formed by cutting.

  Further, the cylindrical portion 41 and the support portion 43 are vacuum-sealed by an O-ring (not shown) or the like, similar to the RFQ 3. Thereby, although the two DTLs 4 also have a seam in the circumferential direction of the cylindrical portion 41, an integrated structure without a seam in the axial direction of the ion beam 22 is obtained.

  In addition, although DTL4 of the modification shown in FIG. 6 demonstrated the example divided into 2 in the circumferential direction, it may be 4 divisions or other multiple divisions.

  Therefore, the RFQ 3 and the two DTLs 4 resonate the cylindrical portions 31 and 41 with a high frequency electric field of several hundred MHz, and accelerate the ion beam 22 by the electric field generated in the electrode portions 32 and 42.

  Note that when the RFQ 3 and the two DTLs 4 are integrally processed with copper, the circumferential division is more suitable than the division in the beam axis direction. The reason is that when divided in the beam axis direction as in the prior art, in RFQ3, the tips of the electrode portions 32 face each other in the cylindrical space, and electrode processing is difficult. Further, the RFQ 3 and the two DTLs 4 are suitable for machining such as cutting and cutting as described above in order to perform integral machining.

According to this embodiment, since each of the cylindrical portions 31 and 41 of RFQ3, DTL4 is copper products, avoiding the discharge of plating defects, tubular portion 31 and 41 due to aging It becomes possible.

  In addition, according to the present embodiment, RFQ3 and DTL4 have an integral structure with respect to the axial direction of the ion beam 22, and since there is no joint in the axial direction of the ion beam 22, there is no current loss due to electrical resistance, and a high-frequency power source Capacity can be reduced. As a result, the ion injection device 20 capable of reducing the introduction and operation costs can be provided.

  Furthermore, when this embodiment is applied to a heavy ion beam therapy apparatus, stable operation is possible without interrupting operation, preventing a reduction in the operating rate of the therapy apparatus, and improving reliability. Can do.

  In this embodiment, an example in which the ECR ion source 1 is used as an ion source has been described. However, the present invention is not limited to this, and a laser ion source may be used. In this case, the LEBT system device 2 becomes unnecessary.

  Moreover, although this embodiment demonstrated the example which installed one RFQ3 as a front | former stage linear accelerator, you may install multiple units | sets corresponding to not only this but required energy. In addition, although an example in which two DTL4s are installed as a post-stage linear accelerator has been described, the present invention is not limited to this, and it is sufficient to install at least one corresponding to the required energy.

  Furthermore, in this embodiment, the triple quadrupole electromagnet 5 is installed between RFQ3 and DTL4, and between DTL4 and DTL4. However, a double quadrupole electromagnet may be used, or a triple quadrupole electromagnet. The number of 5 installed may be 0 or plural.

  Moreover, in this embodiment, you may install beam monitors, such as CT (current transformer), FC (Faraday cup), a wire monitor, a fluorescent screen, in the space where the triple quadrupole electromagnet 5 is installed.

  Further, in the present embodiment, the cylindrical portions 31 and 41 and the electrode portions 32 and 42 of the RFQ 3 and DTL 4 are made of copper products, but the present invention is not limited to this, and either the cylindrical portion and the electrode portion of the RFQ 3 or DTL 4 are used. May be a copper product.

  In the present embodiment, each of the cylindrical portions 31 and 41 of RFQ3 and DTL4 is an integrally formed product having an integral structure with respect to the axial direction of the ion beam 22. However, the present invention is not limited to this, and either one of RFQ3 or DTL4 is used. The cylindrical portion may be an integrally molded product having an integral structure. Moreover, it is good also considering both one cylindrical part and electrode part of RFQ3 and DTL4 as an integrally molded product.

(Second Embodiment of Ion Injection Device)
FIG. 7 is a block diagram showing an ion injection device of the second embodiment. In addition, the same code | symbol is attached | subjected to the structure same as the said 1st Embodiment, and the overlapping description is abbreviate | omitted.

  In the first embodiment, the vacuum tube amplifier 15 is used for the high-frequency power supply, but in the present embodiment, the semiconductor amplifier 17 is used.

  As shown in FIG. 7, a semiconductor amplifier 17 that is a high-frequency power source is connected to RFQ 3 and the two DTLs 4 via waveguides 16 respectively. Each waveguide 16 supplies high frequency power from the respective semiconductor amplifier 17 to RFQ 3 and two DTLs 4. That is, each semiconductor amplifier 17 supplies high-frequency power of 200 kW or less to RFQ 3 and two DTLs 4 through the waveguide 16.

  In the present embodiment, it is possible to introduce a semiconductor amplifier having a track record of operation by setting the high frequency power of the semiconductor amplifier 17 to 200 kW or less. In the present embodiment, the semiconductor amplifiers 17 having a high frequency power of 200 kW or less are connected to the two DTLs 4 respectively. However, when two semiconductor amplifiers 17 having a high frequency power of 200 kW or less are combined, the DTL 4 is combined into one. But it is possible.

  As described above, according to the present embodiment, since the semiconductor amplifier 17 is used as the high frequency power source of the RFQ 3 and the two DTLs 4, it is not necessary to adjust various operation parameters after replacement or at the time of malfunction, and the maintainability can be improved. become.

  In the present embodiment, the RFQ 3 and the two DTL 4 high-frequency power supplies are the semiconductor amplifier 17, but at least one of the RFQ 3 and DTL 4 may be the semiconductor amplifier 17.

(Other embodiments)
Although the embodiments of the present invention have been described, these embodiments are presented as examples, and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

  For example, in each of the above-described embodiments, an example in which the ion injection device 20 is applied to a heavy particle beam therapy apparatus has been described. However, the present invention is not limited thereto, and can be applied to, for example, a particle beam therapy apparatus using a proton beam. .

  DESCRIPTION OF SYMBOLS 1 ... ECR ion source (ion source), 2 ... LEBT system equipment, 3 ... RFQ (front stage linear accelerator), 3a, 3b ... Split member, 4 ... DTL (back stage linear accelerator), 4a, 4b ... Split member, 5 ... Triple quadrupole electromagnet, 6 ... MEBT system equipment, 7 ... synchrotron, 8 ... deflection electromagnet, 9 ... quadrupole electromagnet, 10 ... hexapole electromagnet, 11 ... high frequency acceleration cavity, 12 ... bump electromagnet, 13 ... extraction equipment, 15 ... Vacuum tube amplifier (high-frequency power source), 16 ... waveguide, 17 ... semiconductor amplifier (high-frequency power source), 18 ... exit orbit, 19 ... irradiation device, 20 ... ion injection device, 21 ... charge conversion device, 22 ... ion beam, 31 ... Cylindrical part, 32 ... Electrode part, 41 ... Cylindrical part, 42 ... Electrode part, 43 ... Support part

Claims (12)

An ion source for generating ions;
A pre-stage linear accelerator and a post-stage linear accelerator for sequentially accelerating the ion beam extracted from the ion source,
The front-stage linear accelerator and the rear-stage linear accelerator each have a cylindrical part and an electrode part installed in the cylindrical part,
The ion injection apparatus according to claim 1, wherein the cylindrical portion of at least one of the front-stage linear accelerator and the rear-stage linear accelerator is a copper product.   The ion injection apparatus according to claim 1, wherein at least one of the cylindrical portions of the front-stage linear accelerator and the rear-stage linear accelerator is an integrally molded product.   The ion injection apparatus according to claim 1, wherein at least one of the cylindrical portion and the electrode portion of the front-stage linear accelerator and the rear-stage linear accelerator is an integrally molded product.   The ion injection apparatus according to claim 2, wherein the integrally molded product is a cut product.   3. The ion injection apparatus according to claim 1, wherein the cylindrical portion of at least one of the front-stage linear accelerator and the rear-stage linear accelerator has an integrated structure with respect to an axial direction of the ion beam.   The ion injection apparatus according to claim 1, wherein at least one of the cylindrical portions of the front-stage linear accelerator and the rear-stage linear accelerator is divided in a circumferential direction.   The ion injection apparatus according to claim 6, wherein the cylindrical portion is divided into two or four in the circumferential direction.   The high-frequency power supply for supplying high-frequency power to each of the front-stage linear accelerator and the rear-stage linear accelerator is further provided, and at least one of the front-stage linear accelerator and the rear-stage linear accelerator is a semiconductor amplifier. The ion injection device according to any one of 1 to 7.   9. The ion injection apparatus according to claim 1, wherein the front-stage linear accelerator is a high-frequency quadrupole linear accelerator, and the rear-stage linear accelerator is a drift tube linear accelerator.   The ion injection apparatus according to claim 1, wherein a plurality of the latter-stage linear accelerators are installed.   The triple quadrupole electromagnet for converging the ion beam is further installed between the front-stage linear accelerator and the rear-stage linear accelerator and between the plurality of rear-stage linear accelerators, respectively. An ion injection apparatus according to 1. An ion source for generating ions;
A front linear accelerator and a rear linear accelerator for sequentially accelerating an ion beam extracted from the ion source;
A synchrotron that transports an ion beam of the latter-stage linear accelerator and accelerates the ion beam to a predetermined energy by circling the ion beam;
An extraction device for extracting an ion beam accelerated by the synchrotron;
An irradiation device for irradiating an irradiation target with an ion beam extracted by the extraction device,
The front-stage linear accelerator and the rear-stage linear accelerator each have a cylindrical part and an electrode part installed in the cylindrical part,
The particle beam therapy system according to claim 1, wherein the cylindrical portion of at least one of the front-stage linear accelerator and the rear-stage linear accelerator is a copper product.

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