Particle beam therapy device

Abstract

To reduce a beam loss in a beam transport system from a synchrotron to a rotary gantry and efficiently implement beam adjustment in the rotary gantry.SOLUTION: A particle beam therapy device 10 comprises: an injector 11 which performs generation and initial acceleration of a beam 1; a synchrotron 12 to which the beam from the injector is injected and which performs acceleration and deceleration of the beam; a rotary gantry 14 which adjusts an irradiation direction of the beam to a patient; and a beam transport system 13 which transports the beam from the synchrotron to the rotary gantry. In the particle beam therapy device, the beam transport system is configured by having an emittance adjustment device 20 by which, when the beam moves in a traveling direction, a horizontal direction orthogonal to the traveling direction and a vertical direction orthogonal to the traveling direction and the horizontal direction, a correlation can be imparted to the movements of the beam in different two directions among the traveling direction, the horizontal direction and the vertical direction by utilizing an electromagnetic field so as to fix the sum of emittance in the horizontal direction and the vertical direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a particle beam therapy system having a beam transport system that transports a beam from a synchrotron to a rotating gantry. [Background technology]

[0002] As shown in FIG. 4, particle beam therapy device 100 is configured to include an injector 111 that generates and initially accelerates beam 101, a synchrotron 112 that injects beam 101 from injector 111 and accelerates or decelerates beam 101, a beam transport system 113 that transports beam 101 extracted from synchrotron 112, a rotating gantry 114 that can adjust the irradiation direction of beam 101 by 360 degrees, and a treatment room 15 that irradiates beam 101 to a patient.

[0003] When the beam 101 is transported using the rotating gantry 114, in order to efficiently adjust the beam in the rotating gantry 114, it is necessary to keep the current value of the electromagnets in the rotating gantry 114 constant with respect to the rotation of the rotating gantry 114. For this reason, it is common to set the beam size, beam divergence angle, and emittance at the entrance of the rotating gantry 114 to the same values ​​in the horizontal and vertical directions.

[0004] The synchrotron 112 described above has a beam injection adjustment device 116, a beam converging device 117, a beam deflection device 118, and a beam extraction adjustment device 119, with the beam injection adjustment device 116 connected to the injector 111 and the beam extraction adjustment device 119 connected to the beam transport system 113. The beam transport system 113 is configured to have the beam converging device 117 and the beam deflection device 118, as well as a scatterer 120 described below. Furthermore, the rotating gantry 114 is configured to have the beam deflection device 118 and the beam converging device 117. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4639401 Summary of the Invention [Problem to be solved by the invention]

[0006] It is important for the particle beam therapy device 100 to shorten the device adjustment period from facility construction to the start of treatment. The emittance of the beam 101 extracted from the synchrotron 112 is smaller in the horizontal direction than in the vertical direction, but in order to improve the efficiency of beam adjustment in the rotating gantry 114, the horizontal and vertical emittances must be made uniform. For this reason, currently, a scatterer 120 is installed on the beam transport system 113 from the exit of the synchrotron 112 to the entrance of the rotating gantry 114, and the horizontal emittance is increased to match the vertical emittance while the vertical emittance is not changed, thereby making the horizontal and vertical emittances uniform.

[0007] However, the use of the scatterer 120 increases the total value of the horizontal and vertical emittances, which increases the beam size and makes it more likely that beam loss will occur during transport from the exit of the synchrotron 112 to the entrance of the rotating gantry 114. To prevent this, it takes a long time to adjust the beam in the beam transport system 113.

[0008] An embodiment of the present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a particle beam therapy device that can reduce beam loss in the beam transport system from the synchrotron to the rotating gantry and can efficiently perform beam adjustment at the rotating gantry. [Means for solving the problem]

[0009] A particle beam therapy device in an embodiment of the present invention includes an injector that generates and initially accelerates a beam, a synchrotron that injects the beam from the injector and accelerates and decelerates the beam, a rotating gantry that adjusts the direction of irradiation of the beam to a patient, and a beam transport system that transports the beam from the synchrotron to the rotating gantry, wherein the beam transport system is characterized in that it is configured with an emittance adjustment device that can use an electromagnetic field to correlate the movement of the beam in two different directions, that is, the direction of travel, the horizontal direction, and the vertical direction, so that the sum of the emittance in the horizontal direction and the vertical direction is constant when the beam moves in the direction of travel, a horizontal direction perpendicular to the direction of travel, and a vertical direction perpendicular to the direction of travel and the horizontal direction. Effect of the Invention

[0010] According to the embodiment of the present invention, it is possible to reduce beam loss in the beam transport system from the synchrotron to the rotating gantry, and to efficiently perform beam adjustment in the rotating gantry. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a particle beam therapy system according to a first embodiment. [Diagram 2] FIG. 11 is a schematic diagram showing the configuration of a particle beam therapy system according to a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram showing the configuration of a particle beam therapy system according to a third embodiment. [Figure 4] FIG. 1 is a schematic diagram showing the configuration of a conventional particle beam therapy device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [A] First embodiment (Fig. 1) Fig. 1 is a schematic diagram of a particle beam therapy system according to the first embodiment. The particle beam therapy system 10 shown in Fig. 1 irradiates a beam 1 of charged particles such as protons to an affected part of a patient to provide treatment, and is configured to include an injector 11, a synchrotron 12, a beam transport system 13, a rotating gantry 14, and a treatment room 15.

[0013] The injector 11 generates the beam 1 and performs initial acceleration of the beam 1, and is connected to a beam injection adjustment device 16 (described later) of the synchrotron 12. The synchrotron 12 injects the beam 1 from the injector 11 via the beam injection adjustment device 16, and accelerates and decelerates the beam 1. The beam transport system 13 is connected to a beam extraction adjustment device 19 (described later) of the synchrotron 12 and the rotating gantry 14, and transports the beam 1 from the synchrotron 12 to the rotating gantry 14. The rotating gantry 14 adjusts the irradiation direction of the beam 1 to a patient in a treatment room 15. The treatment room 15 is connected to the rotating gantry 14, and the beam 1 from the rotating gantry 14 is irradiated to the affected area of ​​the patient.

[0014] As described above, the synchrotron 12, which accelerates and decelerates the beam 1, is configured by installing, in the orbit around which the beam 1 revolves, a beam injection adjustment device 16 that injects the beam 1 into the synchrotron 12, a beam focusing device 17 that focuses the beam 1, a beam deflection device 18 that deflects the direction of travel of the beam 1, a beam extraction adjustment device 19 that extracts the beam 1 to the beam transport system 13, and the like.

[0015] The beam injection adjustment device 16 has an electromagnetic field generating device (not shown) for deflecting the beam 1 and injecting it into the synchrotron 12, and an electromagnetic field generating device (not shown) for generating a bump orbit for merging the injected beam 1 with the beam 1 already orbiting in the circular orbit. This beam injection adjustment device 16 generates a bump orbit that bulges in the horizontal direction, and injects the beam 1 from the injector 11 into this bump orbit for multiple revolutions. Therefore, the beam size of the beam 1 orbiting in the circular orbit of the synchrotron 12 is larger in the horizontal direction than in the vertical direction, and therefore the emittance of the beam 1 is also larger in the horizontal direction than in the vertical direction.

[0016] Here, the horizontal direction is a direction perpendicular to the traveling direction of the beam 1 moving through the particle beam therapy system 10, and the vertical direction is a direction perpendicular to the traveling direction and the horizontal direction.

[0017] The beam focusing device 17 adjusts the tune, which is the number of oscillations of the particles (beam 1) per revolution in the orbit of the synchrotron 12. In the beam focusing device 17, the beam 1 is focused and diverged by a linear force generated by an electromagnetic field. For example, a quadrupole electromagnet or the like is used as the beam focusing device 17. The magnetic field strength of this quadrupole electromagnet becomes stronger as the energy of the beam 1 increases, and becomes weaker as the energy of the beam 1 decreases.

[0018] The beam deflection device 18 changes the traveling direction of the beam 1 and uses an electromagnet or the like that generates a uniform magnetic field. The magnetic field strength of this uniform magnetic field increases as the energy of the beam 1 increases, and decreases as the energy of the beam 1 decreases.

[0019] The beam extraction adjustment device 19 extracts the beam 1 from the synchrotron 12 to the beam transport line 13, and has the following extraction methods: One extraction method is slow extraction, which utilizes the resonance phenomenon to extract the stored beam 1 little by little, and another extraction method is fast extraction, which extracts the stored beam 1 all at once.

[0020] As described above, the beam transport system 13 that transports the beam 1 from the synchrotron 12 to the rotating gantry 14 is configured by sequentially installing the beam focusing device 17, the beam deflection device 18, the emittance adjustment device 20, and the beam focusing device 17 on the transport trajectory of the beam 1. The beam focusing device 17 and the beam deflection device 18 upstream of the emittance adjustment device 20 adjust the beam axis and beam size of the beam 1 transported by the beam transport system 13. This makes it possible for the beam 1 transported by the beam transport system 13 to be accurately irradiated onto the affected part of the patient in the treatment room 15 without any beam loss during transport. The emittance adjustment device 20 and the beam focusing device 17 downstream of the emittance adjustment device 20 will be described in detail later.

[0021] As described above, the rotating gantry 14, which adjusts the irradiation method of the beam 1 to the patient in the treatment room 15, has the beam deflection devices 18 and the beam converging devices 17 arranged alternately on the orbit of the rotating gantry 14 and is configured to be rotatable 360 ​​degrees. By rotating the rotating gantry 14, the irradiation direction of the beam 1 to the patient in the treatment room 15 is adjusted (changed).

[0022] Now, the emittance adjustment device 20 in the beam transport system 13 will be described. The beam 1 moves in the traveling direction, the horizontal direction perpendicular to the traveling direction, and the vertical direction perpendicular to the traveling direction and the horizontal direction within the particle beam therapy device 10 including the beam transport system 13. The emittance adjustment device 20 is configured with skewed quadrupole electromagnets or solenoid electromagnets, and by utilizing the electromagnetic fields generated by these, correlation is imparted to the motions in the traveling direction, horizontal direction, and vertical direction of the beam 1, without making the motions in the two different directions (for example, the horizontal direction and the vertical direction) independent, so that the sum of the emittances in the horizontal direction and the vertical direction is constant.

[0023] Specifically, when the horizontal component of the motion of the beam 1 is X and the vertical component is Y, the vector potential generated by the emittance adjustment device 20 includes a term proportional to (X×Y) in the case of a skewed quadrupole electromagnet, and includes a term proportional to (X×Y) in the case of a solenoid electromagnet. 2 +Y 2 ) Using these terms, the emittance adjustment device 20 correlates the motion in two different directions (e.g., the horizontal and vertical directions) of the traveling direction of the beam 1 so that the sum of the emittances in the horizontal and vertical directions is constant.

[0024] As described above, by providing correlation to the motion of the beam 1 in two different directions among the traveling direction, horizontal direction, and vertical direction so that the sum of the emittances in the horizontal and vertical directions becomes constant, the emittances in the horizontal and vertical directions are adjusted to the same value in the beam transport system 13. Here, the two different directions include the traveling direction and horizontal direction, and the traveling direction and vertical direction, in addition to the horizontal direction and vertical direction described above.

[0025] Next, we will describe the beam focusing device 17 downstream of the emittance adjustment device 20 in the beam transport system 13. This beam focusing device 17 is also composed of a quadrupole electromagnet and the like, similar to the beam focusing device 17 of the synchrotron 12 and the beam focusing device 17 upstream of the beam deflection device 18 in the beam transport system 13. The magnetic field strength of this quadrupole electromagnet increases as the energy of the beam 1 increases, and decreases as the energy of the beam 1 decreases.

[0026] In the beam transport system 13, a beam focusing device 17 is installed downstream of the emittance adjustment device 20, so that the horizontal and vertical beam sizes are adjusted to the same value at the entrance of the rotating gantry 14, and further the horizontal and vertical beam divergence angles are adjusted to the same value. As a result, the current value of the electromagnet in the rotating gantry 14 is set to a constant value regardless of the rotation angle of the rotating gantry 14.

[0027] As configured as above, the first embodiment provides the following advantages (1) to (3). (1) In the beam transport system 13, the emittance adjustment device 20 is configured to use an electromagnetic field to impart correlation to the motion of the beam 1 in two different directions (for example, the horizontal and vertical directions) among the traveling direction of the beam 1 and the horizontal and vertical directions so that the sum of the emittances in the horizontal and vertical directions is constant. Therefore, in the beam transport system 13, the emittances in the horizontal and vertical directions can be adjusted to the same value. As a result, the emittances at the entrance of the rotating gantry 14 can be aligned in the horizontal and vertical directions, so that the rotating gantry 14 does not need to adjust the beam axis and beam size for each rotation angle. Therefore, the beam adjustment of the rotating gantry 14 can be performed efficiently.

[0028] (2) In the emittance adjustment device 20 of the beam transport line 13, the sum of the horizontal and vertical emittances is kept constant, so that the total value of the horizontal and vertical emittances can be reduced compared to the case of the conventional scatterer 120 (Fig. 4). As a result, the beam size can be reduced in the beam transport line 13, so that the beam loss in the beam transport line 13 can be reduced and the adjustment time for the beam size, etc. to reduce the beam loss in the beam transport line 13 can be shortened.

[0029] (3) In the beam transport system 13, a beam converging device 17 is installed downstream of the emittance adjustment device 20, which adjusts the horizontal and vertical beam sizes and further the horizontal and vertical beam divergence angles to the same values ​​at the entrance of the rotating gantry 14. Therefore, the current value of the electromagnet in the rotating gantry 14 is set to a constant value regardless of the rotation angle of the rotating gantry 14, so that beam adjustment in the rotating gantry 14 can be performed efficiently without having to be performed for each rotation angle.

[0030] [B] Second embodiment (Fig. 2) 2 is a schematic diagram of a particle beam therapy device according to a second embodiment. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be simplified or omitted.

[0031] The particle beam therapy system 25 of the second embodiment differs from the first embodiment in that a beam parameter measuring device 27 for measuring beam parameters is installed downstream of the emittance adjustment device 20 and upstream of the beam focusing device 17 in the beam transport system 26. Furthermore, no electromagnetic field generating device that affects the beam 1 is installed between the emittance adjustment device 20 and the beam parameter measuring device 27.

[0032] Here, the beam parameters include the Twiss parameter representing the beam size and beam divergence angle, in addition to the emittance of the beam 1. Also, the measurement method by which the beam parameter measuring device 27 measures the beam parameters includes the Q scan method, the slit scan method, and the like.

[0033] As configured as above, the second embodiment achieves the following effects (4) and (5) in addition to the effects (1) to (3) of the first embodiment.

[0034] (4) By installing the beam parameter measuring device 27 downstream of the emittance adjustment device 20, the beam parameters can be measured by the beam parameter measuring device 27 immediately after the emittance is adjusted by the emittance adjustment device 20. Therefore, it can be immediately confirmed whether the magnetic field strength generated by the emittance adjustment device 20 is set to an optimal value, and the beam adjustment in the beam transport line 26 can be efficiently performed.

[0035] (5) Since no electromagnetic field generating device that affects the beam 1 is installed between the emittance adjustment device 20 and the beam parameter measurement device 27, the beam parameter measurement device 27 can measure the beam parameters of the beam 1 whose emittance has been adjusted by the emittance adjustment device 20 without being affected by any equipment other than the emittance adjustment device 20. Therefore, the results of the emittance adjustment by the emittance adjustment device 20 can be efficiently confirmed.

[0036] [C] Third embodiment (FIG. 3) 3 is a schematic diagram of a particle beam therapy device according to a third embodiment. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be simplified or omitted.

[0037] The particle beam therapy system 30 of the third embodiment differs from the first embodiment in that a beam parameter measuring device 32 that measures beam parameters is installed in the beam transport system 31 upstream of the emittance adjustment device 20 and downstream of the beam deflection device 18.

[0038] Here, the beam parameters include the Twiss parameter representing the beam size and beam divergence angle, in addition to the emittance of the beam 1. Also, the measurement method by which the beam parameter measurement device 32 measures the beam parameters includes the Q scan method, the slit scan method, and the like.

[0039] As configured as above, the third embodiment provides the following effect (6) in addition to the effects (1) to (3) of the first embodiment.

[0040] (6) By installing the beam parameter measurement device 32 upstream of the emittance adjustment device 20, the beam parameter measurement device 32 can measure the beam parameters of the beam 1 immediately before the emittance is adjusted by the emittance adjustment device 20. This makes it possible to theoretically easily estimate the optimal value of the magnetic field strength generated by the emittance adjustment device 20, and therefore makes it possible to efficiently perform beam adjustment in the beam transport line 31.

[0041] Although several embodiments of the present invention have been described above, 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, substitutions, changes, and combinations can be made without departing from the spirit of the invention. Furthermore, these substitutions, changes, and combinations are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0042] 1...beam, 10...particle beam therapy device, 11...injector, 12...synchrotron, 13...beam transport system, 14...rotating gantry, 17...beam focusing device, 20...emittance adjustment device, 25...particle beam therapy device, 26...beam transport system, 27...beam parameter measurement device, 30...particle beam therapy device, 31...beam transport system, 32...beam parameter measurement device

Claims

1. A particle beam therapy device having an injector that generates and initially accelerates a beam, a synchrotron that injects the beam from the injector and accelerates and decelerates the beam, a rotating gantry that adjusts the irradiation direction of the beam to a patient, and a beam transport system that transports the beam from the synchrotron to the rotating gantry, a beam transport system for adjusting the beam length in a direction perpendicular to the beam propagation direction, a horizontal direction perpendicular to the beam propagation direction, and a vertical direction perpendicular to the beam propagation direction and the horizontal direction; and a beam transport system for adjusting the beam length in a direction perpendicular to the beam propagation direction and the horizontal direction.

2. The emittance adjustment device is configured to include a skewed quadrupole electromagnet or a solenoid electromagnet, When the horizontal component of the beam motion is X and the vertical component is Y, the term in which the vector potential generated by the skew quadrupole electromagnet is proportional to (X × Y) is expressed as the term in which the vector potential generated by the solenoid electromagnet is proportional to (X ２ +Y ２ ), 2. The particle beam therapy device according to claim 1, characterized in that these terms are configured to provide a correlation between the beam propagation direction and motion in two different directions, the horizontal direction and the vertical direction, so that the sum of the emittances in the horizontal and vertical directions is constant.

3. 2. The particle beam therapy system according to claim 1, wherein the beam transport system is configured to have a beam converging device for adjusting a beam size and a beam divergence angle downstream of an emittance adjusting device.

4. 4. The particle beam therapy device according to claim 1, wherein the beam transport system is configured to include a beam parameter measuring device downstream of the emittance adjusting device, the beam parameter measuring device measuring beam parameters including emittance.

5. 4. The particle beam therapy device according to claim 1, wherein the beam transport system is configured to include a beam parameter measuring device that measures beam parameters including emittance, upstream of the emittance adjusting device.

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