JP2001210498A - Accelerator system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To irradiate correct position at medical treatment in the treatment room. SOLUTION: Although beam was attenuated by installing an attenuator in a low energy beam transport system in the past, an attenuator 9 (making beam pass through by making a pinhole on a cutoff plate cutting the beam off) is installed to a high-energy beam transport system, and attenuate the strength of beam (number of charged particles or current value) without lowering the beam energy. The attenuated beam becomes to have the same orbit center as the orbit center of full beam, and confirmative irradiation is done before the medical treatment by this beam. On the occasion of full beam radiation at medical treatment, it is enabled to have a radiation with high-accuracy because the obit of full beam becomes equal to the beam orbit adjusted by the attenuated beam beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accelerator system for transporting charged particles such as ions and electrons by accelerating them with an electromagnetic field or the like, and more particularly to an accelerator system for attenuating a beam of charged particles. Such an accelerator system includes a medical accelerator device, an accelerator device for physical experiments and industrial experiments, an SOR for semiconductor manufacturing, and the like, and is mainly used for a medical accelerator device particularly from the viewpoint of the need for an attenuated beam.

[0002]

2. Description of the Related Art Among accelerator devices for accelerating charged particles, a so-called attenuated beam whose intensity (particle number or current value) is extremely lower than that of a normally used charged particle beam, such as a medical device, is known. May be used. For example, in the case of a medical device, it is necessary to change the intensity of the beam emitted from the accelerator device according to the treatment, and it has that function. In the case of a medical accelerator device that has a rotating gantry, all beam transport systems cannot be adjusted due to its structure. The final confirmation of the beam is required.

However, if there is a difference other than the intensity between the attenuated beam and the beam actually used (hereinafter, referred to as a full beam), it is useless for confirmation even though the irradiation is for confirmation. Here, the difference other than the intensity refers to the trajectory (beam trajectory) through which the beam passes, the beam position at the final target point, and the like. Therefore, not only is it necessary to lower the beam intensity of the attenuated beam from the full beam, but also reproducibility is required for the beam trajectory and position.

In the case of a conventional medical accelerator device, it is common to use a method of attenuating a beam before it is incident on an accelerator (such as a synchrotron) for accelerating the beam, that is, an incident system (LEBT system). . As this document, the National Institute of Radiological Sciences, “Comprehensive Report on Construction of Heavy Ion Beam Therapy System” (NIRS-M-109HI) issued in May 1995
MAC-009), which is described in “3.

The configuration of such a medical accelerator device is a general configuration and will be described with reference to the drawings. FIG. 14 is a configuration diagram showing a configuration example of a conventional medical accelerator device. In the figure, 1 is an injector for generating and pre-accelerating a beam of electrons and ions, and 2 is a low energy beam transport system (hereinafter referred to as LEBT) for transporting the beam generated and pre-accelerated by the injector 1 to a synchrotron 4. (Low Energy Beam Transf
er) system, 100 is an attenuator that cuts off a part of the beam to lower the beam intensity, and 3 is a bending electromagnet provided in the LEBT system 2.

Reference numeral 4 denotes a synchrotron for accelerating the beam to a predetermined energy, and reference numeral 5 denotes a high energy beam transport system (hereinafter referred to as HEBT (High Energy Energy Transport System) for transporting the beam accelerated by the synchrotron 4 to a treatment room 13 for irradiating a patient.
Beam transfer) system, 6 is a quadrupole electromagnet provided in the HEBT system 5 for diverging and converging beams, and 7 is an HE magnet.
A bending electromagnet provided in the BT system 5, a monitor 8 for measuring the position and distribution of the beam, a neutron shutter 10 for blocking the beam and neutrons, a rotating gantry 11 for changing the angle of irradiation to the patient, and a reference numeral 12 An irradiation device for shaping and irradiating the beam with the shape of the affected part of the patient, and a treatment room 13 for irradiating the patient.

Next, the operation will be described. First, the flow of the beam will be described. The beam generated and pre-accelerated by the injector 1 is transported by the LEBT system 2. At this time, the light is deflected along the beam line by the deflection electromagnet 3 and is incident on the synchrotron 4. Although omitted in the figure, HEBT
An electromagnet similar to the quadrupole electromagnet 6 provided in the system 5 is provided to diffuse and converge the beam. Although not shown in the drawing, a steering electromagnet for correcting the beam trajectory is also provided, and the beam is adjusted so as to be transported through a predetermined trajectory.

[0008] The beam transported to the synchrotron 4 is incident on the ring of the synchrotron 4 and then accelerated to a predetermined energy. The accelerated beam is emitted from the synchrotron 4 to the HEBT system 5 by an emission device. Beam emitted from synchrotron 4 is HEBT
It is transported by the system 5, and at this time, it is deflected along the beam line by the deflection electromagnet 7 and transported to the irradiation device 12.
At this time, the beam is diffused and converged by the quadrupole electromagnet 6 as in the LEBT system 2. Although omitted in the figure, a steering electromagnet is also provided similarly to the LEBT system 2,
The beam trajectory is also modified. The beam transported to the irradiation device 12 is shaped and irradiated according to the shape of the affected part to be irradiated.

Next, the procedure for the treatment irradiation will be described. First, since the injector 1 and the LEBT system 2 are operated under constant conditions irrespective of the energy accelerated by the synchrotron 4, if adjustments are made in advance, even if the energy changes for each patient, adjustments are made. No need to fix. It is the synchrotron 4 and the HEBT system 5 whose operation is changed by energy. The setting of the irradiation device is changed for each patient, but a detailed description is omitted because it is not directly related to the present invention.

The operation of the synchrotron 4 and the HEBT system 5 is changed depending on the energy used for irradiation.
Adjustments are made before the treatment is delivered. This adjustment is performed in the treatment room 13
This is performed in parallel with the operation of fixing the patient and the operation of positioning the affected part at a predetermined position. As a method of adjustment, the neutron shutter 10 for cutting off the beam is closed, and the HEBT is irradiated with the beam on the neutron shutter 10.
The trajectory of the beam, the distribution of the beam, and the like are measured by a monitor 8 appropriately provided in the system 5. If the beam trajectory needs to be corrected here, the beam trajectory is corrected by changing the excitation of a steering electromagnet (not shown) provided in the HEBT system 5.

Thus, the HE up to the neutron shutter 10
Correction of the beam trajectory of the BT system 5 is performed to adjust the trajectory to a normal trajectory, and then treatment irradiation is performed. However, the beam line inside the rotating gantry 11 downstream of the neutron shutter 10 must be adjusted before treatment. Can not do. For this reason, after the neutron shutter 10 is opened, the extremely attenuated beam is transported to the irradiation device 12 before the treatment irradiation, and the beam is measured by the monitor 8 provided inside the irradiation device 12 for correct measurement. It is necessary to confirm that it is transported in the beam orbit. This attenuated beam is created by inserting the attenuator 100 provided in the LEBT system 2 into the beam line and blocking most of the beam.

FIG. 15 shows the structure of the attenuator 100. In the figure, 20 is a vacuum chamber, 21 is a blocking plate for blocking a beam, 22 is a shaft connected to the blocking plate 21,
Reference numeral 23 denotes a guide for guiding the movement of the shaft 22, and reference numeral 24 denotes a bellows attached to the vacuum chamber 20 for flexibly moving the shaft up and down while maintaining a vacuum. FIG. 16 shows an example of the structure of the blocking plate 21. Here, a slit A101 having a vertical slot and a slit B102 having a horizontal slot are overlapped to form a lattice.

When the beam is to be attenuated, the bellows is pushed down by a drive mechanism provided outside the bellows 24, and the blocking plate 21 is inserted into the beam line. The beam emitted from the injector hits the blocking plate 21 and the slit A10
The beam passes through the portion where both the slot 1 and the slot B102 overlap, but the beam is cut off in other portions. Because most of the beam is cut off in this way,
As a result, the beam incident on the synchrotron 4 decreases according to the amount of the beam cut off by the attenuator 100.
This is accelerated by the synchrotron 4, and the intensity of the emitted beam is similarly reduced. As a result, the intensity of the beam transported to the irradiation device 12 is lower than that of the full beam.

However, according to this conventional technique, the attenuated beam is a state in which the beam itself incident on the synchrotron is attenuated, that is, the number of charged particles incident thereon is smaller than that of the full beam. Is different from that of the full beam, and the emission position and the emission angle of the beam may change due to the influence of the space charge effect or the like. In this case, there is a problem because the beam trajectory in the HEBT system that transports the emitted beam is different from the case of the full beam.

This will be described with reference to FIG. FIG. 17 schematically shows the behavior of the beam in the HEBT system. The beam is diffused to the maximum at the position of the quadrupole electromagnet 6, but is bent in the direction of convergence by the magnetic field of the quadrupole electromagnet 6, becomes a focus at the next intermediate position of the quadrupole electromagnet 6, and then spread again. Transport is performed by repeating such beam divergence and convergence operations.

Since the beam trajectory is adjusted by the steering electromagnet up to the neutron shutter 10 as shown in the above-mentioned procedure, the beam passes through the normal beam trajectory. However, if the emission position and the emission angle are different from those of the full beam at the time of the attenuated beam before irradiation, thereafter, as shown in the drawing, the beam does not pass through the orbit adjusted by the full beam but passes through a shifted orbit. In addition, it can be seen that the beam also has a large diffusion, and has different characteristics from the full beam.

Accordingly, the portion of the HEBT system which is not adjusted every time after the neutron shutter 10 is set with good reproducibility, and the attenuated beam is used to confirm that the beam is transported correctly. Regardless, if the beam passes through a beam trajectory different from that of the full beam or has a different distribution, an error occurs even in a state where the HEBT system is correctly set, so that the accuracy of the confirmation itself is reduced, and in the worst case, the HEBT system is confirmed. Will no longer make sense.

[0018]

As described above, in the case of a medical accelerator device, since there is a portion where the beam trajectory cannot be adjusted every time, such as inside a rotating gantry, an attenuated beam is delivered to the treatment room 13 before treatment irradiation. By introducing and measuring the beam position at the position of the irradiation device, it is necessary to confirm that the portion that cannot be adjusted each time is set and excited with good reproducibility.

For this reason, although the attenuated beam and the full beam need to reach the irradiation equipment with good reproducibility,
In the case of the conventional accelerator device, since the beam intensity is reduced by providing an attenuator in the LEBT system, the operating conditions of the synchrotron change, and as a result, the position and the emission angle of the beam emitted from the synchrotron are changed. It may change from the case of full beam. In this case, even if the HEBT system is correctly set and excited, differences appear in the beam trajectory, diffusion, and convergence when transported by the HEBT system, and appear as deviations in the beam position and changes in the beam distribution confirmed at the irradiation equipment position. As a result, there is a problem that the accuracy of confirmation is reduced.

It is also possible to project an attenuated beam at the end of the beam adjustment of the HEBT system while applying the beam to the neutron shutter, measure the beam trajectory, and predict the beam trajectory and distribution after the neutron shutter. However, this is a problem because it also includes an error.

The present invention has been made to solve the above-mentioned problems, and an accelerator capable of improving the reproducibility of an attenuated beam by irradiating an attenuated beam passing through the same beam trajectory as a full beam. The aim is to get the system.

[0022]

(1) An accelerator according to claim 1 of the present invention includes a circular accelerator for accelerating charged particles incident thereon and an irradiation device for irradiating a charged particle beam accelerated by the circular accelerator. An accelerator system having a beam transport system for transporting, wherein an attenuation means for attenuating the beam intensity of the charged particles is provided in the beam transport system.

(2) In the accelerator system according to the first aspect, the attenuation means is means for passing a part of the charged particle beam.

(3) In the accelerator system according to the second aspect, the damping means is means for passing the charged particle beam only near the center of the orbit of the charged particle beam.

(4) In the accelerator system according to the third aspect, the attenuating means may be a blocking plate having a hole provided near the center of the trajectory of the charged particle beam, or near the center of the trajectory of the charged particle beam. The attenuating means uses a blocking plate having a cross-shaped groove provided in the above, and the charged particle beam is attenuated by passing through the hole or the cross-shaped groove of the blocking plate.

(5) In the accelerator system according to the second aspect, the damping means includes a blocking plate having a donut-shaped slot having substantially the same center as the center of the orbit of the charged particle beam, and the center of the orbit of the charged particle beam. A damping means using a blocking plate provided with a plurality of donut-shaped slots on a concentric circle having substantially the same center as the above, a blocking plate having a grid-shaped slot, or a shielding plate in which a plurality of holes are arbitrarily arranged The charged particle beam is attenuated by passing through the slot or hole of the blocking plate.

(6) Further, in an accelerator system having a circular accelerator for accelerating the charged particles incident thereon and a beam transport system for transporting the charged particle beam accelerated by the circular accelerator to an irradiation device, Attenuating means for attenuating the beam intensity is provided on each of the upstream side and the downstream side in the beam transport system, and the upstream attenuating means is means for passing a part of the charged particle beam, and the downstream attenuating means is When the beam transport in the beam transport system is transported in a normal orbit, the charged particle beam that has passed through the upstream attenuating means is allowed to pass. This is an attenuating means for cutting off part or all of the charged particle beam that has passed.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing the first embodiment. In FIG. 1, reference numeral 1 denotes an injector for generating beams such as electrons and ions for pre-acceleration, 2 denotes a LEBT system for transporting the beam generated and pre-accelerated by the injector 1 to a synchrotron, and 3 denotes a LEBT system 2. It is a provided bending electromagnet.

4 is a synchrotron for accelerating the beam to a predetermined energy, and 5 is an HE for transporting the beam accelerated by the synchrotron 4 to a treatment room 13 for irradiating a patient.
The BT system 6 is used to diffuse the beam provided in the HEBT system 5.
A quadrupole electromagnet that performs convergence, 7 is a bending electromagnet provided in the HEBT system 5, 8a, 8b, and 8c are monitors for measuring the position and intensity of the beam and its distribution, and 9 is a part that cuts off a part of the beam. The attenuator 10 for lowering the beam intensity (particle number or current value) by passing other beams without attenuating the energy of the beam itself, the beam 10 was cut off, and the beam was cut off by the attenuator 9. Neutron shutter for blocking neutrons generated in the event, 11
Denotes a rotating gantry for changing the angle of irradiation on the patient, 12 denotes an irradiation device for shaping the beam in accordance with the shape of the affected part of the patient, and 13 denotes a treatment room for irradiating the patient.

Next, the operation will be described. First, the flow of the beam will be described. The beam generated and pre-accelerated by the injector 1 is transported by the LEBT system 2. At this time, the light is deflected along the beam line by the deflection electromagnet 3 and is incident on the synchrotron 4. Although omitted in the figure, HEBT
An electromagnet similar to the quadrupole electromagnet 6 provided in the system 5 is provided to diffuse and converge the beam. Although not shown in the drawing, a steering electromagnet for correcting the beam trajectory is also provided, and the beam is adjusted so as to be transported through a predetermined trajectory.

The beam transported to the synchrotron 4 is incident on the ring of the synchrotron 4 and then accelerated to a predetermined energy. The accelerated beam is emitted from the synchrotron 4 to the HEBT system 5 by an emission device. Beam emitted from synchrotron 4 is HEBT
It is transported by the system 5, and at this time, it is deflected along the beam line by the deflection electromagnet 7 and transported to the irradiation device 12.
At this time, the beam is diffused and converged by the quadrupole electromagnet 6 as in the LEBT system 2. Although omitted in the figure, a steering electromagnet is also provided similarly to the LEBT system 2,
The beam trajectory is also modified. The beam transported to the irradiation device 12 is shaped and irradiated according to the shape of the affected part to be irradiated.

Next, the procedure for treatment irradiation will be described. First, since the injector 1 and the LEBT system 2 are operated under constant conditions irrespective of the energy accelerated by the synchrotron 4, if the adjustment is made in advance, even if the energy changes for each patient, the adjustment can be performed. No need to fix. Synchrotron 4 changes operation depending on energy
And HEBT system 5. The setting of the irradiation device is changed for each patient, but a detailed description is omitted because it is not directly related to the present invention.

The operation of the synchrotron 4 and the HEBT system 5 is changed according to the energy used for irradiation.
Adjustments are made before the treatment is delivered. This adjustment is performed in the treatment room 13
This is performed in parallel with the operation of fixing the patient and the operation of positioning the affected part at a predetermined position. As a method of adjustment, the neutron shutter 10 for cutting off the beam is closed, and the HEBT is irradiated with the beam on the neutron shutter 10.
The trajectory of the beam, the distribution of the beam, and the like are measured by monitors 8a and 8b appropriately provided in the system 5. Here, if the beam trajectory needs to be corrected, the beam trajectory is corrected by changing the excitation of the steering electromagnet provided in the HEBT system 5.

In this way, the beam trajectory of the HEBT system 5 up to the neutron shutter 10 is corrected to adjust the trajectory to the normal trajectory, and then the therapeutic irradiation is performed. The rotating gantry 11 downstream from the neutron shutter 10 is used. The internal beam line cannot perform pre-treatment adjustments. For that reason,
After opening the neutron shutter 10, transport the extremely attenuated beam to the irradiation device 12 before treatment irradiation,
A monitor 8c provided inside the irradiation device 12 with the beam
It is necessary to confirm that it is transported in the correct beam trajectory by measuring with. This attenuated beam is produced by inserting an attenuator 9 provided in the HEBT system 5 into a beam line and blocking most of the beam, unlike the conventional technique.

FIG. 2 shows an example of the structure of the attenuator 9. In the figure, 20 is a vacuum chamber, 31 is a blocking plate for blocking a beam, 22 is a shaft connected to the blocking plate 31, 23
Denotes a guide for guiding the movement of the shaft 22, and 24 denotes a bellows attached to the vacuum chamber 20 for flexibly moving the shaft 22 up and down while maintaining a vacuum. Here, a small hole is formed in the shielding plate 31 at a portion corresponding to the center of the beam trajectory during insertion.

The beam transported from the upstream is the shielding plate 3
In the case of 1, the beam passes through only the portion of the hole opened at the center of the beam orbit, and the other portions are blocked. As a result, the amount of the beam blocked downstream of the attenuator 9 decreases in accordance with the amount of the beam blocked, and the beam transported to the irradiation device 12 has a lower intensity than the full beam.

Next, the beam trajectory will be described with reference to the drawings. FIG. 3 schematically shows the behavior of the beam when transported by the HEBT system according to the first embodiment. The beam spreads to the maximum at the position of the quadrupole magnet 6, but is bent in the direction of convergence by the magnetic field of the quadrupole electromagnet 6, becomes a focus at the next intermediate position of the quadrupole electromagnet, and thereafter spread again. Transport is performed by repeating such beam diffusion and convergence operations.

As to the beam trajectory in the case of the full beam, the adjustment by the steering electromagnet is performed every time up to the neutron shutter 10 as shown in the above procedure, so that the beam passes through the normal beam trajectory as in the prior art. . However, in the case of an attenuated beam performed before irradiation thereafter, it differs from the prior art. Since the attenuator 9 is provided in the HEBT system 5, even when the beam is attenuated, the synchrotron 4 is used.
Is operated under the same operating conditions as in the beam adjustment, that is, under the full beam, so that the emitted beam is transported to the position of the attenuator 9 through the same orbit as in the beam adjustment.

The beam is adjusted so that the center of the monitor 8a coincides with the center of the beam when the beam is adjusted, so that the center of the beam is also adjusted at the attenuator 9 provided immediately downstream. 31 at the center,
The beam passing through the attenuator 9 passes through the same orbit as in the case of the full beam, as shown in the figure. As for the spread of the beam, only the central portion of the full beam passes through the attenuator 9, so that the beam has a narrower distribution than the full beam.

By providing the HEBT system 5 with the attenuator 9 having a hole only at the center as described above, the trajectory of the attenuated beam can be made the same as the full beam, and the reliability of confirming the attenuated beam before irradiation is improved. It is possible.

Although the attenuator 9 is disposed immediately downstream of the monitor 8a, the same effect can be obtained by arranging the attenuator 9 immediately upstream or at a portion where a normal beam trajectory is obtained during beam adjustment.

The blocking plate 31 of the attenuator 9 has a hole at the center. However, a blocking plate 31a having a cross-shaped slot as shown in FIG. 4 or a donut as shown in FIG. The same effect can be obtained by using a member that allows a part of the beam to pass, such as a blocking plate 31b having a slot in the shape.

Further, in the first embodiment, the case where one irradiation room 13 for treating one synchrotron 4 is shown, but the present invention is not limited to this. It may be a deployed accelerator system. In this case, an attenuator 9 may be provided in the beam transport system after branching to each irradiation chamber, or an attenuator 9 may be provided in a beam transport system of a common part up to a branch point to each irradiation chamber. In these cases, the same effects as those in the first embodiment can be obtained. As an example of these, FIG. 6 shows a case where an attenuator 9 is provided in the beam transport system after branching.
FIG. 7 shows a case where the attenuator 9 is provided in the beam transport system of the common part up to the branch point. Further, the method of providing the attenuator 9 is not limited to these. Further, FIGS. 6 and 7 show a case where there are three irradiation rooms for performing the treatment, but it goes without saying that two irradiation rooms or four or more irradiation rooms may be provided.

Further, in the first embodiment, the neutron shutter 10 is provided, and the beam is adjusted while the beam is applied to the neutron shutter 10. HEBT
The attenuator according to the present invention can be applied if the system 5 is configured to be capable of performing beam adjustment or if the device stability is such that beam adjustment is unnecessary.

In FIG. 1, the attenuator 9 is connected to the rotating gantry 1
1 is disposed between the quadrupole electromagnet 6 and the neutron shutter 10 immediately before, but if the HEBT system 5 is used, it may be disposed further upstream. When the influence of neutrons is dealt with without providing the neutron shutter 10, the neutron shutter 10 may be provided in the HEBT system 5 in the rotating gantry 11. The arrangement positions of these attenuators 9 can be similarly applied to Embodiments 2, 3, and 4 described below.

In FIG. 3, the attenuator 9 may be moved back and forth. The size of the hole of the blocking plate may be determined according to the spread (beam cross-sectional area) of the full beam at the moved installation position. Note that, even when the attenuator 9 is installed at the position of the full beam focal point shown in FIG. 3, the aperture of the blocking plate 31 shown in FIG. 2 may be made smaller according to the size of the focal point.

Embodiment 2 In the first embodiment, the attenuated beam is generated by using one attenuator 9.
It uses two or more attenuators. FIG. 8 shows a configuration diagram in the second embodiment. Each component in the figure is the same as that shown in FIG. 8, the second embodiment differs from FIG. 1 in that a second attenuator 91 is provided immediately upstream of the monitor 8b upstream of the neutron shutter 10. In the example of FIG. 8, the attenuator 91 has the same structure as the attenuator 9 shown in FIG. 2, and the shielding plate 21 has a small hole at the center of the beam orbit.

Next, the operation will be described. In FIG. 8, the flow of the beam from when the beam is generated and pre-accelerated by the injector 1 and transported to the treatment room 13 is the same as in the first embodiment. The difference is in the method of generating the attenuated beam in the treatment irradiation procedure. The attenuators 9 and 91 are provided at two locations immediately downstream of the upstream monitor 8a and immediately upstream of the downstream monitor 8b. When an attenuated beam is generated, the two attenuators 9 and 91 are connected to a beam line. Insert

Next, the beam trajectory will be described with reference to the drawings. FIG. 9 schematically shows the behavior of a beam when transported by the HEBT system according to the second embodiment. The behavior at the time of full beam is the same as that of the first embodiment shown in FIG. In the case of an attenuated beam, the behavior is basically the same. However, since the attenuators 9 and 91 are provided at two locations, the attenuator 91 on the downstream side is required if the beam orbit does not pass as normal. Can not pass through.

Therefore, if the beam trajectory changes due to a change in the apparatus between the state in which the beam adjustment of the HEBT system 5 is performed and the state in which the irradiation with the attenuated beam is confirmed, the downstream attenuator is used. The beam cannot pass through 91. That is, only when the beam orbit is correct, the downstream attenuator 9
If the position is shifted by the monitor 8c inside the irradiation device 12 during irradiation of the attenuated beam, it is understood that the problem is caused by the downstream attenuator 91 and thereafter. For this reason, the second downstream attenuator 91 functions as a filter.

Conversely, when the beam is not transported to the irradiation device 12 or when there is a partial omission, it is understood that there is a problem upstream of the attenuator 91. Here, the case where the beam trajectory changes due to a change in the apparatus here means that, for example, when there is a long time from the beam adjustment of the HEBT system 5 to the confirmation of the attenuated beam, the temperature change of the electromagnet of the HEBT system 5 occurs. And the beam trajectory changes.

As described above, also in the second embodiment, the same effect as in the first embodiment can be obtained. Further, by installing the attenuator at two locations, the downstream attenuator 91 is provided.
Irradiation device 1 if the beam trajectory upstream is not in a normal state
Since it is not transported up to 2, the accuracy of the attenuation beam confirmation is improved. Further, when an abnormality occurs, it is possible to determine whether the abnormality is upstream or downstream of the attenuator 91, so that it is possible to shorten a treatment time when an abnormality occurs and improve an operation rate of the apparatus.

Here, the attenuators 9 and 91 are arranged immediately downstream of the upstream monitor 8a and immediately upstream of the downstream monitor 8b, respectively. The same effect is achieved by arranging the parts. For example, in FIG. 9, the position of the second downstream attenuator 91 may be any position as long as it is downstream of the attenuator 9. In the case of an arbitrary position, the diameter of the hole of the shielding plate 31 shown in FIG. 2 is the same as the diameter of the attenuation beam indicated by the dotted line in FIG. 3 at the arbitrary position.

The shielding plates 31 of the attenuators 9 and 91 are perforated at the center, but have a cross-shaped slot as shown in FIG. 4 or a donut-shaped as shown in FIG. The same effect can be obtained by using a device that allows a part of the beam to pass through, such as a type having a slot.

Further, in the second embodiment, the case where one irradiation room 13 for performing the treatment for one synchrotron is shown. However, even in the case of an accelerator device having a plurality of treatment rooms 13, Either the attenuators 9 and 91 are provided after branching to the respective treatment rooms 13 (see FIG. 6 of the first embodiment), or the attenuators 9 and 91 are provided at a common portion from the synchrotron outlet to the first branch to the treatment room 13 A similar effect can be obtained by a method such as providing 91 (see FIG. 7 of the first embodiment).

Further, in the first embodiment, the neutron shutter 10 is provided, and the beam is adjusted while the beam is applied to the neutron shutter 10. HEBT
The effect of the present invention can be obtained if the system 5 is configured to be able to perform beam adjustment or if the device stability is such that beam adjustment is unnecessary.

Embodiment 3 Although only the portion near the center of the beam is passed by the attenuator 9 in the first embodiment, the entire beam may be attenuated. Here, the attenuation of the entire beam is such that the trajectory of the beam before being attenuated (diffusion / convergence shape of the beam) and the trajectory of the beam after attenuated are substantially the same, and the energy of the beam is not changed and the beam energy is not changed. It attenuates the intensity (particle number or current value).

FIG. 10 shows a configuration diagram in the third embodiment. In the figure, each component is the same as that shown in FIG. 10 differs from FIG. 1 in the first embodiment in that the type of the attenuator 92 is different from that of the attenuator 9 in the first embodiment.

Next, the operation will be described. In FIG. 10, the beam is generated and pre-accelerated by the injector 1 so that the treatment room 13
The flow of the beam until it is transported to is the same as in the first embodiment. The difference is in the method of generating the attenuated beam in the treatment irradiation procedure. In the attenuator 9 according to the first embodiment, a type that passes only a portion near the center of the beam as shown in FIG. 2 or FIGS. 4 and 5 is used.
In the attenuator 92 according to the third embodiment, the lattice type shown in FIG. 16 described in the related art is used.

Next, the beam trajectory will be described with reference to the drawings. FIG. 11 schematically shows the behavior of a beam when transported by the HEBT system according to the third embodiment. The behavior at the time of full beam is the same as that of the first embodiment shown in FIG. However, in the case of an attenuated beam, the beam only passes through the slot of the grid on the grid-shaped blocking plate, but the beam spreads slightly at that time, so the distribution is wider than the full beam as shown in the figure However, since the beam trajectory is the same as in the case of the full beam, no displacement occurs even if the measurement is performed by the monitor 8c inside the irradiation device 12. Therefore, if the settings after the neutron shutter 10 are correct, the attenuated beam is transported through a regular orbit, and the accuracy of the attenuated beam confirmation is improved.

As described above, also in the third embodiment, the same effect as in the first embodiment can be obtained. Also, by using the lattice-like attenuator 92, it is possible to generate an attenuated beam without largely changing the beam distribution, so that it is not necessary to change the design of the monitors 8a, 8b, 8c. The above effects can be easily obtained.

Here, the attenuator 92 is arranged immediately downstream of the monitor 8a. However, the same effect can be obtained by arranging the attenuator 92 immediately upstream and in a portion where a regular beam trajectory is obtained during beam adjustment. Further, the barrier plate 31 of the attenuator 92 has a lattice shape, but a barrier plate 31c of a type in which small holes are uniformly provided as shown in FIG. 12 or a donut shape having a different diameter as shown in FIG. The same effect can be obtained by using a type in which the entire beam is attenuated, such as a blocking plate 31d having a combination of slots.

In the third embodiment, one irradiation room 13 for performing treatment on one synchrotron is shown. However, even in the case of an accelerator apparatus having a plurality of treatment rooms 13, A similar effect can be obtained by providing an attenuator 92 at a common portion up to a branch point to each treatment room 13.

In the first embodiment, the neutron shutter 10 is provided, and the beam is adjusted with the beam applied to the neutron shutter 10. HEBT
The attenuator according to the present invention can be applied if the system 5 is configured to be capable of performing beam adjustment or if the device stability is such that beam adjustment is unnecessary.

Embodiment 4 In the first to third embodiments, a synchrotron is used as an accelerator. However, a cyclotron may be used. That is, the present invention can be applied to a case where a circular accelerator such as a synchrotron or a cyclotron is used.

[0066]

As described above, according to the present invention, a beam transport system for transporting a charged particle beam accelerated by a circular acceleration to an irradiation device is provided with an attenuating means for attenuating the beam intensity of the charged particle beam. As a result, the accelerator can be operated in the same state with the full beam and the attenuated beam, so that an attenuated beam having the same orbit as the full beam can be obtained, and a highly reliable accelerator system can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an accelerator system according to Embodiment 1 of the present invention.

FIG. 2 is a structural diagram of an attenuator according to Embodiment 1 of the present invention.

FIG. 3 is a diagram showing a beam trajectory according to the first embodiment of the present invention.

FIG. 4 is a structural diagram of a blocking plate according to Embodiment 1 of the present invention.

FIG. 5 is a structural diagram of a blocking plate according to Embodiment 1 of the present invention.

FIG. 6 is a configuration diagram of an accelerator system when there are a plurality of treatment rooms according to Embodiment 1 of the present invention.

FIG. 7 is a configuration diagram of an accelerator system when there are a plurality of treatment rooms according to Embodiment 1 of the present invention.

FIG. 8 is a configuration diagram of an accelerator system according to Embodiment 2 of the present invention.

FIG. 9 is a diagram showing a beam trajectory according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram of an accelerator system according to Embodiment 3 of the present invention.

FIG. 11 is a diagram showing a beam trajectory according to a third embodiment of the present invention.

FIG. 12 is a structural diagram of a blocking plate according to Embodiment 3 of the present invention.

FIG. 13 is a structural diagram of a blocking plate according to Embodiment 3 of the present invention.

FIG. 14 is a configuration diagram of a conventional accelerator.

FIG. 15 is a structural diagram of a conventional attenuator.

FIG. 16 is a structural view of a conventional blocking plate.

FIG. 17 is a diagram showing a conventional beam trajectory.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Injector 2 Low energy beam transport system 3 Bending electromagnet 4 Synchrotron 5 High energy beam transport system 6 Quadrupole magnet 7 Bending electromagnet 8, 8a, 8b,
8c monitor 9, 91, 92 attenuator (attenuating means) 10 neutron shutter 11 rotating gantry 12 irradiation equipment 13 treatment room 13a course 1 treatment room 13b course 2 treatment room 13c course 3 treatment room 14 low-energy beam transport system quadrupole electromagnet 18a course 1 selection bending electromagnet 18b Course 2 selection bending electromagnet 18c Course 3 selection bending electromagnet 20 Vacuum chamber 21, 31, 3
1a to 31d Blocking plate 22 Shaft 23 Guide 24 Bellows 30 Low energy beam transport system deflection electromagnet 60 High energy beam transport system quadrupole electromagnet 61 Course 1 Quadrupole electromagnet 62 Course 2
Quadrupole electromagnet 63 Course 3 quadrupole electromagnet 101 Slit A 102 Slit B

Claims (6)

[Claims] 1. An accelerator system comprising: a circular accelerator for accelerating an incident charged particle; and a beam transport system for transporting a charged particle beam accelerated by the circular accelerator to an irradiation device, wherein a beam intensity of the charged particle is adjusted. An accelerator system, wherein a damping means for damping is provided in the beam transport system. 2. The accelerator system according to claim 1, wherein the attenuation means is means for passing a part of the charged particle beam. 3. The accelerator system according to claim 2, wherein the attenuating means is means for passing the charged particle beam only near the center of the orbit of the charged particle beam. 4. The accelerator system according to claim 3, wherein the damping means is provided in a blocking plate having a hole provided near a center of the trajectory of the charged particle beam, or provided near a center of the trajectory of the charged particle beam. An accelerator system comprising: an attenuating means using a blocking plate having a cross-shaped groove, wherein the charged particle beam is attenuated by passing through the hole or the cross-shaped groove of the blocking plate. 5. The accelerator system according to claim 2, wherein said damping means has a donut-shaped slot having substantially the same center as the center of the trajectory of the charged particle beam.
A blocking plate provided with a plurality of donut-shaped slots having concentric circles having substantially the same center as the orbital center of the charged particle beam,
A blocking plate having a lattice-shaped slot, or an attenuating means using a blocking plate in which a plurality of holes are arbitrarily arranged, so that the charged particle beam is attenuated by passing through the slot or hole of the blocking plate. An accelerator system characterized in that: 6. An accelerator system comprising: a circular accelerator for accelerating an incident charged particle; and a beam transport system for transporting a charged particle beam accelerated by the circular accelerator to an irradiation device, wherein a beam intensity of the charged particle is reduced. Attenuating means for attenuating is provided on each of the upstream side and the downstream side in the beam transport system, the upstream attenuating means is a means for passing a part of the charged particle beam, and the downstream attenuating means is a beam transport system. If the beam is transported in a normal orbit, the charged particle beam passed through the upstream attenuation means is passed.If the beam is not transported in a normal orbit, the charged particle beam is transmitted through the upstream attenuation means. An accelerator system comprising a damping means for cutting off a part or all of a particle beam.