KR20180060243A - Transport lines of compact-tridactyl high energy beam with minimal quadrupole magnets for Acceleator-Boron Neutron Capture Therapy - Google Patents

Abstract

The present invention relates to a compact high-energy beam transmission line, branched into three sub-lines, for a boron-neutron capturing treatment device based on a proton accelerator. The beam transmission line, guiding a beam to a plurality of targets (50) located on a shielding wall (40), comprises: a matching means (A) which matches a beam to a straight or curved section; achromat means (B, B′) which are branched from the matching means and remove changes of a horizontal direction location and a size of the beam caused by dispersion; beam extending means (C, C′) which are extended from the achromat means (B, B′), respectively, and generate a large and uniform distribution in a horizontal direction of the beam; and a beam extension means (C′) which is extended from the matching means (A) and generates a large and uniform distribution in the horizontal direction of the beam. In general, a matching structure requires four to five quadrupole electromagnets, but the number of quadrupole electromagnets is reduced to three by using properties of the beam transmitted by a DTL in the present invention. The number of quadrupole, which is 20 commonly required by a high-energy beam transmission line branched into three sub-lines and comprises a beam extension device, is reduced to 11 by removing a matching structure needed between an achromat and the beam extension device by using a corner effect of the achromat. Accordingly, costs for constructing the treatment device are significantly reduced by reducing the required total length of the beam transmission line. In addition, the effort for designing a dipole electromagnet is reduced since the whole structure is simplified. The compact high-energy beam transmission line has an extraordinary advantage of being capable of controlling the beam in an easy manner, during the operation, compared to a common beam line and thus is a useful invention.

Description

[0001] The present invention relates to a three-branched, compact high energy beam transmission line for a boron-neutron capture therapy based on a proton accelerator,

The present invention relates to the design of a three-way branched high energy beam transmission line for operating three treatment rooms using a proton accelerator based boron-neutron capture therapy apparatus, and more particularly, to a matching structure, achromat) and beam expander to meet the three requirements of the three-branch branching, the chromatic aberration problem in the bending process, and the generation of a large and uniform lateral distribution required by the treatment machine, while simultaneously using the minimum matching structure and the electromagnet To a three-way branched high energy beam transmission line for a boron-neutron capture therapy device based on a proton accelerator.

Unlike conventional small particle accelerators that collide particles with cancer cells and remove cancer cells by using the heat generated by the boron-neutron capture therapy device, the drug is administered to the patient and the drug is reacted with the neutron to generate heat .

In the case of the boron-neutron capture therapy, the boron drug makes cancer cells come into contact, and only the drug reacts with the neutrons. The damage to normal cells can be minimized compared with the conventional method.

In such a treatment facility, it is advantageous to have more than two treatment rooms to increase the number of acceptable patients, and the neutrons necessary for the boron-neutron capture therapy are generated by colliding a proton beam accelerated with a particle accelerator to the target, The beamline for transmitting the accelerated high energy proton beam must be branched off after the accelerating device by the number of necessary treatment rooms.

Such a branching method is also used in a research facility that already uses another proton accelerator as shown in Non-Patent Document 1.

In order to branch the beam transmission line, a fin section that advances after the beam is horizontally bent and a straight section that directly uses the beam that is advanced straight is required. In the case of the fin section, one or more bipolar electromagnets are used to progress the beam Bend the direction.

Generally, particles in the particle beam have different energies near the reference energy. Therefore, when the beam passes through the bipolar electromagnet, there is a difference in the degree of warping depending on the energy, so that the position or size of the beam in the lateral direction is desired It changes in the form that it does not. In particular, since the acceleration in the accelerator is not always constant, the beam always has energy jitter, which causes a risk of generating a large amount of radiation by colliding the beam with the tube, , There is a possibility of reducing treatment efficiency by reducing the yield of neutrons.

A structure called achromat is used to eliminate the lateral positional change and size change due to such dispersion (see Non-Patent Document 2).

A beam transmission line of Non-Patent Document 1 is shown in Fig. FIG. 1 shows a schematic view of a conventional beam transmission line used for three-fold branching of a beam transmission line, in which three two-pole electromagnets are used for the acromat construction, one and four four poles An additional electromagnet is inserted. Since a large number of such electromagnets increase the cost of constructing the accelerator, it is necessary to reduce the number of electromagnets that can be used when constructing accelerators for industrial or medical purposes.

Acromat can be composed of 2-pole electromagnets and 2-pole electromagnets in the form of 2-pole electromagnets, 4-pole electromagnets and 2-pole electromagnets. However, when two electromagnets and one quadrupole electromagnet are used, When the beam is bent in the horizontal direction, the beam must be focused in the horizontal direction in order to remove the chromatic aberration. In this process, the beam is strongly spread in the vertical direction, and the vertical direction property It will fall out. For this reason, two or more quadruple electromagnets are often used as in Non-Patent Document 1.

In the case of boron-neutron capture therapy, it is not appropriate to use Gaussian, which is a general lateral distribution of the beam, and to rebalance the distribution in a large and uniform form Because of the high proton beam power required to generate sufficient neutrons for treatment, small lateral dimensions can cause the problem of melting the target and the size of the incoming proton beam is large enough to treat large lesions at one time There is a need.

In order to minimize the heat problem for a given lateral dimension, uniform distribution is required instead of a central concentration of particles such as Gaussian, The effect of shortening the time can also be invoked.

Generally, a beam expander is used to generate a large and uniform lateral distribution. The structure using a beam expander is generally composed of two or more quadrupole electromagnets and two eight-pole electromagnets as in Non-Patent Document 3. [

The two quadrupole electromagnets converge the beam in the horizontal and vertical directions, respectively. After passing through the focal point due to the strong focusing, the vertical and horizontal sizes of the beam rapidly increase. In this process, The extreme electromagnets deform the phase space of the beam through the third order nonlinear magnetic field component so that the particles located outside of the beam are pushed to the center to uniformly resize the entire distribution.

Such a structure can be constituted by one quadrupole electromagnet and one eight-pole electromagnet as shown in Non-Patent Document 4 in the case of controlling only the vertical or horizontal direction, but in the case of controlling both the vertical and horizontal directions, It is difficult to satisfy the size of the beam at the required target while controlling the beam so as not to collide with the vacuum tube. In order to avoid this, It is general to control the beam by using two or more quadruple electromagnets as in the case of Patent Document 3.

Special-purpose structures, such as the acromat and beam expander mentioned above, require specific properties for the incoming beam in order to perform their function, and two different specimens, such as a branched-boron-neutron capture device, If the beamline needs to be beamed or one beam can be used in both the straight section and the warped section, it is necessary to adjust the conditions required by the respective structures so that the beams passing through the previous structure are satisfied. The same process is called matching (see the matching of non-patent document 5).

There are two types of properties of the transverse beam, namely, size and divergence. Since the horizontal and vertical directions have two properties, there is a need to adjust four transverse directions in total . Thus, in the case of typical matching, four quadrupole electromagnets are used to adjust all four properties or to increase the degree of freedom.

In Fig. 1, it can be seen that four quadrupole electromagnets are inserted in order to match the acromat starting from the AC magnet to the previous beam line (see Non-Patent Document 1), and in Non-Patent Document 3 shown in Fig. 2 From the acromat to the beam expander, five quadrupole electromagnets are inserted to perform matching with the beam transmission.

In order to construct a high-energy beam transmission line of a boron-neutron capturing apparatus branched by a triple branch using a generally known method as described above, a straight line section is formed by a straight line section and a fin section, Since the section requires a matching structure with acromat and a beam expander, it requires about 20 quadrupole electromagnets and at the same time requires a large space for the quadrupole electromagnets, there was.

Non-Patent Document 1: In-Seok Hong et al., In Proceedings of European Particle                Accelerator Conference 2008, THPP093, p3581 Non-Patent Document 2: Helmut Wiedemann, Particle Accelerator Physics 3rd ed., ISBN-13 978-3-540-49043-2, P397 Non-Patent Document 3: Sang-Pil Yun et al., In Proceedings of International Parallel Accelerator Conference 2012, WEPPD033, p2579 Non-Patent Document 4: Yosuke Yuri et al., PRSTAB 10, 104001 (2007) Non-Patent Document 5: Helmut Wiedemann, Particle Accelerator Physics 3rd ed., ISBN-13 978-3-540-49043-2, p264

The present invention has been made to solve the various drawbacks and problems caused by the conventional beam transmission line in consideration of the above-mentioned problems. The object of the present invention is to overcome the problem of chromatic aberration and energy tremble by using the simplest acromat, And the matching structure using a quadrupole electromagnet that matches both the fin section and the straight section with the section before the high energy beam transmission line is used for the boron-neutron capturing treatment A three-way branched high energy beam transmission line for a proton accelerator based boron-neutron capture therapy device that simplifies the high energy beam transmission line required for a high energy beam transmission line, .

In order to accomplish the above object, a three-branched, high-energy beam transmission line for boron-neutron capture therapy based on the proton accelerator of the present invention includes a plurality of targets 50 located in a shielding wall 40, A beam transmission line for guiding a beam, comprising: a matching means (A) for matching a beam to a straight line and a bent line; and a beam splitter for splitting at the matching means (A) Beam expanding means (C, C ") for producing a large and uniform lateral distribution of the beam leading to each of the acom- matic means (B, B '), And a beam expanding means (C ') leading to a means (A) for producing a large and uniform lateral distribution of the beam.

The present invention reduces the number of matching structures required between acromat and beam expander by reducing the number of matching structures requiring four to five quadrupole electromagnets to three by utilizing beam characteristics from DTL and utilizing the edge effect of acromat To reduce the number of 20 quadrupole electromagnets required in a three-branch high-energy beam transmission line including a beam expander to 11, thereby reducing the length of the required total beam transmission line, And the overall structure is simplified, thereby reducing the design burden of the bipolar electromagnet and facilitating beam adjustment during operation as compared with a normal beam line.

1 is a schematic view of a conventional beam transmission line,
2 is a view showing transmission distribution of conventional 20 MeV and 100 MeV proton beam lines,
3 is a schematic diagram of a three-pronged, compact high energy beam transmission line for a boron-neutron capture therapy device based on the present invention proton accelerator,
4 shows a lateral distribution (right) of the beam immediately after the DTL structure (left) and a lateral distribution (right) after a further 50 cm,
FIG. 5 is a graph showing a result of a computer simulation showing a lateral size variation of a beam during the traveling of the high energy beam transmission line shown in FIG. 3;
FIG. 6 is a diagram showing the lateral distribution of the beam before (above) and after passing (below) the high energy beam transmission line shown in FIG.

Hereinafter, a preferred embodiment of a three-branched branched high energy beam transmission line for a boron-neutron capture therapy apparatus based on the proton accelerator of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a schematic diagram of a three-pronged compact high energy beam transmission line for boron-neutron capture therapy based on the proton accelerator of the present invention, FIG. 4 is a schematic diagram of a lateral distribution (left) FIG. 5 is a graph showing a result of a computer simulation showing the lateral size variation of the beam during the traveling of the high energy beam transmission line shown in FIG. 3, and FIG. 6 1 shows a lateral distribution of the beam before (above) and after passing through (below) the high energy beam transmission line, in which the three-way for boron-neutron capture therapy based on the present invention proton accelerator The branched, compact high energy beam transmission line is a beam transmission line for guiding a beam to a plurality of targets 50 located in the shielding wall 40. The beam transmission line includes matching means A for matching the beam to a straight line and a bent line, , The above- (B, B ') branching at a step (A) and eliminating a change in the lateral position and size of the beam due to a disperion, and each of the acromat means (B, B') (C, C ") leading to a large, uniform lateral distribution of the beam leading to said matching means (A) and a beam expanding means (C ') leading to a large, .

The matching means (A) has a configuration in which three quadrupole electromagnets (10) are arranged in a straight line at regular intervals.

Each of the acromat means B and B 'has a configuration in which one quadrupole electromagnet is arranged between the bipolar electromagnet 20 and the bipolar electromagnet 20' which are shared.

The two quadrupole electromagnets 10 and two eight-pole electromagnets 30 are arranged in the order of the quadrupole electromagnets 10 and the eight-pole electromagnets 30 in the order of the beam expanding means C, C ', C " Alternately arranged.

Hereinafter, the operation of a three-branched, compact high energy beam transmission line for the boron-neutron capture therapy apparatus based on the present invention of the present invention will be described in detail.

A focusing / defocusing (FODO) structure is generally used to adjust the beam through a drift tube linac (DTL) structure for acceleration. The beams passing through the FODO (focusing / defocusing) structure are similar in beam size in the horizontal and vertical directions as shown in the left drawing of FIG. 4. However, as shown in the right drawing of FIG. 4, But spread in the other direction. This is similar to what happens when a typical circular beam passes through a quadrupole electromagnet.

Therefore, by using such a beam as it is, it is possible to adjust the lateral property of the beam in a comparatively wide range with only three quadruple electromagnets 10, thereby satisfying the beam property required by the beam expanding means C, C ', C " The distance between the quadrupole electromagnets 10 is not critical when the distance between the quadrupole electromagnets 10 is more than 10 cm, so it is adjusted according to the installation conditions of the other devices required for the beam transmission line. (B, B ') at the entrance to meet the requirements of the beam expanding means (C, C', C ") in the optimization code A beam transfer matrix is used to predict the beam state at the entrance of the acromat means B, B 'according to the quadrupole electromagnet 10 intensity.

The acromat means B and B 'have a structure of a bipolar electromagnet 20, a quadrupole electromagnet 10 and a bipolar electromagnet 20' as shown in Fig. 3 for removing chromatic aberration. The structure of each of the entire acromat means B and B 'is symmetrical with respect to the quadrupole electromagnet 10 and the distance between the bipolar electromagnets 20 and 20' and the quadrupole electromagnet 10 is a quadrupole electromagnet 10 ). The distance between the vacuum tube of the straight section and the quadrupole electromagnet 10 is sufficiently increased so as not to physically overlap. As the distance increases, the required strength of the quadrupole electromagnet 10 drops, and the angle between the edges of the bipolar electromagnets 20 and 20 'and the advancing direction of the beam can be changed according to the intensity.

3, the beam is bent by 20 to 30 degrees with the bipolar electromagnet 20, the distance between the bipolar electromagnets 20 and 20 'and the quadrupole electromagnet 10 is set to 0.8 to 1.2 m, (20, 20 '), which is simple and simple, using 5 ~ 5.4 T / m.

The beams adjusted through the matching means A and the acromat means B and B 'are directly incident on the beam expanding means C, C' and C ", and the beam expanding means C, C and C ' The first quadrupole electromagnet 10 of the first quadrupole electromagnet 10 focuses the beam in the vertical / horizontal direction and places the first 8 pole electromagnet 30 at the focus point to perform horizontal / vertical beam adjustment.

Thereafter, the beam is again enlarged in the vertical / horizontal direction, and the beam is re-focused in the remaining direction, i.e., in the horizontal / vertical direction, by using the second quadrupole electromagnet 10 of the beam expanding means C, C, The beam is accelerated at a higher speed in the conventional vertical / horizontal direction. [0044] A second 8-pole electromagnet 30 is placed at a focus point created by the second quadrupole electromagnet 10, As shown in FIG.

At this time, since the size of the beam is larger in the second quadrupole electromagnet 10, the beam spreads faster than the first quadrupole electromagnet 10, and the size of the two beams is changed equally in the target 50 position. The entire process can be confirmed from the result of computer simulation showing the beam size change along the high energy beam transmission line shown in FIG.

The transverse distribution changes adjusted through the 8-pole electromagnet 30 of the beam expanding means C, C and C ", as can be seen from the computational simulation results of Fig. 6, show that the distribution of the initial Gaussian form is uniform Distribution.

While the present invention has been described with reference to the preferred embodiments, it is to be understood that the invention is not limited thereto and that various changes and modifications may be made therein without departing from the scope of the invention.

10: Four pole electromagnet 20, 20 ': Two pole electromagnet
30: 8 pole Electromagnet 40: Shielding wall
50: Target A: matching means
B, B ': acromat means C, C', C ": beam expanding means

Claims (5)

A beam transmission line for guiding a beam to a plurality of targets (50) located in a shielding wall (40), comprising: a matching means (A) for matching a beam to a straight and a bent region; (B, B ') for eliminating the lateral positional change and the size change of the beam due to the disperion, and each of the acromat means (B, B' (C, C ") for generating a direction distribution and a beam expanding means (C ') for generating a large and uniform lateral distribution of the beam in succession to said matching means (A) A three-pronged, compact high-energy beam transmission line for neutron capture therapy. 2. The proton accelerator-based boron-neutron capture device according to claim 1, wherein the matching means (A) comprises three quadrupole electromagnets (10) arranged in a straight line at regular intervals. A branched high energy beam transmission line. [3] The apparatus according to claim 1, wherein each of the acromat means B and B 'has a configuration in which one quadrupole electromagnet is arranged between a shared dipole electromagnet 20 and a dipole electromagnet 20' A three-prong branched high energy beam transmission line for boron-neutron capture therapy based on proton accelerators. The electromagnet according to claim 3, wherein each of the acromat means B and B 'is formed by bending the beam 20 to 30 degrees with the bipolar electromagnet 20 and between the bipolar electromagnets 20 and 20' And a quadrupole electromagnet (10) having a strength of 5 to 5.4 T / m, wherein the distance between the quadrupole electromagnet (10) and the quadrupole electromagnet (10) is in the range of 0.8 to 1.2 m. Beam transmission line. 2. The apparatus of claim 1, wherein each of the beam expanding means (C, C ', C ") comprises two quadrupole electromagnets (10) and two quadrupole electromagnets (30) 30). The proton accelerator-based boron-neutron capture therapy apparatus is a three-way branched high energy beam transmission line.

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