Deflection magnet system capable of supporting multi-angle isocenter irradiation, realizing parallel beam bidirectional scanning and having boundary focusing effect

Abstract

The invention discloses a deflection magnet system supporting multi-angle isocenter irradiation, capable of realizing parallel beam bidirectional scanning and having a boundary focusing effect. The deflection magnet system comprises a deflection magnet A (1) having an edge focusing effect and three deflection magnets B (2) having an edge focusing effect in a group, the deflection magnet B (2) has an edge focusing effect, the deflection magnet C (3) has an edge focusing effect, the deflection magnet A (1) is responsible for enabling a particle beam A (100) incident along a Y axis to deviate from the Y axis, and the deflection magnet B (2), the deflection magnet C (3) and the deflection magnet D (4) are combined to realize parallel beam bidirectional scanning; the four magnets can rotate with the Y axis as the axis, and multi-angle equal-axis irradiation is achieved. The special structures processed on the magnetic pole edges of the four magnets generate a focusing effect on particle beams, and can replace a special quadrupole focusing magnet.

Description

Technical Field

[0001] The present invention relates to particle radiotherapy, in particular to multi-angle rotational irradiation therapy, and is limited to the field of scanning irradiation therapy. The particles may be light ions such as protons or heavy ions such as carbon ions. Background Art

[0002] Previously, the inventor applied for a series of invention patents (Type I to III) for "a magnet system in a particle beam multi-angle bidirectional scanning irradiation mechanism", all of which were applied to fixed racks. The common feature of these patents is that the bidirectional scanning particle beams emitted from the final deflection magnet are parallel to each other, which the inventor calls parallel beam bidirectional scanning.

[0003] Parallel beam bidirectional scanning has two advantages: 1. Push the virtual point light source to infinity to maximize the focus-to-skin ratio; 2. The width of the radiation field in the X-axis direction (see the patent drawing) can be spliced ​​and extended by moving the treatment bed or treatment chair.

[0004] If parallel beam bidirectional scanning is applied to a rotating gantry, there are two additional advantages: 1. The arrangement of the final deflection magnet does not need to consider the source wheelbase problem, but only the treatment space. The final deflection magnet can be placed as close to the gantry rotation axis as possible to reduce the radius of the rotating gantry.

[0005] 2. A structure capable of focusing the particle beam can be made on two sets of deflection magnets whose deflection directions are perpendicular to each other, thereby replacing the four-stage focusing magnets and related equipment in the rotating frame and shortening the axial length of the rotating frame.

[0006] The reduction of radial and axial dimensions is conducive to reducing the volume of the rotating frame, reducing its weight and lowering its cost. Summary of the invention

[0007] The present invention aims at solving the problem that the current rotating gantry-style particle radiotherapy system is bulky. The invention uses a parallel beam bidirectional scanning magnet system with edge focusing effect after modification in the rotating gantry. The radial dimension of the rotating gantry is reduced while the axial dimension of the rotating gantry is reduced, thereby achieving the purpose of reducing the volume of the rotating gantry. The main contents are: A deflection magnet A is set. In the initial state, a rectangular coordinate system composed of an X-axis, a Y-axis and a Z-axis is referred to, and the magnetic pole surfaces of the two magnetic poles A are mirror-symmetric with respect to the YZ plane. The function of the deflection magnet A is to deviate the particle beam A incident along the Y-axis toward the origin of the rectangular coordinate system upward from the XY plane in the YZ plane, and a structure capable of generating edge focusing force is processed on the end face of the magnetic pole A, where the particle beam A is incident and the particle beam C is emitted.

[0008] Furthermore, a group of three deflection magnets B is provided, which are located between the deflection magnet A and the coordinate origin. The magnetic pole faces of the two magnetic poles in each of the three groups are perpendicular to the YZ plane and are mirror-symmetric with respect to the particle beam C. The function of the deflection magnets B is to scan the parallel beam in the direction parallel to the X-axis. Among the three deflection magnets B, the deflection magnets B1 and B2 are responsible for scanning on one side of the extension line of the particle beam C, so that the particle beam E emitted from the deflection magnet B2 is parallel to the particle beam C; the deflection magnets B2 and B3 are responsible for scanning on the other side of the extension line of the particle beam C, so that the particle beam E emitted from the deflection magnet B3 is parallel to the particle beam C. By controlling the angles between the boundary normals of the deflection magnets B1, B2 and B3 and the incident and outgoing particle beams, an edge focusing force is generated.

[0009] Furthermore, a deflection magnet C is set up and located between a group of three deflection magnets B and the coordinate origin. The magnetic pole surfaces of its two magnetic poles C are mirror-symmetric relative to the YZ plane. Its function is to be responsible for parallel beam scanning in the Y-axis direction together with the deflection magnet D set up next. At the position where the particle beam E enters the magnetic pole C of the deflection magnet C, a structure that can generate edge focusing force is processed. At the end face of the deflection magnet C where the particle beam G exits, the angle between the boundary normal and the exiting particle beam G is controlled to generate edge focusing force.

[0010] Furthermore, a deflection magnet D is set and located between the deflection magnet C and the coordinate origin. The magnetic pole surfaces of its two poles D are mirror-symmetric relative to the YZ plane. Its function is to be responsible for parallel beam scanning in the Y-axis direction together with the deflection magnet C, so that the particle beams I emitted from the deflection magnet D are parallel to each other and perpendicular to the Y-axis. When the particle beam G enters the end face of the magnetic pole D of the deflection magnet D, the angle between the boundary normal and the incident particle beam G is controlled to generate edge focusing force.

[0011] Furthermore, a particle beam detection system is set up, wherein an ionization chamber A is located at the particle beam outlet end of the deflection magnet A, and is used to measure the axial line position of the particle beam C, and provide the deflection magnet A with beam steering parameters in the YZ plane; an ionization chamber B is located at the particle beam outlet end of the deflection magnet D, and is used to measure the axial line position and dose of the particle beam I, wherein the axial line position parameter is a beam steering parameter in the X-axis direction provided by a group of three deflection magnets B.

[0012] The above-arranged deflection magnet A, a group of three deflection magnets B, deflection magnet C, deflection magnet D and particle beam detection system can rotate with the rectangular coordinate system with the Y axis as the axis to achieve multi-angle isocenter irradiation. Among them, the combination of a group of three deflection magnets B, deflection magnet C and deflection magnet D can achieve parallel beam bidirectional scanning; the edge focusing structure processed on the deflection magnet A, a group of three deflection magnets B, deflection magnet C and deflection magnet D can produce a focusing effect on the deflected and emitted particle beams, and can replace the dedicated four-stage focusing magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 , Deflection magnet layout Figure 2 , magnetic poles and detection system layout Figure 3 , Schematic diagram of the rotation of the deflection magnet system Figure 4 , one Schematic diagram of parallel beam scanning with three deflection magnets B Figure 5 , one Schematic diagram of parallel beam bidirectional scanning with three deflection magnets B, C and D Figure 6 , Schematic diagram of the boundary normal of deflection magnet A Figure 7 , one Schematic diagram of the boundary normal of the three deflection magnets B. Figure 8 , one Schematic diagram of the boundary normal of the three deflection magnets B (part 2) Fig. 9 , Schematic diagram of the boundary normal of deflection magnet C Fig.10 , Schematic diagram of the boundary normal of deflection magnet D Symbols in the figure: 0. The origin of the X-axis, Y-axis, and Z-axis rectangular coordinate system 1. A deflection magnet A 1-1. Two magnetic poles A 2. A set of three deflection magnets B 2-1. Deflection magnet BA 2-1-1, Two magnetic poles BA 2-2. Deflection magnet BB 2-2-1. Two magnetic poles BB 2-3. Deflection magnet BC 2-3-1. Two magnetic poles BC 3. Deflection magnet C 3-1. Two magnetic poles C 4. Deflection magnet D 4-1. Two magnetic poles D 5. Detection system 5-1. Ionization chamber A 5-2. Ionization chamber B 100. Particle beam A incident on deflection magnet A 200. Arc-shaped particle beam B deflected between the poles of deflection magnet A 300. Particle beam C emitted from deflection magnet A 400. A particle beam D running between the poles of three deflection magnets B 411. Arc-shaped particle beam DAA deflected between the magnetic poles of the deflection magnet BA 412. Particle beam DAB emitted from deflection magnet BA 413. Arc-shaped particle beam DAC deflected between the magnetic poles of the deflection magnet BB 421. Arc-shaped particle beam DBA deflected between the magnetic poles of the deflection magnet BB 422. Particle beam DBB emitted from deflection magnet BB 423. Arc-shaped particle beam DBC deflected between the poles of the deflection magnet BC 500. Particle beam E emitted from three deflection magnets B 600. Arc-shaped particle beam F deflected between the poles of deflection magnet C 700. Particle beam G emitted from deflection magnet C 800, deflection magnet D deflects arc-shaped particle beam H between magnetic poles 900. Particle beam I emitted from deflection magnet D 1001. The boundary normal AA of the particle beam A incident on the boundary position of the magnetic pole of the deflection magnet A 1002. Boundary normal AB at the boundary position of magnetic pole A of particle beam C exiting deflection magnet A 1010. The center of the arc particle beam B is A 2110, the center of the arc particle beam DAA BAA 2111、Boundary normal BAAA of particle beam C incident on end face of magnetic pole BA 2112. The boundary normal BAAB of the particle beam DAB exiting from the magnetic pole BA 2120, the center of the arc particle beam DAC BAB 2121、Boundary normal BABA of particle beam DAB incident on end face of magnetic pole BB 2122, particle beam E from the magnetic pole BB end surface boundary normal BABB 2220, the center of the arc particle beam DBA BBB 2221, particle beam C incident on the boundary normal BBBA of the end face of magnetic pole BB 2222, particle beam DBB is emitted from the magnetic pole BB, and the boundary normal BBBB 2230, the center of the arc particle beam DBC BBC 2231、Boundary normal BBCA of particle beam DBB incident on end face of magnetic pole BC 2232, particle beam E from the magnetic pole BC end surface boundary normal BBCB 3001. The boundary normal line CA of the particle beam E incident on the boundary position of the magnetic pole of the deflection magnet C 3002, particle beam G from the magnetic pole C magnetic pole end surface boundary normal CB 3010, the center C of the arc particle beam F 4001. The particle beam G is incident on the boundary normal line D of the magnetic pole end face of the deflection magnet D. 4010, the center D of the arc particle beam H DETAILED DESCRIPTION

[0014] In order to simplify the description and make the features of the present invention clear and easy to understand, reference is made to a rectangular coordinate system consisting of an X-axis, a Y-axis and a Z-axis to indicate the orientation of the components based on the drawings. The rectangular coordinate system can be rotated with the present embodiment about the Y-axis as the axis, and when indicating the orientation of the components, the specific embodiment of the present invention is in an initial state.

[0015] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Without violating the scope of the present invention, the present invention is not limited by the specific embodiments disclosed below.

[0016] This embodiment is a deflection magnet system that supports multi-angle isocenter irradiation, realizes parallel beam bidirectional scanning and has a boundary focusing effect.

[0017] like Figure 1 As shown, this embodiment includes, along the Y-axis direction, relative to the coordinate origin 0, arranged from far to near, a deflection magnet A1, a group of three deflection magnets B2, a deflection magnet C3 and a deflection magnet D4.

[0018] like Figure 2 As shown, the pole surfaces of the two poles A1 - 1 of the deflection magnet A1 are mirror-symmetric relative to the YZ plane, and their function is to deviate the particle beam A100 incident along the Y axis toward the origin 0 of the rectangular coordinate system upward from the XY plane in the YZ plane.

[0019] Figure 2 In the figure, in order to see the arc-shaped particle beam B200 deflected between the two magnetic poles A1-1, the magnetic pole facing the reader is hidden.

[0020] like Figure 2As shown, the pole faces of the three groups of two poles in each group of the three deflection magnets B2 are perpendicular to the YZ plane and are mirror-symmetric with respect to the particle beam C300. Their function is to perform parallel beam scanning in a plane perpendicular to the YZ plane and containing the particle beam C300 in a direction parallel to the X-axis. Among the three deflection magnets B2, the deflection magnet BA2-1 is close to the deflection magnet A1, the deflection magnet BC2-3 is close to the coordinate origin 0, and the deflection magnet BB2-2 is in the center.

[0021] like Figure 3 As shown, the pole faces of the three deflection magnets B2 are all isosceles triangles, with their bases parallel to the particle beam C300, the bases of the pole faces of the deflection magnet BA2-1 pole BA2-1-1 and the bases of the pole faces of the deflection magnet BC2-3 pole BC2-3-1 are located on the same side of the extension line of the particle beam C300, and the bases of the pole faces of the deflection magnet BB2-2 pole BB2-2-1 are located on the other side of the extension line of the particle beam C300, wherein the deflection magnet BA2-1 and the deflection magnet BB2-2 are responsible for scanning on one side of the extension line of the particle beam C300, so that the particle beam E500 emitted from the deflection magnet BB (2-2) is parallel to the particle beam C300, and the deflection magnet BB2-2 and the deflection magnet BC2-3 are responsible for scanning on the other side of the extension line of the particle beam C300, so that the particle beam E500 emitted from the deflection magnet BC2-3 is parallel to the particle beam C300.

[0022] like Figure 2 As shown, the pole surfaces of the two poles C3 - 1 of the deflection magnet C3 are mirror-symmetric with respect to the YZ plane, and their function is to be responsible for parallel beam scanning in the Y-axis direction together with the deflection magnet D4.

[0023] Figure 2 In the figure, in order to see the arc-shaped particle beam F600 deflected between the two magnetic poles C3-1, the magnetic pole facing the reader is hidden.

[0024] like Figure 2 As shown, the pole surfaces of the two poles D4-1 of the deflection magnet D4 are mirror-symmetric relative to the YZ plane. Their function is to be responsible for parallel beam scanning in the Y-axis direction together with the deflection magnet C3, so that the particle beam I900 emitted from the deflection magnet D4 is parallel to each other and perpendicular to the Y-axis.

[0025] Figure 2 In the figure, in order to see the arc-shaped particle beam H800 deflected between the two magnetic poles D4-1, the magnetic pole facing the reader is hidden.

[0026] like Figure 2As shown, this embodiment also includes a particle beam detection system 5, wherein an ionization chamber A5-1 is located at the particle beam outlet end of the deflection magnet A1, and is used to measure the axial line position of the particle beam C300, and provide the beam steering parameters in the YZ plane for the deflection magnet A1; an ionization chamber B5-2 is located at the particle beam outlet end of the deflection magnet D4, and is used to measure the axial line position and dose of the particle beam I900, wherein the axial line position parameters are the beam steering parameters in the X-axis direction provided by a group of three deflection magnets B2.

[0027] This arrangement enables the deflection magnet A1 to function as a Y-direction guiding magnet, and enables a group of three deflection magnets B2 to function as an X-direction guiding magnet.

[0028] like Figure 4 As shown, the deflection magnet A1, a group of three deflection magnets B2, the deflection magnet C3, the deflection magnet D4 and the particle beam detection system 5 can rotate with the rectangular coordinate system with the Y axis as the axis to achieve multi-angle isocentric irradiation.

[0029] like Figure 2 , Figure 3 and Figure 5 As shown, a combination of a group of three deflection magnets B2, deflection magnet C3 and deflection magnet D4 can realize parallel beam bidirectional scanning, so that the bidirectional scanning particle beams I900 emitted from the deflection magnet D4 are parallel to each other.

[0030] like Figure 6 As shown, at the location where the particle beam A100 enters the magnetic pole A1-1, the end face of the magnetic pole is processed into a narrow slope so that the boundary normal AA1001 at the entrance of the particle beam A100 and the center point A1010 of the deflected arc particle beam B200 between the magnetic poles are located on the same side of the incident particle beam A100.

[0031] The boundary normal AA1001 intersects the incident particle beam A100 and the inter-pole deflected arc particle beam B200 at the end surface of the magnetic pole A1-1, and the same applies below.

[0032] According to the regulations, when the center of the deflected particle beam orbit between the magnetic poles and the normal line of the magnetic pole boundary are on the same side of the incident particle beam, the edge effect of the magnet is focusing, and the same applies below.

[0033] The end face of the magnetic pole A1-1 at the location where the particle beam C300 exits is processed into an inclined surface so that the boundary normal AB1002 at the exit and the center A1010 of the deflected arc particle beam B200 between the magnetic poles are located on the same side of the exit particle beam C300.

[0034] The boundary normal line AB1002 intersects the outgoing particle beam C300 and the inter-pole deflected arc particle beam B200 at the end surface of the magnetic pole A1-1, and the same applies below.

[0035] According to the regulations, when the center of the deflected particle beam orbit between the magnetic poles and the normal line of the magnetic pole boundary are on the same side of the outgoing particle beam, the edge effect of the magnet is focusing, and the same applies below.

[0036] like Figure 7 As shown, in the particle beam path scanned by the deflection magnets BA2-1 and BB2-2: When the particle beam C300 is incident on the boundary of the magnetic pole BA2-1-1, the center BAA2110 of the deflected arc particle beam DAA411 between the boundary normal BAAA2111 and the magnetic pole BA2-1-1 is located on the same side of the incident particle beam C300; When the particle beam DAB412 exits the boundary of the magnetic pole BA2-1-1, the center BAA2110 of the deflected particle beam DAA411 between the boundary normal BAAB2112 and the magnetic pole BA2-1-1 is located on the same side of the exiting particle beam DAB412; When the particle beam DAB412 is incident on the boundary of the magnetic pole BB2-2-1, the center BAB2120 of the deflected particle beam DAC413 between the boundary normal BABA2121 and the magnetic pole BB2-2-1 is located on the same side of the incident particle beam DAB412; When the particle beam E500 exits the boundary of the magnetic pole BB2-2-1, the boundary normal BABB2122 and the center BAB2120 of the deflected particle beam DAC413 between the magnetic pole BB2-2-1 are located on the same side of the exiting particle beam E500.

[0037] like Figure 8 As shown, in the particle beam path scanned by the deflection magnets BB2-2 and BC2-3: When the particle beam C300 is incident on the boundary of the magnetic pole BB2-2-1, the center BBB2220 of the deflected particle beam DBA421 between the boundary normal BBBA2221 and the magnetic pole BB2-2-1 is located on the same side of the incident particle beam C300; When the particle beam DBB422 exits the boundary of the magnetic pole BB2-2-1, the center BBB2220 of the deflected particle beam DBA421 between the boundary normal BBBB2222 and the magnetic pole BB2-2-1 is located on the same side of the exiting particle beam DBB422; When the particle beam DBB422 is incident on the boundary of the magnetic pole BC2-3-1, the center BBC2230 of the deflected particle beam DBC423 between the boundary normal BBCA2231 and the magnetic pole BC2-3-1 is located on the same side of the incident particle beam DBB422; When the particle beam E500 exits the boundary of the magnetic pole BC2-3-1, the boundary normal BBCB2232 and the center BBC2230 of the deflected particle beam DBC413 between the magnetic pole BC2-3-1 are located on the same side of the exiting particle beam E500.

[0038] like Fig. 9 As shown, at the position where the particle beam E500 is incident on the magnetic pole C3-1 of the deflection magnet C3, the end face of the magnetic pole is processed into a narrow inclined surface, so that the boundary normal CA3001 at the incident position of the particle beam E500 and the center C3010 of the deflected arc particle beam F600 between the magnetic pole C3-1 are located on the same side of the incident particle beam E500; When the particle beam G700 is emitted from the magnetic pole C3 - 1 of the deflection magnet C3 , the center C3010 of the deflected arc particle beam F600 between the boundary normal CB3002 and the magnetic pole C3 - 1 is located on the same side of the emitted particle beam G700 .

[0039] like Fig.10 As shown, when the particle beam G700 is incident on the magnetic pole D4-1 of the deflection magnet D4, the center D4010 of the deflected particle beam H800 between the boundary normal D4001 and the magnetic pole D4-1 is located on the same side of the incident particle beam G700.

[0040] from Figure 2 , Figure 3 , Figure 5~Figure 10 From the description, it can be seen that due to the use of parallel beam bidirectional scanning, there are at least two Y-direction scanning magnets and two X-direction scanning magnets, and multiple boundary focusing effects can be generated at their boundaries. On the other hand, the size of each boundary focusing effect depends on the angle between the incident or outgoing particle beam and the boundary normal. The larger the angle, the stronger the boundary focusing effect. This patent does not limit the angle between the particle beam and the boundary normal, and it can be adjusted as needed. When the synthetic boundary focusing effect of multiple magnets and multiple boundaries is large enough, it can replace the dedicated four-stage focusing magnet.

Claims

1. A deflection magnet system that supports multi-angle isocenter irradiation, realizes parallel beam bidirectional scanning and has a boundary focusing effect, characterized in that: include: A deflection magnet A (1) with edge focusing effect, in an initial state, refers to a rectangular coordinate system composed of an X-axis, a Y-axis and a Z-axis and can rotate around the Y-axis, and the magnetic pole surfaces of the two magnetic poles A (1-1) are mirror-symmetric with respect to the YZ plane, and its function is to deviate the particle beam A (100) incident along the Y-axis toward the origin (0) of the rectangular coordinate system upward from the XY plane in the YZ plane; A group of three deflection magnets B (2) with edge focusing effect is located between the deflection magnet A (1) and the coordinate origin (0). The magnetic pole faces of the two magnetic poles in each group of the three groups are perpendicular to the YZ plane and are mirror-symmetric with respect to the particle beam C (300). The function of the three deflection magnets B (2) is to perform parallel beam scanning in a direction parallel to the X-axis in a plane perpendicular to the YZ plane and containing the particle beam C (300). Among the three deflection magnets B (2), the deflection magnet BA (2-1) close to the deflection magnet A (1) and the deflection magnet BA (2-2) are arranged on the plane perpendicular to the YZ plane and containing the particle beam C (300). The magnet BB (2-2) is responsible for scanning one side of the extension line of the particle beam C (300), so that the particle beam E (500) emitted from the deflection magnet BB (2-2) is parallel to the particle beam C (300), and the deflection magnet BB (2-2) and the deflection magnet BC (2-3) close to the coordinate origin (0) are responsible for scanning the other side of the extension line of the particle beam C (300), so that the particle beam E (500) emitted from the deflection magnet BC (2-3) is parallel to the particle beam C (300); A deflection magnet C (3) with an edge focusing effect is located between a group of three deflection magnets B (2) and the coordinate origin (0), and the magnetic pole surfaces of its two magnetic poles C (3-1) are mirror-symmetrical with respect to the YZ plane. Its function is to be responsible for scanning in the Y-axis direction together with the deflection magnet D (4); A deflection magnet D (4) with an edge focusing effect is located between the deflection magnet C (3) and the coordinate origin (0), and the magnetic pole surfaces of its two magnetic poles D (4-1) are mirror-symmetrical with respect to the YZ plane. Its function is to be responsible for parallel beam scanning in the Y-axis direction together with the deflection magnet C (3), so that the particle beam I (900) emitted from the deflection magnet D (4) is parallel to each other and perpendicular to the Y-axis; A particle beam detection system (5), wherein an ionization chamber A (5-1), located at the particle beam exit end of a deflection magnet A (1), is used to measure the axis line position of a particle beam C (300) and provide the deflection magnet A (1) with beam guidance parameters in the YZ plane; an ionization chamber B (5-2), located at the particle beam exit end of a deflection magnet D (4), is used to measure the axis line position and dose of a particle beam I (900), wherein the axis line position parameter is a beam guidance parameter in the X-axis direction provided by a group of three deflection magnets B (2); A deflection magnet A (1), a group of three deflection magnets B (2), a deflection magnet C (3), a deflection magnet D (4) and a particle beam detection system (5) can rotate with a rectangular coordinate system with the Y axis as the axis center to achieve multi-angle isocentric irradiation; A combination of a group of three deflection magnets B (2), a deflection magnet C (3) and a deflection magnet D (4) can realize parallel beam bidirectional scanning, so that bidirectional scanning particle beams I (900) emitted from the deflection magnet D (4) are parallel to each other; A deflection magnet A (1) having an edge focusing effect, a group of three deflection magnets B (2), a deflection magnet C (3) and a deflection magnet D (4) can produce a focusing effect on the deflected and emitted particle beams.

2. The deflection magnet A (1) with edge focusing effect as claimed in claim 1, wherein at the position where the particle beam A (100) is incident on its magnetic pole A (1-1), the end surface of the magnetic pole is processed into a narrow inclined surface, so that the boundary normal line AA (1001) at the incident position of the particle beam A (100) and the center point A (1010) of the deflected arc particle beam B (200) between the magnetic poles are located on the same side of the incident particle beam A (100); at the position where the particle beam C (300) exits the magnetic pole A (1-1), the end surface of the magnetic pole is processed into a narrow inclined surface, so that the boundary normal line AB (1002) at the exit position of the particle beam C (300) and the center point A (1010) of the deflected arc particle beam B (200) between the magnetic poles are located on the same side of the exiting particle beam C (300).

3. A set of three deflection magnets B (2) with edge focusing effect as claimed in claim 1, wherein the magnetic pole faces of the three deflection magnets B (2) are all isosceles triangles, and the base is parallel to the particle beam C (300), the base of the magnetic pole face of the deflection magnet BA (2-1) magnetic pole BA (2-1-1) and the base of the magnetic pole face of the deflection magnet BC (2-3) magnetic pole BC (2-3-1) are located on the same side of the extension line of the particle beam C (300), and the base of the magnetic pole face of the deflection magnet BB (2-2) magnetic pole BB (2-2-1) is located on the other side of the extension line of the particle beam C (300), and in the particle beam path scanned by the deflection magnet BA (2-1) and the deflection magnet BB (2-2): When the particle beam C (300) is incident on the boundary of the magnetic pole BA (2-1-1), the center BAA (2110) of the deflected arc particle beam DAA (411) between the boundary normal BAAA (2111) and the magnetic pole BA (2-1-1) is located on the same side of the incident particle beam C (300); When the particle beam DAB (412) exits the boundary of the magnetic pole BA (2-1-1), the center BAA (2110) of the deflected arc particle beam DAA (411) between the boundary normal BAAB (2112) and the magnetic pole BA (2-1-1) is located on the same side of the exiting particle beam DAB (412); When the particle beam DAB (412) is incident on the boundary of the magnetic pole BB (2-2-1), the center BAB (2120) of the deflected arc particle beam DAC (413) between the boundary normal BABA (2121) and the magnetic pole BB (2-2-1) is located on the same side of the incident particle beam DAB (412); When the particle beam E (500) exits the boundary of the magnetic pole BB (2-2-1), the center BAB (2120) of the deflected arc particle beam DAC (413) between the boundary normal BABB (2122) and the magnetic pole BB (2-2-1) is located on the same side of the exiting particle beam E (500); In the particle beam path scanned by deflection magnets BB (2-2) and BC (2-3): When the particle beam C (300) is incident on the boundary of the magnetic pole BB (2-2-1), the center BBB (2220) of the deflected arc particle beam DBA (421) between the boundary normal BBBA (2221) and the magnetic pole BB (2-2-1) is located on the same side of the incident particle beam C (300); When the particle beam DBB (422) exits the boundary of the magnetic pole BB (2-2-1), the center BBB (2220) of the deflected arc particle beam DBA (421) between the boundary normal BBBB (2222) and the magnetic pole BB (2-2-1) is located on the same side of the exiting particle beam DBB (422); When the particle beam DBB (422) is incident on the boundary of the magnetic pole BC (2-3-1), the center BBC (2230) of the deflected arc particle beam DBC (423) between the boundary normal BBCA (2231) and the magnetic pole BC (2-3-1) is located on the same side of the incident particle beam DBB (422); When the particle beam E (500) exits the boundary of the magnetic pole BC (2-3-1), the center BBC (2230) of the deflected arc particle beam DBC (423) between the boundary normal BBCB (2232) and the magnetic pole BC (2-3-1) is located on the same side of the exiting particle beam E (500).

4. The deflection magnet C (3) with edge focusing effect as claimed in claim 1 is processed into a narrow inclined surface at the position where the particle beam E (500) is incident on the magnetic pole C (3-1) of the deflection magnet C (3), so that the boundary normal CA (3001) at the incident position of the particle beam E (500) and the center C (3010) of the deflected arc particle beam F (600) between the magnetic pole C (3-1) are located on the same side of the incident particle beam E (500); When the particle beam G (700) exits the magnetic pole C (3-1) of the deflection magnet C (3), the center C (3010) of the deflected arc particle beam F (600) between the boundary normal CB (3002) and the magnetic pole C (3-1) is located on the same side of the exiting particle beam G (700).

5. The deflection magnet D (4) with edge focusing effect as claimed in claim 1, wherein when the particle beam G (700) is incident on the magnetic pole D (4-1) of the deflection magnet D (4), the center D (4010) of the deflected arc particle beam H (800) between the boundary normal D (4001) and the magnetic pole D (4-1) is located on the same side of the incident particle beam G (700).

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