Medical proton synchrotron

Abstract

The present application relates to a kind of medical proton synchrotron, it includes four deflection dipole magnets by four straight sections connection to form a ring structure, wherein the deflection dipole magnet is first, second, third and fourth deflection dipole magnet, it includes four sextupole combined magnet in the straight section, and the four sextupole combined magnet is first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnet.The structure of the present application is very compact, adopts four sextupole combined magnet, reduces unnecessary gap and magnet element, to realize the function of medical accelerator with as few element number as possible, reduce the space occupied by synchrotron, in turn, reduce construction cost and treatment cost.

Description

TECHNICAL FIELD

[0001] The present application relates to tumor treatment, more particularly to a medical proton synchrotron. BACKGROUND

[0002] The excellent Bragg peak characteristics of protons in the depth direction make it one of the most advanced means in tumor treatment, and there are more and more proton treatment devices and centers being built in the world. At present, the main types of proton treatment accelerators are cyclotrons and synchrotrons.

[0003] The cyclotron can provide stable continuous beams, and the beam-off and beam-on speed is fast, which can meet the requirements of respiratory gating. However, the cyclotron relies on a mechanical device installed on the high-energy line, i.e., an energy reducer, to reduce the beam energy by scattering; the advantage is that the energy can be adjusted quickly, and the energy can be changed at a speed of 50 milliseconds per step, which can support fast repetitive scanning mode to treat moving tumors; but the disadvantage is that the scattering causes very low beam utilization, and the through efficiency is less than 1% when the minimum energy is 70 MeV during treatment, and the scattering caused by energy reduction and the large amount of beam loss caused by subsequent energy selection will cause a lot of radiation, which will cause great pressure on radiation protection and equipment safety.

[0004] Compared with the cyclotron, the obvious advantage of the synchrotron is that it can conveniently adjust the energy of the beam to adapt to the need for accurate changes in ion energy for radiotherapy, and it does not need an additional energy reducer, which can ensure a relatively clean (low radiation) environment. After adopting a new multi-energy extraction method, the inherent disadvantages of slow energy conversion time and long invalid time can be overcome, and the synchrotron can adapt to fast repetitive scanning.

[0005] The patent document CN105392270A considers this new technology in the design of magnets, power supplies, etc., thereby greatly reducing the treatment time. However, the design of this accelerator has the following disadvantages: first, it is relatively complex, and it uses 8 deflection dipole magnets and 12 focusing and defocusing quadrupole magnets, which means that the increase in components leads to a decrease in reliability; second, the structure is not compact enough, and the gap between components is a waste; third, the energy consumption is high, and the magnets are high-power devices, and the cyclic energy increasing and decreasing process wastes a lot of energy; fourth, the vertical envelope function is still large, reaching 6 meters, so the space charge effect is large, resulting in less particle storage. Patent documents CN208094872U, CN208094871U, etc. disclose several relatively compact accelerator designs, but their vertical envelope functions are large, the acceptance is small, the dipole magnet angle is large, the length is long, the manufacturing difficulty is large, and they are not suitable for practical application, and the number of quadrupole magnets used is also large, and the structure is not compact enough. SUMMARY

[0006] In order to solve the problems of the prior art, such as the structure being not compact enough, the present application provides a medical proton synchrotron.

[0007] The medical proton synchrotron according to the present application comprises four deflection dipole magnets connected by four straight sections to form a ring structure, wherein the deflection dipole magnets are first, second, third and fourth deflection dipole magnets, the first deflection dipole magnet and the second deflection dipole magnet are connected, the second deflection dipole magnet and the third deflection dipole magnet are connected, the third deflection dipole magnet and the fourth deflection dipole magnet are connected, and the fourth deflection dipole magnet is further connected with the first deflection dipole magnet to form the ring structure, and the straight sections comprise four sextupole combined magnets, wherein the four sextupole combined magnets are first, second, third and fourth horizontal focusing sextupole combined magnets, the first horizontal focusing sextupole combined magnet is connected between the first deflection dipole magnet and the second deflection dipole magnet, the second horizontal focusing sextupole combined magnet is connected between the second deflection dipole magnet and the third deflection dipole magnet, the third horizontal focusing sextupole combined magnet is connected between the third deflection dipole magnet and the fourth deflection dipole magnet, and the fourth horizontal focusing sextupole combined magnet is connected between the fourth deflection dipole magnet and the first deflection dipole magnet.

[0008] It should be understood that the four deflection dipole magnets herein are different from directly providing four sets of deflection dipole magnets. The structure of the synchrotron formed by the four sets of deflection dipole magnets has differences in envelope functions and working points from the present application. Moreover, the four sets of deflection dipole magnets will have a longer circumference due to the magnet gap. In addition, the four sextupole combined magnets herein can better ensure compactness.

[0009] Preferably, the first deflection dipole magnet and the second deflection dipole magnet are sequentially connected with the first horizontal focusing sextupole combined magnet, a second injection convex rail magnet and an injection electrostatic cutting plate.

[0010] Preferably, the injection electrostatic cutting plate is connected with an injection electrostatic cutting magnet.

[0011] Preferably, the second deflection dipole magnet and the third deflection dipole magnet are sequentially connected with a high-frequency accelerating device, a third injection convex rail magnet, a second fast quadrupole magnet and a second horizontal focusing sextupole combined magnet.

[0012] Preferably, the third deflection dipole magnet and the fourth deflection dipole magnet are sequentially connected with a third horizontal focusing sextupole combined magnet, an extraction electrostatic cutting plate and an extraction excitation electrode.

[0013] Preferably, the fourth deflection dipole magnet and the first deflection dipole magnet are sequentially connected with a first fast quadrupole magnet, a first injection convex rail magnet and a fourth horizontal focusing sextupole combined magnet.

[0014] Preferably, the fourth deflection dipole magnet is connected with an extraction static magnetic cutting magnet.

[0015] The medical proton synchrotron according to the present application controls the full ring envelope function in a smaller level by using a smaller number of deflection dipole magnets in combination with the horizontal focusing quadrupole magnets which control the working point (adjustment of the working point by using different intensities), effectively increases the acceptance and the number of proton storage of the synchrotron, improves the utilization rate and the duty cycle of the protons, and shortens the treatment time. In addition, the structure of the present application is very compact, uses the quadrupole and sextupole combined magnets, reduces unnecessary gaps and magnet elements, uses as few elements as possible to realize the function of the medical accelerator, reduces the space occupied by the synchrotron, and further reduces the construction cost and the treatment cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of a medical proton synchrotron according to a preferred embodiment of the present application.

[0017] Figure 2 is a schematic diagram of the envelope function of the medical proton synchrotron of Figure 1 DETAILED DESCRIPTION

[0018] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0019] As shown in Figure 1 , the medical proton synchrotron according to a preferred embodiment of the present application includes first, second, third and fourth deflection dipole magnets 1, 2, 3, 4, wherein the first deflection dipole magnet 1 is connected with the second deflection dipole magnet 2, the second deflection dipole magnet 2 is connected with the third deflection dipole magnet 3, the third deflection dipole magnet 3 is connected with the fourth deflection dipole magnet 4, and the fourth deflection dipole magnet 4 is further connected with the first deflection dipole magnet 1 to form a ring structure to deflect the beam (the direction of the beam is the clockwise direction of the ring structure). Figure 1

[0020] The medical proton synchrotron further includes first, second, third and fourth straight-line sections, wherein the first straight-line section is connected between the first deflection dipole magnet 1 and the second deflection dipole magnet 2, the second straight-line section is connected between the second deflection dipole magnet 2 and the third deflection dipole magnet 3, the third straight-line section is connected between the third deflection dipole magnet 3 and the fourth deflection dipole magnet 4, and the fourth straight-line section is connected between the fourth deflection dipole magnet 4 and the first deflection dipole magnet 1.

[0021] ​​The first linear section comprises a first horizontal focusing quadrupole and sextupole combined magnet 11, a second injection convex rail magnet 42 and an injection electrostatic cutting plate 52 connected in sequence between the first deflection dipole magnet 1 and the second deflection dipole magnet 2. The first linear section further comprises an injection static magnetic cutting magnet 51 connected with the injection electrostatic cutting plate 52.

[0022] The second linear section comprises a high frequency accelerating device 61, a third injection convex rail magnet 43, a second fast quadrupole 32 and a second horizontal focusing quadrupole and sextupole combined magnet 12 connected in sequence between the second deflection dipole magnet 2 and the third deflection dipole magnet 3.

[0023] The third linear section comprises a third horizontal focusing quadrupole and sextupole combined magnet 13, an extraction electrostatic cutting plate 21 and an extraction exciting electrode 22 connected in sequence between the third deflection dipole magnet 3 and the fourth deflection dipole magnet 4.

[0024] The fourth linear section comprises a first fast quadrupole magnet 31, a first injection convex rail magnet 41 and a fourth horizontal defocusing quadrupole and sextupole combined magnet 14 connected in sequence between the fourth deflection dipole magnet 4 and the first deflection dipole magnet 1. The fourth linear section further comprises an extraction static magnetic cutting magnet 23 connected with the fourth deflection dipole magnet 4.

[0025] The above-mentioned components are connected through vacuum tubes (not shown in the figure).

[0026] In actual use, the low-energy proton beam provided by the injector is injected into the medical proton synchrotron of the application through the injection static magnetic cut magnet 51, the injection static electric cut plate 52, the first, second and third injection convex rail magnets 41, 42, 43, and the first, second, third and fourth deflection dipole magnets 1, 2, 3, 4 in a treatment cycle, and is stored; then, according to the treatment requirements, the field strength of the first, second, third and fourth deflection dipole magnets 1, 2, 3, 4 and the first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnets 11, 12, 13, 14 is synchronously raised, and the energy of the protons is raised under the action of the high-frequency accelerating device 61. When the required treatment energy is reached, the strength of the first and second fast quadrupole magnets 31, 32 is excited, so that the operating point moves to the vicinity of the third-order resonance line, and the strength of the sextupole component of the first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnets 11, 12, 13, 14 is adjusted, so that the stable area is reduced while the chromaticity is maintained at the required strength, and the protons are diffused to the extraction channel under the action of the extraction excitation electrode 22, the first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnets 11, 12, 13, 14, and are extracted to the high-energy transport line outside the proton synchrotron through the extraction static electric cut plate 21 and the extraction static magnetic cut magnet 23 and then to the patient. When needed, the extraction can be stopped by reducing the strength of the first and second fast quadrupole magnets 31, 32, and the quadrupole and sextupole components of the first, second, third and fourth deflection dipole magnets 1, 2, 3, 4 and the first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnets 11, 12, 13, 14 and the high-frequency voltage operating frequency of the high-frequency accelerating device 61 are synchronously changed to switch the energy and implement the extraction again.

[0027] In this way, the horizontal focusing effect of the first, second, third and fourth deflection dipole magnets 1, 2, 3, 4, the horizontal focusing effect of the first, second, third and fourth horizontal focusing quadrupole and sextupole combined magnets 11, 12, 13, 14, and the edge angle defocusing effect of the first, second, third and fourth deflection dipole magnets 1, 2, 3, 4 are utilized to achieve bidirectional focusing, and the weak focusing formed can control both the horizontal and vertical envelope functions to be small.

[0028] Figure 2 The horizontal and vertical beam envelope functions corresponding to the embodiment are shown in the figure, wherein the longitudinal coordinate represents the size of the function, and the unit is meter (m), and the transverse coordinate represents the longitudinal position in the synchrotron, and the unit is meter (m). It can be seen that the application has the characteristics of small envelope function and large effective acceptance, and simulation calculation shows that more protons can be stored.

[0029] In summary, the embodiment adopts four deflection dipole magnets combined with quadrupole iron focusing to reduce the envelope function and shorten the circumference, and the resonance sextupole magnet combination on the quadrupole magnet greatly simplifies the number of components and reduces the energy consumption.

[0030] Compared with the technical solutions of patent documents CN105392270A, CN208094872U and CN208094871U, the vertical envelope function of the application is smaller, effectively increasing the acceptance of the synchrotron, increasing the number of proton storage, improving the utilization rate and duty cycle of protons, and shortening the treatment time; moreover, the small envelope function means smaller magnet aperture and smaller magnet energy storage, also reducing energy consumption; fewer magnets also reduce the circumference of the entire accelerator, thereby effectively utilizing the space of the synchrotron, and further minimizing the construction cost of the device and building, and reducing the treatment cost. In addition, the application adds two fast quadrupole irons 31 and 43 for more convenient and fast work point adjustment when multiple energy extraction is performed, and better supports multiple energy extraction.

[0031] The above is only a preferred embodiment of the application, not to limit the scope of the application, and the above embodiment of the application can also be variously changed. That is, any simple, equivalent changes and modifications made according to the content of the claims and the specification of the application fall within the scope of protection of the patent claims of the application. The application is not described in detail.

Claims

1. A medical proton synchrotron characterized by comprising: The medical proton synchrotron comprises four deflection dipole magnets connected by four straight sections to form a ring structure, wherein the deflection dipole magnets are first, second, third and fourth deflection dipole magnets (1, 2, 3, 4), the first deflection dipole magnet (1) and the second deflection dipole magnet (2) are connected, the second deflection dipole magnet (2) and the third deflection dipole magnet (3) are connected, the third deflection dipole magnet (3) and the fourth deflection dipole magnet (4) are connected, and the fourth deflection dipole magnet (4) is also connected with the first deflection dipole magnet (1) to constitute the ring structure, the straight section comprises a four-six pole combined magnet, and the four-six pole combined magnet is a first, second, third and fourth horizontal focusing four-six pole combined magnet (11, 12, 13, 14), wherein the first horizontal focusing four-six pole combined magnet (11) is connected between the first deflection dipole magnet (1) and the second deflection dipole magnet (2), the second horizontal focusing four-six pole combined magnet (12) is connected between the second deflection dipole magnet (2) and the third deflection dipole magnet (3), the third horizontal focusing four-six pole combined magnet (13) is connected between the third deflection dipole magnet (3) and the fourth deflection dipole magnet (4), and the fourth horizontal focusing four-six pole combined magnet (14) is connected between the fourth deflection dipole magnet (4) and the first deflection dipole magnet (1), the second deflection dipole magnet (2) and the third deflection dipole magnet (3) are sequentially connected with a high-frequency accelerating device (61), a third injection convex rail magnet (43), a second fast four-pole magnet (32) and a second horizontal focusing four-six pole combined magnet (12), and the fourth deflection dipole magnet (4) and the first deflection dipole magnet (1) are sequentially connected with a first fast four-pole magnet (31), a first injection convex rail magnet (41) and a fourth horizontal focusing four-six pole combined magnet (14).

2. The medical proton synchrotron according to claim 1, characterized by The first deflection dipole magnet (1) and the second deflection dipole magnet (2) are sequentially connected with the first horizontal focusing four-six pole combined magnet (11), a second injection convex rail magnet (42) and an injection electrostatic cutting plate (52).

3. The medical proton synchrotron according to claim 2, characterized by The injection electrostatic cutting plate is connected with an injection electrostatic cutting magnet (51).

4. The medical proton synchrotron according to claim 1, wherein The third deflection dipole magnet (3) and the fourth deflection dipole magnet (4) are sequentially connected with the third horizontal focusing four-six pole combined magnet (13), an extraction electrostatic cutting plate (21) and an extraction excitation electrode (22).

5. The medical proton synchrotron according to claim 1, wherein The fourth deflection dipole magnet (4) is connected with an extraction electrostatic cutting magnet (23).

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