High-throughput X-ray tube for studying the flashover effect

Abstract

The present invention discloses a high-throughput X-ray tube for studying the flashover effect, which includes an electron gun for generating an electron beam. A detachable X-ray target is connected to the electron beam output end of the electron gun. The X-ray target includes a target surface for bombarding by the electron beam. The target surface surrounds to form a conical bombardment cavity, and the inner diameter of the conical bombardment cavity decreases along the direction away from the electron gun. The X-ray target further includes a heat sink. In the high-throughput X-ray tube for studying the flashover effect disclosed by the present invention, the electron beam is dispersed and bombarded on the target surface, and the high temperature generated during the bombardment of the target surface can be uniformly diffused over a large area, and the target surface can be quickly cooled without additionally setting a cooling device. The cooling speed of the target surface is fast. Therefore, the purpose of increasing the X-ray flux can be achieved by increasing the density of the electron beam. At the same time, the inner diameter of the conical bombardment cavity gradually decreases along the direction away from the electron gun, ensuring that more electron beams bombard the target surface, and the generated X-rays are relatively concentrated after passing through the X-ray target.

Description

Technical Field

[0001] The present invention relates to the field of radiation radiotherapy, and particularly to a high-throughput X-ray tube for studying the FLASH effect. Background Art

[0002] Radiotherapy is a method of treating tumors using ionizing radiation. When performing radiotherapy on tumors, a radiation radiotherapy instrument is usually required. The radiation radiotherapy instrument includes an electron linear accelerator, a gamma knife, a proton radiotherapy instrument, etc. The main function of the radiation radiotherapy instrument is to concentrate the ionizing radiation in the tumor area to achieve the effect of eliminating tumor cells. Another main function of the radiation radiotherapy instrument is to minimize the irradiation of ionizing radiation to healthy tissues, thereby protecting healthy cells.

[0003] Traditional radiotherapy adopts low-dose-rate irradiation (~0.1 Gy / s). In recent years, it has been found that high-dose-rate irradiation (>40 Gy / s) has a better protective effect on healthy cells, but retains the killing effect of low-dose-rate irradiation on cancer cells. This effect is called the FLASH effect, that is, the FLASH effect.

[0004] Due to the subversive advantages of the FLASH effect, more and more people are investing in the research of the FLASH effect.

[0005] However, so far, most of the research on the FLASH effect has been achieved by modifying a linear accelerator with an electron beam. However, the linear accelerator device is complex and expensive. Therefore, researchers have tried to use a single or multiple X-ray tubes to achieve the FLASH effect. However, for the X-ray tubes on the market, limited by the heat dissipation limit of the tube, FLASH can only be achieved within a few centimeters from the tube window, and the dose rate is not high.

[0006] The patent with the patent number US9508523B2 discloses an X-ray source that uses electrons to bombard the inner wall of a metal anode pipe, including at least one anode pipe that can utilize incident primary electrons and secondary electrons. The primary electrons bombard the upper part of the pipe, and the scattered electrons bombard the lower part of the pipe to generate X-rays; the pipe can be outwardly expanded, angled, or offset to increase the number of primary electrons bombarded; the electron beam is conical to increase the number of primary electrons bombarded. This patent proposes to use such a single or multiple X-ray sources for imaging.

[0007] The X-ray source provided by the above patent has inherent defects for imaging. For an X-ray source used for imaging, it is required that the area of the X-ray source be as small as possible to improve the resolution. However, the primary and secondary electrons of the above X-rays are generated at different positions on the anode, resulting in a relatively large source area distribution of the ray source, thereby affecting the imaging spatial resolution. In particular, in the above patent, high-energy X-rays are generated by bombarding the upper part of the anode pipe with primary electrons, and low-energy X-rays are generated by bombarding the lower part of the pipe with secondary electrons. When studying the flash effect in radiotherapy, the low-energy X-rays cannot penetrate into the interior of the experimental object, so the rear part of the anode pipe is of little use for realizing the flash effect. Summary of the Invention

[0008] To solve the problems existing in the prior art, the present invention provides a high-throughput X-ray tube for studying the flash effect, which can achieve rapid cooling of the target surface without an additional cooling device, and the emitted X-rays are relatively concentrated, and can achieve high-dose-rate irradiation on the inside of the experimental object within a certain space range from the X-ray tube.

[0009] A high-throughput X-ray tube for studying the flash effect includes an electron gun for generating an electron beam, and an X-ray target is detachably connected to the electron beam output end of the electron gun;

[0010] The X-ray target includes a target surface for bombarding with the electron beam, and a conical bombardment cavity is formed around the target surface, and the inner diameter of the conical bombardment cavity decreases along the direction away from the electron gun;

[0011] The X-ray target further includes a heat sink attached to the outside of the target surface for dissipating heat from the target surface.

[0012] Specifically, the dose rate of irradiation is related to the flux of X-rays and the energy of X-rays. Therefore, in order to achieve the flash effect, an electron gun capable of generating a high-energy electron beam is preferably selected;

[0013] A conical bombardment cavity is formed around the target surface, so that the electron beams emitted in all directions by the electron gun can bombard the target surface; a heat sink made of a metal with a fast heat dissipation speed is attached to the outside of the target surface, which can significantly accelerate the heat dissipation speed of the target surface. That is, this structure of the X-ray target increases the area of the target surface and the heat dissipation speed of the target surface, enabling the target surface to withstand the bombardment of a high-density electron beam. After the high-density electron beam bombards the target surface, high-throughput X-rays can be obtained; that is, the X-ray tube provided by this solution ensures the high throughput of the emitted X-rays, and it is suitable to use this X-ray tube to study the flash effect.

[0014] Preferably, a hardened metal sheet is provided at the ray outlet of the conical bombardment cavity, and the hardened metal sheet is used to filter X-rays so that the filtered X-rays can irradiate the inside of the experimental object; the hardened metal sheet covers at least the entire ray outlet.

[0015] Specifically, the energies of the X-rays generated after the electron beam bombards the target surface are different. X-rays with too low energy cannot irradiate into the experimental object's body, and thus cannot be used for imaging the experimental object or treating tumors in the experimental object's body. Therefore, a hardening metal sheet is provided to filter and absorb them. After being filtered and absorbed by the hardening metal sheet, the X-rays passing through the hardening metal sheet can all irradiate into the experimental object's body;

[0016] In addition, due to the obvious individual differences among experimental objects, for different experimental objects, the range of low-energy X-rays is not the same. Different thicknesses of hardening metal sheets can be replaced according to the experimental object to absorb low-energy X-rays;

[0017] Moreover, when X-rays are emitted, their emission directions show a divergent state. Therefore, the hardening metal sheet should at least cover the entire ray exit. More preferably, the area of the hardening metal sheet is larger than the ray exit, further ensuring the absorption of low-energy X-rays in all emission directions.

[0018] Preferably, the conical bombardment chamber is a conical bombardment chamber, and the angle between the side wall and the height of the conical bombardment chamber is greater than 5° and less than 90°.

[0019] Specifically, the inclination angle of the side wall of the conical bombardment chamber should be adjusted according to the electron beam energy and scattering conditions; large angles can be used for low-energy and more divergent electron beams, and small angles can be used for high-energy and more convergent beams.

[0020] Preferably, the X-ray target includes a first connection part, and the electron gun includes a second connection part. The X-ray target and the electron gun are detachably connected by detachably connecting the first connection part and the second connection part.

[0021] Specifically, the first connection part and the second connection part can adopt structures such as bolts or flanges to achieve detachable connection.

[0022] Preferably, the first connection part is a target cover, and the target cover is sleeved on the periphery of the radiator and is arranged at one end of the radiator close to the electron gun.

[0023] Specifically, the structure of the target cover sleeved on the outside of the radiator makes the position of the X-ray target more stable after being connected to the electron gun.

[0024] Preferably, the electron gun includes a chamber provided with an electron beam exit, the electron beam exit is provided with a beryllium window for maintaining the vacuum environment in the chamber, and the chamber is sequentially provided with a filament lead, a filament, a grid electrode, a focusing electrode, and an anode in the direction close to the electron beam exit.

[0025] Specifically, when heating the filament in a non-vacuum environment, the filament is extremely prone to oxidation. Therefore, a chamber needs to be set up, with the filament placed inside the chamber to maintain a vacuum environment inside the chamber.

[0026] The filament lead is used to connect to an external power supply to heat the filament, and the heated filament generates an electron beam current. The filament is made of tungsten and its alloys. The grid electrode is used to adjust the intensity and movement trajectory of the electron beam current; the converging electrode is used to converge the electron beam current; the anode is used to accelerate the electron beam current; since beryllium has density and a silhouette, the electron beam current loses less energy when passing through the beryllium window. The beryllium window is arranged at the electron beam outlet to ensure that the vacuum environment inside the chamber is appropriate.

[0027] Preferably, a diverging electrode is provided between the grid electrode and the converging electrode, and the diverging electrode is used to diverge the electron beam current; or a diverging sheet for diverging the electron beam current is further provided inside the chamber of the electron gun, and the diverging sheet is arranged close to the beryllium window.

[0028] Specifically, when the electron beam current bombards different positions of the conical bombardment chamber in a relatively dispersed manner, that is, bombards different positions on the target surface, the heat generated by the bombardment will also be relatively dispersed at this time. Therefore, setting the diverging electrode and the diverging sheet makes the dispersion trend of the electron beam current more obvious after it exits the electron gun, so that it can bombard the target surface more dispersedly, and the target surface will cool down more quickly.

[0029] Preferably, the caliber of the electron beam outlet is smaller than the caliber of the entrance of the conical bombardment chamber.

[0030] Specifically, since only the electron beam current bombarding the target surface will form X-rays, such a structure is set to ensure that all the emitted electron beam current can bombard the target surface.

[0031] Compared with the prior art, the advantages of the present invention at least include:

[0032] (1) The electron gun generates an electron beam current that bombards the target surface dispersedly, and the target surface surrounds to form a conical bombardment chamber. A heat sink is attached to the outside of the conical bombardment chamber. Therefore, the high temperature generated when the electron beam current bombards the target surface is absorbed and diffused uniformly over a large area, thereby realizing rapid cooling of the target surface, that is, only relying on the heat sink can achieve rapid cooling of the target surface without additionally setting up a cooling device; since the target surface cools down quickly, the purpose of increasing the X-ray flux can be achieved by increasing the density of the electron beam current.

[0033] (2) Since the electron beam current will gradually spread after being emitted, the structure in which the inner diameter of the conical bombardment chamber gradually decreases along the direction away from the electron gun can ensure that more electron beams bombard the target surface, and the X-rays generated after the bombardment are relatively concentrated after passing through the X-ray target. Description of the Drawings

[0034] Figure 1 Assembly drawing of the high-throughput X-ray tube provided by the present invention for studying the flashover effect;

[0035] Figure 2 Cross-sectional schematic diagram of the first embodiment of the high-throughput X-ray tube provided by the present invention for studying the flashover effect;

[0036] Figure 3 Cross-sectional schematic diagram of the electron gun provided by the present invention;

[0037] Figure 4 Cross-sectional schematic diagram of the X-ray target provided by the present invention;

[0038] Figure 5 Cross-sectional view of the second embodiment of the high-throughput X-ray tube provided by the present invention for studying the flashover effect;

[0039] Figure 6 Cross-sectional view of the third embodiment of the high-throughput X-ray tube provided by the present invention for studying the flashover effect. Detailed implementation manners

[0040] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] Figure 1 It is the assembly drawing of the high-throughput X-ray tube for studying the flashover effect. As Figure 1 shown, the electron gun 10 and the X-ray target 20 are detachably connected through the first connecting portion 24 and the second connecting portion 11. The first connecting portion 24 is a target cover, and the target cover is provided with threaded holes. Threaded holes are also provided at the position of the second connecting portion 11 that is adapted to the target cover. By using bolts to connect the threaded holes on the target cover and the threaded holes on the second connecting portion 11, the detachable connection between the electron gun 10 and the X-ray target 20 is achieved.

[0042] In addition, a detachable connection method such as flange connection or keyway connection can also be adopted between the first connecting portion 24 and the second connecting portion 11.

[0043] The X-ray target 20 further includes a hardening metal sheet 23, and the hardening metal sheet 23 is used to filter the X-ray 32 so that the filtered X-ray 32 can irradiate into the body of the experimental object.

[0044] The energies of the X-rays 32 generated after the electron beam 31 bombards the target surface 21 are different. The X-rays 32 with too low energy cannot irradiate into the body of the experimental object, and thus cannot be used for imaging the experimental object or treating tumors in the body of the experimental object. Therefore, the hardening metal sheet 23 is provided to filter and absorb it. After being filtered and absorbed by the hardening metal sheet 23, the X-rays 32 passing through the hardening metal sheet 23 can all irradiate into the body of the experimental object.

[0045] When the X-ray 32 is emitted, its emission direction presents an emission state. To ensure that the hardened metal sheet 23 can absorb the low-energy X-rays 32 in all emission directions, the hardened metal sheet 23 adopted in this embodiment covers the entire ray exit port and has an area larger than the ray exit port;

[0046] When facing different experimental objects, the values of the low-energy X-rays 32 are not the same. Generally, the larger the volume of the experimental object, the thicker the thickness of the hardened metal sheet 23 selected.

[0047] Figure 2 It is a cross-sectional schematic diagram of the first embodiment of a high-flux X-ray tube for studying the flash effect, Figure 3 It is a cross-sectional schematic diagram of an electron gun, as Figure 2 、 3 shown, the electron gun 10 includes a chamber 12 provided with an electron beam outflow port. The electron beam outflow port is provided with a beryllium window 18 for maintaining the vacuum environment in the chamber 12. The chamber 12 is sequentially provided with a filament lead 13, a filament 14, a grid electrode 15, a focusing electrode 16, and an anode 17 in the direction close to the electron beam outflow port;

[0048] The filament lead 13 is used to connect to an external power supply to heat the filament 14, and an electron beam current 31 is generated by heating the filament 14 according to specific requirements; the filament 14 is made of tungsten and its alloys. The grid electrode 15 is used to adjust the intensity and movement trajectory of the electron beam current 31; the focusing electrode 16 is used to focus the electron beam current 31, and the anode 17 is used to accelerate the electron beam current 31. Since beryllium has a small density and the electron beam current 31 loses less energy when passing through the beryllium window 18, the beryllium window 18 is arranged at the electron beam outflow port to ensure that the vacuum environment in the chamber 12 is appropriate.

[0049] At the same time, the diameter of the electron beam outflow port is smaller than the diameter of the conical bombardment chamber entrance.

[0050] Since only the electron beam current 31 bombarding the target surface 21 will form the X-ray 32, such a structure is provided to ensure that all the emitted electron beam currents 31 can bombard the target surface 21

[0051] Figure 4 It is a cross-sectional schematic diagram of an X-ray target, as Figure 4 shown, the X-ray target 20 includes a target surface 21 for the electron beam current 31 to bombard. The target surface 21 surrounds to form a conical bombardment chamber. A heat sink 22 is attached to the outside of the conical bombardment chamber. The diameter of the conical bombardment chamber decreases along the direction away from the electron gun 10.

[0052] The heat sink 22 is made of a metal such as copper and can quickly dissipate the heat generated by the electron beam current 31 bombarding the target surface 21, thereby realizing rapid cooling of the target surface.

[0053] The conical bombardment chamber is a conical bombardment chamber, and the angle between the side wall and the height of the conical bombardment chamber is 10°.

[0054] The inclination angle of the side wall of the conical bombardment chamber can be selected according to the electron energy and the degree of divergence. When the electron energy is high and the beam divergence is small, a small-angle side wall can be used; otherwise, a large-angle side wall can be used. The purpose is to deposit as much X-ray energy as possible in the experimental body behind the window.

[0055] Figure 5 It is a cross-sectional view of the second embodiment of the high-flux X-ray tube for studying the flash effect, as Figure 5 shown, a divergence electrode 19a is further provided on the grid electrode 15;

[0056] Since the electron gun 10 has a focusing electrode 16, when the electron beam current 31 exits from the electron beam exit, it will converge relatively. However, when the relatively converged electron beam current 31 bombards the target surface 21, the bombardment positions will be relatively concentrated, which is not conducive to the heat dissipation of the target surface 21. Therefore, structures such as a divergence electrode 19a or a divergence sheet 19b need to be provided to increase the divergence trend of the electron beam current 31 when it exits from the electron beam exit, so that the positions where the electron beam bombards the target surface 21 are more dispersed and the heat dissipation of the target surface 21 is accelerated.

[0057] Figure 6 It is a cross-sectional view of the third embodiment of the high-flux X-ray tube for studying the flash effect, as Figure 6 shown, a divergence sheet 19b is provided in the orientation of the chamber 12 close to the beryllium window 18;

[0058] When the electron beam current 31 bombards different positions of the conical bombardment chamber relatively dispersedly, that is, bombards different positions of the target surface 21, the heat generated by the bombardment will also be relatively dispersed at this time. Therefore, setting the divergence electrode 19a or the divergence sheet 19b makes the divergence trend of the electron beam current 31 more obvious after it exits the electron gun 10, so that it can bombard the target surface 21 more dispersedly and the target surface 21 will cool down more quickly.

Claims

1. A high-throughput X-ray tube for studying the flashover effect, comprising an electron gun for generating an electron beam current, characterized in that, The electron beam outflow end of the electron gun is detachably connected with an X-ray target; The X-ray target includes a target surface for bombarding by an electron beam current. The target surface surrounds to form a conical bombardment cavity. The inner diameter of the conical bombardment cavity decreases along the direction away from the electron gun. A hardening metal sheet is provided at the ray outlet of the conical bombardment cavity. The hardening metal sheet is used for filtering X-rays so that the filtered X-rays can irradiate into the body of an experimental object; The hardening metal sheet covers at least the entire ray outlet; The X-ray target further includes a heat sink attached to the outer side of the target surface for dissipating heat from the target surface.

2. The high-throughput X-ray tube for studying the flashover effect according to claim 1, wherein The conical bombardment cavity is a conical bombardment cavity, and the included angle between the side wall and the height of the conical bombardment cavity is greater than 5° and less than 90°.

3. The high-throughput X-ray tube for studying the flashover effect according to claim 1, characterized in that, The X-ray target includes a first connection part, and the electron gun includes a second connection part. The detachable connection between the X-ray target and the electron gun is realized by the detachable connection between the first connection part and the second connection part.

4. The high-throughput X-ray tube for studying the flashover effect according to claim 3, wherein The first connection part is a target cover, and the target cover is sleeved on the periphery of the heat sink and is arranged at one end of the heat sink close to the electron gun.

5. The high-throughput X-ray tube for studying the flashover effect according to claim 1, wherein The electron gun includes a chamber provided with an electron beam outflow port. A beryllium window for maintaining the vacuum environment in the chamber is provided at the electron beam outflow port. The chamber is sequentially provided with a filament lead, a filament, a grid electrode, a focusing electrode, and an anode in the direction close to the electron beam outflow port.

6. The high-throughput X-ray tube for studying the flashover effect according to claim 5, wherein A divergence electrode is further provided on the grid electrode, and the divergence electrode is used for diverging the electron beam current.

7. The high-throughput X-ray tube for studying the flashover effect according to claim 5, wherein A divergence sheet for diverging the electron beam current is further provided in the chamber of the electron gun, and the divergence sheet is arranged close to the beryllium window.

8. The high-throughput X-ray tube for studying the flashover effect according to claim 5, characterized in that, The caliber of the electron beam outflow port is smaller than the caliber of the entrance of the conical bombardment cavity.

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