Miniature wireless pyroelectric X-ray source

Abstract

The invention relates to the technical field of X-ray generation equipment, and particularly discloses a miniature wireless pyroelectric X-ray source, which comprises a conversion target, a target adapter ring, an insulating tube shell, an optical fiber, a graphene electrode, a pyroelectric crystal, a crystal adapter seat, a getter and a laser transmission window, one end of the target adapter ring is connected with the conversion target; one end of the pyroelectric crystal is connected with the graphene electrode; the other end of the pyroelectric crystal is grounded and is connected with the crystal adapter; one end of the laser transmitting window is connected with the crystal adapter, and the other end of the laser transmitting window is connected with the optical fiber; the getter is configured to be arranged on the crystal adapter in a sleeving manner; the conversion target, the target adapter ring, the insulating tube shell, the graphene electrode, the pyroelectric crystal, the crystal adapter seat, the getter and the laser transmission window are all packaged in the insulating tube shell; the miniature wireless pyroelectric X-ray source does not need to be powered by a high-voltage power supply, does not need to heat the cathode to generate electrons, is low in power consumption, can generate X-rays in a wireless mode, and realizes remote control.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray generating equipment, and in particular to a miniature wireless pyroelectric X-ray source. Background Art

[0002] Brachytherapy, also known as internal beam radiotherapy, is a radiotherapy technique in which the radiation source is placed directly into or next to the tumor tissue for irradiation.

[0003] As an important source of radiation for brachytherapy, photon radiation sources have the advantage of being able to generate high-energy photons. These radiations have strong penetrating power and can penetrate deep into tissues to precisely irradiate tumors. Currently, photon radiation sources used in brachytherapy are divided into two categories: one is a gamma-ray source based on a radioactive isotope source, and the other is an X-ray source based on bremsstrahlung radiation generated by electron accelerator target shooting.

[0004] Existing X-ray sources based on bremsstrahlung usually use hot cathodes as electron emission sources. By heating the cathode filament to more than 1000°C, cathode electrons escape. The escaped electron beam bombards the anode target under the action of the anode high voltage, and produces X-rays required for radiotherapy through bremsstrahlung. This type of ray source is connected to an external high-voltage source through a thin high-voltage cable to provide a high voltage for electron acceleration. Although it has the advantages of strong controllability, good ray quality, and high radiation safety, it has problems such as high temperature and high voltage transmission, which limits its application as a neutron source in the field of brachytherapy. Summary of the invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a miniature wireless pyroelectric X-ray source, which does not require the use of a high-voltage power supply, does not require cathode heating to generate electrons, has low power consumption, can generate X-rays wirelessly, and realizes remote control.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] A miniature wireless pyroelectric X-ray source comprises: a conversion target, a target adapter ring, an insulating tube shell, an optical fiber, a graphene electrode, a pyroelectric crystal, a crystal adapter seat, a getter and a laser transmission window.

[0008] One end of the target adapter ring is connected to the conversion target.

[0009] The target adapter ring is located at one end of the insulating tube shell, and the optical fiber is located at the other end of the insulating tube shell.

[0010] One end of the pyroelectric crystal is connected to the graphene electrode; the other end of the pyroelectric crystal is grounded and connected to the crystal adapter.

[0011] One end of the laser transmission window is connected to the crystal adapter, and the other end of the laser transmission window is connected to the optical fiber.

[0012] The getter is configured to be sleeved on the crystal adapter.

[0013] The conversion target, the target adapter ring, the insulating tube shell, the graphene electrode, the pyroelectric crystal, the crystal adapter seat, the getter and the laser transmission window are all packaged in the insulating tube shell to form a sealed vacuum cavity environment.

[0014] The miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure further includes a window adapter ring.

[0015] The optical fiber and the insulating tube shell are both fixedly connected to the adapter ring with window.

[0016] The laser transmission window is located on the window adapter ring, and the laser emitted by the optical fiber passes through the laser transmission window and then enters the insulating tube shell.

[0017] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, the graphene electrode includes a Ni substrate, and multiple layers of vertical graphene are grown on the Ni substrate.

[0018] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, the conversion target is internally coated.

[0019] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, the coating film is one of a W film, an Au film, a Ta film and a Cu film.

[0020] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, the thickness of the coating is 0.1-10 μm.

[0021] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, the getter is arranged in a circular ring shape.

[0022] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, a first electrically conductive and thermally conductive adhesive layer is provided between the Ni substrate and the pyroelectric crystal.

[0023] The Ni substrate and the pyroelectric crystal are both bonded and fixed by the first electrically conductive and thermally conductive adhesive layer.

[0024] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, a second electrically conductive and thermally conductive adhesive layer is provided between the crystal adapter and the pyroelectric crystal.

[0025] The crystal adapter and the pyroelectric crystal are bonded and fixed by the second electrically conductive and thermally conductive adhesive layer.

[0026] In the miniature wireless pyroelectric X-ray source provided in at least one embodiment of the present disclosure, a graphite coating is provided on one end of the crystal adapter facing the laser transmission window.

[0027] The beneficial effects of the present invention are: using laser to remotely heat the pyroelectric crystal material, causing its temperature to change, so as to obtain a negative high voltage, further causing the vertical graphene to emit electrons and accelerate them to hit the target, thereby obtaining X-rays. Compared with the prior art, this technology does not require the use of a high-voltage power supply, does not require heating the cathode to generate electrons, has low power consumption, can generate X-rays wirelessly, and realizes remote control, greatly improving the application scenarios of the technology.

[0028] When in use, the micro X-ray source is used as a neutron source and implanted near the tumor tissue in the body. A fiber connector is reserved at the human skin. The laser generated by an external laser is used to irradiate the fiber connector. The laser reaches the laser transmission window of the micro X-ray source through the optical fiber. After passing through the laser transmission window, it irradiates the crystal adapter and heats it. The crystal adapter transfers the heating temperature to the pyroelectric crystal connected to it, causing the temperature of the pyroelectric crystal to change. The temperature rise of the whole process is controlled within 30-50°C, thereby generating a negative polarity high voltage at one end face of the pyroelectric crystal. At the same time, a layer of graphene electrode is attached to this end face. The high voltage will cause the graphene electrode to emit electrons and accelerate them. After the electrons are accelerated, they bombard the conversion target to generate bremsstrahlung, thereby generating X-rays. After the generated X-rays pass through the conversion target, they irradiate the tumor tissue to cause its biological activity to fail, thereby achieving the purpose of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a three-dimensional diagram of a miniature wireless pyroelectric X-ray source in Example 1.

[0031] Figure 2 This is a schematic diagram of the internal structure of a miniature wireless pyroelectric X-ray source in Example 1.

[0032] Figure 3 This is a stereoscopic diagram of a miniature wireless pyroelectric X-ray source in Example 2.

[0033] Figure 4 This is a schematic diagram of the internal structure of a miniature wireless pyroelectric X-ray source in Example 2.

[0034] In the figure:

[0035] 1. Conversion target; 2. Target adapter ring; 3. Insulating tube shell; 4. Adapter ring with window; 5. Optical fiber; 6. Graphene electrode; 7. Pyroelectric crystal; 8. Crystal adapter seat; 9. Getter; 10. Laser transmission window; 11. Planar conversion target; 12. Planar target adapter ring; 13. Conical insulating tube shell; 14. Planar crystal adapter seat; 15. Wafer pyroelectric crystal; 16. Wafer graphene electrode; 17. Ring-shaped getter. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments, rather than all the embodiments.

[0037] In view of the problems of high temperature and high voltage transmission in the current X-ray source based on bremsstrahlung, which limits its application as a neutron source in the field of brachytherapy, one purpose of the present invention is to propose a miniature wireless pyroelectric X-ray source, which does not need to be powered by a high-voltage power supply, does not need to heat the cathode to generate electrons, has low power consumption, can generate X-rays wirelessly, and can achieve remote control. It has a compact size, is easy to implant near tumor tissue in the body as a neutron source, has no risk of high voltage leakage, and is flexible and convenient to use and shut down.

[0038] Example 1

[0039] like Figure 1 and 2 As shown, this embodiment provides a micro X-ray source device for brachytherapy, which adopts a pin-tube structure, specifically including a conversion target 1, a target adapter ring 2, an insulating tube shell 3, a window adapter ring 4, an optical fiber 5, a graphene electrode 6, a pyroelectric crystal 7, a crystal adapter seat 8, a getter 9 and a laser transmission window 10. In order to ensure that the pin-tube type micro X-ray source device can stably generate X-rays, each component needs to be vacuum-encapsulated in an insulating tube shell after specific connections to form a sealed vacuum cavity environment, and the vacuum level can be maintained for a long time.

[0040] The conversion target 1 is a pointed cylindrical structure, made of Be material as a whole, with a diameter of 3-5mm at the thick end, a diameter of 1-2mm at the thin end, a height of 5mm, and a thickness of 0.05-0.5mm at the thin end. It is used as a Be window to allow the generated X-rays to pass through and improve the transmittance of X-rays. The thick end is connected to the target adapter ring 2 by laser welding or brazing. The conversion target is internally coated with W, Au, Ta, Cu, etc., with a thickness of 0.1-10μm, and its function is to generate X-rays after electron bombardment.

[0041] The target adapter ring 2 is made of Kovar alloy material, with an outer diameter of 3-5mm and an inner diameter of 2-4mm. One end is connected to the conversion target 1, and the other end is connected to the insulating tube shell 3. The connection method is one of laser welding or brazing. It serves as a sealing device for metal and ceramic or glass to ensure the airtightness of the electric vacuum device.

[0042] The insulating tube shell 3 is made of alumina ceramic material, which can be specifically one of 99 porcelain, 95 porcelain or glass, and the glass can be specifically one of quartz glass or high silica glass; the insulating tube shell 3 has an outer diameter of 3-5mm, an inner diameter of 2-4mm, and a length of 20-30mm. One end is connected to the target adapter ring 2, and the other end is connected to the window adapter ring 4. The connection method is one of laser welding or brazing, and the function is high-voltage insulation and fixed support.

[0043] The window adapter ring 4 is made of Kovar alloy material, with an outer diameter of 3-5 mm and an inner diameter of 1-3 mm; one end of the window adapter ring 4 is connected to the insulating tube shell; the laser passes through the optical fiber 5 and the laser transmission window 10 and then enters the interior of the device.

[0044] Optical fiber 5 is made of biocompatible cladding optical fiber such as acrylic ester or ETFE, and the core is made of non-magnetic ceramic core or metal core with good thermal conductivity. The core diameter is 200-550μm, the cladding diameter is 240-600μm, the spectral range is 200-2400nm, and the transmission laser power is 2-20W. It serves as a transmission medium for laser and can transmit laser from an external laser to the inside of a micro X-ray source in the body through an optical fiber connector. The laser is totally reflected inside the micro X-ray source, thereby realizing long-distance light transmission.

[0045] The graphene electrode 6 adopts a structure of multi-layer vertical graphene grown on a Ni substrate, the diameter of the Ni substrate is 1-3mm, the thickness of the Ni substrate is 0.5-1mm, and the Ni substrate is connected to the pyroelectric crystal 7 by bonding with conductive and thermal conductive adhesive; the height of the vertical graphene is 1-10μm, and its function is to generate electron cold emission, and its field enhancement factor is greater than 2000.

[0046] The pyroelectric crystal 7 is made of lithium tantalate or lithium niobate, with a diameter of 1-3mm, a thickness of 5-10mm, and z-phase cutting. Its function is to change the spontaneous polarization of the crystal by changing the temperature of the crystal, so that a negative high voltage is generated at one end; the high voltage end of the pyroelectric crystal 7 is connected to the Ni substrate of the graphene electrode 6, and the other end is grounded and connected to the crystal adapter 8, and the connection method is conductive and thermally conductive adhesive bonding.

[0047] The crystal adapter 8 is made of a material with good thermal conductivity such as Ag, Cu or graphite, with a diameter of 1-3mm and a thickness of 3-5mm. One end of the crystal adapter 8 is connected to the pyroelectric crystal 7, and the other end is assembled with the laser transmission window 10. Its function is to absorb the laser passing through the laser transmission window 10 and transfer the laser energy to the pyroelectric crystal 7, causing its temperature to rise. In order to improve the absorption rate of the laser, a graphite coating (not shown) is provided on the end of the metal crystal adapter 8 facing the laser transmission window 10.

[0048] The getter 9 is made of titanium, zirconium, vanadium and other metals and their alloys. The getter 9 is a circular ring structure with an outer diameter of 1.6-3.6 mm, an inner diameter of 0.8-2.4 mm and a height of 1-3 mm. The getter 9 is mounted on the crystal adapter 8 to maintain the vacuum degree of the micro X-ray source below 10° after high temperature activation. -3 Pa.

[0049] The laser transmission window 10 is made of GaF2 material and is embedded and packaged on the window adapter ring 4 to maintain vacuum and prevent air leakage. One end of the laser transmission window 10 is connected to the crystal adapter seat 8, and the other end is connected to the optical fiber 5 through an optical fiber connector.

[0050] Example 2

[0051] like Figure 3 and 4 As shown, this embodiment provides a micro X-ray source device for brachytherapy, which adopts a button-type structure, specifically including a plane conversion target 11, a plane target adapter ring 12, a conical insulating tube shell 13, an optical fiber 5, a round graphene electrode 16, a round pyroelectric crystal 15, a plane crystal adapter 14, an annular getter 17 and a laser transmission window 10. In order to ensure that the pin-tube type micro X-ray source device can stably generate X-rays, each component needs to be vacuum-encapsulated in an insulating tube shell after specific connection to form a sealed vacuum cavity environment, and the vacuum level can be maintained for a long time.

[0052] The plane conversion target 11 is a dome-shaped structure, made of Be material as a whole, with an upper diameter of 8-28 mm, a lower diameter of 10-30 mm, a height of 1.5-3 mm, and an upper thickness of 0.05-0.5 mm. It is used as a Be window to allow the generated X-rays to pass through and improve the transmittance of X-rays. The plane conversion target is internally coated with a coating material of one of W, Au, Ta and Cu, with a thickness of 0.1-10 μm, which is used to generate X-rays after electron bombardment.

[0053] The plane target adapter ring 12 is made of Kovar alloy material, with an outer diameter of 10-30mm and an inner diameter of 8-28mm; one end of the plane target adapter ring 12 is connected to the plane conversion target 11, and the other end is connected to the conical insulating tube shell 13, and the connection method is laser welding or brazing. The function of the plane target adapter ring 12 is to serve as a sealing device for metal and ceramic or glass to ensure the airtightness of the device.

[0054] The conical insulating shell 13 is made of alumina ceramic material, which can be specifically one of 99 porcelain, 95 porcelain or glass, and the glass can be specifically quartz glass or high silica glass; the cone bottom diameter of the conical insulating shell 13 is 10-30mm, the cone top diameter is 5-7mm, the height is 4-6mm, the cone side wall angle is 165°, the cone bottom is connected to the plane target adapter ring 12, and the cone top is connected to the optical fiber through a joint, and the connection method is one of laser welding or brazing, which serves as high-voltage insulation and fixed support.

[0055] Optical fiber 5 is made of biocompatible cladding optical fiber such as acrylic ester and ETFE, and the core is made of non-magnetic ceramic core or metal core with good thermal conductivity. The core diameter is 200-550μm, the cladding diameter is 240-600μm, the spectral range is 200-2400nm, and the transmission laser power is 2-20W. It serves as a transmission medium for laser and can transmit laser from an external laser to the inside of a micro X-ray source in the body through an optical fiber connector. The laser is totally reflected inside the micro X-ray source, thereby realizing long-distance optical transmission.

[0056] The circular graphene electrode 16 adopts a structure of multi-layer vertical graphene grown on a Ni substrate, the diameter of the Ni substrate is 8-26 mm, the thickness of the Ni substrate is 0.5-1 mm, and the height of the vertical graphene is 1-10 μm. Its function is to generate electron cold emission, and its field enhancement factor is greater than 2000.

[0057] The disc pyroelectric crystal 15 is made of lithium tantalate or lithium niobate. The disc pyroelectric crystal 15 is in the shape of a truncated cone, with a large end diameter of 8-26mm, a small end diameter of 1-3mm, a height of 3-5mm, and a z-phase cut. The function is to change the spontaneous polarization of the crystal by changing the crystal temperature, thereby generating a negative high voltage at the large end. The large end of the disc pyroelectric crystal 15 is connected to the Ni substrate of the disc graphene electrode 16, and the other end is grounded and connected to the planar crystal adapter 14, and the connection method is conductive and thermally conductive adhesive bonding.

[0058] The planar crystal adapter 14 is made of materials with good thermal conductivity such as Ag, Cu, and graphite, with a diameter of 3-5 mm and a thickness of 1-3 mm. One end is connected to the circular pyroelectric crystal 15, and the other end is assembled with the laser transmission window 10. Its function is to absorb the laser passing through the laser transmission window 10 and transfer the laser energy to the circular pyroelectric crystal 15, causing its temperature to rise. In order to improve the absorption rate of the laser, a graphite coating (not shown) is provided on the end of the metal planar crystal adapter 14 facing the laser transmission window 10.

[0059] The annular getter 17 is made of titanium, zirconium, vanadium and other metals and their alloys. The annular getter 17 adopts a circular ring structure with an outer diameter of 5-7mm, an inner diameter of 3-5mm and a height of 0.5-1mm. The annular getter 17 is mounted on the plane crystal adapter 14. The function of the annular getter 17 is to maintain the vacuum degree of the micro X-ray source below 10 after high temperature activation. -3 Pa.

[0060] The laser transmission window 10 is made of GaF2 material and is embedded in a conical insulating tube shell 13 to maintain vacuum and prevent air leakage. One end of the laser transmission window 10 is connected to the planar crystal adapter 14, and the other end is connected to the optical fiber 5 through an optical fiber connector.

[0061] Although the embodiments of the present application have been shown and described above, the scope of protection of the present invention is not limited thereto, and any changes or substitutions that are not conceivable through creative work should be included in the scope of protection of the present invention; unless explicitly stated, any elements, actions or instructions used in this document should not be interpreted as critical or necessary.

Claims

1. A miniature wireless pyroelectric X-ray source, characterized in that: include: Conversion target, target adapter ring, insulating tube shell, optical fiber, graphene electrode, pyroelectric crystal, crystal adapter, getter and laser transmission window; One end of the target adapter ring is connected to the conversion target; The target adapter ring is located at one end of the insulating tube shell, and the optical fiber is located at the other end of the insulating tube shell; One end of the pyroelectric crystal is connected to the graphene electrode; the other end of the pyroelectric crystal is grounded and connected to the crystal adapter; One end of the laser transmission window is connected to the crystal adapter, and the other end of the laser transmission window is connected to the optical fiber; The getter is configured to be sleeved on the crystal adapter; The conversion target, the target adapter ring, the insulating tube shell, the graphene electrode, the pyroelectric crystal, the crystal adapter seat, the getter and the laser transmission window are all packaged in the insulating tube shell to form a sealed vacuum cavity environment.

2. A miniature wireless pyroelectric X-ray source according to claim 1, characterized in that: Also includes a windowed adapter ring; The optical fiber and the insulating tube shell are both fixedly connected to the adapter ring with window; The laser transmission window is located on the window adapter ring, and the laser emitted by the optical fiber passes through the laser transmission window and then enters the insulating tube shell.

3. A miniature wireless pyroelectric X-ray source according to claim 1 or 2, characterized in that: The graphene electrode comprises a Ni substrate, on which multiple layers of vertical graphene are grown.

4. A miniature wireless pyroelectric X-ray source according to claim 1 or 2, characterized in that: The conversion target is internally coated with a film.

5. The miniature wireless pyroelectric X-ray source according to claim 4, characterized in that: The plated film is one of a W film, an Au film, a Ta film and a Cu film.

6. The miniature wireless pyroelectric X-ray source according to claim 4, characterized in that: The thickness of the coating is 0.1-10 μm.

7. A miniature wireless pyroelectric X-ray source according to claim 1 or 2, characterized in that: The getter is arranged in a circular ring shape.

8. The miniature wireless pyroelectric X-ray source according to claim 3, characterized in that: A first conductive and thermally conductive adhesive layer is provided between the Ni substrate and the pyroelectric crystal; The Ni substrate and the pyroelectric crystal are both bonded and fixed by the first electrically conductive and thermally conductive adhesive layer.

9. The miniature wireless pyroelectric X-ray source according to claim 8, characterized in that: A second conductive and thermally conductive adhesive layer is provided between the crystal adapter and the pyroelectric crystal; The crystal adapter and the pyroelectric crystal are bonded and fixed by the second electrically conductive and thermally conductive adhesive layer.

10. A miniature wireless pyroelectric X-ray source according to claim 1 or 2, characterized in that: A graphite coating is provided on one end of the crystal adapter facing the laser transmission window.

Images