X-ray generator and X-ray imaging device

Abstract

This X-ray generation device comprises an X-ray generation tube and an accommodation container. The X-ray generation tube includes: an insulating tube having a first open end and a second open end; a cathode that is positioned so as to block the first open end and includes an electron emission part; and an anode that is positioned so as to block the second open end and includes a target. The accommodation container has a first space for accommodating at least a portion of the X-ray generation tube and a second space for accommodating a drive circuit. The first space is positioned so as to protrude from the second space. The accommodation container has a third open end. The X-ray generation tube is positioned so as to block the third open end. An insulating liquid is filled into the accommodation container so as to contact a portion of the insulating tube. The insulating tube has a boundary surface constituting the outer surface of the X-ray generation tube. A first member positioned at a distance from the second opening end contacts at least a portion of the boundary surface. The first member is sandwiched between the insulating tube and a second member that is positioned at a distance from the accommodation container.

Description

[Technical Field]

[0001] The present invention relates to an X-ray generating device and an X-ray imaging device. [Background technology]

[0002] Patent Document 1 describes an X-ray generating device that includes an X-ray generating tube, a tube drive circuit that drives the X-ray generating tube, and a container that houses the X-ray generating tube and the tube drive circuit. The container is filled with an insulating liquid that ensures insulation between the X-ray generating tube and the tube drive circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-103451 Summary of the Invention

[0004] When an X-ray generating device is used for a long period of time, abnormal discharge may occur in the X-ray generating tube. Investigations by the inventors have revealed that abnormal discharge occurs between the cathode and anode of the X-ray generating tube through the outer surface of the insulating tube. The abnormal discharge may cause the X-ray generating device to stop or break down.

[0005] One aspect of the present invention provides an advantageous technique for suppressing the occurrence of abnormal discharge in an X-ray generating device.

[0006] A first aspect of the present invention relates to an X-ray generator, the X-ray generator comprising: an X-ray generating tube having an insulating tube with a first open end and a second open end; a cathode arranged to close the first open end of the insulating tube and including an electron emitting portion; and an anode arranged to close the second open end and including a target that generates X-rays when electrons from the electron emitting portion collide with the target; and a container that houses the X-ray generating tube and a drive circuit, the container having a first space that houses at least a part of the X-ray generating tube and a drive circuit. the first space is disposed so as to protrude from the second space, the container has a third open end, the X-ray generating tube is disposed so as to close the third open end, an insulating liquid is filled in the container so as to contact a part of the insulating tube, the insulating tube has a boundary surface that forms the outer surface of the X-ray generating tube, at least a part of the boundary surface is in contact with a first member disposed at a distance from the second open end, and the first member is sandwiched between the insulating tube and a second member disposed at a distance from the container.

[0007] A second aspect of the present invention relates to an X-ray generator, the X-ray generator comprising: an X-ray generating tube having an insulating tube with a first open end and a second open end; a cathode arranged to close the first open end of the insulating tube and including an electron emitting portion; and an anode arranged to close the second open end and including a target that generates X-rays when electrons from the electron emitting portion collide with the target; and a container that contains the X-ray generating tube and a drive circuit, the container having a first space that contains at least a part of the X-ray generating tube and a second space that contains the drive circuit. the first space is disposed so as to protrude from the second space, the container has a third open end, the X-ray generating tube is disposed so as to close the third open end, an insulating liquid is filled in the container so as to be in contact with a part of the insulating tube, the insulating tube includes a boundary surface that forms an outer surface of the X-ray generating tube and an inner surface that faces the internal space of the X-ray generating tube, the boundary surface includes an enclosing surface that faces the space enclosed by the insulating tube, and a third space is defined so as to be surrounded by the enclosing surface of the boundary surface and a bottom surface of the cathode.

[0008] A third aspect of the present invention relates to an X-ray imaging device, which includes the X-ray generator according to the first aspect and an X-ray detector that detects X-rays emitted from the X-ray generator. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically showing the configuration of a conventional X-ray generator, illustrating the basic configuration of the X-ray generator according to the present disclosure. [Figure 2] FIG. 1 is a diagram exemplarily and schematically illustrating the configuration of an X-ray generator according to a first embodiment. [Figure 3] FIG. 10 is a diagram exemplarily and schematically illustrating the configuration of an X-ray generator according to a second embodiment. [Figure 4] FIG. 10 is a diagram exemplarily and schematically illustrating the configuration of an X-ray generator according to a third embodiment. [Figure 5] FIG. 10 is a diagram exemplarily and schematically illustrating the configuration of an X-ray generator according to a fourth embodiment. [Figure 6]FIG. 2 is a diagram schematically illustrating the occurrence of abnormal discharge. [Figure 7] FIG. 1 is a diagram illustrating a triboelectric series in frictional electrification with an insulating liquid. [Figure 8] FIG. 11 is a diagram showing a problem in the X-ray generator according to the fifth embodiment. [Figure 9] FIG. 10 is a diagram exemplarily and schematically illustrating the configuration of an X-ray generator according to a fifth embodiment. [Figure 10] FIG. 13 is a diagram schematically showing the configuration of a first modified example of the X-ray generator according to the fifth embodiment. [Figure 11] FIG. 13 is a diagram schematically showing the configuration of a second modified example of the X-ray generator according to the fifth embodiment. [Figure 12] FIG. 13 is a diagram schematically showing the configuration of a third modified example of the X-ray generator according to the fifth embodiment. [Figure 13] FIG. 13 is a diagram schematically showing the configuration of a fourth modified example of the X-ray generator according to the fifth embodiment. [Figure 14] FIG. 1 is a diagram showing the configuration of an X-ray imaging apparatus according to an embodiment. [Figure 15A] FIG. 13 is a diagram schematically showing the configuration of a fifth modified example of the X-ray generator according to the fifth embodiment. [Figure 15B] FIG. 15B is a schematic diagram showing an enlarged portion of FIG. 15A. [Figure 16A] FIG. 13 is a diagram schematically showing the configuration of a sixth modified example of the X-ray generator according to the fifth embodiment. [Figure 16B] FIG. 16B is a schematic diagram showing an enlarged portion of FIG. 16A. [Figure 17] FIG. 13 is a diagram schematically showing the configuration of a seventh modified example of the X-ray generator according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the claimed invention. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] First, the basic configuration of an X-ray generator 100 according to the present disclosure will be described with reference to FIG. 1 . The X-ray generator 100 may include an X-ray generating tube 1 and a housing 50 that houses the X-ray generating tube 1. The X-ray generator 100 may further include a drive circuit 40 that drives the X-ray generating tube 1. The drive circuit 40 may be housed in the housing 50 and connected to the X-ray generating tube 1 via a cable 42. A portion of the X-ray generating tube 1 (the anode 20, described below) may be exposed to the external space of the housing 50 (the external space of the X-ray generator 100). The internal space of the housing 50 is filled with an insulating liquid 60. From another perspective, the internal space of the housing 50 is filled with the insulating liquid 60, except for the spaces occupied by the components housed in the housing 50 (the X-ray generating tube 1, the cable 42, etc.). The insulating liquid 60 may be, for example, an insulating oil such as mineral oil or synthetic oil. Alternatively, the insulating liquid 60 may be a liquid other than insulating oil, for example, a fluorine-based inert liquid (for example, Fluorinert (trademark)).

[0012] The X-ray generating tube 1 may include an insulating tube 10, a cathode 30, and an anode 20. The insulating tube 10, the cathode 30, and the anode 20 may be configured to define an internal space ISX of the X-ray generating tube 1. The internal space ISX of the X-ray generating tube 1 is maintained in a vacuum. The insulating tube 10 may have a first open end OP1 and a second open end OP2. The insulating tube 10 may have a cylindrical shape, for example. The insulating tube 10 may be configured to provide vacuum tightness and insulation for the internal space ISX, which may be defined by the insulating tube 10, the cathode 30, and the anode 20. The insulating tube 10 may be made of a ceramic material, for example, primarily alumina or zirconia. Alternatively, the insulating tube 10 may be made of a glass material, such as borosilicate glass.

[0013] The cathode 30 may be positioned to close the first open end OP1 of the insulating tube 10. The cathode 30 includes an electron emitter 32. The anode 20 may be positioned to close the second open end OP2 of the insulating tube 10. The anode 20 may include a target 23 that generates X-rays when electrons from the electron emitter 32 collide with it. The anode 20 may include a target holding plate 22 that holds the target 23 and an electrode 21 that supports the target holding plate 22. The electrode 21 is made of a conductor and is electrically connected to the target 23, applying a potential to the target 23. The anode 20 and the container 50 may be maintained at, for example, ground potential, but may also be maintained at other potentials. The target 23 may be made of a material with a high melting point and high X-ray generation efficiency, such as tungsten, tantalum, or molybdenum. The target holding plate 22 may be made of a material that is easily transparent to X-rays, such as beryllium or diamond.

[0014] The container 50 may have a third open end OP3. The container 50 may include, for example, a first portion 52, a second portion 53, a third portion 54, a fourth portion 55, and a fifth portion 56. The first portion 52 may have a cylindrical shape, such as a cylindrical shape. The first portion 52 may define the third open end OP3 of the container 50. In other words, the first portion 52 may have the third open end OP3. The second portion 53 is made of a conductor and is electrically connected to the anode 20 of the X-ray generating tube 1. The second portion 53 may be understood to constitute the anode together with the electrode 21. The second portion 53 may have a ring or frame shape. The second portion 53 may be arranged to contact the insulating liquid 60. Alternatively, the conductive member including the electrode 21 and the second portion 53 may be arranged to contact the insulating liquid 60. The electrode 21 and the second portion 53 may be formed as a single piece using the same material. The fourth portion 55 may have a cylindrical shape, such as a cylindrical or rectangular tube shape. The third portion 54 may be connected to one end of the fourth portion 55 and may have a ring or frame shape. The first portion 52 may be connected to the third portion 54 so as to protrude from the third portion 54. The fifth portion 56 may be connected to the other end of the fourth portion 55. Alternatively, the third portion 54, the fourth portion 55, and the fifth portion 56 may be integrated together to form a hollow spherical shape, excluding the joint portion with the first portion 52.

[0015] The insulating liquid 60 can convect in the internal space of the container 50. The insulating tube 10 has an outer surface (boundary surface) 14 that constitutes the outer surface OSX of the X-ray generating tube 1, an inner surface 15 that faces the internal space ISX (vacuum space) of the X-ray generating tube 1, and a contact surface 16 that comes into contact with other components (e.g., the cathode 30, the anode 20) that constitute the internal space ISX (vacuum space) of the X-ray generating tube 1. The outer surface OSX includes the outer surface (boundary surface) 14 and the outer surface 34 of the cathode 30. The outer surface 14 of the insulating tube 10 is a surface of the entire surface of the insulating tube 10 that is neither the inner surface 15 nor the contact surface 16. When the entire outer surface 14 of the insulating tube 10 is in contact with the insulating liquid 60, friction between the outer surface 14 of the insulating tube 10 and the insulating liquid 60 can cause the insulating tube 10 and the insulating liquid 60 to become electrically charged. This type of charging is called triboelectric charging. Generally, triboelectric charging refers to the phenomenon in which electric charges are transferred between two different materials due to friction, resulting in one material becoming positively charged and the other material becoming negatively charged. The inventors conducted an experiment in which an insulating tube was placed in convective insulating oil (insulating liquid) and the potential of the outer surface of the insulating tube was measured using a surface electrometer. The results confirmed that the outer surface of the insulating tube became positively charged and that the amount of charge increased in proportion to time. The polarity of the charge generated by friction depends on the characteristics of the rubbing materials. Examples of material characteristics include the triboelectric series and the dielectric constant. Figure 7 shows an example of the triboelectric series for insulating oil. The triboelectric series indicates whether a rubbed material will become positively or negatively charged and indicates the order in which it will easily become charged. In the triboelectric series, materials closer to the positive side are more likely to be positively charged, while materials closer to the negative side are more likely to be negatively charged.

[0016] Positive charging of the outer surface 14 of the insulating tube 10 can reduce the insulating performance between the cathode 30 and the anode 20. The insulating performance between the cathode 30 and the anode 20 depends on factors such as the potential difference between the cathode 30 and the anode 20, the resistance between the cathode 30 and the anode 20, and the distance between the cathode 30 and the anode 20. Experimental results showed that when the insulating tube 10 is positively charged, a short circuit occurs between the cathode 30 and the anode 20 via the outer surface 14 of the insulating tube 10, as schematically shown by the thick arrows in Figure 6. Experimental results also showed that abnormal discharge due to electron avalanches is likely to occur when a triple junction is formed between the outer surface 14 of the insulating tube 10, the cathode 30, and the insulating liquid 60.

[0017] The X-ray generating device 100 of the present disclosure will be exemplarily described below through a number of embodiments shown in Figures 2, 3, 4, and 5. Items not mentioned below may follow the basic configuration described with reference to Figure 1.

[0018] FIG. 2 exemplarily and schematically illustrates the configuration of the X-ray generator 100 of the first embodiment. The container 50 may be filled with an insulating liquid 60 so as to contact a portion of the anode (e.g., the second portion 53) and cover the outer surface 14 of the insulating tube 10 and the outer surface 34 of the cathode 30. In the X-ray generator 100 of the first embodiment, at least a portion of the insulating tube 10 is surrounded by a member 72 to reduce abnormal discharge between the cathode 30 and the anode 20 via the insulating tube 10. The member 72 may be made of an insulating material. More specifically, in the X-ray generator 100 of the first embodiment, the entire outer surface 34 of the insulating tube 10 may be surrounded by the member 72. From another perspective, the entire outer surface 14 of the insulating tube 10 may be covered by the member 72. Furthermore, the entire outer surface 34 of the cathode 30 may be covered by the member 72 in addition to the entire outer surface 14 of the insulating tube 10. The first embodiment is effective in preventing the outer surface 14 of the insulating tube 10, the cathode 30, and the insulating liquid 60 from forming a triple point, thereby reducing the occurrence of abnormal discharge.

[0019] To reduce abnormal discharge between the cathode 30 and the anode 20 via the insulating tube 10, the material of the member 72 may be selected so that the member 72 is negatively charged and the insulating liquid 60 is positively charged due to frictional charging between the member 72 and the insulating liquid 60. When insulating oil is used as the insulating liquid 60, the material of the member 72 may be selected so that the member 72 is negatively charged due to frictional charging between the member 72 and the insulating oil, for example, according to the triboelectric series illustrated in FIG. 7 . Suitable materials for the member 72 include polytetrafluoroethylene (Teflon™), PMMA (polymethyl methacrylate resin), epoxy, and fluororubber (e.g., Viton™). The member 72 may be disposed so as to entirely cover the outer surface 14 of the insulating tube 10 and the outer surface 34 of the cathode 30. For example, molding, spraying, or dipping may be used for this purpose.

[0020] In order to reduce abnormal discharge between the cathode 30 and the anode 20 via the insulating tube 10, the material of the member 72 can be determined so that the difference in relative dielectric constant between the member 72 and the insulating liquid 60 is smaller than the difference in relative dielectric constant between the member 72 and the insulating tube 10. For example, the member 72 is made of Viton, which has a relative dielectric constant of 3, or polytetrafluoroethylene, which has a relative dielectric constant of 2.1, and the insulating tube 10 is made of borosilicate glass, which has a relative dielectric constant of 4.9, or alumina, which has a relative dielectric constant of 9. Here, the fact that the difference in relative dielectric constant between the member 72 and the insulating liquid 60 is smaller than the difference in relative dielectric constant between the member 72 and the insulating tube 10 may be evaluated at the temperature at which X-rays are generated or at room temperature (e.g., 25°C). However, there is no significant difference between the former and the latter.

[0021] Here, we will explain a molding method suitable for forming the member 72 to coat the X-ray generating tube 1 (the outer surface 14 of the insulating tube 10 and the outer surface 34 of the cathode 30). The material for the member 72, i.e., the coating material, can be prepared by kneading the base material and curing agent in a kneading device to prevent air bubbles from being trapped, and then maintaining a constant temperature to maintain proper fluidity. In the case of epoxy-based resin, the temperature is, for example, around 100°C, but this temperature can be determined appropriately depending on the material used. The coating material can be poured into a container slightly larger than the X-ray generating tube 1 to be coated. During this process, the temperature difference between the container and the coating material can cause the coating material to rapidly cool, reducing its fluidity. To prevent this, it is desirable to preheat the container. After the poured coating material overflows from the container, the coating material can be solidified at an appropriate cooling rate and temperature distribution to prevent problems such as shrinkage.

[0022] In the X-ray generating tube 1, a high voltage is applied between the anode 20 and the cathode 30. Therefore, if bubbles with a low dielectric constant are present in the member 72 made of the coating material, an electric field will concentrate there, which may induce abnormal discharge. To avoid this, the space in which the coating material is filled can be evacuated in advance using a vacuum pump to a vacuum level of several hundred to several thousand Pa. Furthermore, to improve adhesion between the coating material and the X-ray generating tube 1, a primer material may be applied to the surface of the X-ray generating tube 1, or unevenness may be formed by blasting, before the member 72 is applied. From the viewpoint of heat dissipation of the X-ray generating tube 1, it is desirable that the thickness of the member 72 be thin. The thickness of the member 72 is preferably, for example, 5 mm or less, and more preferably 3 mm or less. The thickness of the member 72 is preferably, for example, 0.3 mm or more, and more preferably 0.5 mm or more.

[0023] FIG. 3 exemplarily and schematically illustrates the configuration of an X-ray generator 100 according to a second embodiment. Matters not mentioned in the description of the second embodiment may follow the basic configuration described with reference to the first embodiment or FIG. 1. The member 72 may be arranged to cover the contact portion C between the cathode 30 and the insulating tube 10. The member 72 may also be arranged to cover the cathode 30. The second embodiment is also effective in preventing the outer surface 14 of the insulating tube 10, the cathode 30, and the insulating liquid 60 from forming a triple point, thereby reducing the occurrence of abnormal discharge.

[0024] FIG. 4 exemplarily and schematically illustrates the configuration of an X-ray generator 100 according to a third embodiment. Details not mentioned in the description of the third embodiment may follow the basic configuration described with reference to the first or second embodiment or FIG. 1 . In the third embodiment, an intermediate layer 75 is provided between the member 72 and the insulating tube 10. The intermediate layer 75 may be made of an insulating material. The intermediate layer 75 may be configured to cover the insulating tube 10. The member 72 may be configured to cover the intermediate layer 75. The intermediate layer 75 may be made of at least one of Kovar glass, nylon, and a mixture containing a metal oxide primarily composed of silica. Providing the intermediate layer 75 is advantageous for forming a smooth surface covering the outer surface 14 of the insulating tube 10, for example. Forming the intermediate layer 75 is also advantageous for preventing foreign matter from entering between the particles that make up the insulating tube 10. As a result, the creepage withstand voltage on the surface of the member 72, which is arranged to cover the insulating tube 10, can be improved. This prevents abnormal discharge and extends the life of the X-ray generating device 100.

[0025] FIG. 5 exemplarily and schematically illustrates the configuration of an X-ray generator 100 according to a fourth embodiment. Details not mentioned in the description of the fourth embodiment may follow the basic configuration described with reference to the first to third embodiments or FIG. 1 . In the fourth embodiment, the member 72 may include a ring-shaped portion. Alternatively, the member 72 may be a ring-shaped portion. The ring-shaped portion may completely surround a portion of the outer surface 14 of the insulating tube 10 in the axial direction (the axial direction of the insulating tube 10, which is also the direction in which electron beams are emitted from the electron emitter 32). The outer surface 14 of the insulating tube 10 may be in contact with the insulating liquid 60 in a region other than the region surrounded by the member 72. The shortest distance between the member 72 and the cathode 30 is preferably shorter than the shortest distance between the member 72 and the anode 20. The insulating tube 10 may be surrounded by multiple members 72 (ring-shaped portions). The multiple members 72 may be arranged spaced apart from each other in the axial direction of the insulating tube 10. The member 72 may be made of, for example, Viton. Even if the outer surface 14 of the insulating tube 10 is positively charged, the amount of charge to the positive polarity on the entire outer surface 14 of the insulating tube 10 can be reduced by the member 72 being negatively charged. This can reduce the occurrence of abnormal discharge.

[0026] 9 exemplarily and schematically illustrates the configuration of an X-ray generator 100 according to the fifth embodiment. Matters not mentioned in the description of the fifth embodiment may follow the basic configuration described with reference to the fourth embodiment or FIG.

[0027] To improve the insulation between the anode 20 and the cathode 30, the creepage distance on the outer surface 14 of the insulating tube 10 between the cathode 30 and the anode 20 can be increased by providing a protruding portion PP on the insulating tube 10 as shown in FIG. 8 or by extending the axial length of the insulating tube 10. However, if the protruding portion PP is provided integrally with the insulating tube 10, the insulating tube 10 will have a complex shape, which increases the manufacturing cost of the insulating tube 10 and may reduce the yield. On the other hand, if the protruding portion PP is provided as a separate member, the creepage distance cannot be increased due to the gap between the insulating tube 10 and the protruding portion PP. Furthermore, extending the axial length of the insulating tube 10 increases the size of the X-ray generator 100. Therefore, a solution was sought to increase the creepage distance without increasing the size of the X-ray generator 100 or changing the shape of the insulating tube 10.

[0028] In the fifth embodiment, in order to increase the creepage distance between the cathode 30 and the anode 20, a first member 72 disposed at a distance from the second open end OP2 of the insulating tube 10 contacts at least a portion of the outer surface 14 of the insulating tube 10. The outer surface 14 of the insulating tube 10 has a cylindrical outer side surface (cylindrical surface), and in the configuration example shown in Fig. 9, at least a portion of the cylindrical outer side surface (cylindrical surface) of the outer surface 14 of the insulating tube 10 is surrounded by the first member 72 disposed at a distance from the second open end OP2 of the insulating tube 10. The first member 72 is sandwiched between the insulating tube 10 and a second member 73 disposed at a distance from the container 50.

[0029] Like the member 72 in the fourth embodiment, the first member 72 may include a ring-shaped portion and may be made of fluororubber such as Viton. The first member 72 can be pressed against the insulating tube 10 by the second member 73, thereby coming into close contact with the insulating tube 10. The first member 72 is preferably made of an elastic material such as rubber.

[0030] In the example shown in FIG. 9, a second member 73 is provided around a first member 72. The second member 73 may be a resin-impregnated glass cloth laminate (e.g., a laminated plate or a laminated pipe) that has been molded under heat and pressure. The resin-impregnated glass cloth laminate may be formed, for example, by laminating or winding a member (prepreg) in which a glass nonwoven fabric is impregnated with a resin such as an epoxy resin or a phenolic resin, followed by molding under heat and pressure. The second member 73 may be made of, for example, glass epoxy. The second member 73 has a volume resistivity of 1×10 at 25°C. 5 It is preferable that the second member 73 has an insulating property of Ωm or more. The second member 73 may be made of insulating materials such as epoxy resin, polycarbonate, glass, ceramics, PEEK (polyether ether ketone), ABS (acrylonitrile-butadiene-styrene copolymer synthetic resin), polytetrafluoroethylene (Teflon (trademark)), PMMA (polymethyl methacrylate resin), fluororubber (for example, Viton (trademark)), etc.

[0031] The second member 73 may have, for example, a ring shape. The second member 73 may be composed of multiple separable parts or may be composed of a single piece. Furthermore, as in the modified example shown in FIG. 10, the second member 73 may also function as an insulating container that covers electrical components such as the drive circuit 40. The modified example shown in FIG. 10 also allows for a long creepage distance between the cathode 30 and the anode 20. The first member 72 and the second member 73 may be provided on the outer surface 14 of the insulating tube 10 at a distance from the cathode 30, or may be provided at the contact portion (boundary) between the outer surface 14 of the insulating tube 10 and the cathode 30. The latter prevents the formation of a triple point between the outer surface 14 of the insulating tube 10, the cathode 30, and the insulating liquid 60.

[0032] The second member 73 may have a ring shape as shown in FIG. 9 . The maximum dimension of the second member 73 in a second direction, which is a direction perpendicular to the axial direction of the insulating tube 10, may be greater than the maximum dimension of the second member 73 in a first direction, which is the axial direction of the insulating tube 10. Hereinafter, unless otherwise defined, the first and second directions will follow this definition in this specification. For example, the difference between the outer and inner diameters of the second member 73 in the second direction may be two or more times, three or more times, four or more times, or five or more times the dimension of the second member 73 in the first direction. The second member 73 may be disposed in the first space SP1, rather than in the second space SP2 protruding from the first space SP1 surrounded by the third portion 54, the fourth portion 55, and the fifth portion 56. Furthermore, the maximum dimension of the second member 73 in the second direction may be greater than the maximum dimension of the second space SP in the second direction. For example, when the first portion 52 has a cylindrical shape, the outer diameter of the first member 73 may be larger than the inner diameter of the first portion 52 .

[0033] Furthermore, the second member 73 may have a tubular shape, such as a cylindrical shape, as in the modified example shown in FIGS. 15A and 15B . Even with this structure, the creepage distance between the cathode 30 and the anode 20 can be increased, thereby improving the pressure resistance performance of the X-ray generator 100. Here, the length of the second member 73 in the axial direction (first direction) of the insulating tube 10 may be greater than the thickness of the second member 73 in the direction (second direction) perpendicular to the axial direction of the insulating tube 10. For example, the length of the second member 73 in the axial direction (first direction) of the insulating tube 10 may be two or more times, three or more times, four or more times, or five or more times the thickness of the second member 73 in the direction (second direction) perpendicular to the axial direction of the insulating tube 10. The second member 73 has a facing region 731 facing the insulating tube 10 in the second direction. The insulating tube 10 has a facing region 101 facing the second member 73 in the second direction. 15, there is a fourth space SP4 whose outer surface, inner surface, and bottom surface are surrounded by the facing region 731, the facing region 101, and the first member 72, and a fifth space SP5 whose outer surface, inner surface, and top surface are surrounded by the facing region 731, the facing region 101, and the first member 72. The fourth space SP4 exists on the anode 20 side of the fifth space SP5. The fifth space SP5 may exist on the cathode 30 side of the fourth space SP4. Part or all of the fifth space SP5 or the fourth space SP4 may exist in the first space SP1.

[0034] The second member 73 may be configured to surround only a portion of the insulating tube 10. From another perspective, the length of the second member 73 in the axial direction (first direction) of the insulating tube 10 may be shorter than the length of the insulating tube 10 in the first direction. From yet another perspective, it is preferable that the second member 73 does not contact the anode 20 or the housing vessel 50. This configuration is advantageous for suppressing heat accumulation in the space inside the second member 73, particularly in the insulating tube 10 (X-ray generating tube 1). In particular, in a configuration in which the third opening end OP3 is closed by the X-ray generating tube 1, the longer the second member 73, the closer the second member 73 and the anode 20 become, which inhibits the flow of insulating liquid 60 between the fourth space SP4 and the second space SP2, and this may cause heat to accumulate in the insulating tube 10 (X-ray generating tube 1). Therefore, a configuration in which the second member 73 surrounds only a portion of the insulating tube 10, or a configuration in which the length of the second member 73 in the axial direction (first direction) of the insulating tube 10 is shorter than the length of the insulating tube 10 in the first direction, is advantageous for suppressing such heat accumulation.

[0035] The second member 73 may be arranged so as not to surround the side surface 35 of the cathode 30 in a plane perpendicular to the axial direction of the insulating tube 10. Such a configuration is advantageous for cooling the cathode 30, because the insulating liquid 60 in contact with the cathode 30 can easily dissipate heat to the container 50. On the other hand, the second member 73 may be arranged so as to surround the side surface 35 of the cathode 30 in a plane perpendicular to the axial direction of the insulating tube 10. Such a configuration is advantageous for improving the pressure resistance performance of the X-ray generator 100, because the side surface 35 of the cathode 30 does not directly face the container 50.

[0036] Furthermore, the second member 73 may have a structure that does not include the fourth space SP4, as in the modified example shown in Figures 16A and 16B, for example. Alternatively, the second member 73 may be arranged so as not to define the fifth space SP5.

[0037] Furthermore, the first member 72 and the second member 73 may be disposed between the outer surface 14 of the insulating tube 10 and the first portion 52, as in the modified example shown in FIG. 11 . In the modified example shown in FIG. 11 , the drive circuit 40 is disposed in a first space SP1 surrounded by the third portion 54, the fourth portion 55, and the fifth portion 56. Also, in the modified example shown in FIG. 11 , a second space SP2 surrounded by the first portion 52 and the second portion 53 protrudes from the first space SP1. The first portion 52 may be understood as a portion that constitutes the protrusion. In the modified example shown in FIG. 11 , the first member 72 and the second member 73 are disposed in the second space SP2. The entire insulating tube 10 may be disposed in the second space SP2, or only a portion of the insulating tube 10 may be disposed in the second space SP2.

[0038] As in the modified example shown in Fig. 12, a third member 74 may be provided between the X-ray generating tube 1 and the housing vessel 50 so as to surround a portion of the X-ray generating tube 1. This makes it possible to prevent abnormal discharge between the housing vessel 50 and the X-ray generating tube 1. In this case, the second member 73 and the third member 74 may be integrated. Furthermore, like the second member 73 in the modified example shown in Fig. 10, the third member 74 may also function as an insulating container that covers electrical components such as the drive circuit 40.

[0039] As in the modified example shown in FIG. 13 , the cathode 30 may be disposed so that its entirety fits within the second space SP2. The outer surface 34 of the cathode 30 may have a cylindrical side surface 35 and a circular bottom surface 36. The cylindrical side surface 35 has a non-zero dimension in the axial direction of the insulating tube 10 or in the direction D (first direction) in which electron beams are emitted from the electron emitter 32. The bottom surface 36 of the outer surface 34 of the cathode 30 may face the drive circuit 40. The bottom surface 36 has a non-zero dimension in the radial direction of the insulating tube 10 or in a direction (second direction) perpendicular to the direction D in which electron beams are emitted from the electron emitter 32. The insulating tube 10 may be disposed so as to surround the entire side surface 35 of the cathode 30. This configuration may improve the insulation performance between the cathode 30 and the container 50. In a cross section (FIG. 13) including the direction D in which the electron beam is emitted (the axis of the X-ray generating tube 1), the second part 52 or the third part 54 of the container 50 may have a protrusion 90 that protrudes toward the inside of the container 50.

[0040] The insulating tube 10 includes a boundary surface 14' that constitutes the outer surface OSX of the X-ray generating tube 1 and an inner surface 15 that faces the internal space ISX (vacuum space) of the X-ray generating tube 1. A first member 72 that is disposed at a distance from the second open end OP contacts at least a portion of the boundary surface 14'. The first member 72 is sandwiched between the insulating tube 10 and a second member 73 that is disposed at a distance from the housing vessel 50. The insulating tube 10 may extend so as to block at least a portion of any imaginary line VL1 that connects the protrusion 90 and the outer surface 34 of the cathode 30. The boundary surface 14' of the insulating tube 10 (the surface that constitutes the outer surface OSX of the X-ray generating tube 1) includes an enclosing surface ISS that faces the space enclosed by the insulating tube 10. A third space SP3 may be defined so as to be surrounded by the enclosing surface ISS of the boundary surface 14' and the bottom surface 36 of the cathode 30. The first member 72 may be disposed in the third space SP3 so as to contact an enclosing surface ISS of the boundary surface 14' of the insulating tube 10 that encloses the third space SP3. If the third space SP3 has a cylindrical shape, the top surface of the cylindrical shape may be defined by the bottom surface 36 of the cathode 30, the side surface may be defined by the enclosing surface ISS, which is part of the boundary surface 14' of the insulating tube 10, and the bottom surface may be defined by an imaginary plane defined by the first open end OP1 of the insulating tube 10. The first member 72 may be disposed in the third space SP3 so as to contact a part of the enclosing surface ISS and be spaced apart from the cathode 30. The first member 72 is sandwiched between the enclosing surface ISS (or the insulating tube 10) and a second member 73 that is disposed apart from the container 50. The first member 72 may include a ring-shaped portion. The second member 73 may also include a ring-shaped portion.

[0041] The second member 73 may have a disk shape. In one example, the maximum dimension of the second member 73 in the direction perpendicular to the axial direction of the insulating tube 10 (second direction) is larger than the maximum dimension of the second member 73 in the axial direction of the insulating tube 10 (first direction). In another example, the first member 72 and the second member 73, whose maximum dimension in the direction perpendicular to the axial direction of the insulating tube 10 (second direction) is smaller than the maximum dimension of the second member 73 in the axial direction of the insulating tube 10 (first direction), may contact the bottom surface 36 of the cathode 30. The first member 72 is sandwiched between the second member 73 and the insulating tube 10, which is disposed apart from the container 50. The first member 72 may include a ring-shaped portion. This configuration is effective for increasing the distance between the second member 73 and the first portion 52. Furthermore, this configuration allows the second member 73 to block a portion of the virtual line VL1. The first member 72 may be disposed so as to cover the contact portion (boundary) between the cathode 30 and the insulating tube 10.

[0042] Furthermore, as in the modified example shown in FIG. 17 , the cathode 30 may be arranged so that its entirety is contained within the first space SP1. In addition to the tube drive circuit 40, high-voltage electrical components (not shown), such as a transformer and a booster circuit, may be stored within the first space SP1. In a configuration in which the cathode 30 is arranged within the first space SP1 as shown in FIG. 17 , the X-ray generating tube 1 forms the third space SP3, and arranging the first member 72 and the second member 73 within the third space SP3 is advantageous for improving the insulation performance between the cathode 30 and the tube drive circuit 40, the housing 50, and other high-voltage electrical components (not shown), such as a transformer and a booster circuit. In such a configuration, the first member 72 and the second member 73 may not be provided, and only the third space SP3 may be provided.

[0043] In the fifth embodiment illustrated in Figures 9, 10, 11, 12, 13, 15A, 15B, 16A, 16B, and 17, insulation measures may also be taken between the cathode 30 and the anode 20, as in the first and fourth embodiments.

[0044] FIG. 14 shows the configuration of an X-ray imaging device 200 according to one embodiment. The X-ray imaging device 200 may include an X-ray generator 100 and an X-ray detection device 110 that detects X-rays 104 emitted from the X-ray generator 100 and transmitted through an object 106. The X-ray imaging device 200 may further include a control device 120 and a display device 130. The X-ray detection device 110 may include an X-ray detector 112 and a signal processing unit 114. The control device 120 may control the X-ray generator 100 and the X-ray detection device 110. The X-ray detector 112 detects or captures the X-rays 104 emitted from the X-ray generator 100 and transmitted through the object 106. The signal processing unit 114 may process a signal output from the X-ray detector 112 and supply the processed signal to the control device 120. The control device 120 controls the display device 130 to display an image based on the signal supplied from the signal processing unit 114.

[0045] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

Claims

1. an X-ray generating tube including: an insulating tube having a first open end and a second open end; a cathode arranged to close the first open end of the insulating tube and including an electron emitting portion; and an anode arranged to close the second open end and including a target that generates X-rays when electrons from the electron emitting portion collide with the target; a housing that houses the X-ray generating tube and a drive circuit, the container has a first space that accommodates at least a part of the X-ray generating tube and a second space that accommodates the drive circuit, the first space being disposed so as to protrude from the second space; the container has a third open end, and the X-ray generating tube is disposed so as to close the third open end; an insulating liquid is filled in the container so as to be in contact with a part of the insulating tube, the insulating tube having a boundary surface that constitutes an outer surface of the X-ray generating tube; a first member including a ring-shaped portion, the first member being spaced apart from the second open end, contacting the boundary surface over its entire circumference; the first member is sandwiched between the insulating tube and a second member disposed apart from the container; An X-ray generating device characterized by:

2. a maximum dimension of the first member in a first direction that is an axial direction of the insulating pipe is smaller than a maximum dimension of the second member in a second direction that is perpendicular to the first direction; 2. The X-ray generating device according to claim 1.

3. an X-ray generating tube including: an insulating tube having a first open end and a second open end; a cathode arranged to close the first open end of the insulating tube and including an electron emitting portion; and an anode arranged to close the second open end and including a target that generates X-rays when electrons from the electron emitting portion collide with the target; a housing that houses the X-ray generating tube and a drive circuit, the container has a first space that accommodates at least a part of the X-ray generating tube and a second space that accommodates the drive circuit, the first space being disposed so as to protrude from the second space; the container has a third open end, and the X-ray generating tube is disposed so as to close the third open end; an insulating liquid is filled in the container so as to be in contact with a part of the insulating pipe; the insulating tube includes a boundary surface that forms an outer surface of the X-ray generating tube and an inner surface that faces an internal space of the X-ray generating tube, the boundary surface includes an enclosing surface facing a space enclosed by the insulating tube, a third space is defined so as to be surrounded by the surrounding surface of the boundary surface and a bottom surface of the cathode; a first member is disposed in the third space so as to be in contact with a portion of the surrounding surface and spaced apart from the cathode, and the first member is sandwiched between the surrounding surface and a second member disposed spaced apart from the container; An X-ray generating device characterized by:

4. the ring-shaped portion is in contact with the boundary surface over the entire circumference at a portion at a certain distance from the second opening end; 2. The X-ray generating device according to claim 1.

5. a difference between an inner diameter and an outer diameter of the ring-shaped portion is smaller than a difference between an inner diameter and an outer diameter of the second member; 2. The X-ray generating device according to claim 1.

6. The first member is made of an insulating material.

2. The X-ray generating device according to claim 1.

7. The first member is made of fluororubber.

2. The X-ray generating device according to claim 1.

8. The second member is made of an insulating material.

2. The X-ray generating device according to claim 1.

9. the second member is made of any one of polytetrafluoroethylene, PMMA (polymethyl methacrylate resin), epoxy resin, polycarbonate, glass, ceramics, PEEK (polyether ether ketone), ABS (acrylonitrile butadiene styrene copolymer synthetic resin), and fluororubber; 2. The X-ray generating device according to claim 1.

10. The insulating liquid is insulating oil.

10. The X-ray generating device according to claim 1,

11. The insulating liquid is a fluorine-based inert liquid.

10. The X-ray generating device according to claim 1,

12. An X-ray generator according to any one of claims 1 to 9; an X-ray detector that detects X-rays emitted from the X-ray generator; An X-ray imaging device comprising:

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