X-ray tube

Abstract

To provide an X-ray tube that can prevent an increase in the temperature of an anode.SOLUTION: An X-ray tube comprises an anode 13 and a cathode. The anode 13 has an anode target body 14, and an anode target layer 15 provided on the anode target body 14. The cathode faces the anode target layer 15. The anode target body 14 has an anisotropic graphite part 16 formed by laminating a plurality of graphite layers 17. The anode target layer 15 is provided on a surface intersecting a lamination direction a of the graphite layers 17.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to an X-ray tube. [Background technology]

[0002] X-ray tubes generate X-rays by causing electrons emitted from a cathode to collide with an anode, but the efficiency of converting the energy given to the electrons into X-rays is only about 1%, with the rest being converted into heat.

[0003] The heat generated by the electrons colliding with the anode is stored in the anode, and if the temperature of the electron impact surface of the anode exceeds the melting point of the material during the electron impact, the electron impact surface will melt. For this reason, the power input to the X-ray tube must be limited so that the temperature of the anode does not exceed its melting point. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-86463 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide an X-ray tube capable of suppressing a temperature rise in the anode. [Means for solving the problem]

[0006] The X-ray tube of this embodiment includes an anode and a cathode. The anode has an anode target body and an anode target layer provided on the anode target body. The cathode faces the anode target layer. The anode target body has an anisotropic graphite portion formed by stacking multiple graphite layers. The anode target layer is provided on a plane intersecting the stacking direction of the graphite layers. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a side view of a fixed anode type X-ray tube showing a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the anode of the X-ray tube. [Figure 3] FIG. 10 is a schematic cross-sectional view of a rotating anode type X-ray tube showing a second embodiment. [Figure 4] FIG. 2 is a perspective view of the X-ray tube with a portion of the rotation axis and the anode cut away. [Figure 5] FIG. 2 is an enlarged cross-sectional view of the anode of the X-ray tube. [Figure 6] 3A, 3B, and 3C are schematic cross-sectional views showing specific configuration examples in which an anode target layer is provided on an anode target body of the anode of the X-ray tube. [Figure 7] FIG. 10 is an enlarged cross-sectional view of an anode of a rotating anode type X-ray tube according to a third embodiment. [Figure 8] FIG. 10 is an enlarged cross-sectional view of an anode of a rotating anode type X-ray tube according to a fourth embodiment. [Figure 9] FIG. 10 is an enlarged cross-sectional view of an anode of a rotating anode type X-ray tube according to a fifth embodiment. [Figure 10] FIG. 1 is a schematic diagram of an X-ray computed tomography diagnostic apparatus using a rotating anode X-ray tube according to any of the second to fifth embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0008] The first embodiment will be described below with reference to FIGS.

[0009] 1 shows a side view of a fixed anode type X-ray tube 10. The X-ray tube 10 includes a vacuum envelope 11, a cathode 12 sealed in one end of the vacuum envelope 11, and an anode (anode target) 13 sealed in the other end of the vacuum envelope 11.

[0010] The vacuum envelope 11 is made of, for example, glass, and the inside thereof is kept in a vacuum.

[0011] The cathode 12 emits electrons toward the anode 13 .

[0012] The anode 13 includes an anode target body 14 and an anode target layer 15 provided on the anode target body 14. The anode target layer 15 faces the cathode 12, and electrons emitted from the cathode 12 collide with the anode target layer 15 to generate X-rays, which are then emitted outside the vacuum envelope 11.

[0013] 2 shows a schematic cross-sectional view of the anode 13. The anode target body 14 of the anode 13 has an anisotropic graphite portion 16, and the anode target layer 15 is provided on this anisotropic graphite portion 16.

[0014] Anisotropic graphite portion 16 is formed by stacking a plurality of graphite layers 17, such as graphite sheets. Anisotropic graphite portion 16 has a stacking direction a of graphite layers 17 and a plane direction, which is the graphene crystal plane of graphite layer 17, that intersects with stacking direction a. The thermal conductivity in the plane direction is higher than the thermal conductivity in stacking direction a and is also higher than the thermal conductivity of other metal materials such as copper.

[0015] Anisotropic graphite portion 16 has stacking end surface 18 formed of end surfaces of multiple graphite layers 17 on a surface intersecting stacking direction a of graphite layers 17. The tip surface of anode target body 14 facing cathode 12 is stacking end surface 18, and is provided on an inclined surface that is inclined with respect to the direction facing cathode 13.

[0016] Anode target layer 15 is provided on stacking end surface 18, which is the tip surface of anode target body 14 and is a surface that intersects with stacking direction a of anisotropic graphite portion 16, and is in contact with and thermally connected to multiple graphite layers 17. Electron collision surface 19, with which electrons emitted from cathode 12 collide, is formed on the surface of anode target layer 15.

[0017] Anode target layer 15 is formed of a heavy metal with a high melting point, such as molybdenum (Mo), tungsten (W), or an alloy thereof. For example, a molybdenum alloy layer is formed on stacking end surface 18 of anisotropic graphite portion 16, a tungsten alloy layer is formed on this molybdenum alloy layer, and an electron collision surface 19 is formed on the surface of the molybdenum alloy layer.

[0018] When the X-ray tube 10 is in operation, electrons emitted from the cathode 12 collide with the anode target layer 15 of the anode 13 to generate X-rays, which are then emitted outside the vacuum envelope 11 .

[0019] Heat is generated when electrons collide with anode target layer 15 of anode 13. The heat generated in anode target layer 15 is transferred to multiple graphite layers 17 of anisotropic graphite portion 16, spreads in the plane direction of multiple graphite layers 17 where the thermal conductivity is high, and escapes to the outside of X-ray tube 10.

[0020] Anode target body 14 is normally made of a highly thermally conductive metal such as copper to dissipate heat generated in anode target layer 15 to the outside of X-ray tube 10, but by using anisotropic graphite portion 16, heat generated in anode target layer 15 can be quickly dissipated to the outside of X-ray tube 10. This prevents a rise in temperature of anode 13 and keeps the temperature of anode target layer 15 below the melting point of the material of anode target layer 15, thereby easing restrictions on the power input to X-ray tube 10.

[0021] Next, a second embodiment is shown in FIGS.

[0022] 3 shows a schematic cross-sectional view of a rotating anode type X-ray tube 20. The X-ray tube 20 includes a vacuum envelope 21, a cathode 22, a fixed shaft 23, a rotating body 26 having a rotating shaft 24 and an anode 25, a rotor 27, and a stator coil 28. The cathode 22, fixed shaft 23, rotating body 26, and rotor 27 are disposed within the vacuum envelope 21, and the stator coil 28 is disposed outside the vacuum envelope 21.

[0023] The inside of the vacuum envelope 21 is maintained at a vacuum. The vacuum envelope 21 is provided with an X-ray transmission window that emits X-rays generated by the anode 25 to the outside.

[0024] The cathode 22 emits electrons toward the anode 25 .

[0025] The fixed shaft 23 is made of metal and has a substantially cylindrical shape, with one end supported by the vacuum envelope 21. A cooling passage 29 is formed inside the fixed shaft 23, through which a refrigerant, which is a coolant for cooling, passes. The refrigerant is circulated between the cooling passage 29 and the heat exchanger by a cooling device equipped with a heat exchanger (not shown).

[0026] The rotating shaft 24 is cylindrical and is rotatably disposed around the fixed shaft 23 by means of, for example, a fluid metal bearing structure.

[0027] The anode 25 is provided in a disk shape and is disposed around the rotation shaft 24 .

[0028] The rotor 27 is cylindrical and is provided around the rotation shaft 24 .

[0029] The stator coil 28 is disposed in a position facing the rotor 27 across the vacuum envelope 21, and generates a magnetic field that rotates the rotor 27.

[0030] FIG. 4 is a perspective view showing the rotating shaft 24 and the anode 25 with parts cut away.

[0031] A rotating shaft-side mounting portion 30 for mounting the anode 25 is provided around the rotating shaft 24. Mounting holes 31 for mounting the anode 25 with bolts are provided at multiple locations around the circumference of the rotating shaft-side mounting portion 30. The axial direction of the mounting holes 31 is parallel to the axial direction of the rotating shaft 24.

[0032] The anode 25 includes an anode target body 32 and a target layer 33 provided on the anode target body 32 .

[0033] The anode target body 32 is disk-shaped and has a central insertion hole 34 through which the rotary shaft 24 passes. An anode-side attachment portion 35 is provided around the insertion hole 34 and attached to the rotary shaft-side attachment portion 30 of the rotary shaft 24. The anode-side attachment portion 35 has a plurality of attachment holes 36 formed at multiple locations in the circumferential direction, corresponding to the positions of the plurality of attachment holes 31 in the rotary shaft-side attachment portion 30. The axial direction of the attachment holes 36 is parallel to the axial direction of the disk-shaped anode target body 32. The anode-side attachment portion 35 is disposed in the rotary shaft-side attachment portion 30, and a plurality of bolts are attached to the attachment holes 31 in the rotary shaft-side attachment portion 30 through the attachment holes 36 in the anode-side attachment portion 35. Thus, the anode target body 32 is fixed to the rotary shaft 24 and thermally connected to the rotary shaft 24. The anode target body 32 has an inclined surface 37 on the outer circumferential side of one axial surface facing the cathode 22.

[0034] The anode target layer 33 is provided along the circumferential direction on the outer periphery of one axial surface of the anode target body 32 that faces the cathode 22. The anode target layer 33 is provided on an inclined surface 37 of the anode target body 32. The anode target layer 33 is formed of a heavy metal with a high melting point, such as molybdenum (Mo), tungsten (W), or an alloy thereof. An electron collision surface 38 with which electrons emitted from the cathode 22 collide is formed on the surface of the anode target layer 33.

[0035] 5 shows an enlarged cross-sectional view of the anode 25. The anode target body 32 of the anode 25 has an anisotropic graphite portion 39, and the anode target layer 33 is provided on the anisotropic graphite portion 39. In this embodiment, the entire anode target body 32 is formed of the anisotropic graphite portion 39.

[0036] Anisotropic graphite portion 39 is formed by stacking a plurality of graphite layers 40, such as graphite sheets. Anisotropic graphite portion 39 has a stacking direction a of graphite layers 40 and a plane direction, which is the graphene crystal plane of graphite layer 40, that intersects with stacking direction a. The thermal conductivity in the plane direction is higher than the thermal conductivity in stacking direction a and is also higher than the thermal conductivity of other metal materials such as copper.

[0037] The stacking direction a of graphite layers 40 is aligned along circumferential direction Z, which is the rotation direction of anode target body 32, and the plane direction of graphite layers 40 is aligned along radial direction X and axial direction Y, which is the thickness direction of anode target body 32. Therefore, stacking end faces 41, which are formed by end faces of multiple graphite layers 40 that are planes intersecting with stacking direction a of graphite layers 40, are formed on one surface, the other surface, the outer peripheral surface, and the inner peripheral surface of anode target body 32 in the axial direction.

[0038] The anode target body 32 is attached such that the other axial surface of the anode target body 32 and the stacked end surface 41 on the inner peripheral surface are in contact with the rotating shaft 26, and thus the multiple graphite layers 40 are fixed in a state in which they are in contact with and thermally connected to the rotating shaft 26.

[0039] The anode target layer 33 is provided along the circumferential direction Z on a stacking end surface 41 on one axial surface of the anode target body 32, which is a surface that intersects with the stacking direction a of the graphite layers 40, and is in contact with and thermally connected to the multiple graphite layers 40.

[0040] 6(a) to 6(c) show schematic cross-sectional views of specific configuration examples in which an anode target layer 33 is provided on an anode target body 32. The anode target layer 33 has a first layer 43 made of, for example, a tungsten alloy that forms an electron collision surface 38, and a second layer 44 that is a bonding layer that bonds the first layer 43 and an anisotropic graphite portion 39 together.

[0041] In the configuration example shown in Figure 6(a), an inclined surface 37 is formed on a stacking end surface 41 on one axial surface of the anode target body 32, which is a surface that intersects with the stacking direction a of the graphite layer 40, and a first layer 43 is provided on this inclined surface 37 via a second layer 44.

[0042] In the configuration example shown in Figure 6(b), a recessed portion 45 is provided from the stacking end surface 41 on one axial surface of the anode target body 32, which is a surface intersecting the stacking direction a of the graphite layer 40, to the outer circumferential surface, a second layer 44 is provided in this recessed portion 45, and a first layer 43 is provided on an inclined surface 37 provided on this second layer 44.

[0043] In the configuration example shown in Figure 6(c), a second layer 44 is laminated on a lamination end surface 41 on one axial surface of the anode target body 32, which is a surface that intersects with the lamination direction a of the graphite layer 40, and a first layer 43 is provided on an inclined surface 37 provided on this second layer 44.

[0044] When the X-ray tube 20 is in operation, electrons emitted from the cathode 22 collide with the electron collision surface 38 of the anode target layer 33 of the rotating anode 25, generating X-rays, which are then emitted to the outside through the X-ray transmission window of the vacuum envelope 21.

[0045] Heat is generated when electrons collide with anode target layer 33. The heat generated in anode target layer 33 is transferred from stacked end surface 41 of anisotropic graphite portion 39 to multiple graphite layers 40, spreading in the planar direction where thermal conductivity is high, and then quickly and efficiently transferred to rotating shaft 24 on which anode 25 is attached, and then dissipated from rotating shaft 24 to the outside via fixed shaft 23, etc.

[0046] Therefore, the heat generated in the anode target layer 33 can be quickly and efficiently conducted to the rotation axis 24 by the anisotropic graphite portion 39 and dissipated, suppressing a rise in temperature of the anode target layer 33 and keeping the temperature of the anode target layer 33 below the melting point of the material of the anode target layer 33, thereby easing restrictions on the power input to the X-ray tube 20.

[0047] Next, a third embodiment is shown in Fig. 7. Fig. 7 shows an enlarged cross-sectional view of an anode 25 of a rotating anode type X-ray tube 20. Note that the same components as those in the second embodiment are given the same reference numerals and their description will be omitted.

[0048] The anode target body 32 has an anisotropic graphite portion (first anisotropic graphite portion) 39 in which the stacking direction a of the graphite layer 40 is arranged along the circumferential direction Z of the anode target body 32, and a second anisotropic graphite portion 50 in which the stacking direction a of the graphite layer 40 is arranged along the axial direction of the anode target body 32.

[0049] The anisotropic graphite portion 39 is provided on the outer peripheral side of the anode target body 32, and the anode target layer 33 is provided on a stacking end surface 41 on one side of the anode target body 32 in the axial direction, which is a surface that intersects with the stacking direction a of the graphite layer 40.

[0050] The second anisotropic graphite portion 50 is provided closer to the inner periphery of the anode target body 32 than the anisotropic graphite portion 39 is, and is disposed between the anisotropic graphite portion 39 and the rotation shaft 24 .

[0051] Stacking end face 41 on the inner circumferential surface of anisotropic graphite portion 39 is joined to stacking end face 41 on the outer circumferential surface of second anisotropic graphite portion 50. Stacking direction a of graphite layers 40 at stacking end face 41 on the inner circumferential surface of anisotropic graphite portion 39 intersects with stacking direction a of multiple graphite layers 40 at stacking end face 41 on the outer circumferential surface of second anisotropic graphite portion 50, and multiple graphite layers 40 of anisotropic graphite portion 39 and multiple graphite layers 40 of second anisotropic graphite portion 50 are in contact with each other in a crossing (lattice) pattern.

[0052] The lamination end face 41 on the inner circumferential surface of the second anisotropic graphite portion 50 is attached in contact with the rotary shaft 24 .

[0053] When X-ray tube 20 is in operation, heat generated in anode target layer 33 by electron collisions is transferred from stacking end surface 41 of anisotropic graphite portion 39 to multiple graphite layers 40, spreading in the planar direction where thermal conductivity is high, and then transferred from multiple graphite layers 40 of anisotropic graphite portion 39 to multiple graphite layers 40 of second anisotropic graphite portion 50, spreading in the planar direction where thermal conductivity is high. The heat is then quickly and efficiently transferred to rotating shaft 24 to which second anisotropic graphite portion 50 is attached, and then escapes from rotating shaft 24 to the outside via fixed shaft 23, etc.

[0054] Therefore, the heat generated in the anode target layer 33 can be quickly and efficiently conducted to the rotation axis 24 by the anisotropic graphite portions 39, 50 and dissipated, suppressing a rise in temperature of the anode target layer 33 and keeping the temperature of the anode target layer 33 below the melting point of the material of the anode target layer 33, thereby easing restrictions on the power input to the X-ray tube 20.

[0055] Next, a fourth embodiment is shown in Fig. 8. Fig. 8 shows an enlarged cross-sectional view of the anode 25 of the rotating anode type X-ray tube 20. Note that the same components as those in the second and third embodiments are designated by the same reference numerals and their description will be omitted.

[0056] The anode target body 32 has an anisotropic graphite portion (first anisotropic graphite portion) 39 in which the stacking direction a of the graphite layer 40 is arranged along the circumferential direction Z of the anode target body 32, and a second anisotropic graphite portion 50 in which the stacking direction a of the graphite layer 40 is arranged along the axial direction of the anode target body 32.

[0057] Anisotropic graphite portion 39 is provided on the outer circumferential side and inner circumferential side of anode target body 32. In anisotropic graphite portion 40 on the outer circumferential side, anode target layer 33 is provided on stacking end surface 41 on one surface in the axial direction of anode target body 32, which is a surface that intersects with stacking direction a of graphite layer 40. Anisotropic graphite portion 39 on the inner circumferential side is provided with anode side mounting portion 35 that is attached to rotation shaft 24.

[0058] The second anisotropic graphite portion 50 is provided between the anisotropic graphite portion 39 on the outer periphery side and the anisotropic graphite portion 39 on the inner periphery side.

[0059] Stacking end face 41 on the inner peripheral surface of outer peripheral anisotropic graphite portion 39 and stacking end face 41 on the outer peripheral surface of inner peripheral anisotropic graphite portion 39 are joined to stacking end face 41 on the outer peripheral surface and stacking end face 41 on the inner peripheral surface of second anisotropic graphite portion 50, respectively. Stacking direction a of graphite layers 40 at stacking end face 41 of each anisotropic graphite portion 39 intersects with stacking direction a of graphite layers 40 at stacking end face 41 of second anisotropic graphite portion 50, so that the plurality of graphite layers 40 of anisotropic graphite portion 39 and the plurality of graphite layers 40 of second anisotropic graphite portion 50 are in contact with each other in a crossing (lattice) pattern.

[0060] The anisotropic graphite portion 39 on the inner periphery side is attached so that the other surface in the axial direction of the anode target body 32 and a lamination end surface 41 on the inner periphery surface are in contact with the rotation shaft 24 .

[0061] When the X-ray tube 20 is in operation, heat generated in the anode target layer 33 by the collision of electrons is transmitted from the stacking end surface 41 of the anisotropic graphite portion 39 on the outer periphery to the plurality of graphite layers 40, spreading in the planar direction where the thermal conductivity is high; then, from the plurality of graphite layers 40 of the anisotropic graphite portion 39 on the outer periphery to the plurality of graphite layers 40 of the second anisotropic graphite portion 50, spreading in the planar direction where the thermal conductivity is high; then, from the plurality of graphite layers 40 of the second anisotropic graphite portion 50 to the plurality of graphite layers 40 of the anisotropic graphite portion 39 on the inner periphery, spreading in the planar direction where the thermal conductivity is high; finally, the heat is transmitted quickly and efficiently to the rotating shaft 24 to which the anisotropic graphite portion 39 on the inner periphery is attached, and escapes from the rotating shaft 24 to the outside via the fixed shaft 23, etc.

[0062] Therefore, the heat generated in the anode target layer 33 can be quickly and efficiently conducted to the rotation axis 24 by the anisotropic graphite portions 39, 50 and dissipated, suppressing a rise in temperature of the anode target layer 33 and keeping the temperature of the anode target layer 33 below the melting point of the material of the anode target layer 33, thereby easing restrictions on the power input to the X-ray tube 20.

[0063] Next, a fifth embodiment is shown in Fig. 9. Fig. 9 shows an enlarged cross-sectional view of the anode 25 of the rotating anode type X-ray tube 20. Note that the same components as those in the second to fourth embodiments are given the same reference numerals and their description will be omitted.

[0064] The anode target body 32 is formed using a highly thermally conductive metal such as copper.

[0065] The rotating shaft 24 has an anisotropic graphite portion formed by stacking a plurality of graphite layers along the circumferential direction of the rotating shaft 24 .

[0066] When the X-ray tube 20 is in operation, heat generated in the anode target layer 33 by the collision of electrons is transmitted through the anode target body 32 to the multiple graphite layers 40 of the anisotropic graphite portion 39 of the rotating shaft 24, where it spreads in the planar direction with high thermal conductivity, and is then quickly and efficiently transmitted from the rotating shaft 24 to the fixed shaft 23 and other parts, before being released to the outside.

[0067] Therefore, the heat generated in the anode target layer 33 is transferred to the rotation shaft 24 and can be quickly and efficiently dissipated to the outside, suppressing a rise in temperature of the anode target layer 33 and keeping the temperature of the anode target layer 33 below the melting point of the material of the anode target layer 33, thereby easing restrictions on the power input to the X-ray tube 20.

[0068] The anode 25 shown in any of the second to fourth embodiments may be combined with the rotating shaft 24 shown in the fifth embodiment. In this case, the heat generated in the anode target layer 33 can be quickly and efficiently transferred to the outside and dissipated.

[0069] Furthermore, the rotating anode type X-ray tube 20 shown in the second to fifth embodiments can be used in an X-ray computed tomography diagnostic apparatus 60 shown in Fig. 10. Fig. 10 is a schematic diagram of the X-ray computed tomography diagnostic apparatus 60.

[0070] The X-ray computed tomography diagnostic apparatus 60 has a gantry 62 disposed in a housing 61 so as to rotate, and the X-ray tube 20 is mounted on the gantry 62 .

[0071] The X-ray tube 20 mounted on the gantry 62 is positioned so that the axial direction of the rotation axis 24 is parallel to the rotation axis of the gantry 62, and the X-ray transmission window faces the direction of the rotation center of the gantry 62.

[0072] By using the anisotropic graphite portion 39 or the anisotropic graphite portion 50 for the anode target body 32 of the anode 25, the density of the graphite material is low and it is lightweight, so that the rotation of the stand 62 on which the rotating anode type X-ray tube 20 is mounted can be stabilized compared to when a metal material such as copper is used for the anode target body 32 of the anode 25.

[0073] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0074] 10 X-ray tube 12 Cathode 13 Anode 14 Anode target body 15 Anode target layer 16 Anisotropic graphite section 17 graphite layers 20 X-ray tube 22 Cathode 24 Rotation Axis 25 Anode 32 Anode target body 33 Anode target layer 39 Anisotropic graphite section 40 graphite layers 50 Second anisotropic graphite section a Stacking direction Z circumferential direction

Claims

1. an anode having an anode target body and an anode target layer provided on the anode target body; a cathode facing the anode target layer; Equipped with the anode target body has an anisotropic graphite portion formed by stacking a plurality of graphite layers; The anode target layer is provided on a surface intersecting the stacking direction of the graphite layers. An X-ray tube characterized by:

2. an anode having an anode target body that rotates around a rotation axis and an anode target layer provided on the anode target body; a cathode facing the anode target layer; Equipped with the anode target body has an anisotropic graphite portion formed by stacking a plurality of graphite layers along a circumferential direction of the anode target body, The anode target layer is provided on a surface intersecting the stacking direction of the graphite layers. An X-ray tube characterized by:

3. The anode target body has the anisotropic graphite portion, in which the stacking direction of the graphite layers is provided along the circumferential direction of the anode target body, and a second anisotropic graphite portion, in which the stacking direction of the graphite layers is provided along the axial direction of the anode target body, and the second anisotropic graphite portion is provided between the anisotropic graphite portion and the rotation axis.

3. The X-ray tube according to claim 2.

4. A rotation axis; an anode having an anode target body provided around the rotation axis and an anode target layer provided on the anode target body; a cathode facing the anode target layer; Equipped with The rotating shaft has an anisotropic graphite portion formed by stacking a plurality of graphite layers along the circumferential direction of the rotating shaft. An X-ray tube characterized by:

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