X-ray generation device and x-ray imaging device

Abstract

An X-ray generation device according to the present invention includes an X-ray generation tube having: a negative electrode including an electron emission portion; and a positive electrode including a target for generating X-rays. The X-ray generation device includes a storage container including: a first portion disposed so as to surround a portion of a side surface of the X-ray generation tube and forming a first space; a second portion having a smaller width than the first space, disposed so as to surround another portion of the side surface of the X-ray generation tube, and forming a second space; and a connection portion connecting the first portion and the second portion to each other so as to form an internal space communicating the first space and the second space, the connection portion having a convex portion pointed toward the internal space. The X-ray generation device includes: a first insulation portion that is disposed between the convex portion and the X-ray generation tube so as to be in contact with the convex portion and spaced apart from the X-ray generation tube, and surrounds the X-ray generation tube; and a second insulation portion that is disposed so as to be in contact with at least a portion of the negative electrode and spaced apart from the first insulation portion, and surrounds the negative electrode.

Description

X-ray generator and X-ray imaging device

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

[0002] The magnification of an X-ray transmission image can increase as the distance between the X-ray generating unit formed on the target and the subject decreases. Therefore, to obtain sufficient magnification even when the subject is located deep inside, an X-ray generator is known in which a thin, long protrusion is provided on the main body of the container, and an X-ray generating unit is attached to the tip of the protrusion. Such an X-ray generator is described in Patent Document 1.

[0003] Patent Document 1 describes an X-ray generating device including an X-ray generating tube and a housing container that houses the X-ray generating tube. The X-ray generating tube includes an anode, a cathode having an electron emission source, and an insulating tube that forms a vacuum space between the anode and the cathode, and the anode is electrically connected to the housing container. The housing container has a rear housing section, a flange section that extends from the rear housing section toward the insulating tube of the X-ray generating tube and surrounds the insulating tube, and a protrusion that protrudes from the flange section, and the anode of the X-ray generating tube is fixed to the protrusion. An annular bend is formed between the protrusion and the flange. A protective member is disposed between the cathode of the X-ray generating tube and the annular bend. The protective member is an annular member formed by rotating an L-shaped cross section.

[0004] When a protective member such as that disclosed in Patent Document 1 is provided, the gap between the protective member and the insulating tube of the X-ray tube becomes narrow. Experiments conducted by the present applicant have revealed the problem that this narrows the gap, strengthening the electric field of the insulating oil present in the gap and potentially causing a discharge between the cathode and anode of the X-ray tube. Furthermore, a configuration in which the protective member extends toward the cathode side of the X-ray tube to physically block the discharge path between the cathode and anode is inappropriate because it results in improper filling of the insulating oil at the tip of the protruding portion during the manufacture of the X-ray tube.

[0005] Japanese Patent Application Laid-Open No. 2018-73625

[0006] The present invention provides an advantageous technique for preventing discharge between the cathode and anode of an X-ray tube and for facilitating the application of insulating oil to the tip of the protrusion during manufacturing.

[0007] A first aspect of the present invention relates to an X-ray generating device, the X-ray generating device comprising: an X-ray generating tube having a cathode including an electron emitting portion that emits electrons in a first direction, and an anode including a target that generates X-rays when struck by electrons emitted from the electron emitting portion; a first portion that is disposed to surround a portion of a side surface of the X-ray generating tube and forms a first space; and a second portion that is disposed to surround another portion of the side surface of the X-ray generating tube and has a width in a second direction orthogonal to the first direction smaller than that of the first space. the cathode is in contact with a portion of the cathode and is spaced apart from the first insulating part, and the cathode is surrounded by a first insulating part that is disposed between the X-ray generating tube and the protrusion and is spaced apart from the first insulating part.

[0008] A second aspect of the present invention relates to an X-ray imaging device, the X-ray imaging device including the X-ray generating device according to the first aspect, and an X-ray detecting device that detects X-rays emitted from the X-ray generating device and transmitted through an object.

[0009] 1 is a diagram showing the configuration of an X-ray generation apparatus according to a first embodiment;

[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 invention claimed. 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] FIG. 1 schematically illustrates the configuration of an X-ray generator 100 according to a first embodiment. The X-ray generator 100 may include an X-ray generating tube 102, a voltage supply unit 110, a container 130, an insulating liquid 108, and an insulating structure 120. FIG. 1 illustrates a cross section of the X-ray generating tube 102 along a virtual plane including a tube axis AX. The X-ray generating tube 102 may include a cathode 104 including an electron emitter 23 that emits electrons in a first direction (Z direction) parallel to the tube axis AX, and an anode 103 including a target 1 that generates X-rays when struck by electrons emitted from the electron emitter 23. The X-ray generating tube 102 may also include an insulating tube 4 that forms part of the outer surface of the X-ray generating tube 102. The voltage supply unit 110 supplies voltage to the X-ray generating tube 102, more specifically, to the cathode 104, via a conductive wire 109. The conductive wire 109 may include a conductive member and an insulating material covering the conductive member, but may not include the insulating material.

[0012] The receiving container 130 may include a first portion 131, a second portion 132, and a connecting portion 133. The first portion 131 is disposed to surround a portion of a side surface of the X-ray generating tube 102 and forms a first space SP1. The first portion 131 may also house the voltage supply unit 110. The second portion 132 is disposed to surround another portion of the side surface of the X-ray generating tube 102 and forms a second space SP2. The connecting portion 133 may connect the first portion 131 and the second portion 132 to each other to form an internal space ISP in which the first space SP1 formed by the first portion 131 and the second space SP2 formed by the second portion 132 are connected to each other. The second portion 132 has a smaller width in a second direction (Y direction) perpendicular to the first direction (Z direction) than the first portion 131. Furthermore, the second space SP2 has a smaller width in a second direction (Y direction) perpendicular to the first direction (Z direction) than the first space SP1.

[0013] The connecting portion 133 may have a convex portion 135 that is pointed toward the internal space ISP of the housing container 130 in a cross section taken along an imaginary plane including the tube axis AX of the X-ray generating tube 102. The second portion 132 may have a tubular shape, such as a cylindrical shape. In a cross section taken along an imaginary plane including the tube axis AX of the X-ray generating tube 102 as shown in FIG. 1 , the convex portion 135 may have a 90-degree interior angle, an acute interior angle, or an obtuse interior angle. In the first direction (Z direction), the convex portion 135 is disposed between the cathode 104 and the anode 103. In the example shown in FIG. 1 , the length of the second portion 132 in the first direction is shorter than the length of the X-ray generating tube 102 in the first direction.

[0014] The insulating liquid 108 may be filled in the internal space ISP of the receiving container 130 to contact the cathode 104 and surround the conductive wire 109. The insulating structure 120 may be disposed in the internal space ISP of the receiving container 130 to surround at least a portion of the insulating tube 4. The insulating structure 120 may also be disposed in the internal space ISP of the receiving container 130 to surround at least a portion of the cathode 104. The insulating structure 120 may include a first insulating portion 121 and a second insulating portion 122. The first insulating portion 121 and the second insulating portion 122 may be disposed spaced apart from each other in a first direction (Z direction).

[0015] The first insulating portion 121 is disposed between the protrusion 135 and the X-ray generating tube 102 so as to be in contact with the protrusion 135 and be spaced apart from the X-ray generating tube 102, and surrounds the X-ray generating tube 102. The first insulating portion 121 can be disposed so as to block at least the shortest path between the insulating tube 4 and the protrusion 135 of the connecting portion 133. The first insulating portion 121 can be disposed so as to block a straight path between the insulating tube 4 and the protrusion 135 of the connecting portion 133 over the entire insulating tube 4. The first insulating portion 121 can also be disposed so as to block a straight path between the protrusion 135 of the connecting portion 133 and a cathode member 21 of the cathode 104 that constitutes a part of the outer surface of the X-ray generating tube 102. At least a part of the insulating tube 4 can be disposed so as to face the first insulating portion 121 in a plane (a cross-sectional view in a plane) perpendicular to the first direction (Z direction).

[0016] An arrangement in which the first insulating portion 121 contacts the protrusion 135 or the storage container 130 is advantageous for increasing the gap G1 between the first insulating portion 121 and the insulating tube 4 and the gap G2 between the first insulating portion 121 and the second insulating portion 122. Increasing the gaps Gap1 and Gap2 increases the conductance of the insulating liquid 108 from the first space SP1 to the second space SP2 when the insulating liquid 108 is filled, allowing the insulating liquid 108 to fill the entire second space SP2. It is desirable that the gap G1 be larger than the gap G2. Furthermore, increasing the gaps G1 and G2 can reduce the electric field in the gaps G1 and G2.

[0017] The second insulating portion 122 is in contact with at least a portion of the cathode 104 and is disposed spaced apart from the first insulating portion 121, surrounding the cathode 104. Here, at least a portion of the cathode 104, for example, the cathode member 21, can be disposed so as to be in contact with the second insulating portion 122. The second insulating portion 122 can be disposed so as to be in contact with both at least a portion of the cathode member 21 and at least a portion of the insulating tube 4. From another perspective, the second insulating portion 122 can be disposed so as to be in contact with the boundary surface (contact portion) between the cathode member 21 and the insulating tube 4. Furthermore, it is desirable that the second insulating portion 122 be in contact with the entire boundary surface (contact portion) between the cathode member 21 and the insulating tube 4 and surround the boundary surface (contact portion).

[0018] The first insulating portion 121 has an opening S1 with an inner diameter R1. The second insulating portion 122 has an outer diameter R2. R2 is preferably larger than R1. This increases the discharge distance between the portion of the cathode member 21 not covered by the second insulating portion 122 and the portion of the second portion 132 not covered by the first insulating portion 121, thereby preventing abnormal discharge. At least a portion of the X-ray generating tube 102 can be disposed within the opening S1. From another perspective, the X-ray generating tube 102 can be disposed so as to pass through the opening S1. From yet another perspective, the insulating tube 4 of the X-ray generating tube 102 can be disposed so as to pass through the opening S1.

[0019] The first insulating portion 121 may include a cylindrical portion 141 having an inner diameter R1 and a ring portion 142 extending radially from a portion (e.g., one end) of the cylindrical portion 141. The central axis of the cylindrical portion 141 and the central axis of the ring portion 142 may coincide with each other. In another aspect, the central axis of the cylindrical portion 141 and the central axis of the ring portion 142 may coincide with the tube axis AX of the X-ray generating tube 102. The second insulating portion 121 may be formed of a ring portion arranged parallel to the ring portion 142 of the first insulating portion 121. The central axis of the second insulating portion 121 may coincide with the central axis of the cylindrical portion 141 and the central axis of the ring portion 142. In another aspect, the central axis of the second insulating portion 121 may coincide with the tube axis AX of the X-ray generating tube 102.

[0020] The first insulating portion 121 and the second insulating portion 122 may be made of any insulating solid material, such as ceramic, glass, or glass-epoxy resin. The first insulating portion 121 and the second insulating portion 122 have a volume resistivity of 1×10 at 25° C. ５ It is preferable that the insulating property is Ωm or more.

[0021] The target 1 of the X-ray generating tube 102 housed in the second portion 132 may be located at the tip end (upper end in FIG. 1 ) of the second portion 132. The X-ray generating tube 102 may be a transmission type X-ray generating tube. In the X-ray generating tube 102, the anode 103, the cathode member 21, and the insulating tube 4 form a vacuum airtight container. The insulating tube 4 has a tubular shape, for example, a cylindrical shape, and connects the anode 103 and the cathode 104 while insulating them from each other. The anode 103 may include the target 1 and the anode member 2. The target 1 may include a target layer 1a and a support window 1b that supports the target layer 1a. The anode member 2 may have a ring shape. The anode member 2 supports the target 1. The anode member 2 may be electrically connected to the target layer 1a. The anode member 2 and the support window 1b may be joined by, for example, brazing material. 1, the target 1 and the tip of the second portion 132 are arranged on the same plane. However, as long as the target 1 is at the same potential as the second portion 132 (i.e., grounded), the target 1 may be arranged to protrude outward from the tip of the second portion 132 or to be recessed from the tip of the second portion 132. Such an arrangement may also be included in the arrangement in which the target 1 is located at the tip of the second portion 132.

[0022] The target layer 1a contains a heavy metal such as tungsten or tantalum, and generates X-rays when irradiated with electrons. The thickness of the target layer 1a can be determined based on the balance between the electron penetration depth that contributes to the generation of X-rays and the amount of self-attenuation of the generated X-rays when they pass through the support window 1b. The thickness of the target layer 1a can be, for example, in the range of 1 μm to several tens of μm.

[0023] The support window 1b has a function of transmitting X-rays generated in the target layer 1a and emitting them to the outside of the X-ray generating tube 102. The support window 1b can be made of a material that transmits X-rays, such as beryllium, aluminum, silicon nitride, or a carbon allotrope. In order to effectively transfer heat generated by the target layer 1a to the anode member 2, the support window 1b can be made of, for example, diamond, which has high thermal conductivity.

[0024] The insulating tube 4 may be made of a ceramic material such as alumina or zirconia, which has vacuum-tightness and insulating properties, or a glass material such as soda lime or quartz. The cathode member 21 and the anode member 2 may be made of materials having linear expansion coefficients αc (ppm / °C) and αa (ppm / °C) close to the linear expansion coefficient αi (ppm / °C) of the insulating tube 4, in order to reduce thermal stress between them. The cathode member 21 and the anode member 2 may be made of an alloy such as Kovar or Monel, for example.

[0025] The cathode 104 may include an electron emitter 23, a cathode member 21 that forms part of the outer surface of the X-ray generating tube 102, and a fixing portion 22 that fixes the electron emitter 23 to the cathode member 21. The electron emitter 23 may be connected to the cathode member 21, for example, via brazing material, thermally fused by laser welding or the like, or electrically connected by another method. The electron emitter 23 may include an electron source such as an impregnated thermionic electron source, a filament thermionic electron source, or a cold cathode electron source. The electron emitter 23 may include an electrostatic lens electrode (not shown) that defines an electrostatic field, such as an extraction grid electrode or a focusing lens electrode. The fixing portion 22 may have a tubular shape through which a conductive wire 109 electrically connected to the electron source and the electrostatic lens electrode passes. The conductive wire 109 may include multiple conductive members that are insulated from each other.

[0026] The X-ray generator 100 may be configured as an anode-grounded type in which the anode 103 is grounded. In the anode-grounded type, the anode 103 may be electrically connected to the receiving container 130. The receiving container 130 may be electrically connected to a ground terminal 105. The cathode 104 may be electrically connected to a voltage supply unit 110 via a conductive wire 109.

[0027] The voltage supply unit 110 may include a power supply circuit 111 and a drive circuit 112 that receives power supplied from the power supply circuit 111 via a power line 107 and drives the X-ray generating tube 102 via a conductive line 109. The drive circuit 112 may be electrically connected to the housing 130 via the power line 107, the power supply circuit 111, and a ground line 106. The drive circuit 112 may control the amount of electrons emitted from the electron source and the electron beam diameter by controlling voltages supplied to the electron source, extraction grid electrode, focusing lens electrode, etc. A positive terminal of the power supply circuit 111 is grounded via the ground line 106 and the housing 130, and a negative terminal of the power supply circuit 111 is connected to the drive circuit 112 via the power line 107 and supplies a negative voltage to the drive circuit 112. A control signal may be supplied to the drive circuit 112 from a control unit (not shown) located outside the housing 130 via a cable such as an optical fiber cable, for example.

[0028] The first portion 131, the second portion 132, and the connecting portion 133 constituting the storage container 130 may be made of a conductive material, electrically connected to each other, and grounded. Such a configuration is advantageous for ensuring electrical safety. The first portion 131, the second portion 132, and the connecting portion 133 may be made of a metallic material. The storage container 130 may be vacuum-filled with the insulating liquid 108. This is because, if bubbles exist in the insulating liquid 108, a localized region with a lower dielectric constant than the surrounding insulating liquid 108 is formed, which may cause discharge.

[0029] The insulating liquid 108 also has the function of suppressing discharge between the X-ray generating tube 102 and the storage container 130 and discharge between the voltage supply unit 110 (power supply circuit 111, drive circuit 112) and the storage container 130. As the insulating liquid 108, a liquid having excellent heat resistance, fluidity, and electrical insulation properties in the operating temperature range of the X-ray generating device 100, such as silicone oil, fluororesin-based oil or other chemically synthesized oil, or mineral oil, can be used.

[0030] The X-ray generating tube 102 can be fixed to the second portion 132 of the housing container 130 by being joined to an opening provided at the tip end (the lower end in FIG. 1 ) of the second portion 132. An insulating liquid 108 can be filled between the X-ray generating tube 102 and the inner surfaces of the second portion 132. The power supply circuit 111 and the drive circuit 112 can be fixed to the first portion 131 of the housing container 130 by fixing members (not shown). The power supply circuit 111 and the drive circuit 112 can be surrounded by the insulating liquid 108. The conductive wires 109 can be surrounded by the insulating liquid 108.

[0031] The connecting portion 133 of the storage container 130 has, for example, a plate portion that extends in a direction perpendicular to the first direction (Z direction), and the plate portion has an opening through which the X-ray generating tube 102 passes. The plate portion can be abutted against a mounting surface of a structure (e.g., a housing) that supports the X-ray generating device 100. Alternatively, the plate portion can be fitted into an opening in the structure that supports the X-ray generating device 100. In the storage container 130, the side surface of the opening in the plate portion and the inner side surface of the second portion 132 can form a continuous surface without any steps. In one example, the opening in the plate portion can be a circular opening, and the inner side surface of the second portion 132 can be a cylindrical surface. The protrusion 135 can be formed at the edge of the opening in the plate portion.

[0032] Although there is a method of increasing the distance between the convex portion 135 and the cathode 104 by increasing the dimensions of the opening that defines the convex portion 135, such a method is not preferable because it results in an increase in the size of the X-ray generating device 100.

[0033] 2 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 generation device 100 and an X-ray detection device 210 that detects X-rays 192 emitted from the X-ray generation device 100 and transmitted through an object 191. The X-ray imaging device 200 may further include a control device 220 and a display device 230. The X-ray detection device 210 may include an X-ray detector 212 and a signal processing unit 214. The control device 220 may control the X-ray generation device 100 and the X-ray detection device 210. The X-ray detector 212 detects or captures the X-rays 192 emitted from the X-ray generation device 100 and transmitted through the object 191. The signal processing unit 214 may process a signal output from the X-ray detector 212 and supply the processed signal to the control device 220. The control device 220 may cause the display device 230 to display an image based on the signal supplied from the signal processing unit 214.

[0034] 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 device comprising: an X-ray generating tube having a cathode including an electron emitting portion that emits electrons in a first direction, and an anode including a target that generates X-rays when electrons emitted from the electron emitting portion collide with the cathode; a container having a first portion disposed to surround a portion of a side surface of the X-ray generating tube and forming a first space, a second portion having a width in a second direction perpendicular to the first direction smaller than the first space and disposed to surround another portion of the side surface of the X-ray generating tube and forming a second space, and a connecting portion connecting the first portion and the second portion to each other so that an internal space is formed in which the first space and the second space are connected, the connecting portion having a protrusion that is pointed toward the internal space; a first insulating portion disposed between the protrusion and the X-ray generating tube so as to be in contact with the protrusion and spaced from the X-ray generating tube, and surrounding the X-ray generating tube; and a second insulating portion disposed in contact with at least a portion of the cathode and spaced from the first insulating portion, surrounding the cathode.

2. The X-ray generating device according to claim 1, characterized in that the first insulating portion is disposed so as to block at least the shortest path between the cathode and the protruding portion.

3. The X-ray generating device according to claim 1 or 2, characterized in that the length of the second portion in the first direction is shorter than the length of the X-ray generating tube in the first direction.

4. An X-ray generating device according to any one of claims 1 to 3, characterized in that the outer diameter of the second insulating part is larger than the inner diameter of the first insulating part.

5. An X-ray generating device according to any one of claims 1 to 4, characterized in that the X-ray generating tube has a cathode member constituting a part of the outer surface of the X-ray generating tube and an insulating tube, and the second insulating part is arranged so as to cover the contact part between the cathode member and the insulating tube.

6. The X-ray generating device according to claim 5, characterized in that the second insulating portion is arranged so as to cover the entire contact portion between the cathode member and the insulating tube.

7. An X-ray generating device according to any one of claims 1 to 6, characterized in that the first insulating portion includes a cylindrical portion and a ring portion extending radially from a part of the cylindrical portion.

8. The X-ray generating device according to claim 7, wherein the second insulating portion includes a ring portion arranged parallel to the ring portion of the first insulating portion.

9. The X-ray generating device according to any one of claims 1 to 8, characterized in that the X-ray generating tube is a transmission type X-ray generating tube.

10. An X-ray generating device as claimed in any one of claims 1 to 9, characterized in that the first insulating section and the second insulating section are made of a resin material using glass epoxy.

11. The X-ray generating device according to any one of claims 1 to 10, characterized in that the cathode is disposed in the first space.

12. The X-ray generating device according to any one of claims 1 to 11, characterized in that, in the first direction, the convex portion is disposed between the cathode and the anode.

13. The X-ray generating device according to any one of claims 1 to 12, further comprising an insulating liquid filled in the internal space.

14. An X-ray imaging device comprising: an X-ray generating device according to any one of claims 1 to 13; and an X-ray detecting device for detecting X-rays emitted from the X-ray generating device and transmitted through an object.

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