JP2016085946A - X-ray generator tube, X-ray generator and X-ray imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate X-ray of sufficient dose by controlling the relative position of an electron emission source and a target with high accuracy, while simultaneously preventing the inner periphery of an insulation tube from being charged reliably, in an X-ray generation tube.SOLUTION: A positive electrode member 43 has tubular outer periphery 43b projecting to the negative electrode 51 side, an insulation tube 110 has a groove 116 extending in the tube diameter direction in the end face on the target holding portion 43a side, and an inner peripheral conductive film 112 located on the inner peripheral surface of the insulation tube 110 and the tubular outer periphery 43b are bonded electrically via an in-groove conductive film 113 located in the groove 116.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray generator tube that generates X-rays that can be applied to, for example, medical devices and non-destructive inspection apparatuses, and an X-ray generator and X-ray imaging system using the X-ray generator tube.

  In an X-ray generator tube, a high voltage is applied in a vacuum vessel, an electron beam is emitted from an electron emission source, and electrons are collided with a target made of a metal material having a large atomic number such as tungsten. Is generated.

  The voltage applied between the cathode including the electron emission source and the anode including the target is approximately 10 kV to 150 kV, although it varies depending on the usage of X-rays. In order to keep the inside of the vacuum vessel in a vacuum and to electrically insulate between the cathode and the anode, the body is constituted by an insulating tube made of an insulating material such as glass or a ceramic material.

  When the X-ray generator tube is driven to emit electrons from the electron emission source, scattered electrons and secondary electrons are generated in the X-ray generator tube, and they may be trapped and charged in the inner periphery of the insulating tube. . When the inner circumference of the insulating tube is charged, the electron beam trajectory is disturbed by the electric field, and the irradiation position and focal spot diameter of the electron beam are changed, and the focal position and dose of the emitted X-ray may be changed. In addition, the distribution of the scattered electron and secondary electron irradiation positions causes variations in the charging position and charge amount on the inner periphery of the insulating tube, causing a potential difference on the inner periphery of the insulating tube, leading to discharge, and the insulating tube It was sometimes damaged.

  Conventionally, a technique for preventing a charge from being accumulated by forming a conductive film made of fine metal particles and a glaze on the inner periphery of an insulating tube is known (see Patent Document 1).

JP 58-44662 A

  However, in Patent Document 1, no special consideration is given to the connection between the low conductive film and the electrode. For this reason, since the connection between the conductive film and the electrode becomes insufficient, scattered electrons and secondary electrons cannot be released, and the conductive film itself is charged, which disturbs the trajectory of the electron beam, There was a possibility that the output fluctuated.

  Here, the conductive film is extended to the end face of the insulating tube, and the conductive film is sandwiched between the end face of the insulating tube and the electrode, and the insulating tube and the electrode are joined, so that the contact between the conductive film and the electrode is achieved. The area is increased and sufficient electrical connection can be achieved. However, when the thickness of the conductive film sandwiched between the end face of the insulating tube and the electrode is uneven and the electrode is inclined, the relative position between the electron emission source and the target may be shifted. There is. In this case, a part of the electron beam is shielded by the anode member holding the target, and there is a possibility that the dose of X-rays generated is reduced.

  The present invention reliably prevents the inner periphery of the insulating tube from being charged by using a conductive film, and at the same time, controls the relative position of the electron emission source and the target with high accuracy to generate a sufficient dose of X-rays. Objective.

In order to achieve the above object, according to a first aspect of the present invention, an anode having a target that generates X-rays upon irradiation of electrons, an anode member that is electrically connected to the target and holds the target, and an electron emission portion A cathode having an electron emission source for irradiating the target with an electron beam and a cathode member electrically connected to the electron emission source, and the target and the electron emission portion in the tube axis direction so as to face each other An X-ray generating tube having one end connected to the anode member and the other end connected to the cathode member, the insulating tube having a groove extending in the tube diameter direction at the one end;
The anode member has a target holding portion that holds the target, and a tubular outer peripheral portion that surrounds the outer peripheral surface on the one end side of the insulating tube and protrudes from the target holding portion to the cathode side,
The anode further includes an inner peripheral conductive film that is an inner peripheral surface of the insulating tube and is spaced apart from the cathode, and an inner conductive film that is positioned in the groove, and the inner conductive film Provides an X-ray generating tube characterized in that it is electrically connected to the tubular outer peripheral portion through the conductive film in the groove.

  According to a second aspect of the present invention, there is provided an X-ray generator comprising the X-ray generator tube according to the first aspect of the present invention and a drive circuit for applying a tube voltage between the anode and the cathode. A device is provided.

  A third aspect of the present invention is the X-ray generator according to the second aspect of the present invention, an X-ray detector that detects X-rays generated from the X-ray generator and transmitted through the specimen, and the X-ray generator. The present invention provides an X-ray imaging system including a system control unit that controls the X-ray detector in an integrated manner.

  According to the present invention, the inner peripheral conductive film is electrically connected to the tubular outer peripheral portion of the anode member via the in-groove conductive film formed in the groove provided at one end of the insulating tube. For this reason, since the conductive film is not interposed between the end face of the insulating tube and the anode member, the relative position between the electron emission source and the target is controlled with high accuracy, and X-ray generation that generates a sufficient dose of X-rays is generated. A tube can be provided. Also, by connecting the conductive film in the groove and the tubular outer peripheral portion of the anode member via the outer peripheral conductive film, the reliability of the electrical connection can be improved, and charging of the inner periphery of the insulating tube can be reliably prevented. Thus, it is possible to provide an X-ray generating tube in which fluctuations in X-ray output are suppressed. In addition, it is possible to provide an X-ray generation apparatus and an X-ray imaging system including a highly reliable X-ray generation tube in which fluctuations in X-ray output are suppressed.

It is explanatory drawing about an example of the X-ray generation tube of this invention, (a) is sectional drawing along the tube axis | shaft of an insulating tube, (b) is A-A 'sectional drawing in (a). 2A and 2B are cross-sectional views of the X-ray generating tube shown in FIG. 1, where FIG. 1A is a cross-sectional view along BB ′ in FIG. 1B, and FIG. 1B is a cross-sectional view along CC ′ in FIG. It is. 2A and 2B are explanatory views of an insulating tube of the X-ray generating tube shown in FIG. 1, in which FIG. 1A is a plan view of an end surface on the anode member side, and FIG. It is a schematic block diagram which shows an example of the X-ray generator of this invention. It is a schematic block diagram which shows an example of the X-ray imaging system of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention.

<X-ray generator tube>
FIG. 1A shows a schematic configuration of a transmission type X-ray generator tube 102 including an electron emission source 3 and a target 9.

  The envelope 111 of the X-ray generation tube 102 is preferably composed of a member having hermeticity for maintaining a degree of vacuum and robustness to withstand atmospheric pressure. The envelope 111 of this example includes an insulating tube 110, a cathode 51 having an electron emission source 3, and an anode 52 having an anode member 43 having a target 9 held by a target holding portion 43a. Yes. The cathode 51 and the anode 52 constitute a part of the envelope 111 by the anode member 43 being joined to one end side of the insulating tube 110 and the cathode member 41 being joined to the other end side. Further, the target 9 serves as a transmission window in which the transmission substrate 21 as a constituent member takes out the X-ray bundle 11 generated by the irradiation of the electron beam bundle 5 onto the target layer 22 to the outside of the X-ray generation tube 102, A part of the envelope 111 is formed. The insulating tube 110 and the bonding of the insulating tube 110 and the anode member 43 will be described in detail later.

  The X-ray generation tube 102 is configured to generate the X-ray flux 11 by irradiating the target layer 22 of the target 9 with the electron beam bundle 5 emitted from the electron emission portion 2 provided in the electron emission source 3. A region 11 a where X-rays are generated in the target layer 22 is referred to as a focal point of the X-ray bundle 11. The target layer 22 is disposed on the electron emission source 3 side of the transmission substrate 21 that transmits X-rays, and the electron emission portion 2 of the electron emission source 3 is disposed to face the target 22. Reference numeral 4 denotes a voltage introduction terminal. As the target layer 22, for example, tungsten, tantalum, molybdenum, or the like is used.

  The anode 52 of this example includes a target 9 that generates X-rays by electron irradiation, and an anode member 43 that defines the anode potential of the target 9. The anode member 43 includes a target holding portion 43 a that holds the target 9 and a tubular outer peripheral portion 43 b that is provided for the purpose of securing a bonding area with the insulating tube 110. As the anode member 43 included in the anode 52, a metal such as kovar, tungsten, molybdenum, stainless steel, or the like is selected. From the viewpoint of matching the linear expansion coefficient with the insulating tube 110, Kovar (US registered trademark of CRS Holdings), Monel (US registered trademark of Special Metals Corporation), and the like are selected.

  The tubular outer peripheral portion 43 b has a sleeve shape extending from the anode member 43 toward the cathode 51. The tubular outer peripheral portion 43 b defines the anode potential on the cathode side of the anode 52. Therefore, the distance from the anode member 43 at the end on the cathode side of the tubular outer peripheral portion 43b is preferably constant from the viewpoint of in-plane symmetry of the potential distribution on the anode side. The in-plane symmetry of the potential distribution means that the potential distribution in the plane parallel to the anode member 42 is continuous in the tube circumferential direction, and there is no locally high electric field region in the tube circumferential direction.

  The target holding unit 43 a is joined to the target 9 and plays a role of holding the target 9. Further, the target holding portion 43 a has a through hole 42, and the target 9 is held in a state of closing the through hole 42 in the middle of the through hole 42. At least the portion of the target holding portion 43a that protrudes from the target 9 toward the outer side of the envelope 111 is made of a heavy metal such as tungsten or tantalum or a material containing heavy metal, so that the emission angle of the X-ray bundle 11 is obtained. It can function as a collimator that restricts As shown in FIG. 1A, the target holding portion 43a may be configured as a series of integral members without joints between a cylindrical portion that supports the target 9 and a ring-shaped portion that supports the portion. And it is good also as a structure which joined and integrated, after forming separately.

  The electron emission source 3 irradiates the target 9 with an electron beam from the electron emission part 2, and for example, a hot cathode such as a tungsten filament or an impregnated cathode, or a cold cathode such as a carbon nanotube can be used. The electron emission source 3 may include a grid electrode (not shown) and an electrostatic lens for the purpose of controlling the beam diameter, electron current density, on / off timing, and the like of the electron beam bundle 5. Electrons contained in the electron beam bundle 5 are energy necessary for generating X-rays in the target layer 22 by an accelerating electric field formed in the internal space 13 of the X-ray generator tube 102 sandwiched between the cathode 51 and the anode 52. To be accelerated.

The internal space 13 of the X-ray generator tube 102 is evacuated for the purpose of ensuring the mean free path of the electron beam bundle 5. The degree of vacuum of the internal space 13 is preferably 10 ⁻⁸ Pa or more and 10 ⁻⁴ Pa or less, and from the viewpoint of the lifetime of the electron emission source 3, it is more preferably 10 ⁻⁸ Pa or more and 10 ⁻⁶ Pa or less. preferable. The internal space 13 of the X-ray generation tube 102 can be evacuated by sealing the exhaust pipe after evacuation using an exhaust pipe (not shown) and a vacuum pump. In addition, a getter (not shown) may be disposed in the internal space 13 of the X-ray generation tube 102 for the purpose of maintaining the degree of vacuum.

  The X-ray generation tube 102 is provided with an insulating tube 110 in the body for the purpose of electrical insulation between the electron emission source 3 defined by the cathode potential and the target layer 22 defined by the anode potential. . The insulating tube 110 is made of an insulating material such as a glass material or a ceramic material. The insulating tube 110 may have a function of defining a distance between the electron emission unit 2 and the target layer 22.

  Next, the structure of the insulating tube 110, the bonding structure of the insulating tube 110 and the anode 52, and the forming method thereof will be described.

  As shown in FIG. 2A, the anode 52 surrounds the outer peripheral surface of the insulating tube 110 on the target holding portion 43 a side, and protrudes from the anode member 43 toward the cathode member 41 to the tubular outer peripheral portion 43 b. have. Further, as shown in FIGS. 3A and 3B, the insulating tube 110 is provided with a groove 116 extending in the tube radial direction on the end surface on the target holding portion 43a side. The groove 116 is provided through the tube wall in the tube diameter direction of the insulating tube 110. An inner peripheral conductive film 112 is formed on the inner peripheral surface of the insulating tube 110. As shown in FIG. 2A, the inner peripheral conductive film 112 is inserted into the groove 116 from the end on the target holding portion 43a side. The conductive film 113 extends. An outer peripheral conductive film 114 extends from the end of the in-groove conductive film 113 on the outer peripheral surface side of the insulating tube 110 to the outer peripheral surface, and the outer peripheral conductive film 114 is electrically connected to the tubular outer periphery via the bonding material 115. It is connected to the part 43b. In the present invention, by forming the outer peripheral conductive film 114 connected to the in-groove conductive film 113 on the outer periphery of the insulating tube 110, the inner peripheral conductive film 112 and the tubular outer peripheral portion 43b are interposed through the in-groove conductive film 113. Can be electrically connected well.

  As shown in FIGS. 3A and 3B, the groove 116 is formed by molding, machining, or the like. As the size of the groove 116, the depth in the tube axis direction is 0.5 mm to 5 mm, and the width in the tube circumferential direction is 0.5 mm to 5 mm. The grooves 116 are formed on the end face of the insulating tube 110, and a plurality of the grooves 116 may be discretely arranged in the tube circumferential direction for the purpose of reliably connecting the inner peripheral conductive film 112 and the outer peripheral conductive film 114. preferable.

  Therefore, when considered as the anode of the X-ray generation tube 102, it can be said that the inner peripheral conductive film 112, the outer peripheral conductive film 114, and the in-groove conductive film 113 are included in the anode 52.

  As the inner peripheral conductive film 112, for example, a metal film of silver, copper, tin, gold, zinc, titanium, molybdenum, manganese, chromium, aluminum, magnesium, a conductive film containing these metals, a metal oxide film, or the like can be applied. . The material can be selected in consideration of the adhesion with the inner peripheral surface of the insulating tube 110. The inner peripheral conductive film 112 can be formed by a method of preparing and applying a paste in which a conductive substance, an organic solvent, a binder, or the like is mixed, or any film forming method such as vapor deposition or sputtering.

  The film thickness of the inner peripheral conductive film 112 is 10 μm to 500 μm, and is a continuous film that has sufficient conductivity and does not expose the inner peripheral surface of the insulating tube 110 in the formation range of the inner peripheral conductive film 112. preferable. Further, as shown in FIG. 1A, the inner peripheral conductive film 112 is provided in a region from the end portion of the insulating tube 110 on the target holding portion 43a side to the intermediate portion in the length direction of the insulating tube 110, It is preferable to be separated from the cathode 51. Preferably, the insulating tube 110 is formed so that the end portion is located closer to the anode 43 than the midpoint in the length direction. Further, the inner peripheral conductive film 112 is continuously formed on the entire circumference in the tube circumferential direction. By doing so, the breakdown voltage in the X-ray generation tube 102 can be prevented from failing, and charging of the inner periphery of the insulating tube 110 in the region where the electron beam bundle 5 is emitted can be prevented.

  The in-groove conductive film 113 can use the same material, formation method, and film thickness as the inner peripheral conductive film 112, and is preferably formed so as to be continuous with the inner peripheral conductive film 112. When forming the conductive film 113 in the groove, the paste material is applied only in the groove 116 so that the conductive film does not adhere to the end face of the insulating tube 110, or the mask is disposed on the end face of the insulating tube 110. A method of applying a material or forming a film is preferable.

  The outer conductive film 114 can be formed using the same material, formation method, and film thickness as the inner conductive film 112, and is preferably formed so as to be continuous with the in-groove conductive film 113. The outer peripheral conductive film 114 is preferably formed on the entire circumference continuously in the tube circumferential direction. FIG. 2B shows a form in which the outer peripheral conductive film 114 is not formed by the depth of the groove 116 from the end of the insulating tube 110 on the target holding portion 43a side. It is not limited to. In the present invention, it is sufficient that no conductive film is formed on the end surface of the insulating tube 110 on the target holding portion 43 a side, and the outer peripheral conductive film 114 is formed in the region excluding the groove 116 in the tube circumferential direction of the insulating tube 110. It may be formed up to the end.

  In order to simplify the process and to make it easier to form a film continuous with the inner peripheral conductive film 112, the in-groove conductive film 113 and the outer peripheral conductive film 114 are preferably formed simultaneously with the inner peripheral conductive film 112.

  The insulating tube 110 and the tubular outer peripheral portion 43b are formed so that the peripheral portion of the anode member 43 faces the end surface of the insulating tube 110 on which the inner peripheral conductive film 112, the groove conductive film 113, and the outer peripheral conductive film 114 are formed as described above. Bonding is performed via the bonding material 115 and the outer peripheral conductive film 114. Thereby, the tubular outer peripheral portion 43b and the outer peripheral conductive film 114 are electrically connected. At this time, there is no conductive film on the end face of the insulating tube 110, and the end face of the insulating tube 110 and the anode member 43 are in direct contact. The both end surfaces of the insulating tube 110, the cathode member 41 and the anode member 42 define the relative positions of the electron emission source 3 supported by the cathode member 41 and the target 9 supported by the anode member 42. It is defined in advance with high accuracy. Therefore, since the conductive film that deteriorates the parallelism does not exist on the end face of the insulating tube 110, the relative position between the electron emission source 3 and the target 9 can be controlled with high accuracy in the present invention, and the target holding portion 43a. A reduction in the dose of the X-rays 11 due to the shielding of the electron beam bundle 5 due to. Further, the inner peripheral conductive film 112 is physically connected to the anode member 43 via the in-groove conductive film 113, the outer peripheral conductive film 114, and the tubular outer peripheral portion 43b, so that the inner peripheral conductive film 112 and the anode member 43 are connected to each other. The reliability of electrical connection can be improved.

  Furthermore, since the anode member 43 is connected to the drive circuit 103 as the anode 52, the charge due to scattered electrons and secondary electrons in the X-ray generator tube 102 is transferred to the inner peripheral conductive film 112, the in-groove conductive film 113, and the outer periphery. It can escape to the outside through the conductive film 114. Therefore, charging of the inner periphery of the insulating tube 110 can be prevented, and the X-ray generation tube 102 in which fluctuations in X-ray output are suppressed can be provided.

  Further, in order to keep the inside of the X-ray generation tube 102 in a vacuum, the insulating tube 110 and the tubular outer peripheral portion 43b are hermetically joined. By performing hermetic bonding of the X-ray generation tube 102 on the outer periphery of the insulating tube 110, a sufficient bonding area can be secured, and bonding can be performed without the target holding portion 43a being displaced in the tube radial direction. Further, the insulating tube 110 and the tubular outer peripheral portion 43 b are joined via the outer peripheral conductive film 114, so that the tubular outer peripheral portion 43 b is electrically joined to the in-groove conductive film 113 via the outer peripheral conductive film 114. . Therefore, by setting the outer peripheral conductive film 114 in an annular shape continuous to the outer periphery of the insulating tube 110, the insulating tube 110 and the tubular outer peripheral portion 43b are joined with good airtightness, and the tubular outer peripheral portion 43b and the inner peripheral conductive film 112 are Can have good electrical connection.

  The hermetic bonding can be performed by arranging the bonding material 115 in an annular shape, and can be performed by brazing using a brazing material as the bonding material 115. As the brazing material, for example, a brazing material mainly composed of Au—Cu, nickel brazing, brass brazing, and silver brazing can be used. Specifically, wire rods made of these brazing materials are wound around the joining position of the insulating tube 110, the anode 52 is attached in a fastened state, and the brazing material can be melted by heating to join. A step is provided so that the outer diameter of the end portion of the insulating tube 110 on the target holding portion 43a side is smaller than that of the cathode 51, and the wire is attached to the end portion where the outer diameter is reduced by the step. Thus, the wire can be easily attached to the insulating tube 110, which is preferable. Further, in the tube axis direction of the insulating tube 110, the tubular outer peripheral portion 43b and the outer peripheral conductive film 114 are preferably opposed to each other in a range of 2 mm to 5 mm and brazed in such a range.

  In the case where the insulating tube 110 is a ceramic material such as alumina, the surface of the insulating tube 110 is preferably metallized in order to increase the reliability of hermetic bonding. As a metallization method, for example, there is a method of applying a heat treatment by applying a metallized material such as Ti—Cu or Mo—Mn to the surface of the insulating tube 110. The metallized film formed by metallization also functions as a conductive film. Therefore, it is preferable to form the inner peripheral conductive film 112, the in-groove conductive film 113, and the outer peripheral conductive film 114 from a metallized material. In addition, a method of brazing the tubular outer peripheral portion 43b and the outer periphery of the insulating tube 110 via the outer peripheral conductive film 114 is preferable in terms of simplifying the process and improving the reliability of vacuum holding in the X-ray generation tube 102. .

  For the cathode member 41, the anode member 42, and the tubular outer peripheral portion 42a to be joined to the insulating tube 110, a metal material having a linear expansion coefficient close to that of the insulating tube 110 is selected, and kovar is preferably used. For joining the cathode member 41 and the insulating tube 110, a brazing material similar to the joining material 115 is preferably used.

  In this way, by airtightly bonding the insulating tube 110 and the tubular outer peripheral portion 43b, even if a gap is formed between the end surface of the insulating tube 110 and the anode member 43 by the groove 116, the outside of the X-ray generating tube 102 is removed. The airtightness in the envelope 111 can be maintained.

<X-ray generator>
As shown in FIG. 4, the X-ray generation apparatus 101 of the present invention drives the X-ray generation tube 102 and the X-ray generation tube 102 in FIG. 1 inside a storage container 120 having an X-ray transmission window 121. Drive circuit 103. The storage container 120 and the drive circuit 103 are grounded. The drive circuit 103 is a tube voltage circuit that applies a tube voltage Va between the cathode 51 and the anode 52. When the tube voltage Va is applied between the cathode 51 and the anode 52 by the driving circuit 103, an accelerating electric field is formed between the target layer 22 and the electron emission portion 2. Corresponding to the layer thickness of the target layer 22 and the metal type, the tube type Va can be set as appropriate to select the line type necessary for imaging.

  The storage container 120 for storing the X-ray generation tube 102 and the drive circuit 103 is preferably a container having sufficient strength as a container and excellent in heat dissipation, and examples of its constituent materials include brass, iron, stainless steel, A metal material such as is used. An extra space other than the X-ray generation tube 102 and the drive circuit 103 inside the storage container 120 is filled with an insulating liquid 109. The insulating liquid 109 is a liquid having electrical insulation, and has a role of maintaining electrical insulation inside the storage container 120 and a role as a cooling medium for the X-ray generation tube 102. As the insulating liquid 109, it is preferable to use an electric insulating oil such as mineral oil, silicone oil or perfluoro oil.

<X-ray imaging system>
Next, a configuration example of an X-ray imaging system including the X-ray generation tube 102 of the present invention will be described with reference to FIG. The X-ray imaging system 60 of the present invention includes an X-ray generation apparatus 101 shown in FIG. 4, an X-ray detector 206 that detects X-rays 11 generated from the X-ray generation apparatus 101 and transmitted through the subject 204. And a system control unit 202. The system control unit 202 integrally controls the X-ray generator 101 and the X-ray detector 206. The drive circuit 103 outputs various control signals to the X-ray generation tube 102 under the control of the system control unit 202. The emission state of the X-ray bundle 11 emitted from the X-ray generator 101 is controlled by a control signal output from the drive circuit 103. The irradiation range of the X-ray bundle 11 emitted from the X-ray generation device 101 is adjusted by a collimator unit (not shown) having a movable diaphragm, is emitted to the outside of the X-ray generation device 101, and passes through the subject 204. And detected by the detector 206. The detector 206 converts the detected X-rays into image signals and outputs them to the signal processing unit 205. The signal processing unit 205 performs predetermined signal processing on the image signal under the control of the system control unit 202 and outputs the processed image signal to the system control unit 202. The system control unit 202 outputs a display signal for displaying an image on the display device 203 based on the processed image signal. The display device 203 displays an image based on the display signal on the screen as a captured image of the subject 204.

  The X-ray imaging system of the present invention can be used for nondestructive inspection of industrial products and pathological diagnosis of human bodies and animals.

Example 1
The X-ray generator tube 102 having the insulating tube 110 and the junction structure of the insulating tube 110 and the anode member 43 shown in FIGS. 1 to 3 was manufactured and mounted on the X-ray generator 101.

  As shown in FIG. 3, a groove 116 extending in the tube radial direction was formed on the end surface of the alumina insulating tube 110 on the anode 52 side. The groove 116 had a width of 2 mm and a depth of 1 mm, and was formed by machining at two locations on the end surface of the insulating tube 110 in the tube circumferential direction. The length of the inner peripheral surface of the tubular outer peripheral portion 43b in the tube axis direction of the insulating tube 110 was 4 mm.

  Next, the inner peripheral conductive film 112, the in-groove conductive film 113, and the outer peripheral conductive film 114 were formed on the insulating tube 110. The material of the inner peripheral conductive film 112, the in-groove conductive film 113, and the outer peripheral conductive film 114 was a Ti—Cu-based material used as a ceramic metallization material. As a forming method, a paste containing Ti—Cu-based powder was prepared and applied directly to the insulating tube 110. At this time, the end surface of the insulating tube 110 was masked in advance so that the conductive film did not adhere to the end surface of the insulating tube 110. Next, after drying the Ti—Cu-based paste, the masking was removed and heat treatment was performed at 1000 ° C. in a vacuum. The film thicknesses of the inner peripheral conductive film 112, the in-groove conductive film 113, and the outer peripheral conductive film 114 after the heat treatment are approximately 10 μm to 300 μm, although there are variations depending on the location. In FIG. 2A, the length in which the outer peripheral conductive film 114 and the tubular outer peripheral portion 43b are opposed to each other in the tube axis direction of the insulating tube 110 in the region having the groove 116 is 3 mm. In the region without the groove 116, the outer peripheral conductive film 114 is formed up to the side end of the target holding portion 43 a of the insulating tube 110, and the outer peripheral conductive film 114 and the tubular outer peripheral portion 43 b are formed in the tube axis direction of the insulating tube 110. The opposing length was 4 mm.

  Next, an Ag brazing wire is wound around the outer peripheral conductive film 114 on the outer periphery of the end portion of the insulating tube 110 on the side of the target holding portion 43a at the portion to be joined to the tubular outer peripheral portion 43b protruding from the target holding portion 43a. The outer periphery of the tube 110 and the tubular outer peripheral portion 43b were joined by brazing. Brazing was performed by vacuum heat treatment at 800 ° C. Thereby, the X-ray generating tube 102 was obtained.

  Next, the X-ray generation tube 102 of this example was mounted on the X-ray imaging system shown in FIG. 5, and the output fluctuation of the X-ray was evaluated. In this evaluation, the subject 204 was not disposed, the X-ray generation tube 102 was driven, and the variation in the position of the focal point 11a of the X-ray bundle 11 was evaluated. As a result, the time variation of the center position of the focal point 11a was as good as 10 μm or less.

  Further, when a dosimeter (not shown) was placed in front of the detector 206 and the X-ray generation tube 102 was driven with a tube voltage of 100 kV and a tube current of 10 mA, it was confirmed that a dose of 120 μGy was output.

(Comparative Example 1)
The groove 116 is not formed on the end face of the insulating tube 110 on the anode 52 side, and instead, the end face conductive film continuous with the inner peripheral conductive film 112 and the outer peripheral conductive film 114 is formed on the entire end face. An X-ray generator tube 102 was produced with the same configuration and production method. As a result of measuring the film thickness after forming the end face conductive film, the film thickness was uneven depending on the location, and a maximum film thickness difference of 300 μm was confirmed.

  As in Example 1, the X-ray generator tube 102 of this example was driven, and the variation in the position of the focal point 11a of the X-ray bundle 11 was evaluated. As a result, the variation in the central position of the focal point 11a was 10 μm or less. . However, when the X-ray generator tube 102 was driven under the same conditions as in Example 1 and the X-ray dose was measured, the dose was 100 μGy, which was 17% lower than that in Example 1. In order to analyze the cause of the dose reduction, the image of the focal point 11a of the X-ray bundle 11 was analyzed in detail, and it was confirmed that the area of the focal point 11a was 20% smaller than that in Example 1. For this reason, the parallelism between the electron emission source 3 and the target 9 deteriorates due to the unevenness of the film thickness of the end face conductive film, and a part of the electron beam bundle 5 is blocked by the target support portion 42 that holds the target 9. The dose was estimated to have decreased.

(Example 2)
Using the X-ray generator 101 described in Example 1, the X-ray imaging system illustrated in FIG. In the X-ray imaging system of this example, an X-ray imaging image having a high S / N ratio can be acquired by including the X-ray generation apparatus 101 in which fluctuations in X-ray output are suppressed.

  2: electron emission part, 3: electron emission source, 5: electron beam bundle, 9: target, 11: X-ray bundle, 41: cathode member, 43: anode member, 43a: target holding part, 43b: tubular outer peripheral part, 51: Cathode, 52: Anode, 101: X-ray generator, 102: X-ray generator tube, 103: Drive circuit, 110: Insulating tube, 112: Inner conductive film, 113: In-groove conductive film, 114: Outer conductive film, 115: bonding material, 202: system control unit, 204: subject, 206: X-ray detector

Claims (12)

An anode having a target that generates X-rays upon irradiation of electrons and an anode member that is electrically connected to the target and holds the target, an electron emission source that irradiates the target with an electron beam from an electron emission portion, and the electrons A cathode having a cathode member electrically connected to an emission source, and one end in the tube axis direction is connected to the anode member and the other end is connected to the cathode member so that the target and the electron emission portion face each other. An insulating tube, and an X-ray generating tube, wherein the insulating tube has a groove extending in a tube radial direction at the one end,
The anode member has a target holding portion that holds the target, and a tubular outer peripheral portion that surrounds the outer peripheral surface on the one end side of the insulating tube and protrudes from the target holding portion to the cathode side,
The anode further includes an inner peripheral conductive film that is an inner peripheral surface of the insulating tube and is spaced apart from the cathode, and an inner conductive film that is positioned in the groove, and the inner conductive film Is electrically connected to the tubular outer peripheral portion through the conductive film in the groove.   The X-ray generating tube according to claim 1, wherein a plurality of the grooves are arranged in a tube circumferential direction of the insulating tube.   The X-ray generating tube according to claim 1, wherein the groove penetrates the thickness of the tube wall in the tube radial direction of the insulating tube.   4. The X-ray generating tube according to claim 1, wherein the inner peripheral conductive film and the in-groove conductive film form a continuous film. 5.   The X-ray generating tube according to claim 1, wherein the insulating tube is hermetically joined to the anode at the tubular outer peripheral portion.   The X-ray generating tube according to claim 5, wherein the tubular outer peripheral portion is joined to the insulating tube via an annular joining material. An outer peripheral conductive film connected to the groove conductive film on the outer periphery of the insulating tube;
The X-ray generating tube according to claim 1, wherein the tubular outer peripheral portion is electrically connected to the in-groove conductive film through the outer peripheral conductive film.   The X-ray generating tube according to claim 7, wherein the outer peripheral conductive film extends in an annular shape in the tube circumferential direction.   9. The X-ray generating tube according to claim 7, wherein the in-groove conductive film and the outer peripheral conductive film constitute a continuous film.   The X-ray generating tube according to claim 1, wherein the inner peripheral conductive film is continuously provided in a tube circumferential direction of the insulating tube.   An X-ray generator comprising: the X-ray generator tube according to claim 1; and a drive circuit that applies a tube voltage between the anode and the cathode.   12. The X-ray generation apparatus according to claim 11, an X-ray detector that detects X-rays generated from the X-ray generation apparatus and transmitted through a subject, and the X-ray generation apparatus and the X-ray detector are integrated. An X-ray imaging system comprising: a system control unit for controlling the system.

Images