JP2008159317A - X-ray tube device and x-ray apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct the movement of a focus position and a focal dimension by optimizing a deflecting magnetic field to deflect the electron beam of an X-ray tube device. <P>SOLUTION: An electromagnet 40 serving as a deflecting magnetic field generating means is disposed in close vicinity to the envelope 16 of an X-ray tube 10. The electromagnet 40 has a U-shaped iron core 40 and a winding 44, the end faces 42a, 42b of the rod of the iron core 42 are processed to inclined surfaces, and the deflecting magnetic field is formed in a gap 46 between the end faces 42a, 42b. The inclined surfaces of the end faces 42a, 42b are processed so that the distance of the gap 46 becomes larger as they part from a tube axis 48 in the main radiating direction 35 of X-rays. Therefore, when the magnet 40 is excited, the magnetic field intensity of the deflecting magnetic field becomes high in a place close to the tube axis 48, and becomes low in a remote place. When deflecting the electron beam by this deflecting magnetic field, a large focal length dimension can be obtained in comparison with a conventional magnetic field having uniform intensity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an X-ray tube apparatus used for an X-ray CT apparatus and the like, and in particular, an X-ray tube apparatus capable of moving the position of a focal point on a target by deflecting an electron beam forming a focal point with a deflection magnetic field. About.

  The rotary anode X-ray tube device is configured to generate an X-ray from the target by colliding an electron beam generated at the cathode with a target of the rotary anode rotating at a high speed of the rotary anode X-ray tube. In the rotating anode, the target is rotatably supported by a rotating mechanism, and the rotating mechanism is composed of a rotating body to which the target is connected and a fixed body that supports the rotating body, and a bearing is provided between the rotating body and the fixed body. ing. A stator for rotationally driving the rotating body is disposed around the rotating anode.

  In a rotating anode X-ray tube device, an electron beam emitted from a cathode filament is accelerated and focused by an X-ray tube voltage applied between the cathode and the rotating anode, for example, a voltage of 100 to 150 kV. , Collide with the target to form an actual focal point as an X-ray generation source. When electrons having high energy, for example, energy of 100 to 150 keV, collide with the target, the electrons are rapidly decelerated in the target, braking X-rays are generated, and X-rays are emitted from the actual focus of the target. At this time, about 1% of the kinetic energy of the electrons colliding with the target is converted into X-rays, and the remaining 99% of the energy is converted into heat, so that the target is heated by this heat. Due to this heat, the temperature of the target as a whole rises to about 1000 ° C., the temperature of the actual focal plane rises to 2000 ° C. or more, and this heat is further conducted to each part constituting the rotating anode, so that the temperature of each part Rises to several hundred degrees Celsius. As the temperature rises, each part of the rotating anode thermally expands, and the target moves to the cathode side along the central axis of the rotating anode (usually corresponding to the central axis of the X-ray tube). The amount of movement of the target at this time is 500 μm or more, and as a result of the movement of the target, the position of the actual focal point on the target moves by the same amount.

  The X-ray dose distribution of the X-ray incident on the X-ray detection unit (dosimeter) fluctuates in an X-ray inspection apparatus equipped with the X-ray tube apparatus, for example, an X-ray CT apparatus, by moving the actual focus position of the X-ray tube apparatus However, there is a problem that the X-ray image is deteriorated. This problem is particularly noticeable when an inspection is performed with a small slice width by an X-ray CT apparatus.

As countermeasures for the problem of the movement of the actual focal point of the X-ray tube apparatus, there are proposed ones that are performed by the X-ray tube apparatus itself and those that are performed at a portion of the X-ray apparatus that supports the X-ray tube apparatus. . As an example of the former, there is one disclosed in Patent Document 1. Patent Document 1 discloses a technique for compensating by deflecting an electron beam from the cathode of an X-ray tube with a deflection coil and moving the position of the actual focal point on the anode target. In this technique, first, in an X-ray tube apparatus, a deflection coil is disposed in the vicinity of a cathode outside the X-ray tube, and an electric current is passed through the deflection coil to deflect an electron beam in the radial direction of the disk-shaped target. A deflection magnetic field is generated. Next, on the X-ray apparatus side, the X-ray detector detects the amount of movement of the actual focal point of the X-ray tube from the X-ray dose distribution or the like. Next, the amount of current flowing through the deflection coil is adjusted to deflect the electron beam in the radial direction on the target. Due to the deflection of the electron beam, the position of the real focus moves in the direction opposite to the movement direction of the real focus, thereby compensating for the movement amount of the real focus.
US Pat. No. 5,550,889

  As an example of the latter, a moving mechanism for moving the entire X-ray tube apparatus in a direction parallel to the rotation axis of the anode of the X-ray tube is provided on a support base that supports the X-ray tube apparatus. The X-ray tube apparatus is moved by the same movement amount in the direction opposite to the movement of the actual focal point by cooperating with a focal movement amount detecting mechanism for detecting the movement amount of the actual focal point of the tube apparatus. Some compensate for the amount of movement of the actual focal point of the tube apparatus. In this conventional example, since the entire X-ray tube apparatus is moved, there is a problem that the moving mechanism becomes a large structure.

  In the X-ray apparatus described in Patent Document 1, it is possible to easily deflect the electron beam emitted from the cathode of the X-ray tube by the deflection magnetic field formed by the deflection magnetic field generating means. As a result, it is easy to move the position of the actual focal point formed on the anode target. However, since the deflection magnetic field generating means uses a large-diameter coil to form a deflection magnetic field having a substantially uniform magnetic field strength in the space between the cathode and the anode of the X-ray tube, the following problems arise. There is.

  The first problem is that when the X-ray tube apparatus is mounted on the X-ray CT apparatus, the magnetic flux generated by the large-diameter coil serving as the deflection magnetic field generating means leaks outside through the X-ray tube container of the X-ray tube apparatus. As a result, the deflection magnetic field generating means rotates while generating a magnetic flux around the scanner, causing an eddy current to be generated in the components of the scanner body.

  The second problem is that the deflecting magnetic field generating means is such that a copper wire or the like is wound around a large-diameter coil, so that the magnetic field generating efficiency at the time of generating the deflecting magnetic field is poor and a large amount of heat is released from the coil. There is a problem that no consideration is given to the cooling means for the heat generation of the coil itself.

  The third problem is that when the electron beam emitted from the cathode of the X-ray tube is deflected by the substantially uniform deflection magnetic field formed by the deflection magnetic field generating means, the area of the actual focus formed on the target increases. In the former case, the effective focal length viewed from the X-ray main radiation direction, which is the direction in which X-rays are used, increases, causing a reduction in resolution during X-ray imaging. In the latter case, the actual focal plane temperature increases due to a decrease in the area of the actual focal spot, and the load resistance as an X-ray tube decreases.

  The third problem is caused by a change in the length of the actual focal point when the electron beam is deflected, and is closely related to the present invention, and will be described in detail below with reference to FIG. FIG. 7 is a diagram for explaining the change in the length of the actual focal point when the electron beam from the cathode of the X-ray tube is deflected by a deflecting magnetic field having a substantially uniform magnetic field strength. FIG. 7A shows a case where the electron beam is deflected in a direction approaching the central axis of the X-ray tube, and FIG. 7B shows a case where the electron beam is deflected in a direction away from the central axis of the X-ray tube. FIG. 7 is an enlarged view of a portion where an electron beam of the X-ray tube travels, that is, a portion where the cathode 12 (cathode support 24) and the rotary anode 14 of the X-ray tube face each other and the vicinity thereof. In FIG. 7A, the focusing electrode 22 of the cathode 12 and the inclined surface 28a of the disk-shaped target 28 of the rotating anode 14 are arranged to face each other, and the electron beam 18 emitted from the filament 20 included in the focusing electrode 22 is disposed. Travels toward the inclined surface 28a of the target 28, collides with the target 28, and generates X-rays. At this time, an actual focus (X-ray source) 100 corresponding to the cross-sectional area of the electron beam 18 is formed on the surface of the target 28. A high voltage of 60 to 150 kV is applied between the cathode 12 and the rotating anode 14 of the X-ray tube, and a deflection magnetic field having a substantially uniform magnetic field strength is formed in the space between the focusing electrode 22 and the inclined surface 28a of the target 28. Is formed. In this case, the deflection magnetic field is for deflecting the electron beam 18 in the direction of the arrow 101 by electromagnetic force, and the magnetic flux is directed from the back side to the front side of the drawing. In FIG. 7A, solid outlines 100a and 100b of the electron beam 18 are those of the electron beam 100 in a state where no deflection magnetic field is applied, and the broken outlines 102a and 102b of the electron beam 18 are magnetic fluxes on the front surface. The electron beam 102 is in a state where a deflection magnetic field directed to the side is applied. Hereinafter, the electron beam 100 in a state in which a deflection magnetic field is not applied is referred to as a magneticless electron beam 100, and the electron beam 102 in a state in which a deflection magnetic field in which the magnetic flux is directed toward the front side is referred to as a front-facing magnetic flux application electron beam, Contour lines 100a and 102a closer to the center axis 48 of the electron beam 18 are referred to as inner electron beams, and contour lines 100b and 102b away from the center axis 48 of the X-ray tube are referred to as outer electron beams. I will decide.

  In FIG. 7A, when the deflection magnetic field is applied to the electron beam 18, the electron beam 18 is deflected in a direction approaching the central axis 48 of the X-ray tube, but the inner electron beam 102a and the outer electron beam are deflected. Since the traveling distance between the cathode 12 and the rotating anode 14 is different from that of 102b and the outer electron beam 102b is longer, the outer electron beam 102b is inner electron beam 102a when deflected by a deflecting magnetic field having a uniform magnetic field strength. Is more greatly deflected. As a result, the distance 102c between the inner electron beam 102a and the outer electron beam 102b when the front-facing magnetic flux applying electron beam 102 collides with the inclined surface 28 of the target 28 is equal to the inner electron beam 100a and the outer electron of the magnetic fieldless electron beam 100. It becomes smaller than the distance 100c from the line 100b. Here, since the distance between the inner electron beam and the outer electron beam corresponds to the length of the actual focal point, the length of the actual focal point after deflection by the deflection of the electron beam by the deflection magnetic field of the front-facing magnetic flux from the above results. The dimension 102c is reduced from the actual focal length 100c before deflection, and the area of the actual focal spot is also reduced accordingly. This reduction in the area of the actual focal point reduces the load resistance of the X-ray tube. Further, the effective focus length dimension 102d after deflection is smaller than the effective focus length dimension 100d before deflection.

  Next, in FIG. 7B, the direction of the magnetic flux of the deflection magnetic field is opposite to that in FIG. 7A, and is from the front side to the back side of the paper. Others are the same as in the case of FIG. 7B, since the direction of the magnetic flux of the deflection magnetic field is opposite to that of FIG. 7A, the electron beam 18 is moved away from the central axis 48 of the X-ray tube by the deflection magnetic field as indicated by an arrow 103. It is deflected in a direction away from the central axis 48 of the X-ray tube in response to the electromagnetic force directed to it. Here, the electron beam 104 in a state in which a magnetic flux is deflected toward the back side is given as the back-facing magnetic flux applying electron beam, the contour 104a closer to the central axis 48 of the X-ray tube as the inner electron beam, and the X The contour 104b on the side away from the central axis 48 of the ray tube will be referred to as an outer electron beam. Also in this case, the inner electron beam 104a and the outer electron beam 104b have different traveling distances between the cathode 12 and the rotating anode 14, and the outer electron beam 104b is longer. Deflection greater than 104a. As a result, the interval 104c between the inner electron beam 104a and the outer electron beam 104b when the back surface magnetic flux applying electron beam 104 collides with the inclined surface 28a of the target 28 becomes larger than the interval 100c of the magnetic fieldless electron beam 100. Since the distances 100c and 104c correspond to the length of the actual focus, when the electron beam 18 is deflected by the deflecting magnetic field of the back-facing magnetic flux, the length of the actual focus 104c is the length of the actual focus before the deflection. The dimension is larger than 100c. As a result, the effective focus length 104d as viewed from the X-ray main radiation direction after deflection by the deflection magnetic field of the back-facing magnetic flux is also larger than the effective focus length 100d before deflection. It causes the fall of.

  In view of the above, in the present invention, when the electron beam from the cathode of the X-ray tube is deflected by using a deflection magnetic field, there is no change in the size of the actual focal point, no reduction in load resistance and resolution, and the X-ray tube. An object of the present invention is to provide an X-ray tube apparatus in which magnetic field leakage to the outside of the apparatus is reduced and an X-ray apparatus using the same.

  In order to solve the above-mentioned problems, in the X-ray tube apparatus of the present invention, a cathode having an electron generation source that emits electrons and a focusing electrode that focuses the electrons emitted from the electron generation source into a narrow beam of electron beams; An anode having a target that is disposed opposite to the cathode and on which an X-ray source (hereinafter referred to as a real focal point) that emits X-rays by colliding with an electron beam is formed; An X-ray tube having an envelope sealed in a vacuum-tight manner, and an X-ray tube disposed at the periphery of the envelope of the X-ray tube and deflecting a magnetic field for deflecting an electron beam from the cathode An X-ray tube apparatus comprising: a deflection magnetic field generating means formed in a space between a cathode and an anode of the X-ray tube; and an X-ray tube container containing the X-ray tube and the deflection magnetic field generating means. Regardless of the magnetic field strength and direction of the magnetic field, the real focus is viewed from the X-ray main radiation direction. Dimensions (hereinafter, referred to as an effective focal dimensions) are those having a means for substantially maintaining a constant value (claim 1).

  In the X-ray tube apparatus of the present invention, the magnetic field intensity of the deflection magnetic field formed by the deflection magnetic field generating means in the space in which the electron beam travels between the cathode and the anode of the X-ray tube (hereinafter referred to as the deflection magnetic field space) is In the direction orthogonal to the central axis of the X-ray tube (hereinafter abbreviated as the tube axis) and parallel to the X-ray main radiation direction, the distance increases or decreases almost monotonously with the distance (claim 2).

  In the X-ray tube apparatus of the present invention, a cathode having an electron generating source that emits electrons, a focusing electrode that focuses the electrons emitted from the electron generating source into a thin beam-shaped electron beam, and the cathode are opposed to each other. An X-ray comprising an anode having a target disposed on the opposite surface and having a target on which a real focal point for emitting X-rays by colliding with an electron beam is formed, and an envelope for sealing the cathode and the anode in a vacuum-tight manner A deflecting magnetic field generating means for forming a deflecting magnetic field for deflecting an electron beam from a cathode in a deflecting magnetic field space of the X-ray tube, disposed in the periphery of the envelope of the tube and the X-ray tube; And an X-ray tube device including a deflection magnetic field generating means, the deflection magnetic field generation means includes one or more electromagnets, and the electromagnet has iron with a gap (gap) in which the deflection magnetic field is generated. The electromagnet has a core and a winding wound around an iron core. The X-ray tube is disposed so as to contain the deflection magnetic field space in the gap between the iron cores.

  In the X-ray tube device of the present invention, the end faces on both sides forming the gap between the iron cores of the electromagnet are formed such that the distance between the both end faces increases or decreases almost monotonously in the X-ray main radiation direction. . In addition, at least one of the both end surfaces of the iron core of the electromagnet is a surface that is inclined in the X-ray main radiation direction.

  In the X-ray tube apparatus of the present invention, the deflection magnetic field generating means has two or more electromagnets, and the adjacent electromagnets are arranged so that the end surfaces of the iron cores are arranged substantially parallel and close to the X-ray main radiation direction. Arranged and excited so that there is a difference in the magnetic field strength in the X-ray main radiation direction of the deflection magnetic field generated in the gap between the iron cores, and the magnetic field strength in the X-ray main radiation direction of the deflection magnetic field as a whole is almost monotonous. Increase or decrease.

  In the X-ray tube apparatus of the present invention, the deflection magnetic field generating means has two electromagnets having substantially the same excitation capability, and the end surfaces of the iron cores of the two electromagnets are substantially parallel to the X-ray main radiation direction. In addition, they are arranged so as to be close to each other, and provide a difference in the excitation currents flowing through the windings of the two electromagnets.

  The X-ray apparatus of the present invention is an X-ray apparatus comprising an X-ray tube device, an X-ray detection means, an X-ray control means, and an X-ray image forming means. An X-ray tube apparatus, in which an X-ray detection means controls focal position movement detection means for detecting movement of the actual focal position of the X-ray tube apparatus, and an X-ray control means controls deflection magnetic field generation means in the X-ray tube apparatus. Each includes a deflection magnetic field control means, and the deflection magnetic field control means adjusts the magnetic field strength of the deflection magnetic field generated by the deflection magnetic field generation means based on the focal position movement information and the effective focal spot size information from the focal position movement detection means. (Claim 3).

  In the X-ray apparatus of the present invention, the deflection magnetic field generating means is an electromagnet having an iron core and a winding, and the deflection magnetic field control means is an electromagnet power supply that supplies an excitation current to the electromagnet, and an electromagnet power supply control that controls the electromagnet power supply. Part.

  In the X-ray tube apparatus of the present invention, an electron beam from the cathode is introduced into the deflection magnetic field space between the cathode and the anode in the X-ray tube by the deflection magnetic field generating means disposed in the periphery of the envelope of the X-ray tube. A deflecting magnetic field is formed to deflect the electron beam so that the effective focus size when the actual focus is viewed from the X-ray main radiation direction is maintained at a substantially constant value, and the position of the effective focus is maintained at a substantially constant position. Therefore, there is a problem that the focal position moves during use and artifacts are generated in the X-ray image, a problem that the focal dimension is increased and the image quality of the X-ray image is deteriorated, and the focal dimension is reduced. Therefore, the problem that the load resistance of the X-ray tube is lowered is eliminated, and high performance can be maintained (claim 1).

  In the X-ray tube apparatus of the present invention, a deflection magnetic field in which the magnetic field strength increases or decreases almost monotonously in a direction parallel to the X-ray main radiation direction is generated in the deflection magnetic field space in the X-ray tube by the deflection magnetic field generating means. Therefore, it is possible to move the effective focus in the tube axis direction and increase or decrease the length of the effective focus. Normally, the effective focal length decreases in a deflection magnetic field with a monotonically increasing magnetic field strength, and the effective focal length increases in a monotonically decreasing deflection magnetic field. By the above combination, the movement of the effective focus and the length of the effective focus (actual focus length) are corrected to improve the image quality of the X-ray image and the load resistance of the X-ray tube. (Claim 2).

  Further, in the X-ray tube apparatus of the present invention, the deflection magnetic field generating means for generating the deflection magnetic field in the deflection magnetic field space in the X-ray tube includes an electromagnet having an iron core and a winding having a gap in which the deflection magnetic field is generated, Since the deflection magnetic field space is included in the gap between the iron cores, the spread of the magnetic flux generated by the electromagnet is concentrated in the iron core, the gap between the iron cores, and the surrounding area. Compared with the case of the deflection magnetic field generating means having no large-diameter winding alone, the spread of the magnetic flux is remarkably reduced. As a result, the problem that an eddy current is generated in the constituent material of the scanner main body by the magnetic flux generated by the deflection magnetic field generating means when mounted on the scanner of the X-ray CT apparatus and rotated is also avoided. In addition, since the above-mentioned electromagnet is wound around an iron core to generate a magnetic flux for creating a deflection magnetic field in the gap between the iron cores, the magnetic field generation efficiency when generating a deflection magnetic field is limited to that of conventional windings. Compared to the case of electromagnets, it is much improved, and the heat radiation from the windings is greatly reduced.

  In the X-ray tube apparatus of the present invention, the distance between both end surfaces that form the gap between the iron cores of the electromagnet of the deflection magnetic field generating means changes in the X-ray main radiation direction, and is formed so as to increase or decrease almost monotonously. Therefore, the magnetic field strength in the X-ray main radiation direction of the deflection magnetic field space enclosed in the gap between the iron cores also decreases or increases almost monotonously (the magnetic field strength is low at a large interval and the magnetic field at a small interval). Strength increases). As a result, the effective focal length can be increased when the distance between both end faces increases almost monotonically, and the effective focal length can be reduced when the distance decreases almost monotonically. Can do. In addition, when both end faces or one end face of the iron core of the electromagnet is inclined in the X-ray main radiation direction, the shape of the end face of the iron core becomes simple, and the gap interval can be changed by changing the inclination angle of the end face. And the change rate of the magnetic field strength can be easily and variously changed. At the same time, since the shape of the end face is simple, machining becomes easy, which contributes to reduction of machining costs.

  Further, in the X-ray tube apparatus of the present invention, the deflection magnetic field generating means has two or more electromagnets having different deflection magnetic field generation capabilities, and the end surfaces of the iron cores of the electromagnet are substantially parallel to and close to the X-ray main radiation direction. The magnetic field strength of the deflection magnetic field formed in the deflection magnetic field space in the X-ray tube by these electromagnets increases or decreases almost monotonously in the X-ray main radiation direction. The length dimension can be reduced. In the latter case, the effective focus length dimension can be increased. By using both as needed, it is possible to correct the effective focal length and the effective focal length.

  Further, in the X-ray tube apparatus of the present invention, the deflection magnetic field generating means has two electromagnets having substantially the same specifications, and the two electromagnets are close to each other so that the end surfaces of the iron core are substantially parallel to the X-ray main radiation direction. Since the excitation currents flowing through the windings of the two electromagnets are different from each other, the magnetic field strength of the deflection magnetic field formed in the deflection magnetic field space in the X-ray tube by the two electromagnets is X It increases or decreases almost monotonically in the line main radiation direction. As a result, it is possible to correct the movement of the effective focus and the length of the effective focus by controlling the exciting currents of the two electromagnet windings.

  Further, the X-ray apparatus of the present invention comprises the X-ray tube apparatus of the present invention, an X-ray detection means, an X-ray control means, and an X-ray image forming means, and the X-ray detection means is at the position of the actual focus. Focus movement detection means for detecting movement, and deflection magnetic field control means for controlling the deflection magnetic field generation means of the X-ray tube device by the X-ray control means, respectively, focus position movement information and effective focal spot size from the focus movement detection means Since the deflection magnetic field control means can adjust the magnetic field strength of the deflection magnetic field in the X-ray tube based on the information of the X-ray tube, when the X-ray tube focus position shifts or the effective focal spot size changes during use of the X-ray apparatus, Can be easily performed, and the high performance of the X-ray tube apparatus can be maintained (claim 3).

  In the X-ray apparatus of the present invention, the deflection magnetic field generating means is an electromagnet having an iron core and a winding, and the deflection magnetic field control means is an electromagnet power supply that supplies an excitation current to the electromagnet, and an electromagnet power supply control that controls the electromagnet power supply. The excitation current supplied from the electromagnet power supply to the electromagnet winding by the electromagnet power supply control section based on the focal position movement information and the effective focal spot size information from the focal movement detection means. Thus, it is possible to correct the magnetic field strength of the deflection magnetic field generated in the deflection magnetic field space in the X-ray tube, and to correct the movement of the focal position and the effective focal dimension.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The X-ray tube apparatus and the X-ray apparatus using the X-ray tube apparatus according to the present invention are improvements in the technology for deflecting an electron beam emitted from the cathode of an X-ray tube by a deflecting magnetic field generating means. Since the main characteristic point is that the deflection magnetic field generating means and its control means are different, those portions will be mainly described in the following description. FIG. 1 is a structural diagram of an X-ray tube of the first embodiment of the X-ray tube apparatus according to the present invention and its peripheral portion, and FIG. 2 is an electron beam of the X-ray tube in the X-ray tube apparatus of the present embodiment. FIGS. 3 and 4 are diagrams for explaining the deflection state, FIGS. 3 and 4 are an external view and a schematic configuration diagram of an embodiment of an X-ray apparatus to which the X-ray tube apparatus according to the present invention is applied, and FIG. 5 is an X-ray of this embodiment. It is a figure for demonstrating control of the deflection magnetic field generation means contained in a tube apparatus.

  In FIG. 1, FIG. 1 (a) shows an X-ray tube installed in the first embodiment of the X-ray tube apparatus according to the present invention and a deflecting magnetic field generating means arranged in the periphery thereof, FIG.1 (b) shows the A view of Fig.1 (a). Similar to the conventional X-ray tube device, the X-ray tube device according to the present embodiment includes, in addition to the X-ray tube, an X-ray tube container that contains the X-ray tube and shields X-rays, The X-ray tube support that is supported on the inner wall of the X-ray tube container and the high voltage applied to the X-ray tube filled in the X-ray tube container are insulated and the heat released from the X-ray tube is cooled. Insulating oil, a stator for rotationally driving the anode (rotary anode) of the X-ray tube, a cable receptacle for supplying high voltage, filament heating voltage, etc. to the X-ray tube, and X-ray for extracting X-rays to the outside It has a radiation window. Since these components have substantially the same structure and function as a conventional X-ray tube apparatus, a detailed description thereof will be omitted. The same applies to the following embodiments of the X-ray tube apparatus.

  In FIG. 1A, an X-ray tube 10 is a rotating anode X-ray tube, and is composed of a cathode 12, a rotating anode 14, and an envelope 16. The cathode 12 emits electrons 20, a focusing electrode 22 that includes the filament 20 and has a focusing groove for focusing the electrons into a thin beam-shaped electron beam 18, and a cathode support that fixes and supports the focusing electrode 22. The body 24 and the cathode support 24 are insulated and supported, and a stem 26 coupled to the envelope 16 is formed. The rotating anode 14 includes a disk-shaped target 28 made of tungsten or a tungsten alloy, a substantially cylindrical rotor 30 that supports the target 28, and a bearing that supports the rotor 30 in a freely rotatable manner (not shown, included in the rotor 30). And a fixed portion 32 that supports the bearing. The envelope 16 is usually made of an insulating material such as glass or ceramic, and supports the cathode 12 and the rotating anode 14 so as to face each other, and is enclosed in a vacuum-tight manner. In some cases, a metal material is used as the material of the envelope 16, but in the present invention, a magnetic field for deflecting the electron beam 18 from the cathode 12 is applied to the space between the cathode 12 and the target 28. Since it is formed from the outside of the envelope 16, it is necessary to use a nonmagnetic metal material for at least the central portion of the envelope 16. Further, the electron beam 18 from the cathode 12 collides with the inclined surface 28a of the disk of the target 28 to generate X-rays 34, which are taken out from the X-ray tube emission window of the X-ray tube device. Used for X-ray diagnosis. An X-ray source 36 is formed at a portion of the inclined surface 28a (FIG. 2A) of the target 28 where the electron beam 18 collides, and this X-ray source 36 is called a normal focus (actual focus). Here, the direction that is substantially the central axis of the range in which the X-ray 34 is radiated to the outside, and the direction orthogonal to the central axis of the X-ray tube is generally called the X-ray main radiation direction 35. It corresponds to. Further, the real focal point 36 viewed from the X-ray main radiation direction 35 is called an effective focal point.

  In FIG. 1A, an electromagnet 40 is disposed around the X-ray tube 10. The electromagnet 40 is a magnetic field for deflecting the electron beam 18 from the cathode 12 into a space 37 (hereinafter referred to as a deflection magnetic field space) 37 between the focusing electrode 22 of the cathode 12 of the X-ray tube 10 and the target 28 of the rotating anode 14. This is a deflection magnetic field generating means for forming the. FIG. 1B shows a view A as viewed from the cathode side of the X-ray tube 10 in FIG. 1A and 1B, an electromagnet 40 includes an iron core 42 and a winding 44. The iron core 42 is a substantially U-shaped rod-shaped body, and is made of a magnetic material such as iron or a silicon steel plate. The cross section of the rod-shaped body of the iron core 42 is usually formed in a circular shape or a quadrangular shape, but may have other shapes. Both end faces 42a and 42b of the rod-shaped body of the iron core 42 are substantially opposed to each other, and a deflection magnetic field is formed in a gap 46 between the both end faces 42a and 42b. A substantially central portion of the rod-shaped body of the iron core 42 is a winding portion 42c, and a winding 44 is wound around the winding portion 42c. The winding 44 is a copper wire coated with insulating enamel or the like and wound from several tens to several hundreds of turns. An exciting current of several A (amperes) flows through the winding 44 when a magnetic field is generated.

  Since the electromagnet 40 is normally held at or near the ground potential, the iron core 42 and the winding 44 are arranged a little away from the envelope 16 of the X-ray tube 10 for insulation, and the inner wall of the X-ray tube container. And so on through a support. The current to the winding 44 of the electromagnet 40 is introduced from the X-ray control unit of the external X-ray apparatus through the wall surface of the X-ray tube container in the same manner as the energizing current of the stator.

  In the present embodiment, both end faces 42a, 42b of the rod-shaped body of the iron core 42 are inclined surfaces, and the distance between the both end faces 42a, 42b changes in accordance with the location change in the direction parallel to the X-ray main radiation direction 35. I have to. In the example of FIG. 1 (b), both end faces 42a and 42b are inclined surfaces, and the distance between both end faces 42a and 42b is narrower near the center axis (hereinafter abbreviated as tube axis) 48 of the X-ray tube, Widen away from the tube axis 48. As another example, the inclined surfaces of the end faces 42a and 42b may be reversed, and the distance between the both end faces 42a and 42b may be wider near the tube axis 48 and narrower away from the tube axis. By forming the end faces 42a and 42b of the rod-shaped body of the iron core 42 in this way, the deflection magnetic field generated in the gap 46 between the both end faces 42a and 42b is in the radial direction of the coordinate system with the tube axis 48 as the central axis. In this case, the magnetic field strength decreases with the radial distance, and in the latter case, the magnetic field strength increases with the radial distance.

  Next, the electron beam deflection state of the X-ray tube in the X-ray tube apparatus of this embodiment will be described with reference to FIG. For the sake of simplicity, FIG. 2 shows an enlarged view of the facing portion between the focusing electrode of the cathode of the X-ray tube and the target of the rotating anode. 2A shows the deflection state of the electron beam of the X-ray tube, and FIG. 2B shows the magnetic field intensity distribution in the radial direction about the tube axis 48 of the deflection magnetic field space where the electron beam travels. An example is shown. For comparison, FIG. 2 (a) also shows the state of deflection of an electron beam when deflected by a deflecting magnetic field having a substantially uniform magnetic field strength of a conventional product. First, in FIG. 2B, the solid line A indicates the deflection magnetic field of this embodiment, and the broken line B indicates the deflection magnetic field of the conventional product. The horizontal axis represents the radial distance from the central axis (corresponding to the tube axis 48) of the rotating anode, and the vertical axis represents the magnetic field strength. Whereas the deflection magnetic field (B) of the conventional product has a substantially uniform magnetic field intensity distribution in the radial direction, the deflection magnetic field (A) of the present embodiment has a high magnetic field strength on the side close to the tube axis 48 and a radius of The magnetic field strength decreases as it increases and decreases on the side far from the tube axis 48.

  Next, FIG. 2 (a) is an enlarged view of the facing portion between the focusing electrode 22 of the cathode of the X-ray tube and the target 28 of the rotating anode. The cathode focusing electrode 22 and the inclined surface 28a of the disk of the target 28 face each other, and the electron beam 18 emitted from the electron generating source such as a filament included in the focusing electrode 22 travels toward the target 28, It collides with the real focal point 36 on the inclined surface 28a and emits X-rays from the real focal point 36. A deflection magnetic field is formed between the focusing electrode 22 and the inclined surface 28 a of the target 28. The direction of the magnetic flux of the deflection magnetic field is from the back side to the front side of the drawing, and by this magnetic flux, the electron beam 18 receives an electromagnetic force directed to the tube axis 48 indicated by the arrow 50 and deflects to the tube axis 48 side. The electron beam shown in FIG. 2 (a) is deflected in the radial direction with the tube axis 48 as the central axis using the deflection magnetic field of FIG. 2 (b), the solid line 52 is according to this embodiment, and the broken line 54 is conventional. It is a product. The electron beam 52 deflected by the deflection magnetic field of the present embodiment has a solid inner contour line (hereinafter referred to as an inner electron beam) 52a and an outer contour line (hereinafter referred to as an outer electron beam) 52b. The electron beam 54 deflected in (1) has a broken inner electron beam 54a and outer electron beam 54b. Comparing the magnetic field strength of the deflection magnetic field of the present example with that of the conventional product, the magnetic field strength of the present example is higher in the part inside the electron beam near the tube axis 48 than in the conventional product and is far from the tube axis 48. Since the magnetic field strength is lower in the portion outside the line than in the conventional product, in the electron beam 52 of this embodiment, the inner electron beam 52a is deflected to the tube axis 48 side larger than the inner electron beam 54a of the conventional product, and the outer side. The electron beam 52b is deflected smaller than the conventional outer electron beam 54b toward the tube shaft 48 side. As a result, the actual focal length 52c corresponding to the distance between the inner electron beam 52a and the outer electron beam 52b in this embodiment is the actual focal length corresponding to the distance between the inner electron beam 54a and the outer electron beam 54b of the conventional product. Since it becomes larger than the length dimension 54c, an actual focal area increases from the past, and the load resistance as an X-ray tube is improved. Also, the effective focal length as viewed from the X-ray main radiation direction is 52 d longer than the conventional 52 d in the present embodiment, and before deflection (the deflection magnetic field is not applied at all). The length is almost the same as the length of

  In the X-ray tube apparatus of the present embodiment, when the inclined surfaces of the end surfaces 42a and 42b of the iron core 42 of the electromagnet 40 are inclined opposite to those in FIG. 1B, as described above, between the both end surfaces 42a and 42b. Is wider near the tube axis 48 and narrower away from the tube axis 48. As a result, the magnetic field strength is lower near the tube axis 48 and higher away from the tube axis 48. Compared to the deflection magnetic field with uniform magnetic field strength, the inner electron beam is deflected smaller on the tube axis 48 side, and the outer electron beam is deflected more on the tube axis 48 side. The distance between the electron beam and the outer electron beam, that is, the actual focal length is smaller than that of the conventional product. Therefore, the above-described deflection magnetic field is an effective means that can be applied when the length of the actual focal point is reduced to improve the resolution of the X-ray image. Further, in this embodiment, since the end faces 42a and 42b of the iron core 42 of the electromagnet 40 are inclined surfaces, the shape thereof is simple. By changing the inclination angle of the inclined surface, the change in the gap 46 can be changed. It is possible to easily and variously change the ratio and the change ratio of the magnetic field strength. At the same time, since the shapes of the end faces 42a and 42b are simple, the processing becomes easy.

  In FIG. 2A, the electromagnetic force in the direction of the arrow 50 is generated and the electron beam 18 is deflected toward the tube shaft 48. However, the direction of the excitation current flowing through the winding 44 of the electromagnetic force 40 is reversed. Thus, the direction of the electromagnetic force can be reversed from the direction of the arrow 50, and the electron beam 18 can be deflected away from the tube axis 48. Compared with the conventional product in which the deflection of the electron beam in this case is deflected by a deflecting magnetic field having a uniform magnetic field intensity, the inner electron beam is largely deflected to the side farther from the tube axis 48, and the outer electron beam is farther from the tube axis 48. Therefore, the distance between the inner electron beam and the outer electron beam, that is, the length of the actual focal point can be made smaller than that of a conventional product deflected by a deflecting magnetic field having a uniform magnetic field strength. Further, when the inclined surfaces of the end faces 42a and 42b of the iron core 42 of the electromagnet 40 are opposite to those in FIG. 1 (b) and an excitation current in the reverse direction is passed through the winding 44, the inner electron beam The distance from the outer electron beam, that is, the length of the actual focal point can be made larger than that of a conventional product deflected by a deflecting magnetic field having a uniform magnetic field strength. In any of the above cases, the position of the actual focal point moves to the outside of the target 28 with respect to the state before changing the direction of the exciting current of the winding, and as a result, the effective focal point moves to the anode side in the direction of the tube axis 48. Moving.

  Further, in the X-ray tube apparatus of the present embodiment, as shown in FIG. 1, the electromagnet 40 as the deflection magnetic field generating means is configured by winding the winding 44 around the iron core 42. Is concentrated on the iron core 42 and diverges into the surrounding space at its end faces 42a and 42b and is focused. Therefore, this magnetic flux is focused on the focusing electrode 22 and the rotating anode 14 of the cathode 12 of the X-ray tube. Compared to the conventional electromagnet with only winding coils, the magnetic flux divergence is significantly reduced, and the magnetic field generation efficiency when generating the deflection magnetic field is also reduced. Greatly improved. As a result, the leakage of the magnetic flux to the outside of the X-ray tube device is significantly reduced as compared with the conventional product, and the heat radiation from the winding 44 of the electromagnet 40 is also greatly reduced.

  In the X-ray tube apparatus of the present embodiment, the X-ray tube to be installed is described as a rotary anode X-ray tube, but the X-ray tube is not limited to this and may be a fixed anode X-ray tube. Further, although the end surface of the iron core of the electromagnet as the deflection magnetic field generating means has been described as an inclined surface, the role of this end surface is parallel to the X-ray main radiation direction orthogonal to the tube axis 48 in the deflection magnetic field space 37 in the gap 46. In the direction, the magnetic field strength changes almost monotonically with distance. In other words, since an increasing or decreasing deflection magnetic field is formed, the overall shape may be a substantially inclined stepped shape, a square shape, a concave shape, or a convex shape. In the illustrated example, both end surfaces of the iron core are inclined surfaces, but only one end surface may be an inclined surface, and the other end surface may be a plane orthogonal to the axis of the rod-shaped body. Further, the cross section of the iron core rod-like body is not uniform, and the area may be increased in the vicinity of the end face.

  Next, an embodiment of an X-ray apparatus equipped with the X-ray tube apparatus of this embodiment will be described. 3 is an external view of an essential part of an X-ray CT apparatus equipped with the X-ray tube apparatus of the present embodiment, FIG. 4 is a block diagram showing a schematic configuration thereof, and FIG. 5 is an electromagnet of the X-ray tube apparatus of the present embodiment. It is a figure for demonstrating control. FIG. 3 shows an external view of a gantry and a patient table of an X-ray CT apparatus equipped with the X-ray tube apparatus of this embodiment. 3, the X-ray CT apparatus includes a gantry 60 that collects X-ray attenuation data of a patient 66, a patient table 65 on which the patient 66 is placed, and a control unit (see FIG. 4) that controls and drives these. An image reconstruction unit (see FIG. 4) that creates an X-ray image of the patient 66 from the above X-ray attenuation data is configured. The gantry 60 has a substantially disc shape, and includes a scanner 61 that rotates around the patient 66 and a substantially rectangular support base 62 that rotatably supports the scanner 61. The scanner 61 has an opening 67 for accommodating a patient 66 at the center, and an X-ray tube device 63 and a dosimeter 64 are supported to face each other across the opening 67. A patient 66 is placed on the patient table 65, and a portion to be examined of the patient 66 is inserted into the opening 67 of the scanner 61 at the time of examination.

  In FIG. 4, in addition to the gantry 60 and the patient table 65, the X-ray CT apparatus 70 drives the gantry 60 and controls the rotation of the scanner 61, and the X-ray tube voltage is applied to the X-ray tube device 63. X-ray control unit 72 that controls X-ray radiation, X-ray radiation data collection unit 73 that collects X-ray dose data measured by dosimeter 64, and patient table 65 that drives patient 66 A table driving unit 74 for positioning the test part 66a at the time of the examination, and an image reconstruction for reconstructing the X-ray image of the test part 66a of the patient 66 based on the X-ray dose data collected by the X-ray dose data collecting part 73 Based on the component 75, the console 76 for the operator to input instructions and operating parameters for operating the gantry 60 with a keyboard and the like, and the gantry driving unit 71 based on the instructions and parameters from the console 76 X-ray control unit 72, X-ray dose data collection unit 73, A computer (abbreviated as CPU) 77 for supplying control signals and information to the table driving unit 74, the image reconstruction unit 75, etc., and X-ray image data reconstructed by the image reconstruction unit 75 are stored. A data storage unit 78, a monitor device 79 for displaying an X-ray image reconstructed by the image reconstruction unit 75, and the like.

  3 and 4, an X-ray tube device 63 and a dosimeter 64 are disposed opposite to the scanner 61 of the gantry 60 with an opening 67 interposed therebetween. Here, a narrow fan-shaped X-ray 80 is radiated from the X-ray tube device 63, and the dosimeter 64 has a large number of detecting elements 81 arranged in a fan-shape so that the fan-shaped X-ray 80 can be detected. Yes. During the examination of the examination part 66 a of the patient 66, the examination part 66 a of the patient 66 placed on the patient table 65 is inserted into the opening 67 of the scanner 61, and the X-ray is collected around the central axis 82 of the scanner 61 together with the scanner 61. The tube device 63 and the dosimeter 64 rotate, the X-ray 80 is emitted from the X-ray tube device 63, and the X-ray transmitted through the subject 66a of the patient 66 is measured by the detection element 81 of the dosimeter 64. The X-ray dose data measured by 81 is collected by the X-ray dose data collection unit 73. The image reconstruction unit 75 reconstructs an X-ray image of the subject 66a of the patient 66 based on the X-ray data for one rotation of the scanner 61 collected by the X-ray data collection unit 73. The reconstructed X-ray image of the subject 66a of the patient 66 is displayed on the monitor device 79. The image data of the X-ray image is accumulated in the data storage unit 78. In the above description, the operation of one rotation of the scanner 61 has been described. However, the scanner 61 is continuously rotated, and at the same time, the patient table 65 is continuously moved to continuously move the subject 66a of the patient 66. Thus, it is also possible to reconstruct a plurality of X-ray images of the test portion 66a in a predetermined range of the patient 66.

  Next, the control of the deflection magnetic field generating means included in the X-ray tube apparatus of this embodiment will be described with reference to FIGS. In the case shown in FIG. 5, the movement of the focal position of the X-ray tube is detected by the focal position sensor, and the operation of the deflection magnetic field generating means is controlled based on the detection result to correct the movement of the focal position. It is. In FIG. 5, an electromagnet 40 which is a deflecting magnetic field generating means for applying a deflecting magnetic field to an X-ray tube is housed in an X-ray tube device 63 and is supplied with power from an electromagnet power supply 85 in an X-ray controller 72. . Further, the polarity of the voltage (or current) and the voltage value (or current value) of the electromagnet power source 85 are controlled by the electromagnet power source control unit 86 in the X-ray control unit 72. The electromagnet power source controller 86 receives data on the amount of movement of the focal position of the X-ray tube from the focal position sensor 87 included in the dosimeter 64. The focal position sensor 87 is usually arranged at the end most distant from the center of the dosimeter 64 in FIG. 4, and a method of measuring a change in the dose distribution of the X-ray 80 due to the movement of the focal position is used. .

  As an operation for correcting the movement of the focal position of the X-ray tube, in FIG. 4 and FIG. 5, first, the focal position sensor 87 of the dosimeter 64 measures the movement of the focal position of the X-ray tube. To do. The moving direction is the anode side or cathode side of the X-ray tube. For example, in the focus movement due to the temperature rise of the target of the rotary anode of the X-ray tube, movement data of about 0.5 mm is measured to the cathode side. Next, the measurement data of the focus position sensor 87 is input to the electromagnet power supply controller 86, and the electromagnet power supply 85 is controlled based on this measurement data. The electromagnet power supply control unit 86 controls the flow direction and magnetic field of the deflection magnetic field generated in the X-ray tube by controlling the flow direction (voltage polarity) and current value of the current (excitation current) flowing through the winding of the electromagnet. Control strength. For this reason, the direction in which the exciting current flows through the winding is determined by the moving direction of the focal position, and the current value of the exciting current in the winding is determined by the moving amount of the focal position. Next, when the electromagnet power supply 85 is operated under the control of the electromagnet power supply control unit 86, an exciting current flows through the winding of the electromagnet 40 in the X-ray tube device 63, and a deflection magnetic field is formed in the X-ray tube. The electron beam is subjected to a desired deflection, and the movement of the focal position is corrected. At this time, the actual focal spot size is automatically corrected by the proper magnetic field strength distribution of the deflection magnetic field created by the electromagnet.

  In the example of FIG. 5 described above, the input to the electromagnet power control unit 86 is only the focus position sensor 87, but the input to the electromagnet power control unit 86 is not limited to this, and other inputs may be input. Needless to say. For example, when the amount of deflection of the electron beam from the cathode of the X-ray tube varies greatly depending on the voltage value of the X-ray tube voltage, the voltage value of the X-ray tube voltage is input to control the excitation current of the electromagnet. Is possible.

  Next, a second embodiment of the X-ray tube apparatus according to the present invention will be described with reference to FIG. FIG. 6 shows a structural diagram of the X-ray tube and its peripheral portion of the second embodiment of the X-ray tube apparatus according to the present invention. The structure of the other part of the X-ray tube apparatus of the present embodiment is the same as that of the X-ray tube apparatus of the first embodiment, and is substantially the same as that of the conventional X-ray tube apparatus. 6 (a) shows an X-ray tube built in the X-ray tube apparatus and a deflection magnetic field generating means disposed in the periphery thereof, and FIG. 6 (b) shows FIG. 6 (a). FIG.

  In FIG. 6A, the X-ray tube 10 has the same structure as that of the first embodiment. The deflecting magnetic field generating means includes two electromagnets, that is, a first electromagnet 88 disposed in the vicinity of the envelope 16 of the X-ray tube 10 and a second electromagnet 89 disposed outside the first electromagnet 88. It consists of. The first electromagnet 88 includes an iron core 90 and a winding 91, and the second electromagnet 89 includes an iron core 92 and a winding 93. The iron cores 90 and 92 and the windings 91 and 93 have substantially the same structure as that of the first embodiment, but the end faces 90a, 90b, 92a and 92b of the iron cores 90 and 92 are not inclined surfaces but are parallel to each other. Surface. Further, the end surfaces 90a and 92a and the end surfaces 90b and 92b of the iron cores 90 and 92 of the two electromagnets 88 and 89 are arranged in close contact with each other. At this time, the end surfaces 90a and 90b of the iron core 90 are on the side close to the tube axis 48, the end surfaces 92a and 92b of the iron core 92 are on the side far from the tube axis 48, and all the end surfaces are substantially in the X-ray main radiation direction 35. The center of the deflection magnetic field formed by the magnetic fluxes from the end faces 90a, 90b, 92a, 92b of the iron cores 90, 92 substantially coincides with the traveling path of the electron beam from the cathode of the X-ray tube. Are arranged as follows. The winding portions 90c and 92c of the iron cores 90 and 92 are arranged slightly apart in consideration of insulation and heat dissipation. The number of windings 91 and 93 of the electromagnets 88 and 89 is usually equal.

  During the operation of the deflection magnetic field generating means, the magnet cores 90, 92 of the electromagnets 88, 89 are caused by flowing exciting currents having different current values through the windings 91 and 93 of the first electromagnet 88 and the second electromagnet 89. In the gap 46, a deflection magnetic field having different magnetic field strengths in the radial direction with the tube axis 48 as the central axis is formed. For example, when the current value of the winding 91 is made larger than the current value of the winding 93, the magnetic field strength on the side near the tube axis 48 of the deflection magnetic field is high and the magnetic field strength on the side far from the tube axis 48 is low. Conversely, when the current value of the winding 91 is made smaller than the current value of the winding 93, the magnetic field strength on the side close to the tube axis 48 of the deflection magnetic field is low and the magnetic field strength on the side far from the tube shaft 48 is high. Become. In this way, by changing the value of the current flowing through the windings 91 and 93 of the two electromagnets 88 and 89, the deflection for deflecting the electron beam from the cathode of the X-ray tube, as in the first embodiment. As for the magnetic field, it is possible to form a deflecting magnetic field having a magnetic field distribution such that the magnetic field strength changes in a substantially inclined or stepped manner in the radial direction with the tube axis 48 as the central axis. The movement of the focal position of the X-ray tube can be corrected.

  Also in the present embodiment, since the direction of the excitation current (voltage polarity) flowing through the windings 91 and 93 of the electromagnets 88 and 89 can be changed, the winding 91 is the same as in the first embodiment. , 93 can be changed so that the electron beam 18 of the X-ray tube 10 can be deflected to the side closer to the tube axis 48 or to the side away from the tube axis 48. In the example shown in the figure, the deflecting magnetic field generating means uses two electromagnets, and the number of electromagnets is not limited to this, and may be three or more.

  Further, in the X-ray apparatus using the X-ray tube apparatus of this embodiment, in FIG. 5, two electromagnet power supplies are provided in the X-ray controller 72, and the first electromagnet 88 and the second electromagnet 88 of the X-ray tube apparatus are provided. The electromagnet power supply control unit 86 controls the excitation current that flows through the winding 91 of the first electromagnet 88 and the excitation current that flows through the winding 93 of the second electromagnet 89.

1 is a structural diagram of an X-ray tube and its peripheral portion of a first embodiment of an X-ray tube device according to the present invention. The figure for demonstrating the deflection | deviation state of the electron beam of the X-ray tube in the X-ray tube apparatus of a present Example. 1 is an external view of an embodiment of an X-ray apparatus according to the present invention. 1 is a schematic configuration diagram of an embodiment of an X-ray apparatus according to the present invention. The figure for demonstrating control of the deflection | deviation magnetic field generation means contained in the X-ray tube apparatus of a present Example. FIG. 6 is a structural diagram of the periphery of an X-ray tube of a second embodiment of the X-ray tube apparatus according to the present invention. The figure for demonstrating the change of the length dimension of a real focus at the time of deflecting the electron beam of an X-ray tube with a substantially uniform deflection magnetic field.

Explanation of symbols

10 ... X-ray tube
12 ... Cathode
14 ... Rotating anode
16 ... Envelope
18, 52, 54 ... electron beam
22 ... Focusing electrode
28 ... Target
28a ... inclined surface
34, 80 ... X-ray
35 ... X-ray main radiation direction
36 ... X-ray source (actual focus)
37 ... Deflection magnetic field space
40, 88, 89 ... Electromagnet (deflection magnetic field generating means)
42, 90, 92 ... iron core
42a, 42b, 90a, 90b, 92a, 92b ... end face
42c, 90c, 92c ... Winding part
44, 91, 93 ... winding
46 ・ ・ ・ Gap
48 ... X-ray tube center axis (tube axis)
50 ... Arrow
52a, 54a ... inner contour line (inner electron beam)
52b, 54b ... Outer contour (outer electron beam)
52c, 54c ... Length of actual focus
52d, 54d ... effective focal length
60 ... Gantry
61 ... Scanner
63 ... X-ray tube device
64 ... Dosimeter
67 ... Opening
70 ・ ・ ・ X-ray CT system
72 ... X-ray controller
73 ・ ・ ・ X dose data collection unit
76 ... Console
77 ・ ・ ・ Computer (CPU)
81 ... Detection element
85 ・ ・ ・ Electromagnetic power supply
86 ・ ・ ・ Electromagnet power controller
87 ・ ・ ・ Focus position sensor
88 ・ ・ ・ First electromagnet
89 ・ ・ ・ Second electromagnet

Claims (3)

A cathode having an electron source that emits electrons, a focusing electrode that focuses the electrons emitted from the electron source into a narrow beam of electron beams, and an electron beam disposed on the opposite surface of the cathode. An X-ray tube comprising: an anode having a target on which an X-ray source (hereinafter referred to as an actual focal point) that emits X-rays upon collision; and an envelope that vacuum-tightly seals the cathode and the anode; A deflecting magnetic field generating means disposed in the periphery of the envelope of the X-ray tube to form a deflecting magnetic field for deflecting an electron beam from the cathode in a space between the cathode and the anode of the X-ray tube; In an X-ray tube apparatus comprising an X-ray tube and an X-ray tube container containing a deflection magnetic field generating means,
The deflection magnetic field generating means is means for maintaining the size of the real focus viewed from the X-ray main radiation direction (hereinafter referred to as effective focus size) at a substantially constant value regardless of the magnetic field strength and direction of the deflection magnetic field. An X-ray tube device comprising:   2. The X-ray tube apparatus according to claim 1, wherein the magnetic field intensity of the deflection magnetic field formed by the deflection magnetic field generating means in the space where the electron beam between the cathode and the anode of the X-ray tube travels is the central axis of the X-ray tube. An X-ray tube device characterized in that it increases or decreases almost monotonically with distance in a direction perpendicular to and parallel to the X-ray main radiation direction.   An X-ray apparatus comprising an X-ray tube apparatus, an X-ray detection means, an X-ray control means, and an X-ray image forming means, wherein the X-ray tube apparatus is the X-ray tube apparatus according to claims 1 and 2. The X-ray detecting means detects the movement of the actual focal position of the X-ray tube apparatus; and the X-ray control means controls the deflection magnetic field generating means of the X-ray tube apparatus. Magnetic field control means, respectively, and based on the focal position movement information and the effective focal spot size information from the focal position movement detection means, the deflection magnetic field control means determines the magnetic field strength of the deflection magnetic field formed by the deflection magnetic field generation means. An X-ray apparatus characterized by adjusting.

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