X-ray source device

Abstract

To provide a lightweight medical X-ray source device.SOLUTION: A medical X-ray source device is installed in an X-ray tube housing, and includes an attenuation tube 6 arranged around the outer periphery of an X-ray tube 2 to attenuate the X-ray flux, an irradiation port flange 7 arranged between the attenuation tube 6 and an X-ray transparent window, which is cylindrical in shape congruent or similar to the opening of the attenuation tube 6, restricts an irradiation area of a primary X-ray flux passing through a cylindrical portion 7a, and can extract the primary X-ray flux with the restricted irradiation area from the cylindrical portion 7a. The device has a shielding cone that restricts the irradiation area of the primary X-ray flux emitted from the X-ray transparent window outside the X-ray tube housing and extracts the X-ray flux in a predetermined irradiation field. The X-ray tube housing, the irradiation port flange 7, and the X-ray transparent window are sealed between each other, an insulating medium is sealed inside the X-ray tube housing, the primary X-ray flux passes through the insulating medium filled between the surface of the X-ray tube 2 and the X-ray transparent window, and soft X-rays are absorbed. This configuration shields primary X-rays outside the irradiation field and reduces shielding lead around the device.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to the structure of an X-ray source device, and more particularly to a technique for reducing the amount of lead used to prevent leakage of X-ray flux from an X-ray source device and for making the X-ray source device lighter and smaller in size. [Background technology]

[0002] In general, X-ray tubes and X-ray tube devices incorporating the X-ray tubes and X-ray source devices including irradiation field limiters are used in medical X-ray diagnostic devices and industrial X-ray inspection devices. In these X-ray tubes, a cathode that generates an electron beam and an anode equipped with a target that generates an X-ray flux when the electron beam generated from the cathode collides with them are arranged facing each other in a vacuum envelope. The cathode is composed of a filament that generates thermal electrons, a focusing electrode that focuses the thermal electrons into an electron beam toward the anode, a focusing electrode support that supports the focusing electrode, and a stem that insulates and supports these and has lead wires for supplying a high-voltage cathode potential and a filament heating voltage. The anode is also composed of a target that generates an X-ray flux when the electron beam from the cathode collides with it, and a target support that supports the target and dissipates the heat generated there. The vacuum envelope is usually made of an insulator and insulates and supports the cathode and anode. The X-ray flux is emitted to the outside through an X-ray emission window in the envelope. The X-ray flux emitted from the focal point is irradiated over a hemispherical range such that the intensity is greatest in the normal direction of the target and is zero in the direction along the target.

[0003] The X-ray source device with the built-in X-ray tube described above is composed of the X-ray tube, an X-ray tube case that houses it, insulating oil that fills the X-ray tube case and insulates the X-ray tube and other components, a cable receptacle for supplying high voltage to the X-ray tube, and bellows that cushion the expansion and contraction of the insulating oil. The X-ray tube case is equipped with an X-ray emission port for extracting the X-ray beam to the outside and a cable receptacle attachment part for attaching a cable receptacle, and lead plates are attached to the inner wall surface or outside of the X-ray tube case to prevent X-ray leakage from parts other than the X-ray emission port. The cable receptacle is a high-voltage connection part that introduces high voltage supplied from an external high-voltage generator into the X-ray tube case. In some cases, a high-voltage generator is stored inside the X-ray source device instead of a cable receptacle.

[0004] Generally, in diagnostic radiology, X-ray source devices are used to attenuate the X-ray flux, mainly in the low energy region of the X-ray spectrum, for X-ray imaging applications, thereby reducing the dose and noise, and thus improving the quality of the X-ray image. The material and thickness of the filter are determined by the X-ray attenuation characteristics of the object being examined. In diagnostic radiology, the conventional minimum filtering is often achieved by standard filtering with 3 mm aluminum as a benchmark for comparing the X-ray output from different X-ray tubes.

[0005] The secondary X-ray flux is generated, for example, when the primary X-ray flux incident on the subject causes the photoelectric effect or Compton scattering in the subject.

[0006] Generally, the secondary X-ray beam is smaller in quantity, softer, and has a larger angle of incidence than the primary X-ray beam, so copper and iron-based metals can effectively attenuate X-rays.

[0007] As a publicly known example, an X-ray source device in which an X-ray beam irradiation area is limited by providing a cylindrical cone lined with lead and an X-ray shielding tube and attenuation tube are provided inside a metal X-ray tube container is disclosed in Patent Document 1. However, there is no description of a structure for shielding the primary X-ray beam with a shielding tube and attenuation tube surrounding the tube and an X-ray aperture component.

[0008] As a publicly known example, an X-ray source device having a structure for shielding the primary X-ray flux with metal around the X-ray tube is disclosed in Patent Document 2. However, there is no description of a structure for shielding the primary X-ray flux with a shielding tube / attenuation tube surrounding the tube and an X-ray aperture part.

[0009] As a publicly known example, an X-ray source device having a structure for attenuating X-ray flux in the low energy region of the X-ray spectrum by a filter is disclosed in Patent Document 3. However, there is no description or suggestion of a structure for attenuating soft X-rays by configuring a filter with an insulating medium, or a structure for shielding the primary X-ray flux by using a shielding tube / attenuation tube surrounding the tube and an X-ray aperture component.

[0010] As a publicly known example, an X-ray diagnostic device equipped with X-ray protective gear is disclosed in Patent Document 4. However, there is no description or suggestion of a structure for shielding the primary X-ray beam with a shielding tube / attenuation tube surrounding the tube and an X-ray aperture part.

[0011] As a publicly known example, an X-ray source device having an X-ray shielding tube / attenuation tube made of a material other than lead is disclosed in Patent Document 5. However, there is no description or suggestion of a structure in which a filter is made of an insulating medium to attenuate soft X-rays, or a structure in which a shielding tube / attenuation tube surrounding the tube and an X-ray aperture part are used to shield the primary X-ray beam.

[0012] As a publicly known example, an X-ray source device in which a primary X-ray flux passes through an insulating medium is disclosed in Patent Document 6. However, there is no description or suggestion about a structure in which a filter is made of an insulating medium to attenuate soft X-rays, or about X-ray aperture components.

[0013] As a known example, an X-ray source device having an X-ray aperture part is disclosed in Patent Document 7. However, the primary X-ray flux does not penetrate an insulating medium, and there is no description or suggestion about the attenuation of soft X-rays necessary for a medical X-ray source device. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Reality Fair 03-019199 [Patent Document 2] Patent 4919956 [Patent Document 3] Special table 2009-545840 [Patent Document 4] Patent Publication No. 2021-115113 [Patent Document 5] Patent Publication No. 56-042998 [Patent Document 6] Korean Patent Publication No. 10-2022-0157243 [Patent Document 7] Japanese Patent Application Publication No. 57-25660 Summary of the Invention [Problem to be solved by the invention]

[0015] In the conventional method, it is necessary to provide an aluminum plate filter to attenuate the soft X-rays emitted from the X-ray tube, but since aluminum has a low density and a low X-ray attenuation coefficient, the primary X-ray flux cannot be attenuated in the filter area, so lead is wrapped around the X-ray tube housing to attenuate and shield it. Therefore, the surface area of ​​lead is large, and the thickness of the lead required for attenuation and shielding is large, which makes the X-ray source device heavy, and as a result, there is an issue that the strength required for the support structure to support the X-ray source device and ensure vibration stability is high. [Means for solving the problem]

[0016] The medical X-ray source device of the first invention is The X-ray tube housing and the X-ray aperture part are sealed, and the X-ray aperture part and the X-ray transparent window are sealed to hermetically seal the insulating medium in the X-ray tube housing; and a primary X-ray flux passes through an insulating medium filled between a surface of an X-ray tube disposed in an X-ray tube container and an X-ray transmission window, and soft X-rays are absorbed by the insulating medium, a tube surrounding attenuator disposed within an X-ray tube container filled with an insulating medium and disposed around the outer periphery of the X-ray tube to attenuate the primary X-ray flux and the higher-order X-ray flux emitted from the X-ray tube, the tube surrounding attenuator being made of a metal having a second density greater than the first density of the metal material of the X-ray tube container; An irradiation field limiter that limits the irradiation area of ​​the primary X-ray beam emitted from the X-ray transmission window and extracts the X-ray beam in a predetermined irradiation field. having The X-ray aperture component is disposed in an X-ray tube container filled with an insulating medium, and is provided between the tube-surrounding attenuation body and the X-ray transmissive window. The X-ray aperture component has a cylindrical shape that is congruent or similar to the opening of the tube-surrounding attenuation shielding body, limits the irradiation area of ​​the primary X-ray flux passing through the opening of the tube-surrounding attenuation body, and can extract the primary X-ray flux with the limited irradiation area from the opening of the X-ray aperture component. The X-ray aperture component is made of a metal having a third density greater than the first density.

[0017] The medical X-ray source device of the second invention is as follows: The X-ray tube housing and the X-ray aperture part are sealed, and the X-ray aperture part and the X-ray transparent window are sealed to hermetically seal the insulating medium in the X-ray tube housing; and a primary X-ray flux passes through an insulating medium filled between a surface of an X-ray tube disposed in an X-ray tube container and an X-ray transmission window, and soft X-rays are absorbed by the insulating medium, a tube surrounding attenuator disposed within an X-ray tube container filled with an insulating medium and disposed around the outer periphery of the X-ray tube to attenuate the primary X-ray flux and the higher-order X-ray flux emitted from the X-ray tube, the tube surrounding attenuator being made of a metal having a second density greater than the first density of the metal material of the X-ray tube container; An irradiation field limiter that limits the irradiation area of ​​the primary X-ray beam emitted from the X-ray transmission window and extracts the X-ray beam in a predetermined irradiation field. having The X-ray aperture component is disposed in an X-ray tube container filled with an insulating medium, and is provided between the tube-surrounding attenuation body and the X-ray transmissive window. The X-ray aperture component has a cylindrical shape that is congruent or similar to the opening of the tube-surrounding attenuation shielding, limits the irradiation area of ​​the primary X-ray flux passing through the tube-surrounding attenuation shielding, and can extract the primary X-ray flux with the limited irradiation area from the opening of the X-ray aperture component. The X-ray aperture component is made of a metal having a third density greater than the first density.

[0018] The third invention relates to a medical X-ray source device according to the first or second invention, The second density and the third density are characterized as being approximately equal.

[0019] The fourth aspect of the present invention is the medical X-ray source device according to the first or second aspect of the present invention, The device is characterized by having an insulating object disposed between the outer periphery of the X-ray tube and the tube-surrounding attenuator, the insulating object having an opening similar in shape to and smaller than the opening of the tube-surrounding attenuator.

[0020] The fifth aspect of the present invention is the medical X-ray source device of the fourth aspect of the present invention, The insulating body has a cylindrical shape, and is characterized in that a bulb surrounding attenuator is provided on the outer circumferential surface of the insulating body.

[0021] The sixth aspect of the present invention is the medical X-ray source device according to the first or second aspect of the present invention, The X-ray aperture component is characterized by having a cylindrical portion having a cylindrical shape and a disk-shaped flange portion provided at one end of the cylindrical portion on the X-ray transmission window side.

[0022] The seventh aspect of the present invention is the medical X-ray source device of the sixth aspect of the present invention, The flange has an O-ring groove for sealing the insulating medium. It is characterized by:

[0023] The eighth aspect of the present invention is the medical X-ray source device of the sixth aspect of the present invention, The cylindrical part of the X-ray aperture part has a flat end on the X-ray tube side. It is characterized by:

[0024] The ninth aspect of the present invention is a medical X-ray source device according to the first or second aspect of the present invention, characterized in that the X-ray tube has a hood which covers the anode target and has an opening for passing electrons emitted from the cathode and an opening for limiting the primary X-ray flux irradiated from the target. Effect of the Invention

[0025] In the first and second inventions, by providing an X-ray aperture component between the tube surrounding attenuator and the X-ray transmitting window, it is possible to attenuate soft X-rays and limit the strong primary X-ray flux as X-rays around the X-ray tube, thereby making it possible to provide a lightweight medical X-ray source device by reducing the area and thickness of the lead wrapped around the entire X-ray source device. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram showing an X-ray source device arranged within an xyz coordinate system with the X-ray tube focal point O of an X-ray tube 2 as the origin. [Diagram 2] FIG. 2 is a cross-sectional view of the X-ray source device of FIG. 1 taken along the xy plane. [Diagram 3] FIG. 3 is an enlarged view of the periphery of the X-ray tube 2 in FIG. [Figure 4] FIG. 4 is a diagram showing the arrangement of the X-ray tube 2, insulating tube 5, tube attenuation tube 6, and X-ray aperture part 7 within an xyz coordinate system with the X-ray tube focal point O of the X-ray tube 2 as the origin. [Diagram 5] FIG. 5 is a diagram of the yz plane of FIG. 4 as viewed from the positive direction of the x axis. [Figure 6] FIG. 6 is a diagram showing the shapes and irradiation areas of the X-ray tube 2, the X-ray aperture part 7, and the shielding cone 4 (irradiation field limiter) in relation to the xy plane cross section of FIG. [Figure 7] FIG. 7 is a diagram showing the shapes and irradiation areas of the X-ray tube 2, the X-ray aperture part 7, and the shielding cone 4 in relation to the zx plane cross section of FIG. [Figure 8] FIG. 8 is a diagram showing the shape and irradiation area of ​​the X-ray tube 2 and the X-ray aperture part 7 in FIG. [Figure 9]FIG. 9 is a diagram showing the shape and irradiation area of ​​the X-ray tube 2 and the X-ray aperture part 7 in FIG. [Figure 10] FIG. 10 is a diagram showing the irradiation area in FIG. 6, focusing on the positional relationship between the X-ray tube 2, the X-ray aperture part 7, and the shielding cone 4. [Figure 11] FIG. 11 is a diagram showing the irradiation area by changing the diameter of the irradiation port flange 7 in FIG. 10 and focusing on the positional relationship between the opening 6a of the tube attenuation tube 6, the irradiation port flange 7, and the shielding cone 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] (One embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The disclosure is an example, and appropriate modifications that can be easily conceived by a person skilled in the art while maintaining the gist of the invention are included in the scope of the present invention. In addition, the drawings may show dimensions, shapes, etc., in a schematic manner compared to the actual ones in order to make the explanation clearer. When elements in this specification and each drawing are similar to elements in a previous drawing, the same reference numerals may be used, and detailed explanations may be omitted as appropriate.

[0028] First, an X-ray source device according to an embodiment will be described. Fig. 1 shows the appearance of an embodiment of an X-ray source device according to the present invention, Fig. 2 is a cross-sectional view of the xy plane in Fig. 1, and Fig. 3 is an enlarged view of the periphery of an X-ray tube 2 with a fixed anode hood in Fig. 2.

[0029] An example of an irradiation field limiter in the claims is a shielding cone 4, an example of an insulating object is an insulating tube 5, an example of a tube surrounding attenuator is a tube attenuator tube 6, and an example of an X-ray aperture part is an irradiation port flange 7.

[0030] In this embodiment, the X-ray source device in Fig. 2 has an X-ray tube 2 and a high-voltage circuit board 3 inside an X-ray tube container 1, and the inside is filled with an insulating medium 14 as shown in Fig. 3. To seal, an irradiation port flange 7 having a flange portion 7a with an O-ring groove and a cylindrical portion 7b is used. In Fig. 3, an O-ring 8 is inserted between the X-ray tube container 1 and the irradiation port flange 7, and a packing 9 is inserted between the irradiation port flange 7 and the X-ray transmission window 10, so that the inside of the X-ray tube container 1 is sealed at the X-ray tube container irradiation port 1a, and the insulating medium 14 can be a liquid or gas. On the outer periphery of the X-ray tube 2, there is a cylindrical insulating tube 5 to which a tube attenuation tube 6 is fixed with adhesive or the like, and this insulating tube 5 is fixed to a tube fixing plate 13 with a metal band or the like, and after aligning the cylindrical portion 7b of the irradiation port flange 7 described later with the opening 5a of the insulating tube 5, the tube fixing plate 13 is fastened to the X-ray tube case 1 with a screw, and the X-ray tube 2 is fixed to the X-ray tube case 1. The insulating tube 5 is a resin cylinder used to avoid discharge to surrounding metal parts when a high voltage is applied to the X-ray tube 2, and high-voltage resistant wires connected to the anode 2a and cathode 2b of the X-ray tube 2 in FIG. 7 are passed through both end faces of the insulating tube 5. The tube attenuation tube 6 is made of a high-density metal such as brass, which has a higher density than the aluminum alloy that is the material of the X-ray tube case 1, and is placed around the X-ray tube 2 and the insulating tube 5 to attenuate the X-ray flux around the X-ray tube. The thickness and material of the irradiation port flange 7 and the tube attenuation tube 6 are determined depending on the output required for the X-ray generator. The shielding cone 4, which is a conical pipe-shaped resin part wrapped with lead, is fastened to the outside of the X-ray tube container 1 with screws via a metal fixing bracket.

[0031] In the X-ray source device in Fig. 3, the insulating tube 5 and the tube attenuation tube 6 have openings 5a and 6a, respectively, and the opening 2a-2 that opens in the hood 2a-1 of the anode 2a of the X-ray tube, the opening 5a of the insulating tube 5, and the opening 6a of the tube attenuation tube 6 are concentric circles and have the same or similar shapes. The opening 2a-2 of the hood 2a-1, the irradiation port flange 7, the ring-shaped packing 9, the disk-shaped X-ray transmission window 10, the ring-shaped washer 11, the ring-shaped irradiation port fixing screw 12, and the conical pipe-shaped shielding cone 4 all have the same central axis. This central axis is the x-axis including the X-ray tube focal point O shown in Fig. 1.

[0032] In the X-ray source device of FIG. 3, the irradiation port flange 7 has a disk-shaped flange portion 7a and a cylindrical portion 7b with a groove for fitting an O-ring 8, and is a rotating body with the x-axis as a center line. The irradiation port flange 7 is made of high-density metal such as brass. X-ray flux is easily attenuated when passing through a high-density material, and lead is easily attenuated, and the lower the density is, such as brass and aluminum alloy, the less attenuated it is, so it is necessary to increase the distance through which the X-rays pass. In this embodiment of the X-ray tube container 1, the tip of the cylindrical portion 7b is processed on one plane. The irradiation port flange 7 is inserted into the irradiation port 1a opening in the X-ray tube container 1 with an O-ring 8 made of NBR rubber fitted in the groove. At this time, the irradiation port flange 7 is arranged coaxially with the opening 2a-2 opening in the hood 2a-1, the opening 5a of the insulating tube 5, and the opening 6a of the tube attenuation tube 6, and the opening 6a of the tube attenuation tube 6 and the cylindrical portion 7b of the irradiation port flange 7 are concentric circles and are the same or similar in shape. The tip of the cylindrical portion 7b of the irradiation port flange 7 is in line contact with the tube attenuation tube 6 with two line segments parallel to the z-axis or approaches as close as possible. Next to the irradiation port flange 7, a rubber packing 9 made of silicon or the like and an X-ray transparent window 10 made of resin such as acrylic are arranged and fastened with a metal washer 11 and an irradiation port fixing screw 12 to fix it to the X-ray tube case 1. In order to seal the insulating medium 14 inside the X-ray tube case 1, an O-ring 8 seals between the X-ray tube case 1 and the irradiation port flange 7, and a packing 9 seals between the irradiation port flange 7 and the X-ray transparent window 10. The inside of the X-ray tube case 1 is filled with an insulating medium 14 such as insulating oil, and insulates against high voltage. The space between the surface of the X-ray tube 2 and the distance L of the X-ray transparent window 10 is also filled with the insulating medium 14, and soft X-rays, which are easily attenuated in the X-ray flux, are absorbed by passing through the insulating medium 14. In medical X-ray generators, it is necessary to absorb soft X-rays, adjust the radiation quality, and display the total filtration expressed as radiation quality equivalent filtration. The radiation quality can be adjusted by changing the distance L through which the X-ray flux passes based on the inherent filtration value of the insulating medium 14, and the distance L is determined by the length L7 of the irradiation port flange 7.

[0033] In the X-ray source device of FIG. 3, the X-ray tube container 1 and the irradiation port flange 7 are sealed, the irradiation port flange 7 and the X-ray transparent window 10 are sealed, and an insulating medium 14 is hermetically sealed in the X-ray tube container 1. The primary X-ray flux passes through the insulating medium 14 filled between the surface of the X-ray tube 2 arranged in the X-ray tube container 1 and the X-ray transparent window 10 over a distance L, whereby soft X-rays are absorbed.

[0034] FIG. 4 is a diagram of the X-ray tube 2, the insulating tube 5, the tube attenuation tube 6, and the irradiation port flange 7 from the embodiment of FIG. 1 on the xyz coordinate system of FIG. 1. FIG. 5 is a diagram of the yz plane of FIG. 4 viewed from the positive direction of the x axis, and the inner diameter d5 of the opening 5a of the insulating tube 5 is formed to be equal in size to the inner diameter d7 of the irradiation port flange 7. As a result, by passing a cylindrical jig through the opening 5a of the insulating tube 5 to which the X-ray tube 2 is attached and the inner diameter side of the irradiation port flange 7, the opening 5a of the insulating tube 5 and the irradiation port flange 7 can be aligned so that their central axes are the same. In order to avoid discharge between the X-ray tube 2 and the tube attenuation tube 6, the inner diameter d6 of the opening 6a of the tube attenuation tube 6 is made larger than the inner diameter d5 of the opening 5a of the insulating tube 5. In addition, the inner diameter d6 of the opening 6a of the tube attenuation tube 6 is formed smaller than the cylindrical outer diameter D7-1 of the irradiation port flange 7 in order to limit the irradiation area described later.

[0035] FIG. 6 is an xy-plane cross-sectional view of the X-ray tube 2, the shielding cone 4, the insulating tube 5, the tube attenuation tube 6, and the irradiation port flange 7 among the components of the X-ray source device of the embodiment of FIG. 1, and FIG. 7 is a zx-plane cross-sectional view of the same configuration as FIG. 6. Also, FIG. 6 and FIG. 7 show how an X-ray flux is irradiated in the x-axis direction from the X-ray tube focus O of the X-ray tube 2 when a voltage is applied from the high-voltage circuit board 3 of FIG. 2. The primary X-ray flux irradiated from the X-ray tube 2 is irradiated in a hemispherical shape along the surface of the target 2a-3 of the anode 2a, and is divided into an irradiation area A1 limited by the opening 2a-2 of the hood 2a-1 and an irradiation area A2 irradiated toward the cathode 2b. The irradiation area A2 hits the focusing body 2b-1 and the shielding plate 2b-2 of the cathode 2b, and the primary X-ray flux is attenuated. Irradiation area A1 is divided into irradiation area A3 of the primary X-ray flux that has passed through opening 6a of tube attenuation tube 6 and irradiation area A1' of the primary X-ray flux that has been attenuated by transmitting through tube attenuation tube 6. The primary X-ray fluxes of irradiation area A3 and irradiation area A1' are further attenuated and shielded by irradiation port flange 7 and limited to irradiation area A4. Finally, irradiation area A4 is limited by shielding cone 4 to obtain a predetermined irradiation field A5 required for imaging, which is irradiated onto subject 15 and an X-ray image is acquired on X-ray receiving surface 16.

[0036] Figures 8 and 9 show cross-sectional views in the zx and xy planes, respectively, of the mechanism by which the irradiation areas A1, A3, and A4 are limited by the X-ray tube 2, insulating tube 5, tube attenuation tube 6, and irradiation port flange 7. Figure 10 shows the shielding range of the irradiation port flange 7 and the shielding cone 4.

[0037] Points P1 to P12 in Fig. 8 are points on the cross section of the irradiation port flange 7, and the irradiation port flange 7 is a rotational body about the x-axis of the region (P1-P2-P3-P4-P5-P6-P7-P8-P9-P10-P11-P12). The region (P1-P2-P3-P4-P12) is the cylindrical portion 7b of the irradiation port flange 7, and the region (P4-P5-P6-P7-P8-P9-P10-P11-P12) is the flange portion 7a. Also, the region (P8-P9-P10-P11) is a groove into which the O-ring 8 is fitted.

[0038] In FIG. 8, the line segment (P1-P2) is on the surface of the tip of the cylindrical portion 7b of the irradiation port flange 7 and is a line parallel to the yz plane. The line segment (P2-P3) is a line parallel to the x-axis and is a line that forms the inner diameter d7 of the cylindrical portion 7b of the irradiation port flange 7 centered on the x-axis. The line segment (P4-P5) is on the surface of the tip of the flange portion 7a of the irradiation port flange 7 and is a line parallel to the yz plane. The line segment (P6-P7) is a line parallel to the x-axis and is a line that forms the outer diameter D7-2 of the flange portion 7a of the irradiation port flange 7 centered on the x-axis. The line segments (P3-P4) and (P5-P6) are chamfered shapes for the line segments (P2-P3), (P4-P5), (P4-P5), and (P6-P7), respectively. Line segment (P7-P8) and line segment (P11-P12) are collinear and parallel to the yz plane. Line segment (P12-P1) is a line parallel to the x-axis, and is a line that forms the outer diameter D7-1 of the cylindrical portion 7b of the irradiation port flange 7 centered on the x-axis. Line segments (P8-P9) and line segment (P10-P11) are parallel to the x-axis and form the groove width for the O-ring 8. Line segment (P9-P10) is parallel to line segment (P7-P12) and forms the groove bottom for the O-ring 8.

[0039] 8 and 9, irradiation area A1 is irradiated from the X-ray tube focal point O and limited by target 2a-3 of anode 2a and opening 2a-2 of hood 2a-1, and is attenuated when it hits point Ri1 on the inner wall of tube attenuation tube 6 on the extension of point Q on opening 2a-2 of hood 2a-1 and X-ray tube focal point O. When the outer diameter side of the point on opening 6a of tube attenuation tube 6 is point R2 and the inner diameter side is point R3, irradiation area A3 is obtained in the range on the line connecting point R2 and X-ray tube focal point O. A part of irradiation area A1 limited by target 2a-3 does not hit tube attenuation tube 6 and is irradiated further out without being limited by opening 6a.

[0040] The point on the boundary of the irradiation area A3 on the line segment (P1-P2) at the tip of the irradiation port flange 7 in Figures 8 and 9 is set as point Pi1, and the point on the line segment (P2-P3) on the inner wall of the cylindrical part 7b of the irradiation port flange 7 on the extension line of the target 2a-3 in Figure 8 is set as point Pi0. The primary X-ray flux coming out of the opening 6a of the tube attenuation tube 6 is irradiated to the irradiation port flange 7 within the range of the line segments (Pi1-P2) and (P2-P3). On the extension line of the line segment (O-Pi1), the point on the line segment (P12-P1) is set as point Po1, the point on the line segment (P9-P10) is set as point Pi2, and the point on the line segment (P4-P5) is set as point Po2, and the point on the line segment (P3-P4) on the extension line of the line segment (O-Pi0) is set as point Po0. The primary X-ray flux in the irradiation area A3 is attenuated within the range of the area (Pi1-P2-P3-P4-Po2-Pi2-P10-P11-P12-Po1).

[0041] 8 and 9, when the X-ray intensity is strong, the primary X-ray flux may pass through the tube attenuation tube 6, and the primary X-ray flux in the irradiation area A1 attenuated in the region (Ri1-Ro1-R2-R3) of the tube attenuation tube 6 may irradiate the flange portion 7a. This irradiation area is called irradiation area A1'. In Fig. 9, the primary X-ray flux that has passed through and been attenuated is incident on the line segment (Pi-P8), line segment (P8-P9), or line segment (P9-Pi2) on the flange portion 7a, and is attenuated, so that the primary X-ray flux in the irradiation area A1' is shielded.

[0042] In the region (Po1-P12-P11-P10-Pi2) in FIG. 8 and FIG. 9, the thin wall of the cylindrical portion 7b of the irradiation port flange 7 cannot shield the primary X-ray flux, and the attenuated primary X-ray flux may penetrate and irradiate the flange portion 7a. This irradiation region is called irradiation region A3'. In FIG. 9, the primary X-ray flux that has penetrated the cylindrical portion 7b of the irradiation port flange 7 and has been attenuated is re-entered into the line segment (Pi2-P10) or line segment (P11-P12) on the flange portion 7a, and is attenuated, thereby shielding the primary X-ray flux in the irradiation region A3'. The flange portion 7a has a groove for the O-ring 8 and a structure for attenuating the primary X-ray flux, and the outer diameter D7-2 is determined by the groove width and the irradiation region A3 irradiated from the tube attenuation tube 6.

[0043] 8 and 9, the attenuation ability in the region (P2-P3-P4) becomes closer to the x-axis, closer to P3, and since the distance the primary X-ray flux passes through the irradiation port flange 7 is short, when the X-ray intensity is strong, some of the X-ray flux cannot be shielded and attenuated primary X-ray flux may pass through. In Fig. 10, the primary X-ray flux passing through P2 is attenuated by the shielding cone 4 on the extension line, and it is possible to shield the primary X-ray flux except for the irradiation field A5 required for imaging as an X-ray source device.

[0044] The existence of the area (P1-Pi1-Po1), area (Pi2-Po2-P5-P6-P7-P8-P9), and line segment (Pi1-P2) in Figure 8 makes it possible to absorb errors in the coaxial alignment of the cylindrical portion 7b of the irradiation port flange 7 and the opening 6a of the tube attenuation tube 6, and errors in the primary X-ray flux area irradiated due to the presence or absence of contact between the tip of the cylindrical portion 7b of the irradiation port flange 7 and the tube attenuation tube 6.

[0045] In Figures 8 and 9, there is a gap of area (R2-P2-P1) filled with insulating medium 14 between line segment (P1-P2) and point R2 on opening 6a of attenuation tube 6. Area (R2-P2-P1) is smallest in the zx plane cross section of Figure 8 because point Pi1 on line segment (P1-P2) and point R2 on opening 6a of tube attenuation tube 6 coincide or approach each other as close as possible, and is largest in the xy plane cross section of Figure 9 because the tip line segment (P1-P2) of cylindrical part 7b of irradiation port flange 7 is flat and tube attenuation tube 6 is cylindrical. Point R2 moves in the x-axis direction along opening 6a of tube attenuation tube 6, so the area (R2-P2-P1) on the xy plane cross section increases continuously from the area (R2-P2-P1) on the zx plane cross section.

[0046] 8, point Pi1 on cylindrical portion 7b of irradiation port flange 7 coincides with or approaches as close as possible to point R2 on opening 6a of tube attenuation tube 6. At this time, line segment (P1-P2) of the tip of cylindrical portion 7b of irradiation port flange 7 makes line contact with tube attenuation tube 6 via line segment (P1-Pi1), or approaches as close as possible.

[0047] 8 and 9, the region (R2-P2-P1) can be divided into the region (R2-Pi1-P1) and the region (R2-P2-Pi1). The primary X-ray flux in the region (R2-Pi1-P1) is attenuated and shielded by the tube attenuation tube 6, and the irradiation direction of the primary X-ray flux is limited. The primary X-ray flux passing through the region (R2-P2-Pi1) enters the irradiation port flange 7 and is attenuated and shielded, so the primary X-ray flux does not leak out.

[0048] FIG. 11 is a diagram showing a case where the inner diameter d7-1 of the cylindrical portion 7b of the irradiation port flange 7 is made larger than that of the opening 5a of the insulating tube 5 and the opening 6a of the tube attenuation tube 6 in FIG. 10. When the irradiation port flange 7 is made larger than the opening 6a of the tube attenuation tube 6, the irradiation area A4 that limits the irradiation area A3 becomes larger, and the irradiation port flange 7 cannot limit the irradiation area A3. In addition, the irradiation area A4 may become equal to the irradiation area A3. In addition, since the irradiation area A4 can be attenuated when it is irradiated inside the shielding cone lead 4b, when the irradiation area A4 becomes larger, the shielding cone 4 becomes thicker, and the amount of lead used for the shielding cone lead 4b required for shielding increases, so the X-ray source device becomes heavier and larger. The size and position of the irradiation port flange 7 and the shielding cone 4 are determined taking into consideration that the irradiation area A3 is limited by the irradiation port flange 7 and the irradiation area A4 is limited by the shielding cone lead.

[0049] The secondary X-ray flux and higher order X-ray fluxes emitted from the region (R2-P2-P1) in Figures 8 and 9 and the cylindrical part of the tube attenuation tube 6 are shielded by the X-ray tube case shielding lead wrapped around the X-ray tube case 1.

[0050] If the line segment (P1-P2) at the tip of the cylindrical portion 7b of the irradiation port flange 7 in Figure 9 has a shape that follows the outer periphery of the tube attenuation tube 6, the processing costs will increase, but the area (R2-P2-P1) will be infinitesimally small and approximately constant on the circumference of the cylindrical portion 7b of the irradiation port flange 7, the primary X-ray flux will be attenuated by the irradiation port flange 7, and further attenuation of the higher-order X-ray flux will be possible.

[0051] When extracting the primary X-ray flux limited to the irradiation area A4 in Figures 6 and 7 for medical or diagnostic purposes, it is necessary to secure the distance between the X-ray tube focal point O and the subject 15 for each application and limit the range of the X-ray flux irradiated from the X-ray source device. The irradiation area A4 is limited to the irradiation field A5 by the lead inner wall of the shielding cone 4, and the distance between the X-ray tube focal point O and the subject is secured by the length of the shielding cone 4.

[0052] In the X-ray source device in Fig. 1, the primary X-ray beam other than that effectively used for diagnosis and examination as the irradiation field within the X-ray irradiation area is shielded by the hood 2a-1 of the X-ray tube 2, the tube attenuation tube 6, the irradiation port flange 7, and the shielding cone 4 in Fig. 7. As a result, the lead surrounding the outside of the X-ray tube container 1 is used only to attenuate the secondary X-ray beam, which is generated by the interaction between the primary X-ray beam and the parts in the X-ray source device and has a lower dose than the primary X-ray beam and is softer, and the thickness of the lead can be thinner than when it is used to attenuate the X-ray beam including the primary X-ray beam, making the X-ray source device lighter.

[0053] In the X-ray source device of Fig. 3, by avoiding the use of soft metals such as pure lead as the material for the tube attenuation tube 6, the probability of metal powder generation due to wear during assembly and transportation can be reduced, and processing and assembly can be made easier. The tube attenuation tube 6 and the irradiation port flange 7 can be made of materials with approximately the same density. In this embodiment, they are made of brass, and the two parts can be made of a combination of C2700 and C3604, respectively, or both parts can be made of C3604.

[0054] In the X-ray source device of FIG. 1, an example of a method for manufacturing the X-ray tube container 1 that is easy to process, lightweight, and strong is aluminum die casting.

[0055] In the X-ray source device of FIG. 1, ABS resin is an example of a material for the conical pipe-shaped resin part of the shielding cone 4 that can be molded in a mold and is inexpensive to manufacture.

[0056] In the X-ray source device of FIG. 3, examples of materials for the resin insulating tube 5 that is available in a pipe shape, is easy to cut, and has electrical insulation properties include acrylic resin and ABS resin.

[0057] In the X-ray source device of FIG. 1, examples of materials for the irradiation port flange 7 that have a larger X-ray attenuation coefficient, are harder, and are easier to machine than the aluminum alloy that is the material of the X-ray tube container 1 include brass and stainless steel (SUS303, SUS304, SUS316).

[0058] In the X-ray source device of FIG. 3, examples of materials for the O-ring 8 that are resistant to the insulating medium 14 such as insulating oil include NBR rubber, silicone rubber, fluororubber, and ethylene propylene rubber (EPDM).

[0059] In the X-ray source device of FIG. 3, examples of the material of the packing 9 that is resistant to the insulating medium 14 such as insulating oil include silicon rubber, NBR rubber, fluororubber, and ethylene propylene rubber (EPDM).

[0060] In the X-ray source device of FIG. 3, examples of materials for the X-ray transparent window 10 that are resistant to the insulating medium 14 such as insulating oil and transmit X-rays include acrylic and pure aluminum.

[0061] In the X-ray source device of FIG. 3, examples of materials that can be used to form the washer 11 include brass, SUS303, SUS304, and SUS316.

[0062] In the X-ray source device of FIG. 3, examples of materials for the irradiation port fixing screw 12 that can be formed into a screw by cutting include brass, SUS303, SUS304, and SUS316.

[0063] In the X-ray source device of FIG. 3, examples of the insulating medium 14 that electrically insulates the voltage applied to the X-ray tube 2 include insulating fluids such as insulating oil and sulfur hexafluoride, and insulating resins such as epoxy resin, silicone resin, and urethane resin. [Explanation of symbols]

[0064] 1 X-ray tube container 1a X-ray tube container irradiation port 2 X-ray tube 2a Anode 2a-1 Food 2a-2 Opening 2a-3 Target 2b Cathode 2b-1 Focusing body 2b-2 Shield plate 3 High voltage circuit board 4. Cone of Cone 4a Shielding Cone Shape Guide 4b Shielding cone lead 5. Insulating tube 5a opening 6 Tube attenuation tube 6a opening 7 Irradiation port flange 7a Flange 7b Cylindrical part 8 O-ring 9. Packing 10 X-ray transparent window 11 Washer 12 Irradiation port fixing screw 13 Tube fixing plate 14 Insulating media 15 Subject 16 Photosensitive surface A1: Irradiation area limited by the opening 2a-2 of the hood 2a-1 A1': Irradiation area of ​​primary X-rays attenuated by passing through the tube attenuation tube 6 A2 X-ray flux area irradiated to cathode 2b A3: Irradiation area of ​​the primary X-ray beam passing through the opening 6a of the tube attenuation tube 6 A3' Attenuated radiation transmitted through the cylindrical portion 7b of the irradiation port flange 7 Primary X-ray irradiation area A4 Irradiation area limited to the inner diameter of the cylindrical part 7b of the irradiation port flange 7 A5 Required irradiation field for imaging (irradiation field limited by shielding cone 4) OX ray tube^^ Pn(1≦n≦12) Outline point on irradiation port flange 7 Pin(0≦n≦2) X-ray incidence point on the irradiation port flange 7 and the irradiation area boundary Pon(0≦n≦2) X-ray transmission point on the boundary between the irradiation port flange 7 and the irradiation area Pi X-ray incidence point on the boundary between the flange 7 and the irradiation area A3' Q Point on opening 2a-2 of hood 2a-1 Ri1 Irradiation area A1 and point on the inner diameter of tube attenuation tube 6 Ro1 Irradiation area A1 and point on the outer diameter of tube attenuation tube 6 R2: Point on the outer diameter side of the opening 6a of the attenuated irradiation tube 6 R3: Point on the inner diameter side of the opening 6a of the attenuated irradiation tube 6 d2: Inner diameter of opening 2a-2 of hood 2a-1 d5: Inner diameter of opening 5a of insulating tube 5 d6 Inner diameter of opening 6a of tube attenuation tube 6 d7 Inner diameter of cylindrical part 7b of irradiation port flange 7 D7-1 Outer diameter of cylindrical part 7b of irradiation port flange 7 D7-2 Outer diameter of flange portion 7a of irradiation port flange 7 L Distance between tube surface and X-ray transmission window L7 Length of irradiation port flange 7

Claims

1. a gap between the X-ray tube housing and the X-ray diaphragm component is sealed, and the X-ray diaphragm component and the X-ray transmissive window are sealed to hermetically seal the insulating medium in the X-ray tube housing; and a primary X-ray flux passes through an insulating medium filled between a surface of an X-ray tube disposed in an X-ray tube container and an X-ray transmission window, and soft X-rays are absorbed by the insulating medium, a tube surrounding attenuator disposed within the X-ray tube case filled with an insulating medium and disposed around the outer periphery of the X-ray tube to attenuate the primary X-ray flux and the higher-order X-ray flux emitted from the X-ray tube, the tube surrounding attenuator being made of a metal having a second density greater than the first density of the metal material of the X-ray tube case; an irradiation field limiter that limits an irradiation area of ​​the primary X-ray beam emitted from the X-ray transmission window and extracts the X-ray beam in a predetermined irradiation field; having a medical X-ray source device, characterized in that the X-ray limiting component is disposed in an X-ray tube container filled with an insulating medium, and is provided between a tube-surrounding attenuator and an X-ray transmission window, has a cylindrical shape congruent or similar to the opening of the tube-surrounding attenuator, limits an irradiation area of ​​a primary X-ray flux passing through the opening of the tube-surrounding attenuator, and can extract the primary X-ray flux with the limited irradiation area from the opening of the X-ray limiting component, and is made of a metal having a third density greater than a first density.

2. a gap between the X-ray tube housing and the X-ray diaphragm component is sealed, and the X-ray diaphragm component and the X-ray transmissive window are sealed to hermetically seal the insulating medium in the X-ray tube housing; and a primary X-ray flux passes through an insulating medium filled between a surface of an X-ray tube disposed in an X-ray tube container and an X-ray transmission window, and soft X-rays are absorbed by the insulating medium, a tube surrounding attenuator disposed within the X-ray tube case filled with an insulating medium and disposed around the outer periphery of the X-ray tube to attenuate the primary X-ray flux and the higher-order X-ray flux emitted from the X-ray tube, the tube surrounding attenuator being made of a metal having a second density greater than the first density of the metal material of the X-ray tube case; an irradiation field limiter that limits an irradiation area of ​​the primary X-ray beam emitted from the X-ray transmission window and extracts the X-ray beam in a predetermined irradiation field; having the X-ray limiting component is disposed in an X-ray tube container filled with an insulating medium, and is provided between a tube-surrounding attenuator and an X-ray transmission window, has a cylindrical shape congruent or similar to the opening of the tube-surrounding attenuator, limits an irradiation area of ​​a primary X-ray flux passing through the tube-surrounding attenuator, and can extract the primary X-ray flux with the limited irradiation area from the opening of the X-ray limiting component, and is made of a metal having a third density greater than the first density.

3. 3. A medical X-ray source device according to claim 1, wherein the second density and the third density are substantially equal.

4. 3. A medical X-ray source device according to claim 1, further comprising an insulating body provided between the outer periphery of the X-ray tube and the tube-surrounding attenuator and having an opening smaller than and similar in shape to the opening of the tube-surrounding attenuator.

5. 5. A medical X-ray source device according to claim 4, wherein the insulating body has a cylindrical shape and a tube surrounding attenuator is provided on the outer circumferential surface of the insulating body.

6. 3. A medical X-ray source device according to claim 1, wherein the X-ray aperture part has a cylindrical portion having a cylindrical shape and a disk-shaped flange portion provided at one end of the cylindrical portion on the X-ray transmission window side.

7. 7. A medical X-ray source device according to claim 6, wherein the flange portion has an O-ring groove for sealing an insulating medium.

8. 7. The medical X-ray source device according to claim 6, wherein one end of the cylindrical portion of the X-ray aperture part on the X-ray tube side has a flat shape.

9. 3. The medical X-ray source device according to claim 1, wherein the X-ray tube has a hood which covers the anode target and has an opening for passing electrons emitted from the cathode and an opening for restricting the primary X-ray flux irradiated from the target.

Images