JP2024118389A - X-ray source device - Google Patents

Abstract

To reduce a weight of an X-ray source device by reducing a use amount of lead for blocking a leakage ray.SOLUTION: An X-ray source device includes: an X-ray pipe container that is filled with an insulation medium; an X-ray pipe 2 that is arranged in the X-ray pipe container; a bulb attenuation lead 6 that is arranged at an outer periphery of the X-ray pipe 2 in order to block an X-ray flux radiated from the X-ray pipe 2 and can radiate a primary X-ray flux whose radiation region is limited, from an open part; an X-ray transparence window 10 that is arranged in order to fetch out a primary X-ray flux from the X-ray pipe container at a distance from the X-ray pipe 2 for attenuating a soft X-ray during the primary X-ray flux by the insulation medium; an irradiation port flange 7 that is provided between the bulb attenuation lead 6 and the X-ray transparence window 10, has a cylinder-like shape that is the same with or similar to a bulb attenuation open part, and limits the irradiation region of the primary X-ray flux radiated from the bulb attenuation open part at the neighbor of the bulb attenuation open part; and a blocking cone that obtains the X-ray flux in an irradiation field in which the irradiation region of the primary X-ray flux radiated from the X-ray transparence window 10 is limited and is defined. In the X-ray source device, lead for blocking the circumference of the device is reduced by blocking the primary X-ray other than the irradiation field.SELECTED DRAWING: Figure 10

Description

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.

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 the cathode are disposed in a vacuum envelope, facing each other. 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 is equipped with 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 the target, 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 radiated to the outside through an X-ray radiation 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.

The X-ray tube assembly incorporating the X-ray tube 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 the like, 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 provided with an X-ray emission port for extracting the X-ray beam to the outside and a cable receptacle attachment portion for attaching a cable receptacle, and a lead plate or the like is 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 a high voltage supplied from an external high-voltage generator into the X-ray tube case. In some cases, a high-voltage generator is housed in the X-ray tube assembly instead of a cable receptacle.

Generally, in diagnostic radiology, X-ray source devices use filters to attenuate the X-ray flux, mainly in the low energy region of the X-ray spectrum, thereby reducing the dose and noise and 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 under examination. In diagnostic radiology, a conventional minimum filtration is often performed by standard filtration with 3 millimeters of aluminum as a standard for comparing the X-ray output from different X-ray tubes.

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

Generally, the secondary X-ray flux is smaller in quantity, softer, and generally has a larger angle of incidence than the primary X-ray flux, so copper-based and iron-based metals may be effective in attenuating X-rays.

As a known example, an X-ray source device in which an X-ray flux irradiation area is limited by providing a cylindrical cone lined with lead and an X-ray shielding cylinder is provided inside a metal X-ray tube housing is disclosed in Patent Document 1. However, there is no description of a structure for shielding the primary X-ray flux with a shielding cylinder surrounding the tube and an irradiation port flange.

As a known example, an X-ray tube 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 cylinder surrounding the tube and an X-ray aperture part.

As a publicly known example, an X-ray tube assembly 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 in which the filter is made of insulating oil, or a structure in which the primary X-ray flux is shielded by a shielding cylinder surrounding the tube and an X-ray aperture part.

As a known example, an X-ray diagnostic apparatus 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 cylinder surrounding the tube and an X-ray aperture part.

As a publicly known example, an X-ray tube assembly having an X-ray shielding cylinder 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 insulating oil, or a structure in which the primary X-ray flux is shielded by a shielding cylinder surrounding the tube and an X-ray aperture part.

Actual fairness 03-019199 Patent 4919956 Special table 2009-545840 Patent Publication No. 2021-115113 JP 56-042998 A

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 a problem that the strength required for the support structure to support the X-ray source device and ensure vibration stability is high.

The X-ray source device of the first aspect of the present invention is
an x-ray tube envelope made of a metal having a first density filled with an insulating medium;
an x-ray tube disposed within an x-ray tube housing;
a tube surrounding shield arranged around the outer periphery of the X-ray tube to shield the primary X-ray flux and the higher-order X-ray flux irradiated from the X-ray tube, capable of extracting the primary X-ray flux with a limited irradiation area from an opening, and made of a metal having a second density greater than the first density;
an X-ray transmitting window arranged at a distance from the X-ray tube where the insulating medium attenuates soft X-rays among the X-rays emitted from the X-ray tube, for extracting a primary X-ray beam from the X-ray tube container;
an X-ray aperture part that is provided between the tube surrounding shield and the X-ray transmission window, has a cylindrical shape that is congruent or similar to the opening of the tube surrounding shield, limits an irradiation area of the primary X-ray flux emitted from the opening of the tube surrounding shield to the vicinity of the opening of the tube surrounding shield, and is made of a metal having a third density that is greater than the first density and less than the second density;
and an irradiation field limiter for limiting an irradiation area of the primary X-ray flux emitted from the X-ray transmission window to extract the X-ray flux in a predetermined irradiation field.

The second aspect of the present invention is the X-ray source device of the first aspect of the present invention,
The X-ray tube has an insulating body provided between the outer periphery of the X-ray tube and a tube-surrounding shield, the insulating body having an opening that is similar in shape to and smaller than the opening of the tube-surrounding shield.

The third aspect of the present invention is the X-ray source device of the second aspect of the present invention,
The insulating body has a cylindrical shape, and a bulb surrounding shield is provided on the outer circumferential surface of the insulating body.

The fourth aspect of the present invention is the X-ray source device of the first aspect of the present invention,
The X-ray aperture part 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.

The fifth aspect of the present invention is the X-ray source device of the fourth aspect of the present invention,
The flange portion is characterized by having an O-ring groove for sealing the insulating medium.

The sixth aspect of the present invention is the X-ray source device of the first aspect of the present invention,
The X-ray aperture part is characterized in that one end of the cylindrical portion on the X-ray tube side has a flat shape.

The seventh invention is the X-ray source device of the first invention, characterized in that the X-ray tube has a hood that 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.

In the first invention, by providing an X-ray aperture component between the tube surrounding shield 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, so that the area of lead wrapped around the entire X-ray source device can be made small, the thickness can be made thin, and a lightweight X-ray source device can be provided.

FIG. 1 is a diagram showing an X-ray source device arranged within an xyz coordinate system with the focal position O of an X-ray tube 2 as the origin. FIG. 2 is a cross-sectional view of the X-ray source device of FIG. 1 taken along the xy plane. FIG. 3 is an enlarged view of the periphery of the X-ray tube 2 in FIG. FIG. 4 is a diagram showing the arrangement of the X-ray tube 2, insulating tube 5, tube attenuation lead 6, and X-ray aperture part 7 within an xyz coordinate system with the focal position O of the X-ray tube 2 as the origin. FIG. 5 is a diagram of the yz plane of FIG. 4 as viewed from the positive direction of the x axis. 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 an xy plane cross section. 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 a zx plane cross section. 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. 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. FIG. 10 is a diagram showing the irradiation area in FIG. 6 with attention focused on the positional relationship between the X-ray tube, the X-ray aperture part 7, and the shielding cone 4. FIG. 11 is a diagram showing the irradiation area in FIG. 10 with attention focused on the positional relationship between the tube shielding lead opening 6a, the irradiation port flange 7, and the shielding cone 4.

(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 the previous drawings, the same reference numerals may be used, and detailed explanations may be omitted as appropriate.

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

An example of an irradiation field limiter in the claims is the shielding cone 4, an example of an insulating object is the insulating tube 5, an example of a shield around the tube is the tube attenuation lead 6, and an example of an X-ray aperture part is the irradiation port flange 7.

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. To seal, an irradiation port flange 7 having a flange portion 7a and a cylindrical portion 7b with an O-ring groove 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 liquid or gas. On the outer periphery of the X-ray tube 2, there is a cylindrical insulating tube 5 with a tube attenuation lead 6 fixed to the outer periphery with an adhesive, and this insulating tube 5 is fixed to a tube fixing plate 13 by a metal band, 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 container 1 with a screw, and the X-ray tube 2 is fixed to the X-ray tube container 1. The insulating tube 5 is a resin cylinder used to prevent discharge to surrounding metal parts when 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 Figure 7 are passed through both end faces of the insulating tube 5. Tube attenuation lead 6 is wrapped around the insulating tube to attenuate the X-ray flux around the X-ray tube. The thickness and purity of the lead are determined by the output required for the X-ray generator. The shielding cone 4, which is made of lead wrapped around a conical pipe-shaped resin part, is fastened to the outside of the X-ray tube container 1 with screws via metal fixing brackets.

In the X-ray source device in Fig. 3, the insulating tube 5 and the tube attenuation lead 6 have openings 5a and 6a, respectively, and the opening 2a-2 of the anode 2a of the X-ray tube in the hood 2a-1, the insulating tube opening 5a, and the attenuation lead opening 6a are concentric circles. 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 have the same central axis. This central axis is the x-axis including the X-ray tube focal point O shown in Fig. 1.

In the X-ray source device of FIG. 3, the irradiation port flange 7 is a rotating body having a disk-shaped flange portion 7a and a cylindrical portion 7b with a groove for fitting an O-ring 8, and a center line of the x-axis. 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 most 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. With an O-ring 8 made of NBR rubber fitted in the groove of the irradiation port flange 7, it is inserted into the irradiation port 1a opening in the X-ray tube container 1. At this time, the irradiation port flange 7 is arranged coaxially with the opening 2a-2 opening in the hood 2a-1, the insulating tube opening 5a, and the attenuation lead opening 6a, and the tip of the cylindrical portion 7b of the irradiation port flange 7 is in line contact or as close as possible to the tube attenuation lead 6 with two line segments parallel to the z-axis. Next to the irradiation port flange 7, a rubber packing 9 such as silicone and an X-ray transmission window 10 made of resin such as acrylic are arranged, and are fastened with a metal washer 11 and an irradiation port fixing screw 12 to fix it to the X-ray tube container 1. In order to seal the insulating medium 14 inside the X-ray tube container 1, an O-ring 8 seals between the X-ray tube container 1 and the irradiation port flange 7, and a packing 9 seals between the irradiation port flange 7 and the X-ray transmission window 10. The inside of the X-ray tube container 1 is filled with an insulating medium 14 such as insulating oil, and insulates against high voltage. The distance L between the surface of the X-ray tube 2 and the X-ray transmission 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 a medical X-ray generator, it is necessary to absorb soft X-rays, adjust the radiation quality, and display the total filtration expressed in radiation quality equivalent filtration. By changing the distance L through which the X-ray flux passes based on the inherent filtration value of the insulating medium 14, it is possible to adjust the radiation quality. The distance L is determined by the length L7 of the irradiation port flange 7.

4 is a diagram in which the X-ray tube 2, the insulating tube 5, the tube attenuation lead 6, and the irradiation port flange 7 are extracted 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, it is possible to align the opening 5a of the insulating tube 5 and the irradiation port flange 7 so that the central axis of the opening 5a is the same. Here, in addition to the measures against deformation at the contact portion between the irradiation port flange 7 and the tube attenuation lead 6 described later, when using a jig for alignment, in order to avoid deformation of the opening 6a of the tube attenuation lead 6, the inner diameter d6 of the opening 6a of the tube attenuation lead 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 lead 6 is formed smaller than the outer diameter D7-1 of the cylindrical portion of the irradiation port flange 7 in order to limit the irradiation area described later.

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 lead 6, and the irradiation port flange 7, among the components of the X-ray source device of the embodiment of FIG. 1, arranged in an xyz coordinate system with the X-ray tube focal position as the origin. Also, FIG. 7 is a zx plane cross-sectional view of the same configuration as FIG. 6.
This shows 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. 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. The irradiation area A1 is limited to an irradiation area A3 by the opening 6a of the tube attenuation lead 6, and is further limited to an irradiation area A4 by the irradiation port flange 7. Finally, the irradiation area A4 is limited by the shielding cone 4, and a predetermined irradiation field A5 required for imaging is obtained, which is irradiated to the subject 15, and an X-ray image is acquired on the X-ray receiving surface 16.

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

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. The region (P8-P9-P10-P11) is a groove into which the O-ring 8 is fitted.

The line segment (P1-P2) in FIG. 8 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 7b 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. The line segments (P7-P8) and (P11-P12) are collinear and parallel to the yz plane. The line segment (P12-P1) is 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. The line segments (P8-P9) and (P10-P11) are parallel to the x-axis and form the groove width for the O-ring 8. The line segment (P9-P10) is parallel to the line segment (P7-P12) and forms the groove bottom for the O-ring 8.

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 the opening of hood 2a-1, and is attenuated when it hits point R1 on the inner wall of tube attenuation lead 6 on an extension of point Q on the opening of hood 2a-1 and focal point O. Irradiation area A3 is obtained in the range on the line connecting point R2 on the opening 6a of tube attenuation lead 6 and focal point O. A part of irradiation area A1 limited by target 2a-3 does not hit tube attenuation lead 6 and is irradiated further out without being limited by the opening 6a.

A 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 a 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 lead 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), a point on the line segment (P12-P1) is set as point Po1, a point on the line segment (P9-P10) is set as point Pi2, and a point on the line segment (P4-P5) is set as point Po2, and a 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 of the irradiation area A3 is attenuated within the range of the area (Pi1-P2-P3-P4-Po2-Pi2-P10-P11-Po1).

8 and 9, when the X-ray intensity is strong, the thin wall of the cylindrical portion 7b of the irradiation port flange 7 cannot shield the primary X-ray flux in the region (Po1-P12-P11-P10-Pi2), and the attenuated primary X-ray flux may penetrate and irradiate the flange portion 7a. In FIG. 9, the transmitted X-ray flux is re-entered into the line segment (Pi2-P10) or line segment (P11-P12) on the flange portion 7a and is attenuated. 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 lead 6.

8 and 9, the attenuation ability in the region (P2-P3-P4) becomes closer to P3 as it approaches the x-axis, and the distance that the primary X-ray flux passes through the irradiation port flange 7 is short, so when the X-ray intensity is strong, some of the X-ray flux cannot be shielded and the attenuated primary X-ray flux may pass through. In Fig. 10, the primary X-ray flux is attenuated by the shielding cone 4 on the extension line of the primary X-ray flux passing through P2, 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.

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 lead 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 lead 6.

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

In the zx plane cross section of FIG. 8, point Pi1 on the cylindrical portion 7b of the irradiation port flange 7 and point R2 on the opening 6a of the tube attenuation lead 6 coincide or approach as close as possible. At this time, the line segment (P1-P2) of the tip of the cylindrical portion 7b of the irradiation port flange 7 makes line contact with the tube attenuation lead 6 at the line segment (P1-Pi1), or approaches as close as possible. The point on the opening 5a of the insulating tube 5 is set as point S, and the point where the insulating tube 5 and the opening 6a of the tube attenuation lead 6 are in contact is set as point R3. When the tip of the irradiation port flange 7 contacts the tube attenuation lead 6, the opening 6a of the tube attenuation lead 6 may be deformed. At this time, the thickness of the line segment (R2-R3) becomes thinner at the deformed portion of the tube attenuation lead 6, and the opening 6a becomes smaller. Due to this deformation, point R3 approaches point S, but it is very small, and deformation occurs within the range of the region (S-R3-R2). If the tube attenuation lead 6 is deformed beyond the edge at point S, the tube attenuation lead 6 is subjected to shear stress at point S, which may cause burrs or shear fracture and may result in electrical risks such as discharge. In this embodiment, the tube attenuation lead 6 does not come into contact with point S, so burrs or shear fracture do not occur.

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 lead 6, and the irradiation direction of the primary X-ray flux in the region (R2-P2-Pi1) is also limited, so the primary X-ray flux does not leak.

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 lead 6 in FIG. 10. When the irradiation port flange 7 is made larger than the opening 6a of the tube attenuation lead 6, the irradiation area A4 that limits the irradiation area A3 becomes larger, and finally the irradiation port flange 7 cannot limit the irradiation area A3, and the irradiation area A4 becomes equal to the irradiation area A3. In addition, when the irradiation area A4 is irradiated inside the shielding cone lead 4b, it can be attenuated, so when the irradiation area A4 becomes larger, the shielding cone 4 becomes thicker, and the shielding cone lead 4b required for shielding becomes more, so the X-ray source device becomes heavier and larger. Considering 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, the size and position of the irradiation port flange 7 and the shielding cone 4 are determined.

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

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 lead 6, the processing costs will increase, but the area (R2-P2-P1) will be extremely 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 in the area (R2-P2-P1), and further attenuation of higher order X-ray flux will be possible.

6 and 7 for medical or diagnostic purposes, it is necessary to ensure the distance between the focal point O and the subject 15 for each purpose and to 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 focal point O and the subject is ensured by the length of the shielding cone 4.

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

In the X-ray tube assembly 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.

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.

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

In the X-ray tube 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, SUS303, SUS304, and SUS316.

In the X-ray tube assembly of FIG. 3, examples of materials for the O-ring 8 that are resistant to insulating oil include NBR rubber, silicone rubber, fluororubber, and ethylene propylene rubber (EPDM).

In the X-ray tube assembly of FIG. 3, examples of the material of the packing 9 that is resistant to insulating oil include silicon rubber, NBR rubber, fluororubber, and ethylene propylene rubber (EPDM).

In the X-ray tube assembly of FIG. 3, examples of materials for the X-ray transmissive window 10 that are resistant to insulating oil and transmit X-rays include acrylic and pure aluminum.

In the X-ray tube assembly of FIG. 3, examples of materials that can be used to form the washer 11 include brass, SUS303, SUS304, and SUS316.

In the X-ray tube assembly of FIG. 3, examples of materials for the irradiation port fixing screw 12 that can be threaded by cutting include brass, SUS303, SUS304, and SUS316.

In the X-ray tube assembly of FIG. 3, examples of the insulating medium 14 that electrically insulates the voltage applied to the X-ray tube include insulating fluids such as insulating oil, and insulating resins such as epoxy resin, silicone resin, and urethane resin.

1 X-ray tube container 1a X-ray tube container irradiation port 2 X-ray tube 2a Anode 2a-1 Hood 2a-2 Opening 2a-3 Target 2b Cathode 2b-1 Focusing body 2b-2 Shielding plate 3 High voltage circuit board 4 Shielding cone 4a Shielding cone shape guide 4b Shielding cone lead 5 Insulating tube 5a Insulating tube opening 6 Tube attenuation lead 6a Attenuation lead irradiation opening 7 Irradiation port flange 7a Flange portion 7b Cylindrical portion 8 O-ring 9 Gasket 10 X-ray transmission window 11 Washer 12 Irradiation port fixing screw 13 Tube fixing plate 14 Insulating medium 15 Subject 16 Light receiving surface A1 Irradiation area A2 limited by hood opening 2b X-ray flux area A3 irradiated to cathode 2b Irradiation area A4 limited to tube attenuation lead 6 opening 6a Irradiation area A5 limited to inner diameter of irradiation port flange 7 cylindrical portion 7b Required irradiation field (irradiation field limited to shielding cone 4)
O X-ray tube focal point Pn (1≦n≦12) Outer shape point Pin on irradiation port flange 7 (0≦n≦2) X-ray incidence point Pon (0≦n≦2) on the boundary between irradiation port flange 7 and the irradiation area X-ray transmission point Q on the boundary between irradiation port flange 7 and the irradiation area Point R1 on the hood opening Point R2 on the irradiation area A1 and the inner wall of the tube attenuation lead 6 Point R3 on the outer diameter side on the attenuation lead irradiation opening 6a Point S on the inner diameter side on the attenuation lead irradiation opening 6a Point d2 on the outer diameter side on the insulating tube opening 5a Inner diameter d5 of hood opening 2b Inner diameter d6 of insulating tube opening 5a Inner diameter d7 of opening 6a of tube attenuation lead 6 Inner diameter D7-1 of cylindrical part 7b of irradiation port flange 7 Outer diameter D7-2 of cylindrical part 7b of irradiation port flange 7 Outer diameter L of flange part 7a of irradiation port flange 7 Distance L7 between tube surface and X-ray transmission window Length of irradiation port flange 7

Claims (7)

an x-ray tube envelope made of a metal having a first density filled with an insulating medium;
an x-ray tube disposed within an x-ray tube housing;
a tube surrounding shield arranged around the outer periphery of the X-ray tube to shield the primary X-ray flux and the higher-order X-ray flux irradiated from the X-ray tube, capable of extracting the primary X-ray flux with a limited irradiation area from an opening, and made of a metal having a second density greater than the first density;
an X-ray transmitting window arranged at a distance from the X-ray tube where the insulating medium attenuates soft X-rays among the X-rays emitted from the X-ray tube, for extracting a primary X-ray beam from the X-ray tube container;
an X-ray aperture part that is provided between the tube surrounding shield and the X-ray transmission window, has a cylindrical shape that is congruent or similar to the opening of the tube surrounding shield, limits an irradiation area of the primary X-ray flux emitted from the opening of the tube surrounding shield to the vicinity of the opening of the tube surrounding shield, and is made of a metal having a third density that is greater than the first density and less than the second density;
and an irradiation field limiter for limiting an irradiation area of the primary X-ray beam emitted from the X-ray transmission window to extract the X-ray beam in a predetermined irradiation field. 2. The X-ray source device according to claim 1, further comprising an insulating body provided between an outer periphery of the X-ray tube and a tube surrounding shield, the insulating body having an opening smaller than and similar in shape to the opening of the tube surrounding shield. 3. The X-ray source device according to claim 2, wherein the insulating body has a cylindrical shape and a tube surrounding shield is provided on the outer circumferential surface of the insulating body. 2. The X-ray aperture part according to claim 1, wherein the X-ray aperture part is an X-ray source device 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. 5. The X-ray source device according to claim 4, wherein the flange portion has an O-ring groove for sealing the insulating medium. 4. The X-ray source device according to claim 3, wherein one end of the cylindrical portion of the X-ray aperture part on the X-ray tube side has a flat shape. 2. The X-ray tube according to claim 1, further comprising an X-ray source device having a hood which covers an anode target and has an opening for passing electrons emitted from the cathode and an opening for restricting a primary X-ray flux irradiated from the target.

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