JP2009162577A - X-ray inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray inspection device having high image quality by reducing deviation due to changes in aging in an X-ray focus point of a micro focus X-ray tube. <P>SOLUTION: This device comprises an electron gun 114 stored in a vessel being kept in a vacuum state; a target 115, arranged at one end part of the advancing direction side of the electron generated from the electron gun 114; an X-ray tube 11a for generating the X-ray 3 from the X-ray focus point F of the target 115 by applying high voltage on the electron gun 114 and the target 115; an X-ray detector 13 for detecting the X-ray irradiated from the X-ray tube 11a and passed through an inspection object 2; a projection piece 117, arranged at the outer circumference of the vessel in the vicinity of the target 115; a rail 16 for supporting the X-ray tube 11a to be slidable in the direction where the X-ray focus point F is on one end; and a support base 14, equipped with a lock part 141 locking the projection piece 117 at a position closer to the target 115 than to the rail 16 to support the X-ray tube 11a at a predetermined position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus including a microfocus X-ray tube having a minute X-ray focal point.

  One type of X-ray tube used in an X-ray inspection apparatus is a microfocus X-ray tube having a small X-ray focal point of about 1 μm. Such a microfocus X-ray tube is used, for example, in an X-ray inspection apparatus such as an X-ray fluoroscopic inspection apparatus, a CT (Computer Tomography) apparatus, and a tomography apparatus (for example, see Patent Document 1).

As described above, the microfocus X-ray tube has a small X-ray focal point of about 1 μm. Therefore, in an X-ray inspection apparatus equipped with a microfocus X-ray tube, even if a subject is brought close to the X-ray focal point and a high-magnification transmission image is taken, a high-quality image with little blur of the transmission image due to the focal size is obtained. It is a feature that can be obtained.
JP 2001-135497 A

  Incidentally, in the X-ray inspection apparatus, each part of the X-ray tube may thermally expand due to a temperature change due to heat generation, and the X-ray tube may be distorted due to the thermal expansion. In particular, an X-ray inspection apparatus equipped with a microfocus X-ray tube is easily affected by the movement of the X-ray focal point with time due to thermal expansion during high magnification inspection. If the X-ray focus shifts during imaging with an X-ray inspection apparatus such as a CT apparatus or a tomography apparatus, the position of the rotation axis on the transmission image shifts, resulting in incomplete reconstruction processing and image degradation. Become.

  In view of the above-described problems, an object of the present invention is to provide an X-ray inspection apparatus with high image quality in which a shift with time of an X-ray focal point of a microfocus X-ray tube is reduced.

  In order to solve the above problems, an X-ray inspection apparatus according to a feature of the present invention includes an electron gun housed in a vacuum container and an end on the traveling direction side of electrons generated from the electron gun in the container. An X-ray tube that generates X-rays from an X-ray focal point of the target by applying a high voltage to the electron gun and the target, and irradiated from the X-ray tube, An X-ray inspection apparatus comprising: an X-ray detector that detects X-rays transmitted through a specimen; and a projection piece provided on an outer periphery of the container in the vicinity of the target, and the X-ray in a direction having the X-ray focal point as one end. A slide support portion that slidably supports the X-ray tube, and a locking portion that locks the protrusion at a position closer to the target than the slide support portion, and supports the X-ray tube at a predetermined position. And a support base.

  In the X-ray inspection apparatus having the above-described configuration, the X-ray tube is slidably supported on the sliding support portion (rail) while being fixed at a position close to the target. It is possible to stabilize the position of the target by absorbing along the slip along the line, reducing distortion caused by thermal expansion in each part of the X-ray tube and reducing movement of the X-ray focal point on the target.

  In the X-ray inspection apparatus, each of the projecting piece and the engaging portion has a surface perpendicular to the sliding direction, and the surface of the projecting piece and the surface of the engaging portion are abutted and fixed. Thus, the X-ray tube is positioned.

  With the above configuration, the X-ray tube and the fixing portion are fixed by screwing on the surface orthogonal to the sliding direction of the sliding support portion (rail), so that the force generated by screwing is along the sliding support portion (rail). It is absorbed by sliding and can be prevented from remaining as distortion in each part of the X-ray tube by fixing the X-ray tube, and the position of the target and the position of the focal point can be stabilized.

  According to the present invention, it is possible to improve the image quality of the X-ray inspection apparatus by reducing the temporal shift of the X-ray focus of the microfocus X-ray tube.

  Hereinafter, an X-ray inspection apparatus according to each embodiment of the present invention will be described with reference to the drawings. In the following embodiments, a CT apparatus will be described as an example of an X-ray inspection apparatus. In the following description, the same parts are denoted by the same reference numerals, and the description thereof is omitted. Similar parts are denoted by similar symbols. The present invention can be applied to various X-ray inspection apparatuses such as an X-ray fluoroscopic inspection apparatus and a tomography apparatus in addition to a CT apparatus.

<First Embodiment>
As shown in the plan view of FIG. 1A and the front view of FIG. 1B, the CT apparatus 1a according to the first embodiment includes an X-ray tube 11a and a subject 2 and a rotational axis RA. A rotation table 12 that rotates the subject 2 by rotating around the X-ray tube 11, an X-ray detector 13 that detects X-rays 3 generated from the X-ray tube 11 a and transmitted through the subject 2, and an X-ray tube 11 a And a support base 14 for supporting.

  The CT apparatus 1a includes a control unit that controls the X-ray tube 11a, a control unit that controls rotation of the rotary table 12, an image processing unit that reconstructs an inspection image using X-rays detected by the X-ray detector 13, Although connected to a monitor or the like for displaying the reconstructed image, FIG. 1 shows only the configuration used for realizing the present invention, and therefore the control unit and the like are not shown.

  The X-ray tube 11a is a microfocus X-ray tube having an X-ray focal point F of about 1 μm. As shown in FIG. 1, the X-ray tube 11 a includes a high-pressure generator 111 that generates a high voltage, a first vacuum vessel 112 connected to the high-voltage generator 111, and a second connected to the first vacuum vessel 112. And a vacuum vessel 113. The X-ray tube 11a of the CT apparatus 1a according to the first embodiment is an X-ray tube integrated with a high-pressure generator that includes a high-pressure generator 111 therein.

  Each of the first vacuum vessel 112 and the second vacuum vessel 113 has a cylindrical shape with the same diameter opened only on one side, and the opening of the first vacuum vessel 112 and the second vacuum vessel 113 is an O-ring ( It is hermetically connected with screws via a screw (not shown) to form one internal space that becomes an electronic passage (not shown). Since the internal space formed by the first vacuum vessel 112 and the second vacuum vessel 113 is shut off from the outside, the internal air is exhausted by a vacuum pump (not shown) to be in a vacuum state.

  As shown in FIG. 1, the first vacuum vessel 112 and the second vacuum vessel 113 have an axis TA as a central axis. Inside the first vacuum vessel 112, an electron gun 114, which is a cathode, is disposed on the axis TA. The tip of the second vacuum vessel 113 on the cylinder bottom side has a truncated cone shape in which the diameter of the cylinder bottom is shorter than the diameter of the cylinder mouth, and the target 115 serving as an anode is perpendicular to the axis TA on the cylinder bottom. The converging coil 116 is arranged around the axis TA. That is, in the X-ray tube 11a, the electron gun 114 and the target 115 are disposed in an internal space (electron passage) that is in a vacuum state formed by the first vacuum vessel 112 and the second vacuum vessel 113. On the other hand, the converging coil 116 is arranged at a position where the outer periphery of the electron passage inside the second vacuum vessel 113 is in an atmospheric pressure state.

  At the time of inspection (at the time of X-ray irradiation), a high voltage is applied between the electron gun 114 and the target 115 by the high voltage generator 111. By applying a high voltage, electrons generated from a filament (not shown) of the electron gun 114 are accelerated as an electron beam in a vacuum, and the electron beam accelerated by the magnetic field created by the focusing coil 116 is on the axis TA. To converge. Further, the X-ray 3 is generated from the X-ray focal point F when the electron beam converged on the axis TA hits the target 115.

  As shown in FIG. 1, two bearing blocks 15 are respectively fixed on two straight lines (not shown) parallel to the axis TA on the support base 14 side of the high pressure generator 111. The bearing block 15 is a generally used bearing block having a plurality of balls 15a and 15b as shown in FIG.

  Two linear rails 16 are installed in parallel on the parallel surface 142 of the support base 14. On each rail 16, two bearing blocks 15 fixed to the high-pressure generator 111 are arranged so as to engage with the rail 16.

  When a longitudinal force of the rail 16 is applied to the bearing block 15, the balls 15 a and 15 b move while rotating on the inside of the bearing block 15 and on the rail 16, and the bearing block 15 slides on the rail 16. The rail 16 and the bearing block 15 correspond to a sliding support portion in claims. Therefore, the bearing block 15 fixed to the X-ray tube 11a is arranged on the rail 16 so that the longitudinal direction (the direction of the axis TA) with the X-ray focal point of the X-ray tube 11a as one end coincides with the longitudinal direction of the rail 16. Thus, when a force in the direction of the axis TA is applied to the X-ray tube 11a, the bearing block 15 fixed to the X-ray tube 11a slides on the rail 16 along the axis TA.

  Here, the length of the rail 16 only needs to be long enough to support the X-ray tube 11a, and is, for example, about half the length of the X-ray tube 11a. In the CT apparatus 1a, the X-ray tube 11a can be stably supported by having the plurality of bearing blocks 15 and the rails 16, but the number of the bearing blocks 15 and the rails 16 is not limited.

  As shown in FIG. 1B, the second vacuum vessel 113 has a projecting piece 117 having a surface perpendicular to the axis TA on the outer periphery at a position closer to the target 115 than the rail 16. In addition, the support base 14 has a locking portion 141 having a surface that is perpendicular to the axis TA and engages with the protruding piece 117.

  FIG. 3 is a view of the CT apparatus 1a as viewed from the target 115 side. As shown in FIG. 3, the support base 14 fixes the second vacuum vessel 113 by fixing with the screw 17 in a state where the locking portion 141 and the protruding piece 117 are engaged.

  Here, when the projecting piece 117 and the locking part 141 are fixed, the bearing block 15 fixed to the high pressure generating unit 111 is engaged with the projecting piece 117 and the locking part 141 along the rail 16. Move and fasten with screws. In the example shown in FIG. 3, the protruding piece 117 and the locking portion 141 are fixed by two screws 17, but the number of screws 17 is not limited.

  The first vacuum vessel 112 and the second vacuum vessel 113 are connected by a hinge 118 as shown in FIG. When performing maintenance such as filament replacement of the electron gun 114, first, the internal space formed by the first vacuum vessel 112 and the second vacuum vessel 113 is changed from a vacuum state to an atmospheric pressure state, and then the projecting piece 117 and the locking portion Remove the screw 17 fixing 141. Thereafter, a screw (not shown) for fixing the first vacuum vessel 112 and the second vacuum vessel 113 is removed, and the side surface of the second vacuum vessel 113 on the hinge 118 side with the hinge 118 as an axis as shown in FIG. The second vacuum vessel 113 is moved so that the side surface on the hinge 118 side of the first vacuum vessel 112 is aligned to open the internal space formed by the first vacuum vessel 112 and the second vacuum vessel 113, and filament replacement and the like are performed. Do.

  The X-ray tube 11a undergoes thermal expansion in each part of the high-pressure generator 111, the first vacuum vessel 112, and the second vacuum vessel 113 when a high voltage is generated. For example, in the CT apparatus 1a shown in FIG. 1, the position near the high-pressure generator 111 of the X-ray tube 11a and the converging coil 116 of the second vacuum vessel 113 is likely to become high temperature and often causes thermal expansion. When the expansion and contraction in the TA direction accompanying thermal expansion occurs in the X-ray tube 11a, in the CT apparatus 1a described above, the bearing block 15 slides on the rail 16 along with the expansion and contraction of the X-ray tube 11a. The strain 11 a is absorbed by the sliding of the bearing block 15. In particular, the expansion and contraction in the TA direction has a great influence on the shift of the X-ray focal point F. However, the CT block described above can be obtained by sliding the bearing block 15 on the rail 16 in the TA direction as the X-ray tube 11a expands and contracts. In 1a, the distortion due to the expansion and contraction of the X-ray tube 11a in the TA direction is absorbed, and the shift of the X-ray focal point F can be reduced.

  Further, expansion and contraction and vibration in the vicinity of the target 115 cause a shift in the X-ray focal point F. However, since the X-ray tube 11a is fixed in the vicinity of the target 115, in the X-ray tube 11a of the CT apparatus 1a described above, The deviation of the X-ray focal point F can be reduced.

  Further, when the projecting piece 117 and the locking portion 141 are fixed, the direction of the screw 17 is aligned with the direction of the axis TA, and the force generated by the screwing is absorbed by the bearing block 15, so that the X-ray tube 11a is fixed. The distortion does not remain, and the deviation of the X-ray focal point F can be reduced.

  As described above, in the CT apparatus 1a according to the first embodiment of the present invention, the expansion and contraction caused by thermal expansion in each part of the X-ray tube 11a is absorbed by the bearing block 15 to prevent distortion, and the X-ray focal point F is set. Since it becomes possible to stabilize, the image quality of CT apparatus 1a can be improved.

<Modification>
In the CT apparatus 1a described above, the bearing block 15 is fixed to the high pressure generator 111, and the bearing block 15 is slidable on the rail 16 disposed on the support base 14. However, the fixing member fixed to the X-ray tube 11 a is not limited to the bearing block 15. Further, the member that is disposed on the support base 14 and supports the bearing block 15 is not limited to the rail 16. That is, the X-ray tube 11a may be configured to be slidable along the axis TA. For example, as shown in FIG. 5, a wheel 181 is used as a fixing member instead of the bearing block 15, and the wheel 181 rotates on the rail 16 around a shaft 182 connected to the high pressure generator 111. Also good. Further, instead of the bearing block 15, a block without balls may be used so that the block slides on the rail 16. In this case, the rail 16, the wheel 181, the shaft 182, the block without a ball, and the like correspond to the sliding support portion of the claims. Further, the rail may be fixed to the high pressure generator 111 and the bearing block (or the wheel 181, the shaft 182, a block without a ball, etc.) may be fixed to the support base 14.

  Further, in the CT apparatus 1a described above, the projecting piece 117 is fixed to the locking portion 141 with a screw. However, the configuration for fixing the X-ray tube 11 a is not limited to the screw 17. That is, the X-ray tube 11a can be fixed to the support base 14 at a position close to the target 115, and the internal structure constituted by the first vacuum vessel 112 and the second vacuum vessel 113 when the filament is exchanged. Any structure that can open the space may be used. It is desirable that the projecting piece 117 and the locking portion 141 are fixed in the direction of the axis TA, and the force generated by the fixing is absorbed by the sliding of the bearing block 15. For example, it is conceivable to use bolts and nuts, fixing levers or the like instead of the screws 17.

  In the first embodiment, as the X-ray tube 11a, the transmission type X-ray tube using the X-rays transmitted through the target 115 has been described above. However, the present invention can be applied even when a reflection type X-ray tube is used. Can be easily understood by those skilled in the art.

<Second Embodiment>
As shown in the plan view of FIG. 6A and the front view of FIG. 6B, the CT apparatus 1b according to the second embodiment includes an X-ray tube 11b, a rotary table 12, and an X-ray detector. 13 and a support base 14 for supporting the X-ray tube 11b. In the CT apparatus 1b, similarly to the CT apparatus 1a according to the first embodiment described above, the protruding piece 117 of the X-ray tube 11b is fixed to the locking portion 141 of the support base 14 with screws 17.

  When the CT apparatus 1b according to the second embodiment is compared with the CT apparatus 1a according to the first embodiment, the CT apparatus 1a uses an X-ray tube 11a integrated with a high-pressure generator. On the other hand, the CT apparatus 1b is different in that a high-pressure generating part separation type X-ray tube 11b is used. That is, the X-ray tube 11b shown in FIG. 6 includes the first vacuum container 112 and the second vacuum container 113, but does not include the high-pressure generator 111. In the CT apparatus 1a, the bearing block 15 is connected to the high pressure generator 111. On the other hand, the CT apparatus 1b differs in that the bearing block 15 is connected to the first vacuum vessel 112.

  Therefore, the CT apparatus 1b generates a high voltage by a high voltage generator (not shown) provided outside the X-ray tube 11b during the inspection (at the time of X-ray irradiation), and between the electron gun 114 and the target 115. A high voltage is applied to generate X-rays 3 from the X-ray focal point F to obtain an inspection image of the subject 2.

  The other configuration of the CT apparatus 1b is the same as that of the CT apparatus 1a described above. When the X-ray tube 11b expands and contracts due to thermal expansion, the bearing block 15 fixed to the X-ray tube 11b moves on the rail 16 along the axis TA. To prevent distortion due to thermal expansion.

1 is a schematic diagram illustrating a CT apparatus according to a first embodiment of the present invention. It is the schematic explaining the bearing block utilized with CT apparatus of FIG. It is the schematic explaining the structure which fixes an X-ray tube to a support stand with CT apparatus of FIG. It is the schematic explaining opening and closing of the vacuum vessel of the X-ray tube of CT apparatus of FIG. It is the schematic explaining the wheel utilized with CT apparatus concerning a modification. It is the schematic explaining the CT apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b ... CT apparatus 11a, 11b ... X-ray tube 111 ... High pressure generation part 112, 113 ... Vacuum vessel 114 ... Electron gun 115 ... Target 116 ... Converging coil 117 ... Projection piece 118 ... Hinge 12 ... Rotary table 13 ... X-ray Detector 14 ... Supporting base 141 ... Locking part 15 ... Bearing block 15a, 15b ... Ball 16 ... Rail 17 ... Screw 181 ... Wheel 182 ... Shaft

Claims (2)

An electron gun housed in a vacuum container and a target disposed in an end of the container in the traveling direction side of electrons generated from the electron gun and a high voltage applied to the electron gun and the target An X-ray tube that, when applied, generates X-rays from the X-ray focal point of the target;
In an X-ray inspection apparatus having an X-ray detector that detects X-rays irradiated from the X-ray tube and transmitted through the subject,
A projecting piece provided on the outer periphery of the container in the vicinity of the target;
A sliding support portion for slidably supporting the X-ray tube in a direction having the X-ray focal point as one end; and a locking portion for locking the protruding piece at a position closer to the target than the sliding support portion. A support base for supporting the X-ray tube at a predetermined position;
An X-ray inspection apparatus comprising: Each of the projecting piece and the engaging portion has a surface perpendicular to the sliding direction, and the surface of the projecting piece and the surface of the engaging portion are abutted and fixed, thereby positioning the X-ray tube. Will be
The X-ray inspection apparatus according to claim 1.

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