JP2023139720A - X-ray inspection device - Google Patents

Abstract

To provide an X-ray inspection device that can reduce the mass of the entire X-ray inspection device to reduce cost for shield material and transportation cost and reduce the floor withstand load of an installation location.SOLUTION: An X-ray inspection device comprises: an inspection table 1 on which an object to be inspected A is placed; an X-ray generator 2 that irradiates the object to be inspected A with an X-ray; and an X-ray detector 3 that is arranged opposite to the X-ray generator 2. The X-ray inspection device comprises: a first shield chamber 4 that is provided on the periphery of the inspection table 1, X-ray generator 2, and X-ray detector 3, and blocks the X-ray; a second shield chamber 5 that is provided inside the first shield chamber 4 and on the periphery of the X-ray generator 2, and block the X-ray; and a shield plate 6 that is provided inside the first shield chamber 4 and on the back of the X-ray generator 3, and blocks the X-ray from the X-ray generator 2.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to an X-ray inspection apparatus.

In recent years, industrial X-ray inspection apparatuses that inspect small electronic components such as lithium ion batteries and semiconductor devices with high resolution have been widely used. In this X-ray inspection apparatus, an X-ray generator that irradiates X-rays and an X-ray detector that has a two-dimensional pixel array that detects X-rays are arranged facing each other. A rotatable examination table is provided between the X-ray source and the X-ray detector. While the object to be inspected placed on the inspection table is being irradiated with X-rays, the inspection table rotates once, and the object to be inspected is irradiated with X-rays in all directions. A tomographic image can be obtained by reconstructing a set of fluoroscopic images collected by the X-ray generator from hundreds to thousands of X-ray irradiation directions during one rotation. Recently, cone beam CT (CBCT), which can obtain hundreds to thousands of tomographic images in one scan, is often used.

Industrial X-ray inspection equipment has an inspection room surrounded by a shield made of lead or the like to prevent X-rays harmful to the human body from leaking outside the equipment. If the X-ray generator is exposed inside this X-ray inspection device, the X-rays leaking from the X-ray generator itself must be shielded in the X-ray inspection room, so the shielding in the X-ray inspection room is thick. This resulted in an increase in the mass of the entire device.

Therefore, Prior Art 1 discloses an X-ray shielding means that not only shields the X-ray examination room but also shields the X-rays emitted from the X-ray generator into the X-ray examination room.

Japanese Patent Application Publication No. 5-264476

However, in Prior Art 1, since X-rays are irradiated with the shutter of the X-ray shielding means open, it is not possible to attenuate the direct X-rays irradiated from the X-ray generator. Therefore, there still remains the problem that the shielding material in the X-ray examination room becomes thicker and the mass of the entire X-ray examination apparatus increases.

Embodiments of the present invention have been made to solve the above problems, and the purpose is to reduce the mass of the entire X-ray inspection device, thereby reducing shielding material costs and transportation costs, and reducing the installation location. An object of the present invention is to provide an X-ray inspection device that can reduce the floor load capacity.

The X-ray inspection apparatus of the embodiment has the following configuration.
(1) An inspection table on which the object to be inspected is placed.
(2) An X-ray generator that irradiates the object to be inspected with X-rays.
(3) An X-ray detector placed opposite the X-ray generator.
(4) A first shielding chamber provided around the examination table, the X-ray generator, and the X-ray detector to shield the X-rays.
(5) A second shielding chamber provided inside the first shielding chamber and around the X-ray generator to shield the X-rays.
(6) A shielding plate provided inside the first shielding chamber and on the back surface of the X-ray detector to shield the X-rays from the X-ray generator.

The X-ray inspection apparatus of the embodiment may further include the following configuration.
(1) An opening narrower than the irradiation width of the X-rays irradiated from the X-ray generator is provided in the front wall of the second shielding chamber.
(2) A collimator is installed in the opening.
(3) The X-ray generator includes a movement mechanism that adjusts the distance to the object to be inspected.
(4) The X-ray generator includes an angle adjustment mechanism that adjusts the irradiation angle of the X-rays.
(5) The second shielded room is provided with a heat exhaust fan that exhausts heat generated from the X-ray generator.

FIG. 1 is a sectional view showing the overall configuration of an X-ray inspection apparatus according to the present embodiment. It is a top view showing the size and wall thickness of the 1st shielding room and the 2nd shielding room of this embodiment. FIG. 1 is a sectional view showing the overall configuration of a conventional X-ray inspection apparatus. FIG. 2 is a plan view showing the size and wall thickness of a first shielded chamber of the prior art.

[1. composition]
An X-ray inspection apparatus 100 according to a first embodiment will be described below with reference to FIG. 1. The X-ray inspection apparatus 100 of the first embodiment is an X-ray inspection apparatus that has an industrial cone beam CT (CBCT) function that inspects small electronic parts such as lithium ion batteries and semiconductor devices to cast parts with high resolution. be.

The X-ray inspection apparatus 100 is an apparatus used for non-destructive inspection of an object A to be inspected. The X-ray inspection apparatus 100 irradiates the periphery of the object A with an X-ray beam that passes through the object A, and detects the amount of X-rays attenuated by passing through the object A. A CT image, which is a cross-sectional image of the inspection object A, is generated based on this detection result. The X-ray inspection apparatus 100 generates a 3D image from a plurality of generated CT images.

As shown in FIG. 1, such an X-ray inspection apparatus 100 includes an examination table 1, an X-ray generator 2, an X-ray detector 3, a first shielding chamber 4, a second shielding chamber 5, and a shielding plate 6. . The inspection table 1 is a table having a mounting surface on which the object to be inspected A is placed. The inspection table 1 is movable in a direction parallel to or perpendicular to the mounting surface. Furthermore, the inspection table 1 is rotatable around a direction perpendicular to the mounting surface. The inspection table 1 has a sample table, and may have a rotation/elevating mechanism (not shown) inside or below the sample table.

The specimen A is placed on the specimen table. The sample table is configured with an actuator including a drive source such as a motor, and is rotatable about a direction perpendicular to the mounting surface. While the X-ray beam is being irradiated, this sample table rotates, so that the object A to be inspected is irradiated with the X-ray beam in all directions.

The rotation/elevating mechanism is provided inside or under the sample table, and can use, for example, a ball screw mechanism driven by a servo motor. The rotation/elevating mechanism is movable in a direction perpendicular to the mounting surface of the examination table 1. That is, the height of the mounting surface can be adjusted by moving the rotating/elevating mechanism in a direction perpendicular to the mounting surface. By adjusting the height of the mounting surface, it becomes possible to align the optical axis Id of the X-rays with the center of the object to be inspected A or with the user's arbitrary position. Moreover, the rotation/elevating mechanism is rotatable with a rotation axis in a direction perpendicular to the mounting surface.

The X-ray generator 2 irradiates an X-ray beam that passes through the object A to be inspected. The X-ray beam is a bundle of X-rays that has a focal point P of the X-ray generator 2 as its apex and spreads out in a conical shape with a cone angle. In this embodiment, the X-ray generator 2 is, for example, a reflective or transmissive microfocus X-ray tube, and generates an X-ray beam. Note that not only X-rays but also γ-rays that transmit through the inspection object A can be used.

The X-ray generator 2 has a movement mechanism that adjusts the distance to the object A to be inspected. The moving mechanism moves in the xyz-axis directions with respect to the optical axis Id of the X-rays so that the inspection object A is irradiated with X-rays only in the minimum necessary range from the opening 52 of the second shielding chamber 5, which will be described later. It is possible. The positional relationship between the second shielding chamber 5 and the X-ray generator 2 is adjusted by the movement mechanism of the X-ray generator 2 . The X-ray generator 2 may include an angle adjustment mechanism that adjusts the irradiation angle of X-rays.

The X-ray detector 3 is provided opposite the X-ray generator 2 with the examination table 1 and the object A to be inspected in between, and detects a two-dimensional distribution of X-ray intensity that is attenuated according to the transmission path of the X-rays. , outputs a perspective image to a control unit (not shown). The X-ray detector 3 has an imaging area with a two-dimensional pixel array, and is configured by, for example, a flat panel detector (FPD). The X-ray detector 3 is installed so that the center of the imaging region coincides with the optical axis Id of the X-ray generator 2.

The first shielding chamber 4 is provided around the examination table 1, the X-ray generator 2, and the X-ray detector 3, and shields X-rays. The first shielding chamber 4 is bottomless box-shaped and has four side walls and a ceiling. A first shield 41 made of lead or a material containing lead is disposed on the four side walls and the inner wall of the ceiling in the first shield chamber 4 . The first shield 41 shields X-rays generated from the X-ray generator 2 from leaking to the outside of the first shielding chamber 4 .

The second shielding chamber 5 is provided inside the first shielding chamber 4 and around the X-ray generator 2, and shields X-rays. The second shielded room 5 is box-shaped with a bottom and has four side walls, a ceiling, and a floor. A second shield 51 made of lead or a material containing lead is arranged on the inner walls of the four side walls, the ceiling, and the floor of the second shield room 5. Note that the second shielding object 51 may also serve as the four side walls, the ceiling, and the floor of the second shielding chamber 5. The second shield 51 prevents X-rays generated from the X-ray generator 2 from leaking to the outside of the second shield chamber 5.

A circular opening 52 that is narrower than the irradiation width of the X-rays emitted from the X-ray generator 2 is provided in the front wall 51 a of the second shielding chamber 5 . A circular collimator is installed in the opening 52. In this specification, regarding the side walls of the second shielding chamber 5, the side to which the X-ray beam is irradiated from the X-ray generator 2 is referred to as the front wall 51a, and the opposite side is referred to as the rear wall 51b.

A heat exhaust fan 53 is provided on the ceiling of the second shielded room 5 to exhaust heat generated from the X-ray generator 2. A labyrinth structure 54 is provided outside the heat exhaust fan 53. The labyrinth structure 54 is made of lead or a material containing lead, and prevents the X-rays generated from the X-ray generator 2 from leaking to the outside of the second shielding chamber 5, as well as preventing the exhaust from inside the second shielding chamber 5. It is a flow path.

The shielding plate 6 is provided inside the first shielding chamber 4 and on the back side of the X-ray detector 3 to shield X-rays from the X-ray generator 2 . The shielding plate 6 is a rectangular plate-shaped member, and is made of lead or a material containing lead. In this specification, the side of the X-ray detector 3 that detects the X-rays emitted from the X-ray generator 2 is referred to as the front side, and the opposite side is referred to as the back side. The shielding plate 6 preferably has a surface wider than the irradiation width of the X-rays reaching the X-ray detector 3 in order to attenuate the direct X-rays irradiated from the X-ray generator 2 . Although the method of fixing the shielding plate 6 does not matter, in this embodiment, it is fixed to the side surface of the pedestal of the X-ray detector 3.

[2. Example]
An example of the X-ray inspection apparatus 100 of the first embodiment having the above configuration will be described with reference to FIGS. 1 to 4. Below, the thickness of the first shield 41 and the second shield 51 on the back side of the X-ray generator 2 will be explained as an example.

3 and 4 show a conventional X-ray inspection apparatus 100 without the second shielding chamber 5. FIG. The tube voltage of the X-ray generator 2 is 450 kV, and the material of the first shield 41 is lead (density ρ 11.36 g/cm ³ ). As shown in FIGS. 3 and 4, the first shield 41 has a height (H) of 2500 mm, a width (D) of 2000 mm, and a distance from the X-ray generator 2 to the first shield 41 of 500 mm.

Assuming that the X-ray leakage ray IO from the X-ray generator 2 itself is the thickness tp of the first shield 41, the mass of the wall shield in the X-ray inspection apparatus 100 is calculated.

In the standard (JIS Z4606) for tube voltages of 200 kV or higher for non-medical applications, the X-ray leakage IO from the X-ray generator 2 is defined as 4.3 mGy/h (unit: absorbed dose). In this example, the allowable leakage line I' from the first shielding room 4 determined based on the Ionizing Radiation Hazard Prevention Regulations (ITC) standard (1.3 mSv/3 months) is set at 2 μSv/h (unit: equivalent dose). The conversion coefficient k of the equivalent dose from the absorbed dose of X-rays is assumed to be 1.26Sv/Gy. The allowable leakage line from the first shielding chamber 4 is 0.00252 mGy/h based on I=I'×k. The linear absorption coefficient μ of lead is 0.304 mm ⁻¹ . When the lead thickness is calculated as tp=1/μ·In(IO/(I·L ² )) under these conditions, it becomes 29.04 mm.

When the wall surface of the first shielding chamber 4 is constructed with this thickness of lead, the mass of the shielding material is 1649.5 kg (Wa=tp×H×D/10 ^{6 )} .

On the other hand, FIGS. 1 and 2 show an X-ray inspection apparatus 100 of this embodiment in which a second shielding chamber 5 is provided. The tube voltage of the X-ray generator 2 is 450 kV, and the material of the first shield 41 and the second shield 51 is lead (density ρ 11.36 g/cm ³ ). As shown in FIGS. 1 and 2, the first shield 41 has a height (H) of 2500 mm and a width (D) of 2000 mm, and the second shield 51 has a height (H) of 900 mm, a width (D) of 500 mm, and an X-ray The distance from the generator 2 to the second shield 51 is 250 mm, and the distance from the second shield 51 to the first shield 41 is 250 mm.

X-ray leakage ray IO from the X-ray generator 2 itself, X-ray leakage ray I2 from the second shielding chamber, X-ray leakage ray I1 from the first shielding chamber, thickness tp2 of the shielding material in the second shielding chamber, Assuming that the thickness of the shield on the back side of the X-ray generator in the first shield room is tp1, the masses of the first shield 41 and the second shield 51 in the X-ray inspection apparatus 100 are calculated.

First, the mass of the second shield 51 is calculated. The X-ray leakage IO from the X-ray generator 2 is specified as 4.3 mGy/h. In this embodiment, the allowable leakage line I2' from the second shielding chamber 5 is provisionally set at 5 μSv/h. The conversion coefficient k of the equivalent dose from the absorbed dose of X-rays is assumed to be 1.26Sv/Gy. The allowable leakage line from the second shielding chamber 5 is 0.00630 mGy/h based on I2=I2'×k. The linear absorption coefficient μ of lead is 0.304 mm ⁻¹ . When the lead thickness is calculated as tp2=1/μ·In(IO/(I2·L ² )) under these conditions, it becomes 30.59 mm.

When the wall surface of the second shielding chamber 5 is constructed with this thickness of lead, the mass of the second shielding member 51 is 156.4 kg, as W1=tp×H×D/10 ⁶ .

Next, the mass of the first shield 41 is calculated. As mentioned above, the X-ray leakage ray I2 from the second shielded room is defined as 0.006 mGy/h. In this embodiment, the permissible leakage line I' from the first shielding chamber 4 determined based on the Ionizing Radiation Hazard Prevention Regulations (ITC) standard (1.3 mSv/3 months) is set at 2 μSv/h. The conversion coefficient k of the equivalent dose from the absorbed dose of X-rays is assumed to be 1.26Sv/Gy. The allowable leakage line from the first shielding chamber 4 is 0.00252 mGy/h based on I1=I1'×k. The linear absorption coefficient μ of lead is 0.304 mm ⁻¹ . When the lead thickness is calculated as tp1=1/μ·In(IO/(I1·L ² )) under these conditions, it becomes 12.13 mm.

When the wall surface of the first shielding chamber 4 is constructed with this thickness of lead, the mass of the first shielding member 41 is 689.2 kg (W2=tp×H×D/10 ^{6 )} .

When the mass (W1) of the second shield 51 and the mass (W2) of the first shield 41 are combined, Wb=W1+W2 is 845.60 kg.

From the above, the difference in mass of the shielding object of the X-ray inspection apparatus 100 with and without the second shielding chamber 5 is 803.9 kg as W=Wa−Wb.

[3. effect]
The effects of this embodiment are as follows.
(1) The X-ray inspection apparatus 100 of this embodiment includes a first shielding chamber 4 and a second shielding chamber 5 that shield X-rays. This makes it possible to reduce the mass of the entire X-ray inspection apparatus 100, reduce shielding material costs and transportation costs, and reduce the floor load capacity of the installation location.

(2) The X-ray inspection apparatus 100 of this embodiment has the second shielding chamber 5 and the shielding plate 6, thereby reducing the mass of the first shielding object 41 of the first shielding chamber 4. This makes it possible to reduce the use of lead, which is the material of the first shield 41, and to reduce the environmental load when the X-ray inspection apparatus 100 is disposed of.

(3) The X-ray inspection apparatus 100 of this embodiment includes a shielding plate 6 that shields X-rays from the X-ray generator 2. Therefore, as shown in FIG. 1, by blocking X-rays with the thick second shield (tp2) of the second shield chamber 5 and the shield plate (tp3) on the back of the Since the first shields (tp1, tp4) can be made thinner, the weight of the device can be reduced. In particular, the shielding plate 6 makes it possible to attenuate the direct X-ray ray Id emitted from the X-ray generator 2 into the X-ray leakage ray I3 from the shielding plate 6, reducing the weight of the X-ray inspection apparatus 100. can be realized simply and easily.

(4) The X-ray generator 2 of this embodiment has a movement mechanism that adjusts the distance to the object A to be inspected and an angle adjustment mechanism that adjusts the irradiation angle of X-rays. Therefore, it is possible to irradiate the inspection object A with X-rays only in the minimum necessary range from the opening 52 of the second shielding chamber 5, and it is possible to obtain high quality images in the desired imaging area.

(5) The second shielded room 5 of this embodiment is provided with a heat exhaust fan 53 that exhausts heat generated from the X-ray generator 2. Therefore, even if the X-ray inspection device 100 is operated for a long time, it is possible to prevent the inside of the second shielded chamber 5 from becoming high temperature. 100% weight reduction can be achieved.

[4. Other embodiments]
Although a plurality of embodiments according to the present embodiment have been described in this specification, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

(1) In the above embodiment, the first shielding chamber 4 is box-shaped without a bottom, but it may be box-shaped with a bottom. By having a bottom, it is possible to block downward X-rays.

(2) In the above embodiment, the heat exhaust fan 53 for exhausting the heat generated from the X-ray generator 2 is provided on the ceiling of the second shielded room 5, but the installation of the heat exhaust fan 53 It may be provided on the back wall or side wall of the second shielding chamber 5, regardless of the location. Further, the number of heat exhaust fans 53 may not be one, but may be plural.

(3) Although the shielding plate 6 of the above embodiment is made of a rectangular plate-like member, the shape of the shielding plate 6 is not limited and may be circular. In addition, the shielding plate 6 of the above embodiment is fixed to the side surface of the mount of the X-ray detector 3, but the shielding range is adjusted according to the irradiation position of the direct X-ray irradiated from the X-ray generator 2. It may have a moving mechanism for adjustment.

100 X-ray inspection device 1 Examination table 2 X-ray generator 3 X-ray detector 4 First shielding chamber 41 First shielding object 5 Second shielding chamber 51 Second shielding object 52 Opening part 53 Heat exhaust fan 54 Maze structure part 6 Shielding plate A Test object P Focus I1 X-ray leakage rays from the first shielding chamber
I2 X-ray leakage ray I3 from the second shielding room X-ray leakage ray IO from the shielding plate 6 X-ray leakage ray Id from the X-ray generator itself X-ray from the X-ray generator (direct ray)
tp Thickness of the shield tp1, tp4 Thickness of the shield on the back of the X-ray generator in the first shield room tp2 Thickness of the shield in the second shield room tp3 Shield plate on the back of the X-ray detector 3

Claims (6)

an inspection table on which the object to be inspected is placed;
an X-ray generator that irradiates the object to be inspected with X-rays;
an X-ray detector arranged opposite to the X-ray generator;
a first shielding chamber provided around the examination table, the X-ray generator, and the X-ray detector to shield the X-rays;
a second shielding chamber provided inside the first shielding chamber and around the X-ray generator and shielding the X-rays;
a shielding plate provided inside the first shielding chamber and on the back side of the X-ray detector and shielding the X-rays from the X-ray generator;
An X-ray inspection device equipped with. The X-ray inspection apparatus according to claim 1, wherein the front wall of the second shielding chamber is provided with an opening narrower than an irradiation width of the X-rays irradiated from the X-ray generator. The X-ray inspection apparatus according to claim 2, wherein a collimator is installed in the opening. The X-ray inspection apparatus according to any one of claims 1 to 3, wherein the X-ray generator includes a movement mechanism that adjusts a distance from the object to be inspected. The X-ray inspection apparatus according to claim 4, wherein the X-ray generator includes an angle adjustment mechanism that adjusts the irradiation angle of the X-rays. The X-ray inspection apparatus according to any one of claims 1 to 3, wherein the second shielded room is provided with a heat exhaust fan that exhausts heat generated from the X-ray generator.