JPH10104175A - X-ray inspection apparatus for specifying material quality - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material quality specifying X-ray inspection apparatus capable of specifying an element of the object contained in an article to be measured to specific material quality. SOLUTION: Objects with known elements are irradiated with X-rays to calculate the characteristic data of the detection output of transmitting X-rays and the thickness of the object by the energy of irradiating X-rays and elements to store them in a characteristic data memory means (characteristic data memory 14). An article 4 to be measured is irradiated with two-X-rays different in energy from X-ray sources (first and second X-ray tubes 2h, 2l) and the transmitted X-rays to respective X-rays are detected by detectors (first and second line sensor X-ray tubes 6h, 6l) to calculate the detection output level. A material quality specifying means (image memory 12, operation and comparison circuit 13, control circuit 15) uses characteristics of the object corresponding to two detection output levels to calculate elements with equal thickness. From the equality of the thickness to the detection output level by different X-ray energies, the element of the object contained in the article to be measured is specified to specify the material quality of the article to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material specifying X-ray inspection apparatus for specifying a material of an inspection object by detecting transmitted X-rays.

[0002]

2. Description of the Related Art Conventionally, nondestructive inspection using an X-ray inspection apparatus has been performed in various fields. The X-ray inspection apparatus irradiates an object to be measured with X-rays from an X-ray source and transmits X-rays through the object to be measured.
This is to generate a transmission image by detecting a line. This enables inspections at airports, post offices, military industries, courts, etc. for the presence of controlled objects such as guns and guns, inspections of welds for cracks and defects at factories, and inspections of foreign substances in foods and pharmaceuticals. It can be carried out. Conventional X-ray inspection equipment
Using an X-ray source that emits a single energy, X-rays transmitted through an object to be measured are imaged and displayed by an X-ray line sensor.

[0003]

An image obtained by a conventional X-ray inspection apparatus that emits X-rays of a single energy is:
The display of the shape of the object to be measured and the light and shade display according to the degree of X-ray absorption are performed. FIG. 12 is an example of a display image by a conventional X-ray inspection apparatus. In the display image of FIG.
In the case of the DUT 61 containing a heavy element such as a metal, the amount of X-ray absorption is large, so that the amount of transmission is reduced and displayed at a high output level. In the case of 63, since the amount of absorption of X-rays is small, the amount of transmission is increased and the image is displayed at a low output level. Therefore, the target object is predicted based on the shape of the displayed image and the shading of the display, but the target object cannot be specified for the measured object having no characteristic shape such as an explosive or a drug. There is a problem.

An X-ray inspection apparatus for simultaneously inspecting an object containing a heavy element and an object containing a light element by using X-rays having different energies has also been proposed. Is similar to the X-ray inspection apparatus described above in that an image obtained by X-rays of a single energy is obtained for an object by using single-energy X-rays. The problem of not being able to do so has not been solved.

Accordingly, the present invention solves the above-mentioned problems of the conventional X-ray inspection apparatus, and specifies an element of an object included in an object to be measured to specify a material.
It is an object to provide a line inspection device.

[0006]

A material specific X-ray inspection apparatus according to the present invention is an X-ray inspection apparatus for inspecting an object to be measured using transmitted X-rays, wherein at least two X-rays having different energies are measured. X-ray source for irradiating X-rays, detector for detecting X-rays transmitted through the object to be measured, and characteristic data of the detection output of transmitted X-rays and the thickness of the object for each energy and element of the irradiated X-rays Material specification for determining the material by determining from the characteristic data storage means an element having the same thickness of the object obtained for two detection outputs obtained by irradiation with X-rays having different energies. This makes it possible to specify the element of the object contained in the object, specify the material, and perform the inspection of the object whose shape cannot be specified.

FIG. 3 is a diagram showing the relationship between the energy of X-rays emitted from the X-ray source and the relative X-ray flux. 120KV, 1m
When an X-ray source is composed of two X-ray tubes, a first X-ray tube of A and a second X-ray tube of 60 KV, 4 mA, as shown in FIG. 3, X-ray energies of 120 KeV and 60 KeV are obtained from each X-ray tube. An X-ray flux having an energy width above and below the center is irradiated.

The detection output level of the transmitted X-ray by the X-ray shows a predetermined characteristic with respect to the thickness of the target object for each energy of the X-ray and each element of the target object. FIG. 4 shows the detected output level-thickness characteristic, and FIG. 5 shows the detected output level when the same object is irradiated with X-rays having different energies. The detection output level for an object having the same element and the same thickness differs depending on the energy of the irradiated X-ray. The detection output level when irradiating high energy X-ray is Lh, and the detection output level when irradiating low energy X-ray. Is Ll (<Lh).

[0009] This characteristic differs for each element, and when the thickness corresponding to the detected output level is obtained, the same thickness can be obtained for different energy X-rays only for the same element. Therefore, in FIGS. 5B and 5C, FIG.
(A) Detection output level (Lh, Ll) transmitted through the object 4
The element of the object can be obtained by obtaining the element having the same thickness corresponding to, and the material of the object included in the measured object can be obtained.

In order to inspect whether or not an object is included in an object to be measured by the material specifying X-ray inspection apparatus of the present invention,
The process of irradiating an object with a known element in advance with X-rays and obtaining the detection output characteristics with respect to the thickness of the transmitted X-rays by varying the energy of the X-rays allows the detection output of the transmitted X-rays and the object to be obtained. Characteristic data with respect to the energy and the element of the irradiated X-rays and store them as characteristic data.

Then, the object is irradiated with two X-rays having different energies from an X-ray source, and each X-ray is irradiated.
X-rays transmitted through the X-rays are detected by a detector to obtain a detection output level. The material specifying means obtains the thickness of the object corresponding to the two detected output levels using the obtained characteristic data, and obtains an element having the same thickness. When the thicknesses corresponding to the detection output levels due to different X-ray energies match, the element of the characteristic data is the element of the object included in the object, and the material of the object is specified.

According to a first embodiment of the present invention, two X-ray tubes having different irradiation energies are arranged in an X-ray source along a direction of relative movement between an object to be measured and the X-ray source. Makes the irradiated X-rays incident on the detector without interfering with each other, whereby a scanning image of two X-ray energies can be obtained. Further, a second embodiment of the present invention is a method of
An X-ray apparatus of a grid control type is arranged as a radiation source, and high and low tube voltages are switched in a short time by grid control to alternately emit X-rays having different energies.
It irradiates a detector provided with a three-dimensional television camera, whereby a still image of two X-ray energies can be obtained.

According to a third embodiment of the present invention, a detector for obtaining a scanning image is two photodiode arrays with phosphors for collecting X-ray energy images, and an X-ray beam from an X-ray source is received by the photodiode array. This is provided with a stop means limited to a surface, whereby the two photodiode arrays can be irradiated with X-ray beams having different energies without interference.

According to a fourth embodiment of the present invention, the material specifying means is provided with a means for obtaining a detection output level of X-rays transmitted through the object, and the means identifies the object on an X-ray energy image. Means for specifying, a means for extracting an outline of the object based on the specification, a means for specifying a background portion near the object, and a method for subtracting pixel data of the background from pixel data in the object. And a means for obtaining data unique to the object. With this configuration, it is possible to obtain data unique to the object by removing an error in the background portion of the X-ray transmitted through the object.

The fifth embodiment of the present invention comprises display means for displaying the object with a specific brightness or color tone for each of the obtained elements, whereby the material of the object to be measured can be distinguished and displayed. .

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram for explaining an outline of a material specifying X-ray inspection apparatus according to the present invention. In the schematic block diagram of FIG. 1, a material specifying X-ray inspection apparatus 1 includes a first X-ray tube 2h and a second X-ray tube 21 for irradiating an object 4 with an X-ray beam, and a first X-ray tube 2h.
Line sensor 6 for detecting transmitted X-rays emitted from
h and the second line sensor 61 detecting the transmitted X-rays emitted from the second X-ray tube 2l, and the characteristic data of the detection output of the transmitted X-rays and the thickness of the target object by energy and element of the irradiated X-rays. There is provided a stored characteristic data memory 14 and material specifying means for specifying the material of the DUT based on data read from the characteristic data storage memory 14.

The X-ray tube 2 is configured to irradiate X-rays of different energies. The first X-ray tube 2h irradiates high X-ray energy and the second X-ray tube 21 irradiates low X-ray energy. And For example, the first X-ray tube 2h has 120
A configuration in which a continuous X-ray of 120 KeV is irradiated using an X-ray tube of KV and 1 mA, and a continuous X-ray of 60 KeV is irradiated to the second X-ray tube 2l using an X-ray tube of 60 mA and 4 mA.

As the first line sensor 6h and the second line sensor 61, a photodiode array with a phosphor for collecting an X-ray energy image can be used. And converts the optical signal into an electric signal to convert the signal into an image signal.
Send to The image processing circuit 11 performs signal processing for converting a one-dimensional signal from the line sensor into a two-dimensional image, and sends the image data to the first image memory 12h and the second image memory 12l, respectively, to store image data. As the image memory, for example, a VRAM or the like can be used. Image memory 1
The stored image data 2 can be displayed on the display device 18 by the display circuit 17 or output to the output device 19.

The material specifying means includes the image memory 12, an operation and comparison circuit 13, a control circuit 15, an input device 16, and the like. The calculation and comparison circuit 13 uses the image data and the characteristic data memory 14 stored in the image memory 12 to calculate and compare the thickness of the object in the measured object for each X-ray irradiation energy and each element. , A circuit for performing processing for obtaining an element having the same thickness. Control circuit 1
Reference numeral 5 denotes a circuit that performs data control of image data and characteristic data, control of a display circuit, and the like. Also, the input device 16
Is a device for designating a part for specifying the material in the object to be measured by the control circuit 15, and a pointing device such as a mouse can be used.

Each circuit configuration of the above-mentioned material specifying means conceptually shows the function of the material specifying means.
It can be configured by either hardware or software.

Further, the material-specifying X-ray inspection apparatus 1 is provided with a belt 5 for moving the object 4 to be measured, and irradiates the X-ray tube 2 and the line sensor 6 along the moving direction of the belt 5 with X-rays. A configuration in which a scanning image is obtained by arranging at a position where light is incident can be employed. At this time, the X-ray diaphragm 3 can be arranged between the X-ray tube 2 and the line sensor 6 to prevent interference of irradiated X-rays.

Next, the operation of the material specifying X-ray inspection apparatus of the present invention will be described with reference to the flowchart of FIG. First, before specifying the material of the DUT 4, the material specification X
The line inspection apparatus 1 obtains the detection output while changing the thickness of a plurality of elements, and stores the characteristic data obtained by obtaining the thickness-detection output characteristic for each element in the characteristic data memory 14 as a database (step S1).

Next, an X-ray image of the measured object 4 is obtained and displayed on the display device 18. To obtain an X-ray image as a scanning image, a transmitted X-ray image of X-rays emitted from the first X-ray tube
The transmission X-ray image detected by the line sensor 6h and X-rays emitted from the second X-ray tube 21 is detected by the second line sensor 61. The image processing circuit 11 converts a one-dimensional detection output obtained by each line sensor 6 into a two-dimensional signal, and stores the two-dimensional signal in the first image memory 12h and the second image memory 12h to obtain image data. The image data is displayed on the display device 18 via the display circuit 17 under the control of the control circuit 15.

FIG. 6 shows a display example of the display device. FIG.
(A) is an image example when irradiating high energy X-rays, and FIG. 6 (b) is an image example when irradiating low energy X-rays. The display of the container 22 and the object 23 of the light element in the container 22 is performed. In an image obtained by irradiation with low-energy X-rays, the outline of the image of the object 23 is unclear due to the container 22. Therefore, in order to perform the process of defining the shape of the object to be measured in step S3, a high energy X
The image obtained by the line is displayed (step S
2).

The image displayed on the display device 18 is observed, and feature points for defining the shape of the DUT 4 are input by the input device 16. FIG. 7 is a diagram illustrating input of a feature point. In FIG. 7, in order to define the shapes of the objects 21 and 23 displayed on the screen 20, feature points 31 and 3 are defined.
2 (x in the figure) and feature points 34 and 35 (x in the figure) are input (step S3). The control circuit 15
By using these feature points 31, 32, 34, and 35, the object 2
Rectangles 33 and 36 enclosing 1 and 23 are generated and displayed on the screen 20, and the outline of the device under test is extracted. Here,
Although the outline of the object to be measured is extracted by the rectangular shape based on the input of the two feature points, the outline approximated to the shape of the object to be measured can be extracted by the input of multiple points (step S4).

Next, in order to obtain the detection output of the transmitted X-ray of the object to be measured, the approximate points A, B,... Are specified in step S5, and the measurement points a, b,.
・ Make the settings. The designation of the approximate point is for obtaining the detection output of the transmitted X-ray in the background portion of the measured object, and is input by the input device 16 while observing the display screen. In FIG. 7, approximate points are indicated by stars 41 and 43 (step S).
5). The setting of the measurement point is for obtaining the detection output of the transmitted X-ray of the object to be measured.
The setting is performed based on the contour of the object to be measured extracted in step. FIG.
Inside, measurement points are indicated by triangles 42 and 44 (step S6).

The control circuit 15 obtains the detection outputs of the measurement points and the approximate points from the image memory 12. In this processing, the first image memory 12 h and the second image memory 12
1 can be read. Here, the detection output of the measurement point by the high energy X-ray is Lah,
Lbh,..., And the detection output of the approximate point is LAh, LBh,.
.., And the detection output of the measurement point by the low energy X-ray is Lal, Lbl,.
Al, LBl, ... (Step S7).

Next, a corrected detection output at the measurement point is obtained by using the detection output obtained in step S7. The detection outputs of the approximate points A, B, ... are measured points a, b, ...
Is the background output of the detected output, and is a noise component with respect to the detected output of only the target object. FIG. 8 is a diagram showing a detection output. FIG. 8A shows a detection output by a high energy X-ray, and FIG. 8B shows a detection output by a low energy X-ray. In FIG. 8, Lw is a white level output when there is no DUT, LBh and LBl are background outputs,
Lh and Ll are detection outputs, and the detection outputs Lh * and Ll * of only the object can be obtained as outputs obtained by subtracting the background outputs LBh and LBl from the detection outputs Lh and Ll.

Therefore, the detection outputs LA, LB,... Of the approximate points A, B,.
8), the background output is subtracted from the detection outputs La, Lb,... Of the measurement points a, b,. This operation is performed by the operation / comparison circuit 13.
The detection output can be performed by reading the detection output from the image memory 12 and performing a subtraction operation on the high energy X-rays and the low energy X-rays (steps S9 and S10).

Next, using the obtained corrected detection output,
The material of the target object is specified by the following steps S11 to S15. FIG. 9 is a diagram illustrating material identification using the thickness-detection output characteristics of each element. FIG. 9A shows the detection output characteristics with respect to the thickness of the element having the atomic number N1 with respect to the high-energy X-ray and the low-energy X-ray. Similarly, FIGS. 4 shows detection output characteristics of elements. In FIG. 9, the thicknesses Dh, Dl with respect to the detection outputs Lh *, Ll * obtained in the above steps are shown.
l, the thickness Dh, at atomic number N1, N2
Dl is different. The measured object thickness is high energy X
Since it is the same for the X-ray and the low-energy X-ray, it is understood that the elements of the measured object are not atomic numbers N1 and N2. Therefore, the atomic numbers Nn where the thicknesses Dh and Dl match
, The element of the target object can be specified.

The control circuit 15 reads the thickness-detection output characteristic from the characteristic data memory 14 (step S12),
The arithmetic and comparison circuit 13 calculates and compares the thicknesses Dh and Dl with respect to the detection outputs Lh * and Ll * (step S1).
3, 14), the atomic number N where the thicknesses Dh and Dl match (steps S11, S16, S16), and the material of the object is specified from the matching atomic number N (step S15).

The display device 18 can display the specified material with a specific brightness or color tone for each element, and thereby can display the material of the device under test in a distinguished manner. FIG. 10 shows an example of a display color when an element is displayed in a color tone. For example, light elements having atomic numbers 1 to 10 are displayed in red, atomic numbers 11 to 15 are green, and atomic numbers 1 are.
6 or more can be displayed in a color such as blue. Note that the division of the atomic number and the color tone are merely examples, and the present invention is not limited thereto.

Although the above-described embodiment shows the configuration and operation for obtaining a scanned image, a configuration for obtaining a still image may be adopted. FIG. 11 shows an example of a configuration for obtaining a still image of the material specific X-ray inspection apparatus according to the present invention. Only an X-ray source and a detector are shown, and other configurations are substantially the same as those in FIG.

In FIG. 11, an X-ray source is a grid-controlled triode X-ray tube 51 having a grid 52, and irradiates an X-ray beam 53 two-dimensionally to a detector. The detector is an X-ray luminance intensifier tube 54, an optical system 55, and a two-dimensional television camera 56. The triode X-ray tube 51 switches between high and low tube voltages in a short time by grid control, and irradiates the detector with high-energy X-rays and low-energy X-rays alternately. The detector receives transmitted X-rays from the X-ray beam and outputs a two-dimensional signal to obtain a still image.

[0035]

As described above, it is possible to provide a material specifying X-ray inspection apparatus capable of specifying the element of the object contained in the measured object and specifying the material.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an outline of a material specific X-ray inspection apparatus according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the material specifying X-ray inspection apparatus of the present invention.

FIG. 3 is a diagram showing a relationship between energy of X-rays emitted from an X-ray source and relative X-ray flux.

FIG. 4 is a characteristic diagram showing a detection output level-thickness characteristic.

FIG. 5 is a detection output diagram when the same object is irradiated with X-rays having different energies.

FIG. 6 is a display example of a display device.

FIG. 7 is a diagram illustrating input of a feature point.

FIG. 8 is a diagram showing a detection output.

FIG. 9 is a diagram illustrating material specification using the thickness-detection output characteristics of each element.

FIG. 10 is an example of a display color when an element is displayed in a color tone.

FIG. 11 is a configuration example for obtaining a still image of the material specifying X-ray inspection apparatus of the present invention.

FIG. 12 is an example of a display image by a conventional X-ray inspection apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Material specific X-ray inspection apparatus, 2h ... 1st X-ray tube, 2l ...
2nd X-ray tube, 3 ... X-ray aperture, 4 ... DUT, 5 ... Belt, 6h ... 1st line sensor, 6l ... 2nd line sensor, 11 ... Image processing circuit, 12h ... 1st image memory, 1
21: second image memory, 13: operation and comparison circuit, 14 ...
Characteristic data memory, 15: control circuit, 16: input device,
17 display circuit, 18 display device, 19 output device, 2
0: Screen, 21, 22, 23 ... Object, 31, 32, 3
4, 35 ... feature points, 33, 36 ... rectangles, 41, 43 ... approximation points, 42, 44 ... measurement points, 51 ... tripolar X-ray tube, 52 ...
Grid, 53: X-ray beam, 54: X-ray brightness intensifier,
55: Optical system, 56: Two-dimensional television camera.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanori Ota 1-3-3 Kandanishikicho, Chiyoda-ku, Tokyo Shimadzu Corporation Tokyo branch office

Claims (1)

[Claims] 1. An X-ray inspection apparatus for inspecting an object to be measured using transmitted X-rays, an X-ray source for irradiating the object with at least two X-rays having different energies, and an X-ray transmitted through the object to be measured. A detector for detecting X-rays; characteristic data storage means for storing characteristic data of the detection output of transmitted X-rays and the thickness of an object for each energy and each element of irradiation X-rays; Material specifying means for specifying a material by obtaining, from the characteristic data storing means, an element having the same thickness of the object obtained for the two detected outputs obtained. Line inspection equipment.