JP2007064727A - X-ray inspection device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray inspection device and a method capable of identifying a material of an inspected object, using a small number of inexpensive X-ray generators and X-ray detectors, and capable of reducing thereby a size and a cost of the device. <P>SOLUTION: The device includes the X-ray generators 12 for generating an X-ray 3 with an output fluctuated at a fixed time period T between the prescribed maximum output I<SB>max</SB>and the minimum output I<SB>min</SB>, X-ray irradiation devices 14 for irradiating the inspected object 1 with the X-ray, the X-ray detectors 16 for detecting the intensity of the X-ray transmitted through the inspected object, and controllers 18 for the X-ray generators and the X-ray detectors. The controller 18 detects an X-ray intensity I<SB>1</SB>at a high output time and an X-ray intensity I<SB>2</SB>at a low output time detected by the X-ray detector 16, at the high output time and the low output time in the X-ray outputs generated by the X-ray generator 12, and identifies the material of the inspected object. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus and an X-ray inspection method having a material identification function of an inspection object.

Conventionally, X-ray inspection equipment that detects X-ray intensity distribution of transmitted X-rays and detects internal dangerous objects (firearms, etc.) in inspection of baggage at customs and airports has been widely used. It has been.
In recent years, X-ray inspection apparatuses that can identify not only metals such as firearms but also dangerous materials such as explosives and poisons are known (for example, Non-Patent Document 1).

  The X-ray inspection apparatus of Non-Patent Document 1 uses, for example, two types of pulse X-rays of 75 kVp and 150 kVp. To identify.

X-ray is an electromagnetic wave having a wavelength of about of about ^{0.01~100Å (10- 12 ~10- 8 m)} , these X-rays shorter in wavelength (λ = 0.01~1Å) hard X-rays, the wavelength Long X-rays (λ = 1 to 100Å) are called soft X-rays.

  An X-ray tube is widely known as an X-ray generation source. An X-ray tube is an apparatus that generates X-rays by accelerating thermoelectrons obtained by heating a filament in a vacuum at a high voltage to collide with a metal anode (target).

  On the other hand, X-ray detectors for detecting X-ray intensity and images are proportional counters using gas ionization, scintillation counters using solid fluorescence, and semiconductor detectors using solid semiconductor ionization. , Etc. are conventionally known.

  As related prior art, for example, Patent Documents 1 to 3 have already been disclosed.

L-3 Communications Security and Detection Systems, Automated Screening Systems, Internet <URL: http: // www. dsxray. com / ProductCategoryDetails. asp? CatID = 7>

Japanese Patent Laid-Open No. 10-104175, “Material Specific X-ray Inspection Device” JP 2003-279503 A, "X-ray inspection apparatus" JP-A-8-201316, "X-ray elemental analyzer"

  In order to identify organic substances, non-organic substances, and metals, conventionally, for example, two types of pulse X-rays need to be used as disclosed in Non-Patent Document 1. In addition, in order to inspect the entire surface of baggage or the like with high accuracy, it is necessary to alternately switch two kinds of pulse X-rays in a short time. Therefore, such a pulse X-ray generator has a problem of being large and expensive.

In order to solve this problem, as in Patent Document 1, two sets of X-ray generators and X-ray detectors are used, one X-ray tube is irradiated with high-power X-rays, and then the other X-ray is irradiated. It is also possible to irradiate low-power X-rays with a ray tube and identify the material of the inspection object from the intensity distribution of each X-ray image.
However, in the case of this means, there is a problem that it is difficult to accurately match the positions of two X-ray images because the time and place are different. In addition, this means requires two sets of X-ray generators and X-ray detectors, and is still expensive.

Further, as in Patent Document 2, two X-ray detectors that irradiate X-rays having a wide wavelength region with a single X-ray generator and pass X-rays that pass through the object to be inspected with a filter interposed therebetween. And the material of the object to be inspected can be identified from the intensity distribution of each X-ray image.
In the case of this means, the two X-ray images are taken at the same time and place since the time and place are the same. However, this method requires only one X-ray generator, but two X-ray detectors are required, and a special filter that cuts a specific wavelength of X-rays is required between them. is there.

  Further, in Patent Document 3, a single X-ray generator and a single X-ray detector are used to perform elemental analysis of an object to be inspected by an X-ray image processing apparatus. There is a problem that is complicated.

  In order to inspect the entire surface of baggage etc. with high accuracy in baggage inspection at customs and airports, an X-ray detector that detects X-rays that have passed through the inspection object has a very small pitch (for example, about 1 to 2 mm). ) Need to have a large number of detection cells (or detection channels) arranged in a straight line. Therefore, such a multi-channel X-ray detector is expensive, and it has been desired that the required number can be reduced as much as possible (preferably only one).

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to easily identify the material of an object to be inspected by using an inexpensive and a small number of X-ray generators and X-ray detectors, thereby making the apparatus compact and inexpensive. An object is to provide an inspection apparatus and an X-ray inspection method.

According to the present invention, an X-ray generator that continuously generates X-rays whose output fluctuates at a constant time period T between a predetermined maximum output and a minimum output;
An X-ray irradiation apparatus for irradiating the inspection object with the X-ray;
An X-ray detector for detecting the intensity of X-rays transmitted through the inspection object;
A control device for controlling the X-ray generator and the X-ray detector;
The control device is configured to detect the X-ray intensity I ₁ at the high output and the X-ray intensity I at the low output detected by the X-ray detector when the X-ray output generated by the X-ray generator is high and low. _The X-ray inspection apparatus is characterized in that the material of the inspection object is identified from ₂ .

According to a preferred embodiment of the present invention, the X-ray generator includes an X-ray tube that generates X-rays by accelerating the thermal electrons with an applied voltage and colliding with the anode;
And a variable voltage device that generates the applied voltage that fluctuates at a constant time period T.

  The output fluctuation of the X-ray generator is sinusoidal or rectangular.

The X-ray irradiation device is a linear irradiation device that linearly irradiates an inspection object with X-rays,
The X-ray detector is preferably a linear detector that detects the intensity of linear X-rays that have passed through the inspection object.

  The linear detector includes a plurality of scintillators arranged linearly adjacent to each other, a plurality of photodiodes for detecting light emission by X-rays of each scintillator, and current outputs of the photodiodes as voltage signals, respectively. It is preferable to have a plurality of current-voltage conversion amplifiers that convert and amplify the signals and a plurality of A / D converters that respectively convert the converted voltage signals into digital signals.

The control device classifies the material of the inspection object by the equivalent atomic number from the detected X-ray intensity I ₁ at the time of high output and X-ray intensity I ₂ at the time of low output, and outputs the result.

  It is preferable that the control device includes a display device that displays an image of the X-ray intensity transmitted through the object to be examined, and that the equivalent atomic number classification is colored and displayed on the image.

According to the present invention, an X-ray generation step of continuously generating X-rays whose output fluctuates at a constant time period T between a predetermined maximum output and a minimum output;
An X-ray irradiation step of irradiating the inspection object with the X-ray;
An X-ray detection step of detecting an X-ray intensity I ₁ at the time of high output and an X-ray intensity I ₂ at the time of low output at the time of high output and low output of the X-ray output;
A material identification step of identifying the material of the object to be inspected from the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output, and the respective steps are processed in real time. An X-ray inspection method is provided.

According to a preferred embodiment of the present invention, in the X-ray generation step, the X-ray tube voltage is changed in a sinusoidal shape,
In the X-ray detection process, data is collected at two high energy points and two low energy points during one cycle of the sine wave.

According to the apparatus and method of the present invention, the X-ray generator continuously generates X-rays whose output fluctuates at a constant time period T between a predetermined maximum output and a minimum output. Since the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output at the time of high output and low output of the line output are detected, a single X-ray generator and single unit Using one X-ray detector, the material of the inspection object can be identified from the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

First, the principle of the present invention will be described.
FIG. 1 is a schematic diagram of an X-ray tube which is a kind of X-ray generator. As shown in this figure, X-rays are generated when thermoelectrons obtained by heating a filament in vacuum are accelerated at a high voltage and collide with an anode (target).
X-rays generated from the X-ray tube are composed of continuous X-rays due to bremsstrahlung of electrons and characteristic X-rays that are emission line spectra. Characteristic X-rays are used for applications that require X-rays of a specific wavelength.
As an anode material for continuous X-rays, tungsten having a high atomic number and a high melting point is suitable.

  FIG. 2 is an intensity distribution of continuous X-rays whose anode is tungsten. In this figure, the horizontal axis represents the wavelength, the vertical axis represents the X-ray intensity, and the numbers in the figure represent the applied voltage of the X-ray tube. As can be seen from this figure, X-rays with shorter wavelengths are generated as the applied voltage of the X-ray tube is higher, and X-rays with longer wavelengths are generated as the applied voltage of the X-ray tube is lower.

The wavelength of the X-ray is about 0.01 to 100Å (10 ⁻¹² to 10 ⁻⁸ m), and the relationship of the formula (1) is established between the wavelength λ [Å] and the photon energy E [keV]. There is.
E = 12.4 / λ (1)
Therefore, there is a one-to-one correspondence between the wavelength λ [Ｖ] and the photon energy E [keV]. The photon energy E [keV] is substantially proportional to the voltage applied to the X-ray tube.

Further, the X-ray intensity I when X-rays pass through a substance with a distance x is expressed by the formula (2).
I = I ₀ exp (−μx) (2)
Here, I ₀ is the X-ray intensity before entering the material, and μ is an attenuation coefficient (or linear absorption coefficient).
It is known that the attenuation coefficient generally varies depending on the substance and the wavelength. For example, in the case of the same substance, as the wavelength becomes longer, the attenuation coefficient increases, so that the transmission becomes difficult. Conversely, as the wavelength becomes shorter, the attenuation coefficient decreases and the light easily transmits.

If the density is ρ, equation (2) can be rewritten as equation (3).
I = I ₀ exp (−μ / ρ) (ρx) (3)
This μ / ρ has a value peculiar to a substance and is small when the wavelength of X-rays is short and becomes large when the wavelength of X-rays is long, but generally has a discontinuous absorption edge in the middle rather than a continuous change. .

However, equation (4) is approximately established between the absorption edges.
μ / ρ = k × λ ³ × Z ³ (4)
Here, k is a constant and Z is an effective atomic number. From this equation, it can be seen that if the absorption edge is ignored for a fixed wavelength, the attenuation coefficient generally increases as the element becomes heavier, and X-rays are difficult to pass.

FIG. 3 is a principle view of the X-ray inspection apparatus of the present invention. In this figure, it is assumed that two types of X-rays having different wavelengths λ ₁ and λ ₂ are transmitted through a certain subject and the X-ray intensities I ₁ and I ₂ after passing are measured.
In this case, if the incident X-ray intensities I ₁₀ and I ₂₀ are known, μ ₁ and μ ₂ are determined from the equation (2), and the following equations (4a) and (4b) satisfying the above (4) are obtained.
μ ₁ / ρ = k × λ ₁ ³ × Z ³ (4a)
μ ₂ / ρ = k × λ ₂ ³ × Z ³ (4b)
The unknowns in the equations (4a) and (4b) are only ρ and Z of the substance, and ρ and Z of the substance can be obtained by solving these two equations.

In other words, the detected output level of transmitted X-rays by X-rays has a predetermined characteristic for each X-ray energy and for each element of the object with respect to the thickness of the object. The detection output level for an object varies depending on the energy of the irradiated X-rays. The detection output level when irradiated with high energy X-rays is Lh, and the detection output level when irradiated with low energy X-rays is L1 (<Lh). Become.
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 when the same element is used.
Therefore, the element of the object can be obtained by obtaining an element having the same thickness corresponding to the detection output level (Lh, Ll) transmitted through the object, and the material of the object contained in the object to be measured can be obtained. Can be sought.

  FIG. 4 is an overall configuration diagram showing an embodiment of the X-ray inspection apparatus of the present invention. In this figure, an X-ray inspection apparatus 10 of the present invention includes an X-ray generation apparatus 12, an X-ray irradiation apparatus 14, an X-ray detector 16, and a control apparatus 18. In this figure, 1 is an object to be inspected, and 2 is a conveyor for conveying the object to be inspected horizontally.

X-ray generator 12, with the predetermined maximum output I _max and the minimum output I _min, continuously generates X-rays 3 that varies the output at a constant time period T. The output fluctuation of the X-ray 3 is preferably sinusoidal or rectangular.
In this example, the X-ray generator 12 includes an X-ray tube 12a and a variable voltage device 12b. The X-ray tube 12a generates X-rays by accelerating thermoelectrons with an applied voltage and colliding with the anode. The variable voltage device 12b generates an applied voltage that fluctuates at a constant time period T. The applied voltage is preferably in the range of 22 to 160 kV, for example.
With this configuration, the applied voltage can be arbitrarily changed by the variable voltage device 12b, and the intensity of the X-ray generated in the X-ray tube 12a can be changed in a sine wave shape or a rectangular wave shape by the variable voltage.
Note that the present invention is not limited to this configuration, and other known X-ray generators can be used as long as X-rays whose output fluctuates at a constant time period T can be continuously generated.

The X-ray irradiation device 14 irradiates the inspection object 1 with X-rays 3 generated by the X-ray generation device 12.
In this example, the X-ray irradiation apparatus 14 is a linear irradiation apparatus that linearly irradiates the inspection object 1 with X-rays 3.
With this configuration, the inspection object 1 having a large area is conveyed by horizontally conveying the inspection object 1 on the conveyance conveyor 2 and simultaneously irradiating the X-ray 3 linearly in a direction crossing (for example, orthogonal) in the conveyance direction. Even so, the entire surface can be easily inspected.
In addition, this invention is not limited to this structure, You may irradiate only a part or whole of the to-be-inspected object 1 with an X-ray.

The X-ray detector 16 detects the intensity of X-rays that have passed through the inspection object 1.
In this example, the X-ray detector 16 is a linear detector that detects the intensity of linear X-rays that have passed through the inspection object 1.
In addition, the linear detector includes a plurality of scintillators arranged linearly adjacent to each other, a plurality of photodiodes for detecting light emission by X-rays of each scintillator, and a current output of each photodiode as a voltage signal. A plurality of current-voltage conversion amplifiers that convert and amplify, and a plurality of A / D converters that convert the converted voltage signals into digital signals, respectively.
With this configuration, the intensity distribution of the linear X-rays that have passed through the object to be inspected 1 is converted into a digital signal simultaneously by a plurality of scintillators, a plurality of current-voltage conversion amplifiers, a plurality of photodiodes, and a plurality of A / D converters. can do.

The present invention is not limited to this configuration, and may be a planar X-ray detector in which a large number of detectors are two-dimensionally arranged and a two-dimensional image can be captured at a time.
By using such a planar X-ray detector, an X-ray image transmitted through the inspection object 1 can be captured at a time.

  Further, the X-ray detector 16 may be a semiconductor detector using an ionization action of a solid semiconductor, a combination of a thin CsI film and a CCD, or the other.

The control device 18 controls the X-ray intensity I ₁ at the time of high output detected by the X-ray detector 16 and the X-ray intensity at the time of low output when the X-ray output generated by the X-ray generator 12 is high and low. identifying the material of the specimen 1 from the I ₂ Metropolitan.
In this example, the control device 18 classifies the material of the inspection object 1 by the equivalent atomic number from the detected X-ray intensity I ₁ at high output and X-ray intensity I ₂ at low output. Output.
Further, the control device 18 includes a display device 19 for displaying an image of the X-ray intensity transmitted through the object 1 to be displayed on the image by coloring the classification of equivalent atomic numbers.

  FIG. 5 is an operation explanatory diagram of the X-ray inspection apparatus of the present invention. This figure shows the time change of the applied voltage. A circle (●) in the figure indicates a data collection point detected by the X-ray detector.

When the X-ray tube voltage is changed in a sine wave shape, it is possible to technically easily realize that the frequency is as low as possible, and the durability of the X-ray tube can be improved.
In addition, since the sampling frequency of the data sampling system is limited, the method shown in FIG. 5 is effective to make both this condition and the above-described condition compatible.
F in the figure indicates the maximum collection frequency of the data collection system. Moreover, it is an example of high energy: 140 kV and low energy: 70 kV.
If two points of high energy and two points of low energy are collected during one cycle of the sine wave, the X-ray tube voltage is changed to a sine wave shape as compared with the case of collecting data at the high and low peaks of the tube voltage. The frequency can be reduced to ½.
Data collection is performed at a phase of 45 ° + (135 ° × n), n = 0.1, 2,..., And when the data collection frequency is f = 1 kHz, the frequency of the sine wave is F = f / 4 = 250 Hz. Become.

The means for identifying the material of the inspection object 1 from the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output detected by the X-ray detector 16 is the above-described formulas (4a) and (4b). Ρ and Z of the substance can be obtained by solving and the material can be identified from this.

As shown in FIG. 2, although the wavelength of continuous X-rays spreads in a certain distribution, the X-ray at the time of high output has a short wavelength at the maximum output, and the X-ray at the time of low output has a wavelength at the maximum output. Long wavelength.
Therefore, the approximate values of ρ and Z of the substance are obtained by solving the equations (4a) and (4b) with the X-ray wavelengths at the maximum output as μ ₁ and μ ₂ , respectively, and the material is identified by the equivalent atomic number from this. Can do. As μ ₁ and μ ₂ , instead of the X-ray wavelength at the maximum output, respective average values or arbitrarily set values may be used.

Moreover, this invention is not limited to Formula (4a) (4b), You may use another approximate formula.
Furthermore, for a certain wavelength, the attenuation coefficient generally increases as the element becomes heavier, and X-rays are less likely to pass through. For the same substance, the attenuation coefficient increases as the wavelength increases, making transmission difficult. On the other hand, it is known that the shorter the wavelength, the lower the attenuation coefficient and the easier the transmission.
Therefore, based on this characteristic, the relationship between the ratio I ₁ / I ₂ (or I ₁ / I ₂ ) of the detected X-ray intensities I ₁ and I ₂ and the equivalent atomic number is preliminarily tested to create a calibration curve or the like, This may be used to identify the equivalent atomic number or its classification.
Also, using the X-ray intensity I ₁₀ at the time of high output generated by the X-ray generator 12 and the X-ray intensity I ₂₀ at the time of low output, a similar calibration curve or the like is created and identified using these. Also good.

FIG. 6 is a flowchart showing the X-ray inspection method of the present invention. As shown in this figure, the method of the present invention comprises an X-ray generation step S1, an X-ray irradiation step S2, an X-ray detection step S3, and a material identification step S4.
In the X-ray generation step S1, the X-ray generation device 12 is used to continuously generate X-rays 3 whose output fluctuates at a constant time period T between a predetermined maximum output I _max and a minimum output I _min. To do. The output fluctuation of the X-ray 3 is preferably sinusoidal or rectangular.
In the X-ray irradiation step S2, the generated X-ray 3 is irradiated to the inspection object 1.
In the X-ray detecting step S3, the high output power and low output power of the irradiated X-rays, detects X-ray intensity I ₂ at the time of low output and the X-ray intensity I ₁ at the time of high output which has passed through the object to be inspected 1.
In the material identifying step S4, it identifies the material of the specimen 1 from the high output power of the X-ray intensity I ₁ and the low output of the X-ray intensity I ₂ Prefecture.
In addition, it is preferable that each process of said S1-S4 processes in real time within the fixed time period T, and repeats this.

Examples of the present invention will be described below.
FIG. 7 is an X-ray image showing an embodiment of the present invention. This image is an X-ray image when the travel bag is inspected using the apparatus shown in FIG. In this example, the detected X-ray intensities I ₁ and I ₂ are used to color-code (not shown) basically by equivalent atomic numbers, and those that may be dangerous materials are highlighted with a thick rectangle. it's shown.
Specifically, an equivalent atomic number of 10 or less is represented by an orange based hue as an organic substance, an equivalent atomic number of 20 or more is represented by an inorganic substance and a blue based hue, and an intermediate equivalent atomic number as an intermediate. It is represented by a hue based on green, and shows the difference between the equivalent atomic numbers. For example, the equivalent atomic number of explosives is 7-8 and is included in organic matter.

  FIG. 8 is another X-ray image showing an embodiment of the present invention. This image is an X-ray image when the tool box is similarly inspected. In this example as well, the internal contents are similarly identified and color-coded, and those that are potentially dangerous goods are highlighted in a thick rectangle.

As described above, according to the apparatus and method of the present invention, the X-ray generator 12 continuously applies the X-ray 3 whose output fluctuates between the predetermined maximum output and the minimum output at the constant time period T. The X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output that are transmitted through the inspection object 1 are detected at the time of high output and low output of the X-ray output. The X-ray generator and the single X-ray detector 16 can be used to identify the material of the inspection object 1 from the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output. .
In addition, since the target X-ray generator can be configured using the most popular inexpensive X-ray tube, the X-ray generator can be made small and inexpensive.

In addition, when the X-ray output fluctuates sinusoidally (sine curve), the wavelength of the X-ray measurement can be controlled by freely changing the high and low output measurement positions on the sine curve. It is possible to select and measure the wavelength at which dangerous substances (explosives, poisons, etc.) and specific substances can be detected most effectively.
Further, when the X-ray output is a rectangular wave, the X-ray wavelength has a constant value (μ ₁ , μ ₂ ), so that the ρ and Z of the substance can be accurately determined by solving the above-described equations (4a) and (4b). From this, the material can be identified more accurately.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is a schematic diagram of an X-ray tube. It is an intensity distribution of continuous X-rays whose anode is tungsten. It is a principle figure of the X-ray inspection apparatus of this invention. 1 is an overall configuration diagram showing an embodiment of an X-ray inspection apparatus of the present invention. It is operation | movement explanatory drawing of the X-ray inspection apparatus of this invention. It is a flowchart which shows the X-ray inspection method of this invention. It is an X-ray image which shows the Example of this invention. It is another X-ray image which shows the Example of this invention.

Explanation of symbols

1 Inspected object, 2 Conveyor, 3 X-ray,
10 X-ray inspection equipment, 12 X-ray generation equipment,
12a X-ray tube, 12b Fluctuating voltage device,
14 X-ray irradiation device, 16 X-ray detector,
18 control device, 19 display device

Claims (9)

An X-ray generator that continuously generates X-rays whose output fluctuates at a constant time period T between a predetermined maximum output and a minimum output;
An X-ray irradiation apparatus for irradiating the inspection object with the X-ray;
An X-ray detector for detecting the intensity of X-rays transmitted through the inspection object;
A control device for controlling the X-ray generator and the X-ray detector;
The control device is configured to detect the X-ray intensity I ₁ at the high output and the X-ray intensity I at the low output detected by the X-ray detector when the X-ray output generated by the X-ray generator is high and low. _2. An X-ray inspection apparatus characterized in that the material of the inspection object is identified from ₂ . The X-ray generator includes an X-ray tube that accelerates thermal electrons with an applied voltage and collides with an anode to generate X-rays;
The X-ray inspection apparatus according to claim 1, further comprising: a variable voltage device that generates the applied voltage that fluctuates at a constant time period T.   The X-ray inspection apparatus according to claim 1, wherein the output fluctuation of the X-ray generation apparatus is a sine wave shape or a rectangular wave shape. The X-ray irradiation device is a linear irradiation device that linearly irradiates an inspection object with X-rays,
The X-ray inspection apparatus according to claim 1, wherein the X-ray detector is a linear detector that detects the intensity of linear X-rays that have passed through the inspection object.   The linear detector includes a plurality of scintillators arranged linearly adjacent to each other, a plurality of photodiodes for detecting light emission by X-rays of each scintillator, and a current output of each photodiode converted into a voltage signal, respectively. The X-ray inspection apparatus according to claim 4, further comprising: a plurality of current-voltage conversion amplifiers that amplify and a plurality of A / D converters that respectively convert the converted voltage signals into digital signals. The control device classifies the material of the inspection object by an equivalent atomic number based on the detected high-power X-ray intensity I ₁ and low-power X-ray intensity I _2, and outputs the result. The X-ray inspection apparatus according to claim 1.   The said control apparatus is equipped with the display apparatus which displays the image of the X-ray intensity which permeate | transmitted the to-be-inspected object, and colors the division of the said equivalent atomic number, and displays it on an image. X-ray inspection equipment. An X-ray generation step of continuously generating X-rays whose output fluctuates at a constant time period T between a predetermined maximum output and a minimum output;
An X-ray irradiation step of irradiating the inspection object with the X-ray;
An X-ray detection step of detecting an X-ray intensity I ₁ at the time of high output and an X-ray intensity I ₂ at the time of low output at the time of high output and low output of the X-ray output;
A material identification step of identifying the material of the object to be inspected from the X-ray intensity I ₁ at the time of high output and the X-ray intensity I ₂ at the time of low output, and each of the steps is processed in real time. X-ray inspection method. In the X-ray generation process, the X-ray tube voltage is changed in a sine wave shape,
9. The X-ray inspection method according to claim 8, wherein, in the X-ray detection step, data is collected at two points of high energy and two points of low energy during one cycle of the sine wave.

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