KR102140053B1 - Radiation inspection apparatus and radiation inspection method - Google Patents

Abstract

An object of the present invention is to provide a radiation inspection apparatus and a radiation inspection method capable of improving the detection accuracy of a vacancy or foreign object, regardless of the location of the vacancy or foreign object.
As a means for solving such a problem, the radiation inspection apparatus includes a radiation source 2 that irradiates radiation, a stage 4 that is located in the irradiation range of the radiation source 2, and is capable of placing the subject 1. , A detector 3 which is located on the opposite side to the radiation source 2 with the stage 4 interposed therebetween, and detects radiation transmitted through the subject 1, and two-dimensional of the subject 1 obtained from the detector 3 And a processing device 6 for imaging the perspective information of and a display device 7 for displaying an image obtained by the processing device 6. Then, the processing device 6 has a calculation unit 62 that calculates a ratio of two pieces of transmitted data having different positions of the subject 1 and generates a two-dimensional ratio image, and the display device (7) displays the non-image generated by the calculation unit 62.

Description

Radiation inspection device and radiation inspection method {RADIATION INSPECTION APPARATUS AND RADIATION INSPECTION METHOD}

An embodiment of the present invention relates to a radiation inspection apparatus that detects radiation transmitted through a subject and forms an image of the subject.

BACKGROUND ART A radiation inspection apparatus for performing a non-destructive inspection of a subject is known by irradiating the subject with radiation represented by X-rays, and detecting and imaging a two-dimensional distribution of attenuated radiation by passing through the subject. For example, a void, also called a void existing inside the subject, or foreign matter on the surface or inside of the subject can be found by the radiographic inspection apparatus.

However, the public or foreign matter is generally very small, and the contrast with the surroundings is low. For this reason, it is not easy to detect a public object or a foreign object by simply skimming a perspective image. Therefore, in order to improve the detection precision, a method using a differential image is known.

The difference image is an image obtained by taking a difference in pixel values between two perspective images taken by slightly shifting the position of the same subject. The pixel values representing the subject to be the background of the public or foreign matter are almost the same between the two perspective images. Therefore, in the differential image, the subject to be the background is canceled out, and a vacancy or a foreign object becomes an outstanding image. By referring to this differential image, the detection accuracy of vacancy and foreign matter is improved.

Japanese Patent No. 3545073

However, in the method using the differential image, it has been found that even if the same vacancy or foreign matter is present, the detection accuracy changes depending on where the subject is located. The reason is that if the thickness of the subject, i.e., the transmission distance of the radiation is different, the transmission distance of the subject to be the background changes, and the radiation transmission intensity of the thin portion and the thickness of the thick portion change. , Because the influence is reflected in the difference image. Particularly, when a void or a foreign body is present in a thick part of the subject, the radiographic transmittance of the part becomes lower than when the same void or a foreign material is present in the thin part of the subject, and thus the contrast appearing on the differential image is also low. Discarded, there was a non-uniformity in detection accuracy.

In order to solve the above-mentioned problems, the present embodiment aims to provide a radiographic inspection apparatus and a radiographic inspection method capable of improving the detection accuracy of vacancy or foreign matter, regardless of the location of vacancy or foreign matter.

In order to achieve the above object, the radiation inspection apparatus according to the present embodiment includes a radiation source that irradiates radiation, a stage that is located in an irradiation range of the radiation source, and is capable of placing an object, and the stage. The detector is located on the opposite side to the radiation source and detects radiation transmitted through the subject, a processing apparatus for imaging two-dimensional perspective information of the subject obtained from the detector, and an image obtained by the processing apparatus. A display device is provided, and the processing device has a calculation unit that calculates a ratio of the two pieces of fluoroscopy information having different positions of the subject, and generates a two-dimensional ratio image. The apparatus is characterized by displaying the non-image generated by the operation unit.

The radiation inspection method according to the present embodiment is a radiation detection method using a radiation inspection device having a radiation source, a detector, and a display device, and the radiation emitted by the radiation source and transmitted through the subject is detected by the detector, A first acquisition step for acquiring first perspective information, a movement step for moving the subject after the first acquisition step, and the blood irradiated by the radiation source after the movement step and moved in the movement step A second acquiring step for detecting radiation transmitted through the sample by the detector, obtaining second fluoroscopy information, calculating a ratio between the first fluoroscopy information and the second fluoroscopy information, and generating a two-dimensional non-image And a calculation step and a display step for displaying the non-image on the display device.

In addition, the radiation inspection method according to the present embodiment is a radiation detection method using a radiation inspection apparatus having a flat panel detector having a radiation source and a gain correction value setting mode for correcting a sensitivity deviation of each pixel, the gain correction value A starting step for starting the setting mode, a gain correction obtaining step for detecting radiation emitted by the radiation source and passing through the subject by the flat panel detector, and obtaining a gain correction value, and moving the subject It has a moving step and a perspective image acquiring step for detecting radiation transmitted through the subject moved in the moving step by the flat panel detector and acquiring a perspective image.

1 is a diagram showing an example of a configuration of a radiation inspection apparatus according to a first embodiment.
2 is a flow chart showing an example of the operation of the radiation inspection apparatus according to the first embodiment.
3 is a view showing a subject having a different thickness with respect to the direction of transmission of radiation, and shows a subject having voids therein.
4 is a view showing a subject having a different thickness with respect to the direction of radiation transmission, and shows a subject having foreign matter on the surface.
5 is a view showing a subject having a different thickness with respect to the direction of transmission of radiation, and shows a subject having foreign matter therein.
6 is a diagram showing an example of the configuration of a radiographic examination device according to a second embodiment.
7 is a diagram for explaining gain correction.
8 is a functional block diagram of a flat panel detector.
9 is a diagram for explaining gain correction in a state where the subject is placed on the stage.
10 is a flow chart showing an example of the operation of the radiation inspection apparatus according to the second embodiment.

(First embodiment)

Hereinafter, the radiation inspection apparatus according to the first embodiment will be described in detail with reference to the drawings.

(Configuration)

1 is a diagram showing an example of the configuration of a radiographic inspection apparatus according to the present embodiment. The radiation inspection apparatus irradiates the subject 1 with radiation, detects radiation that has passed through the subject 1, and forms a perspective image in the subject 1 based on the detection result. This radiation inspection device has a radiation source 2, a detector 3, a stage 4, a moving mechanism 5, a processing device 6, and a display device 7.

The radiation source 2 irradiates the radiation beam 22 toward the subject 1. The radiation is, for example, X-ray. The radiation beam 22 is a bundle of radiation that expands in a pyramidal shape with the focal point 21 as a vertex, and is a result of narrowing in the collimator the radiation that is expanded in a cone shape. The radiation source 2 is, for example, an X-ray tube. A typical X-ray tube faces a target such as filament and tungsten in a vacuum. The filament is irradiated with electrons, and the electron is accelerated by the tube voltage between the filament and the target, goes toward the target, and irradiates X-rays against the target. This electron flow is the tube current, and the tube current is in the opposite direction to the electron flow.

The detector 3 is arranged to face the focal point 21 of the radiation source 2. The detector 3 is composed of, for example, an image intensifier (I.I.) and a camera, or a flat panel detector (FPD). II expands the scintillator surface made of cesium iodide or the like, which emits light when excited by radiation, in a two-dimensional shape, and multiplies the luminance of the fluorescent image while converting the two-dimensional distribution of the incident radiation into a fluorescent image.倍). The camera parallelizes imaging elements such as CCD and CMOS, and captures a fluorescent image. The FPD has, for example, a photodiode and a TFT switch along the scintillator surface. The photodiode converts and accumulates the fluorescent image into electric charge, and the TFT switch outputs the electric charge accumulated in the photodiode when an ON signal is given.

That is, the detector 3 detects a two-dimensional distribution of the attenuated radiation intensity according to the transmission path of radiation, and outputs transmission data proportional to the radiation intensity. Then, the transmission data is a radiation intensity, an amount of charge indicating the intensity of radiation, or a luminance value indicating the intensity of radiation, and is digitized, for example, at 256 gradations.

The stage 4 is a placement table for the subject 1. The stage 4 is interposed between the radiation source 2 and the detector 3 so that the placement surface faces the radiation source 2, and the placement surface is orthogonal to the optical axis of the radiation beam. This stage 4 is variable in position with respect to the radiation source 2 and the detector 3 by the moving mechanism 5.

The moving mechanism 5 linearly moves and elevates the stage 4. The linear movement direction is the X-axis direction and the Y-axis direction. The X-axis direction is one direction along the plane in which the stage 4 widens. The Y-axis direction is a direction perpendicular to the X-axis direction along the plane in which the stage 4 is widened. The elevation direction is the Z-axis direction. The Z-axis direction is orthogonal to the stage 4 and, in other words, is a direction in which the radiation source 2 is folded.

The processing apparatus 6 controls the radiation source 2, the detector 3 and the moving mechanism 5, causes the subject 1 to be photographed, and also generates an image in the subject 1. The processing device 6 is a so-called computer and a driver circuit connected to the computer by a signal line, and the computer part is composed of a storage such as a CPU, HDD or SSD, and RAM. The storage stores a program, a program is unfolded in RAM, and data is temporarily stored in RAM, the CPU processes the program, and the driver circuit is, for example, a motor driver. Power.

The processing device 6 generates a non-image as an image in the subject 1. The non-image is an image generated by calculating the ratio of two pieces of transmitted data obtained by the same subject 1 being moved by location and photographing, and the value of the ratio of the two pieces of transmitted data is shown on a two-dimensional surface in shades. have. Since the position of the subject 1 is different even though the public or foreign objects are the same, a pair of images appears as a phase of the public or foreign objects on the non-image. The processing device 6 has a storage unit 61, a calculation unit 62, and a photographing control unit 63.

The photographing control unit 63 includes a driver circuit, controls the moving mechanism 5 to move the position of the subject 1, and irradiates the radiation beam before and after the movement to transmit two pieces of transmitted data. Get The storage unit 61 is configured to include storage, and at least stores transmission data of the subject 1 obtained before moving the position.

The calculation unit 62 includes a CPU, calculates a ratio of two pieces of transmitted data having different positions of the subject 1, and generates a two-dimensional non-image. The arithmetic unit 62, for example, the luminance value of the subject 1 stored in the storage unit 61 and the brightness of another subject 1 at a position where the subject 1 is moved slightly. The ratio with the value is obtained in the same coordinate pixel. Then, the calculation unit 62 generates a non-image composed of the ratio of the luminance values in two dimensions by obtaining the ratio in each pixel widening to the placement surface of the detector 3.

The display device 7 is a monitor such as a liquid crystal display or an organic EL display. The display device 7 displays a non-image obtained by the calculation unit 62 on the screen.

(action)

The operation of the radiographic inspection apparatus is shown in the flow chart of FIG. 2. First, the subject 1 is placed on the stage 4 (step S1). Then, the subject 1 on the stage 4 is photographed by radiation (step S2). That is, the radiation beam 22 is irradiated to the subject 1 by the radiation source 2, and the radiation transmitted through the subject 1 is detected by the detector 3. At this time, here, the detector 3 converts the incident radiation intensity into an amount of charge that is proportional to the intensity, and uses discrete pixel values according to the amount of charge. The detector 3 outputs the two-dimensional distribution of pixel values as transmission data to the processing device 6. Then, the processing device 6 stores the input transmission data in the storage unit 61 (step S3).

Next, the subject 1 is moved slightly by moving the stage 4 by the moving mechanism 5 (step S4). Here, the "slightly moving" distance is, for example, a distance that is about the size of a public V or foreign matter F (see FIGS. 3 and 4), and preferably, a public V or foreign matter ( It is a distance less than the size of F), and when an image having the same width as the moving distance is displayed on the display device 7, it is the degree to which the observer can clearly grasp the image. For example, if the size of the foreign matter F to be detected is 100 μm, it is a distance smaller than 100 μm.

After the subject 1 is moved slightly in this way, the subject 1 on the stage 4 is photographed by radiation (step S5). That is, the radiation beam 22 is irradiated to the subject 1 by the radiation source 2, and the radiation transmitted through the subject 1 is detected by the detector 3. The detector 3 outputs the transmission data to the processing device 6.

Then, the calculation unit 62 calculates the ratio between the transmission data stored in the storage unit 61 and the transmission data obtained from the detector 3 in step S5 between pixels of the same coordinates, and calculates the non-image. It is created (step S6). The calculation unit 62 outputs the generated non-image to the display device 7, and displays the non-image on the screen (step S7).

Accordingly, irrespective of the location of the presence of the vacancy (V) and the foreign matter (F), the unique images of the contrast of the vacancy (V) and the foreign matter (F) are obtained, so that the vacancy (V) and the foreign matter (F) are detected The precision to be made can be improved. The principle of improving the detection accuracy of this void and foreign matter will be described with reference to FIGS. 3 and 4.

(Action)

3 and 4 are views showing the subject 1 having a different thickness with respect to the direction of radiation transmission, and the subject 1 of FIG. 3 has a void V therein, and the subject of FIG. (1) Foreign matter (F) is present on the surface. If the intensity of radiation transmitted through the subject 1 and incident on any pixel of the detector 3 is I _A and the intensity of radiation incident on the pixel when the subject 1 is not present is I ₀ , The radiation intensity (I _A ) can be expressed by Equation (1).

μ _A is a line (線) attenuation coefficient of the test body (1), t _A is a transmission distance, i.e. the thickness of the test body (1), which radiation is transmitted through the test object (1).

As shown in FIG. 3, the radiation intensity I ₁ that has transmitted through only the background portion I with a small thickness of the subject 1 can be expressed as in Equation (2), and the background portion I and the public ( The intensity of radiation (I _1+V ) transmitted through _V ) can be expressed as in Expression (3).

t ₁ is the transmission distance of the background portion (I), and t _V is the transmission distance of the public (V).

Therefore, the ratio (I _1+V /I ₁ ) of the radiation intensity is obtained from the formulas (2) and (3) as in the formula (4).

On the other hand, the intensity (I ₂ ) of radiation transmitted through only the thick background portion (II) of the subject 1 can be expressed as in Equation (5), and transmitted through the background portion (II) and the cavity (V). The radiation intensity (I _2+V ) can be expressed as in equation (6).

t ₂ is a transmission distance of the background portion II, and t _V is a transmission distance of the public V.

Therefore, the ratio (I _2+V /I ₂ ) of the radiation intensity is obtained from the formulas (5) and (6) as in the formula (7).

As is evident from the above formulas (4) and (7), the ratio of the radiation intensity (I _1+V /I ₁ and I _2+V /I ₂ ) is equivalent. That is, the ratio of the intensity of radiation transmitted through only the background portion of the subject 1 to the intensity of radiation transmitted through the background portion and the cavity V is not affected by the thickness of the subject 1 serving as the background, and is and ray attenuation coefficient (μ _a) of the sample (1), is a unique value determined by the transmission distance _(V t) of the public (V). Therefore, by calculating the ratio between the intensity of radiation when passing through the voids V and the intensity of radiation when not passing through the voids V, an image reflecting the ratio is generated, whereby the existence of the voids V is present. Presence or absence can be detected.

In addition, as shown in FIG. 4, the ratio (I _1+F ／ I ₁ and I _2+F ／ I _{2) of the} radiation intensity of different thicknesses similarly also when foreign matter F exists on the surface of the subject 1 ) Is equivalent. That is, the intensity of the radiation (I _1+F ) transmitted through the background portion (I) and the foreign matter (F), where the thickness of the subject (1) is thin, can be expressed as in Equation (8). The intensity of radiation (I _2+F ) transmitted through the thick background portion (II) and the foreign matter ( _F ) can be expressed as in Equation (9).

μ _F is the line attenuation coefficient of the foreign material _F , and t _F is the transmission distance of the foreign material F, that is, the thickness of the foreign material F.

Therefore, the ratio of the radiation intensity in each background part I, II from Formula (2), Formula (5), Formula (8), and Formula (9) becomes as Formula (10).

As is apparent from equation (10), the ratio of the intensity of the radiation transmitted through the foreign matter (F) to the background intensity relative to the intensity of radiation transmitted through only the background part of the subject 1 is the background of the subject 1 It does not depend on the thickness, and is a unique value determined by the line attenuation coefficient (μ _F ) of the foreign material F and the transmission distance t _F of the foreign material F. Therefore, by calculating the ratio between the intensity of radiation when the foreign matter F is transmitted and the intensity of radiation when the foreign matter F is not transmitted, an image reflecting the ratio is generated to generate the presence of the foreign matter F. Presence or absence can be detected.

In addition, as shown in FIG. 5, the ratio (I _1+F /I ₁ and I _2+F /I _{2) of the} radiation intensity having different thicknesses is similarly performed when the foreign matter F is present inside the subject 1 ) Is equivalent. That is, the intensity of radiation (I _1+F ) transmitted through the background portion (I) and the foreign matter (F), where the thickness of the subject 1 is thin, can be expressed by Equation (11), and The intensity of radiation (I _2+F ) transmitted through the thick background portion (II) and the foreign matter ( _F ) can be expressed as in equation (12).

μ _A is the line attenuation coefficient of the subject ₁ , and t ₁ is the transmission distance through which the radiation passes through the background part I of the subject 1, that is, the background part I of the subject 1 Is the thickness. t ₂ is a transmission distance through which the radiation penetrates the background portion II of the subject 1, that is, the thickness of the background portion II of the subject 1. μ _F is the line attenuation coefficient of the foreign material _F , and t _F is the transmission distance of the foreign material F, that is, the thickness of the foreign material F.

Therefore, the ratio of the radiation intensity in each background part (I, II) from Formula (2), Formula (5), Formula (11), and Formula (12) becomes as Formula (13).

As is apparent from equation (13), the ratio of the intensity of the radiation transmitted through the foreign matter (F) to the background part and the intensity of the radiation transmitted through only the background part of the subject 1 is the background of the subject 1 Independent of the thickness, a unique value determined by the line attenuation coefficient (μ _A ) of the subject, the line attenuation coefficient (μ _F ) of the foreign matter (F), and the transmission distance (t _F ) of the foreign matter (F) It becomes. Therefore, by calculating the ratio between the intensity of radiation when the foreign matter F is transmitted and the intensity of radiation when the foreign matter F is not transmitted, an image reflecting the ratio is generated to generate the presence of the foreign matter F. Presence or absence can be detected.

That is, in this radiation inspection apparatus, the intensity of the radiation and the vacancy (V) when passing through the vacancy (V) or the foreign matter (F) are calculated by moving the stage (4) slightly and calculating the ratio of transmitted data before and after movement. ) Or the ratio with the intensity of radiation when the foreign material (F) is not transmitted is calculated.

And, to make the stage 4 move slightly, for example, the intensity of radiation transmitted through only the background portion II of the subject 1, the background portion I and the public V or foreign substances ( This is to avoid becoming a ratio of the intensity of radiation transmitted through F). However, the degree to which the pixel region in which the ratio of the intensity of radiation when passing through the void (V) or foreign matter (F) and the intensity of radiation when not passing through the void (V) or foreign matter (F) is calculated can be grasped on the image Is preferred. Specifically, it is preferable that the pixel pitch of the detector 3 at the position where the void V or the foreign matter F exists, for example, is about three times as a small movement amount. Here, the pixel pitch of the detector 3 at the position where the void V or foreign matter F is present means the pixel pitch of the detector 3, and the radiation input surface of the focus 21 and the detector 3 It is the value divided by the ratio (FDD/FOD) of the distance (FDD) and the distance (FOD) between the focal point (21) and the public (V) or foreign object (F).

Moreover, it is preferable that the movement mechanism 5 moves the subject 1 in the direction in which the subject 1 has translational symmetry. The direction having translational symmetry is a direction in which there is little change in transmission data before and after the movement of the subject 1. Therefore, this radiation inspection apparatus is particularly effective for a subject 1, such as a cylindrical battery having an internal structure in which an anode foil and a cathode foil are wound, for example. This battery has a structure in which each cross section orthogonal to the axis has the same structure, and the direction of its cylindrical axis has translational symmetry.

(effect)

As described above, the radiation inspection apparatus of the present embodiment includes a stage 4 and a stage 4 that are located in the irradiation range of the radiation source 2 and the radiation source 2 for irradiating radiation, and on which the subject 1 can be placed. The image of the two-dimensional perspective information of the detector 3 which is located on the opposite side to the intervening radiation source 2 and which detects radiation transmitted through the subject 1 and the subject 1 obtained from the detector 3 A processing device 6 to be converted and a display device 7 to display images obtained by the processing device 6 are provided. In addition, the processing device 6 has a calculation unit 62 that calculates a ratio of two transmitted data having different positions of the subject 1 and generates a non-image of two dimensions, and the display device 7 includes a calculation unit The non-image generated by (62) was displayed.

Accordingly, irrespective of the location of the presence of foreign matter and foreign matter, a non-image of a unique contrast of voids and foreign matter is obtained, and thus the accuracy of detecting voids and foreign matters can be improved. For example, when viewing a perspective image, since background portions other than the public and foreign objects are almost uniform shades, information of the background portions is calculated by calculating the ratio of two pieces of transmitted data having different positions of the subject 1. Can be offset. On the other hand, since the portions of the voids and foreign matters are intrinsic values that do not depend on the X-ray transmission thickness of the background portion, they can have a noticeable difference in shade and make them stand out. Therefore, it is possible to improve the precision of detecting voids or foreign objects.

In addition, in this embodiment, the ratio of the transmission data output from the detector 3 was calculated. However, as long as it is perspective information derived from a two-dimensional distribution of radiation intensity, regardless of the location of the public or foreign matter, the public and the foreign matter are unique. Since a non-contrast non-image is obtained, the accuracy of detecting voids and foreign matter can be improved. As the fluoroscopy information, in addition to the transmissive data, there can be exemplified a transmissive image in which the pixel value of the transmissive data is converted into a luminance value such as grayscale and displayed on the display device 7.

Moreover, the radiation inspection apparatus of this embodiment has the moving mechanism 5 which moves the stage 4, and the moving mechanism 5 is the direction to which the subject 1 has translational symmetry, and the subject 1 ) Had to move. Accordingly, the perspective information of the background portion other than the public and foreign objects can be almost the same before and after the movement of the subject 1, and thus can be offset, thereby making the public and foreign objects stand out. As a result, it is possible to improve the detection accuracy of vacancy and foreign matter.

(Second embodiment)

(Configuration)

Next, the radiation inspection apparatus according to the second embodiment will be described in detail with reference to the drawings. The same code|symbol is attached|subjected about the same structure and the same function as 1st Embodiment, and detailed description is abbreviate|omitted.

6 is a diagram showing an example of the configuration of a radiation inspection apparatus according to the second embodiment. As shown in FIG. 6, the radiation inspection apparatus of this embodiment has the flat panel detector 8. The flat panel detector 8 has a gain correction value setting mode. The gain correction value setting mode is a mode for setting a gain correction value to correct variations in sensitivity of each pixel. As shown in Fig. 7, each pixel has a variation in sensitivity, and even when the incident radiation intensity is the same, the value of the fluoroscopy information as an output value is different. Therefore, the gain correction value is obtained so that the value of the perspective information output from the flat panel detector 8 is output at a constant value in each pixel, and the sensitivity is fixed by multiplying the detection amount of the flat panel detector 8 by a gain correction value. To do the correction. In order to make the output value of each pixel constant, for example, if the output value is normalized to 1, the gain correction value is the reciprocal of the detection amount of the flat panel detector 8, and as shown in Fig. 7, the detection sensitivity of each pixel And complementary relationships.

8 is a functional block diagram of the flat panel detector 8. As shown in Fig. 8, this flat panel detector 8 includes an X-ray detection unit 3a, a gain correction acquisition unit 81, a storage unit 82, and a calculation unit 83.

The X-ray detector 3a is a radiation detection element of the flat panel detector 8, and has a photodiode and a TFT switch along the scintillator surface.

The gain correction acquisition unit 81 detects the radiation transmitted through the subject 1 while the subject 1 is placed on the stage 4, and obtains a gain correction value in which each pixel value is the same value. To acquire. This gain correction value is a two-dimensional distribution, and the subject 1 is reflected. For example, as shown in Fig. 9, when the subject 1 is placed on the stage 4 and the radiation transmitted through the subject 1 is detected, the variance in sensitivity of each pixel and the subject are observed in the perspective information. The shape according to the thickness of (1) appears. The gain correction acquisition unit 81 acquires a gain correction value as the reciprocal of the perspective information. The storage unit 82 includes storage, and stores gain correction values acquired by the gain correction acquisition unit 81. The calculation unit 83 includes a CPU, and multiplies the gain correction value with respect to the perspective information obtained by the X-ray detection unit 3a.

(Action)

10 is a flowchart showing an example of the operation of the radiation inspection apparatus according to the present embodiment. As shown in Fig. 10, first, the gain correction value setting mode is activated (step S21). Next, the subject 1 is placed on the stage 4 (step S22). Then, the radiation irradiated by the radiation source 2 and transmitted through the subject 1 is detected by the flat panel detector 8, and the gain correction value is acquired by the gain correction acquisition unit 81 (step S23). ). Further, the obtained gain correction value is stored in the storage unit 82 (step S24).

Next, the gain correction value setting mode is terminated (step S25), and the subject 1 is moved slightly by moving the stage 4 by the moving mechanism 5 (step S26). After the subject 1 is moved slightly, the inspection mode is started (step S27), and the subject 1 on the stage 4 is photographed by radiation (step S28). That is, the radiation beam 22 is irradiated to the subject 1 by the radiation source 2, and the radiation transmitted through the subject 1 is detected by the flat panel detector 8. The perspective information, which is the result of the detection, is output to the calculation unit 83.

Then, in step S28, the calculation unit 83 multiplies the two-dimensional luminance values obtained from the X-ray detection unit 3a and the gain correction values stored in the storage unit 82 between pixels of the same coordinates. At this time, since the gain correction value is the reciprocal of the perspective information of the subject 1, this multiplication produces a non-image (step S29). The calculation unit 83 outputs the generated non-image to the display device 7, and displays the non-image on the screen (step S30).

(effect)

The radiation inspection apparatus of the present embodiment has a flat panel detector 8, and the flat panel detector 8 sets each pixel value to the same value while the subject 1 is placed on the stage 4 It has a gain correction acquisition unit 81 for acquiring a gain correction value, a storage unit 82 for storing a gain correction value, and a calculation unit 83. The calculation unit 83 generated a non-image by multiplying the gain correction value and the perspective information obtained by moving the subject 1 to a position different from when the gain correction value is acquired.

Accordingly, the output of the flat panel detector 8 is a non-image as it is, and the configuration and time for calculating the non-image can be reduced. That is, the gain correction value is obtained in the state where nothing is placed on the stage 4, and the gain correction value is obtained by multiplying the gain correction value by the perspective information in the state where the subject 1 is placed on the stage 4 to perform gain correction. In the case of the conventional method of using the result as the output value of the flat panel detector 8, it is necessary to calculate the ratio between the perspective information by the first imaging and the perspective information by the second imaging by moving the position. .

On the other hand, in this embodiment, since the gain correction value is acquired while the subject 1 is placed on the stage 4, the variation in sensitivity of each pixel and the subject 1 are reflected in this gain correction value. The gain correction value is, for example, the reciprocal of the perspective information by the first imaging in the first embodiment. Therefore, the result obtained by performing the gain correction that multiplies this gain correction value by the perspective information by the shifted imaging is the non-image itself.

Therefore, it is not even possible to actually calculate a non-image, and by performing a gain correction using a general flat panel detector having a gain correction function, the same effect as substantially calculating a non-image can be obtained. In other words, the arithmetic unit 83 is substantially the same as the arithmetic unit 62, and the flat panel detector 8 is obtained by storing the gain correction value acquired by the gain correction acquisition unit 81 in the storage unit 61, It can be configured to include a detector 3 and a processing device (6).

In addition, there is an advantage in that a non-image with a good SN can be obtained, rather than gain correction using a gain correction in which air is passed through the stage 4 in which nothing is placed. In addition, in the conventional method using a gain correction in which the air in the state where nothing is placed on the stage 4 is transmitted, since the same gain correction is continuously used even when the subject 1 is changed, the change over time of each pixel or the like is changed. Is not reflected. On the other hand, in this embodiment, since the gain correction value is acquired in the state where the subject 1 is placed on the stage 4 every time the subject 1 changes, the ratio over time of the flat panel detector 8 is also considered. An image can be obtained, and the accuracy of detecting voids (V) and foreign matter (F) can be further improved.

(Other embodiments)

In the present specification, embodiments according to the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. The embodiment and its modifications are included in the scope of the invention and the equivalents of the invention described in the claims.

For example, in the first and second embodiments, the calculation units 62 and 83 are configured as computers, but may be configured by dedicated electronic circuits. The calculation unit 62 may be configured to include a logarithmic conversion circuit for logarithmic conversion of perspective information, a difference circuit for calculating the difference between two logarithmic converted perspective information, and an exponential conversion circuit for exponentially converting values obtained by the difference circuit. do. Accordingly, a non-image can be generated at a higher speed.

In the first and second embodiments, the subject 1 is moved by the moving mechanism 5, but the worker may move it.

1: Subject 2: Radiation source
21: focus 22: radiation beam
3: detector 3a: X-ray detector
4: stage 5: moving mechanism
6: processing unit 61: storage unit
62: operation unit 63: shooting control unit
7: Display device 8: Flat panel detector
81: gain correction acquisition unit 82: storage unit
83: operation unit

Claims (7)

A radiation source that irradiates radiation,
A stage positioned in the irradiation range of the radiation source and capable of placing a subject;
A detector which is located on the opposite side to the radiation source with the stage interposed therebetween, and detects radiation transmitted through the subject;
A processing apparatus for imaging two-dimensional perspective information of the subject obtained from the detector;
And a display device for displaying the image obtained by the processing device,
The processing device,
Has a calculation unit for calculating the ratio of the two pieces of perspective information having different positions of the subject, and generating a two-dimensional ratio image,
The display device,
A radiation inspection apparatus characterized by displaying the non-image generated by the operation unit. According to claim 1,
The stage is moved to move the position of the subject,
The radiation source irradiates radiation before and after movement of the stage,
The detector detects radiation that has passed through the subject before and after movement of the stage, respectively.
And the calculation unit calculates a ratio of the two perspective information before and after the stage is moved. The method according to claim 1 or 2,
The calculation unit,
A logarithmic conversion circuit for algebraically converting the perspective information;
A difference circuit for calculating the difference between the two algebraic transformed perspective information,
And an exponential conversion circuit that exponentially converts the value obtained by the difference circuit. The method according to claim 1 or 2,
Having a flat panel detector comprising the detector and the processing device,
The flat panel detector,
A gain correction acquiring unit for acquiring a gain correction value in which each pixel value is set to the same value while the subject is placed on the stage;
Further having a storage unit for storing the gain correction value,
The calculation unit generates the non-image by multiplying the perspective correction information obtained by moving the subject to a position different from when the gain correction value is acquired and the gain correction value. The method according to claim 1 or 2,
It has a moving mechanism for moving the stage,
And the moving mechanism moves the subject in a direction in which the change in the perspective information before and after the movement of the position is small. A radiation detection method using a radiation inspection device having a radiation source, a detector and a display device,
A first acquiring step of detecting radiation emitted by the radiation source and passing through the subject by the detector, and acquiring first perspective information;
A moving step for moving the subject after the first acquiring step,
A second acquiring step of detecting radiation emitted by the radiation source after the moving step and passing through the subject moved in the moving step by the detector, and obtaining second perspective information;
A calculation step of calculating a ratio between the first perspective information and the second perspective information, and generating a two-dimensional non-image,
And a display step of displaying the non-image on the display device. delete

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