JP2015075358A - Radiation inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device that can identify, at a high resolution, a foreign matter deposited in fluid stored in an analyte, and can accurately detect it.SOLUTION: A radiation generating tube 1A is disposed so as to emit radiation at a predetermined angle with respect to the vertical direction, and, in a radiation detector 2, the string of radiation detection elements 21 is disposed in the longitudinal direction. They are disposed so as to satisfy θ>θ. Here, θshows the angle between the straight line 51 that connects the center of the radiation detection element 211 located at the lowest end to the focal point center of the radiation generating tube 1A and the normal line 5 of the electron irradiation surface of a target passing the focal point center. The θshows the angle between the normal line 5 and the straight line 52 that connects the center of the radiation detection element 212 located at the upper end to the focal point center of the radiation generating tube 1A.

Description

  The present invention relates to a radiation inspection apparatus that detects a foreign substance in a subject by irradiating the subject with radiation such as X-rays.

  Radiation inspection apparatuses are used as means for inspecting the presence or absence of foreign matters in various products. The radiation inspection apparatus irradiates a subject with radiation such as X-rays, and detects radiation transmitted through the subject with a radiation detector. Due to the difference in the amount of radiation transmitted through the subject, foreign matter in the subject is detected. The presence or absence of is detected.

  In recent years, particularly in the food field, there has been an increasing demand for food safety, and there is a need to prevent contamination by foreign substances. For this reason, various measures have been taken to improve the detection accuracy of foreign substances in radiation inspection apparatuses.

  Conventionally, for example, Patent Document 1 discloses a radiation inspection apparatus that irradiates radiation near the bottom surface of a subject obliquely with respect to a horizontal plane. Patent Document 1 describes that, according to such a radiation inspection apparatus, foreign matter in the vicinity of the bottom surface can be enlarged and detected, so that the accuracy of foreign matter detection in beverages in which foreign matter tends to settle can be improved. Yes.

JP 2012-68126 A

  By the way, in the case of foreign matter mixed in fluid such as beverages, depending on the type of fluid and the manufacturing process, foreign matter having a specific gravity larger than that of the subject fluid and easily settled may be mixed, and the specific gravity may be higher than that of the subject fluid. There may be small foreign objects that are likely to rise.

  However, in the radiation inspection apparatus disclosed in Patent Document 1, no particular improvement has been made with respect to the detection of foreign matter that floats in the fluid. Further, Patent Document 1 only discloses that the foreign matter is enlarged and detected, but does not specifically disclose that the minute foreign matter is detected with high resolution.

  The present invention solves the above-mentioned problems, and an object of the present invention is to detect foreign matter unevenly distributed in a fluid due to a difference in specific gravity, etc., so that it can be accurately detected. The object is to provide a radiological examination apparatus.

To that end, a first aspect of the present invention is a radiation generating tube provided with a target that generates radiation by electron irradiation,
A radiation detector having a plurality of rows of radiation detection elements that receive radiation from the radiation generating tube;
In a radiological examination apparatus comprising a subject placement unit capable of positioning a subject between the radiation generating tube and the radiation detector,
The radiation generating tube is arranged to emit the radiation with a predetermined radiation angle in the vertical direction, and
The radiation detector is arranged so that the rows of the radiation detection elements are in a vertical direction,
The angle formed by the straight line connecting the center of the radiation detecting element located at the lower end and the focal center of the radiation generating tube and the normal of the electron irradiation surface of the target passing through the focal center is θ ₁ , and the radiation located at the upper end Provided is a radiation inspection apparatus characterized in that θ ₁ > θ ₂ when θ ₂ is an angle formed by a straight line connecting the center of the detection element and the focal center of the radiation generating tube and the normal line. Is.

A second aspect of the present invention is a radiation generating tube provided with a target for generating radiation by irradiation with an electron beam bundle,
A radiation detector having a plurality of rows of radiation detection elements that receive radiation from the radiation generating tube;
In a radiological examination apparatus comprising a subject placement unit capable of positioning a subject between the radiation generating tube and the radiation detector,
The radiation generating tube is arranged to emit the radiation with a predetermined radiation angle in the vertical direction, and
The radiation detector is arranged with the rows of the radiation detection elements oriented in the vertical direction,
The angle formed by the straight line connecting the center of the radiation detecting element located at the lower end and the focal center of the radiation generating tube and the normal of the electron irradiation surface of the target passing through the focal center is θ ₁ , and the radiation located at the upper end Provided is a radiation inspection apparatus characterized in that θ ₂ > θ ₁ when θ ₂ is an angle formed between a straight line connecting the center of the detection element and the focal center of the radiation generating tube and the normal line. Is.

  According to the first aspect of the present invention, the apparent focal length on the lower side of the subject provided in the subject placement portion is smaller than the apparent focal length on the upper side and the focal length on the target. As a result, the resolution on the lower side of the subject can be increased, so that highly accurate detection can be performed on the lower portion of the subject. Therefore, the radiological examination apparatus according to the first aspect of the present invention uses a container containing a fluid as a subject, and detects foreign matter having a specific gravity higher than that of the fluid mixed in the subject as a detection target. Can be detected well.

  According to the second aspect of the present invention, the apparent focal length on the upper side of the subject provided in the subject placement portion is smaller than the apparent focal length on the lower side and the focal length on the target. As a result, the resolution on the upper side of the subject can be increased, so that highly accurate detection can be performed on the upper portion of the subject. Therefore, in the radiological examination apparatus according to the second aspect of the present invention, if a container containing a fluid is used as a subject and a foreign substance having a specific gravity lower than that of the fluid mixed therein is detected, the foreign substance levitated on the fluid is accurately detected. Can be detected well.

It is a schematic diagram which shows the 1st example of the radiography apparatus of this invention. It is explanatory drawing regarding the radiation angle and focal length in the radiographic inspection apparatus of this invention. It is a schematic diagram of the radiation generating tube used for the radiation inspection apparatus of this invention. 1 is a system configuration diagram of a radiation inspection apparatus of the present invention. It is a schematic diagram which shows the 2nd example of the radiography apparatus of this invention. It is a schematic diagram which shows the 3rd example of the radiography apparatus of this invention. It is a schematic diagram which shows the 4th example of the radiography apparatus of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same reference numerals indicate the same components. 1, 5, 6 and 7, the vertical direction is the vertical direction.

[First example]
First, a first example of the present invention will be described with reference to FIGS. In this example, the subject 4 is a container 42 in which a fluid 41 is stored, and a radiological examination apparatus suitable for detecting a foreign substance having a higher specific gravity than the stored fluid 41 mixed in the container 42. It is an example. In addition, an example in which radiation is irradiated obliquely from above the subject 4 is shown.

  As shown in FIG. 1, the radiation inspection apparatus of this example includes a radiation generating tube 1 </ b> A, a radiation detector 2, and a subject placement unit 3.

  The radiation detector 2 has a row of a plurality of radiation detection elements 21 that receive radiation from the radiation generating tube 1A. In this example, a line sensor in which a plurality of radiation detection elements 21 are arranged in a line is used. The radiation detector 2 is arranged with the row of radiation detection elements 21 oriented in the vertical direction. The arrangement directed in the vertical direction is an arrangement in which one end is positioned vertically above and the other end is positioned below, and includes both vertical arrangement and oblique arrangement. Here, the radiation detection element located at the lower end in the vertical direction is designated as 211, and the radiation detection element located at the upper end in the vertical direction is designated as 212. The subject 4 is a container 42 that contains a fluid 41. The subject 4 is positioned between the radiation generating tube 1 and the radiation detector 2 by the subject placement unit 3. The subject 4 is erected on the subject placement unit 3. A collimator (not shown) or the like can be arranged between the radiation generating tube 1 and the subject 4 in order to suppress irradiation of unnecessary radiation.

  When the radiation detector 2 has a rectangular radiation detection surface in which a plurality of radiation detection elements 21 are arranged vertically and horizontally, the radiation is irradiated from the radiation generating tube 1 </ b> A to the region corresponding to the radiation detection surface. In this case, the subject 4 can be examined while being moved between the radiation generating tube 1A and the radiation detector 2, but the subject 4 standing on the subject placement unit 3 can be examined in a stationary state. it can. Further, when the radiation detector 2 is a line sensor in which the radiation detection elements 21 are arranged in a line, the radiation is usually irradiated in a line shape corresponding to the radiation detection elements 21 in a line. In this case, the subject placement unit 3 that can transport the subject 4 across the space between the radiation generating tube 1A and the radiation detector 2 is usually used. By detecting the radiation with the line sensor while moving the subject 4 between the radiation generating tube 1A and the radiation detector 2, the entire subject 4 can be inspected. In the example of FIG. 1, the subject placement unit 3 is a rotating plate, and the subject 4 can be moved between the ray generating tube 1 </ b> A and the radiation detector 2 by the rotation.

  The radiation generating tube 1A is arranged so as to emit radiation with a predetermined radiation angle in the vertical direction. The radiation angle of the radiation generating tube 1A is an angle in which the entire height direction of the subject 4 located between the radiation generating tube 1A and the radiation detector 2 is included inside the radiation irradiation region by the radiation generating tube 1A. Is preferred. By setting such an angle, the entire height direction of the subject 4 can be inspected at a time.

  FIG. 3 is a schematic diagram of radiation generating tubes 1A and 1B that can be used in the radiation inspection apparatus of the present invention. In the radiation inspection apparatus of the present invention, either the transmission type radiation generating tube 1A shown in FIG. 3A or the reflection type radiation generating tube 1B shown in FIG. 3B can be used. FIG. 1 shows an example using a transmission type radiation generating tube 1A as an example.

  The transmission type radiation generating tube 1A will be described with reference to FIG. As shown in FIG. 3A, the radiation generating tube 1A includes an electron emission source 11 that emits an electron beam bundle, and a transmission target 12A that generates radiation by electron irradiation.

  The target 12A includes a target layer 12a and a support substrate 12b. When a high voltage is applied between the electron emission source 11 and the target layer 12a, electrons are emitted from the electron emission source 11, incident on the target layer 12a, and radiation is generated. The radiation generated in the target layer 12a passes through the support substrate 12b and is then emitted to the outside of the radiation generating tube 1. In addition, the irradiation area | region (area | region which generate | occur | produces a radiation) of the electron beam bundle to the target layer 12a is called the focus 13, and the center of the focus 13 is called the focus center 13a (refer FIG. 2). The position of the focal center 13a is a position corresponding to the barycentric position of the plate material when a plate material having the same shape and size as the focal point 13 and a uniform thickness is assumed.

  An anode member 15 is disposed around the target 12A and is electrically connected to the target layer 12a. The support substrate 12b is mechanically connected to the anode member 15 and constitutes a part of the envelope of the radiation generating tube 1. The electron emission source 11 is electrically connected to the cathode member 16. An insulating tube 17 is mechanically connected between the anode member 15 and the cathode member 16.

  The target layer 12a is disposed on the surface of the support substrate 12b on the electron emission source 11 side (electron irradiation surface side). The material constituting the target layer 12a is preferably a material having a high melting point and high radiation generation efficiency. For example, tungsten, tantalum, molybdenum and alloys thereof can be used. The material constituting the support substrate 12b is strong enough to support the target layer 12a, has little heat absorption of the radiation generated in the target layer 12a, and has high thermal conductivity so that heat generated in the target layer 12a can be quickly dissipated. Those are preferred. For example, diamond, silicon carbide, aluminum nitride, or the like can be used.

  The electron emission source 11 may be a tungsten filament, a hot cathode such as an impregnated cathode, or a cold cathode such as a carbon nanotube. An extraction electrode and a focusing electrode (not shown) may be provided in the vicinity of the electron emission portion 11. In the case where these are provided, electrons are emitted from the electron emission portion by the electric field formed by the extraction electrode, and the emitted electrons are converged by the convergence electrode and incident on the target layer 12a to generate radiation.

  Next, the reflection type radiation generating tube 1B will be described with reference to FIG. In FIG. 3B, the same components as those in FIG. 3A are denoted by the same reference numerals. As shown in FIG. 3B, the radiation generating tube 1B includes an electron emission source 11 and a reflective target 12B. The target 12B is electrically connected to the anode member 15. As a material constituting the target 12B, tungsten, tantalum, molybdenum, an alloy thereof, or the like can be used.

  When electrons emitted from the electron emission source 11 enter the target 12B, radiation is generated on the electron irradiation surface side of the target 12B. In the reflection type radiation generating tube 1B, of the radiation generated by the target 12B, the radiation reflected by the target 12B and emitted toward the electron emission source 11 passes through a transmission window (not shown) provided in the insulating tube 17. And released to the outside of the radiation generating tube 1B.

  Next, the positional relationship and the angular relationship among the targets 12A and 12B, the subject 4 and the radiation detector 2 of the radiation generating tube 1 will be described with reference to FIGS. FIG. 2 shows the apparent focal point 14 and its focal length when the focal point 13 is viewed from the direction of the radiation angle θ. FIG. 2A shows the case of the transmission type target 12A (transmission type radiation generating tube 1A), and FIG. 2B shows the case of the reflection type target 12B (reflection type radiation generating tube 1B). 2A and 2B, the display of the electron beam bundle and the electron emission source is omitted, but the size of the focal point 13 is defined by the beam diameter of the electron beam bundle irradiated from the electron emission source. Is. Although the size of the focal point 13 is desired to be small in terms of detection resolution, from the viewpoint of the radiation intensity and the heat resistance of the targets 12A and 12B, a predetermined focal size is industrially selected.

  First, with reference to FIG. 1 and FIG. 2A, the positional relationship and the angular relationship among the target 12A, the subject 4 and the radiation detector 2 when the transmission type radiation generating tube 1A is used will be described.

  In the radiation detector 2, the radiation transmitted through the bottom surface side of the subject 4 is incident on the radiation detection element on the radiation detection element 211 side at the lower end, and the radiation transmitted through the upper surface side of the subject 4 is converted into the radiation detection element at the upper end. It arrange | positions so that it may inject into the radiation detection element of 212 side.

Here, the normal 5 of the electron irradiation surface of the target 12A passing through the focal center 13a (perpendicular to the electron irradiation surface of the target 12A) and a straight line 51 connecting the focal center 13a and the center of the radiation detecting element 211 at the lower end are formed. The angle is θ ₁ . Further, an angle formed by the normal 5 and a straight line 52 connecting the focal center 13a and the center of the radiation detecting element 212 at the upper end is defined as θ ₂ . In the example of FIG. 1, the target 12A is disposed so as to satisfy θ ₁ > θ ₂ . As shown in FIG. 2A, when the focal length on the target 12A is L ₀ and the angle between the normal 5 of the target 12A and the radiation in an arbitrary direction is θ, the focal point viewed from the angle θ direction. The length L ₁ is represented by L ₀ × cos θ. Accordingly, when θ is in the range of 0 ° ≦ θ ≦ 90 °, the apparent focal length L ₁ becomes smaller as θ becomes larger. In this example, since the target 12A is disposed so as to satisfy θ ₁ > θ ₂ , the focal length L ₁ viewed from the bottom surface side of the subject 4 can be further reduced. Therefore, the foreign matter existing on the bottom surface side of the subject 4 can be detected with higher resolution.

In order to detect the bottom surface side of the subject 4 with higher resolution, it is preferable to arrange so that θ ₁ is larger than θ ₂ as much as possible. However, if the difference between θ ₁ and θ ₂ is too large, the difference in radiation dose irradiated between the bottom surface side and the top surface side of the subject 4 becomes large, and image processing for detecting foreign matter may be difficult. Therefore, it is preferable that θ ₂ <θ ₁ <θ ₂ × 10 (where θ ₁ <90 °), and θ ₂ × 2 <θ ₁ <θ ₂ × 5 (where θ ₁ <90 °). Is more preferable.

In addition, the angle formed between the normal 5 of the target 12A and the surface of the radiation detection element 21 (the surface of the radiation detector 2) in the column direction of the radiation detection element 21, and the angle on the radiation detection element 211 side at the lower end is φ ₁ , The angle on the radiation detection element 212 side at the upper end is φ ₂ . At this time, it is preferable to arrange the radiation detector 2 so that φ1 ≦ 90 °. By setting φ ₁ ≦ 90 °, the blur of the image projected on the radiation detection element 21 on the radiation detection element 211 side at the lower end can be reduced, and the resolution can be increased. The smaller the angle φ _{1, the} higher the resolution on the bottom surface side of the subject 4. However, the smaller the angle φ ₁ , the lower the resolution on the upper surface side of the subject 4, and the required length of the radiation detector 2. become longer. Therefore, the angle φ ₁ is preferably in the range of 45 ° ≦ φ ₁ ≦ 90 °.

FIG. 2B shows a case where the reflective target 12B is used (when the reflective radiation generating tube 1B is used). The relationship between the radiation angle θ and the apparent focal length L ₁ is the same as when the transmission type target 12A shown in FIG. 2A is used (when the transmission type radiation generating tube 1A is used). Therefore, the relationship between θ ₁ and θ ₂ is the same when the reflection type radiation generating tube 1B is used. In the present invention, either the transmission type radiation generating tube 1A or the reflection type radiation generating tube 1B can be used. However, since the transmission type radiation generating tube 1A has a wider radiation angle, More preferably, it can be used.

  Next, the system configuration of the radiation inspection apparatus of the present invention will be described with reference to FIG. The system control device 62 controls the radiation generating tube 1 </ b> A (1 </ b> B), the radiation detection device 61, and the transport driving device 68 in a coordinated manner. The radiation generation tube control unit 65 outputs various control signals to the radiation generation tube 1A (1B) under the control of the system control device 62. The emission state of the radiation emitted from the radiation generating tube 1A (1B) is controlled by the control signal. The transport driving device 68 drives the subject placement unit 3 so as to pass the subject 4 across between the radiation generating tube 1A (1B) and the radiation detector 2. The radiation emitted from the radiation generating tube 1A (1B) passes through the subject 4 and is detected by the radiation detector 2. The radiation detector 2 converts the detected radiation into an image signal and outputs the image signal to the signal processing unit 67. The signal processing unit 67 performs predetermined signal processing on the image signal under the control of the system control device 62, and outputs the processed image signal to the system control device 62. The system control device 62 determines the presence / absence of a foreign substance based on the processed image signal. The determination result is output to the display device 63. The subject 4 for which the examination has been completed is transported to a predetermined place by the subject placement unit 3 driven by the transport driving device 68 according to the determination result.

  As described above, according to the present embodiment, since the resolution on the bottom surface side of the subject 4 is improved, it is possible to provide a radiation inspection apparatus that can accurately detect a foreign substance having a higher specific gravity than the fluid stored in the subject 4. it can.

[Second example]
Next, a second example of the present invention will be described with reference to FIG. The subject 4 in this example is a container 42 containing a fluid 41, and a foreign object having a higher specific gravity than the fluid 41 contained in the container 42 and contained in the container 42 is to be detected. It is an example of a suitable radiological examination apparatus. This example is an example in the case of irradiating radiation from the side surface direction of the subject 4, and other than that is the same as the first example.

Also in this example, the target 12A of the radiation generating tube 1A is arranged so as to satisfy θ ₁ > θ ₂ . Here, the definitions of θ ₁ and θ ₂ are the same as those in the first example. Thereby, the resolution on the bottom surface side of the subject 4 can be increased. In this example, since the radiation is irradiated from the side surface direction of the subject 4, the radiation is incident at a low angle on the bottom surface side of the subject 4. Therefore, the foreign matter on the bottom surface side of the subject 4 can be further enlarged and detected, and the foreign matter detection accuracy can be further increased.

  As described above, according to this example, it is possible to provide a radiation inspection apparatus capable of accurately detecting a foreign substance having a higher specific gravity than the fluid 41 stored in the subject 4. In addition, although this example is an example at the time of using the transmissive | pervious radiation generator tube 1A, it is the same also using the reflective radiation generator tube 1B.

[Third example]
Next, a third example of the present invention will be described with reference to FIG. The subject 4 in this example is a container 42 containing a fluid 41, and is an example of a radiation inspection apparatus suitable for detecting foreign matter mixed in the container 42 and having a lower specific gravity than the contained fluid 41. The rest is the same as the first example. This example is an example in the case of irradiating radiation from obliquely above the subject 4 as in the first example.

In this example, the target 12A of the radiation generating tube 1A is disposed so as to satisfy θ ₂ > θ ₁ , contrary to the first example. Here, the definitions of θ ₁ and θ ₂ are the same as those in the first example. As a result, the apparent focal length L ₁ on the upper surface side of the subject 4 can be further reduced, and the foreign matter existing on the upper surface side of the subject 4 can be detected with higher resolution.

The relationship between θ ₁ and θ ₂ and φ ₁ and φ ₂ in this example is opposite to that in the first example, and the preferred range of θ ₂ is θ ₁ <θ ₂ <θ ₁ × 10 (where θ ₂ < 90 °), and a more preferable range is θ ₁ × 2 <θ ₂ <θ ₁ × 5 (where θ ₂ <90 °). Moreover, it is preferable to arrange the radiation detector 2 so that φ ₂ ≦ 90 °. By setting φ ₂ ≦ 90 °, the blur of the image projected on the radiation detection element 21 on the radiation detection element 212 side at the upper end can be reduced and the resolution can be increased. The smaller the angle φ _{2, the} higher the resolution on the upper end side of the subject 4. However, the smaller the angle φ ₂ , the lower the resolution on the lower surface side of the subject 4, and the required length of the radiation detector 2. become longer. Therefore, the angle φ ₂ is preferably in the range of 45 ° ≦ φ ₂ ≦ 90 °. The definitions of φ ₁ and φ ₂ are the same as those in the first example.

  As described above, according to this example, it is possible to provide a radiation inspection apparatus capable of accurately detecting a foreign substance having a specific gravity lower than that of the fluid of the subject. This example is an example in which the position of the focal center 13a is the same as that in the first example, and the inclination of the target 12A (radiation generating tube 1A) is changed. That is, the radiation inspection apparatus according to the first example and the radiation inspection apparatus of the present example can be switched by changing the inclination of the radiation generating tube 1A. In addition, although this example is an example at the time of using the transmissive | pervious radiation generator tube 1A, it is the same also using the reflective radiation generator tube 1B.

[Fourth example]
Next, a fourth example of the present invention will be described with reference to FIG. In this example, as in the third embodiment, the subject 4 is a container 42 in which a fluid 41 is stored, and a radiation inspection apparatus that detects a foreign substance having a specific gravity lower than that of the fluid 41 stored in the subject 4. It is an example. This example is an example in the case of irradiating radiation from the side surface direction of the subject 4, and other than that is the same as the third example.

In this example, the target 12A of the radiation generating tube 1A is arranged so as to satisfy θ ₂ > θ ₁ . The definitions of θ ₁ and θ ₂ are the same as those in the first example. Thereby, the resolution on the upper surface side of the subject 4 can be increased.

  According to this example, it is possible to provide a radiation inspection apparatus capable of accurately detecting a foreign substance having a specific gravity lower than that of the fluid 41 stored in the subject 4. This example is an example in which the position of the focal center 13a is the same as in the second example, and the inclination of the target 12A (radiation generating tube 1A) is changed. That is, it is possible to switch between the radiation inspection apparatus of the second example and the radiation inspection apparatus of the present example by changing the inclination of the radiation generating tube 1A. In addition, although this example is an example at the time of using the transmissive | pervious radiation generator tube 1A, it is the same also using the reflective radiation generator tube 1B.

  1A, 1B: radiation tube, 2: radiation detector, 3: subject placement unit, 4: subject, 5: target normal passing through the focal center, 11: electron emission source, 12A, 12B: target, 12a : Target layer, 12b: support substrate, 13: focus, 13a: focus center, 14: apparent focus, 15: anode member, 16: cathode member, 17: insulating tube, 21: radiation detection element, 41: fluid, 42 : Container, 51: straight line connecting the center of the focus and the center of the radiation detection element at the lower end, 52: straight line connecting the center of the focus and the center of the radiation detection element at the upper end, 61: radiation detection device, 62: system control device, 63 : Display device, 65: Radiation generation tube control unit, 67: Signal processing unit, 68: Transport drive device, 211: Radiation detection element at the lower end, 212: Radiation detection element at the upper end

Claims (12)

A radiation generating tube having a target for generating radiation by electron irradiation;
A radiation detector having a plurality of rows of radiation detection elements that receive radiation from the radiation generating tube;
In a radiological examination apparatus comprising a subject placement unit capable of positioning a subject between the radiation generating tube and the radiation detector,
The radiation generating tube is arranged to emit the radiation with a predetermined radiation angle in the vertical direction, and
The radiation detector is arranged with the rows of the radiation detection elements oriented in the vertical direction,
The angle formed by the straight line connecting the center of the radiation detecting element located at the lower end and the focal center of the radiation generating tube and the normal of the electron irradiation surface of the target passing through the focal center is θ ₁ , and the radiation located at the upper end a straight line connecting the focal center of said radiation tube of the detecting element, the angle between the normal line forms when the theta _2, the radiation inspection apparatus which is a θ _1> θ _2.   The radiological examination apparatus according to claim 1, wherein the subject is a container containing a fluid, and the detection target is a foreign substance having a higher specific gravity than the fluid mixed in the container. The radiation inspection apparatus according to claim 1, wherein θ ₂ <θ ₁ <θ ₂ × 10 (where θ ₁ <90 °). The radiation inspection apparatus according to claim 1, wherein θ ₂ × 2 <θ ₁ <θ ₂ × 5 (where θ ₁ <90 °). The angle formed between the normal line and the surface of the radiation detection element in the column direction of the radiation detection element, the angle on the radiation detection element side at the lower end is φ ₁ , and the angle on the radiation detection element side at the upper end is φ ₂ The radiation inspection apparatus according to claim 1, wherein φ ₁ ≦ 90 ° and 45 ° ≦ φ ₁ ≦ 90 °. A radiation generating tube having a target for generating radiation by electron irradiation;
A radiation detector having a plurality of rows of radiation detection elements that receive radiation from the radiation generating tube;
In a radiological examination apparatus comprising a subject placement unit capable of positioning a subject between the radiation generating tube and the radiation detector,
The radiation generating tube is arranged to emit the radiation with a predetermined radiation angle in the vertical direction, and
The radiation detector is arranged with the rows of the radiation detection elements oriented in the vertical direction,
The angle formed by the straight line connecting the center of the radiation detecting element located at the lower end and the focal center of the radiation generating tube and the normal of the electron irradiation surface of the target passing through the focal center is θ ₁ , and the radiation located at the upper end A radiation inspection apparatus, wherein θ ₂ > θ _1, where θ ₂ is an angle formed by a straight line connecting the center of the detection element and the focal center of the radiation generating tube and the normal line.   The radiation inspection apparatus according to claim 3, wherein the subject is a container containing a fluid, and the detection target is a foreign substance having a specific gravity lower than that of the fluid mixed in the container. The radiation inspection apparatus according to claim 6, wherein θ ₁ <θ ₂ <θ ₁ × 10 (where θ ₂ <90 °). The radiation inspection apparatus according to claim 6, wherein θ ₁ × 2 <θ ₂ <θ ₁ × 5 (where θ ₂ <90 °).   The predetermined radiation angle is an angle in which the entire height direction of the subject located between the radiation generating tube and the radiation detector is included inside a radiation irradiation region of the radiation generating tube. The radiation inspection apparatus according to any one of claims 1 to 9.   The radiological examination according to claim 1, wherein the subject placement unit is capable of transporting the subject across the radiation generating tube and the radiation detector. apparatus.   The radiation inspection apparatus according to claim 1, wherein the radiation generation tube is a transmission type radiation generation tube.

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