Imaging unit, radiological image acquisition system and radiological image acquisition method

Abstract

The imaging unit includes a frame having an incident window through which radiation that has passed through an object is passed, a scintillator having an input surface that inputs the radiation that has passed through the incident window, and a line scan sensor having an imaging surface that images scintillated light output from the input surface. The imaging unit also includes a slit member disposed between the incident window and the scintillator that forms a slit that guides the radiation that has passed through the incident window toward the input surface, and an equal magnification lens disposed between the scintillator and the line scan sensor that images the scintillated light output from the input surface on the imaging surface of the line scan sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to an imaging unit, a radiological image acquisition system, and a radiological image acquisition method. BACKGROUND

[0002] Conventionally, there is known a radiological detection apparatus including a radiological source and a radiological detector that irradiates a subject conveyed on a conveyance path disposed therebetween with radiological rays, and converts the radiological rays that have passed through the subject into fluorescent rays (visible light) using a wavelength conversion member (see Patent Literature 1). In the radiological detection apparatus, the wavelength conversion member is supported by a support portion provided to a frame. The radiological rays that have passed through the subject pass through an opening portion formed in a shielding member, and are incident on a fluorescent layer of the wavelength conversion member. The fluorescent rays emitted from the fluorescent layer of the wavelength conversion member pass through a condenser, and are incident on a light-receiving portion of a photoelectric conversion element. The radiological detector generates and outputs a two-dimensional radiological image signal of the subject.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2018-14163 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the above-described conventional detector, there is a tendency that the radiological rays that have passed through the opening portion spread. Therefore, the irradiation range of the radiological rays in the input face of the wavelength conversion member (the base material layer of the wavelength conversion member in the above-described detector) becomes large, and as a result, the resolution becomes low. Further, since the working distance is long, the sensitivity becomes low.

[0008] The present application describes an imaging unit, a radiological image acquisition system, and a radiological image acquisition method that can improve the resolution and the sensitivity.

[0009] TECHNICAL MEANS FOR SOLVING THE PROBLEM

[0010] One embodiment of the present application is an imaging unit for acquiring a radiological image of a subject conveyed in a conveyance direction, including: a frame having an incident window through which radiological rays that have passed through the subject pass; a scintillator provided inside the frame, having an input face that inputs the radiological rays that have passed through the incident window; a line scan sensor provided inside the frame, having an imaging face that images scintillated light output from the input face; a slit member disposed between the incident window and the scintillator, forming a slit that guides the radiological rays that have passed through the incident window toward the input face; and an equal magnification lens disposed between the scintillator and the line scan sensor, imaging the scintillated light output from the input face on the imaging face of the line scan sensor.

[0011] According to the imaging unit, the radiations transmitted through the object enter the frame body through the entrance window of the frame body. The slit member in the frame body guides the radiations toward the input surface of the scintillator. At this time, the irradiation area of the radiations on the input surface of the scintillator is reduced (i.e., limited) by the slit of the slit member. Thus, the resolution can be improved. Since the equal magnification lens used in imaging of the scintillated light can shorten the working distance, the sensitivity can be improved. The equal magnification lens is disposed, for example, close to the input surface of the scintillator. Even in this case, since the irradiation area of the radiations is reduced by the slit, the influence of the scattered radiations is reduced.

[0012] Also, the slit member can be disposed with the slit in a direction inclined with respect to the normal direction of the input surface of the scintillator, and the equal magnification lens and the line scan sensor can image and capture the scintillated light output in the direction inclined with respect to the normal direction of the input surface. In this case, it is easy to make the equal magnification lens and the line scan sensor close to the input surface. From the viewpoints of improvement of the resolution and improvement of the sensitivity, desired imaging is possible.

[0013] The slit member can also be disposed with the slit extending obliquely with respect to the conveyance direction. When the slit is made to be oblique with respect to the conveyance direction, the optical path of the radiations transmitted through the object becomes long. As a result, the contrast of the acquired radiograph becomes high.

[0014] Also, the slit member can be disposed with the slit in a direction inclined with respect to the normal direction of the input surface of the scintillator, and the equal magnification lens and the line scan sensor can image and capture the scintillated light output in the direction inclined with respect to the normal direction of the input surface. In this case, it is easy to make the equal magnification lens and the line scan sensor close to the input surface.

[0015] Also, the frame body can have another entrance window through which the radiations transmitted through the object pass, and the imaging unit can further include another slit member disposed between the other entrance window and the scintillator to form another slit that guides the radiations that have passed through the other entrance window toward the input surface, and the slit member and the other slit member can be disposed with the slit and the other slit being directed toward the input surface of the scintillator from different two directions, respectively. The radiograph based on the radiations (incident radiations) guided from the different two directions becomes different images based on the difference in angle. Thus, various examination accuracies can be improved. For example, by using a mechanical shutter or the like, two kinds of images can be acquired at one time of imaging, and the examination time can also be shortened.

[0016] The imaging unit can also include a cover member that holds the slit member and is detachably attached to the frame. By preparing a plurality of cover members and a combination workpiece of the slit member held by the cover member in advance, the incident direction (incident angle) of the radiation with respect to the input surface of the scintillator can be easily changed by appropriately replacing the cover member.

[0017] The slit member can also be configured such that the width in the conveyance direction of the slit narrows as it approaches the input surface of the scintillator. In this case, since the entrance portion of the slit can be enlarged, the incident direction (incident angle) of the radiation with respect to the input surface of the scintillator can be changed, or the radiation can be guided to the input surface in a plurality of incident directions.

[0018] The slit member, the equal magnification lens, and the line scan sensor can also be rotatable within the frame about an axis extending along the input surface. In this case, the incident direction (incident angle) of the radiation with respect to the input surface of the scintillator can be easily changed. For example, by changing the incident direction of the radiation and performing imaging a plurality of times, various inspection accuracies can be improved.

[0019] As another aspect of the present application, a radiation image acquisition system that acquires a radiation image of an object can also be provided, and includes: a radiation source that outputs radiation toward the object; a conveyance device that conveys the object in a conveyance direction and allows the radiation to pass therethrough; and any of the above-described imaging units, disposed such that the radiation source and the incident window are on the same plane. According to this radiation image acquisition system, by virtue of the above-described effects, the resolution can be improved, and the sensitivity can also be improved.

[0020] In the radiation image acquisition system, the conveyance device and the slit member of the imaging unit can be disposed such that the slit extends obliquely with respect to the conveyance direction. When the slit is made to extend obliquely with respect to the conveyance direction, the optical path of the radiation that has passed through the object becomes longer. As a result, the contrast of the acquired radiation image becomes higher.

[0021] Another aspect of the present application is a radiation image acquisition method of acquiring a radiation image of an object, including: a radiation output step of outputting radiation toward an object conveyed along a conveyance direction; a radiation introduction step of introducing radiation that has passed through the object into a frame through an entrance window, and guiding the radiation toward an input surface of a scintillator by a slit formed in the frame; a scintillated light output step of inputting the radiation that has passed through the entrance window to the input surface of the scintillator, and outputting scintillated light from the input surface by converting the input radiation into the scintillated light; a scintillated light imaging step of imaging the scintillated light output from the input surface on an imaging surface of an online scanning sensor by an equal magnification lens; and a scintillated light imaging step of imaging the scintillated light on the imaging surface of the online scanning sensor.

[0022] According to the radiation image acquisition method, the radiation that has passed through the object enters the frame through the entrance window of the frame. The slit member in the frame guides the radiation toward the input surface of the scintillator. At this time, the irradiation area of the radiation on the input surface of the scintillator is reduced (i.e., limited) by the slit of the slit member. Thus, the resolution can be improved. Since the equal magnification lens used in the scintillated light imaging step can shorten the working distance, the sensitivity can be improved. The equal magnification lens is disposed close to the input surface of the scintillator, for example. Even in this case, since the irradiation area of the radiation is reduced by the slit in the radiation introduction step, the influence of the scattered radiation is reduced.

[0023] Also, in the radiation output step, the object can be conveyed along the conveyance direction multiple times, and in the multiple conveyances, the radiation can be output toward the object from different directions. In the radiation introduction step, the radiation can be guided toward the input surface of the scintillator from the multiple directions in the multiple conveyances. The radiation image acquisition method can further include an image processing step of performing image processing on multiple imaging images obtained in the scintillated light imaging step. The radiation image based on the radiation guided (i.e., introduced) from the multiple directions becomes different images based on the difference in the angle. Thus, the accuracy of various inspections can be improved.

[0024] Effects of the Invention

[0025] According to the aspects of the present application, the resolution can be improved, and the sensitivity can also be improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a perspective view showing a radiation image acquisition system according to an embodiment of the present application.

[0027] Figure 2 is a perspective view showing a radiation image acquisition system according to an embodiment of the present application. Figure 1 is a diagram showing the outline structure of the radiation image acquisition system shown in FIG. 1.

[0028] Figure 3 is a diagram showing the outline structure of the radiation image acquisition system shown in FIG. 1. Figure 1A cross-sectional view of the internal structure of the camera unit in the image.

[0029] Figure 4 It means Figure 1 A diagram showing the configuration of each part in the radiographic image acquisition system.

[0030] Figure 5 (a) and Figure 5 (b) is a diagram showing the configuration of various parts in various variations of a radiographic image acquisition system.

[0031] Figure 6 (a) and Figure 6 (b) is a diagram illustrating the difference in the angle of incidence of radiation relative to the object.

[0032] Figure 7 (a)~ Figure 7 (c) is a diagram showing the configuration of various parts in different variations of a radiographic image acquisition system.

[0033] Figure 8 (a) and Figure 8 (b) is a diagram showing the internal structure of various variations of a radiographic image acquisition system.

[0034] Figure 9 (a) and Figure 9 (b) is a diagram showing the internal structure of various variations of a radiographic image acquisition system.

[0035] Figure 10 (a)~ Figure 10 (c) is a diagram showing the sequence of illumination and imaging from multiple directions.

[0036] Figure 11 This is a diagram showing the configuration of various parts in a modified example of a radiographic image acquisition system.

[0037] Figure 12 This is a diagram showing the configuration of various parts in a modified example of a radiographic image acquisition system.

[0038] Figure 13 It means and Figure 12 A cross-sectional view of the internal structure of the camera unit corresponding to the modified example.

[0039] Figure 14 It is an enlarged representation Figure 13 A partial cross-sectional view.

[0040] Figure 15 (a) and Figure 15 (b) is a diagram showing the difference between the irradiated area and the imaging area caused by the presence or absence of the slit component.

[0041] Figure 16is a table showing measurement results of a scattering test of a radiation.

[0042] Figure 17 (a) ~ Figure 17 (c) are radiation images obtained in a photographing test using the samples, respectively.

[0043] Figure 18 (a) and Figure 18 (b) are radiation images obtained in a photographing test using the samples, respectively. DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment of the present application will be described with reference to the drawings. In addition, in the description of the drawings, the same elements are given the same symbols, and overlapping descriptions are omitted. Furthermore, each drawing is made for the purpose of explanation, and is depicted in a manner of particularly emphasizing an object portion to be described. Therefore, the dimensional ratios of the components in the drawings do not necessarily agree with those of the actual.

[0045] As shown in Figs. 1 and 2, a radiation image acquisition system 1 of an embodiment is an apparatus for acquiring a radiation image of an object A. The radiation image acquisition system 1 is a non-destructive inspection system capable of performing an inspection without disassembling or destroying the object A. The object A contains, for example, a substance composed of light elements. The radiation image acquisition system 1 is applicable, for example, to the fields of food inspection, battery inspection, or inspection of electronic components, and the like. In the field of food inspection, for example, it is inspected whether or not a foreign matter is mixed in a sealed container packaging. The radiation image acquisition system 1 is particularly excellent in the discrimination performance of a substance composed of light elements. As such a substance, for example, there can be mentioned a food fragment, hair, plastic, a worm, a bone in meat, and the like. The radiation image acquisition system 1 is applicable, for example, to an inline X-ray inspection. Figure 1 Figure 2 The radiation image acquisition system 1 includes a radiation source 2 that outputs a radiation such as white X-rays toward the object A, a conveyance device 20 that conveys the object A along a prescribed conveyance direction D, a scintillator 6 that generates scintillating light in accordance with an input of the radiation that has passed through the object A conveyed by the conveyance device 20, a line scan sensor 3 that detects the scintillating light output from an input surface 6a of the scintillator 6, and a computer 10 that controls a plurality of functions of the radiation image acquisition system 1 and creates a radiation image. Thus, the radiation image acquisition system 1 is an X-ray photographing system of a scintillator surface observation type. The radiation image acquisition system 1 is excellent in the sensitivity of X-rays of low energy.

[0046] The radiation image acquisition system 1 includes a radiation source 2 that outputs a radiation such as white X-rays toward the object A, a conveyance device 20 that conveys the object A along a prescribed conveyance direction D, a scintillator 6 that generates scintillating light in accordance with an input of the radiation that has passed through the object A conveyed by the conveyance device 20, a line scan sensor 3 that detects the scintillating light output from an input surface 6a of the scintillator 6, and a computer 10 that controls a plurality of functions of the radiation image acquisition system 1 and creates a radiation image. Thus, the radiation image acquisition system 1 is an X-ray photographing system of a scintillator surface observation type. The radiation image acquisition system 1 is excellent in the sensitivity of X-rays of low energy.

[0047] ​The radiation source 2 outputs a cone beam X-ray from the X-ray exit portion. The radiation source 2 has a focal point 2a of the cone beam X-ray. The radiation source 2 can be, for example, a microfocus X-ray source or a millimeter focus X-ray source. The X-ray emitted from the radiation source 2 forms a radiation beam. In the radiographic image acquisition system 1, the X-ray existing in the output region is input to the input surface 6a of the scintillator 6 through the line source side slit member 26 and the slit member 16 (refer to Figure 2 ), to the limited portion. The irradiation region 12 extends in a triangular shape (or a fan shape) toward the scintillator 6 in the frame 15 of the imaging unit 30.

[0048] The conveyance device 20 has, for example, two belt conveyors 21, 21 that move around a track, and the object A is placed or held on the conveyance surface 21a of the belt conveyor 21. The belt conveyor 21 is a conveyance table or a conveyance section. The conveyance device 20 includes a drive source not shown that drives each belt conveyor 21. The conveyance device 20 is configured to convey the object A at a certain speed in the conveyance direction D. In the present embodiment, the conveyance direction D is the horizontal direction. Between the two belt conveyors 21, 21, at a position corresponding to the irradiation region 12 described above, a gap C that allows the X-ray to pass through is provided. The gap C has a certain length (width) that is small in the conveyance direction D and extends straight in the detection width direction that is orthogonal to the conveyance direction D. The conveyance timing and the conveyance speed of the object A in the conveyance device 20 are set in advance and are controlled by the control section 10a of the computer 10. In addition, the belt conveyor 21 does not need to have the gap C that allows the X-ray to pass through, and the belt member of the belt conveyor 21 can be made of a material that has radiolucent properties.

[0049] In addition, the radiographic image acquisition system 1 can correspond to all types of conveyance devices 20. For example, the conveyance direction D can be horizontal, but can also be inclined with respect to the horizontal. The conveyance direction D can not be linear, and can be, for example, curved. In this case, the conveyance direction D can also be a tangent line to a portion of the conveyance path of the object A that overlaps the irradiation region 12. The conveyance device 20 can also not have a physical conveyance surface 21a. For example, the conveyance device 20 can also convey the object A in a state in which the object A is floating by air. Furthermore, the conveyance device 20 can convey the object A by dropping the object A into the air. In this case, the conveyance path of the object A can also be, for example, parabolic.

[0050] The conveying device 20 is not limited to having a belt conveyor 21. The conveying device 20 may also include, for example, a roller conveyor comprising multiple rollers. Since the roller conveyor does not have a belt, the influence of the belt can be eliminated. The presence of gaps (slit-shaped openings) between the rollers is also advantageous compared to a belt conveyor. By using a roller conveyor, X-ray attenuation caused by the belt is reduced. The roller conveyor can be effectively utilized when considering the configuration of the radiation source 2 and the configuration of the irradiation area 12 (oblique irradiation) described below. The roller conveyor is a suitable conveying mechanism for a radiation image acquisition system 1 where low-energy X-ray sensitivity is important. By providing two or more belt conveyors in the conveying direction as in this embodiment, and irradiating X-rays from the gap C between these belt conveyors, the belt conveyor 21 can be used and the influence of the belt can be eliminated.

[0051] like Figures 1-3 As shown, the radiographic image acquisition system 1 includes a camera unit 30 arranged along the conveyor 20. The camera unit 30 is mounted relative to the conveyor 20 and fixed to it. The camera unit 30 may also be mounted outside the conveyor 20. The camera unit 30 may also be placed on a stand or similar surface. The camera unit 30 is mounted in a manner that does not interfere with the surrounding area of ​​the belt conveyor 21. This is also true when the conveyor 20 is a roller conveyor. The camera unit 30 is arranged with a gap between it and the conveying section, such as a belt conveyor or roller conveyor, so as not to interfere with the movement of the conveying section.

[0052] The camera unit 30 has a rectangular frame 15. The frame 15 may have, for example, an aluminum rectangular frame body 13 and a lead shield 14 covering the outer surface (outer peripheral surface) of the frame body 13. The frame body 13 houses the various structures included in the camera unit 30 within an internal space 15S. The lead shield 14 shields radiation in a manner that prevents external radiation from the frame body 13 from affecting the internal space 15S of the camera unit 30. The lead shield 14 can be disposed on the outside or inside of the frame 15. Other shields may also be installed on the outside of the lead shield 14. From the viewpoint of the strength and handling of lead, it is preferable to install other materials on the outside of the lead shield. The shield material can be a substance other than lead, such as tungsten, iron, stainless steel, copper, etc. Furthermore, rubber-like materials or sheet materials containing heavy metals such as tungsten in rubber (resin) can also be used.

[0053] The frame body 13 is made of a material capable of shielding X-rays, for example. The frame body 13 can be made of iron or stainless steel, or the like. The frame body 13 can include a shielding material, and as the shielding material, lead, tungsten, or copper can be used. In addition, a rubber-like material or a sheet-like material containing heavy metals such as tungsten in rubber (resin) can also be used. The frame body 13 includes an upper wall portion 13a and a bottom wall portion 13d opposed in the up-down direction, a pair of first side wall portions 13b opposed in the conveyance direction D, and a pair of second side wall portions 13c opposed in a detection width direction orthogonal to the conveyance direction D. The size of the imaging unit 30 in the conveyance direction D of the frame body 13 is very small, and the device becomes compact. The conveyance direction D is parallel to the x direction shown in the drawing, which is parallel to the paper surface. The detection width direction is parallel to the y direction shown in the drawing, which is perpendicular to the paper surface. The up-down direction is parallel to the z direction shown in the drawing, which is parallel to the paper surface.

[0054] The upper wall portion 13a is disposed in opposition to the conveyance device 20. On the upper wall portion 13a, a top plate portion 14a of a lead cover 14 is installed at a distance from the upper wall portion 13a. The top plate portion 14a is disposed in parallel to the upper wall portion 13a. Between the upper wall portion 13a and the top plate portion 14a, an aluminum support plate portion 13e for supporting a slit member 16 described below is provided. In addition, as the support plate portion 13e for supporting the slit member 16, a metal such as stainless steel, iron, or the like can be used. On the outer side surfaces of the pair of first side wall portions 13b, a pair of first side plate portions 14b of the lead cover 14 are installed. On the outer side surfaces of the pair of second side wall portions 13c, a pair of second side plate portions (not shown) of the lead cover 14 are installed. The lead cover 14 covers the entire surface of the frame body 13 except for the bottom wall portion 13d. In addition, in the Figure 1 In the drawing of FIG. 6, the illustration of the first side plate portion 14b is omitted.

[0055] On the top plate portion 14a of the lead cover 14, an incident window 14f through which X-rays transmitted through the object A pass is formed. The incident window 14f has a slight length (width) in the x direction and extends straight in the y direction. The length of the incident window 14f in the x direction can be determined by the width of a slit S of the slit member 16 described below or the width (thickness in the conveyance direction D) of the desired irradiation region 12. The length of the incident window 14f in the x direction is constant in the detection width direction (y direction) and the thickness direction (z direction) of the top plate portion 14a.

[0056] On the support plate portion 13e, at a position corresponding to the incident window 14f, a through-hole 13g having a certain length (width) in the x direction and extending straight in the y direction is formed (refer to FIG. 6). Figure 3A slit member 16 for defining the irradiation area 12 is disposed and fixed within the through hole 13g. The slit member 16 includes a first slit plate 17 and a second slit plate 18 opposed to each other in the x-direction by a small interval. The first slit plate 17 and the second slit plate 18 are, for example, made of copper. The interval between the first slit plate 17 and the second slit plate 18 is equal to the width of the slit S formed by the slit member 16, for example, equal to the length (width) of the entrance window 14f in the x-direction. The width of the slit S may be slightly different from the length (width) of the entrance window 14f in the x-direction. With the upper end 16a of the slit member 16 inserted into the through hole 13g of the support plate portion 13e, the upper end 16a is fixed to the support plate portion 13e. The support plate portion 13e supports the slit member 16 in a manner that the slit S and the entrance window 14f are continuous. That is, the entrance end Sa of the slit S is directly (for example, without gaps) connected to the entrance window 14f. The two ends of the first slit plate 17 and the second slit plate 18 in the y direction can be open or closed by other copper plates, etc.

[0057] A slit member 16 is disposed within the frame 15. The slit member 16 is positioned between the entrance window 14f and the scintillator 6. The slit member 16 passes through the opening 13f formed in the upper wall portion 13a and hangs downwards toward the interior space 15S. The slit member 16 extends to the vicinity of the input surface 6a of the scintillator 6. The configuration of the slit member 16 and its positional relationship with the scintillator 6 will be described later. Alternatively, for example, if the top plate portion 14a is not provided, the upper end of the slit member 16 may protrude from the top surface of the frame 15, or it may protrude upwards from the frame 15. In this case, the upper end of the slit member 16 also serves as the entrance window.

[0058] like Figure 1 and Figure 2 As shown, a source-side slit component 26 is provided for the radiation source 2, defining an irradiation area 12. The source-side slit component 26, for example, has a pair of triangular copper plates. The pair of triangular copper plates are spaced apart in the x-direction to form a slit. The two ends of the source-side slit component 26 in the y-direction are closed, for example, by other copper plates. In the radiation image acquisition system 1, the components—the focal point 2a of the radiation source 2, the slit of the source-side slit component 26, the gap C of the conveying device 20, the entrance window 14f, and the slit S of the slit component 16—are arranged on the same plane. These components define (limit) the irradiation area 12 of X-rays, ensuring that only a portion of the X-rays output from the radiation source 2 passes through the object A and reaches the input surface 6a of the scintillator 6. The irradiation area 12 is, for example, a pyramidal region with a small thickness in the x-direction defined by the inner peripheral surface of the line source side slit member 26, the inner wall surface of the incident window 14f, and the inner wall surface of the slit member 16.

[0059] likeFigure 2 and Figure 3 As shown in FIG. 1, the slit member 16 guides the X-rays that have passed through the incident window 14f toward the input face 6a of the scintillator 6 with the slit S. With the slit member 16, scattering of the X-rays in the internal space 15S of the frame 15 is prevented. The input face 6a of the scintillator 6 inputs the X-rays that have passed through the irradiation region 12 of the slit member 16. In addition, the "input face 6a of the scintillator 6" refers only to the region that effectively acts on the output of the scintillated light. For example, a region covered by the scintillator holder and the like in the entire rectangular input face 6a is not included in the "input face 6a of the scintillator 6".

[0060] In the radiographic image acquisition system 1, the imaging unit 30 is configured to be able to image the scintillated light that is output from the input face 6a of the scintillator 6 toward a direction that is inclined with respect to the input face 6a. The scintillator 6, the line scan sensor 3, and the equal magnification lens 7 are provided within the frame 15. Further, the shielding member 9 is installed between the line scan sensor 3 and the equal magnification lens 7. The line scan sensor 3, the shielding member 9, and the equal magnification lens 7 are integrated. The line scan sensor 3, the shielding member 9, and the equal magnification lens 7 are held in the internal space 15S by a bracket or the like (not shown).

[0061] The scintillator 6 is held by a scintillator holder (not shown), for example, and is arranged horizontally, for example. The scintillator 6 is a wavelength conversion member that is flat. The scintillator 6 is a long rectangular shape (see FIG. 2) that is long in the detection width direction (y direction). Figure 1 The scintillator 6 is composed of Gd2O2S:Tb, Gd2O2S:Pr, CsI:Tl, CdWO4, CaWO4, Gd2SiO5:Ce, Lu 0.4 Gd 1.6 SiO5, Bi4Ge3O 12 , Lu2SiO5:Ce, Y2SiO5, YAlO3:Ce, Y2O2S:Tb, YTaO4:Tm, YAG:Ce, YAG:Pr, YGAG:Ce, YGAG:Pr, GAGG:Ce, and the like. The thickness of the scintillator 6 is set to an appropriate value by the energy band of the X-rays detected in the range of several μm to several mm. The scintillator 6 converts the X-rays that have passed through the object A into visible light. The X-rays of lower energy are converted by the input face 6a of the scintillator 6 and are output from the input face 6a.

[0062] The line scan sensor 3 captures an image in accordance with the movement of the object A, and outputs one-dimensional image data, i.e., radiation image data. The line scan sensor 3 has an imaging surface 3a that captures scintillated light output from the input surface 6a of the scintillator 6. The line scan sensor 3 is, for example, a general line sensor, a multi-line sensor, or a region image sensor capable of TDI (Time Delay Integration) driving. The line scan sensor 3 is, for example, a CCD image sensor or a CMOS image sensor. The line scan sensor 3 has a structure in which a plurality of light-receiving elements are arranged in a column in a pixel direction, and a plurality of columns are arranged in a column direction in accordance with the movement direction of the object A. The line scan sensor 3 has a scanning direction corresponding to the conveyance direction D of the object A, and a line direction orthogonal to the scanning direction. The line direction is the pixel direction described above, and is parallel to the y direction in FIG. 1. Further, the scanning direction corresponds to the column direction described above, and is parallel to the z direction in FIG. 1. In the case of the region image sensor capable of TDI driving, the column direction becomes the same direction as the integration direction. Figure 2 Figure 2

[0063] The line scan sensor 3 captures an image of the object A in accordance with the movement of the object A by the control section 10a. That is, the line scan sensor 3 captures an image on the imaging surface 3a in synchronization with the movement of the object A by the conveyance device 20, and outputs radiation image data. Thus, a radiation image with a good S / N ratio can be obtained. Further, in order to synchronize the movement of the object A by the stage with the capturing of the line scan sensor, an encoder can be provided to the stage, and the line scan sensor 3 can be controlled using a signal from the encoder.

[0064] The scintillator 6 of the present embodiment is arranged so that the input surface 6a is parallel to the conveyance direction D and parallel to the line direction described above. That is, the input surface 6a of the scintillator 6 is parallel to the xy plane.

[0065] The equal magnification lens 7 is arranged between the scintillator 6 and the line scan sensor 3, and images the scintillated light output from the input surface 6a on the imaging surface 3a of the line scan sensor 3. The equal magnification lens 7 is a lens with a magnification of 1, and can be implemented by, for example, a refractive index distribution type lens (GRIN lens), or a rod lens, a rod lens array, or the like. The focal point of the equal magnification lens 7 is aligned with the input surface 6a of the scintillator 6. The equal magnification lens 7 has a deep depth of field, and thus even if the fluorescent screen is captured obliquely, the defocus is small, and is favorably used in the oblique capturing of the present embodiment. Further, the equal magnification lens 7 improves the degree of freedom of the arrangement of the radiation source 2, the object A, and the line scan sensor 3.

[0066] ​​The shielding component 9 is a radiation shielding component that allows the scintillation light generated by the scintillator 6 and focused by the equal-magnification lens 7 to pass through, thereby shielding X-rays. The shielding component 9 is, for example, lead-containing glass, or lead-free radiation shielding glass containing heavy elements such as Sr, Ba, Ti, B, W, Si, Gd, and Zr, FOP (fiber optic plate), or radiation shielding resin. The shielding component 9 is mounted on the surface of the line scan sensor 3 (the surface of the protective resin). The shielding component 9 reduces the influence of scattered X-rays.

[0067] like Figure 3 As shown, in the imaging unit 30 of the radiation image acquisition system 1, the slit member 16 is arranged such that the slit S is located in the direction of the normal B of the input surface 6a of the scintillator 6. The equal-magnification lens 7, the shielding member 9, and the line scan sensor 3 are arranged in a direction inclined relative to the normal B of the input surface 6a. The equal-magnification lens 7 images the scintillation light output in the direction inclined relative to the normal B of the input surface 6a onto the imaging surface 3a. The line scan sensor 3 images the scintillation light output in the direction inclined relative to the normal B of the input surface 6a.

[0068] The exit end Sb of the slit S formed by the slit member 16 is close to the input surface 6a of the scintillator 6. Furthermore, the front end surface 7a of the equal-magnification lens 7 is close to the input surface 6a of the scintillator 6. In the imaging unit 30, the components are arranged such that the slit member 16 and the equal-magnification lens 7 are as close as possible to the input surface 6a of the scintillator 6. The slit member 16 extends to a position close to the input surface 6a of the scintillator 6 to a degree that does not obstruct the imaging of the scintillating light performed by the line scan sensor 3 and the equal-magnification lens 7. The distance from the exit end Sb of the slit S to the input surface 6a of the scintillator 6 is preferably less than 20 mm, for example. The shorter the distance from the exit end Sb of the slit S to the input surface 6a of the scintillator 6, the better; preferably less than 5 mm. Additionally, the lower ends of the two slit plates do not need to be aligned, and the distances from the scintillator can differ between the slit plate on the side of the equal-magnification lens 7 (first slit plate) and the slit plate on the opposite side (second slit plate).

[0069] The equal-magnification lens 7 is configured such that its front end surface 7a does not interfere with the scintillator 6 and the slit component 16, and faces the illumination area 12 on the scintillator 6 (see reference). Figure 15 (a) Approaching the irradiated area 12.

[0070] The computer 10 has, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. The computer 10 has a control section 10a (control processor) that controls the radiation source 2 and the line scan sensor 3, and an image processing section 10b (image processing processor) that creates a radiation image of the object A on the basis of radiation image data output from the line scan sensor 3. The image processing section 10b inputs the radiation image data and performs a prescribed process such as image processing on the input radiation image data. The display device 11 is connected to the computer 10. The image processing section 10b outputs the created radiation image to the display device 11. The control section 10a controls the radiation source 2 on the basis of values of a tube voltage and a tube current of the radiation source 2 stored through input by a user or the like. The control section 10a controls the line scan sensor 3 on the basis of an exposure time or the like of the line scan sensor 3 stored through input by a user or the like. The control section 10a and the image processing section 10b can be different processors or can be the same processor. Further, the computer 10 can be programmed to be able to perform the functions of the control section 10a and the functions of the image processing section 10b. In addition, the computer 10 can be constituted by a microcomputer, an FPGA (Field Programmable Gate Array).

[0071] Next, the operation of the radiation image acquisition system 1, that is, the method of acquiring a radiation image, will be described. First, the object A is conveyed in the conveyance direction D using the conveyance device 20 (conveyance process). At the same time, radiation such as white X-rays is output from the radiation source 2 toward the object A (radiation output process). Next, the radiation that has passed through the object A is made to enter the frame 15 through the entrance window 14f, and the radiation is guided toward the input surface 6a of the scintillator 6 using the slit S formed in the frame 15 (radiation introduction process). The radiation that has passed through the object A is input to the input surface 6a, and conversion from the radiation to scintillating light is performed by the scintillator 6, and the scintillating light is output from the input surface 6a (scintillating light output process). Then, the scintillating light output from the input surface 6a is imaged on the imaging surface 3a of the line scan sensor 3 by the equal magnification lens 7 (scintillating light imaging process). Further, the scintillating light is imaged on the imaging surface 3a of the line scan sensor 3 (scintillating light imaging process). The line scan sensor 3 outputs radiation image data obtained by the imaging to the image processing section 10b of the computer 10.

[0072] The image processing section 10b of the computer 10 inputs the radiation image data and performs a prescribed process such as image processing on the input radiation image data, and creates a radiation image (image creation process). The image processing section 10b outputs the created radiation image to the display device 11. The display device 11 displays the radiation image output from the image processing section 10b. Through the above processes, a radiation image based on surface observation of the object A is obtained.

[0073] According to the imaging unit 30, radiation image acquisition system 1, and radiation image acquisition method of this embodiment, radiation passing through the object A enters the frame 15 through the entrance window 14f. The slit member 16 within the frame 15 guides the radiation toward the input surface 6a of the scintillator 6. At this time, the irradiation area 12 of the radiation on the input surface 6a of the scintillator 6 is reduced (i.e., restricted) by the slit S of the slit member 16. Figure 15 (a) indicates the irradiation area 12 when the slit component 16 is provided. Figure 15 (b) shows the irradiation area 12 without the slit component 16. From Figure 15 (a) and Figure 15 (b) It can be seen that the illumination area 12 on the input surface 6a of the scintillator 6 is limited to a narrower area by providing the slit component 16. Therefore, the imaging area of ​​the equal-magnification lens 7 is also... Figure 15 (a) The illumination area 12 shown is also a narrow area. When the illumination area 12 of the radiation on the input surface 6a of the scintillator 6 is wide, crosstalk (hybridization) of the fluorescence emitted on the scintillator 6 causes a decrease in resolution. In addition, a decrease in resolution occurs due to the influence of scattered rays, etc. By reducing the illumination area 12 of the radiation, the decrease in resolution caused by crosstalk and scattered rays can be prevented. Therefore, by reducing the illumination area 12 in this way, the resolution can be improved. Since the equivalent magnification lens 7 used in the scintillation imaging process can shorten the working distance, the sensitivity can be improved. The equivalent magnification lens 7 is arranged close to the input surface 6a of the scintillator 6. Even in this case, since the illumination area 12 of the radiation is reduced by the slit S in the radiation introduction process, the influence of scattered radiation is reduced. The slit member 16 also has the effect of preventing the line scan sensor 3 and the equivalent magnification lens 7 from being irradiated. In the imaging unit 30, the compactness of the unit is achieved by applying the slit member 16 and the equivalent magnification lens 7.

[0074] like Figure 4 As shown, the slit component 16 is configured such that the slit S is located in the direction of the normal B of the input surface 6a of the scintillator 6. The equal-magnification lens 7 and the line scan sensor 3 image and capture the scintillating light output in a direction inclined relative to the normal B of the input surface 6a. This structure facilitates the proximity of the equal-magnification lens 7 and the line scan sensor 3 to the input surface 6a. From the viewpoint of improved resolution and sensitivity, the desired image capture is possible.

[0075] Furthermore, since the online scanning sensor 3 is equipped with a shielding component 9, it has the effect of suppressing scattered X-rays. Figure 16is a table showing measurement results of a scattering test of a radiation. In this test, a lead cover 14 is provided around the frame main body 13 including the vicinity of the incident window 14f. In Embodiments 1 and 2 in which a copper plate slit portion having the same structure as the slit member 16 is provided and Comparative Example in which the copper plate slit portion is not provided, the number of pixels of scattered X-rays is measured. As shown in Figure 16 (a) and

[0076] The radiation image acquisition system and the imaging unit of the present application can be adopted in various modified manners in addition to the manner shown in Figures 2-4 Hereinafter, the modified manners of the present application will be described with reference to the drawings. In the following description, although the illustration of the shielding member 9 is omitted, the shielding member 9 can be provided in any of the modified manners as well as in the imaging unit 30.

[0077] For example, as shown in Figure 5 (a), the slit member 16 can be configured so that the slit S extends obliquely with respect to the conveyance direction D. In the radiation image acquisition system 1A and the imaging unit 30A, the slit member 16 is configured so that the slit S is located in a direction oblique with respect to the normal line B of the input face 6a of the scintillator 6, and the equal magnification lens 7 and the line scan sensor 3 image and capture the scintillated light output in the direction of the normal line B of the input face 6a. As shown in Figure 6 (a) and Figure 6 (b), by making the slit S oblique with respect to the conveyance direction D, the optical path of the radiation that has passed through the object A can be lengthened. In the case where the object A has a certain thickness (thickness in the direction orthogonal to the conveyance face 21a), the optical path length Lb shown in Figure 6 (b) is longer than the optical path length La shown in Figure 6 (a). As a result, the contrast of the acquired radiation image becomes higher.

[0078] Further, as shown in Figure 5 (b), the slit member 16 can be configured so that the slit S extends obliquely with respect to the conveyance direction D. In the radiation image acquisition system IB and the imaging unit 30B, the slit member 16 is configured so that the slit S is located in a direction oblique with respect to the normal line B of the input face 6a of the scintillator 6, and the equal magnification lens 7 and the line scan sensor 3 also image and capture the scintillated light output in the direction oblique with respect to the normal line B of the input face 6a. In this case as well, the contrast of the acquired radiation image becomes higher.

[0079] Figure 17 (a) ~ Figure 17 (c) are test results of a test of mixing of foreign matter F (hair or the like) in a seal portion of a plastic bag that packages a snack. As shown in the image of Figure 17 (a), in a case where the slit member 16 is not provided, the foreign matter F cannot be visually confirmed, but as shown in the image of Figure 17 (b), in a case where the slit member 16 is provided, perpendicular incidence of X-rays as shown in Figure 4 is performed, the foreign matter F is confirmed. Further, as shown in the image of Figure 17 (c), in a case where the slit member 16 is provided, oblique incidence of X-rays as shown in Figure 5 is performed, the foreign matter F is also confirmed. In addition, in the images of Figure 17 (b) and Figure 17 (c), by lowering the tube voltage of the radiation source 2 to 25 kV and increasing the tube current to 25 mA, the contrast in the images is clear (100 kV, 15 mA in Figure 17 (a), respectively).

[0080] Figure 18 (a) and Figure 18 (b) are test results of a test of mixing of foreign matter in a seal portion of a plastic bag that packages a snack. As shown in the image of Figure 18 (a), in a case where the slit member 16 is provided, perpendicular incidence of X-rays as shown in Figure 4 is performed, a large packaging bag P1 and a small packaging bag P2 housed inside thereof (the sugar inside is colored in black) are confirmed. Further, as shown in the image of Figure 18 (b), in a case where the slit member 16 is provided, oblique incidence of X-rays as shown in Figure 5 is performed, the large packaging bag P1, the small packaging bag P2 housed inside thereof, and the concave-convex of the seal portion P3 of a larger packaging bag P1 are also confirmed.

[0081] As shown in Figure 7 (a), the slit member 16 can also be disposed in a manner that the slit S extends obliquely with respect to the conveyance direction D. In this radiographic image acquisition system 1C and the imaging unit 30C, the conveyance direction D is oblique with respect to the normal B direction of the input face 6a of the scintillator 6. The slit member 16 is disposed in a manner that the slit S is located in the normal B direction of the input face 6a of the scintillator 6, and the equal-magnification lens 7 and the line scan sensor 3 image and capture the scintillated light that is output in a direction oblique with respect to the normal B of the input face 6a. In this case, the contrast of the acquired radiographic image also becomes high. In Figure 7(b) The radiation image acquisition system 1D and camera unit 30D shown differ from the radiation image acquisition system 1C and camera unit 30C in that the orientation of the conveying surface 21a is not changed, but the orientation of the radiation source 2 and camera unit 30D is tilted. In other respects, they are the same as the radiation image acquisition system 1C and camera unit 30C. Furthermore, in Figure 7 In the radiation image acquisition system 1E and camera unit 30E shown in (c), the orientation of the object A is tilted only on the conveying surface 21a.

[0082] like Figure 8 As shown in (a), the slit member 16 can also be configured such that the width of the slit S in the transport direction D narrows as it approaches the input surface 6a of the scintillator 6. In this radiation image acquisition system 1F and imaging unit 30F, the opening of the slit member 16 is enlarged by a pair of tapered first slit plates 17 and second slit plates 18, enabling both vertical and oblique incidence of X-rays within a frame 15. Furthermore, an angle display 40 can be installed within the frame 15 to facilitate visual confirmation of the angle of oblique incidence. The equal-magnification lens 7 and the line scan sensor 3 image and capture the scintillation light output in a direction oblique to the normal B relative to the input surface 6a. Thus, since the entrance portion of the slit S can be enlarged, the incident direction (incident angle) of the radiation relative to the input surface 6a of the scintillator 6 can be changed, or the radiation can be guided to the input surface 6a in multiple incident directions. For the oblique incidence of X-rays, additional entrance windows 14g can be formed in the frame 15, for example, to allow the radiation that has passed through the object A to pass through. The entrance windows 14g can also be formed in conjunction with the configuration of the second slit plate 18 (defining the oblique surface of the slit S). Appropriate opening and closing mechanisms for the entrance windows 14f and 14g can also be provided. These opening and closing mechanisms can operate in conjunction with the imaging timing of the line scan sensor 3.

[0083] like Figure 8 As shown in (b), the slit component 16, the equal-magnification lens 7, and the line scan sensor 3 can also rotate within the housing 15 about an axis L extending along the input surface 6a. In this radiation image acquisition system 1G and imaging unit 30G, after fixing the angle between the irradiation area 12 of the radiation source 2 and the optical axis E of the line scan sensor 3, their angles relative to the input surface 6a can be easily changed. Therefore, a rotation mechanism 50 is provided that allows the equal-magnification lens 7 and the line scan sensor 3 to rotate about the axis L. That is, the incident direction (incident angle) of the radiation relative to the input surface 6a of the scintillator 6 can be easily changed. For example, by changing the incident direction of the radiation and performing multiple imaging operations, the accuracy of various inspections can be improved.

[0084] like Figure 9(a) shown, the imaging unit 30H can also include a cover member 43 that holds the slit member 16 and is attached to the frame in a detachable manner. In this radiographic image acquisition system 1H and the imaging unit 30H, the slit member 16 is fixed to the L-shaped cover member 43 in a manner that the slit S faces the normal line B direction of the input surface 6a. By attaching the unit 45H that integrates them to the frame 15, the same imaging as Figure 4 (a) shown can be performed. On the other hand, as Figure 9 (b) shown, the imaging unit 30J can also include a cover member 44 that holds the slit member 16 and is attached to the frame in a detachable manner. In this radiographic image acquisition system 1J and the imaging unit 30J, the slit member 16 is fixed to the L-shaped cover member 44 in a manner that the slit S faces a direction that is inclined with respect to the normal line B of the input surface 6a. By attaching the unit 45J that integrates them to the frame 15, the same imaging as Figure 5 (b) shown can be performed. In this way, by preparing a plurality of cover members and the combined work of the slit member 16 held by the cover member in advance, the replacement is appropriately performed, and the incident direction (incident angle) of the radiographic rays with respect to the input surface 6a of the scintillator 6 can be easily changed. For example, by changing the incident direction of the radiographic rays and performing imaging a plurality of times, the accuracy of various inspections can be improved.

[0085] Alternatively, as Figure 10 (a) to Figure 10 (c) shown, the imaging of the radiographic image acquisition system 1K and the imaging unit 30K that are configured the same as Figure 4 the radiographic image acquisition system 1L and the imaging unit 30L that are configured the same as Figure 5 (a), and the radiographic image acquisition system 1M and the imaging unit 30M that are combined after the configuration of the slit member 16 with respect to the normal line B of the input surface 6a is symmetrical to the radiographic image acquisition system 1L and the imaging unit 30L can be performed. That is, it is also possible that, in the radiographic ray outputting process, the object A is conveyed a plurality of times in the conveyance direction D, and in the plurality of conveyances, the radiographic rays are outputted toward the object A from different directions, and in the radiographic ray introduction process, the input surface 6a of the scintillator 6 is guided by the radiographic rays from a plurality of directions in the plurality of conveyances. In this case, the radiographic image acquisition method can also include an image processing process of performing image processing on a plurality of imaging images obtained in the scintillated light imaging process. The radiographic images based on the radiographic rays guided (incident) from a plurality of directions become different images based on the difference in the angle. Thereby, the accuracy of various inspections can be improved. By increasing the combination, imaging like CT imaging is also possible. In the different radiographic ray sources 2, 2A, the tube voltage can also be changed.

[0086] Further, as Figure 11As shown, the frame 15 may also have other entrance windows 14g that allow radiation passing through the object A to pass through. The imaging unit 30N also includes other slit components 16A, which are disposed between the other entrance windows 14g and the scintillator 6, forming other slits SA that guide the radiation passing through the other entrance windows 14g toward the input surface 6a. The slit components 16 and other slit components 16A are configured such that the slits SA and other slits guide the radiation from two different directions relative to the input surface 6a of the scintillator 6. The radiation images based on the (incident) radiation guided from the two different directions become different images based on the different angles. This can improve various inspection accuracies. For example, by using mechanical shutters 41 and 42, which are made of lead plates or the like, two images can be acquired in one shot, which can also shorten the inspection time. For example, the mechanical shutters 41 and 42 can be synchronized with the shutter of the line scan sensor 3. An opening and closing mechanism can be configured to open and close the entrance windows 14f and 14g, and this mechanism can operate in conjunction with the opening and closing timing of the mechanical shutters 41 and 42 (based on the imaging timing of the line scan sensor 3). By adding combinations, imaging similar to CT imaging is also possible. The tube voltage can also be changed in different radiation sources 2 and 2A.

[0087] In addition, such as Figure 12 As shown, the scintillator 6 can also be arranged at an angle within the housing 15. In this radiation image acquisition system 1P and imaging unit 30P, the slit member 16 is arranged such that the slit S is tilted relative to the normal B of the input surface 6a of the scintillator 6. The equal-magnification lens 7 and the line scan sensor 3 also image and capture the scintillating light output in the direction tilted relative to the normal B of the input surface 6a. This structure also facilitates the proximity of the equal-magnification lens 7 and the line scan sensor 3 to the input surface 6a.

[0088] As explained above, X-ray images differ under perpendicular and oblique incidence. Under perpendicular incidence, there are observable and unobservable phenomena, while under oblique incidence, there are both observable and unobservable phenomena. Furthermore, even with oblique incidence, the image differs depending on the angle (direction) of the X-ray incidence relative to the object A. By processing these images, the accuracy of various examinations is improved. Combinations of perpendicular and oblique incidence, as shown in the various variations above, allow for combinations of infinitely close types by employing all methods.

[0089] Reference Figure 13 and Figure 14A specific configuration example of the imaging unit 30R that images the scintillated light output in the direction inclined with respect to the input surface 6a of the scintillator 6 from the direction in which the radiation is incident, the equal magnification lens 7, and the line scan sensor 3 will be described. Figure 13 is a cross-sectional view that shows an internal configuration example of the imaging unit 30R. Figure 14 is a cross-sectional view that shows a part of Figure 13 enlarged. Figure 13 The imaging unit 30R shown in Figure 12 has the same structure as the imaging unit 30P shown in

[0090] The imaging unit 30R is configured to be able to image the scintillated light output in the direction inclined with respect to the input surface 6a of the scintillator 6 from the input surface 6a. The scintillator 6, the line scan sensor 3, and the equal magnification lens 7 are provided inside the frame body 15. The equal magnification lens 7 is disposed between the scintillator 6 and the line scan sensor 3. The imaging unit 30R has a configuration for holding the scintillator 6, the line scan sensor 3, and the equal magnification lens 7 in a prescribed positional relationship.

[0091] As shown in Figure 13 and Figure 14 , the imaging unit 30R includes a holding member 60 that holds the equal magnification lens 7 and the line scan sensor 3, a positioning member 70 that positions the scintillator 6, and a support member 80 that is fitted to the positioning member 70 and supports the scintillator 6. The holding member 60, the positioning member 70, and the support member 80 are attached to the frame body 13 of the frame body 15 and fixed at prescribed positions. Hereinafter, the structures of the scintillator 6, the line scan sensor 3, and the equal magnification lens 7 and the structures for holding these parts will be described.

[0092] As shown in Figure 13 , the holding member 60 is housed inside the frame body 13. The holding member 60 has a positioning portion 61 that functions as a guide. Further, the holding member 60 holds the equal magnification lens 7 in the positioning portion 61 of the holding member 60 that faces the scintillator 6. Further, the holding member 60 holds the line scan sensor 3 in a base end portion 65 on the opposite side from the positioning portion 61. The holding member 60 holds the equal magnification lens 7, for example, in such a manner that a front end surface (one end surface) 7a of the equal magnification lens 7 is orthogonal to the x direction. The holding member 60 holds the line scan sensor 3, for example, in such a manner that an imaging surface 3a of the imaging portion 31 is orthogonal to the x direction. As shown in Figure 14 , the imaging portion 31 of the line scan sensor 3 is held to the main body portion 32 attached to the base portion 33. A part of the base portion 33 and the main body portion 32 are fitted into the base end portion 65 of the holding member 60.

[0093] As Figure 13 and Figure 14 shown, the positioning member 70 is assembled to the frame body main body 13 at a position directly below the incident window 14f. The positioning member 70 is made of metal such as copper, for example. The positioning member 70 has a first through-hole 74 through which radiation passes and a second through-hole 75 through which scintillating light converted by the scintillator 6 and output from the scintillator 6 passes. The first through-hole 74 is formed along the yz plane, for example, and the second through-hole 75 is formed along the xy plane, for example. The lengths of the first through-hole 74 and the second through-hole 75 in the y direction are longer than the length of the scintillator 6 in the y direction. The first through-hole 74 and the second through-hole 75 communicate in a space extending in the y direction. The positioning member 70 has a mounting surface 77 extending in a manner inclined with respect to the first through-hole 74, that is, the passage path of radiation. The mounting surface 77 is inclined at 45° with respect to the xy plane, for example. The scintillator 6 is pressed against the mounting surface 77 by a support member 80. In this mounting surface 77, a space in which the first through-hole 74 and the second through-hole 75 intersect is open. The input surface 6a of the scintillator 6 faces this opening 70d. By appropriately setting the inclination angle of the mounting surface 77, the angle of the input surface 6a with respect to radiation input to the input surface 6a and the angle of the input surface 6a with respect to the imaging surface 3a are determined. The inclination angle (45°) of the above-described mounting surface 77 is merely an example, and the mounting surface 77 can also be inclined at another angle with respect to the xy plane.

[0094] The first through-hole 74 forms a slit that is a passage path of radiation. The incident window 14f of the top plate portion 14a, the through-hole 13g of the support plate portion 13e, and the opening 13f of the upper wall portion 13a have a certain length in the x direction and are arranged in the z direction. The first through-hole 74 is arranged in line with the incident window 14f, the through-hole 13g, and the opening 13f. The first through-hole 74 guides X-rays that have passed through the incident window 14f toward the input surface 6a of the scintillator 6. With the positioning member 70, scattering of X-rays in the internal space of the frame 15 is prevented. The input surface 6a of the scintillator 6 inputs X-rays (radiation) within the irradiation region 12 (refer to Figure 12 ) that have passed through the first through-hole 74 of the positioning member 70.

[0095] Although the equal magnification lens 7 has a publicly known structure, the following describes important characteristic portions in the imaging unit 30R. The equal magnification lens 7 has a rectangular parallelepiped shape. The equal magnification lens 7 has, for example, a configuration in which a plurality of cylindrical lens bodies (lenses) 8 arranged in a line are held by a lens holding portion 7b. The equal magnification lens 7 images the scintillating light output in the direction oblique to the normal direction of the input face 6a of the scintillator 6 and the imaging face 3a of the line scan sensor 3, respectively, by the lens bodies 8 arranged in an array. The front end face 7a and the base end face (the other end face) 7c in the direction of the lens length of the equal magnification lens 7 are parallel to each other and become flat faces, respectively. The both end faces of the lens bodies 8 are exposed to the front end face 7a and the base end face 7c and are the same as the both end faces of the lens holding portion 7b. In the equal magnification lens 7, the adjacent lens bodies 8 are arranged so as to overlap the images. Since the lens bodies 8 are arranged in an array, the brightness is not different at the center portion and the end portions of the array, and in addition, lens distortion at the end portions is not generated. In the equal magnification lens 7, the working distance on the side of the front end face 7a and the working distance on the opposite side correspond to the distance from the input face 6a to the front end face 7a and the distance from the base end face 7c to the imaging face 3a, respectively, as shown in FIG. 6. That is, the conjugate length of the equal magnification lens 7 corresponds to the distance from the input face 6a to the imaging face 3a. Figure 14 The distance from the input face 6a to the front end face 7a and the distance from the base end face 7c to the imaging face 3a are equal to each other. That is, the conjugate length of the equal magnification lens 7 corresponds to the distance from the input face 6a to the imaging face 3a.

[0096] Returning to Figure 14 In the imaging unit 30R, the passing path of the radiation formed by the first through-hole 74 is arranged so as to be oblique to the normal direction of the input face 6a of the scintillator 6. The equal magnification lens 7, the shielding member 9, and the line scan sensor 3 are arranged in the direction oblique to the normal direction of the input face 6a. The equal magnification lens 7 images the scintillating light output in the direction oblique to the normal direction of the input face 6a on the imaging face 3a. The line scan sensor 3 images the scintillating light output in the direction oblique to the normal direction of the input face 6a.

[0097] The shielding member 9 is, for example, a plate-like member provided on the line scan sensor 3, but can be a block-like member provided in the space between the imaging face 3a of the line scan sensor 3 and the base end face 7c of the equal magnification lens 7. That is, a gap can be formed between the shielding member 9 and the equal magnification lens 7, but can not exist.

[0098] The positioning member 70 has a stopper plate portion 79 that contacts the side surface of the frame body 13 and a main body portion 70a that is disposed inside the frame body 13. The first through-hole 74 and the second through-hole 75 are formed in the main body portion 70a. The main body portion 70a is disposed between the incident window 14f and the scintillator 6 and is a slit member that forms a slit that guides the radiation that has passed through the incident window 14f toward the input surface 6a. A recess 70c, for example, in a rectangular shape is formed in the main body portion 70a, and the positioning portion 61 of the holding member 60 is fitted in the recess 70c. In this way, the positioning member 70 that is fixed with respect to the frame body 13 has the holding member 60 fitted and fixed inside the frame body 13.

[0099] The positioning member 70 has a first positioning portion 71 that contacts the input surface 6a of the scintillator 6 to position the scintillator 6. The first positioning portion 71 is formed as a part of the mounting surface 77 described above and has a flat surface. The first positioning portion 71, for example, makes surface contact with the input surface 6a of the scintillator 6.

[0100] The support member 80 that is fitted in the positioning member 70 supports the scintillator 6. The support member 80 has a support surface 82 that opposes the mounting surface 77 in which the first positioning portion 71 is formed. The inclination angle of the support surface 82 is equal to the inclination angle of the mounting surface 77, and thus the support surface 82 is parallel to the mounting surface 77. The support member 80 sandwiches the scintillator 6 between the mounting surface 77 and the support surface 82. The support member 80 is fixed to the positioning member 70 by a suitable fixing mechanism such as a screw or a bolt in a manner that allows adjustment of the interval 89 (the distance in the normal direction of the support surface 82) between the mounting surface 77 and the support surface 82.

[0101] The positioning member 70 has a second positioning portion 72 that contacts the front end surface 7a of the magnification lens 7 to position the imaging surface 3a. The second positioning portion 72 is formed as a part of the side surface 76 that opposes the holding member 60 and has a flat surface. The second positioning portion 72, for example, makes surface contact with the front end surface 7a of the magnification lens 7.

[0102] According to the imaging unit 30R, the positioning member 70 that is a single member positions the scintillator 6 by the first positioning portion 71 and positions the magnification lens 7 by the second positioning portion 72. Since the input surface 6a of the scintillator 6 contacts the first positioning portion 71, the positional accuracy of the input surface 6a can be easily ensured, for example, even in the case where the thickness of the scintillator 6 varies. Thus, the distance between the line scan sensor 3 and the input surface 6a of the scintillator 6 can be maintained constant. This structure does not need to consider the positional accuracy of different members and brings an advantage compared to the existing detector. The distance between the input surface 6a of the scintillator 6 and the front end surface 7a of the magnification lens 7 is also maintained constant, and the accuracy of the focal distance (the working distance of the magnification lens 7) is also ensured.

[0103] In the camera unit 30R, the main body 70a of the positioning member 70 forms a slit for guiding radiation to the scintillator 6. The aforementioned slit member 16 (first slit plate 17 and second slit plate 18) is not required. That is, the slit is formed by positioning the input surface 6a of the scintillator 6 and the front end surface 7a of the equal-magnification lens 7. A second through-hole 75, serving as the optical path for the scintillating light, is also formed. Furthermore, the holding member 60 of the line scan sensor 3 is positioned by embedding it into the positioning member 70. Thus, it is possible to easily achieve [the desired effect]. Figure 12 The camera unit shown has the same configuration as the 30P camera shown.

[0104] In addition, although Figure 13 In the camera unit 30R shown, a substrate and the like are arranged in a space extending from the position of the line scan sensor 3 along the x-direction (conveyance direction D). However, in such a camera unit 30R, the size of the frame body 13 in the Z-direction can also be reduced. In addition, the layout of various components within the frame 15 can be changed depending on the application destination or installation location of the camera unit, or the desired surrounding layout.

[0105] In addition, it is also possible to Figures 1-12 The various embodiments shown above (camera units 30, 30A-30H, 30J-30N, 30P) utilize the structure of at least one of the positioning member 70, the support member 80, and the holding member 60, i.e., the same structure as the camera unit 30R. When using the positioning member 70, the main body 70a of the positioning member 70 can be formed into a slit for guiding radiation to the scintillator 6. In this case, the slit member 16 can be omitted.

[0106] Continuing with the description of various variations. For example, the range of the slit member 16 may be smaller than that described in the above embodiment, or it may be a portion of the path from the entrance window 14f to the input surface 6a of the scintillator 6.

[0107] The material used for the slit component 16 is not limited to copper plate; for example, it can be aluminum, stainless steel, iron, lead, etc. In the slit component 16, a process can be performed to cover the surface of the aluminum, iron, stainless steel, or lead material with copper foil or a copper plate, or to cover the surface of the material with copper. Furthermore, the slit component 16 can be formed from multiple materials. The same applies to the line source side slit component 26. Alternatively, the line source side slit component 26 can be omitted. Copper has the characteristic of being difficult to generate scattered radiation; using copper is advantageous from the viewpoint of reducing scattered radiation and the associated sensor noise.

[0108] The shielding member 9 can also be omitted. In this case, an equal magnification lens is directly attached with respect to the line scan sensor 3. In addition, in the above embodiment, although the scintillated light emitted from the input face 6a of the scintillator 6 is imaged, in addition to this, the scintillated light emitted from the opposite face of the input face 6a of the scintillator 6 can also be imaged. In this case, the scintillator 6 can be composed of a plurality of scintillators, or a member that shields the scintillated light can be added between the plurality of scintillators.

[0109] Industrial Applicability

[0110] According to the several modes of the present application, it is possible to improve the resolution, and it is also possible to improve the sensitivity.

[0111] Explanation of Symbols

[0112] 1...radiation image acquisition system, 3...line scan sensor, 3a...imaging face, 6...scintillator, 6a...input face, 7...equal magnification lens, 9...shielding member, 13...frame main body, 14...lead cover, 14f...incident window, 14g...other incident window, 15...frame, 16...slit member, 16A...other slit member, 17...first slit plate, 18...second slit plate, 20...conveyance device, 21a...conveyance face, 30...imaging unit, 26...line source side slit member, 70...positioning member (slit member), B...normal (of the input face of the scintillator), C...gap, D...conveyance direction, E...optical axis (of the line scan sensor), S...slit, SA...other slit.

Claims

1. An imaging unit, wherein is an imaging unit for acquiring a radiation image of an object conveyed in a conveyance direction, comprises: a frame having an incident window through which a radiation that has passed through the object passes; a scintillator provided inside the frame, having an input surface that inputs the radiation that has passed through the incident window; a line-scan sensor provided inside the frame, having an imaging surface that images scintillated light output from the input surface; a slit member disposed between the incident window and the scintillator, forming a slit that guides the radiation that has passed through the incident window toward the input surface; and an equal magnification lens disposed between the scintillator and the line-scan sensor, imaging the scintillated light output from the input surface on the imaging surface of the line-scan sensor, the slit member is configured such that a width of the slit in the conveyance direction becomes narrower as approaching the input surface of the scintillator.

2. The imaging unit according to claim 1, wherein the slit member is disposed in a manner that the slit is located in a normal line direction of the input surface of the scintillator, the equal magnification lens and the line-scan sensor image and image the scintillated light output in a direction inclined with respect to the normal line direction of the input surface.

3. The imaging unit according to claim 1, wherein the slit member is disposed in a manner that the slit extends obliquely with respect to the conveyance direction.

4. The imaging unit according to claim 2, wherein the slit member is disposed in a manner that the slit extends obliquely with respect to the conveyance direction.

5. The imaging unit according to claim 1, wherein the slit member is disposed in a manner that the slit is located in a direction inclined with respect to a normal line direction of the input surface of the scintillator, the equal magnification lens and the line-scan sensor image and image the scintillated light output in a direction inclined with respect to the normal line direction of the input surface.

6. The imaging unit according to any one of claims 1 to 5, wherein further comprising: a cover member that holds the slit member, and is attached to the frame in a detachable manner.

7. An imaging unit, wherein is an imaging unit for acquiring a radiation image of an object conveyed in a conveyance direction, comprises: a frame having an incident window through which a radiation that has passed through the object passes, and another incident window through which a radiation that has passed through the object passes; a scintillator provided inside the frame, having an input surface that inputs the radiation that has passed through the incident window; a line-scan sensor provided inside the frame, having an imaging surface that images scintillated light output from the input surface; a slit member disposed between the incident window and the scintillator, forming a slit that guides the radiation that has passed through the incident window toward the input surface; another slit member disposed between the other incident window and the scintillator, forming another slit that guides the radiation that has passed through the other incident window toward the input surface; and an equal-magnification lens disposed between the scintillator and the line-scan sensor to image the scintillating light output from the input face on the imaging face of the line-scan sensor, the slit member and the other slit member are disposed so that the slit and the other slit respectively guide the radiation from different two directions with respect to the input face of the scintillator.

8. An imaging unit, wherein is an imaging unit for acquiring a radiation image of an object conveyed along a conveyance direction, includes: a frame having an incident window through which a radiation transmitted through the object passes; a scintillator provided in the frame, having an input face that inputs the radiation that has passed through the incident window; a line-scan sensor provided in the frame, having an imaging face that images scintillating light output from the input face; a slit member disposed between the incident window and the scintillator, forming a slit that guides the radiation that has passed through the incident window toward the input face; and an equal-magnification lens disposed between the scintillator and the line-scan sensor to image the scintillating light output from the input face on the imaging face of the line-scan sensor, the slit member, the equal-magnification lens, and the line-scan sensor are rotatable about an axis extending along the input face within the frame.

9. A radiation image acquisition system, wherein is a radiation image acquisition system that acquires a radiation image of an object, includes: a radiation source that outputs the radiation toward the object; a conveyance device that conveys the object along the conveyance direction and passes the radiation; and the imaging unit according to any one of claims 1 to 8 is disposed so that the radiation source and the incident window are disposed on the same plane.

10. The radiation image acquisition system according to claim 9, wherein the conveyance device and the slit member of the imaging unit are disposed so that the slit extends obliquely with respect to the conveyance direction.

11. A radiation image acquisition method, wherein is a radiation image acquisition method that acquires a radiation image of an object, includes: a radiation output step of outputting a radiation toward the object conveyed along a conveyance direction; a radiation introduction step of causing the radiation that has transmitted through the object to be incident on a frame through an incident window, and guiding the radiation toward an input face of a scintillator by a slit formed in the frame so as to narrow in width in the conveyance direction as approaching the input face of the scintillator; a scintillating light output step of inputting the radiation that has passed through the slit to the input face of the scintillator, converting the input radiation into scintillating light, and outputting the scintillating light from the input face; a scintillating light imaging step of imaging the scintillating light output from the input face on an imaging face of a line-scan sensor by an equal-magnification lens; and a scintillating light imaging step of imaging the scintillating light on the imaging face of the line-scan sensor.

Images