Radiation detector

Abstract

The radiation detector includes: a positioning component having a through-hole for radiation to pass through; a scintillator having an input surface for receiving radiation passing through the through-hole and converting the radiation into scintillation light; a sensor having a light-receiving surface for receiving the scintillation light converted by the scintillator and detecting the scintillation light; and a lens having a lens that images the input surface of the scintillator and the light-receiving surface of the sensor, respectively. The positioning component has a first positioning part for positioning the scintillator by contacting its input surface, and a second positioning part for positioning the lens by contacting one end face of the lens.

Description

Technical Field

[0001] This invention relates to a radiation detector. Background Technology

[0002] A radiation detector is known, comprising a phosphor that converts radiation into light and a sensor unit that senses the light from the phosphor (see, for example, Patent Document 1). Such a radiation detector is used in inspection devices or imaging devices equipped with a radiation source to detect radiation irradiated from the radiation source onto an object and passing through that object. In the radiation detector described in Patent Document 1, the sensor unit is supported by a first support member, and the phosphor is supported by a second support member. The second support member is fitted into the first support member. The sensor unit is surrounded by the first support member and a protective member mounted on the first support member. An opening is provided in the protective member, through which light from the phosphor enters the sensor unit.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-191059 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the existing radiation detectors described above, the surface of the phosphor is tilted relative to both the +Z direction (facing the radiation source) and the +X direction (facing the sensor section). The relative position between the sensor section supported by the first support member and the phosphor supported by the second support member is maintained by fixing the relative configuration between the first and second support members. However, various variations can exist in the thickness of the phosphor (scintillator). In existing radiation detectors, the position of the phosphor surface is determined by the position and height of the second support member, but when the phosphor thickness varies, the surface position also changes according to the thickness variation.

[0008] As the position of the phosphor's surface (i.e., the input surface for the input radiation) changes, the distance between the sensor unit and the phosphor's surface also changes. If the distance between the sensor unit and the phosphor's surface changes, for example, if a lens is placed between the phosphor and the sensor unit, undesirable conditions may occur, such as difficulty in achieving the desired image through the lens.

[0009] The present invention describes a radiation detector that can easily ensure the positional accuracy of the input surface of a scintillator, thereby maintaining a constant distance between the sensor section and the input surface of the scintillator.

[0010] Technical means to solve the problem

[0011] The constituent elements of one aspect of the present invention are described below.

[0012] [1] A radiation detector, wherein,

[0013] have:

[0014] Positioning component having a through hole for the passage of radiation;

[0015] A scintillator having an input surface that receives the radiation passing through the through-hole and converts the radiation into scintillating light;

[0016] The sensor unit has a light-receiving surface that receives the flashing light converted by the scintillator and detects the flashing light;

[0017] The lens section has lenses that respectively image the input surface of the scintillator and the light-receiving surface of the sensor section.

[0018] The positioning component has a first positioning part that positions the scintillator by contacting the input surface of the scintillator, and a second positioning part that positions the lens part by contacting one end face of the lens part.

[0019] According to this radiation detector, a single component, namely the positioning component, positions the scintillator via a first positioning part and the lens part via a second positioning part. Because the input surface of the scintillator is in contact with the first positioning part, the positional accuracy of the input surface can be easily ensured, for example, even if the thickness of the scintillator changes. Therefore, the distance between the sensor part and the input surface of the scintillator can be maintained constant. This structure eliminates the need to consider the positional accuracy of different components, offering advantages over existing detectors. The distance between the input surface of the scintillator and one end face of the lens part is also maintained constant, ensuring the accuracy of the focal distance.

[0020] In several ways, the constituent elements of the present invention may also be described as follows.

[0021] [2] According to the radiation detector of [1], the first positioning part is in surface contact with the input surface of the scintillator.

[0022] This structure allows for easy stabilization of the scintillator's orientation, further improving the positional accuracy of the scintillator's input surface.

[0023] [3] According to the radiation detector described in [1] or [2], wherein,

[0024] The second positioning part is in surface contact with one end face of the lens part.

[0025] This structure allows for reliable and easy fixation of the lens portion, further improving its positional accuracy.

[0026] [4] The radiation detector according to any one of [1] to [3], wherein,

[0027] It also includes a holding member for holding the lens portion and the sensor portion.

[0028] The retaining member has a surface opposite to the side of the second positioning portion on which the positioning member is formed, and one end face of the lens portion is exposed on the surface.

[0029] According to this structure, the relative positions of the sensor section, lens section, and scintillator are determined only by assembling the positioning component with the holding component.

[0030] [5] According to the radiation detector described in [4], wherein,

[0031] The positioning component and the retaining component are fixed with a gap between the side and the surface.

[0032] According to this structure, heat generated by the sensor unit is not easily transferred to the positioning component. By protecting the positioning component from heat, it is easy to maintain a constant distance between the first and second positioning parts. Even if there are deviations in the characteristics of the lens, the effects of these deviations can be compensated for.

[0033] [6] The radiation detector according to any one of [1] to [5], wherein,

[0034] The positioning component has a recess that receives the end edge of the scintillator.

[0035] Based on this structure, the position of the scintillator can be easily fixed.

[0036] [7] The radiation detector according to any one of [1] to [6], wherein,

[0037] It also includes: a support component that engages with the positioning component to support the flashing device.

[0038] The support member has a support surface opposite to the mounting surface of the first positioning portion on which the positioning member is formed, and the flasher is held between the mounting surface and the support surface.

[0039] According to this structure, the scintillator can be reliably supported and fixed simply by fitting the support component into the positioning component.

[0040] [8] According to the radiation detector described in [7], wherein,

[0041] The support component is fixed to the positioning component in a manner that allows adjustment of the spacing between the mounting surface and the support surface.

[0042] This structure allows for the adaptation of scintillators of any thickness.

[0043] The effects of the invention

[0044] According to several methods of the present invention, the positional accuracy of the input surface of the scintillator can be easily ensured, thereby maintaining a constant distance between the sensor section and the input surface of the scintillator. Attached Figure Description

[0045] Figure 1 This is a perspective view illustrating a radiographic image acquisition system according to an embodiment of the present invention.

[0046] Figure 2 It means Figure 1 The radiographic image shown is a diagram of the system's general structure.

[0047] Figure 3 It means Figure 1 A cross-sectional view of the internal structure of the radiation detector in the image.

[0048] Figure 4 It is Figure 3 A magnified cross-sectional view of a portion of the image.

[0049] Figure 5 It is along Figure 4 The cross-sectional view of the V-V line is a view showing one end face of the lens portion exposed on the surface of the holding component.

[0050] Figure 6 This is a diagram showing a schematic structure of a lens section in an example.

[0051] Figure 7 It means Figure 3 A three-dimensional view of the radiation detector.

[0052] Figure 8 This diagram shows the state of the support component after it has been removed from the positioning component.

[0053] Figure 9 This diagram shows the state of the scintillator after it has been removed from the positioning component. Detailed Implementation

[0054] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same symbols are used to denote the same elements, and repeated descriptions are omitted. Additionally, the drawings are made for illustrative purposes and are depicted in a way that particularly emphasizes the parts to be explained. Therefore, the dimensional ratios of the parts in the drawings may not necessarily match the actual dimensions.

[0055] like Figure 1 and Figure 2 As shown, one embodiment of the radiographic image acquisition system 1 is an apparatus for acquiring radiographic images of an object A. The radiographic image acquisition system 1 is a non-destructive inspection system capable of inspecting the object A without disassembling or damaging it. The object A may contain, for example, a substance composed of light elements. The radiographic image acquisition system 1 is applied in fields such as food inspection, battery inspection, or inspection of electronic components. In the field of food inspection, for example, it is used to check for the presence or absence of foreign objects in sealed containers. The radiographic image acquisition system 1 exhibits particularly excellent discrimination performance against substances composed of light elements. Examples of such substances include food scraps, hair, plastic, insects, and bones in meat. The radiographic image acquisition system 1 is applied, for example, to embedded X-ray inspection.

[0056] The radiographic image acquisition system 1 includes a radiation source 2 that outputs white X-rays or other radiation toward an object A, a transport device 20 that transports the object A along a predetermined transport direction D, a scintillator 6 that generates scintillation light based on the input of radiation from the object A transported by the transport device 20, a line scan sensor (sensor unit) 3 that detects the scintillation light output from the radiation input surface 6a of the scintillator 6, and a computer 10 that controls several functions of the radiographic image acquisition system 1 and generates radiographic images. Thus, the radiographic image acquisition system 1 is an X-ray imaging system using a scintillator surface observation method. The radiographic image acquisition system 1 exhibits excellent sensitivity to low-energy X-rays.

[0057] Radiation source 2 outputs a cone-beam X-ray from the X-ray exit section. Radiation source 2 has a focal point 2a for the cone-beam X-ray. Radiation source 2 can be, for example, a microfocus X-ray source or a millimeter focus X-ray source. The X-rays emitted from radiation source 2 form a radiation beam. In the radiation image acquisition system 1, a source-side slit member 26 and a positioning member 70 (see reference 1) are used. Figure 2 The X-rays within the narrowed, confined portion of the X-rays in the output region of the radiation beam are input to the input surface 6a of the scintillator 6. The irradiation region 12 extends in a triangular (or fan-shaped) shape toward the scintillator 6 within the housing 15 of the radiation detector 30.

[0058] The conveying device 20, for example, includes two belt conveyors 21, 21 that move on a circular track. An object A is placed or held on the conveying surface 21a of the belt conveyor 21. The belt conveyor 21 serves as a conveying platform or conveying section. The conveying device 20 includes a drive source (not shown) that drives each belt conveyor 21. The conveying device 20 is configured to convey the object A at a constant speed along the conveying direction D. In this embodiment, the conveying direction D is horizontal. Between the two belt conveyors 21, 21, a gap C is provided at a position corresponding to the aforementioned irradiation area 12, allowing X-rays to pass through. The gap C has a small, constant length (width) along the conveying direction D and extends straight along a horizontal detection width direction orthogonal to the conveying direction D. The timing and speed of conveying the object A in the conveying device 20 are preset and controlled by the control unit 10a of the computer 10. Furthermore, the belt conveyor 21 does not need to have a gap C that allows X-rays to pass through, and the belt component of the belt conveyor 21 can also be made of a material that is radiolucent. Figure 1 and Figure 2 The conveying direction D shown is parallel to the x-direction parallel to the paper plane shown in the figure. The aforementioned detection width direction is parallel to... Figure 2 The paper shown is perpendicular to the y-direction. The up and down directions are parallel to the vertical direction. Figure 2 The z-direction, which is parallel to the plane of the paper shown, is parallel.

[0059] Furthermore, the radiographic imaging system 1 can be compatible with all types of transport devices 20. For example, the transport direction D can be horizontal, but it can also be inclined relative to the horizontal. The transport direction D also does not have to be straight; for example, it can be curved. In this case, the transport direction D can also be a tangent in the portion of the transport path of the object A that overlaps with the irradiation area 12. The transport device 20 may also not have a physical transport surface 21a. For example, the transport device 20 can also transport the object A while using air to levitate it. Alternatively, the transport device 20 can also transport the object A by releasing it into the air. In this case, the transport path of the object A can be parabolic, for example.

[0060] The conveying device 20 is not limited to having a belt conveyor 21. The conveying device 20 may also have, for example, a roller conveyor comprising multiple rollers. Because 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. Considering the configuration of the radiation source 2 and the configuration of the irradiation area 12 (oblique irradiation) described below, the roller conveyor can be effectively utilized. The roller conveyor is a suitable conveying unit for a radiographic imaging 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.

[0061] like Figures 1-3 As shown, the radiation image acquisition system 1 includes a radiation detector 30 arranged along the conveyor 20. The radiation detector 30 is a camera unit for capturing radiation images of an object A. The radiation detector 30 is mounted on and fixed to the conveyor 20, for example. The radiation detector 30 may also be mounted outside the conveyor 20. The radiation detector 30 may also be placed on a stand or the like. The radiation detector 30 is installed in a manner that does not interfere with the surrounding area of ​​the belt conveyor 21. The same applies when the conveyor 20 is a roller conveyor. The radiation detector 30 is arranged with some clearance from the conveyor section in a manner that does not interfere with the movement of the conveyor section, such as the belt conveyor or roller conveyor.

[0062] The radiation detector 30 has a rectangular parallelepiped housing 15. The housing 15 may have, for example, an aluminum rectangular parallelepiped body 13 and a lead shield 14 covering the outer surface (outer peripheral surface) of the housing body 13. The housing body 13 houses the various structures of the radiation detector 30. The lead shield 14 shields radiation so that radiation outside the housing body 13 does not affect the internal space of the radiation detector 30. The lead shield 14 can be disposed on the outside of the housing 15 or on the inside of the housing 15. Alternatively, another shield may be mounted on the outside of the lead shield 14. From the viewpoint of the strength or handling of lead, it is preferable to mount another material on the outside of the lead shield. The material for the shield can be a substance other than lead, such as tungsten, iron, stainless steel, copper, etc. Alternatively, a rubbery material or sheet material containing heavy metals such as tungsten in rubber (resin) can be used.

[0063] The housing body 13 is made of a material capable of shielding X-rays, for example. The housing body 13 can also be made of iron or stainless steel. The housing body 13 may also contain a protective material, such as lead, tungsten, or copper. Alternatively, a rubber-like raw material or sheet-like raw material containing heavy metals such as tungsten in rubber (resin) can also be used.

[0064] The upper wall portion 13a of the housing body 13 is arranged opposite to the conveying device 20. A top plate portion 14a of the lead cover 14 is installed on the upper wall portion 13a at intervals from it. The top plate portion 14a is arranged parallel to the upper wall portion 13a. An aluminum cover portion 13e is provided between the upper wall portion 13a and the top plate portion 14a. Alternatively, the cover portion 13e may be made of a metal such as stainless steel or iron.

[0065] The lead shield 14 covers, for example, the entire surface except for the bottom wall of the housing body 13. (Illustrations of the lead shield 14 other than the top plate portion 14a are omitted.) An entrance window 14f is formed in the top plate portion 14a of the lead shield 14 to allow X-rays that have passed through the object A to pass through. The entrance window 14f has a small, constant length (width) in the x-direction and extends straight along the y-direction. The length of the entrance window 14f in the x-direction can also be determined by the width of the slit formed by the first through hole 74 described below or the width of the desired irradiation area 12 (thickness in the transport direction D).

[0066] In the cover wall portion 13e and the upper wall portion 13a, through holes 13g and 13f are formed at positions corresponding to the entrance window 14f. These holes have a constant length (width) in the x-direction and extend straight in the y-direction. (Refer to...) Figure 3 The entrance window 14f of the top plate portion 14a, the through hole 13g of the cover portion 13e, and the through hole 13f of the upper wall portion 13a have a constant length in the x direction and are arranged in the thickness direction, forming the path of the radiation, i.e., the first part of the slit.

[0067] The radiation detector 30 is configured to capture scintillation light output from the input surface 6a of the scintillator 6 in a direction inclined relative to the input surface 6a. The scintillator 6, the line scan sensor 3, and the equal-magnification lens (lens section) 7 are disposed within the housing 15. The equal-magnification lens 7 is positioned between the scintillator 6 and the line scan sensor 3. The radiation detector 30 has a structure for holding the scintillator 6, the line scan sensor 3, and the equal-magnification lens 7 in a predetermined positional relationship. In the radiation detector 30, a substrate, etc., are disposed within a space extending along the x-direction (transport direction D) from the position of the line scan sensor 3. The layout of various components within the housing 15 can be changed according to the application target of the radiation detector, the installation location, or the required surrounding layout.

[0068] like Figure 3 and Figure 4 As shown, the radiation detector 30 includes a holding member 60 for holding the equal-magnification lens 7 and the line scan sensor 3, a positioning member 70 for positioning the scintillator 6, and a support member 80 that engages with the positioning member 70 to support the scintillator 6. The holding member 60, the positioning member 70, and the support member 80 are mounted on the housing body 13 of the housing 15 and fixed in a predetermined position. The structure of the scintillator 6, the line scan sensor 3, and the equal-magnification lens 7, as well as the structure for holding these components, will be described below. Furthermore, in Figure 1 The positioning component 70 and the support component 80 are omitted from the illustration.

[0069] The scintillator 6 is held, for example, in a scintillator holder (not shown), and is configured, for example, horizontally. The scintillator 6 is a plate-shaped wavelength conversion component. The scintillator 6 has, for example, a substantially constant thickness. The scintillator 6 is a rectangular shape that is longer in the detection width direction (y-direction) (see reference). Figure 1 and Figure 9 The scintillator 6 is composed of, for example, Gd₂O₂S:Tb, Gd₂O₂S:Pr, CsI:Tl, CdWO₄, CaWO₄, Gd₂SiO₅:Ce, Lu 0.4 Gd 1.6 SiO5, Bi4Ge3O 12 The scintillator 6 is composed of materials such as Lu2SiO5:Ce, Y2SiO5, YAlO3:Ce, Y2O2S:Tb, YTaO4:Tm, YAG:Ce, YAG:Pr, YGAG:Ce, YGAG:Pr, and GAGG:Ce. The thickness of the scintillator 6 is set to an appropriate value based on the energy band of the detected radiation in the range of a few μm to a few mm. The scintillator 6 converts the X-rays that have passed through the object A into visible light (scintillating light). Lower-energy X-rays are converted by the input surface 6a of the scintillator 6 and output from the input surface 6a.

[0070] The line scan sensor 3, in conjunction with the movement of the object A, captures images and outputs one-dimensional image data, i.e., radiation image data. The imaging unit 31 of the line scan sensor 3 has an imaging surface 3a for capturing the scintillation light output from the input surface 6a of the scintillator 6. This imaging surface 3a is a light-receiving surface that receives the scintillation light. The line scan sensor 3 can be, 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 can be, for example, a CCD image sensor or a CMOS image sensor. The line scan sensor 3 has a structure in which multiple light-receiving elements are arranged in a column in the pixel direction and arranged in one or more levels in the column direction. Figure 2In the diagram, the vertical direction is parallel to the Z-direction. The line scan sensor 3 has a scanning direction corresponding to the transport direction D of the object A and a line direction orthogonal to the scanning direction. This line direction is the pixel direction mentioned above, and... Figure 2 The y-direction is parallel to it. Furthermore, the scanning direction corresponds to the aforementioned longitudinal direction. Figure 2 In the meantime, the longitudinal direction is parallel to the z-direction. Furthermore, in the case of a region image sensor capable of TDI driving, the longitudinal direction becomes the same as the integration direction.

[0071] The line scan sensor 3, controlled by the control unit 10a, captures images of the object A in conjunction with its movement. Specifically, the line scan sensor 3 captures images on the imaging surface 3a synchronously with the movement of the object A by the transport device 20, and outputs radiographic image data. This allows for the acquisition of radiographic images with a good signal-to-noise ratio (S / N). Furthermore, to synchronize the movement of the object A by the stage with the image capture by the line scan sensor, an encoder can be installed on the stage, and the line scan sensor 3 can be controlled using signals from the encoder.

[0072] In this embodiment, the scintillator 6 is configured, for example, with its input surface 6a tilted relative to the transport direction D and parallel to the aforementioned line direction.

[0073] like Figure 3 As shown, the retaining member 60 is housed inside the housing body 13. The retaining member 60 includes a positioning portion 61 that functions as a guide. Furthermore, the retaining member 60 holds a constant magnification lens 7 at its positioning portion 61 facing the scintillator 6. Additionally, the retaining member 60 holds a line scan sensor 3 at its base end 65 on the side opposite to the positioning portion 61. The retaining member 60 holds the constant magnification lens 7, for example, with one end face 7a orthogonal to the x-direction. The retaining member 60 holds the line scan sensor 3, for example, with the imaging surface 3a of the imaging unit 31 orthogonal to the x-direction. Figure 4 As shown, the imaging portion 31 of the line scan sensor 3 is held in place by the main body portion 32 mounted on the base portion 33. A portion of the base portion 33 and the main body portion 32 are embedded into the base end portion 65 of the retaining member 60.

[0074] like Figure 3 and Figure 4As shown, the positioning member 70 is installed in the housing body 13 directly below the entrance window 14f. The positioning member 70 is made of a metal such as copper. The positioning member 70 has a first through hole 74 for the passage of radiation and a second through hole 75 for the passage of scintillating light converted by and output from the scintillator 6. The first through hole 74 is formed, for example, along the yz plane, and the second through hole 75 is formed, for example, along the xy plane. 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 are connected by a space extending in the y direction. The positioning member 70 has a mounting surface 77 that extends obliquely relative to the first through hole 74, i.e., the path of the radiation. The mounting surface 77 is obliquely 45° relative to the xy plane, for example. The scintillator 6 is pressed against the mounting surface 77 by a support member 80. On the mounting surface 77, there is a spatial opening where the first through hole 74 and the second through hole 75 intersect. The input surface 6a of the scintillator 6 faces the opening 70d. By appropriately setting the tilt angle of the mounting surface 77, the angle of the input surface 6a relative to the radiation input to the input surface 6a and the angle of the input surface 6a relative to the camera surface 3a are determined. The tilt angle of the mounting surface 77 described above (45°) is only an example; the mounting surface 77 may also be tilted at other angles relative to the xy plane.

[0075] The first through-hole 74 forms the path for the radiation, i.e., the second part of the slit, and works in conjunction with the first part to guide the X-rays that have passed through the entrance window 14f toward the input surface 6a of the scintillator 6. The positioning member 70 prevents the scattering of X-rays within the interior space of the housing 15. The input surface 6a of the scintillator 6 receives X-rays (radiation) within the irradiation area 12 that have passed through the first through-hole 74 of the positioning member 70.

[0076] In the radiographic image acquisition system 1, for example, a shielding component 9 is installed between the line scanning sensor 3 and the equal-magnification lens 7. The line scanning sensor 3, the shielding component 9, and the equal-magnification lens 7 are integrated into one unit.

[0077] 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 can be, 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. The shielding component 9 can be, for example, a plate-like component disposed on the line scan sensor 3, but it can also be a block-like component disposed throughout the space between the imaging surface 3a of the line scan sensor 3 and the other end face 7c of the equal-magnification lens 7. That is, a gap can be formed between the shielding component 9 and the equal-magnification lens 7, but a gap may also not exist.

[0078] A constant-magnification lens 7 is positioned between the scintillator 6 and the line-scan sensor 3, imaging the scintillator light output from the input surface 6a onto the imaging surface 3a of the line-scan sensor 3. The constant-magnification lens 7 is a 1x lens and can be implemented using, for example, a refractive index distribution lens (GRIN lens), a rod lens, or a rod lens array. The focal point of the constant-magnification lens 7 is aligned with the input surface 6a of the scintillator 6. Because of its depth of field, the constant-magnification lens 7 exhibits minimal blurring even when photographing the phosphor at an angle, making it advantageous for tilted imaging as described in this embodiment. Furthermore, the constant-magnification lens 7 increases the flexibility in the arrangement and combination of the radiation source 2, the object A, and the line-scan sensor 3.

[0079] Figure 6 This is a diagram showing a schematic structure of an example of a 7-fold equal-magnification lens. (See diagram for example.) Figure 6 As shown, the equal-magnification lens 7 is rectangular. For example, the equal-magnification lens 7 has a structure in which a plurality of cylindrical lens bodies (lenses) 8 arranged in a row are held by a lens holding portion 7b. The equal-magnification lens 7 has a total length W, a thickness T, and a lens length L2. Each lens body 8 has an aperture angle θ and a field of view radius R. The equal-magnification lens 7 images the scintillator 6 input surface 6a and the line scan sensor 3a respectively through the lens bodies 8 arranged in an array. One end face 7a and the other end face 7c of the equal-magnification lens 7 are parallel to each other in the direction of the lens length L2, and are respectively formed as flat surfaces. The two end faces of the lens body 8 are exposed at one end face 7a and the other end face 7c, and are the same surface as the two end faces of the lens holding portion 7b. In the equal-magnification lens 7, adjacent lens bodies 8 are arranged in a way that overlaps with each other. Because the lens bodies 8 are arranged in an array, the brightness will not be different at the center and ends of the array, and no lens deformation occurs at the ends. Figure 6 The working distance L1 on one end face 7a and the working distance L1 on the opposite side shown are respectively equivalent to Figure 4 The distance between the input surface 6a and one end surface 7a, and the distance between the other end surface 7c and the imaging surface 3a are shown. That is, the conjugate length LC of the equal-magnification lens 7 is equivalent to the distance between the input surface 6a and the imaging surface 3a.

[0080] Back Figure 4 In the radiation detector 30, the path of the radiation formed by the first through-hole 74 is configured to be inclined relative to the normal direction 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 disposed in a direction inclined relative to the normal direction of the input surface 6a. The equal-magnification lens 7 images the scintillation light output in a direction inclined relative to the normal direction of the input surface 6a onto the imaging surface 3a. The line scan sensor 3 captures the scintillation light output in a direction inclined relative to the normal direction of the input surface 6a.

[0081] Back Figure 4The positioning member 70 has a locking plate portion 79 that contacts the side of the housing body 13 and a main body portion 70a disposed within the housing body 13. A first through hole 74 and a second through hole 75 are formed in the main body portion 70a. For example, a rectangular recess 70c is formed in the main body portion 70a, and the positioning portion 61 of the retaining member 60 is embedded in the recess 70c. In this way, the retaining member 60 is embedded and fixed within the housing body 13 relative to the positioning member 70 fixed to the housing body 13.

[0082] The positioning member 70 has a first positioning portion 71 that positions the scintillator 6 by contacting the input surface 6a of the scintillator 6. The first positioning portion 71 is formed as part of the aforementioned mounting surface 77 and has a flat surface. The first positioning portion 71, for example, contacts the input surface 6a of the scintillator 6.

[0083] A support member 80, which engages with the positioning member 70, supports the scintillator 6. The support member 80 has a support surface 82 opposite to the mounting surface 77 on 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, thus the support surface 82 is parallel to the mounting surface 77. Both the mounting surface 77 and the support surface 82 have, for example, flat surfaces. The support member 80 holds 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 unit such as a screw or small screw, in a manner that allows adjustment of the gap 89 (the distance in the normal direction of the support surface 82) between the mounting surface 77 and the support surface 82. The size of the gap 89 is, for example, constant in its extending direction (along the direction of the inclined surface (parallel to the mounting surface 77) containing the y-axis).

[0084] More specifically, such as Figure 8 As shown, the positioning member 70 has a pair of side plate portions 73, 73 disposed at both ends in the y direction, and a support member 80 is embedded between the side plate portions 73, 73.

[0085] The positioning member 70 has a second positioning portion 72 that positions the imaging surface 3a by contacting one end face 7a of the equal magnification lens 7. The second positioning portion 72 is formed as part of the side surface 76 opposite to the holding member 60 and has a flat surface. The second positioning portion 72 contacts, for example, one end face 7a of the equal magnification lens 7.

[0086] More specifically, the retaining member 60 has a surface 62 opposite to the side surface 76 where the second positioning portion 72 is formed, but a gap 69 is formed between the two parallel surfaces, namely the side surface 76 and the surface 62. The gap 69 is formed along the yz plane and, for example, is constant throughout the entire surface. The positioning member 70 and the retaining member 60 are fixed together with the gap 69. Figure 5 As shown, one end face 7a of the equal magnification lens 7 is exposed on surface 62. (As...) Figure 4 As shown, one end face 7a of the equal magnification lens 7 protrudes from the surface 62 and abuts against the side 76 of the positioning member 70. The length of the protruding end face 7a is equal to the width of the gap 69.

[0087] With the structure described above, the positioning component 70 positions the scintillator 6 and the equal-magnification lens 7.

[0088] Reference Figure 4 , Figure 8 and Figure 9 The mounting structure (mounting method) of the scintillator 6 relative to the positioning member 70 will be described. The positioning member 70 has an L-shaped recess 78 at the lower end of the mounting surface 77 (the end opposite to the first through hole 74) that receives the end edge 6c of the scintillator 6. The recess 78 extends along the y-direction and is formed over the entire area in the y-direction (see reference). Figure 9 When the scintillator 6 is pressed against the mounting surface 77, the end edge 6c of the scintillator 6 is embedded into the recess 78, thereby stabilizing the posture of the scintillator 6 (see reference). Figure 8 In this state, the input surface 6a of the flasher 6 faces the opening 70d formed by the intersection of the first through hole 74 and the second through hole 75. Figure 8 As shown, the back 6b of the flasher 6 is exposed. Then, by mounting the support member 80 (see reference 70) on the positioning member 70... Figure 7 And use appropriate fixing units to fix the support component 80 and fix the flasher 6. For example... Figure 4 As shown, the support member 80 supports the scintillator 6 with the support surface 82 in contact with the back surface 6b of the scintillator 6. A gap 89 equal to the thickness of the scintillator 6 is formed between the positioning member 70 and the support member 80.

[0089] The recess 78 may have a flat surface, for example. The surface of the recess 78 may also be orthogonal to the aforementioned inclined surface (the surface parallel to the mounting surface 77). The height of the surface of the recess 78 (the depth of the recess 78, the length in the direction orthogonal to the y-direction) may be approximately equal to or less than the thickness of the scintillator 6. When its height (depth) is less than the thickness of the scintillator 6, the end face of the scintillator 6 that abuts against the recess 78 protrudes from the recess 78. The greater the thickness of the scintillator 6, the larger the gap 89. Depending on the thickness of the scintillator 6, the position of the support member 80 differs in the x-direction (moving parallel), and the support member 80 can be fixed in the appropriate position. The depth of the recess 78 defines the minimum dimension of the gap 89. In order to reliably hold the scintillator 6 without imparting clearance, the depth of the recess 78 is the same as or less than the thickness of the thinnest scintillator 6 that can be provided in the radiation detector 30. The recess 78 is a cutout or receiving surface that receives part or all (at least part in the thickness direction) of the end face of the scintillator 6 formed on the positioning member 70.

[0090] Back Figure 2 The computer 10 includes, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and input / output interfaces. The computer 10 has a control unit 10a (control processor) that controls the radiation source 2 and the line scan sensor 3, and an image processing unit 10b (image processing processor) that creates a radiation image of the object A based on radiation image data output from the line scan sensor 3. The image processing unit 10b inputs radiation image data and performs prescribed processing such as image processing on the input radiation image data. A display device 11 is connected to the computer 10. The image processing unit 10b outputs the created radiation image to the display device 11. The control unit 10a controls the radiation source 2 based on the values ​​of the tube voltage or tube current of the radiation source 2 stored through user input, etc. The control unit 10a controls the line scan sensor 3 based on the exposure time, etc., stored through user input, etc. The control unit 10a and the image processing unit 10b can be different processors or the same processor. Furthermore, the computer 10 can be programmed to perform the functions of the control unit 10a and the image processing unit 10b. Additionally, the computer 10 can also be constructed from a microcomputer or an FPGA (Field-Programmable Gate Array).

[0091] Next, the operation of the radiation image acquisition system 1, i.e., the method of acquiring radiation images, will be explained. First, the object A is transported along the transport direction D using the transport device 20 (transport process). Simultaneously, 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 directed into the housing 15 through the entrance window 14f, and guided toward the input surface 6a of the scintillator 6 through a slit formed within the housing 15 (radiation introduction process). The radiation that has passed through the object A is input to the input surface 6a, where it is converted from radiation to scintillation light by the scintillator 6, and scintillation light is output from the input surface 6a (scintillation light output process). Then, the scintillation light output from the input surface 6a is imaged onto the imaging surface 3a of the online scanning sensor 3 using the equal magnification lens 7 (scintillation light imaging process). Finally, the scintillation light is captured in the imaging surface 3a of the online scanning sensor 3 (scintillation light imaging process). The line scan sensor 3 outputs the radiographic image data obtained by taking pictures to the image processing unit 10b of the computer 10.

[0092] The image processing unit 10b of the computer 10 inputs radiation image data and performs prescribed processing such as image processing on the input radiation image data to create a radiation image (image creation process). The image processing unit 10b outputs the created radiation image to the display device 11. The display device 11 displays the radiation image output from the image processing unit 10b. After the above process, a radiation image based on surface observation of object A is obtained.

[0093] According to the radiation detector 30 of this embodiment, a single component, namely the positioning component 70, positions the scintillator 6 via a first positioning part 71 and positions the equal-magnification lens 7 via a second positioning part 72. Because the scintillator 6a is in contact with the first positioning part 71, the positional accuracy of the input surface 6a can be easily ensured, for example, even if the thickness of the scintillator 6 changes. 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 require consideration of the positional accuracy of different components, offering advantages over conventional detectors. The distance between the input surface 6a of the scintillator 6 and one end face 7a of the equal-magnification lens 7 is also maintained constant, and the focal distance ( Figure 6 The accuracy of the working distance L1 shown is also ensured.

[0094] In existing radiation detectors, focus adjustment is required each time the thickness of the scintillator varies. However, in the radiation detector 30 of this embodiment, the scintillator 6 is fixed by contacting the input surface 6a of the scintillator 6 with the positioning member 70. Furthermore, the distance between the input surface 6a and one end face 7a of the equal-magnification lens 7, and the distance between the other end face 7c of the equal-magnification lens 7 and the imaging surface 3a, are naturally fixed, so individual focus distance adjustments are unnecessary. The input surface 6a of the scintillator 6 can be easily moved close to one end face 7a of the equal-magnification lens 7 regardless of the thickness of the scintillator 6. Because the depth of field of the bar lens array, i.e., the equal-magnification lens 7, is shallow, the positional accuracy of the input surface 6a of the scintillator 6 is very important, but according to the radiation detector 30, the scintillating light emitted from the input surface 6a can be detected appropriately.

[0095] Because the first positioning part 71 is in contact with the input surface 6a of the scintillator 6, it can easily stabilize the posture of the scintillator 6. This further improves the positional accuracy of the input surface 6a of the scintillator 6.

[0096] Because the second positioning part 72 is in contact with one end face 7a of the equal magnification lens 7, the position of the equal magnification lens 7 can be reliably and easily fixed. This further improves the positional accuracy of the equal magnification lens 7.

[0097] In addition, the relative positions of the line scan sensor 3, the equal magnification lens 7, and the scintillator 6 are determined simply by assembling the positioning component 70 with the holding component 60.

[0098] Because the positioning member 70 and the holding member 60 are fixed with a gap 69, the heat generated by the line scan sensor 3 is not easily transferred to the positioning member 70. By protecting the positioning member 70 from heat, it is easy to maintain a constant distance between the first positioning part 71 and the second positioning part 72. Even if there are deviations in the characteristics of each lens body 8, the effects of these deviations can be compensated.

[0099] The position of the flasher 6 can be easily fixed by the recess 78 formed in the positioning member 70.

[0100] Furthermore, the scintillator 6 can be reliably supported and fixed simply by fitting the support member 80 into the positioning member 70. For example, the scintillator 6 can be easily replaced if it deteriorates.

[0101] Because the support component 80 is fixed in a way that allows for adjustable intervals 89, it can accommodate scintillators of any thickness.

[0102] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the above embodiments, the manner in which the first positioning part contacts the input surface of the scintillator has been described. However, it is also possible that the first positioning part includes three or more protrusions, and the input surface of the scintillator contacts these protrusions. In this case, the front end of the protrusion defines a predetermined positioning plane for determining the position of the input surface of the scintillator. The front end of the protrusion (the part supporting the scintillator) can be a point, a line, or any planar shape. Alternatively, any combination of these shapes can be used.

[0103] In the above embodiment, the method of the second positioning part contacting one end face of the lens part has been described. However, it is also possible that the second positioning part includes three or more protrusions, and one end face of the lens part contacts these protrusions. In this case, the front end of the protrusion defines a predetermined positioning plane for determining the position of one end face of the lens part. The front end of the protrusion (the part supporting the lens part) can be point-shaped, line-shaped, or any planar shape. Alternatively, any combination of these shapes can be used.

[0104] The structure of the retaining component can be modified appropriately. For example, the portion retaining the lens and the portion retaining the sensor can be separate. Alternatively, the retaining component as described in the above embodiment can be omitted, and other suitable retaining units (such as brackets) can be used to fix the lens and / or sensor within the housing.

[0105] The shape of the recess can be appropriately modified. Alternatively, the recess may not be provided in the positioning member. A structure may also be adopted in which the scintillator contacts a plane formed on the positioning member, and the end edge of the scintillator contacts another plane intersecting that plane. That is, the recess in the above embodiment has three planes, but the positioning member may also have only two planes in contact with the scintillator.

[0106] The support component can also be omitted. In this case, a mounting structure that is fixed only by embedding the scintillator into the positioning component can be used, or an additional fastener can be installed to fix the scintillator to the support component.

[0107] The slit that serves as the path for the radiation can also be formed by a component different from the positioning component 70. Alternatively, it can be another component that keeps the retaining component 60 from being embedded in the positioning component 70 and fixed within the housing 15.

[0108] Industrial availability

[0109] According to several methods of the present invention, the positional accuracy of the input surface of the scintillator can be easily ensured, thereby maintaining a constant distance between the sensor section and the input surface of the scintillator.

[0110] Explanation of symbols

[0111] 1…Radiation image acquisition system, 3…Line scan sensor (sensor unit), 3a…Image sensor surface, 6…Scintillator, 6a…Input surface, 7…Equal magnification lens (lens unit), 7a…One end face, 8…Lens body (lens), 15…Housing, 20…Transport device, 30…Radiation detector, 60…Holding member, 62…Surface, 69…Gap, 70…Positioning member, 71…First positioning part, 72…Second positioning part, 74…First through hole, 75…Second through hole, 76…Side side, 77…Mounting surface, 78…Recess, 80…Supporting member, 82…Supporting surface, 89…Gap.

Claims

1. A radiation detector, wherein, have: Positioning component having a through hole for the passage of radiation; A scintillator having an input surface that receives the radiation passing through the through-hole and converts the radiation into scintillating light; The sensor unit has a light-receiving surface that receives the flashing light converted by the scintillator and detects the flashing light; The lens section has lenses that respectively image the input surface of the scintillator and the light-receiving surface of the sensor section. The positioning component has a first positioning part that positions the scintillator by contacting the input surface of the scintillator, and a second positioning part that positions the lens part by contacting one end face of the lens part.

2. The radiation detector according to claim 1, wherein, The first positioning part is in surface contact with the input surface of the flashing device.

3. The radiation detector according to claim 1, wherein, The second positioning part is in surface contact with one end face of the lens part.

4. The radiation detector according to claim 1, wherein, The first positioning part is in surface contact with the input surface of the flashing device. The second positioning part is in surface contact with one end face of the lens part.

5. The radiation detector according to any one of claims 1 to 4, wherein, It also includes a holding member for holding the lens portion and the sensor portion. The retaining member has a surface opposite to the side of the second positioning portion on which the positioning member is formed, and one end face of the lens portion is exposed on the surface.

6. The radiation detector according to claim 5, wherein, The positioning component and the retaining component are fixed with a gap between the side and the surface.

7. The radiation detector according to any one of claims 1 to 4, wherein, The positioning component has a recess that receives the end edge of the scintillator.

8. The radiation detector according to any one of claims 1 to 4, wherein, It also includes: a support component that engages with the positioning component to support the flashing device. The support member has a support surface opposite to the mounting surface of the first positioning portion on which the positioning member is formed, and the flasher is held between the mounting surface and the support surface.

9. The radiation detector according to claim 8, wherein, The support component is fixed to the positioning component in a manner that allows adjustment of the spacing between the mounting surface and the support surface.

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