JP2010112741A - Radiation detector and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray detector 11 improving reliability, achieving reduction in size, and improving various characteristics. <P>SOLUTION: An X-ray detector body 12 including a photo detection substrate 21 and a scintillator layer 24 is housed in a case 13 including a base 31 and a multiple cover body 32. A plurality of covers 37 of the multiple cover body 32 are disposed opposite an X-ray incident surface 29 of the scintillator layer 24 in a multiple manner, and the innermost cover 37 is directly in contact with the X-ray incident surface 29 of the scintillator layer 24. When external force is applied to the outer surface of the multiple cover body 32, the external force is received by the plurality of covers 37, and also received by the entire scintillator layer 24 via the innermost cover 37. Accordingly, the stress is dispersed to the entire X-ray detector 11, and the stress concentration is reduced by the scintillator layer 24 to improve reliability, to achieve reduction in size, and to improve various characteristics. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation detector for detecting radiation and a method for manufacturing the same.

  As a new generation image detector for X-ray diagnosis, a planar X-ray detector using an active matrix or a solid-state imaging device (CCD, CMOS, etc.) is attracting attention. By irradiating the X-ray detector with X-rays, an X-ray image or a real-time X-ray image is output as a digital signal. Since this X-ray detector is a solid state detector, it is highly expected in terms of image quality performance and stability, and a lot of research and development is being conducted.

  The main application of an X-ray detector using an active matrix has been developed for breast imaging or general imaging for collecting still images with a relatively large dose, and has been commercialized in recent years. Commercialization is expected in the near future for applications in the fields of circulatory organs and digestive organs that require higher performance and real-time moving images of 30 frames / sec or more under fluoroscopic dose. For this video application, improvement of S / N, real-time processing technology of minute signals, and the like are important development items.

  The main applications of X-ray detectors using solid-state image sensors (CCD, CMOS, etc.) are industrial nondestructive inspections that collect still images with large doses, and still images that are inserted into the oral cavity. In recent years, dentistry and other products have been commercialized, but it is important to improve S / N, real-time processing of minute signals, miniaturization of X-ray detectors, improvement of reliability, including support for moving images. It is a development item.

  X-ray detectors are roughly classified into two methods, a direct method and an indirect method. The direct method is a method in which X-rays are directly converted into charge signals by a photoconductive film such as a-Se and led to a charge storage capacitor, and the photoconductive charges generated by the X-rays are directly stored by a high electric field. Therefore, the resolution characteristic defined by the pixel electrode pitch of the active matrix can be obtained. On the other hand, the indirect method is a method in which X-rays are once converted into visible light by the scintillator layer, and the visible light is converted into signal charges by an a-Si photodiode, CCD, CMOS, etc., and led to the charge storage capacitor. Resolution characteristics deteriorate due to optical diffusion and scattering until visible light from the scintillator layer reaches the photodiode, CCD, and CMOS.

  Usually, in the indirect X-ray detector, the characteristics of the scintillator layer are important due to the structure, and in order to improve the output signal intensity with respect to incident X-rays, for example, the scintillator layer has a halogen compound such as CsI, GOS or the like. In many cases, a high-intensity fluorescent material composed of such an oxide compound is used. In particular, when a halogen compound such as CsI is used for the scintillator layer, resolution characteristics can be improved by forming the scintillator layer having a strip-like columnar crystal structure using a vacuum deposition method. However, when a halogen compound such as CsI, which is a high-intensity fluorescent material, is used for the scintillator layer, there is a risk that the scintillator layer will deliquesce by reacting with moisture in the atmosphere, so a protective layer may be formed on the scintillator layer, The scintillator layer is covered with a protective cover and sealed (for example, see Patent Document 1).

Further, in a general indirect X-ray detector, an X-ray detector main body including a scintillator layer is accommodated in a housing in order to protect from an external force (see, for example, Patent Documents 2 and 3).
Japanese translation of PCT publication No. 2002-518686 (7th page, FIG. 1) JP 2006-58124 A (page 5-6, FIG. 1) JP 2008-107134 A (page 3, FIG. 1)

  In general, since the scintillator layer is structurally low in strength against external force, especially in X-ray detectors for dental and industrial applications where external force is likely to be applied, the external force causes the housing to be plastically deformed. When is added to the scintillator layer, stress concentration occurs in the scintillator layer and it is damaged. Therefore, the casing has a solid structure that does not cause plastic deformation. However, when the housing has a solid structure, the reliability against external force is improved, but there are problems that the X-ray detector is enlarged and various characteristics including X-ray transmission characteristics are deteriorated.

  The present invention has been made in view of these points, and an object thereof is to provide a radiation detector capable of improving reliability, downsizing, and improving various characteristics, and a method for manufacturing the same.

  The radiation detector according to the present invention includes a light detection substrate that converts light into an electrical signal, and a surface opposite to the light detection substrate that is provided on the light detection substrate. A radiation detector main body having a scintillator layer for converting radiation incident from the radiation incident surface into light, and a plurality of covers are arranged in a multiple manner facing the radiation incident surface of the scintillator layer, and the innermost cover is the scintillator layer It has a multiple cover body in contact with the radiation incident surface, and a housing that houses the radiation detector main body in a sealed state.

  Further, in the method for manufacturing a radiation detector according to the present invention, a scintillator layer for converting radiation incident from a radiation incident surface opposite to the light detection substrate onto the light detection substrate that converts light into an electrical signal is provided. A method of manufacturing a radiation detector for accommodating a provided radiation detector main body in a casing having a base and a multiple cover body, wherein a light detection substrate of the radiation detector main body is disposed on one surface of the base A plurality of covers of the multi-cover body, a plurality of covers facing the radiation incident surface of the scintillator layer, and an innermost cover in contact with the radiation incident surface of the scintillator layer; A step of filling an organic continuous polymer between the covers of the cover body and sealing the radiation detector body between the base and the multiple cover body.

  According to the present invention, the plurality of covers of the multiple cover body are arranged in multiple positions so as to face the radiation incident surface of the scintillator layer, and the innermost cover is directly or via a protective layer on the radiation incident surface of the scintillator layer. Indirect contact is made so that when external force is applied to the outer surface of the multiple cover body, the external force is received by a plurality of covers, and the entire scintillator layer is also received via the innermost cover, whereby the radiation detector Stress can be dispersed throughout, reducing stress concentration in the scintillator layer, improving reliability, downsizing, and improving various characteristics.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, 11 is an X-ray detector as a radiation detector, which is an indirect X-ray planar image detector. The X-ray detector 11 includes an X-ray detector main body 12 as a radiation detector main body, and a housing 13 that accommodates the X-ray detector main body 12 in a sealed state.

  The X-ray detector main body 12 converts a light detection substrate 21 that converts light into an electrical signal, and converts the X-ray 22 that is provided on the light detection substrate 21 into light 23 that is visible light. A scintillator layer 24 is provided.

  The light detection substrate 21 is a solid-state imaging device, and is electrically connected to the light receiving unit 27 and the photoelectric conversion device 26, in which at least a plurality of photoelectric conversion devices 26 are arranged one-dimensionally or two-dimensionally on the substrate 25. A connected electrode pad 28 is formed.

  The scintillator layer 24 is formed on the light receiving portion 27 of the light detection substrate 21, and the surface opposite to the light detection substrate 21 side is used as an X-ray incident surface 29 as a radiation incident surface on which the X-rays 22 are incident. Yes. The scintillator layer 24 is made of, for example, a high-intensity fluorescent material composed of a halogen compound such as CsI or an oxide compound such as GOS. In particular, when a halogen compound such as CsI is used, resolution characteristics can be improved by forming the scintillator layer 24 having a strip-like columnar crystal structure by a vacuum deposition method.

  The housing 13 has a base 31 on which the light detection substrate 21 of the X-ray detector main body 12 is arranged and fixed on one surface, and the X-ray detector main body 12 is hermetically sealed between the base 31. And a multiple cover body 32 for housing.

  On one surface of the base 31, an external connection electrode pad 33 is provided on the side where the light detection substrate 21 is disposed. The electrode pads 28 of the light detection substrate 21 and the external connection electrode pads 33 are electrically connected by wirings 34, and these electrical connection portions are covered with an insulating layer 35 mainly made of a resin material. An electrode terminal 36 electrically connected to the external connection electrode pad 33 is provided on the outer surface of the base 31.

  The multiple cover body 32 is provided with a plurality of covers 37 that are arranged in multiple layers, the outer shape of the outer cover 37 is larger than the outer shape of the inner cover 37, and the outer side of the inner cover 37 is outside. Covers 37 are arranged in multiple layers. These covers 37 have a surface portion 38 facing the X-ray incident surface 29 of the scintillator layer 24, and a side wall portion 39 that integrally protrudes from the peripheral portion of the surface portion 38 toward the base 31. ing. The surface portion 38 of the inner cover 37 is in direct contact with the X-ray incident surface 29 of the scintillator layer 24. The front end portion of the side wall portion 39 of each cover 37 is fixed on one surface of the base 31 and supports the surface portion 38 with respect to the base 31.

  The inner cover 37 and the outer cover 37 are formed of different materials, for example, the material of the inner cover 37 is PPS and the material of the outer cover 37 is Al.

  A space between the covers 37 of the multiple cover body 32 is filled with at least an organic continuous polymer 41 such as a silicone resin. This continuous polymer 41 is not in contact with the X-ray incident surface 29 of the scintillator layer 24. Further, the elastic coefficient of the continuous polymer 41 has a smaller relationship than the elastic coefficient of the cover 37. Furthermore, the linear thermal expansion coefficient of the nth cover 37 from the inside of the multiple cover body 32 is An, the linear thermal expansion coefficient of the (n + 1) th cover 37 is An + 1, and the nth cover 37 and the (n + 1) th cover 37 are between. When the linear thermal expansion coefficient of the continuous polymer 41 to be filled is Bn, there is a relationship of An <Bn <An + 1 or An> Bn> An + 1.

  In order to manufacture the multiple cover body 32, for example, a plurality of covers 37 are arranged on the base 31 on which the light detection substrate 21 is fixed, and a liquid continuous polymer 41 is inserted between the covers 37 from an injection portion (not shown). Inject and fill. The continuous polymer 41 filled between the covers 37 is cured, so that the inner cover 37 and the outer cover 37 are integrated. Further, a part of the liquid continuous polymer 41 filled between the covers 37 flows out from the front end portion of the side wall portion 39 of each cover 37 and comes into contact with one surface of the base 31. The side wall 39 is fixed to the base 31 by curing, and the space between the multiple cover body 32 and the base 31 is sealed.

  In the X-ray detector 11 configured as described above, the light 23 converted by the scintillator layer 24 by the incident X-rays 22 reaches the photoelectric conversion element 26 of the light detection substrate 21, whereby the photoelectric conversion element 26 charges. Is converted and stored. The charges accumulated in the photoelectric conversion elements 26 are transmitted from the signal lines (not shown) corresponding to the photoelectric conversion elements 26 to the electrode pads 28 corresponding to the photoelectric conversion elements 26, the wiring 34, and the electrode pads 33 for external connection of the base 31. And sequentially read out as an output signal via the electrode terminal 36. The read output signal is converted into a digital image signal by a predetermined signal processing circuit or the like.

  In the X-ray detector 11, a plurality of covers 37 of the multiple cover body 32 are arranged in multiple positions so as to face the X-ray incident surface 29 of the scintillator layer 24, and the innermost cover 37 is placed on the X-rays of the scintillator layer 24. Since it is in direct contact with the incident surface 29, when an external force is applied to the outer surface of the multiple cover body 32, the external force is received by a plurality of covers 37 and the entire scintillator layer 24 is passed through the innermost cover 37. However, it is possible to disperse stress throughout the X-ray detector 11 and reduce stress concentration in the scintillator layer 24, thereby improving reliability, downsizing, and improving various characteristics.

  Since the inner cover 37 of the multiple cover body 32 is in direct contact with the X-ray incident surface 29 of the scintillator layer 24, the X-ray detector 11 can be changed by changing the reflectance of the inner cover 37 with respect to the light 23. It is also possible to vary the various characteristics.

  Each cover 37 of the multiple cover body 32 has a surface portion 38 facing the X-ray incident surface 29 of the scintillator layer 24 and a side wall portion 39 formed integrally with the peripheral portion of the surface portion 38. Since 39 is fixed on one surface of the base 31 and supports the surface portion 38 with respect to the base 31, the rigidity of the cover 37 against external force can be increased.

  In the multiple cover body 32, when the material of at least one cover 37 is a metal made of a light element such as Al having a high X-ray transmittance, the reliability of the X-ray detector 11 with respect to the external force and the reliability with respect to electromagnetic waves can be improved. Furthermore, since the water vapor transmission rate of the multiple cover body 32 can be made zero, even when a halogen compound such as CsI having deliquescence is used as the scintillator layer 24, the X-ray detector 11 It is possible to prevent the deterioration of various characteristics.

  In addition, since the continuous polymer 41 is filled between the covers 37 of the multiple cover body 32, the continuous polymer 41 functions as a damper against the external force applied to the multiple cover body 32, and the rigidity of the multiple cover body 32 against the external force. Can be increased.

  By making the elastic coefficient of the continuous polymer 41 smaller than that of the cover 37, when an external force is applied to the multiple cover body 32, the external force applied by the continuous polymer 41 can be dispersed and absorbed. .

  By providing the continuous polymer 41 between the covers 37 in this way, it becomes possible to ensure reliability against external force without making each cover 37 a rigid structure, and thus the X-ray detector 11 can be downsized. .

  Furthermore, the linear thermal expansion coefficient of the nth cover 37 from the inside of the multiple cover body 32 is An, the linear thermal expansion coefficient of the (n + 1) th cover 37 is An + 1, and the nth cover 37 and the (n + 1) th cover 37 are between. When the linear thermal expansion coefficient of the continuous polymer 41 to be filled is Bn, if the relationship of An <Bn <An + 1 or An> Bn> An + 1 is satisfied, the difference in the linear thermal expansion coefficient of each cover 37 is obtained. Since the influence of the accompanying stress can be reduced, the reliability of the X-ray detector 11 with respect to a temperature change can be improved.

  Further, since the continuous polymer 41 filled between the covers 37 of the multiple cover body 32 is not in contact with the X-ray incident surface 29 of the scintillator layer 24, the continuous polymer 41 is impregnated into the scintillator layer 24. It is possible to prevent the deterioration of various characteristics.

  The configuration and the manufacturing method of the multiple cover body 32 of the X-ray detector 11 are not limited to the first embodiment shown in FIG. 1, but the second to fourth embodiments shown in FIGS. 2 to 4, respectively. You may make it like a form.

  That is, in the second embodiment shown in FIG. 2, a plurality of covers 37 are arranged on a base 31 to which the X-ray detector main body 12 is fixed, and the liquid continuous polymer 41 is connected to the base 31 and the cover. It is injected from one end side between the cover 37 and the space between the cover 37 and between the base 31, the X-ray detector main body 12 and the inner cover 37, and between the base 31 and the cover 37. Next, the continuous polymer 41 is cured after flowing out from the other end. At this time, since the inner cover 37 is in direct contact with the X-ray incident surface 29 of the scintillator layer 24, the continuous polymer 41 is not impregnated from the X-ray incident surface 29 of the scintillator layer 24.

  As shown in the third embodiment of FIG. 3, a base 31 on which an X-ray detector main body 12 is fixed is formed by previously filling a continuous polymer 41 between covers 37 to form an integrated multiple cover 32. The multiple cover body 32 is arranged on the top, and the tip of the side wall portion 39 of the multiple cover body 32 and the base 31 are fixed in a sealed state by, for example, an epoxy resin bonding layer 45.

  As shown in the fourth embodiment of FIG. 4, an inner cover 37 is arranged on a base 31 to which the X-ray detector main body 12 is fixed, and the liquid continuous polymer 41 is connected to the base 31 and the inner side. The other end between the base 31 and the cover 37 is filled with the space between the base 31, the X-ray detector main body 12 and the inner cover 37. The continuous polymer 41 is cured after flowing from the side and being applied to the outer surface of the inner cover 37. At this time, since the inner cover 37 is in direct contact with the X-ray incident surface 29 of the scintillator layer 24, the continuous polymer 41 is not impregnated from the X-ray incident surface 29 of the scintillator layer 24. Thereafter, the outer cover 37 is put on the outer side of the inner cover 37, and the space between the tip of the side wall 39 of the outer cover 37 and the base 31 is fixed in a sealed state by the bonding layer 45.

  In the second to fourth embodiments, the same operational effects as those of the above-described first embodiment can be obtained.

  Further, a protective layer 51 covering the entire scintillator layer 24 may be formed as in the fifth to eighth embodiments shown in FIGS. The protective layer 51 is formed of a material such as polyparaxylylene having water vapor barrier properties.

  The cover 37 inside the multiple cover body 32 indirectly contacts the X-ray incident surface 29 of the scintillator layer 24 via the protective layer 51.

  The structure and the manufacturing method of the multiple cover body 32 of the X-ray detector 11 in the fifth to eighth embodiments shown in FIGS. 5 to 8 are the first to fourth shown in FIGS. 1 to 4, respectively. This is the same as the embodiment.

  Therefore, these fifth to eighth embodiments also have the same effects as the first embodiment described above.

  Further, as an embodiment of the present invention, for example, the X-ray detector 11 of the eighth embodiment shown in FIG. 8 and the X-ray detector 11 of the comparative example shown in FIG. When the external force is applied to the same structure as that of the embodiment, the presence of damage to the X-ray detector 11 is inspected.

  For the X-ray detector 11 of the present embodiment, the number of overlapping covers 37 of the multiple cover body 32 is 2, the material of the innermost cover 37 is PPS, the thickness of the innermost cover 37 is 0.2 mm, The material of the outer cover 37 is Al, the thickness of the outermost cover 37 is 0.2 mm, the material of the continuous polymer 41 is a silicone resin, the thickness of the continuous polymer 41 is 0.1 mm, and the material of the bonding layer 45 is The material of the epoxy resin, the scintillator layer 24 is CsI (Tl Dope), and the material of the protective layer 51 is polyparaxylylene.

  In the X-ray detector 11 of the comparative example shown in FIG. 10, the cover 37 is single, and the side wall portion 39 of the cover 37 is in a state where the surface portion 38 of the cover 37 is separated from the X-ray incident surface 29 of the scintillator layer 24. The tip and the base 31 were fixed with a bonding layer 45. For the X-ray detector 11 of this comparative example, the cover 37 is made of Al, the cover 37 is 0.5 mm thick, the bonding layer 45 is made of epoxy resin, and the scintillator layer 24 is made of CsI (Tl Dope). The material of the protective layer 51 was polyparaxylylene.

FIG. 9 shows that the entire surface portion 38 of the cover 37 is 5 kg / cm ² , 10 kg / cm ² , 15 kg / cm ^{2 in} the X-ray detector 11 of the present embodiment and the X-ray detector 11 of the comparative example. The results of examining whether or not the X-ray detector 11 is damaged for each pressure when each pressure of 20 kg / cm ² is applied are shown.

  In the X-ray detector 11 of the comparative example, the pressure applied to the cover 37 causes the cover 37 to be plastically deformed or the base 31 to be damaged, thereby causing stress concentration on the scintillator layer 24 and causing damage. As a result, the reliability with respect to the external force of the X-ray detector 11 cannot be secured.

  In contrast, in the X-ray detector 11 of the present embodiment, the multiple cover body 32, the base 31, and the scintillator layer 24 are not deformed or damaged, and the reliability of the X-ray detector 11 with respect to the external force can be secured. As a result.

  For this reason, the X-ray detector 11 according to the present embodiment can be packaged even by a molding technique such as hot melt molding in which an external force is applied to the entire X-ray detector 11, so that the use environment is severe and high. It can be used for X-ray detectors 11 for dental and industrial applications that require reliability and downsizing.

  Note that the multiple cover body 32 is not limited to being configured by the double cover 37, and may be configured by a triple or more cover 37.

It is sectional drawing of the radiation detector which shows the 1st Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 2nd Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 3rd Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 4th Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 5th Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 6th Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 7th Embodiment of this invention. It is sectional drawing of the radiation detector which shows the 8th Embodiment of this invention. It is a table | surface which shows the result of having test | inspected the presence or absence of the damage with respect to the pressure in the radiation detector of the 8th Embodiment of this invention, and the radiation detector of a comparative example. It is sectional drawing which shows the radiation detector of a comparative example.

Explanation of symbols

11 X-ray detectors as radiation detectors
12 X-ray detector body as a radiation detector body
13 Enclosure
21 Light detection board
22 X-rays as radiation
23 Light
24 Scintillator layer
29 X-ray entrance surface as radiation entrance surface
31 base
32 Multiple cover body
37 Cover
38 Surface
39 Side wall
41 Continuous polymer
51 Protective layer

Claims (9)

A light detection substrate that converts light into an electrical signal, and a radiation incident surface on which the radiation is incident on a surface opposite to the light detection substrate that is provided on the light detection substrate. A radiation detector body having a scintillator layer for converting to light;
A plurality of covers are arranged in multiple layers facing the radiation incident surface of the scintillator layer, and the innermost cover has a multiple cover body in contact with the radiation incident surface of the scintillator layer, and accommodates the radiation detector body in a sealed state A radiation detector. The radiation detector body has a protective layer covering the scintillator layer,
2. The radiation detector according to claim 1, wherein an innermost cover of the multiple cover body of the housing indirectly contacts a radiation incident surface of the scintillator layer via the protective layer. The housing includes a base on which a light detection substrate of the radiation detector main body is disposed on one surface,
Each cover of the multiple cover body has a surface portion facing the radiation incident surface of the scintillator layer, and a side wall portion formed in a peripheral portion of the surface portion, and the side wall portion is on one surface of the base. The radiation detector according to claim 1, wherein the radiation detector is fixed and supports the surface portion with respect to the base, and seals the scintillator layer between the base and the base. The radiation detector according to any one of claims 1 to 3, wherein the multiple cover body has a cover formed of a different material. The radiation detector according to any one of claims 1 to 4, wherein a space between the covers of the multiple cover body is filled with at least an organic continuous polymer. The radiation detector according to claim 5, wherein an elastic coefficient of the continuous polymer is smaller than an elastic coefficient of the cover. The linear thermal expansion coefficient of the nth cover from the inside of the multiple cover body is An, the linear thermal expansion coefficient of the (n + 1) th cover is An + 1, and the continuous weight is filled between the nth cover and the (n + 1) th cover. 7. The radiation detector according to claim 5, wherein when the combined linear thermal expansion coefficient is Bn, any relationship of An <Bn <An + 1 and An>Bn> An + 1 is established. A radiation detector body provided with a scintillator layer for converting radiation incident from a radiation incident surface opposite to the light detection substrate onto the light detection substrate that converts light into an electrical signal, A method of manufacturing a radiation detector accommodated in a housing having a cover body,
Placing the light detection substrate of the radiation detector body on one surface of the base;
A plurality of covers of the multiple cover body are arranged in multiple positions facing the radiation incident surface of the scintillator layer, and the innermost cover is brought into contact with the radiation incident surface of the scintillator layer;
Filling a continuous polymer of organic matter between the covers of the multiple cover body, and sealing the radiation detector main body between the base and the multiple cover body. Manufacturing method of the detector. The radiation detector body is provided with a protective layer covering the scintillator layer,
The method for manufacturing a radiation detector according to claim 8, wherein the innermost cover is brought into indirect contact with a radiation incident surface of the scintillator layer through the protective layer.

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