JP2010112743A - Iation 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 cover 32. A gap 40 is formed between the cover 32 and an X-ray incident surface 29 of the scintillator layer 24. The size of the gap 40 is equal to or less than the maximum bending amount in an elastic deformation region of the cover 32 with respect to the external force. The external force applied to the outer surface of the cover 32 is received by the cover 32. The bending in the elastic deformation region is generated in the cover 32 to which the external force is applied, the cover 32 is in contact with the X-ray incident surface 29 of the scintillator layer 24, and the external force is also received by the entire scintillator layer 24. 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 a charge signal by a photoconductive film such as a-Se and led to a charge storage capacitor, and the photoconductive charge generated by the X-rays is 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 are degraded by 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 housed 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 radiation incident surface on the opposite side of the light detection substrate that is provided on the light detection substrate. A radiation detector body having a scintillator layer that converts radiation incident from a radiation incident surface into light; and a housing that houses the radiation detector body in a sealed state, the housing being the radiation detector body A base on which the photodetecting substrate is disposed on one surface, a surface portion facing the radiation incident surface of the scintillator layer of the radiation detector body, and a side wall portion formed on the periphery of the surface portion, A space is provided between the surface portion and the radiation incident surface of the scintillator layer, and the size of the space is set to be equal to or less than the maximum deflection amount in the elastic deformation region of the surface portion with respect to an external force, and the side wall portion is formed on the base. Fixed to the upper supporting said surface portion relative to the base, the one in which and a cover enclosing the radiation detector body between said base.

  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 for converting light into an electrical signal is provided. A method of manufacturing a radiation detector for housing a provided radiation detector main body in a casing having a base and a cover, the step of arranging a light detection substrate of the radiation detector main body on one surface of the base A gap is provided between the surface portion of the cover and the radiation incident surface of the scintillator layer, and the size of the gap is set to be equal to or less than the maximum deflection amount in the elastic deformation region of the surface portion with respect to an external force. A side wall formed on the periphery of the surface portion is fixed on one surface of the base to support the surface with respect to the base, and the radiation detector main body is disposed between the base and the cover. Sealing process It is one that is equipped with a.

  According to the present invention, a gap is provided between the surface portion of the cover and the radiation incident surface of the scintillator layer, and the size of the gap is set to be equal to or less than the maximum deflection amount in the elastic deformation region of the surface portion with respect to an external force. Since the part is fixed on one surface of the base and the surface part is supported against the base, when an external force is applied to the surface of the cover, the external force is received by the cover and is bent in the elastic deformation region. The cover is in contact with the scintillator layer and part of the external force is received by the scintillator layer, which distributes stress throughout the radiation detector, reducing stress concentration in the scintillator layer, improving reliability, downsizing, and various characteristics Can be improved.

  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 formed 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 cover 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 cover 32 has a surface portion 38 that faces 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. Yes.

The surface portion 38 of the cover 32 is disposed between the X-ray incident surface 29 of the scintillator layer 24 with a gap 40 that is less than or equal to the maximum deflection amount in the elastic deformation region with respect to the external force of the cover 32. The front end portion of the side wall portion 39 of the cover 32 is fixed on one surface of the base 31 and supports the surface portion 38 with respect to the base 31.

  In order to manufacture the X-ray detector 11, the X-ray detector main body 12 is disposed and fixed on the base 31, the cover 32 is disposed on the base 31, and the side wall 39 of the cover 32 is provided. For example, an epoxy resin bonding layer 45 is used to fix the front end of the base plate 31 to the base 31 in a sealed state.

  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 gap 40 is provided between the surface portion 38 of the cover 32 and the X-ray incident surface 29 of the scintillator layer 24, and the size of the gap 40 is set within the elastic deformation region of the surface portion 38 with respect to external force. In order to fix the side wall portion 39 of the cover 32 on one surface of the base 31 and support the surface portion 38 against the base 31, an external force is applied to the surface portion 38 of the cover 32. In this case, the external force is received by the cover 32, and the cover 32 bent in the elastic deformation region is in contact with the scintillator layer 24 and a part of the external force is also received by the scintillator layer 24, whereby the entire X-ray detector 11 is The stress can be dispersed to reduce the stress concentration in the scintillator layer 24, improving reliability, downsizing, and improving various characteristics.

Further, when an external force is applied to the X-ray detector 11, the cover 32 can be approximated by a four-sided fixed model with uniform distribution load in terms of material mechanics. If the maximum bending stress is σmax,
ωmax = α · p · a ⁴ / E · h ³ (1)
σmax = β · p · a ² / h ² (2)
α: Maximum bending coefficient of structure β: Maximum stress coefficient of structure p: Load per unit area E: Young's modulus of structure a: Short side length of structure h: Thickness of structure. Therefore, when the load per unit area that causes the cover 32 to cause the maximum deflection in the elastic deformation region with respect to the external force is p _e and the maximum deflection amount in the elastic deformation region with respect to the external force of the cover 32 is ω _e , From equation (2)
ω _e = α · _pe · a ⁴ / E · h ³ (3)
^{_{p e = σ e · h 2}} / β · a 2 ... (4)
From these equations (3) and (4),
ω _e = α · σ _e · a ² / β · E · h (5)
α: Maximum bending coefficient of structure β: Maximum stress coefficient of structure σ _e : Strength of structure E: Young's modulus of structure a: Short side length of structure h: Thickness of structure.

For this reason, if the dimension of the gap 40 between the cover 32 and the X-ray incident surface 29 of the scintillator layer 24 is equal to or less than ω _e, the external force applied to the X-ray detector 11 is removed. Since the shape returns to the state before the external force is applied to the X-ray detector 11, the gap 40 between the cover 32 and the X-ray detector 11 of the scintillator layer 24 is maintained. Since it is not optically affected by direct contact with the 24 X-ray incident surfaces 29, stable characteristics of the X-ray detector 11 can be obtained.

  The cover 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. The side wall portion 39 is a base. Since it is fixed on one surface 31 and supports the surface portion 38 against the base 31, the rigidity of the cover 32 against external force can be increased.

  When the material of the cover 32 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 external force and the reliability of electromagnetic waves can be improved. Since the transmittance can be made zero, it is possible to prevent deterioration of various characteristics of the X-ray detector 11 even when a halogen compound such as CsI having deliquescence is used as the scintillator layer 24.

  The configuration and manufacturing method of the cover 32 of the X-ray detector 11 are not limited to the first embodiment shown in FIG. 1, but may be the second embodiment shown in FIG.

  That is, in the second embodiment shown in FIG. 2, the cover 32 is disposed on the base 31 to which the X-ray detector main body 12 is fixed, and the liquid bonding material of the bonding layer 45 is replaced with the base 31 and the cover. Pour between 32 and cure the bonding material. At this time, by adjusting the injection amount of the bonding material injected between the base 31 and the cover 32, the bonding material can be prevented from coming into contact with and impregnating the X-ray incident surface 29 of the scintillator layer 24.

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

  Further, as in the third and fourth embodiments shown in FIGS. 3 and 4, respectively, a protective layer 51 covering the entire scintillator layer 24 may be formed. The protective layer 51 is formed of a material such as polyparaxylylene having water vapor barrier properties.

  Between the cover 32 and the protective layer 51 that covers the X-ray incident surface 29 of the scintillator layer 24, a gap 40 that is equal to or less than the maximum deflection amount in the elastic deformation region with respect to the external force of the cover 32 is formed.

  The configuration and manufacturing method of the X-ray detector 11 in the third and fourth embodiments shown in FIGS. 3 and 4 are the same as those of the first and second embodiments shown in FIGS. 1 and 2, respectively. It is the same.

  Therefore, also in these 3rd and 4th embodiment, there exists an effect similar to 1st Embodiment mentioned above.

  As an embodiment of the present invention, for example, in the X-ray detector 11 of the fourth embodiment shown in FIG. 4, the cover 32 is made of Al (5052-H32), and the cover 32 has a thickness of 0.5 mm. The dimension of the gap 40 is 0.1 mm, the material of the bonding layer 45 is epoxy resin, the material of the scintillator layer 24 is CsI (Tl Dope), the material of the protective layer 51 is polyparaxylylene, and the outer dimension of the cover 32 is 45 mm. Consider a configuration example in which (L) × 35 mm (W) and the external dimensions of the scintillator layer 24 are 40 mm (L) × 30 mm (W).

In the configuration example of the present embodiment, ω _e is α = 0.03 from the short side length of the scintillator layer 24, the plate thickness of the outermost cover 32 of the cover 32, and the mechanical properties of Al (5052-H32). By substituting β = 0.5, σ _e = 195 N / mm ² , E = 70 kN / mm ² , a = 30 mm, and h = 0.5 mm into the above equation (5), ω _e ≈0.3 mm.

Here, the value of ω _e (0.3 mm) in the configuration example of the present embodiment is larger than the value of the gap 40 (0.1 mm) between the cover 32 and the X-ray incident surface 29 of the scintillator layer 24. Therefore, when an external force is applied to the X-ray detector 11, the cover 32 is bent in the elastic deformation region, and the cover 32 comes into contact with the X-ray incident surface 29 of the scintillator layer 24. The external force is uniformly applied to the entire line detector 11.

As a result, stress concentration does not occur in the scintillator layer 24 that is structurally low in strength against external force, so that reliability of the external force of the X-ray detector 11 is ensured and the external force applied to the X-ray detector 11 is removed. In this case, since the shape of the cover 32 returns to the state before the external force is applied to the X-ray detector 11, the gap 40 between the cover 32 and the X-ray incident surface 29 of the scintillator layer 24 is maintained. Therefore, since the cover 32 is not optically affected by direct or indirect contact with the X-ray incident surface 29 of the scintillator layer 24, various characteristics of the X-ray detector 11 can be obtained stably.
Next, as a comparative example with respect to the configuration example of the present embodiment, the configuration example of FIG. 6 is shown (the same reference numerals are used for the same structures as those of the embodiment of the present invention). In the X-ray detector 11 of the comparative example shown in FIG. 6, the material of the cover 32 is Al (5052-H32), the thickness of the cover 32 is 0.5 mm, the gap 40 is 0.5 mm, and the material of the bonding layer 45 is The material of the epoxy resin, the scintillator layer 24 is CsI (Tl Dope), the material of the protective layer 51 is polyparaxylylene, the outer dimension of the cover 32 is 45 mm (L) × 35 mm (W), and the outer dimension of the scintillator layer 24 is 40 mm (L) × 30 mm (W).

In this comparative example, ω _e is α = 0.03, β = 0.5, σ _e = 195 N from the short side length of the scintillator layer 24, the plate thickness of the cover 32, and the mechanical characteristics of Al (5052-H32). Substituting / mm ² , E = 70 kN / mm ² , a = 35 mm, and h = 0.5 mm into the above equation (5), ω _e ≈0.4 mm.

Here, since the value of ω _e (0.4 mm) in the comparative example is smaller than the value of the gap 40 (0.5 mm) between the cover 32 and the X-ray incident surface 29 of the scintillator layer 24, the X-ray When an external force of a certain level or more is applied to the detector 11, the plastic deformation region of the cover 32 is bent. Therefore, even if the external force applied to the X-ray detector 11 is removed, the cover 32 remains bent. For this reason, since the gap 40 between the cover 32 and the X-ray incident surface 29 of the scintillator layer 24 is not maintained, the reliability against the external force of the X-ray detector 11 cannot be ensured.

FIG. 5 shows that the entire surface portion 38 of the cover 32 is 5 kg / cm ² , 10 kg / cm ² , 15 kg / cm in the X-ray detector 11 of the present embodiment and the X-ray detector 11 of the comparative example. The results of inspecting whether or not the X-ray detector 11 is damaged for each pressure when each pressure of cm ² and 20 kg / cm ² is applied are shown.

  In the X-ray detector 11 of the comparative example, the pressure applied to the cover 32 causes the cover 32 to be plastically deformed or the base 31 to be damaged, thereby causing stress concentration in 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.

  On the other hand, in the X-ray detector 11 of the present embodiment, the cover 32, the base 31, and the scintillator layer 24 are not deformed or damaged, and the reliability with respect to the external force of the X-ray detector 11 can be secured. became.

  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.

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 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 3rd 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 Cover
38 Surface
39 Side wall
40 Air gap

Claims (2)

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 housing for housing the radiation detector body in a sealed state;
The housing is
A base on which a light detection substrate of the radiation detector body is arranged on one surface;
A surface portion facing the radiation incident surface of the scintillator layer of the radiation detector main body, and a side wall portion formed in a peripheral portion of the surface portion, and between the surface portion and the radiation incident surface of the scintillator layer A space is provided, and the size of the space is set to be equal to or less than the maximum deflection amount in the elastic deformation region of the surface portion with respect to an external force, and the side wall portion is fixed on one surface of the base, and the surface portion with respect to the base And a cover that seals the main body of the radiation detector between the base and the base. A radiation detector main body provided with a scintillator layer for converting radiation incident on a light detection substrate that converts light into an electrical signal into light from a radiation incident surface opposite to the light detection substrate. A method of manufacturing a radiation detector housed in a housing having
Placing the light detection substrate of the radiation detector body on one surface of the base;
A space is provided between the surface portion of the cover and the radiation incident surface of the scintillator layer, and the size of the space is not more than the maximum deflection amount in the elastic deformation region of the surface portion with respect to an external force. A side wall formed on the periphery of the base is fixed on one surface of the base to support the surface with respect to the base, and the radiation detector main body is sealed between the base and the cover. And a process for producing a radiation detector.

Images