JP5518457B2 - Radiation detector and scintillator panel - Google Patents

Description

  The present invention relates to a radiation detector and a scintillator panel having a phosphor layer that converts incident X-rays into visible light.

  Radiation detectors used for medical, dental or industrial non-destructive inspections, such as computed radiology (hereinafter referred to as CR) and flat panel detector (hereinafter referred to as FPD), emit X-rays as a phosphor. The method of converting into visible light by the layer is the mainstream.

  FPD includes a form in which a phosphor layer is directly formed on the photoelectric conversion element of a sensor having a photoelectric conversion element, and a form in which a scintillator panel having a phosphor layer is bonded on the photoelectric conversion element of the sensor.

  A radiation detector in which a phosphor layer is directly formed on a sensor having a photoelectric conversion element is disclosed in Patent Document 1, for example.

  In this radiation detector, a scintillator layer is vapor-deposited on a substrate having a photoelectric conversion element, a reflective layer in which a reflective material is dispersed in an organic paste is applied and formed thereon, and a moisture-proof body is further applied to end portions of the moisture-proof body. Is sealed with an adhesive layer.

  However, such a radiation detector has a problem that the adhesion between the phosphor layer and the substrate is weak.

  The cause of this weak adhesion is that the adhesion between the vapor deposition film and the substrate is only an intermolecular force, and that the thermal expansion coefficient is different between the substrate and the phosphor layer, Can be considered. These can be alleviated to some extent by selecting the material of the substrate matrix (usually liquid crystal glass) and the material of the outermost surface, but the fundamental solution is difficult.

  Further, when the phosphor layer is formed by a vacuum deposition method, a tapered portion is formed at the cross-sectional end of the phosphor layer. The cause of the taper at the edge is the structure of the vapor deposition mask that fixes the substrate.

  In other words, when a phosphor is deposited on a substrate fixed to a deposition mask, it is expected that a phosphor layer is uniformly formed on the entire surface that is not masked by the deposition mask. This shadow causes a tapered portion having a small taper angle at the end of the phosphor layer.

  On the other hand, a scintillator panel in which a phosphor layer is not directly formed on a photoelectric conversion element is described in Patent Document 2, for example.

In this scintillator panel, a sheet in which bubbles and TiO ₂ are dispersed in a resin sheet is adhered to both surfaces of a CFRP (carbon fiber reinforced plastic) support substrate, a phosphor layer is provided on the sheet, and a moisture-proof layer is formed on the phosphor layer. It is formed covering the entire surface. The moisture-proof layer and the sheet are in close contact with each other at the periphery of the phosphor layer, and this forms a sealing structure for the moisture-proof layer.

  However, even in the case of such a structure, the situation is similar to the case of the radiation detector directly formed on the above-described photoelectric conversion element, and there is a problem that the adhesive force is weak.

  Further, in order to examine the problem of the peeling off of the phosphor layer end, a vapor deposition mask 71 having a structure as shown in FIG. 8 is used, and a substrate 63 made of CFRP and the vapor deposition mask 71 are arranged on the same plane, not shown. The phosphor layer 77 was vapor-deposited in a state where it was fixed at a portion where there were few restrictions on the active area. In this case, the vapor deposition mask 71 and the adhering phosphor 75 adhering thereto do not shadow the phosphor vapor flying to the substrate 63, and the phosphor layer 77 having a uniform film thickness on almost the entire surface of the substrate 63. Can be formed. (However, strictly, a slight taper is recognized at the end of the phosphor layer 77.)

  However, also in this phosphor layer 77, since the board | substrate which laminated | stacked the carbon fiber bundle was cut | disconnected to the desired size as the board | substrate 63, a scrunch arises in an edge part, and the edge part of the phosphor layer 77 is based on the scoop. In other words, projections 79 made of a large number of phosphors are generated.

  In addition, in this case, since the phosphor layer 77 has a taper that is too steep, there is a disadvantage in that a portion in which the end portion of the phosphor layer is missing is generated during handling of the scintillator panel manufacturing process.

JP 2009-128023 A International Publication No. WO2008-117821

  Furthermore, as a problem when vapor-depositing the phosphor layer on the substrate of the radiation detector or the support substrate of the scintillator panel, the larger the phosphor layer thickness, the easier it is to peel off. This becomes prominent when the film thickness exceeds 300 μm, and particularly when the film thickness is 500 μm or more, if the phosphor layer 77 having the structure shown in FIG. .

  The present invention has been made in view of the above-described points, and an object thereof is to provide a radiation detector and a scintillator panel in which an end portion of a phosphor layer is less likely to be lost.

  In order to achieve the above-described object, the radiation detector of the present invention includes a phosphor layer provided on the active area of a substrate having an active area in which a plurality of photoelectric conversion elements are arranged, and a vertical section of the phosphor layer. In the radiation detector having a tapered portion in which first inclined surfaces are formed at both ends, a step portion is provided at an intermediate position in the thickness direction of the phosphor layer in the tapered portion.

  The scintillator panel of the present invention is a taper in which a phosphor layer is provided on one surface of a support substrate that transmits radiation, and first inclined surfaces are formed at both ends of a vertical cross section of the phosphor layer. In the scintillator panel having a portion, a step portion is provided at an intermediate position in the thickness direction of the phosphor layer in the tapered portion.

  According to the present invention, it is possible to provide a radiation detector and a scintillator panel in which the end portion of the phosphor layer is unlikely to be lost.

It is sectional drawing which shows 1st Embodiment of the radiation detector which concerns on this invention. It is sectional drawing which shows a part of manufacturing method of the radiation detector of FIG. 1, (a) is the state before vapor deposition of a fluorescent substance layer, (b) is sectional drawing which shows the state in process of vapor deposition. It is sectional drawing which shows 2nd Embodiment of the radiation detector which concerns on this invention. It is sectional drawing which shows 1st Embodiment of the scintillator panel which concerns on this invention. It is sectional drawing which shows a part of manufacturing method of the scintillator panel of FIG. 4, (a) is the state before vapor deposition of a fluorescent substance layer, (b) is sectional drawing which shows the state in process of vapor deposition. It is sectional drawing which shows 2nd Embodiment of the scintillator panel which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the radiation detector which concerns on this invention. It is the schematic explaining the relationship between the structure of the vapor deposition mask used when vapor-depositing a fluorescent substance layer, and the taper of the edge part of a fluorescent substance layer.

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

(First embodiment)
FIG. 1 is a sectional view showing a first embodiment of a radiation detector according to the present invention.

  In this radiation detector 10, a phosphor layer 4 is directly formed on a substrate 3 having an active area 2 in which a plurality of photoelectric conversion elements 1 are arranged, and a reflective layer 5 and a moisture-proof layer 6 are sequentially formed on the phosphor layer 4. Are stacked. Further, the moisture-proof layer 6 and the substrate 3 are sealed by an adhesive layer (not shown) at the end of the substrate 3.

In addition, the tapered portions 7 are formed at both ends of the phosphor layer 4. However, since the phosphor layer 4 is formed so as to cover the entire area of the active area 2 with a substantially uniform thickness, It is preferable that the taper angle θ ₁ , which is an inclination angle of the one inclined surface 7 a from the surface direction of the phosphor layer 4, is not less than 40 degrees and not more than 90 degrees.

  Further, in the radiation detector 10, a step portion 8 having an intermediate surface 8 a parallel to the surface direction of the phosphor layer 4 is provided at an intermediate position in the thickness direction of the tapered portion 7 of the phosphor layer 4. .

  Here, for example, the thickness of the phosphor layer 4 can be 500 μm, the entire width of the tapered portion 7 can be 500 μm, and the width of the intermediate surface 8 a can be 100 μm.

In FIG. 1, the intermediate surface 8a is formed in parallel to the surface direction of the phosphor layer 4, but may be inclined. However, if you are inclined, the inclination angle of the plane direction of the phosphor layer 4 in the intermediate surface 8a, it is necessary to form a smaller angle than the taper angle theta ₁ of the tapered portion 7.

  As the substrate 3 having the active area 2 in which a plurality of the photoelectric conversion elements 1 are arranged, a photodiode photodetecting element is arranged on a matrix on a liquid crystal glass, and a signal of each element is read for each column by a TFT switching element, Examples include CMOS and CCD. In particular, a CMOS can be preferably used because a ratio of an active area portion where photoelectric conversion elements are arranged to a substrate size is large.

  Moreover, as the fluorescent substance layer 4, the thing produced by the vacuum evaporation method like CsI, CsI / Tl, CsI / Na, CsBr / Eu, and a large sensitivity characteristic is useful.

The reflective layer 5 has a function of returning the emitted light directed toward the moisture-proof layer 6 back to the phosphor layer 4, and thus has a function of improving the sensitivity of the phosphor layer 4. As the reflective layer 5, it is possible to use a layer formed by applying a diffuse reflective layer composed of a light scattering material such as TiO ₂ and a binder resin.

  Furthermore, as the moisture-proof layer 6, for example, an AL alloy foil (A1N30-O material) formed by press-molding into a structure having a flange portion at the peripheral portion can be used.

  X-rays that have entered the radiation detector 10 having such a structure through an object from an X-ray source are converted into visible light by the phosphor layer 4. If it demonstrates using a X-ray photon as a representative, a photon will be converted into visible light by the light emission point in the fluorescent substance layer 4. FIG. Light from the emission point diverges in all directions regardless of the incident photon vector. On the other hand, when CsI is used as the phosphor layer 4, since the phosphor layer 4 has a pillar structure, the difference in refractive index between the gap between the pillars and CsI (CsI refractive index = 1.8) A certain proportion of the emitted photons pass through the pillar and reach the photoelectric conversion element 1. Light that diverges beyond the adjacent pillar should also have a low probability of divergence across the optical interface between many pillars. When it reaches a certain interface, it is still confined within that pillar and is trapped in the photoelectric conversion element 1. To reach.

  Due to the above-described action, the phosphor layer 4 having a pillar structure does not so much emit light, and can transmit the emitted light to the photoelectric conversion element 1, thereby obtaining an FPD having relatively high resolution characteristics. it can.

To manufacture the radiation detector 10 according to the present embodiment, first, an end portion of the vapor deposition mask 61 shown in FIG. 2A is formed on the substrate 3 having the active area 2 in which a plurality of photoelectric conversion elements 1 are arranged. after the formation of the 61a by performing vapor deposition of phosphors as a predetermined angle taper angle theta ₁ of the tapered portion 7 of the phosphor layer 4 to more than 40 degrees, as shown in FIG. 2 (b), the end portion 63a given The phosphor layer 4 provided with the stepped portion 8 is completed while the deposition mask 63 having an angle is added to deposit the phosphor to form the intermediate surface 8a.

  Next, the reflective layer 5 and the moisture-proof layer 6 are sequentially laminated on the phosphor layer 4, and an adhesive layer (not shown) is provided at the end of the substrate 3 as necessary to seal the moisture-proof layer 6 and the substrate 3. .

  According to the radiation detector 10 according to the present embodiment, by providing the step portion 8 having the intermediate surface 8a at the intermediate position in the thickness direction of the phosphor layer 4, the fluorescence on the side attached to the substrate 3 is provided. Since the end part film thickness of the body layer 4 can be effectively reduced, it is possible to reduce the loss of the phosphor layer 4 from the end part.

Further, since the taper angle theta ₁ of the phosphor layer 4 in the tapered portion 7 provided on a substrate 3 having a photoelectric conversion element 1 is more than 40 degrees, approximately the thickness of the phosphor layer 4 in the active area 2 A uniform phosphor layer can be formed. Thus, the sensitivity is good even at the outermost peripheral portion of the image, and a uniform image can be obtained as a whole.

(Second Embodiment)
FIG. 3 is a sectional view showing a second embodiment of the radiation detector according to the present invention. In addition, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and description is abbreviate | omitted.

In the radiation detector 20 of the present embodiment, tip portions 9 having a second inclined surface 9a are further formed at both ends of the phosphor layer 4, and the surface of the phosphor layer 4 of the second inclined surface 9a. the inclination angle theta ₂ from direction are formed to be smaller angle than the taper angle theta ₁ is an inclined angle from the phosphor layer 4 in the surface direction of the first inclined surface 7a.

Similarly to the first embodiment, the intermediate surface 8 a of the intermediate portion 8 provided at the intermediate position in the thickness direction of the phosphor layer 4 is formed only in parallel to the surface direction of the phosphor layer 4. It may be inclined. However, if you are inclined, the inclination angle of the plane direction of the phosphor layer 4 in the intermediate surface 8a, it is necessary to form a smaller angle than the average taper angle theta ₃ in the overall thickness of the phosphor layer 4 .

According to the radiation detector 20 according to the present embodiment, the same effect as that of the first embodiment is obtained, and the inclination angle θ ₂ of the tip portion 9 is set to an angle smaller than the taper angle θ ₁ of the taper portion 7. By forming, the adhesion of the phosphor layer 4 at the end of the substrate 3 can be further strengthened.

(Third embodiment)
FIG. 4 is a cross-sectional view showing a first embodiment of a scintillator panel according to the present invention.

  In this scintillator panel 30, a phosphor layer 34 is provided on one surface of a support substrate 33 in which a resin reflection sheet 32 is pasted on both sides of a carbon fiber reinforced plastic (CFRP) 31, and further, the phosphor layer 34 is entirely covered. A moisture-proof layer 35 is formed.

Here, the taper angle θ ₄ , which is an inclination angle of the first inclined surface 36 a from the surface direction of the phosphor layer 34 in the tapered portion 36 provided at both ends of the phosphor layer 34, is set to 40 degrees or more and 90 degrees or less. It is preferable to do so.

  Further, in this scintillator panel 30, an intermediate portion 37 having an intermediate surface 37 a that is flat in the horizontal direction is provided at an intermediate position in the thickness direction of the tapered portion 36 of the phosphor layer 34.

In FIG. 4, the intermediate surface 37a is formed in parallel to the surface direction of the phosphor layer 34, but may be inclined. However, if you are inclined, the inclination angle of the plane direction of the phosphor layer 34 of the intermediate surface 37a, it is necessary to form a smaller angle than the taper angle theta ₄ of the tapered portion 36.

In order to manufacture the scintillator panel 30 according to the present embodiment, first, the support substrate 33 is formed by pasting the resin reflection sheets 32 on both sides of the carbon fiber reinforced plastic (CFRP) 31, and then supporting the support substrate 33. on the substrate 33, the taper angle theta ₄ of the tapered portion 36 of the phosphor layer 34 an end portion 61a by performing a deposition of the phosphor as a predetermined angle of the deposition mask 61 shown in more than 40 degrees in FIGS. 5 (a) After the formation, as shown in FIG. 5 (b), a fluorescent mask is provided with a step portion 37 while forming an intermediate surface 37a by adding a vapor deposition mask 63 having an end portion 63a at a predetermined angle to form a phosphor. The body layer 34 is completed. Further, a moisture-proof layer 35 is formed so as to cover the entire surface of the phosphor layer 34.

  According to the scintillator panel 30 according to the present embodiment, by providing the intermediate portion 37 having the intermediate surface 37a at the intermediate position in the thickness direction of the phosphor layer 34, the fluorescence on the side attached to the support substrate 33 is provided. Since the thickness of the end portion of the body layer 34 can be effectively reduced, it is possible to reduce the loss of the phosphor layer 34 from the end portion.

Further, by making the taper angle θ ₄ of the taper portion 36 of the phosphor layer 34 provided on the support substrate 33 to be 40 degrees or more, as will be apparent from the fifth embodiment described later, the active area 2 A phosphor layer 34 having a substantially uniform film thickness can be formed thereon. Accordingly, it is possible to manufacture a radiation detector that has good sensitivity even at the outermost peripheral portion of the image and can obtain a uniform image as a whole.

(Fourth embodiment)
FIG. 6 is a cross-sectional view showing a second embodiment of the scintillator panel according to the present invention. In addition, the same code | symbol is attached | subjected to the component same as 3rd Embodiment, and description is abbreviate | omitted.

In the scintillator panel 40 of the present embodiment, tip portions 38 having second inclined surfaces 38a are further formed at both ends of the phosphor layer 34, and the surface direction of the phosphor layer 34 of the second inclined surfaces 38a. the inclination angle theta ₅ from is formed such that a smaller angle than the taper angle theta ₄ of the tapered portion 36.

Similarly to the third embodiment, the intermediate surface 37a of the intermediate portion 37 provided at the intermediate position in the thickness direction of the phosphor layer 34 is simply formed parallel to the surface direction of the phosphor layer 34. It may be inclined. However, if you are inclined, the inclination angle of the plane direction of the phosphor layer 34 of the intermediate surface 37a, it is necessary to form a smaller angle than the average taper angle theta ₆ in the entire thickness of the phosphor layer 34.

According to the scintillator panel 40 according to the present embodiment, the same effect as that of the third embodiment is obtained, and the inclination angle θ ₅ of the tip portion 38 is formed to be smaller than the taper angle θ ₄ of the taper portion 36. By doing so, the adhesion of the phosphor layer 34 at the end of the support substrate 33 can be further strengthened.

(Fifth embodiment)
FIG. 7 is a sectional view showing a third embodiment of the radiation detector according to the present invention.

  The radiation detector 50 is formed by bonding the scintillator panel 30 of the third embodiment to the active area 2 side of the substrate 3 having the structure shown in FIG.

  In this radiation detector 50, an area where the film thickness of the phosphor layer 34 is uniform is in close contact so as to include the active area 2 on the substrate 3.

  Further, since the size of the support substrate 33 of the scintillator panel 30 can be reduced, the scintillator panel 30 does not interfere with the protrusion 43 such as a bonding portion at the end of the substrate 3.

DESCRIPTION OF SYMBOLS 1 ... Photoelectric conversion element 2 ... Active area 3 ... Substrate 4 ... Phosphor layer 5 ... Reflective layer 6 ... Moisture-proof layer 7 ... Tapered part 7a ... 1st Inclined surface 8 ... Step 8a ... Intermediate surface 9 ... Tip 9a ... Second inclined surface 10 ... Radiation detector 20 ... Radiation detector 30 ... Scintillator panel 31 ... Carbon fiber reinforced plastic 32 ... Resin reflection sheet 33 ... Support substrate 34 ... Phosphor layer 35 ... Dampproof film 36 ... Tapered portion 36a ... First inclined surface 37 ..Intermediate portion 37a ... intermediate surface 38 ... tip 38a ... second inclined surface 40 ... scintillator panel 43 ... projection 50 ... radiation detector 61 ... deposition mask 61a ... end 63 ... substrate 63a ... end 65 ... phosphor layer 65a ... Supermarkets portion 67 ... coated phosphor 71 ... substrate 75 ... coated phosphor 77 ... phosphor layer 79 ... projections

Claims (9)

A phosphor layer is provided on the active area of the substrate having an active area in which a plurality of photoelectric conversion elements are arranged, and has a tapered portion in which first inclined surfaces are formed at both ends of a vertical section of the phosphor layer. In the radiation detector,
A radiation detector, wherein a step portion is provided at an intermediate position in the thickness direction of the phosphor layer in the tapered portion.   The radiation detector according to claim 1, wherein the step portion includes an intermediate surface formed in parallel with a surface direction of the phosphor layer.   The step portion includes an intermediate surface inclined with respect to the surface direction of the phosphor layer, and an inclination angle of the intermediate surface from the surface direction is an inclination of the first inclined surface from the surface direction. The radiation detector according to claim 1, wherein the radiation detector is formed to have an angle smaller than a taper angle that is an angle.   At both ends of the vertical cross section of the phosphor layer, there are further provided tip portions formed with second inclined surfaces, and the inclination angle of the second inclined surface from the surface direction of the phosphor layer is: 4. The radiation detector according to claim 1, wherein the radiation detector is formed to have an angle smaller than a taper angle that is an inclination angle of the first inclined surface from the surface direction. 5. . In a scintillator panel having a tapered portion in which a phosphor layer is provided on one surface of a support substrate that transmits radiation, and first inclined surfaces are formed at both ends of a vertical cross section of the phosphor layer.
A scintillator panel, wherein a step portion is provided at an intermediate position in the thickness direction of the phosphor layer in the tapered portion.   The scintillator panel according to claim 5, wherein the step portion includes an intermediate surface formed in parallel with a surface direction of the phosphor layer.   The step portion includes an intermediate surface inclined with respect to the surface direction of the phosphor layer, and an inclination angle of the intermediate surface from the surface direction is an inclination of the first inclined surface from the surface direction. 6. The scintillator panel according to claim 5, wherein the scintillator panel is formed to have an angle smaller than a taper angle which is a corner.   At both ends of the vertical cross section of the phosphor layer, there are further provided tip portions formed with second inclined surfaces, and the inclination angle of the second inclined surface from the surface direction of the phosphor layer is: The scintillator panel according to any one of claims 5 to 7, wherein the scintillator panel is formed so as to have an angle smaller than a taper angle that is an inclination angle of the first inclined surface from the surface direction.   9. A radiation detector comprising: a scintillator panel according to claim 5 bonded to the active area of a substrate having an active area in which a plurality of photoelectric conversion elements are arranged.

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