Method for manufacturing a scintillator screen, scintillator screen and corresponding image detector

Abstract

To provide a method of manufacturing a scintillator screen.SOLUTION: The present invention relates to a method of manufacturing a scintillator screen. The manufacturing method comprises steps: (1) of providing a flexible substrate having at least one surface with a high visible light reflectance or a high visible light absorbance; (2) fixing the other side surface opposite the side surface of the flexible substrate with a high visible light reflectance or high visible light absorbance onto a thermally conductive rigid substrate using a uniformly filled thermally conductive adhesive; and (3) forming a scintillator layer on the side surface of the flexible substrate with a high visible light reflectance or high visible light absorbance.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] This application relates to a method for manufacturing a scintillator screen, and simultaneously to a scintillator screen obtained by using the manufacturing method, and further to an image detector employing the scintillator screen, and belongs to the field of X-ray radiation imaging.

Background Art

[0002] In the industrial and medical fields, X-ray detectors are widely used, and the scintillator screen, which is an essential part of the X-ray detector, is becoming increasingly important. Currently, commonly used scintillator screens are classified into columnar crystal scintillator screens and ceramic scintillator screens. Columnar crystal scintillator screens are represented by scintillator materials such as cesium iodide and sodium iodide, and have advantages such as high brightness and high resolution. However, compared with ceramic scintillator screens (gadolinium sulfate, bismuth germanate), columnar crystal scintillator screens have two major drawbacks. On the one hand, columnar crystal scintillators are materials that are prone to generating moisture. When exposed to air, they absorb moisture and deliquesce, thus reducing the performance of the scintillator screen, especially causing a decrease in the resolution of images. On the other hand, columnar crystal scintillators have a low density and a high porosity of the crystal columns. Residual X-rays are likely to penetrate the scintillator and further affect the electronic circuits in the X-ray image sensor.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The main technical problem to be solved by the present invention is to provide a method for manufacturing a scintillator screen.

[0004] Another technical problem to be solved by the present invention is to provide a scintillator screen obtained by using the above manufacturing method.

[0005] Another technical problem to be solved by the present invention is to provide an image detector using the above-mentioned scintillator screen.

[0006] To achieve the above object, the present invention adopts the following technical solutions.

[0007] According to a first aspect of an embodiment of the present invention, a method for manufacturing a scintillator screen is provided, and the manufacturing method includes: a step of fabricating a crystal columnar scintillator layer on a predetermined surface of a substrate; a step of fabricating a moisture-proof layer around the substrate on which the crystal columnar scintillator layer is formed; a step of fabricating an X-ray absorption layer on the remaining surfaces of the moisture-proof layer other than the surface used for receiving X-rays; a step of fabricating a protective layer on the outer surface of the X-ray absorption layer and on the surface of the moisture-proof layer used for receiving X-rays.

[0008] According to a second aspect of an embodiment of the present invention, a method for manufacturing a scintillator screen is provided, and the manufacturing method includes: a step of fabricating a crystal columnar scintillator layer on a predetermined surface of a substrate; a step of fabricating a moisture-proof layer around the substrate on which the crystal columnar scintillator layer is formed; a step of fabricating a first intermediate layer on the remaining surfaces of the moisture-proof layer other than the surface used for receiving X-rays; a step of fabricating an X-ray absorption layer on the outer surface of the first intermediate layer; a step of fabricating a second intermediate layer on the outer surface of the X-ray absorption layer; a step of fabricating a protective layer on the outer surface of the second intermediate layer and on the surface of the moisture-proof layer used for receiving X-rays.

[0009] Preferably, to fabricate a crystal columnar scintillator layer on a predetermined surface of the substrate, it includes: a sub-step of selecting the raw materials of the substrate and the crystal columnar scintillator layer to be formed; Using a vacuum evaporation method, a sub-step of forming the crystal columnar scintillator layer on the substrate with the raw material of the crystal columnar scintillator layer to be formed is included.

[0010] Preferably, the substrate is selected from substrates having a high visible light reflectivity and an X-ray transmittance.

[0011] Preferably, the raw material of the crystal columnar scintillator layer to be formed is selected from X-ray conversion materials that convert X-rays into visible light.

[0012] Preferably, the moisture-proof layer and the protective layer are each a transparent organic film obtained by a chemical vapor deposition method.

[0013] Preferably, the X-ray absorption layer is an oxide film obtained from a material with a high atomic number using a vacuum magnetron sputtering method.

[0014] Preferably, the first intermediate layer and the second intermediate layer are each an inorganic antireflection film obtained by a vacuum magnetron sputtering method.

[0015] According to a third aspect of an embodiment of the present invention, a method for manufacturing a scintillator screen based on a flexible substrate is provided, and the manufacturing method includes: providing a substrate having at least one surface with a high visible light reflectivity or a high visible light absorption rate; fixing the flexible substrate to a thermally conductive rigid substrate with a thermally conductive adhesive uniformly filled on the other side corresponding to the side surface of the flexible substrate having a high visible light reflectivity or a high visible light absorption rate; manufacturing a scintillator layer on the side surface of the flexible substrate having a high visible light reflectivity or a high visible light absorption rate.

[0016] Preferably, the method further includes peeling and removing the rigid thermally conductive substrate and the thermally conductive adhesive.

[0017] Preferably, a step of manufacturing a waterproof protective layer is further included outside the above-described structure so as to at least completely cover the scintillator layer, thereby obtaining a complete scintillator screen based on a flexible substrate.

[0018] Preferably, the thermal conductivity coefficient of the rigid heat-conductive substrate is greater than 10 W / mK, the thermal conductivity coefficient of the thermally conductive adhesive is greater than 1 W / mK, and the coefficient of thermal expansion of the thermally conductive adhesive should be interposed between the coefficient of thermal expansion of the flexible substrate and the coefficient of thermal expansion of the rigid heat-conductive substrate.

[0019] Preferably, the rigid heat-conductive substrate is an aluminum alloy, a copper alloy, or stainless steel.

[0020] Preferably, the thermally conductive adhesive is an adhesive or a double-sided tape, and the filling method of the adhesive is any one of a casting method, a Czochralski method, screen printing, and spraying.

[0021] Preferably, the visible light reflectance of at least one surface of the flexible substrate is 80% - 100% or 0 - 20%.

[0022] Preferably, a transparent flexible substrate is selectively used for the flexible substrate, and a light reflection layer or a light absorption layer is manufactured on at least one surface of the flexible substrate.

[0023] Preferably, the peeling method is any one of mechanical peeling, light irradiation peeling, and laser peeling.

[0024] According to a fourth aspect of an embodiment of the present invention, a scintillator screen manufactured by a method for manufacturing a scintillator screen is provided.

[0025] According to a fifth aspect of an embodiment of the present invention, an X-ray image detector is provided that uses the above-described scintillator screen and has an X-ray image sensor installed at the bottom of the scintillator screen.

[0026] The method for manufacturing a scintillator screen provided by the present invention improves the X-ray absorption rate, the transmittance of the converted visible light, and the moisture resistance of the formed scintillator screen by successively fabricating a crystal columnar scintillator layer, a moisture-proof layer, an X-ray absorption layer, and a protective layer. Further, by increasing the X-ray absorption layer that absorbs X-rays not completely absorbed by the crystal columnar scintillator layer, X-ray shielding for the electronic circuit of the X-ray image sensor is realized, and the radiation interference of X-rays to the X-ray image sensor is reduced.

Brief Description of the Drawings

[0027]

Figure 1

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Embodiments for Carrying Out the Invention

[0028] Hereinafter, with reference to the drawings and specific embodiments, the technical content of the present invention will be described in more detail.

[0029] In an embodiment of the present invention, the scintillator screen refers to a crystal columnar scintillator screen. After converting the incident X-rays into visible light, the crystal columnar scintillator screen transmits it to an X-ray image sensor, facilitating the conversion of the received visible light by the X-ray image sensor and the electronic circuit in the X-ray image sensor into an analog signal, and converting it into a digital signal via an A / D converter (analog / digital converter), and transmitting it to a computer to obtain an initial digital image of the X-ray.

[0030] As shown in FIG. 1, the method for manufacturing the scintillator screen includes step S1 of fabricating a crystal columnar scintillator layer on a predetermined surface of a substrate.

[0031] The step includes sub-step S11 of selecting a substrate and raw materials for the crystal columnar scintillator layer to be formed.

[0032] After the X-rays are irradiated on the crystal columnar scintillator screen, in order to ensure that they are better absorbed by the crystal columnar scintillator layer and converted into visible light, a substrate with high visible light reflectivity and X-ray transmittance can be selected. The substrate can only transmit X-rays and cannot transmit visible light. For example, the substrate can be selected from a high-reflectivity PET (polyethylene terephthalate) substrate, an AI (aluminum) substrate, a C (graphite) substrate, a Be (beryllium) substrate, etc. with a preset thickness.

[0033] In order for the crystalline columnar scintillator layer to absorb X-rays and convert them into visible light, the raw material of the to-be-formed crystalline columnar scintillator layer can select an X-ray conversion material that can convert X-rays into visible light. For example, the raw material of the to-be-formed crystalline columnar scintillator layer can be materials such as CsI (cesium iodide) doped with Tl (thallium) or Na (sodium), NaI (sodium iodide) doped with Tl (thallium), etc.

[0034] Step S12: Using the vacuum evaporation method, form a crystalline columnar scintillator layer on the substrate with the raw material of the to-be-formed crystalline columnar scintillator layer.

[0035] Place the substrate selected in Step S11 and the raw material of the to-be-formed crystalline columnar scintillator layer in a vacuum evaporation apparatus. Under vacuum conditions, heat and evaporate the raw material of the to-be-formed crystalline columnar scintillator layer, and the atoms or molecules obtained by evaporation are adsorbed on a predetermined surface of the substrate to form a thin film, and the thin film is the crystalline columnar scintillator layer. Among them, the vacuum evaporation method is a conventional and commonly used technique, and will not be specifically mentioned here.

[0036] Hereinafter, taking the selection of a PET substrate with high reflectivity (for example, with a thickness of 188 μm) as the substrate and the selection of bead-shaped thallium iodide particles and powdery cesium iodide material as the raw material of the to-be-formed crystalline columnar scintillator layer as an example, the process of forming a crystalline columnar scintillator layer on the substrate in this step will be described.

[0037] As shown in FIG. 3, put the high-reflectivity PET substrate 11, bead-shaped thallium iodide particles and powdery cesium iodide material into a vacuum evaporation apparatus. Under vacuum conditions, using the co-evaporation method, heat and evaporate the bead-shaped thallium iodide particles and powdery cesium iodide material, and attach the atoms or molecules obtained by evaporation to the lower surface of the high-reflectivity PET substrate 11 to form a crystalline columnar cesium iodide layer 12. The crystalline columnar cesium iodide layer 12 converts X-rays into visible light.

[0038] Step S2: A moisture-proof layer is fabricated around the substrate on which the crystal columnar scintillator layer is formed.

[0039] Since the crystal columnar scintillator layer (for example, the crystal columnar cesium iodide layer 12 described above) has high hygroscopicity, if the crystal columnar scintillator layer is directly exposed to the air, the crystal columnar scintillator layer interacts with water vapor in the air, the crystal columns of the scintillator screen deliquesce, adhesion occurs between the crystal columns, and the resolution effect of the image is affected. In addition, since there is a certain gap between the crystal columns of the crystal columnar scintillator layer, the lower surface of the crystal columnar scintillator layer is uneven, and there is also residual X-ray that passes through the crystal columnar scintillator layer and affects the electronic circuit of the X-ray image sensor. Therefore, a moisture-proof layer can be deposited around the substrate provided with the crystal columnar scintillator layer formed in step S1 by using chemical vapor deposition.

[0040] Among them, the moisture-proof layer may be a transparent organic film obtained from materials such as poly(para-chlorotoluene), poly(para-xylylene), poly(tetrachloropara-xylylene), and poly(dimethylpara-xylylene) by using chemical vapor deposition.

[0041] Taking as an example the formation of a poly(p - dichlorotoluene) film around a high - reflectivity PET substrate 11 on which a crystalline columnar cesium iodide layer 12 is formed, as shown in FIG. 4, the high - reflectivity PET substrate 11 on which the crystalline columnar cesium iodide layer 12 is formed is placed in a chemical vapor deposition apparatus. Through the chemical vapor deposition apparatus, a first poly(p - dichlorotoluene) film 13 with a preset thickness is formed around the high - reflectivity PET substrate 11 and the crystalline columnar cesium iodide layer 12. Preferably, it is most optimal to form a first poly(p - dichlorotoluene) film 13 with a thickness of 10 μm around the high - reflectivity PET substrate 11 and the crystalline columnar cesium iodide layer 12. The first poly(p - dichlorotoluene) film 13 can effectively reduce the influence of water vapor in the air on the crystalline columnar cesium iodide layer 12. At the same time, by using the first poly(p - dichlorotoluene) film 13 to fill the gaps existing between the crystal columns of the crystalline columnar cesium iodide layer 12 and form a dense barrier layer, the lower surface of the crystalline columnar cesium iodide layer 12 is flattened.

[0042] Step S3: An X - ray absorption layer is fabricated on the remaining surfaces of the moisture - proof layer fabricated in Step S2, excluding the surface used for receiving X - rays.

[0043] The function of the X - ray absorption layer fabricated on the remaining surfaces of the moisture - proof layer fabricated in Step S2, excluding the surface used for receiving X - rays, is to reduce the X - ray radiation interference on the X - ray image sensor by absorbing the X - rays that are not completely absorbed by the crystalline columnar scintillator layer. Using the vacuum magnetron sputtering method, an X - ray absorption layer with a preset thickness is fabricated on the remaining surfaces of the moisture - proof layer, excluding the surface used for receiving X - rays. Preferably, based on the X - ray radiation dose and the crystalline columnar scintillator layer, the thickness of the X - ray absorption layer is appropriately adjusted, and the optimal adjustment range of the thickness of the X - ray absorption layer is 300 nm to 500 nm. Also, the vacuum magnetron sputtering method is a conventional and commonly used technique and will not be mentioned here.

[0044] Among them, the X-ray absorption layer may be an oxide film obtained from high atomic number Z materials such as PbO (lead oxide), Bi2O3 (bismuth oxide), PbxOy (lead oxide), WO3 (tungsten trioxide), etc. using the vacuum magnetron sputtering method.

[0045] Taking the case where the X-ray absorption layer is a lead oxide film as an example, as shown in FIG. 5, a high reflectivity PET substrate 11 provided with a columnar cesium iodide layer 12 and a first poly(p-dichlorotoluene) film 13 fabricated in step S2 is placed in a vacuum magnetron sputtering apparatus. Under vacuum conditions, a 500 nm thick lead oxide film 15 is formed on the remaining surfaces other than the upper surface of the first poly(p-dichlorotoluene) film 13 using the vacuum magnetron sputtering method.

[0046] Step S4: A protective layer is fabricated on the outer surface of the X-ray absorption layer fabricated in step S3 and on the surface of the moisture-proof layer fabricated in step S2 that is used for receiving X-rays.

[0047] In order to prevent the X-ray absorption layer fabricated in step S3 and the moisture-proof layer fabricated in step S2 from being caught or peeled off, and to further reduce the influence of water vapor in the air on the moisture-proof layer, a protective layer is deposited on the outer surface of the X-ray absorption layer fabricated in step S3 and on the surface of the moisture-proof layer fabricated in step S2 that is used for receiving X-rays using the chemical vapor deposition method.

[0048] Among them, the protective layer may be a transparent organic film obtained from materials such as poly(p-dichlorotoluene), poly(p-xylylene), polytetrachloroparaxylylene, poly(dimethylparaxylylene), etc. using the chemical vapor deposition method.

[0049] Taking the case where the protective layer is a poly - paradichlorotoluene film as an example, as shown in FIG. 6, a high - reflectivity PET substrate 11 provided with a columnar - crystal cesium iodide layer 12, a first poly - paradichlorotoluene film 13, and a lead oxide film 15 prepared in step S3 is placed in a chemical vapor deposition apparatus. By the chemical vapor deposition apparatus, a second poly - paradichlorotoluene film 17 with a preset thickness is formed on the upper surface of the first poly - paradichlorotoluene film 13 and the outer surface of the lead oxide film 15. Preferably, it is most optimal to form a second poly - paradichlorotoluene film 17 with a thickness of 10 μm on the upper surface of the first poly - paradichlorotoluene film 13 and the outer surface of the lead oxide film 15. The second poly - paradichlorotoluene film 17 can prevent the first poly - paradichlorotoluene film 13 and the lead oxide film 15 from being caught or peeled off, and can effectively reduce the influence of water vapor in the air on the columnar - crystal cesium iodide layer 12.

[0050] Using the above steps S1 - S4, a columnar - crystal scintillator screen can be manufactured. In order to improve the bonding effect between the moisture - proof layer and the X - ray absorption layer in the columnar - crystal scintillator screen, and to improve the moisture resistance of the columnar - crystal scintillator layer and the transmittance of the visible light converted by it, as shown in FIG. 2, the manufacturing method of this scintillator screen further provides the following preferred technical solutions including the following steps.

[0051] Step S10: Fabricate a columnar - crystal scintillator layer on a predetermined surface of the substrate. This step is the same as the description of step S1 and the sub - steps of step S1 above.

[0052] Step 20: Fabricate a moisture - proof layer around the substrate on which the columnar - crystal scintillator layer is formed. This step is the same as the description of step S2 above.

[0053] Step S30: Fabricate a first intermediate layer on the remaining surfaces of the moisture - proof layer fabricated in step S20 other than the surface used for receiving X - rays.

[0054] The function of the first intermediate layer formed on the remaining surfaces of the moisture-proof layer produced in step S20, other than the surface used for receiving X-rays, is to improve the bonding effect between the moisture-proof layer and the X-ray absorption layer to be produced in a later step, and also to improve the moisture resistance of the crystal columnar scintillator layer and the transmittance of the visible light converted by it. Using the vacuum magnetron sputtering method, a first intermediate layer with a preset thickness is formed on the remaining surfaces of the moisture-proof layer, other than the surface used for receiving X-rays. Preferably, according to the requirements of the light output, the thickness of the first intermediate layer is appropriately adjusted, and the optimal adjustment range of the thickness of the first intermediate layer is 50 nm to 200 nm.

[0055] Among them, the first intermediate layer may be an inorganic antireflection film obtained from materials such as SiO2 (silica), TiO2 (titanium dioxide), SiN (silicon nitride), MgF2 (magnesium fluoride), and SiNO (silicon oxynitride) using the vacuum magnetron sputtering method.

[0056] Taking the case where the first intermediate layer is a silica film as an example, as shown in FIG. 7, a high-reflectivity PET substrate 11 including a crystal columnar cesium iodide layer 12 and a first polyparadichlorotoluene film 13 produced in step S20 is placed in a vacuum magnetron sputtering apparatus. Under vacuum conditions, using the vacuum magnetron sputtering method, a first silica film 14 with a thickness of 100 nm is formed on the remaining surfaces of the first polyparadichlorotoluene film 13 other than the upper surface.

[0057] Step S40: An X-ray absorption layer is formed on the outer surface of the first intermediate layer produced in step S30.

[0058] The function of the X-ray absorption layer formed on the outer surface of the first intermediate layer fabricated in step S30 is to reduce the X-ray radiation interference to the X-ray image sensor by absorbing the X-rays that are not completely absorbed by the crystal columnar scintillator layer. Using the vacuum magnetron sputtering method, an X-ray absorption layer with a preset thickness is fabricated on the outer surface of the first intermediate layer. Preferably, according to the X-ray radiation dose and the crystal columnar scintillator layer, the thickness of the X-ray absorption layer is appropriately adjusted, and the optimal adjustment range of the thickness of the X-ray absorption layer is 300 nm to 500 nm.

[0059] Among them, the X-ray absorption layer may be an oxide film obtained from materials with atomic number Z such as PbO (lead oxide), Bi2O3 (bismuth oxide), PbxOy (lead oxide), WO3 (tungsten trioxide), etc. using the vacuum magnetron sputtering method.

[0060] Taking the case where the X-ray absorption layer is a lead oxide film as an example, as shown in FIG. 7, a high-reflectivity PET substrate 11 including a crystal columnar cesium iodide layer 12, a first poly(p-dichlorotoluene) film 13, and a first silica film 14 fabricated in step S30 is placed in a vacuum magnetron sputtering apparatus. Under vacuum conditions, using the vacuum magnetron sputtering method, a lead oxide film 15 with a thickness of 500 nm is formed on the outer surface of the first silica film 14.

[0061] Step S50: A second intermediate layer is fabricated on the outer surface of the X-ray absorption layer fabricated in step S40.

[0062] The function of the second intermediate layer formed on the outer surface of the X-ray absorption layer fabricated in step S40 is to improve the moisture resistance of the crystal columnar scintillator layer and the transmittance of the visible light it converts. Using the vacuum magnetron sputtering method, a second intermediate layer with a preset thickness is fabricated on the outer surface of the X-ray absorption layer. Preferably, according to the requirements of the light output, the thickness of the second intermediate layer is appropriately adjusted, and the optimal adjustment range of the thickness of the second intermediate layer is 50 nm to 200 nm.

[0063] Among them, the second intermediate layer may be an inorganic antireflection film obtained from materials such as SiO2 (silica), TiO2 (titanium dioxide), SiN (silicon nitride), MgF2 (magnesium fluoride), and SiNO (silicon oxynitride) using the vacuum magnetron sputtering method.

[0064] Taking the case where the second intermediate layer is a silica film as an example, as shown in FIG. 7, a high-reflectivity PET substrate 11 including a crystalline columnar cesium iodide layer 12, a first polyparadichlorotoluene film 13, a first silica film 14, and a lead oxide film 15 produced in step S40 is placed in a vacuum magnetron sputtering apparatus, and a second silica film 16 with a thickness of 100 nm is formed on the outer surface of the lead oxide film 15 using the vacuum magnetron sputtering method under vacuum conditions.

[0065] Step S60: A protective layer is formed on the outer surface of the second intermediate layer produced in step S50 and on the surface of the moisture-proof layer produced in step S20 that is used for receiving X-rays.

[0066] In order to prevent the second intermediate layer produced in step S50 and the moisture-proof layer produced in step S20 from being caught or peeled off, and to further reduce the influence of water vapor in the air on the moisture-proof layer, a protective layer is deposited on the outer surface of the second intermediate layer produced in step S50 and on the surface of the moisture-proof layer produced in step S20 that is used for receiving X-rays using the chemical vapor deposition method.

[0067] Among them, the protective layer may be a transparent organic film obtained from materials such as polyparadichlorotoluene, polyparaxylylene, polytetrachloroparaxylylene, and polydimethylparaxylylene using the chemical vapor deposition method.

[0068] Taking the case where the protective layer is a poly - paradichlorotoluene film as an example, as shown in FIG. 8, a high - reflectivity PET substrate 11 provided with a crystalline columnar cesium iodide layer 12, a first poly - paradichlorotoluene film 13, a first silica film 14, a lead oxide film 15, and a second silica film 16 produced in step S50 is placed in a chemical vapor deposition apparatus. Through the chemical vapor deposition apparatus, a second poly - paradichlorotoluene film 17 with a preset thickness is formed on the upper surface of the first poly - paradichlorotoluene film 13 and the outer surface of the second silica film 16. Preferably, it is optimal to form a second poly - paradichlorotoluene film 17 with a thickness of 10 μm on the upper surface of the first poly - paradichlorotoluene film 13 and the outer surface of the second silica film 16. The second poly - paradichlorotoluene film 17 can prevent the first poly - paradichlorotoluene film 13 and the second silica film 16 from being caught or peeled off, and can effectively reduce the influence of water vapor in the air on the crystalline columnar cesium iodide layer 12.

[0069] Using the above steps S10 - S60, other crystalline columnar scintillator screens can be produced. As shown in FIG. 9, an X - ray image sensor 20 is installed at the bottom of any one of the above - mentioned two types of crystalline columnar scintillator screens to constitute an X - ray image detector. After converting the incident X - rays into visible light through the crystalline columnar scintillator screen and then transmitting them to the X - ray image sensor, the X - ray image sensor and the electronic circuit of the X - ray image sensor facilitate converting the received visible light into an analog signal, converting it into a digital signal through an A / D converter (analog - to - digital converter), and transmitting it to a computer to obtain an initial digital image of the X - rays.

[0070] The method for manufacturing a scintillator screen provided in the above embodiments improves the X-ray absorption rate, the transmittance of the converted visible light, and the moisture resistance of the formed scintillator screen by successively fabricating a crystalline columnar scintillator layer, a moisture-proof layer, an X-ray absorption layer, and a protective layer. Also, by increasing the X-ray absorption layer that absorbs the X-rays not completely absorbed by the crystalline columnar scintillator layer, X-ray shielding for the electronic circuit of the X-ray image sensor is realized, and the radiation interference of X-rays to the X-ray image sensor is reduced.

[0071] In addition, the cesium iodide screen grown on a flexible substrate is thin, light, bend-resistant, and has excellent waterproof properties. However, when cesium iodide is thermally evaporated onto some large flexible substrates with a low softening temperature, the substrate is likely to deform during the evaporation process. Also, in the coating process, due to the difference in heat dissipation capacity of different parts of the substrate, the temperature difference between different parts of the substrate becomes large, affecting the coating uniformity.

[0072] The embodiments of the present invention further provide a method for manufacturing a scintillator screen that prevents the deformation of a flexible substrate and significantly improves the coating uniformity in a high-temperature coating process for the problem that when a scintillator of columnar crystalline cesium iodide is deposited on a large flexible substrate, it is likely to deform and there are significant non-uniformities in the thin film due to the difference in heat dissipation capacity of different parts of the substrate in the coating process.

[0073] The method for manufacturing a scintillator screen based on the above flexible substrate is as follows: Step (1) of providing a substrate 1 having at least one surface with a high visible light reflectivity or a high visible light absorption rate; Step (2) of fixing the other side of the flexible substrate 1 opposite to the side having a high visible light reflectivity or a high visible light absorption rate to a rigid heat-conducting substrate 3 by a uniformly filled thermally conductive adhesive 2; Step (3) of manufacturing the scintillator layer 4 on the side surface of the flexible substrate 1 having a high visible light reflectivity or a high visible light absorption rate; Step (4) of peeling off and removing the rigid heat conductive substrate 4 and the thermally conductive adhesive 3; Step (5) of manufacturing a waterproof protective layer 5 outside the above-described structure so that a complete scintillator screen based on the flexible substrate can be obtained by at least completely covering the scintillator layer 4.

[0074] Hereinafter, description will be made with reference to the structures shown in FIGS. 10 to 12.

[0075] Among them, the flexible substrate 1 provided in step (1) can be selected from PET (polyethylene terephthalate), PI (polyimide), PE (polyethylene), PMMA (polymethyl methacrylate, organic glass), etc. or the above-described materials that have been surface-treated.

[0076] The visible light reflectivity of at least one surface of the flexible substrate 1 is 80% - 100% or 0 - 20%. When the visible light reflectivity of at least one surface of the flexible substrate 1 is 80% - 100%, the flexible substrate 1 can be used for manufacturing a scintillator screen having high brightness and low resolution by having at least one surface with a high visible light reflectivity. When the visible light reflectivity of at least one surface of the flexible substrate 1 is 0 - 20%, the flexible substrate 1 can be used for manufacturing a scintillator screen having high resolution by having at least one surface with a high visible light absorption rate. In the structures shown in FIGS. 10 to 12, the surface of the flexible substrate 1 having a high visible light reflectivity or a high visible light absorption rate is the upper surface.

[0077] The flexible substrate 1 can also be selected and used as a transparent flexible substrate. By manufacturing a light reflection layer or a light absorption layer on at least one surface of the flexible substrate 1 (the surface used for vapor deposition of the scintillator layer 4), it can have a high visible light reflectance or a high visible light absorption rate, and the same function can be realized.

[0078] In step (2), the other side of the flexible substrate 1 that faces the side with high visible light reflectance or high visible light absorption rate (i.e., the lower surface of the flexible substrate 1 in FIGS. 10 to 12) is fixed to the rigid heat conduction substrate 3 by the uniformly filled thermal conductive adhesive 2.

[0079] Among them, the rigid heat conduction substrate 3 can be selected from aluminum alloy, copper alloy, stainless steel, etc., the thermal conductivity coefficient is greater than 10 W / mK, the thermal conductive adhesive 2 can be an adhesive or a double-sided tape, and the thermal conductivity coefficient is greater than 1 W / mK. The thermal expansion coefficient of the thermal conductive adhesive 2 should be between the thermal expansion coefficient of the flexible substrate and the thermal expansion coefficient of the rigid heat conduction substrate. The filling method of the adhesive can be selected from the casting method, the Czochralski method, screen printing, spraying, etc. If necessary, by combining high-pressure or low-pressure defoaming agents, reliable adhesion between the flexible substrate 1 and the rigid heat conduction substrate 3 can be guaranteed.

[0080] In step (2), the thermal conductive adhesive 2 should have a high thermal conductivity and an appropriate bonding strength with the flexible substrate 1. If the bonding strength is too low, it is easy to peel off in the subsequent coating process and cannot play the role of heat conduction. If the bonding strength is too high, there is a problem that it is difficult to peel off the rigid heat conduction substrate after the scintillator layer is vapor deposited.

[0081] In step (3), a scintillator layer 4 is manufactured on the side surface of the flexible substrate 1 having a high visible light reflectivity or a high visible light absorption rate. In the structures shown in FIGS. 10 to 12, the scintillator layer 4 is vapor-deposited on the upper surface of the flexible substrate 1. The scintillator material can be selected from cesium iodide CsI(TI) doped with thallium, cesium iodide CsI(Na) doped with sodium, or other doped columnar cesium iodide crystals, and the manufacturing method can be selected from thermal evaporation, laser evaporation, etc.

[0082] Through the above three steps, the structure shown in FIG. 10 can be obtained.

[0083] In step (4), the rigid heat conduction substrate 3 and the thermally conductive adhesive 2 are peeled off and removed. FIG. 11 shows the structure in which the rigid heat conduction substrate 3 and the thermally conductive adhesive 2 are peeled off and removed from the structure shown in FIG. 10. The peeling method can be selected from mechanical peeling, light irradiation peeling, laser peeling, etc., and the specific peeling process can be determined according to the properties of the rigid heat conduction substrate 3 and the thermally conductive adhesive 2. In the peeling process, the integrity of the flexible substrate 1 and the scintillator layer 4 should be guaranteed, and the deformation of the flexible substrate 1 and the peeling of the scintillator layer 4 should be prevented.

[0084] When the rigid heat conduction substrate 3 and the thermally conductive adhesive 2 do not have a clear blocking effect on X-rays, step (4) can also be skipped without removing the auxiliary material, and the final product is a scintillator screen provided with a composite substrate.

[0085] In step (5), a complete scintillator screen is obtained by selecting and using the prior art to manufacture the waterproof protective layer 5. The waterproof protective layer 5 should at least completely cover the scintillator layer 4 and wrap the scintillator layer 4 inside to achieve waterproof and moisture-proof functions. The available waterproof protective layer 5 includes, but is not limited to, a transparent Pi film (polyimide film), a PET film (polyester film), a vapor-deposited parylene film, etc., or a composite film or composite coating layer formed by laminating the above thin films with a dense inorganic waterproof film such as SiO2, TIO2, Al2O3, etc.

[0086] In the embodiment shown in FIG. 12, a waterproof protective layer 5 is installed outside the flexible substrate 1 and the scintillator layer 4, and the waterproof protective layer 5 wraps the entire flexible substrate 1 and the scintillator layer 4 inside. In an embodiment not shown, the waterproof protective layer 5 can cover only the scintillator layer 4 and the substrate surface within a specific area near the edge of the scintillator layer 4, and the same waterproof effect can also be achieved.

[0087] In the above manufacturing method, the other side of the flexible substrate opposite to the side where the crystal columnar scintillator is deposited (the side away from the side used for depositing the crystal columnar scintillator of the flexible substrate) is fixed to the rigid heat-conducting substrate by a uniformly filled thermally conductive adhesive, realizing the fixation and rapid heat conduction of the flexible substrate during the high-temperature deposition process, preventing the deformation of the flexible substrate caused by gravity or uneven heating, and significantly improving the coating uniformity.

[0088] In the above manufacturing method, a rigid heat-conducting substrate with high thermal conductivity is used as an auxiliary substrate, and a thermally conductive adhesive with high thermal conductivity is used as a thermally conductive bonding material to fix the flexible substrate to the auxiliary substrate, realizing the fixation and rapid heat conduction of the flexible substrate during the deposition process, preventing the deformation of the flexible substrate, and improving the coating uniformity.

[0089] When step (4) is included in the above manufacturing method, the structure of the scintillator screen based on the obtained flexible substrate is as shown in FIG. 12. The scintillator screen based on the flexible substrate includes a flexible substrate 1, a scintillator layer 4, and a waterproof protection layer 5. Among them, the scintillator layer 4 is installed on the side surface of the flexible substrate 1 having a high visible light reflectivity or a high visible light absorption rate, and the waterproof protection layer 5 at least completely covers the scintillator layer 4.

[0090] Also, when step (4) is not included in the above manufacturing method and the auxiliary material is not removed, the obtained final product is a scintillator screen provided with a composite substrate, including a flexible substrate 1, a thermally conductive adhesive 2, a rigid thermally conductive substrate 3, a scintillator layer 4, and a waterproof protection layer 5. The scintillator layer 4 is installed on the side surface of the flexible substrate 1 having a high visible light reflectivity or a high visible light absorption rate. The other side surface of the flexible substrate 1 is fixed to the rigid thermally conductive substrate 4 by the uniformly filled thermally conductive adhesive 2, and the waterproof protection layer 5 at least completely covers the scintillator layer 4.

[0091] In the above two structures, the waterproof protection layer 5 can cover only the scintillator layer 4 and the substrate surface in a specific area near the edge of the scintillator layer 4, and the waterproof protection layer 5 can also wrap the entire structure of the scintillator screen inside.

[0092] Specifically, except when it is necessary to use a flexible screen, in most application cases, a scintillator screen having the above two structures can be used. Similar to the embodiment shown in FIG. 9, an X-ray image detector can be configured by installing an X-ray image sensor 20 at the bottom of any one of the scintillator screens having the above two structures.

[0093] To sum up, the manufacturing method of the scintillator screen based on the flexible substrate provided in the embodiment of the present invention is to fix the other side of the flexible substrate facing the side with high visible light reflectivity or high visible light absorption rate to the rigid heat conduction substrate by a uniformly filled thermally conductive adhesive, thereby realizing the fixation and rapid heat conduction of the flexible substrate in the high-temperature evaporation process, preventing the deformation of the flexible substrate due to gravity or uneven heating, and significantly improving the uniformity of the coating.

[0094] As described above, the manufacturing method of the scintillator screen, the scintillator screen, and the image detector provided by the present invention have been described in detail. For those skilled in the art, any obvious changes made to the present invention without departing from the substantial content of the present invention are all included in the protection scope of the patent rights of the present invention.

Claims

1. A method for manufacturing a scintillator screen based on a flexible substrate, comprising: Step (1) of providing a flexible substrate having at least one surface with a high visible light reflectance or a high visible light absorption rate; Step (2) of fixing the other side of the flexible substrate, which faces the side having a high visible light reflectance or a high visible light absorption rate, to a rigid heat conduction substrate with a uniformly filled thermally conductive adhesive; Step (3) of manufacturing a scintillator layer on the side of the flexible substrate having a high visible light reflectance or a high visible light absorption rate; Step (4) of peeling off and removing the rigid heat conduction substrate and the thermally conductive adhesive, characterized in that it is a method for manufacturing a scintillator screen.

2. The method for manufacturing a scintillator screen according to Claim 1, further comprising Step (5) of manufacturing a waterproof protective layer outside the above-described structure so as to at least completely cover the scintillator layer.

3. The thermal conductivity of the rigid heat conduction substrate is greater than 10 W / mK, the thermal conductivity of the thermally conductive adhesive is greater than 1 W / mK, and the thermal expansion coefficient of the thermally conductive adhesive is between the thermal expansion coefficient of the flexible substrate and the thermal expansion coefficient of the rigid heat conduction substrate, characterized in that it is a method for manufacturing a scintillator screen according to Claim 1 or 2.

4. The rigid heat conduction substrate is an aluminum alloy, a copper alloy or stainless steel, characterized in that it is a method for manufacturing a scintillator screen according to Claim 1.

5. The thermally conductive adhesive is an adhesive or a double-sided tape, and the filling method of the adhesive is any one of a casting method, a Czochralski method, screen printing and spraying, characterized in that it is a method for manufacturing a scintillator screen according to Claim 1.

6. The visible light reflectance of at least one surface of the flexible substrate is 80% to 100% or 0 to 20%, characterized in that it is a method for manufacturing a scintillator screen according to Claim 1.

7. The flexible substrate is selected and used as a transparent flexible substrate, and a light reflection layer or a light absorption layer is manufactured on one side of the flexible substrate, characterized in that it is a method for manufacturing a scintillator screen according to Claim 6.

8. The peeling method used in the step (4) is any one of mechanical peeling, photoirradiation peeling, and laser peeling, and the method for manufacturing a scintillator screen according to claim 1 is characterized by this.

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