Radiation imaging apparatus and radiation imaging system

Abstract

To provide a radiation imaging apparatus that can obtain high-quality radiation images at low cost and with a simple structure while ensuring moisture resistance of a scintillator.SOLUTION: A radiation imaging apparatus comprises: a scintillator layer; a supporting base that supports the scintillator layer; a sensor panel that is provided in contact with the scintillator layer and includes a plurality of photoelectric conversion elements provided in a two-dimensional array on a first surface on the side having the scintillator layer; a substrate provided on the side of a second surface opposite to the first surface of the sensor panel; and a sealing portion that bonds a peripheral portion of the substrate and a peripheral portion of the supporting base, and seals the scintillator layer in a space formed between the substrate and the supporting base. A linear expansion coefficient of the supporting base is in a range from 10×10-6K to 30×10-6K, and a main material of the supporting base is the same element as that of the substrate.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a radiation imaging apparatus and a radiation imaging system.

Background Art

[0002] In recent years, a radiation imaging apparatus has been commercialized in which a scintillator layer that converts radiation such as X-rays into light of a wavelength that can be detected by a photoelectric conversion element is laminated on a sensor panel having a plurality of photoelectric conversion elements formed on its surface.

[0003] In such a radiation imaging apparatus, when the scintillator layer is made of a deliquescent material, moisture protection of the scintillator layer may be performed by sealing the periphery with resin when bonding the support base that supports the scintillator layer and the sensor panel. In such a configuration, when there is a large difference in the coefficient of thermal expansion between the support base that supports the scintillator layer and the sensor panel, there is a risk of warping due to the difference in the coefficient of thermal expansion, peeling between the layers, breakage of the sealing resin, etc.

[0004] Conventionally, for the purpose of preventing such problems, a technique has been proposed in which a base having the same coefficient of thermal expansion as the sensor panel is provided and the scintillator is sealed in a space formed by the base, the sensor panel, and the resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the structure shown in Patent Document 1, the base may absorb the radiation transmitted from the subject, and as a result, the image quality of the obtained radiation image may deteriorate. In addition, as the structure becomes more complex, there is a risk that the device cost and weight will increase.

[0007] This invention has been made in view of the problems of the prior art, and aims to provide a radiography apparatus that can obtain high-quality radiographic images while ensuring moisture resistance of the scintillator with an inexpensive and simple structure. [Means for solving the problem]

[0008] The above problem is solved by a sensor panel comprising: a scintillator layer that converts radiation into light; a support base that supports the scintillator layer; a sensor panel provided in contact with the scintillator layer, with a plurality of photoelectric conversion elements arranged in a two-dimensional array on a first surface on the side having the scintillator layer; a substrate provided on the second surface of the sensor panel opposite to the first surface; and a sealing portion that bonds the peripheral portion of the substrate to the peripheral portion of the support base and seals the scintillator layer in the space formed by the substrate and the support base, wherein the coefficient of thermal expansion of the support base is 10 × 10 -6 K to 30x10 -6 This problem is solved by a radiographic imaging apparatus characterized by being in the range of K and being made of the same element as the substrate. [Effects of the Invention]

[0009] According to embodiments of the present invention, it is possible to provide a radiography apparatus that can obtain high-resolution radiographic images while ensuring moisture resistance of the scintillator layer with an inexpensive and simple structure. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the configuration of a radiography apparatus according to an embodiment of the present invention. [Figure 2] This figure shows the configuration of a radiography apparatus according to an embodiment of the present invention. [Figure 3] This figure shows the configuration of a radiography apparatus according to an embodiment of the present invention. [Figure 4] This figure shows the configuration of a radiography apparatus according to an embodiment of the present invention. [Figure 5]It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 6] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 7] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 8] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 9] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 10] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 11] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 12] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 13] It is a diagram showing the configuration of a stress relaxation layer of a radiation imaging apparatus according to an embodiment of the present invention. [Figure 14] It is a schematic cross-sectional view showing the configuration of a radiation imaging apparatus of Comparative Example 1. [Figure 15] It is a schematic cross-sectional view showing the configuration of a radiation imaging apparatus of Comparative Example 2. [Figure 16] It is a diagram showing the configuration of a radiation imaging system using the radiation imaging apparatus of the present invention.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, the same members are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] FIG. 1 is a schematic plan view showing the configuration of a radiation imaging apparatus 1 as one aspect of the present invention. FIG. 2 is a cross-sectional view taken along the line A-A' of the radiation imaging apparatus 1 shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line B-B' of the radiation imaging apparatus 1 shown in FIG. 1.

[0013] The radiographic apparatus 1 is an apparatus having a photoelectric conversion element and a scintillator layer that converts radiation into light having a wavelength detectable by the photoelectric conversion element. Here, the radiation is preferably X-rays, but is not limited thereto, and includes, for example, electromagnetic waves such as α-rays, β-rays, and γ-rays. As shown in FIGS. 1 to 3, the radiographic apparatus 1 has a scintillator layer 104 and a sensor panel 110, and a laminate thereof is used.

[0014] The sensor panel 110 is configured by providing a photoelectric conversion unit 106 on the first surface of the sensor base 107. Further, a sensor protection layer (not shown) may be formed on the sensor panel 110. In FIG. 2, the sensor panel 110 is configured by arranging a photoelectric conversion unit 106 in which a photoelectric conversion element and a TFT switching element (not shown) are arranged in a two-dimensional array on an insulating sensor base 107 made of glass or the like. The ACF 109 is used when electrically connecting the external wiring 103 and the sensor base 107.

[0015] Further, a flexible material, for example, a resin such as polyimide may be used for the sensor base 107 of the sensor panel 110. Further, the sensor panel 110 may be one in which the photoelectric conversion unit 106 is arranged on a sensor base 107 using Si. Further, a plurality of sensor panels 110 may be fixed to one base.

[0016] Further, a sensor protection layer (not shown) may be formed so as to cover the photoelectric conversion unit 106. When forming the sensor protection layer, it may be made of SiN, TiO2, LiF, Al2O3, MgO, or the like. Further, the sensor protection layer may be made of polyphenylene sulfide resin, fluororesin, polyether ether ketone resin, liquid crystal polymer, polyether nitrile resin, polysulfone resin, polyether sulfone resin, polyarylate resin, or the like.

[0017] Furthermore, the sensor protective layer may be composed of polyamide-imide resin, polyether-imide resin, polyimide resin, epoxy resin, silicone resin, acrylic resin, and compounds containing these.

[0018] When radiation is irradiated onto the radiography apparatus 1, the light converted by the scintillator layer 104 passes through the sensor protection layer. Therefore, the sensor protection layer should be made of a material that has high transmittance for the wavelength of the light converted by the scintillator layer 104.

[0019] Next, the scintillator support base 101 will be described. The scintillator support base 101 is made of a material with high transmittance to radiation. For example, the scintillator support base 101 is made of at least one of beryllium (Be), magnesium (Mg), aluminum (Al), titanium (Ti), iron (Fe), and alloys containing these as main components.

[0020] A scintillator layer 104 is provided on the scintillator support base 101. A base protection layer (not shown) may be formed on the scintillator support base 101, in which case the scintillator layer 104 is placed via the base protection layer. A reflective layer may also be provided on the scintillator support base 101 to effectively utilize the light converted by the scintillator layer 104. Such a reflective layer should preferably be made of a material that has a high reflectivity to the light converted by the scintillator layer 104, such as silver (Ag) or aluminum (Al).

[0021] The scintillator layer 104 is composed of a columnar crystalline scintillator, such as cesium iodide (CsI:Tl) with a small amount of thallium (Tl) added. The scintillator layer 104 may also be formed by directly depositing it onto the scintillator support base 101. In that case, the sensor panel 110 and the scintillator are bonded together via the adhesive layer 105. Alternatively, as shown in Figure 4, the scintillator layer 104 may be directly deposited onto the sensor panel 110, in which case the scintillator support base 101 and the scintillator layer 104 are bonded together via the adhesive layer 105.

[0022] A scintillator protective layer (not shown) may be placed so as to cover the surface and sides of the scintillator layer s104. The scintillator protective layer has the function of protecting the scintillator layer 104 from deterioration due to humidity (moisture-proof or moisture-resistant). As the material of the scintillator protective layer, for example, general organic materials such as silicone resin, acrylic resin, and epoxy resin, or hot melt resins such as polyester, polyolefin, and polyamide can be used.

[0023] The scintillator protective layer is preferably made of a resin with low moisture permeability, such as an organic layer of polyparaxylylene formed by CVD deposition or a hot-melt resin such as a polyolefin resin. Alternatively, the scintillator protective film, as a protective film for temporary moisture protection, may be a protective film composed of metal atoms, oxygen atoms, and hydrophobic functional groups.

[0024] The scintillator protective film provides moisture-proof protection to the scintillator layer 104, preventing moisture from entering from the outside, and impact protection to prevent damage due to impact. When the scintillator layer 104 is composed of a scintillator having a columnar crystal structure, the scintillator protective film is preferably 10 nm to 50 μm thick.

[0025] The scintillator layer 104 is sealed in the space formed by the scintillator support base 101, the substrate 108, and the sealing portion 111. The sealing portion 111 adheres and joins the peripheral portion of the scintillator support base 101 and the peripheral portion of the substrate 108. To improve the moisture resistance of the scintillator layer 104, the sealing portion 111 may be made of a resin with low moisture permeability, particularly epoxy resin, similar to the scintillator protective layer.

[0026] Furthermore, the resin used in the sealing portion 111 can be changed depending on the moisture-proof performance of the scintillator protective layer. For example, when using a highly moisture-proof scintillator protective layer, a relatively moisture-permeable resin such as a silicone-based, acrylic-based, or elastic epoxy resin can be used in the sealing portion 111.

[0027] The substrate 108 is provided on the second surface side of the sensor panel 110, which is the side opposite the first surface, and together with the sealing portion 111 and the scintillator support base 101, it forms a moisture-proof structure. It is desirable to use a material for the substrate 108 that exhibits a similar coefficient of thermal expansion as the scintillator support base 101. Therefore, it is desirable to use a material for the substrate 108 that consists of the same elements as the scintillator support base 101.

[0028] Furthermore, it is desirable that the substrate 108 and the scintillator support base 101 be made of metallic material. Also, the value of the linear expansion coefficient, which represents the change in length among the thermal expansion coefficients, should be 10 × 10 -6 K to 30x10 -6 It is preferable to use a material that exhibits a range of K.

[0029] In the radiography apparatus 1 having such a sealing structure, the sensor base 107 and the substrate 108 are not bonded together. This structure reduces the risk of the sealing portion 111 cracking due to the difference in thermal expansion between the substrate 108 and the scintillator support base 101, even when a highly hard sealing resin is used for the sealing portion 111. It also has the effect of reducing warping of the radiography apparatus 1 and peeling of the scintillator support base 101 and the scintillator layer 104.

[0030] Furthermore, since it is important to alleviate the stress acting between the sensor base 107 and the substrate 108 due to the difference in thermal expansion, a stress-relieving layer 113 may be provided between the sensor base 107 and the substrate 108 as shown in Figure 5. The stress-relieving layer 113 may be a single layer or a multi-layered structure. The stress-relieving layer 113 only needs to be placed between the sensor base 107 and the substrate 108, and may be placed over the entire surface as shown in Figure 5, or it may be placed so as to partially contact the sensor base 107 and the substrate 108 as shown in Figures 6-8.

[0031] Figures 9-13 show various patterns of the stress relaxation layer 113 as viewed from above in Figure 2, but this is not limited to these patterns as long as the stress generated between the sensor base 107 and the substrate 108 can be relieved.

[0032] Furthermore, it is not necessary to determine whether the stress relaxation layer 113 is bonded to the sensor base 107 or the substrate 108. When an adhesive layer is provided between the stress relaxation layer 113 and the sensor base 107 to bond the stress relaxation layer to one side, for example, it is effective to install a coating film or sheet with good sliding properties on the substrate 108 in order to mitigate the transmission of stress.

[0033] The material of the stress relaxation layer 113 is preferably a silicone resin, but any known material used for cushioning purposes may be used.

[0034] The specific characteristics of the radiography apparatus 1 of the present invention will be described below with reference to comparative examples and examples.

[0035] <Comparative Example 1> Figure 14 is a schematic cross-sectional view showing the configuration of the radiography apparatus 2 of Comparative Example 1. Unlike radiography apparatus 1, radiography apparatus 2 seals the scintillator layer 204 by joining the end of the sensor panel 210 and the end of the scintillator support base 201 at the sealing portion 211.

[0036] Referring to Figure 14, a conventional method for manufacturing a radiography apparatus 2 will be described. First, a photoelectric conversion unit 206, an ACF 209, and external wiring 203 are formed on a semiconductor thin film made of amorphous silicon formed on a sensor substrate 207 made of glass or the like. Then, a sensor protective layer made of SiNx is formed on the photoelectric conversion unit 206 to manufacture a sensor panel 210.

[0037] Next, the surface of the aluminum scintillator support base 201 is anodized, and a scintillator layer 204 made of alkali halide with a columnar structure crystal (for example, CsI:Tl (thallium-activated cesium iodide)) is formed (deposited) on it. After deposition, a scintillator protective layer is formed on the scintillator layer 204 to fabricate a scintillator panel 212.

[0038] Next, a frame made of epoxy resin is formed on the sensor panel 210 as a sealing portion 211. Specifically, epoxy resin is applied from a dispensing device in a width of 2 mm and a height of 0.5 mm so as to surround the photoelectric conversion elements 213 arranged two-dimensionally on the sensor substrate 207. After bonding the scintillator panel 212 and the sensor panel via the adhesive layer 205, the sealing portion 211 made of epoxy resin is cured.

[0039] A temperature cycling test was performed on the radiography device 2. The temperature cycling test was conducted as follows: The radiography device 2 was set in the evaluation device and left in an environment of 50°C and 60% humidity for 4 hours, and then left in an environment of -30°C and 0% humidity for 4 hours. This cycle was repeated 5 times. Then, the sealing part 211 was visually inspected to see if any damage (such as cracking or peeling) had occurred due to the difference in thermal expansion between the scintillator support base 201 and the sensor panel 210. In the radiography device 2, the sealing part 211 was damaged.

[0040] <Comparative Example 2> Figure 15 is a schematic cross-sectional view showing the configuration of the radiography apparatus 3 of Comparative Example 2. Unlike radiography apparatus 1, radiography apparatus 3 does not have a stress relief section, and the sensor panel 310 and the substrate 308 are attached via an adhesive layer. The substrate 308 is made of glass. In addition, the sealing section 311 connects the end of the substrate to the end of the scintillator support base 301, which is the same as in radiography apparatus 1.

[0041] Referring to Figure 15, a conventional method for manufacturing a radiography apparatus 2 will be described. First, a photoelectric conversion unit 306, an ACF 309, and external wiring 303 are formed on a sensor substrate 307 made of Si or the like. Then, a sensor protective layer made of SiNx is formed on the photoelectric conversion unit 306 to create a sensor panel 310. Furthermore, the substrate 308 and the sensor panel 310 are bonded together via a substrate adhesive layer 314.

[0042] Next, the scintillator panel 312 is fabricated in the same manner as the radiography apparatus 2. Then, a frame made of epoxy resin is formed on the substrate 308 as a sealing portion 311. Specifically, epoxy resin is applied to the substrate 308 from a dispensing device in a width of 2 mm and a height of 0.5 mm so as to surround the sensor panel. After bonding the scintillator panel 312 and the sensor panel via the adhesive layer 305, the sealing portion 111 made of epoxy resin is cured.

[0043] A temperature cycling test was performed on this radiography device 3. The temperature cycling test was the same as in Comparative Example 1. Then, the sealing portion 311 was visually evaluated to see if any damage (such as cracking or peeling) had occurred due to the difference in thermal expansion between the scintillator support base 301 and the sensor panel 310. In radiography device 2, the sealing portion 311 was damaged.

[0044] <Embodiment> First, the scintillator panel 112 and the sensor panel 110 are formed in the same manner as in Comparative Example 2. Then, the scintillator panel 112 and the sensor panel 110 are bonded together with the adhesive layer 105, as shown in Figure 2. An aluminum substrate 108 is placed underneath. At this time, the substrate 108 and the sensor panel 110 are not bonded together.

[0045] Next, a sealing portion 111 is provided to bond the sensor base 107 and the substrate 108. At this time, the sealing portion does not come into contact with the sensor panel. The above-described temperature cycle test was performed on the radiography apparatus 1 manufactured in this manner. In the radiography apparatus 1, no damage to the sealing portion 111 occurred even during the temperature cycle test.

[0046] <Other Embodiments> The radiography apparatus of the above-described embodiment can be applied to a radiography system. The radiography system includes, for example, a radiography apparatus, a signal processing unit including an image processor for processing signals from the radiography apparatus, a display unit including a display for displaying signals from the signal processing unit, and a radiation source for generating radiation.

[0047] For example, as shown in Figure 16, X-rays 611 generated in the X-ray tube 610 pass through the chest 621 of a patient or other subject 620 and enter the radiography apparatus 630. These incident X-rays contain information about the inside of the subject's body. The scintillator emits light in response to the incident X-rays, and this light is detected by a sensor panel to obtain electrical information.

[0048] Subsequently, this information is digitally converted, processed by an image processor 640 (signal processing unit), and can be displayed on a display 650 (display unit) in the control room. This information can also be transmitted to a remote location via a transmission means including a network 660 such as a telephone, LAN, or internet. This allows the information to be displayed on a display 651 in a doctor's room or other location, enabling a doctor in a remote location to make a diagnosis.

[0049] Furthermore, this information can be stored, for example, on an optical disc, or recorded on a recording unit such as a film 671 by the film processor 670.

[0050] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. [Explanation of symbols]

[0051] 101 Scintillator support base 104 Scintillator layer 108 circuit boards 110 Sensor Panel 111 Sealing part

Claims

1. A scintillator that converts radiation into light; A support base that supports the scintillator; a sensor panel in which photoelectric conversion elements are arranged in a two-dimensional array; A substrate supporting the sensor panel; a sealing portion that bonds a peripheral portion of the substrate and a peripheral portion of the support base and seals the scintillator and the sensor panel in a state where the scintillator and the sensor panel face each other in a space between the substrate and the support base, The support base has a linear expansion coefficient in the range of 10×10 K to 30×10 K, The main material of the support base is made of the same material as the main material of the substrate. A radiation imaging device comprising:

2. 2. The radiation imaging apparatus according to claim 1, wherein the substrate and the sensor panel are not in contact with each other.

3. 2. The radiation imaging apparatus according to claim 1, further comprising a stress relaxation layer between the substrate and the sensor panel for relieving stress acting between the substrate and the sensor panel.

4. 4. The radiation imaging apparatus according to claim 1, wherein the sensor panel is flexible.

5. 5. The radiation imaging apparatus according to claim 4, wherein the sensor panel is made of polyimide.

6. 6. The radiation imaging apparatus according to claim 1, wherein the scintillator is fixed to the support base.

7. 7. The radiation imaging apparatus according to claim 1, wherein the scintillator is fixed to the sensor panel.

8. 8. The radiation imaging apparatus according to claim 1, wherein the support base is made of metal.

9. 9. The radiation imaging apparatus according to claim 8, wherein the support base is made of aluminum.

10. 10. The radiation imaging apparatus according to claim 1, wherein the scintillator is made of cesium iodide.

11. 11. The radiation imaging apparatus according to claim 1, wherein the sealing portion is made of a resin.

12. 12. The radiation imaging apparatus according to claim 11, wherein the resin is made of an epoxy resin.

13. A radiographic imaging apparatus according to any one of claims 1 to 12, a signal processing unit for processing a signal from the radiation imaging apparatus; a display unit for displaying a signal from the signal processing unit; A radiation imaging system comprising:

Images