Radiation detector

Abstract

To provide a radiation detector equipped with elements capable of achieving high MTF.SOLUTION: The radiation detector, according to an embodiment, is equipped with: an array substrate having a plurality of photoelectric conversion units; a scintillator disposed above the plurality of photoelectric conversion units, which converts incident radiation into fluorescence; and an absorption unit disposed on the opposite side of the scintillator from the array substrate, which transmits the radiation and absorbs the incident fluorescence.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a radiation detector. [Background technology]

[0002] An example of a radiation detector is an X-ray detector, which includes a scintillator that converts X-rays into fluorescence, multiple photoelectric conversion units that convert the fluorescence into electric charges, and a circuit unit that processes the electric charges into signals to form an X-ray image.

[0003] Here, the image quality of X-ray images is evaluated using indices called sensitivity and MTF (Modulation Transfer Function). Sensitivity is an index that indicates the amount of signal per dose, and MTF is an index that indicates resolution and contrast.

[0004] In this case, increasing the thickness of the scintillator increases the X-ray detection efficiency (conversion efficiency), thereby increasing sensitivity. On the other hand, increasing the thickness of the scintillator increases the path length of the fluorescence. As the path length of the fluorescence increases, the fluorescence spreads more, resulting in a decrease in MTF. Furthermore, providing a reflective layer on the X-ray incident surface of the scintillator to reflect the fluorescence traveling away from the photoelectric conversion unit toward the photoelectric conversion unit increases the amount of fluorescence reaching the photoelectric conversion unit, thereby increasing sensitivity. On the other hand, providing a reflective layer increases the path length of the fluorescence reflected by the reflective layer, thereby increasing the spread of the fluorescence and decreasing MTF. Furthermore, reducing the size of the photoelectric conversion unit increases resolution and therefore MTF, but decreases the amount of fluorescence reaching the photoelectric conversion unit due to the corresponding decrease in size. Conversely, increasing the size of the photoelectric conversion unit decreases MTF and increases sensitivity. Thus, there is a trade-off between sensitivity and MTF.

[0005] In this case, as mentioned above, the MTF can be increased by reducing the thickness of the scintillator or the size of the photoelectric conversion section, but there is a limit to the amount of change that can be achieved.

[0006] Furthermore, if the MTF can be increased by factors other than the thickness of the scintillator and the size of the photoelectric conversion unit, the sensitivity can be increased by the thickness of the scintillator and the size of the photoelectric conversion unit. In other words, it becomes possible to expand the adjustment range of the sensitivity and the adjustment range of the MTF. Therefore, there has been a demand for the development of a radiation detector equipped with elements that can increase the MTF. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-96344 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a radiation detector having an element that can increase the MTF. [Means for solving the problem]

[0009] The radiation detector according to the embodiment includes an array substrate having a plurality of photoelectric conversion units, a scintillator provided on the plurality of photoelectric conversion units and converting incident radiation into fluorescence, and a light-absorbing unit provided on the side of the scintillator opposite the array substrate, which transmits the radiation and absorbs the incident fluorescence. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic perspective view illustrating an X-ray detector according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view illustrating an X-ray detector. [Figure 3] FIG. 1 is a block diagram of an X-ray detector. [Figure 4] 10A and 10B are schematic cross-sectional views illustrating the propagation of fluorescence in an X-ray detector according to a comparative example. [Figure 5] 10A and 10B are schematic cross-sectional views illustrating the action and effect of the light absorbing portion. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate. Furthermore, the radiation detector according to the embodiment of the present invention can be applied to various types of radiation, such as gamma rays, in addition to X-rays. Here, as an example, a case of X-rays, which are a representative type of radiation, will be described. Therefore, by replacing "X-rays" in the following embodiments with "other radiation," the radiation detector can also be applied to other types of radiation. The radiation detector can also be used in general medical applications, for example. However, the applications of the radiation detector are not limited to general medical applications. For example, the radiation detector can also be used in non-destructive testing.

[0012] FIG. 1 is a schematic perspective view illustrating an X-ray detector 1 according to the present embodiment. In order to avoid complication, the protective layer 2f, the moisture-proof part 5, and the adhesive part 6 are omitted from FIG. FIG. 2 is a schematic cross-sectional view illustrating the X-ray detector 1. As shown in FIG. To avoid complication, the circuit section 4 is omitted from Fig. 2. Fig. 3 is a block diagram of the X-ray detector 1.

[0013] As shown in FIGS. 1 and 2, the X-ray detector 1 includes, for example, an array substrate 2, a scintillator 3, a circuit section 4, a moisture-proof section 5, an adhesive section 6, and a light-absorbing section . The X-ray detector 1 may also be provided with a housing (not shown). The housing may contain an array substrate 2, a scintillator 3, a circuit section 4, a moisture-proof section 5, an adhesive section 6, and a light-absorbing section 7. For example, a plate-shaped support plate may be provided inside the housing, and the array substrate 2, the scintillator 3, the moisture-proof section 5, the adhesive section 6, and the light-absorbing section 7 may be provided on the surface of the support plate on the side where X-rays 100 are incident, and the circuit section 4 may be provided on the surface of the support plate opposite to the side where X-rays 100 are incident.

[0014] The array substrate 2 may be provided with a substrate 2a, a photoelectric conversion section 2b, a control line (or gate line) 2c1, a data line (or signal line) 2c2, a wiring pad 2d1, a wiring pad 2d2, and a protective layer 2f. The numbers of photoelectric conversion units 2b, control lines 2c1, and data lines 2c2 are not limited to those shown in the example.

[0015] The substrate 2a has a plate shape and is made of glass such as alkali-free glass, etc. The planar shape of the substrate 2a is, for example, a rectangle.

[0016] A plurality of photoelectric conversion units 2b are provided on one surface of the substrate 2a. The photoelectric conversion units 2b are, for example, rectangular and are provided in an area defined by a control line 2c1 and a data line 2c2. The plurality of photoelectric conversion units 2b can be arranged in a matrix. Note that one photoelectric conversion unit 2b corresponds to, for example, one pixel of an X-ray image.

[0017] Each of the photoelectric conversion units 2b includes, for example, a photoelectric conversion element 2b1 and a thin film transistor (TFT) 2b2, which is a switching element. A storage capacitor (not shown) may also be provided to store the signal charge converted by the photoelectric conversion element 2b1. The storage capacitor may have, for example, a rectangular plate shape and be provided below each thin film transistor 2b2. However, depending on the capacitance of the photoelectric conversion element 2b1, the photoelectric conversion element 2b1 may also function as the storage capacitor.

[0018] The photoelectric conversion element 2b1 is, for example, a photodiode. The thin-film transistor 2b2 switches between storing and discharging charges in the storage capacitor. The thin-film transistor 2b2 has, for example, a gate electrode 2b2a, a drain electrode 2b2b, and a source electrode 2b2c. The gate electrode 2b2a of the thin-film transistor 2b2 is electrically connected to, for example, a corresponding control line 2c1. The drain electrode 2b2b of the thin-film transistor 2b2 is electrically connected to, for example, a corresponding data line 2c2. The source electrode 2b2c of the thin-film transistor 2b2 is electrically connected to, for example, a corresponding photoelectric conversion element 2b1 and a storage capacitor. The anode side of the photoelectric conversion element 2b1 and the storage capacitor can be electrically connected to ground. The anode side of the photoelectric conversion element 2b1 and the storage capacitor can also be electrically connected to a bias line (not shown).

[0019] A plurality of control lines 2c1 can be provided parallel to each other at a predetermined interval. The control lines 2c1 extend, for example, in the row direction. Each control line 2c1 is electrically connected to one of a plurality of wiring pads 2d1 provided near the periphery of the substrate 2a. One of a plurality of wirings provided on the flexible printed circuit board 2e1 is electrically connected to one wiring pad 2d1. The other ends of the plurality of wirings provided on the flexible printed circuit board 2e1 are electrically connected to a readout circuit 4a provided in the circuit unit 4.

[0020] A plurality of data lines 2c2 can be provided parallel to each other at a predetermined interval. The data lines 2c2 extend, for example, in a column direction perpendicular to the row direction. Each data line 2c2 is electrically connected to one of a plurality of wiring pads 2d2 provided near the periphery of the substrate 2a. One of a plurality of wires provided on the flexible printed circuit board 2e2 is electrically connected to one of the wiring pads 2d2. The other ends of the plurality of wires provided on the flexible printed circuit board 2e2 are electrically connected to a signal detection circuit 4b provided in the circuit unit 4. The control line 2c1 and the data line 2c2 are formed using a low resistance metal such as aluminum or chromium.

[0021] The protective layer 2f covers, for example, the photoelectric conversion unit 2b, the control line 2c1, and the data line 2c2. The protective layer 2f is made of an insulating material such as an oxide or a nitride.

[0022] The scintillator 3 is provided on the plurality of photoelectric conversion units 2b and converts incident X-rays 100 into fluorescence, i.e., visible light. The scintillator 3 can be provided on the substrate 2a so as to cover the region where the plurality of photoelectric conversion units 2b are provided (effective pixel region A).

[0023] The scintillator 3 is formed using, for example, cesium iodide (CsI):thallium (Tl), sodium iodide (NaI):thallium (Tl), or cesium bromide (CsBr):europium (Eu). The scintillator 3 is formed using, for example, a vacuum deposition method. If the scintillator 3 is formed using the vacuum deposition method, a scintillator 3 including a plurality of columnar crystals is formed.

[0024] When forming the scintillator 3 using the vacuum deposition method, a mask with openings is used. In this case, the portion of the scintillator 3 formed at the position of the mask opening (the portion of the scintillator 3 formed on the effective pixel area A) has a substantially constant thickness. The portion of the scintillator 3 formed outside the position of the mask opening (the portion of the scintillator 3 formed outside the effective pixel area A) has a thickness that gradually decreases toward the outside.

[0025] The scintillator 3 can also be formed using, for example, terbium-activated gadolinium sulfate (Gd2O2S / Tb or GOS) etc. In this case, a matrix of grooves can be provided so that a square pillar-shaped scintillator 3 is provided for each of the multiple photoelectric conversion units 2b.

[0026] 1, the circuit unit 4 is provided, for example, on the side of the array substrate 2 opposite to the side on which the scintillator 3 is provided. For example, the circuit unit 4 is electrically connected to the array substrate 2 via flexible printed circuit boards 2e1 and 2e2.

[0027] As shown in FIG. 3, the circuit section 4 includes, for example, a read circuit 4a and a signal detection circuit 4b. The readout circuit 4a switches the thin film transistor 2b2 between an on state and an off state, for example, and includes a plurality of gate drivers 4aa and a row selection circuit 4ab.

[0028] A control signal S1 is input to the row selection circuit 4ab from, for example, an image processing unit (not shown) provided outside the X-ray detector 1. The row selection circuit 4ab inputs the control signal S1 to the corresponding gate driver 4aa according to the scanning direction of the X-ray image. The gate driver 4aa inputs the control signal S1 to the corresponding control line 2c1. The control signal S1 input to the control line 2c1 turns on the thin film transistor 2b2, allowing the charge (image data signal S2) to be read out from the storage capacitor.

[0029] The signal detection circuit 4b includes, for example, a plurality of integral amplifiers 4ba, a plurality of selection circuits 4bb, and a plurality of AD converters 4bc. The integrating amplifier 4ba sequentially receives the image data signals S2 from the photoelectric conversion unit 2b. The integrating amplifier 4ba integrates the current flowing within a fixed time and outputs a voltage corresponding to the integrated value to the selection circuit 4bb. The integrating amplifier 4ba converts image data information corresponding to the intensity distribution of the fluorescence generated in the scintillator 3 into potential information.

[0030] The selection circuit 4bb selects the integrating amplifier 4ba to perform reading, and sequentially reads out the image data signal S2 converted into potential information. The AD converter 4bc sequentially converts the read image data signals S2 into digital signals. An image processing unit (not shown) provided outside the X-ray detector 1 constructs an X-ray image based on the image data signals S2 converted into digital signals.

[0031] The moisture-proof portion 5 prevents the characteristics of the scintillator 3 from deteriorating due to moisture in the air. The moisture-proof portion 5 covers the scintillator 3 and the light-absorbing portion 7. There may be a gap between the moisture-proof portion 5 and the light-absorbing portion 7, or the moisture-proof portion 5 and the light-absorbing portion 7 may be in contact with each other. For example, if the vicinity of the periphery of the moisture-proof portion 5 is bonded to the array substrate 2 in an environment where the pressure is reduced below atmospheric pressure, the area covered by the moisture-proof portion 5 is reduced below atmospheric pressure. Therefore, atmospheric pressure can bring the moisture-proof portion 5 and the light-absorbing portion 7 into contact with each other. The moisture-proof portion 5 is made of a material with a low moisture permeability coefficient. The moisture-proof portion 5 is made of a metal such as aluminum. The thickness of the moisture-proof portion 5 is determined taking into account X-ray absorption, rigidity, and the like. The thickness of the moisture-proof portion 5 is, for example, approximately 0.1 mm.

[0032] The adhesive portion 6 is provided between the vicinity of the periphery of the moisture-proof portion 5 and the array substrate 2. The adhesive portion 6 can be formed by curing, for example, an ultraviolet curing adhesive or a two-component mixed adhesive.

[0033] As described above, the X-rays 100 incident on the scintillator 3 are converted into fluorescence. The generated fluorescence propagates inside the scintillator 3. FIG. 4 is a schematic cross-sectional view illustrating the propagation of fluorescence in an X-ray detector 200 according to a comparative example. The X-ray detector 200 according to the comparative example includes an array substrate 2, a scintillator 3, a circuit section 4, a moisture-proof section 5, and an adhesive section 6. To avoid complication, only the array substrate 2, the scintillator 3, and the moisture-proof section 5 are depicted in FIG.

[0034] As shown in FIG. 4, X-rays 100 that have passed through moisture-proof section 5 and entered scintillator 3 are converted into fluorescent light 101 by scintillator 3 . A part of the generated fluorescence 101 heads toward the array substrate 2. The fluorescence 101 headed toward the array substrate 2 is repeatedly scattered and reflected as it propagates inside the scintillator 3. Therefore, the range S where the fluorescence 101 headed toward the array substrate 2 is incident on the array substrate 2 has a certain area.

[0035] Furthermore, a portion of the generated fluorescence 101 travels toward the moisture-proof section 5. The fluorescence 101 traveling toward the moisture-proof section 5 is repeatedly scattered and reflected as it propagates through the scintillator 3. Therefore, the area over which the fluorescence 101 traveling toward the moisture-proof section 5 is incident on the interface between the moisture-proof section 5 and the scintillator 3 has a certain area. The fluorescence 101 that has entered the interface between the moisture-proof section 5 and the scintillator 3 is reflected at the interface between the moisture-proof section 5 and the scintillator 3 to become fluorescence 101a (reflected light) traveling toward the array substrate 2. The fluorescence 101a is repeatedly scattered and reflected as it propagates through the scintillator 3. In this case, as can be seen from FIG. 4 , the path length of the fluorescence 101a reflected at the interface between the moisture-proof section 5 and the scintillator 3 becomes longer. Therefore, the area of ​​the area Sa over which the fluorescence 101a is incident on the array substrate 2 is larger than the area of ​​the area S over which the fluorescence 101 is incident on the array substrate 2.

[0036] In some cases, a reflective layer is provided between the scintillator 3 and the moisture-proof section 5. In such cases, the area of ​​the range Sa where the fluorescent light 101a is incident on the array substrate 2 may become even larger.

[0037] 4, when the fluorescent light 101 and the fluorescent light 101a are incident on multiple photoelectric conversion units 2b, the amount of incident light increases, and therefore the sensitivity increases. However, the MTF decreases because the number of photoelectric conversion units 2b onto which the fluorescent light 101 and the fluorescent light 101a are incident increases.

[0038] Depending on the application of the X-ray detector 1, it may be desirable to increase either the sensitivity or the MTF. For example, it may be desirable to increase the MTF rather than the sensitivity. For example, an X-ray detector 1 used in mammography may be allowed to have a somewhat low sensitivity, but is required to have a high MTF. For example, an X-ray detector 1 used in non-destructive testing may be required to have a high MTF.

[0039] In this case, if the thickness of the scintillator 3 is reduced, the path length of the fluorescent light 101a is shortened, and the MTF can be increased. Also, if the size of the photoelectric conversion unit 2b is reduced, the MTF can be increased. However, the thickness of the scintillator 3 is small (for example, about 600 μm). Also, as shown in FIG. 2, the size of the multiple photoelectric conversion units 2b formed using a semiconductor process is small. Therefore, there is a limit to how much the MTF can be increased by reducing the thickness of the scintillator 3 or the size of the photoelectric conversion units 2b.

[0040] Therefore, the X-ray detector 1 according to this embodiment is provided with a light-absorbing section 7. As shown in Fig. 2, the light-absorbing section 7 is provided on the side of the scintillator 3 opposite to the array substrate 2 side. The light-absorbing section 7 transmits X-rays 100 and absorbs incident fluorescence 101. By absorbing the incident fluorescence 101, the light-absorbing section 7 suppresses the generation of the above-mentioned fluorescence 101a.

[0041] FIG. 5 is a schematic cross-sectional view illustrating the function and effect of the light absorbing portion 7. As shown in FIG. As shown in FIG. 5, X-rays 100 that have passed through the moisture-proof section 5 and the light-absorbing section 7 and are incident on the scintillator 3 are converted into fluorescent light 101 by the scintillator 3 .

[0042] 4, part of the generated fluorescence 101 propagates through the inside of the scintillator 3 while being repeatedly scattered and reflected. Then, the fluorescence 101 heading toward the array substrate 2 enters the range S.

[0043] Furthermore, a portion of the generated fluorescence 101 travels toward the moisture-proof section 5. The fluorescence 101 traveling toward the moisture-proof section 5 is incident on the light-absorbing section 7. The fluorescence 101 that has entered the light-absorbing section 7 is absorbed by the light-absorbing section 7. Therefore, as shown in FIG. 5, it is possible to suppress the generation of fluorescence 101a (reflected light) traveling toward the array substrate 2. As a result, almost only the fluorescence 101 is incident on the array substrate 2. If it is possible to prevent the fluorescence 101a from entering the array substrate 2, it is possible to suppress an increase in the number of photoelectric conversion sections 2b onto which the fluorescence is incident. This makes it possible to improve the MTF.

[0044] Furthermore, if the light absorption unit 7 is provided, the amount of fluorescent light incident on the photoelectric conversion elements 2b1 of the photoelectric conversion unit 2b can be reduced. If the amount of fluorescent light incident on the photoelectric conversion elements 2b1 is reduced, saturation of the photoelectric conversion elements 2b1 can be suppressed. As a result, the quality of the X-ray image can be improved.

[0045] Furthermore, if the provision of the light absorption unit 7 can prevent the photoelectric conversion element 2b1 from saturating, the X-ray dose can be increased. If the X-ray dose can be increased, the range of objects to be inspected can be expanded. For example, in non-destructive inspection, it becomes easier to inspect objects that include materials through which X-rays do not easily penetrate, or objects through which X-rays have a long penetration distance (for example, thick objects).

[0046] As described above, the sensitivity and MTF can also be adjusted by the thickness of the scintillator 3 and the size of the photoelectric conversion unit 2b. Therefore, if the light-absorbing unit 7 that can increase the MTF is provided, the adjustment range of the sensitivity and the adjustment range of the MTF can be expanded.

[0047] For example, if the light-absorbing section 7 is provided, the thickness of the scintillator 3 is reduced, or the size of the photoelectric conversion section 2b is reduced, the MTF can be further increased. Furthermore, by providing the light-absorbing portion 7, the MTF can be increased, and the sensitivity can be increased by increasing the thickness of the scintillator 3 or the size of the photoelectric conversion portion 2b.

[0048] The light-absorbing section 7 that absorbs the incident fluorescent light 101 contains, for example, a black pigment and a binder resin. The black pigment may be any material that absorbs fluorescent light 101 with a wavelength of 300 nm or more and 800 nm or less. The black pigment may be, for example, carbon such as carbon black, iron oxide, copper-chromium composite oxide, copper-chromium-zinc composite oxide, silicon carbide, or the like. The binder resin may be, for example, butyral resin, or the like.

[0049] In this case, if the black pigment is carbon, the elements contained in the light-absorbing portion 7 will mainly be light elements such as hydrogen, carbon, and oxygen. Therefore, if the black pigment is carbon, the scattering and absorption cross section of X-rays will be small, so that it is possible to suppress a decrease in sensitivity due to the light-absorbing portion 7 and a decrease in MTF due to scattered rays, and ultimately it becomes possible to obtain higher sensitivity and higher MTF. Furthermore, if the black pigment is carbon, it can effectively absorb the fluorescent light 101 having a wavelength of 400 nm or more and 700 nm or less, making it easy to obtain a high MTF.

[0050] In this case, taking into consideration the dispersion in the binder resin, it is preferable to use carbon black as the black pigment.

[0051] Furthermore, the absorptance can be changed by varying the pigment volume concentration (PVC) of the black pigment. In this case, lowering the pigment volume concentration reduces the absorption of the incident fluorescent light 101, thereby suppressing a decrease in sensitivity. Increasing the pigment volume concentration increases the absorption of the incident fluorescent light 101, thereby increasing the MTF. However, if the pigment volume concentration of the black pigment exceeds the critical pigment volume concentration (CPVC), the elasticity and tensile strength of the light-absorbing section 7 decrease significantly. As a result, cracks and peeling may occur when forming the light-absorbing section 7.

[0052] According to the findings of the present inventors, it is preferable to set the pigment volume concentration of the black pigment to 1% or more and 50% or less. Furthermore, if the pigment volume concentration of the black pigment is set to 5% or more and 50% or less, it is possible to suppress a decrease in sensitivity and improve MTF. Furthermore, it is possible to suppress the occurrence of cracks and peeling in the light-absorbing portion 7.

[0053] The light-absorbing portion 7 can be formed by applying a material containing, for example, a black pigment and a binder resin to the end of the scintillator 3 opposite to the array substrate 2 side, and then curing the material.

[0054] The light-absorbing section 7 can also be formed by applying a material containing a black pigment and a binder resin to the surface of the moisture-proof section 5 facing the scintillator 3 and then curing the applied material. Alternatively, a sheet containing a black pigment can be adhered or thermocompressed to the surface of the moisture-proof section 5 facing the scintillator 3.

[0055] Furthermore, the light-absorbing portion 7 may be formed on the end of the scintillator 3 opposite to the array substrate 2 side or on the surface of the moisture-proof portion 5 facing the scintillator 3 using a film-forming method such as sputtering.

[0056] In this case, if the light-absorbing section 7 is formed on the end of the scintillator 3 opposite to the array substrate 2 side, it becomes easier to adhere the light-absorbing section 7 to the scintillator 3 compared to when the light-absorbing section 7 is formed on the surface of the moisture-proof section 5 facing the scintillator 3. If the light-absorbing section 7 can be adhered to the scintillator 3, the absorptivity of the incident fluorescence 101 increases, and the MTF increases.

[0057] On the other hand, if the light absorbing portion 7 is formed on the surface of the moisture-proof portion 5 facing the scintillator 3, a slight amount of fluorescence 101a (reflected light) can be generated, thereby improving the MTF and the sensitivity.

[0058] The difference in the absorptivity of the incident fluorescent light 101 can be considered, for example, as follows: The refractive index of the binder resin contained in the light-absorbing part 7 is approximately 1.4 to 1.6. On the other hand, the refractive index of the air contained in the area covered by the moisture-proof part 5 is approximately 1.0.

[0059] Therefore, by forming light-absorbing section 7 at the end of scintillator 3, and by closely adhering light-absorbing section 7 containing a binder resin with a higher refractive index than air to scintillator 3, it is possible to reduce the amount of fluorescence 101 that is totally reflected at the interface between scintillator 3 and light-absorbing section 7. If the amount of fluorescence 101 that is totally reflected is reduced, more fluorescence 101 will be incident on light-absorbing section 7, and therefore the absorption rate of the incident fluorescence 101 can be increased.

[0060] As mentioned above, there are cases where the pressure in the area covered by the moisture-proof part 5 is reduced below atmospheric pressure. In such cases, the atmospheric pressure causes the light-absorbing parts 7 formed on the surface of the moisture-proof part 5 to adhere closely to the scintillator 3, so that the absorption rate of the incident fluorescence 101 can be increased, similar to when the light-absorbing parts 7 are formed on the ends of the scintillator 3. As described above, the light absorbing section 7 is provided between the scintillator 3 and the moisture-proof section 5, and can be brought into close contact with at least one of the scintillator 3 and the moisture-proof section 5.

[0061] When viewed from the X-ray incident side, the light absorption unit 7 can be configured to overlap at least the area where the multiple photoelectric conversion units 2b are provided (effective pixel area A). This can reduce the amount of fluorescence 101a incident on the multiple photoelectric conversion units 2b, thereby improving the MTF.

[0062] In this case, if the light-absorbing section 7 overlaps the scintillator 3 when viewed from the X-ray incident side, the fluorescence 101a incident on the multiple photoelectric conversion sections 2b can be further reduced, thereby further improving the MTF. For example, as shown in Figures 1 and 2, the light-absorbing section 7 may be formed over the entire end of the scintillator 3 on the side opposite to the array substrate 2, or the light-absorbing section 7 may be formed in the region of the moisture-proof section 5 facing the scintillator 3.

[0063] Furthermore, if there is an unevenness in the contact between the light-absorbing portion 7 and the scintillator 3, there may be an unevenness in the absorptivity for the fluorescent light 101. If there is an unevenness in the absorptivity for the fluorescent light 101, there may be an unevenness in the sensitivity and MTF, which may result in a decrease in the quality of the X-ray image.

[0064] Therefore, it is preferable that the state of contact between the light-absorbing section 7 and the scintillator 3 is uniform at least in the portion facing the region (effective pixel region A) where a plurality of photoelectric conversion sections 2b are provided. In this way, it is possible to prevent unevenness in sensitivity and MTF from occurring, which would result in a decrease in the quality of the X-ray image. In this case, it is more preferable that the state of contact between the light-absorbing section 7 and the scintillator 3 is uniform over the entire region. If the state of contact between the light-absorbing section 7 and the scintillator 3 is uniform over the entire region, it is possible to more effectively prevent unevenness in sensitivity and MTF from occurring, which would result in a decrease in the quality of the X-ray image.

[0065] The thickness of the light-absorbing section 7 is not particularly limited as long as it does not cause discontinuities or unevenness in the light-absorbing section 7. As described above, when the scintillator 3 is formed using a vacuum deposition method, a scintillator 3 including a plurality of columnar crystals is formed. Therefore, as shown in FIG. 5 , fine irregularities are formed on the end of the scintillator 3 opposite the array substrate 2. In this case, if the thickness of the light-absorbing section 7 is set to 10 μm or more and 100 μm or less, it is possible to prevent discontinuities and unevenness from occurring in the light-absorbing section 7.

[0066] Although the embodiments have been described above, the present invention is not limited to these descriptions. Any design modifications made by a person skilled in the art to the above-described embodiments are also encompassed within the scope of the present invention as long as they include the features of the present invention. Furthermore, the elements of each of the above-described embodiments can be combined to the greatest extent possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention.

[0067] The following are additional notes regarding the above-described embodiment.

[0068] (Appendix 1) an array substrate having a plurality of photoelectric conversion units; a scintillator that is provided on the plurality of photoelectric conversion units and converts incident radiation into fluorescence; a light-absorbing section provided on the side of the scintillator opposite to the array substrate, the light-absorbing section transmitting the radiation and absorbing the incident fluorescence; A radiation detector comprising:

[0069] (Appendix 2) 2. The radiation detector according to claim 1, wherein, when viewed from the radiation incident side, the light absorption section overlaps at least a region in which the plurality of photoelectric conversion sections are provided.

[0070] (Appendix 3) Further provided is a moisture-proof part covering the scintillator, 3. The radiation detector according to claim 1, wherein the light-absorbing portion is provided between the scintillator and the moisture-proof portion and is in close contact with at least one of the scintillator and the moisture-proof portion.

[0071] (Appendix 4) 4. The radiation detector according to claim 3, wherein the area covered by the moisture-proof part is decompressed below atmospheric pressure.

[0072] (Appendix 5) 5. The radiation detector according to claim 1, wherein the light-absorbing portion contains a black pigment and a binder resin, and absorbs the fluorescence having a wavelength of 300 nm or more and 800 nm or less.

[0073] (Appendix 6) 6. The radiation detector according to claim 5, wherein the black pigment contains carbon and has a pigment volume concentration of 1% or more and 50% or less. [Explanation of symbols]

[0074] 1 X-ray detector, 2 array substrate, 2a substrate, 2b photoelectric conversion unit, 2b1 photoelectric conversion element, 3 scintillator, 5 moisture-proof unit, 7 light-absorbing unit

Claims

1. an array substrate having a plurality of photoelectric conversion units; a scintillator that is provided on the plurality of photoelectric conversion units and converts incident radiation into fluorescence; a light-absorbing section provided on the side of the scintillator opposite to the array substrate, the light-absorbing section transmitting the radiation and absorbing the incident fluorescence; A radiation detector comprising:

2. The radiation detector according to claim 1 , wherein, when viewed from the radiation incident side, the light absorption section overlaps at least a region in which the plurality of photoelectric conversion sections are provided.

3. Further provided is a moisture-proof part covering the scintillator, 3. The radiation detector according to claim 1, wherein the light-absorbing portion is provided between the scintillator and the moisture-proof portion and is in close contact with at least one of the scintillator and the moisture-proof portion.

4. 4. The radiation detector according to claim 3, wherein the area covered by the moisture-proof part is at a pressure lower than atmospheric pressure.

5. 3. The radiation detector according to claim 1, wherein the light absorbing portion contains a black pigment and a binder resin, and absorbs the fluorescence having a wavelength of 300 nm or more and 800 nm or less.

6. 6. The radiation detector according to claim 5, wherein the black pigment contains carbon, and the pigment volume concentration of the black pigment is 1% or more and 50% or less.

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