JP2016070752A - X-ray image detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the degree of freedom in design of an X-ray image detection device including a plurality of X-ray image detectors.SOLUTION: The X-ray image detection device 10 includes a plurality of X-ray image detectors 1-1 to 1-5 arranged so that they overlap each other in the incident direction f of X rays. Each of the X-ray image detectors 1 includes: a substrate 5 made of a flexible material; an X ray conversion film 3; a plurality of pixel electrodes 4; a switching element connected to each of the plurality of pixel electrodes 4; a data line that is connected to the switching element and transfers a signal indicating an X-ray amount in each pixel; and a control line for supplying a signal for controlling the switching element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for capturing an image using X-rays.

  Flat X-ray image detectors (Flat Panel Detector: FPD) are mainly classified into indirect conversion type and direct conversion type depending on the X-ray detection principle. The indirect conversion type is a system in which X-rays are converted into light by a scintillator, and then light is converted into an electrical signal by a photodiode. The direct conversion type is a system in which X-rays are directly converted into electric signals by an X-ray conversion film (X-ray photoconductor). In the direct conversion type X-ray conversion film, a hole-electron pair, that is, a charge is excited in accordance with the incident X-ray dose.

  For example, in the fields of medicine and science, a plurality of substances are often measured simultaneously. Therefore, separating the energy of the X-rays transmitted through the sample for each wavelength component is effective for identifying the target substance. However, the FPD is difficult to detect the energy for each detected X-ray wavelength because of its structure. Therefore, for example, in Patent Document 1 below, multicolor X-rays including a plurality of monochromatic X-rays having different wavelengths are passed through a plurality of X-ray detectors, and the most upstream side is detected from the detection intensity of each X-ray detector. It is described that each intensity of a plurality of monochromatic X-rays incident on the X-ray detector or a ratio thereof is calculated.

Japanese Patent No. 4839050

  In the above-described conventional configuration, a plurality of X-ray detectors are stacked so that multicolor X-rays sequentially pass simultaneously. Each X-ray detector has a configuration in which, for example, a CsI film as an X-ray conversion film and a CCD are combined. In this configuration, a certain distance is generated between the CsI film of one X-ray detector and the CsI film of the adjacent X-ray detector. Since there is a distance between the plurality of X-ray conversion films in this manner, the X-ray detection position in the upstream X-ray detector and the same X-ray detection position in the downstream X-ray detector are likely to shift. . Therefore, when the number of X-ray detectors to be stacked is increased, the quality of the X-ray image is likely to deteriorate. As a result, the number of X-ray detectors is limited and the degree of freedom in design is low, making it difficult to effectively utilize a configuration using a plurality of X-ray detectors. Therefore, the present application discloses a technique for increasing the degree of design freedom of an X-ray image detection apparatus including a plurality of X-ray image detectors.

  An X-ray image detection apparatus according to an embodiment of the present invention includes a plurality of X-ray image detectors arranged so as to overlap in the X-ray incident direction. Each of the X-ray image detectors includes a substrate formed of a flexible material, an X-ray conversion film that is fixed to the substrate and generates a charge or visible light corresponding to an incident X-ray dose. And a detection element provided corresponding to each of the plurality of pixels arranged on one surface of the X-ray conversion film and having a detection surface in contact with the X-ray conversion film, and connected to each of the plurality of detection elements A switching element, a data line connected to the switching element and transmitting a signal based on electric charge or visible light collected on a detection surface of the detection element as a signal indicating an X-ray dose in each pixel, and the switching element A control line is connected and supplies a signal for controlling the switching element.

  According to the present disclosure, the degree of freedom in designing an X-ray image detection apparatus including a plurality of X-ray image detectors can be increased.

FIG. 1 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the first embodiment. FIG. 2 is a cross-sectional view illustrating a configuration example of one pixel of the X-ray image detector 1. FIG. 3 is a circuit diagram showing an equivalent circuit of one pixel of the X-ray image detector 1. FIG. 4 is a diagram for explaining an example in which different wavelength regions are detected. FIG. 5 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the second embodiment. FIG. 6 is a diagram for explaining an example of detecting X-rays that have passed through the vicinity of the pixel electrodes 4-1 to 4-3. FIG. 7 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the third embodiment. FIG. 8 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the third embodiment. FIG. 9 is a diagram illustrating a configuration example in the case of supplying different voltages for each X-ray image detector. FIG. 10 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the fourth embodiment. FIG. 11 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the fifth embodiment. 12 is an enlarged view of the X-ray image detectors 1-1 to 1-3 shown in FIG. FIG. 13 is a cross-sectional view illustrating a configuration example of an indirect conversion type X-ray image detection apparatus. FIG. 14 is a cross-sectional view showing a modification of the X-ray image detection apparatus. FIG. 15 is a cross-sectional view showing another modification of the X-ray image detection apparatus.

  An X-ray image detection apparatus according to an embodiment of the present invention includes a plurality of X-ray image detectors arranged so as to overlap in the X-ray incident direction. Each of the X-ray image detectors includes a substrate formed of a flexible material, an X-ray conversion film that is fixed to the substrate and generates a charge or visible light corresponding to an incident X-ray dose. And a detection element provided corresponding to each of the plurality of pixels arranged on one surface of the X-ray conversion film and having a detection surface in contact with the X-ray conversion film, and connected to each of the plurality of detection elements A switching element, a data line connected to the switching element and transmitting a signal based on electric charge or visible light collected on a detection surface of the detection element as a signal indicating an X-ray dose in each pixel, and the switching element A control line is connected and supplies a signal for controlling the switching element.

  In the above configuration, each of the plurality of X-ray image detectors is formed on a substrate formed of a flexible material, that is, an X-ray conversion film fixed to the flexible substrate, and one surface of the X-ray conversion film. A detection element to be formed, a switching element connected to the detection element, a data line, and a control line are provided. Therefore, the thickness of one X-ray image detector can be reduced as compared with an X-ray pixel detector using a conventional substrate. That is, the distance between the detection surfaces of a plurality of adjacent X-ray image detectors can be reduced. In addition, since a substrate formed of a flexible material is used, it is easy to mold the X-ray detection surface of each X-ray image detector into various forms. As a result, restrictions on the thickness of the X-ray conversion film, the distance between the plurality of X-ray conversion films, the number of X-ray image detectors, the shape of the X-ray conversion film, and other components in the plurality of X-ray image detectors are relaxed. Become. That is, the degree of freedom in design increases. The material having flexibility includes a material that is elastically deformed or plastically deformed when a certain force or more is applied.

  In the X-ray image detection apparatus, at least two of the plurality of X-ray image detectors may detect X-rays having different wavelength ranges from incident continuous X-rays. Thereby, X-rays in different wavelength regions in continuous X-rays can be detected by a plurality of X-ray image detectors, respectively. Continuous X-rays are X-rays that indicate a continuous energy spectrum. Note that the X-rays targeted by the X-ray image detection apparatus are not limited to continuous X-rays, but can also be continuous X-rays in a region including characteristic X-rays.

  In the above-described configuration, the detection surface of the detection element in at least one pixel in one X-ray image detector among the plurality of X-ray image detectors detects the detection element in the corresponding pixel of the other X-ray image detector. The surface may be partially overlapped in the X-ray incident direction. That is, the detection surface of the detection element of a certain pixel in one X-ray image detector has a portion that overlaps the detection surface of the detection element of the corresponding pixel in another X-ray image detector and a portion that does not overlap. . Accordingly, the corresponding pixels of the plurality of X-ray image detectors can be arranged so as to be shifted from each other with respect to the X-ray incident direction. Therefore, it is possible to specify the X-ray detection position with higher accuracy than when detecting with one X-ray image detector. Note that the detection surface of the detection element can be a region that directly receives charges or light generated according to X-rays incident on the X-ray conversion unit from the X-ray conversion unit. In the case of the direct conversion type, the detection element can be a pixel electrode in contact with the X-ray conversion unit. In the case of the indirect conversion type, the detection element can be a photoelectric conversion element such as a photodiode in contact with the X-ray conversion unit. .

  The X-ray imaging apparatus includes a shielding member that is provided between two adjacent X-ray image detectors among the plurality of X-ray image detectors and restricts transmission of X-rays having a certain wavelength or wavelength range. Furthermore, it can be provided. Thereby, the wavelength range of the X-rays detected by the X-ray image detector upstream of the shielding member can be made different from the wavelength of the X-rays detected by the X-ray image detector downstream of the shielding member.

  In the above configuration, the substrate may have a curved surface that is recessed in a direction in which X-rays are incident, and the X-ray conversion film may be formed along the curved surface. As a result, the angle of the X-ray incident on the X-ray conversion film can be made closer to the X-ray incident surface uniformly.

  In the above configuration, X-rays penetrating the detection surface of the detection element of at least one pixel in one X-ray image detector among the plurality of X-ray image detectors in the corresponding pixel in the other X-ray image detector. The detection surface of the detection element of the one X-ray image detector and the detection surface of the detection element of the other X-ray image detector can be arranged so as to penetrate the detection surface of the detection element. Thereby, the shift | offset | difference of the X-ray detection position in one X-ray image detector and the same X-ray detection position in another X-ray image detector can be made small. The “corresponding pixel” in the other X-ray image detector is, for example, a pixel of another X-ray image detector corresponding to the same coordinate as the coordinate of the one pixel of the one X-ray image detector. Can do.

  Each of the X-ray image detectors may have a counter electrode provided at a position facing the detection surface of the detection element on the other surface facing the one surface of the X-ray conversion film. In that case, the X-ray image detection device is independent of the counter electrode in one X-ray image detector of the plurality of X-ray image detectors and the counter electrode in another X-ray image detector. And a power supply unit for supplying a voltage. Thereby, an X-ray image can be detected with an appropriate voltage according to the configuration of each X-ray image detector.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. In addition, in order to make the explanation easy to understand, in the drawings referred to below, the configuration is shown in a simplified or schematic manner, or some components are omitted. Further, the dimensional ratio between the constituent members shown in each drawing does not necessarily indicate an actual dimensional ratio.

<Embodiment 1>
(Configuration of X-ray imaging apparatus)
FIG. 1 is a cross-sectional view illustrating a configuration example of the X-ray imaging apparatus according to the first embodiment. An X-ray imaging apparatus 10 shown in FIG. 1 includes a plurality of X-ray image detectors 1-1 to 1-5 arranged so as to overlap in the X-ray incident direction F (hereinafter, X-rays unless otherwise specified). (Collectively referred to as image detector 1). The plurality of X-ray image detectors 1-1 to 1-5 are stacked in the X-ray incident direction F so that the respective X-ray conversion films 3 are parallel to each other. A plurality of X-ray image detectors 1-1 to 1-5 are stacked so that the X-rays transmitted through the front X-ray image detector 1 enter the next X-ray image detector 1. An interval (space) may be provided between the plurality of X-ray image detectors 1-1 to 1-5, or an adhesive or the like may be filled therein. The configuration of the plurality of X-ray image detectors 1-1 to 1-5 may not be exactly the same.

  Each X-ray image detector 1 includes a flexible substrate 5 and an X-ray conversion film 3 bonded to the flexible substrate 5. The X-ray conversion film 3 generates a charge corresponding to the incident X-ray dose. Pixel electrodes 4 corresponding to a plurality of pixels are provided on one surface of the X-ray conversion film 3. The pixel electrode 4 has a detection surface in contact with the X-ray conversion film. The pixel electrode 4 is an example of a detection element. The counter electrode 2 is provided at a position facing the plurality of pixel electrodes 4 on the other surface of the X-ray conversion film 3. The counter electrode 2 is integrally provided in a region facing the plurality of pixel electrodes 4. On one surface of the X-ray conversion film 3, the plurality of pixels are arranged in a lattice shape, for example, and can form a matrix having rows and columns.

  Each pixel electrode 4 is provided with a thin film transistor (hereinafter referred to as TFT; not shown in FIG. 1), which is an example of a switching element. A data line and a control line are connected to the TFT. The data line transmits a signal based on the charge in each pixel electrode as a signal indicating the X-ray dose in each pixel. The control line supplies a signal for controlling the TFT. The data line extends in the first direction (for example, the horizontal (row) direction of the pixel matrix) and is connected to a plurality of pixels arranged in the first direction via the TFT. The control line extends in a second direction (for example, the vertical (column) direction of the pixel matrix) different from the first direction, and is connected to a plurality of pixels arranged in the second direction via the TFT. Note that the data line can also be referred to as a source line, a signal line, or the like, and the control line can also be referred to as a gate line or a scanning line.

  In the example shown in FIG. 1, the counter electrodes 2 of the plurality of X-ray image detectors 1-1 to 1-5 are connected in parallel to each other. Thereby, the same bias electrode can be applied to the counter electrodes 2 of the plurality of X-ray image detectors 1-1 to 1-5. Alternatively, the counter electrode 2 of each X-ray image detector 1 can be configured not to be connected to the counter electrode 2 of another X-ray image detector 1. Thereby, a different bias voltage can be applied to the counter electrode 2 for each X-ray image detector 1. Further, a signal indicating the X-ray dose can be taken out through the data lines of the X-ray image detector 1.

  FIG. 2 is a cross-sectional view illustrating a configuration example of one pixel of the X-ray image detector 1. FIG. 3 is a circuit diagram showing an equivalent circuit of one pixel of the X-ray image detector 1. In the example shown in FIG. 2, the TFT 32, the charge storage capacitor 31 (including the pixel electrode 4), the control line 23, and the data line 24 formed on the flexible substrate 5 are included in one pixel. In this manner, a substrate in which the electrode wiring including the control lines 23 and the data lines 24 and the pixel array layer including the charge storage capacitors 31 and the TFTs 32 is formed on the flexible substrate 5 is referred to as an active matrix substrate 19. it can. On the active matrix substrate 19, an X-ray conversion film 3 that is a semiconductor layer having photoconductivity such as a-Se or CdTe is adhered. On the X-ray conversion film 3, a counter electrode 2 for bias voltage (also referred to as an upper electrode) is formed.

  As shown in FIG. 3, the gate of the TFT 32 is connected to the control line 23, the source is connected to the data line 24, and the drain is connected to the pixel electrode 4. A charge storage capacitor 31 is formed by the pixel electrode 4 and the CS electrode provided opposite thereto.

  When the X-ray image detection apparatus 10 captures an X-ray image, a bias voltage is applied to the counter electrode 2 of each X-ray image detector 1. At the time of imaging, X-rays radiated from an X-ray source (not shown) enter the X-ray conversion film 3 through the subject. In the X-ray conversion film 3, charges corresponding to the incident X-ray dose, that is, pairs of holes and electrons are generated by the photoconductive effect. The generated charges move to the pixel electrode 4 according to the polarity of the bias voltage Vh applied to the X-ray conversion film 3. As a result, an amount of charge corresponding to the incident X-ray dose is accumulated in the charge storage capacitor 31 in the pixel. That is, since the charge storage capacitor 31 and the X-ray conversion film 3 are connected in series via the pixel electrode 4, a bias voltage (Vh) is applied between the counter electrode 2 and the CS electrode 25. If applied, the charges generated in the X-ray conversion film 3 move to the + electrode side and the − electrode side, respectively, and as a result, charges are accumulated in the charge storage capacitor 31.

  Thereafter, the control line 23 on the flexible substrate 5 is scanned and selected in line sequence. The TFT 32 connected to the selected control line 23 is turned on, and the charge stored in the charge storage capacitor 31 is output to the data line 23. Thereby, the charge information of each pixel can be read from the data line. For example, a gate driver that sequentially selects the control line 23 is connected to the end of the control line 23. For example, an amplifier circuit (CSA: Charge Sensitive Amplifier) and an A / D converter are connected to the end of the data line. Thereby, the charge information of each pixel read out via the data line is converted into a digital signal and sequentially output. Here, the electrode wiring (control line 23 and data line 24), TFT 32, charge storage capacitor 31 and the like are all provided in a matrix. Therefore, X-ray image information can be obtained two-dimensionally by sequentially scanning signals input to the control line 23.

  Here, a specific example of the configuration shown in FIG. 2 will be described. In one pixel, a control line (gate line) 23 and a CS electrode 25 are provided on the flexible substrate 5 by a metal film (Ta or the like), and an insulating layer 26 is formed so as to cover them. For the insulating layer 26, for example, SiNx or SiOx is used. A semiconductor film (i layer) 27 is provided in a region that becomes a channel portion of the TFT 32 on the gate line 23. One end of the semiconductor film (i layer) 27 is connected to the source line 24 via a semiconductor film (n + layer) 28 that is in contact with the data line (source line). The other end of the semiconductor film (i layer) 27 is connected to the drain electrode, that is, the pixel electrode 4 through a semiconductor film (n + layer) 28 that is in contact with the drain electrode. Thereby, the TFT 32 which is a switching element connected to the gate line 23, the source line 24, and the pixel electrode 4 is formed.

  The material of the semiconductor films 27 and 28 is not limited to a specific material, but may include, for example, an oxide semiconductor. As the oxide semiconductor, for example, InGaZnOx containing indium (In), gallium (Ga), zinc (Zn), and oxygen (O) as main components can be used. This InGaZnOx, that is, an In—Ga—Zn—O-based semiconductor is a ternary oxide of In, Ga, and Zn, and the ratio (composition ratio) of In, Ga, and Zn is not particularly limited. For example, In: Ga: Zn = 2: 2: 1, In: Ga: Zn = 1: 1: 1, In: Ga: Zn = 1: 1: 2, and the like may be used. By using the TFT 18 having the semiconductor films 27 and 28 including an In—Ga—Zn—O-based semiconductor for the detector 8, the power consumption of the detector 8 can be reduced. In addition, the degree of freedom in designing the active matrix substrate 19 can be increased.

Note that the In—Ga—Zn—O-based semiconductor may be amorphous or may include a crystalline part and have crystallinity. The semiconductor films 27 and 28 may include another oxide semiconductor instead of the In—Ga—Zn—O-based semiconductor. Specifically, the semiconductor films 27 and 28 are formed of, for example, a Zn—O based semiconductor (ZnO), an In—Zn—O based semiconductor (IZO (registered trademark)), or a Zn—Ti (titanium) —O based semiconductor. Semiconductor (ZTO), Cd (cadmium) -Ge (germanium) -O based semiconductor, Cd—Pb (lead) —O based semiconductor, CdO (cadmium oxide) —Mg (magnesium) —Zn—O based semiconductor, An In—Sn (tin) —Zn—O based semiconductor (eg, In ₂ O ₃ —SnO ₂ —ZnO), an In—Ga (gallium) —Sn—O based semiconductor, or the like may be included.

  An insulating layer 34 is provided on the TFT 32. The pixel electrode 4 is formed extending from the drain electrode of the TFT 32 onto the CS electrode 25. A transparent electrode such as ITO can also be used for the pixel electrode 4. A charge storage capacitor 31 can be formed by the pixel electrode 4. An X-ray conversion film 3 is provided over the entire pixel region so as to cover the TFT 32 and the pixel electrode 4.

  As the X-ray conversion film 3, for example, an Se amorphous film can be formed on the active matrix substrate 19 with a thickness of about 0.3 mm by vapor deposition. On the X-ray conversion film 3, the counter electrode 2 is formed of metal (Ti, Ag, etc.). An electron blocking layer made of an AlOx thin insulating layer or the like may be further formed between the X-ray conversion film 3 and the counter electrode 2.

  In the above example, the flexible substrate 5 is formed of a plate-like member having flexibility. For example, the flexible substrate 5 can be formed of a plate material having rigidity and thickness that can be plastically deformed or elastically deformed by applying a force. The thickness of the flexible substrate 5 is not particularly limited, but can be, for example, less than 0.3 mm. Typically, the flexible substrate 5 can be formed with a thickness of 0.500 mm to 0.010 mm. As a material of the flexible substrate 5, for example, a plastic film, an ultra thin plate glass, or stainless steel that is an organic material can be used. Examples of organic materials include PEN (polyethylene 2,6 naphthalate), PES (polyethersulfone), COS (cycloolefin polymer), PC (polycarbonate), PET (polyethylene terephthalate), polyimide, aramid, bio-nanofiber, and the like. It is done. Or, polyether ether ketone (PEEK), polyethylene (PE), polypropylene (PP), polyphenylene sulfide (PPS), polyether imide (PEI), cellulose triacetate (CTA), cyclic polyolefin (COP), polymethyl methacrylate (PMMA) ), Synthetic resin such as polysulfone (PSF), polyamideimide (PAI), nobornene resin, or allyl ester resin can be used as the material of the flexible substrate 5. As long as the flexible substrate 5 can be molded, the rigidity of the flexible substrate 5 is not particularly limited. As a standard, for example, a material having an elastic modulus (Young's modulus) smaller than 50 Gpa can be used for the flexible substrate 5. The material of the flexible substrate 5 is not limited to a specific material. In addition, the flexible substrate 5 has an insulating film, a barrier film for ensuring gas (moisture, oxygen, etc.) barrier properties, an additional film for improving flatness or adhesion to electrodes, and appropriate rigidity. For this purpose, a reinforcing layer and other necessary layers can be provided.

(Effect of this embodiment)
In the above example, the X-ray image detector in which the pixel electrode, the X-ray conversion film, and the counter electrode are formed on the flexible substrate 5 is regarded as one unit, and a plurality of these units are stacked. Here, the material of the flexible substrate 5 has thickness and rigidity so as to have flexibility. Therefore, the flexible substrate 5 is thin with flexibility. In this configuration, the thickness of each unit can be reduced as compared with the case of stacking conventional FPDs. Therefore, many units can be stacked.

  Further, the distance between the X-ray conversion films 3 of the plurality of X-ray image detectors 1 to be stacked can be shortened by reducing the thickness of the unit. Thereby, for example, it is possible to suppress blurring of an image caused by X-rays generated from an X-ray tube and expanding radially, and enlargement of the image. That is, when conventional FPDs are stacked, quality such as blurring and enlargement of the image is affected. Therefore, it is preferable that the conventional X-ray image detection apparatus is configured with one FPD. On the other hand, in the X-ray image detection apparatus according to the present embodiment, the number of X-ray image detectors 1 and the thickness of the X-ray conversion film can be freely set without being restricted by the problem of image quality degradation. Easy to design.

  For example, when an X-ray image detection apparatus is configured with a single FPD as in the prior art, the thickness of the X-ray conversion film must be limited in consideration of the drift length of electrons and holes in the X-ray conversion film. did not become. In contrast, in the present embodiment, by providing a plurality of X-ray image detectors 1, the X-ray conversion film 3 of each X-ray image detector 1 is thin, but a plurality of X-ray image detectors 1 are provided. The total film thickness of the X-ray conversion film 3 of the detector 1 can be adjusted as necessary. The total film thickness of the X-ray conversion film can be determined without being limited by the drift length.

  Even if the total film thickness of the X-ray conversion films is the same, the range of detectable X-rays can be expanded by increasing the number of X-ray image detection devices. The movement of electrons and holes in the X-ray conversion film depends on the product of the mobility, lifetime (relaxation time), and electric field that penetrates the substance constituting the X-ray conversion film. For example, in the X-ray conversion film, when the intensity of incident X-rays is small and the electric field is weak, electrons or holes corresponding to the X-ray dose may not be accumulated in the pixel electrode. That is, in order to accumulate charges due to incident X-rays with low intensity in the pixel electrode, it is necessary to apply a high bias voltage to the counter electrode facing the pixel electrode with the X-ray conversion film interposed therebetween.

  On the other hand, when the incident X-ray is too strong, charge saturation occurs in the charge storage capacitor in the pixel, and measurement becomes impossible. Also, since X-rays have a relatively high transmittance among electromagnetic waves, if a thin X-ray conversion film is used, not all of the incident X-rays can be absorbed. It may disappear. For these reasons, there is a limit to the range of X-rays that can be detected by one X-ray conversion film even if the bias voltage and the thickness of the X-ray conversion film are adjusted.

  In the present embodiment, the plurality of X-ray conversion films 3 are arranged so as to overlap in the X-ray incident direction. Therefore, the incident X-ray is detected by the foreground X-ray image detector 1-1, and the X-ray transmitted through the X-ray image detector 1-1 is detected by the downstream X-ray image detector 1-2. And transparent. The transmitted X-ray is detected and transmitted by the downstream X-ray image detector 1-3. This will continue until the most downstream X-ray image detector 1 or until all the X-rays are absorbed.

  Here, when incident X-rays pass through one X-ray image detector 1, the intensity of transmitted X-rays is smaller than the intensity of incident X-rays due to the X-ray shielding rate of the material of the X-ray image detector 1 itself. Become. According to the configuration of the present embodiment, even when the incident X-ray is strong and is saturated by the upstream X-ray image detector 1-1, it is detected by the downstream X-ray image detectors 1-2, 1-3,. Things are possible. Many X-ray absorptions occur near the surface of the X-ray conversion film. Therefore, when compared with a detector having one X-ray conversion film having the same conversion film thickness as the total of the X-ray conversion films of the plurality of X-ray image detectors 1-1 to 1-5, an X-ray image detector 1-1 to 1-5 can take an X-ray image in a practically wide range.

  That is, in this embodiment, even when X-rays having too high energy are incident, the X-rays are attenuated by the upstream X-ray image detector 1 and the attenuated X-rays are captured by the downstream X-ray image detector 1. I can do things. When X-rays having too low energy are incident, since one X-ray conversion film 3 is thin, it can be detected with a low voltage. Thereby, an X-ray flat panel detector having a wide dynamic range can be realized.

  In the present embodiment, at least two of the plurality of X-ray image detectors 1-1 to 1-5 are configured to detect X-rays in different wavelength ranges of incident continuous X-rays. it can. For example, the thickness in the X-ray incident direction of the X-ray conversion film 3 of the two or more X-ray image detectors 1 on the upstream side among the plurality of X-ray image detectors 1-1 to 1-5 is set as the downstream X-ray image. It can be set according to the penetration length of the wavelength region to be detected by the detector 1. Thereby, X-rays in different wavelength regions can be detected among the incident continuous X-rays.

  A specific example in the case of detecting different wavelength regions of continuous X-rays will be described with reference to FIG. The configuration shown in FIG. 4 is the same as that of the X-ray image detection apparatus 10 shown in FIG. As an example, a case where X-rays in a certain wavelength range are desired to be detected by the third X-ray image detector 1-3 from the upstream will be described. In this case, the total (T1 + T2) of the thicknesses T1 and T2 of the X-ray conversion film layers 3 of the X-ray image detectors 1-1 and 1-2 upstream (front surface) of the X-ray image detector 1-3 is expressed as X The line image detector 1-3 has a thickness less than the penetration length of continuous X-rays included in the wavelength region to be detected. That is, the thicknesses of the X-ray image detectors 1-1 and 1-2 are set so that X-rays having a wavelength longer than the wavelength of the X-rays to be detected by the X-ray image detector 1-3 are absorbed upstream. To do. As a result, X-rays X3, X4, and X5 in the wavelength range desired to be detected by the X-ray image detector 1-3 reach the X-ray conversion film 3 of the X-ray image detector 1-3, and X in the longer wavelength range. The lines X1 and X2 are attenuated by the X-ray image detectors 1-1 and 1-2. Therefore, the X-ray image detector 1-3 can detect X-rays X3, X4, and X5 in a desired wavelength range.

  In the example shown in FIG. 4, the X-ray having high energy is detected by the downstream X-ray image detector 1 using the fact that the X-ray having high energy penetrates deeper into the substance. That is, the X-ray wavelength or wavelength range detected for each X-ray image detector 1 can be varied. Therefore, it becomes possible to simultaneously detect a plurality of wavelength components included in continuous X-rays. Thereby, the wavelength component of the energy of the X-ray detected for every pixel can be decomposed | disassembled. As a result, for example, it is possible to photograph measurement objects having different transmittances at a time.

  As described above, the X-ray image detection apparatus according to the embodiment can be used for imaging using continuous X-rays. Further, it is possible to configure by changing the thickness of the X-ray conversion film layer in accordance with the X-ray penetration depth in the wavelength region to be detected. In this way, by adjusting the thickness of the X-ray conversion film of the X-ray image detector 1, energy can be decomposed with respect to the incident continuous X-rays, for example, by the number of layers. Further, continuous X-rays in a wavelength region including characteristic X-rays can also be targeted.

<Embodiment 2>
FIG. 5 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the second embodiment. In the example shown in FIG. 5, in the plurality of X-ray image detectors 1-1 to 1-3, the detection surface of the pixel electrode 4 of at least one pixel in one X-ray image detector 1-1 is the other X-ray image detector 1-1. The line image detectors 1-2 and 1-3 partially overlap the detection surface of the pixel electrode 4 of the corresponding pixel in the X-ray incident direction f. In the present embodiment, the detection surface of the pixel electrode 4 indicates a portion in contact with the X-ray conversion film 3.

  For example, the pixel electrode 4-1 of the most upstream X-ray image detector 1-1 and the corresponding pixel electrode 4-2 of the second X-ray image detector 1-2 from the upstream are in the X-ray incident direction. It is shifted in a direction perpendicular to f (in this example, a direction parallel to the detection surface). Thereby, the pixel electrode 4-1 and the pixel electrode 4-2 are in a state where a part thereof overlaps in the X-ray incident direction f and the other part does not overlap. Similarly, the pixel electrode 4-2 of the X-ray image detector 1-2 and the pixel electrode 4-3 of the downstream X-ray image detector 1-3 are partially overlapped. The pixel electrode 4-1 and the pixel electrode 4-3 also have overlapping portions and non-overlapping portions. By arranging the corresponding pixel electrodes 4-1 to 4-3 having the same coordinates so as not to overlap in the X-ray incident direction, an improvement in resolution is expected.

  In the present embodiment, the pixel center of one X-ray image detector 1 is shifted by a specific amount in an arbitrary direction on the TFT matrix plane with respect to the pixel centers of other adjacent X-ray image detectors 1. Be placed. By performing image processing on the X-ray images detected by the plurality of X-ray image detectors 1, a high resolution can be obtained in a pseudo manner. FIG. 6 is a diagram for explaining an example of detecting X-rays that have passed through the vicinity of the pixel electrodes 4-1 to 4-3. In the example shown in FIG. 6, the direction perpendicular to the detection surfaces of the X-ray image detectors 1-1 to 1-3 is taken as the Z axis, and the axes orthogonal to each other in the plane perpendicular to the Z axis are taken as the X axis and the Y axis. Yes. As shown in FIG. 6, the X-ray transmitted through the pixel electrode 4-1 of the first X-ray image detector 1-1 enters the second X-ray image detector 1-2. The position of the pixel electrode 4-2 on the XY plane is shifted by Δx in the X direction with respect to the position of the pixel electrode 4-1 on the XY plane. Whether or not the X-ray transmitted through the pixel electrode 4-1 is also detected by the pixel electrode 4-2 depends on the amount of deviation Δx between the pixel electrode 4-1 and the pixel electrode 4-2, and the X-ray incident position. Depends on. Therefore, the incident position of the X-ray in the X direction can be detected with a finer accuracy than the length of the pixel electrode 4-1 in the X direction.

  In the example illustrated in FIG. 6, the three pixel electrodes 4-1 to 4-3 are arranged so as to be shifted in the X direction by about one third of the length of the pixel electrode in the X direction. That is, Δx is about one third of the length of the pixel electrode in the X direction. Therefore, the resolution in the X direction can be approximately tripled. Here, a virtual pixel is set by dividing one pixel electrode into about three equal parts in the X direction. Virtual pixels around the pixel electrodes 4-1 to 4-3 are denoted by a to g. The X-ray X1 incident on the pixel d passes through the pixel electrodes 4-1, 4-2 and 4-3. Therefore, when the number of arrivals of X1 is 1, detection is performed once for each of the pixel electrodes 4-1, 4-2, and 4-3. The number of detections in the virtual pixel group (a, b, c, d, e, f, g) is (0111000) for the pixel electrode 4-1, and (0011100), 4 for the pixel electrode 4-1, as shown in FIG. -3 is (0001110). When these are added, an arrangement of the number of times of detection (0123210) can be obtained. When the X-ray reaches the position of the pixel c once, (1232100) is obtained. When the X-rays reach both the pixel d and the pixel c once, they are overlapped to form an array of detection times of (0123210) + (1232100) = (13555310). Similarly, in the Y direction, it is possible to obtain an arrangement of the number of detections by shifting the pixel electrodes 4-1 to 4-3 in the Y direction. In this manner, for example, by performing two-dimensional peak fitting on the two-dimensional arrangement of the detection counts represented as an overlap of the detection counts at a plurality of virtual pixels, the number of arrivals at each virtual pixel is obtained. Can be calculated. Actually, X-rays may be shielded after passing through the pixel electrodes 4-1 and 4-2. Therefore, it is more effective to correct this based on absorption of X-rays before obtaining the number of detections. The accuracy can be increased.

As an example, when the X-ray i reaches ni times in a virtual pixel whose position in the X direction is xi, the detection count mi at the position x in the X direction in any virtual pixel is expressed as a function of x. It can represent with following formula (1).
When | x−xi | ≦ 2Δx, mi (x) = (3ni) (1− | {1 / (3Δx)} × (x−xi) |)
When 2Δx <| x−xi | mi (x) = 0 ―― (1)
In the above equation (1), Δx is the size (the shift amount between 4-2 and 4-1) of the virtual pixel in the X direction. xi and x are discontinuous amounts in increments of Δx. The symbol “||” indicates an absolute value.

  According to the above equation (1), the number of detections mi at xi and its surrounding virtual pixels (xi−2Δx, xi−Δx, xi, xi + Δx, xi + 2Δx) when the X-ray reaches ni times in xi is ((1ni), (2ni), (3ni), (2ni), (1ni)).

Here, when the number of times of detection in the entire pixel region is M, the arrival of X-rays at all positions can be expressed by the following equation (2) using the above equation (1).
M (x) = Σmi (x) + m0 (2)
Here, Σ is a symbol representing the sum of a sequence of numbers, and indicates that a sum is obtained for all i. m0 is a constant corresponding to an offset component including other error components such as noise.

  Since the arrangement of the number of detections based on the X-rays that have reached a plurality of pixels can be expressed by the above equation (2) as a superposition of the function expressed by the above equation (1), for example, the nonlinear least square method (iterative method) ) Can be used to calculate the value of the number of arrivals ni of the X-ray i in each virtual pixel. Note that the function used for the fitting is not limited to the above formula (1), and it can be approximated by using a general peak function such as a Gaussian function.

  As shown in FIG. 5, in the case of a configuration in which three X-ray image detectors 1-1 to 1-3 are stacked, the information amount is three times the resolution with respect to one axis (for example, the x axis). become. In the configuration of the present embodiment, since a plurality of X-ray image detectors 1 are installed in an overlapping manner, the position of incident light can be specified with higher accuracy substantially exceeding the resolution of one X-ray image detector. Can do.

  The detailed configuration of each X-ray image detector 1 in the present embodiment can be the same as that in the first embodiment. In addition, the same effects as in the first embodiment can be obtained in the present embodiment.

  In the example shown in FIG. 5, the pixel electrodes 4-2 and 4-3 of the downstream X-ray image detector are shifted in one direction (the positive direction of the x axis) as going downstream. However, the displacement direction of the pixel electrode is not limited to one direction. For example, the pixel electrode 4-2 and the pixel electrode 4-3 may be shifted in opposite directions with respect to the pixel electrode 4-1. That is, the direction in which the pixel electrodes are displaced can be staggered. It is also possible to shift the pixel electrodes by specific amounts in the x direction and the y direction, respectively. Thereby, the resolution in the x direction and the resolution in the y direction can be increased.

  In the example shown in FIG. 5, all the pixel electrodes in one X-ray image detector 1 are shifted from the pixel electrodes of other X-ray image detectors 1. On the other hand, the above effect can also be obtained by shifting at least some of the pixel electrodes in one X-ray image detector 1 with respect to the pixel electrodes of other X-ray image detectors 1. .

<Embodiment 3>
7 and 8 are cross-sectional views illustrating a configuration example of the X-ray image detection apparatus according to the third embodiment. In the X-ray image detection apparatus shown in FIG. 7, a plurality of X-ray image detectors 1-1 and 1-2 having different thicknesses T1 and T2 of the X-ray conversion film 3 are stacked in the X-ray incident direction. A shielding member 37 that restricts transmission of X-rays having a certain wavelength or wavelength region is provided between two adjacent X-ray image detectors 1-1 and 1-2. The detailed configuration of each X-ray image detector 1 shown in FIG. 7 can be the same as that of the first embodiment.

  As shown in FIG. 7, the wavelength range of X-rays detected in each of the plurality of X-ray conversion films 3 can be controlled by making the thicknesses of the plurality of X-ray conversion films 3 different. Alternatively, instead of making the thicknesses of the plurality of X-ray conversion films 3 different, the materials of the plurality of X-ray conversion films 3 can be made different. Also by this, the wavelength range of X-rays detected in each of the plurality of X-ray conversion films 3 can be controlled.

  Further, the shielding member 37 can remove unnecessary X-rays in the wavelength region. Alternatively, the shielding plate 37 can be used to more accurately extract X-rays in a wavelength region desired to be detected downstream by blocking X-rays in a specific wavelength region.

  For example, the film thickness T1 of the X conversion film 3 can be set so that X-rays in the wavelength region x1 are substantially blocked by the upstream X-ray image detector 1-1. Further, the thickness of the shielding film 37 is set so that the shielding film 37 substantially shields the X-ray in the wavelength region x2 and the X-ray in the wavelength region x3. Thereby, it can be set as the structure by which the X-ray of the wavelength range x4 outside the wavelength range x1, x2, x3 is detected by the X-ray image detector 1-2.

  The bias voltage (voltage of the counter electrode 2) applied to each X-ray conversion film can be set according to the energy of X-rays to be detected in each X-ray image detector 1. In this case, the bias voltages of the X-ray conversion films in the plurality of X-ray image detectors 1-1 and 1-2 are often different from each other.

  As an example, it is possible to provide a power supply unit that supplies a voltage independently to the counter electrode 2 in the X-ray image detector 1-1 and the counter electrode 2 in another X-ray image detector 1-2. FIG. 9 is a diagram illustrating a configuration example in the case of supplying different voltages for each X-ray image detector. In the example shown in FIG. 9, in each of the X-ray pixel detectors 1-1 and 1-2, for each pixel, the pixel electrode 4 in contact with the X-ray conversion film 3 and the X-ray conversion film 3 through the pixel electrode 4. A charge storage capacitor 31 for storing the received charge and a TFT 32 for controlling the output of the stored charge are provided. The drain terminal of the TFT 32 is connected to the pixel electrode 4, the gate terminal 32g is connected to the control line 23 (see FIG. 3), and the source terminal 32s is connected to the data line 24 (see FIG. 3). The pixel electrode 4, the charge storage capacitor 31, the TFT 32, the control line 23, and the data line 24 can be formed on the flexible substrate 5 as in the above embodiment. Further, the counter electrode 2 is integrally formed at a position facing the plurality of pixel electrodes 4 with the X-ray conversion film 3 interposed therebetween.

  In the example shown in FIG. 9, power supply units 7-1 and 7-2 for supplying a bias voltage to the counter electrode 2 are provided in the X-ray image detectors 1-1 and 1-2, respectively. Thereby, a voltage can be independently supplied to the counter electrode 2 in the X-ray image detector 1-1 and the counter electrode 2 in the X-ray image detector 1-2. For example, the bias voltage Vh-1 at the time of imaging by the X-ray image detector 1-1 may be different from the bias voltage Vh-2 at the time of imaging by the X-ray image detector 1-2. For example, an appropriate bias voltage can be set according to the film thickness of the X-ray conversion film 3. In the example shown in FIG. 9, the film thickness of the X-ray conversion film 3 of the X-ray image detector 1-2 is smaller than the film thickness of the X-ray conversion film 3 of the X-ray image detector 1-1. The bias voltage Vh-2 of the line image detector 1-2 can be made smaller than the bias voltage Vh-1 of the X-ray image detector 1-1 (Vh-1> Vh-2). Thus, the bias voltage can be increased in proportion to the film thickness.

  In addition, when it is desired to reduce the influence of dark current (leakage current), the bias voltage can be lowered accordingly. In addition, since the amount of electrons (carriers) generated is higher in the upstream than in the downstream, charge saturation tends to occur. In order to prevent charge saturation, the voltage can be set lower as it goes upstream. As another example, when different materials are used for the conversion films of the plurality of X-ray image detectors 1-1 and 1-2, a material having a longer mean free path in which electrons (carriers) move is used. It is also possible to lower the bias voltage. The detected amount of carriers tends to change depending on the amount of incident X-rays, wavelength, physical properties (mobility, lifetime), film thickness, voltage, and the like. Therefore, as in the above example, the detected amount of carriers can be adjusted by setting the voltage of the conversion film.

  In the present embodiment, X-rays having different wavelength ranges included in incident continuous X-rays due to the thickness of the X-ray conversion film 3, the material of the X-ray conversion film 3, or the shielding member 37 between the X-ray image detectors 1. Can be detected by different X-ray image detectors 1 respectively. That is, it becomes possible to control the decomposition range of X-ray energy.

  For example, it is effective when it is desired to know the energy distribution of specific X-rays at each detector. In the example shown in FIG. 8, X-rays radiated from an X-ray source and detected by passing through the measurement object 36 are converted into X-rays converted by the X-ray image detector 1-1 installed on the front surface (upstream). Detected with the membrane 3. Of the X-rays transmitted through the X-ray image detector 1-1, those having low energy are shielded by the shielding member 37. X transmitted through the shielding member 37 is detected by the X-ray image detector 1-2 installed further downstream (rear part).

  In this configuration, a description will be given of a case where, among X-rays detected through the measurement object 36, both the X-ray whose wavelength component of energy is 30 keV or more and the entire energy of the incident continuous X-ray are desired to be known. To do. In this case, the film thickness of the X-ray conversion film 3 of the X-ray image detector 1-1 installed on the front surface (the most upstream) is adjusted according to the X-ray penetration length at which the energy wavelength component is about 30 eV. . In this example, the thickness of the X-ray conversion film 3 of the X-ray image detector 1-1 can be set to be smaller than the penetration length of the X-ray where the wavelength component of energy is around 30 eV. Thereby, among the continuous X-rays incident on the X-ray image detector 1-1, X-rays containing a wavelength component of energy near 30 eV are transmitted, and X-rays having a wavelength longer than the wavelength corresponding to this energy are transmitted. It can be prevented from being transmitted. The entire energy of the incident continuous X-ray is detected by the X-ray image detector 1-1. Further, among the X-rays transmitted through the X-ray image detector 1-1, those having energy lower than the vicinity of 30 eV as a wavelength component are shielded by the shielding member 37. Thereby, the X-ray image detector 1-2 detects X-rays having a wavelength of 30 eV or more.

<Embodiment 4>
FIG. 10 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the fourth embodiment. In the example shown in FIG. 10, the flexible substrate 5 of the X-ray image detectors 1-1 to 1-3 has a curved surface that is recessed in the direction f in which X-rays are incident. The X-ray conversion film 3 is formed along this curved surface. That is, the X-ray conversion film 3 also has a curved surface that is recessed in the direction f incident on the X-rays. In the example shown in FIG. 10, the central portion of the flexible substrate 5 is most recessed, and the recess becomes shallower as it approaches the periphery of the flexible substrate 5 from the central portion. The central portion of the X-ray conversion film 3 is also most recessed along the flexible substrate 5, and the recess is shallower as it approaches the periphery from the center. As a result, the X-ray incident angle at the central portion of the X-ray conversion film 3 and the X-ray incident angle at the peripheral portion can both be close to 0 degrees.

  In the example shown in FIG. 10, the shape of the curved surface of the flexible substrate 5 in the cross section of the XZ plane passing through the radiation source 6 is an arc shape. The X-ray source 6 can be arranged near the center of the virtual circle formed by this arc. Thereby, the distance from the X-ray source 6 to the incident surface of the X-ray conversion film 3 can be made uniform. Note that the cross-sectional shape of the curved surface in the XY plane may similarly be an arc shape or a linear shape. For example, by making the curved surface of the flexible substrate 5 spherical, the detection surface of the X-ray conversion film 3 can also be spherical.

  Thus, in this embodiment, the flexible substrate 5 and the X-ray conversion film 3 are formed in a bent state so that the detection surface of the X-ray conversion film 3 is perpendicular to the incident X-rays. Thereby, the distance until X-rays are emitted from the X-ray source 6 and reach the detection surface of the X-ray conversion film 3 can be made substantially constant over the entire detection surface. Thereby, the X-ray dose leaking from the detection range is reduced. Even if the X-ray source is not a point light source, the X-ray conversion film 3 having a shape suitable for the apparatus configuration can be created by taking advantage of the ease of forming the flexible substrate 5. For example, the X-ray emitted from the X-ray source 6 is perpendicular to the detection surface at any position on the detection surface of the X-ray conversion film 3, that is, the flexible substrate 5 and the X-ray so that the incident angle approaches 0 degrees. The line conversion film 3 can be formed.

  When the detection surface of the X-ray conversion film that receives X-rays radiated from the X-ray source 6 is a flat surface, the distance from the X-ray source 6 is different for each pixel. Since the X-ray dose is inversely proportional to the square of the distance, the X-ray energy obtained at the peripheral pixels is less than that at the central pixel of the detection surface. Since the incident angle of the captured image increases toward the periphery, the image is stretched and the resolution tends to decrease. In the present embodiment, the X-ray image detector 1 can be configured such that the distance between the X-ray source 6 and the pixels of each X-ray image detector 1 is constant over the entire detection surface. As a result, it is possible to obtain a constant image independent of the pixel coordinates.

  The detailed configuration of each X-ray image detector 1 in the present embodiment can be the same as that in the first embodiment except for the shape that is recessed in the direction in which the X-rays are incident.

<Embodiment 5>
FIG. 11 is a cross-sectional view illustrating a configuration example of the X-ray image detection apparatus according to the fifth embodiment. 12 is an enlarged view of the X-ray image detectors 1-1 to 1-3 shown in FIG. In the example shown in FIGS. 11 and 12, in the X-ray image detector 1-1, X-rays penetrating the detection surface of the pixel electrode 4a-1 corresponding to a certain pixel are converted into other X-ray image detectors 1-2, In 1-3, the pixel electrodes 4 of the X-ray image detector 1-1 and other X-ray image detectors 1 so as to penetrate the detection surfaces of the pixel electrodes 4a-2 and 4a-3 of the pixels corresponding to the pixels. -2 and 1-3 pixel electrodes 4 are arranged.

  In the example shown in FIG. 11 and FIG. 12, the pixels of the X-ray image detectors 1-2 and 1-3 on the downstream side of the pixels in the X-ray image detector 1-1 have a radial spread of incident X-rays. It is arranged at a position spread according to the degree. For example, the pixel group of the X-ray image detectors 1-2 and 1-3 can be arranged in a larger area and size than the pixel group in the X-ray image detector 1-1. That is, the region where the X-ray conversion film 3 and the pixels are arranged can be changed so as to reduce the spread of the image with respect to the incident X-rays.

  When X-rays radiated from the X-ray source 6 enter the X-ray image detection device, the image is enlarged and displayed as the distance from the X-ray source 6 increases if the detection surface of the X-ray conversion film 3 is a plane. Therefore, in this case, even if the distance between the X-ray image detectors 1 is maximized, the sizes of the images detected by the plurality of X-ray image detectors 1-1, 1-2, and 1-3. It is difficult to keep the same at all times. Therefore, strictly speaking, X-ray images captured by a plurality of X-ray image detectors are often in different ranges with respect to the display area. Therefore, in the present embodiment, the X-ray image detection apparatus has X-ray image detectors 1-1, 1 whose sizes are sequentially changed so as to follow the width of the spread of the X-rays emitted and incident from the X-ray source 6. -2, 1-3 are arranged. That is, the X-rays emitted from the X-ray source 6 are configured to be displayed as the same coordinates by the respective X-ray image detectors 1-1 to 1-3. Therefore, the display range shift for each X-ray image detector 1 can be suppressed. As a result, the sizes of the images obtained by the plurality of X-ray image detectors 1-1, 1-2, and 1-3 can be made closer to each other.

  The X-ray source 6 does not have to be a point light source as shown in FIG. The detailed configuration of each X-ray image detector 1 in the present embodiment can be the same as that of the first embodiment except for the shape that is recessed in the direction in which the X-rays are incident.

(Modification)
As mentioned above, although embodiment was described, embodiment of this invention is not restricted to the said Embodiment 1-5. In the above example, the TFT 32, the pixel electrode 4, the control line 23, and the data line 24 are provided between the flexible substrate 5 and the X-ray conversion film 3, but the configuration is not limited thereto. For example, the counter electrode 2 is provided on the surface of the X-ray conversion film 3 on the side of the flexible substrate 5, and the TFT 32, the pixel electrode 4, and the control line 23 are provided on the surface facing the surface of the X-ray conversion film 3 on the side of the counter electrode 2. , Data line 24 can be. In this case, the counter electrode 2 and the X-ray conversion film 3 are formed on the flexible substrate 5, and the TFT 32, the pixel electrode 4, the charge storage capacitor 31, the control line 23, and the data line 24 are formed on the X-ray conversion film 3. The structure to do may be sufficient.

  The above example is a direct conversion type X-ray image detection apparatus, but the present invention can also be applied to an indirect conversion type X-ray image detection apparatus. In the case of the indirect conversion type, the X-ray conversion film 3 can be a scintillator film that generates visible light corresponding to the incident X-ray dose. As the scintillator film, for example, a CsI film or the like can be used. The detection element is a photodiode.

  FIG. 13 is a cross-sectional view illustrating a configuration example of an indirect conversion type X-ray image detection apparatus. In the example shown in FIG. 13, in each of the plurality of X-ray image detectors 1-1 to 1-3, the photodiode 4a corresponding to each of the plurality of pixels is provided on one surface of the scintillator film 3a as the X-ray conversion film. Is placed. Although not shown, a charge storage capacitor and a TFT are connected to the photodiode 4a. A control line and a data line are connected to the TFT. The configurations of these charge storage capacitors, TFTs, control lines, and data lines can be the same as those in the above embodiment. The photodiode 4a receives the light emitted from the scintillator film 3a and generates a charge corresponding to the amount of light received. This charge is stored in the charge storage capacitor. By the operation of the TFT based on the control signal of the control line, a signal based on the charge of the charge storage capacitor is output via the TFT and the data line. As a result, a signal based on the charge corresponding to the amount of light received for each pixel is output as a signal indicating the X-ray dose of each pixel.

  In the above configuration, each X-ray image detector includes the flexible substrate 5 having flexibility, but the X-ray image detection device itself in which a plurality of X-ray image detectors are stacked does not need to have flexibility. For example, in each of the X-ray image detectors 1, a substrate (for example, a glass substrate or the like) that is higher in rigidity than the flexible substrate 5 may be attached to the flexible substrate 5. In the example shown in FIG. 14, in each of the X-ray image detectors 1-1 to 1-5, the flexible substrate 5 is attached to the substrate 41 having higher rigidity. Alternatively, for example, as shown in FIG. 15, a plurality of stacked X-ray image detectors may be attached to a substrate 42 having a higher rigidity than the flexible substrate 5. In the example of FIG. 15, each X-ray image detector 1-1 to 1-5 is bonded to an adjacent X-ray image detector. On the substrate 42, a plurality of X-ray image detectors 1-1 to 1-5 bonded to each other are stacked. Thereby, in the X-ray image detector 1 or the X-ray image detection apparatus, deformation of the flexible substrate 5 due to an external force can be suppressed.

  The configuration for obtaining the desired rigidity is not limited to the one using the substrates 41 and 42 as described above. For example, the X-ray conversion film 3 can be formed of a material having higher rigidity than the flexible substrate 5. In this case, the deformation of the X-ray image detector due to the external force can be suppressed by the rigidity of the X-ray conversion film 3. In addition, the flexible substrate 5 can be formed of a plastic material.

  Moreover, the use of the X-ray image detection apparatus of the said embodiment is not limited to a specific thing. For example, the X-ray image detection apparatus of the above-described embodiment can be used for medical use, industrial inspection use, research use, and other various uses. For medical use, for example, in addition to an X-ray imaging apparatus used for imaging of the chest, abdomen, bones, joints, etc., the mammography and tomosynthesis imaging apparatus such as a tomosynthesis imaging machine, An X-ray image detection apparatus can be used. For research purposes, for example, the X-ray image detection apparatus can be used for studies such as astronomy, particle physics, and materials science using cosmic rays.

1, 1-1, 1-2, 1-3 X-ray image detector 2 Counter electrode 3 X-ray conversion film 4 Pixel electrode 5 Flexible substrate 6 X-ray source 10 X-ray image detection device

Claims (7)

A plurality of X-ray image detectors arranged so as to overlap in the X-ray incident direction;
Each of the X-ray image detectors is
A substrate formed of a flexible material;
An X-ray conversion film that is fixed to the substrate and generates a charge or visible light corresponding to the incident X-ray dose;
A detection element provided corresponding to each of a plurality of pixels arranged on one surface of the X-ray conversion film, and having a detection surface in contact with the X-ray conversion film;
A switching element connected to each of the plurality of detection elements;
A data line connected to the switching element and transmitting a signal based on charge or visible light collected on the detection surface of the detection element as a signal indicating an X-ray dose in each pixel;
An X-ray image detection apparatus having a control line connected to the switching element and supplying a signal for controlling the switching element.   2. The X-ray image detection apparatus according to claim 1, wherein at least two of the plurality of X-ray image detectors detect X-rays in different wavelength ranges from incident continuous X-rays.   The detection surface of the detection element in at least one pixel in one X-ray image detector among the plurality of X-ray image detectors includes the detection surface of the detection element in the corresponding pixel of the other X-ray image detector, The X-ray image detection apparatus according to claim 1, wherein the X-ray image detection apparatus partially overlaps in the X-ray incident direction.   A shielding member that is provided between two adjacent X-ray image detectors among the plurality of X-ray image detectors and that limits transmission of X-rays having a certain wavelength or wavelength range. The X-ray image detection apparatus according to any one of the above. The substrate has a curved surface that is recessed in the direction of incidence of X-rays,
The X-ray image detection apparatus according to claim 1, wherein the X-ray conversion film is formed along the curved surface.   Among the plurality of X-ray image detectors, X-rays penetrating a detection surface of a detection element of at least one pixel in one X-ray image detector detect a detection element in a corresponding pixel in another X-ray image detector. The detection surface of the detection element of the one X-ray image detector and the detection surface of the detection element of the other X-ray image detector are arranged so as to penetrate the surface. The X-ray image detection apparatus described in the item. Each of the X-ray image detectors has a counter electrode provided at a position facing the detection surface of the detection element on the other surface facing the one surface of the X-ray conversion film,
A power supply unit that independently supplies a voltage to the counter electrode in one X-ray image detector of the plurality of X-ray image detectors and the counter electrode in another X-ray image detector; The X-ray image detection apparatus of any one of Claims 1-6.

Images