JP2011227044A - Radiation imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation imaging device which can be used for a plurality of applications.SOLUTION: A light shielding layer 27 which shields light generated respectively by light emitting layers 28A, 28B is provided between radiation detectors 20A, 20B with light emitting layers 28A, 28B having different properties for radiation. Thereby the light emitted by each light emitting layer 28A, 28B can be separated and measured respectively, and radiation images including different information such as responsibility to energy, sensitivity and resolution can be simultaneously imaged.

Description

  The present invention relates to a radiation imaging apparatus.

  In recent years, a radiation sensitive layer is disposed on a TFT (Thin Film Transistor) active matrix substrate, radiation such as irradiated X-rays is detected, and an electric signal indicating a radiation image represented by the detected radiation is output (FPD). Radiation detectors such as Flat Panel Detector have been put into practical use. This radiation detector has an advantage that an image can be confirmed immediately and a moving image can be confirmed as compared with a conventional imaging plate.

  As a technique relating to this type of radiation detector, Patent Document 1 discloses that a first scintillator is formed on one surface of a photoelectric conversion unit capable of receiving light from both front and back surfaces, and a second scintillator is formed on the other surface of the photoelectric conversion unit. And a radiation detector in which a first scintillator, a photoelectric conversion unit, and a second scintillator are sequentially stacked. According to the technique disclosed in Patent Document 1, X-rays are incident from the first scintillator side during imaging and the first scintillator emits light, and the second scintillator emits light by X-rays transmitted through the first scintillator. In addition, it is possible to increase the sensitivity by receiving both the light generated by the first scintillator and the second scintillator in the photoelectric conversion unit.

  Patent Document 2 discloses a two-layer scintillator that converts irradiated radiation into light and a two-layer scintillator that detects light converted by the two-layer scintillator and detects an electrical signal. A radiation detector comprising a solid-state photodetector that converts to

JP-A-9-145845 JP 2007-163467 A

  However, although the radiation detectors of the techniques of Patent Document 1 and Patent Document 2 can increase the sensitivity by receiving both light generated by the two scintillators, they cannot individually detect the light generated by the two scintillators. For this reason, it is not possible to individually obtain a radiographic image by light generated by each scintillator, and when it is desired to obtain an energy subtraction image by radiographic images by light generated by two scintillators, imaging is performed by another radiographic apparatus. There is a need to do.

  An object of this invention is to provide the radiography apparatus which can be used for several uses in view of said situation.

  In order to achieve the above object, the radiation imaging apparatus according to the first aspect of the present invention includes a light emitting layer that generates light when irradiated with radiation, and charges are accumulated by receiving the light generated in the light emitting layer. Each having a substrate on which a switching element for reading out the electric charge is formed and disposed so as to overlap each other, and the two radiation detectors provided between the two radiation detectors. A light-shielding layer that shields light generated in the light-emitting layer of the detector from each other.

  The radiation imaging apparatus according to the present invention includes a light emitting layer that generates light when irradiated with radiation, and a switch element that accumulates charges by receiving light generated in the light emitting layer and reads the charges. Two radiation detectors each having a formed substrate are arranged so as to overlap each other, and a light shielding layer is provided between the two radiation detectors to shield the light generated in the light emitting layers of the two radiation detectors from each other. It has been.

  As described above, the present invention provides a light-emitting layer of one radiation detector by providing a light-shielding layer that shields light generated in the light-emitting layers of the two radiation detectors between the two radiation detectors. Does not enter the other radiation detector, and the light of the light emitting layer of the other radiation detector does not enter one of the radiation detectors, and the radiation image by the light generated in the light emitting layer is individually detected. Can be used in multiple applications.

In the present invention, as in the invention described in claim 2, the two radiation detectors may be arranged such that a light emitting layer is sandwiched between the light shielding layers.

  Moreover, this invention is good also as the light-shielding board | substrate which has the rigidity as the said light-shielding layer like invention of Claim 3.

  Further, in the present invention, as in the invention described in claim 4, the light emission characteristics of the light emitting layers of the two radiation detectors with respect to radiation may be different.

  According to a fourth aspect of the invention, as in the fifth aspect of the invention, the light emitting layers of the two radiation detectors are filled with the thickness of each light emitting layer and each light emitting layer and irradiated with radiation. The particle size of the particles that emit light, the layered structure of the particles, the filling rate of the particles, the dope amount of the activator, the material of each light emitting layer, and at least one change in the layer structure of each light emitting layer, and each Any of the formation of the reflective layer that reflects the light on the surface of the light emitting layer that is not opposed to the substrate may be performed.

  Further, in the invention according to claim 4 or claim 5, as in the invention according to claim 6, one of the light emitting layers of the two radiation detectors has a light emitting characteristic emphasizing image quality, and the other has an emphasis on sensitivity. The light emission characteristics may be used.

  Further, in the invention according to claim 4 or 5, as in the invention according to claim 7, when the radiation layer of the two radiation detectors is irradiated with radiation from one side, The light emission characteristics may be substantially the same.

  Further, in the invention described in claims 1 to 7, as in the invention described in claim 8, at least one of the light emitting layers of the two radiation detectors emits light when irradiated with radiation. You may be comprised including the columnar crystal of a body material.

  In the invention described in claim 8, as in the invention described in claim 9, the phosphor material may be CsI.

  Further, the invention according to claims 1 to 9 is different from the invention according to claim 10 in that the readout characteristics of the signals obtained by reading the accumulated charges on the substrates of the two radiation detectors are different. It may be.

  Further, in the invention described in claims 1 to 10, as in the invention described in claim 11, the light shielding layer may shield radiation.

  Further, according to the invention described in claims 1 to 11, as in the invention described in claim 12, the charges accumulated in the two radiation detectors can be individually read out, and the accumulated charges Are respectively generated as electrical signals, generating means for generating image information indicating a radiation image based on the read electrical signals, receiving means for receiving processing conditions for the two radiation detectors, and processing for the two radiation detectors And a management unit that manages processes for the two radiation detectors according to the processing conditions received by the receiving unit.

  According to a twelfth aspect of the present invention, as in the thirteenth aspect of the present invention, chargeable reading from the two radiation detectors by the generating means is performed in a replaceable process for the two radiation detectors. Processing, image processing for image information read from each of the two radiation detectors and generated by the generation unit, image information generated by the generation unit and transmission processing of the image information subjected to the image processing, and It is good also as at least 1 of the preservation | save processing of the image information produced | generated by the production | generation means and the said image processed image information.

  The invention according to claims 1 to 13 is formed in a flat plate shape as in the invention according to claim 14, and the two radiation detectors and the light shielding layer are built in the flat plate. An imaging unit capable of imaging a radiation image of radiation applied on either one of the surface side and the other surface side, a control unit including the reception unit and the management unit, the imaging unit, and the control And a connecting member that can be opened and closed in an unfolded state in which the units are arranged and a storage state in which the photographing unit and the control unit are overlapped and folded.

  The invention described in claims 1 to 13 is formed in a flat plate shape as in the invention described in claim 15, and the two radiation detectors and the light shielding layer are built in, and the flat plate An imaging unit capable of capturing a radiographic image of radiation applied on either one side or the other surface, a control unit including the reception unit and the management unit, and the control unit A connecting member that reversibly connects one surface and the other surface of the photographing unit.

  The radiation imaging apparatus of the present invention has an excellent effect that a radiation imaging apparatus that can be used in a plurality of applications can be provided.

It is sectional drawing which showed typically the structure of the radiation detector which concerns on embodiment. It is the top view which showed the structure of the radiation detector which concerns on embodiment. It is sectional drawing which showed roughly the structure of the TFT substrate which concerns on embodiment. It is sectional drawing which showed the structure of the radiation detector which concerns on embodiment. It is a graph which shows the change of the thickness and sensitivity of a scintillator layer concerning an embodiment. It is a graph which shows the change of the thickness of a scintillator layer and image quality concerning an embodiment. It is sectional drawing which shows the structure of the imaging | photography part which concerns on embodiment. It is the schematic diagram which showed the multilayer structure of the small particle and large particle of a scintillator layer. It is sectional drawing which shows a structure at the time of forming a reflection layer in the surface on the opposite side to the TFT substrate of a scintillator layer. It is a perspective view which shows the structure of the flat electronic cassette which concerns on embodiment. It is sectional drawing which shows the structure of the flat electronic cassette which concerns on embodiment. It is a block diagram which shows the principal part structure of the electric system of the electronic cassette concerning embodiment. It is a perspective view which shows the laminated structure of two radiation detectors concerning an embodiment, a gate line driver, and a signal processing part. It is a flowchart which shows the flow of a process of the image reading process program which concerns on 1st Embodiment. It is a perspective view which shows the structure of the electronic cassette which can be opened and closed which concerns on embodiment. It is a perspective view which shows the structure of the electronic cassette which can be opened and closed which concerns on embodiment. It is sectional drawing which shows the structure of the electronic cassette which can be opened and closed which concerns on embodiment. It is a perspective view which shows the structure of the electronic cassette which can be reversed which concerns on embodiment. It is a perspective view which shows the structure of the electronic cassette which can be reversed which concerns on embodiment. It is sectional drawing which shows the structure of the electronic cassette which can be reversed which concerns on embodiment. It is a top view which shows the pixel arrangement | sequence of the two radiation detectors concerning 2nd Embodiment. It is a flowchart which shows the flow of a process of the image reading process program which concerns on 2nd Embodiment. It is the figure which showed typically the complementation process which concerns on 2nd Embodiment. It is sectional drawing which shows the other structure of the imaging | photography part which concerns on embodiment. It is sectional drawing which shows the other structure of the imaging | photography part which concerns on embodiment. It is sectional drawing which shows the other structure of the imaging | photography part which concerns on embodiment. It is sectional drawing which shows the other structure of the imaging | photography part which concerns on embodiment. It is a graph which shows the relationship between the cumulative exposure amount of CsI, and a sensitivity. (A) is sectional drawing which shows the cross-sectional structure in the accommodation state of the electronic cassette which can be opened and closed which concerns on another form, (B) is the cross-sectional structure in the expansion | deployment state of the electronic cassette which can be opened and closed which concerns on another form It is sectional drawing shown. It is a graph which shows an example of the sensitivity change of the scintillator layer formed with CsI.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of the radiation detector 20 according to the present embodiment will be described.

  FIG. 1 is a cross-sectional view schematically showing the configuration of the radiation detector 20 according to the present embodiment, and FIG. 2 is a plan view showing the configuration of the radiation detector 20. .

  As shown in FIG. 1, the radiation detector 20 includes a TFT substrate 26 in which a switch element 24 such as a thin film transistor (TFT) is formed on an insulating substrate 22.

  On the TFT substrate 26, a scintillator layer 28 that converts incident radiation into light is formed as an example of a radiation conversion layer that converts incident radiation.

As the scintillator layer 28, for example, CsI: Tl, GOS (Gd ₂ O ₂ S: Tb) can be used. The scintillator layer 28 is not limited to these materials.

  The wavelength range of light emitted by the scintillator layer 28 is preferably a visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 20, a green wavelength range is included. It is more preferable.

  Specifically, the phosphor used in the scintillator layer 28 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and the emission spectrum upon irradiation with X-rays is 420 nm to 600 nm. It is particularly preferred to use some CsI (Tl). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

  The scintillator layer 28 may be formed by vapor deposition on a vapor deposition substrate, for example, when it is intended to be formed of columnar crystals such as CsI (Tl). Thus, when the scintillator layer 28 is formed by vapor deposition, an Al plate is often used as the vapor deposition substrate from the viewpoint of X-ray transmittance and cost, but is not limited thereto. When GOS is used as the scintillator layer 28, the scintillator layer 28 may be formed by applying GOS to the surface of the TFT substrate 26 without using a vapor deposition substrate.

  Any insulating substrate 22 may be used as long as it has optical transparency and low radiation absorption. For example, a glass substrate, a transparent ceramic substrate, or an optically transparent resin substrate can be used. The insulating substrate 22 is not limited to these materials.

  Between the scintillator layer 28 and the TFT substrate 26, a photoconductive layer 30 that generates charges when light converted by the scintillator layer 28 is incident is disposed. A bias electrode 32 for applying a bias voltage to the photoconductive layer 30 is formed on the surface of the photoconductive layer 30 on the scintillator layer 28 side.

  The photoconductive layer 30 absorbs light emitted from the scintillator layer 28 and generates a charge corresponding to the absorbed light. The photoconductive layer 30 may be formed of a material that generates charges when irradiated with light. For example, the photoconductive layer 30 may be formed of amorphous silicon, an organic photoelectric conversion material, or the like. The photoconductive layer 30 containing amorphous silicon has a wide absorption spectrum and can absorb light emitted by the scintillator layer 28. If the photoconductive layer 30 includes an organic photoelectric conversion material, it has a sharp absorption spectrum in the visible region, and electromagnetic waves other than light emitted by the scintillator layer 28 are hardly absorbed by the photoconductive layer 30, such as X-rays. Noise generated when radiation is absorbed by the photoconductive layer 30 can be effectively suppressed.

  The organic photoelectric conversion material constituting the photoconductive layer 30 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator layer 28 in order to absorb light emitted by the scintillator layer 28 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator layer 28, but if the difference between the two is small, the light emitted from the scintillator layer 28 can be sufficiently absorbed. It is. Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator layer 28 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of organic photoelectric conversion materials that can satisfy such conditions include quinacridone-based organic compounds and phthalocyanine-based organic compounds. For example, since the absorption peak wavelength of quinacridone in the visible region is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator layer 28, the difference in the peak wavelength may be within 5 nm. The amount of charge generated in the photoconductive layer 30 can be substantially maximized.

  On the TFT substrate 26, a charge collecting electrode 34 for collecting charges generated in the photoconductive layer 30 is formed. In the TFT substrate 26, the charges collected by the charge collection electrodes 34 are read out by the switch element 24.

  Next, the photoconductive layer 30 applicable to the radiation detector 20 according to the present embodiment will be specifically described.

  The electromagnetic wave absorption / photoelectric conversion site in the radiation detector 20 according to the present invention includes a pair of charge collection electrode 34 and bias electrode 32, and a photoconductive layer 30 sandwiched between the charge collection electrode 34 and bias electrode 32. It can be comprised by the organic layer to contain. More specifically, this organic layer is a part that absorbs electromagnetic waves, a photoelectric conversion part, an electron transport part, a hole transport part, an electron blocking part, a hole blocking part, a crystallization preventing part, an electrode, and an interlayer contact improvement. It can be formed by stacking or mixing parts.

  The organic layer preferably contains an organic p-type compound or an organic n-type compound.

  The organic p-type semiconductor (compound) is a donor organic semiconductor (compound) mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound.

  An organic n-type semiconductor (compound) is an acceptor organic semiconductor (compound) mainly represented by an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound.

  Since the materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoconductive layer 30 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted. The photoconductive layer 30 may be formed by further containing fullerenes or carbon nanotubes.

  The sensor unit 36 constituting each pixel unit only needs to include at least the charge collection electrode 34, the photoconductive layer 30, and the bias electrode 32. In order to suppress an increase in dark current, an electron blocking film and a hole blocking unit are included. It is preferable to provide at least one of the films, and it is more preferable to provide both.

  The electron blocking film can be provided between the charge collection electrode 34 and the photoconductive layer 30, and when a bias voltage is applied between the charge collection electrode 34 and the bias electrode 32, the charge collection electrode 34 to the photoconductive layer 30. It is possible to prevent the dark current from being increased due to the injection of electrons.

  An electron donating organic material can be used for the electron blocking film.

  The material actually used for the electron blocking film may be selected according to the material of the adjacent electrode, the material of the adjacent photoconductive layer 30 and the like, and the electron function is 1.3 eV or more from the work function (Wf) of the adjacent electrode material. Those having a large affinity (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoconductive layer 30 are preferable. Since the material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The thickness of the electron blocking film is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably 50 nm, in order to surely exhibit the dark current suppressing effect and prevent a decrease in the photoelectric conversion efficiency of the sensor unit 36. It is 100 nm or less.

  The hole blocking film can be provided between the photoconductive layer 30 and the bias electrode 32. When a bias voltage is applied between the charge collecting electrode 34 and the bias electrode 32, the hole blocking film is applied from the bias electrode 32 to the photoconductive layer 30. It is possible to suppress the increase in dark current due to the injection of holes.

  An electron-accepting organic material can be used for the hole blocking film.

  The thickness of the hole blocking film is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, particularly preferably, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 36. It is 50 nm or more and 100 nm or less.

  The material actually used for the hole blocking film may be selected according to the material of the adjacent electrode, the material of the adjacent photoconductive layer 30 and the like, and 1.3 eV or more from the work function (Wf) of the material of the adjacent electrode. A material having a large ionization potential (Ip) and an Ea equivalent to or larger than the electron affinity (Ea) of the material of the adjacent photoconductive layer 30 is preferable. Since the material applicable as the electron-accepting organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  In the case where the bias voltage is set so that the holes move to the bias electrode 32 and the electrons move to the charge collecting electrode 34 among the charges generated in the photoconductive layer 30, the electron blocking film and the hole blocking are set. What is necessary is just to reverse the position of a film | membrane. Moreover, it is not necessary to provide both the electron blocking film and the hole blocking film. If either one is provided, a certain degree of dark current suppressing effect can be obtained.

  FIG. 3 schematically shows the configuration of the switching element 24.

  On the TFT substrate 26, a switching element 24 is formed corresponding to the charge collection electrode 34, which converts the electric charge moved to the charge collection electrode 34 into an electric signal and outputs it. The region where the switching element 24 is formed has a portion that overlaps the charge collection electrode 34 in plan view. With such a configuration, the switching element 24 and the sensor unit 36 in each pixel portion have a thickness. There will be overlap in the direction. In order to minimize the plane area of the radiation detector 20 (pixel portion), it is desirable that the region where the switching element 24 is formed is completely covered by the charge collection electrode 34.

  In the switching element 24, a gate electrode 220, a gate insulating film 222, and an active layer (channel layer) 224 are stacked, and a source electrode 226 and a drain electrode 228 are formed on the active layer 224 at a predetermined interval. Yes.

  The drain electrode 228 is electrically connected to the corresponding charge collection electrode 34 through a wiring made of a conductive material formed through an insulating film 219 provided between the insulating substrate 22 and the charge collection electrode 34. Has been. Thereby, the charges collected by the charge collection electrode 34 can be moved to the switching element 24.

  The active layer 224 can be formed of, for example, amorphous silicon, amorphous oxide, organic semiconductor material, carbon nanotube, or the like. Note that the material forming the active layer 224 is not limited thereto.

The amorphous oxide that can form the active layer 224 is preferably an oxide containing at least one of In, Ga, and Zn (for example, In—O-based), and at least two of In, Ga, and Zn. Oxides containing one (for example, In—Zn—O, In—Ga—O, and Ga—Zn—O) are more preferable, and oxides including In, Ga, and Zn are particularly preferable. As the In—Ga—Zn—O-based amorphous oxide, an amorphous oxide whose composition in a crystalline state is represented by InGaO ₃ (ZnO) _m (m is a natural number less than 6) is preferable, and InGaZnO is particularly preferable. ₄ is more preferable. Note that the amorphous oxide that can form the active layer 224 is not limited thereto.

  Examples of the organic semiconductor material that can form the active layer 224 include, but are not limited to, phthalocyanine compounds, pentacene, vanadyl phthalocyanine, and the like. In addition, about the structure of a phthalocyanine compound, since it is demonstrated in detail in Unexamined-Japanese-Patent No. 2009-212389, description is abbreviate | omitted.

  If the active layer 224 of the switching element 24 is formed of an amorphous oxide, an organic semiconductor material, or a carbon nanotube, the radiation such as X-rays is not absorbed, or even if it is absorbed, a very small amount remains. Generation of noise in the element 24 can be effectively suppressed.

  Further, when the active layer 224 is formed of carbon nanotubes, the switching speed of the switching element 24 can be increased, and the switching element 24 having a low degree of light absorption in the visible light region can be formed. When the active layer 224 is formed of carbon nanotubes, the performance of the switching element 24 is remarkably deteriorated only by mixing a very small amount of metallic impurities into the active layer 224. Therefore, the carbon nanotubes of extremely high purity can be obtained by centrifugation or the like. Need to be separated and extracted.

  Here, any of the above-described amorphous oxide, organic semiconductor material, carbon nanotube, and organic photoelectric conversion material can be formed at a low temperature. Therefore, the insulating substrate 22 is not limited to a highly heat-resistant substrate such as a semiconductor substrate, a quartz substrate, and a glass substrate, and a flexible substrate such as plastic, aramid, or bionanofiber can also be used. Specifically, flexible materials such as polyesters such as polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), etc. A conductive substrate can be used. If such a plastic flexible substrate is used, it is possible to reduce the weight, which is advantageous for carrying around, for example.

  Further, the substrate 22 is provided with an insulating layer for ensuring insulation, a gas barrier layer for preventing permeation of moisture and oxygen, an undercoat layer for improving flatness or adhesion to electrodes, and the like. May be.

  Since aramid can be applied at a high temperature process of 200 ° C. or more, the transparent electrode material can be cured at a high temperature to reduce the resistance, and can also be used for automatic mounting of a driver IC including a solder reflow process. Moreover, since aramid has a thermal expansion coefficient close to that of ITO (indium tin oxide) or a glass substrate, warping after production is small and it is difficult to crack. In addition, aramid can form a substrate thinner than a glass substrate or the like. The insulating substrate 22 may be formed by laminating an ultrathin glass substrate and aramid.

  Bionanofiber is a composite of cellulose microfibril bundles (bacterial cellulose) produced by bacteria (Acetobacter Xylinum) and a transparent resin. The cellulose microfibril bundle has a width of 50 nm and a size of 1/10 of the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. By impregnating and curing a transparent resin such as an acrylic resin or an epoxy resin in bacterial cellulose, a bio-nanofiber having a light transmittance of about 90% at a wavelength of 500 nm can be obtained while containing 60-70% of the fiber. Bionanofiber has a low coefficient of thermal expansion (3-7ppm) comparable to silicon crystals, and is as strong as steel (460MPa), highly elastic (30GPa), and flexible, compared to glass substrates, etc. A thin insulating substrate 22 can be formed.

  In the present embodiment, the switching element 24, the sensor unit 36, and the transparent planarization layer 38 are sequentially formed on the insulating substrate 22, and an adhesive resin having a low light absorption property or the like is used on the insulating substrate 22. The radiation detector 20 is formed by attaching the scintillator layer 28 with the adhesive layer 39. Hereinafter, the insulating substrate 22 formed up to the planarizing layer 38 is referred to as a TFT substrate 26.

  As shown in FIG. 2, the TFT substrate 26 includes a bias electrode 32, a photoconductive layer 30, and a charge collection electrode 34. The sensor unit 36 functions as a photodiode that generates charges when light is incident thereon. The switch element 24 for reading out the electric charge accumulated in the sensor unit 36 includes two pixels 37 in a certain direction (row direction in FIG. 2) and a crossing direction with respect to the certain direction (column direction in FIG. 2). A plurality of dimensions are provided.

  The TFT substrate 26 has a plurality of gate wirings 40 extending in a certain direction (row direction) for turning on / off each switch element 24, and an on-state switch element extending in the crossing direction (column direction). A plurality of data wirings 42 are provided for reading out charges through 24.

  A flattening layer 38 (see FIG. 1) for flattening the TFT substrate 26 is formed on the TFT substrate 26. An adhesive layer 39 for bonding the scintillator layer 28 to the TFT substrate 26 is formed between the TFT substrate 26 and the scintillator layer 28 and on the planarizing layer 38.

  The TFT substrate 26 is flat and has a quadrilateral shape having four sides on the outer edge in plan view. Specifically, it is formed in a rectangular shape.

  Here, as shown in FIG. 4, the radiation detector 20 is irradiated with radiation from the front side to which the scintillator layer 28 is bonded (also referred to as front side irradiation, back side reading method (so-called PSS (Penetration Side Sampling) method)). Alternatively, radiation may be applied from the TFT substrate 26 side (back side) (backside irradiation, surface reading method (also referred to as so-called ISS (Irradiation Side Sampling) method)), and the radiation detector 20 is irradiated with radiation from the front side. In this case, when light is emitted more strongly on the upper surface side (opposite side of the TFT substrate 26) of the scintillator layer 28 and radiation is irradiated from the back side, the radiation transmitted through the TFT substrate 26 enters the scintillator layer 28 and enters the scintillator layer 28. The TFT substrate 26 side emits light more intensely, and each photoconductive layer 30 is charged by the light generated in the scintillator layer 28. Therefore, radiation is generated. The ejector 20 can be designed with high sensitivity to radiation because radiation does not pass through the TFT substrate 26 when radiation is irradiated from the front side compared to when radiation is irradiated from the back side. Moreover, since the light emission position of the scintillator layer 28 with respect to each photoconductive layer 30 is closer when the radiation is irradiated from the back side than when the radiation is irradiated from the front side, the resolution of the radiographic image obtained by imaging is higher.

  FIG. 5 shows an example of changes in the thickness and sensitivity of the scintillator layer 28 when the radiation detector 20 is irradiated with radiation on the front surface and when the radiation detector 20 is irradiated with back radiation. FIG. 6 shows changes in the thickness and MTF (Modulation Transfer Factor) of the scintillator layer 28 when the radiation detector 20 is irradiated with radiation from the front surface and when the radiation detector 20 is irradiated with radiation from the back surface. An example is shown.

  Next, the configuration of the imaging unit 21 that captures radiographic images will be described.

  The imaging unit 21 according to the present embodiment has two imaging systems that capture radiographic images indicated by the irradiated radiation, and can individually read image information indicating the radiographic images captured by each imaging system It is configured as follows.

  Specifically, as shown in FIG. 7, the two radiation detectors 20 (20A and 20B) are arranged so that the scintillator layer 28 is positioned on the upper and lower surfaces of the light shielding plate 27 that transmits radiation and shields light. is doing. Hereinafter, when distinguishing the scintillator layer 28 and the TFT substrate 26 of the two radiation detectors 20A and 20B, the scintillator layer 28 and the TFT substrate 26 of the radiation detector 20A are denoted by reference symbol A, and the scintillator layer 28 of the radiation detector 20B. The TFT substrate 26 will be described with reference numeral B.

  Thus, by providing the scintillator layer 28A and the TFT substrate 26A in this order on one surface of the light shielding plate 27, the radiation detector 20A is irradiated with radiation from one surface side, and the other side of the light shielding plate 27 is exposed. By providing the scintillator layer 28B and the TFT substrate 26B in this order on the surface, radiation irradiation from the other surface side of the radiation detector 20B becomes back surface irradiation. Further, by providing the light shielding plate 27 between the two radiation detectors 20A and 20B, the light generated in the scintillator layer 28A is not transmitted to the scintillator layer 28B side, and the light generated in the scintillator layer 28B is not generated. Does not penetrate to the side.

  Here, as described above, the light emission characteristics of the scintillator layer 28 change depending on the thickness as shown in FIGS.

  The thicker the scintillator layer 28, the more light is emitted and the higher the sensitivity, but the image quality is degraded by light scattering or the like.

  Therefore, by setting the thickness of the scintillator layers 28A and 28B to be the scintillator layer 28B> the scintillator layer 28A, the scintillator layer 28A side can be focused on image quality, and the scintillator layer 28B side can be focused on sensitivity. If the scintillator layer 28 is less than 50 μm, an output for X-rays cannot be sufficiently obtained. In the case of surface irradiation, if it exceeds 300 μm, the reflected light will be scattered and absorbed in the scintillator layer 28, so that it will come out on the surface. The amount of light coming in tends to be insufficient. When used for surface irradiation, the scintillator layer 28 preferably has a thickness in the range of 50 to 300 μm, and more preferably in the range of 100 to 250 μm.

  The scintillator layer 28 is filled in the scintillator layer 28, and the larger the particle size of the particles that emit light when irradiated with radiation, the greater the amount of light emission and the higher the sensitivity. Since the particles that are present affect adjacent pixels, the image quality is degraded.

  Therefore, by setting the particle size of the scintillator layers 28A and 28B to scintillator layer 28B> scintillator layer 28A, the scintillator layer 28A side can be focused on image quality, and the scintillator layer 28B side can be focused on sensitivity.

  Further, the scintillator layer 28 can have a multilayer structure of small particles and large particles. For example, as shown in FIG. 8, the scintillator layer 28 has a small particle region 25A on the irradiation side and a large particle region 25B on the TFT substrate 26 side. It is difficult for the oblique component of the light to reach the TFT substrate 26, and the sensitivity is lowered. In addition, the sensitivity is increased by changing the ratio of the region 25A and the region 25B to increase the large particle layer relative to the small particle layer, but the image quality deteriorates because light scattering affects the adjacent pixels. To do.

  Therefore, by changing the layered structure of the particles of the scintillator layers 28A and 28B, the scintillator layer 28A side can be focused on image quality, and the scintillator layer 28B side can be focused on sensitivity.

  Further, the scintillator layer 28 has higher sensitivity as the filling rate is higher, but light scattering increases and image quality is degraded. Here, the filling rate is a value obtained by dividing the total volume of particles of the scintillator layer 28 / the volume of the scintillator layer 28 × 100. In addition, since the scintillator layer 28 is difficult to manufacture when handling powder and the filling rate exceeds 80%, the filling rate is preferably 50 to 80% by volume.

  Therefore, by setting the particle filling rate of the scintillator layers 28A and 28B to scintillator layer 28B> scintillator layer 28A, the scintillator layer 28A side can be focused on image quality, and the scintillator layer 28B side can be focused on sensitivity.

  In addition, the scintillator layer 28 changes in light emission characteristics depending on the amount of activator doped, and the amount of light emitted tends to increase as the amount of activator doped increases, but the amount of light scattering increases and image quality deteriorates. .

  Therefore, by setting the scintillator layers 28A and 28B to have an activator doping amount of scintillator layer 28B> scintillator layer 28A, the scintillator layer 28A side can be focused on image quality, and the scintillator layer 28B side can be focused on sensitivity.

  Further, the scintillator layer 28 has different emission characteristics with respect to radiation by changing the material used.

  For example, when the scintillator layer 28A is formed of GOS and the scintillator layer 28B is formed of CsI: Tl, the scintillator layer 28A is focused on sensitivity, and the scintillator layer 28B is focused on image quality.

  Further, the scintillator layer 28 has a flat or columnar layer structure, and thus has different emission characteristics with respect to radiation.

  For example, when the scintillator layer 28A has a flat layer structure and the scintillator layer 28B has a columnar separation layer structure, the scintillator layer 28A is focused on sensitivity, and the scintillator layer 28B is focused on image quality.

  Further, as shown in FIG. 9, by forming a reflective layer 29 that transmits X-rays and reflects visible light on the surface of the scintillator layer 28 opposite to the TFT substrate 26, the generated light is more efficiently generated. Since it can be led to the TFT substrate 26, the sensitivity is improved. The reflective layer may be provided by any of sputtering, vapor deposition, and coating methods. The reflective layer 29 is preferably a material that is highly reflective in the emission wavelength region of the scintillator layer 28 to be used, such as Au, Ag, Cu, Al, Ni, Ti. For example, when the scintillator layer 28 is GOS: Tb, Ag, Al, Cu or the like having a high reflectance at a wavelength of 400 to 600 nm is preferable, and the reflectance is not obtained when the thickness is less than 0.01 μm, and the thickness exceeds 3 μm. However, since a further effect is not acquired by the improvement of a reflectance, 0.01-3 micrometers is preferable.

  Here, the scintillator layer 28 is formed by combining particle diameter, particle multilayer structure, particle filling rate, activator dope amount, material, layer structure change, and formation of the reflective layer 29. Needless to say, the characteristics can be different.

  Further, the TFT substrates 26A and 26B can be made by changing the material of the photoconductive layer 30, or by forming a filter between the TFT substrate 26A and the scintillator layer 28A, between the TFT substrate 26B and the scintillator layer 28B, And the TFT substrate 26B, the light receiving area of the photoconductive layer 30 functioning as a photodiode is changed so that the light receiving area is wider than the side where the image quality is emphasized on the side where the sensitivity is important, or the pixel between the TFT substrate 26A and the TFT substrate 26B. The light receiving characteristics of the TFT substrates 26A and 26B with respect to the light are changed by changing the pitch so that the pixel pitch is narrower than the sensitivity-oriented side or by changing the signal reading characteristics of the TFT substrates 26A and 26B. be able to.

  In the present embodiment, the thickness of the scintillator layers 28A and 28B, the particle size of the particles, the particle multilayer structure, the particle filling rate, the dope amount of the activator, the material and the layer structure are changed, or the reflective layer 29 is formed. Or a filter is formed between the TFT substrate 26A and the scintillator layer 28, and between the TFT substrate 26B and the scintillator layer 28, or the photoconductive layer 30 that functions as a photodiode is received by the TFT substrate 26A and the TFT substrate 26B. Change the area to make the light receiving area wider on the side that emphasizes the sensitivity than the side that emphasizes the image quality, or change the pixel pitch between the TFT substrate 26A and the TFT substrate 26B and on the side that emphasizes the image quality on the pixel pitch side. Also, the characteristics of the radiographic images taken by the radiation detectors 20A and 20B are made different.

  Specifically, the radiation detector 20A is focused on image quality, and the radiation detector 20B is focused on sensitivity.

  Next, the configuration of the electronic cassette 10 incorporating such a photographing unit 21 will be described.

  FIG. 10 is a perspective view showing the configuration of the electronic cassette 10, and FIG. 11 is a cross-sectional view of the electronic cassette 10.

  The electronic cassette 10 includes a flat housing 18 made of a material that transmits the radiation X, and has a waterproof and airtight structure. The above-described photographing unit 21 is disposed inside the housing 18. The housing 18 has imaging regions 18A and 18B to which radiation is irradiated during imaging, in areas corresponding to the positions where the imaging unit 21 is provided on one flat surface and the other surface. An imaging unit 21 is built in the housing 18 so that the radiation detector 20A is on the imaging area 18A side with the light shielding plate 27 interposed therebetween. The imaging area 18A is an imaging area in which image quality is important, and an imaging area 18B. It is a shooting area that emphasizes sensitivity.

  In addition, a case 31 that accommodates a control unit 50 and a power supply unit 70 described later is disposed at one end inside the housing 18 at a position that does not overlap the radiation detector 20 (outside the range of the imaging regions 18A and 18B). ing. Here, since the electronic cassette 10 can capture radiographic images on both sides of the imaging regions 18A and 18B, a member that affects the radiographic image such as a circuit or an element is not arranged in the imaging regions 18A and 18B. Yes.

  Further, the electronic cassette 10 is provided with an operation panel 19 having various buttons on the side surface of the housing 18.

  FIG. 12 is a block diagram showing the main configuration of the electrical system of the electronic cassette 10.

  In the radiation detectors 20A and 20B, gate line drivers 52A and 52B are arranged on one side of two adjacent sides, and signal processing units 54A and 54B are arranged on the other side. The individual gate lines 40 of the radiation detector 20A are connected to the gate line driver 52A, the individual data lines 42 of the radiation detector 20A are connected to the signal processing unit 54A, and the individual gate lines 40 of the radiation detector 20B. Are connected to the gate line driver 52B, and the individual data lines 42 of the radiation detector 20B are connected to the signal processing unit 54B.

  Since the gate line drivers 52A and 52B and the signal processing units 54A and 54B generate heat, as shown in FIG. 13, when the radiation detectors 20A and 20B are stacked, one of the gate line drivers 52A and 52B rotates with respect to the other. It is preferable to arrange the line driver 52A and the gate line driver 52B, and the signal processing unit 54A and the signal processing unit 54B so as not to overlap with each other to suppress the influence of heat.

  Further, inside the housing 18, an image memory 56, a cassette control unit 58, and a wireless communication unit 60 are provided as the control unit 50.

  The switch elements 24 of the TFT substrates 26A and 26B are sequentially turned on in units of rows by signals supplied from the gate line drivers 52A and 52B via the gate wiring 40, and read by the switch elements 24 that are turned on. The electric charge is transmitted as an electric signal through the data wiring 42 and input to the signal processing units 54A and 54B. As a result, the charges are sequentially read out in units of rows, and a two-dimensional radiation image can be acquired.

  Although not shown, the signal processing units 54A and 54B are each provided with an amplification circuit and a sample hold circuit for amplifying an input electric signal for each data wiring 42, and are transmitted through the individual data wirings 42. The electric signal is amplified by the amplifier circuit and then held in the sample hold circuit. Further, a multiplexer and an A / D (analog / digital) converter are connected in order to the output side of the sample and hold circuit, and the electric signals held in the individual sample and hold circuits are sequentially (serially) input to the multiplexer. The digital image data is converted by an A / D converter.

  An image memory 56 is connected to the signal processing units 54A and 54B, and image data output from the A / D converters of the signal processing units 54A and 54B are stored in the image memory 56 in order. The image memory 56 has a storage capacity capable of storing a predetermined number of image data, and image data obtained by imaging is sequentially stored in the image memory 56 each time a radiographic image is captured.

  The image memory 56 is connected to the cassette control unit 58. The cassette control unit 58 is constituted by a microcomputer, and includes a CPU (central processing unit) 58A, a memory 58B including a ROM and a RAM, a nonvolatile storage unit 58C including a flash memory, and the like, and operates the electronic cassette 10 as a whole. Control.

  A wireless communication unit 60 is connected to the cassette control unit 58. The wireless communication unit 60 corresponds to a wireless local area network (LAN) standard represented by IEEE (Institute of Electrical and Electronics Engineers) 802.11a / b / g, etc. Control transmission of various information. The cassette control unit 58 can wirelessly communicate with an external device that controls the entire radiographic imaging such as a console via the wireless communication unit 60, and can transmit and receive various types of information to and from the console. .

  The cassette control unit 58 individually controls the operation of the gate line drivers 52A and 52B, and can individually control reading of image information indicating a radiation image from the radiation detectors 20A and 20B. The cassette control unit 58 stores various information such as imaging conditions received from the console via the wireless communication unit 60, and controls the gate line drivers 52A and 52B based on the imaging conditions to control the radiation detectors 20A and 20B. Read the image.

  In addition, the operation control unit 19 is connected to the cassette control unit 58, and the operation content for the operation panel 19 can be grasped.

  Further, the electronic cassette 10 is provided with a power supply unit 70, and the various circuits and elements described above (the operation panel 19, gate line drivers 52A and 52B, signal processing units 54A and 54B, an image memory 56, a wireless communication unit). 60 and the microcomputer functioning as the cassette control unit 58 are operated by the electric power supplied from the power supply unit 70. The power supply unit 70 incorporates a battery (a rechargeable secondary battery) so as not to impair the portability of the electronic cassette 10, and supplies power from the charged battery to various circuits and elements. In FIG. 12, wiring for connecting the power supply unit 70 to various circuits and elements is omitted.

  Next, the operation of the electronic cassette 10 according to the present exemplary embodiment will be described.

  The electronic cassette 10 according to the present embodiment is capable of imaging with only one of the radiation detectors 20A and 20B and imaging with both of the radiation detectors 20A and 20B when imaging a radiographic image. .

  In addition, when the radiation detectors 20A and 20B are both photographed, it is possible to generate an energy subtraction image by performing image processing that weights and adds the radiation images photographed by the radiation detectors 20A and 20B for each corresponding pixel. Has been.

  In addition, the electronic cassette 10 is capable of individually storing image information indicating the radiation images captured by the radiation detectors 20A and 20B and image information of the generated energy subtraction image.

  When the radiographer captures a radiographic image, the radiographer designates, as a captured image, any of image quality emphasis, sensitivity emphasis, and energy subtraction image depending on the application. In addition, when the photographer designates an energy subtraction image as a photographed image, the photographer designates execution or non-execution of image processing for generating an energy subtraction image in the electronic cassette 10 with respect to the console. Further, the photographer instructs the console to execute or not save the image information captured in the electronic cassette 10.

  The console transmits to the electronic cassette 10 the processing conditions that are the execution and non-execution of the image processing for generating the specified captured image and energy subtraction image, and the execution and non-execution of storing the image information.

  The electronic cassette 10 stores the transmitted processing conditions in the storage unit 58C.

  The electronic cassette 10 is provided with an imaging area 18A emphasizing image quality and an imaging area 18B emphasizing sensitivity, and by inverting the whole, radiographic images can be captured in the imaging area 18A or the imaging area 18B.

  The electronic cassette 10 generates radiation as shown in FIG. 11 with the imaging region 18A up when taking image quality and energy subtraction images, and with the imaging region 18B up when taking sensitivity. The radiation generator 80 is arranged at a distance from each other, and the imaging target region B of the patient is arranged on the imaging region. The radiation generation apparatus 80 emits radiation having a radiation dose according to imaging conditions given in advance. The radiation X emitted from the radiation generator 80 is irradiated to the electronic cassette 10 after carrying image information by passing through the imaging target region B.

  The radiation X irradiated from the radiation generator 80 reaches the electronic cassette 10 after passing through the imaging target region B. As a result, charges corresponding to the dose of the irradiated radiation X are collected and accumulated in each charge collecting electrode 34 of the radiation detector 20 incorporated in the electronic cassette 10.

  The cassette control unit 58 performs an image reading process for reading an image in accordance with the processing conditions stored in the storage unit 58C after the irradiation with the radiation X is completed.

  FIG. 14 shows a flowchart showing the flow of the image reading processing program executed by the CPU 58A. The program is stored in advance in a predetermined area of the ROM of the memory 58B.

  In step S10, it is determined whether or not the captured image specified as the processing condition is focused on image quality. If the determination is affirmative, the process proceeds to step S12. If the determination is negative, the process proceeds to step S14.

  In step S12, the gate line driver 52A is controlled, and an ON signal is sequentially output from the gate line driver 52A to each gate wiring 40 of the radiation detector 20A, which is a quality-oriented characteristic, to read image information. The image information read from the radiation detector 20A is stored in the image memory 56.

  On the other hand, in step S14, it is determined whether or not the captured image specified as the processing condition is sensitive. If the determination is affirmative, the process proceeds to step S16. If the determination is negative, the process proceeds to step S20. To do.

  In step S16, the gate line driver 52B is controlled, and an ON signal is sequentially output from the gate line driver 52B to each gate wiring 40 of the radiation detector 20B, which has sensitivity-sensitive characteristics, to read image information. The image information read from the radiation detector 20B is stored in the image memory 56.

  In step S18, the image information stored in the image memory 56 is transmitted to the console.

  As a result, the image information of the radiographic image captured by the radiation detector 20A with the image quality-oriented characteristic or the image information of the radiographic image captured by the radiation detector 20B with the sensitivity-oriented characteristic is transmitted to the console.

  On the other hand, in step S20, both the gate line drivers 52A and 52B are controlled on the assumption that the captured image specified as the processing condition is an energy subtraction image, and the gate wirings 40 of the radiation detectors 20A and 20B are sequentially turned on line by line. The image information is read out by outputting a signal. The image information read from the radiation detectors 20A and 20B is stored together in the image memory 56.

  In step S22, it is determined whether or not image processing for generating an energy subtraction image is specified as a processing condition. If the determination is affirmative, the process proceeds to step S24. If the determination is negative, step S28 is performed. Migrate to

  In step S24, an energy subtraction image is generated by performing weighted addition for each corresponding pixel of the radiation image with respect to the image information by the radiation detectors 20A and 20B stored in the image memory 56.

  In the next step S26, the image information of the generated energy subtraction image is transmitted to the console.

  On the other hand, in step S28, image information by the radiation detectors 20A and 20B stored in the image memory 56 is transmitted to the console. The console can generate an energy subtraction image by performing weighted addition for each corresponding pixel of the radiation image with respect to the transmitted image information by the radiation detectors 20A and 20B. Further, the console can also obtain image information of a radiographic image captured by the radiation detector 20A with characteristics emphasizing image quality and image information of a radiographic image captured by the radiation detector 20B with characteristics emphasizing sensitivity.

  In step S30, it is determined whether or not image information storage is designated as a processing condition. If the determination is affirmative, the process proceeds to step S32. If the determination is negative, the process ends.

  In step S32, the image information read in step S12, step S16 or step S20 is stored in the storage unit 58C in association with identification information for identifying image information.

  In step S34, the identification information associated with the image information in step S32 is transmitted to the console, and the process ends.

  The console stores the transmitted identification information, and transmits the identification information to the electronic cassette 10 when it is desired to read the image information stored in the electronic cassette 10.

  When receiving the identification information transmitted from the console, the electronic cassette 10 reads the image information of the identification information from the storage unit 58C and transmits it to the console.

  Thereby, the image information of the radiographic image image | photographed with the electronic cassette 10 can be obtained again.

  The electronic cassette 10 determines that the storage period for storing the image information in the storage unit 58C is, for example, until a predetermined period has elapsed or until the next shooting is performed, and can notify the console of the storage period. preferable.

  As described above, the electronic cassette 10 according to the present exemplary embodiment can capture a radiographic image that emphasizes image quality, a radiographic image that emphasizes sensitivity, and an energy subtraction image, and thus can be used for a plurality of applications.

  Note that the electronic cassette 10 according to the present exemplary embodiment is reversed in its entirety so as to enable photographing on both sides of the photographing region 18A or the photographing region 18B. However, the electronic cassette 10 as shown in FIGS. Examples of the configuration that can be made, and a configuration that enables a part of the electronic cassette 10 to be reversed as shown in FIGS.

  15 and 16 are perspective views showing other configurations of the electronic cassette 10, and FIG. 17 is a cross-sectional view showing a schematic configuration of the electronic cassette 10. Note that portions corresponding to those of the electronic cassette 10 (see FIGS. 10 to 11) are denoted by the same reference numerals, and description of portions having the same functions is omitted.

  The electronic cassette 10 includes the imaging unit 21, the gate line drivers 52A and 52B, the signal processing units 54 and 54B, and the like. The flat imaging unit 12 that captures a radiographic image of the irradiated radiation, and the control described above. The control unit 14 in which the unit 50 and the power supply unit 70 are incorporated is connected by a hinge 16 so as to be opened and closed.

  The photographing unit 12 and the control unit 14 are rotated in a state where the other of the photographing unit 12 and the control unit 14 is pivoted about the hinge 16 so that the photographing unit 12 and the control unit 14 are aligned (FIG. 16). 12 and the control unit 14 can be opened and closed in the storage state (FIG. 15) folded and overlapped.

  The electronic cassette 10 is provided with an operation panel 19 on the upper surface of the control unit 14.

  As shown in FIG. 17, the imaging unit 12 incorporates an imaging unit 21 so that the radiation detector 20B is on the control unit 14 side and the radiation detector 20A is on the outside (opposite side of the control unit 14 side). In the retracted state, the surface side that is on the outer side is an imaging region 18B that emphasizes sensitivity, and the surface side that faces the control unit 14 is an imaging region 18A that emphasizes image quality (FIG. 16).

  The imaging unit 21, the control unit 50, and the power supply unit 70 are connected by a connection wiring 44 provided in the hinge 16.

  As described above, the electronic cassette 10 can be easily opened and closed to capture radiographic images having different characteristics by performing imaging in the imaging region 18A or the imaging region 18B.

  18 and 19 are perspective views illustrating other configurations of the electronic cassette 10 according to the embodiment, and FIG. 20 is a cross-sectional view illustrating a schematic configuration of the electronic cassette 10. . Note that portions corresponding to those of the electronic cassette 10 (see FIGS. 10 to 17) are denoted by the same reference numerals, and description of portions having the same functions is omitted.

  The electronic cassette 10 includes the above-described imaging unit 21, gate line drivers 52A and 52B, and signal processing units 54 and 54B, and includes a flat imaging unit 12 that captures a radiographic image of irradiated radiation, and the above-described control unit. 50 and a control unit 14 having a built-in power supply unit 70 are rotatably connected by a rotating shaft 17.

  In addition, the photographing unit 12 is provided with photographing regions 18A and 18B on one surface and the other surface of the flat plate corresponding to the arrangement position of the photographing unit 21.

  The electronic cassette 10 is provided with an operation panel 19 on the upper surface of the control unit 14.

  The imaging unit 21 is built in such that the radiation detector 20B is on the imaging region 18B side, and the radiation detector 20A is on the imaging region 18A. The imaging region 18B is a sensitivity-sensitive imaging region, and the imaging region 18A is image quality. It is regarded as an important shooting area.

  The imaging unit 21, the control unit 50, and the power supply unit 70 are connected by a connection wiring 44 provided in the rotary shaft 17.

  The photographing unit 12 and the control unit 14 are rotated with respect to the other, whereby the photographing region 18A and the operation panel 19 are arranged (FIG. 18), and the photographing region 18B and the operation panel 19 are arranged. It can be changed to (FIG. 19).

  As described above, the electronic cassette 10 can be easily rotated to capture radiographic images having different characteristics by performing imaging in the imaging region 18A or the imaging region 18B.

[Second Embodiment]
Next, a second embodiment will be described.

  Since the configuration of the electronic cassette 10 according to the second embodiment is the same as that of the first embodiment (see FIGS. 1 to 4), only the different parts will be described here, and the description of the same parts will not be given. Omitted.

  As in the first embodiment, the imaging unit 21 according to the second embodiment causes the two radiation detectors 20A and 20B to face each other on the scintillator layer 28 side with the light shielding plate 27 interposed therebetween (see FIG. 7). Further, as shown in FIG. 21, the two-dimensionally provided pixels 37 are arranged by a half pitch of the intervals of the pixels 37 in a certain direction (row direction) and crossing direction (column direction) by the radiation detectors 20A and 20B. It arranges so that it may shift. In FIG. 21, the pixel array of the radiation detector 20A is indicated by a solid line, and the pixel array of the radiation detector 20B is indicated by a dotted line.

  In addition, the imaging unit 21 according to the second embodiment is configured so that the characteristics of the radiation images captured by the radiation detectors 20A and 20B are substantially the same when radiation is irradiated from the imaging region 18A side. The thicknesses of the scintillator layers 28A and 28B, the particle diameter, the particle multilayer structure, the particle filling rate, the activator dope amount, the material, the layer structure, and the like are adjusted.

  Next, the operation of the electronic cassette 10 according to the present exemplary embodiment will be described.

  The electronic cassette 10 according to the present embodiment is also capable of imaging with only one of the radiation detectors 20A and 20B and imaging with the radiation detectors 20A and 20B when capturing a radiation image.

  In addition, when imaging is performed with the radiation detectors 20A and 20B, it is possible to generate a high-resolution radiation image with an increased resolution by performing interpolation processing on the radiation images captured by the radiation detectors 20A and 20B, respectively. ing.

  In addition, the electronic cassette 10 can individually store image information indicating the radiation images captured by the radiation detectors 20A and 20B and image information of the generated high-resolution radiation image.

  The electronic cassette 10 according to the present exemplary embodiment is arranged with an imaging region 18A facing upward when taking a radiographic image, with a radiation generator 80 generating radiation as shown in FIG. A region B to be imaged by the patient is arranged on the region.

  When taking a radiographic image, the photographer designates either a standard image used for normal diagnosis or a high-resolution image used for precise examination as a taken image on the console according to the application. When the image condition is designated, the console transmits image condition information indicating the designated image condition to the electronic cassette 10. When the photographer designates a high-resolution image as a photographed image, the photographer designates whether or not to perform image processing for generating a high-resolution image on the electronic cassette 10 with respect to the console. Further, the photographer instructs the console to execute or not save the image information captured in the electronic cassette 10.

  The console transmits to the electronic cassette 10 as processing conditions the execution / non-execution of image processing for generating a specified captured image and high-resolution image, and the execution / non-execution of storing image information.

  The electronic cassette 10 stores the transmitted processing conditions in the storage unit 58C.

  FIG. 22 is a flowchart showing the flow of processing of the image reading processing program according to the second embodiment.

  In step S50, it is determined whether the captured image specified as the processing condition is a standard image. If the determination is affirmative, the process proceeds to step S52. If the determination is negative, the process proceeds to step S56.

  In step S52, the gate line driver 52A is controlled, and an ON signal is sequentially output from the gate line driver 52A to each gate wiring 40 of the radiation detector 20A, which is an image quality-oriented characteristic, to read image information. The image information read from the radiation detector 20A is stored in the image memory 56.

  In step S54, the image information stored in the image memory 56 is transmitted to the console.

  Thereby, the image information of the radiographic image image | photographed with 20 A of radiation detectors is transmitted to a console.

  On the other hand, in step S56, both the gate line drivers 52A and 52B are controlled on the assumption that the captured image specified as the processing condition is a high resolution image, and the gate wirings 40 of the radiation detectors 20A and 20B are sequentially turned on line by line. The image information is read out by outputting a signal. The image information read from the radiation detectors 20A and 20B is stored together in the image memory 56.

  In step S58, it is determined whether or not image processing for generating a high-resolution image is designated as a processing condition. If the determination is affirmative, the process proceeds to step S60, and if the determination is negative, step S64 is performed. Migrate to

  In step S60, a high-resolution radiation image obtained by interpolating the pixel value of each pixel from the image information by the radiation detectors 20A and 20B stored in the image memory 56 on the assumption that the image interval of the radiation image is halved. Is generated.

  FIG. 23 shows an example of the interpolation process. In FIG. 23, the pixel array of the radiation image 90A captured by the radiation detector 20A is indicated by a solid line, the pixel array of the radiation image 90B captured by the radiation detector 20B is indicated by a dotted line, and the generated high resolution The pixel array of the radiation image 90C is indicated by a one-dot chain line.

  In the present embodiment, the arrays of the pixels 37 of the radiation detectors 20A and 20B are arranged so as to be shifted by a half pitch of the pixel interval in a certain direction (row direction) and crossing direction (column direction). For this reason, the pixel array (solid line) of the radiation image 90A and the pixel array (dotted line) of the radiation image 90B are shifted by a half pitch of the pixel interval. In the present embodiment, the region where the pixel 92A of the radiographic image 90A and the pixel 92B of the radiographic image 90B overlap is defined as the pixel 92C of the high-resolution radiographic image 90C, and a value obtained by averaging the pixel values of the pixels 92A and 92B is obtained. Image information of the radiation image is generated as the pixel value of the image C (C = (A + B) / 2).

  In step S62, the image information of the generated high-resolution radiation image is transmitted to the console.

  On the other hand, in step S64, the image information by the radiation detectors 20A and 20B stored in the image memory 56 is transmitted to the console. The console can generate a high-resolution radiation image by performing image processing for generating a high-resolution radiation image on the transmitted image information from the radiation detectors 20A and 20B. Moreover, the console can also obtain image information of the radiation image of the standard image by the radiation detector 20A20B.

  In step S66, it is determined whether or not image information storage is designated as a processing condition. If the determination is affirmative, the process proceeds to step S32. If the determination is negative, the process ends.

  In step S68, the image information read in step S52 or step S56 is stored in the storage unit 58C in association with identification information for identifying the image information.

  In step S70, the identification information associated with the image information in step S68 is transmitted to the console, and the process ends.

  As described above, the electronic cassette 10 according to the present exemplary embodiment can be used for a plurality of applications because it can capture radiographic images with different resolutions.

  Here, when an attempt is made to obtain a high-resolution radiation image with a single radiation detector 20, the pixel array of the radiation detector 20 needs to be miniaturized, resulting in a poor yield of the radiation detector 20.

  On the other hand, when a high-resolution radiation image is generated by the two radiation detectors 20A and 20B as in the present embodiment, the pixel array of the radiation detectors 20A and 20B does not need to be miniaturized, so the yield is high. good.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  The above embodiments do not limit the invention according to the claims (claims), and all the combinations of features described in the embodiments are essential for the solution means of the invention. Is not limited. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  In each of the above embodiments, the case where the electronic cassette 10 which is a portable radiation imaging apparatus is applied has been described. However, the present invention is not limited to this, and is applied to a stationary radiation imaging apparatus. May be.

  Further, in each of the above embodiments, as shown in FIG. 7, the imaging unit 21 detects two radiations so that the scintillator layers 28A and 28B face each other with a light shielding plate 27 that transmits radiation and shields light. Although the case where it was set as the structure which has arrange | positioned container 20A, 20B was demonstrated, it is not limited to this. For example, as shown in FIG. 24, the two radiation detectors 20A and 20B may be arranged so that the TFT substrates 26A and 26B face each other with the light shielding plate 27 interposed therebetween. In addition, for example, as shown in FIG. 25, the radiation detectors 20A and 20B may be stacked with the TFT substrate 26 and the scintillator layer 28 aligned. Further, for example, as shown in FIG. 26, the radiation detectors 20A and 20B may be laminated so that both are irradiated on the back surface, and as shown in FIG. 27, both the radiation detectors 20A and 20B are irradiated on the front surface. You may laminate | stack so that it may become.

  In each of the above-described embodiments, the case where the two radiation detectors 20A and 20B are arranged with the light shielding plate 27 that transmits radiation and shields the light is described. However, the present invention is not limited to this. is not. For example, when imaging is performed on both sides of the imaging regions 18A and 18B, the light shielding plate 27 may shield the radiation. Further, the radiation detectors 20A and 20B may be held by the light shielding plate 27 as the light shielding plate 27 having rigidity. When the light-shielding plate 27 is a light-shielding substrate having rigidity, each TFT can be formed on the light-shielding substrate, so that an insulating substrate (a glass layer in the actual product) on which a conventional TFT is formed becomes unnecessary. Since two insulating substrates can be eliminated, the weight can be reduced. In this case, since the flexible light emitting layer and the TFT can be provided on the light shielding substrate, for example, the TFT may be disposed between the light shielding substrate and the light emitting layer.

  In the second embodiment, the case where the pixel arrays of the radiation detectors 20A and 20B are shifted has been described. However, the present invention is not limited to this. For example, by matching the pixel arrays of the radiation detectors 20A and 20B and averaging the radiation images taken by the radiation detectors 20A and 20B with the corresponding pixels to generate a radiation image, noise included in the radiation image Can be reduced.

  In each of the above embodiments, the case where an image is not read out from a shooting system that is not used under the conditions specified by the shot image has been described. However, the present invention is not limited to this. For example, in the first embodiment, an image is read from the radiation detectors 20A and 20B regardless of whether the captured image specified as the processing condition is focused on image quality or sensitivity. If the captured image is focused on image quality, the radiation detector 20B is read. The image information read out from the image data is stored in the storage unit 58C without being transmitted, and if the captured image is sensitive, the image information read out from the radiation detector 20A is stored in the storage unit 58C without being transmitted, and the request from the console Thus, the image information stored in the storage unit 58C may be transmitted to the console.

  Further, in each of the above-described embodiments, a case has been described in which processing conditions for each imaging system of the imaging unit 21 are received by the wireless communication unit 60 by wireless communication from the console, but the present invention is not limited to this. For example, it may be accepted by an input from the operation panel 19.

  In each of the above embodiments, the image processing for generating a captured image and an energy subtraction image is performed or not performed, the image processing for generating a high-resolution image is performed or not performed, and the image information is stored or not performed. Although the case where it was set as processing conditions was demonstrated, it is not limited to this. For example, execution or non-execution of image information reading processing from each imaging system of the imaging unit 21 or implementation or non-execution of various other image processing on image information read from each imaging system, reading from each imaging system Execution / non-execution of the transmission processing of the image information that has been issued and the image information that has undergone image processing, and execution / non-execution of the storage processing of the image information read from each imaging system and the image information that has undergone image processing Good.

  By the way, as shown in FIG. 28, the sensitivity of CsI decreases as the cumulative exposure dose increases, and the sensitivity decreases when the CsI is maintained without being irradiated.

  For this reason, for example, as shown in FIGS. 7 and 24 to 27, the scintillator layers 28 </ b> A and 28 </ b> B of the imaging unit 21 having two scintillator layers 28 (28 </ b> A and 28 </ b> B) are CsI (for example, CsI: Tl columnar crystals). Form with. And this imaging | photography part 21 is built in the electronic cassette 10, and it comprises so that a radiographic image can be image | photographed by one side and the other side (imaging area | region 18A, 18B). In this case, the electronic cassette 10 detects the doses of radiation irradiated on one surface and the other surface, stores the cumulative exposure doses on the one surface and the other surface, and estimates them from the cumulative exposure doses. When the sensitivity of the scintillator layer 28 falls below a predetermined allowable sensitivity that affects the image quality of the radiographic image to be shot, photographing on the surface where the sensitivity of the scintillator layer 28 falls below the allowable sensitivity is prohibited. It is also possible to encourage shooting on the side surface. Detection of the dose of irradiated radiation may be performed by providing a sensor capable of detecting radiation inside the electronic cassette 10, or may be performed from the pixel value of each pixel of the captured radiation image. (For example, the cumulative value of the pixel values of all pixels is regarded as the dose of irradiated radiation). The prohibition of shooting when the sensitivity of the scintillator layer 28 is less than the allowable sensitivity may be notified to the photographer via an external device such as a console, and a display unit or the like is provided on the operation panel 19. The display may be performed.

  Also, CsI recovers quickly from the reduced sensitivity when stored in a high temperature environment. Moreover, CsI can suppress the fall of a sensitivity, the one where use environment temperature is high. For this reason, for example, as shown in FIGS. 7 and 24 to 27, one scintillator layer 28 </ b> A of the imaging unit 21 having two scintillator layers 28 (28 </ b> A and 28 </ b> B) is formed as CsI (for example, CsI: Tl columnar crystal). And the other scintillator layer 28B is formed of GOS. And this imaging part 21 is built in the electronic cassette 10 which can be opened and closed shown in FIGS. 15-17, and it comprises so that a radiographic image can be image | photographed by one side and the other side (imaging area | region 18A, 18B). In this case, the photographing unit 21 is preferably built in the photographing unit 12 so that the scintillator layer 28B is on the control unit 14 side and the scintillator layer 28A is on the outside (opposite side to the control unit 14 side) in the housed state.

  29A and 29B show a state in which, for example, the photographing unit 21 shown in FIG. 7 is built in the electronic cassette 10 that can be opened and closed shown in FIGS.

  In the electronic cassette 10, heat from the control unit 14 is easily transmitted to the photographing unit 12 in the housed state. For this reason, by disposing the scintillator layer 28A on the imaging region 18B side and using the scintillator layer 28A for imaging in the housed state (FIG. 29A), a decrease in sensitivity of the scintillator layer 28A is suppressed. On the other hand, the sensitivity of GOS hardly changes due to temperature change. For this reason, by arranging the scintillator layer 28B on the photographing region 18A side and using the scintillator layer 28B for photographing in the unfolded state (FIG. 29B), there is almost no change in image quality due to a change in sensitivity due to a temperature change.

  In addition, when the scintillator layer 28 is formed of CsI, a change in the sensitivity of the scintillator layer 28 is estimated from the accumulated exposure amount, and when the sensitivity of the scintillator layer 28 becomes lower than the allowable sensitivity, the temperature of the scintillator layer 28 is maintained high. The reduced sensitivity may be recovered quickly.

  FIG. 30 shows an example of sensitivity change of the scintillator layer 28A formed of CsI in the electronic cassette 10 having the configuration shown in FIGS. 29 (A) and 29 (B), for example.

  In the electronic cassette 10, the sensitivity of the scintillator layer 28A is reduced by performing imaging in the imaging region 18B on the first and second imaging days, and the scintillator layer is maintained in a state where no radiation is irradiated at night. The sensitivity of 28A is restored. In addition, the electronic cassette 10 is subjected to fluoroscopic imaging (moving image imaging) in which radiographic images are continuously captured in the imaging region 18B on the third day of imaging, and when the sensitivity of the scintillator layer 28A falls below the allowable sensitivity, Shooting in the shooting area 18B is prohibited, and shooting in the shooting area 18A or shooting with another electronic cassette 10 is encouraged.

  The change in sensitivity of the scintillator layer 28A on each shooting date is, for example, when calibration is performed to calibrate the apparatus state by first irradiating the electronic cassette 10 with a predetermined amount of radiation on each shooting date. FIG. 28 shows the sensitivity of the scintillator layer 28A detected at the time of calibration by detecting the sensitivity of the scintillator layer 28A during the calibration of the day, obtaining the cumulative exposure dose irradiated during each photographing day. As shown, the sensitivity of the scintillator layer 28A may be estimated as the sensitivity decreases as the cumulative exposure increases. Further, the sensitivity of the scintillator layer 28A may be estimated from the irradiation time when radiation is irradiated in imaging, the accumulated exposure dose, and the period maintained without irradiation.

  In addition, when the sensitivity of the scintillator layer 28A becomes less than the allowable sensitivity, the electronic cassette 10 generates heat at the control unit 14 at night, for example, and warms the photographing unit 12 by the heat of the control unit 14, and the temperature of the scintillator layer 28A. The sensitivity of the scintillator layer 28A, which has been lowered, is recovered quickly by maintaining a high value. In the case where the electronic cassette 10 is stored and stored in a storage device such as a cradle, the storage device may warm the electronic cassette 10 at night to keep the temperature of the scintillator layer 28A high.

  In addition, the configurations of the electronic cassette 10 and the radiation detector 20 described in the above embodiment are merely examples, and it is needless to say that the configurations can be appropriately changed without departing from the gist of the present invention.

10 Electronic cassette 12 Imaging unit 14 Control unit 16 Hinge (connection member)
17 Rotating shaft (connecting member)
19 Operation panel (reception means)
20, 20A, 20B Radiation detector 21 Imaging unit 22 Insulating substrate 24 Switch elements 26, 26A, 26B TFT substrate 27 Light shielding plate (light shielding layer)
28, 28A, 28B Scintillator layer (light emitting layer)
52A, 52B Gate line driver (generation means)
54A, 54B Signal processing unit (generation means)
58 Cassette control unit (management means)
58A CPU (management means)
58B Memory 60 Wireless communication unit (accepting means)

Claims (15)

Each has a light-emitting layer that generates light when irradiated with radiation, and a substrate on which a switch element for reading out the charge is formed while accumulating charges by receiving light generated in the light-emitting layer Two radiation detectors arranged to overlap,
A light shielding layer that is provided between the two radiation detectors and shields light generated in the light emitting layers of the two radiation detectors from each other;
A radiography apparatus comprising: The radiation imaging apparatus according to claim 1, wherein the two radiation detectors have the light emitting layer disposed so as to sandwich the light shielding layer. The radiation imaging apparatus according to claim 1, wherein the light shielding layer is a light shielding substrate having rigidity. The radiation imaging apparatus according to claim 1, wherein the light emitting layers of the two radiation detectors have different emission characteristics with respect to radiation. The light-emitting layers of the two radiation detectors are the thickness of each light-emitting layer, the particle size of each light-emitting layer, and the particle size of particles that emit light when irradiated with radiation, the layered structure of the particles, the filling rate of the particles, At least one change in the doping amount of the activator, the material of each light emitting layer, and the layer structure of each light emitting layer, and the formation of a reflective layer that reflects the light on the surface of each light emitting layer that is not opposed to the substrate The radiation imaging apparatus according to claim 4, wherein either one is performed. The radiation imaging apparatus according to claim 4, wherein one of the light emitting layers of the two radiation detectors has light emission characteristics that emphasize image quality, and the other has light emission characteristics that emphasize sensitivity. The radiation imaging apparatus according to claim 4, wherein the light emitting layers of the two radiation detectors have substantially the same light emission characteristics when irradiated with radiation from one side. The radiation according to any one of claims 1 to 7, wherein at least one of the light emitting layers of the two radiation detectors includes a columnar crystal of a phosphor material that emits light when irradiated with radiation. Shooting device. The radiation imaging apparatus according to claim 8, wherein the phosphor material is CsI. The radiographic apparatus according to any one of claims 1 to 9, wherein the substrates of the two radiation detectors have different readout characteristics of a signal obtained by reading out accumulated charges. The radiation imaging apparatus according to claim 1, wherein the light shielding layer shields radiation. Generation means for individually reading out the charges accumulated in the two radiation detectors, reading the accumulated charges as electric signals, and generating image information indicating a radiation image based on the read-out electric signals; ,
Receiving means for receiving processing conditions for the two radiation detectors;
Management means that can switch processing for the two radiation detectors, and manages processing for the two radiation detectors according to the processing conditions received by the receiving means;
The radiation imaging apparatus according to any one of claims 1 to 11, further comprising: The exchangeable processing for the two radiation detectors includes a read-out process of charges from the two radiation detectors by the generation unit, and an image read out from the two radiation detectors and generated by the generation unit. At least one of image processing for information, image information generated by the generating unit and transmission processing of the image processed image information, and image information generated by the generating unit and storage processing of the image processed image information The radiation imaging apparatus according to claim 11. Imaging that is formed in a flat plate shape, and that includes the two radiation detectors and the light shielding layer, and that can capture a radiation image of the irradiated radiation on either one side or the other side of the flat plate Unit,
A control unit in which the receiving means and the management means are built-in;
A connecting member that is openably and closably connected to an unfolded state in which the photographing unit and the control unit are aligned, and a storage state in which the photographing unit and the control unit are overlapped and folded;
The radiation imaging apparatus according to claim 1, further comprising: Imaging that is formed in a flat plate shape, and that includes the two radiation detectors and the light shielding layer, and that can capture a radiation image of the irradiated radiation on either one side or the other side of the flat plate Unit,
A control unit in which the receiving means and the management means are built-in;
A connecting member that reversibly connects one surface of the photographing unit to the control unit, and the other surface;
The radiation imaging apparatus according to claim 1, further comprising:

Images