JP2012013682A - Radiographic image photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic image photographing device in which impact resistance is improved while achieving thinning and lightweight.SOLUTION: The thinning and lightweight is achieved by directly attaching a scintillator 8 that generates light by irradiation with radioactive ray, a sensor unit that generates charges by receiving light generated by the scintillator 8, and a radioactive ray detection unit 20 having a substrate on which a thin film transistor is formed for reading charges generated by the sensor unit to a face of a top plate 41B opposite to a face on which the radioactive ray X is incident, the top plate 41B having a transmission face through which the radioactive ray X that has passed through a subject C transmits. The impact resistance is improved by composing the sensor unit with an organic photoelectric conversion material being excellent in load resistance and drop impact resistance.

Description

  The present invention relates to a radiographic imaging apparatus, and more particularly to a radiographic imaging apparatus provided with a radiation detector.

  2. Description of the Related Art In recent years, radiation detectors such as FPD (Flat Panel Detector) capable of directly converting radiation such as X-rays into digital data by arranging a radiation sensitive layer on a TFT (Thin Film Transistor) active matrix substrate have been put into practical use. The radiographic imaging device using this radiation detector can see images immediately and can continuously capture radiographic images as compared with conventional radiographic imaging devices using X-ray film or imaging plate. There is an advantage that (moving image shooting) can also be performed.

Various types of radiation detectors of this type have been proposed. For example, radiation is once converted into light by a scintillator such as CsI: Tl, GOS (Gd ₂ O ₂ S: Tb), and converted light. There is an indirect conversion method in which a sensor unit such as a photodiode converts it into electric charge and stores it. In the radiographic imaging apparatus, the electric charge accumulated in the radiation detector is read as an electric signal, and the read electric signal is amplified by an amplifier and then converted into digital data by an A / D (analog / digital) converter.

  As a technique related to this type of radiographic imaging apparatus, Patent Document 1 discloses a first layer that emits light according to the intensity of incident radiation, and an organic compound that converts light output from the first layer into electrical energy. There is disclosed an imaging panel having a second layer made of a third layer and a third layer for outputting a signal based on electric energy obtained in the second layer.

  Patent Document 2 discloses a technique for attaching a scintillator to a top plate of a housing with an adhesive.

JP 2003-172783 A US Patent Application Publication No. 2009/0122959

  However, in the technique disclosed in Patent Document 1, since the radiation detector (imaging panel) and the housing are separated from each other, the radiographic imaging device can be sufficiently thinned and lightened. There was a problem that it was not limited.

  On the other hand, in the technique disclosed in Patent Document 2, since the scintillator is attached to the top plate of the housing, it can contribute to thinning of the radiographic image capturing apparatus, but becomes a radiographic image capturing target. There is a problem that impact resistance is required because the radiation detector directly receives the impact of the subject.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a radiographic imaging apparatus capable of improving impact resistance while achieving reduction in thickness and weight.

  In order to achieve the above object, the radiographic imaging device according to claim 1 generates a charge by receiving a light emitting layer that generates light when irradiated with radiation, and light generated by the light emitting layer. A radiation detector having a substrate on which a sensor unit including an organic photoelectric conversion material is formed, a transmission surface through which the radiation transmitted through the subject is transmitted, and on the opposite side of the surface on which the radiation is incident And a top plate on which the radiation detector is directly attached.

  The radiographic imaging device according to claim 1 includes a light emitting layer that generates light when irradiated with radiation, and an organic photoelectric conversion material that generates electric charges when receiving light generated in the light emitting layer. The radiation detector having the substrate on which the sensor unit is formed is directly attached to the surface opposite to the surface on which the radiation is incident on the top plate having a transmission surface through which the radiation transmitted through the subject is transmitted.

  That is, in the present invention, as the radiation detector, one in which the sensor portion includes an organic photoelectric conversion material having excellent load resistance and drop impact resistance is applied, while the radiation detector is used as a top plate. By directly attaching, the impact resistance of the radiographic imaging device is improved.

  In addition, since the impact resistance can be improved in this way in the present invention, the top plate is made thinner or the material constituting the top plate is lighter and more rigid than when the present invention is not applied. As a result, the thickness can be reduced and the weight can be reduced.

  Thus, according to the radiographic imaging device of claim 1, the light emitting layer that generates light when irradiated with radiation, and the organic that generates charges by receiving the light generated in the light emitting layer. A radiation detector having a substrate on which a sensor unit including a photoelectric conversion material is formed has a transmission surface through which a radiation transmitted through a subject is transmitted. Therefore, the impact resistance can be improved while reducing the thickness and weight.

  In the present invention, as in the invention described in claim 2, the substrate of the radiation detector may further include a switching element for reading out the electric charge generated in the sensor unit.

  In the present invention, as in the invention described in claim 3, the top plate may be directly attached to the substrate of the radiation detector. Thereby, the resolution of the radiographic image obtained by imaging can be increased, and a decrease in sensitivity to radiation can be suppressed.

  In the present invention, as in the invention described in claim 4, the substrate may be made of any one of plastic resin, aramid, and bionanofiber. Thereby, the rigidity of a radiation detector can be made high, As a result, a top plate can be made thin.

  According to a second aspect of the present invention, as in the fifth aspect of the present invention, the switching element may be a thin film transistor having an active layer containing an amorphous oxide. As a result, radiation is not absorbed by the switching element, or even if it is absorbed, the amount of the radiation remains very small, and generation of noise in the switching element can be effectively suppressed.

  Moreover, as for this invention, the said top plate may be comprised with the material containing a reinforced fiber resin like the invention of Claim 6. Thereby, compared with the case where a top plate is comprised with a carbon single-piece | unit etc., the intensity | strength of a top plate can be made high.

  Particularly, in the invention described in claim 6, as in the invention described in claim 7, the reinforcing fiber resin may be a carbon fiber reinforced plastic. As a result, it is possible to increase the thermal conductivity of the top plate as compared with the case where the top plate is made of carbon alone, and as a result, image unevenness due to temperature unevenness of the radiation image obtained by the radiation detector is reduced. Can be suppressed.

  Further, according to the present invention, as in the invention described in claim 8, a measuring unit that measures a degree of curvature of the radiation detector at the time of capturing a radiographic image, and the radiation according to a measurement result by the measuring unit. The image processing apparatus may further include correction means for correcting distortion of the radiation image indicated by the image information obtained by the detector. Thereby, even when the radiation detector is curved, the distortion of the radiation image due to the curvature can be suppressed.

  In the present invention, as in the invention described in claim 9, the radiation detector may be attached to the top plate so as to be separable. Thereby, a housing | casing can be exchanged efficiently.

  Further, according to the present invention, as in the invention described in claim 10, the radiation detector is bonded to the top plate so that an internal space is formed between the radiation detector and the top plate. The adhesive member may be further provided with a ventilation unit that communicates the internal space and the outside and prevents foreign matter from entering the internal space from the outside.

  According to the present invention, since the radiation detector is bonded to the top plate so that an internal space is formed between the radiation detector and the top plate using the adhesive member, the contact of the adhesive member to the radiation detector and the top plate is achieved. Even if air remains on the surface, the remaining air can be released to the internal space. Further, since the internal space communicates with the outside through the ventilation means, the pressure in the internal space and the external atmospheric pressure can be kept constant even when the atmospheric pressure changes. Therefore, it can prevent that the adhesiveness of the radiation detector with respect to a top plate falls by atmospheric pressure change.

  Further, since the ventilation means prevents foreign matters from entering the internal space from the outside, it is possible to eliminate the concern that foreign matters such as metal pieces that absorb radiation enter the internal space and are displayed in the radiation image. . Accordingly, it is possible to suppress the contamination of foreign matters that leads to the deterioration of the quality of the radiation image.

  In particular, the invention described in claim 10 is a communication path in which the ventilation means is formed in the adhesive member and communicates with the inner space and the outside bent as in the invention described in claim 11. May be.

  According to the present invention, since the communication path is bent, it is possible to prevent the foreign matter from entering the internal space even when foreign matter flows into the communication path from the outside together with air. This is because the mass of the foreign matter is larger than the mass of air, so that the foreign matter cannot follow the flow of air flowing through the bent portion of the communication path. Further, since the communication path is formed in the adhesive member, the foreign matter is likely to adhere to the wall surface of the communication path. Accordingly, the foreign matter that can no longer follow the air flow at the bent portion of the communication passage is reliably captured by the wall surface of the communication passage having adhesiveness. As a result, it is possible to more reliably prevent foreign matter from entering the internal space.

  According to a tenth aspect of the present invention, as in the twelfth aspect of the present invention, the venting means is formed in the adhesive member so as to communicate the internal space and the outside, and the communication path. There may be provided a filter member that permits the flow of air between the outside and prevents foreign matter from entering the communication path from the outside. Thereby, it is possible to realize communication between the internal space and the outside and prevention of foreign matter from entering the internal space from the outside with a simple configuration.

  Further, in the invention according to any one of claims 10 to 12, as in the invention according to claim 13, the adhesive member is made of a material whose adhesive force is changed by an external factor. It may be comprised.

  According to the present invention, since the adhesive force of the adhesive member can be changed, for example, when the radiation detector is peeled from the top plate, the adhesive force of the adhesive member is reduced, or the radiation detector is attached to the top. When adhering to a board, the adhesive force of the said adhesive member can be raised. As a result, it is possible to eliminate the concern that the radiation detector is damaged when the radiation detector is peeled from the top plate, or that the radiation detector bonded to the top plate is peeled off.

  Furthermore, in the present invention, as in the invention described in claim 14, the top plate may constitute a part of a housing that houses the radiation detector. Thereby, compared with the case where a top plate is comprised separately from a housing | casing, a top plate can be comprised more simply.

  According to the radiographic imaging device of the present invention, it is configured to include a light emitting layer that generates light when irradiated with radiation, and an organic photoelectric conversion material that generates electric charge by receiving light generated in the light emitting layer. The radiation detector having the substrate on which the sensor unit is formed is directly attached to the surface opposite to the surface on which the radiation is incident on the top plate having a transmission surface through which the radiation transmitted through the subject is transmitted. Therefore, it is possible to improve the impact resistance while reducing the thickness and weight.

It is a cross-sectional schematic diagram which shows schematic structure of the 3 pixel part of the radiation detector which concerns on embodiment. It is the cross-sectional side view which showed schematically the structure of the signal output part of 1 pixel part of the radiation detector which concerns on embodiment. It is a schematic plan view which shows the structure of the radiation detector which concerns on embodiment. It is a perspective view which shows the structure of the electronic cassette concerning embodiment. It is a section side view showing the composition of the electronic cassette concerning an embodiment. It is a cross-sectional bottom view which shows the internal structure of the housing | casing of the electronic cassette concerning 1st Embodiment. It is a partially expanded sectional bottom view which shows the internal structure of the housing | casing of the electronic cassette concerning 1st Embodiment. It is explanatory drawing which shows the state which peels a radiation detector from a top plate in the 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 schematic diagram which shows the structure of the conversion information which concerns on embodiment. It is a flowchart which shows the flow of a process of the image transmission process program which concerns on embodiment. It is a cross-sectional side view for demonstrating the surface irradiation and back surface irradiation of the radiation to a radiation detector. It is a partially expanded sectional bottom view which shows the modification of the internal structure of the housing | casing of the electronic cassette concerning 1st Embodiment. It is a cross-sectional bottom view which shows the internal structure of the housing | casing of the electronic cassette concerning 2nd Embodiment. It is a partially expanded sectional bottom view which shows the internal structure of the housing | casing of the electronic cassette concerning 3rd Embodiment. It is a partially abbreviated cross-sectional explanatory drawing of the electronic cassette concerning 4th Embodiment. It is a partially-omission cross-sectional explanatory drawing which shows the modification of the housing | casing of the electronic cassette concerning embodiment. It is explanatory drawing which shows the modification of the housing | casing of the electronic cassette concerning embodiment. It is explanatory drawing which shows the modification of the housing | casing of the electronic cassette concerning embodiment. It is a graph which shows an example of the sensitivity characteristic of various materials. It is a graph which shows an example of the sensitivity characteristic of various materials.

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

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

  FIG. 1 is a schematic cross-sectional view schematically showing a configuration of three pixel portions of a radiation detector 20 according to an embodiment of the present invention.

  In the radiation detector 20, a signal output unit 14, a sensor unit 13, and a scintillator 8 are sequentially stacked on an insulating substrate 1, and a pixel unit is configured by the signal output unit 14 and the sensor unit 13. . A plurality of pixel units are arranged on the substrate 1, and the signal output unit 14 and the sensor unit 13 in each pixel unit are configured to overlap each other.

  The scintillator 8 is formed on the sensor unit 13 via the transparent insulating film 7 and is formed by forming a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 1) into light. It is. Providing such a scintillator 8 absorbs the radiation transmitted through the subject and emits light.

  The wavelength range of light emitted by the scintillator 8 is preferably a visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 20, the wavelength range of green is included. Is more preferable.

  Specifically, the phosphor used in the scintillator 8 is preferably one containing cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 420 nm to 700 nm upon X-ray irradiation. It is particularly preferable to use CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

  The scintillator 8 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). When the scintillator 8 is formed by vapor deposition as described above, an Al plate is often used as the vapor deposition substrate in terms of X-ray transmittance and cost, but is not limited thereto. When GOS is used as the scintillator 8, the scintillator 8 may be formed by applying GOS to the surface of the TFT substrate 30 described later without using a vapor deposition substrate.

  The sensor unit 13 includes an upper electrode 6, a lower electrode 2, and a photoelectric conversion film 4 disposed between the upper and lower electrodes. The photoelectric conversion film 4 absorbs light emitted from the scintillator 8 and generates charges. It is composed of an organic photoelectric conversion material.

Since it is necessary for the upper electrode 6 to cause the light generated by the scintillator 8 to be incident on the photoelectric conversion film 4, it is preferable that the upper electrode 6 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 8. It is preferable to use a transparent conductive oxide (TCO) having a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the upper electrode 6, TCO is preferable because it tends to increase the resistance value when it is desired to obtain a transmittance of 90% or more. For example, ITO, IZO, AZO, FTO, SnO ₂ , TiO ₂ , ZnO _{2 and the} like can be preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. Note that the upper electrode 6 may have a single configuration common to all the pixel portions, or may be divided for each pixel portion.

  The photoelectric conversion film 4 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 8, and generates a charge corresponding to the absorbed light. In this way, the photoelectric conversion film 4 containing an organic photoelectric conversion material has a sharp absorption spectrum in the visible range, and electromagnetic waves other than light emitted by the scintillator 8 are hardly absorbed by the photoelectric conversion film 4. The noise generated by the radiation such as being absorbed by the photoelectric conversion film 4 can be effectively suppressed.

  The organic photoelectric conversion material constituting the photoelectric conversion film 4 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 8 in order to absorb light emitted by the scintillator 8 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 8, but if the difference between the two is small, the light emitted from the scintillator 8 can be sufficiently absorbed. . 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 8 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone-based organic compounds and phthalocyanine-based organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 8, the difference in peak wavelength can be within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 4 can be substantially maximized.

  Next, the photoelectric conversion film 4 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 may be composed of an organic layer including a pair of electrodes 2 and 6 and an organic photoelectric conversion film 4 sandwiched between the electrodes 2 and 6. it can. 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. Accordingly, 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. Accordingly, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound.

  The materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoelectric conversion film 4 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, and thus the description thereof is omitted. The photoelectric conversion film 4 may be formed by further containing fullerenes or carbon nanotubes.

  The thickness of the photoelectric conversion film 4 is preferably as large as possible in terms of absorbing light from the scintillator 8. However, when the thickness is more than a certain level, the photoelectric conversion film 4 is generated in the photoelectric conversion film 4 by a bias voltage applied from both ends of the photoelectric conversion film 4. Since electric field strength is reduced and charges cannot be collected, the thickness is preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, and particularly preferably 80 nm to 200 nm.

  In the radiation detector 20 illustrated in FIG. 1, the photoelectric conversion film 4 has a single-sheet configuration common to all pixel units, but may be divided for each pixel unit.

  The lower electrode 2 is a thin film divided for each pixel portion. The lower electrode 2 can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be suitably used.

  The thickness of the lower electrode 2 can be, for example, 30 nm or more and 300 nm or less.

  In the sensor unit 13, by applying a predetermined bias voltage between the upper electrode 6 and the lower electrode 2, one of electric charges (holes, electrons) generated in the photoelectric conversion film 4 is moved to the upper electrode 6. The other can be moved to the lower electrode 2. In the radiation detector 20 of the present embodiment, a wiring is connected to the upper electrode 6, and a bias voltage is applied to the upper electrode 6 through this wiring. In addition, the polarity of the bias voltage is determined so that electrons generated in the photoelectric conversion film 4 move to the upper electrode 6 and holes move to the lower electrode 2, but this polarity is reversed. May be.

  The sensor unit 13 constituting each pixel unit only needs to include at least the lower electrode 2, the photoelectric conversion film 4, and the upper electrode 6. In order to suppress an increase in dark current, the electron blocking film 3 and hole blocking are performed. It is preferable to provide at least one of the films 5, and it is more preferable to provide both.

  The electron blocking film 3 can be provided between the lower electrode 2 and the photoelectric conversion film 4. When a bias voltage is applied between the lower electrode 2 and the upper electrode 6, electrons are transferred from the lower electrode 2 to the photoelectric conversion film 4. It is possible to suppress the dark current from increasing due to the injection of.

  An electron donating organic material can be used for the electron blocking film 3.

  The material actually used for the electron blocking film 3 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 4 and the like, and 1.3 eV or more from the work function (Wf) of the material of the adjacent electrode. Those having a large electron affinity (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 4 are preferable. The material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, and thus the description thereof is omitted.

  The thickness of the electron blocking film 3 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, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 13. It is 50 nm or more and 100 nm or less.

  The hole blocking film 5 can be provided between the photoelectric conversion film 4 and the upper electrode 6. When a bias voltage is applied between the lower electrode 2 and the upper electrode 6, the hole blocking film 5 is transferred from the upper electrode 6 to the photoelectric conversion film 4. 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 5.

  The thickness of the hole blocking film 5 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, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 13. Is from 50 nm to 100 nm.

  The material actually used for the hole blocking film 5 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 4 and the like, and 1.3 eV from the work function (Wf) of the material of the adjacent electrode. As described above, it is preferable that the ionization potential (Ip) is large and that the Ea is equal to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 4. 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 addition, when a bias voltage is set so that holes move to the upper electrode 6 and electrons move to the lower electrode 2 among the charges generated in the photoelectric conversion film 4, the electron blocking film 3 and the hole blocking are set. The position of the film 5 may be reversed. Moreover, it is not necessary to provide both the electron blocking film 3 and the hole blocking film 5. If either one is provided, a certain degree of dark current suppressing effect can be obtained.

  A signal output unit 14 is formed on the surface of the substrate 1 below the lower electrode 2 of each pixel unit.

  FIG. 2 schematically shows the configuration of the signal output unit 14.

  Corresponding to the lower electrode 2, a capacitor 9 that accumulates the charge transferred to the lower electrode 2, and a field effect thin film transistor (hereinafter referred to simply as “Thin Film Transistor”) that converts the charge accumulated in the capacitor 9 into an electric signal and outputs the electric signal. 10 may be formed. The region in which the capacitor 9 and the thin film transistor 10 are formed has a portion that overlaps the lower electrode 2 in a plan view. With such a configuration, the signal output unit 14 and the sensor unit 13 in each pixel unit are connected to each other. There will be overlap in the thickness direction. In order to minimize the plane area of the radiation detector 20 (pixel portion), it is desirable that the region where the capacitor 9 and the thin film transistor 10 are formed is completely covered by the lower electrode 2.

  The capacitor 9 is electrically connected to the corresponding lower electrode 2 through a wiring made of a conductive material penetrating an insulating film 11 provided between the substrate 1 and the lower electrode 2. Thereby, the electric charge collected by the lower electrode 2 can be moved to the capacitor 9.

  In the thin film transistor 10, a gate electrode 15, a gate insulating film 16, and an active layer (channel layer) 17 are stacked, and a source electrode 18 and a drain electrode 19 are formed on the active layer 17 at a predetermined interval. . The active layer 17 can be formed of, for example, amorphous silicon, amorphous oxide, organic semiconductor material, carbon nanotube, or the like. In addition, the material which comprises the active layer 17 is not limited to these.

The amorphous oxide that can form the active layer 17 is preferably an oxide containing at least one of In, Ga, and Zn (for example, In—O-based), and at least 2 of In, Ga, and Zn. Are more preferable (for example, In—Zn—O, In—Ga—O, and Ga—Zn—O), 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. In addition, the amorphous oxide which can comprise the active layer 17 is not limited to these.

  Examples of the organic semiconductor material that can form the active layer 17 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 17 of the thin film transistor 10 is formed of an amorphous oxide, an organic semiconductor material, or a carbon nanotube, it will not absorb radiation such as X-rays, or even if it absorbs it, it will remain in a very small amount. Generation of noise in the portion 14 can be effectively suppressed.

  When the active layer 17 is formed of carbon nanotubes, the switching speed of the thin film transistor 10 can be increased, and the thin film transistor 10 having a low light absorption in the visible light region can be formed. In addition, when the active layer 17 is formed of carbon nanotubes, the performance of the thin film transistor 10 is remarkably deteriorated only by mixing a very small amount of metallic impurities into the active layer 17, so that extremely high purity carbon nanotubes can be obtained by centrifugation or the like. It is necessary to form by separating and extracting.

  Here, any of the amorphous oxides, organic semiconductor materials, carbon nanotubes constituting the active layer 17 of the thin film transistor 10 and organic photoelectric conversion materials constituting the photoelectric conversion film 4 can be formed at a low temperature. . Therefore, the substrate 1 is not limited to a substrate having high heat resistance 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.

  In addition, the substrate 1 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.

  On the other hand, 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 its resistance, and it 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, there is little warping after manufacturing and it is difficult to crack. In addition, aramid can form a substrate thinner than a glass substrate or the like. The substrate may be formed by laminating an ultrathin glass substrate and aramid.

  The bionanofiber is a composite of a cellulose microfibril bundle (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 to 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. The substrate 1 can be formed thinly.

  In the present embodiment, the TFT substrate 30 is formed on the substrate 1 by sequentially forming the signal output unit 14, the sensor unit 13, and the transparent insulating film 7, and the light-absorbing adhesive resin is formed on the TFT substrate 30. The radiation detector 20 is formed by pasting the scintillator 8 using, for example.

  As shown in FIG. 3, the TFT substrate 30 includes a pixel 32 including the sensor unit 13, the capacitor 9, and the thin film transistor 10 described above in a certain direction (the row direction in FIG. 3) and an intersection with the certain direction. A plurality of two-dimensional shapes are provided in the direction (column direction in FIG. 3).

  Further, the radiation detector 20 extends in the predetermined direction (row direction), and extends in the intersecting direction (column direction) with a plurality of gate wirings 34 for turning on and off each thin film transistor 10. A plurality of data wirings 36 for reading out charges through the thin film transistor 10 in the on state are provided.

  The radiation detector 20 has a flat plate shape and a quadrilateral shape having four sides on the outer edge in a plan view, more specifically, a rectangular shape.

  Next, the configuration of a portable radiographic image capturing apparatus (hereinafter referred to as an electronic cassette) 40 that incorporates the radiation detector 20 and captures a radiographic image will be described.

  FIG. 4 is a perspective view showing the configuration of the electronic cassette 40 according to the present exemplary embodiment.

  As shown in the figure, an electronic cassette 40 according to the present embodiment includes a flat casing 41 made of a material that transmits radiation, and has a waterproof and airtight structure. A space (external space) A for accommodating various components is formed inside the housing 41, and the subject is transmitted through the space from the irradiation surface side of the housing 41 irradiated with the radiation X. The radiation detector 20 for detecting the radiation X and the lead plate 43 for absorbing the back scattered radiation of the radiation X are arranged in this order.

  Here, in the electronic cassette 40 according to the present exemplary embodiment, the area corresponding to the arrangement position of the radiation detector 20 on one flat surface of the housing 41 is a quadrilateral imaging area 41A capable of detecting radiation. Has been. The surface having the imaging region 41A of the housing 41 is a top plate 41B in the electronic cassette 40. In the electronic cassette 40 according to the present embodiment, as shown in FIG. 30 is disposed on the top plate 41B side, and is attached to the inner surface of the casing 41 of the top plate 41B (the surface opposite to the surface on which radiation of the top plate 41B is incident).

  By the way, the electronic cassette 40 according to the present embodiment has an image correction function for correcting the distortion of the radiation image indicated by the image information obtained by the imaging, which is caused by the distortion of the radiation detector 20 in the radiation incident direction. Have. For this reason, in the electronic cassette 40 according to the present exemplary embodiment, a strain gauge 46 for detecting the strain amount of the radiation detector 20 is bonded to the central portion on the lower surface side of the scintillator 8 of the radiation detector 20.

  Also, a cassette control unit 58 and a power source unit 70 (both shown in FIG. 9), which will be described later, are accommodated at one end inside the housing 41 at a position that does not overlap the radiation detector 20 (outside the range of the imaging region 41A). A case 42 is disposed.

  The casing 41 is made of, for example, carbon fiber (carbon fiber), aluminum, magnesium, bionanofiber (cellulose microfibril), or a composite material in order to reduce the weight of the entire electronic cassette 40.

  As the composite material, for example, a material including a reinforced fiber resin is used, and the reinforced fiber resin includes carbon, cellulose, and the like. Specifically, as the composite material, carbon fiber reinforced plastic (CFRP), a structure in which a foamed material is sandwiched with CFRP, or a material in which the surface of the foamed material is coated with CFRP is used. In the present embodiment, a structure in which a foam material is sandwiched with CFRP is used. Thereby, compared with the case where the housing | casing 41 is comprised with a carbon single-piece | unit, the intensity | strength (rigidity) of the housing | casing 41 can be improved.

  On the other hand, inside the housing 41, a support body 44 is disposed on the inner surface of the back surface portion 41C facing the top plate 41B. Between the support body 44 and the top plate 41B, the radiation detector 20 and the lead plate 43 are disposed. They are arranged in this order in the irradiation direction of the radiation X.

  The support body 44 is made of, for example, a foam material from the viewpoint of weight reduction and absorption of dimensional deviation, and supports the lead plate 43.

  As shown in FIGS. 5-7, the adhesive member 80 which adhere | attaches the TFT substrate 30 of the radiation detector 20 so that peeling is possible is provided in the inner surface of the top plate 41B. As the adhesive member 80, for example, a double-sided tape is used. In this case, the double-sided tape is formed so that the adhesive force of one adhesive surface is stronger than the adhesive force of the other adhesive surface.

  Specifically, the weak adhesive surface (weakly adhesive surface) is set to 1.0 N / cm or less at 180 ° peel adhesive force. Then, the surface having a strong adhesive force (strong adhesion surface) is in contact with the top plate 41B, and the weak adhesion surface is in contact with the TFT substrate 30. Thereby, compared with the case where the radiation detector 20 is fixed to the top plate 41B with fixing members, such as a screw, the thickness of the electronic cassette 40 can be made thin. Even if the top plate 41B is deformed by an impact or load, the radiation detector 20 follows the deformation of the top plate 41B having high rigidity, so that only a large curvature (slow bend) is generated, and a local low curvature is generated. Therefore, the possibility that the radiation detector 20 is damaged is reduced. Furthermore, the radiation detector 20 contributes to the improvement of the rigidity of the top plate 41B. The double-sided tape also has an adhesive force on a surface other than the surface in contact with the TFT substrate 30 and the top plate 41B.

  Further, as shown in FIG. 6, the adhesive member 80 is disposed along the side wall of the housing 41 in a state of being formed in a band shape. Thus, an internal space B is formed between the TFT substrate 30 and the top plate 41B in a state where the TFT substrate 30 is bonded to the top plate 41B (see also FIG. 5).

  As shown in FIG. 7, the adhesive member 80 is formed with a communication path 82 as a ventilation means for communicating the internal space B and the external space A at a portion corresponding to the corner of the top plate 41 </ b> B. The communication path 82 is bent and specifically has four corners 84. That is, the communication path 82 has a labyrinth structure formed so as to be bent. In addition, the bending angle of the bent part (corner part 84) of the communication path 82 can be set arbitrarily, and may be bent like a bow. Further, the passage width d of the communication passage 82 is set as narrow as possible within a range where air can flow. However, the passage width d of the communication passage 82 may be set arbitrarily.

  As described above, in the electronic cassette 40 according to the present exemplary embodiment, the radiation detector 20 is attached to the inside of the top plate 41B of the housing 41, so that the housing 41 is on the top plate 41B side and the back surface portion 41C side. When the radiation detector 20 is attached to the top plate 41B or the radiation detector 20 is peeled off from the top plate 41B, the housing 41 is placed on the top plate 41B side. And the back surface portion 41C side are separated into two.

  In the present embodiment, the radiation detector 20 may not be bonded to the top plate 41B in a clean room or the like. This is because when a foreign object such as a metal piece that absorbs radiation is mixed between the radiation detector 20 and the top plate 41B, the foreign object can be removed by peeling the radiation detector 20 from the top plate 41B.

  By the way, when peeling the radiation detector 20 from the top plate 41B so as to directly grip the radiation detector 20, the side wall of the housing 41 becomes an obstacle. Therefore, as shown in FIG. 8, ears 86 may be provided on the TFT substrate 30 of the radiation detector 20. Thus, the operator can easily peel the radiation detector 20 from the top board 41B while holding the ear 86. The ear 86 may be fixed to the TFT substrate 30 or may be detachable from the TFT substrate 30. In the latter case, it is possible to eliminate the concern that the ear 86 becomes an obstacle when capturing a radiographic image.

  On the other hand, FIG. 9 is a block diagram showing a main configuration of the electrical system of the electronic cassette 40 according to the present exemplary embodiment.

  In the radiation detector 20, a gate line driver 52 is disposed on one side of two adjacent sides, and a signal processing unit 54 is disposed on the other side. Each gate wiring 34 of the TFT substrate 30 is connected to a gate line driver 52, and each data wiring 36 of the TFT substrate 30 is connected to a signal processing unit 54.

  The housing 41 includes an image memory 56, a cassette control unit 58, and a wireless communication unit 60.

  Each thin film transistor 10 of the TFT substrate 30 is sequentially turned on in a row unit by a signal supplied from the gate line driver 52 via the gate wiring 34, and the electric charge read by the thin film transistor 10 in the on state is converted into an electric signal. The data wiring 36 is transmitted and input to the signal processing unit 54. 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 unit 54 includes an amplification circuit and a sample hold circuit for amplifying an input electric signal for each data wiring 36, and the electric signal transmitted through the individual data wiring 36. 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 unit 54, and image data output from the A / D converter of the signal processing unit 54 is sequentially stored in the image memory 56. 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 includes a microcomputer, and includes a CPU (Central Processing Unit) 58A, a memory 58B including a ROM (Read Only Memory) and a RAM (Random Access Memory), a nonvolatile storage unit 58C including a flash memory and the like. And controls the entire operation of the electronic cassette 40.

  The cassette control unit 58 is connected to a strain gauge 46 and has a Wheatstone bridge in which a resistance in the strain gauge 46 is incorporated. The strain gauge 46 is arranged using the Wheatstone bridge. A strain measurement unit 58D that measures the strain amount of the radiation detector 20 at the site is provided, and the cassette control unit 58 is based on the change amount of the resistance value of the strain gauge 46, and is a central portion in a plan view of the radiation detector 20. The amount of distortion can be grasped.

  Further, 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 such as a console that performs control related to radiographic image capturing via the wireless communication unit 60, and can transmit and receive various types of information to and from the console. Has been.

  The electronic cassette 40 is provided with a power supply unit 70, which functions as the above-described various circuits and elements (gate line driver 52, signal processing unit 54, image memory 56, wireless communication unit 60, and cassette control unit 58). The microcomputer is operated by 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 40, and supplies power from the charged battery to various circuits and elements. In FIG. 9, the power supply unit 70 and various circuits and wirings for connecting each element are omitted.

  By the way, as described above, the electronic cassette 40 according to the present exemplary embodiment corrects the distortion of the radiation image indicated by the image information obtained by imaging, which is caused by the distortion of the radiation detector 20 in the radiation incident direction. It has a correction function. For this reason, in the electronic cassette 40 according to the present embodiment, the conversion information shown in FIG. 10 is stored in advance in the ROM of the memory 58B as an example.

  As shown in the figure, the conversion information according to the present embodiment is converted into the pre-conversion for each predetermined strain amount in the central portion of the radiation detector 20 measured by the strain gauge 46 and the strain measurement unit 58D. A conversion table composed of coordinates and converted coordinates is stored and configured.

  Here, the conversion table converts the position coordinate of each pixel data constituting the image information from the pre-conversion coordinate when the distortion amount in the central portion of the radiation detector 20 is the corresponding distortion amount. This is derived in advance as one that can be converted into position coordinates when the amount of distortion is 0 (zero) by replacing with rear coordinates.

  In the electronic cassette 40 according to the present embodiment, a lower limit value (3 mm in the present embodiment) of the distortion amount for performing image correction by the image correction function is predetermined, and the conversion information includes A conversion table is stored for each distortion amount that is equal to or greater than the lower limit value and has a predetermined step size.

  Next, the operation of the electronic cassette 40 according to the present exemplary embodiment will be described.

  The electronic cassette 40 according to the present embodiment, when taking a radiographic image, is arranged with a top plate 41B at the top and spaced apart from a radiation generator 72 that generates radiation X, as shown in FIG. A patient's imaging target region C is arranged on the imaging region. The radiation generating device 72 emits radiation X having a radiation dose according to imaging conditions given in advance. The radiation X emitted from the radiation generator 72 is irradiated to the electronic cassette 40 after carrying image information by passing through the imaging target part C.

  The radiation X emitted from the radiation generator 72 reaches the electronic cassette 40 after passing through the imaging target region C. As a result, charges corresponding to the dose of the irradiated radiation X are generated in each sensor unit 13 of the radiation detector 20 incorporated in the electronic cassette 40, and the charges generated by the sensor unit 13 are accumulated in the capacitor 9. The

  The cassette control unit 58 controls the gate line driver 52 after the irradiation of the radiation X, and sequentially outputs an on signal line by line from the gate line driver 52 to each gate wiring 34 of the radiation detector 20 to read image information. I do. Image information read from the radiation detector 20 is stored in the image memory 56.

  Next, the operation of the electronic cassette 40 when transmitting image information obtained by photographing to the console will be described with reference to FIG. FIG. 11 is a flowchart showing the flow of processing of an image transmission processing program executed by the cassette control unit 58 every time image information for one image is stored in the image memory 56. The program is stored in the memory 58B. Pre-stored in the ROM.

  In step 100 in the figure, the image information stored in the image memory 56 is read out, and in the next step 102, the distortion measuring unit 58D measures the amount of distortion at the central portion of the radiation detector 20 at this time.

  In the next step 104, it is necessary to perform image correction by the image correction function by determining whether or not the distortion amount measured by the processing in step 102 is equal to or greater than the lower limit value (3 mm in the present embodiment). If the determination is negative, the process proceeds to step 108 described later, whereas if the determination is affirmative, the process proceeds to step 106.

  In step 106, a conversion table corresponding to the distortion amount measured by the process of step 102 is read from the conversion information (see also FIG. 10), and the image information read by the process of step 100 is read using the read conversion table. After performing the image correction by the image correction function by converting the coordinate position for each pixel, the process proceeds to step 108.

  In step 108, the image information obtained by the above processing is transmitted to the console via the wireless communication unit 60, and then the present image transmission processing program is terminated.

  Incidentally, in the electronic cassette 40 according to the present embodiment, as shown in FIG. 5, the radiation detector 20 is incorporated so that the radiation X is irradiated from the TFT substrate 30 side.

  Here, as shown in FIG. 12, the radiation detector 20 is also referred to as radiation irradiation from the front side on which the scintillator 8 is formed (“front surface irradiation”, “back surface reading method” (so-called PSS (Penetration Side Sampling) method)). .)), The scintillator 8 emits light more strongly on the upper surface side (opposite side of the TFT substrate 30) of the scintillator 8, and radiation is irradiated from the TFT substrate 30 side (back side) ("back surface irradiation", "front surface reading method"). The so-called ISS (Irradiation Side Sampling) method)). ), The radiation transmitted through the TFT substrate 30 enters the scintillator 8, and the TFT substrate 30 side of the scintillator 8 emits light more strongly. Electric charges are generated in each sensor unit 13 provided on the TFT substrate 30 by light generated by the scintillator 8. For this reason, since the radiation detector 20 is closer to the light emission position of the scintillator 8 with respect to the TFT substrate 30 when the radiation is irradiated from the back side than when the radiation is irradiated from the front side, the radiation detector 20 High resolution.

  In the radiation detector 20, the photoelectric conversion film 4 is made of an organic photoelectric conversion material, and the photoelectric conversion film 4 hardly absorbs radiation. For this reason, the radiation detector 20 according to the present embodiment suppresses a decrease in sensitivity to radiation because the amount of radiation absorbed by the photoelectric conversion film 4 is small even when radiation is transmitted through the TFT substrate 30 by backside illumination. it can. In the backside irradiation, the radiation passes through the TFT substrate 30 and reaches the scintillator 8. In this way, when the photoelectric conversion film 4 of the TFT substrate 30 is composed of an organic photoelectric conversion material, the radiation of the photoelectric conversion film 4 is irradiated. Since there is almost no absorption and radiation attenuation can be suppressed to a low level, it is suitable for backside illumination.

  In addition, both the amorphous oxide constituting the active layer 17 of the thin film transistor 10 and the organic photoelectric conversion material constituting the photoelectric conversion film 4 can be formed at a low temperature. For this reason, the board | substrate 1 can be formed with a plastic resin, aramid, and bio-nanofiber with little radiation absorption. Since the substrate 1 formed in this way has a small amount of radiation absorption, even when the radiation is transmitted through the TFT substrate 30 by backside illumination, a decrease in sensitivity to radiation can be suppressed.

  Further, according to the present embodiment, as shown in FIG. 5, the radiation detector 20 is attached to the top plate 41B in the housing 41 so that the TFT substrate 30 is on the top plate 41B side. When 1 is formed of a highly rigid plastic resin, aramid, or bio-nanofiber, the radiation detector 20 itself has high rigidity, so that the top plate 41B of the housing 41 can be formed thin. In addition, when the substrate 1 is formed of a highly rigid plastic resin, aramid, or bionanofiber, the radiation detector 20 itself has flexibility, so that even when an impact is applied to the imaging region 41A, the radiation detector 20 is damaged. It ’s hard.

  As described above in detail, the present embodiment includes a scintillator 8 that generates light when irradiated with radiation, and an organic photoelectric conversion material that generates charges by receiving light generated by the scintillator 8. The radiation detector 20 having the substrate 13 on which the thin film transistor 10 for reading out the electric charges generated in the sensor unit 13 configured by the sensor unit 13 is formed has a transmission surface through which the radiation X transmitted through the subject is transmitted. Since the top plate 41B is directly attached to the surface opposite to the surface on which the radiation is incident, the impact resistance can be improved while reducing the thickness and weight.

  In the present embodiment, the degree of curvature of the radiation detector 20 at the time of capturing a radiographic image is measured, and the distortion of the radiographic image indicated by the image information obtained by the radiation detector 20 according to the measurement result. Therefore, even if the radiation detector 20 is curved, the distortion of the radiation image due to the curvature can be suppressed.

  In the present embodiment, since the top plate 41B constitutes a part of the housing 41 that houses the radiation detector 20, it is simpler than when the top plate is configured separately from the housing. A top plate can be constructed.

  In the present embodiment, since the internal space B is formed between the TFT substrate 30 and the top plate 41B, when the radiation detector 20 is bonded to the top plate 41B, the TFT substrate 30 and the top plate 41B are bonded. Even if air remains on the bonding surface of the member 80, the remaining air can escape to the internal space B. In addition, since the communication member 82 that communicates the internal space B and the external space A is formed in the adhesive member 80, the pressure in the internal space B and the air pressure in the external space A can be reduced even when the atmospheric pressure in the external space A changes. Can be kept constant. Thereby, it can prevent that the adhesiveness of the TFT substrate 30 with respect to the top plate 41B falls by atmospheric pressure change.

  In the present embodiment, the communication path 82 has a corner 84. Therefore, even when foreign matter having a mass larger than that of air flows into the communication path 82 from the external space A, the foreign matter cannot follow the flow of air flowing through the corner portion 84. Mixing into B can be prevented. As a result, it is possible to suppress contamination of foreign matter that leads to deterioration of the quality of the radiation image.

  Further, since the communication path 82 is formed in the adhesive member 80 and the adhesive member 80 has adhesive force on the entire surface, the foreign matter that could not follow the air adheres to the wall surface of the communication path 82 at the corner 84. It becomes easy. Therefore, the foreign matter can be reliably captured in the communication path 82. Therefore, it is possible to more reliably prevent foreign matter from entering the internal space B.

  Further, according to the present embodiment, the passage width d of the communication passage 82 is set as narrow as possible within the range in which air can circulate, so that it is possible to cope with the mixing of foreign matters such as relatively small metal powder. it can. If the passage width d of the communication passage 82 is set according to the assumed size of the foreign matter, it is possible to efficiently prevent the foreign matter from being mixed.

  By the way, generally, the scintillator 8 is more fragile than the TFT substrate 30. Therefore, when the scintillator 8 is bonded to the top plate 41B with the adhesive member 80, the scintillator 8 may be damaged when the radiation detector 20 is peeled off. However, in the present embodiment, since the TFT substrate 30 is bonded to the top plate 41B with the adhesive member 80, the concern that the scintillator 8 is damaged when the radiation detector 20 is peeled can be eliminated.

  Depending on the shooting environment, shooting may be performed with a subject (patient) on the top board 41B. In this case, the top plate 41B is easily damaged. When the top plate 41B is scratched, it may be displayed on the radiographic image as fixed pattern noise, so it is desirable to replace the housing 41. However, when the radiation detector 20 is pasted to the top plate 41B so as not to be peeled off, there is a problem that when the casing 41 is replaced, the expensive radiation detector 20 needs to be replaced together and costs increase. It was. According to the present embodiment, since the radiation detector 20 is detachably bonded to the top plate 41B, the housing 41 can be efficiently replaced.

  Note that the present embodiment is not limited to the configuration described above. As an example, as shown in FIG. 13, the communication path 90 may have only one corner 92. Thereby, the communication path 90 can be easily formed in the adhesive member 80.

  Further, when the radiation detector 20 is peeled from the top plate 41B, an organic solvent or the like may be poured into the adhesive member to weaken the adhesiveness of the adhesive member 80 and then the radiation detector 20 may be peeled off. In this case, since the adhesive member 80 has corners, the organic solvent can easily penetrate into the adhesive member 80.

[Second Embodiment]
Next, an electronic cassette 40 according to a second embodiment will be described with reference to FIG. Note that, in the second embodiment, the same reference numerals are given to the same components as those in the first embodiment, and duplicate descriptions are omitted.

  As shown in FIG. 14, in this embodiment, the configuration of the communication path 94 is different from that of the first embodiment, and a filter member 96 is added. Specifically, the corner portion 92 of the first embodiment is omitted from the communication path 94. And the filter member 96 is affixed on the inner surface of the top plate 41B so that the opening part by the side of the external space A of the communicating path 94 may be plugged up. Further, the filter member 96 is formed with fine holes that allow air to flow between the external space A and the communication path 94 and prevent foreign matters from entering the communication path 94 from the external space A. ing. And thereby, 2nd Embodiment has an effect equivalent to 1st Embodiment. In the present embodiment, the communication path 94 and the filter member 96 correspond to ventilation means.

[Third Embodiment]
Next, an electronic cassette 40 according to a third embodiment will be described with reference to FIG. Note that, in the third embodiment, the same reference numerals are given to the same components as those in the first embodiment, and duplicate descriptions are omitted.

  As shown in FIG. 15, in the present embodiment, a filter member 98 is attached to the inner surface of the top plate 41 </ b> B so as to close the opening on the external space A side of each communication passage 82. The filter member 98 is formed with fine holes that allow air to flow between the external space A and the communication path 82 and prevent foreign matters from entering the communication path 82 from the external space A. ing. Thereby, since the foreign material mixed into the communicating path 82 can be suppressed, the effect of suppressing the mixing of foreign material into the internal space B can be further enhanced. In the present embodiment, the communication path 82 and the filter member 98 correspond to ventilation means.

[Fourth Embodiment]
Next, an electronic cassette 40 according to a fourth embodiment will be described with reference to FIG. In the fourth embodiment, the same reference numerals are assigned to the same components as those in the first embodiment, and duplicate descriptions are omitted. The present embodiment can also be applied to the second and third embodiments. In FIG. 16, for ease of understanding, illustration of components other than the radiation detector is omitted inside the housing.

  As shown in FIG. 16, in the present embodiment, the configuration of the radiation detector 20 'is different from that of the first embodiment. Specifically, the radiation detector 20 ′ is located on the opposite side of the TFT substrate 30 ′ with the scintillator 8 ′ interposed therebetween, and the contact member 88 that contacts the scintillator 8 ′, and the contact member 88 on the TFT substrate 30 ′ side. And a pressing member 89 that can be pressed onto the head. As the pressing member 89, a screw or the like can be used. In this case, the contact member 88 can be pressed against the TFT substrate 30 ′ by tightening a screw to the TFT substrate 30 ′ from the back surface portion 41 </ b> C side. If it is difficult to form a screw tightening hole in the TFT substrate 30 ', a nut or the like may be attached to the TFT substrate 30'.

  According to the present embodiment, when the contact member 88 is pressed against the TFT substrate 30 ′ by the pressing member 89, the scintillator 8 ′ is held between the TFT substrate 30 ′ and the contact member 88, so the TFT substrate 30 ′. The scintillator 8 ′ and the contact member 88 are integrated. Thereby, the strength (rigidity) of the radiation detector 20 ′ can be improved as compared with the case where the scintillator 8 ′ is bonded to the TFT substrate 30 ′ with an adhesive member or the like. Further, when the pressing of the contact member 88 is released, the scintillator 8 'and the TFT substrate 30' are separated. Thus, when one of the scintillator 8 'and the TFT substrate 30' fails, the other can be reused. Further, since the scintillator 8 'is not bonded to the TFT substrate 30' using an adhesive member or the like, the scintillator 8 'is not damaged when the scintillator 8' is removed from the TFT substrate 30 '.

  The present invention is not limited to the first to fourth embodiments described above, and can be implemented in various forms. For example, an adhesive may be used as the adhesive member. In this case, as the adhesive, an adhesive whose adhesive force changes when an external factor acts is used. The external factors include, for example, physical things such as light and heat, and chemical things such as drugs. As such an adhesive, for example, a dismantling adhesive such as a thermoplastic adhesive, an electrically heated plastic adhesive, an ultraviolet plastic adhesive, or a water-absorbing plastic adhesive can be used.

  As a result, the adhesive force of the adhesive member can be changed. For example, when the radiation detector is peeled from the top plate, the adhesive force of the adhesive member is reduced, or when the radiation detector is adhered to the top plate. The adhesive force of the adhesive member can be increased. Therefore, it is possible to eliminate the concern that the radiation detector is damaged when the radiation detector is peeled off from the top plate, or that the radiation detector bonded to the top plate is peeled off. The adhesive member may be a combination of the adhesive and a double-sided tape.

  Moreover, this invention is not limited to the example which adhere | attaches a TFT substrate on the inner surface of a top plate with an adhesive member. For example, the positions of the TFT substrate and the scintillator of the radiation detector described above may be interchanged, and the scintillator may be bonded to the inner surface of the top plate with an adhesive member.

  Furthermore, this invention is not restricted to the form which adhere | attaches a radiation detector on the inner surface of a top plate. For example, in the present invention, an intermediate member may be disposed between the top plate and the radiation detector, and the radiation detector may be bonded to the intermediate member.

  As shown in FIG. 17, the casing 41 ′ may have a top plate 41 </ b> B ′ formed in a plate shape and a partial casing 41 </ b> D excluding the top plate 41 </ b> B ′ formed in a U-shaped cross section. In FIG. 17, illustration of components housed in the housing 41 ′ is omitted. In this case, the top plate 41B 'is made of a fiber reinforced resin such as CFRP, and the partial housing 41D is made of a resin, metal, or the like that is different from the top plate 41B'.

  Furthermore, the housing of the present invention may be made of various materials. For example, as shown in FIG. 18, the housing 41 ″ may be configured by laminating a plurality of carbon fiber sheets. In this case, the number of laminated carbon fiber sheets can be increased with respect to the place where the load is concentrated, and the carbon fiber sheet can be reinforced compared to the place where the load is not concentrated.

  Further, as shown in FIG. 19, the casing 41 '' 'may be configured such that a plurality of honeycomb structures 99A are sandwiched between cover members 99B. In this case, the cover member 99B is formed of CFRP, and the honeycomb structure 99A is formed of, for example, an aramid material or a foam material. As the foam material, polystyrene foam, acrylic foam, polyvinyl chloride foam, foamed silicon, polyurethane foam and the like are used. However, when foamed polypropylene that is an acrylic foam is used as the foamed material, the cost can be kept lower than when other foamed materials are used.

  Moreover, the radiographic imaging device according to the present invention may be used as a radiographic imaging device fixed at a predetermined position.

  In each of the above embodiments, the case where the image correction process in the image correction function is executed using the conversion table has been described. However, the present invention is not limited to this, and the coordinates before conversion are substituted. An arithmetic expression that can obtain the coordinates after conversion is derived in advance, and the image correction process may be executed using the arithmetic expression.

  Further, in each of the above-described embodiments, the case has been described in which the case 42 that accommodates the cassette control unit 58 and the power supply unit 70 and the radiation detector 20 are arranged so as not to overlap each other inside the casing 41 of the electronic cassette 40. However, the present invention is not limited to this. For example, the radiation detector 20 and the cassette control unit 58 or the power supply unit 70 may be arranged so as to overlap each other.

  Further, as the sensor unit 13 of the radiation detector 20, an organic CMOS sensor in which the photoelectric conversion film 4 is made of a material containing an organic photoelectric conversion material may be used. As the TFT substrate 30 of the radiation detector 20, the thin film transistor 10. An organic TFT array sheet in which organic transistors including the organic material are arranged in an array on a flexible sheet may be used. Said organic CMOS sensor is disclosed by Unexamined-Japanese-Patent No. 2009-212377, for example. In addition, the organic TFT array sheet described above is, for example, “Nihon Keizai Shimbun,“ The University of Tokyo, “Developing“ Ultra Flexible ”Organic Transistor” ”, [online], [Search May 8, 2011], Internet <URL : Http://www.nikkei.com/tech/trend/article/g=96958A9C93819499E2EAE2E0E48DE2EAE3E3E0E2E3E2E2E2E2E2E2E2; p = 9694E0E7E2E6E0E2E3E2E2E0E2E0> ”

  When a CMOS sensor is used as the sensor unit 13 of the radiation detector 20, the advantage that photoelectric conversion can be performed at a high speed and the result that the substrate can be thinned can suppress radiation absorption when the ISS method is adopted. There is an advantage that it can be suitably applied to mammography photography.

  On the other hand, when using a CMOS sensor as the sensor unit 13 of the radiation detector 20, there is a low resistance to radiation when a crystalline silicon substrate is used. For this reason, conventionally, there has been a technique for taking measures such as providing an FOP (fiber optical plate) between the sensor unit and the TFT substrate.

  Based on this drawback, a technique using a SiC (silicon carbide) substrate as a semiconductor substrate having high resistance to radiation can be applied. Advantages that can be used as an ISS method by using a SiC substrate, and because SiC has a lower internal resistance and a smaller amount of heat generation than Si, it suppresses the amount of heat generation when shooting movies, and raises the temperature of CsI There is an advantage that it is possible to suppress a decrease in sensitivity due to.

  As described above, a substrate having high resistance to radiation such as a SiC substrate is generally a wide cap (about 3 eV). Therefore, as shown in FIG. 20 as an example, the absorption edge is about 440 nm corresponding to the blue region. Therefore, in this case, a scintillator such as CsI: Tl or GOS that emits light in the green region cannot be used.

  On the other hand, since the research on scintillators that emit light in these green regions has been actively conducted from the sensitivity characteristics of amorphous silicon, there is a high demand for using the scintillators. For this reason, the scintillator which light-emits in a green area | region can be used by comprising the photoelectric converting film 4 with the material containing the organic photoelectric conversion material which absorbs light emission in a green area | region.

  When the photoelectric conversion film 4 is formed of a material containing an organic photoelectric conversion material and the thin film transistor 10 is formed using a SiC substrate, the photoelectric conversion film 4 and the thin film transistor 10 have different sensitivity wavelength regions, and thus the light emitted by the scintillator is emitted. There is no noise of the thin film transistor 10.

  Further, if SiC and a material containing an organic photoelectric conversion material are laminated as the photoelectric conversion film 4, in addition to receiving light emission mainly in the blue region, such as CsI: Na, light emission in the green region is also received. As a result, the sensitivity can be improved. In addition, since the organic photoelectric conversion material hardly absorbs radiation, it can be suitably used for the ISS system.

  Note that SiC is highly resistant to radiation because it is difficult for nuclear nuclei to be blown away even when exposed to radiation. Develop semiconductor devices that can be used for a long time ", [online], [Search May 8, 2011], Internet <URL: http://www.jaea.go.jp/jari/jpn/publish/01/ff/ ff36 / sic.html> ”.

  Moreover, C (diamond), BN, GaN, AlN, ZnO etc. are mentioned as a semiconductor material with high tolerance with respect to radiation other than SiC. These light element semiconductor materials have high radiation resistance because they are mainly wide-gap semiconductors, so they require high energy for ionization (electron-hole pair formation), small reaction cross sections, and This is due to the fact that bonding is strong and atomic displacement is less likely to occur. Regarding this point, for example, “Electronics Research Institute,“ New Development of Nuclear Electronics ”, [online], [Search May 8, 2011], Internet <URL: http: //www.aist .go.jp / ETL / jp / results / bulletin / pdf / 62-10to11 / kobayashi150.pdf> ”. Regarding the radiation resistance of GaN, for example, “Tohoku University,“ Evaluation of radiation resistance of gallium nitride device ”, [online], [Search May 8, 2011], Internet <URL: http: // cycgw1 .cyric.tohoku.ac.jp / ~ sakemi / ws2007 / ws / pdf / narita.pdf> ”.

  In addition, since GaN has good thermal conductivity for applications other than blue LEDs and has high insulation resistance, ICs have been studied in the field of power systems. Further, ZnO has been studied for LEDs that emit light mainly in the blue to ultraviolet region.

By the way, when SiC is used, the band gap Eg is changed from about 1.1 eV to about 2.8 eV of Si, so that the light absorption wavelength λ shifts to the short wavelength side. Specifically, since the wavelength λ = 1.24 / Eg × 1000, the sensitivity changes to wavelengths up to about 440 nm. Therefore, when SiC is used, as shown in FIG. 21, as an example, the scintillator emits light in the blue region rather than CsI: Tl (peak wavelength: about 565 nm) that emits light in the green region. This is more suitable as the emission wavelength. Since the phosphor emits blue light well, CsI: Na (peak wavelength: about 420 nm), BaFX: Eu (X is a halogen such as Br and I, peak wavelength: about 380 nm), CaWO ₄ (peak wavelength: about 425 nm) ZnS: Ag (peak wavelength: about 450 nm), LaOBr: Tb, Y ₂ O ₂ S: Tb, and the like are suitable. In particular, BaFX: Eu used in CsI: Na and CR cassettes, and CaWO ₄ used in screens and films are preferably used.

On the other hand, as a CMOS sensor having high resistance to radiation, a CMOS sensor may be configured by using a configuration of Si substrate / thick film SiO ₂ / organic photoelectric conversion material by SOI (Silicon On Insulator).

  Technologies that can be applied to this configuration include, for example, “Japan Aerospace Exploration Agency (JAXA) Institute for Space Science,“ High radiation resistance by combining the most advanced consumer SOI technology and radiation resistance technology for space. “Development of functional logic integrated circuit development platform for the first time in the world”, [online], [Search May 8, 2011], Internet <URL: http://www.jaxa.jp/press/2010/11/20101122_soi_j .html> ".

  In SOI, since the radiation tolerance of the film thickness SOI is high, examples of the high radiation durability element include a complete separation type thick film SOI and a partial separation type thick film SOI. As for these SOIs, for example, “Patent Office,“ Patent Application Technology Trend Survey Report on SOI (Silicon On Insulator) Technology ”, [online], [Search May 8, 2011], Internet <URL: http://www.jpo.go.jp/shiryou/pdf/gidou-houkoku/soi.pdf> ”.

  Further, even if the thin film transistor 10 or the like of the radiation detector 20 does not have light transmission (for example, a structure in which the active layer 17 is formed of a material having no light transmission such as amorphous silicon), the thin film transistor 10 or the like. Is disposed on a light-transmitting substrate 1 (for example, a flexible substrate made of synthetic resin), and a portion of the substrate 1 where the thin film transistor 10 or the like is not formed is configured to transmit light. It is possible to obtain a radiation detector 20 having optical transparency. Arranging the thin film transistor 10 or the like having a non-light-transmitting structure on the light-transmitting substrate 1 is performed by separating the micro device block manufactured on the first substrate from the first substrate. This can be realized by applying the technology arranged above, specifically, for example, FSA (Fluidic Self-Assembly). The above FSA is, for example, “Toyama University,“ Study on Self-Aligned Placement Technology of Small Semiconductor Blocks ”, [online], [Search May 8, 2011], Internet <URL: http: //www3.u- toyama.ac.jp/maezawa/Research/FSA.html> ”.

1 Substrate 8, 8 'scintillator (light emitting layer)
10 Thin film transistor (switching element)
13 Sensor unit 20, 20 'Radiation detector 30, 30' TFT substrate (substrate)
40 Electronic cassette 41, 41 ′, 41 ″, 41 ′ ″ Housing 41A Imaging regions 41B, 41B ′ Top plate 41C Back surface portion 46 Strain gauge (measuring means)
58 Cassette control unit (correction means)
58D distortion measurement unit (measurement means)
80 Adhesive member 82 Communication path 84 Corner 90 Communication path 92 Corner 94 Communication path 96, 98 Filter member X Radiation

Claims (14)

A light-emitting layer that emits light when irradiated with radiation, and a substrate on which a sensor unit including an organic photoelectric conversion material that generates charges by receiving light generated in the light-emitting layer is formed. A radiation detector;
A top plate having a transmission surface through which the radiation transmitted through the subject is transmitted and the radiation detector is directly attached to a surface opposite to the surface on which the radiation is incident;
A radiographic imaging apparatus comprising: The radiographic imaging apparatus according to claim 1, wherein the substrate of the radiation detector further includes a switching element for reading out electric charges generated by the sensor unit. The radiographic imaging device according to claim 1, wherein the top plate is directly attached to the substrate of the radiation detector. The radiographic imaging apparatus according to any one of claims 1 to 3, wherein the substrate is made of any one of plastic resin, aramid, and bionanofiber. The radiographic imaging apparatus according to claim 2, wherein the switching element is a thin film transistor including an active layer containing an amorphous oxide. The radiographic imaging device according to any one of claims 1 to 5, wherein the top plate is made of a material containing a reinforcing fiber resin. The radiographic image capturing apparatus according to claim 6, wherein the reinforcing fiber resin is a carbon fiber reinforced plastic. Measuring means for measuring the degree of curvature of the radiation detector at the time of radiographic imaging;
According to the measurement result by the measurement means, a correction means for correcting the distortion of the radiation image indicated by the image information obtained by the radiation detector
The radiographic imaging device according to any one of claims 1 to 7, further comprising: The radiographic image capturing apparatus according to claim 1, wherein the radiation detector is detachably attached to the top plate. An adhesive member that bonds the radiation detector to the top plate so that an internal space is formed between the radiation detector and the top plate;
Ventilating means for communicating the internal space and the outside, and preventing foreign matter from entering the internal space from the outside,
The radiographic imaging apparatus according to claim 1, further comprising: The radiographic imaging apparatus according to claim 10, wherein the ventilation means is a communication path formed in the adhesive member and communicating with the inner space and the outside in a bent state. The venting means is formed in the adhesive member to allow communication between the internal space and the outside, allows air flow between the communication path and the outside, and allows foreign matter from the outside to the communication path. The radiographic imaging device according to claim 10, further comprising a filter member that prevents mixing. The radiographic imaging device according to claim 10, wherein the adhesive member is made of a material whose adhesive force changes when an external factor acts. The radiographic imaging apparatus according to any one of claims 1 to 13, wherein the top plate constitutes a part of a housing that accommodates the radiation detector.

Images