JP2013072721A - Radiation detector, radiation image capturing device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately perform synchronization control processing and irradiation control processing.SOLUTION: A radiation detector comprises: a light-emitting layer 13 for emitting light by being irradiated with radiation; a substrate 22 that is laminated to the light-emitting layer 13 and that is formed with a plurality of pixels including sensor units where electric charges are generated by receiving light emitted from the light-emitting layer 13 and switching elements for reading out the electric charges generated in the sensor unit; and a light guide plate 26 that is laminated on the side opposite to the side on which the substrate 22 of the light-emitting layer 13 is laminated or on the side opposite to the side on which the light-emitting layer 13 of the substrate 22 is laminated, that is optically separated into a respective plurality of areas, and where a light guide amount in some areas of the plurality of areas is made larger than a light guide amount in other areas other than the some areas.

Description

  The present invention relates to a radiation detector that detects radiation, a radiation image capturing apparatus including the radiation detector, and a program executed by the radiation image capturing apparatus.

  In recent years, radiation detectors such as flat panel detectors (FPDs) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation directly into digital data have been put into practical use. A radiographic image capturing apparatus that captures a radiographic image represented by irradiated radiation has been put into practical use. The radiation detector used in this radiographic imaging apparatus has an indirect conversion system in which radiation is converted into light by a scintillator and then converted into electric charge in a semiconductor layer such as a photodiode, or the like. There is a direct conversion method in which a semiconductor layer such as amorphous selenium converts into electric charge, and there are various materials that can be used for the semiconductor layer in each method.

  By the way, in this type of radiographic imaging apparatus, if the radiation imaging start itself can detect the start of irradiation, the dose, etc., the radiographic imaging apparatus and the radiographic control apparatus that comprehensively controls the radiographic imaging apparatus and the radiation source, etc. Since it is unnecessary to connect the so-called console and the radiation source, it is preferable for simplifying the system configuration and simplifying the control by the imaging control apparatus.

  The process of detecting the start of radiation irradiation by the radiographic imaging apparatus itself and shifting the operation mode by the radiation detector to the imaging mode at the timing when the start of irradiation is detected is referred to as “synchronous control process” in this specification. Further, the present specification is a process for detecting the radiation dose by the radiation image capturing apparatus itself and stopping the radiation irradiation by the radiation generating apparatus when the radiation dose reaches a predetermined amount based on the imaging conditions. This is called “irradiation control processing”.

  As a technique related to a radiographic imaging apparatus capable of detecting this type of radiation irradiation state, Patent Document 1 discloses a rectangular shape in which a plurality of radiation detection elements constituting pixels are arranged in a two-dimensional matrix to detect radiation. A sensor panel unit, a detection unit that reads out electric charges accumulated in the radiation detection element and converts them into electrical signals, a housing that includes the sensor panel unit and the detection unit, and at least one surface of which is capable of transmitting radiation. A body, a phosphor layer disposed on the radiation incident side of the sensor panel unit, and converting a part of incident radiation into light, and a light guide member for guiding light generated by the phosphor layer in a predetermined direction And a rectangular conversion layer having at least one side of the rectangular conversion layer, and detecting light generated in the phosphor layer and guided by the light guide member A light detection unit, and a control unit that determines whether or not radiation irradiation to the sensor panel unit has started based on a detection result by the light detection unit, and switches and controls a driving state of the detection unit based on the determination result And an apparatus comprising:

JP 2011-99794 A

  However, in the technique disclosed in Patent Document 1, since light guided by one light guide plate (light guide member) is detected for the entire region to be imaged, the region to be imaged is relatively small. When the above-described irradiation control process is executed when the ratio of the area in which the radiation in the imaging target area does not pass through the imaging target site (hereinafter referred to as “elementary area”) to the entire imaging target area is relatively high As a result of detecting a relatively large amount of radiation, there is a problem that exposure may be insufficient. In this case, it is necessary to perform re-imaging with radiation exposure, and as a result, the exposure dose of the subject increases.

  On the other hand, when the synchronous control process described above is executed, it is necessary to detect the start of radiation irradiation as quickly as possible in order to reduce the radiation exposure amount by the subject as much as possible. On the other hand, when performing the above-described irradiation control processing, it is extremely important that the light receiving element that receives the light guided by the light guide plate does not reach the saturation detection amount when detecting the radiation dose. It is.

  However, in the technique disclosed in Patent Document 1, since the light guided by one light guide plate is detected for the entire area to be imaged as described above, the start of radiation irradiation is detected quickly. However, there is a problem that the light receiving element that receives the guided light may reach the saturation detection amount.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a radiation detector, a radiographic imaging apparatus, and a program that can accurately perform the synchronization control process and the irradiation control process.

  In order to achieve the above object, a radiation detector according to the present invention includes, as described in claim 1, a light emitting layer that generates light when irradiated with radiation, and is laminated on the light emitting layer, and the light emitting device. A substrate in which a plurality of pixels including a sensor unit that generates charges by receiving light generated in a layer and a switching element for reading out the charges generated in the sensor unit; and the substrate of the light emitting layer includes: The amount of light guided in a part of the plurality of regions is laminated on the side opposite to the side on which the layers are laminated or on the side opposite to the side on which the light emitting layer is laminated, and is optically separated into a plurality of regions. Includes a light guide plate having a light guide amount larger than that of the other region other than the partial region.

  According to the radiation detector according to claim 1, the sensor unit that generates charges by receiving the light generated in the light emitting layer in the light emitting layer that generates light when irradiated with radiation, and the sensor unit A substrate on which a plurality of pixels including a switching element for reading out the electric charges generated in step 1 is formed is stacked.

  Here, in the present invention, the light emitting layer is optically separated into a plurality of regions on the side opposite to the side on which the substrate is laminated, or on the side opposite to the side on which the light emitting layer is laminated, A light guide plate in which a light guide amount in a partial region of the plurality of regions is larger than a light guide amount in a region other than the partial region is stacked.

  That is, in the present invention, the light guide plate that guides the light generated by the light emitting layer is optically separated into a plurality of regions, and the light detection sensitivity in a part of the plurality of regions is higher than that in other parts. Therefore, by executing the synchronization control process using the light guided by the partial area, it is possible to promptly detect the start of radiation irradiation while guiding the light by the other area. By performing the irradiation control process using the emitted light, saturation of the light receiving element that receives the light can be prevented.

  Thus, according to the radiation detector of claim 1, the light guide plate that guides the light generated by the light emitting layer is optically separated into a plurality of regions, and light in a part of the plurality of regions. Since the detection sensitivity is higher than that of the other parts, the synchronization control process and the irradiation control process can be performed accurately.

  Moreover, in the radiation detector according to the present invention, as described in claim 2, when the light guide plate is laminated on the light emitting layer, the light guide plate is interposed between the light emitting layer and the light guide plate, You may make it further provide the light reflection layer which passes a part and reflects light other than the said part. Thereby, there exists an effect that a synchronous control process and an irradiation control process can be exactly performed using a part of light light-emitted by the light emitting layer.

  Moreover, in the radiation detector according to the present invention, as described in claim 3, the light guide plate is divided for each of the plurality of regions, and the light guide plate and the light guide plate are laminated. You may make it further provide the barrier film interposed between members and maintaining the moisture proof property inside the said radiation detector. Thereby, there exists an effect that the moisture-proof property inside a radiation detector can be maintained.

  Moreover, in the radiation detector according to the present invention, as described in claim 4, the light guide plate has a reflectivity in the partial area which is opposite to the laminated side than in the other area. By providing a high light reflection layer, the light guide amount in a partial region of the plurality of regions may be made larger than the light guide amount in other regions other than the partial region. Thereby, there is an effect that the light guide amount in a part of the region can be easily made larger than the light guide amount in the other region.

  In the radiation detector according to the present invention, as described in claim 5, the light reflecting layer has a light quantity of light passing through a region corresponding to the partial region corresponding to the other region. The amount of light guided in a part of the plurality of regions is made larger than the amount of light guided in a region other than the part of the plurality of regions. Also good. Thereby, there is an effect that the light guide amount in a part of the region can be easily made larger than the light guide amount in the other region.

  In the radiation detector according to the present invention, as described in claim 6, a light reflection layer may be further provided on a side surface of the light guide plate. Thereby, there exists an effect that the light which injects into a light-guide plate can be efficiently condensed.

  Moreover, the radiation detector which concerns on this invention WHEREIN: As described in Claim 7, you may make it the surface of the said light guide plate on the opposite side to the laminated | stacked side be an inclined surface. Thereby, the light guide function can be improved by inclining one surface of the light guide plate.

  Further, in the radiation detector according to the present invention, as described in claim 8, the radiation detector includes an inclined surface, the inclined surface side is laminated on the inclined surface of the light guide plate, and the light detector is laminated on the light guide plate. You may make it further provide the reinforcement board which combines with a light guide plate and becomes a plate shape with the said light guide plate. Thereby, there exists an effect that the intensity | strength with respect to an external pressure can be improved with a reinforcement board.

  In the radiation detector according to the present invention, as described in claim 9, the light guide plate may be laminated on a side opposite to a radiation incident side. Thereby, similarly to the configuration of the first aspect, there is an effect that the synchronization control process and the irradiation control process can be accurately performed.

  Moreover, the radiation detector according to the present invention may further include a plurality of light receiving portions that receive the light guided by the front light guide plate as described in claim 10. Thereby, there exists an effect that the light guided by the light-receiving part with which the radiation detector was equipped can be received.

  On the other hand, in order to achieve the above object, a radiographic imaging device according to an eleventh aspect includes a radiation detector according to any one of the first to ninth aspects and the light guide plate of the radiation detector. A plurality of light-receiving portions that receive the guided light; an imaging unit that captures a radiographic image based on charges obtained by the substrate of the radiation detector; and a part of the plurality of regions. The light guided by the light guide plate is used to detect the radiation dose, and the light guided by the light guide plate through a region other than a part of the plurality of regions is irradiated with radiation. Control means for controlling to be used for detecting the start.

  Therefore, according to the radiographic image capturing apparatus of the eleventh aspect, since it operates in the same manner as the first aspect of the invention, the synchronous control process and the irradiation control process are accurately performed as in the first aspect of the invention. There is an effect that can be performed.

  A radiographic imaging apparatus according to a twelfth aspect of the present invention includes the radiation detector according to the tenth aspect, an imaging unit that captures a radiographic image based on charges obtained by the substrate of the radiation detector, Control means for controlling the photographing operation by the photographing means based on the light reception results of the plurality of light receiving portions of the radiation detector.

  Therefore, according to the radiographic imaging apparatus of the twelfth aspect, since it operates in the same manner as the first aspect of the invention, the synchronous control process and the irradiation control process are accurately performed as in the first aspect of the invention. There is an effect that can be performed.

  On the other hand, in order to achieve the above object, a program according to claim 13 is a program executed by a radiographic imaging apparatus including the radiation detector according to claim 1, wherein the computer detects the radiation detection. Detecting the start of radiation irradiation based on light guided by a part of the plurality of regions in the light guide plate of the detector, and guiding light by other portions of the plurality of regions in the light guide plate of the radiation detector. This is a program for functioning as detection means for detecting the radiation dose based on the emitted light, and control means for controlling the imaging operation by the radiographic apparatus based on the detection result by the detection means.

  Therefore, according to the program described in claim 13, since the computer can be operated in the same manner as in the invention described in claim 1, the synchronous control process and the irradiation control process are performed as in the invention described in claim 1. There is an effect that can be performed accurately.

  According to the present invention, there is an effect that the synchronization control process and the irradiation control process can be accurately performed.

It is a notch perspective view which shows the external appearance of the electronic cassette which is a radiographic imaging apparatus which concerns on embodiment. It is a cross-sectional schematic diagram which shows the structure of the 3 pixel part of the radiation detector of the electronic cassette concerning embodiment. It is a block diagram which shows the principal part structure of the electric system of the electronic cassette concerning embodiment. It is the figure which looked at the radiation detector of the electronic cassette concerning a 1st embodiment from the upper part, and is a figure showing an example of each arrangement position of field A and field B. It is the cross-sectional schematic diagram which showed typically the structure of the side cross section in the YY plane of FIG. 4 of the radiation detector of the electronic cassette concerning 1st Embodiment. (A) thru | or (C) are the cross-sectional schematic diagrams which showed typically the structure of the side cross section of the said radiation detector in each process at the time of forming the radiation detector of the electronic cassette concerning 1st Embodiment. . It is the cross-sectional schematic diagram which showed typically the structure of the side cross section of the other example of the radiation detector of the electronic cassette concerning 1st Embodiment. It is a flowchart which shows the flow of a process of the imaging | photography control processing program performed by CPU of the electronic cassette concerning 1st Embodiment. It is the figure which looked at the radiation detector of the electronic cassette concerning a 2nd embodiment from the upper part, and is a figure showing an example of each arrangement position of field A and field B. It is the cross-sectional schematic diagram which showed typically the structure of the side cross section in the YY plane of FIG. 9 of the radiation detector of the electronic cassette concerning 2nd Embodiment. It is the figure which looked at the radiation detector 3 of the electronic cassette concerning 3rd Embodiment from the upper direction, and is a figure which shows an example of each arrangement position of the area | region A and the area | region B. FIG. It is the cross-sectional schematic diagram which showed typically the structure of the side cross section in the YY plane of FIG. 11 of the radiation detector of the electronic cassette concerning 3rd Embodiment. (A) is a cross-sectional schematic diagram which shows another example of the radiation detector of the electronic cassette concerning 1st Embodiment, (B) shows another example of the radiation detector of the electronic cassette concerning 2nd Embodiment. It is a cross-sectional schematic diagram. (A) thru | or (F) is a top view which shows an example of the other structural example of the light-guide plate in the radiation detector of the electronic cassette concerning embodiment. (A) thru | or (I) is a top view which shows the other example of the arrangement position of the area | region A and the area | region B in the radiation detector of the electronic cassette concerning embodiment.

[First Embodiment]
Hereinafter, the radiographic imaging apparatus according to the first embodiment will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cut-away perspective view showing an external appearance of an electronic cassette 1 that is a radiographic imaging apparatus according to the first embodiment.

  As shown in FIG. 1, the electronic cassette 1 includes a housing 2. In order to reduce the weight of the electronic cassette 1, the housing 2 is made of, for example, carbon fiber (carbon fiber), aluminum, magnesium, bionanofiber (cellulose microfibril), or a composite material. Inside the housing 2, the radiation detector 3 and the lead plate 4 are sequentially stacked in this order along the radiation X irradiation direction. In addition, a case 5 that accommodates a cassette control unit and a power supply unit is disposed at one end inside the housing 2 at a position that does not overlap the radiation detector 3 in the radiation X irradiation direction.

  FIG. 2 is a schematic cross-sectional view illustrating a configuration of a three-pixel portion of the radiation detector 3 provided in the electronic cassette 1 according to the first embodiment.

  As shown in FIG. 2, the radiation detector 3 includes a signal output unit 11, a sensor unit 12, and a scintillator (phosphor film) 13 that are sequentially stacked on an insulating substrate 10. A plurality of signal output units 11 and sensor units 12 are arranged on the substrate 10. The scintillator 13 is formed on the upper part of the sensor unit 12 (on the side not facing the substrate 10) via a transparent insulating film 14, and a phosphor that emits light by converting radiation X such as X-rays into light is formed. Is. In the radiation detector 3, the incident radiation X is converted into light by the scintillator 13.

  The wavelength range of light emitted from the scintillator 13 is preferably a visible light range (wavelength 360 nm to 830 nm). In order to enable monochrome imaging with the radiation detector 3, the wavelength range of green is included. More preferably.

  Specifically, the phosphor used in the scintillator 13 is preferably one containing cesium iodide (CsI) when imaging using X-rays as the radiation X, and has an emission spectrum of 420 nm to 700 nm during X-ray irradiation. It is particularly preferable to use CsI (Tl) (cesium iodide to which thallium is added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

  The sensor unit 12 includes an upper electrode 15a, a lower electrode 15b, and a photoelectric conversion film 16 disposed between the upper and lower electrodes. The photoelectric conversion film 16 is made of an organic photoelectric conversion material that generates charges by absorbing light emitted by the scintillator 13.

Since it is necessary for the upper electrode 15a to cause the light generated by the scintillator 13 to enter the photoelectric conversion film 16, it is preferable that the upper electrode 15a be made of a conductive material transparent to at least the emission wavelength of the scintillator 13. 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 15a, a resistance value is likely to increase if an attempt is made to obtain a transmittance of 90% or more, so the TCO is preferred. 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 15a may have a single configuration common to all pixels, or may be divided for each pixel.

  The photoelectric conversion film 16 includes an organic photoelectric conversion material, absorbs light emitted by the scintillator 13, and generates electric charges according to the absorbed light. In this way, the photoelectric conversion film 16 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 13 are hardly absorbed by the photoelectric conversion film 16. Can be effectively suppressed as a result of being absorbed by the photoelectric conversion film 16.

  The organic photoelectric conversion material constituting the photoelectric conversion film 16 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 13 in order to absorb light emitted by the scintillator 13 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 13, but if the difference between the two is small, the light emitted by the scintillator 13 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 13 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 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 13, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 16 can be substantially maximized.

  The electromagnetic wave absorption / photoelectric conversion site in the radiation detector 3 can be constituted by an organic layer including a pair of electrodes 15a and 15b and an organic photoelectric conversion film 16 sandwiched between the electrodes 15a and 15b. 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.
Since the materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoelectric conversion film 16 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted. The photoelectric conversion film 16 may be formed by further containing fullerenes or carbon nanotubes.

  The thickness of the photoelectric conversion film 16 is preferably as large as possible in terms of absorbing light from the scintillator 13. However, when the thickness is more than a certain level, the photoelectric conversion film 16 is generated in the photoelectric conversion film 16 by a bias voltage applied from both ends of the photoelectric conversion film 16. 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 3 shown in FIG. 2, the photoelectric conversion film 16 has a single-sheet configuration shared across all pixels, but may be divided for each pixel. Moreover, the photoelectric conversion film 16 does not need to contain an organic photoelectric conversion material.

  The lower electrode 15b is composed of a thin film divided for each pixel. The lower electrode 15b can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be suitably used. Moreover, the thickness of the lower electrode 15b can be 30 nm or more and 300 nm or less, for example.

  In the sensor unit 12, by applying a predetermined bias voltage between the upper electrode 15a and the lower electrode 15b, one of charges (holes, electrons) generated in the photoelectric conversion film 16 is moved to the upper electrode 15a. The other can be moved to the lower electrode 15b. In the radiation detector 3 of this embodiment, a wiring is connected to the upper electrode 15a, and a bias voltage is applied to the upper electrode 15a via this wiring. The polarity of the bias voltage is determined so that electrons generated in the photoelectric conversion film 16 move to the upper electrode 15a and holes move to the lower electrode 15b, but this polarity is opposite. May be.

  The sensor unit 12 constituting each pixel only needs to include at least the lower electrode 15b, the photoelectric conversion film 16, and the upper electrode 15a. In order to suppress an increase in dark current, the electron blocking film 17 and the hole blocking film are used. It is preferable to provide at least one of 18, but it is particularly preferable to provide both.

  The electron blocking film 17 can be provided between the lower electrode 15b and the photoelectric conversion film 16, and when a bias voltage is applied between the lower electrode 15b and the upper electrode 15a, electrons are transferred from the lower electrode 15b to the photoelectric conversion film 16. 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 17. The material used for the electron blocking film 17 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 16, and the like. The electron affinity is 1.3 eV or more from the work function (Wf) of the adjacent electrode material. Those having a large (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 16 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 17 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 reliably exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 12. It is 50 nm or more and 100 nm or less.

  The hole blocking film 18 can be provided between the photoelectric conversion film 16 and the upper electrode 15a. When a bias voltage is applied between the lower electrode 15b and the upper electrode 15a, the hole blocking film 18 is transferred from the upper electrode 15a to the photoelectric conversion film 16. 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 18. The thickness of the hole blocking film 18 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 30 nm or less, in order to surely exhibit the dark current suppressing effect and prevent a decrease in the photoelectric conversion efficiency of the sensor unit 12. Is from 50 nm to 100 nm. The material used for the hole blocking film 18 may be selected according to the material of the adjacent electrode and the material of the adjacent photoelectric conversion film 16, and is ionized by 1.3 eV or more from the work function (Wf) of the material of the adjacent electrode. A material having a large potential (Ip) and an Ea equivalent to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 4 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.

  Of the charges generated in the photoelectric conversion film 16, when the bias voltage is set so that holes move to the upper electrode 15a and electrons move to the lower electrode 15b, the electron blocking film 17 and the hole blocking are set. What is necessary is just to arrange | position reversely the position with the film | membrane 18.

  In addition, the signal output unit 11 described above is formed on the surface of the substrate 10 facing the lower electrode 15b of each pixel. The signal output unit 11 corresponds to the lower electrode 15b, a capacitor 19 that accumulates the charges transferred to the lower electrode 15b, and a field effect thin film transistor (Thin) that converts the charges accumulated in the capacitor 19 into an electric signal and outputs the electric signal. Film Transistor (hereinafter sometimes simply referred to as a thin film transistor) 20 is formed. The region in which the capacitor 19 and the thin film transistor 20 are formed has a portion that overlaps the lower electrode 15b in a plan view. With this configuration, the signal output unit 11 and the sensor unit 12 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 3 (pixel), it is desirable that the region where the capacitor 19 and the thin film transistor 20 are formed is completely covered by the lower electrode 15b.

  The capacitor 19 is electrically connected to the corresponding lower electrode 15b through a wiring made of a conductive material penetrating an insulating film 21 provided between the substrate 10 and the lower electrode 15b. Thereby, the electric charge collected by the lower electrode 15 b can be moved to the capacitor 19.

  The thin film transistor 20 includes a gate electrode, a gate insulating film, and an active layer (channel layer) (not shown) stacked, and further, a source electrode and a drain electrode are formed on the active layer with a predetermined interval. In addition, the substrate 10 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.

  Thus, the substrate 10, the insulating film 21, the lower electrode 15b, the (electron blocking film 17,) photoelectric conversion film 16, the (hole blocking film 18,) upper electrode 15a, and the transparent insulating film 14 are sequentially stacked. Thus, a sensor substrate 22 which is a TFT substrate is formed.

  A semi-transmissive layer 23, a glass protective layer 24, a barrier film layer 25, and a light guide plate 26 are sequentially laminated on the upper surface of the scintillator 13 (the surface that does not face the sensor substrate 22).

  The semi-transmissive layer 23 according to the present embodiment transmits a part of incident light and reflects light other than the part of incident light. The semi-transmissive layer 23 is composed of a dichroic filter that can selectively transmit light having a specific wavelength. At this time, for example, light having a long wavelength component that is difficult to be refracted may be selectively transmitted. This is because light having a long wavelength component is likely to cause image blur when reflected by the semi-transmissive layer 23 and received by the sensor unit 12. Further, the semi-transmissive layer 23 may be formed by a half mirror, or a plurality of holes may be formed in a reflective material such as aluminum (Al), silver (Ag), or a hole may be partially formed. These components may be formed so that a part of the light is transmitted and light other than the part is reflected, and further, it may be formed of a diffusion plate. By providing the semi-transmissive layer 23 in the radiation detector 3, a part of the light emitted by the scintillator 13 can be incident on the light guide plate 26.

  The glass protective layer 24 is, for example, a resin film. In this embodiment, the glass protective layer 24 is provided between the semi-transmissive layer 23 and the barrier film layer 25. However, the present invention is not limited to this. You may make it the structure affixed on the film layer 25 directly.

  Part of the light emitted by the scintillator 13 passes through the semi-transmissive layer 23 and enters the glass protective layer 24. The light incident on the glass protective layer 24 passes through the glass protective layer 24, passes through the barrier film layer 25, and then enters the light guide plate 26. The light incident on the light guide plate 26 is guided through the light guide plate 26 and detected by a light detection unit 39 described later.

  FIG. 3 is a configuration diagram illustrating a main configuration of the electrical system of the electronic cassette 1 according to the first embodiment.

  As shown in FIG. 3, in the radiation detector 3 built in the electronic cassette 1, a gate line driver 30 is arranged on one side of two adjacent sides, and a signal processing unit 30A is arranged on the other side. A plurality of gate lines 31 and a plurality of data lines 32 are provided on the sensor substrate 22. The individual gate lines 31 are connected to the gate line driver 30, and the individual data lines 32 are connected to the signal processing unit 30A.

  Each thin film transistor 10 on the sensor substrate 22 is sequentially turned on in a row unit by a signal supplied from the gate line driver 30 through the gate wiring 31, and the electric charge read out by the thin film transistor 20 in the on state is converted into an electric signal. The data line 32 is transmitted and input to the signal processing unit 30A. 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 30 </ b> A includes an amplification circuit and a sample hold circuit that amplifies an input electric signal for each data wiring 32, and the electric signal transmitted through the individual data wiring 32. 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 33 is connected to the signal processing unit 30A, and image data output from the A / D converter of the signal processing unit 30A is sequentially stored in the image memory 33. The image memory 33 has a storage capacity capable of storing a predetermined number of image data, and image data obtained by imaging is stored in the image memory 33 each time a radiographic image is captured.

  The image memory 33 is connected to the cassette control unit 34. The cassette control unit 34 includes a microcomputer, and includes a CPU (Central Processing Unit) 35, a memory 36 including a ROM (Read Only Memory) and a RAM (Random Access Memory) as recording media, a flash memory, and the like. And a non-volatile storage unit 37, which collectively controls the operation of the entire electronic cassette 1.

  Further, a wireless communication unit 38 is connected to the cassette control unit 34. The wireless communication unit 38 is compatible with 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 34 can wirelessly communicate with an external device such as a console via the wireless communication unit 38, and can transmit and receive various types of information to and from the external device.

  A light detection unit 39 is connected to the cassette control unit 34. The light detection unit 39 is an optical sensor including, for example, a phototransistor, a photodiode, a photo IC, a CdS cell, or the like. In addition, the structure of the light detection part 39 is not limited to these. The light detection unit 39 converts the detection result into digital data by an A / D converter (not shown) and outputs the digital data to the cassette control unit 34. The light detector 39 may be provided inside the radiation detector 3 or may be provided inside the electronic cassette 1 separately from the radiation detector 3.

  By the way, the electronic cassette 1 detects the start of exposure when the exposure of the radiation X to the radiation detector 3 is started, and starts to capture a radiographic image. Process. Further, the electronic cassette 1 detects an irradiation amount of the radiation X to the radiation detector 3 and terminates the capturing of the radiation image based on the accumulated irradiation amount, for example, AEC (Automatic Exposure Control) for controlling the radiation image capturing operation. A control process (the above-described irradiation control process) is performed. At this time, the electronic cassette 1 according to the present embodiment guides a part of the light emitted from the scintillator 13 when the radiation detector 3 is irradiated with the radiation X by the light guide plate 26, and the light amount of the derived light. By detecting this, the start of exposure is detected and synchronous control processing is performed, or the dose is detected and AEC control processing is performed.

  By the way, in the conventional electronic cassette, when detecting light guided by one light guide plate for the entire area of the imaging target area, the imaging target area is relatively small, and the radiation in the imaging target area does not pass through the imaging target area. When the AEC control process is executed when the ratio of the unexposed area to the entire area to be imaged is relatively high, a problem is that underexposure results because a relatively large amount of radiation is detected. There was a point. In this case, it is necessary to perform re-imaging with radiation exposure, and as a result, the exposure dose of the subject increases.

  On the other hand, when executing the synchronous control process, it is necessary to detect the start of radiation irradiation as quickly as possible in order to reduce the radiation exposure amount by the subject as much as possible. On the other hand, when executing the irradiation control process, it is extremely important that the light receiving element that receives the light guided by the light guide plate does not reach the saturation detection amount when detecting the radiation dose.

  Therefore, the electronic cassette 1 according to the present embodiment causes a part of the light generated by the scintillator 13 to enter the light guide plate 26, guides the incident light into predetermined regions, and separately guides each region. It is detected and used for either the synchronous control process or the AEC control process for each area. At this time, the electronic cassette 1 according to the present embodiment is configured by a plurality of light guide regions 26a obtained by optically separating the light guide plate 26 as described later, and the light guided for each incident light guide region 26a. Using the fact that the detected light quantity corresponds to the irradiation amount of the radiation X, the synchronization control process or the AEC control process is performed based on the light quantity.

  In the electronic cassette 1 according to the present embodiment, an area in which an irradiation amount is not excessively estimated is an area A for use in AEC control processing, and an area in which the start of exposure to radiation X can be immediately detected. As regions B for use in the synchronization control process, light guide regions 26a are arranged in regions A and B, respectively. Each light guide region 26a is optically blocked, and light is guided inside each light guide region 26a.

  The method of optically blocking each light guide region 26a is known, for example, by forming a reflective film with a reflective material such as aluminum (Al) or silver (Ag) on the surface in contact with each light guide region 26a. Either method. In addition, each light guide area | region 26a which comprises the light guide plate 26 may be optically isolate | separated by the light guide plate 26 being physically divided, or it is integral and adjoins the light guide area | region 26a adjacent. It may be optically separated by providing a reflective film between them.

  FIG. 4 is a view of the radiation detector 3 of the electronic cassette 1 according to the first embodiment as viewed from above. The region A for use in the AEC control process and the region B for use in the synchronization control process. It is a figure which shows an example of each arrangement position.

  As shown in FIG. 4, the electronic cassette 1 is used for AEC control processing at the center side, considering that there is a high possibility that an imaging target region exists at the center side of the radiation detector 3 at the time of imaging. The area A is arranged, and AEC control processing is performed using the light that has passed through the area A. Further, in consideration of the fact that there is a high possibility that no part to be imaged exists at both ends of the radiation detector 3 at the time of imaging, the electronic cassette 1 has regions B for use in synchronization control processing at both ends. The synchronization control process is performed using the light that has passed through the region B. The light that has passed through the region A is incident on the light guide region 26a and is detected by the light detection unit 39, and the light that has passed through the region B is incident on the light guide region 26a different from the region A and is different from the region A. Detection is performed by the detection unit 39. With this configuration, the electronic cassette 1 separately obtains the light that has passed through the region A and the light that has passed through the region B, uses the light that has passed through the region A for the AEC control processing, and the light that has passed through the region B. Used for synchronous control processing.

  In addition, a reflection layer 41 that reflects light is provided in a region of the outer peripheral side surface of each light guide region 26a where the light detection unit 39 is not provided. The reflective layer 41 is made of a reflective material such as aluminum (Al) or silver (Ag). The reflection layer 41 prevents the light guided in each light guide region 26a from leaking outside without being detected by the light detection unit 39, and can effectively use the guided light. it can.

  Here, in the electronic cassette 1 which concerns on this embodiment, the structure for performing the AEC control process and synchronous control process which were mentioned above is demonstrated still in detail.

  FIG. 5 is a schematic cross-sectional view schematically showing a configuration of a side cross section in the YY plane of FIG. 4 of the radiation detector 3 of the electronic cassette 1 according to the first exemplary embodiment.

  As shown in FIG. 5, the radiation detector 3 includes a sensor substrate 22 and a light guide plate 26, and a scintillator 13 in which a plurality of columnar crystals 13 a are arranged is sandwiched between the sensor substrate 22 and the light guide plate 26. Configured.

  A semi-transmissive layer 23 is provided on the upper surface of the scintillator 13 (the surface opposite to the surface on which the sensor substrate 22 is laminated). Further, the semi-transmissive layer 23 is interposed between the scintillator 13 and the light guide plate 26. A glass protective layer 24 is provided. A barrier film layer 25 formed of a resin substrate is provided between the glass protective layer 24 and the light guide plate 26. Since the light guide plate 26 is composed of a plurality of light guide regions 26a, the barrier film layer 25 is formed in the radiation detector 3 in consideration of the possibility that a gap is opened between the adjacent light guide regions 26a. Provided to maintain moisture resistance.

  The semi-transmissive layer 23 is formed so that the amount of light passing through the region corresponding to the region A is reduced and the amount of light passing through the region corresponding to the region B is larger than the region corresponding to the region A. Good. Thereby, the light quantity of the light used for a synchronous control process can be increased.

  A sealing member 40 is provided between the light guide plate 26 and the sensor substrate 22 so as to surround the entire periphery of the scintillator 13. The sealing member 40 is formed of, for example, resin, and the light guide plate 26 and the light guide plate 26 so that a constant space is always formed between the light guide plate 26 and the sensor substrate 22 so that the scintillator 13 is not pressed and damaged. The sensor substrate 22 is fixed and moisture or the like is prevented from entering between the light guide plate 26 and the sensor substrate 22 (that is, the scintillator 13 or the like).

  The light guide plate 26 has a function as a light guide member that guides light emitted from the scintillator 13 in a predetermined direction, and a plurality of light guide regions 26 a are arranged so as to cover one surface of the radiation detector 3. It is configured. When the radiation X is exposed to the radiation detector 3, the radiation X incident on the scintillator 13 is converted into light, and part of the converted light is incident on the semi-transmissive layer 23, and the incident light Further, a part passes through the semi-transmissive layer 23 and enters the light guide plate 26 through the glass protective layer 24 and the barrier film layer 25.

  The light incident on the light guide region 26 a disposed in the region A of the light guide plate 26 and the light incident on the light guide region 26 a disposed in the region B of the light guide plate 26 are respectively detected by the light detection unit 39. It is detected by a separate optical sensor, converted into an electrical signal by each optical sensor, and output to the cassette control unit 34.

  Among the plurality of optical sensors, the detection sensitivity of the optical sensor that detects the light passing through the region A is lowered, and the detection sensitivity of the optical sensor that detects the light passing through the region B is set to the light passing through the region A. It may be configured to be higher than the detection sensitivity of the optical sensor to be detected. Thereby, the detection sensitivity of the light used for a synchronous control process can be made high.

In manufacturing the radiation detector 3, the following methods shown as patterns 1 and 2 can be applied.
(Pattern 1)
The scintillator 13 is formed directly on the sensor substrate 22 by vapor deposition, while the semi-transmissive layer 23 is formed on the glass protective layer 24 by coating or sticking. Further, the barrier film layer 25 is attached to one surface of the light guide plate 26. A glass protective layer 24 is bonded to the side of the scintillator 13 opposite to the sensor substrate 22 so that the semi-transmissive layer 23 is interposed therebetween, and the light guide plate 26 is interposed between the glass protective layer 24 and the barrier film layer 25 therebetween. Paste together.

(Pattern 2)
The scintillator 13 is formed directly on the sensor substrate 22 by vapor deposition, while the semi-transmissive layer 23 is formed on the glass protective layer 24 by coating or sticking. Further, the barrier film layer 25 is attached to one surface of the light guide plate 26. Then, a glass protective layer 24 is stacked on the side of the scintillator 13 opposite to the sensor substrate 22 so that the semi-transmissive layer 23 is interposed therebetween, and the light guide plate 26 is disposed so that the barrier film layer 25 is interposed between the glass protective layer 24 and the glass protective layer 24. The entire radiation detector 3 is pouched (laminated) while being stacked and pressed against each other.

(Pattern 3)
6A to 6C schematically show the configuration of the side cross section of the radiation detector in each step when the radiation detector 3 of the electronic cassette 1 according to the first embodiment is formed by the pattern 3. It is the shown cross-sectional schematic diagram. In addition, illustration of the semi-transmissive layer 23 is abbreviate | omitted in FIG. 6 (A) thru | or (C).

  As shown in FIG. 6A, when the scintillator 13 is laminated directly on the glass protective layer 24 by vapor deposition, the film thickness distribution of CsI forming the scintillator 13 in the glass protective layer 24 is not constant. The center part is formed to be thick. Considering this, as shown in FIG. 6B, the glass protective layer 24 is formed of a heat-resistant resin substrate (resin: polyimide, aramid, etc.), and the glass protective layer 24 is bent along the film thickness of CsI. As a result, the sensor substrate 22 and the scintillator 13 are uniformly adhered.

  6C, a light guide plate 26 is laminated on the upper surface of the glass protective layer 24 (the surface opposite to the surface on which the scintillator 13 is laminated), and the scintillator is formed by the light guide plate 26 and the sensor substrate 22. 13 is sandwiched. As described above, the light guide plate 26 is composed of a plurality of light guide regions 26a made of a glass material, so that the light guide plate 26 has flexibility as a whole and bends in accordance with the shape of the scintillator 13. Since the adhesion between the substrate and the vapor deposition resin substrate is good, the uniform adhesion can be further improved.

  FIG. 7 is a schematic cross-sectional view schematically showing a configuration of a side cross-section of another example of the radiation detector 3 of the electronic cassette 1 according to the first exemplary embodiment.

  As shown in FIG. 7, in the radiation detector 3 of the electronic cassette 1 according to the present embodiment, a reflective layer 42 is provided on the upper surface of the light guide plate 26 (the surface opposite to the surface on which the barrier film layer 25 is laminated). May be. By providing the reflection layer 42 on the light guide plate 26, the light emitted from the scintillator 13 and incident on the light guide plate 26 can be effectively guided to the light detection unit 39.

  The reflection layer 42 is formed of a reflection film 42a having a low reflectance in order to prevent signal saturation in the region A for use in the AEC control processing, and in the region B for use in the synchronization control processing. In order to detect the irradiation of the radiation X to the radiation detector 3 with high sensitivity, it is preferable to form the reflection film 42b having a higher reflectance than the reflection film 42a.

  In the electronic cassette 1 according to the present embodiment, the example in which the light guide plate 26 and the sensor substrate 22 are formed using a glass material has been described. However, the present invention is not limited thereto, and both the light guide plate 26 and the sensor substrate 22 are made of resin. It may be formed by. By sandwiching the scintillator 13 with a substrate made of a similar material, such as a glass substrate and a glass substrate, or a resin substrate and a resin substrate, the strength of the radiation detector 3 against an external pressure can be improved.

  Furthermore, although the light detection part 39 of the electronic cassette 1 which concerns on this embodiment demonstrated the example which detects separately the light which passed the area | region A, and the light which passed the area | region B using several similar optical sensors, respectively. However, the present invention is not limited to this, and a plurality (for example, two) of optical sensors having different detection sensitivities may be used. Specifically, an optical sensor with high detection sensitivity may be used as the optical sensor used for the synchronization control process, and an optical sensor with low detection sensitivity may be used as the optical sensor used for the AEC control process.

  Next, the electronic cassette 1 according to the present embodiment detects the start of irradiation of the radiation X using light that has passed through the region B when the radiation detector 3 starts exposure to the radiation X. A flow when the AEC control process is performed by detecting the completion of the radiation X imaging using the light that has passed through the region A while performing the radiographic image imaging will be described.

  FIG. 8 is a flowchart showing a flow of processing of the photographing control processing program executed by the CPU 35 of the electronic cassette 1 according to this embodiment, and the program is stored in advance in a predetermined area of the storage unit 37 that is a recording medium. Yes.

  A console (not shown) transmits information on a photographing execution instruction to the electronic cassette 1 based on a user operation. Then, based on receiving the information of the shooting execution instruction, the electronic cassette 1 starts the shooting control process.

  When the electronic cassette 1 receives the imaging execution instruction information via the wireless communication unit 35, in step S103, the CPU 35 acquires information indicating the irradiation amount of the radiation X for synchronous control. That is, the CPU 35 acquires information indicating the light amount of the light that has passed through the region B from the light detection unit 39, and derives the irradiation amount of the radiation X from the light amount of the light.

  In the next step 105, the CPU 35 determines whether or not the irradiation amount of the radiation X acquired in step S103 is equal to or greater than a first threshold value. The first threshold value indicates a lower limit value of the dose for recognizing that the exposure to the radiation X has started, and information indicating the lower limit value is preset and stored in a predetermined area of the storage unit 37. Has been.

  When it determines with the irradiation amount of the radiation X having become more than a 1st threshold value in step S105, CPU35 controls the electronic cassette 1 so that imaging | photography of a radiographic image may be started. At this time, after the electric charge accumulated in the capacitor 19 in each pixel of the radiation detector 3 is discharged, the accumulation operation of the electric charge in the capacitor 19 is started again, thereby starting the radiographic image capturing operation.

  When the imaging operation is started, in the next step S109, the CPU 35 acquires the irradiation amount of the radiation X for AEC control. That is, the CPU 35 acquires information indicating the light amount of the light that has passed through the region A from the light detection unit 39, and derives the irradiation amount of the radiation X from the light amount of the light.

  In step S111, the CPU 35 determines whether or not the irradiation amount of the radiation X acquired in step S109 is equal to or greater than a second threshold value. The second threshold value indicates a lower limit value of the dose for recognizing completion of radiographic image capturing, and information indicating the lower limit value is preset and stored in a predetermined area of the storage unit 37. Yes.

  If it is determined in step S111 that the irradiation amount is not equal to or greater than the second threshold value, in step S113, the CPU 35 accumulates the irradiation amount of the radiation X acquired in step S109 and proceeds to step S109. In step S113, the CPU 35 accumulates the radiation X irradiation amount, whereby the radiation X cumulative irradiation amount can be derived.

  If it is determined in step S111 that the irradiation amount (cumulative irradiation amount) is greater than or equal to the second threshold value, in step S115, the CPU 35 performs electronic processing so as to stop radiographic image capturing started in step 107 above. The cassette 1 is controlled.

  In the next step S117, the CPU 35 transmits the information on the exposure stop instruction to the console via the wireless communication unit 38.

  The CPU 35 controls the gate line driver 30 to output an ON signal to each gate wiring 31 in order line by line from the gate line driver 30 until the photographing operation is started and stopped, and is connected to each gate wiring 31. Each thin film transistor 20 is sequentially turned on line by line.

  In the radiation detector 3, when the thin film transistors 20 connected to the gate lines 31 are turned on one line at a time, the charges accumulated in the capacitors 19 one line at a time flow out to the data lines 32 as electric signals. The electric signal flowing out to each data wiring 32 is converted into digital image data by the signal processing unit 30 </ b> A and stored in the image memory 33.

  In this way, in the electronic cassette 1, the light that has passed through the region B among the light guided by the light guide plate 26 is detected, and the irradiation start of the radiation X is determined based on the detected light. Further, in the electronic cassette 1, the light that has passed through the region B among the light guided by the light guide plate 26 is detected, and the end of irradiation of the radiation X is determined based on the detected light. As a result, the synchronization control process and the AEC control process can be accurately performed.

[Second Embodiment]
Hereinafter, the electronic cassette 1A according to the second embodiment will be described in detail with reference to the accompanying drawings. In the radiation detector 3 of the electronic cassette 1 according to the first embodiment, the light guide plate 26 is configured by arranging a plurality of plate-like light guide regions 26a, but the radiation of the electronic cassette 1A according to the second embodiment. The detector 3A is configured such that a light guide plate 26A is configured by arranging a plurality of light guide regions 26b that are inclined on one side and formed in a wedge shape as a whole. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  FIG. 9 is a view of the radiation detector 3 </ b> A of the electronic cassette 1 </ b> A according to the second embodiment as viewed from above, and is a diagram illustrating an example of the arrangement positions of the region A and the region B.

  As shown in FIG. 9, the electronic cassette 1B controls the AEC control on the center side in consideration of the high possibility that the subject is present on the center side of the radiation detector 3A, as in the first embodiment. An area A to be used for processing is arranged, and AEC control processing is performed using light that has passed through the area A. Further, in consideration of the high possibility that the subject does not exist on both ends of the radiation detector 3A, the electronic cassette 1 is arranged with regions B for use in the synchronization control processing on both ends. The synchronization control process is performed using the light passing through B.

  FIG. 10 is a schematic cross-sectional view in the YY plane of FIG. 9 showing the radiation detector 3A of the electronic cassette 1A according to the second embodiment. As shown in FIG. 10, in the electronic cassette 1A according to the second embodiment, in the radiation detector 3A, as described above, a plurality of light guide regions 26b, which are glass substrates, are wedge-shaped. Is formed. Further, the upper surface of each light guide region 26b (the surface opposite to the surface on which the barrier film layer 25 is laminated) has the same shape as the top surface of the light guide region 26b, and is similarly inclined so that one surface is inclined. The reinforcing plates 43 formed in the above are laminated. At this time, the light guide region 26b and the reinforcing plate 43 are laminated so that the inclined surfaces face each other, and the upper surface of the reinforcing plate 43 (the surface opposite to the surface on which the light guiding plate 26A is laminated) and the light guide region 26b. The optical plate 26A is laminated so that the lower surface (the surface opposite to the surface on which the reinforcing plate 43 is laminated) is parallel and has a plate shape as a whole. Then, the light guide plate 26A is configured by arranging a pair of the light guide region 26b and the reinforcing plate 43 that are stacked on each other so as to cover one surface of the radiation detector 3A.

  A light detection unit 39 is provided on the expanded side surface of the wedge-shaped light guide plate 26A, and light incident on the light guide region 26b is guided in the direction of the side surface expanded in the light guide region 26b. Is detected.

  The reinforcing plate 43 may be a glass substrate formed of glass or tempered glass, or a resin substrate formed of a resin and a barrier film. However, when the sensor substrate 22 is a glass substrate, the reinforcing plate 43 is also preferably a glass substrate. When the sensor substrate 22 is a resin substrate, the reinforcing plate 43 is also preferably a resin substrate. In addition, a combination in which the thermal expansion coefficients of the sensor substrate 22 are substantially the same is preferable.

  In the electronic cassette 1B, the housing 2 has a light shielding function and natural light does not enter from the outside to the inside. However, in consideration of a case where natural light leaks from the joint of the housing 2 or the like, it is reinforced. The plate 43 may have light absorptivity (colored) so as to block the natural light. This is particularly effective when the electronic cassette 1 is an ISS system. The ISS (Irradiation Side Sampling) method is a method in which a TFT substrate is disposed on the radiation irradiation surface side of the scintillator.

  In addition, a reflective layer 44 that reflects light emitted from the scintillator 13 is provided between each light guide region 26 b and the reinforcing plate 43. The reflective layer 44 is formed of a reflective material such as aluminum (Al) or silver (Ag). Alternatively, the reflection layer 44 may be formed so as to improve the reflection performance by roughening the surface.

  The reflective layer 44 may be formed so that the reflectance differs between the region corresponding to the light guide region 26b provided in the region A and the region corresponding to the light guide region 26b provided in the region B. In this case, it is preferable that the reflectance be high in the peripheral region B used for the synchronization control processing and the reflectance be low in the central region A used for the AEC control processing. Thereby, the light used for the synchronous control process light-guided by 26 A of light-guide plates can be increased.

  Since the wedge-shaped light guide region 26b has a high light guide function, light that is discarded without being detected by the light detection unit 39 can be reduced. The wedge-shaped light guide region 26b is uneasy about impact properties and load properties, but is supplemented by a reinforcing plate 43 formed in a wedge shape to ensure impact resistance and load resistance. By overlapping a plurality of wedge-shaped glass substrates (in this embodiment, two of the light guide region 26b and the reinforcing plate 43), it is possible to improve light guide performance and maintain strength.

  It should be noted that the electronic cassette 1A according to the second embodiment starts capturing a radiographic image when the radiation X is exposed to the radiation detector 3A, and performs exposure of the radiation X when the radiographic image capturing is completed. The flow at the time of performing the imaging control process for prompting the stop is performed according to the flow shown in FIG. 8 as in the first embodiment.

[Third Embodiment]
Hereinafter, the electronic cassette 1B according to the third embodiment will be described in detail with reference to the accompanying drawings. As in the second embodiment, the radiation detector 3B of the electronic cassette 1B according to the third embodiment has a plurality of light guide regions 26b that are inclined and have a wedge shape as a whole. It is configured. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment and 2nd Embodiment, and the overlapping description is abbreviate | omitted.

  FIG. 11 is a view of the radiation detector 3 </ b> B of the electronic cassette 1 </ b> B according to the third embodiment as viewed from above, and is a diagram illustrating an example of the arrangement positions of the region A and the region B.

  As shown in FIG. 11, in the same manner as in the first embodiment, the electronic cassette 1B performs AEC control on the center side in consideration of the high possibility that an object exists on the center side of the radiation detector 3B. An area A to be used for processing is arranged, and AEC control processing is performed using light that has passed through the area A. Further, in consideration of the high possibility that the subject does not exist on the outer peripheral side in the radiation detector 3B, the electronic cassette 1 arranges the region B for use in the synchronization control processing on the outer peripheral side, The synchronization control process is performed using the light passing through B.

  FIG. 12 is a schematic cross-sectional view in the YY plane of FIG. 11 showing the radiation detector 3B of the electronic cassette 1B according to the third embodiment. As shown in FIG. 12, in the radiation detector 3B of the electronic cassette 1B according to the third embodiment, as described above, the light guide plate 26B, which is a wedge-shaped glass substrate, has a wedge shape in each of the plurality of light guide regions 26b. It is separated to become. Further, the reinforcement formed on the upper surface of each light guide region 26b (the surface opposite to the surface on which the barrier film layer 25 is laminated) is similarly formed in a wedge shape in the same shape as viewed from above on each of the light guide plates 26 and 26B. Plates 43b are stacked. At this time, in a state where the light guide region 26b and the reinforcing plate 43b are laminated, the upper surface of the reinforcing plate 43b (the surface opposite to the surface on which the light guiding region 26b is laminated) and the lower surface of the light guiding region 26b (the reinforcing plate 43b). Are laminated so that the surface on the opposite side to the surface on which the layers are laminated are parallel to each other and form a plate shape as a whole. A set of the light guide region 26b and the reinforcing plate 43b stacked on each other is arranged so as to cover one surface of the radiation detector 3B.

  As described above, the light detection unit 39 is provided on the expanded side surface of each of the wedge-shaped light guide regions 26b, and the direction of the expanded side surface of the light incident on the light guide region 26b in the light guide region 26b is provided. And is detected by the light detection unit 39. When the area A for use in the AEC control process and the area B for use in the synchronization control process are adjacent to each other, the light guided to the light guide area 26b of the area A is detected as shown in FIG. There is a possibility that the light detection unit 39 that detects the light guided to the light guide region 26b in the region B is adjacent to the light detection region 39b. It is preferable to provide a reflecting member so that the light guided to the light guide region 26b in the region A and the light guided to the light guide region 26b in the region B are not mixed.

  Since the wedge-shaped light guide region 26b has a higher light guide function than the plate-shaped light guide plate, light that is discarded without being detected by the light detection unit 39 can be reduced. The wedge-shaped light guide plate 26B is uneasy about impact properties and load properties, but is supplemented by the wedge-shaped reinforcing plates 43 and 43b to ensure impact resistance and load resistance. By overlapping a plurality of wedge-shaped glass substrates (in this embodiment, the light guide plate 26B and the reinforcing plates 43 and 43b), it is possible to improve the light guide performance and maintain the strength.

  It should be noted that the electronic cassette 1B according to the third embodiment starts capturing a radiographic image when the radiation X is exposed to the radiation detector 3A, and performs exposure of the radiation X when the radiographic image capturing is completed. The flow at the time of performing the photographing control process for prompting the stop is performed according to the flow shown in FIG. 8 as in the first embodiment and the second embodiment.

  In the first to third embodiments, the case where X-rays are used as radiation has been described. However, the present invention is not limited to this, and γ-rays and other radiation may be used.

  In the first to third embodiments, the example in which the light guided by each of the light guide plates 26 and 26A is used for either the synchronization control process or the AEC control process has been described. However, the present invention is not limited thereto. Instead, the light guided by each of the light guide plates 26, 26A may be used for any of three or more purposes including other processing.

  In the first to third embodiments, the example in which the light guide plates 26 and 26A are provided on the surface opposite to the surface on which the sensor substrate 22 of the scintillator 13 is stacked has been described. However, the present invention is not limited to this.

  FIG. 13A is a schematic cross-sectional view schematically showing a configuration of a side cross-section of another example of the radiation detector of the electronic cassette relating to the first exemplary embodiment, and FIG. 13B is a diagram showing the second exemplary embodiment. It is the cross-sectional schematic diagram which showed typically the structure of the side cross section of the other example of the radiation detector of the electronic cassette concerning.

  As shown in FIG. 13A, the light guide plate 26 may be provided on the surface of the scintillator 13 on the side where the sensor substrate 22 is laminated. In this case, the sensor substrate 22 is formed of a material that transmits light, and a barrier film layer 25 is provided on the lower surface of the sensor substrate 22 (the surface opposite to the surface on which the scintillator 13 is laminated). A light guide plate 26 is laminated on the lower surface of the film layer 25 (the surface opposite to the surface on which the sensor substrate 22 is laminated). Thereby, it is possible to prevent the light guide plate 26 from being directly irradiated with the radiation X, and to prevent the light guide plate 26 from being deteriorated.

  Similarly, as shown in FIG. 13B, the light guide plate 26A may be provided on the surface of the scintillator 13 on the side where the sensor substrate 22 is laminated. In this case, the sensor substrate 22 is formed of a material that transmits light, and a barrier film layer 25 is provided on the lower surface of the sensor substrate 22 (the surface opposite to the surface on which the scintillator 13 is laminated). A light guide plate 26A and a reinforcing plate 43 are laminated on the lower surface of the film layer 25 (the surface opposite to the surface on which the sensor substrate 22 is laminated). Thereby, the effect similar to the case of 2nd Embodiment can be acquired.

  13A and 13B, when the light guide plates 26 and 26A are stacked on the lower surface side of the sensor substrate 22 (the surface opposite to the surface on which the scintillator 13 is stacked). The semi-transmissive layer 23 is not provided, and the glass protective layer 24 is laminated on the upper surface of the scintillator 13 (the surface opposite to the surface on which the sensor substrate 22 is laminated).

  14A to 14I show the arrangement positions of the light guide regions 26a and 26b in the radiation detectors 3, 3A, and 3B of the electronic cassettes 1, 1A, and 1B according to the first to third embodiments. It is a top view which shows another example.

  FIG. 14A shows an example in which rectangular light guide regions 26a and 26b are arranged in a plurality of rows in the vertical and horizontal directions. By arranging the region A or the region B in each of the light guide regions 26a and 26b so as to match the shape of the subject, AEC control and synchronization control can be performed without depending on the shape of the subject.

  In FIG. 14B, a plurality of triangular light guide regions 26 a and 26 b are arranged in the vertical direction and the horizontal direction on both ends of the radiation detector 3, and a rectangular light guide region is provided at the center side of the radiation detector 3. In this example, 26a and 26b are arranged in one row. FIG. 14C is an example in which a plurality of triangular light guide regions 26a and 26b are arranged in the vertical direction and the horizontal direction. In these cases, as in the case of FIG. 14A, the region A or the region B is set in each of the light guide regions 26a and 26b so as to match the shape of the subject, and thus depends on the shape of the subject. AEC control and synchronization control can be performed without doing so.

  FIG. 14D shows an example in which hexagonal light guide regions 26a and 26b are arranged in a honeycomb shape. Thus, by making the light guide regions 26a and 26b hexagonal, the regions A and B can be arranged so as to match the shape of the rounded subject as much as possible.

  FIG. 14E shows an example in which a plurality of arc-shaped light guide regions 26a and 26b are arranged. Thus, by making the light guide regions 26a and 26b arcs, for example, when mammography is performed, the regions A and B can be arranged so as to match the shape of the breast as much as possible.

  15A to 15I show other arrangement positions of the areas A and B in the radiation detectors 3, 3A, and 3B of the electronic cassettes 1, 1A, and 1B according to the first to third embodiments. It is a top view which shows the example of. In FIG. 14, the arrangement position of the first color filter 25a is shown in black, and the arrangement position of the second color filter 25b is shown in white.

  As shown in FIG. 15A, when it is known that the subject exists in the central part of the radiation detectors 3, 3A, 3B, a region A is arranged in a rectangular shape in the central part, and the outer periphery thereof It is preferable to arrange the region B in the part.

  Further, as shown in FIG. 15B, when photographing the subject's lungs and intestines, the region A is arranged at a position corresponding to the lungs and a position corresponding to the intestines, and the region B is arranged on the outer periphery thereof. It is good to arrange.

  Further, as shown in FIG. 15C, when there is a high possibility that the subject exists in the central part of the radiation detectors 3, 3A, 3B, a large area A is arranged in the central part, and the outer peripheral part thereof. It is preferable to arrange both the area A and the area B in the area.

  Further, as shown in FIG. 15D, in the case of FIG. 11C, it is preferable to arrange a lot of regions A in the central portion and arrange a lot of regions B in the outer peripheral portion.

  As shown in FIG. 15E, when mammography is performed, the region A is preferably arranged at a position corresponding to the breast, and the region B is arranged at the outer periphery thereof.

  As shown in FIG. 15 (F), when the position where the subject is present is not known in the radiation detectors 3, 3A, 3B, the region A on the two diagonal lines in the radiation detectors 3, 3A, 3B. And the region B is preferably arranged on the outer periphery thereof.

  Further, as shown in FIG. 15G, in the case of FIG. 15F, the region A may be arranged only on one diagonal line. In this case, the arrangement position of the region B, that is, the region used for the synchronization control process becomes wider, and the detection sensitivity of the light used for the synchronization control process can be improved.

  Further, as shown in FIG. 15H, when the position where the subject exists in the radiation detectors 3, 3A, 3B is not known, on the two center lines on each side of the radiation detectors 3, 3A, 3B. It is preferable that the area A is arranged in the area and the area B is arranged on the outer peripheral portion thereof.

  As shown in FIG. 15 (I), when the position where the subject is present is not known in the radiation detectors 3, 3A, 3B, the regions A are set such that the adjacent light guide regions 26a, 26b are different from each other. Alternatively, any one of the regions B may be arranged.

  Note that when X-rays are exposed as radiation X, the lung field has a large amount of X-ray transmission, and therefore, a region corresponding to the lung field may be used for the synchronization control process.

  DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Electronic cassette, 2 ... Housing, 3, 3A, 3B ... Radiation detector, 4 ... Lead plate, 5 ... Case, 11 ... Signal output part, 12 ... Sensor part, 13 ... Scintillator, 14 ... Transparent insulating film, 15a ... upper electrode, 15b ... lower electrode, 16 ... photoelectric conversion film, 17 ... electron blocking film, 18 ... hole blocking film, 19 ... capacitor, 20 ... thin film transistor, 21 ... insulating film, 22 ... sensor substrate , 23 ... Semi-transmissive film, 24 ... Glass protective layer, 25 ... Barrier film layer, 26 ... Light guide plate, 26a, 26b ... Light guide region, 30 ... Gate line driver, 30A ... Signal processing unit, 31 ... Gate wiring, 32 Data wiring, 33 ... Image memory, 34 ... Cassette control unit, 35 ... CPU, 36 ... Memory, 37 ... Storage unit, 38 ... Wireless communication unit, 39 ... Light detection unit, 40 ... Sealing member, 41 ... Reflection , 42 ... reflective layer, 43,43B ... reinforcing plate 44 ... reflective layer.

Claims (13)

A light emitting layer that generates light when irradiated with radiation;
A substrate on which a plurality of pixels including a sensor unit that is stacked on the light emitting layer and generates charges by receiving light generated in the light emitting layer and a switching element for reading out the charges generated in the sensor unit are formed. When,
The light emitting layer is laminated on a side opposite to the side on which the substrate is laminated, or on a side opposite to the side on which the light emitting layer is laminated, and is optically separated into a plurality of regions, A light guide plate in which the light guide amount in some regions is greater than the light guide amount in other regions other than the some regions;
Radiation detector equipped with. When the light guide plate is laminated on the light emitting layer, the light guide plate further includes a light reflecting layer that is interposed between the light emitting layer and the light guide plate, allows a part of the light to pass therethrough and reflects light other than the part. The radiation detector according to claim 1. The light guide plate is divided for each of the plurality of regions,
The radiation according to claim 1, further comprising a barrier film interposed between the light guide plate and a member on which the light guide plate is laminated to maintain moisture resistance inside the radiation detector. Detector. The light guide plate is provided on a side opposite to the laminated side by providing a light reflecting layer having a higher reflectance in the partial area than in the other area, so that in the partial area of the plurality of areas. The radiation detector according to any one of claims 1 to 3, wherein a light guide amount is larger than a light guide amount in a region other than the partial region. The light reflecting layer is configured such that a light amount of light passing through a region corresponding to the partial region is greater than a light amount of light passing through a region corresponding to the other region. The radiation detector according to claim 2, wherein a light guide amount in a part of the region is larger than a light guide amount in a region other than the part region. The radiation detector according to any one of claims 1 to 5, further comprising a light reflection layer on a side surface of the light guide plate. The radiation detector according to any one of claims 1 to 6, wherein the light guide plate has an inclined surface on a side opposite to the laminated side. A reinforcing plate that is provided with an inclined surface, the inclined surface side is laminated on the inclined surface of the light guide plate, and is combined with the light guide plate in a state of being laminated on the light guide plate. The radiation detector according to claim 7. The radiation detector according to any one of claims 1 to 8, wherein the light guide plate is laminated on a side opposite to a radiation incident side. The radiation detector according to any one of claims 1 to 9, further comprising a plurality of light receiving portions that receive light guided by the light guide plate. The radiation detector according to any one of claims 1 to 9,
A plurality of light receiving portions for receiving light guided by the light guide plate of the radiation detector;
An imaging means for taking a radiographic image based on the electric charge obtained by the substrate of the radiation detector;
Light that has passed through a part of the plurality of regions and is guided by the light guide plate is used to detect a radiation dose, and passes through a region other than a part of the plurality of regions to guide the light. Control means for controlling the light guided by the light plate to be used for detecting the start of radiation irradiation;
A radiographic imaging apparatus comprising: A radiation detector according to claim 10;
An imaging means for taking a radiographic image based on the electric charge obtained by the substrate of the radiation detector;
Control means for controlling a photographing operation by the photographing means based on light reception results of the plurality of light receiving units of the radiation detector;
A radiographic imaging apparatus comprising: A program executed by a radiographic image capturing apparatus including the radiation detector according to claim 1,
Computer
While detecting the start of radiation irradiation based on the light guided by a part of the plurality of regions in the light guide plate of the radiation detector, and the other part of the plurality of regions in the light guide plate of the radiation detector Detecting means for detecting the radiation dose based on the light guided by
Control means for controlling an imaging operation by the radiographic imaging device based on a detection result by the detection means;
Program to function as.

Images