Portable radiographic image capturing device

A portable radiographic image capturing device includes an image capturing unit, a control unit, and a connecting member. The image capturing unit is formed in the shape of a flat plate, captures a radiographic, and includes a radiation detector that outputs electric signals expressing a captured radiographic image, the image capturing unit being able to capture a radiographic image from either an obverse side or a reverse side of the flat plate. The control unit includes a controller that controls image capturing operations of the radiation detector. The connecting member connects the image capturing unit and the control unit such that both units can be opened and closed between an unfolded state, in which the both units are lined-up next to one another, and a housed state, in which the both units are folded-up so as to be superposed one on another.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2009-227392 filed on Sep. 30, 2009, and is also based on Japanese Patent Application No. 2010-187583 filed on Aug. 24, 2010. The disclosures of these applications are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a portable radiographic image capturing device that captures a radiographic image expressed by irradiated radiation.

2. Related Art

Radiation detectors such as Flat Panel Detectors (FPDs), in which a radiation-sensitive layer is disposed on a Thin Film Transistor (TFT) active matrix substrate and that detect irradiated radiation such as X-rays or the like and output electric signals expressing the radiographic image expressed by the detected radiation, and the like have been put into practice in recent years. As compared with a conventional imaging plate, a radiation detector has the advantages that images can be confirmed immediately, and even video images can be confirmed.

Portable radiographic image capturing devices (hereinafter also called electronic cassettes), that incorporate a radiation detector therein and store radiographic image data outputted from the radiation detector, also are being put into practice. Because the electronic cassette has excellent portability, images of a patient can be captured while the patient lies as is on a stretcher or a bed, and it is also easy to adjust the region to be captured by changing the position of the electronic cassette. Therefore, even situations in which images of a patient who cannot move are captured can be dealt with flexibly.

It is generally known that the electrical characteristics of a radiation detector change due to a rise in temperature. Further, heat dissipation and cooling are extremely important in order to improve normal operation and durability of the electric parts.

In Japanese Patent Application Laid-Open (JP-A) No. 2009-80103, the inventors disclose a technique of structuring an electronic cassette such that electronic parts that generate heat and a radiation detector can be separated. In this technique, the electronic cassette is structured by a cassette main body that incorporates a radiation detector therein, and a control unit that is freely detachable from and can be separated from the cassette main body, and that supplies power to the radiation detector, and that controls the radiation detector and receives image information.

JP-A No. 2002-311526 discloses a technique in which a portion of a casing of an electronic cassette can be opened and closed, and a unit part, that includes a radiation detector and that is made into a unit, is structured so as to be removable.

By using the technique disclosed in JP-A No. 2009-80103, the control unit is structured so as to be able to be separated from the cassette main body. By using the technique disclosed in JP-A No. 2002-311526, a portion of the casing of the electronic cassette can be opened and closed, and the unit part is structured so as to be removable. The section that generates heat can thereby be separated from the radiation detector.

However, in these techniques, because a portion must be physically separated, the operability is poor. Further, these techniques are not techniques that improve the heat dissipating and cooling efficiency of the electronic cassette itself.

SUMMARY

In view of the above-described circumstances, the present invention provides a portable radiographic image capturing device that improves the cooling effect while suppressing a deterioration in operability.

An aspect of the present invention is a portable radiographic image capturing device having: an image capturing unit that is formed in the shape of a flat plate, and captures a radiographic image expressed by irradiated radiation, and has a radiation detector that outputs electric signals expressing a captured radiographic image, the image capturing unit being able to capture a radiographic image by radiation irradiated from either an obverse side or a reverse side of the flat plate; a control unit having a controller that controls image capturing operations of the radiation detector; and a connecting member that connects the image capturing unit and the control unit such that the image capturing unit and the control unit can be opened and closed between an unfolded state, in which the image capturing unit and the control unit are lined-up next to one another, and a housed state, in which the image capturing unit and the control unit are folded-up so as to be superposed one on another.

In accordance with this aspect, the image capturing unit and the control unit are connected by the connecting member so as to be able to open and close between the unfolded state and the housed state. Therefore, deterioration in the operability at the time of setting the image capturing unit and the control unit in the unfolded state in order to physically separate them is suppressed. Further, the cooling effect can be improved by setting the image capturing unit and the control unit in the unfolded state.

In the present aspect, the portable radiographic image capturing device may further have a detecting section that detects an opened/closed state of the image capturing unit and the control unit, wherein, on the basis of results of detection by the detecting section, the controller may control the portable radiographic image capturing device to carry out still image capturing if the opened/closed state of the image capturing unit and the control unit is the housed state, and may control the portable radiographic image capturing device to carry out video image capturing if the opened/closed state is the unfolded state.

In the present aspect, the portable radiographic image capturing device may further have an accepting section that accepts an image capturing instruction for still image capturing also if the opened/closed state of the image capturing unit and the control unit is the unfolded state, wherein, if the accepting section accepts an image capturing instruction for still image capturing, the controller may control the portable radiographic image capturing device to carry out still image capturing also in the unfolded state.

In the present aspect, at the radiation detector, a charge generating layer, at which charges are generated due to radiation being irradiated, and a substrate, that accumulates the charges generated at the charge generating layer and at which are formed switch elements for reading-out the charges, may be layered, and the radiation detector may be incorporated within the image capturing unit such that, in the housed state, the charge generating layer is at a surface side that opposes the control unit.

The radiation detector may include a substrate and a conversion layer that converts radiation irradiated onto the substrate into light, and the charges may be generated at the charge generating layer due to the light converted from the radiation at the conversion layer.

The charge generating layer may include an organic photoelectric conversion material.

The radiation detector may be formed at a substrate that contains plastic resin, aramid, bio-nanofibers, or flexible glass.

In the present aspect, the connecting member may contain therein an amplifying circuit that amplifies the electric signals outputted from the radiation detector.

In the present aspect, the control unit may include a radio communication section that carries out radio communication with an external device.

In the present aspect, a surface of the control unit may be formed to have convex and concave shapes.

In the present aspect, the control unit may have a display section at a surface that opposes the image capturing unit in the housed state.

Thus, the radiographic image capturing device of the present aspect can improve the cooling effect while suppressing a deterioration in operability.

DETAILED DESCRIPTION

Perspective views showing the structure of an electronic cassette10relating to an exemplary embodiment are shown inFIG. 1andFIG. 2.

As shown inFIG. 1, at the electronic cassette10, an image capturing unit12and a control unit14are connected by a hinge16so as to be able to open and close. The image capturing unit12is shaped as a flat plate, and incorporates a radiation detector20(seeFIG. 3) therein, and captures a radiographic image by irradiated radiation. The control unit14incorporates therein a controller50that controls the image capturing operations of the radiation detector20.

Due to one of the image capturing unit12and the control unit14being rotated around the hinge16with respect to the other, the image capturing unit12and the control unit14can be opened and closed between an unfolded state (FIG. 2) in which the image capturing unit12and the control unit14are lined-up next to one another, and a housed state (FIG. 1) in which the image capturing unit12and the control unit14are folded-up so as to be superposed one on another.

In the present exemplary embodiment, the image capturing unit12and the control unit14are made to be the same height in order to eliminate a step between the image capturing unit12and the control unit14in the unfolded state (FIG. 2).

A display section19A and an operation panel19B are provided at the surface of the control unit14which surface faces the image capturing unit12in the housed state. The display section19A has a display device that can display images and the like. The operation panel19B has various types of buttons such as a cross key, a ten key, and the like.

A sectional view showing the schematic structure of the electronic cassette10is shown inFIG. 3.

The radiation detector20, that captures a radiographic image expressed by irradiated radiation and outputs electric signals expressing the captured radiographic image, is incorporated in the image capturing unit12.

The controller50that controls the image capturing operations of the radiation detector, and a power source section70that supplies electric power to the controller50, are incorporated in the control unit14.

The radiation detector20and the controller50are connected by a connection wire44that is provided via the hinge16.

An opening/closing sensor45, that detects the opened/closed state of the image capturing unit12and the control unit14, is provided at the hinge16. The opening/closing sensor45may detect the opened/closed state by detecting a change in the magnetic field due to the opening or closing of the image capturing unit12and the control unit14by combining, for example, a small-sized magnet and a Hall sensor. Or, the opening/closing sensor45may be an angle sensor that detects the angle of the opening/closing, or may be plural mechanical switches that are disposed such that combinations of the on and off states change in accordance with the open/closed state.

Because the image capturing unit12and the control unit14can be opened and closed by the hinge16, bending or bending stress is constantly applied to the hinge16portion of the connection wire44, and it is easy for disconnection or breakage to arise. Therefore, in the present exemplary embodiment, the connection wire44is formed by, for example, a flexible printed substrate or the like. As shown inFIG. 4, the connection wire44is wound plural times around a rotation shaft16A of the hinge16, that supports the image capturing unit12and the control unit14such that they can be opened and closed, so as to form a cylindrical tube portion44A. Tape is wound on the outer periphery thereof so as to hold and fix the cylindrical tube portion44A. Further, the both sides of the cylindrical tube portion44A of the connection wire44are respectively wound plural times around the rotation shaft16A spirally and with leeway, and are led-out to the image capturing unit12and the control unit14respectively.

Due thereto, in a case in which the image capturing unit12is opened or closed, the connection wire44rotates along the rotation shaft16A. Because the both sides of the cylindrical tube portion44A of the connection wire44are respectively wound with leeway around the rotation shaft16A, the connection wire44very flexibly follows the opening or closing of the image capturing unit12, and the connection wire44does not break.

The radiation detector20relating to the present exemplary embodiment is described next with reference toFIG. 5andFIG. 6.FIG. 5is a sectional view schematically showing the structure of the radiation detector20relating to the present exemplary embodiment.FIG. 6is a plan view showing the structure of the radiation detector20.

As shown inFIG. 5, the radiation detector20has a TFT substrate26at which switch elements24such as thin film transistors (TFTs) or the like are formed on an insulating substrate22.

A scintillator layer28, that converts incident radiation into light, is formed on the TFT substrate26as an example of a radiation converting layer that converts incident radiation.

For example, CsI:Tl or GOS (Gd2O2S:Tb) can be used as the scintillator layer28. Note that the scintillator layer28is not limited to these materials.

For example, a glass substrate, any of various types of ceramic substrates, or a resin substrate can be used as the insulating substrate22. Note that the insulating substrate22is not limited to these materials.

Photoconductive layers30, that generate charges due to the light converted by the scintillator layer28being incident thereon, are disposed between the scintillator layer28and the TFT substrate26. Bias electrodes32for applying bias voltage to the photoconductive layers30are formed on the scintillator layer28side surfaces of the photoconductive layers30.

The photoconductive layer30includes an organic photoelectric conversion material, absorbs light that is emitted from the scintillator layer28, and generates charges that correspond to the absorbed light. The photoconductive layer30, that includes an organic photoelectric conversion material in this way, has a sharp absorption spectrum in the visible range, and there is hardly any absorption by the photoconductive layer30of electromagnetic waves other than the light emitted by the scintillator28, and noise, that is generated by radiation such as X-rays or the like being absorbed at the photoconductive layer30, can be effectively suppressed.

In order to most efficiently absorb the light that is emitted at the scintillator layer28, it is preferable that the absorption peak wavelength of the organic photoelectric conversion material that structures the photoconductive layer30be nearer to the emission peak wavelength of the scintillator layer28. It is ideal that the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength of the scintillator layer28coincide, but if the difference therebetween is small, the light emitted from the scintillator layer28can be absorbed sufficiently. Specifically, it is preferable that the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength, with respect to radiation, of the scintillator layer28be within 10 nm, and it is more preferable for the difference to be within 5 nm.

Examples of organic photoelectric conversion materials that can satisfy such a condition are, for example, quinacridone organic compounds and phthalocyanine organic compounds. For example, the absorption peak wavelength in the visible range of quinacridone is 560 nm. Therefore, if quinacridone is used as the organic photoelectric conversion material and CsI(Tl) is used as the material of the scintillator layer28, the difference in the peak wavelengths can be made to be within 5 nm, and the amount of charges generated at the photoconductive layer30can be made to be substantially the maximum.

Charge collecting electrodes34, that collect the charges generated at the photoconductive layers30, are formed at the TFT substrate26. At the TFT substrate26, the charges collected at the respective charge collecting electrodes34are read-out by the switch elements24.

As shown inFIG. 6, the charge collecting electrodes34are disposed in a two-dimensional form on the TFT substrate26. In correspondence therewith, the switch elements24are disposed in a two-dimensional form at the insulating substrate22.

Plural gate lines40that extend in a given direction (the row direction) and are for turning the respective switch elements24on and off, and plural data lines42that extend in a direction (the column direction) orthogonal to the gate lines40and are for reading-out the charges via the switch elements24that are in on states, are provided at the TFT substrate26.

A smoothing layer38for smoothing the top of the TFT substrate26is provided on the TFT substrate26. Further, an adhesive layer39for adhering the scintillator layer28to the TFT substrate26, is formed on the smoothing layer38between the TFT substrate26and the scintillator layer28.

Sensor portions37that structure respective pixel portions36at the radiation detector20can be structured by a bias electrode32and a charge collecting electrode34that form a pair, and an organic layer that contains the organic photoconductive layer30that is sandwiched between the bias electrode32and the charge collecting electrode34. More specifically, this organic layer can be formed by the stacking of or the combining of a region that absorbs electromagnetic waves, a photoelectric conversion region, an electron transport region, a hole transport region, an electron blocking region, a hole blocking region, a crystallization preventing region, electrodes, an interlayer contact improving region, and the like.

It is preferable that the organic layer contain an organic p-type compound or an organic n-type compounds.

An organic p-type semiconductor (compound) is a donor organic semiconductor (compound) exemplified mainly by hole-transporting organic compounds, and means an organic compound that has the property that it easily donates electrons. More specifically, an organic p-type semiconductor (compound) means, when two organic materials are used by being made to contact one another, the organic compound whose ionization potential is smaller. Accordingly, any organic compound can be used as the donor organic compound, provided that it is an electron-donating organic compound.

An organic n-type semiconductor (compound) is an accepter organic semiconductor (compound) exemplified mainly by electron-transporting organic compounds, and means an organic compound that has the property that it easily accepts electrons. More specifically, an organic n-type semiconductor (compound) means, when two organic compounds are used by being made to contact one another, the organic compound whose electron affinity is greater. Accordingly, any organic compound can be used as the accepter organic compound, provided that it is an electron-accepting organic compound.

Materials that can be used as the organic p-type semiconductor and the organic n-type semiconductor, and the structure of the photoconductive layer30, are described in detail in JP-A No. 2009-32854, and therefore, description thereof is omitted.

Here, it suffices for the sensor portion37that structures each pixel portion36to include at least the charge collecting electrode34, the photoconductive layer30and the bias electrode32. However, in order to suppress an increase in dark current, as shown inFIG. 7, it is preferable that the sensor portion37be provided with at least one of an electron blocking film33and a hole blocking film31, and it is more preferable that the sensor portion37be provided with the both.

The electron blocking film33can be provided between the charge collecting electrode34and the photoconductive layer30. The electron blocking film33can suppress the injection of electrons from the charge collecting electrode34into the photoconductive layer30and an increase in dark current, when bias voltage is applied between the charge collecting electrode34and the bias electrode32.

An electron-donating organic material can be used for the electron blocking film33.

It suffices to select the material, that is actually used for the electron blocking film33, in accordance with the material of the electrode adjacent thereto, the material of the photoconductive layer30adjacent thereto, and the like. It is preferable that the material have an electron affinity (Ea) that is 1.3 eV or more greater than the work function (Wf) of the material of the electrode adjacent thereto, and have an ionization potential (Ip) that is equal to or smaller than the ionization potential of the material of the photoconductive layer30adjacent thereto. Materials that can be used as this electron-donating organic material are described in detail in JP-A No. 2009-32854, and therefore, description thereof is omitted.

In order to reliably exhibit a dark current suppressing effect and to prevent a decrease in the photoelectric conversion efficiency of the sensor portion37, it is preferable that the thickness of the electron blocking film33be from 10 nm to 200 nm, and more preferable that the thickness be from 30 nm to 150 nm, and particularly preferable that the thickness be from 50 nm to 100 nm.

The hole blocking film31can be provided between the photoconductive layer30and the bias electrode32. The hole blocking film31can suppress the injecting of holes from the bias electrode32into the photoconductive layer30and an increase in dark current, when bias voltage is applied between the charge collecting electrode34and the bias electrode32.

An electron-accepting organic material can be used for the hole blocking film31.

In order to reliably exhibit a dark current suppressing effect and to prevent a decrease in the photoelectric conversion efficiency of the sensor portion37, it is preferable that the thickness of hole blocking film31be from 10 nm to 200 nm, and more preferable that the thickness be from 30 nm to 150 nm, and particularly preferable that the thickness be from 50 nm to 100 nm.

It suffices to select the material, that is actually used for the hole blocking film31, in accordance with the material of the electrode adjacent thereto, the material of the photoconductive layer30adjacent thereto, and the like. It is preferable that the material have an ionization potential (Ip) that is 1.3 eV or more greater than the work function (Wf) of the material of the electrode adjacent thereto, and have an electron affinity (Ea) that is equal to or greater than the electron affinity of the material of the photoconductive layer30adjacent thereto. Materials that can be used as this electron-accepting organic material are described in detail in JP-A No. 2009-32854, and therefore, description thereof is omitted.

The structure of the switch element24that is formed at the TFT substrate26relating to the present exemplary embodiment is shown schematically inFIG. 8.

The switch element24is formed on the insulating substrate22so as to correspond to the charge collecting electrode34. The region at which the switch element24is formed has, in plan view, a portion that is superposed with the charge collecting electrode34. Due to such a structure, the storage capacitor68, the switching element24and the sensor portion72at each pixel portion are superposed in the thickness direction, and the storage capacitor68, the switch element24and the sensor portion72can be disposed in a small surface area.

The switching element24is electrically connected to the corresponding charge collecting electrode34, via wiring of an electrically-conductive material that is formed so as to pass-through an insulating film27A that is provided between the insulating substrate22and the charge collecting electrode34. Due thereto, the charges collected at the charge collecting electrode34can be moved to the switch element24.

At the switch element24, a gate electrode24A, a gate insulating film27B and an active layer (channel layer)24B are layered, and further, the switch element24is structured as a thin-film transistor at which a source electrode24C and a drain electrode24D are formed on the active layer24B with a predetermined interval therebetween. At the radiation detector20, the active layer24B is formed of an amorphous oxide. As the amorphous oxide that structures the active layer24B, oxides containing at least one of In, Ga and Zn (e.g., In—O types) are preferable, oxides containing at least two of In, Ga and Zn (e.g., In—Zn—O types, In—Ga—O types, Ga—Zn—O types) are more preferable, and oxides containing In, Ga and Zn are particularly preferable. As an In—Ga—Zn—O type amorphous oxide, amorphous oxides whose composition in a crystal state is expressed by InGaO3(ZnO), (where m is a natural number of less than 6) are preferable, and in particular, InGaZnO4is more preferable.

If the active layer24B of the switch element24is formed by an amorphous oxide, radiation such as X-rays and the like is not absorbed, or even if absorbed, the absorbed amount will be extremely small. Therefore, the occurrence of noise at the signal outputting section14can be effectively suppressed.

Here, both the amorphous oxide that structures the active layer24B of the switch element24and the organic photoelectric conversion material that structures the above-described photoconductive layer30can be formed as films at low temperatures. Accordingly, the insulating substrate22is not limited to a highly heat-resistant substrate such as a semiconductor substrate, a quartz substrate, a glass substrate or the like, and a flexible substrate of plastic or the like, and aramid and bio-nanofibers can be used. Specifically, flexible substrates of polyesters such as polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate and the like, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, poly(chlorotrifluoroethylene), and the like can be used. By using a flexible substrate made of such a plastic, the radiation detector20can be made to be lightweight, which is favorable for, for example, carrying the electronic cassette10, and the like.

Further, an insulating layer for ensuring the insulating ability, a gas barrier layer for preventing the transmission of moisture and oxygen, an undercoat layer for improving the flatness and the adhesiveness with the electrodes and the like may be provided at the insulating substrate22.

High-temperature processes of 200° or more can be applied to aramid. Therefore, the transparent electrode material can be hardened at a high temperature and made to have low resistance, and further, automatic packaging of a driver IC, including a solder reflow step, also can be handled. Moreover, because the coefficient of thermal expansion of aramid is near to those of ITO (indium tin oxide) and glass substrates, there is little warping after manufacture, and the substrate is difficult to break. In addition, as compared with a glass substrate and the like, a thin substrate can be formed by using aramid. Note that the insulating substrate22may be formed by layering an ultra-thin glass substrate and aramid.

Bio-nanofibers are fibers in which a cellulose microfibril bundle (bacteria cellulose) that can produce bacteria (acetic acid bacterium, Acetobacter Xylinum), and a transparent resin are compounded. The cellulose microfibril bundle has a width of 50 nm which is a size of 1/10 with respect to the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. By impregnating and hardening a transparent resin, such as acrylic resin, epoxy resin or the like, in bacteria cellulose, bio-nanofibers that contain up to 60 to 70% fiber while still exhibiting light transmittance of about 90% at a wavelength of 500 nm, are obtained. Bio-nanofibers have a low coefficient of thermal expansion (3 to 7 ppm) that is comparable to that of silicon crystal, have strength (460 MPa) to the same extent as that of steel, have high elasticity (30 GPa), and are flexible. Therefore, the insulating substrate22can be formed to be thin as compared with a glass substrate or the like.

The TFT substrate26is, as shown inFIG. 6, in plan view, formed in the shape of a quadrilateral having four sides at the outer edge. Specifically, the TFT substrate26is rectangular.

A connection terminal42, to which the individual gate lines40and the individual data lines42are connected, is disposed at one side at the peripheral end portion of the TFT substrate26as seen in plan view.

The connection terminal42is connected to the controller50via the connection wire44.

Radiation may be irradiated onto the radiation detector20from the obverse side thereof at which the scintillator layer28is adhered, or radiation may be irradiated from the TFT substrate26side (the reverse side). At the radiation detector20, in a case in which radiation is irradiated from the obverse side, light is emitted more strongly at the top surface side (the side opposite the TFT substrate26) of the scintillator layer28. In a case in which radiation is irradiated from the reverse side, radiation that is transmitted through the TFT substrate26is incident on the scintillator layer28, and the TFT substrate26side of the scintillator layer28emits light more strongly. Charges are generated at the respective photoconductive layers30due to the light that is generated at the scintillator layer28. Therefore, at the radiation detector20, in the case in which radiation is irradiated from the obverse side, the radiation is not transmitted through the TFT substrate26. Therefore, the sensitivity to radiation can be designed to be higher in the case in which radiation is irradiated from the obverse side than in the case in which radiation is irradiated from the reverse side. Further, in the case in which radiation is irradiated from the reverse side, the light-emitting positions of the scintillator layer28with respect to the respective photoconductive layers30are closer than in the case in which radiation is irradiated from the obverse side. Therefore, the resolution of the radiographic image obtained by image capturing is higher in the case in which radiation is irradiated from the reverse side.

The radiation detector20is incorporated in the image capturing unit12such that, in the housed state as shown inFIG. 3, the scintillator layer28is at the control unit14side and the TFT substrate26is at the outer side (the side opposite the control unit14side). In the housed state, the surface of the image capturing unit12that is the outer side is an irradiated surface18A for reverse irradiation (seeFIG. 1) in which radiation is irradiated onto the radiation detector20from the reverse side, and the surface facing the control unit14is an irradiated surface18B for obverse irradiation (seeFIG. 2) in which radiation is irradiated onto the radiation detector20from the obverse side.

A block diagram showing the schematic structure of the controller50relating to the present exemplary embodiment is shown inFIG. 9.

As shown inFIG. 9, the controller50has a gate line driver52, a signal processing section54, an image memory56, a cassette controller58, and a radio communication section60.

The respective switch elements24(seeFIG. 5andFIG. 6) are turned on in order in units of rows by signals that are supplied from the gate line driver52via the gate lines40. The charges read-out by the switch elements24that have been turned on are transferred to the data lines42as electric signals, and are inputted to the signal processing section54. Due thereto, the charges are read-out in order in units of rows, and a two-dimensional radiographic image can be acquired.

Although not illustrated, the signal processing section54has, for each of the individual data lines42, an amplifying circuit, that amplifies the inputted electric signal, and a sample/hold circuit. After the electric signals transferred through the individual data lines42are amplified at the amplifying circuits, the signals are held in the sample/hold circuits. Further, a multiplexer and an A/D (analog/digital) converter are connected in that order to the output sides of the sample/hold circuits. The electric signals held in the individual sample/hold circuits are inputted in order (serially) to the multiplexer, and are converted into digital image data by the A/D converter.

The image memory56is connected to the signal processing section54. The image data, that is outputted from the A/D converter of the signal processing section54, is stored in order in the image memory56. The image memory56has a storage capacity that can store a predetermined number of frames of image data. Each time that capturing of a radiographic image is carried out, the image data obtained by the image capturing is successively stored in the image memory56.

The image memory56is connected to the cassette controller58. The cassette controller58is structured by a microcomputer, and has a Central Processing Unit (CPU)58A, a memory58B including a ROM and a RAM, and a non-volatile storage58C formed by a flash memory or the like. The cassette controller58controls the operations of the entire electronic cassette10.

The radio communication section60is connected to the cassette controller58. The radio communication section60corresponds to wireless Local Area Network (LAN) standards exemplified by Institute of Electrical and Electronics Engineers (IEEE) 802.11a/b/g or the like. The radio communication section60controls the transfer of various types of information to and from external devices by radio communication. The cassette controller58can, via the radio communication section60, communicate by radio with an external device that controls the overall radiographic image capturing such as a console or the like, and can transmit and receive various types of information to and from the console. The cassette controller58stores various types of information (data), such as image capturing conditions, patient information, and the like that are received from the console via the radio communication section60, and starts reading-out of the charges on the basis of the image capturing conditions.

The display section19A, the operation panel19B, and the opening/closing sensor45are respectively connected to the cassette controller58. The cassette controller58can control the display of various types of information on the display section19A, and can know of the contents of operation with respect to the operation panel19B and the opened/closed state of the image capturing unit12and the control unit14.

As mentioned above, the power source section70is provided at the electronic cassette10. The above-described various types of circuits and respective elements (the display section19A, the operation panel19B, the opening/closing sensor45, the gate line driver52, the signal processing section54, the image memory56, the radio communication section60, and the microcomputer that functions as the cassette controller58), are operated by electric power supplied from the power source section70. So that the portability of the electronic cassette10is not adversely affected, the power source section70incorporates therein a battery (a chargeable secondary battery) and supplies electric power from the charged battery to the various types of circuits and elements. Note that illustration of the wires that connect the power source section70with the various types of circuits and respective elements is omitted fromFIG. 9.

Operation of the electronic cassette10relating to the present exemplary embodiment is described next.

As shown inFIG. 1andFIG. 3, the electronic cassette10is transported in the housed state in which the image capturing unit12and the control unit14are folded-up and superposed one on another.

On the other hand, when a radiographic image is to be captured, the electronic cassette10is set in the unfolded state in which the image capturing unit12and the control unit14are lined-up next to one another as shown inFIG. 2. Further, the electronic cassette10receives patient information from the console via the radio communication section60. In response to the reception of the patient information, the cassette controller58displays, on the display section19A, information (e.g., the name or ID of the patient) relating to the patient that is based on the received patient information. In this way, at the electronic cassette10relating to the present exemplary embodiment, because the name or ID is displayed on the display section19A, the radiologic technician can reliably confirm whether or not there is mistaken identification of the patient on whom radiographic image capturing is about to be carried out, by, for example, the radiologic technician confirming the name with the patient himself/herself, and comparing the confirmed name with the name displayed on the screen.

When the electronic cassette10is in the housed state, capturing of still images can be carried out. When the electronic cassette10is in the unfolded state, capturing of video images can be carried out.

In a case in which the radiologic technician is to carry out capturing of a still image after completing confirmation of the patient's name, as shown inFIG. 10, the radiologic technician sets the electronic cassette10in the housed state and disposes the electronic cassette10such that there is an interval between the electronic cassette10and a radiation generating device80that generates radiation, and places region B that is the object of image capturing of the patient on the irradiated surface18A. In a case of capturing video images, as shown inFIG. 11, the radiologic technician sets the electronic cassette10in the unfolded state and disposes the electronic cassette10such that there is an interval between the electronic cassette10and the radiation generating device80, and places the region B that is the object of image capturing of the patient on the irradiated surface18B.

On the basis of the results of detection of the opening/closing sensor45, the cassette controller58grasps the opened/closed state of the image capturing unit12and the control unit14. If the state is the housed state, the image capturing mode is a still image capturing mode in which capturing of still images is possible. If the state is the unfolded state, the image capturing mode is a video image capturing mode in which capturing of video images is possible. The cassette controller58gives notice of the image capturing mode to the console via the radio communication section60.

At the console, setting of image capturing conditions that correspond to the notified image capturing mode becomes possible, and the image capturing conditions are set by the radiologic technician. After setting of the image capturing conditions is completed, the console transmits image capturing condition information, that expresses the set image capturing conditions, to the electronic cassette10by radio communication.

After setting of the image capturing conditions is completed, the radiologic technician carries out, at the console, an instructing operation that instructs the start of image capturing. Due thereto, radiation of a radiation amount that corresponds to the image capturing conditions or the like that were provided in advance, is emitted from the radiation generating device80. Due to the radiation X emitted from the radiation generating device80passing through the region B that is the object of image capturing, the radiation X carries image information, and thereafter, is irradiated onto the electronic cassette10.

The radiation X that is irradiated from the radiation generating device80passes through the region B that is the object of image capturing, and thereafter, reaches the electronic cassette10. Due thereto, charges, that correspond to the radiation amount of the irradiated radiation X, are collected and accumulated in the respective charge collecting electrodes34of the radiation detector20that is incorporated within the electronic cassette10.

The cassette controller58controls the gate line driver52such that ON signals are outputted from the gate line driver52to the respective gate lines40in order and line-by-line, and the respective switch elements24that are connected to the respective gate lines40are turned on in order and line-by-line. Due thereto, the charges that are accumulated in the respective charge collecting electrodes34flow-out in order and line-by-line to the respective data lines42as electric signals. The electric signals, that have flowed-out to the respective data lines42, are inputted to the signal processing section54, are converted into digital image information, and are stored in the image memory56.

In the case of the still image capturing mode, after reading-out of the image information of one frame (one shot) is finished, the cassette controller58ends the reading-out of the image information, and transmits the image information that is stored in the image memory56to the console. In the case of the video image capturing mode, the cassette controller58transmits, to the console and at any time, the image information that is stored in the image memory56while repeatedly carrying out reading-out of the image information.

In this way, at the electronic cassette10, at the time of carrying out video image capturing in which the amount of generated heat is large, by setting the electronic cassette10in the unfolded state and carrying out video image capturing, transmission of the heat, that is generated at the controller50within the control unit14, to the radiation detector20within the image capturing unit12can be suppressed. Therefore, changes in the characteristics of the radiation detector20are suppressed, the image quality of the radiographic image that is captured is stable, and the durability of the radiation detector20improves. Further, the image capturing unit12contacts the patient at the time of capturing a radiographic image. Therefore, by suppressing the transmission of heat that is generated at the controller50to the image capturing unit12, it is possible to prevent the surface temperature of the image capturing unit12from becoming too high and the patient from feeling uncomfortable. Moreover, because the radiation detector20is a layered structure and the coefficients of thermal expansion of the members structuring the respective layers are different, the occurrence of deformation or breakage due to heat, and the adhesive deteriorating and peeling due to temperature cycles, can be suppressed.

Further, by setting the electronic cassette10in the unfolded state, the surface area increases, and therefore, the heat dissipating effect improves. In a case of capturing video images in particular, the amount of heat that is generated is large, and therefore, making the surface area larger is preferable from the standpoint of heat dissipation. The heat dissipating effect may be further improved by forming the surface of the control unit14to have convex and concave shapes so as to increase the surface area. The convex and concave shapes may be any of wave shapes, semispherical shapes, or the like.

By carrying out still image capturing with the electronic cassette10in the housed state, radiation is irradiated onto the radiation detector20from the irradiated surface18A that is the reverse side, and therefore, a radiographic image having high resolution can be obtained. Further, by carrying out video image capturing with the electronic cassette10in the unfolded state, radiation is irradiated onto the radiation detector20from the irradiated surface18B that is the obverse side, and the sensitivity of the radiation detector20to radiation is high. Therefore, the amount of radiation that is irradiated at the time of video image capturing can be kept small, and the amount of exposure of the region that is the object of image capturing can be kept low.

When the electronic cassette10is in the unfolded state, the radio communication section60is provided within the control unit14that is apart from the patient. In the case of radio communication, the antenna is apart from the patient, and therefore, it is difficult for radio interference to occur.

Note that the above exemplary embodiment describes a case in which the image capturing unit12and the control unit14are formed to be the same height in order to eliminate a step between the image capturing unit12and the control unit14in the unfolded state (FIG. 2). However, the exemplary embodiment is not limited to the same. For example, in the same way as a liquid crystal display, the radiation detector20can be formed at a glass substrate and can be made to be relatively thin. At the controller50, the circuits such as the inductors and the coils and the like are relatively thick, and, further, the battery and the like as well are relatively thick. Thus, as shown inFIG. 12andFIG. 13, at the electronic cassette10, the image capturing unit12may be formed to be thin, and the control unit14may be structured such that an overlapped portion14A, on which the image capturing unit12is folded-up and superposed in the housed state, is formed to be thin and the same thickness as the image capturing unit12, and a non-overlapped portion14B, on which the image capturing unit12is not superposed, is formed to be thick, and circuits such as the inductors and coils and the like, as well as the battery, are disposed within the non-overlapped portion14B. The display section19A and the operation panel19B may be provided at the overlapped portion14A or may be provided at the non-overlapped portion14B.

Although the above exemplary embodiment describes a case in which radio communication with an external device such as the console or the like is carried out, the exemplary embodiment is not limited to the same. For example, wired communication may be carried out. In this case as well, by providing a connector, to which is connected a cable for carrying out the wired communication, at the control unit14, the connector and the cable do not bother the patient. Further, when placing the cassette under the subject, no frictional resistance or excessive load is applied, and it is therefore difficult for troubles with poor contact such as looseness or disconnection or the like to arise.

Further, although the present exemplary embodiment describes a case in which the image capturing mode is made to be the video image capturing mode when the electronic cassette10is set in the unfolded state, the exemplary embodiment is not limited to the same. For example, the electronic cassette10may be structured so as to accept an image capturing instruction for still image capturing from the operation panel19B also when the electronic cassette10is in an unfolded state, and, in a case in which an image capturing instruction for still image capturing is accepted at the operation panel19B, the cassette controller58may operate in the still image capturing mode also in the unfolded state.

Although the above exemplary embodiment describes a case in which information relating to the patient is displayed on the display section19A, the exemplary embodiment is not limited to the same. For example, the captured radiographic image or the image capturing conditions may be displayed. Further, if the same region that is the object of image capturing of the patient is captured periodically and changes over time are observed, radiographic images that have been captured in the past at that region that is the object of image capturing of the patient may be received from the console and displayed. Moreover, a sample image or image capturing guidance may be displayed in accordance with the region that is the object of image capturing.

The exemplary embodiment describes a case in which the gate line driver52and the signal processing section54are provided within the control unit14, but the exemplary embodiment is not limited to the same. For example, the gate line driver52and/or the signal processing section54may be structured by an integrated circuit55such as an Application Specific Integrated Circuit (ASIC) or the like, and may be disposed within the hinge16as shown inFIG. 14. Due thereto, the effect of cooling the integrated circuit55can be improved. Note that the integrated circuit55does not necessarily have to be provided within the hinge16, and may be provided in a vicinity of the hinge16as shown inFIG. 15.

Due to the electronic cassette10being opened and closed, the device state of the electronic cassette10may transition, such as the power source may be turned on and off, or the mode may shift from an inactive mode to an image capturing mode, or the like.

Further, the above respective exemplary embodiments describe cases in which the present invention is applied to the indirect-conversion-type radiation detector20that once converts radiation into light at the scintillator layer28, and converts the converted light into charges at the photoconductive layers30and accumulates the charges. However, the exemplary embodiments are not limited to the same. For example, the present invention may be applied to a direct-conversion-type radiation detector that directly converts radiation into charges at sensor portions using amorphous selenium or the like, and accumulates the charges.

In a direct-conversion-type radiation detector, as shown inFIG. 15, a photoconductive layer48that converts incident radiation into charges is formed, as an example of a radiation conversion layer that converts incident radiation, on the TFT substrate26.

A bias electrode49, that is formed on the obverse side of the photoconductive layer48and is for applying bias voltage to the photoconductive layer48, is formed on the photoconductive layer48.

In the direct-conversion-type radiation detection device, in the same way as in the indirect-conversion-type radiation detection device, the charge collecting electrodes34, that collect the charges generated at the photoconductive layer48, are formed at the TFT substrate26.

Further, the TFT substrate26in the direct-conversion-type radiation detection device has charge storage capacitors35that store the charges collected at the respective charge collecting electrodes34. The charges stored in the respective charge storage capacitors35are read-out by the switch elements24.

Moreover, the structures of the electronic cassette10and the radiation detector20that were described in the above exemplary embodiments are examples, and appropriate changes may, of course, be made within a range that does not deviate from the gist of the present invention.