JP2012024231A - Radiation image capturing device, radiation image capturing system, and radiation image capturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation image capturing device, radiation image capturing system, and radiation image capturing method at low cost for efficiently reducing noise of radiation image without requiring synchronism of image timing.SOLUTION: In the radiation image capturing device, positioning of a subject 14 to a radiation detector 66 is detected, and read mode for reading an electric signal accumulated in a pixel 102 is started. When a value of the read electric signal is larger than the threshold which arbitrarily enables to set, reading the electric signal is completed to shift the radiation detector 66 to an exposure state.

Description

  The present invention relates to a radiation imaging apparatus, a radiation imaging system, and a radiation imaging method for imaging radiation transmitted through a human body.

  In the medical field, a portable radiation imaging apparatus such as an FPD (Flat Panel Detector) that performs imaging inside a human body by detecting the intensity of radiation transmitted through the human body is used. This FPD (hereinafter referred to as an electronic cassette) can take an image while the patient is placed on a bed or the like, and the imaging location can be adjusted by changing the position of the electronic cassette. It can be handled flexibly.

  By the way, even if the electronic cassette is not irradiated with radiation, electric charge is generated by dark current and the electric charge is accumulated in each pixel. Since this dark current appears as noise in the radiation image, the electronic cassette generally performs an operation of removing charges accumulated in each pixel of the electronic cassette immediately before performing radiation imaging. When the radiography is performed, the control apparatus instructs the radiography apparatus that irradiates the electronic cassette and the radiation with an imaging request. When there is an imaging request, the radiation apparatus starts irradiation of radiation, and the electronic cassette starts exposure. When the radiation irradiation is completed, the electronic cassette reads out the electric charge accumulated by the radiation irradiation. At this time, the irradiation timing of the radiation by the radiation apparatus and the exposure timing of the electronic cassette are synchronized. That is, the shooting timing is synchronized.

  In Patent Document 1 shown below, a console (control device) is provided with a first measuring means for measuring time, and an electronic cassette is provided with second measuring means for measuring time synchronized with the first measuring means, When the exposure start time determined in advance at the console is reached, radiation is emitted from the radiation device for a predetermined period, and after the predetermined period has elapsed from the exposure start time with the electronic cassette, the charge generated in the radiation detector is Reading is described.

JP 2010-081960 A

  In order to synchronize the imaging timing, it is necessary to electrically connect the control device and the radiation device. In order to electrically connect the control device and the radiation device, it is necessary for the manufacturer's service person to perform connection work at the time of installation of the system, which is costly and requires maintenance costs. In addition, when the manufacturer of the control device is different from the manufacturer of the radiation device, there are many cases where electrical connection cannot be performed from the viewpoint of safety. Conversely, when the control device and the radiation device are not electrically connected, the imaging timing cannot be synchronized. In this case, the electronic cassette exposes all the irradiated radiation by allowing the electronic cassette to perform exposure for a longer time than the irradiation time of the radiation and irradiating the radiation while the electronic cassette is performing the exposure. Radiation images can be taken.

  Thus, when the control device and the radiation device are not electrically connected, the imaging timing cannot be synchronized. Then, there is a case where an operation for removing unnecessary charges accumulated in each pixel of the electronic cassette cannot be performed at an appropriate timing such as immediately before photographing. At this time, a noisy radiation image due to dark current is obtained.

  Therefore, in order to eliminate the inconvenience due to the noise, the operation of removing the accumulated unnecessary charges may be repeatedly performed regardless of the photographing timing. However, even in the case of an electronic cassette that is not scheduled to be photographed soon (so-called standby state), it is necessary to continue the operation. In particular, in a portable electronic cassette with a limited battery capacity, power is wasted by frequently performing the above operation, and the number of radiographic images that can be acquired is reduced. For this reason, the convenience that the convenience of an electronic cassette falls arises.

  Therefore, the present invention has been made in view of such a conventional problem, and does not require synchronization of imaging timing, and the radiation imaging apparatus, the radiation imaging system, and the like, which reduce noise of a radiation image efficiently at low cost. It is another object of the present invention to provide a radiation imaging method.

  The radiation imaging apparatus according to the present invention includes an imaging panel having a plurality of pixels arranged in a matrix for converting and storing radiation from a radiation source that has passed through the subject into an electrical signal, and positioning the subject with respect to the imaging panel And a reading mode for reading out the electric signal accumulated in the pixel in accordance with the positioning detected by the positioning detection unit, and the electric signal read out in the reading mode. And a readout control unit that causes the imaging panel to shift to an exposure state by terminating the readout of the electrical signal when the value of is greater than a threshold that can be arbitrarily set.

  Further, the apparatus further includes a use state identifying unit that identifies a use state of the imaging panel based on the positioning detected by the positioning detection unit, and the reading control unit is configured to use the use state identified by the use state identifying unit. The reading mode is preferably started in response to the above.

  Further, the positioning detection unit includes a pressure sensor that detects a pressure change through the subject that occurs during the positioning, and the use state identification unit detects the pressure change detected by the pressure sensor. Accordingly, it is preferable to identify the usage state of the imaging panel.

  Further, the positioning detection unit includes a temperature sensor that detects a temperature change through the subject that occurs during the positioning, and the use state identification unit detects the temperature change detected by the temperature sensor. Accordingly, it is preferable to identify the usage state of the imaging panel.

  Further, the positioning detection unit is configured by a human body / object detection sensor, and the use state identification unit is configured to use the imaging panel depending on whether the subject is detected by the human body / object detection sensor. Preferably, the state is identified.

  Furthermore, the positioning detection unit is configured by an optical sensor, and the usage state identification unit is configured to use the imaging panel according to whether the optical sensor detects lighting of an irradiation field lamp. Is preferably identified.

  Furthermore, the reading control unit ends the reading mode when the positioning detecting unit continuously detects that the subject is not present for a predetermined time.

  Furthermore, it is preferable to further include a start / end notification unit for notifying that the reading mode has started and / or ended.

  Furthermore, in the readout mode, it is preferable that the electrical signals accumulated in the plurality of pixels are simultaneously read out in units of a plurality of rows.

  Furthermore, in the readout mode, it is preferable to read out electric charges accumulated in the pixels in a predetermined row.

  A radiation imaging system according to the present invention includes any one of the radiation imaging apparatuses described above and a radiation source that emits radiation.

  A radiation imaging method according to the present invention is a method for imaging a radiation image using an imaging panel having a plurality of pixels arranged in a matrix for converting and storing radiation from a radiation source that has passed through a subject into an electrical signal. A step of detecting the positioning of the subject with respect to the imaging panel, a step of starting a reading mode for reading out the electrical signal accumulated in the pixel in accordance with the detected positioning, and in the reading mode A step of shifting the imaging panel to an exposure state by ending the reading of the electric signal when the value of the read electric signal is larger than an arbitrarily set threshold value. Features.

  According to the present invention, the start of radiation irradiation is determined based on the electrical signal read from the pixel by the execution of the readout mode, and when it is determined that the radiation irradiation has started, the readout of the charge is terminated and the accumulation state is established. Since the shift is made, it is not necessary to synchronize the photographing timing, and the cost is low. In addition, since the readout mode is executed until the start of radiation irradiation is determined, unnecessary charges accumulated in the pixels can be removed, and noise in the radiation image can be reduced. Further, since the positioning of the subject with respect to the imaging panel is detected, it is possible to predict whether or not the current shooting possibility is possible according to the positioning. That is, the power consumption can be further reduced by starting the reading mode at an appropriate timing such as immediately before shooting.

It is a block diagram of the radiation imaging system of this Embodiment. It is a perspective view of the electronic cassette shown in FIG. It is III-III sectional drawing of the electronic cassette shown in FIG. It is a figure which shows schematically the structure for 3 pixels of the radiation detector shown in FIG. FIG. 5 is a schematic configuration diagram of a TFT and a charge storage unit shown in FIG. 4. It is an electrical schematic block diagram of the electronic cassette shown in FIG. FIG. 7 is a detailed view of a radiation conversion panel, a gate driving unit, a charge amplifier, and a multiplexer unit illustrated in FIG. 6. 5 is a time chart of an input signal input from the cassette control unit to the gate drive unit and an output signal output from the gate drive unit to the cassette control unit in the sequential read mode. 4 is a time chart of an input signal input from the cassette control unit to the gate drive unit and an output signal output from the gate drive unit to the cassette control unit in the scan mode. It is an electrical schematic block diagram of a system controller and a console. It is a figure which shows an example of the table shown in FIG. It is a flowchart which shows operation | movement of the system controller and console of a radiation imaging system. It is a flowchart which shows operation | movement of a cassette control part. It is a time chart which shows operation | movement of an electronic cassette. It is a time chart which shows operation | movement of an electronic cassette when the number of imaging | photography is set with 2 sheets. The state of the charge accumulated in the pixels in each row when the radiation is detected when the charges accumulated in the pixels in the 0th row are read out and the state shifts to the accumulation state after the end of one cycle of the scan mode. FIG. The state of the charge accumulated in the pixels in each row when the radiation is detected when the charge accumulated in the pixels in the 238th row is read out and the state shifts to the accumulation state after the end of one cycle of the scan mode. FIG. It is a figure which shows the mode of the electric charge accumulate | stored in the pixel of each line in the case of immediately complete | finishing reading of the electric charge accumulate | stored in the pixel by a scan mode when a radiation is detected, and shifting to an accumulation state. 10 is a time chart showing the operation of the electronic cassette in Modification 3. It is a partial detail drawing of the radiation conversion panel of this modification 4. It is a partial detail drawing of the radiation conversion panel of this modification 5. It is a perspective view of the electronic cassette of this modification 7. It is an electrical schematic block diagram of the electronic cassette of FIG. It is a flowchart which shows operation | movement of the electronic cassette of FIG. It is a schematic explanatory drawing which shows the time series of operation | movement of the electronic cassette of FIG. It is a schematic explanatory drawing which shows the time series of operation | movement of the electronic cassette of FIG. It is another perspective view of the electronic cassette of this modification 7.

  A radiation imaging apparatus according to the present invention and a radiation imaging system including the radiation imaging apparatus will be described in detail below with reference to the accompanying drawings and preferred embodiments.

  FIG. 1 is a configuration diagram of a radiation imaging system 10 according to the present embodiment. The radiation imaging system 10 detects a radiation device 18 that irradiates radiation 16 and a radiation 16 transmitted through the subject 14 to a patient who is a subject 14 lying on an imaging table 12 such as a bed, and converts the radiation 16 into a radiation image. An electronic cassette (radiation imaging apparatus) 20, a system controller 24 that controls the entire radiation imaging system 10, a console 26 that accepts an input operation by a doctor or an engineer (hereinafter referred to as a user), a captured radiographic image, and the like are displayed. And a display device 28.

  Between the system controller 24, the electronic cassette 20, and the display device 28, for example, UWB (Ultra Wide Band), IEEE 802.11. Signals are transmitted and received by wireless LAN such as a / b / g / n or wireless communication using millimeter waves or the like. Note that signals may be transmitted and received by wired communication using a cable.

  The system controller 24 is connected to a radiology information system (RIS) 30 for comprehensively managing radiographic images and other information handled in the radiology department in the hospital, and the RIS 30 is used to supervise medical information in the hospital. A medical information system (HIS) 32 to be managed is connected.

  The radiation device 18 includes a radiation source 34 that irradiates the radiation 16, a radiation control device 36 that controls the radiation source 34, and a radiation switch 38. The radiation source 34 irradiates the electronic cassette 20 with the radiation 16. The radiation 16 irradiated by the radiation source 34 may be X-rays, α-rays, β-rays, γ-rays, electron beams, or the like. The radiation switch 38 is configured to have a two-stage stroke, and the radiation control device 36 prepares to irradiate the radiation 16 when the radiation switch 38 is half-pressed by the user, and from the radiation source 34 when the radiation switch 38 is fully pressed. Is irradiated. The radiation control device 36 has an input device (not shown), and the user can set values such as the irradiation time of the radiation 16, the tube voltage, and the tube current by operating the input device. The radiation control device 36 irradiates the radiation 16 from the radiation source 34 based on the set irradiation time or the like.

  2 is a perspective view of the electronic cassette 20 shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III of the electronic cassette 20 shown in FIG. The electronic cassette 20 includes a panel unit 52 and a control unit 54 disposed on the panel unit 52. The thickness of the panel unit 52 is set to be thinner than the thickness of the control unit 54.

  The panel unit 52 includes a substantially rectangular casing 56 made of a material that is transmissive to the radiation 16, and the imaging surface 42 of the panel unit 52 is irradiated with the radiation 16. A guide line 58 indicating an imaging region and an imaging position of the subject 14 is formed at a substantially central portion of the imaging surface 42. The outer frame of the guide line 58 becomes an imageable region 60 indicating the irradiation field of the radiation 16. The center position of the guide line 58 (intersection where the guide line 58 intersects in a cross shape) is the center position of the imageable area 60.

  The panel unit 52 includes a radiation detector (imaging panel) 66 having a scintillator 62 and a radiation conversion panel 64, and a drive circuit unit 106 (see FIG. 6) to be described later for driving the radiation conversion panel 64. The scintillator 62 converts the radiation 16 that has passed through the subject 14 into fluorescence that is included in the visible light region. The radiation conversion panel 64 is an indirect conversion radiation conversion panel that converts the fluorescence converted by the scintillator 62 into an electrical signal. A scintillator 62 and a radiation conversion panel 64 are arranged inside the housing 56 in order from the imaging surface 42 irradiated with the radiation 16. When the radiation conversion panel 64 is a direct radiation conversion panel that directly converts radiation into an electrical signal, the radiation conversion panel 64 serves as the radiation detector 66. This is because the scintillator 62 is unnecessary in this case.

  The control unit 54 has a substantially rectangular casing 68 made of a material that is impermeable to the radiation 16. The housing 68 extends along one end of the imaging surface 42, and the control unit 54 is disposed outside the imageable region 60 on the imaging surface 42. In this case, the housing 68 includes a cassette control unit 122 that controls a panel unit 52 described later, a memory 124 as a buffer memory that stores image data of a captured radiographic image, and the system controller 24. A communication unit 126 capable of wireless signal transmission and reception and a power supply unit 128 such as a battery are arranged (see FIG. 6). The power supply unit 128 supplies power to the cassette control unit 122 and the communication unit 126.

  FIG. 4 is a diagram schematically illustrating the configuration of the radiation detector 66 for three pixels. In the radiation detector 66, a TFT (Thin Film Transistor) 72, which is a field effect thin film transistor, a charge storage unit 74, a sensor unit 76, and a scintillator 62 are sequentially stacked on a substrate 70. The sensor unit 76 constitutes a pixel. The pixels are arranged in a matrix on the substrate 70, and each TFT (switching element) 72 outputs the charge of the charge storage portion 74 of the pixel connected to itself. The scintillator 62 is formed on the sensor unit 76 via a transparent insulating film 78, and a phosphor is formed by converting the radiation 16 incident from above (on the side opposite to the substrate 70) into light and emitting light. Is.

  The wavelength range of light emitted by the scintillator 62 is preferably in the visible light range (wavelength 360 nm to 830 nm). In order to enable monochrome imaging by the radiation detector 66, the wavelength range of green is included. It is more preferable. As a phosphor used for the scintillator 62, when X-rays are used for imaging as the radiation 16, those containing gadolinium oxide sulfa (GOS) or cesium iodide (CsI) are preferable, and an emission spectrum at the time of X-ray irradiation is 420 nm to It is particularly preferable to use CsI (Ti) (cesium iodide added with titanium) at 600 nm. Note that the emission peak wavelength of CsI (Ti) in the visible light region is 565 nm.

  The sensor unit 76 includes an upper electrode 80, a lower electrode 82, and a photoelectric conversion film 84 disposed between the upper and lower electrodes 80 and 82. Since the upper electrode 80 needs to cause the light generated by the scintillator 62 to enter the photoelectric conversion film 84, it is preferable that the upper electrode 80 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 62.

  The photoelectric conversion film 84 includes an organic photoconductor (OPC), absorbs light emitted from the scintillator 62, and generates electric charges according to the absorbed light. The photoelectric conversion film 84 including an organic photoconductor has a sharp absorption spectrum in the visible light region, and electromagnetic waves other than light emitted by the scintillator 62 are hardly absorbed by the photoelectric conversion film 84, and the radiation 16 is photoelectric. Noise generated by being absorbed by the conversion film 84 can be effectively suppressed.

  The organic photoconductor constituting the photoelectric conversion film 84 preferably has a peak wavelength closer to the emission peak wavelength of the scintillator 62 in order to absorb light emitted by the scintillator 62 most efficiently. Ideally, the absorption peak wavelength of the organic photoconductor coincides with the emission peak wavelength of the scintillator 62. However, if the difference between the two is small, the light emitted from the scintillator 62 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoconductor and the emission peak wavelength of the scintillator 62 with respect to the radiation 16 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of organic photoconductors that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds. For example, since the absorption peak wavelength of quinacridone in the visible light region is 560 nm, if quinacridone is used as the organic photoconductor and CsI (Ti) is used as the material of the scintillator 62, the difference between the peak wavelengths should be within 5 nm. The amount of charge generated in the photoelectric conversion film 84 can be substantially maximized.

  An electromagnetic wave absorption / photoelectric conversion site can be constituted by an organic layer including the pair of electrodes 80 and 82 and the photoelectric conversion film 84 sandwiched between the electrodes 80 and 82. This organic layer is composed of stacked or mixed parts that absorb electromagnetic waves, photoelectric conversion parts, electron transport parts, hole transport parts, electron blocking parts, hole blocking parts, crystallization preventing parts, electrodes, and interlayer contact improvement parts. Can be formed. The organic layer preferably contains an organic p-type compound or an organic n-type compound.

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

  An organic n-type compound (semiconductor) is an acceptor organic compound (semiconductor) mainly represented by an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound. Since the materials applicable as the organic p-type compound and the organic n-type compound and the configuration of the photoelectric conversion film 84 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The lower electrode 82 is a thin film divided for each pixel portion. The lower electrode 82 can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be suitably used. In the sensor unit 76, by applying a predetermined bias voltage between the upper electrode 80 and the lower electrode 82, one of charges (holes, electrons) generated in the photoelectric conversion film 84 is moved to the upper electrode 80. The other can be moved to the lower electrode 82. In the radiation detector 66 of the present embodiment, a wiring is connected to the upper electrode 80, and a bias voltage is applied to the upper electrode 80 via this wiring. In addition, the polarity of the bias voltage is determined so that electrons generated in the photoelectric conversion film 84 move to the upper electrode 80 and holes move to the lower electrode 82, but this polarity is reversed. May be.

  The sensor unit 76 constituting each pixel only needs to include at least the lower electrode 82, the photoelectric conversion film 84, and the upper electrode 80. In order to suppress an increase in dark current, the electron blocking film 86 and the hole blocking film are used. It is preferable to provide at least one of 88, and it is more preferable to provide both.

  The electron blocking film 86 can be provided between the lower electrode 82 and the photoelectric conversion film 84, and when a bias voltage is applied between the lower electrode 82 and the upper electrode 80, the photoelectric conversion film 84 is formed from the lower electrode 82. It is possible to prevent the dark current from being increased due to the injection of electrons. An electron donating organic material can be used for the electron blocking film 86. The material actually used for the electron blocking film 86 may be selected according to the material of the adjacent lower electrode 82 and the material of the adjacent photoelectric conversion film 84, and the work function (Wf) of the material of the adjacent lower electrode 82. It is preferable that the electron affinity (Ea) is 1.3 eV or more and has an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 84. Since the material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The thickness of the electron blocking film 86 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 the photoelectric conversion rate of the sensor unit 76. It is 50 nm or more and 100 nm or less.

  The hole blocking film 88 can be provided between the photoelectric conversion film 84 and the upper electrode 80, and when a bias voltage is applied between the lower electrode 82 and the upper electrode 80, the photoelectric conversion film is formed from the upper electrode 80. It can be suppressed that holes are injected into 84 and the dark current increases.

  An electron-accepting organic material can be used for the hole blocking film 88. The thickness of the hole blocking film 88 is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, in order to reliably exhibit the dark current suppressing effect and prevent a decrease in the photoelectric conversion rate of the sensor unit 76. Preferably they are 50 nm or more and 100 nm or less.

  The material actually used for the hole blocking film 88 may be selected according to the material of the adjacent upper electrode 80 and the material of the adjacent photoelectric conversion film 84, and the work function (Wf) of the material of the adjacent upper electrode 80. It is preferable that the ionization potential (Ip) is 1.3 eV or more higher and the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 84 is equal to or larger than Ea. 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.

  FIG. 5 is a schematic configuration diagram of the TFT 72 and the charge storage unit 74. A charge accumulating portion 74 that accumulates the charges transferred to the lower electrode 82 and a TFT 72 that converts the charges accumulated in the charge accumulating portion 74 into an electric signal and outputs them are formed. The region where the charge storage portion 74 and the TFT 72 are formed has a portion that overlaps the lower electrode 82 in plan view. With such a configuration, the TFT 72 and the sensor portion 76 in each pixel have a thickness. There will be overlap in the direction. In order to minimize the plane area of the radiation detector 66, it is preferable that the region where the charge storage portion 74 and the TFT 72 are formed is completely covered by the lower electrode 82.

  The charge storage unit 74 is electrically connected to the corresponding lower electrode 82 through a wiring made of a conductive material that penetrates the insulating film 90 provided between the substrate 70 and the lower electrode 82. . As a result, the charges collected by the lower electrode 82 can be moved to the charge storage portion 74.

In the TFT 72, a gate electrode 92, a gate insulating film 94, and an active layer (channel layer) 96 are stacked, and a source electrode 98 and a drain electrode 100 are formed on the active layer 96 with a predetermined interval. The active layer 96 is formed of an amorphous oxide. The amorphous oxide constituting the active layer 96 is preferably an oxide containing at least one of In, Ga, and Zn (for example, In—O-based), and at least two of In, Ga, and Zn. Oxides (for example, In—Zn—O, In—Ga, and Ga—Zn—O) are more preferable, and oxides including all of In, Ga, and Zn are particularly preferable. As the In—Ga—Zn—O-based amorphous oxide, an amorphous oxide whose composition in a crystalline state is represented by InGaO ₃ (ZnO) _m (m is a natural number less than 6) is preferable, and InGaZnO is particularly preferable. ₄ is more preferable.

  If the active layer 96 of the TFT 72 is formed of an amorphous oxide, the radiation 72 such as X-rays is not absorbed, or even if it is absorbed, the amount is very small. Can be suppressed. Here, both of the amorphous oxide constituting the active layer 96 of the TFT 72 and the organic photoconductor constituting the photoelectric conversion film 84 can be formed at a low temperature. Therefore, the substrate 70 is not limited to a substrate having high heat resistance such as a semiconductor substrate, a quartz substrate, and a glass substrate, and a flexible substrate such as plastic, aramid, or bio-nanofiber can be used. Specifically, flexibility such as polyester such as polyethylene terephthalate, polyethylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), etc. A substrate can also be used. If such a flexible substrate made of plastic is used, the weight can be reduced, and it is advantageous for carrying around, for example.

  Since aramid can be applied at a high temperature process of 200 ° C. or more, the transparent electrode material can be cured at a high temperature to reduce the resistance, and can be used for automatic mounting of a driver IC including a solder reflow process. Moreover, since aramid has a thermal expansion coefficient close to that of ITO (Indium Tin Oxide) and a glass substrate, warping after production is small and hardly cracked. Further, aramid can form the substrate 70 thinner than a glass substrate or the like. Note that the substrate 70 may be formed by laminating an ultrathin glass substrate and aramid.

  Bionanofiber is a composite of a cellulose microfibril bundle (bacterial cellulose) produced by bacteria (Acetobacter Xylinun) and a transparent resin. The cellulose microfibril bundle has a width of 50 nm and a size of 1/10 of the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. Bacterial cellulose is impregnated with a transparent resin such as an acrylic resin or an epoxy resin and cured to obtain a bio-nanofiber having a light transmittance of about 90% at a wavelength of 500 nm while containing 60-70% of the fiber. Bionanofiber has a low coefficient of thermal expansion (3-7 ppm) comparable to silicon crystals, is as strong as steel (460 MPa), highly elastic (30 GPa), and flexible, so it is thinner than glass substrates. The substrate 70 can be formed.

  In the present embodiment, a TFT 72, a charge storage unit 74, a sensor unit 76, and a transparent insulating film 78 are sequentially formed on the substrate 70, and an adhesive resin having a low light absorption property is used on the substrate 70. A radiation detector 66 is formed by attaching the scintillator 62. The layer formed up to the transparent insulating film 78 is called a radiation conversion panel 64.

  In the radiation detector 66, the photoelectric conversion film 84 is made of an organic photoconductor, and the radiation 16 is hardly absorbed by the photoelectric conversion film 84. For this reason, the radiation detector 66 according to the present embodiment can reduce the amount of absorption of the radiation 16 by the photoelectric conversion film 84 even when the radiation 16 passes through the radiation conversion panel 64 by backside illumination. A decrease in sensitivity can be suppressed. In backside illumination, the radiation 16 passes through the radiation conversion panel 64 and reaches the scintillator 62. However, when the photoelectric conversion film 84 of the radiation conversion panel 64 is formed of an organic photoconductor, the radiation 16 in the photoelectric conversion film 84 Since there is almost no absorption and attenuation of the radiation 16 can be suppressed, it is also suitable for backside illumination.

  FIG. 6 is a schematic electrical configuration diagram of the electronic cassette 20 shown in FIG. The electronic cassette 20 has a structure in which the pixels 102 are arranged on the matrix TFTs 72. The pixels 102 are arranged in a matrix and have photoelectric conversion elements (not shown). In each pixel 102 to which a bias voltage is supplied from a bias power source 108 that constitutes the drive circuit unit 106, charges generated by photoelectric conversion of visible light are accumulated, and the TFTs 72 are sequentially turned on for each column. A charge signal (electric signal) can be read out as a pixel value of an analog signal via the signal line 112. In FIG. 6, for the sake of convenience, the pixels 102 and the TFTs 72 are arranged in an array of 4 × 4 in the vertical direction. However, in actuality, the array is 2880 × 2304 in the vertical direction.

  The TFT 72 connected to each pixel 102 is connected to a gate line 110 extending in the row direction and a signal line 112 extending in the column direction. Each gate line 110 is connected to a gate drive unit 114 constituting the drive circuit unit 106, and each signal line 112 is connected to a multiplexer unit 118 constituting the drive circuit unit 106 via a charge amplifier 116. The multiplexer unit 118 is connected to an AD conversion unit 120 that converts an electrical signal of an analog signal into an electrical signal of a digital signal. The AD conversion unit 120 outputs an electrical signal converted into a digital signal (pixel value of the digital signal, hereinafter also referred to as a digital value) to the cassette control unit 122.

  The cassette control unit 122 controls the entire electronic cassette 20, and also includes a clock circuit (not shown) and functions as a timer. By causing an information processing apparatus such as a computer to read a predetermined program, the computer can function as the cassette control unit 122 of the present embodiment.

  A memory 124 and a communication unit 126 are connected to the cassette control unit 122. The memory 124 stores pixel values of digital signals, and the communication unit 126 transmits and receives signals to and from the system controller 24. The communication unit 126 transmits a single image (one frame image) configured by arranging a plurality of pixel values in a matrix to the system controller 24 in units of one row. The power supply unit 128 supplies power to the cassette control unit 122, the memory 124, and the communication unit 126. The bias power source 108 supplies the power transmitted from the cassette control unit 122 to each pixel 102.

  The cassette control unit 122 includes a first readout control unit 130, an irradiation start determination unit 132, an elapsed time determination unit 134, and a second readout control unit 136. The first readout control unit 130 reads out the charges accumulated in the pixels 102 simultaneously in units of a plurality of lines, thereby reading out the charges accumulated in each pixel 102 (first readout mode, simply readout mode). ). The first reading control unit 130 executes the scan mode by controlling the gate driving unit 114, the charge amplifier 116, the multiplexer unit 118, and the AD conversion unit 120.

  Note that the scan mode as the first readout mode is a high-speed readout mode in which one frame of image data can be read out in a shorter time than a sequential readout mode as the second readout mode described later.

  Hereinafter, the concept of the scan mode will be described. When the scan mode is executed, for example, the gate driver 114 outputs a gate signal to the gate lines 110 of the 0th and 2nd rows to turn on the TFTs 72 of the 0th and 2nd rows ( The charges accumulated in the pixels 102 in the 0th and 2nd rows are simultaneously read out via the signal lines 112. The read charge of each column is output to the charge amplifier 116 of each column as a charge signal (pixel value). Here, since the charges accumulated in the pixels 102 in the 0th and 2nd rows are read out simultaneously, the electric signal input to the charge amplifier 116 is the electric signal accumulated in the pixels 102 in the 0th and 2nd rows. The signal is added. That is, the electrical signals accumulated in the pixels 102 in the 0th and 2nd rows are added for each column, and the added electrical signal is output to the charge amplifier 116 in each column. Thereby, the charges of the pixels 102 in the 0th and 2nd rows can be added and read out.

  The charge amplifier 116 converts the input charge signal into a voltage signal and outputs the voltage signal to the multiplexer unit 118. The multiplexer unit 118 sequentially selects the input voltage signal and outputs it to the AD conversion unit 120. The AD conversion unit 120 converts the input voltage signal into a digital signal and outputs the digital signal. As a result, the electrical signals (pixel values) accumulated in the pixels 102 in the 0th and 2nd rows are added for each column and output from the AD conversion unit 120 as an electrical signal (pixel value) of a digital signal. The electric signal (pixel value) of the digital signal output from the AD conversion unit 120 is sent to the cassette control unit 122, and the cassette control unit 122 stores the sent digital value in the memory 124. That is, the memory 124 stores image data obtained by adding the image data of the 0th row and the 2nd row for each column.

  When the gate driver 114 reads out the charges accumulated in the pixels 102 in the 0th and 2nd rows as described above, this time, by sending a gate signal to the gate lines 110 in the 1st and 3rd rows, The TFTs 72 in the first and third rows are turned on (the first and third rows are activated) and accumulated in the pixels 102 in the first and third rows via the signal lines 112. Read the electric charge (electric signal) at the same time. The read electrical signal is sent to the cassette control unit 122 as a digital signal through the above-described operation, and stored in the memory 124.

  The first readout control unit 130 ends the execution of the scan mode when it is determined by the irradiation start determination unit 132 described later that the irradiation of the radiation 16 has started. At this time, if the reading of the image data for one frame is not completed, the execution of the scan mode is terminated after the reading of the image data for one frame is completed.

  As described above, since the charge accumulated in the pixel 102 is read out in the scan mode, one frame of image data can be read out in a short time, and the noise charge accumulated in the pixel 102 can be removed in a short time. Since the charge accumulated in the pixel 102 is read out in the scan mode, even if it is determined that the irradiation of the radiation 16 has been started, the exposure state can be immediately shifted, and the radiation 16 having the image information is wasted. There is nothing to do. On the other hand, when noise charges accumulated in the pixel 102 are removed in the sequential readout mode described later, it takes time to read out one frame of image data, and the radiation 16 is read during reading of one frame of image data. If it is determined that the irradiation is started, the exposure state cannot be immediately shifted, and the radiation 16 that is image information is wasted.

  The irradiation start determination unit 132 determines whether the digital value read by the first read control unit 130 and stored in the memory 124 is greater than a threshold value. When the digital value is larger than the threshold value, it is determined that the irradiation of the radiation 16 has started. That is, the irradiation start determination unit 132 detects the radiation 16 based on whether or not the obtained digital value is larger than the threshold value. In the state where the radiation 16 is not irradiated, the electric charge accumulated in the pixel 102 is noise and a very small amount. However, when the radiation 16 is irradiated and enters the electronic cassette 20, the charge accumulated in the pixel 102 becomes larger than when the radiation 16 is not irradiated. Therefore, when the electrical signal read in the scan mode and converted into a digital signal is larger than the threshold value, it can be determined that the irradiation of the radiation 16 has started.

  In addition, since the charges accumulated in the pixels 102 are simultaneously read out in units of a plurality of rows in the scan mode, the irradiation start of the radiation 16 can be determined early and accurately. That is, by adding the charges of the pixel 102, when the radiation 16 is irradiated, the electrical signal of the digital signal obtained is greatly increased, so that the irradiation start of the radiation 16 can be determined at an early stage. . Conversely, by lowering the threshold value without adding the charge accumulated in the pixel 102, the irradiation start of the radiation 16 can be detected at an early stage, but the ratio of noise of the electrical signal to the threshold increases. The irradiation start of the radiation 16 cannot be detected accurately. This threshold can be arbitrarily set by the user.

  The elapsed time determination unit 134 determines whether or not a predetermined time has elapsed since the start of irradiation of the radiation 16. This predetermined time may be a time for the radiation source 34 to irradiate the radiation 16, or may be a time for the electronic cassette 20 to expose the radiation 16 in order to capture a radiation image. This predetermined time is stored in the memory 124.

  The second readout control unit 136 executes a sequential readout mode (second readout mode) in which electrical signals accumulated in the pixels 102 are sequentially read out in units of one row. The second reading control unit 136 controls the gate driving unit 114, the charge amplifier 116, the multiplexer unit 118, and the AD conversion unit 120 to sequentially execute the reading mode.

  Hereinafter, the concept of the sequential reading mode will be described. When the sequential read mode is executed, the gate driver 114 outputs a gate signal to the gate line 110 of the 0th row to turn on the TFT 72 of the 0th row (activate the 0th row), The electric charge accumulated in the pixels 102 in the 0th row is read out through each signal line 112. The read charges in each column are output as charge signals (pixel values) to the charge amplifiers 116 in the respective columns and converted into voltage signals. The converted voltage signal is output to the multiplexer unit 118, and the electric signal (pixel value) accumulated in the pixel 102 in the 0th row is sent to the cassette control unit 122 as a digital signal by the AD conversion unit 120, and the memory 124. That is, the image data on the 0th row is stored in the memory 124.

  When the gate driver 114 reads out the electric charge accumulated in the pixels 102 in the 0th row, this time, by sending a gate signal to the gate line 110 in the 1st row, the TFT 72 in the 1st row is turned on (1 The row is activated), and electric charges (electric signals) accumulated in the pixels 102 in the first row are read out through the signal lines 112. The read electrical signal is sent to the cassette control unit 122 as a digital signal through the above-described operation, and stored in the memory 124.

  When the charge accumulated in the pixels 102 in the first row is read, the gate driver 114 reads out the charges accumulated in the pixels 102 in the second row, and then accumulated in the pixels 102 in the third row. The read charge is read.

  The cassette control unit 122 sequentially transmits one line of image data stored in the memory 124 to the system controller 24 via the communication unit 126. That is, the image data for one line is sequentially transmitted in line units. Note that image data for one frame may be transmitted in a batch instead of in units of rows.

  FIG. 7 is a detailed view of the radiation conversion panel 64, the gate driving unit 114, the charge amplifier 116, and the multiplexer unit 118 shown in FIG. The gate driving unit 114 includes twelve gate driving circuits 150 (first to twelfth gate driving circuits 150), and 240 gate lines 110 are connected to each gate driving circuit 150. Each gate driving circuit 150 reads out the electric charge accumulated in the pixel 102 connected to the 240 gate lines 110 connected to the gate driving circuit 150 via the TFT 72. That is, each gate driving circuit 150 reads out the electric charges accumulated in the pixels 102 in the region (0th to 239th rows) in which the gate driving circuit 150 is responsible for reading. The first to twelfth gate drive circuits 150 are collectively referred to as the gate drive circuit 150.

  The multiplexer unit 118 includes nine multiplexers 152 (first to ninth multiplexers 152), and 256 signal lines 112 are connected to each multiplexer 152. Each multiplexer 152 receives a charge signal of the pixel 102 in the region (first column to 255th column) that it is responsible for via the charge amplifier 116. The first to ninth multiplexers 152 are collectively referred to as a multiplexer 152. As described above, the radiation conversion panel 64 includes 2880 (240 × 12) × 2304 (256 × 9) pixels 102 and the TFTs 72.

  The AD conversion unit 120 includes nine A / D converters 154 (first to ninth A / D converters 154), and the voltage signal output from each multiplexer 152 is sent to each A / D converter 154. Is output. Specifically, the voltage signal output from the first multiplexer 152 is output to the first A / D converter 154, and the voltage signal output from the second multiplexer 152 is input to the second A / D converter 154. Is output. As described above, the voltage signal output from each multiplexer 152 is output to the A / D converter 154 corresponding to each multiplexer 152. The A / D converter 154 converts the input voltage signal into a digital voltage signal. The first to ninth A / D converters 154 are collectively referred to as an A / D converter 154.

  Each gate driving circuit 150 sequentially turns on the TFTs 72 in units of rows. As a result, the charges accumulated in the pixels 102 in units of rows are sequentially read and output to the charge amplifier 116 through the signal line 112 as charge signals. Specifically, each gate drive circuit 150 selects the gate line 110 of the 0th row (row to be read first) among the plurality of gate lines 110 connected to the gate drive circuit 150, and the selected gate line 110 is selected. The gate signal is output to turn on the TFT 72 in the 0th row, and the charge accumulated in the pixels 102 in the 0th row is read out. When the charge accumulated in the pixel 102 in the 0th row is read, the gate line 110 in the first row (row to be read second) is selected and a gate signal is output to the selected gate line 110. The TFT 72 in the first row is turned on, and the charge accumulated in the pixels 102 in the first row is read out. The gate lines 110 are sequentially selected up to the 239th line (the last line to be read), such as the second line and the third line, and a gate signal is output to the selected gate line 110, so that the TFT 72 is turned on. The charge stored in the pixels 102 in each row is read by sequentially turning on the unit.

  The read charge of each column is input to the charge amplifier 116 of each column via each signal line 112. Each charge amplifier 116 includes an operational amplifier 156, a capacitor 158, and a switch 160. When the switch 160 is off, the charge amplifier 116 converts the charge signal input to the operational amplifier 156 into a voltage signal and outputs the voltage signal. The charge amplifier 116 amplifies and outputs the electrical signal with the gain set by the cassette control unit 122. When the switch 160 is on, the charge accumulated in the capacitor 158 is discharged by the closed circuit of the capacitor 158 and the switch 160, and the charge accumulated in the pixel 102 is closed by the closed switch 160 and the operational amplifier. 156 is discharged to GND (ground potential). The operation of turning on the switch 160 and releasing the charge accumulated in the pixel 102 to the GND (ground potential) is called a reset operation (empty reading operation). That is, in the case of the reset operation, the voltage signal corresponding to the charge signal accumulated in the pixel 102 is discarded without being output to the multiplexer unit 118 and the AD conversion unit 120. Note that in this embodiment, in the case of “reading the charge accumulated in the pixel 102”, a voltage signal corresponding to the charge accumulated in the pixel 102 is output to the multiplexer unit 118 and the AD conversion unit 120. .

  The voltage signal converted by each charge amplifier 116 is output to each multiplexer 152. The multiplexer 152 sequentially selects and outputs a plurality of input voltage signals in accordance with a control signal from the cassette control unit 122. Each A / D converter 154 converts the voltage signal output from each multiplexer 152 into a digital signal, and outputs the converted digital signal to the cassette control unit 122.

  FIG. 8 is a time chart of an input signal input from the cassette controller 122 to the gate driver 114 and an output signal output from the gate driver 114 to the cassette controller 122 in the sequential read mode. In the normal read mode, the cassette control unit 122 outputs an input signal (drive signal) a1 to the first gate drive circuit 150. When the drive signal a <b> 1 is input, the first gate drive circuit 150 sequentially selects the gate line 110 that it is in charge of from the 0th row and outputs a gate signal to the selected gate line 110. As a result, the TFTs 72 are sequentially turned on in units of rows, and the charges accumulated in the pixels 102 are read out in units of rows. When the first gate drive circuit 150 selects the last row (239th row), the first gate drive circuit 150 outputs an output signal (end signal) b1 to the cassette control unit 122. When the cassette control unit 122 receives the end signal b1, the cassette control unit 122 outputs an input signal (drive signal) a2 to the second gate drive circuit 150.

  When the input signal a <b> 2 is input, the second gate driving circuit 150 sequentially selects the gate line 110 that it is in charge of from the 0th row and outputs a gate signal to the selected gate line 110. As a result, the TFTs 72 are sequentially turned on in units of rows, and the charges accumulated in the pixels 102 are read out in units of rows. When the second gate drive circuit 150 selects the last row (row 239), the second gate drive circuit 150 outputs an output signal (end signal) b2 to the cassette control unit 122. When the cassette controller 122 receives the end signal b <b> 2, the cassette controller 122 inputs an input signal (drive signal) a <b> 3 to the third gate drive circuit 150. Such an operation is performed up to the twelfth gate drive circuit 150.

  In this way, by inputting the driving signals a1 to a12 from the first gate driving circuit 150 to the twelfth gate driving circuit 150, the gate driving circuits 150 are sequentially driven and accumulated in the pixels 102 in units of rows. The read charges are sequentially read out. As a result, the charges accumulated in the pixels 102 from the 0th row to the 2879th row of the radiation conversion panel 64 are sequentially read out in units of rows from the 0th row. In this sequential readout mode, considering the image quality of the radiographic image to be captured, it takes about 173 μsec to read out one row of the charges accumulated in the pixels 102. Therefore, in the sequential reading mode, it takes about 500 msec (173 μsec / 1 × 2880 line) to read all the rows (2880 rows).

  FIG. 9 is a time chart of an input signal input from the cassette controller 122 to the gate driver 114 and an output signal output from the gate driver 114 to the cassette controller 122 in the scan mode. In the scan mode, the cassette control unit 122 outputs the input signals c1 to c12 to the first to twelfth gate drive circuits 150 simultaneously. When the drive signals c1 to c12 are input, the first to twelfth gate drive circuits 150 sequentially select the gate lines 110 that the first to twelfth gate drive circuits 150 are in charge of from the 0th row, and apply gate signals to the selected gate lines 110. Output. As a result, the TFTs 72 in the region in charge of each gate drive circuit 150 are sequentially turned on in units of rows, and the charges accumulated in the pixels 102 in the region in charge of each gate drive circuit 150 are sequentially read out in units of rows.

  Specifically, the charges accumulated in the pixels 102 in the 0th row in the area in charge of each gate driving circuit 150 are simultaneously read out, and then the charges accumulated in the pixels 102 in the first row are simultaneously read out. . In this way, the charges accumulated in the pixels 102 in the area that each gate drive circuit 150 is responsible for are sequentially read out in units of rows. Therefore, the charges of the pixels 102 read out by the gate driving circuits 150 are added for each column. For example, when the gate driving circuits 150 simultaneously read out the charges of the pixels 102 in the 0th row, the read out charges of the pixels 102 in the 0th row are added for each column. The charge added for each column is input to the charge amplifier 116 of each column. Each gate drive circuit 150 outputs each output signal (end signal) d1-d12 to the cassette control part 122, if the last line (239th line) is selected.

  In the scan mode, it is necessary to shorten the time required to read out the charge accumulated in the pixel 102. On the other hand, if the time required for reading out the charge is made too short, the surplus charge accumulated in the pixel 102 cannot be removed, and a radiographic image with good image quality cannot be taken. In order to satisfy these requirements, one row of charges accumulated in the pixel 102 is read out in a time of 21 μsec. Therefore, in the scan mode, it takes about 5 msec (21 μsec × 2880 line × (1/12)) to read all the rows (2880 rows). This is about 1/100 of the time required in the sequential readout mode, and the charges accumulated in all the pixels 102 can be read out. Here, the reason for multiplying 21 μsec × 2880 line by (1/12) is that, in the scan mode, the charges accumulated in the pixels 102 are read simultaneously in units of 12 rows.

  That is, the electronic cassette 20 is connected to a plurality of pixels 102 arranged in a matrix, a plurality of TFTs 72 arranged in a matrix for reading out electric signals accumulated in the plurality of pixels 102, and the TFTs 72 in each row. A plurality of gate lines 110 parallel to the row direction, and a plurality of gate lines 110 connected to each other, and a plurality of gate drive circuits arranged in parallel along the column direction outputting gate signals to the TFTs 72 of each row via the gate lines 110 150 and a plurality of signal lines 112 parallel to the column direction for reading out electrical signals accumulated in the plurality of pixels 102.

  The gate of the TFT 72 is connected to the gate line 110, and the source is connected to the pixel 102. The drain of the TFT 72 is connected to the signal line 112. When the driving signal a or c is input, each gate driving circuit 150 sequentially selects the gate line 110 connected to itself, and outputs a gate signal to the selected gate line 110, thereby turning on the TFT 72. The electric signals accumulated in the pixels 102 connected to the self through the plurality of signal lines 112 are sequentially read out in units of rows.

  The first readout control unit 130 inputs a drive signal c to each gate drive circuit 150 at the same time, thereby executing a scan mode in which electrical signals accumulated in the plurality of pixels 102 are simultaneously read in a plurality of rows.

  The second reading control unit 136 of the cassette control unit 122 sequentially inputs the driving signal a to each gate driving circuit 150 to drive each gate driving circuit 150 in order, so that the electric signals of the plurality of pixels 102 are sent to one row. A sequential read mode is read in which the unit is read sequentially.

  FIG. 10 is a schematic electrical configuration diagram of the system controller 24 and the console 26. The console 26 receives signals between the input unit 200 that accepts user input operations, the control unit 202 that controls the entire console 26, the display unit 204 that displays an image that assists user input operations, and the system controller 24. Interface I / F 206 which performs transmission / reception of.

  The system controller 24 performs wireless communication between the interface I / F 210 that transmits and receives signals to and from the console 26, the control unit 212 that controls the entire radiation imaging system 10, the electronic cassette 20, and the display device 28. A communication unit 214 that transmits / receives data, a recording unit 216 that records image data and programs transmitted from the electronic cassette 20 via the communication unit 214, and an imaging condition including an irradiation time of the radiation 16 and the like. And a database 220 having a table 218 recorded in association with the diagnosis site. The interface I / F 206 and the interface I / F 210 are connected by a cable 230. The input unit 200 includes a mouse and a keyboard (not shown), and the input unit 200 outputs an operation signal input by the user to the control unit 202.

  The control unit 202 causes the display unit 204 to function as a GUI (Graphical User Interface) by displaying a screen for the user to input an imaging region, a diagnostic region, and the number of images to be captured. The doctor operates the input unit 200 while selecting the imaging region, the diagnostic region, and the number of images while viewing the image displayed on the display unit 204 (the screen of the display unit 204). Here, the imaging part is a part of the body of the patient who performs radiography, and includes, for example, the chest, the lower abdomen, and the legs. The diagnostic part refers to a part to be diagnosed using an image obtained by radiography. For example, even if the photographing part is the same chest, the diagnostic part is different such as a circulatory organ, a rib, and a heart.

  The control unit 202 outputs the imaging region, the diagnostic region, and the number of images selected by the user to the control unit 212 of the system controller 24 via the interface I / Fs 206 and 210. The imaging condition setting unit (irradiation time setting unit) 222 of the control unit 212 sets imaging conditions corresponding to the imaging region and the diagnostic region sent from the console 26 (selected by the user). Specifically, the imaging condition setting unit 222 reads out imaging conditions corresponding to the imaging region and the diagnostic region selected by the user from the table 218, and sets the read imaging conditions as imaging conditions for radiation imaging to be performed from now. The imaging condition setting unit 222 transmits at least the irradiation time among the set imaging conditions via the communication unit 214 to the electronic cassette 20. The electronic cassette 20 stores the transmitted irradiation time in the memory 124. The stored irradiation time is the predetermined time described above.

  The number of shots setting unit 224 of the control unit 212 sets the number of shots sent (selected by the user) sent from the console 26. The number of shots setting unit 224 transmits the set number of shots to the electronic cassette 20 via the communication unit 214. The electronic cassette 20 stores the sent number of shots in the memory 124. The image recording control unit 226 of the control unit 212 causes the recording unit 216 to record image data for one frame transmitted from the electronic cassette 20 via the communication unit 214.

  FIG. 11 is a diagram illustrating an example of the table 218. In the table 218, imaging conditions such as irradiation time, tube voltage, and tube current are recorded corresponding to the imaging region and the diagnostic region. In addition, there are a plurality of diagnostic parts in the imaging part, and imaging conditions are recorded according to the diagnostic part. For example, when the imaging site is the chest, a plurality of diagnostic sites such as a circulatory organ, ribs, and heart are provided, and imaging conditions are recorded corresponding to the diagnostic sites. When the imaging site is the chest and the diagnostic site is the circulatory system, the irradiation time is 200 msec, the tube voltage is 100 kV, the tube current is 10 mA, and the like. Information recorded in the table 218 can be arbitrarily changed by the user operating the input unit 200 of the console 26.

  Next, the operation of the radiation imaging system 10 will be described with reference to the flowcharts of FIGS. FIG. 12 is a flowchart showing the operations of the system controller 24 and the console 26 of the radiation imaging system 10, and FIG. 13 is a flowchart showing the operations of the cassette control unit 122. First, operations of the system controller 24 and the console 26 will be described, and then operations of the cassette control unit 122 will be described.

  The control unit 202 of the console 26 determines whether or not an imaging region, a diagnostic region, and the number of imaging images are selected by the user's operation of the input unit 200 (step S1). At this time, the control unit 202 causes the display unit 204 to display an image for the user to select an imaging region, a diagnostic region, and the number of images to be captured. While viewing the displayed image, the user can select an imaging region and a diagnostic region of the patient to be subjected to radiography.

  If it is determined in step S1 that the imaging region, the diagnostic region, and the number of images are not selected, the process stays in step S1 until it is selected.

  On the other hand, if it is determined in step S1 that the imaging region / diagnosis region and the number of images have been selected by the user, the imaging condition setting unit 222 sets the imaging conditions corresponding to the imaging region / diagnosis region selected by the user from the table 218. In addition to setting the read radiographing conditions as radiographing radiographing conditions to be performed, the radiographing number setting unit 224 sets the radiographing number selected by the user (step S2). Specifically, when an imaging region or the like is selected by the user's operation of the input unit 200, the control unit 202 sends the selected imaging region or the like to the control unit 212 of the system controller 24 via the interface I / Fs 206 and 210. Output. The imaging condition setting unit 222 of the control unit 212 sets the imaging conditions corresponding to the imaging region and the diagnostic region transmitted from the console 26 and sets the number of imaging images transmitted from the console 26. The system controller 24 outputs the set shooting conditions to the control unit 202 via the interface I / F 210 and 206, and the control unit 202 displays the set shooting conditions and the number of shots on the display unit 204. You may let them. Thereby, the user can visually recognize the contents of the set shooting conditions.

  The user operates the input device provided in the radiation control device 36 so that the radiation 16 is emitted from the radiation source 34 under the set imaging conditions, thereby setting the imaging conditions set on the system controller 24 side. The radiation control device 36 is also set with the same imaging conditions. For example, the radiation apparatus 18 may have the same table as the table 218, and the user may set the same imaging condition by selecting an imaging region and a diagnosis region. A tube current or the like may be input.

  When the photographing conditions are set, the control unit 212 activates the electronic cassette 20 by transmitting an activation signal to the electronic cassette 20 via the communication unit 214 (step S3). The electronic cassette 20 is in a sleep state until an activation signal is sent. The sleep state refers to a state where power is not supplied to at least the radiation conversion panel 64 and the drive circuit unit 106. The electronic cassette 20 executes a scan mode when activated. The electronic cassette 20 may perform a reset operation after starting and before executing the scan mode.

  Next, the imaging condition setting unit 222 and the imaging number setting unit 224 transmit the set irradiation time and imaging number to the electronic cassette 20 via the communication unit 214 (step S4).

  Next, the control unit 212 determines whether or not a read start signal from the electronic cassette 20 has been received (step S5). The readout start signal is a signal indicating that readout of charges accumulated in the pixel 102 is started in the sequential readout mode.

  If it is determined in step S5 that the read start signal has not been received, the process remains in step S5 until it is received. If it is determined that the read start signal has been received, the image recording control unit 226 has received one line of image data. It is determined whether or not (step S6). Since the electronic cassette 20 sequentially outputs the image data for one line read sequentially in line units to the system controller 24, the image data for one line is sequentially sent to the system controller 24.

  If it is determined in step S6 that one line of image data has been sent, the image recording control unit 226 stores the sent one line of image data in a buffer memory (not shown) of the control unit 212 (step S7). ).

  Next, the image recording control unit 226 determines whether or not reading of image data for one frame has been completed (step S8). The electronic cassette 20 outputs a read end signal to the system controller 24 when reading of image data for one frame is completed, and the image recording control unit 226 receives one frame when receiving the read end signal. It is determined that the reading of the image data for that time has been completed.

  If it is determined in step S8 that reading of image data for one frame has not been completed, the process returns to step S6 and the above-described operation is repeated.

  If it is determined in step S8 that reading of the image data for one frame has been completed, an image file is generated from the image data for one frame stored in the buffer memory and recorded in the recording unit 216 (step S9).

  Next, the image recording control unit 226 determines whether image data for the number of shots set in step S2 has been sent (step S10). If it is determined in step S10 that the set number of image data has not been sent, the process returns to step S6, and if it is determined that the number of image data has been sent, the process ends.

  Next, the operation of the electronic cassette 20 will be described according to the flowchart shown in FIG. 13 and the time chart shown in FIG. When the activation signal is sent from the system controller 24, the electronic cassette 20 is activated, and the cassette control unit 122 stores the irradiation time and the number of shots sent from the system controller 24 in the memory 124 (step S21).

  Next, the first reading control unit 130 of the cassette control unit 122 starts executing the scan mode (step S22). When the execution of the scan mode is started, the first read control unit 130 outputs a drive signal c to each gate drive circuit 150. When each gate drive circuit 150 receives the drive signal c, each gate drive circuit 150 sequentially selects the gate line 110 that it is in charge of from the 0th row, and outputs a gate signal to the selected gate line 110, thereby the area that it is in charge of. The charges accumulated in the pixels 102 are sequentially read from the 0th row in units of rows. As a result, the charges accumulated in the pixels 102 in the region in charge of each gate drive circuit 150 are sequentially read out in units of rows at the same time, and the read out charges are added for each column.

  Specifically, the electric charges accumulated in the pixels 102 in the 0th row in the region in charge of each gate driving circuit 150 are simultaneously read out, added for each column, and output to the charge amplifier 116 in each column. Then, the charges accumulated in the pixels 102 in the first row in the region in charge of each gate driving circuit 150 are simultaneously read out, added for each column, and output to the charge amplifier 116 in each column. Such an operation is performed up to the 239th line.

  The charge for one row that is sequentially read out in units of rows and added for each column is sent to the charge amplifier 116 and stored in the memory 124 as an electric signal of a digital signal via the multiplexer unit 118 and the AD conversion unit 120. To go. Thus, the added image data for one row is sequentially stored in the memory 124. When each gate driving circuit 150 reads out the electric charge accumulated in the pixels 102 in the 239th row, it outputs an end signal d to the cassette control unit 122.

  Note that the first read control unit 130 controls the switches 160 of the charge amplifiers 116 to be in an OFF state while the scan mode is being executed. Thus, each charge amplifier 116 can output the input charge signal as a voltage signal. The cassette control unit 122 may perform a resetting operation after starting and before starting execution of the scan mode. In addition, the first reading control unit 130 may start executing the scan mode after a predetermined time (for example, 10 seconds) has elapsed since the activation.

  Next, the irradiation start determination unit 132 determines whether or not the electrical signal of the digital signal stored in the memory 124 is greater than the threshold value (step S23). When the radiation 16 is irradiated from the radiation source 34 to the electronic cassette 20, the electric signal of the digital signal stored in the memory 124 becomes larger than the threshold value. That is, whether or not the radiation 16 has been irradiated is detected based on whether or not the electrical signal of the digital signal is greater than the threshold value. If it is determined in step S23 that the electrical signal is not greater than the threshold, the process remains in step S23 until it is determined that the electrical signal is greater than the threshold. When the end signals d1 to d12 are sent from the gate drive circuits 150 to the cassette control unit 122 (when the charge for one frame is read), the first read control unit 130 again drives the drive signals c1 to c12. Is output to each gate drive circuit 150. A period from when the drive signals c1 to c12 are input to each gate drive circuit 150 to when the end signals d1 to d12 are output is defined as one cycle of the scan mode. The end signals d1 to d12 are sent from each gate drive circuit 150 at the same timing.

  On the other hand, when it is determined in step S23 that the electrical signal of the digital signal stored in the memory 124 is larger than the threshold value, the irradiation start determination unit 132 determines that the irradiation of the radiation 16 is started by the radiation source 34 ( Step S24).

  In other words, when the user presses the radiation switch 38 halfway during the execution of the scan mode, the radiation control device 36 prepares for irradiation of the radiation 16, and then when the user fully presses the radiation switch 38, the radiation control device 36 Radiation 16 is emitted from the source 34 for a predetermined time. As described above, since the radiation control device 36 irradiates the radiation 16 under the imaging conditions corresponding to the imaging region and the diagnostic region selected by the user, the predetermined time is determined by the imaging region selected by the user. This is the irradiation time according to the diagnosis site. In addition, when performing a plurality of image capturing operations, the user operates the radiation switch 38 at a certain time interval to irradiate the radiation 16 from the radiation source 34.

  If it is determined in step S24 that the irradiation of the radiation 16 has started, the cassette control unit 122 next starts a timer (step S25), and the first readout control unit 130 executes the scan mode on all the pixels 102. It is determined whether or not all accumulated charges have been read (whether the reading of charges for one frame has been completed) (step S26). That is, the first readout control unit 130 determines whether or not one cycle of the scan mode has ended after it is determined that the irradiation of the radiation 16 has started. Specifically, the first readout control unit 130 determines whether or not the end signals d1 to d12 are sent from each gate drive circuit 150 after the start of irradiation of the radiation 16 is determined.

  If it is determined in step S26 that the reading of the charges accumulated in all the pixels 102 has not been completed, the process stays in step S26 until it is determined that the reading has been completed, and the reading of the charges accumulated in all the pixels 102 has been completed. If so, perform radiography. That is, the radiation 16 is exposed, and the charge accumulated in the pixel 102 by the exposure of the radiation 16 is read. Specifically, the first reading control unit 130 ends the execution of the scan mode to start exposure and shifts to the exposure state (step S27). That is, even if the end signals d1 to d12 are sent, the first read control unit 130 does not output the drive signals c1 to c12 to the gate drive circuits 150 thereafter. The first read control unit 130 turns on the switch 160 of the charge amplifier 116 at the same time as the scan mode ends. Thereby, unnecessary charges stored in the capacitor 158 can be released, and the image quality of the radiation image can be improved.

  As shown in FIG. 14, the scan mode is repeatedly executed until it is determined that the radiation source 34 has started irradiation of the radiation 16. Timing t1 indicates the timing when it is determined that the irradiation of the radiation 16 is started. An arrow A indicates one cycle of the scan mode, and the time is about 5 msec. When it is determined that the irradiation of the radiation 16 has been started, when the cycle of the current scan mode is completed, the execution of the scan mode is terminated and the exposure state is entered.

  When the execution of the scan mode is finished in step S27, the elapsed time determination unit 134 determines whether or not a predetermined time has elapsed since it was determined that the irradiation of the radiation 16 was started (step S28). . If it is determined in step S28 that a predetermined time has not elapsed since the start of irradiation with the radiation 16, the process stays in step S28 until the predetermined time has elapsed. Since this predetermined time is the irradiation time corresponding to the imaging region and the diagnostic purpose selected by the user, it is determined in step S28 whether or not the irradiation of the radiation 16 has ended. Therefore, exposure for radiography is performed until a predetermined time elapses after the execution of the scan mode is completed.

  On the other hand, if it is determined in step S28 that a predetermined time has elapsed since the start of irradiation of the radiation 16, the second reading is performed in order to end the exposure and read out the electric charge obtained by the exposure of the radiation 16. The control unit 136 starts executing the sequential read mode (step S29). At this time, the second read control unit 136 outputs a read start signal to the system controller 24 via the communication unit 126 prior to starting execution of the sequential read mode, or at the start or after the start. As a result, the system controller 24 knows that the image data of the radiation image will be sent from the electronic cassette 20 and can prepare to receive the image data.

  When the sequential read mode is executed, the second read control unit 136 outputs the drive signal a1 to the first gate drive circuit 150. When the first gate driving circuit 150 receives the driving signal a1, the first gate driving circuit 150 sequentially selects the gate lines 110 to which the first gate driving circuit 150 is responsible from the 0th row and outputs a gate signal to the selected gate line 110 so that the first gate driving circuit 150 is in charge of itself. The charges accumulated in the pixels 102 in the area to be read are sequentially read from the 0th row in units of rows. As a result, the charges accumulated in the pixels 102 in the region in charge of the first gate driving circuit 150 are sequentially read out from the 0th row to the 239th row in units of rows. When selecting the 239th row, the first gate driving circuit 150 outputs an end signal b1 to the cassette control unit 122.

  When receiving the end signal b1, the second read control unit 136 outputs the drive signal a2 to the second gate drive circuit 150. Such an operation is performed up to the twelfth gate drive circuit 150. Thereby, the electric charges accumulated in the pixels 102 from the 0th row to the 2879th row of the radiation conversion panel 64 are sequentially read out in units of rows. The electric charges sequentially read out in units of rows are input to the charge amplifiers 116 of the respective columns, and thereafter stored in the memory 124 as electric signals of digital signals via the multiplexer unit 118 and the AD conversion unit 120. That is, the memory 124 sequentially stores image data for one row obtained in units of rows.

  A timing t3 shown in FIG. 14 indicates a timing at which it is determined in step S28 that a predetermined time has elapsed, and the execution of the read mode is started almost simultaneously with the timing t3 or immediately after the timing t3. . Simultaneously with the start of the sequential read mode, a read start signal is output from the second read control unit 136 toward the system controller 24. An arrow B indicates one cycle in the sequential reading mode, and the time is about 500 msec. That is, one cycle of the read mode is sequentially performed from when the driving signal a1 is input to the first gate driving circuit 150 until the twelfth gate driving circuit 150 outputs the end signal b12.

  The cassette control unit 122 controls the switches 160 of the charge amplifiers 116 to be in an off state while executing the sequential reading mode. Thus, each charge amplifier 116 can output the input charge signal as a voltage signal.

  When the execution of the sequential reading mode is started, the cassette control unit 122 starts an operation of sequentially transmitting image data for one row obtained in units of rows to the system controller 24 (step S30). That is, when one line of image data is stored in the memory 124, the stored image data is transmitted to the system controller 24 via the communication unit 126.

  Next, the second reading control unit 136 determines whether or not reading of the charges accumulated in all the pixels 102 has been completed (i.e. reading of charges for one frame has been completed) by executing the sequential reading mode ( Step S31). That is, it is determined whether or not one cycle of the sequential read mode has been completed. Specifically, the second readout control unit 136 determines whether or not the end signal b12 is sent from the twelfth gate drive circuit 150.

  If it is determined in step S31 that the reading of the charges accumulated in all the pixels 102 has not been completed, the process remains in step S31 until it is determined that the reading has been completed, and the reading of the charges accumulated in all the pixels 102 has been completed. If it is determined, the second read control unit 136 ends the execution of the sequential read mode (step S32). At this time, the second read control unit 136 outputs a read end signal to the system controller 24 via the communication unit 126.

  Next, the cassette control unit 122 determines whether or not the number of shots (the number of shots set by the user) stored in step S21 has been shot (exposure and sequential readout for the number of shots have been executed) (step S21). Step S33). If it is determined in step S33 that the number of stored shots has not been taken, the process returns to step S22 and the above operation is repeated. If it is determined that the stored number of shots has been taken, the process ends.

  FIG. 15 is a time chart showing the operation of the electronic cassette 20 when the number of shots is set to two. Until the first radiation 16 is emitted, the first reading control unit 130 of the electronic cassette 20 repeatedly executes the scan mode. Then, irradiation of the radiation 16 from the radiation source 34 is started, and it is determined by the irradiation start determination unit 132 that irradiation of the radiation 16 has started. When one cycle of the currently performed scan mode is completed, the exposure state is entered. After that, when a predetermined time elapses (when irradiation of the radiation 16 is finished), the second readout control unit 136 sequentially executes a readout mode, and reads out the charges accumulated in the pixels 102 by the irradiation of the radiation 16. . Thereafter, again, the first read control unit 130 repeatedly executes the scan mode. Then, it is determined by the irradiation start determination unit 132 that the irradiation of the radiation 16 has started, and when one cycle of the currently performed scan mode is completed, the exposure state is entered. Thereafter, when a predetermined time has elapsed (when the irradiation of the radiation 16 is finished), the charge accumulated in the pixel 102 is read, and the process is terminated. At this time, the user can irradiate the subject 14 twice with the radiation 16 by operating the radiation switch 38 twice with a certain interval.

  As described above, before the radiation 16 is irradiated, the charge accumulated in the pixel 102 is read in the scan mode in which the reading can be sequentially performed at a higher speed than the reading mode, and the digital value obtained by reading the charge is larger than the threshold value. Since it is determined that the irradiation of the radiation 16 has been started and exposure is started, it is not necessary to synchronize the imaging timing (synchronization of the irradiation timing of the radiation 16 and the exposure timing of the electronic cassette 20), and the radiation image can be satisfactorily Can be imaged.

  Further, in the scan mode, the charges accumulated in the pixels 102 are simultaneously read out in units of a plurality of rows, so that it is possible to determine the irradiation start of the radiation 16 early and accurately. In other words, since the charges accumulated in the pixel 102 are added and read out, the digital value obtained when the radiation 16 is irradiated is dramatically larger than when the radiation 16 is not irradiated. The irradiation start of the radiation 16 can be determined at an early stage. On the other hand, if the threshold value is simply lowered without adding charges, the radiation start of radiation 16 can be detected early as much as the lowered value, but the ratio of noise to the threshold increases, and accurate radiation 16 Irradiation start cannot be detected.

  In the scan mode, since reading is performed in units of a plurality of rows, the reading speed of one frame image can be increased (one cycle of the scan mode can be shortened), and the irradiation of the radiation 16 is started. Even when it is determined that the exposure has been performed, the time required to shift to the exposure state can be shortened.

  In the scan mode, each gate drive circuit 150 sequentially reads out the charges accumulated in the pixels 102 in the area that the gate drive circuit 150 is responsible for from the 0th row in units of rows, so that any region of the radiation conversion panel 64 is irradiated with the radiation 16. Even if it is done, it can be detected early that the irradiation of the radiation 16 has started. Temporarily, in order to detect the start of irradiation of the radiation 16, the charge accumulated in the pixel 102 is sequentially read out in the readout mode, and the region from the 2000th line to the 2879th line is irradiated with the radiation 16. In the period in which the charges accumulated in the pixels 102 from the 0th row to the 1999th row are read, irradiation of the radiation 16 cannot be detected. However, since each gate driving circuit 150 reads out the charges accumulated in the pixels 102 in units of rows from the 0th row to the 239th row, that is, reads out the charges accumulated in the pixels 102 at intervals of 240 rows. Even if the area 16 is irradiated with the radiation 16, it can be detected quickly.

  The electronic cassette 20 executes the scan mode until it is determined that the irradiation of the radiation 16 is started, and shifts to the exposure state when it is determined that the irradiation of the radiation 16 is started. The radiation apparatus 18 and the system controller 24 are not electrically connected, and the cost is reduced. Since the scan mode is executed until the start of irradiation of the radiation 16 is determined, unnecessary charges accumulated in the pixels 102 can be removed, and noise in the radiation image can be reduced.

  Further, when it is determined that the irradiation of the radiation 16 is started, the scan mode is ended and the exposure state is shifted, so that the radiation 16 that is image information is not wasted. When the irradiation time (predetermined time) elapses from the start of the irradiation of the radiation 16, the readout mode is sequentially executed, so that the pixel exposure period can be suppressed to the minimum necessary, and noise of the radiation image can be further reduced. . Further, it is not necessary to provide a separate sensor for detecting radiation, and the cost is reduced.

  The above embodiment can be modified as follows.

  (Modification 1) In the above embodiment, when it is determined that the radiation 16 has been irradiated during execution of the scan mode, the exposure state is not shifted until one cycle is completed, but during the execution of the scan mode. When it is determined that the radiation 16 has been irradiated, the exposure state may be immediately shifted.

  FIGS. 16 and 17 are diagrams showing the state of charges accumulated in the pixels 102 in each row when the radiation 16 is detected and the state shifts to the accumulation state after the end of one cycle of the scan mode. While the scan mode is being executed, each gate driving circuit 150 sequentially reads out the charges accumulated in the pixels 102 from the 0th row in units of rows. In this case, for example, even if it is determined that the digital value obtained by reading out the charges accumulated in the pixels 102 in the 0th row is larger than the threshold value and the radiation is detected, the scan mode is in the 239th row. The exposure state cannot be shifted until the charge accumulated in the pixel 102 is read out.

  Accordingly, even after the radiation 16 is detected, the charge accumulated in the pixel 102 due to the irradiation of the radiation 16 is read (discarded) by executing the scan mode, and the radiation 16 having image information is wasted. Will do. This is even more so when radiation 16 is detected in the early stages of one cycle of the scan mode. That is, the closer the timing at which it is detected that the radiation 16 has been applied to the timing for reading out the charges accumulated in the pixels 102 in the 239th row, the more the radiation 16 is not wasted.

  More specifically, as shown in FIG. 16, when the radiation 16 is detected by reading the charges of the pixel 102 in the 0th row, the pixels in the 1st to 239th rows are subsequently executed by executing the scan mode. Since the charges accumulated in the row 102 are sequentially read out in units of rows, the charges accumulated in the pixels 102 from the first row to the 239th row by the irradiation of the radiation 16 are discarded. For this reason, the charge accumulated by the irradiation of the radiation 16 is wasted. The relationship between the charge amount Q0 accumulated in the pixel 102 in the 0th row obtained by exposure for radiography and the charge amount Q239 accumulated in the pixel 102 in the 239th row is Q0> Q239, and the difference therebetween And the variation in the amount of charge accumulated in the pixels 102 in each row is large.

  On the other hand, as shown in FIG. 17, when the radiation 16 is detected by reading the charges on the 238th row, only the charges accumulated in the pixels 102 on the 239th row are read out. Only the charge accumulated in the pixels 102 in the row is discarded. In this case, the charge amount Q0 accumulated in the pixel 102 in the 0th row obtained by exposure for radiography, the charge amount Q238 accumulated in the pixel 102 in the 238th row, and the pixel 102 in the 239th row. The relationship between the charge amount Q239 stored in the pixel and the charge amount Q239 becomes Q0> Q238> Q239, but the difference is small, and the variation in the charge amount stored in the pixels 102 in each row is small.

  As described above, the amount of electric charge accumulated in the pixels 102 in each row by exposure for radiography depends on the timing of irradiation of the radiation 16 and varies.

  Therefore, in the first modification, when the irradiation of the radiation 16 is detected, after the detection of the radiation 16, the state shifts to the accumulation state without reading out the charges accumulated in the pixels 102. Specifically, when the cassette control unit 122 detects the start of irradiation of the radiation 16, it sends a stop signal for stopping the reading to each gate drive circuit 150. When the driving signals c1 to c12 are sent, each gate driving circuit 150 sequentially selects the gate line 110, and outputs the gate signal to the selected gate line 110, so that the charge accumulated in the pixel 102 is changed. Although an operation of sequentially reading in row units is performed, when a stop signal is sent, a mask process is performed and a gate signal is not output from the gate drive circuit 150. That is, the first readout control unit 130 prohibits readout of the charge accumulated in the pixel 102 by executing the scan mode. In this case, each gate driving circuit 150 continuously performs the operation of sequentially selecting the gate lines 110 when the stop signal is sent (although the scan mode is continuously performed), the mask processing is performed. Therefore, the gate signal is not output to the selected gate line 110. Thereby, after the detection of the radiation 16, it is possible to shift to the exposure state.

  For example, when each gate driving circuit 150 outputs a gate signal to the gate line 110 of the 0th row and then a stop signal is sent, the stop signal is sent as the first row and the second row. Even after this, the gate lines 110 are sequentially selected, but no gate signal is output to the selected gate lines 110. In this case, each gate drive circuit 150 sequentially selects the gate lines 110 even when a stop signal is sent. Therefore, after selecting the gate line 110 in the 239th row, each gate drive circuit 150 is selected. 150 outputs the end signals d1 to d12. The first reading control unit 130 ends the scan mode when the end signals d1 to d12 are sent from the gate driving circuits 150.

  FIG. 18 is a diagram illustrating the state of charges accumulated in the pixels 102 in each row when reading of the charges of the pixels 102 in the scan mode is immediately terminated when the radiation 16 is detected and the storage state is entered.

  FIG. 18 is a diagram illustrating a state of charges accumulated in the pixels 102 in each row when the radiation 16 is detected by reading out the charges accumulated in the pixels 102 in the zero row. When the cassette control unit 122 detects radiation, it sends a stop signal to each gate drive circuit 150. Therefore, the charges accumulated in the pixels 102 in the second and subsequent rows are not read out, and the charges are accumulated as they are by irradiation with the radiation 16. ing. In this case, the charge amount Q0 accumulated in the pixel 102 in the 0th row obtained by the radiographic exposure, the charge amount Q1 accumulated in the pixel 102 in the first row, and the pixel 102 in the 239th row. The charge amount Q239 satisfies the relationship Q0 <Q1 = Q239, and the difference in charge amount between Q0, Q1, and Q239 is small. Therefore, exposure can be performed without wasting radiation 16 having image information, and variation can be reduced.

  The operation of the cassette control unit 122 in the first modification is substantially the same as the flowchart shown in FIG. 13, but when the irradiation start determination unit 132 determines that the irradiation of the radiation 16 has started in step S24 of FIG. The first read control unit 130 sends a stop signal to each gate drive circuit 150 and proceeds to the operation of step S25. Thereby, it can shift to an exposure state. In step S26, the first read control unit 130 determines whether or not the end signals d1 to d12 are sent from each gate driving circuit 150, and determines that the end signals d1 to d12 are sent, in step S27. End scan mode execution.

  As described above, when it is determined that the irradiation of the radiation 16 is started, the electronic cassette 20 outputs a stop signal to each gate driving circuit 150, so that the scan mode continues until one cycle is completed. Since the electric charge accumulated in 102 is not read out, the radiation 16 having image information can be imaged without wasting it.

  (Modification 2) In the above-described embodiment and Modification 1, the number of shots setting unit 224 of the system controller 24 sets the number of shots input by the user's operation of the input unit 200 and transmits it to the electronic cassette 20. However, the number of shots may also be recorded in the table 218 according to the shooting site and the purpose of diagnosis. In this case, the imaging condition setting unit 222 reads out and sets the number of images to be imaged according to the imaging region selected by the user and the purpose of diagnosis, and transmits the set number of images to the electronic cassette 20.

  (Modification 3) In the above embodiment and Modifications 1 and 2, when radiation imaging is performed a plurality of times, the radiation source 34 is configured to irradiate the radiation 16 a plurality of times by operating the radiation switch 38 of the user. However, when performing radiography a plurality of times, the radiation source 34 continuously irradiates the radiation 16 for a certain period of time, and the electronic cassette 20 may perform radiation imaging a plurality of times during the certain period of time. Good. The predetermined time can be set by the user operating the input device of the radiation control device 36, and the radiation control device 36 sets the radiation source 34 to emit the radiation 16 for the set fixed time. Control.

  FIG. 19 is a time chart showing the operation of the electronic cassette 20 in the third modification. Until the radiation 16 is irradiated, the first readout control unit 130 of the electronic cassette 20 repeatedly executes the scan mode. Then, when the irradiation of the radiation 16 is started by the radiation source 34, the irradiation start determination unit 132 determines that the irradiation of the radiation 16 has started and shifts to the exposure state. Thereafter, when a predetermined time elapses, the second read control unit 136 sequentially executes the read mode, and reads the charges accumulated in the pixels 102 by the irradiation of the radiation 16. Thereafter, the first read control unit 130 executes the scan mode again, but since the radiation 16 continues to be irradiated, the irradiation start determining unit 132 immediately determines that the irradiation of the radiation 16 has started, and enters the exposure state. Transition. Thereafter, when a predetermined time elapses, the second read control unit 136 sequentially executes the read mode, and reads the charge accumulated in the pixel 102 by the irradiation of the radiation 16. In this manner, radiation imaging may be performed a plurality of times while the radiation 16 is being irradiated. This predetermined time may be an irradiation time corresponding to the imaging region and diagnosis purpose selected by the user, may be a default value, or may be an irradiation time individually set by the user. Good.

  (Modification 4) In the above-described embodiment and Modifications 1 to 3, the scan mode reads the charges accumulated in all the pixels 102 by sequentially performing an operation of simultaneously reading out in units of a plurality of rows. However, only pixels in a predetermined row may be read out. Hereinafter, Modification 4 will be described in detail.

  FIG. 20 is a partial detail view of the radiation conversion panel 64 of the fourth modification. The radiation conversion panel 64 includes a gate line 250, and the gate line 250 is directly connected to the cassette control unit 122. The gate line 250 is connected to the pixel 254 through the TFT 252, and the charge accumulated in the pixel 254 is read from the signal line 112 when the TFT 252 is turned on. The gate line 250 is for supplying a gate signal to the TFT 252 for reading out charges accumulated in the pixel 254 in the scan mode. That is, the gate line 250, the TFT 252, and the pixel 254 are provided separately from the gate line 110, the TFT 72, and the pixel 102 for the scan mode. One gate line 250 may be provided on the radiation conversion panel 64, or one gate line 250 may be provided between the gate drive circuits 150. A plurality of gate lines 250 may be provided at equal intervals over the entire region of the radiation conversion panel 64. For example, between the first gate driving circuit 150 and the second gate driving circuit 150, between the sixth gate driving circuit 150 and the seventh gate driving circuit 150, and between the eleventh gate driving circuit 150 and the twelfth gate. By providing the gate line 250 between the gate driving circuits 150, any pixel 254 can receive the radiation 16 regardless of which region is irradiated with the radiation 16. The pixels 254 connected to the gate line 250 are pixels in a predetermined row.

  Although not shown, 240 gate lines 110 are connected to each gate driving circuit 150, and the pixel 102 is connected to each gate line 110 via a TFT 72.

  In the scan mode according to the fourth modification, the first readout control unit 130 outputs the gate signal directly to the gate line 250, thereby repeatedly reading out the charges accumulated in the pixels 254 in units of rows. For example, when there is only one gate line 250, when a gate signal is output to the gate line 250, one cycle of the scan mode is completed, and the gate signal is output to the gate line 250 again in the next cycle. Thus, the charge accumulated in the pixel 254 is repeatedly read out.

  When there are a plurality of gate lines 250, the first readout control unit 130 sequentially outputs gate signals to the gate lines 250 in order to sequentially read out the charges accumulated in the pixels 254 in units of rows. For example, when there are three gate lines 250, the gate signal is output to the gate line 250 of the 0th row, thereby reading out the charge accumulated in the pixels 254 connected to the gate line 250 of the 0th row, Next, by outputting a gate signal to the gate line 250 in the first row, the charges accumulated in the pixels 254 connected to the gate line 250 in the first row are read, and finally, the gate line 250 in the second row is read out. The gate signal is output to the first row to read out the electric charge accumulated in the pixel 254 connected to the gate line 250 in the second row. When a gate signal is output to the gate line 250 of the second row, one cycle of the scan mode is completed, and the gate signal is output to the gate line 250 of the 0th row again in the next cycle.

  If the irradiation start determination unit 132 determines that the irradiation of the radiation 16 has started, the execution of the scan mode is immediately terminated and the exposure state is entered. When the irradiation start determination unit 132 determines the start of irradiation of the radiation 16, the gate drive circuit 150 does not output a gate signal to the gate line 250 thereafter. For example, if there are three gate lines 250 and it is determined that the digital value obtained by the output of the gate signal to the gate line 250 in the zeroth row is greater than the threshold value, the first and second rows Execution of the scan mode is immediately terminated without outputting a gate signal to the gate line 250 of the eye. Thereby, power consumption by the scan mode can be suppressed.

  Then, after the radiation 16 is detected (after it is determined that the irradiation of the radiation 16 has started), when a predetermined time elapses (when the irradiation of the radiation 16 ends), the second readout control unit 136 The sequential read mode is executed.

  In other words, the electronic cassette 20 includes a plurality of pixels (first pixels) 102 arranged in a matrix and a plurality of TFTs (first pixels) arranged in a matrix for reading out electrical signals accumulated in the plurality of pixels 102. Switching element) 72, a plurality of gate lines (first gate lines) 110 parallel to the row direction connected to the TFTs 72 of each row, and a plurality of gate lines 110 are connected to each other through the gate lines 110 to gate the TFTs 72 of each row. It includes at least a plurality of gate drive circuits 150 arranged in parallel along the column direction for outputting signals, and a plurality of signal lines 112 parallel to the column direction for reading out electrical signals accumulated in the plurality of pixels 102.

  Further, the electronic cassette 20 reads a plurality of pixels (second pixels) 254 arranged along the row direction in a planar shape on which the plurality of pixels 102 are arranged, and an electric signal accumulated in the pixels 102. A plurality of TFTs (second switching elements) 252 arranged along the row direction and at least one gate line 250 connected to the TFT 252 in the row direction are provided.

  The gates of the TFTs 72 and 252 are connected to the gate lines 110 and 250, and the sources are connected to the pixels 102 and 254. The drains of the TFTs 72 and 252 are connected to the signal line 112. When the driving signal a is input, each gate driving circuit 150 sequentially selects the gate line 110 connected to itself, and outputs the gate signal to the selected gate line 110, thereby turning on the TFT 72, The electric signals accumulated in the pixels 102 connected to the self through a plurality of signal lines 112 are sequentially read out in units of rows.

  The first readout control unit 130 sequentially inputs gate signals to the gate line 250, thereby executing a scan mode in which the electrical signals accumulated in the pixels 254 are sequentially read out in units of one row. The second reading control unit 136 sequentially inputs the driving signal a to each gate driving circuit 150 to sequentially drive each gate driving circuit 150 and sequentially reads out the electrical signals of the plurality of pixels 102 in units of one row. Execute read mode.

  The operation of the cassette control unit 122 in Modification 4 is substantially the same as the flowchart shown in FIG. 13, but when the irradiation start determination unit 132 determines that the irradiation of the radiation 16 has started in Step S <b> 24 of FIG. 13, The first read control unit 130 immediately stops outputting the gate signal to the gate line 250 (ends execution of the scan mode), and proceeds to the operation of step S25. When the timer is started in step S25, the process proceeds directly to step S28 without passing through the operations of steps S26 and S27.

  In the fourth modification, the pixel 102 is in an exposure state even during the execution of the scan mode because the charge is not read out during the execution of the scan mode. Therefore, charges corresponding to the irradiated radiation 16 can be accumulated without wasting the radiation 16 that is image information. In addition, since the charge accumulated in the pixel 254 is read and the irradiation start of the radiation 16 is determined, the irradiation start timing of the radiation 16 can be known. In addition, when the irradiation time elapses from the irradiation start timing of the radiation 16, the mode sequentially shifts to the reading mode. Therefore, exposure is not performed after the irradiation of the radiation 16 is completed, and noise in the radiation image can be reduced. Since the start of irradiation with the radiation 16 is determined by reading out the charge accumulated in the pixel 254, power consumption in the scan mode can be suppressed.

  In the scan mode according to the fourth modification, as in the sequential scan mode, the charge accumulated in the pixels 102 for one row may be read out in a time of 173 μsec. As described above, since the charge accumulated in the pixel 102 is read out in a time of 173 μsec, the determination accuracy of the start of irradiation of the radiation 16 does not decrease without adding the charge accumulated in the pixel 102. Further, since the number of scan mode gate lines 250 is smaller than that of the radiation imaging gate lines 110, even if the charges accumulated in one row of pixels 102 are sequentially read out in the same time as the readout mode, the scan mode gate lines 250 can be read. One cycle time can be shortened. For example, if the number of gate lines 250 is 29, the time of one cycle in the scan mode is about 5 msec, which is the same time as one cycle of the scan mode of the above embodiment.

  When a plurality of gate lines 250 are provided, the user operates the input unit 200 of the console 26 so that one or two gate lines 250 used for executing the scan mode are selected from the plurality of gate lines 250. You may select more than this. Since the user can recognize in advance which region of the electronic cassette 20 is irradiated with the radiation 16 by the radiation source 34, the user selects the gate line 250 corresponding to the region irradiated with the radiation 16. Information indicating the selected gate line 250 is sent from the console 26 to the electronic cassette 20 via the system controller 24. The first read control unit 130 outputs a gate signal only to the selected gate line 250 when executing the scan mode.

  Thereby, the irradiation start determination part 132 can determine the irradiation start of the radiation 16 early and reliably. In addition, since no gate signal is output to the gate line 250 in the region where the radiation 16 is not irradiated, power consumption due to execution of the scan mode can be further suppressed.

  In the case where a plurality of gate lines 250 are provided, a large number of gate lines 250 in a region where radiation 16 is likely to be irradiated or a region where radiation 16 is irradiated are selected, and a region where radiation 16 is not likely or not irradiated The number of the gate lines 250 may be selected to be small. When executing the scan mode, a gate signal is output only to the selected gate line 250. The region where the radiation 16 is highly likely to be irradiated or the irradiated region can be designated by the user operating the input unit 200 of the console 26. In this case, the user may directly specify the region that is likely to be irradiated with the radiation 16 or the region to be irradiated, and the system controller 24 controls the region selected according to the imaging region and the diagnostic purpose selected by the user. The unit 212 may read and specify from the table 218. The control unit 212 of the system controller 24 selects the gate line 110 used for executing the scan mode based on the designated area, and sends information indicating the selected gate line 110 to the electronic cassette 20.

  (Modification 5) In Modification 4, the scan mode gate line 250, TFT 252, and pixel 254 are provided separately from the gate line 110, TFT 72, and pixel 102, but a predetermined gate line is used. 110, TFT 72, and pixel 102 may also be used for the scan mode.

  FIG. 21 is a partial detail view of the radiation conversion panel 64 of the fifth modification. Although not shown, 240 gate lines 110 are connected to each gate driving circuit 150, and each gate line 110 is connected to the pixel 102 via the TFT 72. One of the 240 gate lines 110 connected to each gate drive circuit 150 is connected to the cassette control unit 122 via a bypass line 260. A switching element 262 is provided in the bypass line 260.

  Here, the bypass line 260 connected to the gate line 110 of the first gate drive circuit 150 is referred to as a first bypass line 260, and the bypass line connected to the gate line 110 of the second gate drive circuit 150. Is referred to as a second bypass line 260. Similarly, each bypass line connected to the gate line 110 of the third to twelfth gate drive circuits 150 is referred to as a third to twelfth bypass line 260. In addition, for convenience, the gate line 110 to which the first bypass line 260 is connected is referred to as a first scan-and-use gate line 110, and the gate line 110 to which the second bypass line 260 is connected is referred to as a second scan. This is called a dual-purpose gate line 110. Similarly, the gate line 110 connected to the third to twelfth bypass lines 260 is referred to as a third to twelfth scan-use gate line 110. In the fifth modification, for convenience, one of the 240 gate lines 110 connected to the gate drive circuit 150 is the scan-use gate line 110, but the scan-use gate line 110 is provided. There may be a gate drive circuit 150 that is not provided, or there may be a gate drive circuit 150 provided with a plurality of scan / use gate lines 110.

  In the scan mode according to the fifth modification, all the switching elements 262 are turned on or some of the switching elements 262 are turned on, and the first read control unit 130 includes the bypass line 260 in which the switching elements 262 are turned on. The gate signals are sequentially output, and the charges accumulated in the pixels 102 are sequentially read out in units of rows. When gate signals are output to all the bypass lines 260 in which the switching elements 262 are turned on, one cycle of the scan mode is completed, and the process proceeds to the next cycle.

  For example, when the switching elements 262 of all the bypass lines 260 are on, the first read control unit 130 outputs a gate signal to the first bypass line 260 to connect to the first scan / use gate line 110. The charges accumulated in the pixel 102 are read out in units of rows. Then, by outputting a gate signal to the second bypass line 260, the charges accumulated in the pixels 102 connected to the second scan / use gate line 110 are read out in units of rows. As described above, the first read control unit 130 sequentially outputs the gate signals from the first bypass line 260 to the twelfth bypass line 260 and is connected to the first to twelfth scan-use gate lines 110. The charges accumulated in the pixels 102 are sequentially read out in units of rows. When the gate signal is output to the twelfth bypass line 260, one cycle of the scan mode is completed, and the gate signal is output to the first bypass line 260 in the next cycle.

  That is, the electronic cassette 20 is connected to a plurality of pixels 102 arranged in a matrix, a plurality of TFTs 72 arranged in a matrix for reading out electric signals accumulated in the plurality of pixels 102, and the TFTs 72 in each row. A plurality of gate lines 110 parallel to the row direction, and a plurality of gate lines 110 connected to each other, and a plurality of gate drive circuits arranged in parallel along the column direction outputting gate signals to the TFTs 72 of each row via the gate lines 110 150 and a plurality of signal lines 112 parallel to the column direction for reading out electrical signals accumulated in the plurality of pixels 102.

  In addition, a bypass line 260 provided with a switching element 262 is connected to at least one of the plurality of gate lines 110. That is, one or more bypass lines 260 each having a switching element 262 connected to at least one gate line 110 among the plurality of gate lines 110 are provided.

  The gate of the TFT 72 is connected to the gate line 110, and the source is connected to the pixel 102. The drain of the TFT 72 is connected to the signal line 112. When the driving signal a is input, each gate driving circuit 150 sequentially selects the gate line 110 connected to itself, and outputs the gate signal to the selected gate line 110, thereby turning on the TFT 72, The electric signals accumulated in the pixels 102 connected to the self through a plurality of signal lines 112 are sequentially read out in units of rows.

  The first read control unit 130 turns on the switching element 262 of the bypass line 260 connected to the predetermined gate line (scan / gate gate line) 110 and outputs a gate signal to thereby output the predetermined gate. A scan mode is executed in which the electric signals accumulated in the pixels 102 connected to the line 110 are sequentially read out in units of one row. The second reading control unit 136 sequentially inputs the driving signal a to each gate driving circuit 150 to sequentially drive each gate driving circuit 150 and sequentially reads out the electrical signals of the plurality of pixels 102 in units of one row. Execute read mode.

  Here, the user operates the input unit 200 of the console 26 to select the scan / use gate line 110 used to execute the scan mode. The selected scan / use gate line 110 becomes a predetermined gate line 110, and the pixels 102 connected to the selected scan / use gate line 110 become pixels 102 in a predetermined row. Since the user can recognize in advance which region of the electronic cassette 20 is irradiated with the radiation 16 by the radiation source 34, the user selects the scan / gate line 110 corresponding to the region irradiated with the radiation 16. Information indicating the selected scan / use gate line 110 is sent from the console 26 to the electronic cassette 20 via the system controller 24. When executing the scan mode, the first read control unit 130 turns on the switching element 262 of the bypass line 260 connected to the scan / use gate line 110 selected by the user. Note that when the execution of the scan mode ends, the first read control unit 130 turns off all the switching elements 262.

  In the fifth modification, since the gate signal is output only to the selected scan / use gate line 110 during execution of the scan mode, the pixels 102 (predetermined in advance) connected to the selected scan / use gate line 110 are output. The pixels 102 other than the pixel 102) are in an exposed state even when the scan mode is being executed. Therefore, charges corresponding to the irradiated radiation 16 can be accumulated without wasting the radiation 16 that is image information. When the irradiation time elapses from the irradiation start timing of the radiation 16, the mode sequentially shifts to the reading mode. Therefore, exposure is not performed after the irradiation of the radiation 16 is completed, and noise in the radiation image can be reduced.

  Since the user selects the scan / use gate line 110 in the region irradiated with the radiation 16, the irradiation start determination unit 132 can determine the irradiation start of the radiation 16 early and reliably. In addition, since a gate signal is output only to the selected scan / use gate line 110, power consumption due to execution of the scan mode can be suppressed.

  In the scan mode according to the fifth modification, as in the sequential scan mode, the charges accumulated in the pixels 102 for one row may be read out in a time of 173 μsec. As described above, since the charge accumulated in the pixel 102 is read out in a time of 173 μsec, the determination accuracy of the start of irradiation of the radiation 16 does not decrease without adding the charge accumulated in the pixel 102. Further, since the number of the scan-use gate lines 110 is small, even if the charges accumulated in the pixels 102 for one row are read in the same time as the sequential read mode, the time for one cycle in the scan mode can be shortened. .

  It is to be noted that a large number of scan / use gate lines 110 in a region where radiation 16 is likely to be irradiated or a region where radiation 16 is irradiated are selected, and a small number of gate lines 110 in a region where radiation 16 is unlikely to be irradiated or not irradiated. May be. When the scan mode is executed, a gate signal is output only to the selected scan / use gate line 110. The region where the radiation 16 is highly likely to be irradiated or the irradiated region can be designated by the user operating the input unit 200 of the console 26. In this case, the user may directly specify the region that is likely to be irradiated with the radiation 16 or the region to be irradiated, and the system controller 24 controls the region selected according to the imaging region and the diagnostic purpose selected by the user. The unit 212 may read and specify from the table 218. The control unit 212 of the system controller 24 selects the scan / use gate line 110 used for executing the scan mode based on the designated area, and sends information indicating the selected scan / use gate line 110 to the electronic cassette 20.

  (Modification 6) In Modification 4, the scan mode gate line 250, TFT 252, and pixel 254 are provided separately from the gate line 110, TFT 72, and pixel 102, but they are used to execute the scan mode. By driving a predetermined gate driving circuit 150, the gate line 110, the TFT 72, and the pixel 102 in a region in charge of the gate driving circuit 150 may be used for the scan mode.

  When the first read control unit 130 executes the scan mode, the first read control unit 130 outputs a drive signal c to one predetermined gate drive circuit 150. The gate drive circuit 150 to which the drive signal c is input sequentially reads out the charges accumulated in the pixels 102 in the area that it is responsible for from the 0th row to the 239th row in units of rows. Thereby, the electrical signal of the digital signal is sequentially obtained in units of rows, and when the irradiation start determining unit 132 determines that the electrical signal of the digital signal is larger than the threshold value, the first readout control unit 130 is in the scan mode. End execution. The first readout control unit 130 repeats the scan mode until the start of irradiation is determined. That is, when the end signal d is sent from the gate drive circuit 150, the drive signal c is output again to the predetermined gate drive circuit 150. In this case, the time for reading out the charges accumulated in the pixels 102 for one row may be 173 μsec as in the sequential read mode, or 21 μsec as in the scan mode of the above embodiment. .

  The user can select the gate driving circuit 150 used for executing the scan mode by operating the input unit 200 of the console 26. Since the user can recognize in advance which area of the electronic cassette 20 is irradiated with the radiation 16 by the radiation source 34, the gate drive circuit 150 that reads out the pixels 102 corresponding to the area irradiated with the radiation 16. Select. Information indicating the gate driving circuit 150 selected by the user is sent from the console 26 to the electronic cassette 20 via the system controller 24. When the first read control unit 130 executes the scan mode, the gate drive circuit 150 selected by the user is used as a predetermined gate drive circuit 150 and outputs a drive signal c.

  Further, the user may select a plurality of gate drive circuits 150 used for executing the scan mode. In this case, the first read control unit 130 may simultaneously output the drive signal c to each selected gate drive circuit 150. That is, the gate driving circuits 150 may be driven simultaneously. In addition, the first read control unit 130 is sequentially determined in advance so that when the end signal d is sent from one gate driving circuit 150, the driving signal c is output to the next gate driving circuit 150. Alternatively, the gate drive circuit 150 may be driven.

  In the sixth modification, the gate drive circuit 150 other than the selected gate drive circuit 150 does not output a gate signal during execution of the scan mode, so that the selected gate drive circuit 150 is in charge of reading the charge. The pixels 102 other than the pixel 102 in the region to be exposed are in an exposed state even during the execution of the scan mode. Therefore, charges corresponding to the irradiated radiation 16 can be accumulated without wasting the radiation 16 that is image information. When the irradiation time elapses from the irradiation start timing of the radiation 16, the mode sequentially shifts to the reading mode. Therefore, exposure is not performed after the irradiation of the radiation 16 is completed, and noise in the radiation image can be reduced.

  Since the user selects the gate drive circuit 150 that reads out the electric charges accumulated in the pixels 102 in the region irradiated with the radiation 16, the irradiation start determination unit 132 determines the irradiation start of the radiation 16 early and reliably. be able to. In addition, since only the selected gate driving circuit 150 reads out the charges accumulated in the pixel 102, power consumption due to execution of the scan mode can be suppressed.

  (Modification 7) From the viewpoint of reducing power consumption, it is desirable to start the scan mode at an appropriate timing, such as immediately before shooting, for the electronic cassette 20 in a standby state that is not scheduled to be shot soon.

  Therefore, as shown in FIGS. 22 to 27, the electronic cassette 20 according to the modified example 7 sequentially detects the positioning of the subject 14, and predicts the current photographing possibility based on the temporal characteristics of the positioning. Here, the positioning means the position and orientation of the subject 14 when performing radiation imaging under a predetermined arrangement relationship between the radiation device 18 and the electronic cassette 20. The term “positioning” in this specification includes the relative positional relationship between the electronic cassette 20 used for radiography and the subject 14.

  Then, the electronic cassette 20 executes the scan mode after making a transition from the sleep state to the activated state at a timing predicted to be immediately before shooting. At this time, communication via the system controller 24 is not necessary.

  FIG. 22 is a perspective view of the electronic cassette 20 of the seventh modification.

  The electronic cassette 20 further includes three pressure sensors (positioning detection units) 520 and a display unit (start / end notification unit) 522 in addition to the configuration of the above embodiment (see FIG. 2).

  The three pressure sensors 520 are arranged one by one at the center of each side of the three sides of the rectangular flat panel 52 (excluding the short sides of the four sides where the control unit 54 is arranged). ing. The detection surface 524 of each pressure sensor 520 faces the imaging surface 42 side. Thereby, the pressure sensor 520 detects pressure reception from the imaging surface 42 side, and acquires information about pressure. As the pressure sensor 520, a pressure gauge that measures a pressure value may be used, or a pressure switch that performs an on / off operation according to the pressure may be used. In particular, since the pressure switch is small and inexpensive, it is suitable when a plurality of pressure sensors 520 are provided for one electronic cassette 20.

  As an example of the pressure gauge, various types including a diaphragm type, a capsule type, a bellows type, a Bourdon tube, and a piezoelectric element can be adopted. As an example of the pressure switch, various types including a piston type, a microswitch type, and a diaphragm type can be adopted.

  The display unit 522 is provided at an upper end portion of the control unit 54 and notifies the user of a change in the operating state of the electronic cassette 20. The display unit 522 can display various characters and figures, and may be configured using, for example, a liquid crystal panel, an electroluminescence panel, or the like.

  FIG. 23 is a schematic electrical configuration diagram of the electronic cassette 20 of FIG. For convenience of explanation, FIG. 23 shows only one pressure sensor 520 and its connection line.

  The cassette control unit 122 includes a use state identification unit 526 that identifies the use state of the radiation detector 66 in addition to the first readout control unit 130, the irradiation start determination unit 132, the elapsed time determination unit 134, and the second readout control unit 136. Is further provided.

  In the present specification, the term “use state” described above may be applied not only to the radiation detector 66 but also to the electronic cassette 20. This is because the radiation detector 66 is normally housed fixed in the electronic cassette 20 and is substantially synonymous.

  In addition to the memory 124 and the communication unit 126, the cassette control unit 122 is connected to a pressure sensor 520 and a display unit 522. The power supply unit 128 supplies power to the pressure sensor 520 and the display unit 522 in addition to the cassette control unit 122, the memory 124, and the communication unit 126.

  Based on the information related to the positioning of the subject 14, the use state identifying unit 526 is in a state where the electronic cassette 20 is currently used or is scheduled to be used (hereinafter referred to as a “use state”) or not in use. It is identified whether it is in a state (hereinafter referred to as a standby state). The use state identification unit 526 determines whether or not the transition from the sleep state to the start state (or the transition from the start state to the sleep state) is permitted according to the use state (for example, history information) of the acquired electronic cassette 20, An electrical signal is transmitted to instruct the transition of the operating state of the electronic cassette 20.

  FIG. 24 is a flowchart for explaining the operation of the electronic cassette 20 of FIG. The operation of this figure is executed by, for example, performing a timer interrupt at a predetermined time interval (hereinafter referred to as a time interval Δt) in the flowchart of FIG.

  First, the pressure sensor 520 acquires the detection value DV of the electronic cassette 20 at the time interval Δt (step S151). The detected value DV may be any of a measured pressure value, an on / off value (information indicating whether or not a predetermined value that has been set in advance), and the like. In the present modification example 7, it is assumed that the detection value DV is one pressure value acquired from the pressure sensor 520 for convenience of explanation. In addition, the average value of the pressure value acquired from the three pressure sensors 520 may be sufficient, and a weighted average value may be sufficient.

  Next, the use state identifying unit 526 compares the detected value DV acquired from the pressure sensor 520 with the predetermined threshold value TH (step S152). Here, the threshold value TH is a threshold value for identifying whether the current electronic cassette 20 is in use or in a standby state.

If, DV> If the condition is satisfied for TH (YES), it acquires the usage state value _{S U} of the electronic cassette 20, identifies the most recent use state of the electronic cassette 20 (step S153). Here, use state value S _U is a variable representing the state of use of the most recent of the electronic cassette 20 (e.g., the previous detection). In the seventh modification, S _U = 1 is set when the use state is “in use”, and S _U = 0 is set when the use state is “standby state”. The use state value _SU is not limited to binary (1 or 0), and may be three or more types.

When the use state value S _U is 1 (in-use state), the use state identification unit 526 maintains the use state value S _U (S _U = 1) and resets the value of the counter C to 0 (step) S154). Note that the counter C corresponds to the number of times that DV ≦ TH (NO) is continuously determined in step S152 after the electronic cassette 20 is activated and transitioned from the in-use state to the standby state.

On the other hand, when the use state value _SU is 0 (standby state), the operating state of the electronic cassette 20 is changed from the sleep state to the activated state (step S155). At this time, the use state identification unit 526 transmits an activation signal and transmits a predetermined control signal to the display unit 522. In other words, the use state identifying unit 526 estimates that the time when pressure is received from the outside (subject 14) is the timing immediately before the radiography, and permits the electronic cassette 20 to shift to the activated state.

Next, the display unit 522 receives the control signal from the use state identification unit 526 and notifies the user (step S156). For example, the display unit 522 displays a message or the like indicating that the electronic cassette 20 has transitioned to the activated state on the screen. Thereafter, the use state identification unit 526 updates the use state value _SU to 1 and resets the value of the counter C to 0 (step S154).

  In this way, the electronic cassette 20 identifies the use state based on the detection value DV, thereby transitioning from the sleep state to the start state or maintaining the start state as it is.

By the way, returning to step S152, when the condition of DV ≦ TH (NO) is satisfied, the operating state of the electronic cassette 20 is acquired to determine whether the electronic cassette 20 is in the activated state or the sleep state (step S157). When the electronic cassette 20 is in the activated state, the use state identification unit 526 compares the magnitude relationship between the counter C and the threshold value C _SL (step S158).

If C <C _SL (YES), the use state identifying unit 526 adds 1 to the value of the counter C (step S159).

On the other hand, if C ≧ C _SL (NO), the operating state of the electronic cassette 20 is shifted from the activated state to the sleep state (step S160). At this time, the use state identification unit 526 transmits a sleep signal and a predetermined control signal to the display unit 522. In other words, when the predetermined time has elapsed after the pressing from the subject 14 is released, the use state identifying unit 526 estimates that the radiation imaging has ended, and permits the electronic cassette 20 to enter the sleep state.

Next, the display unit 522 receives the control signal from the use state identification unit 526 and notifies the user (step S161). For example, the display unit 522 displays a message or the like indicating that the electronic cassette 20 has transitioned to the sleep state on the screen. Then, using the state identification unit 526 updates the use state value _{S U} to 0 (step S162).

Incidentally, the process returns to step S157, if the electronic cassette 20 is in the sleep state, the use state identification unit 526 maintains the use state values _{S U (S U = 0)} ( step S162).

  Thus, the electronic cassette 20 maintains the activated state (or sleep state) as it is by identifying the use state based on the detection value DV, or transitions from the activated state to the sleep state.

  Next, an operation example of the electronic cassette 20 assumed immediately before radiography will be specifically described with reference to schematic explanatory diagrams showing time series of FIGS.

  First, the user places the electronic cassette 20 in a predetermined storage location, and waits for the electronic cassette 20 (time 0 to t1). Then, the user takes out the electronic cassette 20 from the storage location and carries the electronic cassette 20 into the photographing site (time t1 to t2). The detection value DV measured in step S151 is always 0. At this time, the execution of steps S151, S152, S157, and S162 in FIG. 24 is repeated, and the electronic cassette 20 maintains the sleep state.

  Next, the user prepares for radiography using the electronic cassette 20 (time t2 to t5). When positioning the subject 14, the user closes (or places) the electronic cassette 20 behind (or below) the imaging region of the subject 14. At this time, a load is applied from the imaging surface 42 side of the electronic cassette 20 and the detection surface 524 of the pressure sensor 520 is pressed.

  Then, the detection value DV exceeds the threshold value TH at the time point t3 and increases to the range of the time points t3 to t4. At time t3, steps S151, S152, S153, S155, S156, and S154 in FIG. 24 are executed. At this time, the operating state of the electronic cassette 20 is transitioned from the sleep state to the activated state. Thereafter, the first read control unit 130 starts the scan mode.

  Next, the user repeats shooting (time points t5 to t6), shooting preparation (time points t6 to t9), and shooting (time points t9 to t10).

  For example, it is assumed that the user changes the positioning of the subject 14 in order to change the imaging region during imaging preparation (time t6 to t9). Since the pressure on the electronic cassette 20 is once released, the detection value DV measured in step S151 is below the threshold value TH (time points t7 to t8).

At this time, steps S151, S152, S157, S158, and S159 of FIG. 24 are repeatedly executed from time t7 to time t8, and the counter C is sequentially added. However, the time point t7 to t8, and a relatively short time that does not exceed a predetermined time _{(C SL} · _Δt). Thereafter, at time t8, steps S151, S152, S153, and S154 of FIG. 24 are executed. As a result, the use state value _SU is updated again from 0 (standby state) to 1 (in use state), and the value of the counter C is reset to 0.

  As shown in FIG. 26, after the radiation imaging is completed, the user carries out the electronic cassette 20 and places it in a predetermined storage location (time t12 to t13). After the time t11 when the pressure on the electronic cassette 20 is released and the detection value DV falls below the threshold value TH, the execution of steps S151, S152, S157, S158, and S159 in FIG. 24 is repeated. At this time, the counter C is sequentially added as time passes.

Then, when the counter C exceeds a predetermined threshold C _SL , that is, a predetermined time (C _SL · Δt) from the time t11 when the state is changed from the busy state (S _U = 1) to the standby state (S _U = 0). If exceeded, steps S151, S152, S157, S158, S160, S161, and S162 of FIG. 24 are executed. At this time, the operating state of the electronic cassette 20 is changed from the activated state to the sleep state. At this time, the first reading control unit 130 ends the scan mode.

  As described above, since the positioning detection unit (the pressure sensor 520 in FIGS. 22 and 23) that detects the positioning of the subject 14 with respect to the radiation detector 66 is provided, it is possible to predict the possibility of photographing at the present time according to the positioning. It is. That is, the power consumption can be further reduced by starting the scan mode at an appropriate timing such as immediately before shooting.

  Here, it goes without saying that the scan mode is not limited to the read operation shown in the above embodiment or the fourth modification, and various methods can be adopted. For example, in the scan mode, the electrical signals stored in the pixels 102 and 254 may be read out with a smaller number of readings than the total number of rows of the radiation detector 66 (2880 rows in the above embodiment). You may read using sequential read mode.

Moreover, further is provided with the use state identification unit 526 identifies the usage state S _U of the radiation detector 66 based on the detected positioning, the presence or absence of the photographing possible at present with the electronic cassette 20 accurately predicted it can.

Further, the first reading control unit 130 ends the scan mode when it is detected continuously for a predetermined time ( _CSL · Δt) that the subject 14 is not present. As a result, unnecessary scan mode can be avoided, and power consumption can be further reduced.

  It should be noted that any means for detecting the positioning of the subject 14 may be used as long as a change in physical quantity according to the operation of the subject 14 or the like can be detected. For example, instead of the pressure sensor 520, a temperature sensor, a human body / object detection sensor, an optical sensor, or the like may be used.

  In the case of a temperature sensor, a temperature change through the subject 14 that occurs during positioning is detected. Specifically, the amount of heat flows into the electronic cassette 20 (or the amount of heat flows out of the electronic cassette 20) due to the contact between the imaging surface 42 (detection surface 524) and the subject 14 in FIG. A temperature change occurs. By detecting this temperature change with a temperature sensor, the presence or absence of contact between the electronic cassette 20 and the subject 14 can be identified. At this time, the detection value DV shown in FIGS. 24 to 26 uses temperature (or measurement data associated with the temperature) instead of pressure.

  The relationship between the operating state (imaging phase) of the electronic cassette 20 and the temperature change shows a tendency similar to that of the pressure sensor illustrated in FIGS. For example, when contact with the subject 14 is suddenly detected after a state in which there is no contact with the subject 14, it can be estimated that it is immediately before radiography at the time of detection.

  As an example of the temperature sensor, various methods including a resistance temperature detector, a thermistor, a thermocouple (non-grounded type / grounded type) and the like can be adopted. Further, the terminal portion of the temperature sensor may have any shape of a lead shape, an exposed shape, or a box shape.

  In the case of a human body / object detection sensor, the positional relationship between the subject 14 and the electronic cassette 20 during positioning is detected. At the time of radiography, the subject 14 is disposed in close contact with the imaging surface 42 of the electronic cassette 20 or at a predetermined interval in front of it. The positional relationship between the electronic cassette 20 and the subject 14 can be detected by detecting the presence (more specifically, the separation distance) of the subject 14 with a human body / object detection sensor. At this time, the detection value DV shown in FIGS. 24 to 26 uses a distance (or measurement data associated with the distance) instead of the pressure.

  As the human body / object detection sensor, a distance measuring sensor (non-contact sensor) capable of measuring a distance, an obstacle sensor capable of determining the presence / absence of a human body / object within a predetermined range, or the like may be used. In addition, when detecting the presence or absence of close contact between the electronic cassette 20 and the subject 14, a contact sensor may be used.

  As an example of a human body / object detection sensor, various media including not only electromagnetic waves (visible light, infrared rays, microwaves, millimeter waves, etc.) but also ultrasonic waves, laser beams, and the like can be used. Any of the TOF (Time Of Flight) method and the triangulation method may be used as the measurement algorithm.

  FIG. 27 is another perspective view of the electronic cassette 20 of the seventh modification. In place of the three pressure sensors 520 provided in the panel unit 52 shown in FIG. 22, a camera unit (optical sensor) 528 having a circular imaging surface is provided in the center of the upper surface of the control unit 54. .

  A plurality of images at different time points may be taken using the camera unit 528, and the positioning of the subject 14 may be acquired by a known image processing technique. As the imaging element, a photodiode array, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), or the like can be used.

  Alternatively, the lighting of the irradiation field lamp used for the positioning operation of the subject 14 may be detected using the camera unit 528, and the scan mode may be started at the detection timing. Here, the irradiation field lamp is an auxiliary light source for positioning emitted from the radiation device 18 or the like. That is, the irradiation field lamp is a light source that visualizes a planar region (irradiation field) to be irradiated with the radiation 16.

  Therefore, if the pattern shape in the light image (projected image in plan view) of the irradiation field lamp is stored in advance, it is based on the image acquired from the camera unit 528 using a known image processing technique (template matching method or the like). Whether or not the irradiation field lamp is turned on can be detected. The pattern of the irradiation field lamp may be any of a rectangular shape, a slit shape, a cross shape, a frame shape, and the like.

  The arrangement and number of various sensors shown in Modification 7 may be variously changed. Further, the positioning of the subject 14 may be detected by variously combining various types of sensors (for example, a pressure sensor and an optical sensor). Thereby, the detection accuracy of positioning is further improved.

  Further, the notification means to the user is not limited to the display unit 522, and any configuration may be used as long as it is a means of appealing to the user's five senses (sight or hearing). For example, a lamp, a speaker, or the like may be used. Further, the electronic cassette 20 itself may be notified through an external device (the console 26 or the display device 28 in FIG. 1) without providing a notification means.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Radiation imaging system 16 ... Radiation 18 ... Radiation apparatus 20 ... Electronic cassette 24 ... System controller 26 ... Console 34 ... Radiation source 36 ... Radiation control apparatus 38 ... Radiation switch 52 ... Panel part 54 ... Control part 62 ... Scintillator 64 ... Radiation Conversion panel 66 ... Radiation detector 70 ... Substrate 72, 252 ... TFT
102, 254 ... Pixel 106 ... Drive circuit unit 110, 250 ... Gate line 112 ... Signal line 114 ... Gate drive unit 116 ... Charge amplifier 118 ... Multiplexer unit 120 ... AD conversion unit 122 ... Cassette control unit 124 ... Memory 126 ... Communication unit DESCRIPTION OF SYMBOLS 130 ... 1st read-out control part 132 ... Irradiation start determination part 134 ... Elapsed time determination part 136 ... 2nd read-out control part 150 ... Gate drive circuit 218 ... Table 222 ... Shooting condition setting part 224 ... Shooting number setting part 226 ... Image recording Control unit 260 ... Bypass line 262 ... Switching element 520 ... Pressure sensor 522 ... Display unit 526 ... Usage state identification unit 528 ... Camera unit

Claims (12)

An imaging panel having a plurality of pixels arranged in a matrix for converting and storing radiation from a radiation source that has passed through the subject into an electrical signal;
A positioning detector for detecting the positioning of the subject with respect to the imaging panel;
In response to the positioning detected by the positioning detector, a readout mode for reading out the electrical signal accumulated in the pixel is started, and the value of the electrical signal read out in the readout mode can be arbitrarily set And a reading control unit that shifts the imaging panel to an exposure state by terminating reading of the electrical signal when the threshold value exceeds a threshold value. The radiation imaging apparatus according to claim 1.
A use state identifying unit that identifies a use state of the imaging panel based on the positioning detected by the positioning detection unit;
The radiographic imaging apparatus, wherein the readout control unit starts the readout mode in accordance with the usage state identified by the usage state identification unit. The radiation imaging apparatus according to claim 2, wherein
The positioning detection unit includes a pressure sensor that detects a pressure change through the subject that occurs during the positioning,
The radiation state imaging device, wherein the use state identifying unit identifies the use state of the imaging panel according to the pressure change detected by the pressure sensor. The radiation imaging apparatus according to claim 2, wherein
The positioning detection unit includes a temperature sensor that detects a temperature change through the subject that occurs during the positioning,
The radiation imaging apparatus, wherein the use state identifying unit identifies the use state of the imaging panel according to the temperature change detected by the temperature sensor. The radiation imaging apparatus according to claim 2, wherein
The positioning detection unit includes a human body / object detection sensor,
The radiation imaging apparatus, wherein the use state identifying unit identifies the use state of the imaging panel according to whether or not the subject is detected by the human body / object detection sensor. The radiation imaging apparatus according to claim 2, wherein
The positioning detection unit is composed of an optical sensor,
The radiation imaging apparatus, wherein the usage state identification unit identifies the usage state of the imaging panel according to whether or not lighting of an irradiation field lamp is detected by the optical sensor. The radiation imaging apparatus according to any one of claims 1 to 6,
The radiographic imaging apparatus, wherein the readout control unit ends the readout mode when the positioning detection unit continuously detects that the subject is not present for a predetermined time. The radiation imaging apparatus according to any one of claims 1 to 7,
A radiation imaging apparatus, further comprising a start / end notification unit that notifies that the reading mode has started and / or ended. The radiation imaging apparatus according to any one of claims 1 to 8,
In the readout mode, the radiographic imaging apparatus is characterized in that the electrical signals accumulated in the plurality of pixels are simultaneously read out in units of a plurality of rows. The radiation imaging apparatus according to any one of claims 1 to 8,
In the readout mode, the radiation imaging apparatus is characterized in that charges accumulated in the pixels in a predetermined row are read out.   A radiation imaging system comprising: the radiation imaging apparatus according to claim 1; and a radiation source that emits radiation. A method of imaging a radiographic image using an imaging panel having a plurality of pixels arranged in a matrix for converting and storing radiation from a radiation source that has passed through a subject,
Detecting the positioning of the subject relative to the imaging panel;
In response to the detected positioning, starting a read mode for reading the electrical signal accumulated in the pixel;
When the value of the electrical signal read in the readout mode is greater than a threshold that can be arbitrarily set, the reading of the electrical signal is terminated to shift the imaging panel to an exposure state; and A radiation imaging method comprising:

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