JP5332619B2 - Portable radiographic imaging device and radiographic imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable radiological imaging apparatus and a radiological imaging system which prevent a battery from getting exhausted, and can sufficiently remove an excessive charge from radiation detecting elements. <P>SOLUTION: This portable radiological imaging apparatus 1 includes a plurality of radiation detecting elements 7 which are two-dimensionally arranged in each region r partitioned by a scanning line 5 and a signal line 6, a switch means 8 which is arranged for each radiation detecting element 7, a scanning-driving means 15 which controls ON/OFF of the switch means 8 by controlling a voltage applied to the switch means 8, and the battery 41. The scanning-driving means 15 applies the ON voltage Von1 of a specified voltage value to the switch means 8 through each scanning line 5 at the time of a resetting process of the radiation detecting elements 7 for discharging the excessive electric charge which has been accumulated in the radiation detecting elements 7 prior to the radiological imaging. Then, the scanning-driving means 15 makes the voltage value of the ON voltage fall, and keeps applying the ON voltage Von2 which has been lowered to the switch means 8 through each scanning line 5 until the irradiation of the X ray is started. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a portable radiographic image capturing apparatus and a radiographic image capturing system, and in particular, a portable type that performs a reset process of a radiation detection element that releases at least an excess charge accumulated in the radiation detection element before radiographic image capture. The present invention relates to a radiographic imaging apparatus and a radiographic imaging system using the same.

  A so-called direct type radiographic imaging device that generates electric charges by a detection element in accordance with the dose of irradiated radiation such as X-rays and converts it into an electrical signal, or other radiation such as visible light with a scintillator or the like. Various so-called indirect radiographic imaging devices have been developed that convert charges to electromagnetic waves after being converted into electrical signals by generating electric charges with photoelectric conversion elements such as photodiodes in accordance with the energy of the converted and irradiated electromagnetic waves. Yes. In the present invention, the detection element in the direct type radiographic imaging apparatus and the photoelectric conversion element in the indirect type radiographic imaging apparatus are collectively referred to as a radiation detection element.

  This type of radiographic imaging device is known as an FPD (Flat Panel Detector), and has conventionally been formed integrally with a support base (or a bucky device) (see, for example, Patent Document 1). However, in recent years, a portable radiographic image capturing apparatus in which a radiation detection element or the like is accommodated in a housing has been developed and put into practical use (see, for example, Patent Documents 2 and 3). In these portable radiographic imaging apparatuses, a battery is built in.

  By the way, the internal structure of the portable radiographic image capturing apparatus generally has a plurality of scanning lines 5 and a plurality of signals arranged on the substrate 4 so as to cross each other, as shown in FIGS. A plurality of radiation detection elements 7 are two-dimensionally (matrix-like) arranged in each small region r partitioned by the line 6. As described above, the radiation detection element 7 generates charges in accordance with the dose of the irradiated radiation, the charges of each radiation detection element 7 are read out, and are converted into charge voltages by the readout circuit 17. It is extracted as image data after being amplified.

  However, even when no radiation is applied to the portable radiographic imaging device, charges are generated inside due to thermal excitation or the like due to heat of the radiation detection element 7 itself, and the charge is a so-called dark charge. Accumulated within. Then, when radiographic imaging is performed in a state where a large amount of this dark charge exists in each radiation detection element 7, when the above-described charges generated by radiation irradiation are read out as image data from each radiation detection element 7, This large amount of dark charge is read out together and a large noise component is added to the image data.

  In order to remove the noise component due to this dark charge as much as possible, at the time of radiographic image capturing, dark charges accumulated in the radiation detecting element 7 or the like usually immediately before the radiation image capturing apparatus is irradiated with radiation, etc. A reset process is performed to remove the excess charge.

  In the reset process of the radiation detection element 7, as shown in FIG. 3, FIG. 4, etc., the gate electrode 8g of the TFT 8 (Thin Film Transistor) which is the switch means of each radiation detection element 7 connected to each scanning line 5 is applied. An on-voltage is applied via the scanning line 5 to open the gate of the TFT 8, and extra charge accumulated in the radiation detection element 7 is discharged to the signal line 6 via the TFT 8 to perform reset processing.

  Patent Document 4 describes several methods for applying an on-voltage to the TFT 8. For example, as shown in FIG. 18, at the same time as the irradiation of radiation to the apparatus is started, an on-voltage is applied to the TFT 8 to discharge excess charges from all the radiation detection elements 7 and reset processing is performed. An off voltage is applied to the electrode 8 g to close the gate of the TFT 8, and charges generated by radiation irradiation are accumulated in the radiation detection element 7.

  As another method, for example, as shown in FIG. 19, first, an on-voltage is applied to the TFT 8 to discharge excess charges from all the radiation detection elements 7 and reset processing is performed. A method has been proposed in which irradiation of radiation to the apparatus is started when an off voltage is applied to the TFT 8 and the gate of the TFT 8 is closed, and charges generated by radiation irradiation are accumulated in the radiation detection element 7.

  In any of these methods, since extra charges such as dark charges generated in each radiation detection element 7 are released and reset before radiation irradiation is started, the dark charges generated at the start of radiation irradiation are reset. Apart from noise components due to electric charges or the like, it is possible to obtain image data from which at least noise components generated before the start of radiation irradiation are removed.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP-A-9-131337

  However, according to the method shown in FIG. 18, for example, the charge generated by the radiation irradiated from time t1 to time t2 is released from the radiation detection element 7 by the reset process, and the radiation detection element 7 Since it is not accumulated, radiation is emitted in the meantime. In addition, there is a problem that the exposure dose of the patient as the subject increases.

  In order to avoid this, if the period during which the TFT 8 is turned on, that is, the time interval from the time t1 to the time t2, is shortened, the excess charge can be sufficiently removed from the radiation detection element 7 this time. The above effect of removing noise components generated at least before the start of radiation irradiation from the image data cannot be obtained. For this reason, this method is practically difficult to adopt.

  Therefore, it is conceivable to adopt the method shown in FIG. If this method is used, in an ideal device in which no abnormal element is present in the radiation detection element 7, as shown in FIG. 20, when an on-voltage is applied to the gate electrode 8g of the TFT 8 at time t4, The excess charge accumulated from the radiation detection element 7 is released, and the electrode 78 on the opposite side of the signal line 6 and the electrode 74 to which the TFT 8 of the radiation detection element 7 is connected (FIGS. 7 and 8, etc.) The current i flowing out to the bias line 9 connected to (see) increases.

  Then, if excessive charges accumulated in the radiation detection element 7 are released and a period during which the TFT 8 is turned on (a time interval from time t4 to time t5) is sufficient, the signal line 6 and the bias line The current amount i of the current flowing through 9 can be lowered to the level of the current amount id of the dark current caused by a slight dark charge that continues to be generated in the radiation detection element 7.

  However, it is inevitable that an abnormal radiation detection element 7 is produced in the manufacturing stage of the radiation detection element 7. In a normal radiation detection element 7, when a bias voltage is applied to the electrode 78 from the bias power supply 14 (see FIG. 7, FIG. 8, etc.) via the bias line 9, a capacitor formed by the electrode 78 and the electrode 74 is used. Thus, charges are accumulated in the electrodes 74 and 78, respectively, and the amount of dark current corresponding to the dark charge generated in the i-layer 76 between the electrodes 74 and 78 (see FIG. 5) is extremely small. A small amount of leakage current flows out from the electrodes 74 and 78.

  However, in the abnormal radiation detection element 7 as described above, when a bias voltage is applied to the electrode 78 from the bias power supply 14 to turn on the TFT 8, a short circuit occurs between the electrode 74 and the electrode 78 rather than a capacitor. Or an electric current equivalent to that between the electrode 74 and the electrode 78 connected by a conducting wire flows.

  Therefore, in such a radiation detection element 7, when an on-voltage is applied to the gate electrode 8g of the TFT 8 at time t4, as shown in FIG. 21, excess charges accumulated in the radiation detection element 7 are released, Although the current i flowing through the signal line 6 or the like increases, the current amount i does not decrease even when excess charge accumulated in the radiation detection element 7 is released, or at least lower than the level of the current amount id of the dark current. It only drops to a high level and a relatively large current continues to flow.

  Then, especially in a portable radiographic imaging apparatus with a built-in battery, the battery power is wasted and the battery is consumed. Further, if the period during which the TFT 8 is turned on (time interval from time t4 to time t5) is shortened in order to avoid the consumption of the battery, excess charges cannot be sufficiently removed from the radiation detection element 7. The above effect of removing noise components generated at least before the start of radiation irradiation from the image data cannot be obtained.

  Therefore, the portable radiographic image capturing apparatus and the radiographic image capturing system using the radiographic image capturing apparatus and the radiographic image capturing system do not consume the battery and turn on the TFT 8 even when the abnormal radiation detecting element 7 exists. It is desirable to be able to remove excess charges from the radiation detection element 7 for a sufficient period.

  The present invention has been made in view of the above-described problems, and is a portable radiographic imaging apparatus and radiographic imaging system capable of preventing battery consumption and sufficiently removing excess charges from a radiation detection element. The purpose is to provide.

In order to solve the above problem, the portable radiographic imaging device of the present invention is:
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
When an on-voltage is applied to the scanning line arranged and connected to each radiation detection element, a charge generated in the radiation detection element is released, and an off-voltage is applied to the connected scanning line. Switch means for accumulating charges generated in the radiation detection element in the radiation detection element;
Scanning drive means for controlling the voltage applied to the switch means via the scanning lines;
With
A battery for supplying power to each of the above means is incorporated,
The scan driving unit is configured to apply a predetermined value to the switch unit via each scanning line during a reset process of the radiation detection element that discharges excess charges accumulated in the radiation detection element before radiographic imaging. The on-voltage of the voltage value is applied, and then the voltage value of the on-voltage is lowered, and the switch means is lowered through the scanning lines until the radiation irradiation is started. Continue to apply the ON voltage ,
The voltage value of the lowered on-voltage is set to a voltage value at which the amount of on-current flowing through the switch means exceeds the amount of leakage current flowing through a normal radiation detection element. And

Moreover, the radiographic imaging system of the present invention is
A portable radiographic imaging device of the present invention comprising a communication means capable of communicating with the outside;
A radiation generator comprising: a radiation source that irradiates radiation to the portable radiation imaging apparatus; and an operation console that activates the radiation source and includes an irradiation start switch that instructs the radiation source to start radiation irradiation; ,
With
When the scanning drive unit of the portable radiographic image capturing apparatus receives the radiation source activation signal transmitted from the console via the communication unit, it starts resetting the radiation detection element. Features.

  According to the portable radiographic image capturing apparatus and the radiographic image capturing system of the system of the present invention, normal radiation is once applied to all switch means by applying a high on-voltage that is a normal on-voltage once. For both the detection element and the abnormal radiation detection element, it is possible to sufficiently discharge and remove excess charges accumulated in the radiation detection element. Further, by continuing to apply the on-voltage to the switch means until radiation irradiation is started, it is possible to sufficiently discharge and remove excess charges accumulated in the radiation detection element.

  Further, by reducing the high on-voltage applied to the switch means and continuing to apply the low on-voltage, the amount of current flowing out of the normal radiation detection element as well as the abnormal radiation detection element can be reduced, for example, It is possible to reduce the amount of leakage current including dark current flowing through the radiation detecting element to the same amount. Therefore, it is possible to suppress battery power consumption and prevent battery consumption.

  Further, by continuing to apply the ON voltage to the switch means until radiation irradiation starts, dark charges generated in each radiation detection element before radiation irradiation starts flowing out from each radiation detection element. Therefore, noise components generated at least before the start of radiation irradiation can be accurately removed from the finally obtained image data.

It is a perspective view which shows the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the AA line in FIG. It is a top view which shows the structure of the board | substrate which concerns on this embodiment. It is an enlarged view which shows the structure of the radiation detection element, TFT, etc. which were formed in the small area | region on the board | substrate of FIG. It is sectional drawing which follows the XX line in FIG. It is a side view explaining the board | substrate with which COF, a PCB board | substrate, etc. were attached. It is a figure showing the equivalent circuit schematic of the radiographic imaging apparatus which concerns on this embodiment. FIG. 8 is an equivalent circuit diagram for one pixel in FIG. 7. It is a graph showing the time transition of the voltage value of the voltage applied to a switch means in the radiographic imaging apparatus which concerns on this embodiment. (A) is a graph showing a state in which the voltage applied to the switch means is switched from the off voltage to the on voltage, and (B) the current amount of the current flowing through the bias line connection detected by the current detection means. It is a graph showing a change. (A) It is a graph showing a state in which a high on-voltage is continuously applied to the switch means, and (B) bias line connection detected by the current detection means when all radiation detection elements are assumed to be normal. It is a graph showing the time change of the electric current amount of the electric current which flows. FIG. 11A is a graph showing temporal changes in the amount of current flowing through the bias line connection detected by the current detection means when a voltage is continuously applied as shown in FIG. 11A in the presence of an abnormal radiation detection element. It is. FIG. 10 is a graph showing temporal changes in the amount of current flowing through the bias line connection detected by the current detection means when a voltage is applied as shown in FIG. 9 in the presence of an abnormal radiation detection element. It is a graph showing that the amount of current that flows out to the connection of the bias line increases due to the generation of electric charge in the radiation detection element when radiation irradiation is started. It is a timing chart of the voltage value applied to each line of a scanning line from a scanning drive means. It is a figure which shows the whole structure of the radiographic imaging system which concerns on this embodiment. (A) is a figure which shows the structure of an irradiation start switch, (B) is the state which the button part was half-pressed, (C) is a figure explaining the state by which it fully pressed. It is a timing chart which shows an example of how to apply ON voltage with respect to the switch means of a radiation detection element. It is a timing chart which shows another example of how to apply ON voltage with respect to the switch means of a radiation detection element. It is a graph showing the time change of the electric current amount of the electric current which flows out from a normal radiation detection element when an ON voltage is applied like FIG. It is a graph showing the time change of the electric current amount of the electric current which flows out from an abnormal radiation detection element when an ON voltage is applied like FIG.

  Embodiments of a portable radiographic imaging device and a radiographic imaging system according to the present invention will be described below with reference to the drawings.

  Hereinafter, the portable radiographic imaging device is simply referred to as a radiographic imaging device. In addition, the radiographic imaging apparatus includes a scintillator or the like, and describes a so-called indirect radiographic imaging apparatus that obtains an electrical signal by converting irradiated radiation into electromagnetic waves of other wavelengths such as visible light, and a system using the same. However, the present invention can also be applied to a direct radiographic imaging apparatus and a system using the same.

[Radiation imaging equipment]
FIG. 1 is an external perspective view of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG. As shown in FIGS. 1 and 2, the radiographic imaging apparatus 1 according to the present embodiment is configured as a portable (cassette type) apparatus in which a scintillator 3, a substrate 4, and the like are housed in a housing 2. .

  The housing 2 is formed of a material such as a carbon plate or plastic that transmits radiation at least on a surface R (hereinafter referred to as a radiation incident surface R) that receives radiation. 1 and 2 show a case in which the housing 2 is a so-called lunch box type formed by the frame plate 2A and the back plate 2B. However, the housing 2 is integrally formed in a rectangular tube shape. It is also possible to use a so-called monocoque type.

  As shown in FIG. 1, the side surface of the housing 2 is opened and closed for replacement of a power switch 36, an indicator 37 composed of LEDs and the like, and a battery 41 (not shown) (see FIG. 7 described later). A possible lid member 38 and the like are arranged. In the present embodiment, an antenna device 39 that is a communication unit for wirelessly communicating with the outside is embedded in the side surface of the lid member 38.

  As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a thin lead plate or the like (not shown) on the lower side of the substrate 4. The disposed PCB substrate 33, the buffer member 34, and the like are attached. In the present embodiment, a glass substrate 35 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed.

  The scintillator 3 is attached to a detection unit P, which will be described later, of the substrate 4. As the scintillator 3, for example, a scintillator 3 that has a phosphor as a main component and converts it into an electromagnetic wave having a wavelength of 300 to 800 nm, that is, an electromagnetic wave centered on visible light when it receives incident radiation, is used.

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 3, a plurality of scanning lines 5 and a plurality of signal lines are provided on a surface 4 a of the substrate 4 facing the scintillator 3. 6 are arranged so as to cross each other. In each small region r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 on the surface 4 a of the substrate 4, radiation detection elements 7 are respectively provided.

  Thus, the entire region r in which a plurality of radiation detection elements 7 arranged in a two-dimensional manner are provided in each small region r partitioned by the scanning line 5 and the signal line 6, that is, shown by a one-dot chain line in FIG. The region is a detection unit P.

  In the present embodiment, a photodiode is used as the radiation detection element 7, but other than this, for example, a phototransistor or the like can also be used. Each radiation detection element 7 is connected to the source electrode 8s of the TFT 8 serving as a switch means, as shown in the enlarged views of FIGS. The drain electrode 8 d of the TFT 8 is connected to the signal line 6.

  The TFT 8 is turned on when a turn-on voltage is applied to the connected scanning line 5 by the scanning drive means 15 described later and applied to the gate electrode 8g, and is generated and accumulated in the radiation detection element 7. The charged electric charge is discharged to the signal line 6. Further, the TFT 8 is turned off when the off voltage is applied to the connected scanning line 5 and the off voltage is applied to the gate electrode 8g, and the emission of the charge from the radiation detecting element 7 to the signal line 6 is stopped. The charges generated in the radiation detection element 7 are accumulated in the radiation detection element 7.

  Here, the structure of the radiation detection element 7 and the TFT 8 in this embodiment will be briefly described with reference to the cross-sectional view shown in FIG. FIG. 5 is a sectional view taken along line XX in FIG.

A gate electrode 8g of a TFT 8 made of Al, Cr or the like is formed on the surface 4a of the substrate 4 so as to be integrally laminated with the scanning line 5, and silicon nitride (laminated on the gate electrode 8g and the surface 4a). The first electrode 74 of the radiation detecting element 7 is connected to the upper portion of the gate electrode 8g on the gate insulating layer 81 made of SiN _x ) or the like via the semiconductor layer 82 made of hydrogenated amorphous silicon (a-Si) or the like. The formed source electrode 8s and the drain electrode 8d formed integrally with the signal line 6 are laminated.

The source electrode 8s and the drain electrode 8d are divided by a first passivation layer 83 made of silicon nitride (SiN _x ) or the like, and the first passivation layer 83 covers both electrodes 8s and 8d from above. In addition, ohmic contact layers 84a and 84b formed in an n-type by doping hydrogenated amorphous silicon with a group VI element are stacked between the semiconductor layer 82 and the source electrode 8s and the drain electrode 8d, respectively. The TFT 8 is formed as described above.

  In the radiation detecting element 7, an auxiliary electrode 72 is formed by laminating Al, Cr, or the like on the insulating layer 71 formed integrally with the gate insulating layer 81 on the surface 4 a of the substrate 4. A first electrode 74 made of Al, Cr, Mo or the like is laminated on the auxiliary electrode 72 with an insulating layer 73 formed integrally with the first passivation layer 83 interposed therebetween. The first electrode 74 is connected to the source electrode 8 s of the TFT 8 through the hole H formed in the first passivation layer 83.

  On the first electrode 74, an n layer 75 formed in an n-type by doping a hydrogenated amorphous silicon with a group VI element, an i layer 76 which is a conversion layer formed of hydrogenated amorphous silicon, and a hydrogenated amorphous A p layer 77 formed by doping a group III element into silicon and forming a p-type layer is formed by laminating sequentially from below.

  When radiation enters from the radiation incident surface R of the housing 2 of the radiographic imaging apparatus 1 and is converted into an electromagnetic wave such as visible light by the scintillator 3, and the converted electromagnetic wave is irradiated from above in the figure, the electromagnetic wave is detected by radiation. The electron hole pair is generated in the i layer 76 by reaching the i layer 76 of the element 7. In this way, the radiation detection element 7 converts the electromagnetic waves irradiated from the scintillator 3 into electric charges.

  On the p layer 77, a second electrode 78 made of a transparent electrode such as ITO is laminated and formed so that the irradiated electromagnetic wave reaches the i layer 76 and the like. In the present embodiment, the radiation detection element 7 is formed as described above. The order of stacking the p layer 77, the i layer 76, and the n layer 75 may be reversed. Further, in the present embodiment, a case where a so-called pin-type radiation detection element formed by sequentially stacking the p layer 77, the i layer 76, and the n layer 75 as described above is used as the radiation detection element 7. However, it is not limited to this.

A bias line 9 for applying a bias voltage to the radiation detection element 7 is connected to the upper surface of the second electrode 78 of the radiation detection element 7 via the second electrode 78. The second electrode 78 and the bias line 9 of the radiation detection element 7, the first electrode 74 extended to the TFT 8 side, the first passivation layer 83 of the TFT 8, that is, the upper surfaces of the radiation detection element 7 and the TFT 8 are A second passivation layer 79 made of silicon nitride (SiN _x ) or the like is covered from above.

  As shown in FIGS. 3 and 4, in this embodiment, one bias line 9 is connected to a plurality of radiation detection elements 7 arranged in rows, and each bias line 9 is connected to a signal line 6. Are arranged in parallel with each other. In addition, each bias line 9 is bound to one connection 10 at a position outside the detection portion P of the substrate 4.

  In this embodiment, as shown in FIG. 3, each scanning line 5, each signal line 6, and connection 10 of the bias line 9 are input / output terminals (also referred to as pads) provided near the edge of the substrate 4. 11 is connected. As shown in FIG. 6, a COF (Chip On Film) 12 in which a chip such as an IC 12 a is incorporated in each input / output terminal 11 is an anisotropic conductive adhesive film (Anisotropic Conductive Film) or anisotropic conductive paste (Anisotropic paste). It is connected via an anisotropic conductive adhesive material 13 such as Conductive Paste).

  The COF 12 is routed to the back surface 4b side of the substrate 4 and connected to the PCB substrate 33 described above on the back surface 4b side. Thus, the board | substrate 4 part of the radiographic imaging apparatus 1 is formed. In FIG. 6, illustration of the electronic component 32 and the like is omitted.

  Here, the circuit configuration of the radiation image capturing apparatus 1 will be described. FIG. 7 is an equivalent circuit diagram of the radiation image capturing apparatus 1 according to the present embodiment, and FIG. 8 is an equivalent circuit diagram of one pixel constituting the detection unit P.

  As described above, each radiation detection element 7 of the detection unit P of the substrate 4 has the bias line 9 connected to the second electrode 78, and each bias line 9 is bound to the connection 10 to the bias power supply 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 78 of each radiation detection element 7 via the connection 10 and each bias line 9.

  The bias power source 14 is connected to a control unit 22 described later, and the control unit 22 controls a bias voltage applied to each radiation detection element 7 from the bias power source 14. In the present embodiment, the current detection means 43 for detecting the amount of current flowing through the connection 10 (bias line 9) is provided in the connection 10 of the bias line 9, which will be described later.

  In the present embodiment, as can be seen from the fact that the bias line 9 is connected to the p-layer 77 side (see FIG. 5) of the radiation detection element 7 via the second electrode 78, A voltage equal to or lower than the voltage applied to the first electrode 74 side of the radiation detection element 7 is applied to the second electrode 78 of the radiation detection element 7 as a bias voltage via the bias line 9.

  The first electrode 74 of each radiation detection element 7 is connected to the source electrode 8s of the TFT 8 (indicated as S in FIGS. 7 and 8), and the gate electrode 8g of each TFT 8 (FIGS. 7 and 8). Are respectively connected to the lines L1 to Lx of each scanning line 5 extending from a gate driver 15b of the scanning driving means 15 described later. Further, the drain electrode 8 d (denoted as D in FIGS. 7 and 8) of each TFT 8 is connected to each signal line 6.

  In this embodiment, the scanning drive unit 15 includes a power supply circuit 15a and a gate driver 15b, and controls a voltage applied to the gate electrode 8g of the TFT 8 via each scanning line 5 connected to the gate driver 15b. It is supposed to be.

  Specifically, the power supply circuit 15a of the scanning drive unit 15 sets the voltage values of the on voltage and the off voltage applied to each scanning line 5 from the gate driver 15b to predetermined voltage values, and supplies them to the gate driver 15b. It is supposed to be. Further, the gate driver 15b of the scanning driving means 15 can modulate the pulse width and duty ratio of the pulse wave of the on-voltage applied to each scanning line 5 by pulse width modulation (PWM).

  A method for applying the ON voltage to the TFT 8 via the scanning lines 5 from the scanning driving means 15 will be described in detail later.

  Each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16. Note that a predetermined number of readout circuits 17 are provided in the readout IC 16, and by providing a plurality of readout ICs 16, readout circuits 17 corresponding to the number of signal lines 6 are provided.

  The readout circuit 17 includes an amplifier circuit 18, a correlated double sampling circuit 19, an analog multiplexer 21, and an A / D converter 20. 7 and 8, the correlated double sampling circuit 19 is represented as CDS. In FIG. 8, the analog multiplexer 21 is omitted.

In the present embodiment, the amplifier circuit 18 is configured by a charge amplifier circuit, and is configured by connecting a capacitor 18b and a charge reset switch 18c in parallel to the operational amplifier 18a and the operational amplifier 18a. The signal line 6 is connected to the inverting input terminal on the input side of the operational amplifier 18 a of the amplifier circuit 18, and the initial voltage V ₀ is applied to the non-inverting input terminal on the input side of the amplifier circuit 18. ing. The initial voltage V ₀ is set to a suitable value.

  The charge reset switch 18c of the amplifier circuit 18 is connected to the control means 22 described later, and is controlled to be turned on / off by the control means 22. When the charge reset switch 18c is off and the TFT 8 of the radiation detection element 7 is turned on (that is, when an on-voltage is applied to the gate electrode 8g of the TFT 8 via the scanning line 5), the radiation The electric charge discharged from the detection element 7 flows into the capacitor 18b and is accumulated, and a voltage value corresponding to the accumulated electric charge is output from the output side of the operational amplifier 18a.

  In this way, the amplifier circuit 18 outputs a voltage value in accordance with the amount of charge output from each radiation detection element 7 to perform charge voltage conversion and amplify. When the charge reset switch 18c is turned on, the input side and the output side of the amplifier circuit 18 are short-circuited, and the charge accumulated in the capacitor 18b is discharged to reset the amplifier circuit 18. ing. Note that the amplifier circuit 18 may be configured to output a current in accordance with the charge output from the radiation detection element 7.

  A correlated double sampling circuit (CDS) 19 is connected to the output side of the amplifier circuit 18. In this embodiment, the correlated double sampling circuit 19 has a sample and hold function. The sample and hold function in the correlated double sampling circuit 19 is turned on / off by a pulse signal transmitted from the control means 22. To be controlled.

  That is, in the correlated double sampling circuit 19, after the amplifier circuit 18 is reset, the charge reset switch 18c is turned off, and the charge discharged from the radiation detection element 7 starts to flow into the capacitor 18b and accumulate. When the first pulse signal is received from the control means 22 at that time, the voltage value output from the amplifier circuit 18 at that time is held.

  Then, after a lapse of a predetermined time from that point, when the second pulse signal is received from the control means 22 when the electric charge released from the radiation detecting element 7 flows into the capacitor 18b and is accumulated, it is amplified again at that point. The voltage value output from the circuit 18 is held, and the difference value between these voltage values is output downstream as image data.

  The image data of each radiation detection element 7 output from the correlated double sampling circuit 19 is transmitted to the analog multiplexer 21 and sequentially transmitted from the analog multiplexer 21 to the A / D converter 20. Then, the A / D converter 20 sequentially converts the image data into digital values, which are output to the storage means 40 and sequentially stored.

  The control means 22 is constituted by a computer in which a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface and the like (not shown) are connected to a bus. It may be configured by a dedicated control circuit. And the control means 22 controls operation | movement etc. of each member of the radiographic imaging apparatus 1. The control means 22 is connected to a storage means 40 composed of a DRAM (Dynamic RAM) or the like.

  The control unit 22 is connected to the antenna device 39 described above, and further supplies power to each member such as the detection unit P, the scanning drive unit 15, the readout circuit 17, the storage unit 40, and the bias power source 14. A battery 41 is connected. As described above, the battery 41 is built in the housing 2 of the radiographic imaging apparatus 1, and the battery 41 has a connection terminal 42 for supplying power from the external device to the battery 41 to charge the battery 41. It is attached.

  As described above, the control means 22 controls the bias power supply 14 to set a bias voltage to be applied to each radiation detection element 7 from the bias power supply 14, or the charge reset switch 18 c of the amplification circuit 18 of the readout circuit 17. Various processes such as on / off control and transmission of a pulse signal to the correlated double sampling circuit 19 to control on / off of the sample hold function are executed.

  In addition, the control means 22 is configured such that a signal is input manually by an operator such as a radiologist operating the power switch 36 or wirelessly through an antenna device 39 from an external device. The power supply state to the member is set to a power saving mode (sleep mode) in which the supply of power to the radiation detecting element 7 or the like is stopped and power is supplied only to the necessary member, and the power is supplied to the radiation detecting element 7 or the like. Thus, it is configured to be able to switch between a radiographable mode (wake up mode) that enables radiographic imaging.

  In the power saving mode, since power is not supplied to the radiation detection element 7 and the like, power consumption of the battery 41 can be suppressed, but radiographic imaging cannot be performed. In the photographing enabled mode, power is supplied to each member such as the radiation detection element 7 and radiation detection is possible, but the power of the battery 41 is consumed. For this reason, the control unit 22 switches the power supply state to each member to the photographing enabled mode, and if the radiation image capturing apparatus 1 is not irradiated with radiation even after a predetermined time has elapsed, the power supply state to each member. Switch to the power saving mode.

  The current detection means 43 detects a current flowing in the connection 10 in which the bias lines 9 are bundled. In the present embodiment, the current detection unit 43 includes a resistor having a predetermined resistance value connected in series to the connection 10 and a differential amplifier that measures a voltage between both terminals of the resistor, although not illustrated. By measuring the voltage between both terminals of the resistor with a differential amplifier, the current flowing through the connection 10 is converted into a voltage value and detected.

  As the resistor provided in the current detecting means 43, a resistor having a relatively large resistance value is used in order to amplify a weak current flowing through each bias line 9 and connection 10 and convert it to a voltage value. The current detection means 43 outputs a voltage value corresponding to the detected current amount of the connection 10 to the control means 22.

  Note that, for example, when reading the electric charge accumulated in the radiation detection element 7 by radiation irradiation at the time of radiographic imaging, a current also flows through the bias line 9 and the connection 10, but the resistance value of the resistance of the current detection unit 43 is If it is relatively large, the current flowing through the bias line 9 and the connection line 10 will be hindered.

  For this reason, the current detecting means 43 is provided with a switch (not shown) for short-circuiting both terminals of the resistor, and the control means 22 is normally turned on to short-circuit between both terminals of the resistor. When the voltage value information corresponding to the amount of current flowing through the bias line 9 or the connection 10 is necessary, the switch is turned off, and the voltage corresponding to the current amount of the connection 10 detected from the current detection means 43 The value is output to the control means 22 and the scanning drive means 15.

  Next, the operation of the radiographic image capturing apparatus 1 according to the present embodiment will be described, and the application of the on-voltage to the TFTs 8 via the scanning lines 5 from the scanning drive unit 15 in the radiographic image capturing apparatus 1 according to the present embodiment will be described. How to let it be explained.

  The control means 22 (see FIG. 7) of the radiographic image capturing apparatus 1 receives radiation signals when an awakening signal is input manually by an operator to perform radiographic image capturing or wirelessly from an external device via the antenna device 39. The power supply state for each member of the image capturing apparatus 1 is switched from the power saving mode to the image capturing possible mode.

  The power supply circuit 15a of the scanning drive means 15 is used to close the off voltage Voff applied to the gate electrode 8g of the TFT 8 serving as the switch means of each radiation detection element 7 via the scanning line 5, that is, the TFT 8 of each radiation detection element 7. For example, as shown in FIG. 9, a voltage value of −10 [V] is applied as the OFF voltage Voff.

  The control unit 22 transmits a signal to the scanning drive unit 15 when the power supply state to each member is switched from the power saving mode to the photographing enable mode. The power supply circuit 15a of the scanning drive unit 15 receives a signal from the control unit 22. , The off voltage Voff is set for the gate driver 15b. Then, the gate driver 15b of the scanning drive unit 15 applies the off voltage Voff to all the TFTs 8 via all the lines L1 to Lx of the scanning line 5 (time T0).

  Further, when the power supply state for each member is switched from the power saving mode to the photographing enable mode, the control means 22 transmits a signal to the bias power source 14 and from the bias power source 14 via each bias line 9 and connection 10. A bias voltage having a predetermined voltage value is applied to each radiation detection element 7.

  When the supply state of power to each member is switched to the photographing enabled mode and power is supplied to each member to enter a standby state, the scanning drive unit 15 passes through all the lines L1 to Lx of the scanning line 5 from the gate driver 15b. Thus, the normal ON voltage, for example, +15 [V] ON voltage Von1 is applied to all TFTs 8 (time T1).

  When the on voltage Von1 is applied to the gate electrode 8g, the TFT 8 is turned on, and excess charges (electrons in this embodiment) accumulated in the vicinity of the first electrode 74 from each radiation detection element 7 flow out to the signal line 6 respectively. To do. On the other hand, in the vicinity of the second electrode 78, which is the opposite electrode of each radiation detection element 7, a charge (in this embodiment, positive and negative) opposite to the excess charge accumulated in the vicinity of the first electrode 74 is accumulated. However, as charges (electrons) flow out to the signal line 6, the charges (holes) flow out to the bias lines 9 and flow into the bias power source 14 through the connection 10.

  When the current flowing into the bias power source 14 is monitored by the current detection means 43, as shown in FIG. 10A, when the voltage V applied to the gate electrode 8g of the TFT 8 is switched from the off voltage Voff to the on voltage Von, FIG. As shown in B), the electric charge flowing out from the second electrode 78 of each radiation detecting element 7 is collected in the connection 10 via the respective bias lines 9, and the current I flowing into the bias power source 14 rises greatly.

  Then, as shown in FIG. 20, each radiation detection element 7 is normal, and the current amount i of the current flowing out from each radiation detection element 7 falls to the level of the current amount id of the dark current caused by the dark charge. Then, as shown in FIG. 11A, if a normal on-voltage Von1 is continuously applied to the TFT 8, as shown in FIG. 11B, the current I flowing into the bias power source 14 increases as shown in FIG. Then, after reaching the peak once, it gradually decreases and decreases to a current amount Id corresponding to the sum of the current amounts id of the dark currents flowing out from the radiation detection elements 7.

  As described above, if all the radiation detection elements 7 are normal, even if the on-voltage Von1 applied to the TFT 8 remains at a high value, for example, +15 [V], the excess is accumulated in each radiation detection element 7. After a large amount of charge flows out to the signal line 6 and the bias line 9, the amount of current flowing through the bias line 9 can be reduced to a current amount Id corresponding to the sum of the dark current amounts id. Thus, it is possible to sufficiently remove excess charges from the battery 7, and to suppress power consumption of the battery 41.

  However, as described above, in the radiation detection element 7, as shown in FIG. 21, when the TFT 8 is turned on, it is equivalent to that the electrode 74 and the electrode 78 are connected by a conductive wire. There is an abnormal radiation detection element 7 through which current flows.

  Depending on how many abnormal radiation detection elements 7 are present, if there is such an abnormal radiation detection element 7, a normal TFT 8 is provided in the TFT 8 as shown in FIG. If the on-voltage Von1 is continuously applied, as shown in FIG. 12, the current I flowing into the bias power source 14 is higher than the current amount Id corresponding to the sum of the current amounts id of the dark currents flowing out from the radiation detection elements 7. However, it decreases only to a relatively large current amount Ireal.

  In this case, even if excess charges accumulated in each radiation detection element 7 sufficiently flow out to the signal line 6 and the bias line 9, the amount of current flowing through the signal line 6, the bias line 9, and the connection line 10 is the dark current. Since the current of a relatively large value continues to flow without decreasing to the current amount Id corresponding to the sum of the current amounts id, the power consumption of the battery 41 cannot be suppressed and the battery 41 is consumed.

  Therefore, in the radiographic imaging apparatus 1 according to the present embodiment, when performing the reset process of the radiation detection element 7, the scanning drive unit 15 includes the scanning line 5 connected to the gate driver 15b as shown in FIG. The off voltage Voff is applied at time T0 to all the TFTs 8 that are the switching means of each radiation detection element 7 through all the lines L1 to Lx.

  Then, after applying the on-voltage Von1 that is a normal on-voltage at time T1, the voltage value of the on-voltage is lowered to the voltage value Von2 at time T2, and each scanning line 5 is changed until radiation irradiation is started. Thus, the reduced ON voltage Von2 is continuously applied to each TFT8.

  At this time, in this embodiment, the voltage value Von2 of the reduced on-voltage is the maximum on-current that can flow through the TFT 8 when the on-voltage Von2 is applied to the gate electrode 8g of the TFT 8 and the TFT 8 is turned on. The amount imax (Von2) is set to a voltage value that slightly exceeds the current amount ileak of the leak current including the dark current flowing through the normal radiation detection element 7.

  That is, when an on-voltage having a voltage value of Von is applied to the gate electrode 8g of the TFT8 to turn on the TFT8, the maximum amount of on-current imax (Von) that can flow through the TFT8 is applied to the gate electrode 8g of the TFT8. It changes depending on the voltage value Von of the applied ON voltage, and the maximum current amount imax (Von) of the ON current that can flow through the TFT 8 decreases as the voltage value Von of the ON voltage decreases. When the voltage value Von of the on-voltage decreases to the threshold value Vth, the amount of current that can flow through the TFT 8 rapidly decreases.

  The amount of current that can flow through the TFT 8 that has decreased sharply is about 4 to 5 orders of magnitude smaller than the amount of on-state current that can flow even when the TFT 8 is an ordinary silicon-based transistor device. In the case of an amorphous silicon TFT, it is about 7 orders of magnitude smaller. Then, the amount of current that can flow through the TFT 8 that has decreased sharply is a value that is much lower than the amount of leakage current ileak that includes the dark current that flows through the normal radiation detection element 7.

  For this reason, when a voltage value of the threshold value Vth at which the amount of current that can flow through the TFT 8 sharply decreases is applied to the gate electrode 8g of the TFT 8, the dark current effectively does not flow from the radiation detection element 7 through the TFT 8, It accumulates in the detection element 7. However, in this case, excess charges such as dark charges generated in each radiation detection element 7 are released before the start of radiation irradiation, and at least noise components generated until the start of radiation irradiation are detected from the image data. The purpose of removal cannot be achieved.

  Further, even if the ON voltage applied to the gate electrode 8g of the TFT 8 is increased above the threshold value Vth and the maximum ON current imax (Von) that can flow through the TFT 8 is increased, the maximum ON current that can flow through the TFT 8 is increased. If imax (Von) is smaller than the current amount ileak of the leak current including the dark current flowing through the normal radiation detection element 7, the charge that could not flow out of the radiation detection element 7 is accumulated in the radiation detection element 7. Will come to be.

  Therefore, in the present embodiment, the maximum current amount imax (Von2) of the on-current that can flow through the TFT 8 is the same as the leakage current amount ileak including the dark current that flows through the normal radiation detection element 7 or has some margin. The voltage value Von2 of the lowered on-voltage is set so that the amount is slightly larger than that.

  When the radiation detection element 7 is reset, the scanning drive unit 15 detects each radiation through all the lines L1 to Lx of the scanning line 5 connected to the gate driver 15b as shown in FIG. A normal off voltage Voff is applied at time T0 to all TFTs 8 serving as switching means of the element 7, and an on voltage Von1 that is a normal on voltage is applied at time T1. The value is decreased to the voltage value Von2, and the on-voltage Von2 is continuously applied until radiation irradiation is started at time T3.

  When the on-voltage Von is changed in this way, both the normal radiation detection element 7 and the abnormal radiation detection element 7 accumulate in the on-voltage Von1 which is a normal on-voltage at time T1. The excess electric charges are released to the signal line 6 and the bias line 9 all at once.

  After the time T2, when the voltage value of the on-voltage is lowered to the voltage value Von2, as described above, the current amount ileak of the leak current including the dark current flowing through the normal radiation detecting element 7 becomes the on-voltage. The on-current maximum current amount imax (Von2) that can flow through the TFT 8 at Von2 is smaller. Therefore, a current amount ileak of a leakage current including a dark current flows out from each normal radiation detection element 7 under this on-voltage Von2.

  In this way, under this on-voltage Von2, since all the leakage current amount ileak including dark current flows out from each normal radiation detecting element 7 through the TFT 8, each normal after the time T2 All dark charges and the like generated in the radiation detection element 7 also flow out, and no new charge is accumulated in each normal radiation detection element 7.

  On the other hand, in the abnormal radiation detection element 7, an on-current having a maximum current amount imax (Von2) as long as it can flow through the TFT 8 including a generated dark current flows. However, as described above, in this case, the maximum current amount imax (Von2) of the on-current that can flow through the TFT 8 is the same amount as the current amount ileak of the leakage current including the dark current that flows in the normal radiation detection element 7, or It is set to be a little higher than that.

  For this reason, each of the abnormal radiation detection elements 7 has a maximum amount that is the same as or slightly larger than the current amount ileak of the leakage current including the dark current flowing through the normal radiation detection element 7 under the ON voltage Von2. An on-current with a current amount imax (Von2) flows out.

  Note that under the ON voltage Von2, a current amount equal to or greater than the current amount ileak flows out from each abnormal radiation detection element 7 through the TFT 8, and therefore in each abnormal radiation detection element 7 after time T2. All the generated dark charges and the like also flow out, and no new charges are accumulated in each abnormal radiation detection element 7.

  When the radiation detection element 7 is reset, as described above, the normal radiation detection element 7 is also abnormal by applying the on voltage Von1 that is a normal on voltage to all the TFTs 8 once. The radiation detection element 7 can sufficiently discharge the accumulated charge, and then the on-voltage value is reduced to the above-mentioned voltage value Von2 to apply the on-voltage Von2. Continue until irradiation begins.

  By configuring in this way, not only the normal radiation detection element 7 but also the abnormal radiation detection element 7, the amount of current flowing out from the normal radiation detection element 7 is a current of a leak current including a dark current flowing through the normal radiation detection element 7. It is possible to reduce the amount to the same amount as or close to the amount ileak.

Therefore, even when an abnormal radiation detection element 7 is present in the radiation detection element 7, the ON voltage Von applied to the TFT 8 from the scanning drive means 15 via each scanning line 5 is changed as shown in FIG. Thus, as shown in FIG. 13, the current I flowing into the bias power source 14 is a current corresponding to the sum of the dark current amounts id when all the radiation detection elements 7 are composed of normal radiation detection elements 7. It is possible to reduce the current amount to Id ^* (see FIG. 13) close to the amount Id (see FIG. 11B).

  For this reason, the power consumption of the battery 41 can be suppressed. Then, excess charges can be sufficiently removed from each radiation detection element 7, and the application of the on-voltage Von2 is continued until radiation irradiation is started. In addition, no charge is newly accumulated in each abnormal radiation detection element 7. Therefore, it is possible to remove noise components generated at least before the start of radiation irradiation from the finally obtained image data.

  It should be noted that the voltage applied to the gate electrode 8g of the TFT 8 is turned on from the off voltage Voff at the time T2 when the scan driving means 15 lowers the on voltage Von applied to the gate electrode 8g of the TFT 8 from the on voltage Von1 to the on voltage Von2. It is possible to count the elapsed time from time T1 when switching to the voltage Von1 and set it as the time when a predetermined time has elapsed.

  Further, in order to apply the on-voltage Von1 to the gate electrode 8g of the TFT 8 and to ensure that excess charges accumulated in each radiation detection element 7 flow out to the signal line 6 and the bias line 9, for example, current detection means 43 The current amount I of the current flowing through the connection 10 of the bias line 9 detected in step S1 is transmitted to the scanning drive means 15, and the time when the time change rate of the current amount I becomes equal to or less than a predetermined threshold value by the scan drive means 15 It is also possible to configure so that the ON voltage applied to each TFT 8 as T2 is reduced to Von2.

  For example, if the predetermined threshold value is set to 0, the on-voltage Von1 is applied to the gate electrode 8g of the TFT 8 and excess charge flows out from each radiation detection element 7, and the amount of current flowing through the connection 10 of the bias line 9 When I increases and reaches a peak, and the excess charge is sufficiently discharged to the signal line 6 and the bias line 9, the on-voltage Von is lowered to the on-voltage Von 2. Excess charge can be reliably discharged to the signal line 6 and the bias line 9.

  Note that the predetermined threshold value can be set to another value, and is set to an appropriate value. Also, instead of transmitting the current amount I of the current flowing through the connection 10 of the bias line 9 detected by the current detecting unit 43 to the scanning drive unit 15, the current amount I is transmitted to the control unit 22. It is determined whether or not the time change rate of the current amount I has become a predetermined threshold value or less, and a signal is transmitted to the scanning drive means 15 when it is determined that the time change rate of the current amount I has become the predetermined threshold value or less (time T2). It is also possible to reduce the ON voltage applied to each TFT 8 to Von2.

  On the other hand, in the present embodiment, as shown in FIG. 9, the scanning drive unit 15 reduces the ON voltage applied to the gate electrode 8g of each TFT 8 via each scanning line 5 to the voltage value Von2 at time T2. Thereafter, when radiation irradiation is started at time T3, the voltages applied to the gate electrodes 8g of the TFTs 8 are simultaneously switched to the off voltage Voff.

  In this case, for example, a radiation sensor (not shown) for detecting radiation irradiation is attached to the radiation imaging apparatus 1, and radiation irradiation to the radiation imaging apparatus 1 is started based on a detection signal transmitted from the radiation sensor. It can also be configured to detect this.

  However, in the present embodiment, by monitoring the current amount I of the current flowing through the connection 10 of the bias line 9 detected by the current detection means 43, it is detected that the radiation imaging apparatus 1 has started irradiation with radiation. It is supposed to be.

  Specifically, in the present embodiment, the radiation imaging apparatus 1 is irradiated with radiation while the reduced on-voltage Von2 is applied to the gate electrode 8g of each TFT 8. When the radiation image capturing apparatus 1 is irradiated with radiation, the irradiated radiation is converted into an electromagnetic wave of another wavelength such as visible light by the scintillator 3, and the electromagnetic wave enters the radiation detection element 7 directly below. The incident electromagnetic wave reaches the i layer 76 (see FIG. 5) of the radiation detection element 7, and electron-hole pairs are generated in the i layer 76.

  A predetermined potential gradient is formed in the radiation detection element 7 by a bias voltage applied from the bias power supply 14 via the bias line 9 and the like, and among the electron-hole pairs generated in the radiation detection element 7, One charge (electrons in this embodiment) moves to the first electrode 74 side. In addition, the other charge (hole in this embodiment) having the same amount as the one charge moves to the second electrode 78 side of the radiation detection element 7.

  In this case, since the ON voltage Von2 is applied to the gate electrode 8g of the TFT 8 and the TFT 8 is in the ON state, the electrons that have moved to the first electrode 74 side of the radiation detection element 7 flow out of the first electrode 74. Then, the holes flowing out to the signal line 6 through the TFT 8 and moving to the second electrode 78 side of the radiation detecting element 7 flow out from the second electrode 78 to the bias line 9 and flow in the connection 10, and the current detecting means 43. Is detected. Therefore, as shown in FIG. 14, when radiation irradiation to the radiation imaging apparatus 1 is started, the current amount I of the current flowing through the connection 10 of the bias line 9 increases.

  Therefore, in this embodiment, the scanning drive unit 15 reduces the voltage value of the on-voltage to the voltage value Von2 at time T2, and the amount of current flowing through the connection 10 of the bias line 9 detected by the current detection unit 43. After I decreases, the time when the amount of current I increases again is detected as time T3 when radiation irradiation is started, and the voltage applied to the gate electrode 8g of each TFT 8 is simultaneously switched to the off voltage Voff at that time T3. It is like that.

  Since the off voltage Voff is applied to the gate electrode 8 g of each TFT 8, each TFT 8 is turned off, and the charge hardly flows out from each radiation detection element 7. Therefore, as shown in FIG. 14, immediately after the start of radiation irradiation, the charge generated in each radiation detection element 7 by radiation irradiation flows out to the bias line 9, and the amount of current flowing through the connection 10. Although I increases, since the TFT 8 is turned off, there is almost no outflow of charge from each radiation detection element 7 to the bias line 9 or the connection 10.

  In addition, after each TFT 8 is turned off, the electron-hole pair generated in the radiation detection element 7 by radiation irradiation moves to the first electrode 74 side due to the potential gradient, and the hole is transferred to the second electrode. Although it moves to the 78 side and is separated, it cannot flow out of the radiation detection element 7 and is accumulated in the radiation detection element 7. In each radiation detection element 7, the energy of the radiation that has passed through the subject and applied to the radiation detection element 7 (in this embodiment, the radiation of the electromagnetic waves converted by the scintillator 3 is applied to the scintillator 3. The charge is proportional to the energy.

  When the radiation irradiation is completed, as shown in FIG. 15, the scanning driving unit 15 sequentially switches the lines L1 to Lx of the scanning line 5 to which the signal driver ON voltage Von1 is applied from the gate driver 15b. (Ie, scanning), the electric charge accumulated from each radiation detection element 7 is read out.

  At that time, when the on-voltage Von1 is applied to the gate electrode 8g of the TFT 8 connected to each of the lines L1 to Lx of the scanning line 5, the electrons accumulated in the first electrode 74 of the radiation detection element 7 pass through the TFT 8. The signal is emitted to the signal line 6, converted into image data by charge-voltage conversion and amplification by the readout circuit 17 (see FIG. 7 etc.), and sequentially converted into digital value image data by the A / D converter 20. And stored in the storage means 40.

  On the other hand, in accordance with the outflow of electrons from the first electrode 74 of the radiation detection element 7, the accumulated holes flow out from the second electrode 78 of the radiation detection element 7 to the bias line 9 and flow through the connection 10. It flows into the bias power source 14. Note that when reading out the charges from the radiation detection element 7, it is not necessary to detect the current amount I of the current flowing through the bias line 9 and the connection 10, so the control means 22 switches the switch of the current detection means 43. The both terminals of the resistor of the current detection means 43 are short-circuited in the on state.

  Thereafter, dark reading processing or the like is performed as necessary. That is, as described above, in the radiographic imaging device 1 of the present embodiment, irradiation of radiation is started, and the on-voltage Von2 applied to the gate electrode 8g of each TFT 8 is switched to the off-voltage Voff (time T3). The dark charge generated in each radiation detection element 7 flows out because the TFT 8 is in an ON state, and at least noise components generated before the start of radiation irradiation are removed from the image data.

However, after the voltage is switched to the off voltage Voff at time T3 and each TFT 8 is turned off, the dark charges generated in each radiation detection element 7 are accumulated in each radiation detection element 7. The dark charges accumulated in each radiation detection element 7 are read out from the radiation detection elements 7 for each line L1 to Lx of the scanning line 5 (time T4 _{1 to} T4 _x ). Are read out together with the image data.

Therefore, the image data for each radiation detection element 7, dark charge accumulated in each radiation detection element 7 from the time T3 to the period ΔT ₁ ~ΔT _x to the read start time T4 ₁ to T4 _x of each line The offset corresponding to each is included. By subtracting this offset from the image data, image data corresponding to the true charge generated by the irradiation of radiation can be obtained. The process for calculating the offset is the dark reading process.

  In the dark reading process, when the reading process of the image data from each radiation detection element 7 up to the line Lx which is the final line of the scanning line 5 is completed, first, the reset process of each radiation detection element 7 is performed in the same manner as described above. Done. In the reset process, the voltage applied to each TFT 8 is switched from the off voltage Voff to the on voltage Von1 at time T5, and the on voltage is decreased from the voltage value Von1 to the voltage value Von2 at time T6, which is not shown in FIG. The voltage applied to each TFT 8 is switched from the on voltage Von2 to the off voltage Voff.

When the voltage is switched to the off voltage Voff at time T7 and each TFT 8 is turned off, the dark charge generated in each radiation detection element 7 is accumulated in each radiation detection element 7 thereafter. In the dark reading process, the radiation image capturing apparatus 1 is not irradiated with radiation, and the lines L1 to Lx of the scanning line 5 are left for the same periods ΔT _{1 to} ΔT _x as in the case of radiation image capturing, Dark charges are accumulated in each radiation detection element 7.

The dark charges accumulated in each radiation detection element 7 in each period ΔT _{1 to} ΔT _x in the dark reading process are the dark charges accumulated in each radiation detection element 7 in each period ΔT _{1 to} ΔT _x at the time of radiographic imaging. In order to set the same amount as much as possible, after each period ΔT _{1 to} ΔT _x elapses, the scanning for applying the signal readout on-voltage Von1 from the gate driver 15b of the scanning driving means 15 at the same timing as above. Processes similar to the above, such as sequentially switching (that is, scanning) the lines 5 to Lx of the line 5 to read out the dark charges accumulated from the respective radiation detection elements 7 and amplifying them by charge voltage conversion by the read circuit 17. Are stored in the storage means 40 as dark reading values.

  The dark reading value obtained in this way can be used as an offset as it is, and for example, the above-described dark reading processing is performed a plurality of times to obtain each radiation detection element 7. It is also possible to configure such that an average value of dark reading values for a plurality of times and the like are used as an offset amount. By performing the dark reading process in this way, it is possible to accurately acquire an offset for correcting the image data.

  Further, as described above, the reset processing of each radiation detection element 7 unique to the present invention changes the power supply state to each member of the radiation image capturing apparatus 1 from the power saving mode to the image capture possible mode for radiation image capturing. Not only when switching, but also in reset processing for dark reading processing (see times T5 to T7 in FIG. 15) and the like.

  As described above, according to the radiographic image capturing apparatus 1 according to the present embodiment, the gate electrode of the TFT 8 serving as the switch means of the radiation detecting element 7 in the reset processing of each radiation detecting element 7 performed before radiographic image capturing or the like. After applying a high on-voltage Von1 which is a normal on-voltage once, the voltage applied to 8g is lowered to the gate electrode 8g of the TFT 8 until the on-voltage voltage value is lowered and radiation irradiation is started. The ON voltage Von2 is continuously applied.

  Therefore, first, by applying a high on-voltage Von1 that is a normal on-voltage to all the TFTs 8, both the normal radiation detection element 7 and the abnormal radiation detection element 7 are applied to the radiation detection element 7. It is possible to sufficiently discharge and remove the excess charge accumulated. Further, by continuing to apply the on-voltage Von2 to the TFT 8 until radiation irradiation is started, it is possible to sufficiently discharge and remove excess charges accumulated in the radiation detection element 7.

  Further, by reducing the high on-voltage Von1 applied to the gate electrode 8g of the TFT 8 and continuing to apply the low on-voltage Von2, not only the normal radiation detection element 7 but also the abnormal radiation detection element 7 flows out of it. It is possible to reduce the amount of current to be reduced to the same amount as the current amount ileak of the leak current including the dark current flowing through the normal radiation detection element 7. Therefore, it is possible to suppress power consumption of the battery 41 and prevent the battery 41 from being consumed.

  Further, by continuing to apply the ON voltage Von2 to the TFT 8 until radiation irradiation is started, dark charges generated in each radiation detection element 7 until radiation irradiation is started are caused from each radiation detection element 7. Since it flows out and is removed, it is possible to accurately remove at least noise components generated before the start of radiation irradiation from the finally obtained image data.

  Note that the voltage value of the reduced on-voltage Von2 is, for example, that a normal radiation detection element 7 is used and the maximum current amount imax (Von2) of the on-current that can flow through the TFT 8 flows to the normal radiation detection element 7. A voltage value equal to the current amount ileak of the leakage current including the dark current is measured, and is set in advance by adding a predetermined voltage value to the voltage value.

  Similarly to the case of detecting the start of radiation irradiation to the radiographic imaging apparatus 1, the current amount I of the current flowing through the connection 10 of the bias line 9 detected by the current detection means 43 is monitored, and the current amount I is calculated. It can be configured to detect the end of irradiation by decreasing. In addition, the end of radiation irradiation is not detected, and after a predetermined time has elapsed from the time T3 when radiation irradiation is started, reading of charges (image data) from each radiation detection element 7 is started in advance. You may set it.

  Furthermore, although the case where the current detection unit 43 is provided has been described in the above embodiment, the current detection unit 43 is not necessarily provided. For example, each value of the off voltage Voff and the two types of on voltages Von1 and Von2 It is also possible to set each time interval in advance so that the scanning drive unit 15 performs a reset process, a read process, a dark read process, and the like according to these settings.

[Radiation imaging system]
In the radiographic imaging apparatus 1 described above, the radiation imaging apparatus 1 is irradiated with radiation by using a current sensor 43 provided with a radiation sensor or detecting a current amount I of the current flowing through the connection 10 of the bias line 9. The case where the start and end are detected has been described. However, in many cases, the radiation imaging apparatus 1 is not provided with the radiation sensor or the current detection means 43.

  In such a case, the radiation image capturing apparatus 1 can be configured to transmit a signal notifying the start or end of radiation irradiation to the radiation image capturing apparatus 1 from a radiation generator that irradiates the radiation image 1 or the like. .

  Further, in an actual radiation generator, it often takes about 1 second from the start of the radiation source of the radiation generator to the irradiation of radiation. For this reason, it is possible to configure the radiographic imaging apparatus 1 to perform a reset process before radiographic imaging using the time from activation of the radiation source to irradiation.

  Below, the radiographic imaging system for implement | achieving it is demonstrated. FIG. 16 is a diagram showing an overall configuration of the radiographic image capturing system according to the present embodiment. As shown in FIG. 16, the radiographic imaging system 50 includes, for example, an imaging room R <b> 1 that irradiates radiation and images a subject that is a part of a patient (not shown), and an operator such as a radiologist radiates It is arrange | positioned in front chamber R2 which performs operations, such as irradiation.

  In the present embodiment, in the imaging room R1, a Bucky device 51 that can be loaded with the above-described radiographic image capturing device 1 (portable radiographic image capturing device 1) or an X-ray tube (not shown) that generates radiation to irradiate a subject. A radiation source 52 of the radiation generating apparatus, a radio access point (base station) 54 provided with a wireless antenna 53 that relays these communications when the radiographic imaging apparatus 1 and other apparatuses communicate wirelessly, and the like. ing.

  Further, in the front chamber R2, an operation console 56 of a radiation generation apparatus provided with an irradiation start switch 55 for instructing the start of irradiation of radiation from the radiation source 52, and a radiation image capturing apparatus 1 described later. A tag reader 57 and the like for detecting a tag are provided. The console 56 and the tag reader 57 of the radiation generating apparatus are connected to a console 58 provided outside the imaging room.

  The console 58 performs image processing using image data acquired by the radiation image capturing system 50, a dark read value, and the like, and generates a radiation image. It is possible to provide the console 58 in the front chamber R2. The console 58 is connected to storage means 59 composed of a hard disk or the like.

  Although the configuration of the radiographic image capturing apparatus 1 is as described above, in the present embodiment, the radiographic image capturing apparatus 1 further includes a tag (not shown). In this embodiment, a tag called a so-called RFID (Radio Frequency IDentification) tag is used as the tag, and the tag stores a control circuit that controls each part of the tag and a storage that stores unique information of the radiographic imaging apparatus 1 The part is built in compactly. The unique information includes, for example, a cassette ID, scintillator type information, size information, resolution, and the like as identification information assigned to the radiation image capturing apparatus 1.

  In addition, the radiographic image capturing apparatus 1 can be used in a so-called independent state that is not loaded in the bucky device 51. That is, the radiation image photographing apparatus 1 is arranged in a single state on, for example, a support stand provided in the photographing room R1 or a bucky device 51B for lying position photographing as shown in FIG. 1) and the patient's hand as the subject can be placed on the head, or can be used, for example, inserted between the patient's waist or legs lying on the bed and the bed. ing. In this case, for example, radiation image capturing is performed by irradiating the radiation image capturing apparatus 1 with radiation from a portable radiation source 52B or the like via a subject.

  The bucky device 51 is provided with a cassette holding portion 51a for holding the radiographic image capturing device 1 in a predetermined position, and the radiographic image capturing device 1 can be loaded into the cassette holding portion 51a. Further, in the present embodiment, as the bucky device 51, there are provided a bucky device 51A for standing position shooting and a bucky device 51B for standing position shooting. In the present embodiment, each of the bucky devices 51A and 51B is connected to the operation console 56 of the radiation generating device via a cable, a wireless access point (base station) 54, and the like.

  In the imaging room R1, at least one radiation source 52 including an X-ray tube that irradiates the radiation image capturing apparatus 1 with radiation through a subject is provided. In the present embodiment, one radiation source 52A is shared by the bucky devices 51A and 51B for standing position shooting and standing position shooting. It should be noted that it is also possible to configure each of the bucky devices 51A and 51B so that different radiation sources are associated with each other.

  The radiation source 52A is arranged suspended from the ceiling of the imaging room R1, for example, and is set up based on an instruction from an operation console 56 (to be described later) at the time of imaging. And the direction of the radiation is adjusted so that the radiation direction is in a predetermined direction.

  Further, in the present embodiment, a portable radiation source 52B that is not associated with the standing-up imaging device 51A or the lying-up imaging device 51B is also provided, and the portable radiation source 52B has an imaging function. It can be carried to any place in the room R1, and radiation can be emitted in any direction.

  In the present embodiment, the portable radiation source 52B is also set up based on an instruction from the console 56. In addition to this, for example, the operator manually sets up the radiation source 52B. It is also possible to configure to set up by transmitting a radio signal from the image capturing apparatus 1 to the portable radiation source 52B.

  As the X-ray tube of the radiation source 52, a radiation source using a rotating anode X-ray tube is preferably used. An X-ray tube is often configured to generate radiation by causing an electron beam emitted from a cathode to collide with an anode. However, if an electron beam continues to collide with the same position on the anode, The anode is damaged due to the occurrence. Therefore, in the rotating anode X-ray tube, the anode is extended so that the position where the electron beam collides does not become the same position, thereby extending the life of the anode.

  The front chamber R2 is provided with an operation console 56 of a radiation generating apparatus provided with an irradiation start switch 55 for instructing start of irradiation of radiation from the radiation source 52. In FIG. 16, the console 56 and the irradiation start switch 55 are described as separate bodies, but they are not necessarily configured as separate bodies.

  The console 56 is configured by a computer including a CPU and a dedicated processor. Further, as shown in FIGS. 17A to 17C, the irradiation start switch 55 includes a rod-shaped button portion 55a and a housing portion that supports the button portion 55a so that the button portion 55a can be pressed in the direction indicated by the arrow S in the drawing. 55b. As shown in FIG. 17A, the button portion 55a includes a cylindrical portion 55a1 protruding upward from the housing portion 55b and a columnar portion 55a2 protruding further upward from the inside thereof.

  Then, as shown in FIG. 17B, when the column portion 55a2 is pushed down to the upper end portion of the cylindrical portion 55a1 by the operator and the button portion 55a is half-pressed, a predetermined radiation source 52 is supplied from the console 56. When the activation signal is received, the radiation source 52 starts to rotate by starting rotation of the anode of the X-ray tube. This activation signal is also transmitted to the radiation image capturing apparatus 1 via the wireless access point 54.

  As shown in FIG. 17C, the operator further pushes the cylindrical portion 55a1 and the column portion 55a2 of the button portion 55a of the irradiation start switch 55 to the upper end portion of the housing portion 55b, so that the button portion 55a is When it is fully pressed, an irradiation signal is transmitted from the console 56 to a predetermined radiation source 52. When the radiation source 52 receives the irradiation signal, the irradiation signal is emitted. Yes. This irradiation signal is also transmitted to the radiation image capturing apparatus 1 via the wireless access point 54.

  Instead of transmitting the activation signal or the irradiation signal from the operation console 56 or the irradiation start switch 55 to the radiographic image capturing apparatus 1 via the wireless access point 54, the irradiation start switch 55 is pressed halfway or fully. When the irradiation start switch 55 is half-pressed, an activation signal (or a signal indicating that the radiation source 52 has been activated) is transmitted to the radiographic image capturing apparatus 1, and the irradiation start switch 55 is fully activated. It is also possible to provide a button operation detecting means 60 that transmits an irradiation signal (or a signal indicating that radiation has been irradiated from the radiation source 52) to the radiographic imaging device 1 when pressed.

  Note that the above-described configuration of the irradiation start switch 55 is not a configuration specific to the present invention, but is a configuration that is often used in an operation console of a normal radiographic image capturing system. Usually, the button unit 55a is half-pressed. Even if the button is fully pressed, the radiation is irradiated after a time of at least about 1 second has elapsed since the button was pressed halfway.

  Further, a tag reader 57 (see FIG. 16) for exchanging information with the radiographic imaging apparatus 1 using the RFID technology described above is installed in the vicinity of the entrance of the front chamber R2, and the tag reader 57 is connected to the front chamber R2. In addition, the radiographic imaging device 1 entering or leaving the imaging room R1 is detected, and the information is transmitted to the console 58. The console 58 manages the radiation image capturing apparatus 1 existing in the image capturing room R1 and the front room R2.

  The radiographic image capturing apparatus 1 is a mode in which the power supply state of each member can be captured from the power saving mode (sleep mode) by operating the power switch 36 by an operator such as a radiographer for radiographic image capturing. It is switched to (wake up mode) and loaded into the bucky device 51.

  Then, a subject that is a part of the patient is set on the radiation incident surface R side of the radiographic imaging apparatus 1. In the radiographic image capturing system 50 of the present embodiment, the radiographic image capturing apparatus 1 does not start the reset process of each radiation detection element 7 at the stage where the power supply state to each member is switched to the image capture enable mode. As described in the above-described embodiment of the radiation image capturing apparatus 1, the radiation detection elements 7 may be reset in stages.

  Then, when the operator moves to the console 56 of the radiation generating apparatus in the front chamber R2 and presses the button portion 55a of the irradiation start switch 55 halfway, an activation signal is transmitted from the console 56 to the predetermined radiation source 52. Then, the radiation source 52 is started by starting rotation of the anode of the X-ray tube, and this activation signal (or a signal indicating that the radiation source 52 has been activated) is operated by the console 56, the irradiation start switch 55 or the button operation. It is also transmitted from the detection means 60 to the radiographic imaging apparatus 1 via the wireless access point 54.

  When the activation signal is transmitted wirelessly via the wireless antenna 53 of the wireless access point 54 or via the cable from the wireless access point 54 and wired via the bucky device 51, control of the radiographic imaging device 1 is performed. The means 22 instructs the scanning drive means 15 to perform reset processing of each radiation detection element 7.

  In response to an instruction from the control unit 22, the scanning drive unit 15, as described in the embodiment of the radiographic image capturing apparatus 1 (see particularly FIG. 9 and FIG. 15), all the lines L 1 to Lx of the scanning line 5. After applying an on-voltage Von1 having a predetermined voltage value (for example, +15 [V]) to the gate electrode 8g of the TFT 8 serving as the switching means of each radiation detection element 7 through the voltage, the voltage value of the on-voltage is lowered to perform scanning. The reduced ON voltage Von2 is continuously applied to the gate electrode 8g of the TFT 8 through all the lines L1 to Lx of the line 5.

  When the operator half-presses the button portion 55a of the irradiation start switch 55 of the console 56 and then fully presses the button portion 55a of the irradiation start switch 55, the irradiation signal is sent from the console 56 to the predetermined radiation source 52. Is transmitted, and radiation is emitted from the radiation source 52. Further, this irradiation signal (or a signal indicating that the radiation source 52 has been irradiated) is sent from the console 56, the irradiation start switch 55 or the button operation detection means 60 to the radiographic image capturing apparatus 1 via the wireless access point 54. Sent.

  When receiving the irradiation signal transmitted from the console 56, the irradiation start switch 55, or the like, the control means 22 of the radiographic imaging apparatus 1 transmits a signal notifying the start of radiation irradiation to the scanning driving means 15. When the scanning drive unit 15 receives the signal from the control unit 22, the scanning driving unit 15 switches the on voltage Von 2 applied to the gate electrode 8 g of the TFT 8 through all the lines L 1 to Lx of the scanning line 5 to the off voltage Voff. All TFTs 8 are closed.

  In this way, charges generated in each radiation detection element 7 are accumulated in each radiation detection element 7. The subsequent processing is performed in the same manner as the processing described in the embodiment of the radiographic image capturing apparatus 1 described above. When the radiation irradiation is completed, the scanning driving unit 15 performs the gate operation as shown in FIG. While sequentially switching the lines L1 to Lx of the scanning line 5 to which the on-voltage Von1 for signal reading is applied from the driver 15b, the charges accumulated from the radiation detecting elements 7 are read and converted into image data and stored in the storage means 40. Let

  Thereafter, a dark reading process is performed. In the dark reading process, after the reset process of each radiation detection element 7 is performed, the off voltage Voff is applied to the gate electrode 8g of each TFT 8, and no radiation is irradiated. After being left for a predetermined time, the dark charge generated in each radiation detection element 7 for each line L1 to Lx of the scanning line 5 is read as a dark read value and stored in the storage means 40.

  The image data and dark reading value for each radiation detection element 7 obtained in this way are transmitted to the console 58, an offset is calculated based on the dark reading value, and the offset is subtracted from the image data. Thus, final image data for each radiation detection element 7 is calculated, and a radiation image is generated.

  As described above, according to the radiographic image capturing system 50 according to the present embodiment, the effects of the radiographic image capturing apparatus 1 in the above-described embodiment can be effectively exhibited.

  In the reset process of each radiation detection element 7, the radiation source is in a state in which the on voltage Von 2 reduced from the high on voltage Von 1, which is a normal on voltage, is applied to the gate electrode 8 g of the TFT 8 of each radiation detection element 7. It takes about 1 second at the shortest time from when the activation signal is transmitted to 52 until the irradiation signal is transmitted.

  Therefore, it is possible to sufficiently discharge and remove excess charges accumulated in each radiation detection element 7 and apply an on-voltage Von2 to the gate electrode 8g of the TFT 8 for a longer time than necessary to obtain a radiation image. It is possible to accurately prevent the power of the battery 41 of the photographing apparatus 1 from being wasted, and it is possible to prevent the battery 41 from being consumed.

1 Radiographic imaging device (portable radiographic imaging device)
5, L1 to Lx Scanning line 6 Signal line 7 Radiation detection element 8 TFT (switch means)
9 Bias line 14 Bias power supply 15 Scanning drive means 39 Antenna device (communication means)
41 Battery 43 Current detection means 50 Radiation imaging system 52 Radiation source (radiation generator)
55 Irradiation start switch (radiation generator)
56 console (radiation generator)
I Current amount ileak Leakage current P Detection part r Region Voff Off voltage Von1 On voltage Von2 Reduced on voltage

Claims (9)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
When an on-voltage is applied to the scanning line arranged and connected to each radiation detection element, a charge generated in the radiation detection element is released, and an off-voltage is applied to the connected scanning line. Switch means for accumulating charges generated in the radiation detection element in the radiation detection element;
Scanning drive means for controlling the voltage applied to the switch means via the scanning lines;
With
A battery for supplying power to each of the above means is incorporated,
The scan driving unit is configured to apply a predetermined value to the switch unit via each scanning line during a reset process of the radiation detection element that discharges excess charges accumulated in the radiation detection element before radiographic imaging. The on-voltage of the voltage value is applied, and then the voltage value of the on-voltage is lowered, and the switch means is lowered through the scanning lines until the radiation irradiation is started. Continue to apply the ON voltage ,
The voltage value of the lowered on-voltage is set to a voltage value at which the amount of on-current flowing through the switch means exceeds the amount of leakage current flowing through a normal radiation detection element. A portable radiographic imaging device. A bias line connected to each of the radiation detection elements;
A bias power source for applying a bias voltage to each radiation detection element via the bias line;
Current detection means for detecting the amount of current flowing through the bias line;
Further comprising
The scanning driving means applies the on-voltage having a predetermined voltage value to the switch means via the scanning lines during the reset process of the radiation detecting element before the radiographic image capturing, and the current detecting means When the time change rate of the current amount of the current flowing through the bias line detected by the method is less than or equal to a predetermined threshold value, the voltage value of the on-voltage is reduced until the radiation irradiation is started. The portable radiographic image capturing apparatus according to claim 1, wherein the reduced on-voltage is continuously applied to the switch unit via each scanning line. After the scan driving means has lowered the voltage value of the on-voltage, irradiation of the radiation has started because the amount of the current flowing through the bias line detected by the current detection means has increased. portable radiographic imaging device according to 請 Motomeko 2 and detecting the.   The scan driving means performs a process of reducing the voltage value of the on-voltage applied to the switch means via each scanning line during the reset process of the radiation detection element before the radiographic image capturing. The portable radiographic image capturing apparatus according to any one of claims 1 to 3, wherein the operation is performed simultaneously for all the switch units via the scanning line.   The scan driving means starts applying the on-voltage simultaneously to all the switch means via all the scanning lines during the reset process of the radiation detecting element before the radiographic image capturing. The portable radiographic imaging device according to any one of claims 1 to 4, wherein the portable radiographic imaging device is characterized.   The scanning drive means continues to apply the on-voltage to the switch means via the scanning lines during the reset process of the radiation detection element before the radiographic imaging, and the radiation irradiation starts. 6. The portable radiographic imaging according to claim 1, wherein the voltage to be applied to the switch means is switched to the off voltage via each of the scanning lines. apparatus.   The scan driving means performs a process of switching the voltage applied to the switch means to the off voltage via the scan lines to the off voltage in the reset process of the radiation detection element before the radiographic image capturing. The portable radiographic image capturing apparatus according to claim 6, wherein the portable radiographic image capturing apparatus performs all of the switch means simultaneously through a scanning line. The portable radiographic image capturing apparatus according to any one of claims 1 to 7, further comprising a communication unit capable of communicating with outside.
A radiation generator comprising: a radiation source that irradiates radiation to the portable radiation imaging apparatus; and an operation console that activates the radiation source and includes an irradiation start switch that instructs the radiation source to start radiation irradiation; ,
With
When the scanning drive unit of the portable radiographic image capturing apparatus receives the radiation source activation signal transmitted from the console via the communication unit, it starts resetting the radiation detection element. A featured radiographic imaging system. When the scanning drive unit of the portable radiographic imaging apparatus receives an irradiation signal of the radiation source transmitted from the console via the communication unit, the scan driving unit applies the switch to the switch unit via the scanning lines. The radiographic imaging system according to claim 8 , wherein the voltage to be switched is switched to the off voltage.

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