JP2011193306A - Apparatus and system for photographing radiation image - Google Patents

Abstract

A radiographic imaging device capable of generating a radiographic image without shading based on acquired image data is provided.
When a period for reading data D from all radiation detection elements 7 on a detection unit P is one frame, a control means 22 applies an ON voltage to a scanning line 5 and is connected to the scanning line 5. The image data reading process for reading the image data d from the radiation detecting element 7 and the total value of each charge q leaked from each radiation detecting element 7 without applying the on-voltage to each scanning line 5 leaks for each signal line 6 The leak data reading process to be read as data Dleak is repeatedly performed for each frame, the start of radiation irradiation is detected based on the image data d, and a predetermined number including the frames for which the image data reading process has been performed at the start of radiation irradiation In each frame, image data d and leak data Dleak for each frame are acquired for each radiation detection element.
[Selection] Figure 7

Description

  The present invention relates to a radiographic image capturing apparatus and a radiographic image capturing system, and more particularly to a radiographic image capturing apparatus that performs readout processing even during radiation irradiation and a radiographic image capturing 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 types of so-called indirect radiographic imaging devices have been developed that convert charges into electromagnetic signals after they have been converted into electromagnetic waves of a wavelength, and then generated by 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 apparatus is known as an FPD (Flat Panel Detector), and conventionally formed integrally with a support base (or a bucky apparatus) (see, for example, Patent Document 1). A portable radiographic imaging device in which an element or the like is housed in a housing has been developed and put into practical use (see, for example, Patent Documents 2 and 3).

  In such a radiographic imaging apparatus, for example, as shown in FIGS. 3 and 7 to be described later, the radiation detection elements 7 are usually arranged in a two-dimensional form (matrix) on the detection unit P, and each radiation detection element 7 is arranged. Further, switch means each formed of a thin film transistor (hereinafter referred to as TFT) 8 is provided. Then, before the radiation image is taken, that is, before the radiation image taking device is irradiated with radiation from the radiation generating device, excessive charge remaining in each radiation detecting element 7 is released while appropriately controlling the on / off of the TFT 8. In many cases, the reset process is performed.

  Then, after the reset processing of each radiation detection element 7 is completed, radiation is generated in a state where all the TFTs 8 are turned off by applying an off voltage to the TFTs 8 through the scanning lines 6 from the gate drivers 15b of the scanning driving means 15. When radiation is irradiated from the apparatus to the radiographic imaging apparatus, a charge corresponding to the radiation dose is generated in each radiation detection element 7 and accumulated in each radiation detection element 7.

  Then, after the radiographic image is captured, the lines L1 to Lx of the scanning line 5 to which the on-voltage for signal readout is applied from the gate driver 15b of the scanning driving unit 15 are sequentially switched and accumulated from the radiation detecting elements 7 in the inside. In many cases, the read charge is read out, and is read out as image data by charge-voltage conversion by the read-out circuit 17.

  However, in the case of such a configuration, an interface between the radiographic imaging device and the radiation generation device is accurately constructed, and the radiographic imaging device side accumulates charges in each radiation detection element 7 when radiation is irradiated. Although it is necessary to be ready, it is not always easy to construct an interface between devices. If radiation is irradiated while the radiation imaging apparatus side is performing reset processing of each radiation detection element 7, the charges generated by the radiation flow out from each radiation detection element 7, and irradiation is performed. There has been a problem that the charge of the emitted radiation, that is, the conversion efficiency into image data is lowered.

  Therefore, in recent years, various techniques for detecting that radiation has been irradiated by the radiographic imaging apparatus itself have been developed. As a part of those techniques, for example, using the techniques described in Patent Document 4 and Patent Document 5, it is considered that the radiation imaging apparatus itself detects radiation irradiation.

  In Patent Documents 4 and 5, before the start of radiation irradiation to the radiographic imaging apparatus, for example, as shown in FIG. A radiographic imaging apparatus that repeatedly reads out image data from the radiation detection element 7 while sequentially switching each of the lines L1 to Lx, and continuously reads out the image data while radiation is being applied. And a method for reading out image data.

  Then, when the period for reading out each image data from all the radiation detection elements 7 arranged on the detection unit P is one frame, the frame next to the frame from which the radiation irradiation has ended to the frame from which the radiation irradiation has started. A technique for reconstructing image data for each radiation detection element 7 by adding the image data read for each frame up to each radiation detection element 7 is disclosed.

  That is, as shown in FIG. 23, the gate driver 15b starts to apply the on-voltage to each scanning line 5 in order from the uppermost scanning line 5 in the figure, and thereafter the scanning line 5 to which the on-voltage is applied. In the process of reading out image data from each radiation detection element 7 for each frame, which is performed while sequentially switching in the downward direction in the figure, for example, the scanning line 5 of the portion ΔT indicated by hatching in FIG. It is assumed that radiation is irradiated and irradiation is completed while the on-voltage is sequentially applied.

  In this case, not only the image data read from each radiation detection element 7 in the first frame, which is a frame irradiated with radiation, but also the image data read from each radiation detection element 7 in the next second frame. Is added to the image data of the first frame, and the image data for each radiation detection element 7 is reconstructed.

  As shown in FIG. 25, the image data read from each radiation detection element 7 in the first to third frames is added for each radiation detection element 7 in consideration of the next third frame. In some cases, the image data for each radiation detection element 7 is reconstructed.

  24 and 25 do not represent that radiation is applied only to the portion ΔT indicated by hatching, and the ON voltage is sequentially applied from the uppermost scanning line 5 as shown in FIG. This indicates that when reading processing is performed while switching the scanning line 5 to be applied, radiation is irradiated while the ON voltage is sequentially applied to the scanning line 5 of the portion ΔT indicated by hatching. Is irradiated over the entire area of the detection unit P.

  Then, each radiation detection element 7 connected to the scanning line 5 to which the on-voltage is applied from the gate driver 15b of the scanning driving means 15 while the radiation imaging apparatus is irradiated with radiation is turned on before that. Image data having a significantly larger value than the data read from each radiation detection element 7 connected to the scanning line 5 to which the voltage is applied is read. By utilizing this, the value of the electric charge read from each radiation detection element 7 is monitored, so that the radiation image capturing apparatus itself can detect that the radiation image capturing apparatus has been irradiated with radiation.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP-A-9-140691 Japanese Patent Laid-Open No. 7-72252

  However, in the study by the present inventors, for example, as shown in FIG. 25, each image data read from each radiation detection element 7 in the first to third frames is added for each radiation detection element 7. When the image data for each radiation detection element 7 is reconstructed and a radiation image p as shown in FIG. 26A is generated, the scanning line to which the on-voltage is sequentially applied while the radiation is irradiated 5 is larger than the image data of the upper image area A and the lower image area B of the image area δT corresponding to 5 (that is, the image area corresponding to the shaded portion ΔT in FIG. 25). ing.

  That is, for example, it is generated based on each image data d reconstructed by adding each image data acquired when the same dose of radiation is uniformly applied to the entire detection unit P of the radiographic imaging device. In the radiation image p (see FIG. 26A), when viewing each image data d that has been added and reconstructed along the extending direction of the signal line 6 (the vertical arrow direction in the figure), As shown in FIG. 26B, compared to the image data d of the image area A and the image area B, the image of the image area δT corresponding to the scanning line 5 to which the ON voltage is sequentially applied while the radiation is applied. The data d becomes a large value.

  Therefore, the portion of the image region δT in the radiation image p becomes slightly black (that is, darker) than the image region A and the image region B. In this way, light and shade appear in the radiographic image p even though the radiographic imaging device is uniformly irradiated with radiation.

  This is not only the case where the same dose of radiation is uniformly applied to the entire detection unit P of the radiographic imaging apparatus, but also the radiographic imaging was performed by actually irradiating the radiographic imaging apparatus through the subject. Even in this case, shading appears in the similarly generated radiographic image. Then, when light and shade appear in the radiographic image generated in this way, the radiographic image becomes difficult to see.

  The present invention has been made in view of the above-described problems, and is based on image data obtained by a radiographic imaging apparatus that continuously performs data reading processing while radiation is being applied. It is an object of the present invention to provide a radiographic imaging apparatus capable of generating a non-radioscopic image and a radiographic imaging system using the same.

In order to solve the above-described problem, the radiographic imaging device of the present invention includes
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:
Scanning drive means for applying the data reading voltage while sequentially switching the scanning lines when reading data from the radiation detecting element;
A switch element connected to each of the scanning lines, and discharging the charge accumulated in the radiation detection element to the signal line when the voltage for reading data is applied;
A readout circuit that converts the charge read from the radiation detection element into the data;
Control means for controlling at least the scanning drive means and the readout circuit to perform a readout process of the data from the radiation detection element;
With
When the period for reading the data from all the radiation detection elements on the detection unit is one frame,
The control means includes
An image data read process for reading the data as image data from the radiation detection element connected to the scan line by applying a voltage for reading the data to the scan line from the scan driving means, and for each scan line Leak data read processing for reading out the total value of each charge leaked from all the radiation detection elements connected to the signal line without applying the data read voltage as leak data for each signal line And repeatedly for each frame,
Detecting at least the start of radiation irradiation based on the value of the image data read in the image data reading process;
In each of a predetermined number of frames including the frame that has been subjected to the image data reading process at the time of detecting the start of radiation irradiation, the image data and the leak data for each frame are stored for each radiation detection element. It is characterized by acquiring.

Moreover, the radiographic imaging system of the present invention is
The radiographic imaging device of the present invention comprising a communication means;
When the image data and the leak data are transmitted from the radiographic imaging device, the leak data is subtracted from the image data for each radiation detection element to obtain true image data for each frame. Calculating, adding true image data for each frame by the predetermined number of frames, and calculating true image data for each radiation detection element;
It is characterized by providing.

  According to the radiation image capturing apparatus and the radiation image capturing system of the system as in the present invention, not only the image data reading process for reading the image data d but also the leak data reading process for reading the leak data is performed. Leakage from other radiation detection elements included in each image data d acquired in the readout process can be acquired as leak data in the leak data readout process, and if the leak data is subtracted from the image data d Thus, it is possible to obtain true image data that does not include leaks from other radiation detection elements.

  Therefore, by generating a radiographic image using true image data that does not include leaks from other radiation detection elements, it is possible to generate a radiographic image with no shading, making it very easy to see the radiographic image It becomes possible.

It is a perspective view which shows the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the XX line in FIG. It is a top view which shows the structure of the board | substrate of a radiographic imaging apparatus. 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 YY 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 block diagram showing the equivalent circuit of a radiographic imaging apparatus. It is a block diagram showing the equivalent circuit about 1 pixel which comprises a detection part. It is a timing chart which shows the timing which switches the voltage applied to each scanning line in an image data read-out process between ON voltage and OFF voltage. It is a timing chart which shows the timing which switches the voltage applied to each scanning line between ON voltage and OFF voltage in the reset process of each radiation detection element. It is a figure showing the timing chart in an image data read-out process, (A) shows a charge reset switch, (B) shows a pulse signal, and (C) shows on / off timing of a TFT. It is a graph showing the change of the voltage value etc. in a correlated double sampling circuit. It is a figure showing the timing chart in leak data read-out processing, (A) shows a charge reset switch, (B) shows a pulse signal, and (C) shows on / off timing of TFT. It is a figure which shows the whole structure of the radiographic imaging system which concerns on this embodiment. It is a figure showing the timing chart in the image data read-out process and leak data read-out process performed alternately, (A) is a switch for charge reset, (B) is a pulse signal, (C), (D) is ON of each TFT. / Indicates the off timing. It is a timing chart which shows the example of the timing which a radiation is irradiated in the case of the read-out process of each data from each radiation detection element. It is a figure explaining the relationship between the electric charge discharged | emitted from the radiation detection element before and behind radiation irradiation, each electric charge leaked from other radiation detection elements, and the read image data. It is a figure explaining the relationship between the electric charge discharge | released from a radiation detection element in the middle of radiation irradiation, each electric charge leaked from other radiation detection elements, and the read image data. It is a figure explaining the relationship between each electric charge which leaks from all the radiation detection elements connected to a signal line, and the leak data read. It is a graph explaining that there is no difference in true image data between image areas, and that there is no shading in all image areas of a radiographic image. It is a figure showing a timing chart at the time of performing leak data read-out processing at a rate of 1 time in 2 times of image data read-out processing, (A) is a charge reset switch, (B) is a pulse signal, (C), ( D) represents the on / off timing of each TFT. It is a figure explaining the example of the position on the detection part of an abnormal radiation detection element, and the state in which the radiation detection element in which normal true image data is not calculated is located in a line form in image area (delta) T. It is a figure explaining the read-out process of the image data from each radiation detection element for every frame. It is a figure showing that irradiation was completed while radiation was irradiated while an ON voltage was sequentially applied to the scanning line of the shaded part of the 1st frame. It is a figure explaining the image data for 3 frames used for reconstruction of image data. (A) It is a figure showing the radiographic image produced | generated based on the reconstructed image data, (B) It is a graph showing that the image data of image area (delta) T becomes larger than the image data of image area A and B. .

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

  In the following description, the radiographic imaging device is a so-called indirect radiographic imaging device that includes a scintillator or the like and converts the irradiated radiation into electromagnetic waves of other wavelengths such as visible light to obtain an electrical signal. As will be described, the present invention can also be applied to a direct radiographic imaging apparatus. Although the case where the radiographic image capturing apparatus is portable will be described, the present invention is also applicable to a radiographic image capturing apparatus formed integrally with a support base or the like.

[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 XX of FIG. As shown in FIGS. 1 and 2, the radiation image capturing apparatus 1 according to the present embodiment is configured by housing a scintillator 3, a substrate 4, and the like in a housing 2.

  The housing 2 is formed of a material such as a carbon plate or plastic that at least the radiation incident surface R transmits 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.

  Further, as shown in FIG. 1, the side surface portion of the housing 2 can be opened and closed for replacement of a power switch 36, an indicator 37 composed of LEDs or the like, and a battery 41 (see FIG. 7 described later). The lid member 38 and the like are disposed. Further, in the present embodiment, image data d, leak data Dleak, etc., which will be described later, are transmitted to and received from the side surface portion of the lid member 38 with an external device such as a console 58 (see FIG. 14) which will be described later. An antenna device 39 is embedded as a communication means.

  The installation position of the antenna device 39 is not limited to the side surface portion of the lid member 38, and the antenna device 39 can be installed at an arbitrary position of the radiographic image capturing apparatus 1. The number of antenna devices 39 to be installed is not limited to one, and a plurality of antenna devices 39 may be provided. Furthermore, the image data d and the like can be configured to be transmitted / received to / from an external device in a wired manner. In this case, for example, a connection for connecting by inserting a cable or the like as a communication unit is possible. Terminals and the like are provided on the side surface of the radiation image capturing apparatus 1.

  As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a lead thin plate (not shown) on the lower side of the substrate 4, and an electronic component 32 and the like are disposed on the base 31. The 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 is applied to the gate electrode 8g, and is stored in the radiation detection element 7. The electric charge that is present is emitted 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 electric charge is held and 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 cross-sectional view taken along line YY 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 the 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. Further, each bias line 9 is bound to the 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, each input / output terminal 11 has an anisotropic COF (Chip On Film) 12 in which a chip such as a gate IC 12a constituting a gate driver 15b of a scanning drive means 15 described later is incorporated on the film. They are connected via an anisotropic conductive adhesive material 13 such as an anisotropic conductive adhesive film or an anisotropic 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 a block diagram showing an equivalent circuit of the radiographic imaging apparatus 1 according to the present embodiment, and FIG. 8 is a block diagram showing an equivalent circuit for 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 supply 14 is connected to a control means 22 described later, and the control means 22 controls the bias voltage applied to each radiation detection element 7 from the bias power supply 14.

  As shown in FIGS. 7 and 8, in this embodiment, it can be seen that the bias line 9 is connected via the second electrode 78 to the p-layer 77 side (see FIG. 5) of the radiation detection element 7. In addition, the bias power supply 14 supplies a voltage equal to or lower than a voltage applied to the second electrode 78 of the radiation detection element 7 via the bias line 9 as a bias voltage on the first electrode 74 side of the radiation detection element 7 (that is, a so-called reverse bias voltage). Is applied.

  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 the scanning line 5 extending from the gate driver 15b of the scanning driving means 15 to be 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.

  The scanning drive means 15 is a power supply circuit 15a that supplies an on voltage and an off voltage to the gate driver 15b via the wiring 15c, and a voltage applied to each line L1 to Lx of the scanning line 5 between the on voltage and the off voltage. A gate driver 15b that switches between the on state and the off state of each TFT 8 is provided.

  When the scanning drive unit 15 receives a trigger signal from the control unit 22 (to be described later) during the reading process of data D (image data d and leak data Dleak to be described later) from each radiation detection element 7, the gate driver 15b The switching between the on-voltage and the off-voltage of the voltage applied to the lines L1 to Lx of the scanning line 5 is started.

  Specifically, in the present embodiment, the scanning drive unit 15 receives a trigger signal from the control unit 22 when reading data D (in this case, image data d described later) from each radiation detection element 7. Upon reception, for example, as shown in FIG. 9, a process of sequentially switching the lines L1 to Lx of the scanning line 5 for switching the voltage applied from the gate driver 15b between the on voltage (that is, the voltage for reading data) and the off voltage. This is repeated for each frame, and data D (in this case, image data d) is read from each radiation detection element 7 connected to each line L1 to Lx of the scanning line 5 via each TFT 8. Yes.

  In the following, as shown in FIG. 9, data D (image data d to be described later) is obtained from all the radiation detection elements 7 for one surface arranged two-dimensionally on the detection unit P (see FIGS. 3 and 7). And the leak data (Dleak) are referred to as one frame. In this embodiment, an image data read process for reading image data d from each radiation detection element 7 and a leak data read process for reading leak data Dleak described later are alternately performed. I will explain later.

  In addition, the reset of each radiation detection element 7 that discharges the charge remaining in each radiation detection element 7 before the data D is read from each radiation detection element 7 or until the next radiographic image is taken. It is also possible to configure to perform processing.

  When performing the reset processing of each radiation detection element 7, for example, the scanning drive unit 15 scans the voltage applied from the gate driver 15b between the on voltage and the off voltage, as shown in FIG. The lines L1 to Lx are sequentially switched to perform a reset process Rm for one surface, and the reset processing of each radiation detection element 7 is performed while repeatedly performing the reset process Rm for one surface as necessary. Is done.

  As shown in FIGS. 7 and 8, each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16. In the present embodiment, the readout IC 16 is provided with one readout circuit 17 for each signal line 6.

  The readout circuit 17 includes an amplification circuit 18 and a correlated double sampling circuit 19. An analog multiplexer 21 and an A / D converter 20 are further provided in the reading IC 16. 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. In addition, a power supply unit 18 d for supplying power to the amplifier circuit 18 is connected to the amplifier circuit 18. A switch 18e that opens and closes in conjunction with the charge reset switch 18c is provided between the operational amplifier 18a and the correlated double sampling circuit 19.

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 reference potential V ₀ is applied to the non-inverting input terminal on the input side of the amplifier circuit 18. . Note that the reference potential V ₀ is set to an appropriate value, and in this embodiment, for example, 0 [V] is applied.

  Further, the charge reset switch 18c of the amplifier circuit 18 is connected to the control means 22, and is controlled to be turned on / off by the control means 22, so that the charge reset switch 18c is turned on. The switch 18e is turned off in conjunction with it, and when the charge reset switch 18c is turned off, the switch 18e is turned on in conjunction with it.

  When the data D (image data d and leak data Dleak described later) is read out from each radiation detection element 7, the charge reset switch 18c is turned off and the switch 18e is turned on. When the TFT 8 is turned on, the charge accumulated in each radiation detection element 7 is discharged from each radiation detection element 7 to the signal line 6 via the TFT 8 and flows into the capacitor 18b via the signal line 6. Accumulated.

  A voltage value corresponding to the accumulated charge amount is output from the output side of the operational amplifier 18a. In this way, the amplifier circuit 18 outputs a voltage value according to the amount of charge output from each radiation detection element 7 and converts the charge voltage.

  When the amplifier circuit 18 is reset, the charge reset switch 18c is turned on, and when the switch 18e is turned off, the input side and the output side of the amplifier circuit 18 are short-circuited. The charge accumulated in 18b is discharged.

  Then, the discharged electric charge passes through the operational amplifier 18a from the output terminal side of the operational amplifier 18a, goes out from the non-inverting input terminal and is grounded, or flows out to the power supply unit 18d, whereby the amplifier circuit 18 is reset. 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 image data reading process for reading the image data d from each radiation detection element 7, as shown in FIG. 11A, first, the charge reset switch 18c of the amplifier circuit 18 of each reading circuit 17 is controlled. It is turned off. At that time, the so-called kTC noise is generated at the moment when the charge reset switch 18c is turned off, and the charge caused by the kTC noise accumulates in the capacitor 18b of the amplifier circuit 18.

Therefore, as shown in FIG. 12, the voltage value output from the amplifier circuit 18 starts from the above-described reference potential V ₀ at the moment when the charge reset switch 18c is turned off (indicated as “18coff” in FIG. 12). It changes by the amount of electric charge caused by kTC noise and changes to a voltage value Vin. At this stage, the control means 22 transmits the first pulse signal Sp1 to the correlated double sampling circuit 19, as shown in FIG. 11B, at that time (“CDS hold” (left side in FIG. 12)). The voltage value Vin output from the amplifier circuit 18 is held.

  Subsequently, as shown in FIG. 9, an on-voltage is applied to one scanning line 5 (for example, line Ln of the scanning line 5) from the gate driver 15 b of the scanning driving unit 15, and the gate electrode 8 g is applied to the scanning line 5. Is turned on (see FIG. 11C. In FIG. 12, “TFTon” is displayed), the charges accumulated from the radiation detecting elements 7 to which these TFTs 8 are connected are As shown in FIG. 12, the voltage value output from the amplifying circuit 18 rises according to the amount of charge accumulated in the capacitor 18b as it flows into the capacitor 18b of the amplifying circuit 18 via the signal line 6 and accumulates.

  Then, after a predetermined time elapses, the control means 22 switches the on-voltage applied from the gate driver 15b to the scanning line 5 to the off-voltage to the scanning line 5 as shown in FIG. 11C. The TFT 8 connected to the gate electrode 8g is turned off (indicated as “TFToff” in FIG. 12), and as shown in FIG. 11B, the second pulse signal is sent to each correlated double sampling circuit 19 at this stage. Sp2 is transmitted, and the voltage value Vfi output from the amplifier circuit 18 at that time is held (displayed as “CDS hold” (right side) in FIG. 12).

  When each correlated double sampling circuit 19 holds the voltage value Vfi with the second pulse signal Sp2, the voltage value difference Vfi-Vin is calculated, and the calculated difference Vfi-Vin is downstream as analog value image data d. To output.

  The image data d 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 d into digital values, outputs them to the storage means 40, and sequentially stores them.

  Further, the control means 22 applies the on-voltage from the gate driver 15b of the scanning drive means 15 as shown in FIG. 9, in the image data read processing for reading the image data d from each radiation detection element 7 as described above. This is performed each time the lines L1 to Lx of the scanning line 5 are sequentially switched.

  In FIG. 11A, FIG. 13A and FIG. 15, which will be described later, only on / off of the charge reset switch 18c is described, and on / off of the switch 18e (see FIG. 8) is described. Although not done, as described above, the switch 18e is turned off / on in conjunction with the on / off of the charge reset switch 18c. In the following description, only the operation of the charge reset switch 18c may be described, but the same applies to that case.

  On the other hand, as will be described later, in this embodiment, all the radiation detection elements connected to each signal line 6 immediately after or immediately before the image data reading process for reading the image data d from the radiation detection element 7 as described above. The leak data reading process for reading the total value of the charges leaking from 7 as the leak data Dleak for each signal line 6 is alternately performed with the image data reading process.

  In the leak data reading process, as shown in FIG. 13C, an off voltage is applied to each of the lines L1 to Lx of the scanning line 5 in a state where no on voltage is applied to each of the lines L1 to Lx of the scanning line 5. Done in state.

  In the leak data reading process, as shown in FIGS. 13A and 13B, the on / off control of the charge reset switch 18c by the control means 22 and the pulse signal Sp1 to the correlated double sampling circuit 19, Sp2 transmission and the like are performed in the same manner as in the image data reading process, and the voltage value output from the amplifier circuit 18 in the leak data reading process increases as in the case of the image data reading process shown in FIG. However, the on / off operation of the TFT shown in FIG. 12 is not performed.

  In the case of the leak data reading process, the voltage value output from the amplifier circuit 18 increases. However, compared with the degree of increase in the case of the image data reading process shown in FIG. The degree of increase in the voltage value is small.

  Further, as can be seen by comparing FIG. 11B and FIG. 13B, in the present embodiment, the first pulse signal Sp1 is sent from the control means 22 to the correlated double sampling circuit 19 in the leak data reading process. Interval from when the second pulse signal Sp2 is transmitted, that is, the time interval between the two holding operations of the voltage value performed by the correlated double sampling circuit 19 (see FIG. 13B) However, it can be changed to a time interval different from the time interval (see FIG. 11B) in the image data reading process for reading the image data d.

  In the present embodiment, by changing the transmission interval for transmitting the two pulse signals Sp1 and Sp2 from the control means 22 to the correlated double sampling circuit 19, the voltage value is held twice in the leak data reading process. However, this point will be described later.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface connected to the bus, an FPGA (Field Programmable Gate Array), or the like (not shown). It is configured. 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. Further, as shown in FIG. 7 and the like, the control means 22 is connected with a storage means 40 constituted by a DRAM (Dynamic RAM) or the like.

  In the present embodiment, the above-described antenna device 39 is connected to the control unit 22, and each member such as the detection unit P, the scanning drive unit 15, the readout circuit 17, the storage unit 40, the bias power supply 14, and the like. A battery 41 for supplying electric power is connected. In addition, a connection terminal 42 for charging the battery 41 by supplying power to the battery 41 from a charging device (not shown) is attached to the battery 41.

  As described above, the control unit 22 controls the bias power supply 14 to set or vary the bias voltage applied from the bias power supply 14 to each radiation detection element 7. It is designed to control the operation.

  Here, before describing the image data reading process for reading the image data d from each radiation detection element 7, the leak data reading process performed immediately after or immediately before the image data reading process, and the like, the radiation image capturing system 50 will be described below. The configuration will be described.

[Radiation imaging system]
FIG. 14 is a diagram showing an overall configuration of the radiographic image capturing system according to the present embodiment. As shown in FIG. 14, the radiographic imaging system 50 includes, for example, an imaging room R1 that irradiates radiation and images a subject (part of a patient to be imaged) that is a part of a patient (not shown), a radiation technician, and the like. The anterior chamber R2 where the operator performs various operations such as control of the start of radiation applied to the subject, and the outside thereof are arranged.

  In the radiographing room R1, a bucky device 51 that can be loaded with the radiographic imaging device 1 described above, a radiation source 52 that includes an X-ray tube (not shown) that generates radiation to irradiate a subject, and a radiation generation device 55 that controls the radiation source In addition, when the radiographic image capturing apparatus 1 and the radiation generating apparatus 55 and the console 58 communicate wirelessly, a base station 54 provided with a wireless antenna 53 that relays these communications is provided.

  FIG. 14 shows a case where the portable radiographic imaging device 1 is used by being loaded into the cassette holding part 51a of the bucky device 51. However, as described above, the radiographic imaging device 1 is used as the bucky device 51. Or may be formed integrally with a support base or the like. Further, as described above, when communication between the radiographic imaging apparatus 1 and an external apparatus is performed via a cable such as a LAN cable, these cables are connected to the base station 54 as shown in FIG. It is also possible to configure such that information such as data D can be transmitted / received by cable communication via a cable or the base station 54.

  The base station 54 is connected to the radiation generating device 55 and the console 58, and signals for LAN communication when transmitting information between the radiographic image capturing device 1 and the console 58 are transmitted to the base station 54. Is converted into a signal for transmitting information to and from the radiation generating device 55, and a converter (not shown) that performs the reverse conversion is incorporated.

  In the present embodiment, the front room R2 is provided with an operation console 57 for the radiation generating device 55. The operation console 57 is operated by an operator such as a radiologist to transmit radiation to the radiation generating device 55. An exposure switch 56 for instructing the start of irradiation is provided. The radiation generating device 55 activates the radiation source 52 or emits radiation from the radiation source 52 when the exposure switch 56 is operated by an operator such as a radiologist and a signal is transmitted from the console 57. It is supposed to let you.

  In addition to this, the radiation generating device 55 moves the radiation source 52 to a predetermined position so that the radiation image capturing device 1 loaded in the designated bucky device 51 can be appropriately irradiated with radiation, or the radiation direction thereof. Adjusting a diaphragm (not shown) so that radiation is irradiated within a predetermined region of the radiographic imaging apparatus 1, or adjusting the radiation source 52 so that an appropriate dose of radiation is irradiated Various controls such as these are performed on the radiation source 52. In addition, you may comprise so that operators, such as a radiographer, may perform these processes manually.

  In addition, the radiation generator 55 irradiates the radiation from the radiation source 52 by, for example, stopping the X-ray tube of the radiation source 52 when a predetermined time has elapsed from the start of radiation irradiation from the radiation source 52. Is supposed to stop.

  The configuration and the like of the radiographic image capturing apparatus 1 are as described above. In the present embodiment, the radiographic image capturing apparatus 1 may be mounted and used in the bucky device 51 as described above. In other words, it can be used alone.

  That is, the radiation image capturing apparatus 1 is arranged in a single state, for example, on the upper surface side of a bed provided in the capturing room R1 or a bucky apparatus 51B for supine position capturing as shown in FIG. (See FIG. 1) The patient's hand, which is the subject, can be placed on the top, or the patient's waist, legs, etc. lying on the bed can be inserted between the bed and the bed. It has become. 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.

  On the other hand, in the present embodiment, a console 58 constituted by a computer or the like is provided outside the photographing room R1 and the front room R2. The console 58 is provided with a display unit 58a configured with a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like. In addition, the console 58 is connected to or includes a storage means 59 composed of an HDD (Hard Disk Drive) or the like.

  It is also possible to configure the console 58 so as to be provided, for example, in the front chamber R2. Further, for example, the console 58 has a function of changing the state of the radiographic imaging device 1 between a wake-up state and a sleep state, or an operator such as a radiographer takes an image. It may be configured to have a function that enables creation or selection of imaging order information representing the contents of radiographic imaging performed in the room R1, and the configuration is appropriately configured.

[Reading process of image data and leak data in radiation imaging apparatus]
Next, an image data reading process for reading image data d from each radiation detection element 7 in the radiation image capturing apparatus 1, a leak data reading process that is alternately performed with the image data reading process, and radiation irradiation to the radiation image capturing apparatus 1. A detection process such as a start will be described.

  In the following, a case where the leak data reading process is performed immediately after the image data reading process will be described. However, as can be understood from the following description, the leak data reading process is performed immediately before the image data reading process. It is also possible to obtain the same effect as that performed immediately after the image data reading process.

  In the present embodiment, the control means 22 is configured to press the power switch 36 (see FIG. 1) of the radiographic image capturing apparatus 1 before the radiographic image capture, or to change the radiographic image capture apparatus 1 to the awake state, When a signal for starting the image data reading process or the leak data reading process is received from the console 58, a trigger signal for starting the image data reading process or the like is transmitted to the scanning drive unit 15 at that time. It is like that.

  As described above, when the scanning drive unit 15 receives the trigger signal from the control unit 22, as shown in FIG. 9, FIG. 15C, and FIG. The on-voltage is sequentially applied to the lines L1 to Lx of the scanning line 5 while switching the lines L1 to Lx of the scanning line 5 to which the voltage is applied.

  Then, as shown in FIGS. 15A to 15D, the control unit 22 is connected to each line L1 of the scanning line 5 when an ON voltage is applied to the line L1 of the scanning line, for example. Image data read processing for reading image data d from the radiation detection element 7 is performed.

  That is, as described above, the control means 22 transmits the first pulse signal Sp1 to each correlated double sampling circuit 19 after turning off the charge reset switch 18c of the amplifier circuit 18 of each readout circuit 17. Thus, the voltage value Vin output from the amplifier circuit 18 at that time is held.

  Subsequently, after the on-voltage is applied to the line L1 of the scanning line 5, the second pulse signal Sp2 is transmitted to each correlated double sampling circuit 19 at the time of switching to the off-voltage, and at that time, the amplifier circuit The voltage value Vfi output from 18 is held. Then, in order to reset the capacitor 18b, the charge reset switch 18c is turned on.

  Each correlated double sampling circuit 19 outputs the calculated voltage value difference Vfi−Vin as analog value image data d, which is sequentially converted to digital value image data d by the A / D converter 20 and stored. The data is output to the means 40 and stored sequentially.

  When the control means 22 finishes the image data reading process from each radiation detection element 7 connected to the line L1 of the scanning line 5, as shown in FIGS. 15A to 15D, the control means 22 continues immediately thereafter. In addition, a leak data read process is performed in which the total value of the charges leaking from all the radiation detection elements 7 connected to the signal lines 6 at that time is read as leak data Dleak for each signal line 6. It has become.

  As shown in FIGS. 15C and 15D, the control unit 22 performs the leak data reading process in a state where the on-voltage is not applied to the lines L1 to Lx of the scanning line 5, that is, the scanning line 5 This is performed in a state where an off voltage is applied to each of the lines L1 to Lx.

  Then, as described above, the control means 22 transmits the first pulse signal Sp1 to each correlated double sampling circuit 19 after turning off the charge reset switch 18c of the amplifier circuit 18 of each readout circuit 17. Thus, the voltage value Vin output from the amplifier circuit 18 at that time is held.

  Subsequently, after a predetermined time has elapsed, the second pulse signal Sp2 is transmitted to each correlated double sampling circuit 19, and the voltage value Vfi output from the amplifier circuit 18 at that time is held. Then, in order to reset the charge reset switch 18c, the charge reset switch 18c is turned off.

  From each correlated double sampling circuit 19, the calculated voltage value difference Vfi−Vin is output as analog value leak data Dleak, which is sequentially converted to digital value leak data Dleak by the A / D converter 20 and stored. The data is output to the means 40 and stored sequentially. At this time, the control means 22 stores the leak data Dleak read as described above in association with the image data d read immediately before.

  In this way, the control means 22 applies an on-voltage from the scanning drive means 15 to each of the lines L1 to Lx of the scanning line 5 and reads out each image data d from each radiation detection element 7, and scanning. In a state where no on-voltage is applied to each of the lines L1 to Lx of the line 5, that is, in a state where an off-voltage is applied, a leak data reading process for reading the leak data Dleak for each signal line 6 is alternately performed, and this process is performed for each frame. It is designed to be repeated.

  In the present embodiment, at least the image data reading process for reading the image data d from each radiation detection element 7 is performed at each stage before radiation is irradiated from the radiation source 52 to the radiation image capturing apparatus 1. Although it also serves as a reset process for discharging excess charges from the element 7, for example, before starting the reading process of the image data d and the leak data Dleak from each radiation detection element 7, the reset of each radiation detection element 7 is performed. As described above, the processing may be performed separately.

  In the present embodiment, the image data reading process and the leak data reading process performed alternately are started before the radiation image capturing apparatus 1 is irradiated with radiation. Therefore, in the image data reading process of each frame immediately after each reading process is started, dark charges generated in each radiation detecting element 7 not irradiated with radiation are read as image data d.

The image data d corresponding to these dark charges is the image data d read after the radiation imaging apparatus 1 is irradiated with the radiation, that is, the true image data d caused by the charges generated in the radiation detecting element 7 by the radiation irradiation. ^* it can be a is subtracted from the image data d including by using as an offset correction value O for calculating a ^* true image data d.

  Therefore, in this embodiment, the control means 22 discards each image data d read from each radiation detection element 7 for each frame immediately after the start of the reading process of the image data d and the like as extra image data d. Instead, the offset correction value O is stored in the storage means 40 for each frame.

  However, it is not necessary to store all the offset correction values O for each frame after the start of the reading process of the image data d and the like from each radiation detection element 7. There are also restrictions such as the storage capacity of the storage means 40. Therefore, in the present embodiment, the number of frames in which the image data d and the leak data Dleak are stored in the storage unit 40 is set in advance.

  And the control means 22 repeats each read-out process of the image data d and the leak data Dleak from each radiation detection element 7 as mentioned above, and each radiation detection element 7 for the frame of the preset number of frames is carried out. When the image data d (in this case, the offset correction value O) and the leak data Dleak are stored in the storage means 40, the image data d and leak data Dleak of each subsequent frame are firstly image data d and leak data. In order from the frame storing the Dleak, the image data d and the leak data Dleak of the past frame are sequentially overwritten and stored.

[Detection of radiation start, etc.]
On the other hand, the control means 22 reads out the image data d from each radiation detection element 7 as described above and saves it in the storage means 40, and at the same time, at least radiographic imaging based on the value of the read image data d. The start of radiation irradiation to the device 1 is detected.

  It is assumed that, during the image data reading process and the leak data reading process alternately performed as described above, radiation is irradiated at the timing shown in FIG. 16, for example, in the m-th frame.

  In FIG. 16, the hatched period represents the period during which radiation was applied. Further, the on-voltage is sequentially applied to each of the lines La to Lb of the scanning line 5 shown in FIG. 16 while, for example, the scanning line 5 of the hatched portion ΔT shown in FIG. This corresponds to each line of the scanning line 5. Further, in FIG. 16, illustration of the on / off timing of the charge reset switch 18c, the transmission timing of the pulse signals Sp1 and Sp2, and the like are omitted.

  In the case as shown in FIG. 16, in the m-th frame, the ON voltage is applied to the lines L1 to La-1 of the scanning line 5 and the lines L1 to La-1 of the scanning line 5 are connected. The image data d read from each radiation detection element 7 is data resulting from dark charges read before the radiation is irradiated. For this reason, the image data d has a small value as the value of the image data d itself, as in the case of a frame before the m-1th frame (not shown) (that is, when the image data d is the offset correction value O). Become.

  On the other hand, as shown in FIG. 16, at least the lines La to Lb of the scanning line 5 of the m-th frame are subjected to image data reading processing after irradiation with radiation, so the lines La to Lb of the scanning line 5 are scanned. From each connected radiation detection element 7, image data d having a larger value that is clearly different from the data resulting from dark charges is read out.

  Therefore, for example, the value of the individual image data d read from each radiation detection element 7 by the reading circuit 17 as described above is monitored by the control means 22, and the read image data d is set in advance, for example. It may be configured to determine that radiation irradiation has started when the threshold value is exceeded.

  Further, in such a configuration, when there is an abnormal radiation detecting element 7 that outputs large image data d even though no radiation is irradiated, fluctuations occurring in the image data d happen to be large values. In such a case, there is a risk that it may be determined that radiation irradiation has been started by mistake.

  Therefore, for example, the integrated value Σd (n) of each image data d read from each radiation detection element 7 connected to the line Ln of the scanning line 5 read by the readout circuit 17 as described above. Is calculated for each line Ln of the scanning line 5, and radiation irradiation starts when the integrated value Σd (n) of each data D for each line Ln of the scanning line 5 exceeds, for example, a preset threshold value. It can be configured to determine that it has been performed.

  Further, a total value Σd (m) of the image data d read from all the radiation detection elements 7 arrayed two-dimensionally on the detection unit P is calculated for each frame, and each image data for each frame is calculated. For example, it may be determined that radiation irradiation has started when the total value Σd (m) of d exceeds a preset threshold value.

  In the above case, although the integrated value and the total value are different in the range to be integrated (summed), it means the total sum of each data D and have the same meaning content. In other words, the value Σd (n) and the total value Σd (m).

  In the present embodiment, the control unit 22 determines whether the individual image data d read out or the scanning line 5 is read when each of the above conditions is satisfied in the set determination process, that is, in each of the above standards. When the integrated value Σd (n) of each image data d for each line Ln or the total value Σd (m) of each image data d for each frame exceeds a threshold value, it is determined that radiation irradiation has started. It is like that.

  Accordingly, the control unit 22 does not determine that the irradiation has started since the above condition is not satisfied in any of the determination processes in the (m-1) th frame not illustrated in FIG. In the frame, since the above condition is satisfied in any of the determination processes, it is determined that radiation irradiation has started.

  The threshold value in each determination process may be set in advance as described above. For example, an image data read process for reading image data d from each radiation detection element 7 is started. In the initial stage (that is, when it is certain that the radiation image capturing apparatus 1 is not irradiated with radiation), the image data d (in this case, the offset correction value O) from each radiation detection element 7 and each image data d The integrated value Σd (n) and the total value Σd (m) are acquired, or the image data d, the integrated value Σd (n), and the total value Σd (m) for several frames are acquired and their average values are obtained. It is also possible to configure such that a threshold value is set for each radiographic image capturing by calculating and adding a predetermined value to these values.

  Further, for example, when storing the image data d read from each radiation detection element 7 in the storage means 40, the image data d is voted for a histogram (not shown), and the radiation image is based on the frequency distribution of the histogram. It can also be configured to determine whether or not the radiation of the imaging apparatus 1 has been started.

  That is, in the frame before the start of radiation irradiation, image data d having a small value due to dark charges is read from each radiation detection element 7, and therefore corresponds to image data d having a small value on the histogram. Although the frequency of the class is increased, in a frame in which irradiation of radiation is started, data resulting from charges generated by irradiation of radiation is added to image data d from each radiation detection element 7 and an image having a relatively large value is added. Since the data d is read, the frequency of the class corresponding to the image data d having a large value increases on the histogram.

  Therefore, for example, the frequency of the class in the range corresponding to the large image data d on the histogram is monitored, and when the total value of the frequency in the range exceeds the threshold, it is determined that radiation irradiation has started from the frame. It is also possible to configure as described above.

  In this case as well, as described above, there are abnormal radiation detection elements 7 that output large image data d even though no radiation is irradiated, and fluctuations that occur in the image data d happen to be large values. In some cases, the frequency of the class in the above range corresponding to the large image data d on the histogram may not become zero even in the frame before the start of radiation irradiation.

  Therefore, in this case as well, a value other than 0 may be set in advance as the threshold value. For example, an initial stage in which the reading process of the image data d from each radiation detection element 7 is started. The frequency (or average value of frequencies for several frames) in the above-mentioned range obtained when each image data d is voted on the histogram in one frame (or several frames) is calculated, and the frequency (or average value) is calculated. It is also possible to configure so that the threshold value is set for each radiographic image capture, for example, by setting a value obtained by adding a predetermined value to () to be added as a threshold value.

  In this embodiment, as shown in FIG. 16, for example, when the control unit 22 determines that radiation irradiation has started in the m-th frame, the control unit 22 stores the frame number m of the frame in the CPU memory or the like. It has become.

  On the other hand, in the same manner as the determination of the start of radiation irradiation, for example, the read individual image data d, the integrated value Σd (n) of each image data d for each line Ln of the scanning line 5, or each frame When the total value Σd (m) of each image data d is less than or equal to the threshold value set as described above, it is possible to determine that the irradiation of radiation has ended.

  In this case, the predetermined number of frames for acquiring the image data d and the leak data Dleak for each frame is a frame (in the above example, which has been subjected to image data reading processing or the like when the start of radiation irradiation is detected). The frames from the mth frame) to the frame in which the end of radiation irradiation is detected or the predetermined frame thereafter.

  Also, for example, how many frames of image data read processing or the like are performed in advance from a frame (m-th frame in the above example) that has been subjected to image data read processing or the like when the start of radiation irradiation is detected. It is possible to determine that the irradiation of radiation has been completed when the image data read processing for the predetermined number of frames including the frame for which the irradiation of radiation has been determined has been completed. is there.

  In this embodiment, as described above, the control unit 22 completes, for example, image data reading processing for three frames including a frame determined to have started irradiation of radiation, that is, the m + 2th frame. When the image data read processing or the like is completed, a trigger signal is transmitted to the scanning drive unit 15 to stop application of the on-voltage from the gate driver 15b to the lines L1 to Lx of the scanning line 5, Each readout process of image data d and leak data Dleak from each radiation detection element 7 is terminated.

  In the present embodiment, the control means 22 uses the image data d and the leak data Dleak when the reading process of the image data d and the leak data Dleak from each radiation detection element 7 is completed as described above. When the processing is performed by the console 58, the image data d and the leak data Dleak for each radiation detection element 7 from the m-th frame to the m + 2-th frame are transferred to the antenna device 39 (FIG. 1). Or the like (see FIG. 7 and the like).

Further, as described above, the image data d and leak data Dleak of each frame before the m−1th time before the radiation image capturing apparatus 1 is irradiated with radiation are used to calculate true image data d ^*. Can be used to calculate the offset correction value O. Therefore, when the processing using the image data d and the leak data Dleak is performed on the console 58, the control unit 22 sets the image data d and the leak data for each radiation detection element 7 in each frame before the m-1th time. Dleak is also transmitted to the console 58 via the antenna device 39.

  Note that the image data d and the leak data Dleak read in the (m-1) th frame may be transmitted, and several frames of image data d including the (m-1) th frame are transmitted. It is also possible to configure as described above. Further, the average value of the image data d and the leak data Dleak for each of the radiation detection elements for several frames before the m-th frame where the reading process was performed at the start of radiation irradiation is calculated. The average value or the like can be transmitted.

[Calculation of true image data and generation process of radiation image]
Subsequently, the control means 22 and the console 58 of the radiation image capturing apparatus 1 obtain the true image data d ^* for each radiation detection element 7 based on the image data d and the leak data Dleak acquired as described above. The radiation image p is generated based on the calculated true image data d ^* .

Hereinafter, the calculation of the true image data d ^* and the generation process of the radiographic image p will be described, and the operation of the radiographic image capturing apparatus 1 and the radiographic image capturing system 50 according to the present embodiment will be described.

  In the following, the image data d and leak data Dleak for each radiation detection element 7 read out in the m-th frame and the like are represented as d (m), Dleak (m), and the like, respectively.

  As in the present embodiment, while the radiation image capturing apparatus 1 is irradiated with radiation, the image data d from each radiation detection element 7 is read and the image data d (m) to d (for each frame is read. When m + 2) is acquired, in normal image processing, each image data d (m) to d (m + 2) is added to calculate image data d for each radiation detection element 7 and reconstruct it. To do.

Since each image data d (m) to d (m + 2) is overlaid with an offset correction value O caused by dark charges, each radiation detection element is normally in accordance with the following equation (1). Every 7, true image data d ^* is calculated that does not include the dark charge and is caused only by the charges generated in the radiation detection element 7 by the radiation.
d ^* = (d (m) -O) + (d (m + 1) -O) + (d (m + 2) -O)
∴d ^* = d (m) + d (m + 1) + d (m + 2) −3O (1)

However, by simply adding the image data d (m) to d (m + 2) and subtracting the offset correction value O in this way, as shown in FIG. When the radiation image p is generated on the basis of the true image data d ^* for every 7, as shown in FIG. 26 (B), the scanning line 5 to which the ON voltage is sequentially applied while the radiation is irradiated is shown. line La~Lb true image data d ^* of the image region δT corresponding to (see FIG. 16), than the true image data d ^* of the image area B of the image area a and the lower side of the upper is increased End up.

In our study, the true image data d ^* is the image area A of the thus image area? T, the phenomenon that the value is larger than the true image data d ^* of B, when produced by causes such as: It is considered. In the following, the true image data d ^* for each frame is represented as d ^* (m) to d ^* (m + 2).

  For example, before the radiation image capturing apparatus 1 is irradiated with radiation or after the radiation irradiation is finished, an on-voltage is applied to a line Li where the scanning line 5 is located, and the line Li of the scanning line 5 is connected to the line Li. When the image data dj is read out from each radiation detecting element 7j, the charge Q accumulated in each radiation detecting element 7i connected to the line Li of the scanning line 5 as shown in FIG. And stored in the capacitor 18b of the amplifier circuit 18.

  At this time, the other radiation detection elements 7 connected to the signal line 6 leak a small amount of charge q through the TFTs 8 which are turned off. Each leaked charge q is also accumulated in the capacitor 18 b of the amplifier circuit 18 through the signal line 6.

  Therefore, from the amplification circuit 18, the charge Q read from the radiation detection element 7 i connected to the line Li of the scanning line 5 to which the ON voltage is applied and the other radiation detection connected to the signal line 6. A voltage value corresponding to the total value of each charge q leaked from the element 7 is output and read out as image data di of the radiation detection element 7i.

  On the other hand, while the radiation imaging apparatus 1 is irradiated with radiation, an on-voltage is applied to a line Lj with the scanning line 5, and each radiation detection element 7 j connected to the line Lj of the scanning line 5. 18, when the image data dj is read out, as shown in FIG. 18, the charge Q accumulated in each radiation detecting element 7j connected to the line Lj of the scanning line 5 is discharged to the signal line 6 and amplified. Accumulated in the capacitor 18 b of the circuit 18.

  At this time, similarly to the above, charges q leak from the other radiation detection elements 7 connected to the signal line 6 through the TFTs 8, and the leaked charges q are also The signal is accumulated in the capacitor 18 b of the amplifier circuit 18 through the signal line 6.

  However, in this case, the radiation image capturing apparatus 1 is irradiated with radiation, and each TFT 8 is also irradiated with radiation (in this embodiment, the irradiated radiation is converted into electromagnetic waves by the scintillator 3 (see FIG. 2 and the like)). As a result of this electromagnetic wave being applied to each TFT 8), current easily flows through each TFT 8, and the amount of leakage from each radiation detection element 7 increases. Therefore, the charge amount of each charge q leaked from the other radiation detection elements 7 connected to the signal line 6 increases.

  Therefore, also in this case, the voltage value corresponding to the total value of the charge Q from the radiation detection element 7j and each charge q leaked from the other radiation detection elements 7 is output from the amplification circuit 18 to the image of the radiation detection element 7j. Although read out as data dj, the amount of charge q leaked from other radiation detection elements 7 connected to the signal line 6 is larger than that shown in FIG. The image data dj of the radiation detection element 7j is increased by the total amount of.

  As described above, when radiation is applied to the radiation imaging apparatus 1 in the m-th frame, the radiation voltage is connected to the lines La to Lb of the scanning line 5 to which the on-voltage is sequentially applied while the radiation is applied. In each image data d (m) of the image area δT read from each radiation detection element 7, each radiation connected to the other lines L1 to La-1 and Lb + 1 to Lx of the scanning line 5 is obtained. More data due to the total value of the leaked charges q from the other radiation detection elements 7 than the image data d (m) of the image areas A and B read from the detection element 7 is superimposed. The

Therefore, by simply adding the image data d (m) to d (m + 2) from the mth frame to the m + 2th frame and subtracting the offset correction value O, the true value of the image region δT is obtained. the image data d ^*, since the data corresponding to the increase in the total value of each of the charge q leaked from other radiation detection element 7 of the remains, a true image data d ^* is the image area a of the image region δT , B is considered to be larger than the true image data d ^* .

  Therefore, in the present embodiment, as described above, a state in which an off voltage is applied to each of the lines L1 to Lx of the scanning line 5 immediately after (or immediately before) the image data reading process for reading the image data d from the radiation detection element 7. Thus, as shown in FIG. 19, for each signal line 6, data corresponding to the total value of the charges q leaked from all the radiation detection elements 7 connected to the signal line 6 is read out as leak data Dleak. Leak data reading processing is performed.

  In this case, since the off voltage is applied to each of the lines L1 to Lx of the scanning line 5, each TFT 8 connected to the signal line 6 is in an off state and is connected to the signal line 6. Only the charges q leaked from the radiation detecting elements 7 via the TFTs 8 are accumulated in the capacitor 18 b of the amplifier circuit 18.

  Therefore, the read leak data Dleak is data output from the amplifier circuit 18 in accordance with the total value of the charges q leaked from all the radiation detection elements 7 connected to the signal line 6. When the radiation image capturing apparatus 1 is irradiated with radiation as described above and the amount of leakage from each radiation detection element 7 via each TFT 8 increases, all radiation detection elements connected to the signal line 6 are detected. The leak data Dleak corresponding to the total value of the charges q leaking from 7 increases accordingly.

  Then, by performing the leak data read process immediately after (or immediately before) the image data read process, the total charge q leaked from the other radiation detection elements 7 connected to the signal line 6 as described above. The total value of the charges q leaked from all the radiation detection elements 7 connected to the signal line 6 in the same state as the state in which the image data d in which data corresponding to the increase in value remains is read. Can be read out as leak data Dleak.

  Therefore, by subtracting the leak data Dleak from the image data d, the data corresponding to the increase in the total value of each charge q leaked from the radiation detection element 7 remaining in the image data d is accurately obtained from the image data d. Can be removed.

  As shown in FIG. 18, the image data dj read from the line Lj of the scanning line 5 to which the on-voltage is applied while the radiation image capturing apparatus 1 is irradiated with radiation includes the above-described image data dj. As described above, the total value of the large charges q leaked from the other radiation detection elements 7 is superimposed, and by subtracting the leak data Dleak from the image data dj, the large leak data remaining in the image data dj Dleak is removed.

  However, as shown in FIG. 17, the image data di read from the line Li of the scanning line 5 to which the on-voltage is applied while no radiation is applied is also smaller, The total value of each charge q leaked from the radiation detection element 7 is superimposed. For this reason, the leak data Dleak is subtracted from the image data di read from the line Li of the scanning line 5 to which the on-voltage is applied while no radiation is being applied, so that the leak remaining in the image data di Data Dleak is accurately removed.

  As described above, in this embodiment, whether the image data reading process is performed while the radiation image capturing apparatus 1 is irradiated with radiation or whether the image data reading process is performed while the radiation is not irradiated. Regardless, for any image data d read out in the image data reading process, the leak data Dleak is subtracted from the image data d.

  In FIGS. 17 to 19, all the charges leaking from each radiation detection element 7 are expressed as q, but this does not mean that the leaking charges q have the same charge amount.

Therefore, in the present embodiment, the control means 22 and the console 58 of the radiographic imaging device 1 use the image data d (m) to d (m +) for each radiation detection element 7 acquired for each frame as described above. 2) and leak data Dleak (m) to Dleak (m + 2) read immediately after (or immediately before) and associated with the image data d (m) to d (m + 2), respectively. Based on this, the true image data d ^* for each radiation detection element 7 is calculated as follows.

  That is, as described above, the leak data Dleak (m) to Dleak (m + 2) associated with each image data d (m) to d (m + 2) of each frame is subtracted and calculated. d (m) −Dleak (m) and the like are respectively added. At this time, as described above, the offset correction value O is superimposed on each of the image data d (m) to d (m + 2). .

Therefore, as shown in the following equation (2), after each offset correction value O is subtracted from each of the image data d (m) to d (m + 2), the leak data is calculated from the calculated d (m) -O or the like. Dleak (m) to Dleak (m + 2) are subtracted. Then, the calculated (d (m) −O) −Dleak (m) is added to calculate the true image data d ^* .
d ^* = {(d (m) -O) -Dleak (m)}
+ {(D (m + 1) -O) -Dleak (m + 1)}
+ {(D (m + 2) -O) -Dleak (m + 2)} (2)

That is, the control means 22 and the console 58 of the radiation image capturing apparatus 1 eventually calculate the true image data d ^* for each radiation detection element 7 according to the following equation (3).
d ^* = (d (m) −Dleak (m))
+ (D (m + 1) -Dleak (m + 1))
+ (D (m + 2) -Dleak (m + 2))-3O (3)

In this way, for each radiation detection element 7, the leak data Dleak associated therewith is subtracted from the image data d to obtain true image data for each frame (that is, d in the above equation (3)). (m) −Dleak (m) etc.) and true image data for each frame is added for each frame to calculate true image data d ^* for each radiation detection element 7. Thus, as shown in FIG. 20, there is no difference between the true image data d ^* of the image area δT of the radiation image p and the true image data d ^* of the image areas A and B.

  For this reason, the phenomenon that the portion of the image region δT in the radiation image p becomes darker (or darker) than the image region A or the image region B does not appear, and the light and shade does not appear in the entire region of the radiation image p. Therefore, it is possible to generate a radiographic image p having no shading.

  As shown in FIG. 15 and the like, the time from the transmission of the first pulse signal Sp1 to the correlated double sampling circuit 19 from the control means 22 to the transmission of the second pulse signal Sp2 in the leak data reading process The interval, that is, the time interval between the two holding operations of the voltage value performed by the correlated double sampling circuit 19 is set to a time interval different from the time interval in the image data reading process for reading the image data d. In this case, the leak data Dleak read by the leak data read process is not equivalent to the leak from each radiation detection element 7 included in the image data d read by the image read process.

  Therefore, even if the leak data Dleak (m) associated with the image data d (m) is simply subtracted from the image data d (m), the true image data for each frame cannot be obtained. The leak data Dleak (m) read out in the data read process is converted into a value when the time interval in the leak data read process is set as the time interval in the image data read process, and the image data d (m) etc. The converted leak data Dleak (m) is subtracted.

  As described above, according to the radiographic image capturing apparatus 1 and the radiographic image capturing system 50 according to the present embodiment, an on-voltage (data reading voltage) is sequentially applied to the lines L1 to Lx of the scanning line 5 to generate an image. A data read process is performed to read out and acquire image data d from each radiation detection element 7, and a leak data read process is performed in a state where no on-voltage is applied to all the lines L 1 to Lx of the scanning line 5, and each signal line. 6, the total value of the charges q leaked from all the radiation detection elements 7 connected to 6 is read and acquired as leak data Dleak for each signal line 6.

As described above, since not only the image data reading process for reading the image data d but also the leak data reading process for reading the leak data Dleak is performed, other image data d acquired in the image data reading process includes The leak from the radiation detection element 7 can be acquired as the leak data Dleak by the leak data reading process. If the leak data Dleak is subtracted from the image data d, the leak from the other radiation detection elements 7 can be obtained. It is possible to obtain true image data d ^* not included.

Therefore, by generating the radiation image p using the true image data d ^* that does not include the leak from the other radiation detection elements 7, it is possible to generate the radiation image p without shading, and the radiation image It becomes possible to make p very easy to see.

Note that, as described above, the offset correction value O is the image data d read out in the image data reading process of each frame before the m−1th time before the radiation image capturing apparatus 1 is irradiated with radiation. To be precise, the offset correction value O includes a leak from other radiation detection elements 7. Therefore, when the offset correction value O is, for example, the image data d (m−1) obtained in the m−1th frame, the offset correction value O is accurately
O = d (m-1) -Dleak (m-1) (4)
Should be calculated as

  Therefore, as shown in the above equation (4), the data is read out by the leak data reading process from the image data d read out by the image data reading process in each frame before the radiation image capturing apparatus 1 is irradiated with radiation. The offset correction value O can be calculated based on the value obtained by subtracting the leak data Dleak.

  However, the image data d read out in each frame before the radiation image capturing apparatus 1 is irradiated with radiation is image data resulting from dark charges accumulated in each radiation detecting element 7 and is irradiated with radiation. In this case, the value is smaller than the image data resulting from the charge generated and accumulated in each radiation detection element 7. Further, the amount of dark charges accumulated in each radiation detection element 7 having such a small value leaks to the signal line 6 through the TFT 8 in the off state is very small and can be ignored.

Therefore, as in the present embodiment (see the above formulas (2) and (3)), the offset correction value O is not corrected by the leak data Dleak, and is subtracted from the image data d or the like without changing the offset correction value O. It is possible to configure. Also, with this configuration, it is possible to more easily perform arithmetic processing for calculating the true image data d ^* .

  In the present embodiment, the leak data read process is performed immediately before or after the image data read process, and the image data read process and the leak data read process are alternately performed. For example, as shown in FIG. In addition, the image data read process and the leak data read process are performed at a rate of performing the leak data read process once after the image data read process is performed a preset number of times twice or more. It can also be configured to repeat every frame.

  With this configuration, it is possible to reduce the time required for image data read processing and leak data read processing for each frame.

  FIG. 21 shows the case where the leak data read process is performed once after the image data read process is performed twice, but one time after the image data read process is performed three times or more. It is also possible to set the ratio of performing leak data reading processing.

  In addition, when the leak data read processing is configured to perform the image data read processing and the leak data read processing at a rate of performing once after performing the image data read processing a preset number of times more than twice. For example, the leak data Dleak acquired by the leak data reading process is associated with each image data d read by the image data reading process performed twice or more immediately before that.

In the image processing by the control means 22 and the console 58, the leak data Dleak associated therewith is subtracted from each image data d to calculate the true image data d ^* .

  On the other hand, in the present embodiment, as shown in FIG. 7, the off voltage supplied from one power supply circuit 15 a of the scan driving unit 15 is branched by the gate driver 15 b and applied to the lines L1 to Lx of the scan line 5. Is done. For this reason, the off voltage supplied from the power supply circuit 15a is fluctuated in time, but the fluctuation is also branched by the gate driver 15b and simultaneously with the off voltage applied to the lines L1 to Lx of the scanning line 5. Arise.

  Therefore, the off voltage applied to all the TFTs 8 on the detection part P connected to the lines L1 to Lx of the scanning line 5 slightly increases or decreases simultaneously in all the TFTs 8.

  When the off voltage applied to the gate electrode 8g of the TFT 8 increases, the charge in the radiation detection element 7 easily leaks, and when the off voltage decreases, the charge in the radiation detection element 7 hardly leaks. Therefore, at the moment when the off-voltage supplied from the power supply circuit 15a becomes slightly high due to fluctuation, the amount of leakage from each radiation detection element 7 increases all at once, and the off-voltage supplied from the power supply circuit 15a At the moment when it becomes slightly low, a phenomenon occurs in which the amount of leakage from each radiation detection element 7 decreases simultaneously.

  Therefore, in the case of the present embodiment shown in FIG. 15 or the modification shown in FIG. 21, the amount of charge accumulated in each radiation detection element 7 and the radiation irradiated to the radiation imaging apparatus 1 Even if the dose is the same for each leak data reading process, the off-voltage applied to each TFT 8 is slightly different for each leak data reading process due to the fluctuation as described above. For this reason, a phenomenon occurs in which the leak data Dleak read for each leak data read process does not have the same value.

  Therefore, in order to eliminate the influence of fluctuations generated in the off voltage applied to the TFT 8 from the leak data Dleak, for example, it is possible to use an average value Dleak_ave of a plurality of leak data Dleak as the leak data Dleak. It is.

  For example, when the image data d is read from each radiation detection element 7 connected to the line L2 of the scanning line 5 shown in FIG. 15, it is acquired by two leak data reading processes performed before and after the image data reading process. It is possible to calculate the average value Dleak_ave of the two leaked data Dleak and subtract the average value Dleak_ave of the two leaked data Dleak thus calculated from the image data d.

  Note that the plurality of leak data Dleak for which the average value Dleak_ave is calculated is not limited to the two leak data Dleak as in this case, but an average number Dleak_ave is calculated for an appropriate number of leak data Dleak. It can be configured to be used as a target.

With this configuration, the leak data Dleak to be subtracted from the image data d (that is, the average value Dleak_ave of the plurality of leak data Dleak) can be further reduced in the influence of fluctuations generated in the off-voltage, Also from the true image data d ^* calculated using this, it is possible to more accurately eliminate the influence of fluctuations occurring in the off-voltage.

  Further, as described above, in the present embodiment, as shown in FIGS. 11B, 13B, and 15, in the leak data read processing, the control means 22 adds 1 to the correlated double sampling circuit 19. The time interval from the transmission of the second pulse signal Sp1 to the transmission of the second pulse signal Sp2, that is, the time interval between two holding operations of the voltage value performed by the correlated double sampling circuit 19 (FIG. 13). (See (B)) can be varied at a time interval different from the time interval (see FIG. 11B) at the time of the image data reading process for reading the image data d.

  In the examples shown in FIG. 13B and FIG. 15, the time interval between two holding operations of the voltage value in the correlated double sampling circuit 19 in the leak data reading process is shown in FIG. In the image data reading process, the case where the correlated double sampling circuit 19 is changed to be shorter than the time interval between two holding operations of the voltage value is shown.

  As shown in FIGS. 13B and 15, in the leak data reading process, it is not necessary to turn on / off the TFT 8, so the voltage value in the correlated double sampling circuit 19 in the leak data reading process is twice. The time interval between the holding operations can be made shorter than the time interval in the image data reading process.

  When the time interval in the leak data reading process is shortened in this way, the timing for acquiring the image data d (that is, the timing for transmitting the second pulse signal in the image data reading process) and the timing for acquiring the leak data Dleak (That is, the timing at which the second pulse signal is transmitted in the leak data reading process) can be made closer.

The leak data Dleak read in the leak read process is read out in the image data read process performed immediately before or immediately after the timing of acquiring the image data d and the timing of acquiring the leak data Dleak. Thus, it becomes closer to the total value of the charges q leaked from the radiation detection elements 7 superimposed on the image data d, and the true image data d ^* can be accurately calculated.

  However, the time interval between the two holding operations of the voltage value in the correlated double sampling circuit 19 in the leak data reading process can be changed to be the same as or longer than the time interval in the image data reading process. .

  The time interval between the two holding operations of the voltage value in the correlated double sampling circuit 19 in the leak data reading process is that the timing at which the image data d is acquired and the timing at which the leak data Dleak is acquired as described above. In addition to the viewpoint, the ratio is set in consideration of the ratio of the leak data Dleak read in the leak data read process and the noise superimposed thereon, that is, the S / N ratio.

  That is, when the noise is small, in order to shorten the time required for the image data reading process and the leak data reading process for each frame, the voltage value of the correlated double sampling circuit 19 in the leak data reading process is set twice. It is desirable to vary the time interval between holding operations so as to be short.

  Further, when noise is large, the S / N ratio is improved by making the time interval between two holding operations of the voltage value in the correlated double sampling circuit 19 in the leak data reading process longer. Therefore, it is desirable to vary the time interval so that it becomes longer.

  On the other hand, if the time interval in the leak data reading process is shorter than the time interval in the image data reading process, the leak data Dleak read in the leak data reading process is included in the image data d read in the image reading process. The leak data Dleak read by the leak data read process is included in the image data d read by the image read process when the time interval is made longer than the leak amount from each radiation detection element 7 to be read. Therefore, the subtraction process cannot be simply performed.

  Therefore, in any case, the leak data Dleak read in the leak data read processing is converted into a value when the time interval in the leak data read processing is set as the time interval in the image data read processing, and each image data d Thus, the converted leak data Dleak is configured to be subtracted.

  By the way, when radiation is irradiated in the radiation detecting element 7 (or when the irradiated radiation is converted into an electromagnetic wave by the scintillator 3 as in the present embodiment, the electromagnetic wave is irradiated to the radiation detecting element 7. In some cases, there is a radiation detection element 7 from which abnormally large image data d is read out during the image data reading process regardless of whether or not radiation is irradiated.

The image data d read out from the radiation detecting element 7 by the image data reading process cannot be used to calculate the true image data d ^{* in} the first place, but is connected to the same signal line 6 as well. The calculation of the true image data d ^* of each radiation detection element 7 in the portion of the image region δT that is present may be affected.

That is, as shown in FIG. 22, if radiation detection elements E and F from which abnormal image data d is read are present on the detection unit P, the radiation detection elements E and F themselves are abnormal pixels (also referred to as defective pixels). ), The image data d read from the radiation detection elements E and F and the true image data d ^* calculated from the image data d are not adopted, and the radiation detection element E and the radiation detection element F are used. each radiation detection element 7 known technique the radiation detecting element E using the linear interpolation or the like, for example, based on the calculated true image data d ^* for respectively adjacent, ^* true image data d is interpolated for F The

  However, when the radiation image capturing apparatus 1 is irradiated with radiation, as described above, each TFT 8 is also irradiated with radiation (in this embodiment, the irradiated radiation is converted into electromagnetic waves by the scintillator 3, By irradiating each TFT 8 with an electromagnetic wave), a current easily flows in each TFT 8 and the amount of leakage from each radiation detection element 7 increases.

  An abnormally large charge leaks to the signal line 6 through the TFT 8 from the radiation detection elements E and F from which the abnormal image data d is read. When the TFT 8 is not irradiated with radiation or electromagnetic waves (that is, when the radiation imaging apparatus 1 is not irradiated with radiation), the leakage amount from the radiation detection elements E and F from which abnormal image data d is read is usually other than As in the case of the normal radiation detection element 7, the value becomes very small.

For this reason, the amount of leak that is superimposed on the image data d of the normal radiation detection element 7 that has been subjected to the image data read-out process when the radiation image capturing apparatus 1 is not irradiated with radiation, that is, leak data that is performed immediately after that. The leak data Dleak read in the read process can be regarded as a normal value, and the true image data is obtained by subtracting the leak data Dleak associated therewith from the image data d as in the present embodiment. d ^* can be calculated normally.

  However, among the normal radiation detection elements 7 that have been subjected to the image data reading process when the radiation image capturing apparatus 1 is irradiated with radiation, the same signal lines 6 as the abnormal radiation detection elements E and F (in FIG. 22). In FIG. 5, the normal radiation detection element 7 connected to the vertical direction of the figure (that is, the normal radiation detection element 7 in the image region δT portion indicated by hatching in the figure). ), The radiation detection element E from which the abnormal image data d is read as described above into the leak data superimposed on the image data d, that is, the leak data Dleak read in the leak data reading process performed immediately thereafter, Abnormally large data due to an abnormally large charge leaking from F is included.

Therefore, both the image data d read from the normal radiation detection element 7 in the image region δT and the leak data Dleak have an abnormally large value. Therefore, the original true image data d ^* is buried in the fluctuation of the value generated in the leak data Dleak having an abnormally large value, or the charge corresponding to the image data d and the charge corresponding to the leak data Dleak. Both exceed the saturation charge amount of the amplifier circuit 18, and both the image data d and the leak data Dleak become the maximum values (for example, 2 ¹⁶ ) that the amplifier circuit 18 can output ^. The true image data d ^* cannot be normally calculated, for example, because the value becomes 0.

On the other hand, when the radiation image capturing apparatus 1 is directly irradiated with strong radiation without passing through the subject, even if each radiation detection element 7 is normal, the image data d read out from those radiation detection elements 7 The value of itself may be the maximum value that can be output by the amplifier circuit 18, and even if the value of the image data d itself is seen, an abnormality caused by an abnormally large charge leaked from the abnormal radiation detection elements E and F It is difficult to determine whether or not the image data d contains a large amount of data, or to determine whether or not the calculated true image data d ^* can be adopted.

Therefore, it is possible to make a determination based on the value of the leak data Dleak. That is, when the value of the leak data Dleak acquired in association with the image data d of the radiation detection element 7 is larger than a preset threshold value, the leak detection element 7 leaks from the image data d. data Dleak the without employing the true image data d ^* which is calculated by subtracting, or the first place for the radiation detection element 7 can be configured so as not to calculate the ^* true image data d .

Further, when information such as the position on the detection unit P of the radiation detection element 7 from which the abnormal image data d is read is known in advance, the true image data d ^* is used by using such information. It can also be configured to determine whether or not to do so.

In the above case, as shown by hatching in FIG. 22, at least the radiation detection elements E and F from which abnormal image data d are read out are connected to the image region δT portion of the signal line 6 connected. In each of the radiation detecting elements 7 as described above, since at least the leak data Dleak has an abnormal value, the calculated true image data d ^* is not adopted or the true image data d ^* is not calculated. .

For this reason, the radiation detection elements 7 for which normal true image data d ^* cannot be calculated are arranged in a line along the signal line 6 and a so-called line defect occurs. Therefore, in such a case, for example, a known method such as linear interpolation is used based on the true image data d ^* calculated for each radiation detection element 7 adjacent to the left and right of the radiation detection elements 7. The true image data d ^* for these radiation detection elements 7 is interpolated and calculated.

Then, as described above, based on the value of the leak data dleak, whether to adopt the calculated true image data d ^*, or whether to perform determination perform true image data d ^* calculation of For example, even if the radiation detection element 7 that has not been previously recognized as the abnormal radiation detection element 7 becomes a new abnormal radiation detection element, abnormal leak data can be obtained. It is possible to accurately grasp the occurrence of Dleak.

Then, the true true image data d ^* calculated based on the abnormal leak data Dleak is accurately eliminated, and the true true image data d ^* is interpolated with the normal true image data d ^* . Normalization can be achieved, and the radiation image p can be made very easy to see by generating the radiation image p using the true image data d ^* .

DESCRIPTION OF SYMBOLS 1 Radiographic imaging apparatus 5, L1-Lx Scan line 6 Signal line 7 Radiation detection element 8 TFT (switch means)
15 Scanning drive means 17 Reading circuit 18 Amplifying circuit 19 Correlated double sampling circuit 22 Control means 39 Antenna device (communication means)
50 Radiation imaging system 58 Console D data d Image data d ^* True image data Dleak Leak data Dleak (m) to Dleak (m + 2) Leak data for each frame d (m) to d (m + 2) For each frame Image data P detector Q, q charge r region Vfi-Vin difference Vin, Vfi voltage value ΣD (m) total value ΣD (n) integrated value

Claims (13)

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:
Scanning drive means for applying the data reading voltage while sequentially switching the scanning lines when reading data from the radiation detecting element;
A switch element connected to each of the scanning lines, and discharging the charge accumulated in the radiation detection element to the signal line when the voltage for reading data is applied;
A readout circuit that converts the charge read from the radiation detection element into the data;
Control means for controlling at least the scanning drive means and the readout circuit to perform a readout process of the data from the radiation detection element;
With
When the period for reading the data from all the radiation detection elements on the detection unit is one frame,
The control means includes
An image data read process for reading the data as image data from the radiation detection element connected to the scan line by applying a voltage for reading the data to the scan line from the scan driving means, and for each scan line Leak data read processing for reading out the total value of each charge leaked from all the radiation detection elements connected to the signal line without applying the data read voltage as leak data for each signal line And repeatedly for each frame,
Detecting at least the start of radiation irradiation based on the value of the image data read in the image data reading process;
In each of a predetermined number of frames including the frame that has been subjected to the image data reading process at the time of detecting the start of radiation irradiation, the image data and the leak data for each frame are stored for each radiation detection element. A radiographic imaging apparatus characterized by acquiring the radiation image capturing apparatus.   The radiographic imaging apparatus according to claim 1, wherein the control unit repeatedly performs a process of alternately performing the image data reading process and the leak data reading process for each frame.   The control means performs the leak data read processing and the leak data at a rate of performing the leak data read processing once after performing the image data read processing a preset number of times twice or more. The radiographic image capturing apparatus according to claim 1, wherein a readout process is performed and the process is repeated for each frame. The readout circuit is
An amplifying circuit for converting the charge or the total value of the leaked charges into a voltage value;
The voltage value output from the amplifier circuit is held before the charge or the total value of the leaked charges flows into the amplifier circuit, and the charge or the total value of the leaked charges flows into the amplifier circuit. A correlated double sampling circuit that holds the voltage value output by the amplifier circuit and outputs the difference between the former voltage value and the latter voltage value as the image data or the leak data;
With
In the correlated double sampling circuit, a time interval between the two holding operations in the leak data reading process is a time interval between the two holding operations in the image data reading process. The radiographic imaging apparatus according to any one of claims 1 to 3, wherein the radiographic imaging apparatus is controlled so as to have different time intervals.   In the correlated double sampling circuit, a time interval between the two holding operations in the leak data reading process is shorter than a time interval between the two holding operations in the image data reading process. The radiographic image capturing apparatus according to claim 4, wherein the radiographic image capturing apparatus is variable as follows.   The said control means detects the start of radiation irradiation based on the total value of the said image data read from all the said radiation detection elements on the said detection part for every said flame | frame. The radiographic imaging apparatus as described in any one of Claims 1-5.   The control means detects the start of radiation irradiation based on an integrated value of the image data read from each radiation detection element connected to each scanning line. The radiographic imaging apparatus as described in any one of Claims 5-6.   The control means calculates the true image data for each frame by subtracting the leak data from the image data for each radiation detection element, and calculates the true image data for each frame. The radiographic imaging apparatus according to any one of claims 1 to 7, wherein true image data for each of the radiation detection elements is calculated by adding a number corresponding to each frame.   The radiographic image capturing apparatus according to claim 8, wherein the control unit uses an average value of a plurality of the leak data as the leak data to be subtracted from the image data.   When the value of the leak data acquired for the radiation detection element is greater than or equal to a preset threshold value, the control means subtracts the leak data from the image data for the radiation detection element. The true image data calculated is not adopted, or the true image data is not calculated for the radiation detection element, and the radiation detection element adjacent to the radiation detection element on the detection unit 10. The radiographic image capturing apparatus according to claim 8, wherein true image data for the radiation detection element is calculated using true image data. The radiographic imaging device according to any one of claims 1 to 7, comprising a communication unit;
When the image data and the leak data are transmitted from the radiographic imaging device, the leak data is subtracted from the image data for each radiation detection element to obtain true image data for each frame. Calculating, adding true image data for each frame by the predetermined number of frames, and calculating true image data for each radiation detection element;
A radiographic imaging system comprising:   The radiographic imaging system according to claim 11, wherein the console uses an average value of the plurality of leak data as the leak data to be subtracted from the image data.   When the value of the leak data acquired for the radiation detection element is greater than or equal to a preset threshold value, the console calculates the radiation detection element by subtracting the leak data from the image data. The true image data is not adopted or the true image data is not calculated for the radiation detection element, and the radiation adjacent to the radiation detection element on the detection unit of the radiation image capturing apparatus is used. The radiographic image capturing system according to claim 11, wherein the true image data for the radiation detection element is calculated using the true image data for the detection element.

Images