JP5589715B2 - Radiation imaging equipment - Google Patents

Description

  The present invention relates to a radiographic image capturing apparatus, and more particularly to a radiographic image capturing apparatus capable of performing radiographic image capturing by detecting radiation irradiation by itself.

  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. A so-called indirect radiographic imaging device that converts an electromagnetic wave having a wavelength and then generates a charge in a photoelectric conversion element such as a photodiode according to the energy of the converted electromagnetic wave and converts it to an electrical signal (ie, image data). Have been developed. 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 image capturing apparatus in which an element or the like is stored in a housing and made portable is 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 FIG. 7 and the like to be described later, normally, a plurality of radiation detection elements 7 are arranged in a two-dimensional form (matrix) on the detection unit P, and each radiation detection element 7 is connected to switch means formed by thin film transistors (hereinafter referred to as TFTs) 8. Then, an ON voltage or an OFF voltage is applied to each scanning line 5 from the gate driver 15b of the scanning driving means 15, and each TFT 8 is turned on / off, and charge accumulation in each radiation detection element 7 is performed. Release of charges from each radiation detection element 7 to each signal line 6 is performed.

  Conventional radiographic imaging is configured to perform imaging while exchanging signals and information between the radiographic imaging apparatus and the radiation generation apparatus, that is, both cooperate. Hereinafter, a method for performing radiographic imaging in cooperation while exchanging signals and information between the radiographic imaging device and the radiation generation device in this way is referred to as a cooperative method.

  Specifically, in the cooperation method, normally, as shown in FIG. 35, the radiographic image capturing apparatus first performs the lines L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning driving unit 15 before the irradiation of radiation. A reset process for sequentially applying an on-voltage to discharge the charge remaining in each radiation detection element 7 is repeatedly performed. Then, as shown in FIG. 36, when the radiation generator is ready to irradiate radiation by an operation of a radiologist or the like, a signal to irradiate the radiation imaging apparatus before irradiating the radiation. An irradiation start signal is transmitted.

  When receiving the irradiation start signal from the radiation generating apparatus, the radiographic imaging apparatus stops the reset process of each radiation detection element 7 when the reset process Rm for one surface of the detection unit P performed at that time ends. Then, an off voltage is applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5 to shift to the charge accumulation state. And after the preparation which receives irradiation of a radiation is completed in this way, an interlock release signal is transmitted to a radiation generator. When receiving the interlock release signal from the radiation image capturing apparatus, the radiation generating apparatus irradiates the radiation image capturing apparatus with radiation.

  Then, in the radiographic imaging device, as shown in FIG. 37, when radiation irradiation from the radiation generating device is completed, an on-voltage is sequentially applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5, and an image is obtained. Data D is read out.

  In FIG. 37, the irradiation period of the radiation is indicated by hatching. In FIG. 37, the gate period (that is, the period from when an on-voltage is applied to one scanning line 5 to when the on-voltage is applied to the next scanning line 5) τ in the reset process of each radiation detection element 7 is an image. Although the case where the period is the same as the gate period τ in the reading process of the data D has been shown, the period may be set to be shorter than the gate period τ in the reading process of the image data D.

  In addition, in order to obtain the offset included in the image data D, the same sequence as the processing sequence up to the reading process of the image data D is repeated as shown in FIG. Read processing is performed. That is, reset processing of each radiation detection element 7 is performed, and dark voltage is accumulated in each radiation detection element 7 by applying an off-voltage to each scanning line 5 for the same time as the charge accumulation state in the state where radiation is not irradiated. Then, read processing for reading as offset data O is performed.

  However, when the manufacturers of the radiographic imaging apparatus and the radiation generation apparatus are different, there is a case where signals and the like cannot be accurately exchanged between the two as described above. In such a case, it is necessary to detect that the radiation image capturing apparatus itself has irradiated the radiation. In the following, a method of performing radiographic imaging by detecting radiation irradiation by the radiographic imaging apparatus itself without exchanging signals and information between the radiographic imaging apparatus and the radiation generating apparatus will be described below. This is called a non-cooperation method.

  As a method of detecting radiation irradiation by the radiographic imaging device itself, for example, as described in Patent Document 3, an X-ray sensor is provided in the radiographic imaging device, and whether or not radiation is irradiated by the output value is determined. If the radiation image capturing apparatus is irradiated with radiation as described in, for example, Patent Document 4, wiring in the apparatus (for example, a bias line 9 and a connection line 10 described later) Utilizing the fact that the current flowing in the inside increases, a current detection means is provided in the radiographic imaging apparatus, and the radiation imaging apparatus itself detects radiation irradiation by monitoring the output from the current detection means. It is possible to configure.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP 2009-219538 A

  However, as described above, when the radiographic imaging apparatus is newly provided with an X-ray sensor and current detection means, for example, it is necessary to provide a space for arranging the X-ray sensor in the radiographic imaging apparatus. Due to noise generated or noise generated by the current detection means, a new problem such as deterioration of the S / N ratio of the read image data D occurs.

  Therefore, in order to avoid the occurrence of such a problem, radiographic imaging is performed by using each functional unit such as the readout circuit 17 already provided without providing a new sensor or means in the radiographic imaging apparatus. Research on a radiographic imaging apparatus capable of detecting radiation irradiation by the apparatus itself and performing radiographic imaging is underway.

  As a method for detecting radiation irradiation using each existing functional unit, for example, image data d (image data D as a main image read out after radiation irradiation as described above and image data D before radiation image capturing) In order to make a distinction, this is referred to as image data d), and radiation exposure is detected by utilizing the rapid increase in the value of the read image data d when the radiation imaging apparatus is irradiated with radiation. It is conceivable to configure so as to.

  In this case, before the radiographic image is taken, the gate driver 15b sequentially applies on-voltages to the lines L1 to Lx of the scanning line 5 to read out the image data d. As shown in FIG. 39, for example, the scanning line 5 Scanning from the gate driver 15b when it is detected that the image data d read when the on-voltage is applied to the line Ln starts to irradiate radiation, for example, exceeding a preset threshold value. An off voltage is applied to all the lines L1 to Lx of the line 5 to shift to a charge accumulation state.

  Then, after a predetermined time elapses, on-voltages are sequentially applied to the lines Ln + 1 to Lx and L1 to Ln of the scanning line 5 to obtain image data D as a main image (hereinafter referred to as main image data D). ) Is read out.

  As in the case of the cooperative method (see FIG. 38), in the case of the non-cooperative method, the same sequence as the processing sequence up to the reading process of the main image data D is repeated, and the reading process of reading as offset data O is performed. . That is, as shown in FIG. 40, the image data d is read out, and an off voltage is applied to each scanning line 5 for the same period of time as in the above-described charge accumulation state without irradiation with radiation. After the dark charge is accumulated, read processing for reading out as offset data O is performed.

  In this case, as shown in FIG. 40, instead of performing the reading process of the image data d after the reading process of the main image data D (see FIG. 39), a reset process of each radiation detection element 7 is performed. It is also possible. This is because it is not necessary to detect the start of radiation irradiation based on the image data d after the read processing of the main image data D (see FIG. 39).

By the way, in the case of the non-cooperative system shown in FIG. 39 or FIG. 40, the time for applying the on-voltage to each scanning line 5 (hereinafter referred to as on-time. This is the time until the applied voltage is switched to the off voltage.) When T ^* is controlled to be longer than the on time T in the reading process of the main image data D, the detection efficiency of the start of radiation irradiation by the image data d Is preferable.

  In addition, as described above, the radiation image capturing apparatus is irradiated with radiation, and the value of the image data d is increased. Therefore, the useful charge generated in each radiation detection element 7 due to the radiation irradiation corresponds to that amount. It means that it is lost from each radiation detection element 7. Therefore, since the main image data D read from each radiation detection element 7 has lost some useful data, each of the scanning lines 5 to which each radiation detection element 7 is connected. A so-called line defect occurs in the portion.

  Therefore, when the radiation irradiation start is detected after the on-voltage is applied to the plurality of scanning lines 5 after the radiation irradiation is actually started to the radiographic imaging device, the on-voltage is applied between them. Similarly, useful charges are lost from each radiation detection element 7 connected to each scanning line 5. Therefore, when an on-voltage is applied to, for example, the lines Ln to Ln + 2 of the scanning line 5 between the actual irradiation and detection, as shown in FIG. 41, the three scanning lines 5 Line defects appear continuously in the part.

In this way, if line defects appear continuously, useful data in that portion will be lost, so this can be prevented, or even if line defects occur continuously, in order to suppress the number of occurrences as much as possible, for example, As shown in FIG. 39, it is preferable to control the gate period τ ^* in the reading process of the image data d before radiographic imaging to be longer than the gate period τ in the reading process of the main image data D. By controlling in this way, it is possible to reduce the number of scanning lines 5 to which an on-voltage is applied between the time when radiation is actually emitted and the time when it is detected.

As described above, when the radiation imaging apparatus itself is configured to detect radiation irradiation in a non-cooperative system, the purpose is to improve the detection efficiency at the start of radiation irradiation or reduce the number of generated line defects. Thus, the on-time T ^* and the gate period τ ^* in the reading process of the image data d before radiographic imaging are controlled to be longer than the on-time T and the gate period τ in the reading process of the image data D. Need to be done.

  However, as shown in FIG. 40, at least the time required for the reset process of each radiation detection element 7 (or the read process of the image data d. The same applies hereinafter) performed before the read process of the offset data O is as follows. It becomes longer than the case of the cooperation method shown in FIG. Further, when the reset process is repeatedly performed a plurality of times before the offset data O reading process, the time required for the reset process is further increased.

  As described above, when shooting in the non-cooperative method, there is a problem that the time required for the entire processing including the reading process of the offset data O is longer than that in the cooperative method.

  The present invention has been made in view of the above-described problems, and the time required for the entire processing up to the offset data O readout processing even when imaging is performed in a non-cooperative manner that cannot be coordinated with the radiation generation apparatus. An object of the present invention is to provide a radiographic imaging apparatus capable of shortening

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 comprising a gate driver for switching between and applying an on voltage and an off voltage to each scanning line;
Switch means for releasing the charge accumulated in the radiation detection element to the signal line when an on-voltage is applied via the scanning line;
A readout circuit comprising an amplification circuit and a sampling circuit for converting and reading out the electric charge emitted from the radiation detection element to the signal line;
Control means for controlling at least the scanning drive means and the readout circuit to perform a readout process of the data from each radiation detection element;
With
Before the radiographic image capturing, the control unit is configured to transfer all the scanning lines connected to the gate driver from the gate driver of the scanning driving unit or all the scanning lines connected to the gate driver. A reset process for each of the radiation detection elements performed by applying an on voltage to a part of the plurality of scanning lines, and each of the radiations via the switch means in a state in which an off voltage is applied to each of the scanning lines. Based on the read leak data, the sampling circuit samples the value output from the amplifier circuit corresponding to the charge leaked from the detection element and reads the leak data as leak data. And detecting the start of radiation irradiation.

  According to the radiographic imaging apparatus of the system of the present invention, before radiographic imaging, all the scanning lines connected to the gate driver from the gate driver of the scanning driving means 15 or some of the scanning lines are included. An on-voltage is applied to the image sensor to perform reset processing of each radiation detection element, which is alternately performed with image data read processing and leak data read processing.

  Therefore, after the reading process of the image data as the main image, the reading process of the image data performed by applying the on-voltage to all the scanning lines or a part of the scanning lines and the reset process of each radiation detection element are performed once. Or after about twice, it is possible to immediately shift to the charge accumulation state and perform the offset data reading process, etc., and the entire process from the reading process of the image data to the reading process of the offset data It is possible to reduce the time required for the process.

  Further, it is possible to accurately detect at least the start of radiation irradiation based on image data and leak data read out before radiographic image capturing. Therefore, even when imaging is performed in a non-cooperative manner that cannot be coordinated with the radiation generation apparatus, the radiation imaging apparatus itself can accurately detect radiation irradiation and accurately perform radiographic imaging. .

It is an external appearance perspective view of the radiographic imaging device concerning this embodiment. It is the external appearance perspective view which looked at the radiographic imaging apparatus of FIG. 1 from the other side. 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 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 showing the ON / OFF timing of the charge reset switch and TFT in the reset processing of each radiation detection element. 6 is a timing chart showing charge reset switches, pulse signals, and TFT on / off timings in image data read processing. It is a figure explaining that each electric charge which leaked from each radiation detection element via TFT is read as leak data. 6 is a timing chart showing on / off timings of charge reset switches and TFTs in a leak data read process. 6 is a timing chart in a case where image data is read out by applying an ON voltage to a plurality of scanning lines before radiographic imaging. 6 is a timing chart in the case where leakage data reading processing and reset processing of each radiation detection element performed by applying an ON voltage to a plurality of scanning lines are alternately performed before radiographic image capturing. It is the graph which plotted the image data read by the read-out process performed before radiographic image imaging in time series. It is a block diagram showing the equivalent circuit of the structural example in the case of designating the signal line for a detection. It is a figure showing the case where the radiation which narrowed the irradiation field was irradiated to the radiographic imaging device. It is a graph showing the example of the time transition of the leak data read by each read circuit. FIG. 14 is a timing chart in a case where the leak data reading process is repeatedly performed in the charge accumulation state in the case of FIG. 13. It is a graph which shows that leak data reduce when irradiation of radiation is completed. 14 is a timing chart from the main image data reading process to the offset data reading process in FIG. 13; It is a figure explaining the terminal which is not connected in a gate driver or gate IC. It is a timing chart showing the example at the time of comprising so that reading processing of the image data before radiographic imaging may be performed by applying an ON voltage alternately to each divided scanning line. FIG. 6 is a timing chart showing an example of a case in which image data reading processing before radiographic image capturing is performed by shifting rising and falling of on-voltages applied to a plurality of scanning lines during transmission of a pulse signal twice. is there. It is a timing chart showing the example at the time of comprising so that a reset process before radiographic imaging may be performed by applying an ON voltage alternately to each divided scanning line. It is a timing chart showing the example at the time of comprising so that the reset process before radiographic imaging may be performed by shifting the rise and fall of on-voltage applied to a plurality of scanning lines. FIG. 25 is a timing chart illustrating an example of a configuration in which a pulse signal is transmitted only once in the example of FIG. 24 and image data is read before radiographic imaging is performed. FIG. 27 is a timing chart illustrating an example of a configuration in which a pulse signal is transmitted only once in the example of FIG. 26 and leak data before radiographic imaging is read out. It is a graph showing the time transition of the dark charge ((alpha)) generate | occur | produced at a fixed rate per unit time, and the lag ((beta)) in which the generation rate per unit time attenuate | damps. It is a figure explaining offset part by a lag changing depending on the timing which reads offset data by reading processing of offset data after irradiation. FIG. 41 is a diagram for explaining that a difference in level occurs in true image data before and after the scanning line where the reading process of the main image data is started in the processes according to FIGS. 39 and 40. FIGS. 13 and 21 are diagrams for explaining that there is no step in the true image data before and after the scanning line where the reading process of the main image data is started. It is a graph explaining the delay time of the timing which switches the voltage applied to each terminal of each gate IC. It is a graph explaining that a wavy profile may appear in the main image data (signal value) when the gate IC shown in FIG. 33 is used. It is a timing chart in the case of performing the reset process of each radiation detection element 7 before irradiation of a radiation in a cooperation system. It is a timing chart showing the timing of transmission of the irradiation start signal in a cooperation system, completion | finish of a reset process, transfer to a charge accumulation state, transmission of an interlock release signal, and radiation irradiation. It is a timing chart showing the timing which applies an ON voltage sequentially to each scanning line in a cooperation system. FIG. 38 is a timing chart for explaining that offset data reading processing is performed by repeating the same processing sequence as the series of processing shown in FIG. 37 in the case of the cooperation method. FIG. 10 is a timing chart up to reading processing of main image data in a case where the non-cooperation method is configured to sequentially apply an ON voltage to each scanning line and perform reset processing of each radiation detection element before radiographic image capturing. FIG. 40 is a timing chart for explaining that offset data reading processing is performed by repeating the same processing sequence as the series of processing shown in FIG. 39 in the case of the non-cooperation method. It is a figure showing the state where a line defect appears continuously.

  Embodiments of a radiographic image capturing apparatus according to the present invention will be described below with reference to the drawings.

  In the following description, a so-called indirect radiation image capturing apparatus that includes a scintillator or the like and converts an emitted radiation into an electromagnetic wave having another wavelength such as visible light to obtain an electric signal will be described. The present invention can also be applied to a so-called direct type radiographic imaging apparatus that directly detects radiation with a radiation detection element without using a scintillator or the like. Although the case where the radiographic imaging apparatus is a so-called portable type will be described, the radiographic imaging apparatus is also applied to a so-called dedicated machine type radiographic imaging apparatus formed integrally with a support base or the like.

  FIG. 1 is an external perspective view of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is an external perspective view of the radiographic image capturing apparatus viewed from the opposite side. FIG. 3 is a sectional view taken along line XX of FIG. As shown in FIGS. 1 to 3, the radiographic image capturing apparatus 1 includes a housing 2 in which a sensor panel SP including a scintillator 3 and a substrate 4 is accommodated.

  As shown in FIG. 1 and FIG. 2, in this embodiment, a hollow rectangular tube-shaped housing body 2A having a radiation incident surface R in the housing 2 is made of a material such as a carbon plate or plastic that transmits radiation. The housing 2 is formed by closing the openings on both sides of the housing body 2A with lid members 2B and 2C. Instead of forming the casing 2 as such a so-called monocoque type, for example, a so-called lunch box type formed of a front plate and a back plate can be used.

  As shown in FIG. 1, the lid member 2 </ b> B on one side of the housing 2 is configured with a power switch 37, a changeover switch 38, a connector 39, an LED that displays a battery state, an operating state of the radiographic imaging apparatus 1, and the like. The indicator 40 and the like are arranged.

  In addition, as shown in FIG. 2, an antenna device 41 as a communication unit for the radiographic imaging apparatus 1 to transmit and receive information and signals to / from an external device (not shown) such as a console in a wireless manner includes, for example, a housing. 2 on the opposite side of the lid member 2C. The antenna device 41 can be provided, for example, by being embedded in the lid member 2C. The installation position of the antenna device 41 is not limited to the lid member 2 </ b> C, and the antenna device 41 can be installed at an arbitrary position of the radiographic image capturing apparatus 1. Further, the number of antenna devices 41 to be installed is not limited to one, and a plurality of antenna devices can be provided.

  Although illustration is omitted, it is also possible to configure such that a cable or the like is connected to the connector 39 so that transmission / reception of information, signals, and the like with an external device is performed in a wired manner. In this case, the connector 39 functions as a communication unit. Note that it is possible to transmit / receive a signal or the like to / from a radiation generator (not shown) via the antenna device 41 or the connector 39, but at least as in this embodiment, a radiographic imaging device. When radiographic imaging is performed in a non-cooperative manner using 1, communication with the radiation generator via the connector 39 or the like is not performed.

  As shown in FIG. 3, 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 is disposed on the base 31. The PCB substrate 33, the buffer member 34, and the like are attached. Further, a glass substrate 35 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed. Moreover, in this embodiment, the buffer material 36 for preventing that they collide between the sensor panel SP and the side surface of the housing | casing 2 is provided.

  The scintillator 3 is provided at a position on the substrate 4 that faces a detection unit P described later. In the present embodiment, the scintillator 3 is, for example, a phosphor whose main component is converted into an electromagnetic wave having a wavelength of 300 to 800 nm when receiving radiation, that is, an electromagnetic wave centered on visible light and output. .

  In the present embodiment, the substrate 4 is formed of a glass substrate. As shown in FIG. 4, 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. As shown in FIG. 5 which is an enlarged view of FIG. 4, each radiation detection element 7 is connected to a source electrode 8s of a TFT 8 which is a switch means. The drain electrode 8 d of the TFT 8 is connected to the signal line 6.

  When the radiation detection element 7 receives radiation from the radiation incident surface R of the housing 2 of the radiation image capturing apparatus 1 and is irradiated with electromagnetic waves such as visible light converted from the radiation by the scintillator 3, the inside of the radiation detection element 7 becomes electron positive. Generate hole pairs. In this way, the radiation detection element 7 converts the irradiated radiation (electromagnetic wave irradiated from the scintillator 3) into electric charge.

  The TFT 8 is turned on when a turn-on voltage is applied to the gate electrode 8g via the scanning line 5 from the scanning driving means 15 described later, and is accumulated in the radiation detection element 7 via the source electrode 8s and the drain electrode 8d. The charged electric charge is discharged to the signal line 6. The TFT 8 is turned off when an off voltage is applied to the gate electrode 8g via the connected scanning line 5, and the emission of the charge from the radiation detecting element 7 to the signal line 6 is stopped, and the radiation detecting element The electric charge is accumulated in 7.

  In the present embodiment, as shown in FIG. 5, one bias line 9 is connected to a plurality of radiation detection elements 7 arranged in rows, and as shown in FIG. Each is arranged in parallel to the signal line 6. Further, each bias line 9 is bound to the connection 10 at a position outside the detection portion P of the substrate 4.

  In the present embodiment, as shown in FIG. 4, 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. 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 15c constituting a gate driver 15b of a scanning drive means 15 described later is incorporated on a 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 is connected to the PCB substrate 33 described above on the back surface 4b side. In this way, the sensor panel SP of the radiation image capturing 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 7b, and each bias line 9 is bound to the connection 10 to the bias power source 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 7 b 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 the present embodiment, the bias power supply 14 supplies the second electrode 7 b of the radiation detection element 7 to the first electrode 7 a side of the radiation detection element 7 as a bias voltage via the bias line 9. A voltage equal to or lower than the voltage applied to (i.e., a so-called reverse bias voltage) is applied.

  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 15d, 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. In the present embodiment, the gate driver 15b includes a plurality of gate ICs 15c (see FIG. 6) arranged in parallel.

  It should be noted that the application of the ON voltage from the gate driver 15b of the scanning drive means 15 to each of the lines L1 to Lx of the scanning line 5 during the reading process of the main image data D from each radiation detection element 7 will be described later. I will explain it.

  As shown in FIGS. 7 and 8, each signal line 6 is connected to each readout circuit 17 formed in the readout IC 16. The readout circuit 17 includes an amplification circuit 18 and a correlated double sampling circuit 19 as a sampling circuit. 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 a charge amplifier circuit including an operational amplifier 18a, a capacitor 18b and a charge reset switch 18c connected in parallel to the operational amplifier 18a, and a power supply unit 18d that supplies power to the operational amplifier 18a and the like. It consists of 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.

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

  When the radiation imaging apparatus 1 performs reset processing of each radiation detection element 7 for removing the charge remaining in each radiation detection element 7, as shown in FIG. 9, the charge reset switch 18c is turned on. When each TFT 8 is turned on in the state (and the switch 18e is turned off), electric charges are released from the radiation detection elements 7 to the signal lines 6 through the respective TFTs 8 turned on, The signal passes through the charge reset switch 18c of the amplifier circuit 18, passes through the operational amplifier 18a from the output terminal side of the operational amplifier 18a, is grounded from the non-inverting input terminal, or flows out to the power supply unit 18d.

  On the other hand, when the image data D is read from each radiation detection element 7, the charge reset switch 18c of the amplifier circuit 18 is turned off (and the switch 18e is turned on) as shown in FIG. In this state, when charges are released from the radiation detecting elements 7 to the signal lines 6 through the TFTs 8 that are turned on, the charges are accumulated in the capacitor 18b of the amplifier circuit 18. In the amplifier circuit 18, a voltage value corresponding to the amount of charge accumulated in the capacitor 18 b is output from the output side of the operational amplifier 18 a, and the charge flowing out from each radiation detection element 7 by the amplifier circuit 18. Is converted into a charge voltage.

  The correlated double sampling circuit (CDS) 19 provided on the output side of the amplifier circuit 18 receives the pulse signal Sp1 (see FIG. 10) from the control means 22 before the electric charge flows out from each radiation detection element 7. Then, the voltage value Vin output from the amplification circuit 18 at that time is held, and the charge flowing out from each radiation detection element 7 as described above is accumulated in the capacitor 18b of the amplification circuit 18 and then from the control means 22. When the pulse signal Sp2 is transmitted, the voltage value Vfi output from the amplifier circuit 18 at that time is held.

  When the correlated double sampling circuit 19 holds the voltage value Vfi with the second pulse signal Sp2, the correlated double sampling circuit 19 calculates the difference Vfi−Vin of the voltage value, and uses the calculated difference Vfi−Vin as downstream image data D of the analog value. Output to the side. Then, the image data D of each radiation detection element 7 output from the correlated double sampling circuit 19 is sequentially transmitted to the A / D converter 20 via the analog multiplexer 21, and is sequentially converted into a digital value by the A / D converter 20. The image data D is converted to the image data D, output to the recording means 23 and sequentially stored.

  When one reading process of the image data D is completed, the charge reset switch 18c of the amplifier circuit 18 is turned on (see FIG. 10), and the charge accumulated in the capacitor 18b is discharged, and the same as above. On the other hand, 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, is grounded, or flows out to the power supply unit 18d.

  In addition, the amplifier circuit 18 does not necessarily need to be configured by a charge amplifier circuit as in the present embodiment, and an on-voltage is applied to each scanning line 5 and corresponds to the amount of charge flowing out from each radiation detection element 7. Other types of amplifier circuits can be used as long as they output values.

  Furthermore, in the present embodiment, as described above, the case where the correlated double sampling circuit 19 is used as the sampling circuit has been shown. However, in addition to this, for example, a pulse signal transmitted only once from the control means 22 is received. Then, it is also possible to use a sampling circuit that samples the value output from the amplifier circuit 18 at that timing and outputs it as data. In this case, for example, it is also possible to use a sampling circuit in which the sampling circuit automatically performs sampling at a unique timing without transmitting a pulse signal from the control means 22.

  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 to a recording means 23 composed of a DRAM (Dynamic RAM) or the like.

  In the present embodiment, the above-described antenna device 41 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 recording unit 23, the bias power source 14, and the like. A battery 24 for supplying electric power is connected. Further, a connection terminal 25 for charging the battery 24 by supplying power to the battery 24 from a charging device (not shown) is attached to the battery 24.

  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.

  In the present embodiment, as described above, the radiation image capturing apparatus 1 itself does not exchange radiation signals without exchanging signals or the like between the radiation image capturing apparatus 1 and the radiation generating apparatus (not shown). A process unique to the present invention that is performed by the radiation image capturing apparatus 1 in the method of performing radiation image capturing by detecting the start of irradiation will be described.

[How to detect the start of radiation irradiation]
In the present embodiment, the radiation image capturing apparatus 1 is not provided with a new function unit such as an X-ray sensor, but detection of radiation irradiation, radiation image capturing, or the like is performed using each function unit already installed in the apparatus. It has become. As described above, for example, the following two detection methods can be employed as a method of detecting radiation irradiation by the radiographic imaging apparatus 1 itself using each function unit already provided in the apparatus. Hereinafter, before explaining the processing unique to the present invention, a detection method for detecting the start of radiation irradiation will be described.

[Detection method 1]
For example, as shown in FIG. 39 and the like described above, the image data d is read from each radiation detection element 7 before radiographic imaging, and the start of radiation irradiation is detected based on the read image data d. It can be configured to do so. In this case, the reading process of the image data d before the radiographic image capturing is a process for detecting the radiation irradiation by the radiographic image capturing apparatus 1 itself, but the dark charge remaining in each radiation detecting element 7 or the like It also serves as a reset process for each radiation detection element 7 for removing the electric charge from each radiation detection element 7.

  However, in the present embodiment, as shown in FIG. 39 and the like, the on-voltage is not sequentially applied from the gate driver 15b of the scanning driving unit 15 to the lines L1 to Lx of the scanning line 5, but FIG. As shown in FIG. 8, the on-voltage is applied to the plurality of lines of the scanning line 5 to read out the image data d. This point will be described later.

  When the reading process of the image data d is performed before radiographic imaging as in the detection method 1, as shown in FIG. 10, the correlated double sampling circuit is applied before and after the on-voltage is applied to the scanning line 5 from the gate driver 15b. The pulse signals Sp 1 and Sp 2 are transmitted to 19, and the voltage value Vfi output from the amplification circuit 18 after applying the ON voltage to the scanning line 5 is output from the amplification circuit 18 before the ON voltage is applied to the scanning line 5. The voltage value Vin thus subtracted is subtracted, and a difference Vfi−Vin between the voltage values is read as image data d.

[Detection method 2]
On the other hand, it is possible to repeat the reading process of the leak data dleak before radiographic image capturing. As shown in FIG. 11, the leak data dleak is a signal line of charge q leaked from each radiation detection element 7 via each TFT 8 which is in an OFF state in a state where an OFF voltage is applied to each scanning line 5. Data corresponding to a total value of every six.

  Then, in the readout process of the leak data dleak, as shown in FIG. 12, each readout circuit is supplied from the control means 22 in a state in which each TFT 8 is turned off by applying an off voltage to each line L1 to Lx of the scanning line 5. The pulse signals Sp1 and Sp2 are transmitted to 17 correlated double sampling circuits 19 (see CDS in FIGS. 7 and 8), and the leak data dleak is read out.

  In this case, unlike the case of the reading process of the image data d (see FIG. 10), the ON voltage is not applied from the gate driver 15b to each scanning line 5, but the control means 22 applies to the correlated double sampling circuit 19. The signal line 6 of the charge q leaked from each radiation detection element 7 through each TFT 8 accumulated in the capacitor 18b of the amplifier circuit 18 between the time when the pulse signal Sp1 is transmitted and the time when the pulse signal Sp2 is transmitted. The total value for each is read as leak data dleak.

  However, when the reading process of the leak data dleak is repeatedly performed as described above, each TFT 8 remains in an off state, and thus the dark charge generated in each radiation detection element 7 is accumulated in each radiation detection element 7. It will be in a state to continue. When a large amount of dark charge is accumulated in each radiation detection element 7, the radiation image capturing apparatus 1 is then irradiated with radiation, and useful charges generated in each radiation detection element 7 due to radiation irradiation are accumulated. A possible amount, that is, a dynamic range of each radiation detection element 7 is narrowed.

  For this reason, in the case where the reading process of the leak data dleak is repeatedly performed before the radiographic image capturing, each of the radiation detection elements 7 is between the reading process of the leak data dleak and the reading process of the next leak data dleak. It is configured to perform a reset process. That is, as shown in FIG. 14 and the like to be described later, the reading process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed.

  In this embodiment, in the reset process between the leak data dleak, as shown in FIG. 14 and the like to be described later, the on-voltage is applied to a plurality of lines of the scanning line 5 to perform the reset process. This will be explained later.

[How to apply ON voltage to each scanning line in the process before radiographic imaging]
Next, processing before radiographic imaging unique to the present invention and the like in the system in which the radiographic imaging apparatus 1 itself detects the start of radiation irradiation and performs radiographic imaging in the non-cooperative system will be described. Hereinafter, the operation of the radiographic image capturing apparatus 1 according to the present embodiment will also be described.

  In the present embodiment, the scanning line 5 is applied when the on-voltage is applied from the gate driver 15b to each scanning line 5 before the radiographic image capturing, regardless of whether the detection method 1 or the detection method 2 is employed. The on-voltage is applied to the plurality of lines L to read the image data d (in the case of the detection method 1) and reset the respective radiation detection elements 7 (in the case of the detection method 2).

  Specifically, in the case of the detection method 1, for example, as illustrated in FIG. 13, the control unit 22 transmits the pulse signals Sp1 and Sp2 to the correlated double sampling circuit 19 from the gate driver 15b to the gate. An on-voltage is applied to all the lines L1 to Lx of the scanning line 5 connected to the driver 15b at the same time, and each charge is received from each radiation detection element 7 connected to each line L1 to Lx of the scanning line 5. It is configured to repeatedly perform a reading process of discharging and reading out as image data d.

  In this case, as can be seen from the relationship among each radiation detection element 7, signal line 6, and readout circuit 17 (represented by the amplification circuit 18 in FIG. 11) shown in FIG. 11, each readout circuit 17. The image data d read out in (1) corresponds to the total value of the image data read out from each radiation detection element 7 connected to one signal line 6 connected to the readout circuit 17.

  Then, when the control means 22 detects that radiation irradiation has started based on the image data d read out as described later, as shown in FIG. 13, the control means 22 stops the reading process of the image data d, Each TFT 8 is turned off by applying an off voltage to all the lines L1 to Lx of the scanning line 5 from the gate driver 15b, and useful charges generated in each radiation detecting element 7 due to radiation irradiation are supplied to each radiation detecting element. 7 is shifted to a charge accumulation state to be accumulated in the inside.

  Then, after a predetermined time has elapsed since the start of radiation irradiation was detected, the control means 22 sequentially applies the on-voltage from the gate driver 15b in order from the first line L1 of the scanning line 5, and thereby the main image data D Is read out.

  In the case of the detection method 2, the same processing is performed. That is, as described above, in the present embodiment, the control means 22 performs the leak data dleak read processing (refer to FIG. 12, and is described as “L” in FIG. 14 described later) before radiographic image capturing. The reset processing of each radiation detection element 7 (see FIG. 9; described as “R” in FIG. 14 described later) is alternately repeated.

  At that time, in the reset process of each radiation detection element 7, for example, as shown in FIG. 14, the on-voltage is simultaneously applied from the gate driver 15b to all the lines L1 to Lx of the scanning line 5 connected to the gate driver 15b. The reset process is performed by discharging the remaining charges from the radiation detecting elements 7 connected to the lines L1 to Lx of the scanning line 5.

  Then, when the control means 22 detects that the irradiation of radiation has been started based on the leak data dleak read out as described later, as shown in FIG. 14, the control means 22 stops the leak data dleak readout process, Each TFT 8 is turned off by applying an off voltage to all the lines L1 to Lx of the scanning line 5 from the gate driver 15b, and useful charges generated in each radiation detecting element 7 due to radiation irradiation are supplied to each radiation detecting element. 7 is shifted to a charge accumulation state to be accumulated in the inside.

  Then, after a predetermined time has elapsed since the start of radiation irradiation was detected, the control means 22 sequentially applies the on-voltage from the gate driver 15b in order from the first line L1 of the scanning line 5, and thereby the main image data D Is read out.

[Detection of radiation start]
[principle]
The same applies to the detection method 2 described above. However, as in the detection method 1, when the image data d is read out as described above before radiographic imaging, as shown in FIG. In addition, when radiation irradiation to the radiation image capturing apparatus 1 is started, the image data d read at that time (see time t1 in the figure) (leakage data dleak in the case of the detection method 2; the same applies hereinafter). However, the value is much larger than the image data d read before that.

  Therefore, the control unit 22 is configured to monitor the image data d read in the reading process before radiographic image capturing, and a threshold value dth is set in advance for the image data d as shown in FIG. 15, for example. Then, it is possible to detect the start of radiation irradiation when the read image data d exceeds the threshold value dth.

[Precautions when adopting detection method 1]
At that time, in the detection method 1 in particular, as described above, the read image data d is the total value of the image data read from each radiation detection element 7 connected to one signal line 6. Therefore, the image data d read when the radiation image capturing apparatus 1 is irradiated with radiation has a very large value, which may cause a problem such as damage to the reading IC 16 (see FIG. 7).

  Therefore, in the reading process of the image data d before radiographic imaging, for example, the ON voltage applied to each TFT 8 from the gate driver 15b via each scanning line 5 is used in the reading process of the main image data D. It is possible to reduce the amount of electric charge flowing out from each radiation detection element 7 via each TFT 8 in the reading process of the image data d before the radiographic image capture, with a value lower than the normal ON voltage to be applied. It is.

  However, if the ON voltage applied to each TFT 8 is set to a low value as described above, the detection sensitivity when detecting the start of radiation irradiation based on the image data d as described above may be lowered. Thus, in the case where the detection sensitivity is lowered when the on-voltage applied to each TFT 8 is set to a low value as described above, the problem can be solved by configuring the radiographic imaging apparatus 1 as follows. Is possible.

  That is, for example, as shown in FIG. 16, one or several signals are provided for each readout IC 16 from among the signal lines 6 connected to each readout IC 16 described above, for example, 128 or 256. A predetermined signal line 6 is designated as a detection signal line 6α.

  FIG. 16 shows a case where each signal line 6 at both ends of each readout IC 16 is designated as a detection signal line 6α for each readout IC 16. Further, in FIG. 16, each radiation detection element 7 is shown for only two rows in the scanning line direction, but each radiation detection element 7 in other rows is configured in the same manner. Furthermore, although it is described that the space between the two rows of the radiation detection elements 7 is expanded as compared with the case shown in FIG. 7 and the like, it is a description for making the drawing easier to see, and that it is actually expanded. It doesn't mean. Also, description of the internal configuration of the bias line 9 and the readout IC 16 is omitted.

  Then, as shown in FIG. 16, the TFT 8 of each radiation detection element 7 connected to the designated detection signal line 6α is newly provided from, for example, a gate driver 15e provided separately from the original gate driver 15b. The scanning line 5 (Li, Li + 1) is extended and the gate electrode 8g of the TFT 8 is connected. Note that the scanning line 5 extending from the original gate driver 15b is connected to the gate electrode 8 of each TFT 8 connected to the signal line 6 other than the detection signal line 6α.

  In the reading process of the image data d before radiographic image capturing, the on-voltage is applied at the same timing from each gate driver 15b, 15e to each TFT 8 in at least the same row. A normal high on-voltage is applied from the gate driver 15e to the TFT 8 connected to the signal line 6α, and the original gate driver 15b is applied to the TFT 8 connected to many other signal lines 6. The on-voltage having a value lower than the above-described normal high-value on-voltage is applied.

  With this configuration, the amount of charge flowing into the readout IC 16 via a large number of signal lines 6 other than the detection signal line 6α is reduced, so that a large amount of charge flows into the readout IC 16 as described above and the readout IC 16 It is possible to accurately prevent problems such as damage. Further, when the radiation imaging apparatus 1 is irradiated with radiation, a large amount of charge similar to that in a normal case flows into the readout IC 16 via a small number of detection signal lines 6α, so that the image data d to be read out is read out. Somewhat large value. For this reason, it is possible to accurately prevent the start of radiation irradiation by accurately preventing the read-out image data d from becoming too small and reducing the detection sensitivity at the start of radiation irradiation.

  As described above, if configured as described above, it is possible to accurately detect the start of radiation irradiation while accurately preventing the reading IC 16 from being damaged.

  Further, as described above, if the detection signal line 6α is configured to be set for each readout IC 16, for example, as shown in FIG. Even in the case of irradiation, the detection signal line 6α of any one of the readout ICs 16 exists in the irradiation field F, and is read by at least the readout IC 16 connected to the detection signal line 6α. The value of the image data d is accurately increased by irradiation with radiation. For this reason, it is possible to reliably detect the start of radiation irradiation.

  On the other hand, in the case of the detection method 1, during the reading process of the image data d before radiographic imaging, the above-described on-time (that is, the voltage applied after applying the on-voltage to each scanning line 5 is set to the off-voltage). In the case of the detection method 2, the pulse signals Sp1 and Sp2 transmitted from the control means 22 to the correlated double sampling circuit 19 at the time of reading the leak data dleak before radiographic image capture If the transmission interval is shortened, the amount of charge flowing out from each radiation detection element 7 (in the case of image data d) and the amount of charge leaking from each radiation detection element 7 via each TFT 8 (leakage) (In the case of data dleak) can be reduced, and the above problem can be avoided.

  Furthermore, in the above case, a method for avoiding the above problem by reducing the amount of electric charge flowing out or leaking from each radiation detection element 7 has been described. On the contrary, on the reading IC 16 side, for example, The capacity of the capacitor 18b of each amplifier circuit 18 is made variable, and the capacity of the capacitor 18b is set to be larger than the capacity at the time of the reading process of the main image data D in the reading process of the image data d before radiographic image capturing. It is also possible to make it variable so as to be a large value.

  With this configuration, the reactivity of the potential difference between the electrodes of the capacitor 18b with respect to the charge accumulated in the capacitor 18b can be reduced from the relationship of V = Q / C. Therefore, even if a large charge flows into the capacitor 18b, the change in potential difference between the electrodes can be reduced, and damage to the readout IC 16 can be avoided. Note that the same effect can be obtained by reducing the input resistance of the reading IC 16.

  As described above, even if the ON voltage is applied to the plurality of lines of the scanning line 5 as described above and the amount of charge flowing into the capacitor 18b of the amplifier circuit 18 increases, the reading IC 16 is not adversely affected. It is also possible to appropriately perform processing for preventing the reading IC 16 and the like from being adversely affected.

[Improved detection method of radiation start]
The same applies to the case where the above detection method 1 is adopted. For example, the above detection method 2 is adopted to detect the start of radiation irradiation on the radiographic imaging apparatus 1 based on the value of the leak data dleak. In such a configuration, since the detection unit P of the radiographic image capturing apparatus 1 (see FIG. 4 and FIG. 7 and the like) usually has several thousand to several tens of thousands of signal lines 6 wired, The number of leak data dleak read by the leak data dleak read processing is from several thousand to several tens of thousands.

  If the determination process for determining whether or not the threshold value is exceeded for each of the leak data dleak is performed for each read process, the determination process becomes heavy. Therefore, for example, a maximum value is extracted from the leak data dleak for each read circuit 17 read for each read process, and it is determined whether or not the maximum value of the leak data dleak exceeds a threshold value. It is possible to configure.

  With this configuration, the maximum value is extracted from each leak data dleak (image data d in the case of the detection method 1; the same applies hereinafter) read from each readout circuit 17, and the maximum value, threshold value, and the like are extracted. Therefore, the process of determining whether or not the read leak data dleak has exceeded the threshold can be made very light.

[Detection method considering the readout characteristics of each readout circuit]
At this time, there is a problem that the read characteristics of the data (image data d and leak data dleak) in each read circuit 17 (see FIGS. 7 and 8, etc.) are usually different for each read circuit 17.

  Specifically, the same applies when the above-described detection method 1 is adopted. However, for example, when the above-described detection method 2 is adopted, the total value of charges q leaked from the radiation detection elements 7 to the signal line 6 (see FIG. 11) is the same for each signal line 6, there is a readout circuit 17 that always reads leak data dleak having a larger value than the other readout circuits 17, and a smaller value than the other readout circuits 17 at all times. There is also a read circuit 17 for reading the leak data dleak.

  In such a situation, for example, as shown in FIG. 17, the radiation image photographing apparatus 1 is irradiated with radiation with the irradiation field F being narrowed, and leak data dleak always having a larger value than the other readout circuits 17. Consider a case in which the signal line 6a connected to the readout circuit 17 having the characteristic of reading out exists outside the irradiation field F.

  In such a case, as shown in FIG. 18, the radiation image photographing apparatus 1 is irradiated with radiation, and the leak data dleak read by the readout circuit 17 connected to the signal line 6 existing in the irradiation field F. Even if it rises due to the irradiation of radiation (refer to the data indicated by γ in the figure), it has a characteristic of always reading out leak data dleak having a large value connected to the signal line 6a existing outside the irradiation field F. There may occur a case where the leak data dleak (refer to the data indicated by δ in the figure) read from the read circuit 17 is not exceeded.

  Thus, the leak data extracted when the leak data bleak (γ) that has risen due to radiation irradiation does not exceed the leak data dleak (δ) that is outside the irradiation field F and does not rise even by radiation irradiation. The maximum value of the data dleak is the leak data dleak indicated by δ in the figure. For this reason, the maximum value of the extracted leak data dleak does not increase even when irradiated with radiation and does not exceed the threshold value, so that there is a possibility that the irradiation of radiation cannot be detected.

  Therefore, in order to avoid such a problem, for example, it is possible to calculate the moving average for each read circuit 17 of the leak data dleak read for each read process.

  That is, every time the leak data dleak is read, the average value of the leak data dleak read in each past read process for a predetermined number of times such as 10 times including the read process immediately before the read process (for example, 10 times) That is, the moving average) dleak_ave is calculated for each readout circuit 17.

  Then, for each readout circuit 17, a difference Δdleak between the leak data dleak read out in the current readout process and the calculated moving average dleak_ave is calculated, and the difference Δdleak exceeds a threshold set in advance for the difference Δdleak. If the readout circuit 17 is provided, it can be configured to detect that the radiation imaging apparatus 1 has been irradiated with radiation at that time.

  With this configuration, it is possible to accurately detect whether or not the leak data dleak has risen without being affected by the readout characteristics of the readout circuits 17 as described above. It becomes possible to accurately detect the start of radiation irradiation.

[Further improved detection method for starting irradiation]
However, in this case as well, thousands to tens of thousands of read data 17 from each read circuit 17 provided in each of the signal lines 6 arranged in the thousands to tens of thousands are arranged for each read process of the leak data dleak. Each leak data dleak is read out. If the above-described processing is performed on each of the leak data dleak, the moving average calculation processing and determination processing are also heavy.

  Therefore, in the radiographic imaging apparatus 1 of the present embodiment, for example, 128 or 256 readout circuits 17 are formed in the readout IC 16, and a plurality of readout ICs 16 are provided so that each signal line 6 is connected to each readout circuit 17. The total value of the leak data dleak read by each read circuit 17 is calculated for each read IC 16 for each read process of the leak data dleak by using the configuration that is connected to To do.

  In this case, instead of the configuration in which the total value of the leak data dleak is calculated for each readout IC 16, the average value of the leak data dleak may be calculated. In addition, instead of calculating the total value or the average value of each leak data dleak for each read IC 16, a median value (also referred to as a median or an intermediate value) of each leak data dleak may be calculated. Is possible. The same applies to the following description.

  Similarly to the above, the moving average of the total value of each leak data dleak is calculated for each read IC 16, the total value for each read IC 16 of the leak data dleak read in the current read process, and the calculated total value The difference from the moving average is calculated. Then, if there is a reading IC 16 whose difference exceeds a preset threshold for the difference, it can be configured to detect that the radiation image capturing apparatus 1 has been irradiated with radiation at that time.

  With this configuration, since the number of readout ICs 16 is several to several tens, the above-described processing such as moving average calculation, difference calculation, and comparison between a difference and a threshold value is performed from several to several tens. Since it suffices to perform this operation for each read IC 16, it is possible to lighten the process of determining whether or not the read leak data dleak exceeds the threshold value.

  Further, as described above, the maximum value is extracted from the above differences for each reading IC 16 calculated for each reading process of the leak data dleak, and it is determined whether or not the maximum value exceeds the threshold value. It is also possible to configure. In this case, since the above difference is the same value for each reading IC 16, the problem as shown in FIG. 18 does not occur.

  With this configuration, it is only necessary to compare the maximum value of the total value (or the average value or the median value) of the leak data dleak (image data d in the case of the detection method 1) for each readout IC 16 with the threshold value. Thus, it is possible to make the determination process of whether or not the read leak data dleak exceeds the threshold value very light.

[Detection of radiation exposure completion]
On the other hand, as shown in FIG. 13 and FIG. 14, after detecting the start of radiation irradiation, the image data d is read out (in the case of the detection method 1, see FIG. 13), and each radiation detection element 7. Reset processing and leakage data dleak reading processing (in the case of the detection method 2, refer to FIG. 14), and the state shifts to the charge accumulation state.

  As described above, in this embodiment, in this charge accumulation state, a predetermined time has elapsed since the start of radiation irradiation was detected while maintaining the state in which the off-voltage was applied to each scanning line 5 from the gate driver 15b. When the time has elapsed, the on-voltage is sequentially applied from the gate driver 15b from the first line L1 of the scanning line 5 to read the main image data D.

  However, instead of such a configuration, for example, as shown in FIG. 19, the readout processing of the leak data dleak is repeatedly performed in the state where the off-voltage is applied to each scanning line 5 in the charge accumulation state. It is also possible to configure. If comprised in this way, it will become possible to detect the completion | finish of irradiation of the radiation with respect to the radiographic imaging apparatus 1 so that it may demonstrate below.

  That is, if the read processing of the leak data dleak is performed in the charge accumulation state after detection of the start of radiation irradiation, radiation irradiation has already started in the charge accumulation state in the case of the non-cooperative method. As shown, the read leak data dleak has a large value. When radiation irradiation to the radiographic image capturing apparatus 1 is completed, the leak data dleak returns to the original small value.

  For this reason, for example, a threshold value dleak_th is set in advance, and it is possible to determine that radiation irradiation has ended when the leak data dleak becomes a value equal to or smaller than the threshold value dleak_th (see time t2 in the figure). It is.

  Note that the threshold value dleak_th in this case may be the same value as the threshold value when detecting the start of radiation irradiation by the detection method 2 described above, or may be set as a different value. Further, FIG. 20 shows a case where the reading process of leak data dleak is continued even after the end of radiation irradiation is detected at time t2, but actually, the end of radiation irradiation is as follows. Is detected, the reading process of the leak data dleak is stopped.

  Then, if it is configured to detect the end of radiation irradiation in this way, as shown in FIG. 19, the irradiation of radiation is terminated because the leak data dleak becomes a value equal to or less than the threshold value dleak_th. When this is detected (refer to “A” in FIG. 19, corresponding to time t 2 in FIG. 20), sequential application of the ON voltage to each scanning line 5 is started to read the main image data D. The process can be configured to start.

  If comprised in this way, as shown in FIG. 19, it will become possible to start the read-out process of this image data D immediately after detecting completion | finish of irradiation of a radiation, and after the read-out process of this image data D There is an advantage that it is possible to perform the above process at an early stage.

  Note that FIG. 19 shows a case where the leak data dleak is read out in the charge accumulation state in the detection method 1 shown in FIG. 13, but the illustration is also omitted in the detection method 2 shown in FIG. However, it is possible to continue the reading process of the leak data dleak in a state where an off voltage is applied to each scanning line 5 in the charge accumulation state, and to detect that the irradiation of radiation has been completed.

[Effect of applying ON voltage to multiple scanning lines]
As shown in FIGS. 13 and 14, the gate driver of the scanning drive means 15 in the reading process (detection method 1) of the image data d before radiographic imaging and the reset process (detection method 2) of each radiation detection element 7 are performed. By configuring the ON voltage to be applied to the plurality of lines L of the scanning line 5 from 15b, it is possible to reduce the time required for the entire process from the offset data O reading process even in the non-cooperative system. It is possible to obtain an excellent effect such as

  That is, as in the case of the cooperation method shown in FIGS. 39 and 40, in the case of the non-cooperation method in the present embodiment, in order to obtain the offset included in the main image data D, as shown in FIG. In addition, the offset data O reading process is performed by repeating the same sequence as the processing sequence up to the reading process of the main image data D. The effective accumulation time T shown in FIG. 21 will be described later.

  That is, when the detection method 1 is employed, as shown in FIG. 21, after the read processing of the main image data D, the on-voltage is applied to all the lines L1 to Lx of the scanning line 5 all at once, and the image data The d reading process (or the reset process of each radiation detection element 7 as shown in FIG. 21 without performing the reading operation) may be performed once or twice. Then, after the off-voltage is applied to each scanning line 5 for the same time as the charge accumulation state before the reading process of the main image data D to accumulate dark charges in each radiation detection element 7, the reading process of the offset data O is performed. I do. In this case, the radiation image capturing apparatus 1 is not irradiated with radiation in the charge accumulation state.

  When the detection method 2 is adopted, although not shown, each radiation detection is performed by applying an on-voltage to all the lines L1 to Lx of the scanning line 5 after the main image data D is read out. About one set or two sets of reset processing of the element 7 and reading processing of the leak data dleak performed in a state where the off voltage is applied to each scanning line 5 (in this case, the reading operation may not be performed) are performed. . Then, similarly to the case where the detection method 1 is adopted, after passing through the charge accumulation state, the offset data O is read out.

  As described above, in the present embodiment, after the reading process of the main image data D, the reading process of the image data d performed by simultaneously applying the on-voltage to all the lines L1 to Lx of the scanning line 5 and each radiation detection element. After the reset process 7 is performed once or twice, the state immediately shifts to the charge accumulation state, and the offset data O can be read.

  In the case of the non-cooperative method shown in FIG. 40, after performing the reading process of the main image data D, the on-voltage is sequentially applied to each line of the scanning line 5 to reset the radiation detection elements 7 and the like. As a result, the time required for resetting each radiation detection element 7 is increased, and the time required for the entire process from the reading process of the main image data D to the reading process of the offset data O is increased.

  On the other hand, as shown in FIG. 21, in the present embodiment, even if the same non-cooperation method is used, the detection method 1 and the detection method 2 are adopted, so that the post-read processing of the main image data D is performed. The time required for the reset processing of each radiation detection element 7 becomes very short. Therefore, it is possible to reduce the time required for the entire processing up to the reading processing of the offset data O.

  Further, as in the case of the cooperation method shown in FIG. 38, after the reading process of the main image data D is performed, an ON voltage is sequentially applied to each of the lines L1 to Lx of the scanning line 5 to thereby each radiation detection element 7. Compared with the case where the reset process or the like is performed, in the case of the non-cooperative method of the present embodiment shown in FIG. Therefore, the time required for the entire process up to the reading process of the offset data O can be shortened.

  Further, as described above, if the read processing of the leak data dleak is performed in the charge accumulation state before the read processing of the main image data D to detect the end of radiation irradiation, the time required for the charge accumulation state is shortened. Become. Therefore, the time required for the charge accumulation state before the offset data O reading process is similarly shortened, so that the time required for the entire process up to the offset data O reading process can be further reduced.

  In this case, in the charge accumulation state before the offset data O reading process, the off-voltage may be applied to each scanning line 5 for the same time as the charge accumulation state before the main image data D reading process. In the charge accumulation state before the offset data O reading process, it is not necessary to perform the leakage data dleak reading process as in the charge accumulation state before the main image data D reading process.

  In addition, during the reading process of the main image data D and the reading process of the offset data O, the reading process of the image data d performed by applying the on-voltage to all the lines L1 to Lx of the scanning line 5 all at once and each radiation detection. The reset process of the element 7 is basically a process performed to prevent a part of the main image data D that could not be read out by the read process of the main image data D from being read out in a form included in the offset data O. It is.

  In this case, as described above, if the reading process of the image data d or the resetting process of each radiation detection element 7 is performed once or twice (or about one set or two sets), the unread image is left unread. Data D (accurately corresponding to the data D) is sufficiently removed from each radiation detection element 7.

  Therefore, the number of times of the reading process of the image data d and the resetting process of each radiation detecting element 7 performed between the reading process of the main image data D and the reading process of the offset data O is the radiation detecting element 7, the reading efficiency or the resetting. In consideration of efficiency and the like, as described above, it is set in advance as a small number of times such as once or twice.

[Variation of how to apply on-voltage in processing before radiographic imaging]
By the way, in FIG.13, FIG.14, FIG.21, the read-out process of the image data d performed before radiographic imaging imaging, the read-out process of this image data D, and the read-out process of offset data O, or leak data dleak The case where the reset process of each radiation detection element 7 which is performed alternately with the readout process is performed by simultaneously applying the on-voltage to all the lines L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning driving unit 15. explained.

  In this case, for example, as shown in FIG. 22, when the gate driver 15b or the gate IC 15c constituting the gate driver 15b has a non-connected terminal p to which the scanning line 5 is not connected, the non-connection of the gate driver 15b The on voltage may be applied to all the terminals including the connection terminal p all at once, and the on voltage may be applied to all the lines L1 to Lx of the scanning line 5 all at once. The on-voltage is applied to all the lines L1 to Lx of the scanning line 5 by applying the on-voltage to only the terminals to which the scanning lines 5 are connected and not applying the on-voltage to the unconnected terminals p. May be applied simultaneously.

  In addition, the reading process of the image data d and the reset process of each radiation detection element 7 performed before radiographic image capturing and the like need to be performed by applying an ON voltage to the plurality of scanning lines 5 as described above. However, the on-voltage is not necessarily applied to all the lines L1 to Lx of the scanning line 5.

  Specifically, for example, the lines L1 to Lx of the scanning line 5 shown in FIG. 7 are divided into two in the vertical direction in the drawing, and the on-voltages to the lines L1 to Lm of the scanning line 5 are shown in FIG. And the application of the on-voltage to each of the lines Lm + 1 to Lx of the scanning line 5 can be alternately repeated.

  Further, it is not always necessary to apply the ON voltage to all the lines L1 to Lx of the scanning line 5 simultaneously, that is, simultaneously. Specifically, for example, as shown in FIG. 24, during the period from the transmission of the first pulse signal Sp1 to the correlated double sampling 19 from the control means 22 until the transmission of the second pulse signal Sp2. It is also possible to apply a turn-on voltage to the plurality of lines L of the scanning line 5 from the driver 15b by shifting the rising and falling timings.

  At this time, for example, as shown in FIG. 24, it is possible to apply the rising and falling of the on-voltage sequentially shifted, or although not shown, the rising and falling of the on-voltage are omitted. It is also possible to configure so that the voltages are shifted in a predetermined order or randomly shifted. However, the process of applying the on-voltage to each scanning line 5 by shifting the rising and falling of the on-voltage, as shown in FIG. 24, the first pulse signal Sp1 from the control means 22 to the correlated double sampling 19 is performed. It is necessary to be performed between the transmission of the first pulse signal Sp2 and the second transmission of the pulse signal Sp2.

  In FIG. 24 and FIGS. 26 to 28 to be described later, the pulse signals Sp1 and Sp2 are shown to be transmitted at a transmission interval larger than the transmission interval of the pulse signals Sp1 and Sp2 shown in FIG. However, this is an expression for making the figure easy to see, and does not mean that the transmission interval is actually increased.

  23 and 24 show the case where the detection method 1 shown in FIG. 13 and the like are adopted and the image data reading process is repeatedly performed before radiographic imaging, the detection method 2 shown in FIG. , And when the reset process of each radiation detection element 7 and the reading process of leak data dleak are alternately performed, as shown in FIG. 25, the ON voltage of each line L1 to Lm of the scanning line 5 is changed. The application and the application of the ON voltage to each of the lines Lm + 1 to Lx of the scanning line 5 are alternately repeated, or a plurality of lines of the scanning line 5 from the gate driver 15b as shown in FIG. It is possible to apply the ON voltage to L while shifting the rise and fall timings of the ON voltage. In FIG. 25, the reset process of each radiation detection element 7 is described as “R”, and the readout process of the leak data dleak is described as “L”.

  Further, as described above, for example, a sampling circuit that samples the value output from the amplifier circuit 18 at the timing of receiving the pulse signal Sp transmitted only once from the control means 22, for example, as shown in FIG. When the detection method 1 shown in FIG. 24 is used to read out image data before radiographic imaging, the charge reset switch 18c of the amplifier circuit 18 is turned on as shown in FIG. In a state in which charges can be accumulated in 18b, the gate driver 15 applies an on-voltage to all the scanning lines 5 or a part of all the scanning lines 5 to perform a reading process. After that, the pulse signal Sp is transmitted once from the control means 22, and the voltage value output from the amplifier circuit 18 at that time is output by the sampling circuit. Is sampling may be configured so as to read as the image data d.

  Further, when such a sampling circuit is used, for example, by adopting the detection method 2 shown in FIG. 26, the reset process of each radiation detection element 7 and the reading process of the leak data dleak are alternately performed. 28, the on-voltage is applied from the gate driver 15 to all of the scanning lines 5 or some of the scanning lines 5 to reset each radiation detection element 7. After the processing is performed, the charge reset switch 18c of the amplifier circuit 18 is turned off so that the charge can be accumulated in the capacitor 18b. For example, after a predetermined time has elapsed, the pulse signal Sp is sent from the control means 22 once. The voltage value transmitted from the amplifier circuit 18 at that time is sampled by the sampling circuit and read out as leak data dleak. It can be.

  Further, as described above, when the sampling circuit is configured to automatically perform sampling at a unique timing, the pulse signal Sp is transmitted from the control means 22 shown in FIGS. 27 and 28, for example. The sampling circuit can be configured to automatically perform sampling at a unique timing without transmitting the pulse signal Sp from the control means 22 at the timing. The same applies to the cases shown in FIGS.

  Further, as described above, the offset data O reading process is configured to repeat the same sequence as the processing sequence up to the reading process of the main image data D. Therefore, in the reading process of the image data d before the radiographic image capturing and the resetting process of each radiation detection element 7, for example, as shown in FIG. 23 and FIG. 25, an on voltage is alternately applied to each of the divided scanning lines 5. In the case where the ON voltage is applied to each scanning line 5 by shifting the rising and falling of the ON voltage as shown in FIG. 24 and FIGS. After that, the reset voltage of each radiation detection element 7 is performed by applying an ON voltage to each scanning line 5 in the same manner.

  As described above, according to the radiographic image capturing apparatus 1 according to the present embodiment, all the scanning lines 5 connected to the gate driver 15b from the gate driver 15b of the scan driving unit 15 or the radiographic image capturing before the radiographic image capturing, or An on-voltage is applied to some of the scanning lines 5 among all the scanning lines 5 connected to the gate driver 15b, and the readout process of the image data d and the readout process of the leak data dleak are alternately performed. Each radiation detection element 7 is configured to be reset.

  For example, when the correlated double sampling circuit 19 is used as the sampling circuit, the first pulse signal Sp1 is transmitted from the control means 22 to the correlated double sampling circuit 19 before radiographic imaging, and then the second pulse. The on-voltage is applied from the gate driver 15b to all the scanning lines 5 connected to the gate driver 15b or a plurality of scanning lines 5 of all the scanning lines 5 until the signal Sp2 is transmitted. Thus, the reset process of each radiation detection element 7 which is alternately performed with the reading process of the image data d and the reading process of the leak data dleak is performed.

  Therefore, after the reading process of the main image data D, the reading process of the image data d performed by applying the ON voltage to all the scanning lines 5 or a part of the scanning lines 5 and the reset process of each radiation detection element 7 are performed. After performing once or twice, it is possible to immediately shift to the charge accumulation state and perform the reading process of the offset data O. After the reading process of the main image data D is performed, the reading of the offset data O is performed. It is possible to reduce the time required for the entire processing up to the processing.

  In the radiographic image capturing apparatus 1 according to the present embodiment, it is possible to accurately detect at least the start of radiation irradiation based on the image data d and leak data dleak read out before radiographic image capturing. It becomes possible. Therefore, even when imaging is performed in a non-cooperative manner that cannot be coordinated with the radiation generation apparatus, the radiation image capturing apparatus 1 itself can accurately detect radiation irradiation and accurately perform radiation image capturing. Become.

[Effect of performing reading process of main image data D sequentially from the first scanning line]
In this embodiment, as shown in FIG. 13 and FIG. 14, the control unit 22 starts application of the on-voltage from the first line L <b> 1 of the scanning line 5 from the gate driver 15 b of the scanning driving unit 15. The on-voltage is sequentially applied to each of the lines L1 to Lx of the scanning line 5 to perform the reading process of the main image data D. By configuring in this way, the following effects can be obtained.

  As described above, the offset data O read in the offset data O reading process is data corresponding to the offset included in the main image data D. In the normal case, the offset is mainly This is considered to be caused by so-called dark charges generated by thermal excitation of the radiation detection element 7 itself by heat.

  However, according to the study by the present inventors, when the radiation image capturing apparatus 1 is irradiated with strong radiation, a so-called lag caused by charges generated in each radiation detection element 7 due to radiation irradiation is generated. It is known to occur. This lag also occurs when the radiation image capturing apparatus 1 is irradiated with a normal dose of radiation. However, this lag is not so large and can be ignored in many cases. May be a problem in the case of irradiation.

  The dark charges are relatively easily removed from each radiation detection element 7 by, for example, repeating the reset process of each radiation detection element and the reading process of the image data d. However, it has been found that the above lag does not disappear easily even when the reset process is repeated.

  The reason why the lag does not disappear easily in this way is that some of the electrons and holes generated in the radiation detection element 7 due to the irradiation of radiation are changed to a kind of metastable state, and the radiation This is considered to be because the state of loss of mobility in the detection element is maintained for a relatively long time. And the more intense the radiation, the more electrons and holes transition to this metastable energy level.

  And the electrons and holes in this metastable energy state are not always in the metastable energy level, but the energy level that is considered to be higher than the metastable energy little by little with thermal energy. Transition to the conduction band restores mobility. However, since the ratio is not necessarily large, it is considered that even if the reset process of each radiation detection element 7 is repeatedly performed, it does not easily disappear. There are still many unclear points about the mechanism of lag generation and persistence.

  As described above, when a lag occurs in each radiation detection element 7 due to radiation irradiation, the offset data O acquired in the acquisition process performed after radiographic imaging is included in the normal offset due to the dark charge as described above. In addition to (hereinafter referred to as Odark), an offset due to lag (hereinafter referred to as Olag) is also included.

Normally, in image processing after radiographic imaging, for each radiation detection element 7,
D ^* = DO (1)
The true image data D ^*, which is useful data generated in each radiation detection element 7 due to the irradiation of radiation, is calculated, and the final radiation is calculated based on the true image data D ^*. An image is generated.

  However, as described above, the offset data Olag includes the offset Olag due to the lag, thereby causing the following problems.

  First, when the occurrence state of the offset amount Odark caused by the dark charge and the offset amount Olag caused by the lag is observed, the dark charge is always generated in each radiation detection element 7, as shown by α in FIG. It is thought that it occurs at a constant rate per unit time. On the other hand, as shown by β in FIG. 29, the lag is generated from the time of radiation irradiation, and the generation rate per unit time (that is, the transition from the above-mentioned metastable energy level to the conduction band of higher energy level). It is considered that the rate is attenuated with respect to the elapsed time t from the start of radiation irradiation.

  Both the dark charge and the lag are accumulated in each radiation detection element 7 while the off voltage is applied to the scanning line 5 and the TFT 8 is turned off. Then, the accumulated amount is read as an offset amount Odark caused by dark charges and an offset amount Olag caused by lag. Therefore, the offset amount Odark caused by the dark charge and the offset amount Olag caused by the lag are obtained by integrating the generation rates per unit time indicated by α and β in FIG. 29 by the time when each TFT 8 is in the OFF state. Obtained as a value.

  That is, in the example of FIG. 21, as indicated by T in the figure, it was applied to the scanning line 5 in the last reset process or the like in the reset process or the like of each radiation detection element 7 before the read process of the offset data O. A time T (hereinafter referred to as an effective accumulation time T) from when the on-voltage is switched to the off-voltage to after the charge accumulation state is passed and when the on-voltage applied to the scanning line 5 is switched to the off-voltage in the offset data O reading process. )), The dark charges and lag accumulated in each radiation detection element 7 are offset due to dark charges included in the offset data O read by the offset data O reading process and offset due to the lag. Become Olag.

  Since the offset amount Odark caused by the dark charge and the offset amount Olag due to the lag are generated in this way, for example, as shown in FIG. 39, the on-state is detected when the start of radiation irradiation is detected or immediately before it is detected. The application of the on-voltage is started from the scanning line 5 (line Ln + 1 of the scanning line 5 in the case of FIG. 39) next to the scanning line 5 to which the voltage has been applied (in the case of FIG. 39, the line Ln of the scanning line 5). If the main image data D is read out, the following problems occur.

  After performing the reading process of the main image data D as shown in FIG. 39, the same sequence as the processing sequence until the reading process of the main image data D is repeated as shown in FIG. Is read out.

  In this case, as shown in FIG. 30, for example, when the line Ln of the scanning line 5 and the line Ln + 1 of the scanning line 5 are compared, the reset processing of the last radiation detection element 7 before the offset data O reading process is performed. The timing from when the off voltage is applied to when the on voltage applied in the offset data O reading process is switched to the off voltage is the line Ln + 1 of the scanning line 5 in the line Ln of the scanning line 5. Be faster than the case.

Therefore, during this period, the offset Olag due to the lag calculated by integrating the generation ratio per unit time is the scanning line 5 in the case of the line Ln + 1 of the scanning line 5 as shown in FIG. The value is larger than in the case of the line Ln of 5. In FIG. 30, the timing at which the ON voltage is applied to each scanning line 5 is indicated by arrows. Also, in FIG. 29 and FIG. 30, the illustration of the true image data D ^* resulting from the charges generated by the radiation irradiation is omitted. The true image data D ^* is usually much larger than dark charges and lags.

  If the radiation image is uniformly irradiated in a state where no subject is present in the radiation image capturing apparatus 1, the main image data D has the same value in each scanning line 5, that is, each radiation detection element 7. The offset data O to be read out should be the same for each scanning line 5 as well, but since the timing is different for each scanning line 5 as described above, the radiation is uniformly irradiated. Nevertheless, the reading process of the line Ln + 1 of the next scanning line 5, that is, the main image data D and the offset data O, is started at the minimum in the line Ln of the scanning line 5 where radiation irradiation is detected. It becomes maximum at the line Ln + 1 of the scanning line 5.

Therefore, when the true image data D ^* is calculated by subtracting the offset data O from the main image data D according to the above equation (1), the calculated true image data D ^* is, as shown in FIG. 5 gradually increases from the first line L1 to the line Ln, and the line Ln + 1 of the next scanning line 5 (that is, the scanning line 5 from which the reading process of the main image data D and the offset data O is started). Then, after the value is suddenly reduced and a step is generated in the true image data D ^* , the value is increased toward the final line Lx of the scanning line 5.

In FIG. 31 and FIG. 32 to be described later, the difference of the true image data D ^* for each scanning line 5 is expressed with high emphasis. As described above, since the effective accumulation time T is different for each scanning line 5, the offset amount Odark due to the dark charge contained in the offset data O also has a different value for each scanning line 5.

  However, when viewed for each scanning line 5, since the effective accumulation time T in the reading process of the main image data D and the effective accumulation time T in the reading process of the offset data O are the same, they are included in the main image data D. The offset Odark caused by the dark charge and the offset Odark caused by the dark charge contained in the offset data O have the same value. For this reason, the offset Odark caused by the dark charge is canceled by the subtraction process of the above equation (1).

As described above, when the reading method of the main image data D and the offset data O shown in FIGS. 39 and 40 is employed, there is a problem that a step is generated in the calculated true image data D ^* as described above. Arise.

  In addition, in the method shown in FIG. 39 and the like, the scanning line 5 (line Ln) to which the on-voltage is applied at the time when it is detected that radiation irradiation is started becomes a different scanning line 5 for each imaging. Then, since the reading process is started from the next scanning line 5 (line Ln + 1), the scanning line 5 from which the reading process of the image data D and the offset data O is started also changes for each photographing. Therefore, there is also a problem that the position where the step is generated on the radiation image, that is, the position of the line Ln and the line Ln + 1 of the scanning line 5 is changed every time imaging is performed.

Moreover, in this way a step is formed in the true image data D ^*, if for example such as with a radiation image is generated based on the true image data D ^* in diagnostic like in medical, lesions portion of the step There is a possibility that it is difficult to determine whether or not a part is imaged and is a lesioned part, or that a step is misdiagnosed as a lesioned part. In addition, when correcting the step of the true image data D ^* by image processing or the like, depending on the processing method, there is a possibility that information on a lesioned part imaged in the step portion may be lost.

  On the other hand, in the present embodiment, as described above, the reading process of the main image data D (see FIGS. 13 and 14) and the reading process of the offset data O performed in the same processing sequence (see FIG. 21). Then, the application of the on-voltage is started from the first line L1 of the scanning line 5, and the on-voltage is sequentially applied to each of the lines L1 to Lx of the scanning line 5 to perform the reading process of the main image data D and the offset data O. .

  Therefore, although illustration is omitted, as can be understood from FIG. 30, the offset Olag due to the lag in the offset data O is the maximum in the first line L1 of the scanning line 5 and the final line Lx of the scanning line 5. It becomes smaller as it goes, and becomes the minimum at the last line Lx of the scanning line 5. Therefore, the offset data O itself has the same tendency.

Therefore, when the true image data D ^* is calculated by subtracting the offset data O from the main image data D in accordance with the above equation (1), the calculated true image data D ^* is obtained as shown in FIG. 5 is the smallest at the first line L1 and becomes larger toward the last line Lx of the scanning line 5, and the largest at the last line Lx of the scanning line 5, so that no step appears in the true image data D ^* .

As described above, as in the present embodiment, in the reading process of the main image data D and the offset data O, the reading process is performed by sequentially applying the ON voltage in order from the first line L1 of the scanning line 5. Thus, it is possible to accurately prevent a step from being generated in the true image data D ^* .

It is included in the offset data O based on the generation rate of the lag unit time described above, the above-described effective accumulation time T, the time from when the radiation is applied until the on-voltage is applied in the readout process, and the like. It is also possible to configure so as to calculate the offset Olag due to the lag. In this case, the offset amount Olag due to the calculated lag is subtracted from the read offset data O to calculate the offset amount Odark caused by the dark charge and subtracted from the main image data D to obtain the true image data D ^*. Can be configured to calculate.

  Further, in the present embodiment, as described above, in the reading process of the main image data D and the offset data O, the reading process is performed by sequentially applying the ON voltage in order from the first line L1 of the scanning line 5. For example, the application of the on-voltage is started from the last line Lx of the scanning line 5, and the on-voltage is sequentially applied in the order of the lines Lx, Lx-1, ..., L2, L1 of the scanning line 5. Even if configured, the same effect can be obtained.

  That is, in the reading process of the main image data D and the offset data O, the ON voltage is applied from the scanning line 5 (that is, the first line L1 or the last line Lx of the scanning line 5) at the end of the detection unit P (see FIG. 7 and the like). The same effect can be obtained if the reading process is performed by sequentially applying the ON voltage to each scanning line 5 and starting the reading process.

[Treatment for loss of some useful data]
Incidentally, for example, as shown in FIG. 13 and the like, the image data d is read out by applying an on-voltage to each of the lines L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning driving unit 15 before radiographic image capturing. In the case of the detection method 1 described above, as described above, when an on-voltage is applied at the start of radiation irradiation, each radiation detection element 7 connected to each scanning line 5 detects each radiation by radiation irradiation. A part of useful data generated in the element 7 is lost.

  Therefore, the main image data D read from each of the radiation detection elements 7 in the subsequent read processing of the main image data D becomes the main image data D in which a part of useful data is lost. The same applies to the detection method 2 described above.

  That is, when radiation irradiation is started during the leak data dleak reading process (see L in FIG. 14), the main image data D is hardly affected, but the lines L1 to Lx of the scanning line 5 are not affected. When radiation irradiation is started during the reset process (see R in FIG. 14) of each radiation detection element 7 performed by applying an ON voltage, the radiation detection element 7 is generated by radiation irradiation. A part of useful data is lost from the inside of each radiation detection element 7, and the main image data D read from each radiation detection element 7 in the subsequent reading process of the main image data D is a part of useful data. Is the main image data D lost.

  In such a case, if the present image data D is invalidated as described above because part of the useful data is lost, all the data read from each radiation detection element 7 is used. The actual image data D must be invalidated, and the meaning of performing radiographic imaging is lost. Therefore, in the present embodiment, the main image data D is not invalidated.

  In the above case, it can be considered that a part of the data is lost at a certain rate for all the main image data D read from each radiation detection element 7. Therefore, compared to the case where all the main image data D is read without losing the data, each read main image data D is only reduced at a constant rate as a whole. Except for the cases shown in FIGS. 33 and 34, no problem occurs.

  Therefore, as shown in FIG. 13 and FIG. 14 and the like, in the process before radiographic image capturing, an on-voltage is applied from the gate driver 15b to each of the plurality of scanning lines 5 to read out the image data d and each radiation detection element. When the reset process 7 is performed, the read main image data D can be directly used as the main image data D.

  If necessary, for example, the read main image data D is multiplied by a predetermined constant larger than 1 to increase the main image data D at a constant rate. It is also possible to restore each main image data D that has been output to each main image data D when the data is read without being lost.

  By the way, in the gate IC 15c (see FIGS. 6 and 22) constituting the gate driver 15b of the scanning drive means 15, when a signal is received from the control means 22, the ON voltage is simultaneously applied to each terminal to which each scanning line 5 is connected. The voltage applied to each scanning line 5 is switched to the on voltage or the off voltage all at once, for example, by applying the voltage or switching the on voltage applied to each terminal to the off voltage. There is.

  And, when the voltage applied to each terminal is switched from the off voltage to the on voltage or simultaneously from the on voltage to the off voltage, a large current flows in the IC to prevent the IC from being damaged or destroyed. Therefore, some gate ICs 15c are configured such that, for example, as shown in FIG. 33, when a signal is received, the timing for switching the voltage applied to each terminal is slightly delayed.

  FIG. 33 shows an example of the delay time for each terminal when a signal for switching the ON voltage applied to each terminal to the OFF voltage at the same time is received, and a terminal with a delay time of 0 [ns] is shown. The terminal having the maximum delay time (300 [ns] in the case of FIG. 33) corresponds to the terminal at the center of the gate IC 15c, and corresponds to the terminal at the end of the gate IC 15c. 33 and FIG. 34, which will be described later, show a case where the gate driver 15b is composed of five gate ICs 15c. The horizontal axis of the graph indicates the line number of the scanning line 5 (that is, the terminal of the gate driver 15b). Number).

  As described above, when the timing of switching from the on-voltage to the off-voltage is delayed at each terminal of each gate IC 15c, for example, in the example using the detection method 1 shown in FIG. 13, the last image data d that has detected the start of radiation irradiation. In this reading process, the timing at which the ON voltage applied to each scanning line 5 is switched to the OFF voltage is shifted.

  Then, in the scanning line 5 connected to the terminal that switches to the off voltage earlier (that is, the terminal having a short delay time), each TFT 8 is switched to the off state earlier, and each radiation detection element 7 is irradiated with radiation. More of the generated useful charge is accumulated.

  Further, in the scanning line 5 connected to the terminal that switches to the off voltage later (that is, the terminal that has a longer delay time), each TFT 8 switches to the off state later, so that the radiation of the scanning line 5 is changed before the switching to the off state. More useful charges generated in each radiation detection element 7 due to irradiation flow out to the signal line 6, and the amount of charges accumulated in each radiation detection element 7 decreases.

  Therefore, as shown in FIG. 34, there is a case where a so-called wavy profile appears in a signal value read after irradiation of radiation, that is, main image data D, according to the delay time related to voltage switching as described above. is there. This tendency is the same even when the detection method 2 shown in FIG. 14 is adopted.

  Such variation on the main image data D becomes smaller as the variation in the delay time is smaller. Therefore, as one method for eliminating such variations in the main image data D, a gate IC 15c having no variation in delay time for each terminal as described above or having a small variation in delay time within an allowable range is used. Use.

  Further, for example, a signal for switching the voltage applied to each terminal of the gate IC 15c is received by another control circuit instead of the gate IC 15c, and a signal is simultaneously transmitted from the control circuit to each terminal of the gate IC 15c. For example, the voltage applied from the gate IC 15c to each scanning line 5 can be switched at each terminal at the same time.

  Furthermore, each main image data D read out as described above can be configured to be restored by subsequent image processing. In this case, for example, the delay time t (a) for each terminal of each gate IC 15c (that is, for each scanning line 5) is obtained in advance. Note that a in t (a) represents the line number of each scanning line 5.

  Further, for example, the radiation image capturing apparatus 1 is configured to repeat the reading process of the leak data dleak after the transition to the charge accumulation state as shown in FIG. Configure. Then, the control means 22 is configured to measure the time from when the start of radiation irradiation is detected until the end of irradiation is detected. Hereinafter, this time is referred to as radiation irradiation time t.

As described above, the main image data D in which charge is lost due to the delay time in the gate IC 15c, that is, the main image data D in which variation occurs due to the delay time as shown in FIG. Assuming data D (a), the ratio of the original image data D that should be read out to the original image data D (a) that lacks electric charge is expressed by the irradiation time of radiation as shown in the following equation (2). It is equal to the ratio of t to the time obtained by subtracting the delay time t (a) from the irradiation time t of radiation.
D: D (a) = t: (t-t (a)) (2)

Therefore, the original image data D to be originally read is based on the actually read main image data D (a) in which the charge deficiency has occurred, the delay time t (a), and the irradiation time t.
D = D (a) · t / (t−t (a)) (3)
Can be calculated by calculating.

  As described above, the influence of the delay time t (a) in the gate IC 15c as described above is restored by image processing performed by the radiographic imaging apparatus 1 or a console (not shown) as an external apparatus after radiographic imaging. Is also possible.

  Note that, as shown in FIG. 24, when performing read processing (see FIG. 13) of image data d before radiographic imaging (see FIG. 13) and reset processing of each radiation detection element 7 (see FIG. 14), Even when the rise and fall of the on-voltage applied to the scanning line 5 are shifted in a predetermined order or at random, the rise and fall of the on-voltage at each terminal of the gate driver 15b and the gate IC 15c. Can be obtained in advance in the same manner as the delay time t (a), and the main image data D can be restored by image processing in the same manner as described above.

  Further, as shown in FIG. 23, each line L1 to Lx of the scanning line 5 is divided into two to apply an ON voltage to each line L1 to Lm of the scanning line 5, and to each line Lm + 1 of the scanning line 5. Even when the ON voltage application to Lx is repeated alternately, as described above, there is no variation in the delay time t (a) or a sufficiently small gate IC 15c is used, or another control is performed. A circuit may be provided, or the main image data D may be restored by subsequent image processing.

  However, in the case of FIG. 23, the scanning line 5 to which the on-voltage is applied at the time when it is detected that radiation irradiation has started is half of all the scanning lines 5. Therefore, for example, when the irradiation start is detected when an on-voltage is applied to each of the lines L1 to Lm of the scanning line 5, each of the lines connected to the lines L1 to Lm of the scanning line 5 is detected. In the radiation detection element 7, a defect occurs in the main image data D, but in each radiation detection element 7 connected to the other lines Lm + 1 to Lx of the scanning line 5, no defect occurs in the main image data D. The same applies to the reverse case.

  Therefore, as shown in FIG. 23, each of the lines L1 to Lx of the scanning line 5 is divided into two, or each of the scanning lines 5 is divided into a plurality of ranges to switch between the on voltage and the off voltage for each range. In such a case, it is configured to accurately determine which scanning line 5 is the radiation detection element 7 to which the deficient main image data D is connected. It is necessary to configure so that only the main image data D read from the radiation detection element 7 is repaired.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging device 5 Scanning line 6 Signal line 7 Radiation detection element 8 TFT (switch means)
15 Scan Driver 15b Gate Driver 17 Readout Circuit 18 Amplifier 18a Operational Amplifier 18b Capacitor 18c Charge Reset Switch 19 Correlated Double Sampling Circuit (Sampling Circuit)
22 Control means D Main image data (image data as the main image)
d Image data dleak Leak data L1, Lx Scanning line O at the endmost part Offset data P Detection part q Charge r Region Sp1, Sp2 Pulse signal Vin, Vfi Voltage value (value)
Vfi-Vin difference

Claims (6)

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 comprising a gate driver for switching between and applying an on voltage and an off voltage to each scanning line;
Switch means for releasing the charge accumulated in the radiation detection element to the signal line when an on-voltage is applied via the scanning line;
A readout circuit comprising an amplification circuit and a sampling circuit for converting and reading out the electric charge emitted from the radiation detection element to the signal line;
Control means for controlling at least the scanning drive means and the readout circuit to perform a readout process of the data from each radiation detection element;
With
Before the radiographic image capturing, the control unit is configured to transfer all the scanning lines connected to the gate driver from the gate driver of the scanning driving unit or all the scanning lines connected to the gate driver. A reset process for each of the radiation detection elements performed by applying an on voltage to a part of the plurality of scanning lines, and each of the radiations via the switch means in a state in which an off voltage is applied to each of the scanning lines. Based on the read leak data, the sampling circuit samples the value output from the amplifier circuit corresponding to the charge leaked from the detection element and reads the leak data as leak data. A radiation image capturing apparatus for detecting that radiation irradiation has started. When the sampling circuit receives the pulse signal twice from the control means, the amplification circuit receives the first pulse signal from the value output from the amplification circuit when the second pulse signal is received. A correlated double sampling circuit that outputs the difference obtained by subtracting the value output from the circuit as the data;
The control means, when performing reading processing of the leak data before radiographic imaging, outputs the pulse signal twice to the correlated double sampling circuit with an off voltage applied to each scanning line. The radiographic image capturing apparatus according to claim 1, wherein data corresponding to electric charges that are transmitted and leak from each of the radiation detection elements is read as the leak data via the switch unit. The amplifier circuit is composed of an operational amplifier and a charge amplifier circuit in which a capacitor and a charge reset switch are connected in parallel to the operational amplifier, and an output value is output according to the amount of charge accumulated in the capacitor,
When the resetting process of each radiation detection element is performed before radiographic image capturing, the control unit turns on the gate of the scan driving unit with the charge reset switch of the amplifier circuit turned on. The driver applies an on-voltage to all of the scanning lines connected to the gate driver or to some of the scanning lines of all of the scanning lines connected to the gate driver, and The radiographic imaging apparatus according to claim 1, wherein a reset process is performed.   When the control means causes the reset processing of each radiation detection element to be performed before radiographic imaging, all the scanning lines connected to the gate driver from the gate driver of the scanning driving means, or An on-voltage is simultaneously applied to a part of the plurality of scanning lines among all the scanning lines connected to the gate driver to perform reset processing of the radiation detection elements. The radiographic imaging device according to any one of claims 1 to 3. When the control means detects that radiation irradiation has started, it applies an off voltage to all the scanning lines from the scanning drive means, and after switching each switch means to an off state and shifting to a charge accumulation state, From the scanning drive means, application of an on-voltage is started from the scanning line at the end of the detection unit, and an on-voltage is sequentially applied to each of the scanning lines. radiographic imaging apparatus according to any one of claims 1 to 4, characterized in that to perform the reading processing of the image data. Wherein, after said to perform the reading processing of the image data as the image from the radiation detection elements, to perform a predetermined number of times the reset process before Symbol each radiation detection element before the radiation image capturing, then, In a state where no radiation is irradiated, an off voltage is applied to all the scanning lines from the scanning driving means for the same time as the charge accumulation state before reading processing of the image data as the main image. 6. The radiographic image capturing apparatus according to claim 5 , wherein after the dark charge is accumulated, offset data reading processing for reading the accumulated dark charge as offset data is performed.