JP2013128727A - Radiographic imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic imaging apparatus capable of accurately detecting irradiation start of radiation by the apparatus itself and accurately performing radiographic imaging even when the dose rate of the radiation irradiated to the apparatus is low.SOLUTION: The control means 22 of the radiographic imaging apparatus 1 makes read processing of image data d for irradiation start detection be repeatedly performed by applying an ON voltage to all scanning lines 5 or some scanning lines 5 connected to a gate driver 15b before radiographic imaging, performs processing of calculating a difference Δd between the read image data d for the irradiation start detection and the image data d for the irradiation start detection read in the read processing immediately before for each read processing, adds the calculated difference Δd to the integrated value ΣΔd of the differences by every time the difference Δd is calculated, and detects that the irradiation of the radiation is started at the point of time when the integrated value ΣΔd of the differences to which the difference Δd is added exceeds a set threshold Σth.

Description

  The present invention relates to a radiographic imaging apparatus, and more particularly to a radiographic imaging apparatus that performs radiographic imaging by detecting the start of radiation irradiation by the apparatus 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 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 device is known as an FPD (Flat Panel Detector), and is conventionally configured as a so-called special-purpose machine that is integrally formed with a support base (see, for example, Patent Document 1). In recent years, a portable radiographic imaging apparatus in which a radiation detection element or the like is housed in a casing and can be carried has been developed and put into practical use (for example, see Patent Documents 2 and 3).

  In such a radiographic imaging apparatus, for example, as shown in FIG. 3 and the like, which will 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 of thin film transistors (hereinafter referred to as TFTs) 8.

  In general, radiographic imaging is performed by irradiating radiation from the radiation source of the radiation generating apparatus to the radiographic imaging apparatus through the body of the subject, that is, the subject. Then, after imaging, an ON voltage is sequentially applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5 so that each TFT 8 is sequentially turned on, and is generated and accumulated in each radiation detecting element 7 by radiation irradiation. The formed electric charges are sequentially discharged to the signal lines 6 and read out as image data D by the readout circuits 17 respectively.

  By the way, in the conventional radiographic imaging system using such a radiographic imaging apparatus, radiographic imaging was performed by exchanging signals between the radiographic imaging apparatus and the radiation generating apparatus. However, for example, when the manufacturers of the radiographic imaging device and the radiation generator are different, it may not always be easy to construct an interface between them, or the interface may not be constructed. is there.

  In such a case, when viewed from the side of the radiographic imaging device, it is not known at what timing the radiation is emitted from the radiation source. Therefore, in such a case, the radiographic imaging device needs to be configured so that the device itself can detect that radiation has been emitted from the radiation source. Various types of radiographic image capturing apparatuses that can detect the start of radiation irradiation and perform image capturing with the radiographic image capturing apparatus itself have been developed.

  As a result of various studies on methods for detecting that radiation has been emitted by the radiation imaging apparatus itself, the present inventors can accurately detect that radiation has been emitted by the radiation imaging apparatus itself. Several detection methods could be found (see, for example, Patent Documents 4 and 5).

  In these detection methods, as will be described in detail later, image data and leak data are read out before the radiation image capturing apparatus is irradiated with radiation. Then, the value of the read image data or the like is monitored by utilizing the fact that the value of the read image data or the like is significantly larger than the value of the image data or the like that has been read until then when the radiation is irradiated. For example, when the value of image data or the like exceeds a set threshold value, for example, it is configured to detect that radiation irradiation has started.

  The leak data will be described later. Further, in the case where the image data reading process is performed before radiographic image capturing, it is distinguished from image data as a so-called main image (that is, image data obtained by capturing an object) read after radiographic image capturing. In addition, the image data read before radiographic imaging is referred to as irradiation start detection image data.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 International Publication No. 2011-152093 Pamphlet International Publication No. 2011/13517 Pamphlet

  By the way, as described above, when configured to detect the start of radiation irradiation when the value of the image data for detection of irradiation start and the value of leak data read out before capturing the radiographic image exceed the threshold value, the radiographic image capturing device If the dose rate (ie, the dose per unit time) of the radiation applied to the sensor is small, even if the radiation image detection apparatus starts reading the radiation image and the read-out image data for detecting the start of irradiation increases, In the end, there is a possibility that the start of radiation irradiation cannot be detected.

  Therefore, in the radiographic imaging apparatus, even when the dose rate of the radiation applied to the radiographic imaging apparatus is small as described above, the radiographic imaging apparatus accurately detects the start of radiation irradiation and accurately performs radiographic imaging. It is required to be configured so that As a result of repeated research, the present inventors have further improved each detection method described in Patent Document 4 and Patent Document 5 to accurately detect the start of radiation irradiation even in the above case. I was able to find out what I could do.

  The present invention has been made in view of the above points, and even when the dose rate of radiation irradiated to the apparatus is small, the apparatus itself accurately detects the start of radiation irradiation and accurately performs radiographic imaging. An object of the present invention is to provide a radiographic imaging apparatus capable of performing the above-described operation.

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, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines When,
A scanning driving means comprising a gate driver for switching on and applying an on voltage and an off voltage to each scanning line;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Before radiographic imaging, from the gate driver of the scan driving means, all the scanning lines connected to the gate driver, or a part of all the scanning lines connected to the gate driver While repeatedly performing a reading process of reading the image data for irradiation start detection by applying an on-voltage to the plurality of scanning lines,
A difference between the read image data for detecting the start of irradiation and the image data for detecting the start of irradiation read in the read process immediately before the read process for reading the image data for detecting the start of irradiation is calculated. The processing is performed for each reading process of the image data for detecting the irradiation start,
Each time the difference is calculated, the calculated difference is added to the integrated value of the difference so far, and the integrated value of the difference obtained by adding the difference exceeds the set threshold value. It is characterized by detecting that has started.

Moreover, the radiographic imaging device of the present invention is
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines When,
A scanning driving means comprising a gate driver for switching on and applying an on voltage and an off voltage to each scanning line;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Before radiographic imaging, from the gate driver of the scan driving means, all the scanning lines connected to the gate driver, or a part of all the scanning lines connected to the gate driver A reset process of each radiation detection element performed by applying an ON voltage to a plurality of the scanning lines, and leakage from each radiation detection element via the switch means in a state where an OFF voltage is applied to each scanning line While alternately performing a leak data read process for converting the charge into leak data,
A process of calculating a difference between the read leak data and the leak data read in the read process immediately before the read process for reading the leak data is performed for each leak data read process,
Each time the difference is calculated, the calculated difference is added to the integrated value of the difference so far, and the integrated value of the difference obtained by adding the difference exceeds the set threshold value. It is characterized by detecting that has started.

  According to the radiographic imaging apparatus of the system as in the present invention, since the above integrated value does not exceed the threshold value before the radiation irradiation to the radiographic imaging apparatus is started, erroneous detection of the start of radiation irradiation is detected. Accurately prevented. When radiation irradiation is started, the integrated value increases and exceeds the threshold value. Therefore, by configuring as described above, it is possible to accurately detect the start of radiation irradiation to the radiographic imaging apparatus even when the radiation dose applied to the radiographic imaging apparatus is very small.

  In addition, the voltage applied to all the scanning lines 5 in the readout process of image data for detecting the start of irradiation before radiographic imaging and the reset process of each radiation detection element 7 performed alternately with the readout process of leak data Are simultaneously switched between the on-voltage and the off-voltage, the period during which each TFT 8 is turned off is shortened, and the charge remaining in each radiation detection element 7 is frequently applied to the signal line 6. It will be released.

  For this reason, the amount of dark charge accumulated in each radiation detection element 7 is reduced, and the S / N ratio of the image data d for irradiation start detection read from each radiation detection element 7 can be improved. . And since the S / N ratio of the data read in this way improves, even when the dose rate of the radiation irradiated to the radiographic imaging apparatus 1 is small, it becomes possible to detect the radiation irradiation start more accurately. .

It is sectional drawing of the radiographic imaging apparatus which concerns on this embodiment. It is a top view which shows the structure of the board | substrate of a radiographic imaging apparatus. 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. 6 is a timing chart showing charge reset switches, pulse signals, and TFT on / off timings in image data read processing. It is the graph which plotted the image data for irradiation start detection read out in time series. 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 for explaining the timing of applying an on-voltage to each scanning line in the detection method 1; 6 is a timing chart for explaining the timing of applying an ON voltage to each scanning line in the detection method 2. In the detection method 1, an example in which the reading process of image data before radiographic imaging is performed by shifting the rising and falling of the on-voltage applied to a plurality of scanning lines while transmitting the pulse signal twice. It is a timing chart to represent. 7 is a timing chart illustrating an example of a case where an on-voltage is applied to each scanning line by shifting the rising or falling timing of an on-voltage when resetting each radiation detection element in the detection method. 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. 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 graph showing the temporal change and threshold value of the integrated value obtained by calculating the read image data for irradiation start detection by the integration method. 10 is a timing chart from the main image data reading process to the offset data reading process in the case of the detection method 1 shown in FIG. 9.

  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 electrical 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 present invention can also be applied to a so-called dedicated machine type radiographic imaging apparatus formed integrally with a support base or the like. Is possible.

  FIG. 1 is a cross-sectional view of a radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a plan view illustrating a configuration of a substrate of the radiographic image capturing apparatus.

  As shown in FIG. 1, the radiographic image capturing apparatus 1 includes a scintillator 3, a substrate 4, and the like in a housing 2 formed of a carbon plate having a radiation incident surface R that is a surface irradiated with radiation. The configured sensor panel SP is housed. Although not shown in FIG. 1, in the present embodiment, the housing 2 is provided with an antenna device 41 (see FIG. 3 described later) that is a communication unit that transmits image data D and the like in a wireless manner. Yes.

  As shown in FIG. 1, a base 31 is disposed in the housing 2, and a lead thin plate or the like (not shown) is provided on the radiation incident surface R side (hereinafter simply referred to as the upper surface side) of the base 31. A substrate 4 is provided. A scintillator 3 that converts irradiated radiation into light such as visible light is provided on the scintillator substrate 34 on the upper surface side of the substrate 4, and the scintillator 3 is provided facing the substrate 4 side.

  Further, on the lower surface side of the base 31, a PCB substrate 33 on which electronic components 32 and the like are arranged, a battery 24, and the like are attached. In this way, the sensor panel SP is formed by the base 31, the substrate 4, and the like. In the present embodiment, the buffer material 35 is provided between the sensor panel SP and the side surface of the housing 2.

  In the present embodiment, the substrate 4 is formed of a glass substrate, and as shown in FIG. 2, a plurality of scanning lines 5 and a plurality of signals are provided on the upper surface 4a of the substrate 4 (that is, the surface facing the scintillator 3). The lines 6 are arranged so as to intersect each other. A radiation detection element 7 is provided 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.

  In this way, the entire small region r provided with a plurality of radiation detection elements 7 arranged in a two-dimensional form (matrix) in each small region r partitioned by the scanning lines 5 and the signal lines 6, that is, FIG. The area indicated by the alternate long and short dash line in FIG. In the present embodiment, a photodiode is used as the radiation detection element 7, but a phototransistor or the like can also be used, for example.

  Here, the circuit configuration of the radiation image capturing apparatus 1 will be described. FIG. 3 is a block diagram illustrating an equivalent circuit of the radiographic image capturing apparatus 1 according to the present embodiment, and FIG. 4 is a block diagram illustrating an equivalent circuit for one pixel constituting the detection unit P.

  The first electrode 7a of each radiation detection element 7 is connected to a source electrode 8s (see “S” in FIG. 3 and FIG. 4) of a TFT 8 serving as a switch means. Further, the drain electrode 8d and the gate electrode 8g (see “D” and “G” in FIGS. 3 and 4) of the TFT 8 are connected to the signal line 6 and the scanning line 5, respectively.

  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. Further, when a turn-off voltage is applied to the gate electrode 8 g via the scanning line 5, the gate electrode 8 g is turned off, the discharge of charge from the radiation detection element 7 to the signal line 6 is stopped, and charge is accumulated in the radiation detection element 7. It is supposed to let you.

  In the present embodiment, as shown in FIGS. 2 and 3, the bias line is applied to the second electrode 7 b of each radiation detection element 7 at a rate of one for each radiation detection element 7 in a row on the substrate 4. 9 is connected, and each bias line 9 is bound to the connection 10 at a position outside the detection portion P of the substrate 4. The connection 10 is connected to a bias power supply 14 (see FIGS. 3 and 4) via an input / output terminal 11 (also referred to as a pad, see FIG. 2). The connection 10 and each bias line 9 are connected from the bias power supply 14 to the connection. Thus, a reverse bias voltage is applied to the second electrode 7b of each radiation detection element 7.

  On the other hand, each scanning line 5 is connected to the gate driver 15b of the scanning driving means 15 via the input / output terminal 11, respectively. In the scanning drive means 15, an ON voltage and an OFF voltage are supplied from the power supply circuit 15a to the gate driver 15b via the wiring 15c, and applied to the lines L1 to Lx of the scanning line 5 by the gate driver 15b. The voltage is switched between an on voltage and an off voltage.

  Each signal line 6 is connected to each readout circuit 17 built in the readout IC 16 via each input / output terminal 11. In the present embodiment, the readout circuit 17 is mainly composed of an amplification circuit 18 and a correlated double sampling circuit 19. An analog multiplexer 21 and an A / D converter 20 are further provided in the read IC 16. 3 and 4, the correlated double sampling circuit 19 is represented as CDS.

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. ing.

  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

  In the process of reading the image data D from each radiation detection element 7, as shown in FIG. 5, the TFT 8 of each radiation detection element 7 is in a state where the charge reset switch 18c of the amplifier circuit 18 is turned off. When the ON voltage is applied to the signal line 6, electric charges are discharged from the radiation detection elements 7 to the signal lines 6, and flow into the capacitors 18 b of the amplification circuits 18 of the readout circuits 17 to be accumulated. In the amplifier circuit 18, a voltage value corresponding to the amount of charge accumulated in the capacitor 18b is output from the output side of the operational amplifier 18a.

  The correlated double sampling circuit 19 outputs an increase in the output value from the amplifier circuit 18 before and after the charge flows from each radiation detection element 7 as analog value image data D to the downstream side. The output image data D is sequentially transmitted to the A / D converter 20 via the analog multiplexer 21, and is sequentially converted into digital image data D by the A / D converter 20 and stored in the storage means 23. Output and save sequentially. In this way, the reading process of the image data D is performed.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc., not shown, connected to a bus, an FPGA (Field Programmable Gate Array), or the like. It is configured. It may be configured by a dedicated control circuit.

  Then, the control unit 22 controls the operation of each functional unit of the radiographic imaging apparatus 1 such as controlling the scanning driving unit 15 and the readout circuit 17 to perform the readout process of the image data D as described above. It has become. As shown in FIGS. 3 and 4, the control means 22 is connected to a storage means 23 composed of SRAM (Static RAM), SDRAM (Synchronous DRAM) or the like.

  In the present embodiment, the control unit 22 is connected to the antenna device 41 described above, and is further necessary for each functional unit such as the scanning drive unit 15, the readout circuit 17, the storage unit 23, and the bias power source 14. A battery 24 for supplying power is connected.

[How to detect the start of radiation irradiation]
Next, a method for detecting the start of radiation irradiation in the radiographic imaging apparatus 1 according to the present embodiment will be described.

[About the base detection method]
In the present embodiment, as described above, an interface is not established between the radiographic imaging apparatus 1 and a radiation generation apparatus (not shown), and radiation is emitted from the radiation source of the radiation generation apparatus by the radiographic imaging apparatus 1 itself. Is configured to detect that. And in the radiographic imaging device 1 which concerns on this embodiment, the detection method based on the detection method described in patent document 4 mentioned above and patent document 5 is employ | adopted. Hereinafter, this basic detection method will be briefly described.

[Detection method 1]
The detection method 1 is a detection method described in Patent Document 4 described above. For details of this detection method, refer to this document.

  In this detection method, the control means 22 of the radiographic image capturing apparatus 1 controls the scanning drive means 15 and the respective readout circuits 17 and the like in the same manner as the image data D readout process shown in FIG. Then, the reading processing of the above-described irradiation start detection image data (hereinafter referred to as irradiation start detection image data d in order to distinguish from the image data D as the main image) from each radiation detection element 7 is performed. It is designed to be repeated.

  When the radiation image capturing apparatus 1 is irradiated with radiation, a charge is newly generated in each radiation detection element 7, so that the value of the read image data d for irradiation start detection is read as shown in FIG. It becomes larger than the value of the image data d for irradiation start detection read out before that (see time t1 in FIG. 6). Therefore, this is used to detect the start of radiation irradiation to the radiation image capturing apparatus 1.

[Detection method 2]
The detection method 2 is a detection method described in Patent Document 5 described above. For details of this detection method, refer to this document.

  In this detection method, the control means 22 of the radiographic image capturing apparatus 1 is configured to repeatedly read out the leak data dleak before radiographic image capturing. As shown in FIG. 7, 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 reading process of the leak data dleak, as shown in FIG. 8, each reading 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 data Sp1 and Sp2 are transmitted to 17 correlated double sampling circuits 19 (see CDS in FIGS. 3 and 4), and the leak data dleak is read out.

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

  When the leak data dleak is configured to be read out in this way, when radiation irradiation to the radiation image capturing apparatus 1 is started, electromagnetic waves converted from the radiation by the scintillator 3 (see FIG. 1) are irradiated to each TFT 8. Is done. As a result, the inventors have found that the charges q (see FIG. 7) leaking from the radiation detection elements 7 via the TFTs 8 increase.

  Therefore, when the radiation image capturing apparatus 1 is irradiated with radiation, the charge q leaked from each radiation detection element 7 via each TFT 8 increases, and the value of the leaked data dleak to be read increases. Therefore, this is used to detect the start of radiation irradiation to the radiation image capturing apparatus 1.

  In this detection method 2, the reading process of the leak data dleak is performed in a state where each TFT 8 is turned off as described above. If each TFT 8 is left in this OFF state, dark charges (also referred to as dark current or the like) generated in each radiation detection element 7 are continuously accumulated in each radiation detection element 7.

  Therefore, when the detection method 2 is employed, that is, when the leak data dleak is read repeatedly before radiographic imaging, the leak data dleak read process and the next leak data dleak are usually read. Between each process, it is comprised so that the reset process of each radiation detection element 7 may be performed. That is, the detection method 2 is configured such that the reading process of the leak data dleak and the reset process of each radiation detection element 7 are alternately performed.

[Improvements from detection methods 1 and 2 described in Patent Documents 4 and 5]
Next, in the radiographic image capturing apparatus 1 according to the present embodiment, improvements from the detection method 1 described in Patent Document 4 and the detection method 2 described in Patent Document 5 will be described. The operation of the radiographic image capturing apparatus 1 according to this embodiment will also be described.

[Applying ON voltage to all or multiple scanning lines]
In the above detection method 1 in Patent Document 4, the reading process of the image data d for irradiation start detection before radiographic image capturing is performed from the gate driver 15b (see FIG. 3) of the scanning driving unit 15 to each line L1 of the scanning line 5. The on-voltage is sequentially applied to .about.Lx to read the image data d for detecting the start of irradiation.

  Further, in the detection method 2 in Patent Document 5, in the reset process of each radiation detection element 7 that is alternately performed with the reading process of the leak data dleak before the radiographic imaging, the scanning drive unit 15 performs the same as described above. The reset process is performed by sequentially applying ON voltages to the lines L1 to Lx of the scanning line 5 from the gate driver 15b.

  That is, in any case, the on-voltage is sequentially applied to the lines L1 to Lx of the scanning line 5 while the scanning line 5 to which the on-voltage is applied from the gate driver 15b is shifted line by line.

  On the other hand, in this embodiment, as shown in FIG. 9 and FIG. 10, the control means 22 of the radiographic imaging apparatus 1 detects the detection method 1 before radiographic imaging, that is, before detecting the start of radiation irradiation. In both cases (see FIG. 9) and detection method 2 (see FIG. 10), the gate driver 15b of the scanning drive means 15 applies an on-voltage to all the scanning lines 5 connected to the gate driver 15b. Thus, a reading process (in the case of FIG. 9) of image data d for detecting the start of irradiation and a reset process (in the case of FIG. 10) of each radiation detection element 7 are performed.

  In FIG. 9 and FIG. 10 and FIG. 16 described later, the reading process of the image data D as the main image after the detection of the start of radiation irradiation is simplified and described as the reading process of the main image data D. The read processing of the image data D as the main image, the charge accumulation state, etc. will be described later. In FIG. 10 and FIG. 14 to be described later, “R” represents a reset process for each radiation detection element 7 and “L” represents a read process for leak data dleak.

  In this way, in the reading process of the irradiation start detection image data d before the radiographic image capturing and the reset process of each radiation detection element 7, the voltages applied to all the scanning lines 5 are simultaneously turned on and off. As described in Patent Documents 4 and 5, the period during which each TFT 8 is turned off becomes shorter than when the on-voltage is sequentially applied to each scanning line 5 as described in Patent Documents 4 and 5. .

  As described above, the dark charges generated in each radiation detection element 7 are accumulated in each radiation detection element 7 while each TFT 8 is in the off state. If the period during which is turned off becomes shorter, the amount of dark charge accumulated in each radiation detection element 7 is reduced accordingly.

  When the dose rate of the radiation irradiated to the radiographic imaging apparatus 1 as a subject of the present invention is small, it is difficult to detect the start of radiation irradiation if the S / N ratio of the data read from each radiation detection element 7 is poor. Become. However, as described above, if the amount of dark charge accumulated in each radiation detection element 7 is reduced, the S / N ratio of the data is improved, and the dose rate of radiation applied to the radiation imaging apparatus 1 is small. Even in this case, there is an advantage that it becomes easier to detect the start of radiation irradiation.

  In FIG. 9 and FIG. 10, before the radiation image is taken, the gate driver 15b applies on-voltages to all the scanning lines 5 connected to the gate driver 15b all at once, thereby detecting image data for detecting the start of irradiation. The case where d reading processing (see FIG. 9) and reset processing of each radiation detection element (see FIG. 10) are performed is shown.

  However, it is not always necessary to apply the on-voltage to all the scanning lines 5 simultaneously, that is, simultaneously, before performing radiographic image capturing. For example, as in the case of the detection method 1 shown in FIG. Between the time when the first pulse signal Sp1 is transmitted to the double sampling 19 and the time when the second pulse signal Sp2 is transmitted, the ON voltage is applied to each line L1 to Lx of the scanning line 5 from the gate driver 15b. It is also possible to configure the application so that the rising and falling timings are shifted.

  In addition, as in the case of the detection method 2 shown in FIG. 12, during the reset processing of each radiation detection element 7, the rise or fall of the ON voltage is applied from the gate driver 15 b to each line L <b> 1 to Lx of the scanning line 5. It is possible to apply the on-voltage by shifting the timing.

  Further, for example, as shown in FIG. 11 and FIG. 12, instead of the configuration in which the rising and falling of the on-voltage are sequentially shifted and applied, the illustration of the on-voltage rising and falling is omitted. It is also possible to configure so that the application is performed by shifting in the order of random or randomly.

  However, in the case of the detection method 1 shown in FIG. 11, the process of applying the on voltage to each scanning line 5 by shifting the rise and fall of the on voltage is the first time from the control means 22 to the correlated double sampling 19. In the case of the detection method 2 shown in FIG. 12 between the transmission of the first pulse signal Sp1 and the second pulse signal Sp2, the charge reset switch 18c of the amplifier circuit 18 is turned on. Each needs to be done while being done.

  11 and 12, the on / off interval of the charge reset switch 18c and the transmission interval of the pulse signals Sp1 and Sp2 are set to be larger than the on / off interval and the transmission interval shown in FIG. However, this is merely an expression for making the figure easy to see, and does not mean that the on / off interval or the transmission interval is actually increased.

  Further, as described above, it is not necessary to apply an on-voltage to all the scanning lines 5 before performing radiographic imaging, and processing is not performed from the gate driver 15b to all the scanning lines 5 connected to the gate driver 15b. An on-voltage is applied to some of the plurality of scanning lines 5 to read out image data d for detection of irradiation start (in the case of detection method 1) and reset processing of each radiation detection element (in the case of detection method 2) ) Can also be configured.

  Specifically, for example, when each of the lines L1 to Lx of the scanning line 5 shown in FIG. 3 is bisected in the vertical direction in the drawing, for example, in the case of the detection method 1 shown in FIG. In the reading process of the image data d for detecting the start of irradiation, the application of the ON voltage to each line L1 to Lm of the scanning line 5 and the application of the ON voltage to each line Lm + 1 to Lx of the scanning line 5 are performed. It can also be configured to repeat alternately.

  Further, as in the case of the detection method 2 shown in FIG. 14 for example, in the reset process of each radiation detection element 7 that is alternately performed with the readout process of the leak data dleak before radiographic image capturing, each line L1 to L1 of the scanning line 5 is reset. The application of the on voltage to Lm and the application of the on voltage to the lines Lm + 1 to Lx of the scanning line 5 can be alternately repeated.

  In this way, the on-voltage is applied to some of the scanning lines 5 among all the scanning lines 5 connected to the gate driver 15b to read out the image data d for detecting the start of irradiation (detection method). 1) and the reset processing of each radiation detection element (in the case of the detection method 2), the period during which each TFT 8 is turned off is sufficiently short as described above.

  Therefore, the amount of dark charge accumulated in each radiation detection element 7 is reduced by that amount, and the S / N ratio of the read data is improved. Therefore, the dose rate of radiation applied to the radiation image capturing apparatus 1 is increased. Even in this case, the above-described merit that it is easier to detect the start of radiation irradiation can be obtained in this case.

[About integrating image data etc. for detection of irradiation start]
On the other hand, as a second improvement from the detection method 1 described in Patent Document 4 and the detection method 2 described in Patent Document 5, the radiographic imaging device 1 according to the present embodiment has a control unit. 22 does not use the image data d (detection method 1) or leakage data dleak (detection method 2) for detecting the start of irradiation read out before radiographic imaging as described above, but integrates them, It is configured to perform detection processing of radiation irradiation start.

  The reason for this configuration is as follows. That is, as described in Patent Documents 4 and 5 above, when the radiation image capturing apparatus 1 is irradiated with radiation having a relatively large dose rate, as shown in FIG. The value of the detection image data d and the like is much larger than the previous value.

  Therefore, for example, as shown in FIG. 6, the threshold value dth (threshold value dleak_th for leak data dleak) is set to an appropriate value, and the read image data d for irradiation start detection exceeds the threshold value dth. Therefore, it can be configured to detect the start of radiation irradiation.

  However, when the radiation image capturing apparatus 1 is irradiated with radiation having a small dose rate, as described above, irradiation of the radiation image capturing apparatus 1 is started and read, and image data d for irradiation start detection read out. However, the threshold dth or the like may not be exceeded even if it increases, and eventually the start of radiation irradiation may not be detected.

  Therefore, in the present embodiment, the control unit 22 reads out the irradiation start detection image data d (detection method 1) and leak data dleak (detection method 2) read out as described above, as they are. Integration is performed for each process, and the integrated value is used for the detection process of the start of radiation irradiation.

  However, the read-out image data d for detecting the start of exposure and the leak data dleak are usually superimposed with some offset such as dark charge, and data of a positive value other than 0 is read out. Therefore, if it is configured to simply continue to add them, the integrated value of the image data d for irradiation start detection will eventually exceed the set threshold value, and the radiation image capturing apparatus 1 is not irradiated with radiation. Regardless, the control means 22 detects the start of radiation irradiation.

  Therefore, for example, the control unit 22 performs the irradiation start detection image read out in the readout process immediately before the readout process each time the readout start image data d and leak data dleak are read out. The calculation process of the difference Δd between the data d and the leak data dleak can be performed for each reading process of the image data d for detecting the start of irradiation and the leak data dleak.

In this case, for example, if the image data d for detection of irradiation start and the leak data dleak read in the previous reading process are expressed as dold and dleak_old, the difference Δd is calculated according to the following equations (1) and (2). Is done.
Δd = d−dold (1)
Δd = dleak−dleak_old (2)

  Each time the difference Δd is calculated in this way, the calculated difference Δd is added to the integrated value ΣΔd of the difference so far, and the integrated value ΣΔd of the difference obtained by adding the difference Δd is set to the set threshold value Σth. It can be configured to detect that irradiation of radiation is started at a time exceeding

  Note that, as described above, this detection method includes the irradiation start detection image data d and leak data dleak read before radiographic imaging, and the irradiation start detection image data d and leak data dleak read immediately before. Since the difference Δd from the time is integrated over time, it is hereinafter referred to as integration method 1.

  Further, as described above, the difference Δd between the read image data d and the leak data dleak for detecting the start of irradiation and the image data d and the leak data dleak for detecting the start of irradiation read immediately before is integrated over time. Instead, the following configuration is also possible.

  That is, each time the reading process of the image data d for detecting the start of exposure or the leak data dleak is performed, the control unit 22 reads the past reading process for a predetermined number of times (for example, 10 times) including that reading process. An average of the output image data d for detecting the start of irradiation, that is, a moving average dma is calculated.

In addition, the irradiation start detection image data d read in the reading process of that time and the moving average dma calculated in the previous reading process (that is, the past reading process for a predetermined number of times including the previous reading process). A difference Δd with respect to the read moving average dma) of the irradiation start detection image data d and the like is calculated according to the following equation (3).
Δd = d−dma (3)

In the case where the leak data dleak is read out (and the reset process of each radiation detection element 7) is performed before radiographic imaging (that is, in the case of the detection method 2), the difference Δd according to the following equation (4): Is calculated. In this case, the moving average dma is a moving average of leak data dleak for a predetermined number of times.
Δd = dleak−dma (4)

  Each time the difference Δd is calculated in this way, the calculated difference Δd is added to the integrated value ΣΔd of the difference so far, and the integrated value ΣΔd of the difference obtained by adding the difference Δd is set to the set threshold value Σth. It can be configured to detect that irradiation of radiation is started at a time exceeding

  Note that, as described above, this detection method is a method of temporally integrating the difference Δd between the irradiation start detection image data d and the leak data dleak read out before the radiographic image capturing and the moving average dma. Hereinafter, it is referred to as integration method 2.

  When the integration method 1 or the integration method 2 as described above is adopted as a radiation irradiation start detection method, the image data d or leakage data for irradiation start detection that is read out before the radiation imaging apparatus 1 is irradiated with radiation. The drift is fluctuating and becomes larger or smaller than the image data d for irradiation start detection previously read (in the case of the integration method 1) or the moving average dma (in the case of the integration method 2).

  Therefore, the difference Δd calculated according to the above equations (1) to (4) becomes a positive value or a negative value. For this reason, the integrated value ΣΔd changes to a value close to zero.

  However, when radiation irradiation to the radiation image capturing apparatus 1 is started, the read-out image data d for detection of irradiation start and the value of the leak data dleak are read as image data d for detection of detection of irradiation start read out last time, etc. Since the value is larger than the moving average dma, the difference Δd is a positive value. For this reason, the integrated value ΣΔd increases.

  When the radiation imaging apparatus 1 is irradiated with strong radiation, that is, radiation with a large dose rate, for example, as shown in FIG. 6, the values of the read image data d for detection of irradiation start and the leak data dleak before that are read. It is much larger than the value of the image data d for irradiation start detection read out in (1). The value is much larger than the moving average dma.

  Therefore, the difference Δd between the irradiation start detection image data d and the like read in the reading process of that time and the irradiation start detection image data d and the like read at the previous time and the moving average dma becomes a large value. Therefore, the integrated value ΣΔd in the current read process calculated by adding it to the previous integrated value also increases at a stretch.

  On the other hand, when the dose rate of the radiation irradiated to the radiographic imaging device 1 is small, the integrated value ΣΔd does not increase at a stretch as described above, but the read image data d for detection of irradiation start and leak data are read. Since the value of dleak is often larger than the previously read image data d for detecting the start of irradiation or the like (in the case of the integration method 1) or the moving average dma (in the case of the integration method 2), In many cases, the difference Δd becomes a positive value. Therefore, for example, as shown in FIG. 15, the integrated value ΣΔd also gradually increases in this case.

  Therefore, when the above integration method 1 or integration method 2 is used, the integrated value ΣΔd does not exceed the threshold value Σth (see FIG. 15) before the irradiation of the radiation imaging apparatus 1 is started. Is started, the integrated value ΣΔd increases and exceeds the threshold value Σth. Therefore, by configuring as described above, it is possible to accurately detect the start of radiation irradiation on the radiographic imaging apparatus 1 even when the radiation dose applied to the radiographic imaging apparatus 1 is very small. .

  At that time, as shown in FIGS. 9, 11, and 13, at least the detection method 1 applies an on-voltage to all the scanning lines 5 or a part of a plurality of scanning lines 5 before taking a radiographic image. When configured to perform the reading process of the image data d for start detection, the reading circuit 17 transmits the radiation detection elements 7 (see FIG. 3 and the like) connected to the plurality of scanning lines 5 in one reading process. The charge flows into the state.

  And when the dose rate of the radiation irradiated to the radiographic imaging apparatus 1 is small, the electric charge which flows into the reading circuit 17 from each radiation detection element 7 is a small electric charge amount, respectively, but these are the capacitors 18b ( 4), the image data d for irradiation start detection read in one reading process (actually the total value) becomes large.

  Therefore, as described above, an on-voltage is applied to all of the scanning lines 5 or a part of a plurality of scanning lines 5 before radiographic image capturing to perform the reading processing of the image data d for irradiation start detection. Thus, even when the dose rate of the radiation irradiated to the radiographic imaging device 1 is small, the image data d for irradiation start detection (actually the total value thereof) is increased, and the integrated value ΣΔd is reliably increased. Thus, there is an advantage that the threshold value Σth can be accurately exceeded.

  Note that FIG. 15 shows a case where the radiation imaging apparatus 1 actually starts radiation irradiation at time T1, and the radiation imaging apparatus 1 detects the radiation irradiation start at time t1.

  In practice, as will be described later, since the control unit 22 shifts to the charge accumulation state when the radiation irradiation start is detected, the reading process of the image data d for detecting the irradiation start is stopped. However, FIG. 15 shows the transition of the integrated value ΣΔd when the reading process is continued even after the start of radiation irradiation, and shows the case where the radiation irradiation is completed at time T2.

  In this case, as described above, the threshold value Σth increases when the radiation image capturing apparatus 1 is not irradiated with radiation and the integrated value ΣΔd that changes at a value close to 0 and when radiation irradiation is started. The accumulated value ΣΔd is set to a value that can be clearly separated.

  In the above description, the integration method 1 and the integration method 2 are performed for each readout circuit 17, that is, the difference Δd and the integration value ΣΔd are calculated for each readout circuit 17 (in the case of the integration method 2, further reading is performed). (The calculation of the moving average dma of the image data d for detecting the start of irradiation, etc.) has been described. Actually, the number of readout circuits 17 (that is, the number of signal lines) is from several thousand to several tens of thousands. If it is configured to perform the above-described processing for each of them, the detection process of the start of radiation irradiation becomes a very heavy process.

  Therefore, for example, by using the fact that a large number of readout circuits 17 such as 128 or 256 are formed in the readout IC 16 (see FIGS. 3 and 4), the irradiation read out by each readout circuit 17 is used. The average value, total value, intermediate value, and the like for each read IC 16 such as the image data d for start detection are calculated, and the difference Δd and the integrated value ΣΔd (and moving average dma) are calculated for the average value and the like for each read IC 16. It can be configured to do so.

  Further, for example, the maximum value and the minimum value are extracted from the average value for each reading IC 16 such as the image data d for detecting the start of irradiation, the difference value is calculated, and the threshold value for which the difference value is set It is also possible to configure so as to perform a detection process of the start of radiation irradiation by determining whether or not the maximum value has been exceeded.

  If comprised as mentioned above, the number of the data used for the detection process of radiation irradiation start, and the number of numerical values will decrease, and it will become possible to make the radiation irradiation start detection process light processing. Therefore, the time required for the detection process is shortened, and it becomes possible to detect the start of radiation irradiation on the radiation image capturing apparatus 1 in real time.

  It goes without saying that further improvements can be added to the detection process of the start of radiation irradiation.

[Each process after detection]
When it is detected that the radiation imaging apparatus 1 has started irradiation of radiation as described above, as shown in FIG. 9 (in the case of the detection method 1) and FIG. 10 (in the case of the detection method 2), the control means 22 Applies a turn-off voltage to all the lines L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning driving means 15 to turn off the TFTs 8. Then, the charge generated in each radiation detection element 7 due to radiation irradiation is shifted to a charge accumulation state in which the radiation detection element 7 is accumulated.

  Subsequently, the control unit 22 continues the charge accumulation state for a predetermined time, and then sequentially applies an on-voltage from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5 so that each radiation detection element 7 generates a main image. The image data D is read out from the image data D.

  Further, the image data D to be read is superimposed with the offset due to the dark charge accumulated in each radiation detection element 7 while the TFT 8 is in the OFF state across the charge accumulation state period. .

Therefore, in subsequent image processing, the offset due to the dark charge is subtracted from the image data D to calculate true image data D ^* based only on the charges generated in each radiation detection element 7 due to the irradiation of radiation. In order to be able to do so, the radiographic image capturing apparatus 1 reads offset data O as offset data O that reads offsets due to dark charges superimposed on the image data D before or after radiographic image capturing. Is configured to be performed.

  In this embodiment, the offset data O reading process is performed by repeating a series of processing sequences up to the reading process of the image data D as the main image (see FIGS. 9 and 10).

  That is, for example, the case where the above-described detection method 1 (see FIG. 9) is employed will be described as an example. The control unit 22 of the radiographic image capturing apparatus 1 performs the read processing of the image data D as the main image, and then performs FIG. In the same manner as the reading process of the image data d for irradiation start detection before the radiographic imaging shown in FIG. 5, an on-voltage is applied to all or some of the plurality of scanning lines 5 from the gate driver 15b of the scanning driving means 15. Read processing of the image data d for irradiation start detection is performed.

  Then, after applying the ON voltage from the gate driver 15b to each scanning line 5 for a predetermined number of times, for example, once or twice, all the lines L1 to L1 of the scanning line 5 from the gate driver 15b are applied as in FIG. An off voltage is applied to Lx to shift to a charge accumulation state. Then, after the charge accumulation state is continued for a predetermined time, the ON voltage is sequentially applied from the gate driver 15b to each of the lines L1 to Lx of the scanning line 5 at the same timing as the reading process of the image data D as the main image (see FIG. 9). The offset data O is read out from each radiation detection element 7 by applying.

  In addition, since the radiation image capturing apparatus 1 is not irradiated with radiation when the offset data O is read, it is not necessary to perform radiation irradiation start detection processing. Therefore, instead of performing the reading process of the image data d for irradiation start detection as described above before the reading process of the offset data O, as shown in FIG. 16, each radiation detection element is applied at the same on-voltage application timing. 7 can be configured to perform the reset process.

  As described above, when the offset data O reading process (see FIG. 16) is configured to repeat a series of processing sequences up to the reading process of the image data D as the main image (see FIG. 9 and the like), Such beneficial effects can be obtained.

  The amount of dark charge accumulated in each radiation detection element 7 is the time during which the TFT 8 connected to the radiation detection element 7 is in the off state (that is, see time T in FIGS. 9 and 16, for example). This time increases in proportion to the effective accumulation time. The accumulated dark charge is read as offset data O, and the magnitude of the offset data O also changes depending on the effective accumulation time T. However, if the effective accumulation time T is the same, the read offset data O has the same value.

  As described above, if the processing sequence up to the reading processing of the image data D as the main image and the processing sequence up to the reading processing of the offset data O are the same processing sequence, at least the same scanning line 5 is offset. The effective accumulation time T (see FIG. 16) in which the TFT 8 was turned off during the data O reading process, and the effective accumulation time T (see FIG. 9) during the image data D reading process as the main image Will be at the same time.

For this reason, since the offset due to the dark charge superimposed on the image data D and the offset data O read by the reading process of the offset data O have the same value, the offset data O is subtracted from the image data D. Thus, it is possible to calculate the true image data D ^* based only on the charges generated in each radiation detecting element 7 by the irradiation of radiation.

  When the control unit 22 of the radiographic image capturing apparatus 1 reads the image data D and the offset data O as the main image as described above, the read image data D and the offset data O are transmitted to the image processing apparatus. It has become.

  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 or all the scanning lines 5 from the gate driver 15b of the scanning driving unit 15 are captured before radiographic image capturing. Each of the radiations that is applied to the scanning voltage 5 of some of the scanning lines 5 to read out the image data d for detecting the start of irradiation (in the case of the detection method 1) or alternately with the reading processing of the leak data dleak The reset process of the detection element 7 is performed (in the case of the detection method 2).

  The read irradiation start detection image data d and leak data dleak, and the irradiation start detection image data d (dold) and leak data dleak (dleak_old) read out in the readout process immediately before the readout process. The difference Δd is calculated, and the calculated difference Δd is added to the integrated value ΣΔd of the difference so far to calculate the integrated value ΣΔd of the difference (in the case of the integration method 1).

  Alternatively, the difference Δd from the moving average dma of the irradiation start detection image data d and the leak data dleak read out in each of the past reading processes for a predetermined number of times including the reading process immediately before the reading process is calculated. Then, the calculated difference Δd is added to the integrated value ΣΔd of the difference so far to calculate the integrated value ΣΔd of the difference (in the case of the integration method 2).

  Then, it is configured to detect that radiation irradiation is started when the integrated value ΣΔd of the difference obtained by adding the difference Δd exceeds a set threshold value Σth (for example, see FIG. 15).

  Therefore, since the integrated value ΣΔd does not exceed the threshold value Σth before radiation irradiation to the radiation image capturing apparatus 1 is started, erroneous detection of the start of radiation irradiation is accurately prevented, and radiation irradiation is started. Then, the integrated value ΣΔd increases and exceeds the threshold value Σth.

  Therefore, by configuring as described above, it is possible to accurately detect the start of radiation irradiation on the radiographic imaging apparatus 1 even when the radiation dose applied to the radiographic imaging apparatus 1 is very small. .

  Further, as in the radiographic image capturing apparatus 1 according to the present embodiment, in the readout process of the image data d for irradiation start detection before the radiographic image capture and the reset process of each radiation detection element 7, all the scanning lines 5 are processed. By switching the applied voltage simultaneously between the on voltage and the off voltage, the period during which each TFT 8 is turned off is shortened, and the charge remaining in each radiation detection element 7 is frequently The signal line 6 is released.

  For this reason, the amount of dark charge accumulated in each radiation detection element 7 is reduced, and the S / N ratio of the image data d for irradiation start detection read from each radiation detection element 7 can be improved. . And since the S / N ratio of the data read in this way improves, even when the dose rate of the radiation irradiated to the radiographic imaging apparatus 1 is small, it becomes possible to detect the radiation irradiation start more accurately. .

  Needless to say, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging device 5 Scanning line 6 Signal line 7 Radiation detection element 8 TFT (switch means)
15 Scanning drive means 15b Gate driver 17 Reading circuit 22 Control means D Image data d Image data for detection of irradiation start leak data dma Moving average q Charge r Small area Δd Difference Σth Threshold ΣΔd Integrated value

Claims (4)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines When,
A scanning driving means comprising a gate driver for switching on and applying an on voltage and an off voltage to each scanning line;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Before radiographic imaging, from the gate driver of the scan driving means, all the scanning lines connected to the gate driver, or a part of all the scanning lines connected to the gate driver While repeatedly performing a reading process of reading the image data for irradiation start detection by applying an on-voltage to the plurality of scanning lines,
A difference between the read image data for detecting the start of irradiation and the image data for detecting the start of irradiation read in the read process immediately before the read process for reading the image data for detecting the start of irradiation is calculated. The processing is performed for each reading process of the image data for detecting the irradiation start,
Each time the difference is calculated, the calculated difference is added to the integrated value of the difference so far, and the integrated value of the difference obtained by adding the difference exceeds the set threshold value. A radiographic imaging apparatus, characterized in that it is detected that is started. The control means includes
A difference between the read image data for detecting the start of irradiation and the image data for detecting the start of irradiation read in the read process immediately before the read process for reading the image data for detecting the start of irradiation is calculated. Instead of processing
The irradiation read out in each of the past reading processes for a predetermined number of times including the read-out image data for detection of irradiation start and the read-out process immediately before the read-out process of reading out the image data for detection of irradiation start. The radiographic imaging apparatus according to claim 1, wherein a process of calculating a difference from a moving average of image data for start detection is performed for each reading process of image data for detection of irradiation start. A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other, and a plurality of radiation detection elements arranged in a two-dimensional manner in each small region partitioned by the plurality of scanning lines and the plurality of signal lines When,
A scanning driving means comprising a gate driver for switching on and applying an on voltage and an off voltage to each scanning line;
Switch means connected to each of the scanning lines and causing the signal lines to discharge charges accumulated in the radiation detection element when an on-voltage is applied;
A readout circuit that converts the electric charge emitted from the radiation detection element into image data and reads the image data;
Control means for controlling at least the scanning drive means and the readout circuit to perform readout processing of the image data from the radiation detection element;
With
The control means includes
Before radiographic imaging, from the gate driver of the scan driving means, all the scanning lines connected to the gate driver, or a part of all the scanning lines connected to the gate driver A reset process of each radiation detection element performed by applying an ON voltage to a plurality of the scanning lines, and leakage from each radiation detection element via the switch means in a state where an OFF voltage is applied to each scanning line While alternately performing a leak data read process for converting the charge into leak data,
A process of calculating a difference between the read leak data and the leak data read in the read process immediately before the read process for reading the leak data is performed for each leak data read process,
Each time the difference is calculated, the calculated difference is added to the integrated value of the difference so far, and the integrated value of the difference obtained by adding the difference exceeds the set threshold value. A radiographic imaging apparatus, characterized in that it is detected that is started. The control means includes
Instead of the process of calculating the difference between the read leak data and the leak data read in the read process immediately before the read process for reading the leak data,
The difference between the read leak data and the moving average of the leak data read in the past read processes for a predetermined number of times including the read process immediately before the read process for reading the leak data is calculated. The radiographic imaging apparatus according to claim 3, wherein the process is performed for each reading process of the leak data.

Images