JP2011133302A - Radiographic imaging device and radiographic imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic imaging device for displaying a preview image speedily and accurately preventing a stripe pattern extending in the direction of a signal line from appearing on the preview image. <P>SOLUTION: The radiographic imaging device 1 includes a detection unit P, including radiation detectors 7 disposed two-dimensionally; a plurality of read circuits 17 for reading image data d through a signal line 6 from the radiation detectors 7; a scanning drive circuit 15 for applying on and off voltages to each scanning line 5; a control means 22 for controlling each operation of the scanning drive circuit 15 and the read circuit 17, in read processing of the image data d; and a communication means 39. The control means 22 allows the read circuit 17 to perform read operation, while an off voltage is applied to all scanning lines 5 to acquire an offset value Oline for each read circuit 17 before and after photographing a radiation image or at each read processing of the image data d, and transmits the offset value Oline for each read circuit 17, when the image data d are to be transmitted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiographic image capturing apparatus and a radiographic image capturing system using the same.

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

  This type of radiographic imaging apparatus is known as an FPD (Flat Panel Detector), and conventionally formed integrally with a support base (or a bucky apparatus) (see, for example, Patent Document 1). A portable radiographic imaging device in which an element or the like is housed in a housing has been developed and put into practical use (see, for example, Patent Documents 2 and 3).

  In such a radiographic imaging device, for example, as shown in FIG. 7 to be described later, usually, a plurality of scanning lines 5 and a plurality of signal lines 6 are arranged on the detection part P of the glass substrate so as to intersect each other. In addition, the radiation detection elements 7 are arranged two-dimensionally (matrix) in each region partitioned by the scanning lines 5 and the signal lines 6. Each radiation detection element 7 is connected with a thin film transistor (hereinafter referred to as TFT) 8 as a switching means, and a drain electrode 8d of each TFT 8 (denoted as D in FIG. 7). Are connected to the signal line 6 respectively.

  Each signal line 6 is connected to each readout circuit 17 including an amplification circuit 18 and a correlated double sampling circuit 19 formed in the readout IC 16, and the output of each readout circuit 17. The side is connected to the A / D conversion circuit 20 via the multiplexer 21 and the like. Then, when radiographic imaging is performed, the charge accumulated in each radiation detection element 7 is read out from each radiation detection element 7 to each readout circuit 17 via the signal line 6 during the readout process, After being converted into analog image data d by, for example, charge-voltage conversion in the amplifier circuit 18, it is converted into digital image data (ie, so-called raw data) d by the A / D conversion circuit 20 and output. .

  By the way, as described above, the read circuit 17 including the amplifier circuit 18 and the correlated double sampling circuit 19 has manufacturing variations in the amplifier circuit 18 and the like in the process of manufacturing the read IC. Therefore, the read characteristics of the image data d from each radiation detection element 7 may be different for each read circuit 17.

  When the readout characteristics of the image data d are different for each readout circuit 17 in this way, for example, the radiation image capturing apparatus is irradiated with a low dose of radiation, and the image data d having a relatively low signal value is output from each readout circuit 17. In such a situation, when a radiation image is generated based on the output image data d or the like, a phenomenon occurs in which a striped pattern extending in the direction of the signal line 6 appears on the generated radiation image.

  On the other hand, when generating a diagnostic radiographic image for performing full-scale image processing on image data d (raw data), as shown in FIG. After the reading process of the image data d from the detection element 7, normally, the radiation image capturing apparatus is left for a predetermined time in a state where the radiation image capturing apparatus is not irradiated with radiation, and then, similar to the above-described reading process of the image data d The dark reading process for reading out the dark charge accumulated in each radiation detection element 7 as the dark reading value da is performed once or a plurality of times.

  Then, the dark read value da acquired by the dark reading process or the offset correction value O calculated based on the dark read value da is transmitted to, for example, the console 58 (see FIG. 15) together with the transmission of the image data d. Then, a diagnostic radiation image is generated by performing image processing or the like for correcting the image data d based on the offset correction value O or the like at the console 58.

  In radiographic imaging using a radiographic imaging apparatus, a preview image is created before full-scale image processing is performed on the image data d to generate a diagnostic radiographic image, and a radiographer or the like previews the image. Look at the image and check whether the subject is photographed on the radiographic image, whether the subject is photographed at an appropriate position on the radiographic image, etc. Often configured. At this time, the preview image may be any image that can be checked and determined by a radiologist or the like by looking at it, and is required to be displayed on the screen as soon as possible after imaging.

  However, in preparation of the preview image, after radiographic imaging is performed and the dark read value da is acquired as described above, the image data d and the dark read value da (or offset correction value O) are transmitted to obtain the image data. When the full-scale image processing for d is performed, it takes time until the preview image is displayed on the screen after the photographing is completed.

  Therefore, in Patent Document 4, in order to shorten the time from imaging to display of a preview image, image data d is transmitted immediately after radiographic imaging, and the image data d is directly subjected to image processing as a preview image without being subjected to image processing. Temporary image processing is performed using a display technique, an offset correction value at the time of previous imaging, or a temporary offset correction value O acquired in advance at the time of manufacturing the radiographic imaging apparatus, for the transmitted image data d. A technique for displaying the performed image data d as a preview image is disclosed.

JP-A-9-73144 JP 2006-058124 A JP-A-6-342099 JP 2003-325494 A

  However, when the image data d is directly displayed as a preview image without image processing, as described above, a striped pattern extending in the direction of the signal line 6 derived from different readout characteristics for each readout circuit 17 is displayed on the preview image. Will appear.

  In addition to positioning on the radiographic image of the subject as described above, the point that the radiologist etc. confirms by looking at the preview image is that the lesion of the patient is in good contrast with the surrounding tissue. There is also a point as to whether or not the image has been shot, or whether or not the image can be corrected to a good state if at least full-scale image processing is performed.

  However, the lesioned part of the patient is photographed in an image area where the irradiated radiation becomes a low dose after being absorbed and scattered by the patient's body. The striped pattern extending in the direction of the signal line 6 derived from different readout characteristics for each readout circuit 17 is irradiated with a low-dose image region, that is, the low-dose radiation as described above, and each readout circuit 17. To easily appear in an image area where image data d having a relatively low signal value is output.

  Therefore, when the image data d is configured to be displayed as a preview image as it is without image processing, even if a radiographer or the like looks at the preview image, the patient's lesion has a good contrast with the surrounding tissue. Thus, it is impossible to accurately determine whether or not the image has been shot. Therefore, it is difficult to adopt such a preview image creation method.

  Further, different read characteristics for each read circuit 17 may vary depending on the environment surrounding each read circuit 17 such as the temperature of the read IC 16 and the surrounding temperature. Therefore, as disclosed in Patent Document 4, an offset correction value O at the time of previous imaging, a temporary offset correction value O acquired in advance at the time of manufacturing the radiographic imaging device, or the like is used for the image data d. If the provisional image processing is performed and the image is displayed as a preview image, the environment surrounding each readout circuit 17 may be different at the time of the previous photographing or manufacturing of the radiation image photographing device and at the time of the current photographing. .

  In such a case, provisional image processing is performed on the image data d using the offset correction value O at the time of previous imaging, the provisional offset correction value O acquired in advance at the time of manufacturing the radiation image capturing apparatus, or the like. Then, there is a possibility that a striped pattern extending in the direction of the signal line 6 derived from different readout characteristics for each readout circuit 17 may appear in the low-dose image area where the lesion area of the patient is imaged.

  Therefore, in this case as well, there is a risk that a radiographer or the like will not be able to accurately determine whether or not the patient's lesion is imaged in a good contrast with the surrounding tissue by looking at the preview image. Therefore, it is not always sufficient as a method for creating a preview image.

  The present invention has been made in view of the above-described problems. It is possible to display a preview image promptly after shooting, and to ensure that a striped pattern extending in the signal line direction appears on the preview image. It is an object of the present invention to provide a radiographic image capturing apparatus and a radiographic image capturing system using the same.

In order to solve the above-described problem, the radiographic imaging device of the present invention includes:
A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A plurality of readout circuits for reading out charges from the radiation detection elements through the signal lines and outputting the charges as image data for each of the radiation detection elements;
A scanning drive circuit that switches a voltage applied to each scanning line between an on-voltage and an off-voltage,
In the read processing of the image data from each radiation detection element, at least control means for controlling each operation of the scan drive circuit and the read circuit;
A communication means for transmitting / receiving data to / from an external device;
With
The control means is configured to apply the off voltage to all the scanning lines from the scanning drive circuit before or after radiographic imaging, or at the time of reading out the image data from the radiation detection elements. Each readout circuit performs a readout operation to acquire an offset value for each readout circuit, and when the image data is transmitted to an external device via the communication unit, the offset value for each readout circuit is also transmitted. It is characterized by.

Moreover, the radiographic imaging system of the present invention is
A radiographic imaging device of the present invention;
A console comprising communication means for transmitting and receiving data to and from the radiation image capturing apparatus; and a display unit for displaying an image based on the data;
With
The console corrects the image data with an offset value for each readout circuit based on the image data transmitted from the radiographic imaging apparatus via the communication unit and the offset value for each readout circuit. The generated preview image is displayed on the display unit.

  In the radiographic image capturing apparatus according to the present invention, in the radiographic image capturing apparatus, the control unit creates thinned data in which the image data is thinned out at a predetermined ratio based on the image data, and the image The thinned data is transmitted before data transmission, and an offset value for each readout circuit is also transmitted when the thinned data is transmitted.

Moreover, the radiographic imaging system of the present invention is
The radiographic imaging device of the present invention,
A console comprising communication means for transmitting and receiving data to and from the radiation image capturing apparatus; and a display unit for displaying an image based on the data;
With
The console corrects the thinning data with an offset value for each readout circuit based on the thinning data and the offset value for each readout circuit transmitted from the radiographic imaging device via the communication unit. The generated preview image is displayed on the display unit.

  According to the radiographic image capturing apparatus and radiographic image capturing system of the system of the present invention, when transmitting image data acquired by radiographic image capturing from the radiographic image capturing apparatus or thinning data created based on the image data, the radiographic image is acquired. The offset value for each readout circuit acquired before and after imaging and during readout processing of image data from each radiation detection element is also transmitted. Further, the console displays the preview image generated by correcting the image data and the thinned data transmitted from the radiation image capturing apparatus with the offset value for each circuit on the display unit.

  Therefore, it is possible to quickly display the preview image on the display unit of the console after the radiographic image is captured, and an operator such as a radiographer can see the preview image and the subject is accurately captured on the radiographic image. It is possible to immediately determine whether or not re-photographing is necessary by confirming whether or not there is.

  In addition, since an offset value for each readout circuit is acquired before and after radiographic imaging or during image data readout processing from each radiation detection element, the readout characteristics for each readout circuit may vary depending on the environment such as temperature. The offset value for each readout circuit can be acquired in the same state as the environment in which the image data and the thinned data are acquired.

  Therefore, by correcting the image data and the thinned data with the offset value for each readout circuit acquired in this way, the offset due to the readout characteristics that differ for each readout circuit can be accurately obtained from the image data and the thinned data. This makes it possible to eliminate the occurrence of a striped pattern extending in the signal line direction on the preview image. The striped pattern extending in the signal line direction is accurately removed from the preview image, so that the radiological technician etc. looks at the preview image and the patient's lesion is in good contrast with the surrounding tissue Thus, it is possible to accurately determine whether or not the image has been shot, and it is possible to accurately prevent occurrence of a situation in which it is erroneously determined and re-shooting or the like is required.

It is a perspective view which shows the radiographic imaging apparatus which concerns on this embodiment. It is sectional drawing which follows the XX line in FIG. It is a top view which shows the structure of the board | substrate of a radiographic imaging apparatus. It is an enlarged view which shows the structure of the radiation detection element, TFT, etc. which were formed in the small area | region on the board | substrate of FIG. It is sectional drawing which follows the YY line in FIG. It is a side view explaining the board | substrate with which COF, a PCB board | substrate, etc. were attached. It is a block diagram showing the equivalent circuit of a radiographic imaging apparatus. It is a block diagram showing the equivalent circuit about 1 pixel which comprises a detection part. It is a figure explaining the unconnected terminal to which the scanning line of the gate driver of a scanning drive circuit is not connected. It is a graph showing the change of the voltage value etc. in a correlated double sampling circuit. It is a graph which shows progress of each processing in the case of transmitting image data etc. after radiographic image photography. 6 is a timing chart illustrating an example of timing for sequentially applying an ON voltage to each scanning line and unconnected terminals. 4 is a timing chart showing timings for sequentially applying an ON voltage to unconnected terminals and scanning lines in the present embodiment. It is a graph which shows progress of each processing in the case of performing transmission etc. of thinning data after radiographic image photography. It is a figure which shows the whole structure of the radiographic imaging system which concerns on this embodiment. It is a graph which shows progress of each processing after radiographic imaging in a conventional radiographic imaging device.

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

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

[Radiation imaging equipment]
FIG. 1 is an external perspective view of the radiographic image capturing apparatus according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line XX of FIG. As shown in FIGS. 1 and 2, the radiation image capturing apparatus 1 according to the present embodiment is configured by housing a scintillator 3, a substrate 4, and the like in a housing 2.

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

  As shown in FIG. 1, the side surface of the housing 2 is opened and closed for replacement of a power switch 36, an indicator 37 composed of LEDs and the like, and a battery 41 (not shown) (see FIG. 7 described later). A possible lid member 38 and the like are arranged. In the present embodiment, an antenna device 39, which is a communication means for wirelessly transmitting and receiving image data d and the like to an external device such as a console 58 (see FIG. 15) described later, is provided on the side surface of the lid member 38. Embedded.

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

  As shown in FIG. 2, a base 31 is disposed inside the housing 2 via a lead thin plate (not shown) on the lower side of the substrate 4, and an electronic component 32 and the like are disposed on the base 31. The PCB substrate 33, the buffer member 34, and the like are attached. In the present embodiment, a glass substrate 35 for protecting the substrate 4 and the radiation incident surface R of the scintillator 3 is disposed.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  In this embodiment, as shown in FIG. 3, each scanning line 5, each signal line 6, and connection 10 of the bias line 9 are input / output terminals (also referred to as pads) provided near the edge of the substrate 4. 11 is connected. As shown in FIG. 6, a COF (Chip On Film) 12 in which a chip such as a gate IC 12a constituting a gate driver 15b of the scanning drive means 15 described later is incorporated in each input / output terminal 11 is anisotropically conductively bonded. They are connected via an anisotropic conductive adhesive material 13 such as a film (Anisotropic Conductive Film) or an anisotropic conductive paste (Anisotropic Conductive Paste).

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

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

  As described above, each radiation detection element 7 of the detection unit P of the substrate 4 has the bias line 9 connected to the second electrode 78, and each bias line 9 is bound to the connection 10 to the bias power supply 14. It is connected. The bias power supply 14 applies a bias voltage to the second electrode 78 of each radiation detection element 7 via the connection 10 and each bias line 9. The bias power source 14 is connected to a control unit 22 described later, and the control unit 22 controls a bias voltage applied to each radiation detection element 7 from the bias power source 14.

  In the present embodiment, the current detection means 43 for detecting the amount of current flowing through the connection 10 (bias line 9) is provided in the connection 10 of the bias line 9. As described above, when the radiation imaging apparatus 1 is irradiated with radiation, electron-hole pairs are generated in the i layer 76 (see FIG. 5) of each radiation detection element 7, and this is the bias line 9 or the connection. The current detection means 43 can detect the start and end of radiation irradiation by detecting the increase or decrease of the current flowing through the connection 10. In the present invention, the current detection means 43 is not necessarily provided.

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

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

  The scanning drive unit 15 switches the voltage applied to each line L1 to Lx of the scanning line 5 between the on voltage and the off voltage by switching between the on voltage and the off voltage. A gate driver 15b that switches between an on state and an off state is provided. In the present embodiment, the gate driver 15b of the scanning drive means 15 is formed by arranging a plurality of the gate ICs 12a described above in parallel, and a predetermined number of scanning lines 5 such as 128 are connected to one gate IC 12a. It can be done.

  The radiographic image capturing apparatus 1 of the present embodiment is configured such that a predetermined number x of scanning lines 5 are provided from the lines L1 to Lx. Therefore, as shown in FIG. 9, in the gate IC 12a at the end of the gate driver 15b, that is, the gate IC 12a arranged at the lower end or the upper end in the figure, an unconnected terminal p to which the scanning line 5 is not connected is generated.

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

  The readout circuit 17 includes an amplification circuit 18 and a correlated double sampling circuit 19. An analog multiplexer 21 and an A / D converter 20 are further provided in the reading IC 16. 7 and 8 and FIG. 10 described later, the correlated double sampling circuit 19 is represented as CDS. In FIG. 8, the analog multiplexer 21 is omitted.

  In the present embodiment, the amplifier circuit 18 is configured by a charge amplifier circuit, and is configured by connecting a capacitor 18b and a charge reset switch 18c in parallel to the operational amplifier 18a and the operational amplifier 18a. In addition, a power supply unit 18 d for supplying power to the amplifier circuit 18 is connected to the amplifier circuit 18.

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

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

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

  That is, in the reading process of the image data d from each radiation detection element 7 after radiographic imaging, the control unit 22 first controls the charge reset switch 18c of the amplification circuit 18 of each readout circuit 17 to turn off. To. At that time, so-called kTC noise occurs at the moment when the charge reset switch 18c is turned off, and the charge q caused by the kTC noise accumulates in the capacitor 18b of the amplifier circuit 18.

  As described above, 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 terminal of the operational amplifier 18 a of the amplifier circuit 18, but as described above, the charge q caused by kTC noise. 10 is accumulated in the capacitor 18b, the voltage value output from the output terminal of the operational amplifier 18a at the moment when the charge reset switch 18c is turned off (indicated as “18coff” in FIG. 10), as shown in FIG. From the above-described reference potential V0, it changes instantaneously by the amount of charge q caused by kTC noise and changes to a voltage value Vin.

  At this stage (indicated as “CDS hold” (left side) in FIG. 10), the control means 22 transmits the first pulse signal Sp1 to the correlated double sampling circuit 19 and is output from the amplifier circuit 18 at that time. The voltage value Vin being held is held.

  Subsequently, when the on-voltage Von is applied from the scanning drive circuit 15 to one scanning line 5 and the TFT 8 having the gate electrode 8g connected to the scanning line 5 is turned on ("TFTon" is displayed in FIG. 10). ), The charge accumulated from each radiation detection element 7 connected to these TFTs 8 flows into the capacitor 18b of the amplifier circuit 18 via each signal line 6 and is accumulated. As shown in FIG. 10, the charge is accumulated in the capacitor 18b. The voltage value output from the output side of the operational amplifier 18a increases in accordance with the accumulated charge amount.

  Then, after a predetermined time has elapsed, the control means 22 switches the on voltage Von applied to the scanning line 5 from the scanning drive circuit 15 to the off voltage Voff, and the gate electrode 8g is connected to the scanning line 5. The TFT 8 is turned off (displayed as “TFToff” in FIG. 10), and at this stage, the second pulse signal Sp2 is transmitted to each correlated double sampling circuit 19 and output from the amplifier circuit 18 at that time. The voltage value Vfi is held (displayed as “CDS hold” (right side) in FIG. 10).

  When each correlated double sampling circuit 19 holds the voltage value Vfi with the second pulse signal Sp2, the voltage value difference Vfi−Vin is calculated, and the calculated difference Vfi−Vin is output to the downstream side as image data d. It is like that.

  The image data d of each radiation detection element 7 output from the correlated double sampling circuit 19 is transmitted to the analog multiplexer 21 (see FIG. 7), and is sequentially transmitted from the analog multiplexer 21 to the A / D converter 20. Then, the A / D converter 20 sequentially converts the image data d into digital values, outputs them to the storage means 40, and sequentially stores them.

  The control means 22 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface connected to the bus, an FPGA (Field Programmable Gate Array), or the like (not shown). It is configured. It may be configured by a dedicated control circuit. And the control means 22 controls operation | movement etc. of each member of the radiographic imaging apparatus 1. Further, as shown in FIG. 7 and the like, the control means 22 is connected with a storage means 40 constituted by a DRAM (Dynamic RAM) or the like.

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

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

  In addition, the control means 22 applies each of the scanning driving means 15 to the scanning driving means 15 at the time of reset processing of each radiation detecting element 7 or at the time of reading the image data d from each radiation detecting element 7 after radiographic imaging. A pulse signal for switching the voltage applied to the gate electrode 8g of each TFT 8 between the ON voltage and the OFF voltage via the scanning line 5 is transmitted.

  On the other hand, the control means 22 applies all lines L1 to Lx of the scanning line 5 from the gate driver 15b of the scanning drive circuit 15 before or after the radiographic image capturing or at the time of reading the image data d from each radiation detecting element 7. In a state where an off voltage is applied, that is, in a state where all the TFTs 8 are in an off state, each readout circuit 17 performs a readout operation (that is, a so-called idle reading state in this case). The offset value Oline is obtained. Since each readout circuit 17 is connected to each signal line 6 as described above, the offset value Oline for each readout circuit 17 can also be referred to as the offset value Oline for each signal line 6.

  For example, the readout operation (that is, the idle reading operation) in each readout circuit 17 may be performed before or after radiographic imaging, that is, at one of timings A and B shown in FIG. Is possible. In this case, the readout operation as described above is performed by each readout circuit 17 in a state where the off voltage is applied to all the lines L1 to Lx of the scanning line 5.

  That is, with the off voltage applied to all the lines L1 to Lx of the scanning line 5, the charge reset switch 18c of the amplifier circuit 18 is turned off as in the normal image data d reading operation shown in FIG. The first pulse signal Sp1 is transmitted to each correlated double sampling circuit 19, and the voltage value Vin output from the amplifier circuit 18 at that time is held. In this case, since the off voltage is applied to all the lines L1 to Lx of the scanning line 5, the TFT 8 is not turned on / off.

  Then, after the same predetermined time as the reading operation of the image data d, the second pulse signal Sp2 is transmitted to each correlated double sampling circuit 19, and the voltage value Vfi output from the amplifier circuit 18 at that time is held. . Then, the voltage value difference Vfi−Vin is output from each correlated double sampling circuit 19 as an offset value Oline for each readout circuit 17, and is sequentially transmitted from the analog multiplexer 21 to the A / D converter 20 to be sequentially converted into a digital value. The data is converted and sequentially stored in the storage unit 40.

  In this case, when this so-called idle reading operation is performed a plurality of times, the offset value Oline obtained every time is averaged for each reading circuit 17 to obtain the offset value Oline for each reading circuit 17. In addition, the time of each process in FIG. 11, FIG. 12, and FIG. 13 mentioned later, the time interval between each process, etc. do not necessarily reflect reality.

  Further, for example, at the time of reading the image data d from each radiation detection element 7, that is, at any timing of C or D shown in FIG. ) Can also be configured.

  In the case where each readout circuit 17 is configured to perform an idle reading operation at the timing D shown in FIG. 11, scanning in which an on-voltage is applied at the time of readout processing of image data d from each radiation detection element 7. In this case, the line 5 is configured to perform the reading process while switching in the order of the lines L1, L2,...

  That is, as shown in FIG. 12, for example, an on-voltage is applied to all the lines L <b> 1 to Lx of the scanning line 5 to perform batch reset processing of each radiation detection element 7, and radiation irradiation to the radiation imaging apparatus 1 is performed. Thereafter, in the reading process of the image data d, the lines L1 to Lx of the scanning line 5 among the terminals of the gate IC 12a (see FIG. 9) constituting the gate driver 15b of the scanning drive circuit 15 are connected. The on-voltage is sequentially applied not only to the terminal but also to the unconnected terminal p to which the scanning line 5 is not connected, and the order in which the on-voltage is applied to each terminal of the gate driver 15b of the scanning drive circuit 15 is L1. , L2,..., Lx, p, p,.

  In this case, when an on-voltage is applied to each line L1 to Lx of the scanning line 5, the TFT 8 connected to each line L1 to Lx is turned on, and each radiation detection element 7 connected to the TFT 8 is turned on. The image data d is read out from the image data. However, when the on-voltage is applied to the unconnected terminal p, the image data d is not read out because there is no TFT 8 that is turned on.

  However, even when an on-voltage is applied to the unconnected terminal p, each readout circuit 17 performs an idle reading operation in the same manner as described above to obtain the offset value Oline for each of the readout circuit 17 or a plurality of readout circuits 17, When the configuration is such that a plurality of offset values Oline are acquired, for example, they are averaged for each readout circuit 17 to obtain the offset value Oline for each readout circuit 17.

  With this configuration, it is not necessary to perform the idle reading operation in each readout circuit 17 for acquiring the offset value Oline for each readout circuit 17 before or after radiographic imaging, and one readout operation can be performed. Among them, it is possible to simultaneously acquire the offset value Oline for each readout circuit 17 together with the image data d.

  Further, it becomes possible to read the image data d and the offset value Oline for each reading circuit 17 in the same operation as the normal image data d reading operation. In addition to the normal image data d reading process, the unconnected terminal p Therefore, there is an advantage that it is very easy to construct the processing procedure.

  In the present embodiment, conversely, the control means 22 is configured to cause each readout circuit 17 to perform an idle reading operation at the timing C shown in FIG.

  In this case, when the image data d is read from each radiation detection element 7, the gate driver 15b of the scanning drive circuit 15 applies the turn-on voltage to each terminal as shown in the timing chart of FIG. Contrary to the above case, switching is performed in the order of p,..., P, p, Lx,..., L2, and L1 from the unconnected terminal p.

  The control means 22 first causes each readout circuit 17 to perform an idle reading operation as shown in FIG. 10 when an on-voltage is applied to the unconnected terminal p (in this case, In this case, the TFT 8 is not turned on / off.) The offset value Oline for each readout circuit 17 or a plurality of readout circuits 17 is acquired and stored in the storage means 40 sequentially.

  Subsequently, each radiation detection element connected to each line Lx to L1 via the TFT 8 by sequentially applying an ON voltage to each line Lx to L1 of the scanning line 5 to perform on / off operation of the TFT 8. The image data d from 7 is read out by each readout circuit 17 and stored in the storage means 40 sequentially.

  With this configuration, it is not necessary to perform the idle reading operation in each readout circuit 17 for acquiring the offset value Oline for each readout circuit 17 before or after radiographic imaging, and one readout operation can be performed. Among them, it is possible to simultaneously acquire the offset value Oline for each readout circuit 17 together with the image data d.

  Further, for example, when each readout circuit 17 is activated immediately before starting the readout process of the image data d from each radiation detection element 7 (that is, so-called wake up), the readout characteristics of each readout circuit 17 are unstable. However, as the so-called idle reading is repeated in each readout circuit 17 by sequentially applying an ON voltage to the unconnected terminal p, the temperature of each readout circuit 17 rises and becomes stable.

  Therefore, after that, when the read operation is performed by sequentially applying the ON voltage in the order of each of the lines Lx,..., L2, L1 of the scanning line 5, the temperature of each read circuit 17 should be in a stable state. Can do. Therefore, it is possible to stabilize the read characteristics of each read circuit 17.

  Further, when performing a read operation from the unconnected terminal p in this way, considering only the stabilization of the read characteristics of each read circuit 17, normally, when an on-voltage is applied to the unconnected terminal p. It is considered that the data read by each reading circuit 17 is discarded without being stored in the storage means 40. However, this embodiment has an excellent merit that such normally discarded data can be used effectively as an offset value Oline for each readout circuit 17.

  When the on-voltage is applied to the unconnected terminal p of the gate driver circuit 15b and the idle reading is performed, the offset value for each readout circuit 17 is applied every time the on-voltage is applied to all the unconnected terminals p and the idle reading is performed. The Oline may be acquired and averaged for each readout circuit 17, but as described above, there may be a case where the readout characteristics are not stable because the temperature of each readout circuit 17 is initially rising. is there.

  For this reason, the first empty reading data is discarded (that is, the empty reading operation is performed but not stored in the storage means 40), and the one that is close to the terminal to which the line Lx of the scanning line 5 is connected. Or, the data of idle reading when the on-voltage is applied to several unconnected terminals p (in the example of FIG. 9, the unconnected terminal p on the upper side in the figure) (or their readout circuits 17) It is also possible to obtain an offset value Oline for each readout circuit 17.

  When the control unit 22 is configured to acquire a plurality of offset values Oline, the control unit 22 averages them for each readout circuit 17, calculates the offset value Oline for each readout circuit 17, and stores it in the storage unit 40. In addition, when transmitting an offset value Oline, which will be described later, a plurality of offset values Oline read from the storage means 40 may be transmitted while being averaged for each readout circuit 17. is there.

  As shown in FIG. 11, when the offset value Oline for each readout circuit 17 is obtained, the offset value Oline for each readout circuit 17 is added to the later-described console 58 via the antenna device 39 together with the image data d (see FIG. 15). It can be configured to transmit to an external device.

  At that time, the image data d and the offset value Oline are transmitted after each process such as a compression process is appropriately performed. The console 58 can be configured to display the preview image generated by correcting the transmitted image data d based on the offset value Oline for each readout circuit 17 on the display unit 58a.

  However, as described above, the preview image displayed on the display unit 58a of the console 58 indicates whether or not the subject is photographed at a suitable position on the radiographic image with high contrast when an operator such as a radiographer looks at it. What is necessary is just to be able to confirm. The preview image is required to be displayed on the display unit 58a of the console 58 as quickly as possible.

  Therefore, in the present embodiment, after the offset value Oline for each readout circuit 17 is obtained as shown in FIG. 11, the offset value Oline for each readout circuit 17 is transmitted together with the image data d (raw data). In addition, as shown in FIG. 14, the control means 22 creates thinned data dt in which the image data d is thinned out at a predetermined rate based on the obtained image data d, and before the transmission of the image data d. In addition, the thinned data dt and the offset value Oline for each readout circuit 17 are transmitted. At this time, the thinned data dt and the offset value Oline are transmitted after each process such as a compression process is appropriately performed.

  The thinned data dt is, for example, each line at a predetermined interval of the scanning line 5 as image data d from each radiation detecting element 7 connected to each of the lines L1, L4, L7,. The image data d from each radiation detection element 7 connected to Ln can be extracted and created, or, for example, corresponding to each radiation detection element 7 arranged two-dimensionally. When each image data d is arranged, the image data d for one pixel may be extracted every 3 × 3 pixels or 4 × 4 pixels.

  If the thinned data dt is generated and transmitted before the transmission of the image data d, the thinned data dt has a smaller amount of data than the image data d and can be transmitted to the console 58 in a shorter time. That's it. Therefore, compared to the case where the image data d is transmitted and the preview image based on the image data d is transmitted, the preview image is displayed more quickly on the console 58 when the thinned data dt is transmitted and the preview image is displayed based on the thinned data dt. It can be displayed on the display unit 58a.

  In the present embodiment, as shown in FIG. 11 and FIG. 14, when the control unit 22 transmits the thinning data dt and the image data d, the control unit 22 continues for a predetermined time without irradiating the radiation image capturing apparatus 1 with radiation. (That is, after the batch reset process for each radiation detection element 7 as described above, the time until the reading process of the image data d from each radiation detection element 7 is started) After the radiation image capturing apparatus 1 is left, A dark reading process is performed in which charges (that is, dark charges) and the like accumulated in the radiation detection element 7 are read by the reading circuit 17 and acquired as a dark reading value da.

  11 and 14 show a case where the dark reading process is performed only once. However, as described above, the dark reading process may be performed a plurality of times, and the control unit 22 may be configured as follows. The dark reading process is performed a preset number of times.

  Then, when there is a transmission request from the console 58 by the operation of the operator who has confirmed the preview image on the console 58, or the control means 22 automatically receives the dark acquired as described above without waiting for the transmission request. The offset correction value O calculated as the read value da or, for example, the average value of each of the radiation detection elements 7 of the dark read values da for a plurality of times is transmitted to the console 58 (see FIG. 11).

  In addition, when the thinned data dt is transmitted to the console 58 as in the present embodiment, the remaining image data other than the thinned data dt is automatically issued without a transmission request when there is a transmission request from the console 58. d and the dark reading value da or the offset correction value O are transmitted to the console 58 (see FIG. 14).

  In the dark reading process, an on-voltage is applied to the unconnected terminal p of the gate IC 12a (see FIG. 9) constituting the gate driver 15b of the scan driving circuit 15 as described above, so There is no need to perform processing for obtaining the offset value Oline.

[Radiation imaging system]
FIG. 15 is a diagram illustrating an overall configuration of a radiographic image capturing system according to the present embodiment. As shown in FIG. 15, the radiographic image capturing system 50 includes, for example, an imaging room R <b> 1 that irradiates radiation and images a subject (part of a patient to be imaged) that is a part of a patient, and an operator such as a radiographer. Are arranged in the front chamber R2 for performing various operations such as control of the start of radiation for irradiating the subject, and the outside thereof.

  In the radiographing room R1, a bucky device 51 that can be loaded with the radiographic imaging device 1 described above, a radiation source 52 of a radiation generating device that includes an X-ray tube (not shown) that generates radiation to irradiate a subject, a radiographic imaging device 1 and the console 58 are provided with a base station 54 provided with a wireless antenna 53 for relaying the communication when the console 58 performs wireless communication.

  In the present embodiment, the base station 54 also serves as a communication means on the console 58 side that transmits and receives data between the radiographic imaging apparatus 1 and the console 58. FIG. 15 shows the case where the portable radiographic imaging device 1 is used by being loaded into the cassette holding part 51a of the bucky device 51. However, as described above, the radiographic imaging device 1 is used as the bucky device 51. Or may be formed integrally with a support base or the like. Further, as shown in FIG. 15, the radiographic image capturing apparatus 1 and the base station 54 can be connected by a cable so that data can be transmitted by wired communication via the cable.

  In the present embodiment, when the radiographic imaging device 1 is inserted into the radiographic room R1, a cassette ID that is identification information of the radiographic imaging device 1 is notified to the console 58 via the base station 54. A cradle 55 is provided. The console 58 manages which radiographic imaging device 1 is present in the imaging room R1 based on the cassette ID notified from the cradle 55.

  Note that management of the radiation image capturing apparatus 1 existing in the imaging room R1 may be performed by another mechanism, and the cradle 55 is not necessarily provided. Further, the cradle 55 may be configured to simply charge the radiation image capturing apparatus 1 or the like.

  The front chamber R2 is provided with a radiation generator operation console 57 or the like that controls radiation irradiation, including a switch means 56 for instructing the radiation generator 52 to start radiation irradiation.

  Although the configuration of the radiographic image capturing apparatus 1 is as described above, in the present embodiment, the radiographic image capturing apparatus 1 may be used by being loaded into the bucky device 51 as described above. Is not loaded, so it can be used alone.

  That is, the radiation image capturing apparatus 1 is disposed on the upper surface side in a single state, for example, on a bed provided in the imaging room R1 or a bucky apparatus 51B for lying position photographing as shown in FIG. (See FIG. 1) The patient's hand, which is the subject, can be placed on the top, or the patient's waist, legs, etc. lying on the bed can be inserted between the bed and the bed. It has become. In this case, for example, radiation image capturing is performed by irradiating the radiation image capturing apparatus 1 with radiation from a portable radiation source 52B or the like via a subject.

  In this embodiment, the console 58 that controls the entire radiographic imaging system 50 is provided outside the imaging room R1 and the front room R2. For example, the console 58 is provided in the front room R2 and the like. It is also possible.

  The console 58 is configured by a computer or the like in which a CPU, a ROM, a RAM, an input / output interface and the like (not shown) are connected to a bus. A predetermined program is stored in the ROM, and the console 58 reads out the necessary program, expands it in the work area of the RAM, executes various processes according to the program, and controls the entire radiographic imaging system 50 as described above. Is supposed to do.

  The console 58 is connected to the base station 54, the console 57, the storage means 59 configured by a hard disk or the like, and the cradle 55 is connected to the console 58 via the base station 54. A radiation source 52 and the like are connected to each other. Further, the console 58 is provided with a display unit 58a made up of a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or the like, and other input means such as a keyboard and a mouse are connected thereto.

  As described above, the console 58 transmits the thinned data dt, the offset value Oline, the image data d, the dark read value da, or the offset correction value O for each readout circuit 17 from the radiographic image capturing apparatus 1 through the base station 54. When the data comes, the storage unit 59 stores the data.

  As described above, when the thinning data dt and the offset value Oline for each reading circuit 17 are transmitted from the radiographic imaging apparatus 1, the console 58 reads the thinning data dt based on those data. The data d0 for the preview image is generated by correcting with the offset value Oline for each. As described above, the image data d (see FIG. 11) may be transmitted together with the offset value Oline for each readout circuit 17 instead of the thinned data dt (see FIG. 14). The description also applies to the case of the image data d by replacing the thinned data dt with the image data d.

Specifically, the storage means 59 of the console 58 stores gain correction values G for the radiation detection elements 7 of the radiographic imaging apparatus 1 in advance, and the console 58 is thinned out from the radiographic imaging apparatus 1. When the data dt and the offset value Oline for each readout circuit 17 are transmitted, each thinned data dt is corrected with the offset value Oline for each readout circuit 17 according to the following equation (1) to generate preview image data d0. It is like that.
d0 = G × log (dt−Oline) (1)

  In the calculation of the above equation (1), the offset for the signal line 6 to which the radiation detection element 7 that has output the thinned data dt to be calculated is connected via the TFT 8 as the offset value Oline for each readout circuit 17. The value Oline is used. That is, the same offset value Oline is used for the thinned data dt from the radiation detection element 7 connected to the same signal line 6 via the TFT 8.

  The console 58 displays a preview image on the display unit 58a based on the generated preview image data d0. As described above, when the operator who has confirmed the preview image determines that re-imaging is not necessary, the console 58 sends a transmission request to the radiographic image capturing apparatus 1 when the operator inputs that fact via the input unit. It can be configured to do so.

  On the other hand, when the console 58 receives the image data d or the dark read value d (or offset correction value O) from the radiographic image capturing apparatus 1 via the antenna device 39 or the base station 54, the console 58 confirms the preview image. In the case where an input that does not require re-imaging is performed by the person, the image data d and the like are temporarily stored in the storage unit 59, and then image processing is performed on the image data d to generate a diagnostic radiation image. Yes.

  In this case, the console 58 generates preview image data d0 using the same offset value Oline for each readout circuit 17 with respect to the thinned data dt (or image data d) as in the case of the preview image. Unlike the simple correction method, the dark reading value da acquired for each radiation detection element 7, that is, for each pixel, or the offset correction value O calculated based on them (hereinafter obtained by one dark reading process). In other words, full-scale image processing is performed on the image data d using the dark read value d obtained as an offset correction value O).

That is, the console 58 reads the gain correction value G for each radiation detection element 7 of the radiographic imaging apparatus 1 from the storage unit 59 in the same manner as described above, and converts the image data d into the offset correction value O according to the following equation (2). The diagnostic radiation image data d ^* is generated by correcting the contrast, and further, contrast adjustment and defective pixels are performed on the generated diagnostic radiation image based on an instruction from an operator such as a radiographer. The final diagnostic radiographic image is generated by performing various corrections such as correction of abnormal data d ^* due to the above.
d ^* = G × log (d−O) (2)

  Next, the operation of the radiographic image capturing apparatus 1 and the radiographic image capturing system 50 according to the present embodiment will be described.

  Each image data d of the radiation image is applied to each line L1 to Lx (see FIGS. 7 and 8) of the scanning line 5 in a state where all TFTs 8 are turned off, and the radiation source of the radiation generator When the radiation imaging apparatus 1 is irradiated with radiation from 52 (see FIG. 15), it is determined by the amount of charges generated and accumulated in each radiation detection element 7, that is, the amount of electron-hole pairs. However, when the image data d is accumulated in each radiation detection element 7 or read by the readout circuit 17, various offset components are superimposed on each image data d.

  As an offset component to be superimposed on the image data d, for example, as shown in FIGS. 12 and 13, an on-voltage is applied to each line L1 to Lx of the scanning line, and each TFT 8 is temporarily turned on to detect each radiation. After performing the batch reset process on the element 7, an off voltage is applied to each line L1 to Lx of the scanning line to turn off all TFTs 8, and then an on voltage is sequentially applied to each line L1 to Lx of the scanning line. In the meantime, there is an offset due to dark charges accumulated in each radiation detection element 7 until the readout processing from each radiation detection element 7 is performed.

  This dark charge is generated by thermal excitation or the like of each radiation detection element 7 itself, and the offset due to the dark charge has a different value for each radiation detection element 7.

  Further, as described above, it is derived from charges derived from the irradiated radiation accumulated in each radiation detection element 7 (that is, charges to be detected originally), thermal excitation by heat of each radiation detection element 7 itself, and the like. Electric charges (that is, dark charges) are read out by the respective readout circuits 17, but also in the readout process, the offset caused by the readout characteristics of the image data d from each radiation detection element 7 differing among the readout circuits 17. The component is superimposed on the image data d.

  The offset component in this case is superimposed on the image data d for each readout circuit 17, and in the readout process, an on-voltage is sequentially applied to each line L1 to Lx of the scanning line, and each TFT 8 is turned on. While being performed, it is superimposed on the image data d read from each radiation detection element 7.

  Therefore, the offset component resulting from the difference in readout characteristics for each readout circuit 17 is superimposed on the same offset for the image data d read from the radiation detection element 7 connected to the same signal line 6 via the TFT 8. However, when the connected signal lines 6 are different, the offset amount superimposed on the image data d read from the radiation detection element 7 is different.

  Then, as described above, before and after radiographic imaging (that is, at the timings A and B in FIGS. 11 and 14), each readout circuit is in a state where an off voltage is applied to all the lines L1 to Lx of the scanning line. The offset component obtained by performing the read operation at 17 and causing each read circuit 17 to perform a so-called idle read operation is an offset component resulting from the difference in the read characteristics of each read circuit 17.

  Further, as in the present embodiment, when the image data d is read from each radiation detection element 7 (that is, at timings C and D in FIGS. 11 and 14), the scanning line 5 is not connected and is not connected. Similarly, an offset voltage obtained by sequentially applying an on-voltage to the terminal p (see FIG. 9) to cause each readout circuit 17 to perform a readout operation, and causing each readout circuit 17 to perform a so-called idle readout operation, This is an offset component resulting from the difference in the readout characteristics for each readout circuit 17 described above.

  These offset components cause a striped pattern extending in the signal line direction to appear on the preview image as described above.

  Further, as described above, the readout characteristics that differ for each readout circuit 17 include the respective readout circuits 17 such as the temperature of the readout IC 16 (see FIGS. 7 and 8) in which each readout circuit 17 is formed and the ambient temperature. It may vary depending on the surrounding environment.

  However, as described above, by acquiring the offset component resulting from the difference in the readout characteristics for each readout circuit 17 immediately before or immediately after radiographic imaging, or during readout processing of the image data d from each radiation detection element 7 The offset component, that is, the offset value Oline for each readout circuit 17 can be acquired with the temperature of the readout IC 16 and the environment surrounding the readout IC 16 being the same as those at the time of radiographic imaging.

  Therefore, as in the present embodiment, when the preview image data d0 is generated by subtracting the offset value Oline for each readout circuit 17 from the thinned data dt (or image data d) (see the above formula (1)), The offset component in the same situation as when the radiographic image was acquired, that is, the offset value Oline for each readout circuit 17 is subtracted from the thinned data dt (or image data d). Therefore, it is possible to accurately remove the striped pattern extending in the signal line direction from the preview image.

  On the other hand, in the dark reading process, as described above, the same process as the reading process of the image data d from each radiation detection element 7 is performed except that the radiation image capturing apparatus 1 is not irradiated with radiation. The dark read value da (or offset correction value O) is acquired for each radiation detection element 7.

  At this time, an offset due to the dark charge accumulated in each radiation detection element 7 occurs before the readout process from each radiation detection element 7 is performed, and the above readout is performed in the process of reading out the dark read value da. An offset component is also generated due to the different read characteristics of each circuit 17. Therefore, the acquired dark read value da includes both the offset due to the dark charge and the offset component resulting from the different read characteristics for each read circuit 17.

  Therefore, as shown in the above equation (2), by performing a process of subtracting the offset correction value O calculated from the dark read value da from the image data d, the signal line direction from the generated diagnostic radiation image is obtained. It is possible to accurately remove the striped pattern extending in the direction.

  Further, since the dark read value da includes an offset due to the dark charge generated for each radiation detection element 7, it is calculated from the dark read value da from the image data d as shown in the above equation (2). By performing the process of subtracting the offset correction value O, the image data d is obtained based on the offset correction value O calculated based on the dark read value da acquired for each radiation detection element 7, that is, for each pixel. Thus, it is possible to appropriately perform image processing and generate an effective diagnostic radiation image.

  As described above, according to the radiographic image capturing apparatus 1 and the radiographic image capturing system 50 according to the present embodiment, the image data d acquired by radiographic image capturing from the radiographic image capturing apparatus 1 and the thinned data created based on the image data d. When transmitting dt, the offset value Oline for each readout circuit 17 acquired before and after radiographic imaging or during readout processing of image data d from each radiation detection element 7 is also transmitted. Further, the console 58 displays a preview image generated by correcting the image data d or the thinned data dt transmitted from the radiation image capturing apparatus 1 with the offset value Oline for each readout circuit 17 on the display unit 58a.

  Therefore, it is possible to promptly display the preview image on the display unit 58a of the console 58 after radiographic image capturing. Then, an operator such as a radiologist can determine whether or not re-imaging is necessary by checking whether or not the subject is accurately photographed on the radiation image by looking at the preview image. Become.

  In addition, since the offset value Oline for each readout circuit 17 is acquired before and after radiographic imaging or during readout processing of image data d from each radiation detection element 7, the readout characteristics for each readout circuit 17 depend on the environment such as temperature. Even if it can fluctuate, the offset value Oline for each readout circuit 17 can be acquired in the same state as the environment in which the image data d and the thinned data dt are acquired.

  Therefore, by correcting the image data d and the thinned-out data dt with the offset value Oline for each readout circuit 17 obtained in this way, the readout characteristics that differ for each readout circuit 17 from the image data d and the thinned-out data dt are obtained. It is possible to accurately remove the offset that is caused, and it is possible to accurately prevent the appearance of a striped pattern extending in the signal line direction on the preview image.

  The striped pattern extending in the signal line direction is accurately removed from the preview image, so that the radiological technician etc. looks at the preview image and the patient's lesion is in good contrast with the surrounding tissue Thus, it is possible to accurately determine whether or not the image has been shot, and it is possible to accurately prevent occurrence of a situation in which it is erroneously determined and re-shooting or the like is required.

  In the case where the radiographic imaging device 1 is configured to acquire the offset value Oline for each readout circuit 17 during the readout process of the image data d from each radiation detection element 7 as in the above embodiment, When radiographic image capturing is performed continuously, an offset value Oline for each readout circuit 17 is acquired for each readout process, and for example, an average value for each readout circuit 17 is used as an offset value Oline for each readout circuit 17. It is also possible to configure such that the offset value Oline for each readout circuit 17 is acquired by any one of the readout processes repeatedly performed or by a predetermined number of readout processes. It is.

  In the above embodiment, the case where the radiation image capturing apparatus 1 performs the batch reset process on each radiation detection element 7 before capturing the radiation image has been described. However, the scanning lines 5 are sequentially applied to the lines L1 to Lx. It is also possible to apply a turn-on voltage and perform a reset process for each radiation detection element 7 connected to each line L1 to Lx of the scanning line 5 via the TFT 8. Further, reset processing for each radiation detection element 7 is appropriately performed after the reading process of the image data d from each radiation detection element 7 or before and after the dark reading process.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the essence of the invention.

DESCRIPTION OF SYMBOLS 1 Radiographic imaging apparatus 5, L1-Lx Scan line 6 Signal line 7 Radiation detection element 15 Scan drive circuit 17 Read-out circuit 22 Control means 39 Antenna apparatus (communication means)
50 Radiation imaging system 54 Base station (communication means on the console side)
58 Console (external device)
58a Display unit d Image data da Dark reading value dt Decimation data O Offset correction value Oline Offset value P for each reading circuit Detection unit p Unconnected terminal (terminal not connected to scanning line)
r region

Claims (9)

A plurality of scanning lines and a plurality of signal lines arranged so as to intersect with each other; a plurality of radiation detecting elements arranged in a two-dimensional manner in each region partitioned by the plurality of scanning lines and the plurality of signal lines; A detector comprising:
A plurality of readout circuits for reading out charges from the radiation detection elements through the signal lines and outputting the charges as image data for each of the radiation detection elements;
A scanning drive circuit that switches a voltage applied to each scanning line between an on-voltage and an off-voltage,
In the read processing of the image data from each radiation detection element, at least control means for controlling each operation of the scan drive circuit and the read circuit;
A communication means for transmitting / receiving data to / from an external device;
With
The control means is configured to apply the off voltage to all the scanning lines from the scanning drive circuit before or after radiographic imaging, or at the time of reading out the image data from the radiation detection elements. Each readout circuit performs a readout operation to acquire an offset value for each readout circuit, and when the image data is transmitted to an external device via the communication unit, the offset value for each readout circuit is also transmitted. A radiographic imaging device characterized by the above. The scan driving circuit includes a terminal not connected to the scan line,
When the control means obtains an offset value for each readout circuit during the readout process of the image data from each radiation detection element, an ON voltage is applied to a terminal not connected to the scanning line of the scanning drive circuit. Is applied to each of the scanning lines and the readout voltage is applied from the scanning drive circuit to each readout circuit, and the readout circuit performs a readout operation similar to the readout processing of the image data for each readout circuit. The radiographic image capturing apparatus according to claim 1, wherein an offset value is acquired.   In the case where the control means obtains an offset value for each readout circuit during the readout processing of the image data from each radiation detection element, the side on which the scanning line is connected to each terminal of the scanning drive circuit The radiographic image capturing apparatus according to claim 2, wherein on-state voltages are sequentially applied in order.   When acquiring the offset value for each readout circuit during the readout process of the image data from each radiation detection element, the control means connects the scanning line of the scanning drive circuit to each terminal of the scan drive circuit. The radiographic imaging apparatus according to claim 2, wherein an on-voltage is applied in order from a terminal not connected to the terminal.   The control means leaves the apparatus for a predetermined time without irradiating radiation, acquires the charge accumulated in the radiation detection element as a dark reading value, and transmits the dark reading value or the dark reading value via the communication means. The radiographic imaging apparatus according to any one of claims 1 to 4, wherein the offset correction value calculated from (1) is transmitted to an external apparatus.   The control means creates thinned data in which the image data is thinned out at a predetermined rate based on the image data, transmits the thinned data before transmitting the image data, and transmits the thinned data The radiographic image capturing apparatus according to any one of claims 1 to 4, wherein an offset value for each readout circuit is also transmitted.   The control means, after transmitting the thinning data and the offset value for each readout circuit, leave the device for a predetermined time without irradiating radiation, and obtain the charge accumulated in the radiation detection element as a dark reading value, The radiographic image capturing apparatus according to claim 6, wherein the image data and the dark reading value or an offset correction value calculated from the dark reading value are transmitted to an external device via the communication unit. The radiographic imaging device according to any one of claims 1 to 5,
A console comprising communication means for transmitting and receiving data to and from the radiation image capturing apparatus; and a display unit for displaying an image based on the data;
With
The console corrects the image data with an offset value for each readout circuit based on the image data transmitted from the radiation imaging apparatus via the communication unit and the offset value for each readout circuit. A radiographic imaging system, wherein the generated preview image is displayed on the display unit. The radiographic imaging device according to claim 6 or 7,
A console comprising communication means for transmitting and receiving data to and from the radiation image capturing apparatus; and a display unit for displaying an image based on the data;
With
The console corrects the thinning data with an offset value for each readout circuit based on the thinning data and the offset value for each readout circuit transmitted from the radiographic imaging device via the communication unit. A radiographic imaging system, wherein the generated preview image is displayed on the display unit.

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