Patent Publication Number: US-2023137069-A1

Title: Radiation detector

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Application No. PCT/JP2021/018041, filed on May, 12, 2021; and is also based upon and claims the benefit of priority from the Japanese Patent Application No.2020-113832, filed on Jul. 1, 2020; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments of the invention relate to a radiation detector. 
     BACKGROUND 
     An X-ray detector is an example of a radiation detector. The X-ray detector includes, for example, an array substrate that includes multiple photoelectric conversion parts, and a scintillator that is located on the multiple photoelectric conversion parts and converts X-rays into fluorescence. Also, the photoelectric conversion part includes a photoelectric conversion element that converts the fluorescence from the scintillator into a signal charge, a thin film transistor that switches between storing and discharging the signal charge, a storage capacitor that stores the signal charge, etc. 
     Generally, an X-ray detector configures an X-ray image as follows. First, the incidence of X-rays is recognized by a signal input from the outside. Then, after a predetermined amount of time has elapsed, the thin film transistors of the photoelectric conversion parts that perform reading are set to the on-state, and the stored signal charge is read as an image data signal. Then, the X-ray image is configured based on the values of the image data signals read from the photoelectric conversion parts. 
     However, values that correspond to the dose of the X-rays and values that correspond to noise are included in the values of the image data signals read from the photoelectric conversion parts. Therefore, when configuring the X-ray image, offset processing (an offset correction) is performed in which the values corresponding to the noise are subtracted from the values of the image data signals read from the photoelectric conversion parts. 
     In such a case, noise can be broadly divided into random noise and lateral noise. Random noise occurs in a uniform distribution over the entire X-ray image. On the other hand, lateral noise appears as a striation in the lateral direction or the longitudinal direction. Therefore, lateral noise is more noticeable than random noise; it is therefore desirable to reduce lateral noise. 
     To reduce such lateral noise, technology has been proposed in which multiple noise detecting parts that do not generate signal charges when X-rays are incident are included, and the lateral noise is detected by the multiple noise detecting parts. Generally, the multiple noise detecting parts are arranged outside the region (the effective pixel region) in which the multiple photoelectric conversion parts are located. 
     Here, in recent years, it is desirable to downsize X-ray detectors. However, a problem results in which the X-ray detector size increases when there is a region outside the effective pixel region in which multiple noise detecting parts are located. 
     It is therefore desirable to develop technology that can detect noise and can suppress an X-ray detector size increase. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic perspective view illustrating an X-ray detector. 
         FIG.  2    is a block diagram of the X-ray detector. 
         FIG.  3    is a circuit diagram of an array substrate. 
         FIG.  4    is a schematic plan view illustrating a noise detecting part according to a comparative example. 
         FIG.  5    is a schematic plan view illustrating the noise detecting part according to the comparative example. 
         FIG.  6    is a schematic plan view illustrating the location of a region in which the multiple noise detecting parts are located. 
         FIG.  7    is a schematic plan view illustrating the noise detecting part according to the embodiment. 
         FIG.  8    is a schematic plan view illustrating the noise detecting part according to the embodiment. 
         FIGS.  9 A and  9 B  are schematic plan views for illustrating the location of a region in which the multiple noise detecting parts are located. 
         FIG.  10    is a schematic plan view illustrating an arrangement of noise detecting parts according to another embodiment. 
         FIG.  11    is a schematic plan view illustrating the arrangement of noise detecting parts according to another embodiment. 
         FIGS.  12 A and  12 B  are schematic plan views for illustrating locations of the region  203 . 
     
    
    
     DETAILED DESCRIPTION 
     A radiation detector according to an embodiment includes multiple control lines extending in a first direction, multiple data lines extending in a second direction orthogonal to the first direction, photoelectric conversion parts located respectively in multiple regions defined by the multiple control lines and the multiple data lines, multiple noise detecting parts arranged outside a region in which the multiple photoelectric conversion parts are located, and a scintillator located on the region in which the multiple photoelectric conversion parts are located. 
     Each of the multiple photoelectric conversion parts includes a first thin film transistor electrically connected to a corresponding control line of the multiple control lines and a corresponding data line of the multiple data lines, and a photoelectric conversion element including an electrode electrically connected with the first thin film transistor. 
     Each of the multiple noise detecting parts includes a second thin film transistor electrically connected to a corresponding control line of the multiple control lines and a corresponding data line of the multiple data lines, and a capacitance part electrically connected with the second thin film transistor. 
     A length of the capacitance part is less than a length of the electrode in at least one of the first direction or the second direction. 
     Embodiments will now be illustrated with reference to the drawings. Similar components in the drawings are marked with the same reference numerals; and a detailed description is omitted as appropriate. 
     A radiation detector according to the embodiment is applicable to various radiation other than X-rays such as γ-rays, etc. Herein, as an example, the case relating to X-rays is described as a typical example of radiation. Accordingly, applications to other radiation also are possible by replacing “X-ray” of embodiments described below with “other radiation”. 
     An X-ray detector  1  illustrated below is an X-ray planar sensor that detects an X-ray image, i.e., a radiation image. 
     For example, the X-ray detector  1  can be used in general medical care, etc., but is not limited in its application. 
       FIG.  1    is a schematic perspective view illustrating the X-ray detector  1 . 
     A bias line  2   c   3  and the like are not illustrated in  FIG.  1   . 
       FIG.  2    is a block diagram of the X-ray detector  1 . 
       FIG.  3    is a circuit diagram of an array substrate  2 . 
     As shown in  FIGS.  1  to  3   , the X-ray detector  1  includes the array substrate  2 , a signal processing circuit  3 , an image configuration circuit  4 , and a scintillator  5 . 
     The array substrate  2  converts, into an electrical signal, fluorescence (visible light) converted from X-rays by the scintillator  5 . 
     The array substrate  2  includes a substrate  2   a,  a photoelectric conversion part  2   b,  a control line (or gate line)  2   c   1 , a data line (or signal line)  2   c   2 , the bias line  2   c   3 , and a noise detecting part  2   g.    
     The numbers and the like of the photoelectric conversion part  2   b,  the control line  2   c   1 , the data line  2   c   2 , the bias line  2   c   3 , and the noise detecting part  2   g  are not limited to those illustrated. 
     The substrate  2   a  is plate-shaped and formed from a light-transmitting material such as alkali-free glass, etc. 
     Multiple photoelectric conversion parts  2   b  are located at one surface of the substrate  2   a.    
     The photoelectric conversion parts  2   b  are rectangular and are located respectively in multiple regions defined by the multiple control lines  2   c   1  and the multiple data lines  2   c   2 . The multiple photoelectric conversion parts  2   b  are arranged in a matrix configuration. 
     One photoelectric conversion part  2   b  corresponds to one pixel (pixel) of the X-ray image. 
     Each of the multiple photoelectric conversion parts  2   b  includes a photoelectric conversion element  2   b   1  and a thin film transistor (TFT; Thin Film Transistor)  2   b   2  (corresponding to an example of a first thin film transistor) that is a switching element. 
     Also, as shown in  FIG.  3   , a storage capacitor  2   b   3  that stores the signal charge converted by the photoelectric conversion element  2   b   1  can be included. The storage capacitor  2   b   3  is, for example, rectangular flat-plate shaped and can be located under each thin film transistor  2   b   2 . However, according to the capacitance of the photoelectric conversion element  2   b   1 , the photoelectric conversion element  2   b   1  also can be used as the storage capacitor  2   b   3 . 
     The photoelectric conversion element  2   b   1  can be, for example, a photodiode, etc. 
     The thin film transistor  2   b   2  switches between storing and discharging the charge generated by fluorescence incident on the photoelectric conversion element  2   b   1 . The thin film transistor  2   b   2  includes a gate electrode  2   b   2   a,  a drain electrode  2   b   2   b,  and a source electrode  2   b   2   c.  The gate electrode  2   b   2   a  of the thin film transistor  2   b   2  is electrically connected with the corresponding control line  2   c   1 . The drain electrode  2   b   2   b  of the thin film transistor  2   b   2  is electrically connected with the corresponding data line  2   c   2 . The source electrode  2   b   2   c  of the thin film transistor  2   b   2  is electrically connected to the corresponding photoelectric conversion element  2   b   1  (electrode  2   b   1   b ) and storage capacitor  2   b   3 . Also, the storage capacitor  2   b   3  and the anode side of the photoelectric conversion element  2   b   1  are electrically connected with the corresponding bias line  2   c   3 . 
     In other words, the thin film transistor  2   b   2  is electrically connected to the corresponding control line  2   c   1  and the corresponding data line  2   c   2 . The electrode  2   b   1   b  at the substrate  2   a  side of the photoelectric conversion element  2   b   1  is electrically connected with the thin film transistor  2   b   2  (see  FIGS.  7  and  8   ). 
     Multiple control lines  2   c   1  are arranged parallel to each other at a prescribed spacing. For example, the control lines  2   c   1  extend in a row direction (corresponding to an example of a first direction). 
     One control line  2   c   1  is electrically connected with one of multiple wiring pads  2   d   1  located at the peripheral edge vicinity of the substrate  2   a.  One of multiple interconnects provided in a flexible printed circuit board  2   e   1  is electrically connected to one wiring pad  2   d   1 . The other ends of the multiple interconnects provided in the flexible printed circuit board  2   e   1  are electrically connected with a control circuit  31  included in the signal processing circuit  3 . 
     Multiple data lines  2   c   2  are arranged parallel to each other at a prescribed spacing. For example, the data lines  2   c   2  extend in a column direction (corresponding to an example of a second direction) orthogonal to the row direction. 
     One data line  2   c   2  is electrically connected with one of multiple wiring pads  2   d   2  located at the peripheral edge vicinity of the substrate  2   a.  One of multiple interconnects provided in a flexible printed circuit board  2   e   2  is electrically connected to one wiring pad  2   d   2 . The other ends of the multiple interconnects provided in the flexible printed circuit board  2   e   2  are electrically connected with a signal detection circuit  32  included in the signal processing circuit  3 . 
     The bias line  2   c   3  is provided parallel to the data line  2   c   2  between the data line  2   c   2  and the data line  2   c   2 . 
     A not-illustrated bias power supply is electrically connected to the bias line  2   c   3 . For example, a not-illustrated bias power supply can be included in the signal processing circuit  3 , etc. 
     The bias line  2   c   3  is not always necessary and may be included as necessary. When the bias line  2   c   3  is not included, the storage capacitor  2   b   3  and the anode side of the photoelectric conversion element  2   b   1  are electrically connected to ground instead of the bias line  2   c   3 . 
     For example, the control line  2   c   1 , the data line  2   c   2 , and the bias line  2   c   3  can be formed using a low-resistance metal such as aluminum, chrome, etc. 
     A protective layer  2   f  covers the photoelectric conversion part  2   b,  the control line  2   c   1 , the data line  2   c   2 , and the bias line  2   c   3 . 
     The protective layer  2   f  includes, for example, at least one of an oxide insulating material, a nitride insulating material, an oxynitride insulating material, or a resin material. 
     Multiple noise detecting parts  2   g  are provided as shown in  FIG.  3   . The multiple noise detecting parts  2   g  are arranged outside the region (the effective pixel region) in which the multiple photoelectric conversion parts  2   b  are located. The multiple noise detecting parts  2   g  are arranged along at least one of the control line  2   c   1  or the data line  2   c   2 . For example, as shown in  FIG.  3   , the multiple noise detecting parts  2   g  can be arranged along the data line  2   c   2 . In such a case, for example, the multiple noise detecting parts  2   g  also can be arranged along the control line  2   c   1 . For example, the multiple noise detecting parts  2   g  also can be arranged along the control line  2   c   1  and the data line  2   c   2 . 
     Although the multiple noise detecting parts  2   g  are located at one outer side of the effective pixel region in the illustration of  FIG.  3   , the multiple noise detecting parts  2   g  may be located at two outer sides, three outer sides, or four outer sides of the effective pixel region. 
     Each of the multiple noise detecting parts  2   g  includes a capacitance part  2   g   1  and the thin film transistor  2   b   2  (corresponding to an example of a second thin film transistor). The thin film transistor  2   b   2  is electrically connected to the corresponding control line  2   c   1  and the corresponding data line  2   c   2 . The capacitance part  2   g   1  is electrically connected with the thin film transistor  2   b   2 . 
     When the photoelectric conversion part  2   b  includes the storage capacitor  2   b   3 , the storage capacitor  2   b   3  also can be included in the noise detecting part  2   g.  For example, the storage capacitor  2   b   3  can be located under the capacitance part  2   g   1 . 
     For example, the capacitance part  2   g   1  can be formed from a conductive material such as a metal, etc. If the capacitance part  2   g   1  is formed from a conductive material, a signal charge is substantially not generated even when the fluorescence generated by the scintillator  5  is incident on the capacitance part  2   g   1 . For example, the capacitance part  2   g   1  can be formed from the same material as the electrode  2   b   1   b  of the photoelectric conversion element  2   b   1 . For example, the capacitance part  2   g   1  can be formed using a low-resistance metal such as aluminum, chrome, etc. 
     The gate electrode  2   b   2   a  of the thin film transistor  2   b   2  included in the noise detecting part  2   g  is electrically connected with the corresponding control line  2   c   1 . The drain electrode  2   b   2   b  of the thin film transistor  2   b   2  is electrically connected with the corresponding data line  2   c   2 . The source electrode  2   b   2   c  of the thin film transistor  2   b   2  is electrically connected to the corresponding capacitance part  2   g   1  and storage capacitor  2   b   3 . Details related to the noise detecting part  2   g  are described below. 
     The signal processing circuit  3  is located at the side of the array substrate  2  opposite to the scintillator  5  side. 
     As shown in  FIG.  2   , the signal processing circuit  3  includes the control circuit  31  and the signal detection circuit  32 . 
     The control circuit  31  switches between the on-state and the off-state of the thin film transistor  2   b   2 . 
     The control circuit  31  includes multiple gate drivers  31   a  and a row selection circuit  31   b.    
     A control signal S 1  is input from the image configuration circuit  4  or the like to the row selection circuit  31   b.  The row selection circuit  31   b  inputs the control signal S 1  to the corresponding gate driver  31   a  according to the scanning direction of the X-ray image. 
     The gate driver  31   a  inputs the control signal S 1  to the corresponding control line  2   c   1 . 
     For example, the control circuit  31  sequentially inputs the control signal S 1  via the flexible printed circuit board  2   e   1  to each control line  2   c   1 . 
     The thin film transistor  2   b   2  that is located in the photoelectric conversion part  2   b  is switched to the on-state by the control signal S 1  input to the control line  2   c   1 ; and the signal charge (an image data signal S 2 ) from the storage capacitor  2   b   3  can be received. 
     When the thin film transistor  2   b   2  is in the on-state, the signal detection circuit  32  reads the image data signal S 2  from the storage capacitor  2   b   3  via the data line  2   c   2  and the flexible printed circuit board  2   e   2  according to the sampling signal from the image configuration circuit  4 . 
     For example, the image data signal S 2  can be read as follows. 
     First, the thin film transistors  2   b   2  are sequentially set to the on-state by the control circuit  31 . By setting the thin film transistor  2   b   2  to the on-state, a certain charge is stored in the storage capacitor  2   b   3  via the bias line  2   c   3 . Then, the thin film transistors  2   b   2  are set to the off-state. When X-rays are irradiated, the X-rays are converted into fluorescence by the scintillator  5 . When the fluorescence is incident on the photoelectric conversion element  2   b   1 , a charge (electrons and holes) is generated by the photoelectric effect; the generated charge and the charge (the heterogeneous charge) stored in the storage capacitor  2   b   3  combine; and the stored charge is reduced. Then, the control circuit  31  sequentially sets the thin film transistors  2   b   2  to the on-state. The reduced charge (the image data signal S 2 ) stored in each storage capacitor  2   b   3  is read by the signal detection circuit  32  via the data line  2   c   2  according to the sampling signal. 
     Also, when the thin film transistors  2   b   2  are in the off-state, the signal detection circuit  32  reads the noise current (a noise signal N) from the noise detecting parts  2   g  via the data line  2   c   2  and the flexible printed circuit board  2   e   2 . 
     The image configuration circuit  4  is electrically connected with the signal detection circuit  32  via by an interconnect  4   a . The image configuration circuit  4  may be formed to have a continuous body with the signal processing circuit  3  or may perform wireless data communication with the signal detection circuit  32 . 
     The image configuration circuit  4  receives the image data signal S 2  that is read, sequentially amplifies the received image data signal S 2 , and converts the amplified image data signal S 2  (an analog signal) into a digital signal. Then, the image configuration circuit  4  configures an X-ray image based on the image data signal S 2  converted into the digital signal. The configured X-ray image data is output from the image configuration circuit  4  toward an external device. 
     The scintillator  5  is located on the region in which the multiple photoelectric conversion parts  2   b  are located and converts the incident X-rays into fluorescence. The scintillator  5  is provided to cover the effective pixel region on the substrate  2   a.    
     For example, the scintillator  5  can be formed using cesium iodide (CsI):thallium (TI), sodium iodide (NaI):thallium (TI), etc. In such a case, the scintillator  5  that is made of an aggregate of multiple columnar crystals is formed by forming the scintillator  5  by using vacuum vapor deposition, etc. 
     Also, for example, the scintillator  5  can be formed using gadolinium oxysulfide (Gd 2 O 2 S), etc. In such a case, a quadrilateral prism-shaped scintillator  5  can be provided for each photoelectric conversion part  2   b.    
     Furthermore, a not-illustrated reflective layer can be provided to cover the front side of the scintillator  5  (the X-ray incident surface side) to increase the utilization efficiency of the fluorescence and improve the sensitivity characteristics. 
     Also, a not-illustrated moisture-resistant body that covers the scintillator  5  and the not-illustrated reflective layer can be provided to suppress the degradation of the characteristics of the scintillator  5  and the characteristics of the not-illustrated reflective layer due to water vapor included in the air. 
     The noise detecting part  2   g  will now be described further. 
     The noise that appears in the X-ray image can be broadly divided into random noise and lateral noise. Random noise occurs in a uniform distribution over the entire X-ray image, and therefore has no specific pattern or contour. In contrast, lateral noise appears as a striation in the lateral direction or the longitudinal direction of the X-ray image. In such a case, because a human views the X-ray image, lateral noise that has patterns and/or contours affects the quality of the X-ray image much more than random noise without patterns or contours. It is therefore desirable to reduce lateral noise of the X-ray detector. 
     The source of the lateral noise is considered to be mainly the control circuit  31 . For example, there are cases where noise generated in the control circuit  31  and/or noise of the power supply line for driving the control circuit  31  enters the control line  2   c   1 . The thin film transistor  2   b   2  is electrically connected between the control line  2   c   1  and the data line  2   c   2 . It is therefore considered that noise does not enter the data line  2   c   2  from the control line  2   c   1  if the thin film transistor  2   b   2  is in the off-state. However, the photoelectric conversion element  2   b   1  is located at the vicinity of the thin film transistor  2   b   2 . Therefore, line-to-line capacitance (stray capacitance) may occur between the thin film transistor  2   b   2  and the electrode  2   b   1   b  of the photoelectric conversion element  2   b   1 ; and noise may enter the data line  2   c   2  from the control line  2   c   1  due to electrostatic coupling. Lateral noise is generated when noise enters the data line  2   c   2  from the control line  2   c   1 . 
     In such a case, the lateral noise can be reduced by reducing the noise generated in the control circuit  31  and the power supply line. However, such noise countermeasures may make the structure of the X-ray detector  1  complex and more expensive. 
     Therefore, generally, multiple noise detecting parts that detect the lateral noise are provided, and offset processing is performed by subtracting a value corresponding to the detected lateral noise from the value of the image data signal S 2  output from each photoelectric conversion part  2   b.    
       FIGS.  4  and  5    are schematic plan views for illustrating a noise detecting part  102   g  according to a comparative example. 
     The bias lines  2   c   3  are not illustrated in  FIGS.  4  and  5   . As shown in  FIGS.  4  and  5   , the photoelectric conversion element  2   b   1  that is included in the photoelectric conversion part  2   b  includes a semiconductor layer  2   b   1   a  having a p-n junction or p-i-n structure, and an electrode  2   b   1   b  located at the substrate  2   a  side of the semiconductor layer  2   b   1   a.  The electrode  2   b   1   b  is electrically connected with the source electrode  2   b   2   c  of the thin film transistor  2   b   2 . 
     The semiconductor layer  2   b   1   a  is not included in the noise detecting part  102   g.  In other words, the noise detecting part  102   g  includes the electrode  2   b   1   b,  the thin film transistor  2   b   2 , and the storage capacitor  2   b   3 . Because the noise detecting part  102   g  does not include the semiconductor layer  2   b   1   a,  the output from the noise detecting part  102   g  includes a value corresponding to the noise without including a value corresponding to the dose of the X-rays. 
     Therefore, an X-ray image in which the lateral noise is suppressed can be obtained by subtracting the value output from the noise detecting part  102   g  from the value of the image data signal S 2  output from each photoelectric conversion part  2   b . The value that is used in the offset processing can be the average value of values output from multiple noise detecting parts  102   g.    
     Here, in recent years, it is desirable to downsize the X-ray detector  1 . In such a case, the effective pixel region in which the multiple photoelectric conversion parts  2   b  are located is the region that performs the imaging of the X-ray detector  1 , and therefore is difficult to reduce. 
     Also, the multiple noise detecting parts  102   g  are arranged outside the effective pixel region. For example, as shown in  FIG.  4   , there are cases where the multiple noise detecting parts  102   g  are arranged in the direction in which the data line  2   c   2  extends. As shown in  FIG.  5   , there are cases where the multiple noise detecting parts  102   g  are arranged in the direction in which the control line  2   c   1  extends. There are also cases where the multiple noise detecting parts  102   g  are arranged in the direction in which the data line  2   c   2  extends and the direction in which the control line  2   c   1  extends. 
       FIG.  6    is a schematic plan view illustrating the location of a region  202  in which the multiple noise detecting parts  102   g  are located. 
     As shown in  FIG.  6   , the region  202  in which the multiple noise detecting parts  102   g  are located is positioned outside an effective pixel region  201 . In the case of the illustration of  FIG.  6   , one region  202  is located at each of two sides of the effective pixel region  201 . 
     Therefore, the X-ray detector is larger by the size of the regions  202  included. 
     Here, the region  202  is not a region that performs the imaging of the X-ray detector  1 , and therefore can be reduced as long as the lateral noise can be detected. 
     Therefore, the region  202  of the X-ray detector  1  according to the embodiment is reduced. 
       FIGS.  7  and  8    are schematic plan views for illustrating the noise detecting part  2   g  according to the embodiment. 
     The bias lines  2   c   3  are not illustrated in  FIGS.  7  and  8   . 
     As shown in  FIGS.  7  and  8   , the noise detecting part  2   g  includes the capacitance part  2   g   1 , the thin film transistor  2   b   2 , and the storage capacitor  2   b   3 . Because the capacitance part  2   g   1  does not include the semiconductor layer  2   b   1   a,  the output from the noise detecting part  2   g  includes a value corresponding to the noise but does not include a value corresponding to the dose of the X-rays. 
     As described above, when line-to-line capacitance occurs between the thin film transistor  2   b   2  and the electrode  2   b   1   b  of the photoelectric conversion element  2   b   1 , noise enters the data line  2   c   2  from the control line  2   c   1  due to electrostatic coupling. 
     Therefore, an appropriate value of the lateral noise can be detected if the line-to-line capacitance between the capacitance part  2   g   1  and the thin film transistor  2   b   2  is about equal to the line-to-line capacitance between the electrode  2   b   1   b  and the thin film transistor  2   b   2 . 
     To generate about the same line-to-line capacitance, it is sufficient to set dimensions S 3  and S 4  between the capacitance part  2   g   1  and the thin film transistor  2   b   2  to be respectively about equal to dimensions S 1  and S 2  between the electrode  2   b   1   b  and the thin film transistor  2   b   2 . In other words, it is sufficient for the gap dimension between the capacitance part  2   g   1  and the thin film transistor  2   b   2  included in the noise detecting part  2   g  to be substantially equal to the gap dimension between the electrode  2   b   1   b  and the thin film transistor  2   b   2  included in the photoelectric conversion part  2   b.  Substantially the same or equal means that differences of about the manufacturing error are acceptable. 
     In such a case, it is favorable for the material of the capacitance part  2   g   1  to be the same as the material of the electrode  2   b   1   b.  It is favorable for the thickness of the capacitance part  2   g   1  to be about equal to the thickness of the electrode  2   b   1   b.    
     Also, it is favorable for the lengths of sides  2   g   1   a  and  2   g   1   b  of the capacitance part  2   g   1  at the sides facing the thin film transistor  2   b   2  to be about equal to the lengths of sides  2   b   2   d  and  2   b   2   e  of the electrode  2   b   1   b  at the sides facing the thin film transistor  2   b   2 . 
     However, the position of a side  2   g   1   c  of the capacitance part  2   g   1  that faces the side  2   g   1   a  and the position of a side  2   g   1   d  of the capacitance part  2   g   1  that faces the side  2   g   1   b  have little effect on the line-to-line capacitance. 
     Therefore, when the multiple noise detecting parts  2   g  are arranged along the data line  2   c   2  as shown in  FIG.  7   , a length Lg 1  of the capacitance part  2   g   1  in a direction orthogonal to the direction in which the data line  2   c   2  extends can be less than a length Lb 1  of the electrode  2   b   1   b  in the direction orthogonal to the direction in which the data line  2   c   2  extends. 
     Also, when the multiple noise detecting parts  2   g  are arranged along the control line  2   c   1  as shown in  FIG.  8   , a length Lg 2  of the capacitance part  2   g   1  in a direction orthogonal to the direction in which the control line  2   c   1  extends can be less than a length Lb 2  of the electrode  2   b   1   b  in the direction orthogonal to the direction in which the control line  2   c   1  extends. 
     Although a case where the length Lg 1  or the length Lg 2  is reduced is illustrated above, the length Lg 1  and the length Lg 2  also can be reduced. 
     In other words, the length of the capacitance part  2   g   1  is less than the length of the electrode  2   b   1   b  in at least one of the direction in which the control line  2   c   1  extends or the direction in which the data line  2   c   2  extends. 
     The capacitance part  2   g   1  may be the electrode  2   b   1   b  with a portion removed. Thus, the multiple capacitance parts  2   g   1  and the multiple electrodes  2   b   1   b  can be formed in the same process; therefore, the productivity can be increased, and the manufacturing cost can be reduced. 
       FIGS.  9 A and  9 B  are schematic plan views for illustrating the location of a region  203  in which the multiple noise detecting parts  2   g  are located. 
     As shown in  FIGS.  9 A and  9 B , the region  203  in which the multiple noise detecting parts  2   g  are located can be located outside the effective pixel region  201 . 
     For example,  FIG.  9 A  is the case illustrated in  FIG.  7   , that is, the case where the multiple noise detecting parts  2   g  are arranged along the data line  2   c   2 . In such a case, for example, as shown in  FIG.  9 A , one region  203  in which the multiple noise detecting parts  2   g  are located can be located at each of the two sides of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged. 
     For example,  FIG.  9 B  is the case illustrated in  FIG.  8   , that is, the case where the multiple noise detecting parts  2   g  are arranged along the control line  2   c   1 . In such a case, for example, as shown in  FIG.  9 B , one region  203  in which the multiple noise detecting parts  2   g  are located can be located at each of the two sides of the effective pixel region  201  in the direction in which the multiple control lines  2   c   1  are arranged. 
     Thus, as shown in  FIG.  9 A , the X-ray detector  1  becomes larger by the amount of the region  203  that is included. However, as shown in  FIG.  7   , the length Lg 1  of the capacitance part  2   g   1  in the direction orthogonal to the direction in which the data line  2   c   2  extends is less than the length Lb 1  of the electrode  2   b   1   b  in the direction orthogonal to the direction in which the data line  2   c   2  extends. Therefore, the region  203  can be smaller than the region  202  according to the comparative example. 
     Also, as shown in  FIG.  9 B , the X-ray detector  1  becomes larger by the amount of the region  203  included. However, as shown in  FIG.  8   , the length Lg 2  of the capacitance part  2   g   1  in the direction orthogonal to the direction in which the control line  2   c   1  extends is less than the length Lb 2  of the electrode  2   b   1   b  in the direction orthogonal to the direction in which the control line  2   c   1  extends. Therefore, the region  203  can be smaller than the region  202  according to the comparative example. 
     Also, one region  203  can be located at one side of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged or the direction in which the multiple control lines  2   c   1  are arranged. 
     Thus, the noise can be detected, and the X-ray detector  1  size increase can be further suppressed. 
     Also, one region  203  can be located at each of the two sides of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged and the direction in which the multiple control lines  2   c   1  are arranged. In other words, the region  203  can be provided to surround the effective pixel region  201 . In such a case as well, the region  203  can be smaller than the region  202  according to the comparative example. 
     As described above, the region  203  can be located on at least one side of the effective pixel region  201 . 
     As described above, the value that is used in the offset processing can be the average value of the values output from the multiple noise detecting parts  2   g.  Therefore, by increasing the number of the noise detecting parts  2   g,  the noise can be detected with high accuracy, which in turn can increase the accuracy of the lateral noise removal. In such a case, the number of the noise detecting parts  2   g  can be increased by increasing the number of the regions  203 . 
     If, however, the number of the regions  203  is increased, the X-ray detector  1  will become larger commensurately. However, as described above, the region  203  can be smaller than the region  202  according to the comparative example. Therefore, even when the number of the regions  203  is increased, the X-ray detector  1  size increase can be suppressed. The number and arrangement of the regions  203  can be appropriately determined according to the specifications of the X-ray detector  1 , etc. 
     According to the X-ray detector  1  according to the embodiment as described above, the lateral noise can be detected. Also, the region  203  in which the multiple noise detecting parts  2   g  are located can be reduced. Therefore, the noise can be detected, and the X-ray detector  1  size increase can be suppressed. 
     Here, as described above, the value that is used in the offset processing can be the average value of values output from the multiple noise detecting parts  2   g.  Therefore, by increasing the number of the noise detecting parts  2   g,  the noise can be detected with high accuracy, which in turn can increase the accuracy of the lateral noise removal. 
     For example, multiple noise detecting parts  2   g  can be electrically connected to each of the multiple data lines  2   c   2 . For example, multiple noise detecting parts  2   g  can be electrically connected to each of the multiple control lines  2   c   1 . In other words, the multiple regions  203  can be arranged. Thus, because the number of the noise detecting parts  2   g  can be increased, the noise can be detected with high accuracy, which in turn can increase the accuracy of the lateral noise removal. 
       FIGS.  10  and  11    are schematic plan views for illustrating arrangements of the noise detecting part  2   g  according to other embodiments. 
     The bias lines  2   c   3  are not illustrated in  FIGS.  10  and  11   . 
       FIGS.  12 A and  12 B  are schematic plan views for illustrating locations of the region  203 . 
     As shown in  FIG.  10   , for example, multiple noise detecting parts  2   g  can be electrically connected to each of two data lines  2   c   2 . In such a case, for example, as shown in  FIG.  12 A , two regions  203  can be located at each of the two sides of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged. Or, for example, two regions  203  can be located at one side of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged. 
     As shown in  FIG.  11   , for example, multiple noise detecting parts  2   g  can be electrically connected to each of two control lines  2   c   1 . In such a case, for example, as shown in  FIG.  12 B , two regions  203  can be located at each of the two sides of the effective pixel region  201  in the direction in which the multiple control lines  2   c   1  are arranged. Also, for example, two regions  203  can be located at one side of the effective pixel region  201  in the direction in which the multiple control lines  2   c   1  are arranged. 
     Also, two regions  203  can be located at two sides of the effective pixel region  201  in the direction in which the multiple data lines  2   c   2  are arranged and the direction in which the multiple control lines  2   c   1  are arranged. In other words, double regions  203  can be provided to surround the effective pixel region  201 . 
     Although a case is illustrated where two regions  203  are located on at least one side of the effective pixel region  201 , the regions  203  can be located on at least three sides. 
     For example, the multiple data lines  2   c   2  to which the thin film transistor  2   b   2  (the second thin film transistors) included in the multiple noise detecting parts  2   g  are electrically connected can be arranged adjacently in the first direction outside the region (the effective pixel region  201 ) in which the multiple photoelectric conversion parts  2   b  are located. 
     For example, the multiple control lines  2   c   1  to which the thin film transistor  2   b   2  (the second thin film transistors) included in the multiple noise detecting parts  2   g  are electrically connected can be arranged adjacently in the second direction outside the region (the effective pixel region  201 ) in which the multiple photoelectric conversion parts  2   b  are located. 
     However, when the number of the regions  203  is increased, the X-ray detector  1  becomes larger commensurately. However, as described above, the region  203  can be smaller than the region  202  according to the comparative example. Therefore, even when the number of the regions  203  is increased, the X-ray detector  1  size increase can be suppressed. The number and arrangement of the regions  203  can be appropriately determined according to the specifications of the X-ray detector  1 , etc. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. Moreover, above-mentioned embodiments can be combined mutually and can be carried out.