JP6618251B2 - Radiation imaging apparatus and radiation imaging system - Google Patents

Description

  The present invention relates to a radiation imaging apparatus and a radiation imaging system.

  Radiation imaging apparatus having a matrix substrate having a pixel array in which a switch such as a TFT (thin film transistor) and a conversion element such as a photoelectric conversion element are used as a radiation imaging apparatus used for medical image diagnosis and nondestructive inspection using radiation such as X-rays Has been put to practical use.

  In recent years, multi-functionalization of radiation imaging apparatuses has been studied. As one of them, it is considered to incorporate a function for monitoring the irradiation of radiation. With this function, for example, it is possible to detect the timing at which radiation irradiation from the radiation source is started, to detect the timing at which radiation irradiation should be stopped, and to detect the radiation dose or integrated dose.

  Patent Document 1 discloses a radiation imaging apparatus including an imaging pixel for acquiring a radiation image and a detection pixel for detecting radiation. And the structure which reads the signal for detecting a radiation via the switch element connected with the said detection pixel is disclosed. Then, in order to switch the conduction state of the switch element when reading the signal of the detection pixel, the driving voltage is appropriately switched between a conduction voltage and a non-conduction voltage.

JP 2012-15913 A

  However, in the radiation imaging apparatus of Patent Document 1, when the drive voltage is switched, it is caused by a parasitic element (parasitic capacitance) between the control line connected to the switch element and the signal line as the voltage of the control line changes. As a result, the potential of the signal line may fluctuate. For this reason, the detection accuracy of radiation irradiation may be insufficient due to the potential fluctuation of the signal line.

  The present invention provides a technique advantageous for accurately reading out radiation irradiation while suppressing potential fluctuations generated in a signal line due to switching of a control signal to a switch element of a radiation detection pixel.

One aspect of the present invention includes a plurality of imaging pixels for acquiring a radiation image, a detection conversion element for detecting the incidence of radiation, and a detection switch element connected to the detection conversion element. A radiation imaging apparatus including a plurality of detection pixels, wherein a signal line commonly connected to two or more detection switch elements among the plurality of detection pixels and a detection line commonly connected to the signal line A drive unit for driving the switch element and a first voltage from an off voltage to an on voltage with respect to a voltage applied to at least one of the two or more detection switch elements commonly connected to the signal line . upon to perform the change, said at least one different from that of the on-voltage so that the change of the polarity opposite from that of the first change to the voltage applied to the different detection switch element and the sensing switch element The first voltage is changed to the on voltage and the second voltage different from the first voltage, and the different voltage for detection is applied while the on voltage is applied to the at least one detection switch element. When the second voltage is applied to the switch element and the second change from the on voltage to the off voltage is performed on the voltage applied to the at least one detection switch element, the different detection is performed. A control unit that controls the drive unit so that the voltage applied to the switch element is changed from the second voltage to the first voltage having a polarity opposite to that of the second change. A radiation imaging apparatus comprising:

  The present invention provides a technique advantageous for accurately reading out radiation irradiation while suppressing potential fluctuations generated in a signal line due to switching of a control signal to a switch element of a radiation detection pixel.

It is a figure which shows the structure of the radiation imaging device in 1st embodiment. It is a figure which shows the structural example of the radiation imaging system containing a radiation imaging device. It is a figure which shows the imaging pixel of the radiation imaging device in 1st embodiment. It is a figure which shows the detection pixel of the radiation imaging device in 1st embodiment. It is a figure which shows operation | movement of the radiation imaging device in 1st embodiment. It is a figure which shows operation | movement of the radiation imaging device in 2nd embodiment. It is a figure which shows the structure of the radiation imaging device in 3rd embodiment. It is a figure which shows the detection pixel of the radiation imaging device in 3rd embodiment. It is a figure which shows operation | movement of the radiation imaging device in 4th embodiment. It is a figure which shows the application example of a radiation imaging device.

  Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. In each embodiment, radiation is a beam having energy of the same degree or more in addition to α rays, β rays, γ rays, etc., which are beams formed by particles (including photons) emitted by radiation decay, For example, X-rays, particle beams, and cosmic rays are also included.

(First embodiment)
The first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a radiation imaging apparatus according to the first embodiment. Here, FIG. 1 shows an example in which pixels of 9 rows and 9 columns are provided, but 1000 × 1000 pixels may be provided, or 5000 × 5000 pixels may be provided.

  The radiation imaging apparatus 200 in FIG. 1 includes a plurality of imaging pixels 1 for acquiring a radiation image, a plurality of detection elements 6 for detecting the incidence of radiation, and a plurality of switch elements 7 connected to the conversion elements. The detection pixel 2 is provided. Further, the radiation imaging apparatus 200 includes at least the detection signal line 12, the drive unit 52, and the control unit 55.

  In the following description, in the plurality of imaging pixels 1 and the plurality of detection pixels 2, the arrangement of pixels arranged in the direction in which the signal line 10 extends is defined as the column direction, and the arrangement of pixels arranged in the direction orthogonal to the column direction is defined as the row direction. And

  The imaging pixel 1 is a pixel for acquiring a radiation image, and includes an imaging conversion element 4 and a first switch element 5. The detection pixel 2 is a pixel having a function for detecting the incidence of radiation, and includes an imaging conversion element 4 and a first switch element 5, a detection conversion element 6 and a second switch element 7. The For this reason, in this embodiment, the detection pixel 2 has a function for detecting the incidence of radiation and a function for acquiring a radiation image. Although the detection pixel 2 has been described with a configuration including the imaging conversion element 4 and the first switch element 5, and the detection conversion element 6 and the second switch element 7, the present invention is not limited thereto. For example, the detection pixel 2 may be configured by only the detection conversion element 6 and the second switch element 7. In this case, the detection conversion element 6 of the detection pixel 2 may be arranged in the same size as the imaging conversion element 4 of the imaging pixel 1, and details will be described in the third embodiment. The imaging switch element in the present invention corresponds to the first switch element 5 in the present embodiment. The detection switch element in the present invention corresponds to the second switch element 7 in the present embodiment.

  The imaging conversion element 4 and the detection conversion element 6 can be composed of a scintillator (not shown) that converts radiation into light and a photoelectric conversion element that converts light into an electrical signal. For example, the scintillator is formed in a sheet shape so as to cover the imaging region, and can be shared by the plurality of imaging pixels 1 and the plurality of detection pixels 2. Alternatively, the imaging conversion element 4 and the detection conversion element 6 may be configured by a conversion element that directly converts radiation into an electrical signal.

  The first switch element 5 and the second switch element 7 can include, for example, a thin film transistor (TFT) in which an active region is formed of a semiconductor such as amorphous silicon or polycrystalline silicon.

  The imaging conversion element 4 is connected to the reading unit 51 via the first switch element 5 and the signal line 10 (S1 to S9). The detection conversion element 6 is connected to the reading unit 51 via the second switch element 7 and the detection signal line 12. The detection signal line 12 is commonly connected to at least two or more second switch elements 7 among the plurality of detection pixels 2.

  All the pixels are connected to a common bias wiring 11, and a predetermined bias voltage is applied from a bias power supply 53. The first switch elements 5 arranged in a predetermined row are connected to the first control line 8 (Vg1 to Vg9). The second switch element 7 is connected to the second control line 9 (Vd1 to Vd3).

  In FIG. 1, nine radiation detection areas (ROI) for detecting radiation are provided (R1 to R9 in FIG. 1). In this radiation detection region (ROI), detection pixels 2 are arranged. The detection pixels 2 of R1, R2, and R3 are connected to a common detection signal line 12 (D1 in FIG. 1). Similarly, the detection pixels 2 of R4, R5, and R6 are connected to a common detection signal line 12 (D2 in FIG. 1), and the detection pixels 2 of R7, R8, and R9 are connected to a common detection signal line 12 (D3 in FIG. 1). )It is connected to the.

  In FIG. 1, nine radiation detection regions (ROIs) of 3 × 3 are arranged, but this is not a limitation. For example, the radiation detection region (ROI) may be provided in 25 regions of 5 × 5 or 100 regions of 10 × 10. About a radiation detection area | region (ROI), you may arrange | position so that it may become equal on a board | substrate, and may arrange | position a radiation detection area | region (ROI) so that it may be biased to a specific range. In the present embodiment, an example is shown in which one detection pixel 2 is arranged in each radiation detection region (ROI). However, a plurality of detection pixels 2 are arranged in one radiation detection region (ROI). You may do it. In this case, a plurality of detection pixels 2 may be connected in the row or column direction. In addition, arrangement | positioning of the imaging pixel 1 and the detection pixel 2 is an example, and is not limited to the said arrangement | positioning.

  The reading unit 51 may include a plurality of detection units 132, a multiplexer 144, and an analog-digital converter 146 (hereinafter referred to as ADC). Each of the plurality of signal lines 10 and the plurality of detection signal lines 12 is connected to a corresponding detection unit 132 among the plurality of detection units 132 of the reading unit 51. Here, one signal line 10 or detection signal line 12 corresponds to one detection unit 132. The detection unit 132 includes, for example, a differential amplifier and a sample hold circuit. The multiplexer 144 selects a plurality of detection units 132 in a predetermined order, and supplies a signal from the selected detection unit 132 to the ADC 146. The ADC 146 converts the supplied signal into a digital signal and outputs the digital signal. The output of the ADC 146 is supplied to the signal processing unit 224 and processed by the signal processing unit 224. The signal processing unit 224 outputs information indicating radiation irradiation to the radiation imaging apparatus 200 based on the output of the ADC 146. Specifically, the signal processing unit 224 detects, for example, radiation irradiation on the radiation imaging apparatus 200 or calculates a radiation dose or an integrated dose.

  The drive unit 52 drives the plurality of imaging pixels 1 via the first control line 8. Further, the drive unit 52 drives the plurality of detection pixels 2 via the second control line 9. The drive unit 52 and the first control line 8 and the second control line 9 are electrically connected. In the present embodiment, the Von voltage indicates a voltage that makes the first switch element 5 and the second switch element 7 conductive. The Voff1 voltage indicates the voltage at which the first switch element 5 and the second switch element 7 are turned off. Voff2 is a voltage having a polarity opposite to that of Von with respect to Voff1. That is, Voff2 is a non-conducting voltage having a larger potential difference with respect to Von than Voff1.

  The control unit 55 controls the driving unit 52 and the reading unit 51. Based on the information from the signal processing unit 224, the control unit 55 controls, for example, the start and end of exposure (accumulation of charge corresponding to radiation irradiated by the imaging pixel 1). That is, the control unit 55 can measure the amount of radiation incident based on the amount of radiation detected by the detection conversion element 6.

  FIG. 2 illustrates a configuration of a radiation imaging system including the radiation imaging apparatus 200. In addition to the radiation imaging apparatus 200, the radiation imaging system includes a controller 1002, an interface 1003, a radiation source interface 1004, and a radiation source 1005.

  The controller 1002 can receive a dose A, an irradiation time B (ms), a tube current C (mA), a tube voltage D (kV), a radiation detection region (ROI) that is a region where radiation should be monitored, and the like. When the explosion switch attached to the radiation source 1005 is operated, radiation is emitted from the radiation source 1005. For example, when the integrated value of the signal read from the detection pixel 2 arranged in the radiation detection region (ROI) reaches the dose A ′, the control unit 55 of the radiation imaging apparatus 200 receives the radiation source interface via the interface 1003. An exposure stop signal is sent to 1004. In response, the radiation source interface 1004 causes the radiation source 1005 to stop emitting radiation. Here, the dose A ′ can be determined by the control unit 55 based on the dose A, the radiation irradiation intensity, the communication delay between the units, the processing delay, and the like. When the irradiation time of the radiation reaches the irradiation time B, the radiation source 1005 stops the irradiation of radiation regardless of the presence or absence of the explosion stop signal.

  Next, the configuration of the imaging pixel will be described with reference to FIG. FIG. 3A is a plan view of the imaging pixel 1, and FIG. 3B is a cross-sectional view taken along the line A-A ′ of the imaging pixel 1.

  The imaging pixel 1 in this embodiment includes an imaging conversion element 4 and a first switch element 5 that outputs an electrical signal corresponding to the charge of the imaging conversion element 4. The imaging conversion element 4 is disposed on a first switch element 5 provided on an insulating substrate 100 such as a glass substrate, with a first interlayer insulating layer 110 interposed therebetween. The first switch element 5 is formed on the substrate 100 in order from the substrate 100 side in order from the control electrode 101, the first insulating layer 102, the first semiconductor layer 103, and the first semiconductor layer 103. A high-concentration first impurity semiconductor layer 104, a first main electrode 105, and a second main electrode 106 are included. The first impurity semiconductor layer 104 is in contact with the first main electrode 105 and the second main electrode 106 in a partial region, and a region between the regions of the first semiconductor layer 103 in contact with the partial region is the first region. It becomes a channel region of one switch element 5. The control electrode 101 is electrically joined to the control line, the first main electrode 105 is electrically joined to the signal line 10, and the second main electrode 106 is electrically joined to the individual electrode 111 of the conversion element. Has been. In the present embodiment, the first main electrode 105, the second main electrode 106, and the signal line 10 are integrally formed of the same conductive layer, and the first main electrode 105 forms part of the signal line 10. . On the 1st main electrode 105, the 2nd main electrode 106, and the signal line 10, the 2nd insulating layer 107 and the 1st interlayer insulation layer 110 are arrange | positioned in an order from the signal line 10 side. In this embodiment, an inverted stagger type switch element using a semiconductor layer mainly made of amorphous silicon and an impurity semiconductor layer is used as the switch element, but the present invention is not limited to this. For example, a staggered switch element whose main material is polycrystalline silicon can be used, or an organic TFT, an oxide TFT, or the like can be used as a switch element. The first interlayer insulating layer 110 is disposed between the substrate 100 and the plurality of individual electrodes 111 so as to cover the first switch element 5 and has a contact hole. The individual electrode 111 and the second main electrode 106 of the imaging conversion element 4 are electrically joined in a contact hole provided in the first interlayer insulating layer 110. The imaging conversion element 4 includes, on the first interlayer insulating layer 110, in order from the first interlayer insulating layer side, the individual electrode 111, the second impurity semiconductor layer 112, the second semiconductor layer 113, A third impurity semiconductor layer 114 and a common electrode 115 are included. A third insulating layer 116 is disposed on the common electrode 115 of the imaging conversion element 4. In addition, the bias electrode 11 disposed on the second interlayer insulating layer 120 is electrically joined to the common electrode 115 of the imaging conversion element 4. A fourth insulating layer 121 as a protective film is disposed on the bias wiring 11.

  Next, the configuration of the detection pixel will be described with reference to FIG. FIG. 4A is a plan view of the detection pixel 2, and FIG. 4B is a cross-sectional view taken along B-B '.

  The detection pixel 2 in the present embodiment includes an imaging conversion element 4 and a first switch element 5, a detection conversion element 6 and a second switch element 7. The detection conversion element 6 is laminated on the first interlayer insulating layer 110 with the same structure as the imaging conversion element 4 of the imaging pixel 1. The bias wiring 11 disposed on the second interlayer insulating layer 120 is electrically joined to the common electrode 115 of the imaging conversion element 4 and the detection conversion element 6. Further, the individual electrode 111 of the detection conversion element 6 is connected to the detection signal line 12 through a contact hole provided in the first interlayer insulating layer 110. A second insulating layer 107 and a first interlayer insulating layer 110 are disposed on the detection signal line 12 in this order from the detection signal line 12 side.

  In addition, since the opening area of the imaging conversion element 4 is smaller in the detection pixel 2 than in the imaging pixel 1 in the present embodiment, the signal amount from the detection pixel 2 is reduced. The influence of this can be reduced by adjusting the gain of the detection unit 132 or correcting the captured image. The correction can be realized by processing such as interpolation using the values of the imaging pixels 1 around the detection pixels 2. In the present embodiment, the imaging conversion element 4 and the detection conversion element 6 are PIN type sensors, but the present invention is not limited to this, and MIS type and TFT type sensors may be used.

  Next, the operation of the radiation imaging apparatus of this embodiment will be described using the timing chart of FIG. In the following description, the voltage applied to the first control line 8 that drives the imaging pixel 1 is signals Vg1 to Vgm (m is equivalent to 9 in FIG. 1), and the second control that drives the detection pixel 2 is performed. The voltages applied to the line 9 are Vd1 to Vd3. The first switch element 5 and the second switch element 7 become conductive when the signal supplied to the gate is at a high level, and become non-conductive when the signal supplied to the gate is at a low level. The combination of the signal level and the conduction state can be determined by a combination of the circuit configuration and the conductivity type of the switch element. Further, the operations of the reading unit 51 and the driving unit 52 shown in FIG. 5 operate based on the control of the control unit 55 as described above. In FIG. 5, the high level is expressed as “Von” and the low level is expressed as “Voff”. The “on voltage” in the present invention corresponds to “Von” in the present embodiment. The “off voltage” in the present invention corresponds to “Voff” in the present embodiment.

  First, the period T1 in FIG. 5 will be described. The period T1 is a period for waiting for the start of radiation irradiation. In the present embodiment, the period from when the radiation imaging apparatus 200 is turned on and the radiation image can be captured until the radiation switch of the radiation source 1005 is operated and radiation irradiation is detected is a period. T1. During the period T1, a voltage Von is sequentially applied to the first switch element 5 and the second switch element 7, and the individual electrodes 111 of the imaging conversion element 4 and the detection conversion element 6 are connected to the signal line 10 and the detection. The potential of the signal line 12 is reset. The second switch element 7 may be in a state where Von is always applied. This prevents charges due to dark current from being accumulated in the conversion element of the image sensor 1 for a long time. The length of the period T1 varies greatly depending on the imaging technique, conditions, etc., but can be several seconds to several minutes, for example.

  Next, the period T2 in FIG. 5 will be described. The period T2 is a period during which radiation is applied. As an example, the period T2 is a period from when the start of radiation irradiation is detected until the radiation exposure amount reaches the optimum dose. It can be said that the period T2 is a period during which the radiation dose is monitored. In the period T2, Von is intermittently applied to Vd1 to Vd3, and the second switch 7 of the detection pixel 2 is intermittently turned on. Since Voff1 is always applied to Vg1 to Vgm, the first switch element 5 is in a non-conductive state. Here, when applying Von or Voff to the second switch element 7, the potential of the detection signal line 12 may be changed via a parasitic capacitance between the second control line 9 and the detection signal line 12. . For example, charges are instantaneously injected from the second control line 9 to the detection signal line 12 via the parasitic capacitance based on the application of Von or Voff, and the potential of the detection signal line 12 is changed. In this case, charges based on the parasitic capacitance appearing on the detection signal line 12 are transferred to the reading unit 51 via the detection signal line 12. Here, the parasitic capacitance indicates a capacitance component caused by the material of the detection signal line 12, the physical structure, the distance from other wirings, the dielectric constant of the substance between the other wirings, and the like.

  The drive unit 52 applies Von or Voff (on or off voltage) to at least one second switch 7 among the two or more second switches 7 commonly connected to the detection signal line 12. A voltage having a polarity opposite to that of the switch element receiving the voltage is applied to the second switch element 7 different from the second switch to which the voltage is applied. As shown in a period T2 in FIG. 5, the driving unit 52 applies Voff2 having a polarity opposite to that of Von to Vd2 so as to overlap with a timing at which Von is applied to Vd1. Here, the overlapping timing is preferably simultaneous, but is not limited thereto. For example, the charge injected due to the parasitic capacitance can be substantially suppressed by applying Von or Voff to one of the two or more second switches 7 commonly connected to the detection signal line 12. If the timing is correct, it is not necessary to completely match. Further, “substantially can be suppressed” only needs to be a level that can suppress the influence of the charge due to the parasitic capacitance to the extent that the detection accuracy is satisfied by using the signal from the detection pixel 2 as a detection system.

The voltages Von, Voff1, and Voff2 are defined based on the capacitance between the second control line 9 and the detection signal line 12. Here, using equations, the influence of the parasitic capacitance and each voltage in the present embodiment will be described using equations. For example, when the Von voltage is applied to Vd1, the charge that appears on the detection signal line 12 via the parasitic capacitance is Q, the parasitic capacitance between the second control line 9 and the detection signal line 12 is Cgs, and Von is applied simultaneously. If the number of the second control lines is n, the charge Q is expressed as in Equation 1.
Q = Cgs × (Von−Voff) × n Equation 1
In order to cancel the charge Q, the driving unit 52 applies the Voff2 voltage to Vd2 at the same time as the Von voltage is applied to Vd1. Then, if the charge generated when the Voff2 voltage is applied to Vd2 is Q ′, and the number of the second control lines to which the Von voltage is applied at the same time is m, Q ′ is expressed by Equation 2.
Q ′ = Cgs × (Voff−Voff2) × m Equation 2
In this embodiment, since n = m = 1,
(Von−Voff) = (Voff−Voff2) Equation 3
The voltages Von, Voff, and Voff2 may be defined so that

  At the same time when Vd1 returns from the Von voltage to the VOFF voltage, Vd2 is returned from the Voff2 voltage to the Voff1 voltage. As a result, the charge generated due to the parasitic capacitance at the timing of switching Von or Voff of Vd1 can be reduced. Then, in the line D1, sample holding is performed by the detection unit 132 at a timing when the ON period of the second switch element 7 ends, and the charge of the detection signal line 12 is reset. With this control, the reading unit 51 can suppress the charge generated due to the parasitic capacitance of the signal of the detection conversion element 6 and can read out the necessary detection signal with high accuracy. Then, after the radiation irradiation amount read by the reading unit 51 reaches a set value, the control unit 55 can send a signal to the outside via the communication IF 1003 to control radiation irradiation.

  Next, the period T3 in FIG. 5 will be described. The period T3 is a period for reading out signals accumulated in the imaging pixels 1 by radiation after the radiation irradiation is completed. In the period T3, the drive units Vd1 to Vdn are set to a low level. In the period T3, the detection signal line 12 is preferably connected to a fixed potential in order to prevent the detection signal line 12 from floating. Further, in order to scan the first control line 7, a Von voltage is sequentially applied to Vg <b> 1 to Vg <b> 9, and a signal accumulated in the imaging conversion element 4 is transferred to the reading unit 51 via the signal line 10.

  In the first embodiment, as described above, the radiation detection pixels sequentially read out during radiation irradiation (corresponding to the period T2). For this reason, since a small signal is acquired at a frequency higher than that of reading out the imaging pixels, the influence of parasitic capacitance tends to appear in the detection signal. Therefore, the control unit 55 causes the drive unit 52 to apply an on voltage or an off voltage to at least one detection switch 7 among the two or more detection switches 7 connected in common to the detection signal line 12. In this case, the drive unit 52 applies a signal having a polarity opposite to that of the switch element receiving the signal to the detection switch 7 different from the detection switch to which the voltage is applied. Thereby, the potential fluctuation generated in the detection signal line due to the switching of the control signal to the switch element of the radiation detection pixel can be suppressed. And in the radiation imaging device of 1st embodiment, irradiation of a radiation can be read with high precision, and it can contribute to realization of more suitable dose control and exposure control.

(Second embodiment)
A second embodiment will be described with reference to FIG. FIG. 6 is a diagram illustrating the operation of the radiation imaging apparatus according to the second embodiment. The configuration of the radiation imaging apparatus of this embodiment is the same as that of the first embodiment. The control unit 55 causes the drive unit 52 to apply an on voltage or an off voltage to at least one detection switch 7 among the two or more detection switches 7 connected in common to the detection signal line 12. The difference from the first embodiment is that, in this case, a voltage having a polarity opposite to that of the switch receiving the voltage is applied to a plurality of second switches 7 different from the second switch to which the voltage is applied. It is a point. Specifically, in the period T2 in FIG. 6, the driving unit 52 supplies Vd2 and Vd3 with a Voff2 voltage having a polarity opposite to that of the Von voltage so as to overlap with the timing when the Von voltage is applied to Vd1. A suitable voltage at this time can be calculated using Equation 1 and Equation 2. In the second embodiment, since the voltages Vd2 and Vd3 are changed at overlapping timings, n = 1 and m = 2. In this case, the relationship between these voltages is expressed by Equation 4.
(Von−Voff) = 2 × (Voff−Voff2) Equation 4
As described above, potential fluctuations generated in the detection signal line due to switching of the control signal to the switch element of the radiation detection pixel can be suppressed. And in the radiation imaging device of 1st embodiment, irradiation of a radiation can be read with high precision, and it can contribute to realization of more suitable dose control and exposure control.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. FIG. 7 is a diagram showing a configuration of a radiation imaging apparatus according to the third embodiment. FIG. 8 is a diagram illustrating the structure of a detection pixel according to the third embodiment. Here, FIG. 7 shows an example in which pixels of 9 rows and 9 columns are provided, but 1000 × 1000 pixels may be provided, or 5000 × 5000 pixels may be provided. As shown in FIG. 8, the difference in configuration between the present embodiment and the first embodiment is that the detection pixel 2 is composed of a combination of the detection conversion element 6 and the second switch element 7, and the imaging conversion element. 4 and the first switch element 5 are not included. Further, the detection pixel 2 has the same signal line as the imaging pixel. According to this configuration, since the area of the detection conversion element 6 can be large, the radiation detection sensitivity can be improved. Further, the detection conversion element 6 is connected to the signal line 10 via the second switch element 7. In this case, since the imaging conversion element 4 is not disposed in the detection pixel 2, it becomes a defective pixel, but it can be corrected by complementing the data from the output of the adjacent imaging pixel or image data. In the present embodiment, a plurality of detection pixels are arranged in one detection region (ROI). In this case, the detection pixels 2 are desirably arranged at least regularly in the row direction, the column direction, or the oblique direction in the detection region 20. Here, the regular arrangement may include not only the case where they are arranged continuously but also the case where the imaging pixels 1 and the detection pixels 2 are arranged at a predetermined interval in the detection region 20. Therefore, the reading unit 51 calculates the incident amount of radiation in each detection region 20 based on a value obtained by adding or averaging values corresponding to signals acquired from a plurality of detection pixels arranged in the detection region 20. (get. The addition or averaging process can be performed by processing the digital signal acquired by the signal processing unit 224 from the AD converter 146. The addition or averaging process is not limited to this, and the detection unit 132 adds or averages values obtained by adding or averaging analog signals acquired from the plurality of detection pixels 2 input to the differential amplifier. The incident amount of radiation can also be calculated (acquired) by supplying it to the converter 146. And the control part 55 can also read the detection pixel 2 in a detection area | region simultaneously by controlling the drive part 52. FIG. In this case, the influence of the potential fluctuation described above can be greater. Therefore, the effect by the operation shown in each embodiment can be further increased.

(Fourth embodiment)
Next, the radiation imaging apparatus according to this embodiment will be described with reference to FIG. The difference in operation between the present embodiment and the first embodiment is that the signal line sample hold and wiring reset are performed when the drive voltage to the detection pixel is in the ON state. In addition, the control unit controls the driving unit so that the timing at which Von is sequentially applied to the detection pixels and the timing at which the detection pixels different from the detection pixels that are turned on are applied with the off voltage are the same. The detailed operation will be described below with reference to FIG. Note that any of the configurations described above can be applied to the configuration of the radiation imaging apparatus.

  The operation during the period T1 and T3 in FIG. 9 is the same as in the first embodiment. The period T2 in FIG. 9 is a period during which radiation is exposed. During this period, Voff is applied to Vg1 to Vg9 as in the first embodiment, and the first switch element 5 is in a non-conductive state. Then, the control unit 55 controls the drive unit 52 so as to sequentially apply Von to Vd1 to Vd3. In this case, in order to suppress the potential fluctuation of the signal line 10 due to the parasitic capacitance, the Von voltage is applied to Vd2 at almost the same timing as the timing of applying the Voff voltage to Vd1. Similarly, Von is applied to Vd3 at substantially the same timing as applying Voff to Vd2, and Von is applied to Vd1 at substantially the same timing as applying Voff to Vd3. By repeating this operation for each control line, it is possible to suppress the potential fluctuation of the signal line due to the parasitic capacitance when Von and Voff are applied to the second switch element. Further, as compared with the first embodiment, the Voff control voltage can be configured by one type, so that the configuration and control of the drive unit 52 can be simplified.

  Next, the timing for sampling and holding the detection signal will be described. The control unit 55 controls the reading unit 51 so that the signal appearing on the signal line connected to the detection pixel 2 to which the on-voltage is applied is read out while the driving unit 52 is applying the on-voltage. Focusing on S2 (D1) of the signal line 10, as shown in FIG. 9, sample hold (SH in FIG. 9) and wiring reset are performed while Von is applied to Vd1 (during application). To do. The same applies to the other signal lines S5 (D2) and S8 (D3) of the signal lines 10. By this control, it is possible to increase the radiation detection speed while suppressing the potential fluctuation appearing on the signal line.

  In the configuration of the present embodiment described above, radiation irradiation can be read with high accuracy, which can contribute to the realization of more appropriate dose control and exposure control.

(Application embodiment)
Next, an example in which the radiation imaging apparatus 200 is applied to a radiation detection system will be described with reference to FIG.

  X-rays 6060 generated by an X-ray tube 6050 serving as a radiation source pass through the chest 6062 of the patient or subject 6061 and enter the radiation imaging apparatus 200. This incident X-ray includes information inside the body of the patient 6061. Corresponding to the incidence of X-rays, the conversion unit 3 converts the radiation into electric charges to obtain electrical information. This information is converted into digital data, image-processed by an image processor 6070 as a signal processing means, and can be observed on a display 6080 as a display means in a control room.

  Further, this information can be transferred to a remote place by transmission processing means such as a telephone line 6090, and can be displayed on a display 6081 serving as a display means such as a doctor room in another place or stored in a recording means such as an optical disk. It is also possible for a doctor to make a diagnosis. Moreover, it can also record on the film 6110 used as a recording medium by the film processor 6100 used as a recording means.

  The embodiment of the present invention can also be realized by a computer or a control computer executing a program (computer program). Further, means for supplying a program to a computer, for example, a computer-readable recording medium such as a CD-ROM recording such a program, or a transmission medium such as the Internet for transmitting such a program is also applied as an embodiment of the present invention. be able to. The above program can also be applied as an embodiment of the present invention. The above program, recording medium, transmission medium, and program product are included in the scope of the present invention.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are within the scope of the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

DESCRIPTION OF SYMBOLS 1 Imaging pixel 2 Detection pixel 6 Detection conversion element 7 Detection switch element 12 Detection signal line 52 Drive part 55 Control part 200 Radiation imaging device

Claims (12)

A plurality of imaging pixels for acquiring a radiation image, and a plurality of detection pixels each having a detection conversion element for detecting incidence of radiation and a detection switch element connected to the detection conversion element. A radiation imaging device comprising:
A signal line commonly connected to two or more detection switch elements of the plurality of detection pixels;
A drive unit for driving a detection switch element commonly connected to the signal line;
When a first change from an off voltage to an on voltage is performed on a voltage applied to at least one detection switch element among two or more detection switch elements commonly connected to the signal line, The on-voltage and the first voltage different from the on-voltage so that the voltage applied to the detection switch element different from the at least one detection switch element has a polarity opposite to the first change. The second voltage is applied to the different detection switch element while the on-voltage is applied to the at least one detection switch element. When the second change from the on-voltage to the off-voltage is performed on the voltage applied to the at least one detection switch element, the different detection switch element And the second change to the voltage applied so as to perform the change to the first voltage from the second voltage to be a change in the opposite polarity, and a control unit for controlling the drive unit,
A radiation imaging apparatus comprising:   The control unit overlaps a timing at which the first change is performed and a timing at which the change from the first voltage to the second voltage is performed, and the timing at which the second change is performed and the second voltage from the second voltage. The radiation imaging apparatus according to claim 1, wherein the drive unit is controlled so that timings at which a change to one voltage is performed overlap. The control unit is configured such that the timing for performing the first change and the timing for performing the change from the first voltage to the second voltage are simultaneous, and the timing for performing the second change and the second 3. The radiation imaging apparatus according to claim 1, wherein the drive unit is controlled so that a timing at which a change from a voltage to the first voltage is performed simultaneously.   The drive unit includes an ON voltage that turns on the detection switch element, a first OFF voltage that is the first voltage that makes the detection switch element non-conductive, and the first OFF voltage that is higher than the first OFF voltage. The radiation imaging apparatus according to claim 1, wherein a second off voltage that is the second voltage having a large difference from an on voltage is applied. A control line connecting the drive unit and the detection switch element;
5. The radiation imaging apparatus according to claim 1, wherein the magnitude of the off-voltage is defined based on a capacitance between the control line and the signal line.   The radiation imaging apparatus according to claim 1, wherein the plurality of different detection switch elements are provided. A reading unit that reads a signal appearing on a signal line connected to the detection pixel;
The control unit controls the reading unit to read a signal appearing on a signal line connected to a detection pixel to which the on-voltage is applied during the application of the on-voltage. 7. The radiation imaging apparatus according to any one of items 1 to 6.   The radiation imaging apparatus according to claim 7, wherein the reading unit includes a sample hold circuit, and performs sample hold based on control from the control unit.   The radiation imaging apparatus according to claim 1, wherein an amount of radiation incident is measured based on the amount of radiation detected by the detection conversion element.   The radiation imaging apparatus according to claim 1, wherein the detection pixel further includes an imaging conversion element and an imaging switch element connected to the imaging conversion element. A plurality of detection pixels each having a plurality of imaging pixels for acquiring a radiation image, a detection conversion element for detecting incidence of radiation, and a detection switch element connected to the detection conversion element; and the plurality of detections A radiation imaging apparatus comprising: a signal line commonly connected to two or more detection switch elements in a pixel; and a drive unit that applies a voltage for controlling the detection switch element commonly connected to the signal line. A control method,
When a first change from an off voltage to an on voltage is performed on a voltage applied to at least one detection switch element among two or more detection switch elements commonly connected to the signal line, The on-voltage and the first voltage different from the on-voltage so that the voltage applied to the detection switch element different from the at least one detection switch element has a polarity opposite to the first change. The second voltage is applied to the different detection switch element while the on-voltage is applied to the at least one detection switch element. When the second change from the on-voltage to the off-voltage is performed on the voltage applied to the at least one detection switch element, the different detection switch element A method for controlling a radiation imaging apparatus, comprising a step of controlling the drive unit so as to cause a change from the second voltage to the first voltage, which has a polarity opposite to the second change, with respect to an applied voltage. . A radiation source that generates radiation; and
A radiation imaging apparatus according to any one of claims 1 to 10,
A radiation imaging system.

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