JP2014163863A - X-ray image detector and its breakage detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate detection of a breakage of an X-ray image detection panel of an X-ray image detector.SOLUTION: An X-ray image detector 10 includes: an X-ray detection panel 41 in which pixels are arranged in a lattice form in a pixel region on a glass substrate; a signal reading device composed of an integral amplifier 43, an A/D converter 44, an image reconstruction circuit 46 and the like; and a breakage detection part 61. The breakage detection part 61 calculates a dispersion value in a subregion which is smaller than a pixel region among electric signals read by the signal reading device while X-rays are not emitted yet, and determines occurrence of an abnormality when the dispersion value is a prescribed value or less. The standard deviation may be used instead of the dispersion value. Alternatively, the average value of differences in electric signals in multiple states in which values of supply voltage to conversion elements in the pixels are different or exposure times are different may be used.

Description

  Embodiments generally relate to an X-ray image detection apparatus and damage detection method thereof.

  Many of the X-ray image detectors currently in practical use adopt the indirect conversion method. In a conventional indirect X-ray image detector, an X-ray image transmitted through a human body or the like is incident on the X-ray image detector, and the image information is converted into an electrical signal. At this time, X-rays are converted into visible light by a fluorescent conversion film that converts X-rays into visible light, and the light is detected as two-dimensional image information by a plurality of photodetectors formed in a lattice pattern. Output as an electrical signal.

  The indirect X-ray detector uses a TFT panel in which signal wiring and TFT (Thin Film Transistor) are formed on a holding substrate by a TFT panel manufacturing process similar to the manufacturing process of a liquid crystal display device. On top of this, photodiode elements for detecting fluorescence from the input surface are formed in a grid pattern. A pixel is formed by electrically connecting the output of the photodiode element to a TFT disposed below.

  The photodiode element is mainly composed of an amorphous semiconductor. Generally, it has a diode structure in which n-type amorphous silicon, intrinsic amorphous silicon, and p-type amorphous silicon are sequentially stacked. In the operating state of the X-ray image detector, an electric field in a reverse bias state is applied to the photodiode element.

  The pixels are arranged in a grid pattern on the holding substrate, and the switching elements of each pixel are connected to a selection line representing a row and a signal line representing a column. The selection line and the signal line are arranged in a grid pattern, and are connected to each pixel arranged in the grid pattern, thereby forming a planar photodetector (image detection unit).

  In an X-ray image detection panel in which a phosphor that converts X-rays into visible light is stacked on a planar photodetector, X-rays incident from the outside are converted into visible light inside the phosphor. Visible light generated inside the phosphor enters a photodiode inside the image detection unit. Visible light incident on the photodiode is converted into electric charge inside the photodiode, and accumulated in the photodiode or in a capacitor element connected in parallel.

  The X-ray image information converted into electric charge is transmitted to the outside of the substrate through a switching element (TFT) connected to the photodiode. When the potential of the selection line changes, the TFT connected to the selection line whose potential has changed becomes conductive. The electric charge accumulated in the photodiode or the capacitive element connected to the TFT in the conductive state is discharged to the outside through the TFT. The charges discharged to the outside are discharged to the outside of the holding substrate through a signal line connected to the TFT.

  Of the selection lines for driving the TFT transistors, the potential of only one selection line is usually changed, so that the TFT transistors in all the pixels corresponding to a specific row are made conductive. By sequentially changing the selection line for changing the potential, a signal from a pixel corresponding to a specific row is discharged to the outside. By referring to the position of the signal line from which the charge has been discharged and the position of the selection line whose potential has fluctuated at that time, it is possible to calculate the X-ray incident position and intensity.

  The charge signal discharged to the outside of the holding substrate is input to the integrating amplifier connected to each signal line. The charge information input to the integrating amplifier is amplified, converted into a potential signal, and output. The potential signal output from the integrating amplifier is converted to a digital value by an analog / digital converter on the circuit board installed inside the X-ray image detector, and after necessary image processing is added, the image signal is finally obtained. And output to the outside of the X-ray image detector.

  The image information stored inside the X-ray image detector is output to the outside through a LAN line or the like. The image information output to the outside is imaged by a program stored inside an information processing apparatus such as a connected personal computer, and is converted into an image whose brightness and contrast are corrected by the program as necessary. Displayed above.

JP 2005-177379 A

  Since the TFT panel used in the X-ray image detector uses a thin holding substrate, it is difficult to completely prevent the TFT panel from being damaged when a large impact is applied from the outside of the X-ray image detector. . When the TFT panel is broken, it becomes impossible to detect an X-ray image in a partial area or the entire area of the X-ray image detector. If X-ray imaging is performed in a state where the TFT panel is broken, a part or all of the image is lost. For this reason, unnecessary X-ray exposure occurs for a patient who is an imaging target.

  In addition to the case where a large impact is applied to the X-ray image detector, the TFT panel can be damaged by changes in the stress on the TFT panel due to temperature changes, and small scratches inside the substrate can naturally grow into damage. Conceivable. For this reason, it is difficult to predict when the TFT panel will break. From this, it is required to check the presence or absence of the TFT substrate as frequently as possible.

  In order to detect the breakage of the TFT panel, a method of irradiating the detector with X-rays without using the subject and viewing the output image can be considered. In this method, when a TFT panel breakage occurs, an abnormal value is output in a partial area or all areas of the output image, so that it is easy to detect the breakage of the TFT panel.

  However, this method requires a photographing operation dedicated to damage detection that is performed without using a subject. If the imaging operation for confirming the TFT panel breakage is performed at a high frequency, the diagnosis work for the patient using the X-ray, which is the original work, is hindered.

  Therefore, an object of the embodiment is to facilitate the detection of breakage of the X-ray image detection panel of the X-ray image detection apparatus and suppress unnecessary exposure to the patient.

  To achieve the above object, an X-ray image detection apparatus according to an embodiment includes a substrate, a plurality of row selection lines extending on the substrate, and a plurality of signals extending on the substrate so as to intersect the row selection lines. A substrate, a conversion element that converts X-rays or fluorescence converted from X-rays into an electric signal, and a switching element that is connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid pattern in the upper pixel region, a signal reader connected to the signal line and reading an electric signal from the pixel, and an electric signal read out by the signal reader when X-rays are not irradiated A damage detection unit that calculates a dispersion value in a small area smaller than the pixel area and determines that an abnormality has occurred when the dispersion value is equal to or less than a predetermined value.

  The X-ray image detection apparatus according to the embodiment includes a substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and an X-ray or In a pixel region on the substrate, a conversion element that converts fluorescence converted from X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid, a signal reader connected to the signal line and reading an electric signal from the pixel, and an electric signal read by the signal reader when the X-ray is not irradiated from the pixel region And a damage detection unit that calculates a standard deviation in a small small area and determines that an abnormality has occurred when the standard deviation is outside a predetermined range.

  The X-ray image detection apparatus according to the embodiment includes a substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and an X-ray or In a pixel region on the substrate, a conversion element that converts fluorescence converted from X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid, a signal reader connected to the signal line and reading an electrical signal from the pixel, and the signal in a plurality of states in which the power supply voltage to the conversion element is different when X-rays are not irradiated Damage detection that calculates a difference between electrical signals read by a reader, calculates an average value of the differences in a small area smaller than the pixel area, and determines that an abnormality has occurred when the difference is outside a predetermined range And The features.

  The X-ray image detection apparatus according to the embodiment includes a substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and an X-ray or In a pixel region on the substrate, a conversion element that converts fluorescence converted from X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid, a signal reader connected to the signal line for reading an electrical signal from the pixel, and the signal reader read in a plurality of states with different exposure times when X-rays are not irradiated A damage detection unit that calculates a difference between electrical signals, calculates an average value of the differences in a small area smaller than the pixel area, and determines that an abnormality has occurred when the difference is outside a predetermined range; It is characterized by doing.

  In addition, the substrate according to the embodiment, the plurality of row selection lines extending on the substrate, the plurality of signal lines extending on the substrate so as to intersect the row selection line, and the X-ray or X-ray converted fluorescence A plurality of conversion elements that are converted into electric signals and switching elements that are connected to the row selection lines and are provided between the conversion elements and the signal lines and arranged in a grid in the pixel region on the substrate And a signal reader connected to the signal line and reading an electrical signal from the pixel. The method for detecting damage in an X-ray image detection apparatus comprises: A step of reading out an electric signal by the device, a step of calculating a dispersion value in a small region smaller than the pixel region of the electric signal, and determining that an abnormality has occurred when the dispersion value is equal to or less than a predetermined value. A process. And wherein the door.

  In addition, the substrate according to the embodiment, the plurality of row selection lines extending on the substrate, the plurality of signal lines extending on the substrate so as to intersect the row selection line, and the X-ray or X-ray converted fluorescence A plurality of conversion elements that are converted into electric signals and switching elements that are connected to the row selection lines and are provided between the conversion elements and the signal lines and arranged in a grid in the pixel region on the substrate And a signal reader connected to the signal line and reading an electrical signal from the pixel. The method for detecting damage in an X-ray image detection apparatus comprises: A step of reading out an electrical signal by the device, a step of calculating a standard deviation in a small region smaller than the pixel region of the electrical signal, and determining that an abnormality has occurred when the standard deviation is outside a predetermined range And comprising a process And wherein the Rukoto.

  In addition, the substrate according to the embodiment, the plurality of row selection lines extending on the substrate, the plurality of signal lines extending on the substrate so as to intersect the row selection line, and the X-ray or X-ray converted fluorescence A plurality of conversion elements that are converted into electric signals and switching elements that are connected to the row selection lines and are provided between the conversion elements and the signal lines and arranged in a grid in the pixel region on the substrate And a signal reader connected to the signal line and reading an electrical signal from the pixel. The method for detecting damage in an X-ray image detection apparatus comprises: A first reading step in which the reading device reads an electric signal, and a second reading step in which the signal reading device reads an electric signal in a state where a power supply voltage to the conversion element is different from the first reading step when X-rays are not irradiated; Read in the first reading step Calculating a difference between the electrical signal read out and the electrical signal read out in the second reading step, calculating an average value of the difference in a small region smaller than the pixel region, and the average value being a predetermined value And a step of determining that an abnormality has occurred when it is out of range.

  In addition, the substrate according to the embodiment, the plurality of row selection lines extending on the substrate, the plurality of signal lines extending on the substrate so as to intersect the row selection line, and the X-ray or X-ray converted fluorescence A plurality of conversion elements that are converted into electric signals and switching elements that are connected to the row selection lines and are provided between the conversion elements and the signal lines and arranged in a grid in the pixel region on the substrate And a signal reader connected to the signal line and reading an electrical signal from the pixel. The method for detecting damage in an X-ray image detection apparatus comprises: A first reading step in which the reading device reads an electric signal, a second reading step in which the signal reading device reads an electric signal in a state in which an exposure time is different from that of the first reading step when X-rays are not irradiated, and the first reading step And the electrical signal read in A step of calculating a difference from the electrical signal read in the second reading step, a step of calculating an average value of the difference in a small region smaller than the pixel region, and the average value is outside a predetermined range. And a step of determining that an abnormality has occurred.

It is a block diagram of the X-ray image detection apparatus by one Embodiment. It is a typical perspective view of the X-ray detection panel in one Embodiment. It is an equivalent circuit diagram of the pixel of the X-ray detection panel in one embodiment. It is an equivalent circuit schematic of the image detection part in one Embodiment.

  Hereinafter, an X-ray image detection apparatus according to an embodiment will be described with reference to the drawings.

  FIG. 1 is a block diagram of an X-ray image detection apparatus according to an embodiment.

  The X-ray image detection apparatus 10 has an X-ray detection panel 41 that converts incident X-rays into electrical signals. A number of integrating amplifiers 43 and gate drivers 42 are connected to the X-ray detection panel 41. A row selection circuit 45 is connected to the gate driver 42. An A / D converter 44 is connected to the integrating amplifier 43. There are a plurality of A / D converters 44, for example, and each A / D converter 44 is connected to a plurality of integrating amplifiers 43.

  An image reconstruction circuit 46 is connected to the A / D converter 44. A damage detector 61 is connected to the image reconstruction circuit 46.

  An offset correction processing unit 47 is connected to the breakage detection unit 61. A gain correction processing unit 49 is connected to the offset correction processing unit 47. A defect correction processing unit 51 is connected to the gain correction processing unit 49. The offset correction processing unit 47 can refer to the offset correction table 48. The gain correction processing unit 49 can refer to the gain correction table 50. The defect correction processing unit 51 can refer to the defect correction table 52. An image display device 54 is connected to the defect correction processing unit 51.

  The gate driver 42 has a function of sequentially changing the voltages of a large number of signal lines connected to the X-ray detection panel 41 when receiving an external signal. The integrating amplifier 43 has a function of amplifying and outputting a very small charge signal output from the X-ray detection panel 41. The row selection circuit 45 has a function of sending a signal to the corresponding gate driver 42 in accordance with the scanning direction of the X-ray image. The analog electric signal amplified by the integrating amplifier 43 is converted into a digital signal by the A / D converter 44. The digital signal converted by the A / D converter 44 is reconstructed as an image signal by the row and column of pixels by the image reconstruction circuit 46.

  The image signal reconstructed by the image reconstruction circuit 46 is subjected to image processing by an offset correction processing unit 47 to remove the dark current component of the pixels inside the X-ray detection panel 41 and the offset component of the integrating amplifier 43. Is done. The gain correction processing unit 49 performs image processing for removing each pixel sensitivity difference and the amplification factor difference of the integrating amplifier 43. The defect correction processing unit 51 performs defect correction processing for removing pixel data of defective pixels. After these image processes are performed, an X-ray image is displayed on the image display device 14.

  The offset correction processing unit 47, the gain correction processing unit 49, and the defect correction processing unit 51 are provided with an offset correction table 58, a gain correction table 50, and a defect correction table 52 for storing parameters used for calculation. Yes. The offset correction processing unit 47, the gain correction processing unit 49, and the defect correction processing unit 51 perform each correction process according to the contents of each table. These correction processes may be performed by components / elements inside the housing that houses the X-ray detection panel 41, or by an information processing apparatus such as a personal computer that is connected by a LAN line and stores an appropriate program. You may go.

  FIG. 2 is a schematic perspective view of the X-ray detection panel in the present embodiment.

  The X-ray detection panel 41 includes the fluorescence conversion film 16 and the image detection unit 20. Incident X-rays 15 incident on the fluorescence conversion film 16 are converted into fluorescence composed of visible light inside the fluorescence conversion film 16. The fluorescence generated in the fluorescence conversion film 16 reaches the surface of the image detection unit 20.

  The image detection unit 20 has a holding substrate 19 mainly composed of a glass substrate. A TFT circuit layer 18 and a plurality of pixels 17 arranged in a lattice pattern are formed on the surface of the holding substrate 19. An area where the pixels 17 are arranged is referred to as a pixel area. The image detection unit 20 has a function of converting a visible light image incident from the outside into an electrical signal by a pixel.

  FIG. 3 is an equivalent circuit diagram of a pixel of the X-ray detection panel in the present embodiment.

  Each pixel 17 includes a thin film transistor 22, a photodiode 23, and a capacitor 24. Each thin film transistor 22 has a switching function for accumulating and discharging charges generated by the incidence of fluorescence on the photodiode 23. The thin film transistor 22 is at least partially composed of a semiconductor material such as amorphous silicon (a-Si) as an amorphous semiconductor, which is a crystalline semiconductor material, or polysilicon (P-Si), which is a polycrystalline semiconductor. Has been.

  A row selection line 21 is connected to the thin film transistor 22. The switching operation of the thin film transistor 22 is controlled by a control signal flowing through the row selection line 21. A bias line 26 is connected to the photodiode 23. A bias voltage necessary for the operation of the photodiode 23 is supplied by the bias line 26. A signal line 25 is connected to the capacitor 24 via the thin film transistor 22.

  When visible light enters the photodiode 23, charges are generated inside the photodiode 23. The electric charge generated inside the photodiode 23 is accumulated in the capacitor 24. The charge accumulated in the capacitor 24 flows to the signal line 25 through the thin film transistor 22 when a predetermined signal is given to the gate of the thin film transistor 22.

  FIG. 4 is an equivalent circuit diagram of the image detection unit in the present embodiment.

  In the image detection unit 20, pixels 17 are arranged in a grid pattern. Each pixel 17 is connected to a row selection line 21, a signal line 25, and a bias line 26.

  Next, the operation of the X-ray image detection apparatus 10 will be described with reference to FIGS. In the initial state, electric charge is stored in the capacitor 24 through the bias line 26, and a reverse bias voltage is applied to the photodiode 23 connected in parallel. At this time, the voltage of the line connecting the photodiode 23 and the thin film transistor 22 is the same as the voltage applied to the signal line 25.

  Since the photodiode 23 is a kind of diode, almost no current flows even when a reverse bias voltage is applied. Therefore, the electric charge stored in the capacitor 24 is held without decreasing.

  Under such circumstances, when incident X-rays 15 pass through an object to be inspected such as a human body and enter the fluorescence conversion film 16, high-energy X-rays are converted into fluorescence composed of visible light inside the fluorescence conversion film 16. Is done. The intensity of this fluorescence is proportional to the incident X-ray intensity. A part of the fluorescence generated inside the fluorescence conversion film 16 reaches the pixels 17 arranged on the surface of the image detection unit 20.

  The fluorescence that has entered the pixel 17 is converted into a charge composed of electrons and holes inside the photodiode 23. These charges are observed as a current flowing in the photodiode 23 by reaching both terminals of the photodiode 23 along the direction of the electric field applied by the capacitor 24.

  The current flowing through the photodiode 23 generated by the incidence of the fluorescence flows into the capacitor 24 connected in parallel, and acts to cancel the charge stored in the capacitor 24. As a result, the charge stored in the capacitor 24 decreases, and the potential difference generated between the terminals of the capacitor 24 also decreases compared to the initial state.

  The row selection line 21 is connected to a specific terminal of the gate driver 42. The gate driver 42 has a function of receiving signals from the row selection circuit 45 and changing the potentials of a number of terminals in order. At a specific time, there is only one row selection line 21 whose potential is changed by the gate driver 42. Between the source and drain terminals of the thin film transistor 22 connected in parallel to the row selection line 21 whose potential has changed, the state changes from an insulated state to a conductive state.

  A specific voltage is applied to each signal line 25. This voltage is applied to the capacitor 24 connected through the source and drain terminals of the thin film transistor 22 connected to the row selection line 21 whose potential has been converted.

  Since the capacitor 24 is in the same potential state as the signal line 25 in the initial state, if the charge amount of the capacitor 24 is not changed from the initial state, no charge transfer from the signal line 25 occurs in the capacitor 24. . However, in the capacitor 24 connected in parallel with the photodiode 23 of the pixel 17 irradiated with the fluorescence generated inside the fluorescence conversion film 16 from the incident X-ray 15 from the outside, the photocurrent generated in the photodiode 23 causes The electric charge stored inside has decreased, and the potential has changed from the initial state. For this reason, the charge is transferred to the signal line 25 through the thin film transistor 22 in the conductive state, and the amount of charge stored in the capacitor 24 returns to the initial state. The amount of charge that has moved becomes a signal that flows through the signal line 25 and is transmitted to the outside.

  The signal line 25 is connected to the integrating amplifier 43. The signal lines 25 are connected to the integration amplifiers 43 corresponding to the signal lines 25 on a one-to-one basis. The current flowing through the signal line 25 is input to the corresponding integrating amplifier 43. The integrating amplifier 43 has a function of integrating a current flowing within a predetermined time and outputting a voltage corresponding to the integrated value to the outside. By performing this operation, the amount of charge flowing through the signal line within a certain time can be converted into a voltage value. As a result, the charge signal generated inside the photodiode 23 corresponding to the intensity distribution of the fluorescence generated inside the fluorescence conversion film 16 by the incident X-ray 15 is converted into potential information by the integrating amplifier 43.

  The potential generated by the integrating amplifier 43 is sequentially converted into a digital signal by the A / D converter 44. The signal that has become a digital value is converted into an image signal that is sequentially arranged in accordance with the row and column of pixels arranged inside the image detection unit 20 inside the image reconstruction circuit 46. During normal imaging, an image signal read by a signal reader including the integration amplifier 43, the A / D converter 44, the image reconstruction circuit 46, and the like is not subjected to special processing in the damage detection unit 61 and is directly processed. This is transmitted to the offset correction processing unit 47.

  In the image signal output from the image reconstruction circuit 46, there is an image noise including an offset component that differs depending on each pixel 17 arranged inside the X-ray detection panel 41 and an individual offset component that the integration amplifier 43 has. include. By passing the offset correction processing unit 47, these noise components included in the image signal output from the image reconstruction circuit 46 can be removed.

  The image signal output from the image reconstruction circuit 46 includes variations in the light detection efficiency, the amplification factor of the integration amplifier 43, and the conversion efficiency of the fluorescence conversion film 16 that differ depending on the individual pixels 17. By passing the gain correction processing unit 49, it is possible to remove these sensitivity variations.

  The image signal output from the gain correction processing unit 49 is input to the defect correction processing unit 51. The defect correction processing unit 51 removes the signal from the defective pixel included in the image based on the defective pixel information recorded in the defect correction table 52, and based on the signal from the surrounding normal pixels. It has a function of repairing and outputting image information from defective pixels.

  The image detection unit 20 of the X-ray detection panel 41 uses a glass holding substrate 19. For this reason, there is a possibility that the glass breaks due to an external impact or a change in internal stress.

  When glass breakage occurs in the image detection unit 20, the row selection line 21 and the signal line 25 formed on the surface of the image detection unit 20 may be disconnected. When the disconnection of the row selection line 21 occurs, the thin film transistor 22 of the pixel 17 located farther from the gate driver 42 than the disconnection portion cannot be driven, and output from the corresponding pixel 17 cannot be performed. When the disconnection of the signal line 25 occurs, the signal from the pixel 17 located far from the integration amplifier 43 from the disconnection point is interrupted, and the output from the corresponding pixel 17 is lost.

  In order to detect such breakage of the image detection unit 20, the X-ray image detection apparatus 10 needs to periodically inspect the state and confirm the presence or absence of breakage. The damage detection unit 61 performs this damage inspection. This is because an X-ray image cannot be output due to breakage, and unnecessary exposure of X-rays due to imaging failure is prevented.

  In order to detect breakage, the breakage detection unit 61 uses a dark image that is output without performing various correction operations by causing the X-ray detection panel 41 to perform an imaging operation in a state where X-rays are not incident. Since these operations do not need to use X-rays, they can be performed frequently between X-ray imaging using a subject.

  The damage detection unit 61 divides the pixel area in which the pixels 17 are arranged into a plurality of small areas in order to detect the presence or absence of damage, and calculates the variation in the pixel output value for the above-described dark image for each small area. . Under normal conditions, variations in image output include “variations in dark image output values due to individual differences for each pixel”, “gate noise” entered from the outside through row selection lines, “integration amplifier noise”, and “ "Offset variation due to individual differences of integrating amplifiers" is included.

  When breakage occurs in the X-ray detection panel 41 and a part of the row selection line 21 is disconnected, the thin film transistor 22 of the pixel 17 cannot be driven due to the disconnection, and from the outside through the row selection line 21 There is no noise intrusion. For this reason, the variation of the dark image in the corresponding region includes only “integration amplifier noise” and “offset variation due to individual differences of integration amplifiers”.

  Even when the signal line 25 is broken, the signal from the corresponding region is interrupted. Therefore, the dark image variation includes only “integration amplifier noise” and “offset variation due to individual difference of the integration amplifier”. Will be.

  For these reasons, when the image detection unit is damaged, the variation of the dark image in the corresponding region is lower than that in the normal state. Therefore, the dark image obtained during the X-ray imaging is divided into small regions, and variations such as dispersion values and standard deviations within the region are calculated. In the case where those values are lower than the normal state and any region having a value corresponding only to the variation caused by the integration amplifier occurs, the breakage detection unit 61 has broken the X-ray detection panel 41. Judgment is made and the alarm is communicated to the outside. When this alarm occurs, the operation of the X-ray generator is stopped, and unnecessary exposure to the patient can be prevented.

  The damage detection operation may be performed by a circuit housed in the same housing as the X-ray detection panel 41, or a personal computer that is connected to the outside of the housing and stores a program for controlling the X-ray image detection panel and performing image processing. It is also possible to do this. In this case, it is not necessary to provide a circuit for detecting breakage inside the casing containing the X-ray detection panel 41, and the cost can be reduced.

  It is also effective to use a rectangular region shape with a width of only one pixel 17 as a divided small region used in breakage detection. When the X-ray detection panel 41 is damaged, the row selection line 21 or the signal line 25 is disconnected, but the affected pixel 17 is the row of the pixel 17 belonging to the disconnected row selection line 21 or the signal line 25. Or the column is the target. In order to detect minute breakage, it is necessary to reduce the area and increase the number of points to be detected. However, it is possible to detect breakage of the minute area by reducing the width to one pixel.

  It is also effective to limit the area where damage is detected to only the area around the X-ray detection panel 41. This is because most of the breakage of the glass substrate constituting the X-ray detection panel 41 occurs from the outer peripheral portion, so that only the region belonging to the outer peripheral portion is the detection target, so that the damage detection accuracy can be saved even if the time required for detection is saved. There is an advantage that there is little to drop.

  Next, a first modification of the present embodiment will be described.

  In this modification, a plurality of dark images having different power supply voltages to the photodiodes 23 of the X-ray detection panel 41 are used. In the damage inspection of the X-ray detection panel 41 in this modification, first, two dark images with different power supply voltages to the photodiode 23 are taken between X-ray imaging operations, and a difference image of these image data is obtained. Ask.

  The photodiode 23 has a diode structure, and a dark current corresponding to the bias voltage flows in the reverse bias state. For this reason, the image data of these dark images includes information on the dark current difference of the photodiode 23 in a state where the bias voltages are different.

  When breakage occurs in the X-ray detection panel 41 and a part of the row selection line 21 is disconnected, the thin film transistor 22 of the pixel 17 cannot be driven by the disconnection. For this reason, the output from the pixel 17 in the region affected by the disconnection is interrupted, and the dark current component of the photodiode 23 is not output. As a result, the output value corresponding to the damaged area of the difference image has no dark current difference and shows a value different from the normal state. When even one region showing a value different from the normal state occurs, it is determined that the X-ray detection panel 41 has been damaged, and an alarm can be notified to the outside. When this alarm is generated, the operation of the X-ray generator is stopped, and unnecessary exposure to the patient can be prevented.

  Even when a disconnection occurs in a part of the signal line, the output from the thin film transistor 22 of the pixel 17 is interrupted, so that the dark current component of the photodiode 23 is not output. As a result, the output value corresponding to the damaged region of the difference image has no dark current difference and shows a value different from the normal state. When even one region showing a value different from the normal state occurs, it is determined that the X-ray detection panel 41 has been damaged, and an alarm can be notified to the outside. When this alarm occurs, the operation of the X-ray generator is stopped, and unnecessary exposure to the patient can be prevented.

  Next, a second modification of the present embodiment will be described.

  In this modification, a plurality of dark images having different exposure times for the X-ray detection panel 41 are used. In the damage inspection of the X-ray detection panel 41 in this modified example, first, two dark images are taken by changing the exposure time of the X-ray detection panel 41 between the X-ray imaging operations, and the image data Find the difference image.

  The photodiode 23 has a diode structure, and a dark current corresponding to the bias voltage flows in the reverse bias state. For this reason, the image data of these dark images includes information on the dark current difference of the photodiode 23 in a state where the bias voltages are different.

  When breakage occurs in the X-ray detection panel 41 and a part of the row selection line 21 is disconnected, the thin film transistor 22 of the pixel 17 cannot be driven by the disconnection. For this reason, the output from the pixel 17 in the region affected by the disconnection is interrupted, and the dark current component of the photodiode 23 is not output. As a result, the output value corresponding to the damaged area of the difference image has no dark current difference and shows a value different from the normal state. When even one region showing a value different from the normal state occurs, it is determined that the X-ray detection panel 41 has been damaged, and an alarm can be notified to the outside. When this alarm is generated, the operation of the X-ray generator is stopped, and unnecessary exposure to the patient can be prevented.

  Even when a disconnection occurs in a part of the signal line, the output from the thin film transistor 22 of the pixel 17 is interrupted, so that the dark current component of the photodiode 23 is not output. As a result, the output value corresponding to the damaged region of the difference image has no dark current difference and shows a value different from the normal state. When even one region showing a value different from the normal state occurs, it is determined that the X-ray detection panel 41 has been damaged, and an alarm can be notified to the outside. When this alarm occurs, the operation of the X-ray generator is stopped, and unnecessary exposure to the patient can be prevented.

  As described above, according to the present embodiment or the modification thereof, it becomes easy to detect breakage of the X-ray image detection panel of the X-ray image detection apparatus, and the unnecessary exposure to the patient is suppressed.

  Although one embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, in the above-described embodiment, incident X-rays are once converted into fluorescence, and the fluorescence is converted into an electrical signal. However, an element that removes the fluorescence conversion film and directly converts X-rays into an electrical signal is used as a configuration. Also good.

DESCRIPTION OF SYMBOLS 10 ... X-ray image detection apparatus, 14 ... Image display apparatus, 15 ... Incident X-ray, 16 ... Fluorescence conversion film, 17 ... Pixel, 18 ... TFT circuit layer, 19 ... Holding substrate, 20 ... Image detection part, 21 ... Row Selection line, 22 ... thin film transistor, 23 ... photodiode, 24 ... capacitor, 25 ... signal line, 26 ... bias line, 41 ... X-ray detection panel, 42 ... gate driver, 43 ... integration amplifier, 44 ... A / D converter , 45 ... Row selection circuit, 46 ... Image reconstruction circuit, 47 ... Offset correction processing unit, 48 ... Offset correction table, 49 ... Gain correction processing unit, 50 ... Gain correction table, 51 ... Defect correction processing unit, 52 ... Defect correction table, 54 ... Image display device, 61 ... Damage detector

Claims (11)

A substrate,
A plurality of row selection lines extending on the substrate;
A plurality of signal lines extending on the substrate so as to intersect the row selection lines;
A pixel on the substrate having a conversion element for converting X-rays or fluorescence converted from the X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid pattern in the region;
A signal reader connected to the signal line to read out an electrical signal from the pixel;
Of the electrical signals read by the signal reader when X-rays are not irradiated, a dispersion value in a small area smaller than the pixel area is calculated, and it is determined that an abnormality has occurred when the dispersion value is equal to or less than a predetermined value. A breakage detector;
An X-ray image detection apparatus comprising: A substrate,
A plurality of row selection lines extending on the substrate;
A plurality of signal lines extending on the substrate so as to intersect the row selection lines;
A pixel on the substrate having a conversion element for converting X-rays or fluorescence converted from the X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid pattern in the region;
A signal reader connected to the signal line to read out an electrical signal from the pixel;
A standard deviation is calculated in a small area smaller than the pixel area among the electric signals read by the signal reader when X-rays are not irradiated, and it is determined that an abnormality has occurred when the standard deviation is outside a predetermined range. A breakage detector;
An X-ray image detection apparatus comprising: A substrate,
A plurality of row selection lines extending on the substrate;
A plurality of signal lines extending on the substrate so as to intersect the row selection lines;
A pixel on the substrate having a conversion element for converting X-rays or fluorescence converted from the X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid pattern in the region;
A signal reader connected to the signal line to read out an electrical signal from the pixel;
The difference between the electrical signals read by the signal reader is calculated in a plurality of states with different power supply voltages to the conversion element when X-rays are not irradiated, and the average value of the differences in a small region smaller than the pixel region is calculated. A damage detection unit that determines that an abnormality has occurred when the difference is outside a predetermined range;
An X-ray image detection apparatus comprising: A substrate,
A plurality of row selection lines extending on the substrate;
A plurality of signal lines extending on the substrate so as to intersect the row selection lines;
A pixel on the substrate having a conversion element for converting X-rays or fluorescence converted from the X-rays into an electric signal and a switching element connected to the row selection line and provided between the conversion element and the signal line A plurality of pixels arranged in a grid pattern in the region;
A signal reader connected to the signal line to read out an electrical signal from the pixel;
The difference between the electrical signals read by the signal reader in a plurality of states with different exposure times when X-rays are not irradiated is calculated, and an average value of the differences in a small region smaller than the pixel region is calculated. A damage detection unit that determines that an abnormality has occurred when out of range,
An X-ray image detection apparatus comprising:   The X-ray according to any one of claims 1 to 4, wherein the breakage detection unit is provided on an information processing device disposed outside a housing in which the substrate is housed. Image detection device.   6. The X-ray image detection apparatus according to claim 1, wherein a width of the small region is one pixel.   The X-ray image detection apparatus according to claim 1, wherein the breakage detection unit performs an operation only on the small region that is in contact with an outer periphery of the pixel region. . A substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and X-rays or fluorescence converted from X-rays are converted into electrical signals. A plurality of pixels arranged in a grid pattern in a pixel region on the substrate having switching elements connected between the conversion elements and the row selection lines and provided between the conversion elements and the signal lines; A damage detection method for an X-ray image detection apparatus, comprising: a signal reader connected to a signal line to read out an electrical signal from the pixel;
Reading the electrical signal by the signal reader when X-rays are not irradiated;
Calculating a variance value in a small area smaller than the pixel area of the electrical signal;
Determining that an abnormality has occurred when the variance value is less than or equal to a predetermined value;
A damage detection method for an X-ray image detection apparatus, comprising: A substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and X-rays or fluorescence converted from X-rays are converted into electrical signals. A plurality of pixels arranged in a grid pattern in a pixel region on the substrate having switching elements connected between the conversion elements and the row selection lines and provided between the conversion elements and the signal lines; A damage detection method for an X-ray image detection apparatus, comprising: a signal reader connected to a signal line to read out an electrical signal from the pixel;
Reading the electrical signal by the signal reader when X-rays are not irradiated;
Calculating a standard deviation in a small area smaller than the pixel area of the electrical signal;
Determining that an abnormality has occurred when the standard deviation is outside a predetermined range;
A damage detection method for an X-ray image detection apparatus, comprising: A substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and X-rays or fluorescence converted from X-rays are converted into electrical signals. A plurality of pixels arranged in a grid pattern in a pixel region on the substrate having switching elements connected between the conversion elements and the row selection lines and provided between the conversion elements and the signal lines; A damage detection method for an X-ray image detection apparatus, comprising: a signal reader connected to a signal line to read out an electrical signal from the pixel;
A first reading step in which the signal reader reads an electrical signal when X-rays are not irradiated;
A second reading step in which the signal reader reads an electric signal in a state where a power supply voltage to the conversion element is different from that in the first reading step when X-rays are not irradiated;
Calculating a difference between the electric signal read in the first reading step and the electric signal read in the second reading step;
Calculating an average value in a small area smaller than the pixel area of the difference;
Determining that an abnormality has occurred when the average value is outside a predetermined range;
A damage detection method for an X-ray image detection apparatus, comprising: A substrate, a plurality of row selection lines extending on the substrate, a plurality of signal lines extending on the substrate so as to intersect the row selection lines, and X-rays or fluorescence converted from X-rays are converted into electrical signals. A plurality of pixels arranged in a grid pattern in a pixel region on the substrate having switching elements connected between the conversion elements and the row selection lines and provided between the conversion elements and the signal lines; A damage detection method for an X-ray image detection apparatus, comprising: a signal reader connected to a signal line to read out an electrical signal from the pixel;
A first reading step in which the signal reader reads an electrical signal when X-rays are not irradiated;
A second reading step in which the signal reader reads an electric signal in a state where an exposure time is different from that of the first reading step when X-rays are not irradiated;
Calculating a difference between the electric signal read in the first reading step and the electric signal read in the second reading step;
Calculating an average value in a small area smaller than the pixel area of the difference;
Determining that an abnormality has occurred when the average value is outside a predetermined range;
A damage detection method for an X-ray image detection apparatus, comprising:

Images