WO2013180078A1

WO2013180078A1 - Radiographic imaging equipment, radiographic imaging system, radiographic imaging method, and radiographic imaging program

Info

Publication number: WO2013180078A1
Application number: PCT/JP2013/064674
Authority: WO
Inventors: 美広岡田; 北野　浩一; 大田　恭義; 孝明伊藤
Original assignee: 富士フイルム株式会社
Priority date: 2012-05-30
Filing date: 2013-05-27
Publication date: 2013-12-05

Abstract

The present invention provides radiographic imaging equipment, a radiographic imaging system, a radiographic imaging method, and a radiographic imaging program with which a defective pixel map for each of a plurality of resolutions can easily be obtained. This radiographic imaging equipment generates a high-resolution defective pixel map by detecting defective pixels. At this time, the types of defects are defined, and the defective pixel map is generated. In addition, a low-resolution defective pixel map is generated by converting the high-resolution defective pixel map to a pixel density at low resolution.

Description

Radiographic imaging apparatus, radiographic imaging system, radiographic imaging method, and radiographic imaging program

The present invention relates to a radiographic imaging device, a radiographic imaging system, a radiographic imaging method, and a radiographic imaging program.

In recent years, radiation detectors such as FPD (Flat Panel Detector) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation dose into digital data (electrical signals) ("Radiation Panel Unit" etc.) Have been put to practical use. Furthermore, a radiographic imaging apparatus that uses this radiation detector to capture a radiographic image represented by the irradiated radiation dose has been put into practical use.

For example, when the technique described in JP2009-159497A determines that there is a defect in the non-binning mode, the area including the defective pixel is stored as a non-binning area. Next, in this technique, when binning is performed, the non-binning area is binned by digital addition or the like after reading out the charge without binning.

In addition, the technique described in Japanese Patent Laid-Open No. 2003-190126 includes a photographing mode in which charges are read from all elements to obtain a high-resolution photographed image, and a perspective image in which a plurality of element data is added to obtain a low-resolution perspective image. Mode. This technique generates offset information corresponding to the fluoroscopic mode based on the offset information obtained in the photographing mode.

However, the techniques described in Japanese Patent Application Laid-Open Nos. 2009-159497 and 2003-190126 do not mention generation of defective pixel maps at a plurality of resolutions. Therefore, there is room for improvement in order to easily obtain a defective pixel map at each resolution.

The present invention provides a radiographic imaging apparatus, a radiographic imaging system, a radiographic imaging method, and a radiographic imaging program capable of easily obtaining respective defective pixel maps at a plurality of resolutions.

According to a first aspect of the present invention, there is provided a radiographic imaging control device including a sensor unit that generates a charge corresponding to irradiated radiation, and a switching element that reads the charge generated by the sensor unit and outputs the charge. A radiation detector provided with a plurality of pixels including, a generation means for detecting a defect of a pixel used in predetermined high-resolution imaging in the radiation detector and generating a high-resolution defect pixel map, and generated by the generation means Conversion means for converting the high-resolution defective pixel map thus obtained into a low-resolution defective pixel map having a resolution lower than the high resolution.

According to the radiographic imaging control apparatus in the first aspect of the present invention, the high resolution defect pixel map is generated by the generation unit, and the conversion unit converts the high resolution defect pixel map generated by the generation unit to the low resolution defect pixel map. Convert. Therefore, according to the first aspect of the present invention, defective pixel maps of high resolution and low resolution can be generated by detecting defective pixels once. Therefore, the first aspect of the present invention can easily obtain each defective pixel map at a plurality of resolutions.

According to a second aspect of the present invention, in the first aspect, the radiation detector includes a sensor unit that generates a charge corresponding to the irradiated radiation, and a first unit that reads the charge from the sensor unit and outputs the charge. A switching element and a second switching element that reads out charges from the sensor unit and outputs charges are provided as switching elements, and each of a plurality of pixels arranged two-dimensionally and a plurality of pixels adjacent in the first direction. A plurality of first control wirings connected to a control end of one switching element; a plurality of second control wirings connected to control ends of second switching elements of a plurality of pixels adjacent in the first direction; A signal wiring is provided for each arrangement along a second direction different from the one direction, and the output terminals of the first switching elements of a plurality of pixels adjacent to the second direction are connected to each signal wiring, and the first A signal wiring group in which the output ends of the second switching elements of the plurality of pixels adjacent in the direction and the output ends of the second switching elements of the plurality of pixels adjacent in the first direction are connected to a part of the signal wiring; May be provided.

In the third aspect of the present invention, in the above aspect, the high resolution defective pixel map and the low resolution defective pixel map may be defined according to the type of defective pixel. In a fourth aspect of the present invention, in the above aspect, the high resolution defective pixel map and the low resolution defective pixel map may be defined according to the cause of the defective pixel.

Further, according to a fifth aspect of the present invention, in the above aspect, the radiographic imaging device of the present invention further includes a correcting unit that corrects the defective pixel based on the high-resolution defective pixel map or the low-resolution defective pixel map. It may be. According to a sixth aspect of the present invention, in the fifth aspect, the correction unit is configured to detect a high-resolution pixel included in the low-resolution pixel that is a defective pixel in the low-resolution defective pixel map when photographing at a low resolution. The defective pixels may be corrected by adjusting the gain according to the number of defective pixels.

Further, according to a seventh aspect of the present invention, in the above aspect, the switching element may be configured in the same direction and size in each pixel. Thus, according to the seventh aspect of the present invention, the electrical parameters of the switching elements can be made uniform.

The eighth aspect of the present invention is a radiographic imaging system, comprising the radiographic imaging apparatus of the above aspect and radiation irradiating means for irradiating a radiation detector via a subject.

That is, since the eighth aspect of the present invention includes the radiographic imaging control device according to the above aspect, each defective pixel map at a plurality of resolutions can be easily obtained as in the above aspect.

According to a ninth aspect of the present invention, there is provided a radiographic imaging method, wherein a plurality of pixels including a sensor unit that generates electric charges according to irradiated radiation and a switching element that reads out electric charges generated by the sensor units are provided. A generation step of generating a high-resolution defect pixel map by detecting a defect of a pixel used in predetermined high-resolution imaging in a given radiation detector, and a high-resolution defect pixel map generated in the generation step being lower than the high resolution Converting to a low resolution defective pixel map of resolution.

According to the radiographic imaging method of the ninth aspect of the present invention, the generation step generates a high-resolution defective pixel map, and the conversion means converts the high-resolution defective pixel map generated in the generation step into a low-resolution defective pixel map. Convert. Therefore, the ninth aspect of the present invention can generate high-resolution and low-resolution defective pixel maps with one defective pixel detection. Accordingly, the ninth aspect of the present invention can easily obtain respective defective pixel maps at a plurality of resolutions.

According to a tenth aspect of the present invention, in the ninth aspect, the radiation detector is configured such that the radiation detector generates a charge corresponding to the irradiated radiation, and reads out the charge from the sensor unit and outputs the charge. A plurality of pixels arranged in a two-dimensional manner and a plurality of pixels adjacent to each other in the first direction. A plurality of first control wirings connected to the control ends of the first switching elements, a plurality of second control wirings connected to the control ends of the second switching elements of the plurality of pixels adjacent in the first direction, and pixels When signal lines are provided for each array along a second direction different from the first direction, and the output terminals of the first switching elements of a plurality of pixels adjacent to each other in the second direction are connected for each signal line. In addition, a signal in which the output ends of the second switching elements of a plurality of pixels adjacent in the second direction and the output ends of the second switching elements of the plurality of pixels adjacent in the first direction are connected to some signal wirings. And a wiring group.

Also, in an eleventh aspect of the present invention, in the ninth or tenth aspect, the high resolution defective pixel map and the low resolution defective pixel map may be defined according to the type of defective pixel. According to a twelfth aspect of the present invention, in the ninth to eleventh aspects, the high resolution defective pixel map and the low resolution defective pixel map may be defined according to the cause of the defective pixel.

The thirteenth aspect of the present invention is the ninth to twelfth aspects, further comprising correction means for correcting the defective pixel based on the high resolution defective pixel map or the low resolution defective pixel map. Good. According to a fourteenth aspect of the present invention, in the thirteenth aspect, the correction means is configured to detect a high-resolution pixel included in a low-resolution pixel that is a defective pixel in the low-resolution defective pixel map when photographing at a low resolution. The defective pixels may be corrected by adjusting the gain according to the number of defective pixels.

The fifteenth aspect of the present invention may be a radiographic image capturing program for causing a computer to function as each means of the radiographic image capturing apparatus of the above aspect of the present invention. The radiographic image capturing program of the fifteenth aspect of the present invention can easily obtain each defective pixel map at a plurality of resolutions, as in the above aspect.

In the above aspect of the present invention, by converting a high-resolution defective pixel map into a low-resolution defective pixel map, it is possible to generate high-resolution and low-resolution defective pixel maps with a single defective pixel detection. Therefore, the present invention can provide a radiographic imaging apparatus, a radiographic imaging system, a radiographic imaging method, and a radiographic imaging program that can easily obtain respective defective pixel maps at a plurality of resolutions.

1 is a schematic configuration diagram of an outline of an overall configuration of an example of a radiographic imaging system according to an exemplary embodiment of the present invention. It is the schematic which shows the outline of the cross section of an example of the indirect conversion type radiation detector which concerns on exemplary embodiment of this invention. It is the schematic which shows the outline of the cross section of an example of the direct conversion type | mold radiation detector which concerns on exemplary embodiment of this invention. It is a schematic block diagram of the radiation panel unit which concerns on exemplary embodiment of this invention. It is a block diagram which shows an example of the whole structure of the radiation panel unit which concerns on exemplary embodiment of this invention. It is a figure for demonstrating the imaging operation in the radiation panel unit which concerns on exemplary embodiment of this invention. It is a figure which shows an example of the high resolution defect pixel map of the radiation panel unit concerning exemplary embodiment of this invention, and an example of the low resolution defect pixel map converted from the high resolution defect pixel map. It is a figure for demonstrating the TFT parameter in the radiation panel unit which concerns on exemplary embodiment of this invention. It is a flowchart which shows the flow of an example of the defective pixel map production | generation process performed with the panel control part which concerns on exemplary embodiment of this invention. It is a flowchart which shows an example of the flow of a low-resolution defect pixel map production | generation process. It is a block diagram which shows schematic structure of the radiation detector in the radiation panel unit of a modification. It is a figure for demonstrating the imaging | photography operation | movement in the radiation panel unit of a modification. It is a figure which shows an example of the high resolution defect pixel map in the radiation panel unit of a modification, and an example of the low resolution defect pixel map of the modification converted from the high resolution defect pixel map.

Hereinafter, an example of the exemplary embodiment will be described with reference to the drawings.

First, a schematic configuration of an entire radiographic imaging system including a radiographic image processing apparatus according to an exemplary embodiment of the present invention will be described. FIG. 1 shows a schematic configuration diagram of an outline of an overall configuration of an example of the radiographic imaging system of the present exemplary embodiment. In addition, the radiographic image capturing system 10 of the present exemplary embodiment can capture still images in addition to moving images. Further, in this exemplary embodiment, “radiation image” refers to both a moving image and a still image unless otherwise specified. In the present exemplary embodiment, a moving image refers to displaying still images one after another at a high speed and recognizing them as moving images. A still image is shot, converted into an electric signal, transmitted, and transmitted from the electric signal to the still image. The process of playing back is repeated at high speed. Therefore, the moving image also includes so-called “frame advance” in which the same area (part or all) is shot a plurality of times within a predetermined time and continuously played back depending on the degree of “high speed”. And

The radiographic imaging system 10 of the present exemplary embodiment is based on an instruction (imaging menu) input from an external system (for example, RIS: Radiology Information System: radiation information system) via the console 16. It has a function of taking a radiographic image by an operation of an engineer or the like.

Further, the radiographic imaging system 10 of the present exemplary embodiment has a function of causing a doctor, a radiographer, or the like to interpret a radiographic image by displaying the radiographic image that has been captured on the display 50 of the console 16 or the radiographic image interpretation device 18. It is what has.

The radiographic imaging system 10 of this exemplary embodiment includes a radiation generation device 12, a radiographic image processing device 14, a console 16, a storage unit 17, a radiographic image interpretation device 18, and a radiation panel unit 20.

The radiation generator 12 includes a radiation irradiation control unit 22. The radiation irradiation control unit 22 has a function of irradiating the imaging target region of the subject 30 on the imaging table 32 with the radiation X from the radiation irradiation source 22 </ b> A based on the control of the radiation control unit 62 of the radiation image processing apparatus 14. .

The radiation X transmitted through the subject 30 is irradiated to the radiation panel unit 20 held by the holding unit 34 inside the imaging table 32. The radiation panel unit 20 has a function of generating charges according to the dose of the radiation X that has passed through the subject 30, and generating and outputting image information indicating a radiation image based on the generated charge amount. The radiation panel unit 20 of the present exemplary embodiment is configured to include a radiation detector 26.

In the exemplary embodiment, the image information indicating the radiation image output by the radiation panel unit 20 is input to the console 16 via the radiation image processing device 14. The console 16 of the present exemplary embodiment uses a radiography (LAN: Local Area Network) or the like, a radiation generation apparatus 12 and a radiation panel unit using an imaging menu or various information acquired from an external system (RIS) or the like. It has a function of performing 20 controls. In addition, the console 16 according to the present exemplary embodiment transmits and receives various types of information to and from the radiation panel unit 20 together with a function of transmitting and receiving various types of information including image information of radiographic images to and from the radiation image processing apparatus 14. Has the function to perform.

The console 16 of the present exemplary embodiment is configured as a server computer, and includes a control unit 40, a display driver 48, a display 50, an operation input detection unit 52, an operation panel 54, an I / O unit 56, and an I / F. A portion 58 is provided.

The control unit 40 has a function of controlling the operation of the entire console 16, and includes a CPU, a ROM, a RAM, and an HDD. The CPU has a function of controlling the operation of the entire console 16, and various programs including a control program used by the CPU are stored in advance in the ROM. The RAM has a function of temporarily storing various data, and the HDD (hard disk drive) has a function of storing and holding various data.

The display driver 48 has a function of controlling display of various information on the display 50. The display 50 of the present exemplary embodiment has a function of displaying an imaging menu, a captured radiographic image, and the like. The operation input detection unit 52 has a function of detecting an operation state with respect to the operation panel 54. The operation panel 54 is used by a doctor, a radiographer, or the like to input operation instructions related to radiographic image capturing. In the exemplary embodiment, the operation panel 54 includes, for example, a touch panel, a touch pen, a plurality of keys, a mouse, and the like. When configured as a touch panel, it may be configured the same as the display 50.

Further, the I / O unit 56 and the I / F unit 58 transmit and receive various types of information to and from the radiation image processing device 14 and the radiation generation device 24 through wireless communication, and also perform an image with the radiation panel unit 20. It has a function of transmitting and receiving various information such as information.

The control unit 40, the display driver 48, the operation input detection unit 52, the I / F unit 58, and the I / O unit 56 are connected to each other via a bus 59 such as a system bus or a control bus so that information can be exchanged. ing. Therefore, the control unit 40 controls the display of various information on the display 50 via the display driver 48, and controls the transmission / reception of various information with the radiation generator 12 and the radiation panel unit 20 via the I / F unit 58. Can be performed respectively.

The radiation image processing apparatus 14 according to the exemplary embodiment has a function of controlling the radiation generation apparatus 12 and the radiation panel unit 20 based on an instruction from the console 16. At the same time, the radiation image processing device 14 has a function of controlling storage of the radiation image received from the radiation panel unit 20 in the storage unit 17 and display on the display 50 of the console 16 and the radiation image interpretation device 18. is there.

The radiation image processing apparatus 14 of this exemplary embodiment includes a system control unit 60, a radiation control unit 62, a panel control unit 64, an image processing control unit 66, and an I / F unit 68.

The system control unit 60 has a function of controlling the entire radiographic image processing apparatus 14 and a function of controlling the radiographic image capturing system 10. The system control unit 60 includes a CPU, ROM, RAM, and HDD. The CPU has a function of controlling operations of the entire radiographic image processing apparatus 14 and the radiographic imaging system 10, and various programs including a control program used by the CPU are stored in advance in the ROM. The RAM has a function of temporarily storing various data, and the HDD has a function of storing and holding various data. The radiation control unit 62 has a function of controlling the radiation irradiation control unit 22 of the radiation generator 12 based on an instruction from the console 16. The panel control unit 64 has a function of receiving information from the radiation panel unit 20 wirelessly or by wire, and the image processing control unit 66 has a function of performing various image processes on the radiation image. .

The system control unit 60, the radiation control unit 62, the panel control unit 64, and the image processing control unit 66 are connected to each other through a bus 69 such as a system bus or a control bus so as to be able to exchange information.

The storage unit 17 of the present exemplary embodiment has a function of storing a captured radiographic image and information related to the radiographic image. An example of the storage unit 17 is an HDD.

The radiological image interpretation device 18 of the exemplary embodiment is a device having a function for a radiographer to interpret a captured radiographic image, and is not particularly limited, but includes a so-called radiological image viewer, a console, and the like. . The radiographic image interpretation device 18 of the present exemplary embodiment is configured as a personal computer, and, like the console 16 and the radiographic image processing device 14, a CPU, ROM, RAM, HDD, display driver, display 23, operation input. A detection unit, an operation panel 24, an I / O unit, and an I / F unit are provided. In FIG. 1, only the display 23 and the operation panel 24 are shown, and other descriptions are omitted in order to avoid complicated description.

Next, the radiation panel unit 20 will be described in detail. First, the radiation detector 26 provided in the radiation panel unit 20 will be described. The radiation detector 26 of the present exemplary embodiment includes a TFT substrate.

As an example of the radiation detector 26, a schematic cross-sectional view of an example of the indirect conversion type radiation detector 26 is shown in FIG. The radiation detector 26 shown in FIG. 2 includes a TFT substrate and a radiation conversion layer.

The bias electrode 72 has a function of applying a bias voltage to the radiation conversion layer 74. In the exemplary embodiment, radiation detector 26 is a hole reading sensor. Therefore, a positive bias voltage is supplied to the bias electrode 72 from a high voltage power source (not shown). In the case where the radiation detector 26 is configured as an electronic reading sensor that reads electrons generated according to the irradiated radiation, a negative bias voltage is supplied to the bias electrode 72.

The radiation conversion layer 74 is a scintillator, and is formed so as to be laminated between the bias electrode 72 and the upper electrode 82 via the upper electrode 82 and the transparent insulating film 80 in the radiation detector 26 of this exemplary embodiment. Has been. The radiation conversion layer 74 is formed by forming a phosphor that emits light by converting the radiation X incident from above or below into light. Providing such a radiation conversion layer 74 absorbs the radiation X and emits light.

The wavelength range of light emitted by the radiation conversion layer 74 is preferably a visible light range (wavelength 360 nm to 830 nm). In order to enable monochrome imaging by the radiation detector 26, the wavelength range of green is included. More preferably.

As the scintillator used for the radiation conversion layer 74, a scintillator that generates fluorescence having a relatively wide wavelength region that can generate light in a wavelength region that can be absorbed by the TFT substrate 70 is desirable. Examples of such a scintillator include CsI: Na, CaWO ₄ , YTaO ₄ : Nb, BaFX: Eu (X is Br or Cl), LaOBr: Tm, and GOS. Specifically, when imaging is performed using X-rays as radiation X, those containing cesium iodide (CsI) are preferable, and CsI: Tl (thallium is added) having an emission spectrum of 400 nm to 700 nm upon X-ray irradiation. It is particularly preferable to use cesium iodide) or CsI: Na. Note that the emission peak wavelength in the visible light region of CsI: Tl is 565 nm. In addition, when using the scintillator containing CsI as the radiation conversion layer 74, it is preferable to use what was formed as a strip-like columnar crystal structure by the vacuum evaporation method.

The upper electrode 82 needs to cause the light generated by the radiation conversion layer 74 to enter the photoelectric conversion film 86. Therefore, the upper electrode 82 is preferably made of a conductive material that is transparent at least with respect to the emission wavelength of the radiation conversion layer 74. Specifically, the transparent electrode has a high visible light transmittance and a low resistance value. It is preferable to use a conductive oxide (TCO). Although a metal thin film such as Au can be used as the upper electrode 82, the TCO is preferable because the resistance value tends to increase when the transmittance of 90% or more is obtained. For example, ITO, IZO, AZO, FTO, SnO ₂ , TiO ₂ , ZnO _{2 and the} like can be preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. Note that the upper electrode 82 may have a single configuration common to all pixels, or may be divided for each pixel.

The photoelectric conversion film 86 is made of an organic photoelectric conversion material that absorbs light emitted from the radiation conversion layer 74 and generates charges. The photoelectric conversion film 86 includes an organic photoelectric conversion material, absorbs light emitted from the radiation conversion layer 74, and generates electric charges according to the absorbed light. Thus, the photoelectric conversion film 86 containing an organic photoelectric conversion material has a sharp absorption spectrum in the visible range, and electromagnetic waves other than light emission by the radiation conversion layer 74 are hardly absorbed by the photoelectric conversion film 86. Noise generated by the radiation X such as X-rays being absorbed by the photoelectric conversion film 86 can be effectively suppressed.

The organic photoelectric conversion material constituting the photoelectric conversion film 86 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the radiation conversion layer 74 in order to most efficiently absorb the light emitted from the radiation conversion layer 74. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the radiation conversion layer 74, but if the difference between the two is small, the light emitted from the radiation conversion layer 74 is sufficiently absorbed. Is possible. Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the radiation conversion layer 74 is preferably within 10 nm, and more preferably within 5 nm. Examples of organic photoelectric conversion materials that can satisfy such conditions include quinacridone-based organic compounds and phthalocyanine-based organic compounds. For example, since the absorption peak wavelength of quinacridone in the visible region is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI: Tl is used as the material of the radiation conversion layer 74, the difference in the peak wavelength may be within 5 nm. The amount of charge generated in the photoelectric conversion film 86 can be substantially maximized.

In order to suppress an increase in dark current, it is preferable to provide at least one of the electron blocking film 88 and the hole blocking film 84, and it is more preferable to provide both. The electron blocking film 88 can be provided between the lower electrode 90 and the photoelectric conversion film 86. When a bias voltage is applied between the lower electrode 90 and the upper electrode 82, electrons are transferred from the lower electrode 90 to the photoelectric conversion film 86. It is possible to suppress the dark current from increasing due to the injection of. An electron donating organic material can be used for the electron blocking film 88. On the other hand, the hole blocking film 84 can be provided between the photoelectric conversion film 86 and the upper electrode 82. When a bias voltage is applied between the lower electrode 90 and the upper electrode 82, the photoelectric conversion film is formed from the upper electrode 82. It is possible to suppress the increase of dark current due to the injection of holes into 86. An electron-accepting organic material can be used for the hole blocking film 84.

A plurality of lower electrodes 90 are formed in a lattice shape (matrix shape) at intervals, and one lower electrode 90 corresponds to one pixel. Each lower electrode 90 is connected to a field effect thin film transistor (hereinafter referred to simply as “TFT”) 98 and a storage capacitor 96 of the signal output unit 94. An insulating film 92 is interposed between the signal output unit 94 and the lower electrode 90, and the signal output unit 94 is formed on the insulating substrate 93. Since the insulating substrate 93 absorbs the radiation X in the radiation conversion layer 74, the insulating substrate 93 has a low X radiation absorbability and is a flexible electrically insulating thin substrate (a substrate having a thickness of about several tens of μm). Specifically, it is preferably a synthetic resin, aramid, bionanofiber, or film glass (ultra thin glass) that can be wound into a roll.

The signal output unit 94 corresponds to the lower electrode 90, and is a storage capacitor 96 that stores the charge transferred to the lower electrode 90, and a switching element that converts the charge stored in the storage capacitor 96 into an electrical signal and outputs the electrical signal. A TFT 98 is formed. The region where the storage capacitor 96 and the TFT 98 are formed has a portion overlapping the lower electrode 90 in plan view. In order to minimize the plane area of the radiation detector 26 (pixel), it is desirable that the region where the storage capacitor 96 and the TFT 98 are formed is completely covered by the lower electrode 90.

As shown in FIG. 2, the radiation detector 26 is irradiated with radiation X from the side on which the radiation conversion layer 74 is formed, and a radiation image is obtained by a TFT substrate 70 provided on the back side of the incident surface of the radiation X. When the so-called back side reading method (PSS (Pentration Side Sampling) method) is used, light is emitted more strongly on the upper surface side of the radiation conversion layer 74 in FIG. On the other hand, there is a so-called surface reading method (ISS (Irradiation Side Sampling) method) in which radiation X is irradiated from the TFT substrate 70 side and a radiation image is read by the TFT substrate 70 provided on the surface side of the incident surface of the radiation X. In this case, the radiation X transmitted through the TFT substrate 70 enters the radiation conversion layer 74 and the TFT substrate 70 side of the radiation conversion layer 74 emits light more strongly. Electric charges are generated in the photoelectric conversion portion 87 of each pixel 100 provided on the TFT substrate 70 by the light generated in the radiation conversion layer 74. For this reason, the radiation detector 26 is closer to the emission position of the radiation conversion layer 74 with respect to the TFT substrate 70 when the front surface reading method is used than when the rear surface reading method is used. High resolution.

The radiation detector 26 may be a direct conversion type radiation detector as shown in a schematic cross-sectional view of an example in FIG. The radiation detector 26 shown in FIG. 3 also includes a TFT substrate and a radiation conversion layer, as in the indirect conversion type described above.

The TFT substrate 110 has a function of collecting and reading (detecting) carriers (holes) that are charges generated in the radiation conversion layer 118. The TFT substrate 110 includes an insulating substrate 122 and a signal output unit 124. When the radiation detector 26 is configured as an electronic reading sensor, the TFT substrate 110 is configured to have a function of collecting and reading out electrons.

Since the insulating substrate 122 absorbs the radiation X in the radiation conversion layer 118, the insulating substrate 122 has a low X radiation absorbability and is a flexible electrically insulating thin substrate (a substrate having a thickness of about several tens of μm). Specifically, it is preferably a synthetic resin, aramid, bionanofiber, or film glass (ultra thin glass) that can be wound into a roll.

The signal detection unit 85 includes a storage capacitor 126 that is a charge storage capacitor, a TFT 128 that is a switching element that converts the electric charge stored in the storage capacitor 126 into an electric signal, and the charge collecting electrode 121.

A plurality of charge collection electrodes 121 are formed in a lattice shape (matrix shape) at intervals, and one charge collection electrode 121 corresponds to one pixel. Each charge collecting electrode 121 is connected to the TFT 128 and the storage capacitor 126.

The storage capacitor 126 has a function of storing charges (holes) collected by the charge collection electrodes 121. The charges accumulated in the respective storage capacitors 126 are read out by the TFT 128. As a result, a radiographic image is taken by the TFT substrate 110.

The undercoat layer 120 is formed between the radiation conversion layer 118 and the TFT substrate 110. The undercoat layer 120 preferably has a rectifying characteristic from the viewpoint of reducing dark current and leakage current. Therefore, the resistivity of the undercoat layer 120 is preferably 10 ⁸ Ωcm or more, and the film thickness is preferably 0.01 μm to 10 μm.

The radiation conversion layer 118 is a photoelectric conversion layer made of a photoconductive material that absorbs irradiated radiation and generates positive and negative charges (electron-hole carrier pairs) according to the radiation. It is preferable that (α-Se) is a main component. The radiation conversion layer 118 includes Bi ₂ MO ₂₀ (M: Ti, Si, Ge), Bi ₄ M ₃ O ₁₂ (M: Ti, Si, Ge), Bi ₂ O ₃ , BiMO ₄ (M: Nb). , Ta, V), Bi ₂ WO ₆ , Bi ₂₄ B ₂ O ₃₉ , ZnO, ZnS, ZnSe, ZnTe, MNbO ₃ (M: Li, Na, K), PbO, HgI ₂ , PbI ₂ , CdS, CdSe, A compound mainly composed of at least one of CdTe, BiI ₃ , GaAs, etc. may be used, but it has a high dark resistance, shows good photoconductivity against radiation irradiation, and is formed at a low temperature by vacuum deposition. An amorphous material capable of forming a large area is preferable.

The thickness of the radiation conversion layer 118 is preferably 100 μm or more and 2000 μm or less in the case of a photoconductive material containing α-Se as a main component, as in the present exemplary embodiment, for example. The thickness of the radiation conversion layer 118 is preferably in the range of 100 μm to 250 μm for mammography applications and 500 μm to 1200 μm for general imaging applications.

The electrode interface layer 116 has a function of blocking hole injection and a function of preventing crystallization, and is formed between the radiation conversion layer 118 and the overcoat layer 114. The electrode interface layer 116 is preferably an inorganic material such as CdS, CeO ₂ , Ta ₂ O ₅ , or SiO, or an organic polymer. The layer made of an inorganic material is preferably used by adjusting the carrier selectivity by changing the composition from the stoichiometric composition or by using a multi-component composition with two or more kinds of homologous elements. As the layer made of an organic polymer, an insulating polymer such as polycarbonate, polystyrene, polyimide, polycycloolefin, and the like can be used by mixing a low molecular weight electron transport material in a weight ratio of 5% to 80%. As such electron transporting materials, trinitrofluorene and derivatives thereof, diphenoquinone derivatives, bisnaphthyl quinone derivatives, oxazole derivatives, triazole derivatives, C _{60 (fullerene),} such a mixture of carbon clusters such as C ₇₀ are preferred. Specific examples include TNF, DMDB, PBD, and TAZ. On the other hand, a thin insulating polymer layer can also be used preferably. For example, acrylic resins such as parylene, polycarbonate, PVA, PVP, PVB, polyester resin, and polymethyl methacrylate are preferable. In this case, the film thickness is preferably 2 μm or less, and more preferably 0.5 μm or less.

The overcoat layer 114 is formed between the electrode interface layer 116 and the bias electrode 112. The overcoat layer 114 preferably has rectification characteristics from the viewpoint of reducing dark current and leakage current. Therefore, the resistivity of the overcoat layer 114 is preferably 10 ⁸ Ωcm or more, and the film thickness is preferably 0.01 μm to 10 μm. The bias electrode 112 is substantially the same as the bias electrode 72 in the direct conversion type described above, and has a function of applying a bias voltage to the radiation conversion layer 118.

Furthermore, the radiation detector 26 is not limited to that shown in FIGS. 2 and 3 and can be variously modified. For example, in the case of the back side scanning method, the signal output units (94, 124) with low possibility of arrival of radiation X are CMOS (ComplementaryａｒMetal-Oxide Semiconductor) images with low resistance to radiation X instead of the above-described ones. You may combine TFT with other imaging elements, such as a sensor. Further, it may be replaced with a CCD (Charge-Coupled Device) image sensor that transfers charges while shifting them with a shift pulse corresponding to the gate signal of the TFT.

For example, a flexible substrate may be used. As the flexible substrate, it is preferable to apply a substrate using ultra-thin glass by a recently developed float method as a base material in order to improve the radiation transmittance. As for the ultra-thin glass that can be applied at this time, for example, “Asahi Glass Co., Ltd.,“ Successfully developed the world's thinnest 0.1 mm thick ultra-thin glass by the float method ”, [online], [2011 Aug. 20 search], Internet <URL: http://www.agc.com/news/2011/0516.pdf> ”.

Next, a circuit configuration of the radiation panel unit 20 that is a radiation image capturing apparatus including the radiation detector 26 according to the exemplary embodiment described above will be described. FIG. 4 shows a schematic configuration diagram of a radiation panel unit 20 including a radiation detector 26 according to an exemplary embodiment of the present invention, and FIG. 5 shows a schematic circuit configuration diagram of an example of the radiation panel unit 20. In the following, the radiation panel unit 20 including the radiation detector 26 shown in FIG. 2 will be described as a specific example. Further, in the present exemplary embodiment, a case where the indirect conversion type radiation detector 26 is applied will be described. 4 and 5, the radiation conversion layer (scintillator) 74 that converts radiation into light is omitted.

The radiation panel unit 20 includes the radiation detector 26 described above. As shown in FIG. 5, the radiation detector 26 generates a charge upon receiving light, stores a photoelectric conversion unit 87 that accumulates the generated charge, and a switching element for reading out the charge stored in the photoelectric conversion unit 87. A plurality of pixels 21 including two TFTs (TFT1, TFT2) are arranged in a matrix. In the present exemplary embodiment, the photoelectric conversion unit 87 generates electric charges when irradiated with light converted by the scintillator.

A plurality of pixels 21 are arranged in a two-dimensional matrix in one direction (the horizontal direction in FIG. 5, hereinafter also referred to as “row direction”) and the cross direction with respect to the row direction (the vertical direction in FIG. 5, hereinafter also referred to as “column direction”). Has been placed. In FIG. 5, the arrangement of the pixels 21 is shown in a simplified manner. For example, 1024 × 1024 pixels 21 are arranged in the row direction and the column direction.

Further, the radiation detector 26 includes a plurality of control wires G (G1 to G4 in FIG. 5) for controlling ON / OFF of the TFT 1 and a plurality of control wires M (for controlling ON / OFF of the TFT 2). In FIG. 5, M1 and M2) and a plurality of signal wirings D (D1 to D4 in FIG. 5) provided for each column of the pixels 21 for reading out the electric charges accumulated in the photoelectric conversion unit 87 are provided. They are provided to cross each other. In the present exemplary embodiment, for example, when 1024 × 1024 pixels 21 are arranged in the row direction and the column direction, 1024 control wirings G and signal wirings D are provided. In this case, the number of the control wirings M is half that of the control wirings G, that is, 512.

The photoelectric conversion unit 87 of each pixel 21 is connected to a common wiring (not shown), and is configured to be applied with a bias voltage from a power source (not shown) via the common wiring.

Control signal for switching each TFT 1 flows through the control wiring G. In this way, when the control signal flows through each control wiring G, each TFT 1 is switched. A control signal for switching each TFT 2 flows through the control wiring M. In this way, when the control signal flows through each control wiring M, each TFT 2 is switched.

In the signal wiring D, an electrical signal corresponding to the amount of charge accumulated in each pixel 21 flows through the TFT 1 or TFT 2 according to the switching state of the TFT 1 and the switching state of the TFT 2 of each pixel 21 (details will be described later).

Each signal wiring D is connected to a signal detection circuit 130 that detects an electrical signal flowing out to each signal wiring D. Each control wiring G is connected to a first gate circuit 132 that outputs a control signal for turning on / off the TFT 1 to each control wiring G. Each control wiring M is turned on / off the TFT 2 to each control wiring M. A second gate circuit 134 that outputs a control signal for turning OFF is connected. 4 and 5, two gate circuits of the first gate circuit 132 and the second gate circuit 134 are provided for simplification of illustration of wiring and the like, but in the present exemplary embodiment, these are provided. They may not be separate but may be the same or separate.

In FIG. 5, the signal detection circuit 130, the first gate circuit 132, and the second gate circuit 134 are illustrated in a simplified manner, but for example, the signal detection circuit 130, the first gate circuit 132, As shown in FIG. 4, the two-gate circuit 134 includes a plurality of

drivers

131, 133, and 135 each connected with a signal wiring D, a control wiring G, and a control wiring M for every predetermined number (for example, 256). Has been. Since the number of control lines M connected to the second gate circuit 134 is smaller than the number of control lines G connected to the first gate circuit 132, the number of drivers 133 of the first gate circuit 132 is smaller than the number of drivers 133. The number of drivers 134 is reduced.

The signal detection circuit 130 incorporates an amplification circuit (not shown) for amplifying an input electric signal for each signal wiring D. In the signal detection circuit 130, an electric signal input from each signal wiring D is amplified by an amplifier circuit and converted into a digital signal by an ADC (analog / digital converter, not shown).

The signal detection circuit 130, the first gate circuit 132, and the second gate circuit 134 are subjected to predetermined processing such as noise removal on the digital signal converted by the signal detection circuit 130, and the signal detection circuit 130 A panel control unit 136 that outputs a control signal indicating the timing of signal detection and outputs a control signal indicating the output timing of the scan signal to the first gate circuit 132 and the second gate circuit 134 is connected. .

The panel control unit 136 of the present exemplary embodiment is configured by a microcomputer and includes a nonvolatile storage unit including a CPU (Central Processing Unit), ROM and RAM, flash memory, and the like. For example, as shown in FIG. 4, the panel control unit 136 may be configured using an FPGA (Field-Programmable-Gate-Array). The panel control unit 136 performs predetermined processing on the image data of the radiation detection pixels 21 to generate and output a radiation image indicated by the irradiated radiation.

Here, the radiographic image capturing operation by the radiation panel unit 20 of the present exemplary embodiment will be described with reference to FIGS. The radiation panel unit 20 detects the start of radiation irradiation, accumulates charges in each pixel 21 of the radiation detector 26, and outputs a radiation image based on image data corresponding to the accumulated charges to capture a radiation image. To do.

In the radiation panel unit 20 of the present exemplary embodiment, when shooting with high resolution (for example, shooting a still image), and shooting with low resolution and a high frame rate (for example, shooting of a moving image). Although two types of photographing can be performed, the operation differs depending on each type.

In the exemplary embodiment, either high-resolution shooting or low-resolution shooting is performed based on an instruction from the console 16. Regardless of high-resolution imaging or low-resolution imaging, charges corresponding to the irradiated radiation are accumulated by the photoelectric conversion unit 87.

First, the case of performing high-resolution shooting such as still image shooting will be described.

When performing high-resolution shooting such as still image shooting, a control signal is output from the second gate circuit 134 to the control wiring M so that the TFT 2 is turned off. On the other hand, a control signal is sequentially output from the first gate circuit 132 to the control wiring G so as to turn on the TFT 1. In the pixel 21 in which the TFT 1 is in the on state, the charge is read from the photoelectric conversion unit 87 and the charge is output to the signal wiring D.

As described above, in the radiation panel unit 20 of the present exemplary embodiment, when high-resolution imaging such as still image imaging is performed, electric charges flow in all the signal wirings D1 to D4 for each column. That is, charge flows through the signal wiring D for each pixel 21.

The electric signal corresponding to the electric charge is converted into a digital signal by the signal detection circuit 130, and the radiation image based on the image data corresponding to the electric signal is generated by the panel control unit 136.

Next, a case where low resolution shooting such as movie shooting is performed will be described.

When performing low-resolution shooting such as moving image shooting, a control signal is output from the first gate circuit 132 to the control wiring G so that the TFT 1 is turned off. On the other hand, a control signal is sequentially output from the second gate circuit 134 to the control wiring M so as to turn on the TFT 2. In the pixel 21 in which the TFT 2 is on, the charge is read from the photoelectric conversion unit 87 and the charge is output to the signal wiring D.

As shown in FIG. 6, when a control signal is output to the control wiring M1 to turn on the TFT2, the TFT2 of the eight pixels 21 (21 (1) to 21 (8)) is turned on, The charges of the four pixels 21 (21 (1), 21 (2), 21 (5), 21 (6)) are output to the signal wiring D1. In addition, the charges of the four pixels 21 (21 (3), 21 (4), 21 (7), 21 (8)) are output to the signal wiring D3.

Further, when a control signal is output to the control wiring M2 to turn on the TFT2, the TFTs 2 of the eight pixels 21 (21 (9) to 21 (16)) are turned on, and the four pixels 21 are turned on. The charges (21 (9), 21 (10), 21 (13), 21 (14)) are output to the signal wiring D2. In addition, the charges of the four pixels 21 (21 (11), 21 (12), 21 (15), 21 (16)) are output to the signal wiring D4.

As described above, in the radiation panel unit 20 of the present exemplary embodiment, when low-resolution shooting such as moving image shooting is performed, the sum of charges of 2 pixels × 2 pixels is alternately (even) in the adjacent signal wiring D. The signal wiring D to which numbers are assigned and the signal wiring D to which odd numbers are assigned alternately).

In addition, when performing low-resolution shooting such as moving image shooting, 2 × 2 pixels are regarded as one pixel 31 and a charge is taken out. Therefore, although the resolution is lower than that in high-resolution shooting, the frame rate is reduced. It can be doubled (frame period is halved).

Incidentally, since each pixel of the radiation detector 26 may include a defective pixel, it is necessary to generate and correct a defective pixel map. In the present exemplary embodiment, as described above, since it is possible to switch between high-resolution imaging and low-resolution imaging, a defective pixel map is required for each.

Therefore, in this exemplary embodiment, after generating a high-resolution defective pixel map, a low-resolution defective pixel map is generated using the generated high-resolution defective pixel map.

The defective pixel detection method may be such that the defective pixel is detected based on the value of each pixel when a predetermined amount of radiation is irradiated, or the defective pixel is based on the value of each pixel during a period when radiation is not irradiated. May be detected. A specific method for detecting a defective pixel can be detected by, for example, a well-known technique (for example, a method described in JP 2008-252564 A or JP 2010-233886 A).

Further, in this exemplary embodiment, these known techniques are used to determine the type of defective pixel, such as a point defect or a line defect, and whether it is a disconnected pixel, and define it in the defective pixel map. It is like that.

In the present exemplary embodiment, defective pixels are detected and a high-resolution defective pixel map as shown in (1) of FIG. 7 is generated. At this time, a defect pixel map is generated by defining the type of defect.

Then, by converting the pixel resolution of the high resolution defective pixel map to a low resolution, a low resolution defective pixel map is generated as shown in (2) of FIG. In addition, the hatched part in FIG. 7 shows a defective pixel, and shows an example in which there are a line defect and a point defect.

Defective pixels can be corrected by the panel control unit 136 using the defective pixel maps generated in this way. For example, as a correction method, a defective pixel such as a point defect or a line defect can be corrected by interpolation using peripheral pixels. For correction for low-resolution shooting, the gain is adjusted according to the number of defective pixels of the high-resolution pixels included in the low-resolution pixels 31 (for example, when one of the four pixels is a defective pixel, The gain may be corrected by increasing the gain by 4/3 times, or may be corrected by interpolating using peripheral low-resolution pixels, or may be corrected by interpolating in the high-resolution pixels and then low-resolution. Pixels may be obtained. Alternatively, a threshold is provided for the number of defective pixels of the high-resolution pixel in the low-resolution pixel 31, and if there is a defective pixel that is greater than or equal to the threshold, interpolation is performed from surrounding pixels, and if the number of defective pixels is less than the threshold, the gain is You may make it correct | amend by increasing.

In the present embodiment, the panel control unit 136 corrects the defective pixel. However, the generated defective pixel map may be transmitted to the radiation image processing apparatus 14 or the console 16 to perform correction.

In this exemplary embodiment, a low-resolution defective pixel map is generated from a high-resolution defective pixel map. However, if the TFT parameters are different, the defect map and the correction map cannot be shared. It is necessary to make the sizes and orientations of the two TFTs (TFT1, TFT2), which are switching elements for reading out the electric charges accumulated in the portion 87, uniform.

Therefore, in this exemplary embodiment, as shown in FIG. 8, the drain / source direction (length direction) of the two TFTs (TFT1, TFT2) and the gate direction (width direction) orthogonal to the length direction are respectively shown. It is set as the structure arrange | positioned so that it may be aligned. Further, since the leakage current value is different even if the length / width ratio of the TFT is the same, the length in each direction needs to be the same, so the length in each direction is also the same. Has been. Thus, by making the TFT directions the same, differences due to the exposure machine and the photomask can be suppressed, so that the electrical parameters such as Ioff and Ion of the TFT can be made the same.

Subsequently, processing when generating a defective pixel map performed by the panel control unit 136 will be described. FIG. 9 is a flowchart illustrating an example of a defective pixel map generation process performed by the panel control unit 136 according to an exemplary embodiment of the present invention.

When generating a defective pixel map, for example, according to an instruction from the console 16, a predetermined amount of radiation is irradiated to the radiation panel unit 20 from the radiation generator 12.

When the radiation panel unit 20 is irradiated with radiation, in step 200, the target high resolution pixel X = 1 is set and the process proceeds to step 202. That is, the pixel of interest (high resolution pixel) 21 is selected.

In step 202, it is determined whether or not the pixel is a defective pixel. If the determination is affirmative, the process proceeds to step 204. If the determination is negative, the process proceeds to step 210. As a method for determining a defective pixel, it may be determined based on the value of each pixel when a predetermined amount of radiation is irradiated, or a known technique (for example, Japanese Patent Application Laid-Open No. 2008-252564 or a special technique). The method may be determined by a method described in Japanese Unexamined Patent Publication No. 2010-233886.

In step 204, the type of defective pixel is detected, and the process proceeds to step 206. As a method for detecting the type of defective pixel, it is possible to detect whether it is a point defect or a line defect using the method described in Japanese Patent Application Laid-Open No. 2008-252564. The cause of the defective pixel may be detected instead of the type of the defective pixel, or both the type and cause may be detected. As a method for detecting the cause of a defective pixel, for example, it can be detected by using a method described in JP 2010-233886 A.

In step 206, the pixel of interest X is defined as a defective pixel and a high-resolution defective pixel map is generated as a defective pixel, and the process proceeds to step 210. When the cause of the defective pixel is detected, the cause of the defective pixel is also defined and a high resolution defective pixel map is generated as the defective pixel.

On the other hand, in step 208, a high-resolution defective pixel map is generated with the target pixel X as a normal defect, and the process proceeds to step 210.

In step 210, the high resolution pixel X of interest is incremented by 1 (X + 1), and the process proceeds to step 212.

In step 212, it is determined whether or not the detection of defective pixels of all pixels has been completed. If the determination is negative, the process returns to step 202 and the above processing is repeated. If the determination is affirmative, the process returns to step 214. Transition.

In step 214, a low-resolution defective pixel map generation process for converting from a high-resolution defective pixel map to a low-resolution defective pixel map is performed, and a series of defective pixel map generation processes ends.

Here, the low-resolution defective pixel map generation process performed in step 214 will be described in detail. FIG. 10 is a flowchart illustrating an example of the flow of low-resolution defective pixel map generation processing.

In step 300, the high-resolution defective pixel map generated above is acquired, and the process proceeds to step 302.

In step 302, the target low resolution pixel Y = 1 is set, and the process proceeds to step 304. That is, the pixel (low-resolution pixel 31) of 2 pixels (high-resolution pixel 21) × 2 pixels (high-resolution pixel 21) of interest is selected.

In step 304, the state of the high resolution pixel corresponding to the low resolution pixel 31 of interest is read from the high resolution defective pixel map, and the process proceeds to step 306.

In step 306, it is determined whether or not the high-resolution pixel 21 in the target low-resolution pixel 31 has a defective pixel. If the determination is affirmative, the process proceeds to step 308. If the determination is negative, the determination is negative. The process proceeds to step 310.

In step 308, the type is defined and a low resolution defective pixel map is generated as a defective pixel, and the process proceeds to step 312. Similar to the high-resolution defective pixel map, the cause of the defective pixel may be defined instead of the type of the defective pixel, or both the type and the cause may be defined.

On the other hand, in step 310, a low-resolution defective pixel map is generated as a normal pixel, and the process proceeds to step 312.

In step 312, the noticed high resolution pixel X is incremented by 1 (X + 1), and the process proceeds to step 314.

In step 314, it is determined whether or not the detection of defective pixels of all pixels has been completed. If the determination is negative, the process returns to step 302 and the above-described processing is repeated. When the determination is affirmative, a series of processing is performed. Exit.

In this way, in the present exemplary embodiment, after a defective pixel map for high resolution is generated, a defective pixel map for low resolution is generated by pixel density conversion of the generated defective pixel map for high resolution. As a result, a defective pixel map having two resolutions can be generated with one defective pixel detection, so that a defective pixel map can be easily obtained. Further, by using the defective pixel maps of the high-resolution imaging and the low-resolution imaging obtained as described above, the panel control unit 136 can correct the defective pixels.

The configuration of the radiation panel unit 20 is not limited to the configuration described in the above exemplary embodiment, and other configurations may be applied. Below, the modification of a radiation panel unit is demonstrated. In the radiation panel unit of the modification, the same part as the radiation panel unit 20 of the above exemplary embodiment is described as such, and detailed description thereof is omitted. In addition, since the radiation panel unit of a modification differs in the structure of the radiation detector from the radiation detector 26 of the said exemplary embodiment, the radiation detector in a modification is demonstrated in detail.

FIG. 11 shows a configuration diagram of an example of a schematic configuration of the radiation detector in the radiation panel unit of the modified example.

Similar to the radiation detector 26 of the above exemplary embodiment, the radiation detector 27 of the modified example includes a photoelectric conversion unit 87 and two TFTs (switching elements for reading out charges accumulated in the photoelectric conversion unit 87 ( A plurality of pixels 21 including a still image TFT 1 and a moving image TFT 2) are arranged in a matrix.

The radiation detector 26 includes a plurality of control wires G (G1 to G4 in FIG. 11) for controlling ON / OFF of the TFT 1 and a plurality of control wires M (FIG. 11) for controlling ON / OFF of the TFT 2. Then, M1) and a plurality of signal wirings D (D1 to D5 in FIG. 11) provided for each column of the pixels 21 for reading out the charges accumulated in the photoelectric conversion unit 87 intersect each other. Is provided. In FIG. 11, only one control wiring M (control wiring M1) is shown, but the number according to the number of rows of the pixels 21, more specifically, the number of control wirings G (the number of the control lines M1). (Number of lines) is provided.

In the radiation detector 26 of the modification, the positional relationship of the control wiring G and the control wiring M connected to the control terminals of the TFT1 and TFT2 connected to the same photoelectric conversion unit 87 with respect to the pixels 21 is an even row of the pixel array. It is configured to invert with odd lines. As shown in FIG. 11, the arrangement relationship between the TFT 1, the TFT 2, and the photoelectric conversion unit 87 is inverted between the even lines and the odd lines of the control wiring G. That is, for example, as can be seen by referring to the pixel 21 (1) and the pixel 21 (5), the TFT1, the TFT2, and the photoelectric conversion unit 87 are arranged so that the arrangement positions are line-symmetric with respect to the control wiring M. Has been placed. By disposing each element in this manner, the TFT 2 of the pixel 21 (1) and the pixel 21 (5) can also be used as the control wiring M. Therefore, the number of the control wiring M is compared with the above exemplary embodiment. Can be reduced. Therefore, the number of control wirings (control wiring G + control wiring M) can be reduced as compared with the above exemplary embodiment.

In the radiation detector 26 of the exemplary embodiment shown in FIG. 5, the control wiring G includes four control wirings G1 to G4, and the control wiring M includes four control wirings M1 and M2 × 2, for a total of eight. Control wiring is required. Therefore, the number of rows × 2 control wirings is required. On the other hand, in the radiation detector 26 shown in FIG. 11 of the modified example, the control wiring G has four control wirings G1 to G4, the control wiring M has two control wirings M1 × 2, and a total of six control wirings. Necessary. Therefore, the number of rows × 1.5 control wirings is required. Thus, in the radiation detector 26 according to the modification, the number of control wirings can be reduced.

Further, in the radiation detector 26 of the modified example, since the TFT 1 is disposed at a position closer to the control wiring G than the TFT 2, the connection wiring for connecting the TFT 1 to the control wiring G can be shortened. On the other hand, since the TFT 2 is disposed at a position closer to the control wiring M than the TFT 1, the connection wiring for connecting the TFT 2 to the control wiring M can be shortened. As a result, it is possible to improve the manufacturing yield.

Next, a radiographic image capturing operation by the radiation detector 26 according to the modification will be described with reference to FIGS.

As described above, in the radiation detector 26 according to the modified example, when a still image is taken, a charge flows in each of the signal wirings D1 to D4 for each column as in the above exemplary embodiment. That is, charge flows through the signal wiring D for each pixel 21.

When performing low-resolution shooting such as moving image shooting, a control signal is output from the first gate circuit 132 to the control wiring G so that the TFT 1 is turned off. On the other hand, a control signal is output from the second gate circuit 134 to the control wiring M so as to turn on the TFT 2. In the pixel 21 in which the TFT 2 is on, the charge is read from the photoelectric conversion unit 87 and the charge is output to the signal wiring D.

As shown in FIG. 12, when a control signal is output to the control wiring M1 to turn on the TFT2, the TFT2 of the 16 pixels 21 (21 (1) to 21 (16)) is turned on. The charges of the two pixels 21 (21 (1) and 21 (5)) are output to the signal wiring D1. Further, the charges of the four pixels 21 (21 (9), 21 (10), 21 (13), 21 (14)) are output to the signal wiring D2. In addition, the charges of the four pixels 21 (21 (2), 21 (3), 21 (6), 21 (7)) are output to the signal wiring D3. Furthermore, the charges of the four pixels 21 (21 (11), 21 (12), 21 (15), 21 (16)) are output to the signal wiring D4. Furthermore, the charges of the two pixels 21 (21 (4), 21 (8)) are output to the signal wiring D5.

As described above, in the radiation detector 26 of the modified example, when low-resolution imaging is performed, the sum of charges of 2 pixels × 2 pixels flows to the adjacent signal wiring D. In addition, when performing low-resolution imaging, the 2 pixels 20 × 2 pixels 21 are regarded as one pixel 31 and the charge is extracted. Therefore, although the resolution is lower than that in high-resolution imaging, the frame rate is quadrupled ( The frame period can be reduced to 1/4).

As described above, in the radiation detector 26 of the modified example, each element (TFT1, TFT2, photoelectric conversion unit 87) is arranged so that the 2 pixels 20 × 2 pixels 21 can be regarded as one pixel 31 in advance. Therefore, the frame rate can be improved as compared with high-resolution imaging. In particular, in the modified example, the pixels 31 that can be regarded as one pixel are arranged so as to be staggered in the column direction. Accordingly, since the charge can flow through the adjacent signal wiring D by one reading, the frame rate can be quadrupled.

In addition, since it is arranged so as to be symmetric with respect to the control wiring M, an increase in the number of control wirings can be suppressed, so that the connection electrodes (illustrated) between the outputs of the TFT1 and TFT2 and the signal wiring D are shown. (Omitted) can be shortened. Thereby, a manufacturing yield can be maintained high.

Even in the modified example configured as described above, when the defective pixel map is generated, the high-resolution defect pixel map is generated after using the generated high-resolution defect map, as in the above exemplary embodiment. Generate a low resolution defective pixel map.

That is, a defective pixel is detected and a high-resolution defect map as shown in (1) of FIG. 13 is generated. At this time, a defect pixel map is generated by defining the type of defect. Thereafter, the high-resolution defective pixel map is converted into a normal array by converting the pixel density to a low resolution, thereby generating a low-resolution defective pixel map as shown in FIG. In addition, the hatched part in FIG. 13 shows a defective pixel, and shows an example with a line defect and a point defect.

This makes it possible to correct a defective pixel using a defective pixel map, as in the above exemplary embodiment.

In the present exemplary embodiment, high-resolution imaging is performed during normal periodic calibration (for example, various corrections for removing noise caused by dark current of the radiation panel unit 20 and measures for image sticking by irradiation of radiation). Since it is only necessary to switch and perform calibration using one high-definition still image, it is not necessary to detect defective pixels for each resolution. For example, when a plurality of resolutions can be selected in moving image shooting or the like, it is unrealistic to detect each defective pixel, but if this exemplary embodiment is applied, only defective pixel detection is performed once. Therefore, it is possible to easily generate a defective pixel map having a plurality of resolutions.

In addition, the radiation panel unit 20 according to this exemplary embodiment requires a smaller number of drivers to be used in low-resolution imaging than in high-resolution imaging, and is expected to reduce power consumption. When performing an operation or the like, switching to low-resolution imaging with a small number of drivers may be used to obtain a power consumption reduction effect. Also, when detecting the start of radiation detection, the power consumption may be reduced by switching to low-resolution imaging. In addition, when reset operation is performed after switching to low-resolution imaging, the time required to complete the reset of the entire imaging area can be shortened compared to high-resolution imaging, and detection of the start of radiation irradiation is detected. The period from the start to the charge accumulation mode can be shortened.

Further, the processing shown in each flowchart in the above exemplary embodiment may be stored and distributed as various programs in various storage media.
Further, the configuration of the radiation detector 26 is not limited to the above-described exemplary embodiment, and a configuration described in JP 2009-267326 A may be used. For example, the photoelectric conversion film 86 may be made of a-Si. Further, the insulating

substrates

93 and 122 may be glass substrates.

In the exemplary embodiment, the case where X-rays are detected as radiation to be detected has been described. However, the present invention is not limited to this. For example, the radiation to be detected may be visible light, ultraviolet rays, infrared ray α, γ ray, or the like.

In addition, the configuration of the radiographic image capturing system, the configuration of the radiographic image capturing apparatus, and the like described in the above exemplary embodiment are merely examples, and can be appropriately changed without departing from the gist of the present invention.

The entire disclosure of Japanese application 2012-123628 is incorporated herein by reference.

All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

A radiation detector provided with a plurality of pixels including a sensor unit that generates electric charge according to irradiated radiation, and a switching element that reads out the electric charge generated by the sensor unit and outputs the electric charge;
Generating means for detecting a defect of a pixel used in photographing at a predetermined high resolution in the radiation detector and generating a high resolution defective pixel map;
Conversion means for converting the high resolution defective pixel map generated by the generation means into a low resolution defective pixel map having a resolution lower than the high resolution;
A radiographic imaging apparatus comprising:
The radiation detector is
A sensor unit that generates a charge corresponding to the irradiated radiation; a first switching element that reads the charge from the sensor unit and outputs the charge; and a first switching element that reads the charge from the sensor unit and outputs the charge. A plurality of pixels each having two switching elements as the switching elements and arranged two-dimensionally;
A plurality of first control wirings connected to control ends of the first switching elements of a plurality of pixels adjacent in the first direction;
A plurality of second control wirings connected to control ends of the second switching elements of a plurality of pixels adjacent in the first direction;
A signal wiring is provided for each arrangement along a second direction different from the first direction of the pixels, and the output ends of the first switching elements of a plurality of pixels adjacent to the second direction are connected for each signal wiring. The output ends of the second switching elements of a plurality of pixels adjacent in the second direction and the output ends of the second switching elements of the plurality of pixels adjacent in the first direction are part of the signal. A group of signal wires connected to the wires;
The radiographic imaging apparatus of Claim 1 provided with.
The radiographic imaging device according to claim 1 or 2, wherein the high-resolution defective pixel map and the low-resolution defective pixel map are defined according to a type of defective pixel.
4. The radiographic image capturing apparatus according to claim 1, wherein the high resolution defective pixel map and the low resolution defective pixel map are defined according to a cause of the defective pixel.
The radiographic image capturing apparatus according to any one of claims 1 to 4, further comprising correction means for correcting defective pixels based on the high resolution defective pixel map or the low resolution defective pixel map.
The correcting means adjusts the gain according to the number of defective pixels of the high resolution pixels included in the low resolution pixels that are the defective pixels of the low resolution defective pixel map at the time of low resolution imaging. The radiographic imaging apparatus of Claim 5 which correct | amends.
The radiographic imaging apparatus according to any one of claims 1 to 6, wherein the switching element is configured to have the same orientation and size for each pixel.
A radiographic imaging apparatus according to any one of claims 1 to 7,
Radiation irradiating means for irradiating the radiation detector through the subject with radiation;
Radiographic imaging system equipped with.
Used for high-definition radiography in a radiation detector provided with a plurality of pixels including a sensor unit that generates electric charge according to the irradiated radiation and a switching element that reads out electric charge generated by the sensor unit. A generation step of detecting a defect in the pixel and generating a high-resolution defect pixel map;
Converting the high resolution defective pixel map generated in the generating step into a low resolution defective pixel map having a resolution lower than the high resolution;
A radiographic imaging method comprising:
The radiation detector is
A sensor unit that generates a charge corresponding to the irradiated radiation; a first switching element that reads the charge from the sensor unit and outputs the charge; and a first switching element that reads the charge from the sensor unit and outputs the charge. A plurality of pixels each having two switching elements as the switching elements and arranged two-dimensionally;
A plurality of first control wirings connected to control ends of the first switching elements of a plurality of pixels adjacent in the first direction;
A plurality of second control wirings connected to control ends of the second switching elements of a plurality of pixels adjacent in the first direction;
A signal wiring is provided for each arrangement along a second direction different from the first direction of the pixels, and the output ends of the first switching elements of a plurality of pixels adjacent to the second direction are connected for each signal wiring. The output ends of the second switching elements of a plurality of pixels adjacent in the second direction and the output ends of the second switching elements of the plurality of pixels adjacent in the first direction are part of the signal. A group of signal wires connected to the wires;
The radiographic imaging method of Claim 9.
The radiographic image capturing method according to claim 9 or 10, wherein the high-resolution defective pixel map and the low-resolution defective pixel map are defined according to a type of defective pixel.
12. The radiographic image capturing method according to claim 9, wherein the high resolution defective pixel map and the low resolution defective pixel map are defined according to a cause of the defective pixel.
13. The radiographic image capturing method according to claim 9, further comprising a correcting step of correcting a defective pixel based on the high resolution defective pixel map or the low resolution defective pixel map.
In the correction step, the defective pixel is adjusted by adjusting the gain according to the number of defective pixels of the high resolution pixel included in the low resolution pixel which is the defective pixel of the low resolution defective pixel map at the time of low resolution photographing. The radiographic imaging method according to claim 13, wherein the correction is performed.
A radiographic imaging program for causing a computer to function as each means of the radiographic imaging apparatus according to any one of claims 1 to 7.