JP2013066602A - Radiographic imaging system, radiographic imaging apparatus, radiographic imaging method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic imaging system, radiographic imaging apparatus, radiographic imaging method and program, which can detect the start of radiation irradiation in a short time while suppressing exposure dose to a subject.SOLUTION: On the basis of a synthesized signal of an electric signal obtained by a plurality of radiation detection pixels 32A corresponding to a nonexistence area (directly irradiated area) of the subject, the start of the radiation irradiation is detected and the nonexistence area is also detected without irradiating the subject with radiation.

Description

  The present invention relates to a radiographic image capturing system, a radiographic image capturing device, a radiographic image capturing method, and a program, and in particular, a radiographic image capturing system, a radiographic image capturing device, and a radiographic image for capturing a radiographic image indicated by radiation transmitted through a subject. The present invention relates to a photographing method and a program.

  In recent years, radiation detectors such as flat panel detectors (FPDs) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation directly into digital data have been put into practical use. A radiographic image capturing apparatus that captures a radiographic image represented by irradiated radiation has been put into practical use. The radiation detector used in this radiographic imaging apparatus has an indirect conversion system in which radiation is converted into light by a scintillator and then converted into electric charge in a semiconductor layer such as a photodiode, or the like. There is a direct conversion method in which a semiconductor layer such as amorphous selenium converts into electric charge, and there are various materials that can be used for the semiconductor layer in each method.

  By the way, in this type of radiographic imaging apparatus, the radiographic imaging apparatus, the radiation source, and the like are comprehensively controlled if the radiographic imaging apparatus itself can detect radiation start / stop, irradiation dose, and the like. Since it is not necessary to connect the imaging control device (so-called console) and the radiation source, it is preferable for simplifying the system configuration and simplifying the control by the imaging control device.

  As a technique related to a radiographic imaging apparatus capable of detecting the irradiation state of this type of radiation, Patent Document 1 discloses a conversion element that converts radiation incident from a radiation source into an electrical signal and generates a charge corresponding to the radiation dose. And a plurality of detection elements arranged in a matrix, and a plurality of charge transfers arranged for each column in the matrix arrangement Radiation that temporarily irradiates at least one detection element among the plurality of detection elements, an output circuit that temporarily holds the charge from the charge transfer line, and outputs an electrical signal corresponding to the charge Select as the first detection element for measuring the quantity, perform the conversion operation simultaneously in the conversion period of all the detection elements including the first detection element during the irradiation period of radiation In this irradiation period, the switch of the first detection element is turned on, the charge generated in the conversion element of the first detection element is accumulated in the output circuit through the charge transfer line, and is accumulated according to the irradiation period. There is disclosed a radiation image capturing apparatus having control means for controlling to periodically read out an electric signal corresponding to the electric charge.

  Note that Patent Document 1 discloses that the first detection element is selected by confirming an imaging range for a subject by irradiating weak radiation or visible light before imaging.

Republished patent WO2007 / 037211

  By the way, when detecting the start of radiation irradiation by the radiographic imaging device, the presence of the subject is the one that is detected in the non-existing region (so-called “elementary region”) where the subject does not exist in the imaging region. Since the radiation exposure amount is larger than that detected in the region, it can be detected quickly, which is preferable.

  However, radiation detectors used by radiographic imaging devices generally have shorter lifetimes and lower sensitivity as the cumulative dose of radiation increases. I want to reduce it as much as possible.

  Note that such a decrease in sensitivity due to an increase in cumulative dose is particularly noticeable when a scintillator including a columnar crystal is applied as shown in FIG. FIG. 25 is a graph showing cumulative dose-sensitivity when CsI is applied as the columnar crystal.

  Further, in the case of a radiographic imaging apparatus using an indirect conversion type radiation detector, when a CMOS sensor is used as a photoelectric conversion element, it is known that the CMOS sensor has low resistance to radiation. However, we want to reduce the radiation dose in the non-existing region as much as possible.

  However, when the radiation dose in the non-existing area is reduced for these reasons, the radiation dose used to detect the start of radiation exposure is reduced. There was a problem that it was not always possible.

  In the technique disclosed in Patent Document 1, not only the point of detecting the start of radiation irradiation using the radiation detected in the non-existing region but also the point of detecting the start of radiation irradiation. It is not described, and the above problems are powerless.

  The present invention has been made to solve the above-described problems, and is capable of detecting the start of radiation irradiation in a short time while suppressing the exposure dose to the subject, a radiation image capturing apparatus, and radiation. An object is to provide an image capturing method and a program.

  In order to achieve the above object, a radiographic image capturing system according to claim 1, a specific apparatus for identifying a non-existing region of the subject in a predetermined photographing region without irradiating the subject with radiation, and a radiation A radiation detector in which a plurality of radiation detection pixels for detecting the irradiation state of the subject and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are respectively disposed, and radiation is applied to the imaging region Detecting means for detecting that radiation irradiation has started, based on a composite signal of electrical signals obtained by a plurality of the radiation detection pixels corresponding to the specified non-existing region A radiographic image capturing apparatus including a control unit that controls a radiographic image capturing operation by the radiation detector based on a detection result by the detection unit; That.

  According to the radiographic image capturing system of the first aspect, the specifying device specifies the non-existing region of the subject in the predetermined capturing region without irradiating the subject with radiation.

  Here, in the present invention, a plurality of radiation detection pixels for detecting a radiation irradiation state and a radiation image of the subject are detected in a state where radiation is irradiated on the imaging region by the detection unit of the radiation image capturing apparatus. Based on a composite signal of electrical signals obtained by a plurality of the radiation detection pixels corresponding to the specified non-existing region of a radiation detector in which a plurality of radiation image acquisition pixels for imaging are respectively arranged Then, it is detected that the irradiation of the radiation is started.

  And in this invention, the imaging | photography operation | movement of the radiographic image by the said radiation detector is controlled by the control means of a radiographic imaging apparatus based on the detection result by the said detection means.

  That is, in the present invention, the start of radiation irradiation is detected based on a composite signal of electrical signals obtained by a plurality of radiation detection pixels corresponding to a non-existing region, and thereby non-existing Compared with the case where the start of radiation irradiation is detected only by an electrical signal obtained by a single radiation detection pixel corresponding to the region, detection can be performed in a shorter time, and thus the exposure dose to the subject is suppressed. To be able to.

  In the present invention, the non-existing region is specified without irradiating the subject with radiation, and the exposure amount to the subject can also be suppressed by this.

  Thus, according to the radiographic imaging system of claim 1, radiation irradiation starts based on the combined signal of the electrical signals obtained by the plurality of radiation detection pixels corresponding to the non-existing region of the subject. Since the non-existing area is detected without irradiating the subject with radiation, the start of radiation irradiation can be detected in a short time while suppressing the exposure amount to the subject. .

  In the present invention, as in the invention described in claim 2, the light receiving region of the irradiated light in a state where the specific device irradiates the imaging region with at least one of visible light, ultraviolet light, and infrared light. The non-existing area may be specified based on Thereby, a non-existing area can be specified without irradiating a subject with radiation.

  In particular, in the invention described in claim 2, as in the invention described in claim 3, the specifying device may specify the non-existing region using a solar cell array. Thereby, a non-existing area | region can be pinpointed simply and at low cost.

  By the way, when the radiation dose is detected, the dose is a cumulative value. Therefore, when an electrical signal obtained by the radiation detection pixel corresponding to the non-existing region is used, the cumulative value may be increased depending on the imaging conditions. There is a problem that the irradiated dose is saturated when the dose exceeds an assumed upper limit, and the dose of radiation cannot be detected in some cases.

  That is, for example, as shown in FIG. 26A as an example, when the accumulated irradiation amount does not saturate until the irradiation of radiation is completed, the end of irradiation can be accurately detected. As shown in FIG. 26B, when the accumulated irradiation amount is saturated before the irradiation of radiation is completed, the end of irradiation of radiation cannot be detected.

  Therefore, according to the present invention, as in the invention according to claim 4, the specifying device further specifies the region where the subject exists in the imaging region without irradiating the subject with radiation, and the detection unit includes: The radiation dose may be further detected based on an electrical signal obtained by the radiation detection pixel corresponding to the specified existence area in a state where the imaging area is irradiated with radiation. As a result, the radiation dose can be detected using the radiation whose dose has been reduced by passing through the subject, and as a result, the radiation dose can be detected more reliably.

  According to a fourth aspect of the present invention, as in the fifth aspect of the present invention, the detection means generates a combined signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the existence region. Based on this, the radiation dose may be detected. This makes it possible to detect the radiation dose more reliably as compared to the case where the radiation dose is excessively reduced by passing through the subject and the radiation dose is detected.

  Further, according to the present invention, as in the sixth aspect of the present invention, even if the radiation detection pixels are arranged in the imaging region such that the density is higher in a region where the frequency of becoming the non-existing region is higher. Good. Thereby, the irradiation start of radiation can be detected in a shorter time and more reliably.

  In particular, in the invention described in claim 6, as in the invention described in claim 7, the region that is frequently used as the non-existing region may be a partial region including a peripheral portion of the imaging region. Good. As a result, almost all subjects can be handled.

  Further, in the invention according to claim 6 or claim 7, as in the invention according to claim 8, the plurality of radiation detection pixels are stepwise or continuous as the region where the non-existing region becomes more frequent. In particular, it may be arranged in the imaging area so as to increase the density.

  In the present invention, as in the invention according to claim 9, the plurality of radiation detection pixels may be arranged between the plurality of radiation image acquisition pixels. Thereby, since the radiation detection pixel and the radiation image acquisition pixel can be configured by the same manufacturing process, the manufacturing cost can be reduced.

  Further, according to the present invention, as in the invention described in claim 10, the radiographic imaging device includes an amplifier that amplifies an electrical signal obtained by the radiation detection pixel at a preset amplification factor, and the identification An amplification factor setting means for setting the amplification factor of the amplifier based on a specific result by the apparatus may be further provided. Thereby, the irradiation state of radiation can be detected more easily and reliably.

  Particularly, in the invention described in claim 10, as in the invention described in claim 11, the amplification factor setting means amplifies the electrical signal obtained by the radiation detection pixel corresponding to the non-existing region. The amplification factor of the amplifier may be set to be higher than that of the amplifier that amplifies the electric signal obtained by the radiation detection pixel corresponding to the existence region. Thereby, the start of radiation irradiation can be detected in a shorter time.

  Further, according to the present invention, as in the invention described in claim 12, the radiographic imaging device has a low-pass frequency set in advance for a signal indicated by charges accumulated by the radiation detection pixels. You may further provide the low-pass filter which performs a low-pass process, and the frequency setting means which sets the said low-pass frequency of the said low-pass filter based on the specific result by the said specific apparatus. Thereby, the start of radiation irradiation can be detected more easily and reliably.

  In particular, in the invention described in claim 12, as in the invention described in claim 13, the frequency setting means has a low frequency range for a signal obtained by the radiation detection pixel corresponding to the non-existing area. The low pass frequency of the low pass filter that performs the pass processing is set to be higher than that of the low pass filter that performs the low pass processing on the signal obtained by the radiation detection pixel corresponding to the existence region. May be. Thereby, the start of radiation irradiation can be detected more accurately.

  On the other hand, in order to achieve the above object, the radiographic imaging device according to claim 14 includes a specifying unit that specifies a non-existing region of the subject in a predetermined imaging region without irradiating the subject with radiation. A radiation detector in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are disposed; and the imaging region is irradiated with radiation. Detection means for detecting that irradiation of the radiation is started based on a composite signal of electrical signals obtained by the plurality of pixels for radiation detection corresponding to the specified non-existing region Control means for controlling a radiographic image capturing operation by the radiation detector based on a detection result by the detection means.

  Therefore, according to the radiographic imaging apparatus of the fourteenth aspect, since it operates in the same manner as the first aspect of the invention, the radiation dose can be reduced in a short time while suppressing the exposure to the subject as in the case of the present invention. The start of irradiation can be detected.

  In order to achieve the above object, the radiographic image capturing method according to claim 15 includes a specifying step of specifying a non-existing region of the subject in a predetermined capturing region without irradiating the subject with radiation. Radiation in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are arranged in a state where radiation is irradiated on the imaging region A detection step of detecting the start of irradiation of the radiation based on a combined signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the specified non-existing region of the detector; And a control step of controlling a radiographic image capturing operation by the radiation detector based on a detection result of the detection step.

  Therefore, according to the radiographic image capturing method of the fifteenth aspect, since it operates in the same manner as the invention of the first aspect, the radiation dose can be reduced in a short time while suppressing the exposure dose to the subject as in the case of the present invention. The start of irradiation can be detected.

  Furthermore, in order to achieve the above object, the program according to claim 16 includes a specifying unit that specifies a non-existing area of the subject in a predetermined imaging area without irradiating the subject with radiation. Radiation in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are arranged in a state where radiation is irradiated on the imaging region Detecting means for detecting that irradiation of the radiation is started based on a combined signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the specified non-existing region of the detector; And a control means for controlling a radiographic image capturing operation by the radiation detector based on a detection result by the detection means. .

  Therefore, according to the program of the sixteenth aspect, since it operates in the same manner as the first aspect of the invention, it is possible to start radiation irradiation in a short time while suppressing the exposure dose to the subject as in the case of the present invention. Can be detected.

  According to the present invention, it is detected that radiation irradiation has started based on a combined signal of electrical signals obtained by a plurality of radiation detection pixels corresponding to a non-existing area of a subject, and the non-existing area Is detected without irradiating the subject without irradiating the subject, so that it is possible to detect the start of radiation irradiation in a short time while suppressing the exposure amount to the subject.

It is a block diagram which shows the structure of the radiation information system which concerns on embodiment. It is a side view which shows an example of the arrangement | positioning state of each apparatus in the radiography room of the radiographic imaging system which concerns on embodiment. It is a cross-sectional schematic diagram which shows schematic structure of the 3 pixel part of the radiation detector which concerns on embodiment. It is the cross-sectional side view which showed schematically the structure of the signal output part of 1 pixel part of the radiation detector which concerns on embodiment. It is a top view which shows the structure of the radiation detector which concerns on embodiment. It is a top view which shows the arrangement | positioning state of the pixel for radiation detection which concerns on embodiment. It is a perspective view which shows the structure of the electronic cassette concerning embodiment. It is a section side view showing the composition of the electronic cassette concerning an embodiment. It is a top view with which it uses for description of the structure of the solar cell array which concerns on embodiment, and the identification method of a presence area | region and a non-existence area | region. It is a graph with which it uses for description of the identification method of the presence area | region and non-existence area | region by the solar cell array which concerns on embodiment. It is a top view which shows the structure of the solar cell array which concerns on embodiment. It is a graph with which it uses for description of the identification method of the presence area | region and non-existence area | region by the solar cell array which concerns on embodiment. It is a block diagram which shows the principal part structure of the electrical system of the radiographic imaging system which concerns on embodiment. It is a circuit diagram which shows the structure of the 2nd signal processing part which concerns on embodiment. It is a flowchart which shows the flow of a process of the radiographic imaging processing program which concerns on embodiment. It is the schematic which shows an example of the initial stage information input screen which concerns on embodiment. It is a flowchart which shows the flow of a process of the cassette imaging | photography processing program which concerns on embodiment. It is a cross-sectional side view for demonstrating the surface reading system and back surface scanning system of a radiographic image. It is a graph which shows an example of a sensitivity wavelength range at the time of applying a quinacridone type organic compound as an organic photoelectric conversion material. It is a top view which shows the other example of an arrangement | positioning state of the pixel for a radiation detection which concerns on embodiment. It is a top view which shows the other example of a form of the electronic cassette concerning embodiment. It is a top view which shows the other example of a form of the electronic cassette concerning embodiment. It is a top view which shows the other example of a form of the radiation detector which concerns on embodiment. It is a top view which shows the other example of an arrangement | positioning state of the pixel for a radiation detection which concerns on embodiment. It is a graph with which it uses for description of the problem of a prior art. It is a graph with which it uses for description of the problem of a prior art.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Here, a description will be given of an example in which the present invention is applied to a radiation information system that is a system for comprehensively managing information handled in a radiology department in a hospital.

  First, the configuration of a radiation information system (hereinafter referred to as “RIS” (Radiology Information System)) 100 according to the present embodiment will be described with reference to FIG.

  The RIS 100 is a system for managing information such as medical appointments and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)).

  The RIS 100 includes a plurality of radiography requesting terminal devices (hereinafter referred to as “terminal devices”) 140, a RIS server 150, and a radiographic imaging system (hereinafter referred to as a radiographic imaging room (or operating room) in a hospital). , Which are referred to as “imaging systems”) 104, which are connected to a hospital network 102 composed of a wired or wireless LAN (Local Area Network) or the like. The RIS 100 constitutes a part of the HIS provided in the same hospital, and an HIS server (not shown) for managing the entire HIS is also connected to the in-hospital network 102.

  The terminal device 140 is used by doctors and radiographers to input and browse diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are also performed via the terminal device 140. Each terminal device 140 includes a personal computer having a display device, and can communicate with the RIS server 150 via the hospital network 102.

  On the other hand, the RIS server 150 receives an imaging request from each terminal device 140 and manages a radiographic imaging schedule in the imaging system 104, and includes a database 150A.

  Database 150A includes patient (subject) attribute information (name, sex, date of birth, age, blood type, weight, patient ID (Identification), etc.), medical history, medical history, radiation images taken in the past, etc. Information regarding the patient, information regarding the electronic cassette 40 used in the imaging system 104, such as an identification number (ID information), model, size, sensitivity, start date of use, number of times of use, etc., and the electronic cassette 40 It includes the environment information which shows the environment which takes a radiographic image using, ie, the environment (for example, a radiography room, an operating room, etc.) which uses electronic cassette 40.

  The imaging system 104 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 150. The imaging system 104 irradiates the subject with radiation X (see also FIG. 7) having a dose according to the exposure conditions from the radiation source 121 (see also FIG. 13), while the subject of the radiation X is examined. Prior to irradiation of the person, the radiation generator 120 that emits visible light for positioning the subject to the irradiation field of the radiation X from the light source 125 (see also FIG. 13), and the light receiving state of the visible light And a solar cell array 168 for detecting the presence area and non-existence area (elementary area) of the subject in the radiographic image capturing area. In addition, the imaging system 104 absorbs the radiation X that has passed through the imaging target region of the subject, generates charges, and generates a radiation detector 20 (FIG. 5) that generates image information indicating a radiation image based on the generated charge amount. 7), a cradle 130 for charging a battery built in the electronic cassette 40, and a console 110 for controlling the electronic cassette 40 and the radiation generator 120.

  The console 110 acquires various types of information included in the database 150A from the RIS server 150, stores them in an HDD 116 (see FIG. 13) described later, and uses the information as necessary to use the electronic cassette 40 and the radiation generator 120. Control.

  FIG. 2 shows an example of the arrangement state of each device in the radiation imaging room 180 of the imaging system 104 according to the present embodiment.

  As shown in the figure, the radiation imaging room 180 has a standing table 160 used when performing radiography in a standing position and a prone table 164 used when performing radiography in a lying position. The space in front of the standing stand 160 is set as a photographing position 170 of the subject when performing radiography in the standing position, and the space above the supine stand 164 is when performing radiography in the prone position. The imaging position 172 of the subject.

  The standing stand 160 is provided with a holding unit 162 that holds the electronic cassette 40, and the electronic cassette 40 is held by the holding unit 162 when a radiographic image is taken in the standing position. Similarly, the holding table 164 is provided with a holding unit 166 that holds the electronic cassette 40, and the electronic cassette 40 is held by the holding unit 166 when a radiographic image is taken in the lying position.

  Further, solar cell arrays 168 are provided on the radiation incident sides of the holding unit 162 and the holding unit 166, respectively. In the imaging system 104 according to the present embodiment, the solar cell array 168 is fixedly provided to each holding unit. However, the present invention is not limited thereto, and the solar cell array 168 can be attached to and detached from each holding unit. The solar cell array 168 may be attached to the holding portion as necessary, and the solar cell array 168 may be arranged at an arbitrary position regardless of each holding portion.

  Further, in the radiation imaging room 180, the radiation source 121 and the light source 125 are arranged on a horizontal axis in order to enable radiation imaging in a standing position and radiation imaging in a lying position by radiation from a single radiation source 121. A support moving mechanism that can rotate around (in the direction of arrow a in FIG. 2), move in the vertical direction (in the direction of arrow b in FIG. 2), and further move in the horizontal direction (in the direction of arrow c in FIG. 2). 124 is provided. Here, the support moving mechanism 124 includes a drive source that rotates the radiation source 121 and the light source 125 around a horizontal axis, a drive source that moves the radiation source 121 and the light source 125 in the vertical direction, and the radiation source 121 and the light source 125. Are respectively provided with a drive source (not shown).

  On the other hand, the cradle 130 is formed with an accommodating portion 130 </ b> A capable of accommodating the electronic cassette 40.

  When the electronic cassette 40 is not in use, the built-in battery is charged in a state of being housed in the housing portion 130A of the cradle 130. When a radiographic image is taken, the electronic cassette 40 is taken out from the cradle 130 by a radiographer or the like, and the photographing posture is established. If it is in the upright position, it is held in the holding part 162 of the standing base 160, and if it is in the upright position, it is held in the holding part 166 of the standing base 164.

  Here, in the imaging system 104 according to the present embodiment, various types of information are transmitted and received between the radiation generation apparatus 120 and the console 110 and between the electronic cassette 40 and the console 110 by wireless communication.

  The electronic cassette 40 is not used only in a state where it is held by the holding part 162 of the standing base 160 or the holding part 166 of the prone base 164. When photographing, it can be used in a state where it is not held by the holding unit.

  Next, the configuration of the radiation detector 20 according to the present embodiment will be described. FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the radiation detector 20 according to the present exemplary embodiment.

  As shown in the figure, in the radiation detector 20 according to the present embodiment, a signal output unit 14, a sensor unit 13, and a scintillator 8 are sequentially stacked on an insulating substrate 1. The pixels are configured by the sensor unit 13. A plurality of pixels are arranged on the substrate 1, and the signal output unit 14 and the sensor unit 13 in each pixel are configured to overlap each other.

  The scintillator 8 is formed on the sensor unit 13 via the transparent insulating film 7, and forms a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 1) or from below into light. It is a thing. Providing such a scintillator 8 absorbs the radiation transmitted through the subject and emits light.

  The wavelength range of light emitted by the scintillator 8 is preferably a visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 20, the wavelength range of green is included. Is more preferable.

  Specifically, the phosphor used in the scintillator 8 is preferably one containing cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 420 nm to 700 nm upon X-ray irradiation. It is particularly preferable to use CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.

  The sensor unit 13 includes an upper electrode 6, a lower electrode 2, and a photoelectric conversion film 4 disposed between the upper and lower electrodes. The photoelectric conversion film 4 absorbs light emitted from the scintillator 8 and generates charges. It is composed of an organic photoelectric conversion material.

Since it is necessary for the upper electrode 6 to cause the light generated by the scintillator 8 to be incident on the photoelectric conversion film 4, it is preferable that the upper electrode 6 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 8. It is preferable to use a transparent conductive oxide (TCO) having a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the upper electrode 6, TCO is preferable because it tends to increase the resistance value when it is desired to obtain a transmittance of 90% or more. 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 6 may have a single configuration common to all pixels, or may be divided for each pixel.

  The photoelectric conversion film 4 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 8, and generates a charge corresponding to the absorbed light. In this way, the photoelectric conversion film 4 containing an organic photoelectric conversion material has a sharp absorption spectrum in the visible range, and electromagnetic waves other than light emitted by the scintillator 8 are hardly absorbed by the photoelectric conversion film 4. The noise generated by the radiation such as being absorbed by the photoelectric conversion film 4 can be effectively suppressed.

  The organic photoelectric conversion material constituting the photoelectric conversion film 4 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 8 in order to absorb light emitted by the scintillator 8 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 8, but if the difference between the two is small, the light emitted from the scintillator 8 can be sufficiently absorbed. . 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 scintillator 8 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone-based organic compounds and phthalocyanine-based organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 8, the difference in peak wavelength can be within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 4 can be substantially maximized.

  Next, the photoelectric conversion film 4 applicable to the radiation detector 20 according to the present embodiment will be specifically described.

  The electromagnetic wave absorption / photoelectric conversion site in the radiation detector 20 according to the present embodiment is configured by an organic layer including a pair of electrodes 2 and 6 and an organic photoelectric conversion film 4 sandwiched between the electrodes 2 and 6. be able to. More specifically, this organic layer is a part that absorbs electromagnetic waves, a photoelectric conversion part, an electron transport part, a hole transport part, an electron blocking part, a hole blocking part, a crystallization preventing part, an electrode, and an interlayer contact improvement. It can be formed by stacking or mixing parts.

  The organic layer preferably contains an organic p-type compound or an organic n-type compound.

  The organic p-type semiconductor (compound) is a donor organic semiconductor (compound) mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Accordingly, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound.

  An organic n-type semiconductor (compound) is an acceptor organic semiconductor (compound) mainly represented by an electron-transporting organic compound and refers to an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Accordingly, as the acceptor organic compound, any organic compound can be used as long as it is an electron-accepting organic compound.

  The materials applicable as the organic p-type semiconductor and organic n-type semiconductor and the configuration of the photoelectric conversion film 4 are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, and thus the description thereof is omitted. The photoelectric conversion film 4 may be formed by further containing fullerenes or carbon nanotubes.

  The thickness of the photoelectric conversion film 4 is preferably as large as possible in terms of absorbing light from the scintillator 8. However, when the thickness is more than a certain level, the photoelectric conversion film 4 is generated in the photoelectric conversion film 4 by a bias voltage applied from both ends of the photoelectric conversion film 4. Since electric field strength is reduced and charges cannot be collected, the thickness is preferably 30 nm to 300 nm, more preferably 50 nm to 250 nm, and particularly preferably 80 nm to 200 nm.

  In the radiation detector 20 shown in FIG. 3, the photoelectric conversion film 4 has a single configuration common to all pixels, but may be divided for each pixel.

  The lower electrode 2 is a thin film divided for each pixel. The lower electrode 2 can be made of a transparent or opaque conductive material, and aluminum, silver, or the like can be suitably used.

  The thickness of the lower electrode 2 can be, for example, 30 nm or more and 300 nm or less.

  In the sensor unit 13, by applying a predetermined bias voltage between the upper electrode 6 and the lower electrode 2, one of electric charges (holes, electrons) generated in the photoelectric conversion film 4 is moved to the upper electrode 6. The other can be moved to the lower electrode 2. In the radiation detector 20 of the present embodiment, a wiring is connected to the upper electrode 6, and a bias voltage is applied to the upper electrode 6 through this wiring. In addition, the polarity of the bias voltage is determined so that electrons generated in the photoelectric conversion film 4 move to the upper electrode 6 and holes move to the lower electrode 2, but this polarity is reversed. May be.

  The sensor unit 13 constituting each pixel only needs to include at least the lower electrode 2, the photoelectric conversion film 4, and the upper electrode 6. In order to suppress an increase in dark current, the electron blocking film 3 and the hole blocking film are used. 5 is preferably provided, and it is more preferable to provide both.

  The electron blocking film 3 can be provided between the lower electrode 2 and the photoelectric conversion film 4. When a bias voltage is applied between the lower electrode 2 and the upper electrode 6, electrons are transferred from the lower electrode 2 to the photoelectric conversion film 4. 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 3.

  The material actually used for the electron blocking film 3 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 4 and the like, and 1.3 eV or more from the work function (Wf) of the material of the adjacent electrode. Those having a large electron affinity (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 4 are preferable. The material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, and thus the description thereof is omitted.

  The thickness of the electron blocking film 3 is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 13. It is 50 nm or more and 100 nm or less.

  The hole blocking film 5 can be provided between the photoelectric conversion film 4 and the upper electrode 6. When a bias voltage is applied between the lower electrode 2 and the upper electrode 6, the hole blocking film 5 is transferred from the upper electrode 6 to the photoelectric conversion film 4. It is possible to suppress the increase in dark current due to the injection of holes.

  An electron-accepting organic material can be used for the hole blocking film 5.

  The thickness of the hole blocking film 5 is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably, in order to surely exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the sensor unit 13. Is from 50 nm to 100 nm.

  The material actually used for the hole blocking film 5 may be selected according to the material of the adjacent electrode, the material of the adjacent photoelectric conversion film 4 and the like, and 1.3 eV from the work function (Wf) of the material of the adjacent electrode. As described above, it is preferable that the ionization potential (Ip) is large and that the Ea is equal to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 4. Since the material applicable as the electron-accepting organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  In addition, when a bias voltage is set so that holes move to the upper electrode 6 and electrons move to the lower electrode 2 among the charges generated in the photoelectric conversion film 4, the electron blocking film 3 and the hole blocking are set. The position of the film 5 may be reversed. Moreover, it is not necessary to provide both the electron blocking film 3 and the hole blocking film 5. If either one is provided, a certain degree of dark current suppressing effect can be obtained.

  A signal output unit 14 is formed on the surface of the substrate 1 below the lower electrode 2 of each pixel. FIG. 4 schematically shows the configuration of the signal output unit 14.

  As shown in the figure, the signal output unit 14 according to the present embodiment corresponds to the lower electrode 2, and a capacitor 9 that accumulates the charges transferred to the lower electrode 2, and the electric charges accumulated in the capacitor 9 are electrically A field effect thin film transistor (Thin Film Transistor, hereinafter simply referred to as a thin film transistor) 10 that converts the signal into a signal and outputs the signal is formed. The region in which the capacitor 9 and the thin film transistor 10 are formed has a portion that overlaps the lower electrode 2 in a plan view. With this configuration, the signal output unit 14 and the sensor unit 13 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 20 (pixel), it is desirable that the region where the capacitor 9 and the thin film transistor 10 are formed is completely covered by the lower electrode 2.

  The capacitor 9 is electrically connected to the corresponding lower electrode 2 through a wiring made of a conductive material penetrating an insulating film 11 provided between the substrate 1 and the lower electrode 2. Thereby, the electric charge collected by the lower electrode 2 can be moved to the capacitor 9.

  In the thin film transistor 10, a gate electrode 15, a gate insulating film 16, and an active layer (channel layer) 17 are stacked, and a source electrode 18 and a drain electrode 19 are formed on the active layer 17 at a predetermined interval. .

  The active layer 17 can be formed of, for example, amorphous silicon, amorphous oxide, organic semiconductor material, carbon nanotube, or the like. In addition, the material which comprises the active layer 17 is not limited to these.

The amorphous oxide constituting the active layer 17 is preferably an oxide containing at least one of In, Ga, and Zn (for example, In—O-based), and at least two of In, Ga, and Zn. An oxide containing In (eg, In—Zn—O, In—Ga—O, or Ga—Zn—O) is more preferable, and an oxide containing In, Ga, and Zn is particularly preferable. As the In—Ga—Zn—O-based amorphous oxide, an amorphous oxide whose composition in a crystalline state is represented by InGaO ₃ (ZnO) m (m is a natural number of less than 6) is preferable, and InGaZnO is particularly preferable. ₄ is more preferable.

  Examples of the organic semiconductor material that can form the active layer 17 include, but are not limited to, phthalocyanine compounds, pentacene, vanadyl phthalocyanine, and the like. In addition, about the structure of a phthalocyanine compound, since it is demonstrated in detail in Unexamined-Japanese-Patent No. 2009-212389, description is abbreviate | omitted.

  If the active layer 17 of the thin film transistor 10 is formed of an amorphous oxide, an organic semiconductor material, or a carbon nanotube, it will not absorb radiation such as X-rays, or even if it absorbs it, it will remain in a very small amount. Generation of noise in the portion 14 can be effectively suppressed.

  When the active layer 17 is formed of carbon nanotubes, the switching speed of the thin film transistor 10 can be increased, and the thin film transistor 10 having a low light absorption in the visible light region can be formed. In addition, when the active layer 17 is formed of carbon nanotubes, the performance of the thin film transistor 10 is remarkably deteriorated only by mixing a very small amount of metallic impurities into the active layer 17, so that extremely high purity carbon nanotubes can be obtained by centrifugation or the like. It is necessary to form by separating and extracting.

  Here, any of the amorphous oxides, organic semiconductor materials, carbon nanotubes constituting the active layer 17 of the thin film transistor 10 and organic photoelectric conversion materials constituting the photoelectric conversion film 4 can be formed at a low temperature. . Therefore, the substrate 1 is not limited to a substrate having high heat resistance such as a semiconductor substrate, a quartz substrate, and a glass substrate, and a flexible substrate such as plastic, aramid, or bionanofiber can also be used. Specifically, flexible materials such as polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene). A conductive substrate can be used. If such a plastic flexible substrate is used, it is possible to reduce the weight, which is advantageous for carrying around, for example.

  In addition, the substrate 1 is provided with an insulating layer for ensuring insulation, a gas barrier layer for preventing permeation of moisture and oxygen, an undercoat layer for improving flatness or adhesion to electrodes, and the like. May be.

  On the other hand, since aramid can be applied at a high temperature process of 200 ° C. or more, the transparent electrode material can be cured at a high temperature to reduce its resistance, and it can be used for automatic mounting of a driver IC including a solder reflow process. Moreover, since aramid has a thermal expansion coefficient close to that of ITO (Indium Tin Oxide) or a glass substrate, there is little warping after manufacturing and it is difficult to crack. In addition, aramid can form a substrate thinner than a glass substrate or the like. The substrate may be formed by laminating an ultrathin glass substrate and aramid.

  The bionanofiber is a composite of a cellulose microfibril bundle (bacterial cellulose) produced by bacteria (Acetobacter Xylinum) and a transparent resin. The cellulose microfibril bundle has a width of 50 nm and a size of 1/10 of the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. By impregnating and curing a transparent resin such as an acrylic resin or an epoxy resin in bacterial cellulose, a bio-nanofiber having a light transmittance of about 90% at a wavelength of 500 nm can be obtained while containing 60 to 70% of the fiber. Bionanofiber has a low coefficient of thermal expansion (3-7ppm) comparable to silicon crystals, and is as strong as steel (460MPa), highly elastic (30GPa), and flexible, compared to glass substrates, etc. The substrate 1 can be formed thinly.

  In the present embodiment, the TFT substrate 30 is formed on the substrate 1 by sequentially forming the signal output unit 14, the sensor unit 13, and the transparent insulating film 7, and the light-absorbing adhesive resin is formed on the TFT substrate 30. The radiation detector 20 is formed by pasting the scintillator 8 using, for example.

  As shown in FIG. 5, the TFT substrate 30 includes a pixel 32 including the sensor unit 13, the capacitor 9, and the thin film transistor 10 described above in a certain direction (row direction in FIG. 5) and crossing the certain direction. A plurality of two-dimensional shapes are provided in the direction (column direction in FIG. 5).

  Further, the radiation detector 20 extends in the predetermined direction (row direction), and extends in the intersecting direction (column direction) with a plurality of gate wirings 34 for turning on and off each thin film transistor 10. A plurality of data wirings 36 for reading out charges through the thin film transistor 10 in the on state are provided.

  The radiation detector 20 has a flat plate shape and a quadrilateral shape having four sides on the outer edge in a plan view, more specifically, a rectangular shape.

  Here, in the radiation detector 20 according to the present exemplary embodiment, a part of the pixels 32 is used to detect the irradiation state of the radiation, and a radiographic image is captured by the remaining pixels 32. Hereinafter, the pixels 32 for detecting the radiation irradiation state are referred to as radiation detection pixels 32A, and the remaining pixels 32 are referred to as radiation image acquisition pixels 32B.

  In the radiation detector 20 according to the present embodiment, the radiation image is captured by the radiation image acquisition pixel 32B excluding the radiation detection pixel 32A in the pixel 32. Therefore, the radiation image at the position where the radiation detection pixel 32A is disposed. Pixel information cannot be obtained. For this reason, in the radiation detector 20 according to the present exemplary embodiment, the radiation detection pixels 32A are arranged so as to be dispersed, while the console 110 obtains the pixel information of the radiation image at the arrangement position of the radiation detection pixels 32A. A defective pixel correction process generated by interpolation using pixel information obtained by the radiation image acquisition pixel 32B positioned around the radiation detection pixel 32A is executed.

  Further, in the radiation detector 20 according to the present exemplary embodiment, the density of the radiation detection pixels 32 </ b> A is increased in a region where the imaging target region is not arranged and the non-existing region (elementary region) is frequently used. Place in the shooting area.

  Here, in the imaging system 104 according to the present embodiment, when imaging is performed using the entire imaging region by the radiation detector 20 as in the case where the imaging target region is an abdomen or the like, or the imaging target region is a leg part. In any case where imaging is performed using only a part of the imaging region by the radiation detector 20 as in the case of an arm portion, a hand portion, or the like, at least a region to be imaged in the central portion of the imaging region It is assumed that shooting is performed in a state where is positioned. For this reason, in the radiation detector 20 according to the present exemplary embodiment, as schematically illustrated in FIG. 6 as an example, the radiation detection pixel 32 </ b> A includes a partial region including the central portion of the imaging region of the radiation detector 20 ( In this embodiment, the radiation detector 20 is arranged so that the rectangular area (centered around the center of the imaging area) 20A has a relatively low density and the surrounding area has a higher density than the area 20A.

  And in order to detect the irradiation state of a radiation, the electronic cassette 40 which concerns on this Embodiment acquires the information (henceforth "radiation dose information") which shows the irradiation amount of the radiation X from the radiation source 121. FIG. A radiation dose acquisition function is provided.

  Therefore, in the radiation detector 20 according to the present embodiment, as shown in FIG. 5, the radiation detection pixel 32A accumulated in the capacitor 9 is connected to the connection portion between the capacitor 9 and the thin film transistor 10 in the radiation detection pixel 32A. Direct readout wirings 38 for directly reading out charges are extended in the above-described fixed direction (row direction) for each of the radiation detection pixels 32A.

  Next, the configuration of the electronic cassette 40 according to the present embodiment will be described. FIG. 7 is a perspective view showing the configuration of the electronic cassette 40 according to the present exemplary embodiment.

  As shown in the figure, an electronic cassette 40 according to the present embodiment includes a housing 41 made of a material that transmits radiation, and has a waterproof and airtight structure. When the electronic cassette 40 is used in an operating room or the like, there is a risk that blood or other germs may adhere. Therefore, one electronic cassette 40 can be used repeatedly by sterilizing and cleaning the electronic cassette 40 as necessary with a waterproof and hermetic structure.

  A space A for accommodating various components is formed inside the housing 41, and the radiation X transmitted through the subject from the irradiation surface side of the housing 41 to which the radiation X is irradiated is formed in the space A. The radiation detector 20 for detecting the radiation X and the lead plate 43 for absorbing the back scattered radiation of the radiation X are arranged in this order.

  Here, in the electronic cassette 40 according to the present exemplary embodiment, the area corresponding to the arrangement position of the radiation detector 20 on one flat surface of the housing 41 is a quadrilateral imaging area 41A capable of detecting radiation. Has been. The surface having the imaging region 41A of the casing 41 is a top plate 41B in the electronic cassette 40. In the electronic cassette 40 according to the present embodiment, the radiation detector 20 is connected to the TFT substrate 30 on the top plate 41B side. The top plate 41B is affixed to the inner surface of the casing 41 (the surface on the opposite side of the surface on which the radiation of the top plate 41B is incident).

  On the other hand, as shown in FIG. 7, a cassette control unit 58 and a power supply unit 70 (both described later) are placed on one end side inside the housing 41 so as not to overlap the radiation detector 20 (outside the range of the imaging region 41A). The case 42 which accommodates FIG. 13 is arrange | positioned.

  The casing 41 is made of, for example, carbon fiber (carbon fiber), aluminum, magnesium, bionanofiber (cellulose microfibril), or a composite material in order to reduce the weight of the entire electronic cassette 40.

  As the composite material, for example, a material including a reinforced fiber resin is used, and the reinforced fiber resin includes carbon, cellulose, and the like. Specifically, as the composite material, carbon fiber reinforced plastic (CFRP), a structure in which a foamed material is sandwiched with CFRP, or a material in which the surface of the foamed material is coated with CFRP is used. In the present embodiment, a structure in which a foam material is sandwiched with CFRP is used. Thereby, compared with the case where the housing | casing 41 is comprised with a carbon single-piece | unit, the intensity | strength (rigidity) of the housing | casing 41 can be improved.

  On the other hand, as shown in FIG. 8, a support body 44 is disposed on the inner surface of the back surface portion 41 </ b> C facing the top plate 41 </ b> B inside the housing 41, and radiation between the support body 44 and the top plate 41 </ b> B. The detector 20 and the lead plate 43 are arranged in this order in the radiation X irradiation direction. The support body 44 is made of, for example, a foam material from the viewpoint of weight reduction and absorption of dimensional deviation, and supports the lead plate 43.

  As shown in the figure, an adhesive member 80 is provided on the inner surface of the top plate 41B to adhere the TFT substrate 30 of the radiation detector 20 in a peelable manner. As the adhesive member 80, for example, a double-sided tape is used. In this case, the double-sided tape is formed so that the adhesive force of one adhesive surface is stronger than the adhesive force of the other adhesive surface.

  Specifically, the weak adhesive surface (weakly adhesive surface) is set to 1.0 N / cm or less at 180 ° peel adhesive force. Then, the surface having a strong adhesive force (strong adhesion surface) is in contact with the top plate 41B, and the weak adhesion surface is in contact with the TFT substrate 30. Thereby, compared with the case where the radiation detector 20 is fixed to the top plate 41B with fixing members, such as a screw, the thickness of the electronic cassette 40 can be made thin. Even if the top plate 41B is deformed by an impact or load, the radiation detector 20 follows the deformation of the top plate 41B having high rigidity, so that only a large curvature (slow bend) is generated, and a local low curvature is generated. Therefore, the possibility that the radiation detector 20 is damaged is reduced. Furthermore, the radiation detector 20 contributes to the improvement of the rigidity of the top plate 41B.

  As described above, in the electronic cassette 40 according to the present exemplary embodiment, the radiation detector 20 is attached to the inside of the top plate 41B of the housing 41, so that the housing 41 is on the top plate 41B side and the back surface portion 41C side. When the radiation detector 20 is attached to the top plate 41B or the radiation detector 20 is peeled off from the top plate 41B, the housing 41 is placed on the top plate 41B side. And the back surface portion 41C side are separated into two.

  In the present embodiment, the radiation detector 20 may not be bonded to the top plate 41B in a clean room or the like. This is because when a foreign object such as a metal piece that absorbs radiation is mixed between the radiation detector 20 and the top plate 41B, the foreign object can be removed by peeling the radiation detector 20 from the top plate 41B.

  On the other hand, as shown in FIG. 9 as an example, solar cell array 168 according to the present embodiment is configured by arranging a plurality of solar cells 168A in a matrix, and the current value output from each solar cell 168A. Is determined to be the aforementioned non-existing area (elementary missing area), and the other solar cell 168A is specified to be the aforementioned existing area.

  In the example shown in FIG. 9, in addition to the area in contact with the outer periphery of the solar cell array 168 where the subject does not exist, the areas A, D, G, and J are identified as non-existing areas. In addition to the area in contact with the central portion of the solar cell array 168 that covers the entire area, the areas B, C, E, F, H, and I are identified as the existing areas.

  In the imaging system 104 according to the present embodiment, the light emission intensity of the light source 125 can be set in accordance with the radiographic image capturing conditions, the imaging environment, and the like. As an example, as illustrated in FIG. The threshold value is determined in advance so that the value becomes larger as the light emission intensity by.

  In the electronic cassette 40 according to the present embodiment, information indicating the relationship between the light emission intensity of the light source 125 and the threshold value as shown in FIG. 10 as an example (hereinafter referred to as “threshold information”) is stored in advance. The presence area and the non-existence area are specified using a threshold value corresponding to the emission intensity of the light source 125 to be actually applied.

  Note that the resolution of the solar cell array 168 by the solar cell 168A does not have to be as high as the pixel unit of the captured image in the electronic cassette 40, and an area where a plurality of pixels are collected is sufficient, and the area becomes wider. Sensitivity can be improved. As an example, as shown in FIG. 11, the possibility that a subject exists in the central portion of the solar cell array 168 is very high, and therefore the area of each region in the central portion is smaller than the peripheral portion. A high-definition form may be used.

  By the way, when an existing region and a non-existing region are specified using a solar cell, as shown in FIG. 12 as an example, a solar cell using amorphous silicon has sensitivity in the emission wavelength band of the fluorescent lamp. And the light from the light source 125 may be confused.

  On the other hand, in the solar cell using crystalline silicon, the wavelength band of infrared light is more dominant than the emission wavelength band of the fluorescent lamp, so it is difficult to confuse the light of the fluorescent lamp with the light from the light source 125. . For this reason, it is preferable to use a light source 125 that emits infrared light and a solar cell array 168 that includes a solar cell using crystalline silicon. When using visible light, the subject may feel dazzled, but this problem can be solved by using infrared light in this way.

  In addition, since the light source that emits visible light generally emits light in the infrared region, when a subject has a light source that emits visible light, the visible light cut filter can be inserted into and removed from the light source. It is more preferable that the light source for positioning the subject can be used as the light source for specifying the existing region and the non-existing region.

  Next, with reference to FIG. 13, the configuration of the main part of the electrical system of imaging system 104 according to the present embodiment will be described.

  As shown in the figure, the radiation detector 20 incorporated in the electronic cassette 40 has a gate line driver 52 arranged on one side of two adjacent sides and a first signal processing unit 54 arranged on the other side. Yes. Each gate wiring 34 of the TFT substrate 30 is connected to the gate line driver 52, and each data wiring 36 of the TFT substrate 30 is connected to the first signal processing unit 54.

  The housing 41 includes an image memory 56, a cassette control unit 58, and a wireless communication unit 60.

  Each thin film transistor 10 of the TFT substrate 30 is sequentially turned on in a row unit by a signal supplied from the gate line driver 52 via the gate wiring 34, and the electric charge read by the thin film transistor 10 in the on state is converted into an electric signal. The data wiring 36 is transmitted and input to the first signal processing unit 54. As a result, the charges are sequentially read out in units of rows, and a two-dimensional radiation image can be acquired.

  Although not shown, the first signal processing unit 54 includes an amplification circuit and a sample hold circuit for amplifying an input electric signal for each data wiring 36, and the individual data wiring 36 is transmitted. The electric signal is amplified by the amplifier circuit and then held in the sample hold circuit. Further, a multiplexer and an A / D (analog / digital) converter are connected in order to the output side of the sample and hold circuit, and the electric signals held in the individual sample and hold circuits are sequentially (serially) input to the multiplexer. The digital image data is converted by an A / D converter.

  An image memory 56 is connected to the first signal processing unit 54, and image data output from the A / D converter of the first signal processing unit 54 is sequentially stored in the image memory 56. The image memory 56 has a storage capacity capable of storing a predetermined number of image data, and image data obtained by imaging is sequentially stored in the image memory 56 each time a radiographic image is captured.

  The image memory 56 is connected to the cassette control unit 58. The cassette control unit 58 includes a microcomputer, and includes a CPU (Central Processing Unit) 58A, a memory 58B including a ROM (Read Only Memory) and a RAM (Random Access Memory), a nonvolatile storage unit 58C including a flash memory and the like. And controls the entire operation of the electronic cassette 40.

  Further, a wireless communication unit 60 is connected to the cassette control unit 58. The wireless communication unit 60 corresponds to a wireless local area network (LAN) standard represented by IEEE (Institute of Electrical and Electronics Engineers) 802.11a / b / g, etc. Control transmission of various information. The cassette control unit 58 can wirelessly communicate with an external device such as the console 110 that performs control related to radiographic image capturing via the wireless communication unit 60, and can transmit and receive various types of information to and from the console 110 and the like. It is possible.

  In addition, the electronic cassette 40 is provided with a connector 62 that is electrically connected to the solar cell array 168 provided in the holding portion held in the holding portion 162 or the holding portion 166. 62 is connected to the cassette control unit 58. Therefore, the cassette control unit 58 can individually grasp the current value output from each solar cell 168A of the solar cell array 168 provided in the held holding unit.

  In addition, the electronic cassette 40 is provided with a power supply unit 70, and the various circuits and elements described above (gate line driver 52, first signal processing unit 54, image memory 56, wireless communication unit 60, cassette control unit 58). A functioning microcomputer or the like is operated by electric power supplied from the power supply unit 70. The power supply unit 70 incorporates a battery (a rechargeable secondary battery) so as not to impair the portability of the electronic cassette 40, and supplies power from the charged battery to various circuits and elements. In FIG. 13, the power supply unit 70, various circuits, and wirings for connecting each element are omitted.

  On the other hand, in the radiation detector 20 according to the present embodiment, the second signal processing unit 55 is arranged on the opposite side of the gate line driver 52 across the TFT substrate 30 in order to realize the radiation dose acquisition function described above. The individual direct readout wirings 38 of the TFT substrate 30 are connected to the second signal processing unit 55.

  Here, the configuration of the second signal processing unit 55 according to the present embodiment will be described. FIG. 14 is a circuit diagram showing a configuration of the second signal processing unit 55 according to the present embodiment.

  As shown in the figure, the second signal processing unit 55 according to the present embodiment can switch between a variable gain preamplifier (charge amplifier) 92 and a low-pass frequency corresponding to each of the direct readout wirings 38. An LPF (low pass filter) 96, and a sample hold circuit 97 in which the sample timing can be set are provided.

  The variable gain preamplifier 92 includes an operational amplifier 92A whose positive input side is grounded, a capacitor 92B, a switch 92E, a capacitor 92C, and a reset switch 92F that are connected in parallel between the negative input side and the output side of the operational amplifier 92A. The switch 92E and the reset switch 92F are switched by the cassette control unit 58.

  The LPF 96 includes a resistor 96A, a resistor 96B, a capacitor 96C, and a switch 96E that short-circuits the resistor 96A. The switch 96E is also switched by the cassette control unit 58. Furthermore, the sample control of the sample hold circuit 97 is also switched by the cassette control unit 58.

  On the other hand, each of the second signal processing units 55 according to the present embodiment includes a single multiplexer 98 and an A / D (analog / digital) converter 99. The selection output by the switch 98A provided in the multiplexer 98 is also switched by the cassette control unit 58.

  Each of the direct readout wirings 38 is connected to an input terminal of the corresponding variable gain preamplifier 92 (a negative input terminal of the operational amplifier 92A), and an output terminal of the variable gain preamplifier 92 is connected to an input terminal of the corresponding LPF 96. The output terminal is connected to the input terminal of the corresponding sample and hold circuit 97.

  Each output terminal of the sample hold circuit 97 is connected to the switch 98A of the multiplexer 98 on a one-to-one basis, and the output terminal of the switch 98A of the multiplexer 98 is connected to the cassette control unit 58. Is connected to the input terminal.

  When the radiation dose acquisition function is activated, the cassette control unit 58 first discharges the charges accumulated in the capacitor 92B and the capacitor 92C by turning on the switch 92E and the reset switch 92F of the variable gain preamplifier 92. .

  Next, the cassette control unit 58 sets the amplification factor by the variable gain preamplifier 92 by setting the switch 92E on / off after the reset switch 92F of the variable gain preamplifier 92 is turned off, and at the same time the switch 96E of the LPF 96 The low pass frequency by the LPF 96 is set by setting the on / off state.

  On the other hand, the electric charge accumulated in each capacitor 9 of the radiation detection pixel 32A by being irradiated with the radiation X is transmitted through the direct readout wiring 38 connected as an electrical signal, and the electrical transmitted through the direct readout wiring 38 is transmitted. The signal is amplified by the variable gain preamplifier 92 at the amplification factor set by the cassette control unit 58, and then filtered by the LPF 96 at the low-pass frequency set by the cassette control unit 58.

  On the other hand, the cassette control unit 58 drives the sample and hold circuit 97 for a predetermined period after setting the amplification factor and the low-pass frequency, so that the signal level of the electrical signal subjected to the filtering process on the sample and hold circuit 97 is set. Hold.

  The signal level held in the sample and hold circuit 97 is sequentially selected by the multiplexer 98 in accordance with control by the cassette control unit 58, A / D converted by the A / D converter 99, and then obtained digital data. Is output to the cassette control unit 58. The digital data output from the A / D converter 99 indicates the radiation dose irradiated to the radiation detection pixel 32A during the predetermined period, and is used when creating the radiation dose information described above. .

  In the cassette control unit 58, digital data (hereinafter referred to as “individual radiation dose information”) corresponding to each of the radiation detection pixels 32A input from the A / D converter 99 is stored in advance in the RAM of the memory 58B. Store in a defined area.

  On the other hand, as shown in FIG. 13, the console 110 is configured as a server computer, and includes a display 111 that displays an operation menu, a captured radiographic image, and the like, and a plurality of keys. And an operation panel 112 for inputting operation instructions.

  The console 110 according to the present embodiment includes a CPU 113 that controls the operation of the entire apparatus, a ROM 114 that stores various programs including a control program in advance, a RAM 115 that temporarily stores various data, and various data. An HDD (Hard Disk Drive) 116 that stores and holds, a display driver 117 that controls display of various types of information on the display 111, and an operation input detection unit 118 that detects an operation state of the operation panel 112 are provided. . In addition, the console 110 transmits and receives various types of information such as an exposure condition, which will be described later, to and from the radiation generation apparatus 120 through wireless communication, and transmits and receives various types of information such as image data to and from the electronic cassette 40. A wireless communication unit 119 is provided.

  The CPU 113, ROM 114, RAM 115, HDD 116, display driver 117, operation input detection unit 118, and wireless communication unit 119 are connected to each other via the system bus BUS. Therefore, the CPU 113 can access the ROM 114, RAM 115, and HDD 116, controls the display of various information on the display 111 via the display driver 117, and the radiation generator 120 via the wireless communication unit 119 and Control of transmission and reception of various types of information with the electronic cassette 40 can be performed. Further, the CPU 113 can grasp the operation state of the user with respect to the operation panel 112 via the operation input detection unit 118.

  On the other hand, the radiation generator 120 includes the radiation source 121, the light source 125, the wireless communication unit 123 that transmits and receives various information such as the exposure conditions between the console 110, and the radiation source 121 based on the received exposure conditions. And a control unit 122 that controls the light emission state of the light source 125.

  The control unit 122 is also configured to include a microcomputer and stores received exposure conditions and the like. The exposure conditions received from the console 110 include information such as tube voltage and tube current. The control unit 122 irradiates the radiation X from the radiation source 121 based on the received exposure condition, and positions the subject with respect to the radiation X irradiation field prior to the irradiation of the radiation X from the radiation source 121. Irradiate visible light.

  Next, the operation of the imaging system 104 according to the present embodiment will be described.

  First, the operation of the console 110 when taking a radiographic image will be described with reference to FIG. FIG. 15 is a flowchart showing the flow of processing of the radiographic image capturing processing program executed by the CPU 113 of the console 110 when an instruction input for execution is performed via the operation panel 112. It is stored in advance in a predetermined area of the ROM 114. Here, a case where the light emission intensity by the light source 125 is set in advance to avoid complications will be described.

  In step 300 of the figure, the display driver 117 is controlled to display a predetermined initial information input screen on the display 111, and in the next step 302, instruction information for causing the light source 125 to emit light at a predetermined light emission intensity. Is transmitted to the radiation emitting device 120 via the wireless communication unit 119, and the next step 304 waits for input of predetermined information.

  FIG. 16 shows an example of an initial information input screen displayed on the display 111 by the processing in step 300 described above. As shown in the figure, in the initial information input screen according to the present embodiment, the name of the subject who will take a radiographic image, the part to be imaged, the posture at the time of radiography, and the exposure of the radiation X at the time of radiography A message prompting the input of conditions (in this embodiment, tube voltage and tube current when the radiation X is exposed) and an input area for such information are displayed.

  When the initial information input screen shown in the figure is displayed on the display 111, the photographer inputs the name of the subject to be imaged, the region to be imaged, the posture at the time of imaging, and the exposure conditions corresponding to each other. An area is input via the operation panel 112.

  On the other hand, when the radiation emitting device 120 receives the instruction information transmitted by the processing in step 302 from the console 110, the light emitting device 120 causes the light source 125 to emit light with the light emission intensity indicated by the instruction information. As a result, the irradiation field of the radiation X from the radiation source 121 is irradiated with visible light having the light emission intensity.

  Therefore, the photographer holds the electronic cassette 40 in the holding unit 162 of the standing table 160 or the holding unit 166 of the standing table 164 when the posture at the time of shooting is the standing position or the lying position, and the light source After the radiation source 121 is positioned at a position where the visible light irradiated from 125 is irradiated onto the imaging region by the electronic cassette 40, the subject is positioned so that the imaging target region is positioned in the imaging region. Thereafter, the photographer designates an end button displayed near the lower end of the initial information input screen via the operation panel 112. When an end button is designated by the photographer, step 304 is affirmative and the process proceeds to step 306.

  In step 306, instruction information for stopping the light emission of the light source 125 started by the processing in step 302 is transmitted to the radiation light emitting device 120 via the wireless communication unit 119. In response to this, the radiation light emitting device 120 stops the light emission of the light source 125.

  In the next step 308, information input on the initial information input screen (hereinafter referred to as “initial information”) is transmitted to the electronic cassette 40 via the wireless communication unit 119, and then in the next step 310. The exposure condition is set by transmitting the exposure condition included in the initial information to the radiation generator 120 via the wireless communication unit 119. In response to this, the control unit 122 of the radiation generation apparatus 120 prepares for exposure under the received exposure conditions.

  In the next step 312, instruction information for instructing the start of exposure is transmitted to the radiation generator 120 and the electronic cassette 40 via the wireless communication unit 119.

  In response to this, the radiation source 121 starts emission of radiation X at a tube voltage and a tube current according to the exposure conditions received by the radiation generator 120 from the console 110. The radiation X emitted from the radiation source 121 reaches the electronic cassette 40 after passing through the subject.

  On the other hand, when receiving the instruction information for instructing the start of exposure, the cassette control unit 58 of the electronic cassette 40 creates radiation dose information by the radiation dose acquisition function described above (details will be described later), and the created radiation dose. The system waits until the radiation dose indicated by the information is equal to or greater than a first threshold value that is predetermined as a value for detecting the start of radiation irradiation. Next, after the electronic cassette 40 starts the radiographic image capturing operation, the cumulative value of the radiation dose indicated by the radiation dose information is determined based on the radiation target X and the exposure conditions included in the initial information. When a predetermined second threshold value is reached as a value for stopping the exposure, the imaging operation is stopped and the exposure stop information is transmitted to the console 110.

  Therefore, in the next step 314, reception of the exposure stop information is waited for, and in the next step 316, instruction information for instructing the stop of the radiation X exposure is sent to the radiation generator 120 via the wireless communication unit 119. To send. In response to this, the exposure of the radiation X from the radiation source 121 is stopped.

  On the other hand, when the electronic cassette 40 stops the radiographic image capturing operation, the electronic cassette 40 transmits image data obtained by the capturing to the console 110.

  Therefore, in the next step 318, the process waits until the image data is received from the electronic cassette 40. In the next step 320, the received image data is subjected to the above-described defective pixel correction process, and then the shading correction is performed. The image processing for performing various corrections such as these is executed.

  In the next step 322, the image data subjected to the image processing (hereinafter referred to as “corrected image data”) is stored in the HDD 116, and in the next step 324, the radiation image indicated by the corrected image data is confirmed. The display driver 117 is controlled to display on the display 111 in order to perform the above.

  In the next step 326, the corrected image data is transmitted to the RIS server 150 via the in-hospital network 102, and then the present radiographic image capturing program is terminated. Note that the corrected image data transmitted to the RIS server 150 is stored in the database 150A, so that the doctor can perform interpretation, diagnosis, and the like of the radiographic image taken.

  Next, the operation of the electronic cassette 40 when the initial information is received from the console 110 will be described with reference to FIG. FIG. 17 is a flowchart showing a flow of processing of a cassette photographing processing program executed by the CPU 58A in the cassette control unit 58 of the electronic cassette 40 at this time, and the program is stored in a predetermined area of the memory 58B in advance. Yes.

  In step 400 of the figure, reception of instruction information instructing the start of exposure from the console 110 is waited for, and in the next step 402, radiation dose information is created by the radiation dose acquisition function described above. At this time, the CPU 58A sets the amplification factor of the variable gain preamplifier 92 and the low-pass frequency of the LPF 96 as follows.

  First, based on the current value output from each solar cell 168A input from the solar cell array 168, the presence region and the non-existence region are specified by the method described above.

  Next, the amplification factor of the variable gain preamplifier 92 connected to the radiation detection pixel 32A corresponding to the non-existing region is derived so as to be higher than that corresponding to the existing region, and corresponds to the non-existing region. The low pass frequency of the LPF 96 connected to the radiation detecting pixel 32A is derived so as to be higher than that corresponding to the existing region.

  In the electronic cassette 40 according to the present embodiment, as described above, the gain of the variable gain preamplifier 92 and the low-pass frequency of the LPF 96 can be set only in two stages. For this reason, the amplification factor on the high magnification side is derived as the amplification factor of the variable gain preamplifier 92 connected to the radiation detection pixel 32A corresponding to the non-existing region, and connected to the radiation detection pixel 32A corresponding to the existence region. As the amplification factor of the variable gain preamplifier 92, the amplification factor on the low and high magnification side is derived. Further, the low-pass frequency on the high frequency side is derived as the low-pass frequency of the LPF 96 connected to the radiation detection pixel 32A corresponding to the non-existing region, and is connected to the radiation detection pixel 32A corresponding to the existing region. The low pass frequency on the low frequency side is derived as the low pass frequency of the LPF 96.

  Then, the switch 92E of the variable gain preamplifier 92 and the switch 96E of the LPF 96 are set so that the derived amplification factor and low-pass frequency are obtained.

  Further, the CPU 58A reads out the individual radiation dose information obtained by the radiation detection pixel 32A corresponding to the specified non-existing region from the RAM in the memory 58B, and creates the radiation dose information by adding up these values.

  In the next step 404, it is determined whether or not the radiation dose indicated by the information created by the processing in step 402 is equal to or more than the first threshold value. If the determination is negative, the process returns to step 402. If the determination is affirmative, it is considered that the exposure of the radiation X from the radiation source 121 has started, and the routine proceeds to step 406.

  In step 406, after discharging the charge accumulated in the capacitor 9 in each pixel 32 of the radiation detector 20, the accumulation of the charge in the capacitor 9 is started again, thereby starting the radiographic image capturing operation. In the next step 408, radiation dose information is created by the radiation dose acquisition function described above. Note that the gain of the variable gain preamplifier 92 and the low-pass frequency of the LPF 96 at this time remain set by the processing of step 402.

  Here, the CPU 58A reads out the individual radiation dose information obtained by the radiation detection pixel 32A corresponding to the existence region specified by the processing in step 402 from the RAM in the memory 58B, and adds these values to add the radiation. Create quantity information.

  In the next step 410, it is determined whether or not the radiation dose indicated by the information created by the processing in step 408 is equal to or greater than the second threshold value described above. If a negative determination is made, the process proceeds to step 412. After accumulating the radiation dose created by the process of step 408, the process returns to step 408. On the other hand, when the determination is affirmative, the process proceeds to step 414. When repeatedly executing the processing from step 408 to step 412, in step 410, it is determined whether or not the radiation dose accumulated so far is equal to or greater than the second threshold value.

  In step 414, the imaging operation started by the processing in step 406 is stopped, and in the next step 416, the above-described exposure stop information is transmitted to the console 110 via the wireless communication unit 60.

  In the next step 418, the gate line driver 52 is controlled to output an ON signal to each gate wiring 34 in order line by line from the gate line driver 52, and each thin film transistor 10 connected to each gate wiring 34 is sequentially output line by line. Turn it on.

  In the radiation detector 20, when the thin film transistors 10 connected to the gate lines 34 are turned on line by line, the charges accumulated in the capacitors 9 line by line flow out to the data lines 36 as electric signals. The electrical signal that has flowed out to each data wiring 36 is converted into digital image data by the first signal processing unit 54 and stored in the image memory 56.

  Therefore, in this step 418, the image data stored in the image memory 56 is read out, and in the next step 420, the read image data is transmitted to the console 110 via the wireless communication unit 60, and then the cassette photographing processing program. Exit.

  Incidentally, in the electronic cassette 40 according to the present embodiment, as shown in FIG. 8, the radiation detector 20 is incorporated so that the radiation X is irradiated from the TFT substrate 30 side.

  Here, as shown in FIG. 18, the radiation detector 20 is irradiated with radiation from the side where the scintillator 8 is formed, and reads a radiation image by the TFT substrate 30 provided on the back side of the incident surface of the radiation. In the case of a so-called back surface reading method, light is emitted more strongly on the upper surface side of the scintillator 8 (opposite side of the TFT substrate 30), radiation is irradiated from the TFT substrate 30 side, and the surface side of the incident surface of the radiation In the case of a so-called surface reading method in which a radiation image is read by the TFT substrate 30 provided on the TFT substrate 30, the radiation transmitted through the TFT substrate 30 enters the scintillator 8 and the TFT substrate 30 side of the scintillator 8 emits light more strongly. Electric charges are generated in each sensor unit 13 provided on the TFT substrate 30 by light generated by the scintillator 8. For this reason, since the radiation detector 20 is closer to the light emission position of the scintillator 8 with respect to the TFT substrate 30 when the front surface reading method is used than when the rear surface reading method is used, the resolution of the radiation image obtained by imaging is higher. high.

  In the radiation detector 20, the photoelectric conversion film 4 is made of an organic photoelectric conversion material, and the photoelectric conversion film 4 hardly absorbs radiation. For this reason, the radiation detector 20 according to the present embodiment suppresses a decrease in sensitivity to radiation because the amount of radiation absorbed by the photoelectric conversion film 4 is small even when radiation is transmitted through the TFT substrate 30 by the surface reading method. Can do. In the surface reading method, radiation passes through the TFT substrate 30 and reaches the scintillator 8. Thus, when the photoelectric conversion film 4 of the TFT substrate 30 is made of an organic photoelectric conversion material, the radiation in the photoelectric conversion film 4 is obtained. Therefore, it is suitable for the surface reading method.

  In addition, both the amorphous oxide constituting the active layer 17 of the thin film transistor 10 and the organic photoelectric conversion material constituting the photoelectric conversion film 4 can be formed at a low temperature. For this reason, the board | substrate 1 can be formed with a plastic resin, aramid, and bio-nanofiber with little radiation absorption. Since the substrate 1 formed in this way has a small amount of radiation absorption, even when the radiation passes through the TFT substrate 30 by the surface reading method, it is possible to suppress a decrease in sensitivity to radiation.

  Further, according to the present embodiment, as shown in FIG. 8, the radiation detector 20 is attached to the top plate 41B in the casing 41 so that the TFT substrate 30 is on the top plate 41B side. When 1 is formed of a highly rigid plastic resin, aramid, or bio-nanofiber, the radiation detector 20 itself has high rigidity, so that the top plate 41B of the housing 41 can be formed thin. In addition, when the substrate 1 is formed of a highly rigid plastic resin, aramid, or bionanofiber, the radiation detector 20 itself has flexibility, so that even when an impact is applied to the imaging region 41A, the radiation detector 20 is damaged. It ’s hard.

  As described in detail above, in the present embodiment, a plurality of radiation detection pixels (in this embodiment) corresponding to non-existing areas (elementary areas) of a subject (in this embodiment, a subject). Based on the combined signal of the electrical signals obtained by the radiation detection pixels 32A), it is detected that radiation irradiation has started, and the non-existing area is detected without irradiating the subject with radiation. Therefore, it is possible to detect the start of radiation irradiation in a short time while suppressing the exposure dose to the subject.

  In the present embodiment, since the imaging region is irradiated with visible light or infrared light, the presence region and non-existence region of the subject in the imaging region are specified based on the light receiving region of the irradiated light. The existence area and the non-existence area can be specified without irradiating the subject with radiation.

  In particular, in the present embodiment, the existence region and the non-existence region are specified using a solar cell array (in this embodiment, the solar cell array 168). The existence area can be specified.

  Further, in the present embodiment, the radiation dose is further detected based on an electrical signal obtained by the radiation detection pixel corresponding to the existence region in a state where the imaging region is irradiated with radiation. As a result, it is possible to detect the radiation dose by using the radiation whose dose has been reduced by passing through the subject. As a result, the radiation dose can be detected more reliably.

  In particular, in the present embodiment, since the radiation dose is detected based on the combined signal of the electrical signals obtained by the plurality of radiation detection pixels corresponding to the existence region, the radiation is transmitted through the subject. As a result, it is possible to detect the radiation dose more reliably as compared with the case where the radiation dose is detected using the radiation whose dose has been excessively reduced.

  In the present embodiment, since the radiation detection pixels are arranged in the imaging region so that the density of the region where the non-existing region is more frequently increased, the radiation detection pixel can be surely and more reliably shortened in a shorter time. The start of irradiation can be detected.

  In particular, in the present embodiment, the region that is frequently used as the non-existing region is a partial region that includes the peripheral portion of the imaging region, and can therefore handle almost all subjects.

  In the present embodiment, the plurality of radiation detection pixels are arranged between the plurality of radiation image acquisition pixels (radiation image acquisition pixels 32B in the present embodiment). Since the pixel and the radiation image acquisition pixel can be configured by the same manufacturing process, the manufacturing cost can be reduced.

  Further, the present embodiment includes an amplifier (in this embodiment, a variable gain preamplifier 92) that amplifies an electrical signal obtained by the radiation detection pixel at a preset amplification factor, and Since the amplification factor of the amplifier is set based on the result of specifying the existing area, the radiation irradiation state can be detected more easily and reliably.

  In particular, in the present embodiment, the amplification factor of the amplifier that amplifies the electrical signal obtained by the radiation detection pixel corresponding to the non-existing region is obtained by the radiation detection pixel corresponding to the existence region. Since it is set to be higher than the amplifier that amplifies the electric signal, the start of radiation irradiation can be detected in a shorter time.

  In this embodiment, a low-pass filter (in this embodiment) performs low-pass processing at a preset low-pass frequency on the signal indicated by the charge accumulated by the radiation detection pixels. , LPF 96), and the low-pass frequency of the low-pass filter is set based on the result of specifying the existence region and the non-existence region, so that the start of radiation irradiation can be detected more easily and reliably. be able to.

  In particular, in the present embodiment, the low-pass frequency of a low-pass filter that performs low-pass processing on the signal obtained by the radiation detection pixel corresponding to the non-existing region corresponds to the existing region. Since the signal obtained by the radiation detection pixel is set to be higher than a low-pass filter that performs low-pass processing, the radiation irradiation start can be detected more accurately.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  The above embodiments do not limit the invention according to the claims (claims), and all the combinations of features described in the embodiments are essential for the solution means of the invention. Is not limited. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in the above embodiment, the case where the solar cell array 168 is applied to specify the presence region and the non-existence region has been described. However, the present invention is not limited to this, and for example, the solar cell array 168 Instead of the above, a photoelectric conversion element made of a material containing an organic photoelectric conversion material may be applied, and a light source 125 that emits visible light may be applied. In this case, since the sensitivity wavelength region of the organic photoelectric conversion material can be narrower than that of amorphous silicon, the existence region and the non-existence region can be more accurately compared with the case where a solar cell array using amorphous silicon is used. Can be identified.

  FIG. 19 shows an example of a sensitivity wavelength region when a quinacridone-based organic compound is applied as the organic photoelectric conversion material. As is clear from the figure, in this embodiment, by using a filter in the insensitive region of the organic photoelectric conversion material, mixing with light emitted from the fluorescent lamp can be reduced.

  In the above-described embodiment, the case where visible light or infrared light is used to specify the existing region and the non-existing region has been described. However, the present invention is not limited to this, and for example, a solar cell array Instead of 168, a photoelectric conversion element using an oxide semiconductor (a-IGZO as an example) may be used, and a light source 125 emitting blue to ultraviolet light may be used. Note that when a-IGZO is used as the oxide semiconductor, sensitivity is obtained in a region of 460 nm or less. In this embodiment, mixing with the light emitted from the fluorescent lamp can be reduced by using the filter that cuts the peak wavelength of the short wave in the light emitted from the fluorescent lamp.

  Further, as an alternative to the solar cell array 168 according to the above embodiment, an LED type photosensor can also be exemplified. Usually, an LED is an element that emits light by passing an electric current. On the contrary, a photovoltaic force is generated by irradiating the LED with light. Using this photovoltaic power, the presence area and the non-existence area are specified by the light from the light source 125.

  In the above-described embodiment, the case where the existence region and the non-existence region are specified using light has been described. However, the present invention is not limited to this, for example, by changing a resistance value or a capacitance value. By using a pressure sensor that detects a contact object or a temperature sensor, the presence area and the non-existence area may be specified without using light. Examples of forms using the pressure sensor include, for example, “NITTA Corporation,“ Tactile Sensor System ”, [online], [Search September 8, 2011], Internet <URL: http: //www.nitta An example using an ultrathin pressure sensor sheet described in “.co.jp / product / mechasen / sensor / tactile_system_sensor.html>” is illustrated.

  In the above embodiment, as shown in FIG. 6, the radiation detection pixels 32 </ b> A have a low density in the partial region 20 </ b> A including the center of the imaging region of the radiation detector 20, and in the peripheral portion of the imaging region. Although the case where it arrange | positions with the density of two steps so that a density becomes high was demonstrated, this invention is not limited to this, It is good also as a form arrange | positioned with the density of three steps or more.

  20A and 20B show an example of a configuration in which the radiation detection pixels 32A are arranged at three levels of density. Here, FIG. 20A shows an example of the radiation detector 20 for general imaging, and FIG. 20B shows an example of the radiation detector 20 'for mammography imaging. Note that in the case of the radiation detector 20 ″ for both general imaging and mammography imaging, as shown in FIG. 20C as an example, the radiation shown in FIGS. 20A and 20B is used. A state in which the arrangement state of the detection pixels 32A is combined can be exemplified.

  Further, although not particularly mentioned in the above embodiment, markers such as characters, symbols, symbols, frames, etc., are located on the surface of the top plate 41B of the electronic cassette 40 at positions corresponding to the regions where the density of the radiation detection pixels 32A is low. It is good also as a form which provides.

  FIG. 21 shows an example of the marker of the electronic cassette 40 incorporating the radiation detector shown in FIG. FIG. 21A shows an example of an electronic cassette 40 incorporating the radiation detector 20 shown in FIG. 20A, and FIG. 21B incorporates the radiation detector 20 ′ shown in FIG. 20B. FIG. 21C shows an example of the electronic cassette 40 incorporating the radiation detector 20 ″ shown in FIG. 20C. A marker 41D in FIG. 21 is a marker for general photography, and a marker 41E is a marker for mammography photography.

  FIG. 22 shows another example of the marker of the electronic cassette 40 incorporating the radiation detector shown in FIG. 22A shows an example of an electronic cassette 40 incorporating the radiation detector 20 shown in FIG. 20A, and FIG. 22B incorporates the radiation detector 20 ′ shown in FIG. 20B. FIG. 22C shows an example of the electronic cassette 40 including the radiation detector 20 ″ shown in FIG. 20C. Further, a broken line marker 41F in FIG. 22 is a marker for general imaging, and a dashed line marker 41G is a marker for mammography imaging.

  By providing such a marker on the top plate 41 </ b> B of the electronic cassette 40, it is possible for the photographer to explicitly grasp the position where the imaging target part should be arranged.

  In the above embodiment, as an example, as shown in FIG. 23A, the case where a part of the radiation image acquisition pixel 32B is applied as the radiation detection pixel 32A has been described. However, the present invention is not limited thereto. For example, as shown in FIG. 23B, for example, the radiation detection pixel 32A may be provided in the gap between the radiation image acquisition pixels 32B. In this case, since the area of the radiation image acquisition pixel 32B corresponding to the position where the radiation detection pixel 32A is provided is reduced, the sensitivity of the pixel is reduced, but the pixel is also used for detection of the radiation image. Therefore, the quality of the radiographic image can be improved.

  In the above-described embodiment, the radiation detection pixel 32A has been described as being disposed in the radiation detector 20 with the density being changed stepwise from the center to the periphery of the imaging region of the radiation detector 20. The invention is not limited to this. For example, as shown in FIG. 24 as an example, the density of the radiation detection pixels 32A is gradually increased from the center to the periphery of the imaging region. Alternatively, the radiation detection pixels 32 </ b> A may be disposed only on one diagonal line of the imaging region.

  In the above embodiment, the case where a partial region including the central portion of the imaging region is applied as the region where the imaging target region in the imaging region of the radiation detector 20 is frequently arranged has been described. The invention is not limited to this, and depending on the use of the electronic cassette 40, a partial area not including the central portion of the imaging area may be applied as an area where the imaging target part is frequently arranged. Good.

  Further, as shown in FIG. 6 and FIG. 24, it is not necessary to arrange the radiation detection pixels 32 </ b> A symmetrically in the imaging region of the radiation detector 20, and in short, depending on the actual application of the electronic cassette 40. As long as the region where the imaging target region is arranged is higher, the density is lower, in other words, the radiation detection pixels 32A may be arranged so that the density is higher in the region where the frequency of becoming a blank region is higher. Forms can also be applied.

  However, in the above embodiment, a part of the pixels 32 provided in the radiation detector 20 is used as the radiation detection pixel 32A, so that the adjacent radiation detection pixel 32A can perform defect pixel correction. Needless to say, they are preferably spaced apart.

  As described above, in the above-described embodiment, the case where a part of the pixels 32 provided in the radiation detector 20 is used as the radiation detection pixel 32A has been described. However, the present invention is not limited to this, for example, The radiation detection pixels 32 </ b> A may be stacked on the radiation detector 20 as a separate layer from the pixels 32. In addition, as a form example in this case, a form in which the light receiving area in the photoelectric conversion layer of the radiation detection pixel 32A is gradually widened from a high frequency area to a low frequency area where the imaging target part is arranged can be exemplified. . In this case, since defective pixels do not occur, the quality of the radiation image can be improved as compared with the above embodiment.

  In the above-described embodiment, the case where both the gain of the variable gain preamplifier 92 and the low-pass frequency of the LPF 96 are switched according to the specified result of the existing region and the non-existing region has been described, but the present invention is not limited to this. However, it is possible to switch only one of them.

  In the above embodiment, the case where the gain of the variable gain preamplifier 92 and the low-pass frequency of the LPF 96 are switched in two stages has been described. However, the present invention is not limited to this, and these are more than three stages. It is good also as a form switched by.

  In the above-described embodiment, the case where the radiation detection pixel 32A is used to start radiation irradiation and detect the irradiation amount has been described. However, the present invention is not limited to this, and radiation irradiation is stopped. The radiation detection pixel 32A may be used to detect the above.

  In the above-described embodiment, in order to avoid complications, no particular mention was made regarding discharging the charge accumulated in the radiation detection pixels 32A. However, the start of radiation irradiation or the detection of the radiation dose is not performed. After the completion, the end of radiation irradiation may be detected after discharging the charge accumulated by the radiation detection pixel 32A. Thereby, the saturation of the said radiation dose at the time of detecting completion | finish of irradiation of a radiation can be prevented.

  In the above embodiment, the case where the sensor unit 13 is configured to include an organic photoelectric conversion material that generates charges by receiving light generated by the scintillator 8 has been described. It is not limited, It is good also as a form which applies what was comprised without including an organic photoelectric conversion material as the sensor part 13. FIG.

  Moreover, although the said embodiment demonstrated the case where it arrange | positions so that the case 42 which accommodates the cassette control part 58 and the power supply part 70 in the inside of the housing | casing 41 of the electronic cassette 40, and the radiation detector 20 may not overlap. It is not limited to this. For example, the radiation detector 20 and the cassette control unit 58 or the power supply unit 70 may be arranged so as to overlap each other.

  Moreover, although the said embodiment demonstrated the case where it communicated by radio | wireless between the electronic cassette 40 and the console 110, and between the radiation generator 120 and the console 110, this invention is limited to this. For example, at least one of these may be configured to perform wired communication.

  In the above embodiment, the case where X-rays are applied as radiation has been described. However, the present invention is not limited to this, and other radiation such as γ-rays may be applied.

  In addition, the configuration of the RIS 100 described in the above embodiment (see FIG. 1), the configuration of the radiation imaging room (see FIG. 2), the configuration of the electronic cassette 40 (see FIGS. 3 to 8 and 14), and imaging. The configuration of the system 104 (see FIG. 13) is an example, and unnecessary portions are deleted, new portions are added, connection states, etc. are changed within the scope not departing from the gist of the present invention. It goes without saying that it can be done.

  The configuration of the initial information described in the above embodiment is also an example, and it goes without saying that unnecessary information can be deleted or new information can be added without departing from the gist of the present invention. Yes.

  The processing flow of various programs described in the above embodiment (see FIGS. 15 and 17) is also an example, and unnecessary steps can be deleted or new within the scope of the gist of the present invention. It goes without saying that steps can be added and the processing order can be changed.

  Furthermore, the configuration of the initial information input screen described in the above embodiment (see FIG. 16) is also an example, and unnecessary information is deleted or new information is added without departing from the gist of the present invention. Needless to say, you can.

20 radiation detector 32 pixel 32A radiation detection pixel 32B radiation image acquisition pixel 38 direct readout wiring 40 electronic cassette (radiation image capturing apparatus)
55 Second signal processing unit 58 Cassette control unit (detection means, control means, amplification factor setting means, frequency setting means)
58A CPU
92 Variable Gain Preamplifier (Amplifier)
96 LPF (low pass filter)
125 Light source 168 Solar cell array (specific device)
168A Solar cell X radiation

Claims (16)

A specifying device for specifying a non-existing region of the subject in a predetermined imaging region without irradiating the subject with radiation;
A radiation detector in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are arranged, and radiation is irradiated to the imaging region Detection means for detecting that irradiation of the radiation is started based on a combined signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the specified non-existing region in a state where And a radiographic imaging device comprising control means for controlling radiographic imaging operation by the radiation detector based on the detection result by the detection means,
A radiographic imaging system comprising: The radiographic image according to claim 1, wherein the specifying device specifies the non-existing region based on a light receiving region of the irradiated light in a state where the imaging region is irradiated with at least one of visible light, ultraviolet light, and infrared light. Shooting system. The radiographic imaging system according to claim 2, wherein the specifying device specifies the non-existing region using a solar cell array. The specifying device further specifies the existence region of the subject in the photographing region without irradiating the subject with radiation,
The detection means further detects the radiation dose based on an electrical signal obtained by the radiation detection pixel corresponding to the specified existence area in a state where the imaging area is irradiated with radiation. The radiographic imaging system of any one of Claims 1-3. The radiographic imaging system according to claim 4, wherein the detection unit detects an irradiation amount of the radiation based on a composite signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the existence region. The radiographic imaging system according to any one of claims 1 to 5, wherein the radiation detection pixels are arranged in the imaging region such that the density of the region where the frequency of becoming the non-existing region increases is higher. . The radiographic image capturing system according to claim 6, wherein the region having a high frequency as the non-existing region is a partial region including a peripheral portion of the imaging region. The radiographic image according to claim 6, wherein the plurality of radiation detection pixels are arranged in the imaging region such that a region having a higher frequency of becoming the non-existing region has a higher density stepwise or continuously. Shooting system. The radiographic imaging system according to any one of claims 1 to 8, wherein the plurality of radiation detection pixels are arranged between the plurality of radiographic image acquisition pixels. The radiographic image capturing apparatus includes:
An amplifier that amplifies the electrical signal obtained by the radiation detection pixel at a preset amplification factor;
An amplification factor setting means for setting the amplification factor of the amplifier based on the identification result by the identification device;
The radiographic imaging system according to claim 1, further comprising: The amplification factor setting means sets an amplification factor of an amplifier that amplifies an electric signal obtained by the radiation detection pixel corresponding to the non-existing region to an electric factor obtained by the radiation detection pixel corresponding to the existence region. The radiographic imaging system according to claim 10, wherein the radiographic imaging system is set to be higher than an amplifier that amplifies a signal. The radiographic image capturing apparatus includes:
A low-pass filter that performs low-pass processing at a preset low-pass frequency for a signal indicated by the charge accumulated by the radiation detection pixels;
Frequency setting means for setting the low-pass frequency of the low-pass filter based on the identification result by the identification device;
The radiographic imaging system according to any one of claims 1 to 11, further comprising: The frequency setting means sets a low-pass frequency of a low-pass filter that performs low-pass processing on a signal obtained by the radiation detection pixel corresponding to the non-existing region, and corresponds to the existing region. The radiographic imaging system according to claim 12, wherein the radiographic imaging system is set to be higher than a low-pass filter that performs low-pass processing on a signal obtained by the radiation detection pixel. A specifying means for specifying a non-existing region of the subject in a predetermined photographing region without irradiating the subject with radiation;
A radiation detector in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are respectively disposed;
Irradiation of the radiation is started based on a composite signal of electrical signals obtained by the plurality of radiation detection pixels corresponding to the specified non-existing region in a state where the imaging region is irradiated with radiation. Detecting means for detecting
A radiographic imaging device comprising: control means for controlling radiographic imaging operation by the radiation detector based on a detection result by the detection means. A specifying step of specifying a non-existing region of the subject in a predetermined imaging region without irradiating the subject with radiation;
Radiation detection in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are arranged in a state where radiation is irradiated on the imaging region A detection step of detecting the start of radiation irradiation based on a composite signal of electrical signals obtained by a plurality of the radiation detection pixels corresponding to the specified non-existing region of the device;
And a control step of controlling a radiographic imaging operation by the radiation detector based on a detection result of the detection step. Computer
A specifying means for specifying a non-existing region of the subject in a predetermined photographing region without irradiating the subject with radiation;
Radiation detection in which a plurality of radiation detection pixels for detecting a radiation irradiation state and a plurality of radiation image acquisition pixels for capturing a radiation image of the subject are arranged in a state where radiation is irradiated on the imaging region Detecting means for detecting that irradiation of the radiation is started based on a composite signal of electrical signals obtained by a plurality of the radiation detection pixels corresponding to the specified non-existing region of the device;
The program for functioning as a control means which controls the imaging | photography operation | movement of the radiographic image by the said radiation detector based on the detection result by the said detection means.

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