WO2015064149A1

WO2015064149A1 - Radiographic imaging device and information processing device

Info

Publication number: WO2015064149A1
Application number: PCT/JP2014/067184
Authority: WO
Inventors: 廣池　太郎
Original assignee: キヤノン株式会社
Priority date: 2013-10-30
Filing date: 2014-06-27
Publication date: 2015-05-07
Also published as: JPWO2015064149A1; JP6425658B2

Abstract

Provided is a radiographic imaging device that immediately performs a refresh operation when it is detected that an X-ray has been emitted during a preparation period that begins when the refreshing of a photoelectric conversion element is completed (or when an X-ray imaging device (100) starts up).

Description

Radiation imaging apparatus and information processing apparatus

The disclosure of the present specification relates to a radiation imaging apparatus and an information processing apparatus.

In recent years, digitization of radiation images such as X-ray images in medical treatment has progressed. By digitizing x-ray images, many benefits can be obtained. For example, speeding up of diagnosis can be achieved by making it possible to immediately confirm a captured X-ray image with a display device or the like. Moreover, automation of diagnosis can be achieved by using X-ray images subjected to various image processing. In addition, it is possible to improve the diagnostic accuracy for minute lesions. In addition, the space efficiency in the hospital can be greatly improved by eliminating the storage space of the film. Furthermore, since there is little deterioration of data due to transmission, it is also possible to transmit a captured X-ray image to a distant place without deterioration. Taking advantage of these features, for example, it is possible to transmit X-ray images taken at home medical care sites or disaster sites to a well-equipped urban hospital for diagnosis by a highly trained physician. It becomes.

Under such a background, a radiation imaging apparatus that converts radiation into an electrical signal to form a radiation image by a plurality of radiation detection elements arranged in a two-dimensional matrix is in practical use and is rapidly spreading.

This type of radiation imaging apparatus includes an X-ray detection apparatus (for example, FPD: Flat Panel Detector). From the X-ray generator, for example, an X-ray detector is provided with a micro X-ray detector in which a solid photoelectric conversion element and a scintillator for converting X-rays into visible light are stacked in a two-dimensional matrix. The irradiated X-ray is converted into an electrical signal (charge amount) according to the irradiation amount of the X-ray. In FPD, in general, charges generated by X-ray irradiation are accumulated in the solid photoelectric conversion element by controlling a voltage applied to the solid photoelectric conversion element. Thereafter, by controlling the voltage applied to the solid photoelectric conversion element to another voltage, the charge is read from the solid photoelectric conversion element, and image data corresponding to the amount of charge accumulated in the solid photoelectric conversion element is formed. When capturing an X-ray image using FPD, the timing of X-ray irradiation and the timing of charge accumulation (photographing) by the X-ray detector are accurately synchronized due to the characteristics of the solid-state photoelectric conversion element being used. There is a need.

Therefore, in Patent Document 1, there is a technique for synchronizing the X-ray irradiation timing and the X-ray image imaging timing by mutually exchanging synchronization signals between the X-ray generator and the X-ray imaging apparatus. It is disclosed. Specifically, first, the X-ray imaging apparatus (for example, FPD) prepares for imaging by receiving an irradiation request signal from the X-ray generator. Thereafter, when the X-ray imaging apparatus starts imaging (charge accumulation starts), the X-ray imaging apparatus transmits an irradiation permission signal to the X-ray generation apparatus, and the X-ray generation apparatus transmits X-rays. Is irradiated.

Further, in Patent Document 2, X-ray irradiation timing is detected by detecting a change in current generated inside the X-ray imaging apparatus when the X-ray imaging apparatus irradiates the X-ray imaging apparatus with X-rays. There is disclosed a technique for detecting an X-ray emission timing and using this X-ray irradiation timing as a trigger to start imaging. In this case, synchronous communication between the X-ray generator and the X-ray imaging apparatus is not necessarily required.

Patent No. 4684747 Japanese Patent Application Laid-Open No. 11-155847

However, even with the techniques described in

Patent Documents

1 and 2, the X-ray can be irradiated at an arbitrary timing by an operation or the like on the X-ray generator side. When adopting such a configuration, the X-ray is irradiated during a preparation period which is a period before preparation for imaging on the X-ray imaging apparatus side or before transition to a state where the image quality is sufficiently ensured. Can occur. In such a preparation period, the state of the X-ray imaging apparatus is not stable. Therefore, an X-ray image based on X-rays irradiated during the preparation period may not be able to be used as an image suitable for diagnosis from the viewpoint of image quality. In addition to this, there is also a possibility that the charge stored in the photoelectric conversion element based on the X-rays irradiated in the preparation period may affect the image quality of the X-ray image obtained in the next imaging. Therefore, it is desirable to shorten the period in which the state of the X-ray imaging apparatus is not stable.

A radiation imaging apparatus according to one of the embodiments of the present invention includes: detection means for detecting that irradiation of radiation has been started based on charges generated in a photoelectric conversion element performing photoelectric conversion; and sensitivity of the photoelectric conversion element And driving means for performing a reset operation for outputting the charge accumulated in the photoelectric conversion element to recover the radiation, wherein the driving means detects the period during which radiation irradiation is not recommended. When it is detected that the irradiation of the radiation has been started by the means, the photoelectric conversion element when it is detected that the irradiation of the radiation has been started by the detection means in a period when the irradiation of the radiation is recommended. The reset operation is performed at a timing at which a period during which charge is accumulated in the photoelectric conversion element becomes shorter than a period during which charge is accumulated.

Thereby, the period when the state of the radiation imaging apparatus is not stable can be shortened.

It is a figure which shows the structure of a radiography system. It is a figure which shows the 1st example of a structure of a X-ray imaging apparatus. It is a figure which shows the equivalent circuit of a X-ray detector. It is a figure which shows the cross section of a photoelectric conversion element. It is a figure which shows the energy band of a photoelectric conversion element. It is a timing chart which shows the drive timing of an X-ray detector. It is a flowchart explaining the 1st example of the process in a radiography apparatus. It is a figure which shows the 2nd example of a structure of a X-ray imaging apparatus. It is a flowchart explaining the 2nd example of the process in a radiography apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, the case of capturing an X-ray image will be described. However, even when radiographs are performed using alpha rays, beta rays, gamma rays, and other electromagnetic waves other than X-rays, the X-rays described below may be replaced by these radiations, etc. Each embodiment can be applied.

First Embodiment
FIG. 1 is a diagram showing an example of the configuration of an X-ray imaging system.

The X-ray imaging system of this embodiment includes an X-ray imaging apparatus 100, an X-ray generation apparatus 200, an imaging information processing apparatus 400, a display unit 410, a storage unit 420, an operation unit 430, and an imaging table 500.

The X-ray generator 200 includes an X-ray control unit 210, an X-ray irradiation switch 220, and an X-ray generation unit 230. The X-ray control unit 210 controls, for example, on / off of X-rays, and generation conditions of X-rays such as tube current and tube voltage. The X-ray generation unit 230 has, for example, a reflective or transmissive target, and generates, for example, pulsed X-rays by colliding the target with an electron beam. The X-ray generated by the X-ray generator 230 is shaped into a bundle of X-rays by the collimator of the X-ray generator 200, and the X-ray is irradiated to the subject 300 (subject) and the X-ray imaging apparatus 100. Further, the X-ray irradiation switch 220 is a switch operated when instructing the irradiation of X-rays. By operating the X-ray irradiation switch 220, X-rays can be generated at any timing.

The imaging table 500 has, for example, a top plate on which the subject 300 is placed, a column movably holding the X-ray generator 200, and a storage unit movably storing the X-ray imaging apparatus 100. The X-ray generation unit 230 and the X-ray imaging apparatus 100 are positioned by the imaging table 500, and the positional relationship between the X-ray generation unit 230 and the subject 300 placed on the top plate can be adjusted.

For example, the X-ray imaging apparatus 100 repeatedly and continuously monitors the output of the X-ray detector 110 (see FIG. 2) to detect that X-rays have been irradiated, and based on the detection result, X-rays are detected. The generation timing of the X-ray by the generator 200 can be detected. Therefore, the connection between the X-ray generator 200 and the imaging information processing apparatus 400 is not necessarily required. The X-ray control unit 210 and the X-ray control unit 210 communicate with the X-ray control unit 210 and the X-ray imaging apparatus 100 to generate X-rays while the X-ray detector 110 is in the accumulation state. The communication with the imaging device 100 may be synchronized. The detailed configuration of the X-ray imaging apparatus 100 will be described later with reference to FIG.

The imaging information processing apparatus 400 includes a control unit 401, a communication circuit 402, and a storage unit 403.

The imaging information processing apparatus 400 communicates with the X-ray imaging apparatus 100 through the communication circuit 402. The control unit 401 generates and manages imaging information for performing X-ray imaging, acquires an X-ray image obtained by X-ray imaging, associates the acquired X-ray image with the imaging information, and stores it in the storage unit 403 or the like. . The control unit 401 is mutually connected to the display unit 410, the storage unit 420, and the operation unit 430, receives an operation input from the operation unit 430, and performs settings such as acquisition, generation, and change of imaging information. The imaging information and the X-ray image are displayed on the display unit 410, and the user can confirm the X-ray image. Further, the imaging information and the X-ray image can be stored in the storage unit 420. The operation unit 430 may be a general-purpose operation device such as a keyboard, a mouse device, or a touch panel, or an operation device dedicated to the imaging information processing apparatus 400.

The imaging information processing device 400 is a computer device, and is connected to a network 700 such as an in-hospital intranet. The imaging information processing apparatus 400 transmits an X-ray image to an output destination apparatus such as the PACS 620, the viewer 630, and the printer 640 through the communication circuit 402.

The RIS (Radiology Information System) 610 manages requests for imaging information, transmits imaging request information to the imaging information processing apparatus 400, and manages the progress of the requested imaging. The imaging information processing apparatus 400 that has received the imaging request information generates imaging information necessary for imaging, and instructs X-ray imaging. The imaging information here includes the drive conditions of the X-ray imaging apparatus 100. In addition to this, the imaging information includes the X-ray irradiation conditions of the X-ray generator 200, the image processing conditions of the X-ray image obtained by the X-ray imaging apparatus 100, cropping of the image processed X-ray image, etc. An output condition may be included. Also, any combination of these may be used as the shooting information. When there is a progress such as start and completion of imaging, the communication circuit 402 transmits information indicating the progress to the RIS 610 according to the control of the control unit 401.

When the imaging information includes the X-ray irradiation condition, the imaging information processing apparatus 400 establishes communication with the X-ray control unit 210 and transmits the X-ray irradiation condition from the communication circuit 402 to the X-ray control unit 210. It is convenient if it makes it. When there is no communication between the imaging information processing apparatus 400 and the X-ray control unit 210, the user operates the console of the X-ray control unit 210 separately to input the X-ray generation condition.

A Picture Archiving and Communication Systems (PACS) 610 is an image management server that receives X-ray images and manages them together with other medical images.

The Viewer 630 is an apparatus that performs image processing and display control for a diagnostician such as a doctor to view a medical image. The Viewer 630 can also communicate with the PACS 620 to obtain medical images.

The printer 640 outputs the X-ray image and the medical image from the imaging information processing apparatus 400, the PACS 620, and the viewer 630 to a recording medium such as film or paper.

FIG. 2 is a diagram showing an example of the configuration of the X-ray imaging apparatus 100. As shown in FIG.
The X-ray imaging apparatus 100 is configured as an example of a radiation imaging apparatus, and includes an X-ray detector 110, an X-ray irradiation detection unit 150, a control unit 160, a drive circuit 165, a readout circuit 170, and an image processing unit 175. And a communication circuit 180.

The X-ray detector 110 includes a two-dimensional imaging device 120 in which a plurality of solid-state photoelectric conversion devices are arranged in a two-dimensional matrix, and a bias power supply 140 for supplying a bias voltage to the two-dimensional imaging device 120. Have.

The X-ray irradiation detection unit (X-ray irradiation detection circuit) 150 is connected to the bias power supply 140 and detects the start of X-ray irradiation.

A control unit (control circuit) 160 controls various operations of the X-ray imaging apparatus 100. The drive circuit 165 drives the X-ray detector 110 based on the control signal from the control unit 160.

The readout circuit 170 reads out image data from the X-ray detector 110. The image processing unit 175 performs various types of image processing on the image data read by the reading circuit 170.

The communication circuit 180 is a circuit for communicating with an external photographing information processing apparatus 400 or the like.

In FIG. 2, an X-ray 240 generated from the X-ray generation unit 230 is irradiated to the subject 300. The X-ray 240 transmitted through the subject 300 is incident on the two-dimensional imaging element 120 disposed inside the X-ray imaging apparatus 100 and is converted into an X-ray image. The X-ray image is read out through the readout circuit 170 and subjected to image processing by the image processing unit 175, and then transferred as digital image data to the external imaging information processing apparatus 400 via the communication circuit 180. The digital image data transferred to the photographing information processing apparatus 400 is stored in the storage unit 420 or displayed on the display unit 410. Communication by the communication circuit 180 may be wired communication or wireless communication. Alternatively, digital image data may be directly stored in the storage unit 420 without passing through the photographing information processing apparatus 400. In addition, a storage unit may be provided inside the X-ray imaging apparatus 100, and the digital image data may be stored in the storage unit.

FIG. 3 is a view showing an example of an equivalent circuit of the X-ray detector 110. As shown in FIG.

The two-dimensional imaging device 120 has a plurality of pixels arranged in a two-dimensional matrix of m rows and n columns. Note that FIG. 3 shows a 3 × 3 two-dimensional matrix of m = 3 and n = 3 in order to simplify the description. However, the actual X-ray detector 110 has many pixels, for example, m = 2800 and n = 2800. Each pixel includes a phosphor (not shown) that converts the X-ray 240 into light in a wavelength band that can be sensed by the photoelectric conversion element, photoelectric conversion elements S11 to S33, and switch elements T11 to T33.

The photoelectric conversion elements S11 to S33 generate and accumulate charges in accordance with the amount of incident X-rays. The amount of transmission of the X-rays transmitted through the subject 300 differs depending on the structure, the lesion, and the like of the bone and viscera inside the subject 300. As described above, the X-rays transmitted through the subject 300 have a distribution depending on the amount of transmission which differs depending on the structure, the lesion, and the like. The distribution of X-rays having such a distribution is converted into a distribution of charges and accumulated in the photoelectric conversion elements S11 to S33.

As the photoelectric conversion elements S11 to S33, various elements using amorphous silicon or polysilicon besides CCD (charge-coupled device) are known. In the present embodiment, MIS type photodiodes, which are disposed on an insulating substrate such as a glass substrate and are mainly made of amorphous silicon, are used as the photoelectric conversion elements S11 to S33. However, for example, PIN type photodiodes may be used as the photoelectric conversion elements S11 to S33. Further, direct type conversion elements that convert radiation directly into electric charges can also be suitably used as the photoelectric conversion elements S11 to S33.

As the switch elements T11 to T33, for example, a transistor having a control terminal and two main terminals is preferably used. In the present embodiment, thin film transistors (TFTs) are used as the switch elements T11 to T33.

In FIG. 3, the lower electrode side of the photoelectric conversion elements S11 to S33 is indicated by G, and the upper electrode side is indicated by D (in the following description, the lower electrode is referred to as the G electrode as necessary, and the upper electrode as the D electrode as necessary. Called The D electrode is electrically connected to one of the two main terminals of the switch elements T11 to T33. On the other hand, the G electrodes are electrically connected to the bias power supply 140 via a common bias line in each row. A control terminal of each of the plurality of switch elements arranged in the same row is commonly connected to the drive wirings g1, g2, g3 of the row (for example, control of each of the switch elements T11 to T13 in the first row) The terminal is connected to the drive wiring g1 in the first row). Drive signals for controlling the conductive states of the switch elements T11 to T33 are supplied from the drive circuit 165 in row units through the drive wirings g1, g2, g3.

Among the main terminals of a plurality of switch elements arranged in the same column, the main terminals not connected to the photoelectric conversion elements S11 to S33 are electrically connected to the signal wirings s1, s2, and s3 of the corresponding column. Ru. For example, among the main terminals of the switch elements T11, T21, and T31, the main terminals not connected to the photoelectric conversion elements S11, S21, and S31 in the first column are electrically connected to the signal wiring s1 in the first column. Ru. The electrical signals corresponding to the charge amount stored in the photoelectric conversion elements S11 to S33 are output to the readout circuit 170 through the signal lines s1 to s3 while the switch elements T11 to T33 are in the conductive state. The plurality of signal lines s1 to s3 arranged in the column direction transmit the electric signals read from the plurality of pixels in parallel to the reading circuit 170.

The readout circuit 170 sequentially processes the electrical signals read out in parallel, and outputs a multiplexer (not shown) as an image signal of a serial signal, and a buffer amplifier (not shown) which converts the impedance of the image signal and outputs it. including. The image signal which is an analog electrical signal output from the buffer amplifier is converted by the AD converter 171 into digital image data.

The bias power supply 140 supplies the bias voltage Vs to the G electrodes of the photoelectric conversion elements S11 to S33 through the bias wiring, and outputs current information including a change in the amount of current supplied to the bias wiring. In this embodiment, a current-voltage conversion circuit having an operational amplifier AMP and a resistor R and an AD converter 141 for converting a converted output voltage into a digital value are used as a circuit for outputting current information. It is not limited to this. For example, a current-voltage conversion circuit using a shunt resistor may be used as a circuit that outputs current information. In addition, the output voltage of the current-voltage conversion circuit may be output as it is. Furthermore, a physical quantity corresponding to the amount of current supplied to the bias wiring may be output.

The current information of the bias wiring is sent to the X-ray irradiation detection unit 150. The X-ray irradiation detection unit 150 detects the X-ray irradiation by capturing a change in the amount of current generated during the X-ray irradiation.

The bias power supply 140 also includes a refresh voltage Vr. Similarly to the bias voltage Vs, the refresh voltage Vr is also supplied to the G electrodes of the photoelectric conversion elements S11 to S33 through the bias wiring. During the refresh period of the photoelectric conversion elements S11 to S33, the refresh voltage Vr is applied to the G electrode. The voltage applied to the G electrode is controlled by the SW control circuit 142. The SW control circuit 142 controls the operation of the switch SW so that the refresh voltage Vr is applied to the G electrode in the refresh period and the bias voltage Vs is applied to the G electrode in the other periods. The AD converter 141 and the SW control circuit 142 may be included in the bias power supply 140 or may be disposed independently of the bias power supply 140.

Next, an example of the photoelectric conversion elements S11 to S33 will be described. There are two types of operation modes of the photoelectric conversion elements S11 to S33: a refresh mode and a photoelectric conversion mode.

FIG. 4 is a view schematically showing an example of a cross section of the photoelectric conversion elements S11 to S33 of the present embodiment.

Various materials are deposited and laminated on a glass substrate 130 made of an insulating substrate to form photoelectric conversion elements S11 to S33. The upper electrode 135 is formed of a transparent electrode. The lower electrode 131 is formed of Al, Cr or the like. The insulating layer 132 is formed of an amorphous silicon nitride film and blocks passage of both electrons and holes. The intrinsic semiconductor layer 133 is formed of hydrogenated amorphous silicon, generates an electron-hole pair when X-rays are incident, and operates as a photoelectric conversion layer. The impurity semiconductor layer 134 is formed of n-amorphous silicon, and operates as a hole blocking layer that blocks the injection of holes from the upper electrode 135 into the intrinsic semiconductor layer 133.

FIG. 5 is a diagram showing an example of energy bands of the photoelectric conversion elements S11 to S33. FIG. 5A is a diagram showing energy bands of the photoelectric conversion elements S11 to S33 at the time of no bias. FIG. 5B is a diagram showing an example of energy bands of the photoelectric conversion elements S11 to S33 in the photoelectric conversion mode. FIG. 5C is a diagram showing an example of energy bands of the photoelectric conversion elements S11 to S33 in a saturated state. FIG. 5D is a diagram showing an example of energy bands of the photoelectric conversion elements S11 to S33 in the refresh mode.

In the photoelectric conversion mode, as shown in FIG. 5B, a bias voltage Vs is applied between the upper electrode 135 and the lower electrode 131 so that the upper electrode 135 has a positive voltage. Electrons in the intrinsic semiconductor layer 133 are swept out of the upper electrode 135 by the bias voltage Vs. On the other hand, although holes are to be injected from the upper electrode 135 toward the intrinsic semiconductor layer 133, the impurity semiconductor layer 134 prevents the holes from being injected into the intrinsic semiconductor layer 133. Therefore, the holes can not move to the intrinsic semiconductor layer 133.

When X-rays enter the intrinsic semiconductor layer 133 in this state, electron-hole pairs are generated by the photoelectric conversion effect. Electrons and holes move in the intrinsic semiconductor layer 133 without recombination according to the electric field. As a result, electrons are swept out of the upper electrode 135, but holes are blocked by the insulating layer 132 and stay at the interface between the insulating layer 132 and the intrinsic semiconductor layer 133.

When the photoelectric conversion operation continues and holes accumulated at the interface between the insulating layer 132 and the intrinsic semiconductor layer 133 increase, the electric field applied to the intrinsic semiconductor layer 133 is weakened due to the influence. As a result, as shown in FIG. 5C, the electron-hole pair generated by the incidence of X-rays disappears by recombination without moving by the electric field, and the photoelectric conversion elements S11 to S33 have sensitivity to light. Lose. Such a state is called saturation.

In order to recover the sensitivity of the saturated photoelectric conversion elements S11 to S33, an operation called refresh is performed. In the refresh mode, as shown in FIG. 5D, a refresh voltage Vr is applied between the upper electrode 135 and the lower electrode 131 so that the lower electrode 131 has a positive voltage. In the refresh mode, holes accumulated at the interface between the insulating layer 132 and the intrinsic semiconductor layer 133 are swept out from the upper electrode 135, and instead, electrons are injected and accumulated at the interface of the insulating layer 132.

Here, when switching to the photoelectric conversion mode again, injected electrons are rapidly swept out of the upper electrode 135. As a result, the photoelectric conversion elements S11 to S33 are in a state where the bias voltage Vr is applied, and the sensitivity to light is restored.

As described above, in order for the photoelectric conversion elements S11 to S33 to maintain the sensitivity to light, it is necessary to operate the photoelectric conversion elements S11 to S33 periodically in the refresh mode. First, refreshment is required immediately after X-rays enter the photoelectric conversion elements S11 to S33. That is, when the X-ray imaging apparatus 100 irradiates X-rays and captures an X-ray image, the X-ray imaging apparatus 100 operates the photoelectric conversion element in the refresh mode to prepare for the next imaging. It is necessary to restore the sensitivity to Further, even if the X-ray is not irradiated, charges (dark current) are randomly generated inside the photoelectric conversion elements S11 to S33 due to the influence of temperature and other factors. The sensitivity to light of the photoelectric conversion elements S11 to S33 is gradually lost also by the accumulation of the charges generated at random. Therefore, it is necessary to operate the photoelectric conversion elements S11 to S33 in the refresh mode also when the X-ray non-irradiation state continues for a predetermined time or more.

During the refresh operation (reset operation), since the current signal (current information of the bias wiring) used to detect the irradiation of the X-ray can not be obtained, it is not possible to detect the irradiation of the X-ray. Further, immediately after switching from the refresh mode to the photoelectric conversion mode, the current signal is unstable, and the detection accuracy of the X-ray irradiation decreases until the current signal is stabilized. Furthermore, offset correction processing is generally performed in acquiring an X-ray image. The offset correction process is a process of removing various offset components which are superimposed on the X-ray image to reduce the image quality. The offset correction process is performed by subtracting offset image data acquired in a state in which X-rays are not irradiated from image data acquired in a state in which X-rays are irradiated.

The offset component is generated mainly by the influence of temperature or fixed noise caused by residual charge remaining based on the characteristics of the phosphor or photoelectric conversion element after the previous imaging, defects inherent to the X-ray detector, or the like. There is a dark current and the like accompanying the charge. In particular, during a fixed period immediately after the refresh mode, the change of the dark current component is often unstable, and the accuracy of the offset correction process is reduced. Therefore, the image quality of the obtained image data is degraded. Therefore, it is necessary to secure a certain preparation period before performing the next imaging after performing the refresh.

Here, for the preparation period, it is desirable to turn off the X-ray irradiation detection unit in order to suppress erroneous detection and to suppress deterioration in the image quality of the X-ray image.

However, when the X-ray irradiation detection unit is turned off during the preparation period, the X-ray irradiation is not detected when the X-ray is accidentally irradiated during the preparation period, so the patient 300 is a subject. May cause unwanted exposure. In addition, the following problems occur.

First, although the X-ray irradiation itself is not detected, charges are generated in the photoelectric conversion elements S11 to S33 in the same manner as usual, as the X-ray irradiation is performed. The charges generated by the photoelectric conversion elements S11 to S33 are gradually removed by blank reading, but the electric charges that can not be removed are accumulated in the photoelectric conversion elements S11 to S33. In this state, when the preparation period ends and imaging is performed, the residual component of the charge generated by the erroneous irradiation is superimposed on the charge generated by the imaging, which causes the image quality of the captured X-ray image to be degraded. . The blank reading will be described later with reference to FIG.

In addition, when the preparation period ends immediately after the erroneous irradiation and detection of the X-ray is started, a large amount of charge generated by the erroneous irradiation remains in the photoelectric conversion elements S11 to S33. Therefore, an X-ray image is output by the X-ray irradiation detection unit erroneously detecting the X-ray irradiation by the charge read from the photoelectric conversion elements S11 to S33 in the blank reading immediately after the erroneous irradiation. There is also the possibility. At this time, since imaging is not actually performed, the image quality of the obtained X-ray image does not reach a predetermined standard, and there is a high possibility that it can not be appropriately used for diagnosis and the like. In such a case, it is necessary for the photographer to perform, for example, an imaging process or the like on such an X-ray image. That is, the load on the photographer may be increased.

Furthermore, the photoelectric conversion elements S11 to S33 may be in a saturated state as shown in FIG. 5C due to the charge generated by the erroneous irradiation of the X-ray. When the photoelectric conversion elements S11 to S33 become saturated, the sensitivity of the pixel itself to light decreases, the saturation level to the incident X-ray (light) decreases, and the dynamic range of the X-ray image narrows, etc. The image quality of the X-ray image may be significantly degraded. Furthermore, when the photoelectric conversion elements S11 to S33 are saturated, the X-ray detection sensitivity itself also decreases. For this reason, it is not possible to accurately detect normally irradiated X-rays, and there is also a possibility of repeatedly causing invalid exposure to the patient.

For these reasons, it is desirable to detect x-ray radiation during preparation as well, to minimize ineffective exposure to the patient. On the other hand, X-ray images obtained by irradiating X-rays during the preparation period have problems with image quality. Therefore, it is desirable to shorten the preparation period as much as possible and to detect the X-ray irradiation over a long period. Therefore, in the present embodiment, when X-ray irradiation is detected during the preparation period, the photoelectric conversion elements S11 to S33 are immediately refreshed. In this embodiment, by doing this, the photoelectric conversion elements S11 to S11 are more likely to be detected when X-ray irradiation is detected during the irradiation determination period than when X-ray irradiation is detected during the preparation period. The period (accumulation period) for accumulating charges in S33 is shortened. The accumulation period when X-ray irradiation is detected during the preparation period is preferably as close to 0 (zero) as possible.

Here, the fixed period after the refresh operation is the first period (the preparation period for receiving the irradiation of the X-ray in the two-dimensional imaging device 120) during which the irradiation of the X-ray is not recommended. This is a second period (irradiation determination period) in which irradiation of a line is recommended. In the present embodiment, a period until the state of the X-ray imaging apparatus 100 is stabilized or a period until the state of the X-ray imaging apparatus 100 is assumed to be stable is referred to as a preparation period. The state of the X-ray imaging apparatus 100 is stabilized by the preparation of imaging at the X-ray imaging apparatus 100 side and the state of the X-ray imaging apparatus 100 transitioning to a state where the image quality of the X-ray image is sufficiently ensured. become. On the other hand, the irradiation determination period refers to a period during which X-ray irradiation is recommended. In this embodiment, an X-ray image having a desired image quality can be obtained (or a desired image quality can be obtained if X-ray irradiation is detected during a period after the preparation period ends as an irradiation determination period and X-ray irradiation is detected during this period. It is assumed that an X-ray image can be obtained.

In the present embodiment, the control unit 160 determines the start and end of the preparation period. In response to the end of the preparation period, the control unit 160 causes the communication circuit 180 to transmit a signal indicating that the preparation period has ended to the imaging information processing apparatus 400. The control unit 401 of the imaging information processing apparatus 400 having received such a signal indicates that the display of the state of the X-ray imaging apparatus 100 displayed on the display unit 410 is in the preparation completion state from the display indicating the unprepared state. Change to display. Here, the indication indicating the ready state is a indication indicating that the X-ray detector 110 is ready to receive X-ray irradiation. When the X-ray imaging apparatus 100 transmits such a signal, when the imaging information processing apparatus 400 receives it, or when such a display is performed, a first period during which X-ray irradiation is not recommended and an X-ray You may switch with the 2nd period when irradiation is not recommended.

The start and end of the preparation period may be determined by the control unit 401 of the imaging information processing apparatus 403. In this case, the control unit 160 of the X-ray imaging apparatus 100 outputs, for example, a signal indicating the start of the preparation period. The control unit 401 of the imaging information processing apparatus 403 displays that the status display of the X-ray imaging apparatus 100 displayed on the display unit 410 is not ready in response to the elapse of a predetermined period from the reception of the signal. Is changed to a display indicating that the preparation is completed. In another example, when the control unit 401 of the imaging information processing apparatus 403 instructs the start of the preparation period, reception of the status signal from the X-ray imaging apparatus 100 becomes unnecessary except in the case where a problem occurs. . In this case, the control unit 401 causes a state display of the X-ray imaging apparatus 100 displayed on the display unit 410 to be in the preparation complete state from the display indicating the unprepared state in response to the passage of a predetermined period from the instruction. Change to a display that indicates that there is.

FIG. 6 is a timing chart showing an example of drive timing of the X-ray detector 110. As shown in FIG. FIG. 6 shows the drive timing of the X-ray detector 110 from the middle of the irradiation detection drive (blank read drive).

The blank read drive is a drive that turns on the switch elements T11 to T33 in a row unit to conduct current sequentially from the top row (y = 0) to the last row (y = m). The blank read drive is performed to remove the charge due to the dark current generated in the photoelectric conversion elements S11 to S33. The blank reading drive is repeated at a constant cycle until X-ray irradiation is detected. During this time, the voltage Vb of the bias line is always kept at the bias voltage Vs.

When X-rays are irradiated to the X-ray detector 110, the amount of charge read out by blank reading (current flowing through the bias wiring) increases. Therefore, X-ray irradiation start is observed by observing changes in current during blank reading. Can be detected. The current information of the bias wiring is input to the X-ray irradiation detection unit 150, and the start of the X-ray irradiation is detected. The X-ray irradiation detection unit 150 can determine, for example, whether or not the peak value of the current flowing through the bias wiring exceeds a predetermined threshold, and can detect the start of X-ray irradiation if it exceeds. In addition, the X-ray irradiation detection unit 150 performs time integration of the current flowing through the bias wiring, and determines whether the integral value (total amount of charge) exceeds a predetermined threshold value. The start can be detected.

When the X-ray irradiation start is determined, the blank reading drive is stopped at that point (in FIG. 6, the X-ray irradiation start is detected in the i-th row), and the operation shifts to an operation of accumulating charge. During charge accumulation, all the switch elements T11 to T33 are turned off. When a predetermined time has elapsed and charge accumulation is completed, the process proceeds to the main reading. This reading is performed by turning on the switch elements T11 to T33 in row units sequentially from the first row (y = 0) to the last row (y = m).

When the main reading is finished, the refresh operation is continued. The refresh operation is performed by setting the voltage Vb of the bias line to the refresh voltage Vr. At this time, at this time, the refresh may be simultaneously performed on the photoelectric conversion elements S11 to S33 of all the lines, or the refresh may be performed in order. Alternatively, a plurality of two-dimensional matrix pixels (photoelectric conversion elements) may be divided into several blocks, and the refresh operation may be performed for each block. When the refresh operation is completed, blank reading is started again.

Here, blank reading is performed as a preparation period during which X-ray irradiation is not recommended for a certain period after the refresh operation. After the preparation period has elapsed, the blank drive is continued as it is, and X-ray irradiation becomes a recommended irradiation determination period. In the preparation period, X-ray irradiation may not be permitted. In addition to or instead of the period after such a refresh operation, the period immediately after the start of the X-ray imaging apparatus 100 may be set as the preparation period.

For example, the X-ray irradiation detection unit 150 is off from the start of the accumulation period to the end of the refresh operation, and is on in the other periods.

The length of the preparation period may be set arbitrarily within the range that guarantees the image quality of the X-ray image and the like, and is set to, for example, 10 seconds. Thus, regardless of whether or not the state of the X-ray imaging apparatus 100 is actually stable, it may be a period in which the state of the X-ray imaging apparatus 100 is assumed to be stable. Of course, a period during which the state of the X-ray imaging apparatus 100 is actually stabilized may be set as the preparation period. The length of the preparation period may be the same or different immediately after activation of the X-ray imaging apparatus 100 and immediately after the refresh operation. Further, the length of the preparation period may be set collectively at the start of the X-ray imaging apparatus 100 and immediately after the refresh operation, or may be set individually. Furthermore, for example, by monitoring the state of the current signal of the bias wiring using the X-ray irradiation detection unit 150, it is possible to set a period until the current signal of the bias wiring is sufficiently stabilized as a preparation period. is there. That is, it is also possible to automatically switch the preparation period according to the current signal of the bias wiring. The degree of stability of the current signal of the bias wiring may be set arbitrarily in consideration of the image quality and the like required for the X-ray image. By doing this, for example, when residual charge is present more than expected due to, for example, irradiation of a high dose at the time of immediately preceding imaging, deterioration of the image quality of the X-ray image due to afterimage etc. by setting a sufficient preparation period. Can be effectively prevented.

FIG. 7 is a flowchart illustrating an example of processing in the X-ray imaging apparatus 100. When the X-ray imaging apparatus 100 and the X-ray generation apparatus 200 are started up, respectively, at the start of X-ray imaging, the flowchart of FIG. 7 starts.

In step S701, the X-ray imaging apparatus 100 (drive circuit 165) starts the idle reading drive immediately after startup. Alternatively, the refresh operation may be performed once after startup, and then the blank read drive may be started.

Next, when blank drive is started, the X-ray imaging apparatus 100 (X-ray irradiation detection unit 150) starts detection of X-ray irradiation in step S702. When detection of X-ray irradiation is started, in step S703, the X-ray imaging apparatus 100 (X-ray irradiation detection unit 150) is irradiated with X-rays based on the change in current flowing in the bias wiring generated by the X-ray irradiation It is determined whether or not. As described above, this determination can be realized by comparing the peak value or the time integral value of the current of the bias wiring with the threshold value.

As a result of this determination, when the X-ray irradiation is not detected, the blank reading drive is continued. On the other hand, when the X-ray irradiation is detected, in step S704, the X-ray imaging apparatus 100 (control unit 160) determines whether or not the timing is within the timing preparation period in which the X-ray irradiation is detected. .

As a result of this determination, when it is determined that the timing at which the X-ray irradiation is detected is a timing other than the preparation period, the process proceeds to step S705.

In step S 705, the X-ray imaging apparatus 100 (drive circuit 165) stops the blank reading drive, and shifts to a mode for accumulating charges generated in the two-dimensional imaging element 120 by X-ray irradiation. The charge may be accumulated for a predetermined time, or the end of the X-ray irradiation may be detected, and the timing of ending the charge accumulation may be controlled based on the detected result. When the charge storage is completed, in step S706, the X-ray imaging apparatus 100 (readout circuit 170) reads the charge stored in the two-dimensional imaging device 120 (performs a main reading). Image data obtained by the main reading is transmitted to the photographing information processing apparatus 400. The timing of transmitting the image data to the imaging information processing apparatus 400 may be the timing of step S706 or the timing after step S706.

Then, when at least the main reading is completed, the process proceeds to step S 707, and the X-ray imaging apparatus 100 (drive circuit 165) performs a refresh operation to restore the sensitivity of the photoelectric conversion elements S 11 to S 33. Thereafter, in step S 708, the X-ray imaging apparatus 100 (control unit 160) determines whether or not the imaging of the X-ray image is to be ended based on an operation or the like by the photographer. As a result of this determination, when the imaging of the X-ray image is not finished, the blank reading drive is started again. On the other hand, when the imaging of the X-ray image is ended, the processing according to the flowchart of FIG.

If it is determined in step S704 that the timing is within the timing preparation period in which the X-ray irradiation is detected, steps S705 and S706 are omitted and the process proceeds to step S707. That is, the refresh operation is immediately performed without the charge accumulation and the real reading. By doing this, the influence of the X-rays irradiated during the preparation period remains at the time of the next imaging, and the image quality of the X-ray image and the detection sensitivity of the X-rays can be effectively prevented from decreasing. it can.

At this time, the control unit 160 can transmit information indicating that X-ray irradiation has been performed at an inappropriate timing to the imaging information processing apparatus 400 via the communication circuit 180. Based on this information, the control unit 401 of the imaging information processing apparatus 400 displays on the display unit 410 a warning message indicating that X-ray irradiation has been performed at an inappropriate timing, and warns the photographer. It is also good.

As described above, in the present embodiment, when it is detected that X-rays are irradiated during a preparation period starting from the start of the refresh of the photoelectric conversion element (or the start of the X-ray imaging apparatus 100), The refresh operation was immediately performed. Therefore, the preparation period (period in which the state of the X-ray imaging apparatus 100 is not stable) can be shortened, and preparation for the next imaging can be made. Therefore, false detection in the preparation period can be suppressed, X-ray images to be provided for diagnosis can be efficiently taken, and useless exposure of the subject 300 can be suppressed. In particular, in an X-ray imaging system capable of imaging without electrically connecting the X-ray imaging apparatus 100 and the X-ray generation apparatus 200, X-ray irradiation is performed during the preparation period of the X-ray imaging apparatus 100. It is possible to suppress the inconvenience that occurs in the case of

In the present embodiment, when it is detected that X-rays are irradiated in the preparation period, the refresh operation is performed immediately. However, the period during which charge is accumulated in the photoelectric conversion elements S11 to S33 when the X-ray irradiation is detected during the irradiation determination period is longer than when the X-ray irradiation is detected during the preparation period (storage This may not be necessary as long as the period is shortened. For example, the refresh operation may be performed on the photoelectric conversion elements S11 to S33 at a timing when a predetermined time has elapsed after detection of X-ray irradiation during the preparation period. Even in this case, it is preferable to perform the refresh operation on the photoelectric conversion elements S11 to S33 as the first operation of the drive circuit 165 after detecting the X-ray irradiation during the preparation period.

Further, in the present embodiment, the case where the accumulated value of the current signal flowing from the photoelectric conversion elements S11 to S33 to the bias wiring by the X-ray irradiation is compared with the threshold has been described as an example. However, as long as the physical quantity that changes in the X-ray detector 110 due to the X-ray irradiation is compared with the threshold, it is not necessary to compare the accumulated value of the current signal flowing in the bias wiring with the threshold. Further, the relationship between the rows and the columns in the two-dimensional imaging device 120 may be reversed. That is, readout of pixel signals in units of columns by the readout circuit 170 may be performed in units of rows, and driving of pixels in units of rows by the drive circuit 165 may be performed in units of columns.

Second Embodiment
Next, a second embodiment of the present invention will be described. In the first embodiment, the refresh operation is always performed when it is detected during the preparation period that the X-rays have been irradiated. On the other hand, in the present embodiment, if it is detected that X-rays have been irradiated from the start of the preparation period until the predetermined condition is satisfied, the refresh is performed as described in the first embodiment. Do the action. On the other hand, when it is detected that X-rays are irradiated after a predetermined condition is satisfied after the preparation period starts, as usual, charge accumulation and main reading are performed, and then the refresh operation is performed. However, in this case, the X-ray image (image data) obtained in this manner and information indicating that the X-ray image is obtained during the preparation period are transmitted to the imaging information processing apparatus 400, The imaging information processing apparatus 400 displays the information. As described above, this embodiment and the first embodiment are different in part of the processing when X-rays are irradiated in the preparation period, and are mainly different in configuration resulting from the part of the processing being different. Therefore, in the description of the present embodiment, the same parts as those of the first embodiment will be denoted by the same reference numerals as those of FIGS. 1 to 7, and the detailed description will be omitted.

FIG. 8 is a diagram showing an example of the configuration of the X-ray imaging apparatus 800. As shown in FIG.

The X-ray imaging apparatus 800 of this embodiment is different from the X-ray imaging apparatus 100 shown in FIG. 2 in that an image storage unit 190 is provided between the image processing unit 175 and the communication circuit 180. The other configuration of the X-ray imaging apparatus 800 is the same as that of the X-ray imaging apparatus 100 shown in FIG.

The image storage unit 190 is for storing at least one photographed image data (X-ray image) and various information attached thereto. For example, a semiconductor memory device, a hard disk drive or the like can be suitably used as the image storage unit 190.

In the present embodiment, the image data read from the X-ray detector 110 by the reading circuit 170 is stored in the image storage unit 190 after being subjected to image processing by the image processing unit 175. The image storage unit 190 has a storage capacity capable of storing at least one piece of image data. The image data that has been stored in the image storage unit 190 is transmitted to the external imaging information processing apparatus 400 via the communication circuit 180. Specifically, the image data is transmitted when the main reading is finished and can be transmitted to the external photographing information processing apparatus 400.

At this time, while the image data may be stored, transmission to the imaging information processing apparatus 400 may be simultaneously performed, but all image data is transmitted to the image storage unit 190 until all the image data is successfully transmitted. It is desirable to keep it. When a part of the image data can not be transmitted due to a poor communication condition or the like, and an accurate X-ray image can not be reproduced (displayed) by the external imaging information processing apparatus 400, the image data is resent, etc. Because you can do it.

If the image data is obtained after a predetermined condition has elapsed since the start of the preparation period, the control unit 160 adds detection timing information indicating that to the header to the image data. The detection timing information may not necessarily be added to the header. For example, the detection timing information may be embedded in the image data, or the detection timing information may be stored and transmitted in a file different from the file of the image data. The detection timing information is, for example, information indicating the time from the end of the refresh driving to the detection of the X-ray (the time from the start of the preparation period to the detection of the X-ray).

The control unit 401 of the imaging information processing apparatus 400 determines whether detection timing information is added to the image data. If detection timing information is added to the image data as a result of this determination, the control unit 401 of the imaging information processing apparatus 400 performs the following processing. That is, when the control unit 401 of the imaging information processing apparatus 400 displays the image data on the display unit 410, the image data is obtained by irradiating X-rays during the preparation period. Is displayed on the display unit 410 at the same time. Specifically, for example, the message is displayed superimposed on the image data (the message is pop-up displayed for the image data). Such a message may include information indicating the time after the end of the refresh driving (the time after the preparation period starts).

By displaying the message as described above, the photographer can use the obtained image data for diagnosis and the like within a range without any problem. This can reduce unnecessary exposure to the patient.

FIG. 9 is a flowchart illustrating an example of processing in the X-ray imaging apparatus 800. When the X-ray imaging apparatus 800 and the X-ray generation apparatus 200 are activated at the start of X-ray imaging, the flowchart of FIG. 9 is started.

The contents of the processes in steps S901 to S908 in FIG. 9 are the same as those in steps S701 to S708 in FIG.

The difference between the flowchart of FIG. 9 and the flowchart of FIG. 7 is the process after it is determined in step S904 that the timing at which the X-ray irradiation is detected is the timing within the preparation period.

If it is determined in step S904 that the timing at which the X-ray irradiation is detected is the timing within the preparation period, the process proceeds to step S909. In step S 909, the control unit 160 determines whether the timing at which the X-ray irradiation has been detected is within one second after the preparation period starts.

As a result of the determination, if the timing at which the X-ray irradiation is detected is within one second after the start of the preparation period, the process proceeds to step S 907, and charge accumulation and processing are performed as in the first embodiment. The refresh operation is immediately performed without the actual reading.

On the other hand, if the timing at which the X-ray irradiation is detected is not within one second after the start of the preparation period, the process proceeds to step S 910. In step S910, the control unit 160 generates detection timing information. As described above, the detection timing information is, for example, information indicating the time from the end of the refresh driving to the detection of the X-ray (the time from the start of the preparation period to the detection of the X-ray).

Next, in step S911, the X-ray imaging apparatus 100 (drive circuit 165) stops the blank reading drive, and shifts to a mode for accumulating charges generated in the two-dimensional imaging element 120 by X-ray irradiation. The process of step S911 is the same as the process of step S905. When the storage of the load is completed, in step S912, the X-ray imaging apparatus 100 (readout circuit 170) reads out the charge stored in the two-dimensional imaging device 120 (performs the main reading). The actual reading operation itself of step S912 is the same as the process of step S906. However, in step S912, the detection timing information generated in step S910 is also transmitted to the imaging information processing apparatus 400 together with the image data obtained by the main reading. The timing of transmitting the image data and the detection timing information to the imaging information processing apparatus 400 may be the timing of step S912 or the timing after step S912. Then, when at least the main reading is completed, the process proceeds to step S 907.

As described above, in the present embodiment, the refresh operation is performed as soon as it is detected that X-rays have been emitted within one second after the start of the preparation period. On the other hand, when it is detected that X-rays have been irradiated after 1 second has passed since the start of the preparation period, as usual, charge accumulation and main reading are performed, and then the refresh operation is performed. Then, the X-ray image (image data) thus obtained and detection timing information indicating that the X-ray image is obtained during the preparation period are transmitted to the imaging information processing apparatus 400, and the imaging information processing apparatus 400 The detection timing information is displayed on the device 400.

When a certain period of time has passed since the start of the preparation period, the state of the X-ray imaging apparatus 100 approaches a stable state, so diagnosis of an X-ray image obtained in such a state is Make it possible to However, since such an X-ray image is obtained during a period in which the X-ray irradiation is not recommended, this is notified. Thus, the image reader can read the X-ray image after recognizing that the X-ray irradiation is not recommended. Therefore, for example, if diagnosis is possible with the X-ray image, it is not necessary to obtain the X-ray image again. On the other hand, the state of the X-ray imaging apparatus 100 is unstable during a period immediately after the start of the preparation period. Therefore, in the present embodiment, the X-ray image obtained at such timing is highly likely not to be suitable for diagnosis, as in the first embodiment, the preparation period (the state of the X-ray imaging apparatus 100 Short) and prepare for the next shooting. As described above, in the present embodiment, it is possible to further suppress unnecessary exposure to the subject 300.

In the present embodiment, it was determined whether or not X-rays were irradiated within 1 second after the preparation period started. However, if it is determined whether or not a predetermined condition is satisfied after the start of the preparation period, this is not necessarily the case. For example, a time other than one second may be employed. Further, for example, it may be determined whether or not the change in the amplitude of the current signal of the bias wiring at a predetermined time before the timing at which the X-ray irradiation is detected is within a predetermined range.

Further, in the present embodiment, detection timing information is added only to image data based on X-rays detected within one second after the preparation period starts. However, this is not necessarily the case, and detection timing information may be added to all image data.

Also, in the present embodiment, the case where the message based on the detection timing information is superimposed and displayed on the image data has been described as an example. However, the method of displaying the detection timing information on the display unit 410 of the imaging information processing apparatus 400 is not limited to such a method.

For example, when detection timing information is added to image data, the control unit 401 of the imaging information processing apparatus 400 may display a message based on the detection timing information on the display unit 410 without displaying the image data. Good. As described above, such a message may include information indicating the time after the end of the refresh driving (the time after the preparation period starts). When only the message is displayed as described above, the control unit 401 of the photographing information processing apparatus 400 displays the image data after the photographer instructs to display the image data based on the operation of the operation unit 430. Can.

Also, messages based on the detection timing information may be displayed in parallel on one screen of the display unit 410 without overlapping the image data. In particular, when the detection timing information added to the image data obtained in the irradiation determination period, not in the preparation period, is displayed, it is preferable to do so because it is not necessary to warn the reader of the hardness. Further, the method of displaying the detection timing information may be different depending on whether the image data obtained in the preparation period is displayed or the image data obtained in the irradiation determination period is displayed.

In addition, it is not necessary to determine whether a predetermined condition is satisfied after the preparation period starts. In this case, the processes of steps S904 to S907 and S909 in FIG. 9 become unnecessary. That is, when the timing at which the X-ray irradiation is detected is the timing within the preparation period, the detection timing information and the image data are transmitted to the imaging information processing apparatus 400 without fail.

Further, for example, due to a communication failure, communication between the X-ray imaging apparatus 100 and the imaging information processing apparatus 400 is interrupted, or some operation (for example, correction of information of a captured X-ray image) is performed by the imaging information processing apparatus 400. If it is, it may be included in the preparation period. That is, a state where an appropriate photographing can not be performed for some reason is defined as a preparation period, and when the image is photographed at such a timing, information indicating that is added to the image data. Just do it. For example, information indicating the communication state between the X-ray imaging apparatus 100 and the imaging information processing apparatus 400 may be added to the image data and displayed as one of the detection timing information.

Also in the present embodiment, various modifications described in the first embodiment can be adopted.

As described in the above embodiments, a PIN type photodiode can be used. In this case, in the case of an imaging device of one transistor as shown in FIG. 3, the reset drive can be substituted by the output of the charge by the switch elements T11 to T33, and the refresh operation becomes unnecessary. Therefore, in one embodiment, the reset driving is the same as the blank reading (output driving).

In another embodiment, the reset driving is to make the on time of the switch element longer than the blank reading. Since the blank reading (output driving) is driving according to the detection of the X-ray by the X-ray irradiation detection unit 150, it is not necessarily implemented in the aspect of the discharge function of the charge accumulated in the photoelectric conversion element. .

In detection of X-rays based on the current flowing through the bias line Vb, artefacts or image defects due to the time lag between the timing when X-ray irradiation is actually started and the timing when X-ray irradiation start is detected Such defects have a line-like or band-like shape extending in the row direction. Such defects should be corrected in the subsequent processing, but it is necessary to suppress the size of image defects in each line in terms of facilitating the correction processing. From this point of view, the on time of the switch element in blank reading (output drive) is determined. Therefore, the on time is set to be shorter than at least the drive of the main reading.

From the above point of view, it was detected that X-rays were irradiated in a period (period in which X-ray irradiation is not recommended, “preparation period” in FIG. 6) other than the regular imaging period (“irradiation determination period” in FIG. 6) For the subsequent reset drive, the drive circuit 165 discharges the charge by controlling the signal of Vg (i) in FIG. 6, for example, to make the on time of the switch element longer than the blank reading in the irradiation determination period. The efficiency can be increased, and the imaging device can be stabilized earlier. In the example of FIG. 6, in the case of the PIN type sensor, the on-time of the switch element is not read long during the refresh period. Detection of the start of X-ray irradiation in this period may increase the size of the defect generated in each line of the image, but since it is a period during which image quality is not stable initially, it can be an image that can not be used for diagnosis The problem is small.

According to this embodiment, when the false exposure is detected, the drive circuit 165 continues the idle reading drive without putting the imaging device 120 in the accumulation state.

In the above embodiment, for example, the functions of the imaging control apparatus (imaging information processing apparatus) 107 may be distributed to a plurality of apparatuses that can communicate with each other to realize the functions of the imaging control apparatus (imaging information processing apparatus) 107 as a control system. It may be For example, there is an example in which some functions such as image processing are provided to an external server. Such an external server may be disposed in an imaging room or an operation room in which an X-ray imaging system performing tomosynthesis imaging is placed and connected by a dedicated LAN, or may be disposed in a hospital and communicated by an in-hospital LAN. It is also good. Alternatively, it may be arranged in a data center outside the hospital regardless of whether it is domestic or foreign, and may exchange data with each other by secure communication such as VPN.

The embodiments described above are merely examples of implementation for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner by these. That is, the present invention can be implemented in various forms without departing from the technical concept or the main features thereof.

(Other embodiments)
The present invention is also realized by performing the following processing. That is, first, software (computer program) for realizing the functions of the above embodiments is supplied to a system or apparatus via a network or various storage media. Then, a computer (or a CPU or MPU or the like) of the system or apparatus reads out and executes the computer program.

The present invention is not limited to the above embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the following claims are attached to disclose the scope of the present invention.

The present application claims priority based on Japanese Patent Application No. 2013-226016 filed on October 30, 2013, the entire contents of which are incorporated herein by reference.

Claims

A radiation imaging apparatus (100) for detecting that radiation irradiation has been started (150),
An imaging device (120) including a plurality of photoelectric conversion devices (S11 to S33);
A drive circuit (165) for performing an operation of outputting an electrical signal based on the charge accumulated in the plurality of photoelectric conversion elements;
A readout circuit (170) for obtaining image data based on the electrical signal;
When it is detected that radiation irradiation has been started during a period when preparation for X-ray imaging of the radiation imaging apparatus is completed, the plurality of photoelectric conversion elements are stored according to the detection. After that, it has a control circuit (160) for performing a readout operation of reading out an electrical signal based on charges obtained in the storage state and acquiring image data, and thereafter performing reset drive of the imaging element after the readout operation. ,
When it is detected that the irradiation of the radiation is started in a period different from the period, the control circuit causes the reset drive to be performed without performing the reading operation. apparatus.
When it is detected that the irradiation of radiation is started in the preparation completion period, the control circuit puts the photoelectric conversion element in the accumulation state, and then the readout in response to the end of the accumulation state. Make it work,
When it is detected that the irradiation of radiation is started in the different period, the control circuit puts the photoelectric conversion element in the accumulation state, and then performs reset driving of the imaging element in accordance with the end of the accumulation state. The radiation imaging apparatus according to claim 1, wherein the radiation imaging apparatus comprises:
The period in which the preparation is completed is at least a period from the end of the reset drive to the establishment of a predetermined condition and a period from the activation of the radiation imaging apparatus to the establishment of the predetermined condition. The radiation imaging apparatus according to claim 2, which is one of the periods.
The radiation imaging apparatus according to claim 3, wherein the predetermined condition is whether or not a predetermined time has elapsed.
An imaging element (120 in which a plurality of pixels (125) each including the photoelectric conversion element and a switch element (T11 to T33) connected to one terminal of the photoelectric conversion element are arranged in a two-dimensional matrix. )When,
A power supply (140) for supplying a voltage to a bias wire (Vb) commonly connected to the other terminal of the plurality of photoelectric conversion elements arranged in the same row or column;
The radiation imaging apparatus according to claim 3, wherein the predetermined condition is determined based on a current flowing through the bias wiring.
6. The control circuit according to claim 1, wherein, when it is detected that the irradiation of radiation has been started in the different period, the control circuit causes a reset drive to be performed after the detection. The radiography apparatus described in.
In the different period, a period from the end of the reset driving to the stabilization of the operation of the radiation imaging apparatus, and a period from the activation of the radiation imaging apparatus to the stabilization of the operation of the radiation imaging apparatus The radiation imaging apparatus according to claim 6, which is at least one period.
The said drive means performs the said reset drive immediately after the said detection, when it is detected that irradiation of the said radiation was started in the said different period, The 1st term in any 1 item Radiographic apparatus as described.
Acquisition means for acquiring detection timing information when it is detected that irradiation of the radiation has been started after a predetermined condition is satisfied in the different periods;
An output of outputting an image based on radiation of which start of irradiation has been detected after a predetermined condition is satisfied in the different period, and detection timing information acquired by the acquisition unit to an information processing apparatus outside the radiation imaging apparatus Means, and
When it is detected that the irradiation of the radiation has been started before the predetermined condition is satisfied in the different periods, the driving means detects that the irradiation of the radiation has been started in the different periods. The radiation imaging apparatus according to any one of claims 1 to 8, wherein the reset drive is started earlier than timing.
10. The radiation imaging apparatus according to claim 9, wherein the detection timing information includes information of time since the start of the different period.
The control circuit causes the drive circuit to repeatedly perform output driving that causes the charge accumulated in the plurality of photoelectric conversion elements to be output.
The control circuit further stops the output driving in response to detection of the start of the irradiation of the radiation during a period different from the period, causing the plurality of photoelectric conversion elements to be in the accumulation state, and the accumulation. The radiation imaging apparatus according to any one of claims 1 to 10, wherein reset driving of the imaging element is performed according to the end of the state.
The control circuit causes the drive circuit to repeatedly perform output driving that causes the charge accumulated in the plurality of photoelectric conversion elements to be output.
The control circuit further causes the output drive to be continuously performed when it is detected that the irradiation of the radiation has been started in a period different from the period, and at least a start of the next irradiation is detected. The radiographing apparatus according to any one of claims 1 to 10, wherein the reading operation is not performed until the time t1.
The radiation imaging apparatus according to claim 12, wherein the output drive is the same drive as the reset drive.
The imaging device includes a plurality of photoelectric conversion devices arranged in a matrix.
A drive signal line (g1-g3) which is commonly provided to a plurality of photoelectric conversion elements arranged in a row direction and transmits signals of the drive circuit;
An output signal line (s1-s3) which is commonly provided to a plurality of photoelectric conversion elements arranged in the column direction and which outputs an electrical signal based on the charge accumulated in the photoelectric conversion elements;
A switch element (T11 to T33) provided for each of the photoelectric conversion elements and controlled by a signal transmitted by the drive signal line, for connecting or not connecting the photoelectric conversion element and the output signal line The radiography apparatus according to any one of claims 1 to 13, comprising
The drive circuit controls signal output such that a period in which each of the switch elements is in the connection state is longer in the reset drive than a period in which each of the switch elements is in the connection state in the output drive. The radiation imaging apparatus according to claim 14, characterized in that:
The drive circuit controls signal output such that a period in which each of the switch elements is connected is longer in the read operation than a period in which each of the switch elements is connected in the output drive. The radiation imaging apparatus according to claim 14, characterized in that:
An information processing apparatus capable of communicating with the radiation imaging apparatus according to claim 9 or 10, comprising:
An information processing apparatus comprising: display means for displaying information based on detection timing information outputted by the output means on a display device.
The information processing apparatus according to claim 17, wherein the display unit displays information based on the detection timing information output by the output unit and an image corresponding to the detection timing information on one screen.
The display means is
After the detection timing information is displayed on the display device without displaying the image corresponding to the detection timing information output by the output unit, the user may perform the operation to display the image on the display device. The information processing apparatus according to claim 17, characterized in that:
A radiation imaging apparatus (100) for detecting that radiation irradiation has been started (150),
An imaging device (120) including a plurality of photoelectric conversion devices (S11 to S33);
A drive circuit (165) for performing an operation of outputting an electrical signal based on the charge accumulated in the plurality of photoelectric conversion elements;
A readout circuit (170) for obtaining image data based on the electrical signal;
When the start of radiation irradiation is detected in a first period, which is a period in which preparation for X-ray imaging of the radiation imaging apparatus is completed, the plurality of photoelectric conversion elements are accumulated according to the detection. After the state is set, an electric signal based on the charge obtained in the storage state is read out to perform a read operation to obtain image data, and at least a part of a second period different from the first period It has a control circuit (160) which does not perform the reading operation when the start of radiation irradiation is detected;
The control circuit is configured to store the plurality of photoelectric conversion elements in response to the detection when the start of the radiation irradiation is detected in a period different from the partial period of the second period. And the read operation is performed.
In the case where the start of radiation irradiation is detected in a period different from the partial period of the second period, the fact that the start of irradiation of the radiation is detected in the second period is 21. The radiation imaging apparatus according to claim 20, further comprising a communication circuit (180) for outputting the information to be shown and the image data obtained by the reading operation to the outside.
A radiation imaging apparatus (100) for detecting that radiation irradiation has been started (150),
And d) a drive circuit (150) for performing an operation of outputting the charges accumulated in the plurality of photoelectric conversion elements (S11 to S33),
When it is detected that the irradiation of the radiation has been started during a period when the preparation for X-ray imaging of the radiation imaging apparatus is completed, the drive circuit is configured to perform the plurality of operations for a predetermined time according to the detection. After putting the photoelectric conversion element in the storage state into the storage state, the output of the charge stored in the storage state is started,
When it is detected that the irradiation of the radiation is started in a period different from the period, the plurality of photoelectric conversion elements are put in the accumulation state for a time shorter than a predetermined time according to the detection, or A radiation imaging apparatus characterized by starting output of accumulated charges in the accumulation state without setting the state.