JP2013188245A - Radiographic system and drive controlling method therefor, and radiation image detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a useless exposure of a body to be examined when such mistakes as forgetting of setting or a mix-up of a radiation image detecting apparatus occur.SOLUTION: A first comparator circuit 75 of a radiation determining/AEC part 52 compares a dose detecting signal from a detecting element of FPD with a radiation determination threshold value. When the dose detecting signal exceeds the radiation determination threshold value within a time set by a time setting circuit 78, the first comparator circuit 75 determines that an X-ray is surely emitted toward the FPD. When the dose detecting signal does not exceed the radiation determination threshold value within the time set by the time setting circuit 78, the first comparator circuit 75 determines that an X-ray is not emitted toward the FPD caused by mistake of setting of an electron cassette, and outputs a radiation stopping signal. The radiation stopping signal is transmitted from a radiation signal I/F82 toward the radiation signal I/F of a radiation source controlling apparatus. The irradiation of X-ray is stopped thereby.

Description

  The present invention relates to a radiation imaging system, a drive control method thereof, and a radiation image detection apparatus.

  In the medical field, X-ray imaging systems using radiation, such as X-rays, are known. An X-ray imaging system includes an X-ray source that irradiates an X-ray toward a subject (patient), an X-ray image detection apparatus that receives an X-ray transmitted through the subject and detects an X-ray image, an X-ray source and an X-ray source A control device for controlling the drive of the line image detection device and an irradiation switch for inputting an X-ray irradiation start instruction.

  In the recent field of X-ray imaging systems, X-ray image detection apparatuses using a flat panel detector (FPD) as a detection panel are widely used in place of X-ray films and imaging plates (IP). In the FPD, pixels that accumulate signal charges corresponding to the X-ray arrival dose are arranged in a matrix. The FPD accumulates signal charge for each pixel, converts the accumulated signal charge into a voltage signal by a signal processing circuit, detects an X-ray image representing the image information of the subject, and uses this as digital image data Output.

  An electronic cassette (portable X-ray image detection apparatus) in which an FPD is built in a rectangular parallelepiped housing has also been put into practical use. Unlike the type that cannot be removed because the electronic cassette is installed on the photographic stand, it can be used detachably attached to an existing photographic stand for film cassettes and IP cassettes or a dedicated photographic stand. It is used by placing it on a bed or holding it on the subject itself in order to take an image of a particular part. In addition, in order to take pictures of elderly people who are being treated at home or those who are suddenly ill due to accidents, disasters, etc., they may be taken out of hospitals where there is no equipment for taking pictures.

  By the way, in hospitals, a single electronic cassette is used for both standing and lying positions, or two electronic cassettes are used for standing and lying positions. I do. In many cases, a film cassette or an IP cassette is also used. Some relatively large hospitals have purchased several spare electronic cassettes in consideration of the failure of taking pictures due to a malfunction.

  In this situation, if all the settings are left to an operator such as a radiologist, for example, the user may take a picture without attaching the electronic cassette to the imaging stand (forget to set), or choose to use the electronic cassette for standing position photography. There is always a possibility that an artificial setting mistake such as irradiating an X-ray on an electronic cassette for the supine photography in the state (misunderstanding) will occur. If a set mistake occurs, the imaging becomes invalid and the subject is exposed to unnecessary exposure.

  If the X-ray accumulated dose reaches a desired value, it does not have an automatic exposure control (AEC) function that stops the X-ray irradiation. Because there is no, it is very dangerous. Even if it has an AEC function, the maximum irradiation time is set as an imaging condition in the X-ray source, and X-ray irradiation is continued until the maximum irradiation time elapses, so that the subject is unnecessarily exposed. That is no different.

  Therefore, conventionally, as in the inventions described in Patent Documents 1 and 2, the ID of the cassette selected for use and the ID of the cassette that is actually used are collated, and if both IDs cannot be collated, X-ray irradiation is prohibited. This prevents the subject from being exposed to unnecessary exposure due to a set mistake. Alternatively, as in the invention described in Patent Document 3, it is detected whether or not the cassette corresponding to the selected imaging mode is directed to the X-ray source, and if not, the fact is notified and imaging is prohibited. doing.

JP 2002-336225 A JP 2009-045432 A JP 2009-207519 A

  However, no matter how much a set mistake is prevented as in Patent Documents 1 to 3, the mechanism itself that prevents the set mistake is not working properly, or the operator overlooks the warning display even if it works normally. For example, set mistakes will still occur. For this reason, the danger that the subject is exposed to unnecessary exposure after all cannot be wiped out.

  The present invention has been made in view of the above problems, and a radiography system capable of avoiding unnecessary exposure of a subject when a forgetting to set a radiological image detection apparatus or a mistake in mixing occurs. An object of the present invention is to provide a drive control method and a radiation image detection apparatus.

  In order to achieve the above object, a radiation imaging system of the present invention includes a radiation source that irradiates a subject with radiation, a radiation source control device that controls driving of the radiation source, and a charge corresponding to the radiation dose. A radiation image detection device having a detection panel in which pixels for storing the image are arranged and communicating various signals with the radiation source control device via a communication means, and an irradiation detection sensor for detecting whether or not the detection panel is irradiated with radiation , A timer that starts timing when a signal that triggers the start of radiation irradiation is communicated between the communication means and the radiation source control device, and whether or not the radiation is surely being irradiated toward the detection panel An irradiation determination means, and the irradiation determination means exceeds a set time set in advance by a timer, and if no irradiation is detected by the irradiation detection sensor within the set time, a set error is detected. When it is determined that the radiation is not irradiated toward the detection panel, and the radiation source control unit determines that the radiation is not irradiated toward the detection panel by the irradiation determination unit, the radiation source control device stops the radiation irradiation. It is characterized by.

  The set time is when the radiation is emitted toward the detection panel, the irradiation detection sensor detects the radiation irradiation after communicating a signal that triggers the start of radiation irradiation between the communication means and the radiation source control device. It is set to a necessary and sufficient time.

  The timer starts measuring time when an irradiation permission signal for allowing irradiation of radiation is transmitted from the communication means to the radiation source control device. Further, the communication unit transmits an irradiation stop signal for stopping the irradiation of radiation to the radiation source control device when the irradiation determining unit determines that the radiation is not irradiated toward the detection panel.

  When it is determined by the irradiation determination means that the radiation is not irradiated toward the detection panel, and the radiation source control device stops the radiation irradiation, it is preferable to include a warning display means for displaying a warning to that effect. The warning display means may be provided in the radiation source control device, or may be provided in a console that controls driving of the radiation image detection device. Or you may provide in a radiographic image detection apparatus itself.

  A setting error prevention means for preventing a setting error is provided, and the irradiation determining means functions as a backup in the case where the setting error prevention means does not work normally. As the setting error prevention means, for example, a lamp that is provided in the radiation image detection apparatus and can be turned on to report that it is used for imaging or a speaker that can be notified by voice can be considered.

  The dose detection sensor that detects the arrival dose of radiation to the detection panel is compared with the integrated value of the arrival dose detected by the dose detection sensor and a preset threshold value, and the integrated value of the arrival dose is calculated based on the comparison result. Automatic exposure control means for determining whether or not the target value has been reached, and when it is determined by the irradiation determination means that radiation is being emitted toward the detection panel, the radiation source control device is an automatic exposure control means. When it is determined that the integrated value of the reached dose has reached the target value, radiation irradiation is stopped.

  It is preferable that the irradiation detection sensor also serves as a dose detection sensor. The irradiation detection sensor is preferably a part of the pixel. Furthermore, it is preferable that the radiation image detection apparatus is an electronic cassette in which a detection panel is housed in a portable housing.

  The radiation imaging system drive control method according to the present invention includes a radiation source that irradiates a subject with radiation, a radiation source control device that controls driving of the radiation source, and a pixel that accumulates charges according to the radiation dose. Is a radiation imaging system drive control method comprising a radiation image detection device that communicates various signals with a radiation source control device via a communication means, the communication means and the radiation source control device. The time measured by the timer when communicating a signal that triggers the start of radiation irradiation exceeds the preset time set by the irradiation detection sensor that detects the presence or absence of radiation irradiation to the detection panel. If no radiation irradiation is detected, the irradiation determination means determines that no radiation is being emitted toward the detection panel due to a setting error. Wherein the stopping of irradiation.

  A radiological image detection apparatus according to the present invention includes a detection panel in which pixels that accumulate charges corresponding to an arrival dose of radiation emitted from a radiation source are arranged, an irradiation detection sensor that detects whether radiation is applied to the detection panel, and The time measurement is started when a communication means that communicates various signals with the radiation source control device that controls the driving of the radiation source, and a signal that triggers radiation irradiation between the communication means and the radiation source control device are communicated. A timer and an irradiation determining means for determining whether or not radiation is surely irradiated toward the detection panel. The irradiation determining means exceeds a preset time set by the timer and falls within the set time. If the irradiation detection sensor does not detect radiation exposure, it is determined that no radiation is being applied toward the detection panel due to a set mistake, and the communication means detects the detection panel using the irradiation determination means. Radiation when it is determined not to be irradiated, and transmits the irradiation stop signal for stopping the irradiation of the radiation source controller towards.

  According to the present invention, when radiation irradiation is not detected within a set time after communication of a signal that triggers radiation irradiation, the radiation irradiation is forcibly stopped. When a forgetting or mistaken mistake occurs, it is possible to avoid unnecessary exposure of the subject.

It is the schematic which shows the structure of a X-ray imaging system. It is a figure which shows the internal structure of a radiation source control apparatus. It is a perspective view which shows the external appearance of an electronic cassette. It is a block diagram which shows the internal structure of an electronic cassette. It is a figure for demonstrating arrangement | positioning of a detection pixel. It is a block diagram which shows the internal structure of an irradiation determination / AEC part. It is a figure which shows the imaging conditions set with a console. It is a figure which shows transition of operation | movement of FPD in X-ray imaging. It is a flowchart which shows the flow of a process of X-ray imaging. It is a flowchart which shows the flow of a process of X-ray imaging. It is a figure which shows the warning display window displayed on the display of a console. It is an external appearance perspective view which shows another aspect of an electronic cassette. It is a figure which shows another aspect of FPD.

  In FIG. 1, an X-ray imaging system 2 includes an X-ray source 10 including an X-ray tube that emits X-rays, a radiation source controller 11 that controls the operation of the X-ray source 10, and an X-ray irradiation start. An irradiation switch 12 for instructing, an electronic cassette 13 for detecting an X-ray transmitted through the subject and outputting an X-ray image, a console 14 for controlling the operation of the electronic cassette 13 and image processing of the X-ray image, It has a standing imaging table 15 for imaging the subject in a standing posture and a lying imaging table 16 for imaging in a lying posture. The X-ray source 10, the radiation source control device 11, and the irradiation switch 12 constitute an X-ray generator 2a, the electronic cassette 13, and the console 14 constitute an X-ray imaging device 2b, respectively. In addition, a radiation source moving device (not shown) for setting the X-ray source 10 in a desired direction and position is provided. The X-ray source 10 includes a standing imaging table 15 and a standing imaging table. 16 shared.

  The X-ray source 10 includes an X-ray tube that emits X-rays, and an irradiation field limiter (collimator) that limits an X-ray irradiation field emitted by the X-ray tube. The X-ray tube has a cathode made of a filament that emits thermoelectrons, and an anode (target) that emits X-rays when the thermoelectrons emitted from the cathode collide. The irradiation field limiter has, for example, a plurality of lead plates that shield X-rays arranged in a cross pattern, and an irradiation opening that transmits X-rays is formed in the center, and the position of the lead plate is moved. The irradiation field is limited by changing the size of the irradiation opening.

  As shown in FIG. 2, the radiation source control device 11 boosts an input voltage with a transformer to generate a high-voltage tube voltage, and supplies the X-ray source 10 through a high-voltage cable. Main information and signals of the console 14 and the control unit 21 that controls the tube voltage that determines the energy spectrum of the X-rays irradiated by the source 10, the tube current that determines the irradiation amount per unit time, and the X-ray irradiation time. And a communication I / F 22 that mediates transmission and reception.

  An irradiation switch 12, a memory 23, and a touch panel 24 are connected to the control unit 21. The irradiation switch 12 is, for example, a two-stage push switch operated by an operator such as a radiographer, and generates a warm-up start signal for starting the warm-up of the X-ray source 10 by one-stage push. An irradiation start signal for causing the X-ray source 10 to start irradiation is generated. These signals are input to the radiation source control device 11 through a signal cable. When receiving the irradiation start signal from the irradiation switch 12, the control unit 21 starts supplying power from the high voltage generator 20 to the X-ray source 10.

  The memory 23 stores several types of imaging conditions such as tube voltage and tube current in advance. The shooting conditions are manually set by the operator through the touch panel 24. The radiation source control device 11 tries to irradiate X-rays with the tube voltage or tube current irradiation time product of the set imaging conditions. When the AEC detects that a necessary and sufficient dose has been reached, the X-ray irradiation is stopped even if it is less than the tube current irradiation time product (irradiation time) to be irradiated on the radiation source control device 11 side. To function. In order to prevent the X-ray irradiation from being terminated due to the end of the X-ray irradiation before the target dose is reached and the AEC is determined to stop the irradiation, the tube current irradiation time product or irradiation time is included in the imaging conditions of the X-ray source 10. The maximum value of is set. Note that the set tube current irradiation time product or irradiation time is preferably set to a value corresponding to the imaging region.

  The irradiation signal I / F 25 is wired or wirelessly connected to the electronic cassette 13 when the X-ray irradiation stop timing is defined based on the output of the detection pixel 58 (see FIG. 4) of the electronic cassette 13. In this case, when receiving a warm-up start signal from the irradiation switch 12, the control unit 21 transmits an inquiry signal to the electronic cassette 13 via the irradiation signal I / F 25. When the electronic cassette 13 receives the inquiry signal, the electronic cassette 13 checks whether or not it can shoot, and if it is in a shootable state, transmits an irradiation permission signal. The control unit 21 receives the irradiation permission signal with the irradiation signal I / F 25, and further starts the power supply from the high voltage generator 20 to the X-ray source 10 when receiving the irradiation start signal from the irradiation switch 12. Further, the control unit 21 stops the power supply from the high voltage generator 20 to the X-ray source 10 when the irradiation stop signal emitted from the electronic cassette 13 is received by the irradiation signal I / F 25, and Stop irradiation.

  The irradiation stop signal is sent to the FPD 35 when the irradiation determination / AEC unit 52 (see FIG. 4) of the electronic cassette 13 determines that the integrated value of the reaching dose to the FPD 35 has reached the target value. There are two types: those sent when it is determined that X-rays are not irradiated. When the latter irradiation stop signal is received by the irradiation signal I / F 25, the control unit 21 lights the patrol lamp 26.

  In FIG. 3, the electronic cassette 13 includes an FPD 35 and a portable housing 13 a that houses the FPD 35. The casing 13a of the electronic cassette 13 is substantially rectangular and has a flat shape, and the plane size is the same size as a film cassette or an IP cassette (also called a CR cassette) (a size based on the international standard ISO 4090: 2001). It is. For this reason, it can be attached to an existing photographing stand for a film cassette or an IP cassette.

  A plurality of electronic cassettes 13, for example, two for an upright imaging table 15 and a vertical imaging table 16 are provided in one imaging room where the X-ray imaging system 2 is installed. The electronic cassette 13 is selected on the console 14 before photographing. The electronic cassette 13 is detachably attached to the holders 15a and 16a of the standing position imaging table 15 and the standing position imaging table 16 so that the imaging surface 37 (see FIG. 4) of the FPD 35 is held in a posture facing the X-ray source 10. Set. The electronic cassette 13 can be used alone as it is placed on the bed on which the subject lies, or held by the subject itself, instead of being set on the standing position imaging stand 15 or the supine position imaging stand 16. is there.

  The console 14 is communicably connected to the electronic cassette 13 by a wired method or a wireless method, and controls the operation of the electronic cassette 13 in accordance with an input operation from an operator via an input device 14a such as a keyboard. Specifically, control such as power on / off of the electronic cassette 13 and mode switching to a standby mode or a photographing mode is performed.

  In addition to being displayed on the display 14b of the console 14, the X-ray image from the electronic cassette 13 is stored in a data storage such as a storage device or memory in the console 14 or an image storage server connected to the console 14 over a network. .

  The console 14 receives an input of an examination order including information such as the patient's sex, age, imaging region, and imaging purpose, and displays the examination order on the display 14b. The examination order is input from an external system that manages patient information such as HIS (Hospital Information System) and RIS (Radiation Information System) and examination information related to radiation examination, or is manually input by an operator. The examination order includes radiographs such as the head, chest, and abdomen, front, side, oblique, PA (X-rays are irradiated from the back of the subject), and AP (X-rays are irradiated from the front of the subject). Directions are included. The operator confirms the contents of the inspection order on the display 14b, and inputs photographing conditions corresponding to the contents through the operation screen displayed on the display 14b.

  In FIG. 4, the electronic cassette 13 includes a communication unit 30 and a battery 31 for communicating with the console 14 in a wired or wireless manner. The communication unit 30 mediates transmission / reception of various information and signals including image data of the console 14 and the control unit 32. The battery 31 supplies power for operating each part of the electronic cassette 13. A relatively small battery 31 is used so as to fit in the thin electronic cassette 13. The battery 31 can be taken out from the electronic cassette 13 and set in a dedicated cradle for charging. The battery 31 may be configured to be capable of wireless power feeding.

  The communication unit 30 is wired to the console 14 when wireless communication between the electronic cassette 13 and the console 14 becomes impossible due to a shortage of the remaining battery 31 or the like. When a cable from the console 14 is connected to the communication unit 30, wired communication with the console 14 is possible. At this time, power may be supplied from the console 14 to the electronic cassette 13.

  The FPD 35 includes a TFT active matrix substrate, and includes an imaging surface 37 formed by arranging a plurality of pixels 36 that accumulate charges according to the X-ray arrival dose on the substrate. The plurality of pixels 36 are two-dimensionally arranged in a matrix of n rows (x direction) × m columns (y direction) at a predetermined pitch.

The FPD 35 has a scintillator (phosphor) that converts X-rays into visible light, and is an indirect conversion type in which visible light converted by the scintillator is photoelectrically converted by the pixels 36. The scintillator is made of CsI: Tl (thallium activated cesium iodide), GOS (Gd ₂ O ₂ S: Tb, gadolinium oxysulfide) or the like, and is disposed so as to face the entire imaging surface 37 on which the pixels 36 are arranged. Has been. The scintillator and the TFT active matrix substrate may be a PSS (Penetration Side Sampling) system in which the scintillator and the substrate are arranged in this order when viewed from the X-ray incident side, or conversely, the ISS (Irradiation) arranged in the order of the substrate and the scintillator. Side sampling) method may be used. Alternatively, a direct conversion type FPD using a conversion layer (such as amorphous selenium) that directly converts X-rays into charges may be used without using a scintillator.

  The pixel 36 includes a photodiode 38 that is a photoelectric conversion element that generates charges (electron-hole pairs) upon incidence of visible light, a capacitor (not shown) that accumulates charges generated by the photodiode 38, and a thin film transistor (TFT). 39).

  The photodiode 38 has a structure in which a semiconductor layer (for example, PIN type) that generates electric charges and an upper electrode and a lower electrode are arranged above and below the semiconductor layer. In the photodiode 38, a TFT 39 is connected to the lower electrode, and a bias line is connected to the upper electrode. The bias lines are provided for the number of rows (n rows) of the pixels 36 in the imaging surface 37 and are bound to one connection. The connection is connected to the bias power supply. A bias voltage is applied to the upper electrode of the photodiode 38 from the bias power source through the connection and the bias line. An electric field is generated in the semiconductor layer by applying a bias voltage, and charges (electron-hole pairs) generated in the semiconductor layer by photoelectric conversion move to the upper and lower electrodes, one of which is positive and the other is negative. As a result, charge is accumulated in the capacitor.

  The TFT 39 has a gate electrode connected to the scanning line 40, a source electrode connected to the signal line 41, and a drain electrode connected to the photodiode 38. The scanning lines 40 and the signal lines 41 are wired in a grid pattern. The scanning lines 40 are the number of rows of the pixels 36 in the imaging surface 37 (n rows), and the signal lines 41 are the number of columns of the pixels 36 (m columns). Min) each is provided. The scanning line 40 is connected to the gate driver 42, and the signal line 41 is connected to the signal processing circuit 45.

  The gate driver 42 drives the TFT 39 to accumulate a signal charge corresponding to the X-ray arrival dose in the pixel 36, a read (main reading) operation for reading the signal charge from the pixel 36, and a reset (empty reading). ) Make an action. The control unit 32 controls the start timing of each of the operations executed by the gate driver 42.

  In the accumulation operation, the TFT 39 is turned off, and signal charges are accumulated in the pixel 36 during that time. In the read operation, gate pulses G1 to Gn for simultaneously driving the TFTs 39 in the same row are generated in sequence from the gate driver 42, the scanning lines 40 are sequentially activated one by one, and the TFTs 39 connected to the scanning lines 40 are provided for each row. Turn on. The charge accumulated in the capacitor of the pixel 36 is read out to the signal line 41 and input to the signal processing circuit 45 when the TFT 39 is turned on.

  The signal processing circuit 45 includes an integrating amplifier 46, a CDS circuit (CDS) 47, a multiplexer (MUX) 48, an A / D converter (A / D) 49, and the like. The integrating amplifier 46 is individually connected to each signal line 41. The integrating amplifier 46 includes an operational amplifier 46a and a capacitor 46b connected between the input and output terminals of the operational amplifier 46a, and the signal line 41 is connected to one input terminal of the operational amplifier 46a. The other input terminal of the operational amplifier 46a is connected to the ground (GND). A reset switch 46c is connected in parallel to the capacitor 46b. The integrating amplifier 46 integrates the charges input from the signal line 41, converts them into analog voltage signals V1 to Vm, and outputs them. The MUX 48 is connected to the output terminal of the operational amplifier 46a in each column via the amplifier 50 and the CDS 47. An A / D 49 is connected to the output side of the MUX 48.

  The CDS 47 has a sample and hold circuit, performs correlated double sampling on the output voltage signal of the integration amplifier 46 to remove noise, and holds the output voltage signal of the integration amplifier 46 for a predetermined period (sample hold). ) The MUX 48 selects one CDS 47 by an electronic switch in order from the CDS 47 of each column connected in parallel based on an operation control signal from a shift register (not shown), and outputs voltage signals V1 to V1 output from the selected CDS 47. Vm is serially input to the A / D 49. The A / D 49 converts the input voltage signals V <b> 1 to Vm into digital voltage signals, and outputs the digital voltage signals to the memory 51 or the irradiation determination / AEC unit 52 built in the electronic cassette 13. An amplifier may be connected between the MUX 48 and the A / D 49.

  When the voltage signals V1 to Vm for one row are read from the integrating amplifier 46 by the MUX 48, the control unit 32 outputs a reset pulse RST to the integrating amplifier 46 and turns on the reset switch 46c. As a result, the signal charge for one row stored in the capacitor 46b is discharged and reset. After resetting the integrating amplifier 46, the reset switch 46c is turned off again, and one sample hold circuit of the CDS 47 is held after a predetermined time has elapsed, and the kTC noise component of the integrating amplifier 46 is sampled. Thereafter, a gate pulse of the next row is output from the gate driver 42 to start reading signal charges of the pixels 36 of the next row. Further, after the gate pulse is output, the signal charge of the pixel 36 in the next row is held by another sample hold circuit of the CDS 47 after a predetermined time has elapsed. These operations are sequentially repeated to read the signal charges of the pixels 36 in all rows.

  When the reading of all rows is completed, image data representing an X-ray image for one screen is recorded in the memory 51. This image data is read from the memory 51 and output to the console 14 through the communication unit 30. Thus, an X-ray image of the subject is detected.

  Dark charges are generated in the semiconductor layer of the photodiode 38 regardless of whether X-rays are incident. This dark charge is accumulated in the capacitor of the pixel 36 because the bias voltage is applied. Since the dark charge generated in the pixel 36 becomes a noise component for the image data, a reset operation is performed at predetermined time intervals in order to remove this. The reset operation is an operation for sweeping out dark charges generated in the pixels 36 through the signal line 41.

  The reset operation is performed, for example, by a sequential reset method in which the pixels 36 are reset row by row. In the sequential reset method, as in the signal charge reading operation, gate pulses G1 to Gn are sequentially generated from the gate driver 42 to the scanning line 40, and the TFTs 39 of the pixels 36 are turned on line by line. While the TFT 39 is on, dark charge flows from the pixel 36 to the capacitor 46 b of the integrating amplifier 46 through the signal line 41. In the reset operation, unlike the read operation, the charge accumulated in the capacitor 46b is not read out by the MUX 48, and the reset pulse RST is output from the control unit 32 in synchronization with the generation of the gate pulses G1 to Gn. 46c is turned on, the charge accumulated in the capacitor 46b is discharged, and the integrating amplifier 46 is reset.

  Instead of the sequential reset method, multiple rows of array pixels are grouped as a group, and the reset is performed sequentially within the group, and the dark charge of the number of rows in the group is simultaneously discharged. An all-pixel reset method that simultaneously sweeps out the dark charges may be used. The reset operation can be speeded up by a parallel reset method or an all-pixel reset method.

  The FPD 35 includes a TFT 57 driven by a gate driver 55 and a scanning line 56 other than the normal pixel 36 in addition to the normal pixel 36 to which the TFT 39 driven by the gate driver 42 and the scanning line 40 is connected as described above. A plurality of detection pixels 58 connected to each other are provided in the same imaging surface 37. The TFT 57 is turned on by gate pulses g 1 to gn from the gate driver 55. The basic configuration of the detection pixel 58 such as the photodiode 38 is exactly the same as that of the pixel 36 except for the driving source, and the stored charge can be read from the signal line 41 independently of the pixel 36. In the reset operation and the read operation, after completing the normal operation of the pixel 36, the gate driver 55 issues gate pulses g1 to gn in the same manner to perform the reset operation or the read operation of the detection pixel 58. Alternatively, in synchronization with the operation of the gate driver 42, the reset operation or the read operation of the pixels 36 and the detection pixels 58 in the same row are simultaneously performed. The detection pixel 58 is a pixel that is used to detect the arrival dose of X-rays on the imaging surface 37, and functions as an irradiation detection sensor and a dose detection sensor. The detection pixels 58 occupy about several ppm to several percent of the pixels 36 in the imaging surface 37.

  As shown in FIG. 5, the detection pixels 58 follow a waveform locus 59 indicated by a dotted line symmetrical with respect to the center of the imaging surface 37 so that the detection pixels 58 are evenly distributed in the imaging surface 37 without being locally biased in the imaging surface 37. Is provided. The detection pixels 58 are provided one by one in the column of pixels 36 to which the same signal line 41 is connected, and the columns in which the detection pixels 58 are provided are provided by sandwiching, for example, two to three columns in which the detection pixels 58 are not provided. It is done. The position of the detection pixel 58 is known when the FPD 35 is manufactured, and the FPD 35 stores the position (coordinates) of all the detection pixels 58 in a nonvolatile memory (not shown) in advance. In contrast to the present embodiment, the detection pixels 58 may be locally concentrated and the arrangement of the detection pixels 58 can be changed as appropriate. For example, in a mammography apparatus that captures an image of the breast, the detection pixels 58 may be arranged concentrated on the chest wall side.

  When a gate pulse is generated from the gate driver 55 and the TFT 57 is turned on, the signal charge generated in the detection pixel 58 is read out to the signal line 41. Since the pixel 36 is a driving source different from the pixel 36, the pixel 36 in the same column can turn off the TFT 39, and the signal charge of the detection pixel 58 can be read even during the accumulation operation for accumulating the signal charge. . At this time, the charge generated in the detection pixel 58 flows into the capacitor 46b of the integration amplifier 46 on the signal line 41 to which the detection pixel 58 is connected. During the accumulation operation of the pixel 36, the charge from the detection pixel 58 that is accumulated in the integrating amplifier 46 with the TFT 57 turned on is output to the A / D 49 at a predetermined sampling period.

  The control unit 32 is provided with a circuit (not shown) that performs various image processing such as offset correction, sensitivity correction, and defect correction on the X-ray image data in the memory 51. The offset correction circuit subtracts the offset correction image acquired from the FPD 35 without irradiating the X-ray in units of pixels from the X-ray image, thereby removing fixed pattern noise caused by individual differences in the signal processing circuit 45 and the imaging environment. .

  The sensitivity correction circuit is also referred to as a gain correction circuit, and corrects variations in sensitivity of the photodiode 38 of each pixel 36, variations in output characteristics of the signal processing circuit 45, and the like. Sensitivity correction is performed based on sensitivity correction data generated based on an image obtained by subtracting the offset correction image from an image obtained by irradiating a predetermined dose of X-rays in the absence of the subject. Sensitivity correction data is shifted from the reference value so that the output of each pixel is uniformly the same by multiplying the X-ray image after offset correction when a predetermined dose of X-rays is irradiated in the absence of the subject. Has a coefficient for correcting each pixel. For example, when the output of the pixel A is the reference 1 but the output of the pixel B is 0.8, the coefficient of the pixel B is 1.25 (1 / 0.8 = 1.25).

  The defect correction circuit linearly interpolates the pixel value of the defective pixel with the pixel values of the surrounding normal pixels based on the defective pixel information attached at the time of shipment. Further, the pixel value of the detection pixel 58 in the lighting field used for the irradiation detection for determining whether or not the X-ray is irradiated toward the FPD 35 and the dose detection of the AEC is similarly interpolated.

  The offset correction image and the sensitivity correction data are acquired, for example, at the time of shipment of the electronic cassette 13, or are acquired by a manufacturer's service person at the time of regular maintenance or by an operator at the start time of the hospital, and are recorded in the internal memory of the control unit 32. And read out during correction. The various image processing circuits described above may be provided in the console 14 and various image processing may be performed by the console 14.

  The irradiation determination / AEC unit 52 is driven and controlled by the control unit 32. The irradiation determination / AEC unit 52 acquires a digital voltage signal (hereinafter referred to as a dose detection signal) from the signal line 41 to which the detection pixel 58 is connected from the A / D 49, and sends it to the FPD 35 based on the acquired dose detection signal. Irradiation determination and AEC are performed to determine whether or not X-rays are surely irradiated.

  In FIG. 6, the irradiation determination / AEC unit 52 includes an irradiation determination circuit group 52a and an AEC circuit group 52b. The irradiation determination circuit group 52a includes a first comparison circuit 75, a first threshold value generation circuit 76, a timer 77, and a time setting circuit 78. The first comparison circuit 75 starts monitoring the dose detection signal when the FPD 35 switches from the standby mode in which the reset operation is repeated to the imaging mode in which the accumulation operation is started. Then, the average value, maximum value, mode value, or total value of the dose detection signals from the detection pixels 58 in the daylighting field and the irradiation determination threshold value (see FIG. 8) given from the first threshold value generation circuit 76 are appropriately timed. Compare with.

  The timer 77 is a countdown timer, and starts measuring the time set by the time setting circuit 78 when an irradiation permission signal is transmitted from the electronic cassette 13 to the radiation source control device 11. When the time set by the time setting circuit 78 elapses and the value becomes 0, a time-up signal indicating that is output to the first comparison circuit 75.

  If the dose detection signal exceeds the irradiation determination threshold before the time-up signal is input from the timer 77, in other words, within the time set by the time setting circuit 78, the first comparison circuit 75 performs X toward the FPD 35. It is judged that the line is surely irradiated, and nothing is done after the monitoring of the dose detection signal is terminated. On the other hand, if the dose detection signal does not exceed the irradiation determination threshold within the time set by the time setting circuit 78, the first comparison circuit 75 is irradiated with X-rays toward the FPD 35 due to a setting error of the electronic cassette 13. It is determined that the dose is not detected, monitoring of the dose detection signal is terminated and an irradiation stop signal is output.

  The AEC circuit group 52b includes an integration circuit 79, a second comparison circuit 80, and a second threshold value generation circuit 81. The integration circuit 79 integrates the average value, the maximum value, the mode value, or the total value of the dose detection signals from the detection pixels 58 in the lighting field. Similar to the first comparison circuit 75, the second comparison circuit 80 starts monitoring the integrated value of the dose detection signal from the integration circuit 79 when the FPD 35 is switched from the standby mode to the imaging mode. Then, the integrated value is compared with the irradiation stop threshold given from the second threshold generation circuit 81 at an appropriate timing. When the integrated value reaches the irradiation stop threshold, the second comparison circuit 80 determines that the integrated value of the dose reaching the FPD 35 has reached the target value, and outputs an irradiation stop signal. The irradiation stop signal output from the second comparison circuit 80 and the irradiation stop signal output from the first comparison circuit 75 have exactly the same effect of stopping the X-ray irradiation. Source information indicating which one of the comparison circuits 75 and 80 is output is added to each irradiation stop signal. The control unit 21 of the radiation source control device 11 turns on the patrol lamp 26 when the source information of the irradiation stop signal received by the irradiation signal I / F 25 indicates that it has been output from the first comparison circuit 75.

  The communication unit 30 is provided with an irradiation signal I / F 82. The irradiation signal I / F 25 of the radiation source control device 11 is wired or wirelessly connected to the irradiation signal I / F 82. The irradiation signal I / F 82 receives an inquiry signal, transmits an irradiation permission signal in response to the inquiry signal, receives an irradiation start signal, and transmits an irradiation stop signal output from the first and second comparison circuits 75 and 80.

  As shown in FIG. 7, in the console 14, an imaging condition can be set for each imaging region by the input device 14a. In the imaging conditions, a tube voltage, a tube current, a lighting field of the detection pixel 58, a setting time of the time setting circuit 78, an irradiation stop threshold, and the like are stored. Although the irradiation determination threshold is not shown, the same value is set regardless of the imaging region. The imaging condition information is stored in the storage device, and the imaging condition corresponding to the imaging region designated by the input device 14 a is read from the storage device and provided to the electronic cassette 13. The imaging conditions of the radiation source controller 11 are manually set by the operator with reference to the imaging conditions of the console 14.

  The daylighting field indicates the region of the detection pixel 58 used for AEC, and a portion that is the region of interest most noticeable at the time of diagnosis and that can stably obtain a dose detection signal is set for each imaging region. For example, when the imaging region is the chest, the left and right lung field portions are set as the daylighting fields as indicated by a and b surrounded by dotted lines in FIG. The daylighting field is represented by xy coordinates. When the daylighting field is rectangular as in this example, for example, two xy coordinates connected by diagonal lines are stored. The xy coordinates correspond to the positions in the imaging surface 37 of the pixels 36 including the detection pixels 58 of the electronic cassette 13. The direction parallel to the scanning line 40 is the x axis and the direction parallel to the signal line 41 is the y axis. The coordinates of the upper left pixel 36 are expressed at the origin (0, 0).

  The set time is the radiation source after the irradiation signal I / F 82 of the communication unit 30 transmits the irradiation permission signal when X-rays are surely irradiated toward the FPD 35 without forgetting to set the electronic cassette 13 or making a mistake. The time until the irradiation start signal is received from the irradiation signal I / F 25 of the control device 11, the X-ray source 10 is actually irradiated with the X-ray, and the dose detection signal from the detection pixel 58 exceeds the irradiation determination threshold. The sum with the time until the irradiation determination / AEC unit 52 detects the X-ray irradiation is set. Of course, the set delay time includes the communication delay time between the irradiation signals I / F 25 and 82 and the processing time of the signal processing circuit 45.

  Although depending on the characteristics of the X-ray source 10, if the tube voltage and tube current to be driven are generally different, the driving of the X-ray source 10 is stabilized after the X-ray irradiation is started, and the arrival dose is saturated. Thus, the way of increasing the dose until it settles to a certain value and the output value from the detection pixel 58 are different. Accordingly, the rise of the dose output is slow, and it takes time until the dose detection signal from the detection pixel 58 exceeds the irradiation determination threshold value under the low-dose imaging condition. The setting time of the imaging condition in which the output value from the detection pixel 58 becomes low at such a low dose is set to be the longest. However, the set time is several hundred μsec to several msec at the longest, and is extremely shorter than the maximum irradiation time set under the imaging conditions of the X-ray source 10.

  If X-rays are surely emitted toward the FPD 35 without forgetting to set the electronic cassette 13 or being mistaken, the irradiation determination / AEC unit 52 detects X-ray irradiation after transmitting an irradiation permission signal. It is also possible to obtain the time until the above by performing a plurality of simulation experiments in advance for each photographing condition, and adopt the mode value or the maximum value of the obtained values as the set time.

  In FIG. 8, before photographing, the FPD 35 operates in a standby mode in which the reset operation is repeatedly executed regardless of whether the pixel 36 or the detection pixel 58 is used. When the irradiation start signal is received by the irradiation signal I / F 82, the control unit 32 causes the FPD 35 to finish the reset operation, start the accumulation operation, and switch from the standby mode to the imaging mode. However, for only the detection pixels 58 in the daylighting field set in the imaging conditions, a dose detection operation for turning on the TFT 57 and outputting a dose detection signal is started.

  Monitoring of the dose detection signal is started by the first comparison circuit 75 of the irradiation determination / AEC unit 52, and monitoring of the integrated value of the dose detection signal from the integration circuit 79 is started by the second comparison circuit 80, respectively. After it is determined by the first comparison circuit 75 that the X-rays are surely irradiated toward the FPD 35, an irradiation stop signal is output from the second comparison circuit 80 when the integrated value of the dose detection signal reaches the irradiation stop threshold. Is done. Thereby, the irradiation stop signal is transmitted from the irradiation signal I / F 82 toward the irradiation signal I / F 25. In response to the irradiation stop signal, the X-ray source 10 stops the X-ray irradiation. At this time, the control unit 32 shifts the operation of the FPD 35 from the accumulation operation to the reading operation regardless of the pixel 36, the detection pixel 58 outside the lighting field, and the detection pixel 58 inside the lighting field. This completes one shooting. The FPD 35 returns to the standby mode. If the first comparison circuit 75 determines that X-rays are not irradiated toward the FPD 35, the process immediately returns to the standby mode. Note that the pixel value of the detection pixel 58 in the daylighting field obtained by the read operation is not adopted as image data, but the pixel value interpolated by the defect correction circuit is adopted.

  Next, a procedure when X-ray imaging is performed in the X-ray imaging system 2 will be described with reference to flowcharts of FIGS. First, the subject is placed at a predetermined position in front of the standing imaging table 15 or placed on the supine imaging table 16, and the two electronic cassettes 13 set on the standing or lying imaging tables 15 and 16 are placed. Among them, the height and horizontal position of the electronic cassette 13 used for imaging are adjusted to align the position with the imaging region of the subject. Further, the height, horizontal position, and size of the irradiation field of the X-ray source 10 are adjusted according to the position of the electronic cassette 13 and the size of the imaging region. Next, the electronic cassette 13 to be used is selected on the console 14, and imaging conditions are set on the radiation source control device 11 and the console 14.

  In FIG. 9, in the standby mode before X-ray imaging, the control unit 32 causes the FPD 35 to repeatedly perform a reset operation and waits for an inquiry signal from the irradiation signal I / F 25 with the irradiation signal I / F 82. When the irradiation switch 12 is pushed one step and an inquiry signal is transmitted from the irradiation signal I / F 25 and received by the irradiation signal I / F 82 (step 10 (S10)), after the state check is performed, the irradiation signal I An irradiation permission signal is transmitted from / F82. At the same time, the time setting circuit 78 sets a time corresponding to the photographing condition provided from the console 14 to the timer 77, and the timer 77 starts measuring time (S11).

  Soon after, the irradiation switch 12 is pushed in two steps and an irradiation start signal is transmitted from the irradiation signal I / F 25. When this is received by the irradiation signal I / F 82 (S12), the pixel 36 and the detection pixel 58 outside the lighting field are displayed. The operation is shifted from the reset operation to the accumulation operation and switched to the photographing mode. On the other hand, the detection pixel 58 in the daylighting field set in the photographing condition is turned on by the TFT 57 being turned on (S13).

  X-ray irradiation by the X-ray source 10 is started by pressing the irradiation switch 12 in two steps. The charges generated thereby are accumulated in the photodiode 38 in the case of the pixel 36 and the detection pixel 58 outside the lighting field, and flow into the integrating amplifier 46 through the signal line 41 in the case of the detection pixel 58 in the lighting field, and as a dose detection signal. The signal is output from the integrating amplifier 46 to the A / D 49 and the irradiation determination / AEC unit 52 at a predetermined sampling period.

  The dose detection signal from the detection pixel 58 in the daylighting field is output to the first comparison circuit 75 and the integration circuit 79 of the irradiation determination / AEC unit 52, monitored by the first comparison circuit 75, and integrated by the integration circuit 79. The integrated value of the dose detection signal of the integration circuit 79 is monitored by the second comparison circuit 80 (S14). The first threshold generation circuit 76 generates an irradiation determination threshold, the second threshold generation circuit 81 generates an irradiation stop threshold, and outputs the irradiation determination threshold to the first comparison circuit 75 and the irradiation stop threshold to the second comparison circuit 80, respectively. To do. The first comparison circuit 75 compares the dose detection signal with the irradiation determination threshold value, and the second comparison circuit 80 compares the integrated value of the dose detection signal with the irradiation stop threshold value (S15).

  In FIG. 10, when the dose detection signal exceeds the irradiation determination threshold within the time set by the time setting circuit 78 (YES in S16), X-rays are surely irradiated toward the FPD 35 (no set error). ) Is determined (S17). Then, the monitoring of the dose detection signal by the first comparison circuit 75 and the comparison with the irradiation determination threshold are aborted. The monitoring of the integrated value of the dose detection signal by the second comparison circuit 80 and the comparison with the irradiation stop threshold are continued as they are (S18).

  When the integrated value of the dose detection signal reaches the threshold value (YES in S19), an irradiation stop signal is output from the second comparison circuit 80, and this is transmitted from the irradiation signal I / F 82 toward the irradiation signal I / F 25. Further, the operation of the FPD 35 is shifted from the accumulation operation to the read operation (S20).

  When an irradiation stop signal whose source information indicates the second comparison circuit 80 is received by the irradiation signal I / F 25, the radiation source control device 11 supplies power from the high voltage generator 20 to the X-ray source 10 by the control unit 21. Is stopped, and X-ray irradiation is thereby stopped.

  Various image processing is performed on the X-ray image data output to the memory 51 by the read operation by the various image processing circuits of the control unit 32, thus generating one X-ray image (S21). The X-ray image is wired or wirelessly transmitted to the console 14 via the communication unit 30, and is displayed on the display 14b for diagnosis.

  On the other hand, in S16, when the dose detection signal does not exceed the irradiation determination threshold within the time set by the time setting circuit 78 (NO in S16), X-rays are not irradiated toward the FPD 35 (there is a setting error). ) Is determined (S22). Then, an irradiation stop signal is output from the first comparison circuit 75 and transmitted from the irradiation signal I / F 82 toward the irradiation signal I / F 25 (S23). Further, the operation of the FPD 35 is returned to the reset operation.

  When an irradiation stop signal whose source information indicates the first comparison circuit 75 is received by the irradiation signal I / F 25, the radiation source control device 11 receives an irradiation stop signal whose source information indicates the second comparison circuit 80. Similarly to the above, the power supply from the high voltage generator 20 to the X-ray source 10 is stopped, X-ray irradiation is stopped, and the patrol lamp 26 is turned on by the control unit 21 (S23).

  As described above, according to the present invention, after the irradiation permission signal is transmitted from the electronic cassette 13 to the radiation source control device 11 via the irradiation signal I / F 82, the time is set within the time set by the time setting circuit 78. When X-ray irradiation is not detected by the first comparison circuit 75 of the irradiation determination / AEC unit 52, an irradiation stop signal is output from the first comparison circuit 75 and directed to the irradiation signal I / F 25 of the radiation source controller 11. Therefore, even if the operator forgets to set the electronic cassette or makes a mistake, and the X-ray is irradiated without the operator noticing it, the X-ray irradiation can be stopped immediately.

  When X-rays are irradiated without noticing the set mistake, the X-ray irradiation is not stopped until the maximum tube current irradiation time product or irradiation time set in the radiation source control device 11 is conventionally reached. Was exposed to unnecessary exposure. On the other hand, in the present invention, X-ray irradiation is stopped as soon as it is determined that a setting error has occurred, so that unnecessary exposure to the subject can be minimized.

  When it is determined that a set error has occurred and X-ray irradiation is stopped, the radiation source control device 11 lights the patrol lamp 26 and displays a warning to that effect so that the operator can notice the set error and set correctly. Re-shooting can be performed quickly.

  Since the detection pixel 58 serves both as an irradiation detection sensor for detecting the presence or absence of X-ray irradiation to the FPD 35 and a dose detection sensor for detecting the arrival dose of X-rays to the FPD 35, the cost is lower than when each sensor is provided separately. It can be kept low.

  Note that the method for reporting to the operator that the X-ray irradiation has been stopped due to the set error is not limited to the patrol lamp 26 of the radiation source control device 11 of the above embodiment. The patrol lamp 26 may be turned on and a sound such as a siren or voice guidance may be emitted. In addition, a signal indicating that a setting error has occurred is transmitted from the electronic cassette 13 to the console 14, and a message is displayed on the display 14 b of the console 14 to confirm that the setting error has been detected and X-ray irradiation has been stopped. The warning display window 85 shown in FIG. 11 may be popped up.

  Further, as in the electronic cassette 90 shown in FIG. 12, an LED lamp 91 and a speaker 92 are provided on the side surface of the housing 90a, and the LED lamp 91 is turned on when X-ray irradiation is stopped because it is determined that a setting error has occurred. And sound may be emitted from the speaker 92.

  When display means such as an LED lamp 91 and a speaker 92 are provided in the electronic cassette, the display means is activated even when it is selected to be used for photographing on the console 14, and the display means is used to prevent set errors in advance. Also good. In this way, the display means becomes the first breakwater, and the irradiation determination / AEC unit 52 becomes the second breakwater in the unlikely event that the display means does not work normally or if a setting error occurs even if it works normally. This is a double safety measure.

  When taking an image with X-rays directed toward the film cassette or IP cassette when the electronic cassette is mistaken with the film cassette or IP cassette, unlike when the electronic cassette is mistaken with each other, the film cassette or IP cassette is used. The object image is projected once. For this reason, even when the electronic cassette is mistaken for the film cassette or the IP cassette, if the X-ray irradiation is stopped as in the above embodiment, the diagnosis can be performed with the subject image displayed on the film cassette or the IP cassette. Despite the possibility, you will have to re-shoot and some customers may be subject to complaints. However, since film cassettes and IP cassettes are usually not provided with display means such as LED lamps 91 and speakers 92, if the electronic cassette display means is activated when it is selected for use in photographing, at that time This makes it possible to recognize that the electronic cassette, the film cassette, and the IP cassette have been mistaken, and reduce the probability that an event that becomes a complaint will occur.

  As means for preventing a setting error, the ID of the selected cassette is compared with the ID of the cassette that is actually used, or it is detected whether or not the cassette corresponding to the selected imaging mode is directed to the X-ray source. Conventional techniques such as these may be used.

  In the above-described embodiment, an aspect in which an irradiation stop signal and the like are exchanged between the radiation source control device and the electronic cassette is described, but an irradiation stop signal and the like may be exchanged via a console. In addition, the timer 77 starts measuring when the irradiation permission signal is transmitted. However, the timer 77 may start measuring when the electronic cassette receives the irradiation start signal from the radiation source control device. Change the set time accordingly. In short, it is only necessary to start timing when a signal that triggers the start of X-ray irradiation is communicated between the electronic cassette and the radiation source control device.

  In the above embodiment, the sizes and the like of the pixel 36 and the detection pixel 58 are the same, but a part of the photodiode 38 of the pixel 36 may be the detection pixel 101 as in the FPD 100 shown in FIG. As in the above-described embodiment, separately from the TFT 39, the scanning line 40, and the gate driver 42 of the pixel 36, the TFT 102, the scanning line 103, and the gate driver 104 are connected to the detection pixel 101. Can be read from the signal line 41. The driving method is the same as in the above embodiment. However, at the time of the reading operation, the gate pulse is simultaneously applied to the scanning lines 40 and 103 in the row where the detection pixel 101 outside the lighting field is present, and the pixel 36 and the detection pixel 101 are read at the same timing. In this way, an image signal in which the accumulated charges of the pixel 36 and the detection pixel 101 are mixed is obtained. This image signal has almost the same value as the pixel 36 without the detection pixel 101. On the other hand, in the row where the detection pixel 101 in the daylighting field is present, an image signal is read from only the pixel 36, and this image signal is interpolated based on the area ratio and output ratio of the pixel 36 and the detection pixel 101.

  A pixel in which a photodiode is directly connected to a signal line without using a TFT may be provided and used as a detection pixel. In this case, the charge accumulated in the detection pixel continues to flow to the signal processing circuit via the signal line regardless of the operation of the gate driver.

  In addition, it is possible to detect the dose by monitoring the current of the bias line connected to a specific pixel by utilizing the current based on the charge generated in the pixel flowing in the bias line that supplies the bias voltage to each pixel. The dose may be detected based on the leaked charge leaking from the pixel when all TFTs are turned off. Furthermore, a detection pixel for irradiation determination and AEC having a different configuration and independent output from the pixel may be provided on the same plane as the imaging surface. Furthermore, the present invention is also effective when a sensor such as a conventionally known ion chamber (ionization chamber) is used separately from the electronic cassette.

  In the above embodiment, the irradiation stop signal is output when the integrated value of the dose detection signal reaches the irradiation stop threshold, but the accumulated dose of X-rays is set to the target value based on the integrated value of the dose detection signal in the second comparison circuit 80. It is also possible to calculate a time expected to reach the value and output an irradiation stop signal when the calculated expected time is reached. Further, irradiation determination may be performed based on a dose detection signal from a detection pixel that exists in an unexposed area where X-rays directly hit without passing through the subject. Furthermore, instead of providing an irradiation determination / AEC unit in the electronic cassette and transmitting an irradiation stop signal to the radiation source control device, an irradiation determination / AEC unit is provided in the radiation source control device so that the electronic cassette can be changed to the radiation source control device. May transmit a dose detection signal and perform irradiation determination and AEC on the radiation source control device side.

  In the above embodiment, the example in which the console 14 and the electronic cassette 13 are separate has been described. However, the console 14 does not have to be an independent device, and the function of the console 14 may be mounted on the electronic cassette 13. Similarly, the radiation source control device 11 and the console 14 may be integrated. Further, the present invention is not limited to an electronic cassette that is a portable X-ray image detection device, and may be applied to an X-ray image detection device that is installed on an imaging table. The present invention is effective because a setting error can occur even in a type that is installed on a photographing stand.

  Furthermore, the present invention can be applied not only to X-rays but also to an imaging system that uses other radiation such as γ rays.

2 X-ray imaging system 10 X-ray source 11 Radiation source control device 13, 90 Electronic cassette 14 Console 21 Control unit 30 Communication unit 32 Control unit 35, 100 FPD
36 pixels 52 irradiation determination / AEC unit 58, 101 detection pixel 75 first comparison circuit 77 timer 80 second comparison circuit 82 irradiation signal I / F
85 Warning display window 91 LED lamp 92 Speaker

Claims (13)

A radiation source that emits radiation toward the subject;
A radiation source control device for controlling the driving of the radiation source;
A radiation image detection device having a detection panel in which pixels for accumulating charges according to the radiation dose are arranged and communicating various signals with the radiation source control device via a communication means;
An irradiation detection sensor for detecting the presence or absence of radiation irradiation on the detection panel;
A timer that starts timing when communicating a signal that triggers the start of radiation irradiation between the communication means and the radiation source control device;
Irradiation determination means for determining whether or not the radiation is surely irradiated toward the detection panel,
Irradiation determination means that the time measured by the timer exceeds the preset time, and if the irradiation detection sensor does not detect the radiation irradiation within the set time, the radiation is not directed toward the detection panel due to a setting error. Judgment,
The radiation source control device stops radiation irradiation when it is determined by the irradiation determination means that the radiation is not irradiated toward the detection panel.   The set time is when the radiation is emitted toward the detection panel, the irradiation detection sensor detects the radiation irradiation after communicating a signal that triggers the start of radiation irradiation between the communication means and the radiation source control device. The radiation imaging system according to claim 1, wherein the time is set to a necessary and sufficient time.   3. The radiation imaging system according to claim 1, wherein the timer starts counting when an irradiation permission signal for permitting irradiation of radiation is transmitted from the communication unit to the radiation source control device. 4.   The communication means transmits an irradiation stop signal for stopping radiation irradiation to the radiation source control device when the irradiation determination means determines that the radiation is not irradiated toward the detection panel. The radiography system as described in any one of thru | or 3.   When it is determined by the irradiation determination means that no radiation is irradiated toward the detection panel, and the radiation source control device stops the irradiation of radiation, a warning display means for displaying a warning to that effect is provided. Item 5. The radiation imaging system according to any one of Items 1 to 4. It is equipped with set mistake prevention means to prevent set mistakes,
6. The radiation imaging system according to claim 1, wherein the irradiation determination unit functions as a backup when the set mistake prevention unit does not operate normally.   7. The radiographic system according to claim 6, wherein the set error prevention means is a lamp that is provided in the radiological image detection apparatus and can be lit to report that it is used for radiographing and / or a speaker that can be reported by voice. . A dose detection sensor for detecting the radiation dose to the detection panel;
An automatic exposure control means for comparing the integrated value of the arrival dose detected by the dose detection sensor with a preset threshold value and determining whether or not the integrated value of the arrival dose has reached the target value based on the comparison result; With
When it is determined by the irradiation determination means that the radiation is emitted toward the detection panel, the radiation source control device determines that the integrated value of the reached dose has reached the target value by the automatic exposure control means. The radiation imaging system according to claim 1, wherein the irradiation is stopped.   The radiation imaging system according to claim 8, wherein the irradiation detection sensor also serves as a dose detection sensor.   The radiation imaging system according to claim 1, wherein the irradiation detection sensor is a part of a pixel.   The radiation imaging system according to any one of claims 1 to 10, wherein the radiation image detection device is an electronic cassette in which a detection panel is housed in a portable housing. A communication means having a radiation source that emits radiation toward the subject, a radiation source control device that controls driving of the radiation source, and a detection panel in which pixels that accumulate charges according to the radiation dose are arranged. A radiation imaging system drive control method comprising a radiation image detection device for communicating various signals with a radiation source control device,
When a signal that triggers the start of radiation irradiation is communicated between the communication means and the radiation source control device, the time measured by the timer exceeds the preset time, and the presence or absence of radiation irradiation on the detection panel is detected. When the irradiation detection sensor does not detect the radiation irradiation within the set time, the irradiation determination means determines that the radiation is not irradiated toward the detection panel due to a set mistake,
A radiation control system drive control method, wherein radiation irradiation is stopped by a radiation source control device at that time. A detection panel in which pixels for accumulating charges according to the arrival dose of radiation emitted from a radiation source are arranged;
An irradiation detection sensor for detecting the presence or absence of radiation irradiation on the detection panel;
A communication means for communicating various signals with a radiation source control device that controls driving of the radiation source;
A timer that starts timing when communicating a signal that triggers the start of radiation irradiation between the communication means and the radiation source control device;
Irradiation determination means for determining whether or not the radiation is surely irradiated toward the detection panel,
Irradiation determination means that the time measured by the timer exceeds the preset time, and if the irradiation detection sensor does not detect the radiation irradiation within the set time, the radiation is not directed toward the detection panel due to a setting error. Judgment,
The communication means transmits a radiation stop signal for stopping the radiation irradiation to the radiation source control device when the radiation judgment means judges that the radiation is not emitted toward the detection panel. apparatus.

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