JP2012070886A - Radiographic apparatus and radiographic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic apparatus, which does not require electric connection to a radiation generator, is not influenced by size of an irradiation field of radiation, and easily controls operation synchronized with irradiation timing of radiation.SOLUTION: An irradiation switch 15 of an X-ray generator 11 is provided with a sensor unit 29 for detecting operation force (pressurizing force) given to an operation button 57. The sensor unit 29 is connected to a photography controller 23 of an X-ray photographing apparatus 12, and when the operation button 57 is pressed and operated, a pressure detection signal is output to the photography controller 23. The photography controller 23 controls operation of an FPD (flat panel detector) incorporated in an electric cassette 21 on the basis of the pressure detection signal and synchronizes the irradiation timing of the X-ray source 13 with accumulation timing of the FPD.

Description

  The present invention relates to a radiation imaging apparatus and a radiation imaging system that capture radiation images using radiation.

  In the medical field, X-ray imaging systems using radiation, for example, X-rays, are known for performing image diagnosis. The X-ray imaging system includes an X-ray generation apparatus that generates X-rays and an X-ray imaging apparatus that receives an X-ray and captures an X-ray image. The X-ray generator has an X-ray source that irradiates X-rays toward a subject, a radiation source control device that controls the X-ray source, and an irradiation switch that is operated by an engineer to input an irradiation start instruction.

  The X-ray imaging apparatus includes an X-ray image detection apparatus that receives an X-ray transmitted through a subject and detects an X-ray image, and an imaging control apparatus that controls the X-ray image detection apparatus. The X-ray image detection device has an imaging region in which pixels that store signal charges according to the amount of incident X-rays are arranged in a matrix, and stores signal charges for each pixel to represent image information of the subject. An apparatus using an FPD (flat panel detector) that detects an X-ray image and outputs it as digital image data has been put into practical use.

  Unlike film cassettes and IP (imaging plate) cassettes, X-ray image detection devices using FPDs must synchronize the irradiation timing of the X-ray source and the timing of signal charge accumulation operation. Such techniques are known.

  In the X-ray imaging system described in Patent Document 1, a signal cable extending from an irradiation switch is bifurcated, one is connected to the radiation source control device, the other is connected to the imaging control device, and the irradiation switch is connected to the radiation source control device. An irradiation start signal is transmitted to both of the imaging control devices, and this irradiation start signal is used as a synchronization signal in the imaging control device.

  The X-ray imaging system described in Patent Document 2 includes an X-ray sensor that detects X-rays, which is different from the FPD, in the vicinity of the imaging region of the FPD, and starts irradiation of the X-ray source with the X-ray sensor. By using it as an irradiation detection sensor for detection, the X-ray imaging apparatus self-detects the irradiation timing of the X-ray source.

  In the X-ray imaging system described in Patent Document 3, a threshold value that assumes dark charge generated in an FPD pixel is set in advance regardless of whether X-rays are incident, and the signal charge output from the pixel is compared with the threshold value. The irradiation timing is self-detected in the X-ray imaging apparatus by determining whether or not the signal charge exceeds the threshold value.

JP 2003-47607 A JP-A-11-151233 JP 2008-507796 A

  However, as in the X-ray imaging system described in Patent Document 1, the following problems are involved in a system in which an X-ray generator and an X-ray imaging apparatus are electrically connected and synchronization control is performed by exchanging synchronization signals. There is. For example, there are cases where a system is constructed with X-ray generators and X-ray imaging apparatuses of different manufacturers, such as when X-ray image detection apparatuses of different manufacturers are introduced into a hospital that already has an X-ray source. The imaging control device is equipped with a connection interface for synchronous control as a standard, but the standard connection interface is not compatible with the connection interface of X-ray generators such as irradiation switches and radiation source control devices There is also. In such a case, it is necessary to take measures such as newly adding a connection interface that matches the connection interface of the X-ray generator, which is a heavy burden for the manufacturer of the X-ray imaging apparatus.

  In addition, in the case of an X-ray generator for film or IP that does not support FPD, since it does not have a function of transmitting a synchronization signal to the X-ray imaging apparatus in the first place, it generates X-rays for film or IP. When a system is constructed by combining an apparatus and an X-ray imaging apparatus using FPD, the X-ray imaging apparatus cannot receive a synchronization signal from the X-ray generation apparatus.

  The X-ray imaging systems described in Patent Document 2 and Patent Document 3 can solve the problems of Patent Document 1 because the X-ray imaging apparatus self-detects the X-ray irradiation timing. The X-ray imaging systems described in Document 2 and Patent Document 3 have the following problems.

  First, as in the X-ray imaging system described in Patent Document 2, when an X-ray sensor arranged in the vicinity of the imaging area of the FPD is used as an irradiation detection sensor, the irradiation field of the X-ray source is the size of the imaging region. If it is made smaller than the imaging area according to the above, the irradiation detection sensor will be removed from the irradiation field, so that irradiation detection cannot be performed.

  In addition, when the FPD pixel is used for irradiation detection as in the X-ray imaging system described in Patent Document 3, irradiation detection is possible regardless of the size of the irradiation field, but the FPD signal processing circuit. Since the FPD needs to be significantly modified such as changing the operation sequence of the TFT drive circuit, it is not easy. In particular, it is difficult to adopt for an already commercialized FPD.

  The present invention has been made in view of the above problems, and does not require electrical connection with a radiation generator, is not affected by the size of the radiation field, and is easily synchronized with the radiation timing. An object of the present invention is to provide a radiation imaging apparatus and a radiation imaging system capable of operation control.

  The radiation imaging apparatus of the present invention receives radiation irradiated from a radiation source and transmitted through a subject, and detects a radiation image of the subject, and starts radiation irradiation by the radiation source. A sensor unit that is detachably attached to the irradiation switch to be operated, detects a pressing force applied to the irradiation switch at the time of operation, and generates a pressing detection signal, and based on the pressing detection signal input from the sensor unit And a control means for controlling the operation of the radiation image detector.

  The operation of the radiation image detector includes an accumulation operation for accumulating signal charges according to the amount of incident radiation, and a dark charge that is executed before the accumulation operation and is generated regardless of whether or not the radiation is incident. Reset operation for resetting.

  The control means causes the radiological image detector to start the accumulation operation or the reset operation based on the press detection signal.

  For example, the irradiation switch is turned on when a first pressing force is applied, and generates a warm-up start signal for starting a warm-up for the radiation source, and the first switch And a second switch that is turned on when a second pressing force higher than the pressing force is applied and generates an irradiation start signal for starting irradiation to the radiation source. In this case, it is preferable that the control means detects that at least one of the first switch and the second switch is turned on based on the pressure detection signal.

  For example, the control unit detects that the first switch is turned on, and causes the radiological image detector to start the reset operation. The radiological image detector may shift to the accumulation operation after the reset operation is completed.

  The pre-control means may detect that the first switch is turned on and cause the radiological image detector to start the accumulation operation. The control means may detect that the second switch is turned on and cause the radiological image detector to start the accumulation operation.

  The sensor unit outputs the pressing detection signal having a signal level different according to the first pressing force and the second pressing force to the control unit, and the control unit outputs the first detection signal according to the signal level. When detecting that each of the first switch and the second switch is turned on and detecting that the first switch is turned on, the radiographic image detector starts the reset operation, and the second switch When it is detected that the switch is turned on, the reset operation may be terminated and the accumulation operation may be started.

The sensor unit absorbs a part of the pressure sensor that outputs a first pressing detection signal in response to the first pressing force and the second pressing force applied to the irradiation switch. And an elastic member that reduces the pressure transmitted to the pressure sensor to the first pressing force,
The control means may detect that the second switch is turned on based on the first press detection signal output from the pressure sensor when the second operating force is applied.

  Furthermore, an irradiation detection sensor for detecting whether or not the radiation source is irradiating radiation, the control means detects that the irradiation of the radiation has been stopped by the irradiation detection sensor, and the accumulation The operation may be terminated.

  The radiation image detector and the control means are configured separately, for example. Preferably, the sensor unit and the control means are connected via an interface converter.

  The radiation imaging system of the present invention includes a radiation source that irradiates radiation, a radiation image detector that receives radiation irradiated from the radiation source and transmitted through the subject, and detects a radiation image of the subject. A sensor unit that is detachably attached to an irradiation switch that is operated to start radiation irradiation, detects a pressing force applied to the irradiation switch during operation, and generates a pressing detection signal, and an input from the sensor unit Control means for controlling the operation of the radiation image detector based on the pressed detection signal.

  The present invention is provided with a sensor unit that is detachably attached to the irradiation switch and that detects a pressing force applied to the irradiation switch during operation and generates a pressing detection signal. Therefore, an electrical connection with the radiation generator is unnecessary. Therefore, it is possible to provide a radiation imaging apparatus and a radiation imaging system capable of easily controlling operation in synchronization with the radiation irradiation timing without being affected by the size of the radiation irradiation field.

It is the schematic which shows the structure of a X-ray imaging system. It is explanatory drawing of FPD. It is explanatory drawing of an irradiation switch. It is a perspective view of an irradiation switch and a sensor unit. It is a block diagram of a pressure sensor. It is explanatory drawing of the threshold value for detecting ON of SW1. 6 is a timing chart for starting a reset operation when SW1 is turned on. It is the schematic which shows the structure of the X-ray imaging system of a comparative example. 6 is a timing chart for starting an accumulation operation when SW1 is turned on. 6 is a timing chart for starting an accumulation operation when SW2 is turned on. It is explanatory drawing of the threshold value for detecting ON of SW2. It is a block diagram of the sensor unit for detecting ON of SW2. It is a timing chart of the example which detects both SW1 and SW2. It is explanatory drawing of the threshold value for detecting both SW1 and SW2. It is a block diagram of the X-ray imaging system which provided the irradiation detection sensor. It is a timing chart which detects an irradiation stop with an irradiation detection sensor. 17 is a timing chart different from FIG. It is a timing chart which detects the start and stop of irradiation with an irradiation detection sensor.

[First Embodiment]
In FIG. 1, the X-ray imaging system 10 includes an X-ray generation device 11 and an X-ray imaging device 12. The X-ray generator 11 includes an X-ray source 13, a radiation source controller 14 that controls the X-ray source 13, and an irradiation switch 15. The X-ray source 13 includes an X-ray tube 13a that emits X-rays and an irradiation field limiter (collimator) 13b that limits the irradiation field of the X-rays emitted by the X-ray tube.

  The X-ray tube 13a 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 target has a disk shape, and is a rotating anode in which the focal point moves on a circular orbit by rotation, and the heat generated at the focal point where thermal electrons collide is dispersed. The irradiation field limiter 13b 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 moves the position of the lead plate. By changing the size of the irradiation aperture, the irradiation field is limited.

  The radiation source control device 14 determines a high voltage generator that supplies a high voltage to the X-ray source 13, a tube voltage that determines the energy spectrum of the X-rays that the X-ray source 13 irradiates, and an irradiation amount per unit time. It consists of a controller that controls the tube current and the irradiation time during which X-ray irradiation continues. The high voltage generator boosts the input voltage with a transformer to generate a high voltage tube voltage, and supplies driving power to the X-ray source 13 through the high voltage cable 16. The X-ray generation device 11 is, for example, a device that does not have a communication function with the X-ray imaging device 12, and imaging conditions such as tube voltage, tube current, and irradiation time are determined from the operation panel of the radiation source control device 14 by a technician. Set manually.

  The irradiation switch 15 is an operation input unit operated by an engineer, and is connected to the radiation source control device 14 by a signal cable 17. The irradiation switch 15 generates a warm-up start signal for starting the warm-up of the X-ray source 13 and an irradiation start signal for starting the irradiation of the X-ray source 13. In warming up the X-ray source 13, the heater is operated to preheat the filament, and the rotation of the target is started to reach the target rotation speed. Control signals for controlling the X-ray source 13 such as a warm-up start signal and an irradiation start signal are input to the radiation source controller 14 through the signal cable 17. The radiation source control device 14 controls the operation of the X-ray source 13 based on a control signal from the irradiation switch 15.

  The X-ray imaging apparatus 12 includes an electronic cassette 21, an imaging table 22, an imaging control apparatus 23, and a console 24. The electronic cassette 21 includes an FPD 36 (see FIG. 2) and a portable housing that houses the FPD 36, and receives an X-ray irradiated from the X-ray source 13 and transmitted through the subject H, and detects an X-ray image. A line image detection apparatus. The housing of the electronic cassette 21 has a flat shape with a substantially rectangular planar shape, and the planar size of the housing is substantially the same as, for example, a film cassette or an IP cassette.

  In FIG. 2, an FPD 36 has a TFT active matrix substrate, and an imaging panel 38 in which an imaging region 38 is formed by arranging a plurality of pixels 37 that accumulate signal charges corresponding to the amount of incident X-rays on the substrate. A gate driver 39 that drives the pixel 37 to control reading of the signal charge, a signal processing circuit 40 that converts the signal charge read from the pixel 37 into digital data, and outputs it, and a gate driver 39 and signal processing And a control circuit 41 for controlling the operation of the FPD 36 by controlling the circuit 40. The plurality of pixels 37 are two-dimensionally arranged in a matrix of n rows (x direction) × m columns (y direction) at a predetermined pitch.

  The FPD 36 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 37. The scintillator is disposed so as to face the entire surface of the imaging region 38 in which the pixels 37 are arranged.

  The pixel 37 includes a photodiode 42 that is a photoelectric conversion element that generates charges (electron-hole pairs) upon incidence of visible light, and a capacitor that accumulates the charges generated by the photodiode 42, and a thin film transistor (TFT) as a switching element. 43.

  The photodiode 42 has a structure in which a semiconductor layer (for example, a 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 42, a TFT 43 is connected to a lower electrode, and a bias line (not shown) is connected to the upper electrode, and a bias voltage is applied through the bias line. Since an electric field is generated in the semiconductor layer by applying a bias voltage, charges (electron-hole pairs) generated in the semiconductor layer by photoelectric conversion are applied to the upper and lower electrodes, one having a positive polarity and the other having a negative polarity. The electric charge is accumulated in the capacitor.

  The TFT 43 has a gate electrode connected to the scanning line 44, a source electrode connected to the signal line 46, and a drain electrode connected to the photodiode 42. The scanning lines 44 and the signal lines 46 are wired in a grid pattern. The scanning lines 44 are the number of rows of the pixels 37 in the imaging region 38 (for n rows), and the signal lines 46 are the number of columns of the pixels 37 (m. Each column is wired. The scanning line 44 is connected to the gate driver 39, and the signal line 46 is connected to the signal processing circuit 40.

  The gate driver 39 drives the TFT 43 to perform three operations: an accumulation operation for accumulating signal charges corresponding to the amount of incident X-rays in the pixel 37, a read operation for reading signal charges from the pixel 37, and a reset operation. It is a drive means to be performed. Dark charges are generated in the semiconductor layer of the photodiode 42 regardless of whether X-rays are incident, and since a bias voltage is applied, the dark charges are accumulated in the capacitor. The reset operation is an operation of resetting the pixel 37 by sweeping out dark charges generated in the pixel 37 through the signal line 46. The control circuit 41 controls the operation timing of the reset operation, the accumulation operation, and the read operation executed by the gate driver 39 based on the control signal from the imaging control device 23 input through the communication unit 23b.

  In the accumulation operation, the TFT 43 is turned off, and signal charges are accumulated in the pixel 37 during that time. Simultaneously with the start of the accumulation operation, the control circuit 41 activates the timer to start measuring the accumulation time. The accumulation time is set to be longer than the maximum irradiation time of the X-ray source 13 so that the accumulation operation is continued while the X-ray is irradiated. In the read operation, the gate driver 39 sequentially generates gate pulses G1 to Gn that are driving pulses for driving the TFT 43, sequentially activates the scanning lines 44 row by row, and activates the TFT 43 connected to the scanning line 44 for one row. Turn on each minute. The charge accumulated in the capacitor of the pixel 37 is read out to the signal line 46 and input to the signal processing circuit 40 when the TFT 43 is turned on.

  The signal processing circuit 40 includes an integration amplifier 47, a multiplexer (MUX) 48, and an A / D converter 49. The integrating amplifier 47 is individually connected to each signal line 46. The integrating amplifier 47 includes an operational amplifier and a capacitor connected between the input and output terminals of the operational amplifier, and the signal line 46 is connected to one input terminal of the operational amplifier. The other input terminal is connected to the ground (GND). The integrating amplifier 47 integrates the charges input from the signal line 46, converts them into voltage signals D1 to Dm, and outputs them. A MUX 48 is connected to the output terminal of the integrating amplifier 47 in each column. An A / D converter 49 is connected to the output side of the MUX 48.

  The MUX 48 selects one integration amplifier 47 in order from a plurality of integration amplifiers 47 connected in parallel, and serially inputs voltage signals D1 to Dm output from the selected integration amplifier 47 to the A / D converter 49. . The A / D converter 49 converts the input voltage signals D <b> 1 to Dm into digital data, and outputs the digital data to the memory 51 built in the housing of the electronic cassette 21.

  When the voltage signal D1 to Dm for one row is read from the integration amplifier 47 by the MUX 48, the control circuit 41 outputs a reset pulse (reset signal) RST to the integration amplifier 47, and sets the reset switch 47a of the integration amplifier 47. Turn on. As a result, the signal charge of the first line (row) accumulated in the integrating amplifier 47 is reset. When the integration amplifier 47 is reset, the control circuit 41 instructs the gate driver 39 to output the gate pulse G2 of the second line, and starts reading the signal charges of the pixel 37 of the second line. The second and subsequent lines are read in the same procedure as the first line.

  When the reading of all lines is completed, image data representing an X-ray image for one screen is recorded in the memory 51. The image data is read from the memory 51 and output to the imaging control device 23 through the communication unit 52. In this way, an X-ray image of the subject H is detected.

  Further, since the dark charge generated in the pixel 37 becomes offset noise for the image data, the reset operation is performed before the signal charge accumulation operation is started. For example, the reset operation is performed by a sequential reset method in which the pixels 37 are reset line by line.

  In the case of the sequential reset method, similarly to the signal charge reading operation, the gate driver 39 sequentially generates gate pulses G1 to Gn for the scanning lines 44 to turn on the TFTs 43 of the pixels 37 one row at a time. While the TFT 43 is on, dark charge flows from the pixel 37 to the integrating amplifier 47 through the signal line 46. In the reset operation, unlike the read operation, the charge accumulated in the integrating amplifier 47 is not read by the MUX 48, and the control circuit 41 outputs the reset pulse RST in synchronization with the generation of the gate pulses G1 to Gn. The integration amplifier 47 is reset. The control circuit 41 performs a reset operation for all lines a predetermined number of times (for example, 1 to 2 times) before starting the accumulation operation, and shifts to the accumulation operation after the reset operation is completed.

  Returning to FIG. 1, the imaging table 22 has a slot in which the electronic cassette 21 can be detachably attached, and holds the electronic cassette 21 in a posture in which an incident surface on which X-rays are incident faces the X-ray source 13. The electronic cassette 21 can be attached to a film cassette or an IP cassette photographing table because the size of the casing is almost the same as that of the film cassette or the IP cassette. As the photographing table 22, a standing photographing table for photographing the subject H (subject) in a standing posture is illustrated, but of course, a standing photographing table for photographing the subject H in a standing posture may be used.

  The imaging control device 23 is communicably connected to the electronic cassette 21 by a wired method or a wireless method using the communication cable 26, and controls the electronic cassette 21. Specifically, the imaging conditions are transmitted to the electronic cassette 21 to set the processing conditions of the signal processing of the FPD 36 (such as the gain of an integrating amplifier that amplifies the voltage according to the signal charge), and the FPD 36 Controls the operation timing of the accumulation operation and the like. Further, the imaging control device 23 receives the image data output from the electronic cassette 21 and transmits it to the console 24.

  The imaging control device 23 includes a CPU 23a that controls the device centrally, a communication unit 23b that communicates with the electronic cassette 21 by a wired method or a wireless method, and connectors 23c and 23d that are connected to the connectors of the signal cable 27 and the communication cable 28. And a memory 23e. The communication unit 23b, connectors 23c and 23d, and memory 23e are connected to the CPU 23a by internal wiring. The memory 23e stores a control program executed by the CPU 23a and setting information such as a threshold value Vth (see FIG. 6) described later.

  The connector 23c is provided as a standard in the imaging control device 23 in order to receive control signals transmitted from the X-ray generator, such as a synchronization signal for synchronizing the irradiation timing of the X-ray source 13 and the accumulation operation of the FPD 36. It is what. When the X-ray generator has a control signal transmission function, a communication cable for connecting to the X-ray generator is connected.

  In the X-ray imaging apparatus 12 of the present invention, the sensor unit 29 is connected to the connector 23c via the signal cable 27. The sensor unit 29 is detachably attached to the irradiation switch 15, detects an operation force (pressing force) applied by an engineer as an operator to the irradiation switch 15, and generates a pressing detection signal. The press detection signal is transmitted to the imaging control device 23. The imaging control device 23 performs synchronization control that synchronizes the operation of the FPD 36 with the irradiation timing of the X-ray source 13 by using the press detection signal as a control signal for synchronization.

  The interface converter 31 includes connectors 31 a and 31 b that connect a signal cable 32 extending from the sensor unit 29 and a signal cable 27 connected to the imaging control device 23. The interface converter 31 is an interface converter for connecting the sensor unit 29 having different connection interfaces and the imaging control device 23 so that they can communicate with each other. Specifically, the connection interface is the shape or signal form of the connector. The interface converter 31 physically connects the sensor unit 29 and the imaging control device 23 by having two types of connectors 31a and 31b that match the shape of the connector. Further, the interface converter 31 converts the pressure detection signal output from the sensor unit 29 into a signal form that can be received and processed by the imaging control device 23 (amplification of signal level, etc.).

  By using the interface converter 31, even if the connection interface of the sensor unit 29 and the connection interface of the imaging control device 23 are not compatible, the imaging control device 23 is not provided with a new connection interface for the sensor unit 29. The pressure detection signal of the sensor unit 29 can be received.

  The console 24 is connected to the imaging control device 23 via a communication cable 28, transmits imaging conditions to the imaging control device 23, and performs image processing on X-ray image data transmitted from the imaging control device 23. Apply. The processed X-ray image is displayed on the monitor of the console 24, and the X-ray image data is stored in a data storage device such as a hard disk or memory in the console 24 or an image storage server connected to the console 24 via a network. Stored.

  In addition, the console 24 receives an input of an examination order including information such as a patient's sex, age, imaging region, and imaging purpose, and displays the examination order on a monitor. 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. Alternatively, it is manually input by an engineer or operator. The operator confirms the contents of the inspection order on the monitor, and selects an imaging condition corresponding to the contents through the operation screen of the console 24. The selected shooting condition is transmitted to the shooting control device 23.

  As shown in FIGS. 3 and 4, the irradiation switch 15 has, for example, a substantially cylindrical shape as a whole. The irradiation switch 15 has a main body portion 56 including a grip portion 56a held by an engineer, and a retaining flange portion 56b having a diameter larger than that of the grip portion 56a above the grip portion 56a. An operation button 57 that can be pressed with the thumb F of the engineer is provided above 56b.

  The irradiation switch 15 is a two-stage switch. As shown in FIG. 3A, the operation button 57 is a first-stage first button 57a for inputting an instruction to start warm-up of the X-ray source 13. The second button 57b in the second stage for inputting an instruction to start irradiation is a two-story building. The second button 57b has a diameter that is slightly larger than that of the first button 57a, and has an opening for sinking the pressed first button 57a.

  The operation button 57 is urged by a spring toward the initial position. When a pressing force P is applied downward from the initial position, the operation button 57 is pushed against the urging of the spring. As shown in FIG. 3B, the irradiation switch 15 is configured such that when a pressing force is applied to the first button 57a and the first button 57a is pressed downward, as shown in FIG. Is pushed into the second button 57b and sinks into the first position. In the first position, the first switch SW1 that generates the warm-up start signal S1 is turned on. The first switch SW1 is kept on while the first button 57a is in the first position, and during that time, the warm-up start signal S1 is input to the radiation source controller 14 through the signal cable 17.

  The radiation source control device 14 causes the X-ray source 13 to start warm-up in response to the input of the warm-up start signal S1. In the warm-up, the rotation of the target is started and the heater is activated to heat the filament. The warm-up time required for warm-up of the X-ray source 13 is, for example, about 200 msec to 500 msec. The engineer inputs a warm-up start instruction by pressing the first button 57a, and then presses the second button 57b and inputs an irradiation start instruction after a necessary time for warm-up.

  As shown in FIG. 3C, when the pressing force is applied to the second button 57b together with the first button 57a, and the pressing operation is performed, the second button 57b is pushed into the main body and sinks to the second position. Include. The second switch SW2 for generating the irradiation start signal S2 is turned on at the second position. The second switch SW2 is also kept on while the second button 57b is in the second position, and the irradiation start signal S2 is input to the radiation source control device 14 through the signal cable 17.

  When the irradiation start signal S2 is input, the radiation source control device 14 starts supplying power to the X-ray source 13 and activates a timer to start measuring the X-ray irradiation time. When the irradiation time T1 (see FIG. 7) set in the imaging conditions has elapsed, X-ray irradiation is stopped regardless of whether the second switch SW2 is on or off. Although the X-ray irradiation time varies depending on the imaging conditions, in the case of still image shooting, the maximum X-ray irradiation time is often set in a range of about 500 msec to about 2 s. The time T1 is set with the maximum irradiation time as an upper limit.

  As shown in FIG. 4, the sensor unit 29 includes a pressure sensor 61 that converts pressure into an electrical signal, and a case 62 that houses the pressure sensor 61. The sensor unit 29 is supplied with electric power for driving the pressure sensor 61 from the interface converter 31 through the signal cable 32.

  The sensor unit 29 has a size that fits in the area of the upper surface of the first button 57a, and is detachably attached to the upper surface of the first button 57a with a double-sided tape 63. The pressure sensor 61 is a small sensor having a square shape with a planar shape of 2.5 mm to 3.5 mm square and a thickness of about 1.0 mm. As such a small pressure sensor 61, for example, one described in http://www.alps.com/WebObjects/catalog.woa/J/HTML/Sensor/Piezo/HSPPA/HSPPA_list.html (Alps Electric) Can be used.

  The size of the irradiation switch 15 differs depending on the manufacturer and model, but the diameter of the grip portion 56a of the irradiation switch 15 is about 40 mm to 60 mm, and the diameter of the operation button 57 is also at least about half that (20 mm to 30 mm). ) In many cases. Therefore, since the small pressure sensor 61 is smaller than the size of the operation button 57, it can be attached to various irradiation switches 15 regardless of the manufacturer or model. The case 62 is formed of an elastic member such as rubber. When a pressing force P is applied to the upper surface of the case 62, the case 62 is elastically deformed and the pressing force P is transmitted to the internal pressure sensor 61.

  As shown in FIG. 5, the pressure sensor 61 includes a piezoelectric element 61a whose current value changes as a resistance value changes according to the magnitude of pressure, and a voltage V corresponding to the current value input from the piezoelectric element 61a. This is an amplifier built-in type having an amplifier 61b that amplifies and outputs. As shown in FIG. 6, the voltage V output from the pressure sensor 61 is a press detection signal indicating a value corresponding to the operating force (pressing force P) applied to the operation button 57.

  The pressure detection signal is input to the interface converter 31 through the signal cable 32, and the signal level is converted by the interface converter 31 and input to the imaging control device 23 through the communication cable 28. In the memory 23e of the imaging control device 23, a threshold value Vth1 corresponding to the pressing force P1 for pressing the first button 57a to the first position is set. The CPU 23a of the imaging control device 23 monitors the signal level of the press detection signal, and detects that the first switch SW1 is turned on when the signal level of the press detection signal reaches the threshold value Vth1.

  When detecting that the first switch SW1 is turned on, the CPU 23a transmits a control signal to the electronic cassette 21, and performs control to synchronize the start timing of the accumulation operation of the FPD 36 with the irradiation timing of the X-ray source 13. .

  Specifically, as shown in the timing chart of FIG. 7, when the CPU 23a detects that the first switch SW1 is turned on through the sensor unit 29 (S1 detection), the CPU 23a transmits a control signal to the electronic cassette 21. Then, the reset operation of the FPD 36 is started. The FPD 36 operates the gate driver 39 and the signal processing circuit 40 to sequentially reset the pixels 37 line by line. Then, after the reset operation for all lines is performed a predetermined number of times (1 to 2 times), the operation proceeds to the accumulation operation.

  There is a time difference corresponding to the warm-up time between the start of warm-up by pressing the first button 57a and the start of irradiation by pressing the second button 57b. In the case of the sequential reset method in which the reset is performed line by line, the reset time for all lines is about 100 msec. Since the warm-up time is about 300 msec to about 500 msec, even if the reset operation for all lines is performed once or twice using the warm-up time before the accumulation operation is started, Accumulation start timing does not deviate greatly.

  The accumulation time T2 during which the accumulation operation continues is set to be longer than the maximum X-ray irradiation time. Specifically, even when the accumulation operation is started before the X-ray irradiation starts, the X-ray In order to prevent the accumulation operation from ending before the irradiation is stopped, a time obtained by adding a time considering the difference between the irradiation start timing and the accumulation start timing to the maximum X-ray irradiation time is set. Therefore, as in this example, even if it is detected that the first switch SW1 that generates the warm-up start signal S1 is turned on and the reset operation and the accumulation operation of the FPD 36 are started, the X-ray irradiation ends. The X-ray accumulation operation never ends before.

  Hereinafter, the operation of the above configuration will be described. When imaging with the X-ray imaging system 10, as the preparation for imaging, the height of the electronic cassette 21 set on the imaging table 22 is adjusted so that the position matching the imaging site of the subject H is performed. The height of the X-ray source 13 and the size of the irradiation field are adjusted according to the height of the electronic cassette 21 and the size of the imaging region. When the power of the electronic cassette 21 is turned on, a bias voltage is supplied from the power supply circuit to the pixel 37 of the FPD 36. At this time, the gate driver 39 and the signal processing circuit 40 are stopped. When shooting conditions are input from the console 24, shooting conditions are set in the electronic cassette 21 via the shooting control device 23. In addition, the imaging conditions are manually set in the radiation source control device 14.

  When the preparation for photographing is completed, the engineer presses the first button 57a of the irradiation switch 15. As shown in FIG. 3B, when the first button 57a reaches the first position, the first switch SW1 is turned on. As shown in FIG. 7, when the first switch SW1 is turned on, a warm-up start signal S1 is transmitted to the radiation source controller 14, and the warm-up of the X-ray source 13 is started. On the other hand, when the first button 57 a is pressed, a pressing detection signal having a value corresponding to the pressing force is transmitted from the sensor unit 29 to the imaging control device 23 via the interface converter 31.

  The press detection signal rises due to an increase in the pressing force P applied to the first button 57a. When the first button 57a is pressed down to the first position, the press detection signal reaches the threshold value Vth1. When the pressing detection signal reaches the threshold value Vth1, the imaging control device 23 detects that the first switch SW1 is turned on (S1 detection), and determines that the warm-up of the X-ray source 13 has started. Upon detection of S1, a control signal is transmitted from the imaging control device 23 to the electronic cassette 21, and the reset operation of the FPD 36 is started.

  After the first button 57a is pressed, the second button 57b is pressed after a warm-up time. As shown in FIG. 3C, when the second button 57b reaches the second position, the second switch SW2 is turned on. As shown in FIG. 7, when the second switch SW2 is turned on, an irradiation start signal S2 is transmitted to the radiation source control device 14, and X-ray irradiation is started.

  The FPD 36 performs the reset operation for all the lines a predetermined number of times, and then turns off the TFTs 43 of all the pixels 37 to shift to the accumulation operation. During the accumulation operation, X-rays that have passed through the subject H enter the imaging region 38 of the FPD 36, and signal charges corresponding to the amount of incident X-rays are accumulated in the pixels 37.

  After the X-ray irradiation starts, when the engineer releases the finger from the operation button 57, the pressing of the operation button 57 is released, and the operation button 57 returns to the initial position. Accordingly, the second switch SW2 and the first switch SW1 are turned off in this order, and the signal level of the pressure detection signal output from the sensor unit 29 is also lower than the threshold value Vth1. The timing at which the X-ray irradiation by the X-ray source 13 is stopped and the timing at which the accumulation operation by the FPD 36 is finished are determined by the timer, so even if the operation button 57 is released during the irradiation period and the accumulation period. The operation of the X-ray source 13 and the FPD 36 is not affected.

  The radiation source control device 14 stops the X-ray irradiation when the irradiation time T1 set in the imaging conditions has elapsed. When the preset accumulation time T2 has elapsed, the FPD 36 ends the accumulation operation and proceeds to a read operation. In the reading operation, the FPD 36 reads the signal charges accumulated in the pixels 37 line by line, and the read image data is sequentially recorded in the memory 51. When the signal charges of the pixels 37 for all lines are read, an X-ray image for one screen is recorded in the memory 51. After the read operation is completed, the FPD 36 stops operating.

  Since the X-ray imaging apparatus 12 of the present invention detects the operation force applied to the irradiation switch 15 by the sensor unit 29 detachably attached to the irradiation switch 15 and controls the operation of the FPD 36, FIG. The irradiation period of the X-ray source 13 and the accumulation period of the FPD 36 are synchronized without electrically connecting the X-ray generation apparatus 11 and the X-ray imaging apparatus 12 as in the X-ray imaging system 200 described in Patent Document 1 shown. be able to.

  A comparative example X-ray imaging system 200 shown in FIG. 8 includes an X-ray generation apparatus 201 and an X-ray imaging apparatus 202. In FIG. 8, the same parts as those of the X-ray imaging system 10 of the present invention are denoted by the same reference numerals and description thereof is omitted, and the X-ray imaging system 200 will be described with respect to differences from the present invention.

  The signal cable 204 extending from the irradiation switch 203 of the X-ray generator 201 is bifurcated, one branch portion 204a is connected to the radiation source control device 14, and the other branch portion 204b is connected to the imaging control device 206. The X-ray generator 201 and the X-ray imaging apparatus 202 are electrically connected by a signal cable 204. The irradiation start signal of the irradiation switch 203 is input to both the radiation source control device 14 and the imaging control device 206 through the signal cable 204. Since the connector 204c of the signal cable 204 is connected to the imaging control device 206, the imaging control device 206 is connected to the connection interface of the irradiation switch 203 such as the connector 206a that matches the shape of the connector 204c. An interface is provided.

  When constructing the X-ray imaging system 200 by combining the X-ray imaging apparatus 202 with the X-ray generation apparatus 201 from different manufacturers, both are electrically connected. Sometimes, a connection confirmation test for confirming the electrical connection of the devices 201 and 202 may be required. When performing a connection confirmation test, it is necessary to cooperate with the manufacturer of the X-ray generator 201 such as the presence of a service person of the manufacturer of the X-ray generator 201. The work burden is large for both manufacturers of the radiographic apparatus 202.

  In addition, the imaging control device 206 needs a connection interface suitable for the irradiation switch 203. If there are a plurality of types of connection interfaces depending on the manufacturer and model of the X-ray generator 201, it is necessary to customize the imaging control device 206 according to those types, which is costly for the manufacturer of the X-ray imaging device 202. The burden is heavy.

  In the X-ray imaging system 10 of the present invention, since the sensor unit 29 detachably attached to the irradiation switch 15 and the imaging control device 23 are connected, electrical connection between the X-ray generator 11 and the X-ray imaging device 12 is achieved. Connection is not required, and there is no need for customization such as adding or changing the connection interface of the imaging control device 23 in accordance with the irradiation switch. Further, in the X-ray imaging system 10, the sensor unit 29 and the imaging control device 23 are connected via the interface converter 31, so there is no need to change the connection interface of the imaging control device 23 according to the sensor unit 29. A connection interface installed as a standard in the imaging control device 23 can be used.

  In addition, since the X-ray imaging system 10 uses the sensor unit 29, unlike the X-ray imaging system described in Patent Document 2, the X-ray imaging system 10 performs irradiation detection with an X-ray sensor provided in the vicinity of the imaging region of the FPD. Irradiation start of the X-ray source 13 can be detected regardless of the size of the X-ray irradiation field.

  Further, since the sensor unit 29 is simply attached to the irradiation switch 15 and connected to the imaging control device 23, the X-ray sensor for detecting irradiation in the FPD is used like the X-ray imaging system described in Patent Document 2 and Patent Document 3. There is no need to remodel the FPD as in the case of attaching a pixel or using a pixel in the imaging area of the FPD as a sensor for detecting radiation. Therefore, it can be easily attached to the X-ray imaging apparatus 12 configured with an existing FPD. As described above, the present invention is very easy as a method of synchronizing the X-ray irradiation timing and the accumulation timing without electrically connecting the X-ray generator 11 and the X-ray imaging 12.

  In addition, in a system that uses a sensor that detects the start of irradiation by receiving X-ray irradiation, such as the X-ray imaging system described in Patent Document 2 or Patent Document 3, it is detected that irradiation has started. Yes, but no sign of starting irradiation can be detected. Therefore, the start timing of the accumulation operation of the FPD 36 is delayed with respect to the X-ray irradiation start timing, and a time lag occurs between the two. Since the X-rays irradiated until the accumulation operation starts do not contribute to the X-ray image, if there is a time lag, the subject H is irradiated with unnecessary X-rays.

  As the irradiation switch, a two-stage switch that can input a warm-up start instruction before giving an irradiation start instruction is generally used like the above-described irradiation switch 15, and therefore the first switch SW <b> 1 is turned on by the sensor unit 29 ( By detecting the input of the warm-up start instruction), it is possible to detect a sign of the start of irradiation. Therefore, since the accumulation operation of the FPD 36 can be started before the X-ray irradiation starts, it is not necessary to subject the subject H to unnecessary exposure.

  In the present embodiment, the imaging control device 23 detects that the first switch SW1 is turned on by the sensor unit 29 and causes the FPD 36 to start a reset operation. Therefore, while the FPD 36 is on standby, the FPD 36 Since it is not necessary to always perform the reset operation, it contributes to power saving.

[Second Embodiment]
As in the second embodiment shown in FIG. 9, when the imaging control device 23 detects that the first switch SW1 that generates the warm-up start signal S1 is turned on, the FPD 36 may start the accumulation operation. In this way, the accumulation operation of the FPD 36 can be started more reliably before the start of X-ray irradiation, as compared with the first embodiment in which the reset operation is started by detecting the first switch SW1 being turned on. In the second embodiment, in consideration of the time required for warm-up, the accumulation time T2 for continuing the accumulation operation is set longer than in the case of the first embodiment.

  In the second embodiment, it is preferable to execute the reset operation in a standby state in which the accumulation operation is started so that the dark charge accumulated in the pixel 37 is reset before the accumulation operation is started.

  The reset operation is performed by, for example, a sequential reset method in which the pixels 37 are reset line by line. After the reset to the last line is completed, the reset is started again from the first line (for one screen). The reset operation is repeated. When resetting is completed in the middle of one screen and the storage operation is started, there are areas where resetting has been completed and areas that have not been reset within one screen, and the density of the image changes between the two areas. End up. Therefore, when it is detected that the first switch SW1 is turned on in the middle of one screen, the reset operation is continued until the reset of the last line is completed, and when the reset for one screen is completed, the operation proceeds to the accumulation operation. It is preferable.

  In addition to the sequential reset method, the reset operation method includes a parallel reset method in which multiple lines are reset and an all-pixel simultaneous reset method in which all lines are reset simultaneously. Also good. Even in the case of the parallel reset method, it is preferable to shift to the accumulation operation when the reset for one screen is completed, as in the sequential reset method.

[Third Embodiment]
In the second embodiment, the ON operation of the first switch SW1 is detected to start the accumulation operation of the FPD 36. However, as in the third embodiment shown in FIG. 10, the ON state of the second switch SW2 is detected. The accumulation operation may be started. In this way, since the start of the accumulation operation is delayed compared to the second embodiment in which the first switch SW1 is turned on and the accumulation operation is started, the accumulation operation starts after the X-ray irradiation starts. Compared to Patent Document 2 and Patent Document 3, the delay of the start of the accumulation operation is small.

  This is because, in Patent Document 2 and Patent Document 3, X-ray irradiation is started by operating the irradiation switch, and the irradiation start is detected by receiving the irradiation, so the operation of the irradiation switch and X-ray irradiation are started. If there is a time lag before the start, the start of the accumulation operation is delayed accordingly. On the other hand, since the present invention detects the operation of the irradiation switch 15 and starts the accumulation operation, there is no delay due to the time lag that occurs between the operation of the irradiation switch and the start of X-ray irradiation. is there.

  Further, the third embodiment has an advantage that an X-ray image with less offset noise due to dark charges can be obtained as compared with the first and second embodiments. While the FPD 36 is performing the accumulation operation, dark charge is accumulated in the pixel 37. Therefore, if the accumulation time is long, the amount of dark charge increases. As in the first and second embodiments, when the accumulation operation is started by detecting the first switch SW1 being turned on, the accumulation time T2 is longer than that in the third embodiment in order to consider the warm-up time. Is set. This is remarkable in the case of the second embodiment shown in FIG. In the third embodiment, the warm-up time does not have to be taken into consideration, so that the accumulation time T2 can be set shorter than in the first and second embodiments. Since the accumulation time T2 is short, the amount of dark charge is reduced, and offset noise caused by dark charge is also reduced.

  As shown in FIG. 11, the first method for detecting that the second switch SW2 is turned on is that the threshold value for determining the signal level of the press detection signal output from the sensor unit 29 in the imaging control device 23 is set as described above. In this method, the threshold value Vth2 is set higher than the threshold value Vth1. The threshold value Vth2 is a value corresponding to the pressing force P2 applied to the operation button 57 and necessary for turning on the second switch SW2, and is set in the memory 23e.

  Even if the signal level of the press detection signal reaches the threshold value Vth1, the imaging control device 23 does not transmit the control signal to the FPD 36, and the second switch SW2 when the signal level of the press detection signal reaches the threshold value Vth2. Is detected (S2 detection). The imaging control device 23 determines that X-ray irradiation from the X-ray source 13 has been started by S2 detection, and causes the FPD 36 to start an accumulation operation.

  As a second method of detecting that the second switch SW2 is turned on, there is a method of using a sensor unit 71 with an elastic member such as a sponge 72 as shown in FIG. According to this, it is possible to detect that the second switch SW2 is turned on without changing the threshold value Vth1 (see FIG. 6) to the threshold value Vth2 (see FIG. 11).

  The sensor unit 71 includes a pressure sensor 61, a sponge 72 disposed above the pressure sensor 61, and a case 73 that houses the pressure sensor 61 and the sponge 72. The sponge 72 absorbs a part of the pressing force P and reduces the pressure transmitted to the pressure sensor 61.

  Specifically, the sponge 72 has the following hardness. When a pressing force P1 necessary to turn on the first switch SW1 is applied to the operation button 57, a part of the pressing force P1 is absorbed and the pressure sensor 61 has a pressure smaller than the pressing force P1. On the other hand, when a pressing force P2 necessary to turn on the second switch SW2 is applied to the operation button 57, a part of the pressing force P2 is absorbed and the pressing force is applied to the pressure sensor 61. It is the hardness which conveys the pressure of P1. In this way, when the second switch SW2 is turned on, the signal level of the pressure detection signal of the sensor unit 71 reaches the threshold value Vth1, so the imaging control device 23 causes the signal level of the pressure detection signal to reach the threshold value Vth1. It is detected that the second switch SW2 is turned on.

  As an example of using the sensor that outputs a signal level corresponding to the applied pressure as the pressure sensor 61, a pressure detection signal is not output to the pressure sensor when the pressure is not applied (the output is “0”). There is also a binary output type pressure sensor that outputs a pressure detection signal (output is “1”) when a predetermined pressure is applied. When such a binary output type pressure sensor is used as the pressure sensor 61, the sensor unit 71 with a sponge is effective.

  Since the output of the binary output type pressure sensor is “0” or “1”, in order to selectively detect whether the first switch SW1 and the second switch SW2 are turned on, the threshold value Vth is changed. The first method cannot be used. Therefore, for example, when the first switch SW1 is turned on, the sponge 72 is not used, and when the second switch SW2 is turned on, the sponge 72 is used. It is possible to selectively detect whether the first switch SW1 and the second switch SW2 are on.

  In addition, when detecting whether the first switch SW1 is turned on instead of the presence of the sponge 72, a relatively soft sponge is used, and when detecting the second switch SW2 being turned on, a relatively hard sponge is used. As described above, sponges 72 having different hardnesses may be used properly.

[Fourth Embodiment]
In the first to third embodiments, the example in which the on-state of the first switch SW1 and the second switch SW2 is selectively detected has been described. However, as in the fourth embodiment shown in FIGS. 13 and 14, the first switch You may detect ON of both SW1 and 2nd switch SW2. In this case, as shown in FIG. 13, in the memory 23e of the imaging control device 23, the threshold value Vth1 corresponding to the pressing force P1 required to turn on the first switch SW1 and the second switch SW2 are turned on. Two threshold values Vth of the threshold value Vth2 corresponding to the necessary pressing force P2 are set. The CPU 23a of the imaging control device 23 monitors the signal level of the pressure detection signal of the sensor unit 29 similar to the first and second embodiments, and turns on the first switch SW1 when the signal level reaches the threshold value Vth1. When the threshold value Vth2 is detected, the second switch SW2 is turned on.

  As illustrated in FIG. 14, the imaging control device 23 causes the FPD 36 to start a reset operation when it detects that the first switch SW1 is turned on, and starts a storage operation when it detects that the second switch SW2 is turned on.

  In the fourth embodiment, similarly to the first embodiment (see FIG. 7), the reset operation is started by detecting the ON of the first switch SW1, but in the first embodiment, the transition from the reset operation to the accumulation operation is not performed. Done automatically. Therefore, in rare cases, for example, even when the operation of the irradiation switch 15 is interrupted without pressing the second button 57b after the first button 57a of the irradiation switch 15 is pressed, the first switch SW1. By turning on, the FPD 36 starts the accumulation operation after the reset operation.

  According to the fourth embodiment, the reset operation is started after the first switch SW1 is turned on by pressing the first button 57a, but the operation of the irradiation switch 15 is interrupted without pressing the second button 57b. However, the accumulation operation is not started.

[Fifth Embodiment]
Like the X-ray imaging system 80 of the fifth embodiment shown in FIG. 15, the sensor unit 29 and the irradiation detection sensor 81 provided in the electronic cassette 21 are combined to allow the sensor unit 29 to set the timing for starting X-ray irradiation. In addition to detection, the irradiation detection sensor 81 may detect the timing of X-ray irradiation stop. Since the configuration of the X-ray imaging system 80 is the same as that of the X-ray imaging system 10 shown in FIG. 1 except that the irradiation detection sensor 81 is provided, the same portions are denoted by the same reference numerals and description thereof is omitted. Hereinafter, the difference will be mainly described.

  The irradiation detection sensor 81 is a sensor that receives X-ray irradiation and outputs an irradiation detection signal corresponding to the amount of incident X-rays. The irradiation detection signal is input to the imaging control device 23 through the communication cable 26. The irradiation detection sensor 81 is provided in the FPD 36 of the electronic cassette 21 and is disposed in the vicinity of the imaging region 38. The imaging control device 23 monitors the signal level of the irradiation detection signal and detects that the X-ray irradiation by the X-ray source 13 is stopped.

  As shown in the timing chart shown in FIG. 16, the imaging control device 23 confirms that the first switch SW1 is turned on based on the press detection signal of the sensor unit 29, as in the second embodiment (see FIG. 9). Detecting, the operation of the FPD 36 is shifted from the reset operation to the accumulation operation. Then, the signal level of the irradiation detection signal of the irradiation detection sensor 81 is monitored, and when the signal level becomes equal to or lower than a predetermined position, it is detected that the irradiation is stopped. When the irradiation stop is detected, the FPD 36 is shifted from the accumulation operation to the reading operation.

  Or similarly to 1st Embodiment (refer FIG. 7), it detects that 1st switch SW1 was turned ON based on the press detection signal of the sensor unit 29, makes FPD36 start reset operation | movement, and performs reset operation | movement. You may make it transfer to accumulation | storage operation | movement after completion | finish. Further, as shown in the timing chart of FIG. 17, it is detected that the first switch SW1 is turned on, the reset operation is started, and the reset operation is detected by detecting that the second switch SW2 is turned on. The accumulation operation may be started after finishing. The detection of irradiation stop is the same as in FIG.

  In this way, by detecting the stop of irradiation and terminating the accumulation operation, the accumulation time T2 can be shortened compared to the above-described embodiment in which the accumulation operation is performed for a predetermined time. As described above, when the accumulation time T2 is long, the amount of dark charge also increases. Therefore, by shortening the accumulation time T2, it is possible to reduce offset noise due to dark charge with respect to the X-ray image.

  Further, as shown in FIG. 18, in addition to stopping the irradiation, the irradiation detection sensor 81 may detect the start of irradiation. In this case, the imaging control device 23 causes the FPD 36 to start the reset operation by detecting that the first switch SW1 is turned on by the sensor unit 29. When the irradiation detection sensor 81 detects the start of irradiation, the FPD 36 starts the accumulation operation. When the irradiation detection sensor 81 detects the irradiation stop, the accumulation operation is ended and the reading operation is started. . Since the timing for starting the reset operation is obtained by the press detection signal output from the sensor unit 29, the FPD 36 does not need to perform the reset operation constantly during standby, which contributes to power saving.

  Although the example in which the irradiation detection sensor 81 is provided in the vicinity of the imaging region 38 of the FPD 36 has been described, a phototimer disposed between the FPD 36 and the subject H may be used. As is well known, the phototimer is a device that measures the amount of X-ray irradiation in order to perform automatic exposure control (AEC) of the FPD 36 and is used in combination with the FPD 36.

  In the above embodiment, the example in which the sensor unit 29 and the imaging control device 23 are connected via the interface converter 31 has been described. However, the sensor unit 29 and the imaging control device 23 are directly connected without providing the interface converter 31. May be. In this case, since the imaging control device 23 and the sensor unit 29 are directly connected, a connection interface for connecting the sensor unit 29 to the imaging control device 23 is required. However, since the sensor unit 29 and the imaging control device 23 can be designed, developed, and manufactured by the manufacturer of the X-ray imaging device 12, a connection interface suitable for an irradiation switch from different manufacturers is provided in the imaging control device 23. Compared to the above, it is advantageous for the manufacturer of the X-ray imaging apparatus 12 to have a high degree of freedom in design, development and manufacture.

  In the above-described embodiment, the example in which the imaging control device 23 is configured separately from the electronic cassette 21 has been described. However, the electronic cassette and the imaging control device are integrated, for example, the function of the imaging control device 23 is built in the control circuit 41. You may comprise. In this case, the sensor unit 29 is directly connected to the electronic cassette.

  In the above embodiment, the irradiation switch having the operation button provided on the upper part is described as an example. However, the irradiation switch having the operation button provided on the grip portion may be used, and the operation button is disposed anywhere. Also good. The operation button may have any shape as long as the operation force can be detected by the sensor unit.

  Further, as the irradiation switch, the two-step switch in which the first button that turns on the first switch SW1 is pressed and then the second button that turns on the second switch SW2 is pressed together with the first button has been described as an example. The switch may not be a two-stage switch, for example, an irradiation switch that can be operated by pressing the first button and the second button independently. In this case, the sensor unit is attached to the first button when detecting that the first switch SW1 is turned on, and attached to the second button when detecting that the second switch SW2 is turned on. . When it is detected that both switches SW1 and SW2 are turned on, sensor units may be provided on both the first button and the second button.

  Further, as the irradiation switch, the first switch SW1 may be omitted, and only the second switch SW2 that generates the irradiation start signal may be provided. Among X-ray sources, there are a fixed anode type in which the anode does not rotate, and a cold cathode type source that does not require preheating. In the case of such an X-ray source, warm-up may be unnecessary. In that case, an irradiation switch in which only the second switch SW2 is provided is used. Even in the case of an X-ray source that requires warm-up, an irradiation start signal is input from the irradiation switch to the radiation source controller, and the radiation source controller starts warm-up based on the irradiation start signal. If irradiation is started after completion, it is not necessary to provide the first switch SW1 for generating a warm-up start signal in the irradiation switch.

  In this case, the imaging control device detects that the second switch SW2 is turned on by the sensor unit, starts the reset operation for the FPD, and starts the accumulation operation after the reset operation ends. Alternatively, in the case of an FPD that is performing a reset operation during standby, it is detected that the second switch SW2 has been turned on and the accumulation operation is started.

  In the above embodiment, the example in which the sensor unit 29 is detachably attached to the irradiation switch 15 with the double-sided tape 63 has been described. However, the attachment unit of the sensor unit 29 may be other than the double-sided tape 63. For example, a method is conceivable in which the attaching means is constituted by an engaging portion that is detachably engaged with the operation button 57 on the case 62 of the sensor unit 29.

  In the above embodiment, the electronic cassette which is a portable X-ray image detection apparatus has been described as an example. However, the present invention may be applied to a stationary X-ray image detection apparatus.

  In the above embodiment, the indirect conversion type has been described as an example of the FPD. However, the present invention may be applied to a direct conversion type FPD using a conversion layer (such as amorphous selenium) that directly converts X-rays into electric charges.

  In each of the above embodiments, X-rays have been described as an example of radiation. However, the present invention may use radiation other than X-rays, such as γ-rays. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 10, 80 X-ray imaging system 11 X-ray generator 12 X-ray imaging apparatus 14 Radiation source control apparatus 15 Irradiation switch 23 Imaging control apparatus 23a CPU
23c, 23d connector 23e memory 29, 71 sensor unit 31 interface converter 32 signal cable 31a, 31b connector 41 control circuit 57 operation button 57a first button 57b second button 61 pressure sensor 81 irradiation detection sensor 21 electronic cassette 36 FPD

Claims (15)

A radiation image detector that receives radiation irradiated from a radiation source and transmitted through the subject and detects a radiation image of the subject; and
A sensor unit which is detachably attached to an irradiation switch operated to start irradiation of the radiation by the radiation source, detects a pressing force applied to the irradiation switch during operation, and generates a pressing detection signal;
A radiation imaging apparatus comprising: control means for controlling the operation of the radiation image detector based on the press detection signal input from the sensor unit.   The operation of the radiation image detector includes an accumulation operation for accumulating signal charges according to the amount of incident radiation, and a dark charge that is executed before the accumulation operation and is generated regardless of whether or not the radiation is incident. The radiation imaging apparatus according to claim 1, further comprising a reset operation for resetting.   The radiographic apparatus according to claim 2, wherein the control unit causes the radiological image detector to start the accumulation operation based on the pressing detection signal.   The radiographic apparatus according to claim 2, wherein the control unit causes the radiological image detector to start the reset operation based on the pressing detection signal. The irradiation switch is turned on when a first pressing force is applied, and generates a warm-up start signal for starting a warm-up for the radiation source, and the first pressing A two-stage switch having a second switch that is turned on when a second pressing force higher than the pressure is applied and generates an irradiation start signal for starting irradiation to the radiation source;
5. The control unit according to claim 2, wherein the control unit detects that at least one of the first switch and the second switch is turned on based on the press detection signal. 6. The radiation imaging apparatus described in 1.   The radiographic apparatus according to claim 5, wherein the control unit detects that the first switch is turned on and causes the radiological image detector to start the reset operation.   The radiation imaging apparatus according to claim 6, wherein the radiation image detector shifts to the accumulation operation after the reset operation is completed.   The radiation control apparatus according to claim 5, wherein the pre-control unit detects that the first switch is turned on and causes the radiation image detector to start the accumulation operation.   6. The radiographic apparatus according to claim 5, wherein the control unit detects that the second switch is turned on and causes the radiological image detector to start the accumulation operation. The sensor unit outputs the pressing detection signal having a signal level different according to the first pressing force and the second pressing force to the control means,
The control means detects that each of the first switch and the second switch is turned on in accordance with the signal level, and when the control means detects that the first switch is turned on, 6. The radiation imaging apparatus according to claim 5, wherein the reset operation is started, and the reset operation is ended and the accumulation operation is started when it is detected that the second switch is turned on. The sensor unit absorbs a part of the pressure sensor that outputs a first pressing detection signal in response to the first pressing force and the second pressing force applied to the irradiation switch. And an elastic member that reduces the pressure transmitted to the pressure sensor to the first pressing force,
The control means detects that the second switch is turned on based on the first press detection signal output from the pressure sensor when the second operating force is applied. Item 10. The radiographic apparatus according to Item 5 or 9. Furthermore, an irradiation detection sensor for detecting whether or not the radiation source emits radiation,
The radiographic apparatus according to any one of claims 2 to 11, wherein the control unit detects that the irradiation of the radiation has been stopped by the irradiation detection sensor, and ends the accumulation operation. .   The radiographic apparatus according to claim 1, wherein the radiological image detector and the control unit are separate bodies.   The radiation imaging apparatus according to claim 1, wherein the sensor unit and the control unit are connected via an interface converter. A radiation source that emits radiation;
A radiation image detector that receives radiation irradiated from a radiation source and transmitted through the subject and detects a radiation image of the subject; and
A sensor unit which is detachably attached to an irradiation switch operated to start irradiation of the radiation by the radiation source, detects a pressing force applied to the irradiation switch during operation, and generates a pressing detection signal;
A radiographic system comprising: control means for controlling the operation of the radiographic image detector based on the press detection signal input from the sensor unit.

Images