JP5623334B2 - Electronic cassette and radiation imaging apparatus - Google Patents

Description

  The present invention relates to an electronic cassette that receives radiation and detects a radiation image, and a radiation imaging apparatus using the electronic cassette.

  A radiation imaging system, for example, an 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 driving of the X-ray source, and an irradiation switch for inputting an X-ray irradiation start instruction. ing. The X-ray imaging apparatus has 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 driving of the X-ray image detection apparatus.

  Recently, an X-ray image detection apparatus using a flat panel detector (FPD) as a detector instead of an X-ray film or an imaging plate (IP) has become widespread. In the FPD, pixels that accumulate signal charges corresponding to the amount of incident X-rays 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. The electronic cassette is used by attaching it to an existing imaging table for film cassettes and IP cassettes or a dedicated imaging table. In addition, the electronic cassette is placed on the bed or held by the subject itself to image areas that are difficult to capture with the stationary type. Used. 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.

  There is a type of electronic cassette that has a built-in battery to cover the drive power of each unit and exchanges signals with the imaging control device by wireless communication. In such a type, the battery can be taken out from the electronic cassette and set in a dedicated cradle for charging, or the electronic cassette itself can be set in the cradle and charged while the battery is built in the electronic cassette.

  In addition, an electromagnetic induction type or magnetic resonance type non-contact power feeding device is provided near the electronic cassette, and power for charging a battery in the electronic cassette is supplied from the non-contact power feeding device (patent). References 1 and 2). In Patent Document 1, in order to prevent noise caused by non-contact power supply from being superimposed on an image and degrading the image quality, non-contact power supply is prohibited during photographing. In Patent Document 2, for the same purpose as Patent Document 1, non-contact power feeding is prohibited when an image is transmitted to an external device.

JP 2010-158513 A JP 2010-223863 A

  In addition to the electromagnetic induction method and the magnetic resonance method mentioned above, there is an electric field coupling method as a non-contact power supply method. In the electric field coupling method, two flat electrodes (feeding electrode that supplies AC power and receiving electrode on the load side) are brought close to each other and faced to propagate power by electric field coupling between the two electrodes. The structure is simple, downsizing, cost reduction, and easy control. In addition, in other methods, power transmission efficiency is significantly reduced unless the positioning of the power supply device and the power-receiving device is strict. However, the electric field coupling method has a relatively high degree of freedom in alignment and does not require strict alignment. It is.

  As described above, the electric field coupling method has various advantages. However, when the electric field coupling type non-contact power feeding is applied to the charging of the battery with the built-in electronic cassette, the receiving electrode is provided on the electronic cassette. However, it is inevitable to increase the size of the electronic cassette. Further, as described in Patent Documents 1 and 2, the need for measures against image quality degradation due to noise is the same as other methods.

  The present invention has been made in view of the above-described problems, and its purpose is to achieve downsizing of an electronic cassette while using electric field coupling type non-contact power feeding, and to reliably prevent image quality deterioration due to noise. It is in.

  In order to achieve the above object, an electronic cassette according to the present invention includes a radiation image detector that receives radiation irradiated from a radiation source and detects a radiation image, a housing that houses the radiation image detector, A battery for supplying electric power; a charging circuit for the battery; and a power receiving electrode for receiving electric power for charging the battery from a non-contact power supply device; and the housing opposite to the imaging surface of the radiation image detector A power receiving electrode that is disposed on the bottom surface in parallel with the imaging surface and receives power from the power feeding electrode of the non-contact power feeding device by electric field coupling, and the connection between the power receiving electrode and the charging circuit or the power receiving electrode and the housing ground is selectively used. And a control means for controlling the switching operation of the changeover switch, and during and / or before the radiographic image detector detects the radiographic image. While the radiographic image data is being transmitted from the radiographic image detector to the external device, the power receiving electrode and the housing ground are connected to cause the power receiving electrode to function as an electromagnetic shield. In other cases, the power receiving electrode And a control means for connecting the charging circuit so as to be able to receive power.

The control means connects the power receiving electrode and the housing ground when radiation irradiation is started. In this case, the control means may switch the changeover switch during non-irradiation of the radiation to detect the images in the radiation image detector, correcting the image data thus obtained, the switching noise of the switching switch appeared As the data , the correction data is preferably subtracted from the data of the radiation image. The correction data is preferably acquired at regular intervals.

  The control means connects the power receiving electrode and the housing ground during a period from when an imaging condition is input to the external device to when radiation irradiation is started, for example, when the imaging condition is received from the external device. It may be when the subject is set on the imaging table.

  The control means connects the power receiving electrode and the housing ground when the battery is fully charged or when the electronic cassette is removed from the holder of the photographing stand.

  The changeover switch may be switched according to an operation of an operation member for instructing charging / non-charging of the battery.

  In the case where the housing includes a front cover that covers the imaging surface side of the radiation image detector and a back cover that covers the opposite side, the back cover may serve as the power receiving electrode. It is preferable that an insulating member having a U-shaped cross section is fitted into a connection portion between the back cover and other components.

  A radiation imaging apparatus of the present invention includes a radiation image detector that receives radiation irradiated from a radiation source and detects a radiation image, a housing that houses the radiation image detector, a battery that supplies power to each unit, A charging circuit for the battery; and a power receiving electrode for receiving power for charging the battery from a non-contact power feeding device; and parallel to the imaging surface on the bottom surface of the casing opposite to the imaging surface of the radiation image detector A power receiving electrode that receives power from a power feeding electrode of a non-contact power feeding device by electric field coupling, a selector switch that selectively switches a connection between the power receiving electrode and the charging circuit, or the power receiving electrode and the housing ground; and Control means for controlling the switching operation of the changeover switch, during detection of a radiographic image by the radiographic image detector and / or outside of the radiographic image detector. While the radiographic image data is being transmitted to the apparatus, the power receiving electrode and the housing ground are connected to cause the power receiving electrode to function as an electromagnetic shield. In other cases, the power receiving electrode and the charging circuit are connected. An electronic cassette having a control means for enabling power reception, a photographing stand having a holder in which the electronic cassette is detachably accommodated, and a photographing control device for comprehensively controlling the operation of the electronic cassette. It is characterized by providing.

  The non-contact power feeding device is built in the holder of the photographing stand. Further, the holder of the photographing stand is made into an electromagnetic shield.

  According to the present invention, since the electric field coupling type power receiving electrode is also used as an electromagnetic shield and the power receiving electrode functions as an electromagnetic shield during photographing and during transmission of image data, the electronic cassette can be reduced in size. Thus, image quality deterioration due to noise can be surely prevented.

It is the schematic which shows the structure of a X-ray imaging system. It is a perspective view which shows the structure of an electronic cassette. It is sectional drawing which shows the structure of an electronic cassette. It is a figure which shows the electrical structure of an electronic cassette and FPD. It is a figure which shows the structure of the electric power receiving function of an electric power feeder and an electronic cassette. It is a flowchart which shows the operation | movement procedure of an electronic cassette. It is a flowchart which shows the operation | movement procedure of an electronic cassette. It is sectional drawing which shows the structure of the electronic cassette which used the receiving electrode as the back cover.

  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 driving of 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 an X-ray irradiation field emitted by the X-ray tube 13a.

  The X-ray tube 13a includes 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 a plurality of lead plates that shield X-rays arranged in a cross-beam shape, and an irradiation opening that transmits X-rays is formed in the center. By moving the position of the lead plate, The irradiation field is limited by changing the size of the irradiation opening.

  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 X-ray irradiation time. 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 apparatus 11 of this example does not have a communication function with the X-ray imaging apparatus 12, and radiographers can set imaging conditions such as tube voltage, tube current, and irradiation time through the operation panel of the radiation source control apparatus 14. Set manually.

  The irradiation switch 15 is operated by a radiologist and is connected to the radiation source control device 14 by a signal cable 17. The irradiation switch 15 is a two-stage push switch, which generates a warm-up start signal for starting the warm-up of the X-ray source 13 by pressing the single stage, and for starting the irradiation of the X-ray source 13 by pressing the two-stage. The irradiation start signal is generated. These signals 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. When the warm-up start signal is received, the radiation source control device 14 activates the heater to preheat the filament, and also starts the rotation of the target to reach the target rotational speed. The time required for warm-up is about 200 msec to 1500 msec. The radiologist inputs a warm-up start instruction by pressing the irradiation switch 15 in one stage, and then inputs the irradiation start instruction by pressing in two stages after a necessary interval for warm-up.

  When receiving the irradiation start signal, 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. Then, when the irradiation time set in the imaging conditions has elapsed, X-ray irradiation is stopped. 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 to a range of about 500 msec to about 2 s, and the irradiation time Is set with this maximum irradiation time as the upper limit.

  The X-ray imaging apparatus 12 includes an electronic cassette 21, a standing position imaging table 22 a, a lying position imaging table 22 b, an imaging control device 23, and a console 24. The electronic cassette 21 includes an irradiation detection sensor 25, an FPD 26 (see also FIGS. 2 to 4), and a portable casing 27 (see FIGS. 2 and 3) that houses the FPD 26. An X-ray image is output upon receiving X-rays that have been irradiated and transmitted through the subject H. The electronic cassette 21 has a substantially rectangular shape and a flat shape, and the plane size is substantially the same size as the film cassette and the IP cassette (size conforming to the international standard ISO 4090: 2001).

  The irradiation detection sensor 25 is disposed in the vicinity of the imaging surface 28 of the FPD 26 (see FIGS. 3 and 4). The irradiation detection sensor 25 receives the X-ray irradiation and outputs an irradiation detection signal corresponding to the incident amount of the X-ray. The irradiation detection signal is input to the imaging control device 23 by the composite cable 29 or wirelessly. The imaging control device 23 monitors the signal level of the irradiation detection signal and detects that X-ray irradiation by the X-ray source 13 has started.

  The standing position imaging table 22a and the recumbent imaging table 22b have holders 30a and 30b to which the electronic cassette 21 can be detachably attached, respectively, and the imaging surface 28 on which X-rays are incident faces the X-ray source 13. The electronic cassette 21 is held. In the figure, a state in which photographing is performed on the standing photographing stand 22a is shown. The X-ray source 13 can be moved within a predetermined range in the imaging room by a moving mechanism (not shown) made of rails or the like laid on the ceiling of the imaging room, and is shared by the standing imaging table 22a and the standing imaging table 22b. Is done.

  Since the size of the casing 27 is substantially the same as that of the film cassette or the IP cassette, the electronic cassette 21 can be attached to an existing photographing stand for the film cassette or the IP cassette. A plurality of electronic cassettes 21 are provided in one room, for example, two for each of the imaging tables 22a and 22b. The electronic cassette 21 can be used as a single unit by being placed on the bed on which the subject H is supine or being held by the subject itself, instead of being set on the standing position photographing stand 22a or the lying position photographing stand 22b. It is.

  The imaging control device 23 is connected to the electronic cassette 21 so as to be communicable by a wired method using a composite cable 29 or a wireless method using an antenna 31 (see FIG. 2 and the like), and controls the electronic cassette 21. Specifically, the imaging conditions are transmitted to the electronic cassette 21 to set the signal processing conditions (such as the gain of the amplifier 74) of the FPD 26, and the operation of the FPD 26 is indirectly controlled. The image data from 21 is transmitted to the console 24.

  The imaging control device 23 communicates with the CPU 23a that centrally controls the device, the electronic cassette 21 by a wired method or a wireless method, and a communication unit 23b that communicates with the console 24 via the communication cable 32, and a memory 23c. Have. The communication unit 23b and the memory 23c are connected to the CPU 23a. The memory 23c stores a control program executed by the CPU 23a.

  The console 24 transmits imaging conditions to the imaging control device 23 and performs various image processing such as offset correction and gain correction on the X-ray image data transmitted from the imaging control device 23. In addition to being displayed on the display of the console 24, the processed X-ray image 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.

  The console 24 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. 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 a radiographer. The radiologist confirms the contents of the examination order on the display, and inputs imaging conditions corresponding to the contents through the operation screen of the console 24.

  2 to 4, the electronic cassette 21 includes an antenna 31 and a battery 41, and wireless communication with the imaging control device 23 is possible. The battery 41 supplies power for operating each part of the electronic cassette 21. A relatively small battery 41 is used so as to fit in the thin electronic cassette 21. The battery 41 can be charged with electric power from a power supply device 81 (see FIG. 5) built in the holders 30a and 30b of the imaging tables 22a and 22b. Further, the battery 41 can be taken out by opening the lid 42 provided on one side of the electronic cassette 21 and can be taken out from the electronic cassette 21 and set in a dedicated cradle for charging. . The antenna 31 transmits and receives radio waves for wireless communication to and from the imaging control device 23.

  The electronic cassette 21 is provided with a socket 43 in addition to the antenna 31. The socket 43 is disposed on one side surface of the electronic cassette 21 opposite to the lid 42. The socket 43 is provided for wired connection with the imaging control device 23, and the connector 44 of the composite cable 29 connected to the imaging control device 23 is inserted into the socket 43. The composite cable 29 is used when wireless communication between the electronic cassette 21 and the imaging control device 23 becomes impossible due to a shortage of the remaining amount of the battery 41 or the like. When the connector 44 is inserted into the socket 43 and the composite cable 29 is used, wired communication with the imaging control device 23 becomes possible and power can be supplied from the imaging control device 23 to the electronic cassette 21.

  The antenna 31 and the socket 43 are connected to the communication unit 45. The communication unit 45 mediates transmission / reception of various information and signals including image data between the antenna 31 or the socket 43 and the control circuit 46 and the memory 47.

  The FPD 26 includes a TFT active matrix substrate 51, and includes an imaging surface 28 in which a plurality of pixels 52 that accumulate signal charges corresponding to the amount of incident X-rays are arranged on the substrate 51. The plurality of pixels 52 are two-dimensionally arranged in a matrix of n rows (x direction) × m columns (y direction) at a predetermined pitch.

  The FPD 26 further includes a scintillator (phosphor) 53 that converts X-rays into visible light, and is an indirect conversion type in which visible light converted by the scintillator 53 is photoelectrically converted by the pixels 52. The scintillator 53 is made of CsI (cesium iodide), GOS (gadolinium oxysulfide), or the like, and is disposed so as to face the entire imaging surface 28 on which the pixels 52 are arranged. Note that a direct conversion type FPD using a conversion layer (such as amorphous selenium) that directly converts X-rays into electric charges may be used.

  The casing 27 includes a front cover 54 that covers the FPD 26 including the TFT active matrix substrate 51 and the scintillator 53 from the front side that irradiates X-rays, and a back cover 55 that covers the rear side on the opposite side. The front cover 54 is made of a conductive resin, and the back cover 55 is made of an insulating resin. The front cover 54 is formed with a rectangular opening, and a transmission plate 56 is attached to the opening. The transmission plate 56 is made of a carbon material that is lightweight, has high rigidity, and has high X-ray permeability.

  On the back side of the FPD 26, a base plate 57, a plurality of circuit boards 58, and a power receiving electrode 61 are arranged in this order. The base plate 57 is made of, for example, stainless steel, and the TFT active matrix substrate 51 is attached to the front side, and the circuit board 58 is attached to the back side. The circuit board 58 includes a gate driver 62 that controls the readout of signal charges by driving the pixels 52, a signal processing circuit 63 that converts the signal charges read from the pixels 52 into digital data, and outputs these operations. Circuit elements constituting the control circuit 46 and the like to be controlled are formed. The circuit board 58 is connected to the TFT active matrix substrate 51 and the power receiving electrode 61 by a flexible cable or the like (not shown).

  The power receiving electrode 61 is made of a metal such as copper or aluminum. The power receiving electrode 61 is a substantially flat electrode having substantially the same shape and size as the back cover 55, and is attached to the bottom plate of the back cover 55. The power receiving electrode 61 and the power feeding electrode 82 of the power feeding device 81 are non-electric field coupling (also referred to as capacitive coupling) systems that feed power from the power feeding electrode 82 to the power receiving electrode 61 when the electronic cassette 21 is set in the holders 30a and 30b. Perform contact power supply.

  The pixel 52 includes a photodiode 64 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 64, and a switching element. A thin film transistor (TFT) 65 is provided.

  The photodiode 64 has a structure in which a semiconductor layer (for example, PIN type) that generates electric charge and an upper electrode and a lower electrode are arranged above and below the semiconductor layer. The photodiode 64 has a TFT 65 connected to the lower electrode and a bias line 66 connected to the upper electrode. The bias line 66 is provided by the number of rows (n rows) of the pixels 52 in the imaging surface 28 and connected. It is bound to 67. The connection 67 is connected to a bias power source 68. A bias voltage Vb is applied from the bias power source 68 to the upper electrode of the photodiode 64 through the connection 67 and the bias line 66. An electric field is generated in the semiconductor layer by application of the bias voltage Vb, and 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 65 has a gate electrode connected to the scanning line 69, a source electrode connected to the signal line 70, and a drain electrode connected to the photodiode 64. The scanning lines 69 and the signal lines 70 are wired in a grid pattern. The scanning lines 69 are the number of rows of the pixels 52 (n rows) in the imaging surface 28, and the signal lines 70 are the number of columns of the pixels 52 (m columns). Min) each is provided. The scanning line 69 is connected to the gate driver 62, and the signal line 70 is connected to the signal processing circuit 63.

  The gate driver 62 drives the TFT 65 to accumulate a signal charge corresponding to the incident amount of X-rays in the pixel 52, a read (reading) operation for reading the signal charge from the pixel 52, and a reset (empty reading). ) Make an action. The control circuit 46 controls the start timing of each operation performed by the gate driver 62.

  In the accumulation operation, the TFT 65 is turned off, and signal charges are accumulated in the pixel 52 during that time. In the read operation, gate pulses G1 to Gn for simultaneously driving the TFTs 65 in the same row are generated sequentially from the gate driver 62, the scanning lines 69 are sequentially activated one by one, and the TFTs 65 connected to the scanning lines 69 are one row at a time. Turn on. The charge accumulated in the capacitor of the pixel 52 is read out to the signal line 70 and input to the signal processing circuit 63 when the TFT 65 is turned on.

  Dark charges are generated in the semiconductor layer of the photodiode 64 regardless of whether X-rays are incident. This dark charge is accumulated in the capacitor because the bias voltage Vb is applied. Since the dark charge generated in the pixel 52 becomes a noise component for the image data, a reset operation is performed to remove this. The reset operation is an operation for sweeping out dark charges generated in the pixels 52 through the signal line 70.

  For example, the reset operation is performed by a sequential reset method in which the pixels 52 are reset row by row. In the sequential reset method, similarly to the signal charge reading operation, gate pulses G1 to Gn are sequentially generated from the gate driver 62 to the scanning line 69 to turn on the TFTs 65 of the pixels 52 one row at a time. While the TFT 65 is on, dark charge flows from the pixel 52 to the integrating amplifier 71 through the signal line 70. In the reset operation, unlike the read operation, the charge accumulated in the integrating amplifier 71 is not read by the multiplexer (MUX) 72, and the reset pulse RST is generated from the control circuit 46 in synchronization with the generation of the gate pulses G1 to Gn. Is output, and the integrating amplifier 71 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 signal processing circuit 63 includes an integrating amplifier 71, a MUX 72, an A / D converter 73, and the like. The integrating amplifier 71 is individually connected to each signal line 70. The integrating amplifier 71 includes an operational amplifier and a capacitor connected between the input and output terminals of the operational amplifier, and the signal line 70 is connected to one input terminal of the operational amplifier. The other input terminal of the integrating amplifier 71 is connected to the ground (GND). The integrating amplifier 71 integrates the charges input from the signal line 70, converts them into voltage signals D1 to Dm, and outputs them. The MUX 72 is connected to the output terminal of the integration amplifier 71 in each column via an amplifier 74 and a sample hold (S / H) unit 75. An A / D converter 73 is connected to the output side of the MUX 72.

  The MUX 72 sequentially selects one integration amplifier 71 from a plurality of integration amplifiers 71 connected in parallel, and serially inputs voltage signals D1 to Dm output from the selected integration amplifier 71 to the A / D converter 73. . The A / D converter 73 converts the input voltage signals D1 to Dm into digital data and outputs the digital data to the memory 47 built in the housing 27 of the electronic cassette 21. An amplifier may be connected between the MUX 72 and the A / D converter 73.

  When the voltage signal D1 to Dm for one row is read from the integrating amplifier 71 by the MUX 72, the control circuit 46 outputs a reset pulse RST to the integrating amplifier 71 and turns on the reset switch 71a of the integrating amplifier 71. As a result, the signal charge for one row accumulated in the integrating amplifier 71 is reset. When the integrating amplifier 71 is reset, the gate pulse of the next row is output from the gate driver 62, and reading of the signal charges of the pixels 52 of the next row is started. These operations are sequentially repeated to read the signal charges of the pixels 52 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 47. The image data is read from the memory 47 and output to the imaging control device 23 through the communication unit 45. Thus, an X-ray image of the subject H is detected.

  In the FPD 26, the irradiation detection sensor 25 detects the start of X-ray irradiation while repeatedly performing the reset operation. When the X-ray irradiation start is detected by the irradiation detection sensor 25, the control circuit 46 shifts the operation of the FPD 26 from the reset operation to the accumulation operation. The control circuit 46 measures the elapsed time from the start of the accumulation operation using a timer. When the elapsed time reaches the time set in the shooting conditions, the FPD 26 is shifted from the accumulation operation to the reading operation. Alternatively, the end of X-ray irradiation may be detected by the irradiation detection sensor 25 without using a timer, and the FPD 26 may be shifted from the accumulation operation to the reading operation.

  The electronic cassette 21 is a minimum such as the communication unit 45 and the charging circuit 93 (see FIG. 5) from the end of imaging of a patient to transmission of image data to the imaging control device 23 until the start of the next imaging (between imaging). It operates in the sleep mode that supplies power only to the necessary parts and stops power supply to other parts to reduce power consumption. When the electronic cassette 21 receives an imaging condition from the imaging control device 12, the electronic cassette 21 supplies power to each unit other than the communication unit 45 and the charging circuit 93 to operate the FPD 26, and can immediately output an X-ray image. Transition from the sleep mode to the preparation mode. When the imaging preparation mode is entered, the FPD 26 repeats the reset operation and waits for detection of the start of X-ray irradiation.

  In FIG. 5, a power feeding device 81 is built in the holders 30a and 30b of the photographing bases 22a and 22b. The power feeding device 81 has a power feeding electrode 82, and an AC power source 83 is connected to the power feeding electrode 82. The power feeding electrode 82 is made of the same material as the power receiving electrode 61 of the electronic cassette 21 and is a flat plate electrode having the same size as the power receiving electrode 61. The power supply electrode 82 is provided at a position where it faces the power receiving electrode 61 in parallel when the electronic cassette 21 is set in the holders 30a and 30b, and the distance from the power receiving electrode 61 is about several millimeters. As described above, the power feeding electrode 82 performs electric field coupling type non-contact power feeding to the power receiving electrode 61.

  The holders 30 a and 30 b are provided with a full charge detection unit 84 and a removal detection unit 85. The full charge detection unit 84 detects whether or not the battery 41 is fully charged, and the removal detection unit 85 detects that the electronic cassette 21 has been removed from the holders 30a and 30b. When the full charge detection unit 84 detects that the battery 41 is fully charged, and when the removal detection unit 85 detects that the electronic cassette 21 has been removed from the holders 30a and 30b for single use, The connection between the power supply electrode 82 and the AC power supply 83 is disconnected, or the drive of the AC power supply 83 is stopped to interrupt the power supply. The power supply device 81 is operating at other times.

  As a method for detecting whether or not the battery 41 is fully charged by the power supply device 81, means for monitoring the discharge voltage of the battery 41 and measuring the amount of charge is provided on the electronic cassette 21 side, and the measurement result is displayed on the electronic cassette. 21 is wired or wirelessly transmitted to the power supply apparatus 81, or the current flowing through the power supply electrode 82 and the AC power supply 83 is measured on the power supply apparatus 81 side, and whether or not the battery 41 is fully charged according to the measurement result is determined. There is a method for determination, and either method may be adopted.

  As a method for detecting that the electronic cassette 21 is used alone, for example, a sensor (reflection) that optically, mechanically, or electrically detects that the electronic cassette 21 has been removed from the holders 30a and 30b. Type optical sensor, ultrasonic sensor, limit switch, electromagnetic wave sensor, etc.), the output of the sensor is transmitted to the power feeding device 81 via the imaging control device 23 or the console 24, or discrete (single) Function) A method of providing a dedicated circuit made of a semiconductor and transmitting directly from the circuit to the power feeding device 81 can be adopted.

  A changeover switch (relay) 91 is connected to the power receiving electrode 61. The changeover switch 91 is connected to the housing ground 92 and the charging circuit 93 of the electronic cassette 21, and selectively switches the connection between these and the power receiving electrode 61. The charging circuit 93 includes an AC / DC converter (rectifier) and a DC regulator. The charging circuit 93 converts AC power from the power feeding electrode 82 received by the power receiving electrode 61 into DC power, and outputs a voltage suitable for charging the battery 41. .

  The changeover operation of the changeover switch 91 is controlled by the control circuit 46. As shown in the figure, the changeover switch 91 shifts to the sleep mode between the above-described shootings in which neither shooting nor image transmission is performed and the shooting preparation mode and the irradiation detection sensor 25 detects the start of X-ray irradiation. The control circuit 46 is brought down to the charging circuit 93 side. The power receiving electrode 61 literally functions as an electrode for non-contact power feeding.

  On the other hand, imaging is performed by detecting the start of X-ray irradiation by the irradiation detection sensor 25, and the changeover switch 91 is tilted toward the housing ground 92 until the image transmission is completed and the sleep mode is entered. In this case, the power receiving electrode 61, together with the front cover 54 made of a conductive resin and the transmission plate 56 made of a carbon material, leaks noise from the inside of the electronic cassette 21 to the outside, and noise from the outside of the electronic cassette 21 to the inside. It functions as an electromagnetic shield that prevents intrusion (mainly electromagnetic noise from the power supply device 81). That is, the power receiving electrode 61 also serves as a non-contact power supply electrode and an electromagnetic shield. When the full charge detection unit 84 detects that the battery 41 is fully charged, and when the removal detection unit 85 detects that the electronic cassette 21 has been removed from the holders 30a and 30b, the changeover switch 91 is also connected to the housing ground. Defeated on the 92nd side.

  Hereinafter, the operation of the above configuration will be described with reference to the flowcharts of FIGS. 6 and 7. When imaging is performed by the X-ray imaging system 10, first, the height and height of the electronic cassette 21 set on the imaging table 22 in either the standing position or the standing position are adjusted, and the imaging region and position of the subject H are adjusted. Adjust. Further, 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. Next, as shown in step 10 (S10) of FIG. 6, the electronic cassette 21 is turned on. The electronic cassette 21 starts up in the sleep mode (S11). Subsequently, shooting conditions are input from the console 24, and the shooting conditions are set in the electronic cassette 21 via the shooting control device 23 (YES in S12). The electronic cassette 21 shifts from the sleep mode to the shooting preparation mode (S13). The imaging conditions are also set in the radiation source control device 14.

  When the electronic cassette 21 is turned on, the changeover switch 91 is tilted toward the charging circuit 93, and the power feeding device 81 performs non-contact power feeding through the electrodes 61 and 82, and the charging circuit 93 charges the battery 41. (S11-S13).

  When preparation for imaging is completed, the radiation switch 15 is pushed one step by the radiologist. As a result, a warm-up start signal is transmitted to the radiation source control device 14 and the warm-up of the X-ray source 13 is started. After a predetermined time has elapsed, the irradiation switch 15 is pushed in two steps, an irradiation start signal is transmitted to the radiation source control device 14, and X-ray irradiation is started.

  The FPD 26 detects whether or not X-ray irradiation has been started by the irradiation detection sensor 25 while performing a reset operation. When the start of X-ray irradiation is detected (YES in S14), the control circuit 46 tilts the changeover switch 91 from the charging circuit 93 side to the housing ground 92 side, and causes the power receiving electrode 61 to function as an electromagnetic shield (S15). .

  When the start of X-ray irradiation is detected, the control circuit 46 turns off all the TFTs 65 and shifts to the accumulation operation. The radiation source control device 14 stops the X-ray irradiation when the irradiation time set in the imaging conditions has elapsed. Further, the FPD 26 also ends the accumulation operation after a lapse of a predetermined time corresponding to the irradiation time set in the imaging conditions, and shifts to a reading operation. In the read operation, the signal charges accumulated in the pixels 52 are read out row by row from the first row, and are recorded in the memory 47 as X-ray image data for one screen. This image data is transmitted to the console 24 via the photographing control device 23 (S16). After the read operation, the FPD 26 restarts the reset operation.

  The image data is subjected to various image processing such as offset correction and gain correction at the console 24, and then displayed on the display of the console 24 or stored in a data storage device. The above series of operations is repeatedly executed until all scheduled shootings are completed (YES in S17).

  In FIG. 7, when the changeover switch 91 is tilted to the charging circuit 93 side and the battery 41 is charged, the full charge detection unit 84 fully charges the battery 41 or the removal detection unit 85 removes the electronic cassette 21 ( (Single use) is detected (YES in S20), charging is performed by moving the changeover switch 91 from the charging circuit 93 side to the housing ground 92 side regardless of whether or not X-ray irradiation is performed and whether image data is transmitted. Is interrupted (S21). The power receiving electrode 61 functions as an electromagnetic shield. On the other hand, when the battery 41 is not fully charged or the use of the electronic cassette 21 alone is not detected (NO in S20), the state where the changeover switch 91 is tilted to the charging circuit 93 side is maintained and the battery 41 is continuously charged. (S22).

  As described above, according to the present invention, the power receiving electrode 61 of the electronic cassette 21 serves as both an electrode for non-contact power feeding and an electromagnetic shield. Therefore, as compared with the case where the electrode for non-contact power feeding and the electromagnetic shield are provided separately. The electronic cassette 21 can be reduced in size (thinned) and reduced in part cost. In particular, the electric field coupling method has a simpler structure and is advantageous for miniaturization than other non-contact power feeding methods such as an electromagnetic induction method and a magnetic resonance method. Can increase the sex.

  Imaging is performed by detecting the start of X-ray irradiation by the irradiation detection sensor 25, and the power receiving electrode 61 functions as an electromagnetic shield until the image transmission is completed and the mode is shifted to the sleep mode, so that noise is superimposed on the image data. It is possible to ensure electromagnetic compatibility (EMC) at the time of shooting or image transmission where there is concern.

  In order to reduce the amount of exposure of the subject, a highly sensitive FPD 26 is used so that even weak electromagnetic waves can be detected. For this reason, there is a high need for ensuring electromagnetic compatibility at the time of shooting and preventing image quality deterioration due to electromagnetic noise, and therefore the usefulness of the present invention is also extremely high.

  In the above embodiment, when the irradiation detection sensor 25 detects the start of X-ray irradiation, the changeover switch 91 is switched from the charging circuit 93 side to the housing ground 92 side, and charging / recharging of the battery 41 without making the engineer aware of it. Switching of non-charging is automatically performed, but an operation switch for instructing charging / non-charging is provided to any of the imaging bases 22a and 22b, the power feeding device 81, the imaging control device 23, and the console 24. The changeover switch 91 may be switched in synchronization with the operation of the operation switch.

  When a relay is used as the changeover switch 91 as in the above embodiment and the changeover switch 91 is switched from the charging circuit 93 side to the housing ground 92 side when the irradiation detection sensor 25 detects the start of X-ray irradiation, the switching is performed. There is a possibility that the switching noise of the switch 91 rides on the image data and causes unevenness in the image.

  In order to dispel this concern, the changeover switch 91 is intentionally switched at the time of non-irradiation of X-rays such as when the electronic cassette 21 is turned on to generate switching noise, and the FPD 26 performs accumulation operation and readout operation. It is preferable that the image data output at this time is stored in the memory of the console 24 as correction data, and the console 24 performs a noise removal process for subtracting the correction data from the image data obtained by X-ray imaging.

  Since the correction data is obtained when X-rays are not irradiated, switching noise of the changeover switch 91 appears in the correction data. If this is subtracted from the image data obtained by X-ray imaging, switching noise can be removed from the image data. Further, if correction data is acquired at regular intervals such as when the electronic cassette 21 is turned on, it is possible to cope with a case where switching noise changes due to aging of the changeover switch 91.

  Instead of switching the changeover switch 91 in response to the detection of the start of X-ray irradiation, for example, from the time when imaging conditions are input through the previous console 24 until the start of X-ray irradiation, for example, the imaging control device 23 It may be switched when shooting conditions are set in the electronic cassette 21 via the. Alternatively, the patient is set on the imaging table (when the patient stands in front of the imaging table 22a in the case of the standing imaging table 22a, or when the patient lies on the imaging table 22b in the case of the standing imaging table 22b) May be detected optically, mechanically, or electrically, and the changeover switch 91 may be switched using this as an opportunity. In these cases, since the changeover switch 91 is switched before the X-ray irradiation is started, there is no possibility that the switching noise is added to the image data. Moreover, it can respond also to the type without the irradiation detection sensor 25.

  In the above embodiment, image data is transmitted immediately after X-ray imaging. However, image data is transmitted after X-ray imaging, or image data is transmitted collectively after several imaging. There is also a case. In this case, when the X-ray imaging is completed, the changeover switch 91 is tilted from the housing ground 92 side to the charging circuit 93 side to charge the battery 41, and when the image data is transmitted, the changeover switch 91 is switched to the housing ground 92 side again. Thus, the power receiving electrode 61 is caused to function as an electromagnetic shield.

  When image data is transmitted using a communication method that is relatively resistant to electromagnetic noise, it is not always necessary to switch the changeover switch 91 to the housing ground 92 side during image data transmission so that the power receiving electrode 61 functions as an electromagnetic shield. .

  In the above embodiment, the material of the holders 30a and 30b is not particularly mentioned, but the holders 30a and 30b are made of a metal material that functions as an electromagnetic shield in order to ensure electromagnetic compatibility under all circumstances. It is preferable.

  When the holders 30a and 30b are electromagnetic shields, when the electronic cassette 21 is set in the holders 30a and 30b, electromagnetic interference from the system including the electronic cassette 21 and the power feeding device 81 to the outside, and power feeding to the electronic cassette 21 from the outside are performed. The holders 30a and 30b can prevent the influence of electromagnetic interference on the system including the device 81. When the electronic cassette 21 is removed from the holders 30a and 30b and used alone, the changeover switch 91 is tilted toward the housing ground 92 as described above, and the power receiving electrode 61 functions as an electromagnetic shield. , It is possible to ensure electromagnetic compatibility under both the situation where it is used by being set to 30b and when it is used alone.

  In the above embodiment, the power receiving electrode 61 and the back cover 55 are separated from each other, but the power receiving electrode 102 may be used as the back cover as in the electronic cassette 101 shown in FIG. Further downsizing (thinning) and part cost reduction are possible. Moreover, since the surface area of the power receiving electrode 61 can be maximized, the power feeding efficiency can be improved. However, in this case, since the back cover is made of metal, for example, a rubber insulating member 105 having a U-shaped cross section is fitted into a connection portion with the front cover 103 or a connection portion with the base plate 104 to insulate from other components. Ensure sex. By making the insulating member 105 have a U-shaped cross section, the electromagnetic shielding ability in the vicinity of the insulating member 105 when the power receiving electrode 102 functions as an electromagnetic shield can be further enhanced.

  Note that how much noise is on the image data is obtained by image analysis, and the relationship between the integrated power supply by the power supply device 81 and the remaining amount of the battery 41 is monitored, and when the noise is larger than a set value, or When the increase in the remaining amount of the battery 41 is small compared to the integrated power supply power, it may be determined that the changeover switch 91 has failed. If it is determined that there is a failure, a message to that effect is displayed on the console 24 display.

  If the changeover switch 91 is broken and remains on the charging circuit 93 side, noise from the power feeding device 81 is added to the image data, and if it is left on the housing ground 92 side, non-contact power feeding is performed. Since it is not performed, if the method of riding noise and the remaining amount of the battery 41 are monitored, it is possible to determine the failure of the changeover switch 91.

  Further, the operation history of the changeover switch 91 may be stored in association with the detection start of X-ray irradiation and the time of image transmission. It can be confirmed from the operation history that the change-over switch 91 has been reliably tilted to the housing ground 92 side during X-ray imaging and image transmission. If there is noise on the image data even though the changeover switch 91 is tilted to the housing ground 92 side, the influence of noise from other than the power supply device 81 can be considered, and the cause of image quality degradation can also be investigated. Can be useful.

  It should be noted that the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

  The X-ray imaging system 10 is not limited to the type installed in the imaging room of the hospital, but the type installed in the round-trip car, the X-ray source 13, the source control device 14, the electronic cassette 21, the imaging control device 23, etc. The present invention may be applied to a portable system capable of carrying out X-ray imaging by carrying it to a site requiring emergency medical treatment such as a disaster or the home of a patient receiving home medical care.

  In the above embodiment, the system that does not have the function of communicating between the X-ray generation apparatus and the X-ray imaging apparatus has been illustrated, but the present invention can also be applied to those having a communication function between the apparatuses. In this case, a sensor for detecting the start of irradiation is unnecessary, and a synchronization signal is sent between the radiation source control device and the imaging control device to notify the start of X-ray irradiation. The power receiving electrode may be made into an electromagnetic shield.

  A dedicated cradle for charging the built-in battery with the electronic cassette itself set may be prepared, and the power supply device may be provided in the cradle. In this case, the setting of the electronic cassette to the cradle and the removal of the electronic cassette from the cradle are detected by a sensor, etc. When the setting to the cradle is detected, the changeover switch is moved to the charging circuit side, Controls the changeover switch to the housing ground side.

  In the above-described embodiment, the electronic cassette and the imaging control device are described separately. However, even if the electronic cassette and the imaging control device are integrated, for example, the function of the imaging control device is built in the control circuit of the electronic cassette. Good. In addition, although image processing is performed by the console, it may be performed by a photographing control device. Further, the console may be integrated with the function of the imaging control device.

  The present invention can be applied not only to X-rays but also to imaging systems that use other radiation such as gamma rays.

DESCRIPTION OF SYMBOLS 10 X-ray imaging system 11 X-ray generator 12 X-ray imaging device 21, 101 Electronic cassette 22a, 22b Standing position, standing position imaging stand 23 Imaging control apparatus 24 Console 26 FPD
27 Housing 30a, 30b Holder 31 Antenna 41 Battery 45 Communication unit 46 Control circuit 52 Pixel 61, 102 Power receiving electrode 63 Signal processing circuit 81 Power feeding device 82 Power feeding electrode 84 Fully charged detection unit 85 Removal detection unit 91 Changeover switch 92 Housing ground 93 Charging circuit 105 Insulating member

Claims (14)

A radiation image detector for detecting a radiation image by receiving radiation irradiated from a radiation source;
A housing for housing the radiation image detector;
A battery for supplying power to each part;
A battery charging circuit;
A power receiving electrode for receiving electric power for charging the battery from a non-contact power supply device, disposed on the bottom surface of the casing opposite to the imaging surface of the radiation image detector in parallel with the imaging surface, A power receiving electrode for receiving power from the power feeding electrode of the contact power feeding device;
A selector switch for selectively switching the connection between the power receiving electrode and the charging circuit, or the power receiving electrode and the housing ground;
Control means for controlling the switching operation of the changeover switch, wherein radiographic image data is transmitted from the radiographic image detector to an external device while a radiographic image is detected by the radiographic image detector. A control means for connecting the power receiving electrode and the housing ground to cause the power receiving electrode to function as an electromagnetic shield, and for other cases, connecting the power receiving electrode and the charging circuit to enable power reception; and An electronic cassette characterized by comprising:   The electronic cassette according to claim 1, wherein the control unit connects the power receiving electrode and the housing ground when radiation irradiation is started. It said control means from detecting images in the radiation image detector switches the said changeover switch during non-irradiation of the radiation,
3. The electronic cassette according to claim 2, wherein the image data obtained thereby is subtracted from the radiographic image data as correction data in which switching noise of the changeover switch appears.   The electronic cassette according to claim 3, wherein the correction data is acquired at regular intervals.   2. The electronic cassette according to claim 1, wherein the control unit connects the power receiving electrode and the housing ground during a period from when an imaging condition is input to an external device to when radiation irradiation is started. .   The electronic cassette according to claim 5, wherein the control unit connects the power receiving electrode and the housing ground when receiving imaging conditions from an external device.   The electronic cassette according to claim 5, wherein the control unit connects the power receiving electrode and the housing ground when the subject is set on an imaging table.   8. The control device according to claim 1, wherein the power receiving electrode and the housing ground are connected when the battery is fully charged or when the electronic cassette is removed from the holder of the photographing stand. The electronic cassette according to any one of the above.   The electronic cassette according to any one of claims 1 to 8, wherein the control means switches the changeover switch in accordance with an operation of an operation member for instructing charging / non-charging of the battery. .   The said housing | casing consists of the back cover which covers the opposite side and the front cover which covers the imaging surface side of the said radiographic image detector, The said back cover is the said receiving electrode, The said receiving power is characterized by the above-mentioned. The electronic cassette according to any one of the above.   11. The electronic cassette according to claim 10, wherein an insulating member having a U-shaped cross section is fitted to a connection portion between the back cover and another component. A radiation image detector for detecting a radiation image by receiving radiation irradiated from a radiation source;
A housing for housing the radiation image detector;
A battery for supplying power to each part;
A battery charging circuit;
A power receiving electrode for receiving electric power for charging the battery from a non-contact power supply device, disposed on the bottom surface of the casing opposite to the imaging surface of the radiation image detector in parallel with the imaging surface, A power receiving electrode for receiving power from the power feeding electrode of the contact power feeding device;
A selector switch for selectively switching the connection between the power receiving electrode and the charging circuit, or the power receiving electrode and the housing ground;
Control means for controlling the switching operation of the changeover switch, wherein radiographic image data is transmitted from the radiographic image detector to an external device while a radiographic image is detected by the radiographic image detector. A control means for connecting the power receiving electrode and the housing ground to cause the power receiving electrode to function as an electromagnetic shield, and for other cases, connecting the power receiving electrode and the charging circuit to enable power reception; and An electronic cassette having
An imaging stand having a holder in which the electronic cassette is detachably accommodated;
A radiation imaging apparatus comprising: an imaging control apparatus that comprehensively controls the operation of the electronic cassette.   The radiation imaging apparatus according to claim 12, wherein the non-contact power feeding apparatus is built in a holder of the imaging table.   The radiation imaging apparatus according to claim 12 or 13, wherein the holder of the imaging stand is electromagnetically shielded.

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