JP5403036B2 - Radiation imaging system - Google Patents

Description

  The present invention relates to a radiation imaging system that irradiates a subject with radiation and detects radiation that has passed through the subject, and particularly relates to a radiation imaging system that uses wireless communication means.

  In recent years, a digital radiation imaging apparatus has been used as a method for irradiating a subject with radiation and detecting radiation transmitted through the subject to obtain a radiation image. As such a radiation imaging apparatus, there is a so-called FPD (Flat Panel Detector).

  An FPD is a two-dimensional array of a plurality of detection elements on a substrate. Visible light is emitted in accordance with the amount of radiation applied to the phosphor (scintillator) irradiated with radiation that has passed through the subject. Is converted into electric charge by a detection element, accumulated in a capacitor, and a radiation image is obtained by reading out the electric charge accumulated in the capacitor.

  In such an FPD, there is a phenomenon that a very small amount of charge is accumulated in a capacitor even when radiation is not irradiated. Although the so-called dark current is called, the electric charge accumulated in the capacitor due to this dark current phenomenon becomes noise in obtaining a radiographic image and adversely affects the image. In order to reduce the influence of this dark current as much as possible, it is important to synchronize radiation irradiation and FPD at the time of imaging.

  Synchronizing radiation and FPD (hereinafter referred to as X-ray cooperation) means that the charge of the FPD capacitor is reset before the radiation irradiation from the radiation generator, and the radiation irradiation starts. In accordance with the timing, the capacitor is changed to a charge accumulation state, and the charge accumulated in the capacitor is read out at the end of radiation irradiation (see Patent Document 1).

  In recent years, a portable cassette type FPD has been used as the FPD. The cassette type FPD is useful in terms of portability and instant confirmation of radiographic image data taken. A radiation system including a wireless communication unit that wirelessly communicates with a type FPD has been proposed (see Patent Document 2). In Patent Document 2, a wireless communication method is used for command communication, shooting timing control, or preview image transfer that is not required to be so fast, and transfer of a detailed image for diagnosis that requires large capacity and high speed. In this method, a wired communication system using a cable such as an optical fiber is used.

JP-A-9-131337 JP 2002-240895 A

  However, in the wireless communication, depending on the position of the patient and the position of the wireless communication means built in the cassette, the communication is temporarily interrupted and the communication between the radiation generator and the cassette type FPD fails, and the above-mentioned X-ray Cooperation may not be performed normally. In particular, when radiation irradiation and FPD cannot be synchronized normally at the start of radiation irradiation, FPD capacitor charge reset and charge accumulation cannot be performed in a timely manner, and a good radiographic image can be obtained even after radiation irradiation. In other words, when re-imaging is performed, useless X-ray radiation is emitted to the subject.

  In view of the above problems, the present invention is a radiation system including a wireless communication unit. Even when wireless communication fails, radiation imaging that reliably performs X-ray cooperation and does not perform useless X-ray radiation on a subject. The purpose is to obtain a system.

  The above object is achieved by the invention described below.

(1) Radiation in which a radiation generating apparatus having radiation irradiating means for irradiating radiation toward a subject and a detection element for converting and storing the radiation irradiated from the radiation irradiating means into a charge signal are arranged two-dimensionally. A portable type comprising: an image detection unit; an imaging control unit that controls an operation state of the radiation image detection unit; an irradiation detection unit that detects radiation irradiation; and a wireless communication unit that communicates with the outside. A radiation imaging system comprising: a radiation imaging apparatus, wherein the imaging control means of the portable radiation imaging apparatus is added when an irradiation start control signal is received from the radiation generation apparatus by the wireless communication means. Te, Kinimo the and the radio by the communication unit does not receive a control signal for starting the irradiation from the radiation generating device, and detects the start of radiation irradiation by the radiation detecting means Ray radiation imaging system wherein the shifting from the charge sweeping state detection elements of the image detector to the charge storage state.

  (2) The irradiation detection unit is a detection element that is a part of the radiation image detection unit that continuously reads out charges at a cycle shorter than an irradiation time during which the radiation irradiation unit irradiates the subject. The radiation imaging system according to (1), which is characterized.

  (3) When the imaging control unit receives a control signal for starting radiation irradiation from the radiation generation device by the wireless communication unit, the imaging control unit shifts the detection element, which is the irradiation detection unit, to a charge storage state and stores the detection element. The radiation imaging system according to (2), wherein the generated charge is read out.

  (4) The imaging control means includes warning notification means for giving a warning when the detection element is shifted from the charge sweep-out state to the charge accumulation state by detection of radiation irradiation by the irradiation detection means. The radiation imaging system according to any one of (1) to (3).

(5) The radiation imaging system according to any one of (1) to (4), wherein the irradiation detection unit is disposed in the radiation image detection unit.

(6) The radiation imaging system according to (5), wherein the irradiation detection unit is a part of the detection elements arranged in the radiation image detection unit.

(7) A signal output from the detection element functioning as the irradiation detection unit is processed by using a signal selection circuit that processes a signal output from the detection element for obtaining a radiation image. The radiation imaging system according to (6).

  According to the present invention, when the irradiation start control signal from the radiation generator is not received by the wireless communication means and the irradiation start is detected by the irradiation detection means, the detection element of the radiation image detecting unit sweeps out the charge. Since the state is shifted to the charge accumulation state, even when the radio communication between the radiation generation apparatus and the cassette type FPD fails, X-ray cooperation is ensured and radiation imaging that does not cause unnecessary X-ray emission to the subject is performed. A system can be obtained.

1 is a schematic diagram of a radiation imaging system according to an embodiment. 1 is an external view of an imaging device F. FIG. 3 is a schematic diagram illustrating a circuit configuration of an imaging panel 22. FIG. It is a figure which shows the control flow of the radiation imaging system which concerns on embodiment. It is a timing chart of the radiation imaging system concerning an embodiment. It is a sequence chart which shows the control process of a X-ray cooperation. It is a sequence chart which shows the control processing of the X-ray cooperation which concerns on other embodiment. It is a figure which shows the control flow at the time of communication error generation | occurrence | production.

  Although the present invention will be described based on an embodiment, the present invention is not limited to the embodiment.

  FIG. 1 is a schematic diagram of a radiation imaging system according to the embodiment. The radiation imaging system includes a radiation generator R, an imaging device F, and a console unit 1. As shown in FIG. 1, in the radiation imaging system, various settings are performed by operating the console unit 1, and radiation is emitted from the radiation generator R based on the set conditions. The radiation transmitted through the subject 2 is detected by the imaging device F, and the radiation information is converted into a digital image signal.

  The console 1, the radiation generation device R, and the imaging device F each have a communication unit 151 and a wireless communication unit 45, and perform communication via the communication network N. As the communication method, for example, an Ethernet LAN is used.

[Console section]
The console unit 1 includes a control unit 12, an image processing unit 13, a memory 14, a display input unit 16, and a communication unit 151. The display input unit 16 includes a display screen such as an LCD for displaying various types of information, and an input unit such as a keyboard or a touch panel disposed on the LCD, and inputs imaging conditions and subject information, or these and radiation. Displays images. These display input units 16 also function as warning notification means. The image processing unit 13 can perform image processing such as density gain adjustment and spatial frequency conversion on the image signal (image data) acquired by the imaging device F.

  The control unit 12 includes a CPU, a system memory, and the like, and performs various controls by the CPU executing various programs stored in the system memory.

[Radiation generator]
The radiation generator R includes a radiation irradiation unit 11, a control unit 12, and a communication unit 151. The radiation irradiation means 11 has an anode made of heavy metal, generates an electron beam by applying a high voltage, for example, 20 kv to 150 kv, to the filament, and generates radiation by applying the electron beam to the anode (target). As the anode, a fixed anode or a rotating anode excellent in durability is used. As the radiation used in the embodiment, for example, X-rays having a wavelength of about 1 × 10 −10 m are used.

[Imaging device]
The imaging apparatus F includes a wireless communication unit 45 and performs wireless communication via a wireless access point 15 installed inside the radiation room. As a wireless communication method, a wireless LAN method compliant with the IEEE 802.11 standard is used. However, the wireless communication method is not limited to this, and other radio wave methods such as UWB (Ultra Wide Band) and Bluetooth, or optical methods such as infrared communication may be used. .

  FIG. 2 is an external view of the imaging apparatus F. Portions common to FIG. 1 are denoted by the same reference numerals. The imaging device F is a portable imaging device and is called a so-called FPD (Flat Panel Detector). As shown in FIG. 2, the imaging apparatus F includes a scintillator 21, an imaging panel 22, a signal selection circuit 27, an imaging control unit 30, a scanning drive circuit 301, a power supply unit 42, a connector 43, and a memory unit 44. These are housed in a housing 41.

  The scintillator 21 emits visible light according to the amount of radiation emitted from the radiation irradiating means 11. The emitted visible light is converted into a digital image signal corresponding to the amount of light by the imaging panel 22, and the digital image signal is read out and temporarily stored in the memory unit 44. The imaging control means 30 having a CPU and a system memory controls the entire imaging apparatus F when the CPU executes a program stored in the system memory. A power supply unit 42 including a battery supplies power to the entire imaging apparatus F. The connector 43 performs data communication (wired communication) with the radiation generation apparatus R, charging of the power supply unit 42, and the like by physically connecting to the imaging apparatus F after the completion of imaging.

  The imaging panel 22 is connected to a scanning drive circuit 301 that reads out electrical energy accumulated according to the intensity of irradiated radiation, and a signal selection circuit 27 that outputs the accumulated electrical energy as an image signal. Note that the inside of the housing 40, the scanning drive circuit 301, the signal selection circuit 27, the imaging control unit 30, the memory 44, the wireless communication unit 45, and the like are covered with a radiation shielding member (not shown). Prevents radiation scattering and radiation to each circuit.

  FIG. 3 is a schematic diagram illustrating a circuit configuration of the imaging panel 22. As shown in the figure, the imaging panel 22 has a plurality of light receiving elements (hereinafter referred to as detection elements) 220 that convert light into an electrical signal in a two-dimensional arrangement, and one detection element 220 corresponds to one pixel of a radiographic image. These pixels are arranged at a density of, for example, 200 to 400 dpi (dots per inch) over the size of the imaging region of the subject.

  Further, scanning lines (horizontal lines) 223 and signal lines (vertical lines) 224 are arranged between the light receiving elements 220, and in the same figure, they are arranged in a grid pattern so that they are orthogonal to each other. Here, assuming that one section surrounded by the scanning line 223 and the signal line 224 is one pixel, the number of pixels of the imaging panel 22 is, for example, m in one direction and n in the other direction. In this case, it is composed of m × n pixels. The imaging panel 22 includes capacitors 221- (1,1) to 221- (m, n) corresponding to the number of m × n pixels and transistors 222- (1,1) to 222 as switching elements. -(M, n) is arranged, and between the pixels, the scanning lines 223-1 to 223-m and the signal lines 224-1 to 224-n are arranged so as to be orthogonal to each other.

  For example, in the first light receiving element, a transistor 222- (1,1) which is a switching element formed of a silicon laminated structure or an organic semiconductor is connected to the capacitor 221- (1,1). For example, a field effect transistor is used as the transistor 222- (1, 1). The drain electrode or the source electrode of the transistor 222- (1,1) is connected to the detection element 220- (1,1), and the gate electrode is connected to the scanning line 223-1. When the drain electrode is connected to the detection element 220- (1,1), the source electrode is connected to the signal line 224-1, and when the source electrode is connected to the detection element 220- (1,1), the drain electrode is a signal. Connect to line 224-1. Similarly, the detection element 220, the capacitor 221, and the transistor 222 in other pixels are connected to the scanning line 223 and the signal line 224.

  In some cases, the imaging panel 22 includes initialization transistors 232-1 to 232-n in which drain electrodes are connected to signal lines 224-1 to 224-n as shown in FIG. In 232-1 to 232-n, the source electrode is grounded, and the gate electrode is connected to the reset line 231.

  The imaging panel 22 converts the radiation image into a digital image signal through these circuits. That is, the imaging control circuit 30 in FIG. 3 supplies the readout signal RS to the scanning lines 223-1 to 223 -m via the scanning driving circuit 25 to perform image scanning, and outputs a digital image signal for each scanning line. Capture and convert the radiation image into a digital image signal. This will be described in detail below.

  The scanning lines 223-1 to 223-m and the reset line 231 of the imaging panel 22 are connected to the scanning drive circuit 301 as shown in FIG. 3. When the readout signal RS is supplied from the scanning drive circuit 301 to any scanning line 223-p (p is any value of 1 to m) among the scanning lines 223-1-223-m, the scanning line 223 is scanned. The transistors 222- (p, 1) to 222- (p, n) connected to −p are turned on, and the charges accumulated in the capacitors 221- (p, 1) to 221- (p, n) are signaled. Output on lines 224-1 to 224-n.

  The signal lines 224-1 to 224-n are connected to the signal converters 271-1 to 271-n of the signal selection circuit 27. In the signal converters 271-1 to 271-n, the signal lines 224-1 to 224-n are connected. Voltage signals SV-1 to SV-n corresponding to the amount of charge output above are output, and voltage signals SV-1 to SV-n output from the signal converters 271-1 to 271-n are supplied to the register 272. To do.

  The register 272 sequentially selects the voltage signal supplied from the signal converter 271, and the selected voltage signal is converted into one digital image signal of 12 bits or 14 bits by the analog / digital (A / D) converter 273. The digital image signal is supplied to the control circuit 30 to convert the radiation image into a digital image signal in units of pixels.

  When the imaging panel 22 is initialized, first, after the reset signal RT is supplied from the scanning drive circuit 301 to the reset line 231 to turn on the initialization transistors 232-1 to 232-n, The readout signal RS is supplied to the scanning lines 223-1 to 223 -m to turn on the transistors 222-(1, 1) to 222-(m, n). Then, the imaging panel 22 is initialized by discharging the charges stored in the capacitors 221- (1,1) to 221- (m, n) through the initialization transistors 232-1 to 232-n. .

  Here, each of the “charge sweep-out state”, “charge read-out state”, and “charge accumulation state” will be described. “Charge sweep-out state” is a state in which the above-described initialization is continuously performed at a predetermined interval. “Charge read-out state” sequentially outputs charges accumulated in the capacitors 221 to the signal lines. In this state, the digital image signal is converted via the register 272. The “charge accumulation state” is a state in which each capacitor 221 converts the charges converted with radiation without being initialized or read out. This means a state where the image is continuously accumulated, that is, a so-called exposure state. The change control of these states is executed by the imaging control means 30 (including the scanning drive circuit 301).

  In addition, in the said embodiment, although the indirect type FPD which detects a radiation indirectly using a scintillator was demonstrated, it is not restricted to this, The direct type | mold FPD in which a photoelectric conversion element directly converts a radiation into an electric signal May be used.

[Irradiation detection means]
In the present embodiment, some of the plurality of detection elements 220 of the imaging panel 22 (radiation image detection unit) are used as “irradiation detection means”. Specifically, the reading signal RS is sent to the scanning line 223-p at a cycle shorter than the irradiation time of the radiation irradiating means with a set of detection elements 220 of one arbitrary row (for example, p row) along the scanning line 223. By supplying and controlling to continuously read out the electric charge, it is used as an irradiation detecting means. The irradiation time of the radiation is, for example, several tens of milliseconds to several hundreds of milliseconds, and the readout cycle when used as the irradiation detection means is set to a cycle shorter than that by one digit or more, for example, a cycle of 0.1 to several milliseconds Yes.

  The irradiation detection means is arranged over the entire range at intervals of about one line for every tens to hundreds of lines, for example, between 223-1 to 223 -m with respect to all the scanning lines 223 of the imaging panel 22. . In the example shown in FIG. 2, the group B detection element 220b corresponds to the irradiation detection means. Of all the pixels (detection elements 220) of the imaging panel 22, some of them function as irradiation detection means of the group B detection elements, and the rest function as the group A detection elements 220a as pixels for obtaining an original radiation image. ing. In FIG. 2, the B group detection element and the A group detection element are color-coded for the sake of explanation, but in actuality, both the detection elements have the same configuration and can be appropriately changed from each other.

  Further, when the group B detection element 220b is functioning as an irradiation detection means, an image signal similar to that of the group A detection element 220a cannot be obtained, resulting in an image defect. In order to reduce this influence, the ratio of the B group detection element 220b to the total number of pixels (m × n) is set to about 0.1% to 1%.

  In this embodiment, the example in which the pixel detection unit 22 functions as the irradiation detection unit as a set of pixels along the scanning line 223 among the pixels of the imaging panel 22 has been described. A dedicated transistor may be provided, and these may be arranged along a line of signal lines to be used as irradiation detection means. Furthermore, a dedicated irradiation detection unit may be arranged in the vicinity of the imaging panel 22 without using a part of the imaging panel 22 as the irradiation detection unit.

  Next, control related to X-ray cooperation will be described with reference to FIGS. FIG. 4 is a diagram illustrating a control flow of the radiation imaging system according to the embodiment. The control flow between the console 1 which the operator operates, the radiation generator R, and the imaging device F is shown.

[X-ray cooperation]
First, in step S <b> 1, the operator issues a shooting instruction by operating the console 1. In subsequent step S2, the radiation generation apparatus R receives an imaging instruction, and based on the instruction, prepares for radiation irradiation (step S3) and transmits a preparation instruction signal (sig1) to the imaging apparatus F by wireless communication. The preparation of radiation irradiation performed here is preparation for rotation of the rotating anode (target) of the radiation irradiation means 11 or the like. In the imaging apparatus F, the imaging panel 22 is set to the charge sweeping state (initialization) as imaging preparation based on the preparation instruction signal (step S4). When preparation is completed (step S5) and the operator instructs radiation irradiation, an irradiation start signal (sig2a) is transmitted to the imaging apparatus F by wireless communication before irradiation (step S6).

  In step S <b> 7, the imaging control unit 30 determines whether or not the irradiation start signal sig <b> 2 a is received by the wireless communication unit 45. When the irradiation start signal sig2a is received (Yes in step S7), the imaging device F sets the imaging panel 22 to the charge accumulation state based on the irradiation start signal (step S10).

  In step S8, radiation irradiation is started by the radiation irradiation means 11. Along with the irradiation of radiation, the group B detection element 220b (hereinafter also referred to as irradiation detection means) detects the irradiation (sig2b).

  At this time, if the irradiation start signal is not received in step S7 (No in S7), the imaging control means 30 determines whether or not irradiation is detected by the group B detection element 220b (step S9). ). If irradiation is detected (Yes in S9), the process of step S10 is executed. If not detected (No in S9), the process of step S7 is executed.

  That is, the process of step S9 accompanying the irradiation detection sig2b in the broken line portion in FIG. 6 is an unnecessary process when the irradiation start signal sig2a is normally communicated in step S7, and is performed as a backup process. . This will be described later with reference to FIGS.

  Upon completion of radiation irradiation by the radiation irradiation means 11 (step S11), an irradiation end signal sig3a is transmitted to the imaging apparatus F by wireless communication. In the imaging apparatus F, the imaging panel 22 is changed from the charge accumulation state to the charge readout state based on the irradiation end signal sig3a, the read charge is converted into a digital signal by the A / D converter 273, and the converted radiation image is converted. Data is temporarily stored in the memory 44 (step S12). The above is the flow related to the X-ray cooperation between the radiation generation apparatus R and the imaging apparatus F related to imaging.

[Post-processing after imaging]
In step S <b> 21, the imaging apparatus F transmits the radiation image data stored in the memory 44 to the console 1 via the wireless access point 15 by the wireless communication unit 45. The received radiographic image data is stored in the memory 14 together with imaging conditions at the time of imaging, subject information, and the like. The image processing unit 13 performs necessary image processing such as density gain adjustment and spatial frequency conversion on the stored radiation image data (step S22). By displaying on the console 1 (step S23), the imaging flow is completed.

  FIG. 5 is a timing chart of the radiation imaging system according to the embodiment. The control flow shown in the figure is performed when S9 in FIG. 4 is executed. Further, unlike FIG. 4, the end of irradiation is also performed by the detection value of the irradiation detection means 220b (sig3b). This will be described below.

  The irradiation detection means 220b has shifted to a measurement state, that is, a state in which charges are continuously read out with a short period tc in accordance with the preparation instruction signal sig1 at time t0. At this time, since no radiation is irradiated, the output value from the irradiation detection means 220b is a minute measurement value (L1) associated with the dark current.

  When the radiation irradiation means 11 is irradiated (time t1), the detection value (L2) of the irradiation detection means 220b increases accordingly, and the detection value at time t2 exceeds the SH (threshold) level. The control unit 30 determines that radiation is being applied, and sets the detection element 220a to the charge accumulation state. As shown in the figure, the accumulated charge amount of the detection element increases with the radiation dose.

  When radiation irradiation ends at the timing of time t3, the detection value of the irradiation detection means 220b decreases (L1), and the detection value at time t4 falls below the SH level. Is stopped, and the detection element 220a is set to the charge reading state. Thereafter, the flow after step S21 in FIG.

  In the description of FIG. 5, an example in which the presence / absence of irradiation is determined based on the output of one irradiation detection unit 220b has been described. However, actually, the irradiation detection unit 220b has a function of a plurality of detection elements. Judgment is made by monitoring a plurality of detection elements.

  FIG. 6 is a sequence chart showing an X-ray cooperation control process. The left side of FIG. 6 shows a sequence between the console 1, the radiation generator R, and the imaging device F, and the right side of FIG. 6 shows the A group detection element 220a and the B group detection element 220b (irradiation detection means). This shows the state. As described above, the A group and the B group are obtained by dividing a large number of detection elements (detection elements 220) into two groups, A group and B group, and using the B group detection element 220b as irradiation detection means. is there.

  In the sequence chart of FIG. 6, the processes common to those in FIG. In this figure, the sequence when the sig2a irradiation start signal (preliminary notice) by wireless communication is not normally performed due to some trouble and a communication error occurs is described.

  First, the radiation generating apparatus R that has received an imaging instruction (S1) from the operator transmits an imaging preparation signal sig1 through wireless communication. Based on the signal, the group A detection element 220a is set in a charge sweeping state (state A1). Preparation OK (sig15) is transmitted from the imaging apparatus F to the radiation generation apparatus R. In response to the signal, irradiation of radiation is started from the radiation generator R.

  Next, the irradiation start signal sig2a is transmitted from the radiation generator R. Even if the imaging apparatus F cannot receive the signal due to a communication error, the radiation generator R follows a predetermined procedure, Radiation irradiation is started from the radiation irradiation means 11 (sig2b). In order for the B group detection element 220b to be in a measurement state in advance, the readout signal RS is supplied to the scanning lines 223-p (p is plural) corresponding to the B group detection element in a short cycle to continuously read out the charges. By controlling so as to perform, it is functioning as an irradiation detection means, so that the start of irradiation from the radiation irradiation means 11 can be detected. Based on this detection, the imaging control means 30 changes the group A detection element 220a from the charge sweeping state to the charge accumulation state (A2) (S10).

  The change from the accumulation state to the charge readout state (A3) is performed in the same manner as in FIG. 4 by determining the end of irradiation based on the detection value (sig3b) of the irradiation detection means 220b and setting the readout state (step S12). Thereafter, the flow of step S21 in FIG.

  As described above, in the radiation system including the wireless communication unit, even when the wireless communication fails, when the radiation detection start is detected by the irradiation detection unit, the detection element of the radiation image detection unit is charged from the charge sweeping state. By shifting to the accumulation state, it is possible to obtain a radiation imaging system that reliably performs X-ray cooperation and does not perform useless X-ray emission on the subject.

  FIG. 7 is a sequence chart showing an X-ray cooperation control process according to another embodiment. 4 to 6, the embodiment in which a part of the detection element of the imaging panel 22 is functioned as an irradiation detection unit has been described. However, in such a case, an original image signal cannot be obtained in that portion, and that portion becomes an image defect. As a countermeasure against such a problem, in the embodiment shown in FIG. 7, when normal communication can be performed by wireless communication, the group B detection element 220 b functioning as the irradiation detection unit is released to perform the original detection. By functioning as an element (pixel), the occurrence of image defects is avoided. In the sequence shown in the figure, the A group detection element 220a used as a normal detection element is the same as that shown in FIGS. In addition, the processes common to those in FIG. This will be described below.

  When the irradiation start signal sig2a is normally communicated by wireless communication, based on the signal, the group B detection element 220b functioning as the irradiation detection means is changed from the measurement state (B1) to the sweeping state (B2). Then, it is changed to the accumulation state (B3) (S10-2). Since the time from the irradiation start signal sig2a to the radiation irradiation start sig2b is set to about several hundred msec, for example, the group B detection element 220b is changed to the sweeping state (B2) and then the accumulation state (B3) is changed. The control to be changed is performed during that time.

  Based on the irradiation end signal sig3a, the B group detection element 220b and the A group detection element 220a are changed from the charge accumulation state to the charge read state, and the read charge is converted into a digital signal by the A / D converter 273. The radiographic image data thus stored is temporarily stored in the memory 44 (S12-2). Thereafter, the flow of step S21 in FIG.

  As described above, when the radio communication means receives the radiation irradiation start control signal from the radiation generating device, a part of the group B detection elements of the imaging panel 22 (radiation image detection unit) used as the irradiation detection means 220b is a radiation imaging system that is controlled so as to shift to a charge accumulation state and function as a normal pixel, so that X-ray cooperation is ensured even when wireless communication fails, and at the time of normal communication Thus, it is possible to obtain a radiation imaging system that does not cause image defects.

[Action when the irradiation start signal (notice) cannot be notified due to a communication error]
Regarding the response when the irradiation start signal (notice) becomes a communication error and the detection element is shifted from the charge sweeping state to the charge accumulation state by the detection of radiation irradiation by the irradiation detecting means, that is, when the situation of FIG. explain.

  Originally, X-ray cooperation should not be performed by detection of the irradiation detection means, but X-ray cooperation should be performed based on an irradiation start signal (notice) sig2a transmitted before the start of irradiation. The control shown in FIG. 6 is to operate the system by reducing the original function when a radio communication error occurs, and can also be referred to as so-called fail software.

  That is, when the sequence shown in FIG. 6 is performed, there is a delay of time t2 from the start of radiation irradiation until the group A detection element 220a enters the charge accumulation state. In other words, what should secure an accumulation time (exposure time) corresponding to the radiation irradiation time t1 can only be exposed (charge accumulation) for an exposure time shorter by the time t2. In this case, the so-called underexposure occurs and the electrical signal that should be secured cannot be obtained. The following will deal with these problems.

  FIG. 8 is a diagram illustrating a control flow when a communication error occurs.

  As shown in FIG. 6, when the irradiation start signal sig2a cannot be notified due to a communication error and the irradiation state is changed to the accumulation state A2 because the irradiation detection unit sig2b is detected by the irradiation detection unit (Yes in step S31), In step S32, abnormality notification is performed. This is notified from the imaging device F to the console 1, and based on the notification, a warning is displayed on the display screen of the display input unit 16 of the console 1 functioning as a warning notification means. This is to prevent the occurrence of a similar communication error repeatedly when imaging is performed by prompting the operator that a communication error has occurred due to some kind of failure.

  Subsequent to step S32, second image processing is performed in step S33. In this case, after the radiation image data is transmitted to the console 1, the image processing unit 13 of the console 1 performs image processing. As the second image processing, for example, density correction is performed by multiplying a coefficient (t1 / t3) corresponding to the amount by which the exposure time is shortened. As shown in FIG. 6, the charge accumulation time (hereinafter referred to as exposure time) that can be secured in the normal time is the same time t1 as the irradiation time t1. However, the exposure time t3 when a communication error occurs is shorter by the time t2 than the normal exposure time t1 (t3 = t1-t2). In step S33, the influence of the insufficient exposure time is compensated.

  On the other hand, when normal X-ray cooperation is performed without occurrence of communication abnormality (No in step S31), the underexposure problem does not occur, and therefore the first normal image processing may be performed (S34). ).

  Thus, when the detection element is shifted to the charge accumulation state by receiving the radiation irradiation start control signal, the detection element is changed from the charge sweeping state to the charge accumulation state by the detection of radiation irradiation by the irradiation detection means. By performing different image processing on the image signal (radiation image data) read out in the case of transfer, it is possible to obtain a radiation imaging system capable of obtaining an appropriate radiation image.

DESCRIPTION OF SYMBOLS 1 Console part R Radiation generator F Imaging device 11 Radiation irradiation means 13 Image processing part 22 Imaging panel (radiation image detection part)
220 Detection element (light receiving element)
220a Group A detection element (pixel)
220b Group B detection element (irradiation detection means)
221 Capacitor 222 Transistor 223 Scanning line 224 Signal line 27 Signal selection circuit 30 Imaging control means 301 Scanning drive circuit 151 Communication means 15 Wireless access point 45 Wireless communication means

Claims (7)

A radiation generator having radiation irradiation means for irradiating the subject with radiation;
A radiation image detection unit that two-dimensionally arranges detection elements that convert the radiation emitted from the radiation irradiating means into charge signals and store them;
Imaging control means for controlling the operating state of the radiation image detection unit;
An irradiation detection means for detecting radiation irradiation;
A wireless communication means for communicating with the outside;
A portable radiation imaging device comprising:
A radiation imaging system comprising:
The imaging control means of the portable radiation imaging apparatus receives the irradiation signal from the radiation generating apparatus by the wireless communication means , in addition to receiving the irradiation start control signal from the radiation generating apparatus by the wireless communication means. without receiving a control signal for starting and wherein the shifting from the state sweeping charge detecting element Kinimo the radiographic image detection unit that detects the start of radiation irradiation to the charge storage state by the irradiation detecting means Radiation imaging system. The irradiation detection unit is a detection element that is a part of the radiation image detection unit, and continuously reads out charges at a cycle shorter than an irradiation time during which the radiation irradiation unit irradiates the subject. The radiation imaging system according to claim 1. The imaging control means shifts the detection element, which is the irradiation detection means, to a charge accumulation state when the radio communication means receives a radiation irradiation start control signal from the radiation generator, and stores the accumulated charge. The radiation imaging system according to claim 2, wherein: The imaging control unit includes a warning notification unit that issues a warning when the detection element is shifted from a charge sweeping state to a charge accumulation state by detection of radiation irradiation by the irradiation detection unit. 4. The radiation imaging system according to any one of items 1 to 3. The radiation imaging system according to any one of claims 1 to 4, wherein the irradiation detection unit is arranged in the radiation image detection unit. The radiation imaging system according to claim 5, wherein the irradiation detection unit is a part of the detection elements arranged in the radiation image detection unit. The signal output from the detection element functioning as the irradiation detection means is processed in common with a signal selection circuit that processes a signal output from the detection element for obtaining a radiation image. Item 7. The radiation imaging system according to Item 6.

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