JP2018153359A - Radiographic apparatus, control method thereof, and imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology advantageous for improving quality of an image in a configuration for performing AEC.SOLUTION: A radiographic apparatus 10 includes a sensor array 11 in which a plurality of sensors capable of detecting a radioactive ray transmitting a subject are arrayed, a reading part 13 for performing signal reading from the sensor array 11, and a controller 16. Of the plurality of sensors, the controller 16 sets a sensor corresponding to a region of interest of object sites of the subject as a first sensor, sets a sensor corresponding to a region other than the region of interest of the subject as a second sensor, reads signals of the first sensor and the second sensor from the reading part 13 during the irradiation of the radioactive ray, ends the irradiation of the radioactive ray at least based on a signal value of the first sensor, and performs signal reading by the reading part from the sensor array 11 on condition that the signal value of the first sensor is within a first reference range, and the signal value of the second sensor is within a second reference range which is wider than the first reference range and includes the first reference range.SELECTED DRAWING: Figure 1

Description

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

  The radiation imaging apparatus includes, for example, a sensor array in which a plurality of sensors capable of detecting radiation are arranged, and a reading unit that reads a signal from each sensor, and generates image data based on the signal read by the reading unit Is done. Some radiation imaging apparatuses read out signals from a part of a plurality of sensors at a predetermined period during radiation irradiation, and terminate radiation irradiation in response to the signal value reaching a reference value ( Patent Document 1). Such control is called AEC (automatic exposure control). After radiation irradiation is completed by AEC, the radiation imaging apparatus reads out signals from each sensor by a reading unit and generates image data.

JP-A-7-201490

  According to Patent Document 1, since AEC is performed by referring to a signal value of a specific sensor, when signals are read from each sensor after the radiation irradiation is finished, signals from sensors other than the specific sensor are not intended. There was a possibility of becoming a value. This may cause a reduction in the quality of the radiation image.

  An object of the present invention is to provide a technique advantageous for improving the quality of a radiographic image in a configuration in which AEC is performed.

  One aspect of the present invention relates to a radiation imaging apparatus, and the radiation imaging apparatus includes a sensor array in which a plurality of sensors capable of detecting radiation transmitted through a subject are arranged, and a reading unit that reads a signal from the sensor array. A radiographic imaging apparatus including a controller, wherein the controller sets, as a first sensor, a sensor corresponding to a region of interest in a target region of the subject among the plurality of sensors, A sensor corresponding to a region other than the region of interest is set as a second sensor, and the signals of the first sensor and the second sensor are read out by the reading unit during the radiation irradiation, and at least the signal of the first sensor The irradiation of the radiation is terminated based on the value, the signal value of the first sensor falls within the first reference range, and the signal value of the second sensor Under the condition that falls within the second reference range including wide and the first reference range from the first reference range, and performs a signal read by the reading unit from the sensor array.

  According to the present invention, the quality of a radiographic image can be improved.

It is a figure for demonstrating the structural example of an imaging system. It is a figure for demonstrating a part of example of a structure of a radiation imaging device. It is a figure for demonstrating a part of example of a structure of the reading part. It is an operation | movement timing chart of the radiation imaging device for performing signal reading. It is a flowchart of AEC for improving the quality of a radiographic image. It is a figure for demonstrating the aspect which improves the quality of a radiographic image. It is a flowchart of AEC for improving the quality of a radiographic image. It is a figure for demonstrating the aspect which improves the quality of a radiographic image. It is a flowchart of AEC for improving the quality of a radiographic image. It is a figure for demonstrating the aspect which improves the quality of a radiographic image. It is a figure for demonstrating the selection method of the sensor used for AEC.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Each drawing is only described for the purpose of explaining the structure or configuration, and the dimensions of the illustrated members do not necessarily reflect actual ones. Moreover, in each figure, the same reference number is attached | subjected to the same member or the same component, and description is abbreviate | omitted about the overlapping content hereafter.

(First embodiment)
FIG. 1 shows a configuration example of an imaging system 1 according to the first embodiment. The imaging system 1 includes, for example, a radiation imaging apparatus 10, a computer 20, an operation terminal 21, a display 22, a radiation source 30, a radiation source control unit 31, and an exposure switch 32.

  The radiation imaging apparatus 10 includes, for example, a sensor array 11, a drive unit 12, a reading unit 13, a processor 14, a communication interface 15, a controller 16, a battery 17, and a power supply unit 18. Although details will be described later, the sensor array 11 includes a plurality of sensors (referred to as sensors S) arranged in an array, that is, so as to form a plurality of rows and a plurality of columns. The drive unit 12 drives the sensor array 11, and in the present embodiment, a plurality of sensors S can be driven for each row. The reading unit 13 reads a signal from the sensor array 11, and in this embodiment, reads a signal (sensor signal) from the sensor S driven by the driving unit 12 for each column. The processor 14 processes the sensor signal and generates image data. The image data generated by the processor 14 is output to the computer 20 via the communication interface 15.

  The controller 16 performs synchronous control of each element in the radiation imaging apparatus 10 using a reference signal such as a clock signal. The controller 16 may be configured by a semiconductor integrated circuit such as an ASIC (Application Specific Integrated Circuit) or a PLD (Programmable Logic Device), or may be configured by a CPU (Central Processing Unit) and a memory. . The same applies to the processor 14. That is, each function described in this specification can be realized by either hardware or software. In this embodiment, the processor 14 corresponds to an element that performs signal processing on a sensor signal, and the controller 16 corresponds to an element that performs synchronous control of other elements. However, as other embodiments, You may be comprised integrally.

  The power supply unit 18 supplies a power supply voltage to each element in the radiation imaging apparatus 10 based on the power from the battery 17. In this embodiment, the radiation imaging apparatus 10 is configured as a portable type including the battery 17 and the power supply unit 18. However, as another embodiment, the battery 17 is provided outside the apparatus 10. May be.

  The computer 20 receives the image data from the radiation imaging apparatus 10, performs incidental image processing (for example, correction processing), and displays a radiation image based on the image data on the display 22. In addition, the user can input information necessary for performing radiography to the computer 20 using the operation terminal 210 such as a keyboard before the start of radiography. This information includes, for example, information indicating examination contents such as a part to be examined (imaging target part) of a subject (subject) such as a patient, a radiation dose corresponding to the part. The computer 20 can control the radiation imaging apparatus 10 and the radiation source control unit 31 based on information input in advance by the user, and can manage image data obtained from the radiation imaging apparatus 10. In the present embodiment, the generation of the image data based on the sensor signal is performed by the processor 14 of the radiation imaging apparatus 10, but a part thereof may be performed by the computer 20.

  The radiation source 30 is connected to a radiation source control unit 31, and the radiation source control unit 31 is connected to an exposure switch 32. The radiation source control unit 31 drives the radiation source 30 when the exposure switch 32 is pressed by the user while receiving an irradiation start permission signal indicating that radiation irradiation is possible, for example, from the computer 20. As a result, the radiation source 30 generates radiation (typically X-rays are used, but alpha rays, beta rays, etc. may be used) and is applied to the sensor array 11 of the radiation imaging apparatus 10. Irradiate radiation. Radiation from the radiation source 30 passes through (passes through) a subject (not shown), enters the radiation imaging apparatus 10, and is detected by the sensor array 11.

  It goes without saying that the radiation imaging apparatus 10 is not limited to this configuration, and a part of this configuration may be changed or deleted depending on the purpose or the like, and other units may be added. Similarly, some functions of a unit may be configured to be realized by another unit, or some units may be configured integrally.

  FIG. 2 shows a configuration example of a part of the radiation imaging apparatus 10 (specifically, the sensor array 11, the drive unit 12, the reading unit 13, and the processor 14). The sensor array 11 includes a plurality of sensors S. In the drawing, for the purpose of distinction, the sensors are referred to as sensors S11 to S33. However, in the following description, when these are not particularly distinguished, they are simply expressed as “sensor S”. Here, for ease of explanation, a configuration in which the sensors S are arranged in 3 rows × 3 columns is illustrated, but the number of rows and the number of columns is not limited to this example. For example, an example of a 17-inch sensor panel Then, the sensors S can be arranged in about 2800 rows × about 2800 columns. Here, assuming that i and j are integers of 1 to 3, the sensor Sij is located in the i-th row and the j-th column. For example, the sensor S11 indicates that it is located in the first row and the first column, and the sensor S23 indicates that it is located in the second row and the third column.

  Focusing on the sensor S11, the sensor S11 includes a detection element D for detecting radiation and a transistor T. The transistor T is a switch element that connects the column signal line LC1 arranged corresponding to the first column of the sensor array 11 and the detection element D. In the detection element D, charges are generated based on the radiation incident on the sensor S11, and charges are accumulated in the detection element D while the transistor T is in a non-conductive state. When the transistor T becomes conductive, the charge accumulated in the detection element D is output to the column signal line LC1 as a sensor signal of the sensor S11.

  Although not described here, the other sensors S12 to S33 are configured in the same manner as the sensor S11. Similarly to the column signal line LC1, column signal lines LC2 to LC3 are arranged corresponding to the second to third columns of the sensor array 11, respectively. In the following description, the column signal lines LC1 to LC3 are simply expressed as “column signal lines LC” unless they are particularly distinguished.

  In the present embodiment, the sensor array 11 is configured to convert radiation into light and photoelectrically convert the light (so-called indirect conversion type), and a scintillator can be disposed on the sensor array 11. The detection element D is a photoelectric conversion element such as a PIN sensor or MIS sensor, and the transistor T is a switch element such as a thin film transistor. As another embodiment, the sensor array 11 may be configured to directly convert radiation into an electrical signal (so-called direct conversion type).

  The drive unit 12 drives the plurality of sensors S in units of rows using control lines VG1 to VG3 corresponding to the first to third rows, respectively. For example, the drive unit 12 supplies the activation signals to the sensors S11 to S13 in the first row via the control line VG1, thereby bringing the transistors T of the sensors S11 to S13 into a conductive state, and the sensors S11 to S13 are turned on. To drive. Thereby, for example, the sensor signals of the sensors S11 to S13 are output to the column signal lines LC1 to LC3, respectively.

  The reading unit 13 reads the sensor signal output from each sensor S through the column signal line LC for each column. The reading unit 13 includes a signal processing unit 131, a multiplexer 132, and an output unit 133. The signal processing unit 131 is provided for each column, and details thereof will be described later, but amplifies and samples the sensor signal output from the sensor S in the corresponding column. The multiplexer 132 sequentially transfers the sampled sensor signals to the output unit 133 for each column (horizontal transfer). The output unit 133 can include, for example, a buffer circuit, an analog-digital converter (ADC), and the like, and outputs each sensor signal to the processor 14 as a digital signal.

  The processor 14 has functions as a data processing unit 141 and an AEC processing unit 142. As a function of the data processing unit 141, the processor 14 generates image data based on the sensor signal read from the reading unit 13, and performs signal processing such as correction processing on the image data incidentally. Although details will be described later, the processor 14 performs automatic exposure control (AEC) as a function of the AEC processing unit 142 based on the sensor signal read from the reading unit 13. With this AEC, when the dose (integrated value) of radiation with respect to the sensor array 11 satisfies the standard, radiation irradiation can be terminated, and details of the content will be described later.

  FIG. 3 shows a configuration example of the signal processing unit 131 of the reading unit 13. The signal processing unit 131 includes, for example, a signal amplification unit A1, a noise removal unit LPF, a first sampling unit USH1, and a second sampling unit USH2. The signal amplifier A1 includes a differential amplifier A11, an input capacitor CIN, feedback capacitors CFB1 and CFB2, and switch elements SW10 to SW12. The input capacitor CIN is arranged between the inverting input terminal (input terminal indicated by “−” in the drawing) of the differential amplifier A11 and the column signal line LC. The non-inverting input terminal (input terminal indicated by “+” in the drawing) of the differential amplifier A11 is fixed to the reference voltage VREF.

  The switch element SW10 is arranged in a first feedback path between the inverting input terminal and the output terminal of the differential amplifier A11. The switch element SW11 and the feedback capacitor CFB1 are connected in series and arranged in a second feedback path that is a path parallel to the first feedback path. In addition, the switch element SW12 and the feedback capacitor CFB2 are connected in series and arranged in a third feedback path that is a path parallel to the first and second feedback paths. When the switch element SW10 becomes conductive, the signal amplifier A1 is reset (initialized). When the switch elements SW11 and / or SW12 are in a conductive state with the switch element SW10 in a non-conductive state, the signal amplifying unit A1 amplifies the sensor signal with a signal amplification factor corresponding to the state of the switch elements SW11 and SW12.

  The noise removal unit LPF is a low-pass filter for removing high-frequency noise components from the signal from the signal amplification unit A1, and a resistance element or the like is used for the noise removal unit LPF.

  The sampling units USH1 and USH2 are sampling circuits for performing correlated double sampling (CDS). Specifically, the sampling unit USH1 includes a sampling switch SWSH1 and a sampling capacitor CSH1, and samples a signal (so-called N signal) from the signal amplifying unit A1 reset by the switch element SW10. The sampling unit USH2 includes a sampling switch SWSH2 and a sampling capacitor CSH2, and samples the signal (so-called S signal) amplified by the signal amplification unit A1. The multiplexer 132 transfers the N signal and the S signal to the output unit 133, and the output unit 133 performs analog-to-digital conversion (AD conversion) as a signal component of the difference between the N signal and the S signal.

  FIG. 4 shows a timing chart for explaining an example of the operation of the radiation imaging apparatus 10. Specifically, with the horizontal axis as the time axis, the state of the exposure switch 32, the signal level of the radiation source drive signal for driving the radiation source 30, the radiation dose (intensity) from the radiation source 320, and the operation of the apparatus 10 The mode, the state of the power supply voltage, and the signal level of each signal are shown.

  Regarding the state of the exposure switch 32, a low level (L level) indicates that the switch 32 is not pressed, and a high level (H level) indicates that the switch 32 is pressed. When the radiation source drive signal becomes H level, the radiation source 30 is driven. The radiation dose indicates the intensity of radiation (irradiation amount per unit time. Irradiation intensity) actually generated by the radiation source 30 in response to the radiation source drive signal becoming H level.

  The radiation source drive signal is a drive signal that the radiation source control unit 31 outputs to the radiation source 30. For example, an exposure switch is generated while the radiation imaging apparatus 1 generates a signal indicating that imaging can be started by the controller 16 and the computer 20 outputs an irradiation start permission signal to the radiation source control unit 31 based on the signal. When 32 is pressed, the radiation source drive signal becomes H level. On the other hand, when it is determined by the AEC described later that the radiation dose (value obtained by time integration of the intensity of the radiation. Integrated value) satisfies the standard, the radiation imaging apparatus 1 ends the radiation by the controller 16. A signal is generated to indicate that a request is made. Based on this, the computer 20 outputs an irradiation end signal to the radiation source control unit 31, whereby the radiation source drive signal becomes L level.

  As operation modes, a preparation operation mode, an accumulation operation / AEC mode, and a read operation mode are shown in the drawing. In the preparatory operation mode, the operation is performed from when the apparatus 10 is activated until radiation imaging can be started. The temperature inside the apparatus 10 is stabilized and the sensor array 11 is initialized (reset). Is done. In the accumulation operation / AEC mode, radiation irradiation is started, and charges are accumulated in each sensor S (detection element D), and at the same time, AEC is performed. In the reading operation mode, signal reading from the sensor array 11 is executed in accordance with the end of radiation irradiation, and image data is obtained.

  The signal RST is a control signal for the switch element SW10 of the signal amplifying unit A1 in the signal processing unit 131. When the signal RST becomes H level, the signal amplifying unit A1 is reset. The signal CDS1 is a control signal for the switch element SWSH1 of the first sampling unit USH1 in the signal processing unit 131. When the signal CDS1 becomes H level, the first sampling unit USH1 performs sampling. The signal CDS2 is a control signal for the switch element SWSH2 of the second sampling unit USH2, and when the signal CDS2 becomes H level, the sampling is executed by the second sampling unit USH2. The signals VG1 to VG3 correspond to the signals of the control lines VG1 to VG3 (see FIG. 2), and the same reference numerals as those of the control lines VG1 to VG3 are used for easy understanding. For example, when the signal VG2 becomes H level, the sensors S21 to S23 in the second row are driven. In addition, the signal CLK is a clock signal used for AD conversion in the ADC of the output unit 133, and the signal ADCOUT indicates a digital signal obtained by the AD conversion.

  In the preparatory operation mode from time t50 to time t52, the signals VG1 to VG3 are sequentially activated while the H level pulse signal RST is supplied in a predetermined cycle, and the sensors S in the first to third rows are sequentially reset. . Here, the H level pulse indicates a pulse waveform that is changed from the L level state to the H level for a predetermined period and then to the L level again.

  In the preparation operation mode, since each sensor S is driven as described above, a sensor signal is output from each sensor S, but since the reading unit 13 is in a pause state, the sensor signal is not read. Specifically, the signal amplifying unit A1 is in a reset state when the switch element SW10 is maintained in the conductive state, and the signals CDS1 and CDS2 are maintained at the L level. Therefore, in the preparation operation mode, the sensor signal output from each sensor S is not read but discarded. This preparation operation mode can also be referred to as a “reset mode” or the like.

  Here, in order to make the drawing easier to see, the mode in which the sensors S in the first row to the third row are reset once is shown, but this reset is actually performed a plurality of times over a predetermined period (for example, about 10 seconds). , Repeatedly executed. Although not shown here, when all the sensors S are sufficiently reset, the user is notified that radiation irradiation can be started, and the user is exposed based on the notification. Press the shooting switch 32. The time when the user presses the exposure switch 32 is defined as time t51.

  At time t52, in response to the completion of the reset of the sensor S in the third row, the operation mode shifts to the accumulation operation / AEC mode, and the radiation source drive signal is set to the H level. In response to this, the signals CDS1 and CDS2 are activated alternately, during which the signal VG2 is activated, and the sensor signals are read from the sensors S21 to S23 in the second row at a predetermined cycle. Although details will be described later, AEC is executed based on this sensor signal.

  At time t53, the radiation dose from the radiation source 30 increases in response to the radiation source drive signal becoming H level at time t52. Therefore, although the radiation source drive signal becomes H level at time t52, the signal value of the sensor signal read from the sensors S21 to S23 during time t52 to t53 is substantially zero.

  After that, although details will be described later, when it is determined by AEC that the radiation dose (integrated value) satisfies the standard, the radiation source drive signal is set to the L level. This time is assumed to be time t54. Specifically, the radiation source drive signal is set to the L level based on the processing result by the processor 14 (AEC processing unit 142). Along with this, the radiation dose becomes the L level, and the radiation irradiation is completed.

  At time t55, the operation mode shifts to the read operation mode, and sensor signals are read sequentially from all the sensors S in the sensor array 11. Specifically, the signals CDS1 and CDS2 are alternately activated while supplying the signal RST of the H level pulse at a predetermined period, and the signals VG1 to VG3 are sequentially activated during that time. Sensor signals are read in order from the sensors S11 to S33 in the third row. The group of sensor signals read out in this way is subjected to predetermined signal processing by the processor 14 (data processing unit 141) and then output to the computer 20 as image data.

  Here, in this readout operation mode, most of the signal components of the sensor signals of the sensors S21 to S23 in the second row are lost due to the signal readout at time t52 to t54. Therefore, the sensor signals of the sensors S21 to 23 are corrected or complemented in the processor 14 based on the signal values of the sensor signals read at the times t52 to t54 and / or based on the signal values of the adjacent sensors S. It is good to be done.

  The control content for each sensor S in the read operation mode is the same as that in the preparation operation mode. In the preparation operation mode, the sensor signal output from the sensor S is discarded, but in the reading operation mode, the sensor signal output from the sensor S is read out by the reading unit 13.

  FIG. 5 shows a flowchart of AEC according to the present embodiment. This flowchart is mainly executed when the controller 16 receiving the processing result from the processor 14 drives or controls other elements. In this flowchart, a part of the plurality of sensors S of the sensor array 11 is selected and set as a sensor for monitoring based on information (examination contents) input in advance by the user. Thereafter, in the accumulation operation / AEC mode (see FIG. 4), the partial signal value is referred to, that is, the sensor signal is read out from this part in a predetermined cycle.

  In the present embodiment, the sensor S22 is set as the “first sensor” as the sensor S corresponding to the imaging target region, and other sensors S21 and S23 different from the first sensor are also set as the “second sensor”. Is set. Here, the first sensor is a sensor S arranged in a position in the sensor array 11 that is a site (tissue in the body) related to the examination content and that can directly image a site of interest to the user. On the other hand, the second sensor is another sensor S that is different from the first sensor among the sensors S that can image the subject, and may be a sensor S in the vicinity of the first sensor or away from the first sensor. It may be a position sensor S. That is, the first sensor is selected from a region to be imaged or a region that is particularly important among them, a so-called “region of interest”, and the second sensor is selected from sensors other than the region of interest in the subject. In this example, since the sensor array 11 has 3 rows and 3 columns, the first sensor (S22) and the second sensor (S21 and S23) are adjacent to each other.

  Thereafter, as described with reference to FIG. 4, in the accumulation operation / AEC mode, the sensors S21 to S23 in the second row are driven at a predetermined cycle, and the signal values of the sensors S21 to S23 (signal values Sig21 to Sig23, respectively). , And so on). Then, AEC is performed by referring to the signal value Sig22 of the first sensor S22, and image data obtained by the subsequent reading operation is unpredictable by referring to the signal values Sig21 and Sig23 of the second sensors S21 and S23. Is not included.

  First, in step S110 (hereinafter simply referred to as “S110”. The same applies to other steps), the controller 16 receives the processing result from the processor 14 and measures the signal value Sig22 of the first sensor S22. . The signal value Sig22 is held in a memory in the processor 14 (AEC processing unit 142), and is cumulatively added every time a signal is read from the sensor S22. The signal values Sig21 and Sig23 of the second sensors S21 and S23 are similarly measured.

  In S120, the controller 16 receives the processing result from the processor 14, and determines whether or not the radiation dose is sufficient based on the signal value Sig22 (cumulative addition value). If the radiation dose is sufficient, the process proceeds to S130, and if not, the process returns to S110. That is, in S110 to S120, radiation irradiation is continued until it is determined that the radiation irradiation amount is sufficient.

  In S130, an end request for radiation irradiation is made. This is realized by the controller 16 making the above determination based on the processing result received from the processor 14 and generating a signal indicating that the end of radiation is requested. That is, the controller 16 functions as a signal generating unit that generates a signal indicating a radiation end request when the radiation dose satisfies a standard. The contents of S110 to S130 described above correspond to AEC.

  Next, in S140, the controller 16 receives the processing result from the processor 14, and determines whether or not the signal values Sig21 and Sig23 of the second sensors S21 and S23 satisfy a predetermined condition after the radiation irradiation is completed. This condition is that, in the present embodiment, the signal values Sig 21 and Sig 23 have not reached the allowable upper limit value of the signal value that can be read by the reading unit 13. When this condition is not satisfied (that is, when the signal values Sig21 and Sig23 reach the allowable upper limit value), the process proceeds to S150, and otherwise, the process proceeds to S160.

  If the signal value of the sensor signal output from the sensor S to the column signal line LC becomes too large, the output value of the reading unit 13 receiving the sensor signal is saturated. This is due to the dynamic range depending on the circuit configuration of the reading unit 13. In this embodiment, the readout unit 13 includes a signal amplification unit A1, and when the signal value of the sensor signal is larger than the upper limit of the input signal value that can be amplified by the signal amplification unit A1, the output value of the signal amplification unit A1 is saturated, It becomes the output upper limit value. Therefore, if AEC is performed based on only the signal value of the sensor S22 corresponding to the imaging target region in S110 to S130, the other sensors S may have unexpected values.

  Therefore, in this embodiment, by referring to the signal values Sig21 and Sig23 of the sensors S21 and S23 in S140, whether or not the values are unexpected in other sensors S (sensors S21 and S23 in this embodiment). Judgment. In other words, it is determined whether or not the signal values of the other sensors S21 and S23 can be appropriately read out by the reading unit 13. Thereby, not only the signal values of the sensors S21 and S23 but also the signal values of the sensors S11 to S13 and S31 to S33 that do not directly refer to the signal values are appropriately read by the reading unit 13 thereafter (in the reading operation mode). It can be estimated whether or not it is possible. That is, according to the present embodiment, appropriate image data should be obtained by AEC, but a part of the radiation image is not appropriately displayed because the image data includes a signal value exceeding the dynamic range. The occurrence of such a situation can be prevented.

  In S150, the controller 16 changes the signal amplification factor of the signal amplification unit A1. In the present embodiment, since one of the signal values Sig21 and Sig23 is considered to have exceeded the allowable upper limit value of the signal value readable by the reading unit 13, the signal amplification factor is changed to another value smaller than that. Is done. The change of the signal amplification factor is realized by selecting the feedback capacitors CFB1 and / or CFB2 by controlling the switch elements SW11 and / or SW12 described with reference to FIG.

  In this embodiment, it is possible to set any signal amplification factor when only the feedback capacitor CFB1 is selected, when only the feedback capacitor CFB2 is selected, or when both the feedback capacitors CFB1 and CFB2 are selected. is there. However, the mode in which the signal gain can be set is not limited to these. For example, as another embodiment, one or more other feedback capacitors and other switch elements for selecting them are further provided in the signal amplifier A1, thereby further increasing variations of the mode in which the signal amplification factor can be set. be able to.

  In S150, the signal amplification factor is set to satisfy the following when the reading unit 13 reads the signal values Sig21 to S23 of the signals S21 to S23 using the signal amplification factor. That is, the signal value Sig22 satisfies the criterion of appropriate AEC, and both the signal values Sig21 and Sig23 are smaller than the allowable upper limit value of the signal value that can be read by the reading unit 13. This is because, as a result of changing the signal amplification factor so that the signal values Sig21 and Sig23 become smaller than the allowable upper limit value, the signal value Sig22 read by using the signal amplification factor appropriately realizes AEC. This is because the value may not be sufficient. Details will be described later.

  In S160, the controller 16 controls the drive unit 12 and the reading unit 13 to perform a reading operation. That is, in the reading operation mode (see FIG. 4), the controller 16 sequentially reads sensor signals from all the sensors S in the sensor array 11. According to the AEC and reading operation according to this flowchart, none of the sensor signals read from the sensor S is saturated, that is, the signal value (pixel value) constituting the image data is an unexpected value. Therefore, an appropriate radiographic image can be displayed.

  FIG. 6A shows an example of the flowchart described above. In the case where the signal value Sig23 has reached the allowable upper limit value, that is, the case where “No” is determined in S140, the signal gain is changed in S150. An embodiment in the case where there is not is shown. The horizontal axis in the figure indicates the radiation irradiation time, that is, the elapsed time from the start of radiation irradiation. The vertical axis in the figure indicates the signal value (cumulative addition value), the solid line indicates the signal value Sig22 of the first sensor S22, the one-dot chain line indicates the signal value Sig21 of the second sensor S21, and the two-dot chain line Indicates the signal value Sig23 of the second sensor S23.

  FIG. 6B is a diagram illustrating a case where the signal gain is changed in S150 in the case where the signal value Sig23 reaches the allowable upper limit value (that is, the case where “No” is determined in S140). The same applies to 6 (a). Since the change of the signal amplification factor is actually performed in S150 after the determination of S140, the line in the figure showing the signal values Sig21 to Sig23 indicates the changed signal amplification factor from the beginning (time t53). Virtually shown when used.

As can be seen from FIGS. 6A and 6B, a first reference range R1 that should be satisfied by the signal value Sig22 of the first sensor S22 is provided as a reference for AEC. The reference range R1 has an upper limit value R1 _MAX and a lower limit value R1 _MIN . The reference range R1 is set with a radiation dose that can appropriately diagnose an imaging target region when referring to a radiographic image as a target. That is, if the signal value Sig22 is within the reference range R1, it can be said that at least diagnosis of the region to be imaged is appropriately performed by a user such as a doctor.

Further, as a reference indicating whether or not appropriate reading by the reading unit 13 is possible, a second reference range R2 to be satisfied by the signal values Sig22 and Sig23 of the second sensors S21 and S23 is provided. Reference range R2 has an upper limit value R2 _MAX . The upper limit _{R2 MAX} is greater than the upper limit value _{R1 MAX} reference range R1, is set based on the allowable upper limit value saturation occurs in the output value at the reading section 13. That is, if the signal values Sig21 and Sig23 are within the reference range R2, a part different from the imaging target part in the radiographic image (in this embodiment, a part imaged by the sensors S21 and S23) is displayed relatively clearly. It can be said.

  In this way, the reference range R2 is provided so as to be wider than the reference range R1 and include the reference range R1. In the present embodiment, the lower limit value of the reference range R2 is not provided.

In the example of FIG. 6A, at time t54, the signal value Sig22 reaches the upper limit value R1 _MAX (Sig22 = R1 _MAX and does not exceed the reference range R1), which is the flowchart of FIG. This corresponds to the “Yes” determination in S120. In response to this, a radiation irradiation termination request is made in S130. Here, at time t54, the signal value Sig23 reaches the upper limit value R2 _MAX and is saturated. Therefore, in S140, it is determined that the signal value Sig23 cannot be properly read by the reading unit 13, and the signal amplification factor of the signal amplification unit A1 of the reading unit 13 is lowered in S150.

As can be seen from FIG. 6B, when the signal amplification factor of the signal amplification unit A1 is lowered, the signal value Sig23 becomes smaller than the upper limit value R2 _MAX , so that it can be appropriately read by the reading unit 13 without being saturated. Become. At this time, the signal amplification factor is set so that the signal value Sig22 is within the reference range R1, that is, the signal value Sig22 is set not to be smaller than the lower limit value R1 _MIN . Thereby, the display of the part different from the imaging target part can be made clear while enabling the display of the imaging target part to be diagnosed.

  In the present embodiment, the two sensors S21 and S23 are set as “second sensors”, but the number of the second sensors is not limited to this, and may be one or three or more. . In the present embodiment, the sensor S22 is set as the “first sensor”, but the number of the first sensors is not limited to this, and may be two or more.

  As described above, according to the present embodiment, the controller 16 sets the sensor S22 among the plurality of sensors S to “first” based on the imaging information (examination contents) input in advance by the user before the start of radiation irradiation. Set as “Sensor”. At the same time, the controller 16 sets other sensors S21 and S23 different from the sensor S22 as “second sensors”. Both the first sensor and the second sensor are sensors for monitoring in the accumulation operation / AEC mode. However, the first sensor is a part related to the examination content and is a part of interest directly to the user. The sensor S is arranged at a position where the region of interest can be imaged. On the other hand, the second sensor is another sensor S that can image a region other than the region of interest in the subject, and is a reference sensor S that is selected to clearly display a region different from the region to be imaged. .

After the start of radiation irradiation, the controller 16 reads out the signal values Sig21 to Sig23 of the sensors S21 to S23 by the reading unit 13. In the present embodiment, the irradiation of radiation is terminated based on the signal value Sig22, and the reading unit from the sensor array 11 under the condition that the signal value Sig22 is in the reference range R1 and the signal values Sig21 and Sig23 are in the reference range R2. 13 performs signal readout. The reference range R2 is wider than the reference range R1 and includes the reference range R1, and in this embodiment, the upper limit value R2 _MAX of the reference range R2 is larger than the upper limit value R1 _MAX of the reference range R1, and the lower limit value of the reference range R2 Is not provided. Note that the above conditions (conditions in which the signal value Sig22 is in the reference range R1 and the signal values Sig21 and Sig23 are in the reference range R2) may not necessarily be satisfied at the end of radiation irradiation. Reading may be performed under the above conditions.

  In the present embodiment, the signal amplification factor of the signal amplifying unit A1 included in the reading unit 13 is lowered so that the signal value Sig22 is in the reference range R1 and the signal values Sig21 and Sig23 are in the reference range R2. . As a result, a signal capable of diagnosing the region to be imaged is obtained from the sensor S22 that images the region to be imaged, and the region is clearly displayed from the sensors S21 and S23 that image regions other than the region to be imaged. Signal is obtained. In addition, it can be expected that the sensors S11 to S13 and S31 to 33 can obtain a signal that clearly displays a region other than the imaging target region. Therefore, according to the present embodiment, the quality of the radiation image can be improved in the configuration in which AEC is performed.

  In the present embodiment, the configuration of each sensor S is exemplified by a configuration in which signal reading is performed by destructive reading (a method in which a signal is erased when a certain signal is read), but this corresponds to non-destructive reading. A configuration may be employed. That is, each sensor S is configured to hold a signal value accumulated and added with irradiation of radiation in the sensor S in a memory or the like, and to read the signal value any number of times at an arbitrary timing. Even in such a configuration, the contents of the above embodiment can be realized.

(Second Embodiment)
The second embodiment is different from the first embodiment described above in that a lower limit value _R2MIN is mainly provided in the reference range R2. Also in the present embodiment, as in the first embodiment, it is assumed that the sensor S22 is set to “first sensor” and the sensors S21 and S23 are set to “second sensor”. According to the present embodiment, it is possible to prevent the occurrence of a situation in which the radiographic image is not properly displayed because the signal values Sig21 and Sig23 of the second sensors S21 and S23 are too small (although they have not reached the upper limit value R2 _MAX ). it can. For example, if the signal value from the sensor S is too small, the signal component may be buried in noise (system noise or the like) in the reading unit 13. According to this embodiment, the quality of a radiographic image can be improved by preventing such disappearance of signal components.

  FIG. 7 shows a flowchart of AEC according to the present embodiment. In S210, signal values Sig21 to Sig23 of the sensors S21 to S23 are measured. The measurement method is the same as S110 of the first embodiment (see FIG. 5).

  In S220, the controller 16 receives the processing result from the processor 14, and determines whether or not the signal values Sig21 and Sig23 of the second sensors S21 and S23 satisfy a predetermined condition. This condition is that, in the present embodiment, the signal values Sig 21 and Sig 23 both reach the minimum signal value that can be read by the reading unit 13. This minimum value is, for example, a value that can be read by the reading unit 13 without causing the sensor signal to be buried in noise. When the above conditions are satisfied (that is, when the signal values Sig21 and Sig23 reach this minimum value), the process proceeds to S230, and otherwise, the process returns to S210. As a result, radiation irradiation is continued until the signal values Sig21 and Sig23 reach at least the minimum value.

In S230, the controller 16 receives the processing result from the processor 14, and determines whether or not the signal value Sig22 of the first sensor S22 satisfies a predetermined condition. This condition, the signal value Sig22 is that reached the lower limit _{R1 MIN} reference range R1. When this condition is satisfied (that is, when the signal value Sig22 reaches the lower limit value R1 _MIN ), the process proceeds to S130, and otherwise, the process returns to S210. Thus, the signal value Sig22 is, until at least the lower limit value _{R1 MIN,} so that the irradiation is continued. Subsequent S130 and S160 are the same as those in the first embodiment (see FIG. 5), and thus the description thereof is omitted here.

Therefore, in this embodiment, radiation irradiation is continued until the following condition is satisfied. That is, the signal values Sig21 and Sig23 reach the lower limit value R2 _MIN (“Yes” determination in S220), and the signal value Sig22 reaches the lower limit value R1 _MIN (“Yes” determination in S230). In other words, in the present embodiment, the end timing of radiation irradiation is determined based on these two conditions.

FIG. 8A shows, as an example of the above flowchart, when the signal value Sig22 has reached the lower limit value R1 _MIN of the reference range R1, the signal value Sig23 has not reached the lower limit value R2 _MIN of the reference range R2. The case is shown in the same manner as in FIG. In the figure, the time when the signal value Sig22 reaches the lower limit value R1 _MIN is defined as “time t54 ′”. In the present embodiment, the signal value Sig22 has reached the lower limit value _{R2 MIN} time t54 'the reference range R2.

In the present embodiment, at time t54 ′ (the signal value Sig22 has reached the lower limit value R1 _MIN of the reference range R1), but since the signal value Sig23 has not reached the lower limit value R2 _MIN , radiation irradiation is terminated. Absent. This corresponds to the “No” determination in S220 of the flowchart of FIG.

FIG. 8B shows that at time t54 after time t54 ′, the signal values Sig21 and Sig23 reach the lower limit value R2 _MIN , and the signal value Sig22 reaches the lower limit value R1 _MIN . A mode in the case where the irradiation is terminated is shown.

In the present embodiment, until the signal value Sig23 reaches the lower limit value R2 _MIN, to continue the irradiation of radiation, it can be said is in the form of its termination request is pending. However, as another embodiment, when the signal value Sig22 before the signal value Sig23 reaches the lower limit value _{R2 MIN} has reached the upper limit value _{R1 MAX} of the reference range R1, the controller 16 may forcibly irradiation It can also be terminated. This is because the radiographic image displayed on the display 22 gives priority to appropriately displaying the imaging target region based on the signal value Sig22.

The signal value of the sensor signal is considered to increase substantially linearly as the radiation irradiation time increases. Therefore, as another embodiment, the controller 13, when the signal value Sig23 is less than the lower limit value R2 _MIN includes the signal value Sig23, based on the irradiation time, the timing should be the end of the irradiation of the radiation Can be calculated and determined.

According to the present embodiment, the controller 13 applies the radiation so that the signal value Sig22 of the first sensor S22 is within the reference range R1, and the signal values Sig21 and Sig23 of the second sensors S21 and S23 are within the reference range R2. Determine the end timing. Lower limit _{R2 MIN} of the reference range R2 is set based on the minimum value of the readable signal value of the read section 13, the lower limit _{R1 MIN} of the reference range R1 is larger than the lower limit value _{R2 MIN.} According to the present embodiment, the sensor S22 that images the imaging target region can obtain a signal capable of diagnosing the imaging target region, and the sensors S21 and S23 that image the region other than the imaging target region can detect the region. A signal that clearly displays the signal is obtained. In addition, it can be expected that the sensors S11 to S13 and S31 to 33 can obtain a signal that clearly displays a region other than the imaging target region. Therefore, according to the present embodiment, the quality of the radiation image can be improved in the configuration in which AEC is performed as in the first embodiment.

The lower limit value _R2MIN is preferably set larger than the average value of noise generated at the output of the reading unit 13 when the reading unit 13 reads the signal. For example, the lower limit value R2 _MIN may be set to be 10 times or more of the average value. Thereby, it is possible to prevent the sensor signal to be read by the reading unit 13 from being buried in noise.

  In the present embodiment, the mode of determining the end timing of radiation irradiation is illustrated. However, as another embodiment, the radiation irradiation is terminated at time t54 ′ and the signal amplification factor of the signal amplification unit A1 is increased. It is also possible to perform signal readout. In that case, the signal amplification factor of the signal amplifier A1 may be increased so that the signal value Sig22 is in the reference range R1 and the signal values Sig21 and Sig23 are in the reference range R2.

(Third embodiment)
In the first embodiment described above, attention has been paid to realizing desired AEC and preventing the signal values Sig21 and Sig23 from being saturated beyond the dynamic range of the reading unit 13. In the second embodiment described above, attention is paid to realizing desired AEC and preventing the signal values Sig21 and Sig23 from being buried in the noise of the reading unit 13. The third embodiment is realized by combining the gist of these first and second embodiments.

  FIG. 9 shows a flowchart of AEC according to the present embodiment. In the present embodiment, in S210 to S230, the signal obtained from the sensor S22 that images the imaging target region is made diagnosable, and the signals of the sensors S21 and S23 that image other sites are imaged. Prevents being buried in noise. In subsequent S130 to S160, the signal obtained from the sensor S22 that images the region to be imaged is made diagnosable, and the signals of the sensors S21 and S23 that image other regions are saturated. To prevent it.

The individual contents of S210 to S230 and S130 to S160 are the same as the contents of the flowcharts of the first and second embodiments (see FIG. 5 and FIG. 7), and thus the description thereof is omitted here. However, the determination condition of S230 is that the signal value Sig22 of the first sensor S22 satisfies the upper limit value R1 _MAX instead of the lower limit value R1 _MIN of the reference range R1. This is because the signal amplification factor of the signal amplification unit A1 may be lowered in later S150.

FIG. 10A shows a mode in which the signal value Sig22 reaches the upper limit value R1 _MAX of the reference range R1 as an example of the description of the flowchart. At time t54 when the signal value Sig22 reaches the upper limit value R1 _MAX of the reference range R1, the signal value Sig23 reaches the upper limit value R2 _MAX of the reference range R2, and is saturated. Note that in the same time t54, the signal value Sig21 has reached the lower limit value _{R2 MIN} reference range R2. This corresponds to a state in which “Yes” determination is made in both S220 and S230 of the flowchart, and then “No” determination is made in S140. Therefore, it is determined that the signal value Sig23 cannot be appropriately read by the reading unit 13, and the signal amplification factor of the signal amplification unit A1 of the reading unit 13 is lowered in S150.

FIG. 10B shows an aspect in the case where the signal amplification factor of the signal amplification unit A1 is lowered by S150. As a result, the signal value Sig23 is smaller than the upper limit value R2 _MAX , and therefore can be appropriately read by the reading unit 13 without being saturated. At this time, the signal amplification factor is set so that the signal value Sig22 is within the reference range R1, that is, the signal value Sig22 is set not to be smaller than the lower limit value R1 _MIN . Further, by reducing the signal amplification factor, noise generated in the reading unit 13 is reduced. Therefore, the lower limit value R2 _MIN of the reference range R2 is lowered to the lower limit value R2 _MIN ′ lower than that. Therefore, even when lowering the signal amplification factor, the signal value Sig21 can be a reference range R2 without being smaller than the lower limit value R2 _{MIN '.}

According to the present embodiment, the controller 16 reads the signal values Sig21 to S23 of the sensors S21 to S23 by the reading unit 13 after the start of radiation irradiation. Then, in response to the signal value Sig22 reaching the upper limit value R1 _MAX of the reference range R1 and the signal values Sig21 and Sig23 both reaching the lower limit value R2 _MIN of the reference range R2, the radiation irradiation is terminated. Thereafter, when the controller 16 reduces the signal amplification factor of the signal amplification unit A1 and performs signal readout from the sensor array 11 by the readout unit 13, the signal value Sig22 falls within the reference range R1, and the signal values Sig21 and Sig23 fall within the reference range R2. _Or less than the upper limit value R2 _MAX . According to the present embodiment, the signal obtained from the sensor S22 that images the region to be imaged can be diagnosed, and the signals of the sensors S21 and S23 that image the other region can be noise. It can prevent being buried or saturated.

In the present embodiment, radiation irradiation is continued until the signal value Sig22 reaches the upper limit value R1 _MAX of the reference range R1 and the signal values Sig21 and Sig23 both reach the lower limit value R2 _MIN of the reference range R2, It can be said that the request is put on hold. However, as another embodiment, if the signal value Sig22 reaches the upper limit value R1 _MAX of the reference range R1 before the signal values Sig21 and Sig23 reach the lower limit value R2 _MIN of the reference range R2, the controller 16 It is also possible to terminate the irradiation of radiation. This is because the radiographic image displayed on the display 22 gives priority to appropriately displaying the imaging target region based on the signal value Sig22.

(Fourth embodiment)
In the fourth embodiment, a selection method of “first sensor” and “second sensor” will be described. As described above, both the first sensor and the second sensor are sensors for monitoring in the accumulation operation / AEC mode. The first sensor is a sensor S that is a part related to the examination content and is arranged at a position where a region of interest including a part directly interested in the user can be imaged. On the other hand, the second sensor is another sensor S that can image a region other than the region of interest in the subject, and is a reference sensor S that is selected to clearly display a region different from the region to be imaged.

  In the example of FIG. 11A, on the sensor array 11, normal sensors (sensors shown by white boxes) and monitor-use sensors (sensors shown by hatched boxes) are mixed. ing. The normal sensor is a sensor that cannot be set as the first sensor / second sensor, and is a sensor S dedicated to imaging. The sensor serving as a monitor is a sensor S that can be set as a first sensor / second sensor, and can function both as an image sensor and a monitor for AEC. The sensors serving as monitors are scattered in the sensor array 11 so as not to be adjacent to each other. Here, among the sensors serving as monitors, the ones marked with “x” indicate the sensor S set as the first sensor, and the ones marked with “\” indicate the sensor S set as the second sensor. Indicates.

  As can be seen from FIG. 11 (a), the second sensor is at least one arranged at a position closest to the first sensor, and in the present embodiment, the second sensor is located 4 above, below, left, and right respectively. One. According to such an aspect, based on the signal from the 1st sensor which images the imaging | photography object site | part, this imaging | photography object site | part can be diagnosed appropriately, and the surrounding site | part is a signal from a 2nd sensor. Diagnosis can be made appropriately based on the above. That is, according to this example, when referring to a radiographic image, it is easy to see the region to be imaged and its periphery, which is advantageous for improving the accuracy of diagnosis.

  In the example of FIG. 11B, the sensor array 11 is divided into a plurality of areas AR11 to AR33. In this example, it is divided into a total of 9 areas of 3 × 3, but is not limited to this number. In this example, a part of the areas AR11 to AR33, which is the area AR22 in this example, is selected based on imaging information (examination contents) input in advance by the user before the start of radiation irradiation. The area AR22 is an area partitioned to include the area of interest.

  Here, the first sensor and the second sensor may be selected and set from the sensors arranged in the area AR22. In this case, the first sensor and the second sensor may be selected so as not to be adjacent to each other. According to this example, when referring to a radiographic image, it is easy to see the region to be imaged and its periphery, which is advantageous in improving the accuracy of diagnosis. In this example, one area AR22 is selected, but two or more areas may be selected.

  In the example of FIG. 11C, as in the example of FIG. 11B, a part of the divided regions AR11 to AR33 is selected as a region where the region of interest can be imaged based on the imaging information (examination content). Is done. Consider the case where the area AR22 is selected also in this example. Here, the first sensor is selected from sensors in the area AR22, while the second sensor is selected from sensors in other areas. In this example, the second sensor is selected from each of the regions R12 and AR32. According to this example, when referring to a radiographic image, not only the region to be imaged but also the entire radiographic image is easy to see.

  According to the above-described example, by selecting and setting the first sensor and the second sensor according to the purpose and the like, it is possible to make it easy to see not only the imaging target site but also other sites related thereto in the radiographic image. . The first sensor and the second sensor can be selected by the controller 16 by referring to the reference table, for example, based on the photographing information, but the selection method is not limited to the above example. For example, the user can directly select any sensor in the sensor array 11 as the first sensor / second sensor.

(program)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program May be realized. For example, the present invention may be realized by a circuit (for example, ASIC) that realizes one or more functions.

(Other)
As mentioned above, although some suitable aspects were illustrated, this invention is not limited to these examples, The one part may be changed in the range which does not deviate from the meaning of this invention. For example, the contents of one embodiment may be combined with part of the contents of another embodiment, and in addition to / alternatively, known elements may be added or deleted as necessary. Also good. In addition, it is needless to say that each term described in this specification is merely used for the purpose of describing the present invention, and the present invention is not limited to the strict meaning of the term. The equivalent can also be included.

  1: radiation imaging device, 11: sensor array, S: sensor, 13: readout unit, 16: controller, S22: first sensor, S21 (S23): second sensor, Sig22: signal value of first sensor, Sig21 ( Sig23): signal value of the second sensor, R1: first reference range, R2: second reference range.

Claims (20)

A radiation imaging apparatus comprising: a sensor array in which a plurality of sensors capable of detecting radiation transmitted through a subject are arranged; a reading unit that reads signals from the sensor array; and a controller.
The controller is
Among the plurality of sensors, a sensor corresponding to a region of interest in the target part of the subject is set as a first sensor, and a sensor corresponding to a region other than the region of interest in the subject is set as a second sensor. And
During irradiation of the radiation, the signals of the first sensor and the second sensor are read by the reading unit, and the irradiation of the radiation is terminated based on at least the signal value of the first sensor. The reading unit from the sensor array under the condition that the value is within the first reference range and the signal value of the second sensor is larger than the first reference range and within the second reference range including the first reference range. A radiation imaging apparatus, wherein signal readout is performed by The reading unit includes a signal amplification unit,
When the controller performs signal reading from the sensor array by the reading unit after the radiation irradiation ends, the signal value of the first sensor is within the first reference range and the signal value of the second sensor is The radiation imaging apparatus according to claim 1, wherein a signal amplification factor of the signal amplification unit is changed so as to be within the second reference range. The signal amplifying unit has a plurality of feedback capacitors and a plurality of switch elements respectively connected to them.
The radiation imaging apparatus according to claim 2, wherein the controller changes the signal amplification factor of the signal amplification unit by controlling the plurality of switch elements. 4. The second reference range is a range in which at least one of an upper limit value and a lower limit value is set based on a range of signal values that can be read by the reading unit. A radiation imaging apparatus according to claim 1. The upper limit value of the second reference range is set based on an allowable upper limit value of a signal value that can be read by the reading unit,
The radiation imaging apparatus according to claim 4, wherein an upper limit value of the first reference range is set smaller than an upper limit value of the second reference range. The lower limit value of the second reference range is set based on a minimum value of signal values that can be read by the reading unit,
The radiation imaging apparatus according to claim 4, wherein a lower limit value of the first reference range is set to be larger than a lower limit value of the second reference range. The radiographic imaging according to claim 6, wherein the lower limit value of the second reference range is set to be larger than an average value of noise generated at the output of the reading unit during signal reading of the reading unit. apparatus. The controller sets the radiation so that the signal value of the first sensor is within the first reference range and the signal value of the second sensor is within the second reference range before the end of the radiation irradiation. The radiation imaging apparatus according to claim 6, wherein an end timing of irradiation is determined. The controller, when the signal value of the second sensor is less than the lower limit value of the second reference range, based on the signal value and the elapsed time from the start of the irradiation of the radiation, The radiation imaging apparatus according to claim 8, wherein an end timing of irradiation is determined. 10. The controller according to claim 1, wherein the controller reads signals from the first sensor and the second sensor by the reading unit at a predetermined cycle after the radiation irradiation is started. The radiation imaging apparatus according to Item. The reading unit includes a signal amplification unit,
The controller sets a plurality of the second sensors based on imaging information input in advance by a user before the start of the radiation irradiation,
The controller is
After starting the radiation, the signal value of the first sensor reaches the upper limit value of the first reference range, and the signal values of the plurality of second sensors all reach the lower limit value of the second reference range. Depending on the case, the irradiation of the radiation is terminated,
When signal reading is performed from the sensor array by the reading unit after the radiation irradiation is completed, the signal value of the first sensor is within the first reference range and the signal value of the second sensor is the second reference value. The radiation imaging apparatus according to claim 10, wherein the signal amplification factor of the signal amplification unit is lowered so as to be equal to or less than an upper limit value of the range. The radiation according to claim 11, wherein an average value of noise generated at the output of the reading unit when the signal of the reading unit is read is reduced when a signal amplification factor of the signal amplifying unit is lowered. Imaging device. The two or more sensors that can be set as the first sensor or the second sensor among the plurality of sensors are provided so as to be scattered discretely in the sensor array. The radiation imaging apparatus according to claim 12. The controller is based on shooting information input in advance by the user,
One of the two or more sensors is set as the first sensor;
The radiation imaging apparatus according to claim 13, wherein among the two or more sensors, a sensor disposed at a position closest to the first sensor is set as the second sensor. The controller receives imaging information input in advance by a user before the start of the radiation irradiation,
The radiation imaging apparatus according to claim 1, wherein the imaging information includes information indicating a part to be inspected of a subject. The sensor array is divided into a plurality of regions,
The controller is
Based on the imaging information input in advance by the user, the one corresponding to the imaging target part is selected from the plurality of areas,
A part of two or more sensors arranged in the selected region is set as the first sensor, and one of the two or more sensors not adjacent to the first sensor is set as the second sensor. The radiation imaging apparatus according to any one of claims 1 to 15, wherein: The sensor array is divided into a plurality of regions,
The controller is
Based on the imaging information input in advance by the user, the one corresponding to the imaging target part is selected from the plurality of areas,
The sensor arranged in the selected area is set as the first sensor, and the sensor arranged in an area different from the selected area is set as the second sensor. The radiation imaging apparatus according to claim 15. A sensor array in which a plurality of sensors capable of detecting radiation transmitted through a subject are arranged;
A drive unit for driving the sensor array;
A reading unit for reading signals from the sensor array;
A signal generator;
A radiation imaging apparatus comprising:
The drive unit is a first sensor that is a sensor corresponding to a region of interest in a target part of the subject among the plurality of sensors, and a sensor that corresponds to a region other than the region of interest in the subject. Driving the second sensor;
During the radiation irradiation, the reading unit reads the signals of the first sensor and the second sensor, and the signal generation unit requests the end of the radiation irradiation based on at least the signal value of the first sensor. And a signal value of the first sensor is within a first reference range, and a signal value of the second sensor is wider than the first reference range and includes the first reference range, and The radiation imaging apparatus, wherein the readout unit performs signal readout from the sensor array under the following conditions. The radiation imaging apparatus according to any one of claims 1 to 18,
An imaging system comprising: a radiation source that generates the radiation. A control method for a radiation imaging apparatus, comprising: a sensor array in which a plurality of sensors capable of detecting radiation transmitted through a subject are arranged; and a reading unit that reads signals from the sensor array,
Among the plurality of sensors, a sensor corresponding to a region of interest in the target part of the subject is set as a first sensor, and a sensor corresponding to a region other than the region of interest in the subject is set as a second sensor. And a process of
During irradiation of the radiation, the signals of the first sensor and the second sensor are read by the reading unit, and the irradiation of the radiation is terminated based on at least the signal value of the first sensor. The reading unit from the sensor array under the condition that the value is within the first reference range and the signal value of the second sensor is larger than the first reference range and within the second reference range including the first reference range. And a step of performing signal readout by the method of controlling a radiation imaging apparatus.

Images