JP2017192444A - Radiation imaging apparatus, processing device, and radiation imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology advantageous for appropriately achieving AEC by a simple method even when a test object is a complicated region.SOLUTION: A radiation imaging device is equipped with an imaging control part for performing radiation imaging using a plurality of sensors. The imaging control part receives image data on a reference image indicating a first subject, and acquires a data value on an object region which is a test object in the first subject, as a first data value, performs a first operation for acquiring a data value on a reference region which is another region different from the object region in the first subject as a second data value, and a second operation for performing radiation photographing about a second subject, monitors a signal value of a sensor corresponding to the reference region after irradiation of radiation onto the second subject is started in the second operation, and predicts an amount of radiation irradiated onto the object region based on the signal value acquired by the monitoring, the first data value, and the second data value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation imaging apparatus, a processing apparatus, and a radiation imaging method.

  The radiation imaging apparatus can include, for example, a sensor array in which a plurality of sensors for detecting radiation are arranged, a processor that processes signal values from each sensor, and the like. Some radiation imaging apparatuses perform automatic exposure control (Auto Exposure Control (AEC)) so that the radiation dose to the sensor array is within an appropriate range. That is, the radiation imaging apparatus ends the radiation irradiation when the radiation irradiation amount reaches the reference value.

  Here, when the dose of radiation that has passed through a part of the body of a subject (a subject such as a patient) increases, the portion is displayed in white in the radiographic image, and the dose of radiation that has passed through the part decreases. In the radiation image, the partial body is displayed in black. Therefore, the amount of radiation irradiation depends on the inspection target so that the subject to be inspected (diagnostic target) has an appropriate density or luminance in the radiographic image, so that the doctor can appropriately diagnose the inspection target. It may be adjusted by AEC.

JP-A-2005-369

  Japanese Patent Application Laid-Open No. 2004-133620 designates a method of performing AEC by specifying coordinates (positions) on a sensor array corresponding to a region to be inspected and monitoring the signal value of the sensor at the specified coordinates after radiation irradiation is started. Is described.

  By the way, the case of using the method of patent document 1 for the comparatively complicated site | part (for example, site | part in which a several organ and bone exist locally) is considered. However, according to this method, if the position of the subject with respect to the sensor array is deviated, the designated coordinates are deviated. As a result, the signal value of another sensor that is not the sensor of the designated coordinates is monitored. It may not be done properly.

  The present invention provides a technique that is advantageous for realizing AEC in a simple manner and appropriately even when the inspection target is a complex part.

  One aspect of the present invention relates to a radiation imaging apparatus, and the radiation imaging apparatus includes a radiation control unit that performs radiation imaging using a plurality of sensors that detect radiation, and the radiation control unit includes: Receiving the image data of the reference image indicating the first subject, obtaining the data value of the target portion to be inspected in the first subject as the first data value, and being designated as the reference portion in the first subject. Performing a first operation of acquiring a data value of another part different from the target part as a second data value, and a second action of performing radiography on the second subject using the plurality of sensors, In the second operation, the imaging control unit monitors a signal value of a sensor corresponding to the reference portion among the plurality of sensors after the irradiation of the second subject is started. And data, a signal value obtained by said monitor, said first data value, based on said second data values to predict the radiation dose irradiated to the target site.

  According to the present invention, AEC can be appropriately realized by a simple method.

It is a figure for demonstrating the structural example of a radiation imaging device. It is a figure for demonstrating the example of a structure of a part of imaging part. It is a figure for demonstrating the example of a structure of a part of read-out part. It is a figure for demonstrating the structural example of a process part. It is a figure for demonstrating the example of AEC. It is a timing chart for explaining an example of operation of a radiation imaging device. It is a figure for demonstrating the structural example of a radiation imaging device.

  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 a radiation imaging apparatus 10 according to the first embodiment. The radiation imaging apparatus 10 includes, for example, an imaging unit 100, a calculation unit 200, a terminal 210, a display unit 220, a radiation control unit 300, an exposure switch 310, and a radiation source 320.

  The imaging unit 100 includes, for example, a sensor array 110, a driving unit 120, a reading unit 130, a processing unit 140, a control unit 150, and a voltage supply unit 160. The sensor array 110 includes a plurality of sensors (referred to as sensors S) arranged in a matrix. The drive unit 120 drives the plurality of sensors S in units of rows. The reading unit 130 reads signals (sensor signals) from the sensors S in each column that are driven by the driving unit 120. The processing unit 140 processes the read sensor signal. The control unit 150 synchronously controls these units using a reference signal such as a clock signal. The voltage supply unit 160 supplies a power supply voltage for appropriately operating each of these units.

  The calculation unit 200 forms image data based on the sensor signal from the imaging unit 100, and additionally performs necessary image processing, and outputs the image data to the display unit 220 (display) to generate a radiation image. Display. In addition, the user calculates imaging information (parts to be examined in the subject (subject such as a patient), personal information of the subject, radiation dose to be targeted, and other information necessary for radiography) via the terminal 210. Can be input to the unit 200. The calculation unit 200 can control the imaging unit 100 and the radiation control unit 300 based on the input imaging information, and can manage image data obtained by radiography.

  The arithmetic unit 200 may be a personal computer storing a program or software for realizing each operation described in this specification, or may be an arithmetic device provided with an integrated circuit (for example, ASIC, FPGA, etc.).

  The radiation control unit 300 drives the radiation source 320 when the user presses the exposure switch 310 while receiving an irradiation start permission signal indicating that radiation irradiation is possible, for example, from the computing unit 200. The driven radiation source 320 irradiates the sensor array 110 of the imaging unit 100 with radiation (typically X-rays are used, but electromagnetic waves such as α-rays and β-rays may be used). To do. The irradiated radiation passes through a subject (not shown) and enters the imaging unit 100 and is detected by each sensor S of the sensor array 110.

  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 certain unit may be configured to be included in another unit, or some units may be configured to be integrated. For example, here, the configuration in which the processing unit 140 and the calculation unit 200 are individually arranged is illustrated, but these may be realized by a single unit. Moreover, the communication means for performing transmission / reception of signals between the imaging unit 100 and the calculation unit 200, between the calculation unit 200 and the radiation control unit 300 may be realized by a wired line such as a LAN, It may be realized by wireless such as Wi-Fi.

  FIG. 2 shows a configuration example of a part of the imaging unit 100 (specifically, the sensor array 110, the driving unit 120, and the reading unit 130).

  The sensor array 110 includes, for example, sensors S11 to S33 arranged in 3 rows × 3 columns (hereinafter simply referred to as “sensor S” unless otherwise distinguished). Note that i and j are integers of 1 to 3, and the sensor Sij is located in the i-th row and the j-th column. For example, the sensor S11 is located in the first row and the first column. , Sensor S23 is located in the second row and the third column. Here, for ease of explanation, a configuration of 3 rows × 3 columns is illustrated, but in reality, the number is larger than this number, for example, about 2800 rows × about 2800 columns in the example of a 17-inch sensor panel.

  Each sensor S includes, for example, a detection element D for detecting radiation, and a transistor T that connects the detection element D and the column signal line LC. In order to distinguish the codes of the column signal lines LC in the figure, those corresponding to the first column to the third column are LC1 to LC3, respectively. Line LC ". When the sensor S is configured to convert radiation into light and photoelectrically convert the light (so-called indirect conversion type), a scintillator can be disposed on the sensor array 110. In this case, a photoelectric conversion element such as a PIN sensor or a MIS sensor can be used as the detection element D, and a thin film transistor or the like can be used as the transistor T. In another example, the sensor S may be configured to directly convert radiation into an electrical signal (so-called direct conversion type).

  The drive unit 120 drives the sensors S in units of rows by controlling the transistors T of the sensors S using the control lines VG1 to VG3 arranged for each row. Specifically, for example, an activation signal is supplied to each sensor S in the first row via the control line VG1 to drive each sensor S in the first row. Thereby, for example, the sensor signals of the sensors S11, S12, and S13 are read by the reading unit 130 via the column signal lines LC1, LC2, and LC3, respectively.

  The reading unit 130 includes a unit 131, a multiplexer 132, and an output unit 133 corresponding to each column. Although details will be described later, the unit 131 performs sampling after amplifying the sensor signal from the corresponding sensor S, for example. The multiplexer 132 sequentially transfers the sampled sensor signal to the output unit 133 for each column. 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 processing unit 140 as a digital signal.

  FIG. 3 shows a configuration example of the unit 131 of the reading unit 130. The unit 131 includes, for example, a signal amplifying unit A1, a noise removing unit LPF, a first sampling unit USH1, and a second sampling unit USH2. The signal amplification unit 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 are arranged in a second feedback path that is a path parallel to the first feedback path. Further, the switch element SW12 and the feedback capacitor CFB2 are connected in series, and are arranged in a third feedback path that is a path parallel to the first and second feedback paths. It is possible to change the signal amplification factor of the signal amplification unit A1 by controlling the switch elements SW11 and SW12. When the switch element SW10 is turned on, the signal amplifier A1 is reset (initialized). When the switch elements SW11 and / or SW12 are turned on under the switch element SW10 being in the OFF 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 configuration example of the processing unit 140. The processing unit 140 includes a memory ME, a first processing unit 410, and a second processing unit 420. Although details will be described later, the radiation imaging apparatus 10 may include a read operation mode and an accumulation operation / AEC (automatic exposure control) mode as operation modes, and the processing unit 140 receives from the output unit 133 in these operation modes. The digital signal is stored in the memory ME.

  In the reading operation mode, sensor signals (digital signals) for forming a radiation image are read from the sensors S11 to S33 by the reading unit 130 and stored in the memory ME. Then, the first processing unit 410 reads the sensor signal from the memory ME, performs signal processing (for example, correction processing) on the sensor signal, and outputs the group of sensor signals subjected to the signal processing to the calculation unit 200. To do.

  In the accumulation operation / AEC mode, the reference value is reached so that the radiation dose is within an appropriate range after the radiation irradiation is started and before the sensor signal is read from each sensor S in the readout operation mode. In some cases, the irradiation is terminated. In this mode, sensor signals (digital signals) are read from a part of the sensors S11 to S33 as monitoring signals for performing AEC and temporarily stored in the memory ME (in addition, other sensors S). Then, charges corresponding to the irradiated radiation are accumulated.) In the following, for ease of explanation, a monitor signal read for performing AEC is simply expressed as a “monitor signal”. The second processing unit 420 reads a monitor signal from the memory ME and performs processing for performing AEC according to the present embodiment on the monitor signal. From this viewpoint, the second processing unit 420 or the processing unit 140 including the second processing unit 420 may be expressed as an imaging control unit for performing AEC in radiography.

  The second processing unit 420 includes, for example, a correction unit 421, a setting unit 422, a reference image data group 423, and a determination unit 424. Although the details will be described later, the setting unit 422 is necessary to perform AEC on the image data for one frame selected from the reference image data group 423 based on information input via the terminal 210 by the user. Set the parameters.

  In the present embodiment, the configuration in which the image data of the reference image is selected from the reference image data group 423 is exemplified, but the selection method is not limited to this example. For example, the image data of the reference image may be selected (or extracted) by the setting unit 422 based on the attribute information (ID or the like) of the data, or directly selected by the user operating the terminal 210 (Or input).

  The correction unit 421 corrects the monitor signal using the parameters set by the setting unit 422. The determination unit 424 determines whether or not the signal value of the corrected monitor signal has reached a reference value, and outputs a signal for ending radiation irradiation based on the determination result. This will be described in detail below with reference to FIGS. 5 (a) and 5 (b).

  FIG. 5A shows a radiation image (hereinafter referred to as “reference image”) based on image data selected from the reference image data group 423. The reference image may be displayed on the display unit 220, for example, so that the user can input information necessary for radiography with the terminal 210 while referring to the reference image. In this embodiment, the reference image shows the subject OB1 (mainly the area extending from the chest to the shoulder).

  The user is a part P1a of the subject OB1 in the reference image, which is a part P1а corresponding to a part to be inspected of a subject (hereinafter, referred to as “subject OB2” for distinction) that is a target of later radiography. Select (specify). In the present embodiment, the target site P1a refers to a part of the organ in the intercostal space (the space between two adjacent ribs), but it does not have to be this portion.

  After selecting (or before) the target part P1a, the user selects the part P1b corresponding to the part P1b of the subject OB1 that is not the inspection target of the subject OB2 as the reference part. In the present embodiment, the reference site P1b indicates a part of the clavicle, but may not be this part. Here, when the target part P1а is a relatively complicated part, a simpler part than the target part P1а may be selected as the reference part P1b.

  FIG. 5B shows the data value (for example, the density (luminance) on the image) of the image data at the cut line passing through the part P1a-P1b in the reference image. A portion with a large data value corresponds to a light (bright or white) portion on the image, and a portion with a small data value corresponds to a dark (dark or black) portion on the image. The ratio between the data value of the target part P1a and the data value of the reference part P1b (about 1.8 in this embodiment) is set by the setting unit 422 as a correction parameter (or coefficient).

  The user selects the target part P1a and the standard part P1b described above with reference to the reference image, and then performs radiation imaging on the subject OB2. Although details will be described later, the subject OB2 may be the same person as the subject OB1, or may be a person different from the subject OB1.

  Here, according to the conventional radiography method, when radiography is performed on the subject OB2, the portion that is the inspection target of the subject OB2 and that corresponds to the target portion P1a of the subject OB1 (hereinafter referred to as “target” It is conceivable that the monitor signal is read from the sensor S corresponding to the part P2a ") and AEC is performed. However, when the target part P2a is a relatively complicated part, it is difficult to specify the sensor S corresponding to the target part P2a, and it is not easy to read the monitor signal from the corresponding sensor S and perform AEC. For example, when a monitor signal is read from another sensor S different from the corresponding sensor S, an appropriate AEC may not be realized. This can occur particularly when the subject OB2 moves during radiography (ie, during AEC) and the relative position of the subject OB2 with respect to the sensor panel 110 shifts.

  Therefore, in the present embodiment, when radiography is performed on the subject OB2, it is another portion that is not the inspection target and corresponds to the reference portion P1b of the subject OB1 (hereinafter referred to as “reference portion P2b” for distinction). AEC is performed by reading a monitor signal from the sensor S corresponding to (). The reference part P2b can be a simpler part than the target part P2a, like the reference part P1b of the subject OB1, and therefore, even if the relative position of the subject OB2 with respect to the sensor panel 110 shifts, the corresponding part caused by it. Variations in the signal value of the sensor S can be reduced.

  The monitor signal from the sensor S corresponding to the reference site P2b is corrected by the correction unit 421 using the parameters set by the setting unit 422. As described above, this parameter is a parameter set based on the reference image that is the image of the subject OB1, and is the ratio between the data value of the target part P1a and the data value of the reference part P1b. By correcting the monitor signal using this parameter, a signal value corresponding to the signal value of the sensor S corresponding to the target part P2a is estimated, that is, the radiation dose (more specifically, the target part P2a is irradiated). , The radiation dose that has passed through the target part P2a) can be predicted. In summary, the estimated value of the signal value of the monitor signal from the sensor S corresponding to the target part P2a corresponds to the estimated radiation dose to the target part P2a, and the monitor signal from the sensor S corresponding to the reference part P2b; It is calculated based on the data value of the target part P1a and the data value of the reference part P1b.

  The determination unit 424 determines whether or not to end radiation irradiation based on the corrected signal value of the monitor signal (that is, the estimated value of the signal value of the sensor S corresponding to the target site P2a). Specifically, the signal value of the corrected monitor signal is cumulatively added in the determination unit 424 (or in the correction unit 421 or other calculation means), and the cumulative addition value has reached the reference value. In response, the determination unit 424 outputs a signal for ending radiation irradiation. In this way, AEC is realized.

  In the present embodiment, the monitor signal from the sensor S corresponding to the reference part P2b is corrected using the correction parameter, and whether the accumulated addition value of the signal values of the corrected monitor signal has reached the reference value. The aspect which performs AEC based on whether or not was illustrated. However, the AEC is not limited to this example. For example, a target value different from the reference value is prepared based on a parameter, and the cumulative addition value of the monitor signal from the sensor S corresponding to the reference part P2b is It may be realized based on whether or not the target value has been reached. That is, the reference value may be corrected using a parameter. In this case, the correction process is not performed on the monitor signal from the sensor S corresponding to the reference part P2b.

  Note that, as in the present embodiment, AEC may be realized based on whether or not the cumulative added value has reached the target value, but the timing at which radiation irradiation should be terminated based on the intermediate calculation result And AEC may be performed based on the prediction result. That is, the arithmetic processing for realizing AEC does not necessarily need to be executed until the cumulative added value reaches the target value.

  In order to improve the accuracy of the correction by the correction unit 421, it is preferable that the subject OB2 and the subject OB1 are the same person. However, when the subject OB2 is a new patient, for example, the relevance or similarity of the subject OB2 It is only necessary to use a reference image of another subject having a high height. In one example, a reference image of another subject within a range of ± 10% of the height of the subject OB2 may be used. In another example, another subject within a range of ± 10% of the weight of the subject OB2 may be used. The reference image may be used. In another example, reference images of other subjects within the range of ± 10% of the age of the subject OB2 may be used. In another example, a reference image of another subject having the same gender as the subject OB2 may be used. Here, height, weight, age and gender are exemplified as criteria for determining relevance or similarity, but body fat percentage, BMI (physique index), etc. may be referred to, and two or more of these conditions may be referred to It may be determined by a combination.

  When selecting the target part P1a and the standard part P1b while referring to the reference image, the data value of the target part P1a may be the pixel value of the pixel specified by the user in the reference image, but the target part P1a is enveloped It may be an average value of pixel values of a plurality of pixels in an area (or at least a part thereof). The same applies to the data value of the reference part P1b. In this case, it is preferable that the area enclosing the reference part P1b is larger (wider) than the area enclosing the reference part P1b in consideration of variations in pixel values in the area enclosing the reference part P1b. For the same reason, it is preferable that the reference part P1b has a gradual change in the concentration distribution (data value change rate) of the area enclosing the reference part P1b as compared to the area enclosing the reference part P1a.

  In the present embodiment, the processing for the AEC is performed by the second processing unit 420 in the processing unit 140. As described above, a part of the function of the processing unit 140 is realized by the arithmetic unit 200. In addition, this processing may also be realized by the arithmetic unit 200. That is, this process may be realized by an external device connected to the imaging unit 100. Specifically, the external device here is a processing device including a processor for performing signal processing or information processing, and may be expressed as a signal processing device, an information processing device, or the like.

  FIG. 6 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 310, the radiation source drive signal (signal level) for driving the radiation source 320, the radiation dose (intensity) from the radiation source 320, and the operation mode , The state of the power supply voltage and each signal (the signal level).

  Regarding the state of the exposure switch 310, a low level (L level) indicates that the switch 310 is not pressed, and a high level (H level) indicates that the switch 310 is pressed. When the radiation source drive signal becomes H level, the radiation source 320 is driven. The radiation dose indicates the intensity of radiation (irradiation amount per unit time) actually generated by the radiation source 320 in response to the radiation source drive signal becoming H level. The operation mode is an operation mode of the apparatus 10. In addition to the above-described read operation mode and accumulation operation / AEC mode, the operation mode is from when the power supply voltage is supplied to the apparatus 10 until radiation imaging can be started. Includes preparation mode of operation.

  The signal RST is a control signal for the switch element SW10 of the signal amplifying unit A1 in the 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 unit 131. When the signal CDS1 becomes H level, sampling is executed by the first sampling unit USH1. 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, each sensor S in the second row is 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, although the aspect which resets the sensor S of the 1st line-the 3rd line once was shown, actually reset is performed a plurality of times (for example, about 10 seconds). 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 310. The time when the user presses the exposure switch 310 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 is shifted 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 aforementioned monitor signals are read from the sensors S (S21 to S23) in the second row. More specifically, the monitor signal is AD-converted by the output unit 133 and stored in the memory ME, and then the second processing unit 420 performs processing for performing AEC. In the accumulation operation / AEC mode, charges corresponding to radiation are accumulated in the sensors S (S11 to S13 and S31 to S33) in the first and third rows.

  At time t53, the radiation dose from the radiation source 320 increases in response to the radiation source drive signal becoming H level at time t52. Therefore, in the example of FIG. 6, the signal value of the monitor signal read during time t52 to t53 is substantially zero.

  At time t54, it is determined that the radiation dose has reached the reference value, and the radiation source drive signal is set to the L level. Specifically, a value obtained by accumulating the estimated value of the signal value of the sensor S corresponding to the target site P2a of the subject OB2 based on the result of the processing by the second processing unit 420 described above is obtained. In response to reaching the reference value), the radiation source drive signal is set to L level. 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 reading operation mode, and sensor signals are read in order from all the sensors S. 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 the activation, whereby the first row to the third row are activated. Sensor signals are read in order from the sensor S in the row. The group of sensor signals read out in this way is stored in the memory ME as described above, subjected to predetermined signal processing by the first processing unit 410, and then output to the arithmetic unit 200. At this time, with respect to the sensor signal of the sensor S in the second row, most of the signal components are lost due to the above-described reading of the monitor signal for AEC (time t52 to t54). It may be corrected or supplemented based on this.

  In summary, in the present embodiment, referring to the reference image, the target part P1a corresponding to the target part P2a to be inspected of the subject OB2 is selected from the plurality of parts of the subject OB1, and the data value is selected. get. Further, a reference part P1b different from the target part P1a is selected from the plurality of parts of the subject OB1, and the data value is acquired. As described above, the reference part P1b may be a simple part with respect to the target part P1a. In the subsequent radiography of the subject OB2, AEC is performed based on the monitor signal of the sensor S corresponding to the reference part P2b, the data value of the target part P1a, and the data value of the reference part P1b. Specifically, based on these, the signal value of the sensor S corresponding to the target part P2a of the subject OB2 is estimated, and it is determined whether or not an appropriate amount of radiation has been applied to the target part P2a.

  Therefore, according to the present embodiment, even when the target part to be inspected is a relatively complicated part, it is not necessary to directly monitor the signal value of the sensor S corresponding to the target part, and the target part AEC can be performed such that an amount of radiation within the range is irradiated. In particular, since radiography may be performed a plurality of times or days for follow-up after surgery, etc., this embodiment is advantageous in reducing the burden on the subject.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. 7 (a) and 7 (b). In the first embodiment described above, the configuration in which the imaging unit 100 has a function for performing AEC is illustrated, but the present invention can be realized by other configurations. As illustrated in FIG. 7A, in the radiation imaging apparatus 20 according to the present embodiment, a processing unit 140 ′ is used instead of the processing unit 140, and the processing unit 140 ′ performs processing for AEC. The second processing unit 420 is not provided. On the other hand, the radiation imaging apparatus 20 further includes an AEC chamber 710 and an AEC chamber controller 720 for realizing the AEC function. That is, a mechanism for realizing the AEC function is arranged outside the imaging unit 100.

  As illustrated in FIG. 7B, the AEC chamber 710 includes chambers 711 to 713 that detect radiation incident on a specific area. For example, the chamber 711 corresponds to the right breast, and the chamber 712 includes Corresponding to the left chest, chamber 713 corresponds to the abdomen. The chamber controller 720 receives data or information indicating the radiation dose detected from the AEC chamber 710 via the connector 714. Then, when the radiation dose reaches the reference value, the chamber controller 720 outputs a signal for ending the radiation to the radiation source control unit 300.

  Even with such a configuration, it is possible to realize the same AEC as in the first embodiment. That is, any one of the chambers 711 to 713 is made to correspond to the reference portion P2b of the subject OB2, and the sensor S corresponding to the target portion P2a of the subject OB2 is based on the radiation dose detected by the corresponding chamber 711 or the like. Estimate the signal value. According to this embodiment, it is possible to realize the AEC without changing the configuration of the conventional radiation imaging apparatus.

  Further, in the first embodiment, a configuration in which each of the plurality of sensors S has both a function as an imaging sensor (that is, a function as a pixel) and a function as an AEC sensor for reading the monitor signal is exemplified. did. However, according to the present invention, a part of the AEC implementation method of the present embodiment is applied to the first embodiment, the function of most of the plurality of sensors S is fixed as an imaging sensor, and the remaining part of the AEC is AEC. The present invention can also be applied to a configuration in which the function is fixed as a general purpose 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. 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.

  10: radiation imaging apparatus, S: sensor, 140: processing unit, 200: calculation unit.

Claims (14)

A radiation imaging apparatus including an imaging control unit that performs radiography using a plurality of sensors that detect radiation,
The photographing control unit
The image data of the reference image indicating the first subject is received, the data value of the target portion that is the inspection target in the first subject is acquired as the first data value, and the reference portion is designated as the reference portion in the first subject. A first operation for acquiring a data value of another part different from the target part as a second data value;
A second operation of performing radiation imaging on a second subject using the plurality of sensors;
And
In the second operation, the photographing control unit
After the irradiation of the radiation to the second subject is started, the signal value of the sensor corresponding to the reference portion among the plurality of sensors is monitored,
A radiation imaging apparatus, wherein the radiation dose irradiated to the target region is predicted based on a signal value obtained by the monitor, the first data value, and the second data value. The radiation imaging apparatus according to claim 1, wherein, in the first operation, the imaging control unit refers to image data of the same subject as the second subject as image data of the reference image. In the first operation, the photographing control unit refers to image data of another subject different from the second subject as image data of the reference image,
The other subject is
The height is within ± 10% of the height of the second subject;
The weight is within ± 10% of the weight of the second subject;
The age is within ± 10% of the age of the second subject, and the gender is the same as the gender of the second subject,
The radiation imaging apparatus according to claim 1, wherein at least one of the following is satisfied. The first data value indicates a density of the target region in the reference image,
The radiation imaging apparatus according to any one of claims 1 to 3, wherein the second data value indicates a density of the reference region in the reference image. The density of the target part is an average density of the area of the target part in the reference image, and the density of the standard part is an average density of the area of the standard part in the reference image. The radiation imaging apparatus according to claim 4. In the reference image, a part that satisfies at least one of a change in density distribution that is gentler than that of the target part and a larger area on the image than that of the target part is designated as the reference part. The radiation imaging apparatus according to any one of claims 1 to 5, wherein the radiation imaging apparatus is characterized in that: In the second operation, the imaging control unit performs the prediction on the radiation dose irradiated to the target part based on a cumulative addition value of signal values of sensors corresponding to the target part. The radiation imaging apparatus according to any one of claims 1 to 6. The radiographic imaging according to claim 7, wherein it is determined whether or not the cumulative added value has reached a reference value, and the radiation irradiation is terminated when the cumulative added value reaches the reference value. apparatus. In the second operation, the photographing control unit reaches the reference value based on a signal value obtained by the monitor and a ratio between the first data value and the second data value. The radiation imaging apparatus according to claim 8, wherein it is determined whether or not it has been performed. In the second operation, the imaging control unit corrects the signal value obtained by the monitor using a ratio between the first data value and the second data value, and the corrected signal value is a target value. The radiation imaging apparatus according to claim 8 or 9, wherein it is determined whether or not the cumulative added value has reached the reference value based on whether or not the value has been reached. In the second operation, the imaging control unit sets a target value based on a ratio between the first data value and the second data value, and a signal value obtained by the monitor is set to the set target value. The radiation imaging apparatus according to claim 8 or 9, wherein it is determined whether or not the cumulative added value has reached the reference value based on whether or not the value has been reached. A processing device comprising a processor for processing signals from a plurality of sensors for detecting radiation,
The processor is
The image data of the reference image indicating the first subject is received, the data value of the target portion that is the inspection target in the first subject is acquired as the first data value, and the reference portion is designated as the reference portion in the first subject. A first operation for acquiring a data value of another part different from the target part as a second data value;
A second operation of performing radiation imaging on a second subject using the plurality of sensors;
And
The processor, in the second operation,
After the irradiation of the radiation to the second subject is started, the signal value of the sensor corresponding to the reference portion among the plurality of sensors is monitored,
A processing apparatus for predicting a radiation dose irradiated to the target region based on a signal value obtained by the monitor, the first data value, and the second data value. A radiography method using a plurality of sensors for detecting radiation,
The image data of the reference image indicating the first subject is received, the data value of the target portion that is the inspection target in the first subject is acquired as the first data value, and the reference portion is designated as the reference portion in the first subject. A first step of acquiring a data value of another part different from the target part as a second data value;
A second step of performing radiation imaging on a second subject using the plurality of sensors;
Including
The second step includes
Monitoring the signal value of the sensor corresponding to the reference part among the plurality of sensors after the irradiation of the radiation to the second subject is started;
Predicting the radiation dose irradiated to the target region based on the signal value obtained by the monitor, the first data value, and the second data value;
A radiation imaging method comprising:   The program for making a computer perform each process of Claim 13.