Radiation imaging system, imaging control device, control method, and program

Abstract

This radiation imaging system that can utilize an AEC function for performing stop control of radiation on the basis of the dose of incident radiation on a radiation imaging apparatus includes: a registration unit for registering setting information for an imaging procedure; and a presentation unit for automatically setting at least one setting relating to the AEC function for radiation imaging by the imaging procedure on the basis of the setting information, or for presenting to a user at least one setting candidate relating to the AEC function.

Description

Radiation imaging system, imaging control device, control method, and program

[0001] The present disclosure relates to a radiation imaging system, an imaging control device, a control method, and a program.

[0002] Radiation imaging devices that combine a pixel array provided with a conversion element that converts radiation into charge, a switching element such as a thin film transistor, and wiring, with a drive circuit and a readout circuit have been put into practical use. One type of radiation imaging device has a function of detecting irradiation information while a radiation source irradiates radiation. This function includes a function of detecting the timing of the start of incidence of radiation irradiated from the radiation source, and a function of detecting the irradiation dose and the integrated irradiation dose of radiation. By this function, it is possible to monitor the integrated irradiation dose and perform automatic exposure control in which the detection device controls the radiation source to end irradiation when the integrated irradiation dose reaches an appropriate amount. By incorporating this automatic exposure control function into the radiation imaging device, stable radiation irradiation control is possible in various imaging techniques and imaging environments, but the optimal control conditions in imaging techniques and imaging environments are different.

[0003] Patent Document 1 discloses a technique for specifying the positions of dose detection pixels in a region of interest of a radiation image from a radiation projection region, an optical image of a subject, a radiation image captured in the past, and the like.

[0004] Japanese Unexamined Patent Application Publication No. 2021-178119

[0005] When performing imaging with a radiation imaging device using an automatic exposure control function, it is required to easily set the conditions for performing automatic exposure control in various imaging techniques and imaging environments.

[0006] A radiation imaging system according to one aspect of the present disclosure is a radiation imaging system capable of using an AEC function that performs stop control of radiation based on the dose of radiation incident on the radiation imaging device, and includes means for registering setting information of a shooting technique, and means for automatically setting at least one setting related to the AEC function for radiation imaging by the shooting technique based on the setting information, or presenting a candidate for at least one setting related to the AEC function to the user.

[0007] This disclosure provides a radiation imaging technology that allows for easy setting of conditions for automatic exposure control.

[0008] A diagram showing the configuration of the radiation imaging system according to the embodiment. A diagram showing an example of information to be input to the imaging procedure setting unit according to the embodiment. A diagram showing the configuration of the FPD processing unit according to the embodiment. A diagram showing an example of setting the determination conditions when the FPD imaging environment according to the embodiment is stand imaging. A diagram showing an example of setting the determination conditions when the FPD imaging environment according to the embodiment is table imaging. A diagram showing an example of setting the determination conditions when the FPD imaging environment according to the embodiment is cassette imaging. A diagram showing an example of imaging subjects with different body thicknesses when the chest lateral imaging is set as the imaging procedure according to the embodiment. A diagram showing the general processing flow of automatic exposure control according to the embodiment.

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are necessary, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] In the following descriptions of each embodiment, the X-ray imaging device used in this disclosure is described as an X-ray imaging device that captures X-ray image data of a subject using X-rays, which are a type of radiation. Furthermore, the disclosed technology is not limited to this X-ray imaging device, but can also be applied to other radiation imaging devices that capture radiographic images of a subject using other types of radiation (e.g., alpha rays, beta rays, gamma rays, etc.).

[0011] Furthermore, while the explanation will primarily focus on automatic exposure control (AEC), the disclosed technology may be used for radiation dose measurement (monitoring) in AEC, and the imaging device itself does not need to control the radiation. Additionally, the disclosed technology may be used to detect the start of radiation exposure, and further, to detect the end of radiation exposure.

[0012] (First Embodiment) Figure 1 shows an example of the configuration of a radiation imaging system 100 including a radiation imaging device according to the first embodiment. The radiation imaging system 100 is used, for example, when acquiring radiation images in a hospital, and the system configuration includes a radiation imaging device 102 that acquires radiation images based on radiation irradiated from a radiation source 101 (radiation generator), and an imaging control device 103. The imaging control device 103 is connected, for example, by a wired or wireless network or a dedicated line to a radiation control device 104 that controls the radiation imaging device 102 and the radiation source 101, and controls radiation imaging using the radiation imaging device 102 and the radiation source 101.

[0013] In Figure 1, the radiation source 101 holds an X-ray tube and rotor that, for example, accelerate electrons with a high voltage to generate radiation and collide them with the anode. The radiation source 101 irradiates the subject 105 with X-rays.

[0014] The radiation imaging device 102 is a flat panel detector (FPD) in which multiple pixels are arranged in a matrix on a planar substrate, and has an image sensor distributed in two dimensions. The FPD 102 detects the two-dimensional distribution (dose information) of radiation dose that has passed through the subject 105 and reached the image sensor, and generates image data. The FPD 102 transmits the generated image data (radiation image data) to the image processing unit 1034 of the imaging control device 103. The FPD 102 also transmits dose information of the detected two-dimensional distribution of radiation dose and judgment information for controlling radiation irradiation in automatic exposure control to the imaging control device 103.

[0015] The FPD 102 is equipped with detection pixels that have radiation detection elements for monitoring the amount of radiation exposure. The detection pixels are distributed within the FPD 102. The detection region 1021 is located within the FPD 102 and has multiple pixels for generating image data and multiple detection pixels. The amount of radiation exposure is monitored for each detection region, and the representative value of the detection pixels within each detection region is used as the pixel information of the detection pixels. Here, as the pixel information (representative value) of the detection pixels within each detection region, in the following embodiment, the average value of the signal of the detection pixels will be described as an example, but it is not limited to this example. The pixel information (representative value) of the detection pixels may be, for example, the median, mode, integrated value, etc., based on the calculation processing of signals detected by multiple detection pixels. Also, in the following description of each embodiment, the detection regions will be described using examples of five regions and nine regions, but the detection regions are not limited to these examples.

[0016] The imaging control device 103 relays communication between the FPD 102 and the radiation control device 104, and performs radiation irradiation control and other operations on the radiation control device 104. The communication method may be wired or wireless. The imaging control device 103 includes an imaging procedure setting unit 1031, an imaging control unit 1032, a communication control unit 1033, an image processing unit 1034, a display control unit 1035, and a storage unit 1036.

[0017] Each unit configuration of the imaging control device 103 can function according to a computer program. Alternatively, some or all of the functions of the unit configuration of the imaging control device 103 may be realized using dedicated circuits. Communication delays and processing delays between each unit in the imaging control device 103 are managed according to the communication method, communication content, and processing content. Therefore, each unit in the imaging control device 103 can communicate while taking into account communication delays and processing delays.

[0018] Next, the functional configuration of the imaging control device 103 will be described. The imaging procedure setting unit 1031 receives setting information (hereinafter also referred to as imaging procedure setting information) input by the operator via the operation input unit 107, and sets judgment conditions related to automatic exposure control (AEC) operation based on the received setting information (imaging area setting information). The imaging procedure setting unit 1031 transmits the received setting information (imaging procedure setting information) and the set judgment conditions to the imaging control unit 1032 and the FPD 102.

[0019] The imaging control unit 1032 controls the FPD 102 based on the setting information (imaging procedure setting information) received from the imaging procedure setting unit 1031 via the communication control unit 1033, and controls the radiation control device 104 based on the determination conditions related to AEC operation. The specific processing inside the FPD 102 will be described in detail later. The communication control unit 1033 functions as a communication interface for sending and receiving data between the FPD 102 and the radiation control device 104.

[0020] The image processing unit 1034 performs processing on the radiation image data transmitted from the FPD 102, including dark current correction, gain correction, loss correction, gradation processing, and noise reduction processing. The image processing unit 1034 then transmits the processed radiation image data to the display control unit 1035.

[0021] The display control unit 1035 performs display control to display the image information transmitted from the image processing unit 1034 on the display unit 106, such as a monitor. The display unit 106 is composed of any device such as a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display panel, or an organic EL panel, and displays the radiation image data acquired from the image processing unit 1034 after image processing.

[0022] The storage unit 1036 can be configured with storage media including, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an optical disc drive. The storage unit 1036 can store various information acquired from each unit configuration, such as data, information about the subject, imaging techniques used when the subject was previously imaged, imaging environment, imaging conditions, and judgment conditions.

[0023] Next, the AEC operation during subject imaging will be explained in general terms with reference to Figures 1 and 8. Figure 8 is a diagram showing the general processing flow of automatic exposure control according to the embodiment.

[0024] In S801, the operator sets the imaging procedure when installing the FPD 102 via the operation input unit 107 and inputs the setting information (imaging procedure setting information) necessary to set the judgment conditions related to AEC operation to the imaging procedure setting unit 1031. Here, the setting information (imaging procedure setting information) includes information including the imaging area and imaging direction of the subject, and information indicating the characteristics of the installation environment in which the FPD 102 is installed. In addition, the setting information (imaging procedure setting information) includes imaging condition information including the tube voltage, tube current, irradiation time of the FPD 102, and the target dose of radiation irradiated by the FPD 102.

[0025] Figure 2 shows an example of setting information (imaging procedure setting information) to be input to the imaging procedure setting unit 1031. The setting information (imaging procedure setting information) includes, for example, the ID information (identification information) of the FPD 102 to be installed, imaging environment information including the installation environment of the FPD 102, such as stand imaging (standing stand imaging), table imaging (lying down table imaging), cassette imaging, imaging procedure information including the imaging area of ​​the subject and imaging direction, or imaging condition information including tube voltage, tube current, irradiation time, target value (EIt: hereinafter also referred to as target dose).

[0026] In S802, the imaging technique setting unit 1031 sets judgment conditions related to AEC operation based on setting information (imaging technique setting information). Specifically, the imaging technique setting unit 1031 sets judgment conditions such as selection pattern information of detection areas used for controlling radiation irradiation, judgment logic used for controlling radiation irradiation, and threshold information for controlling the signal output to the radiation source 101 so that the radiation source 101 stops at a predetermined dose, based on the characteristics of a specific imaging technique and imaging environment included in this setting information. The imaging technique setting unit 1031 sets judgment logic to be applied to the monitor signal value (output signal) output from the detection area selected based on the selection pattern of detection areas selected from a plurality of detection areas. Based on the judgment logic, a monitor signal value (output signal) for comparison with a threshold can be obtained. The imaging technique setting unit 1031 sets judgment logic (AND, OR, AVE, N / A) to be applied to the output signal output from the detection area selected based on the selection pattern in order to obtain a signal to compare with a threshold.

[0027] In S803, the display control unit 1035 displays (presents) the set judgment conditions on the display unit 106. The judgment conditions can be changed before imaging the subject, for example, they may be changed according to the information of the subject to be imaged. If the judgment conditions set in S802 are changed (S803-YES), the imaging procedure setting unit 1031 proceeds to S804.

[0028] In S804, the operator inputs the parameters to be changed via the operation input unit 107. For example, in the threshold setting shown in Figure 2, sensitivity is a parameter that represents the speed at which exposure stops. When sensitivity is high, exposure stops earlier, i.e., the threshold can be lowered. Also, density is linked to the threshold, and increasing density can be adjusted to raise the threshold. For example, it is possible to change the threshold (EI) setting by adjusting the sensitivity and density parameters. Note that the change in judgment conditions is not limited to changing the threshold; it is also possible to change the detection pattern of the detection area, the ON / OFF switching of the rotation linkage function, the judgment logic settings, etc. The detection pattern of the detection area, the rotation linkage function, and the judgment logic will be described later. The process proceeds to S805 after the parameters are input. Examples of changing settings according to the information of the subject being imaged will be described later in the second and third embodiments.

[0029] If the determination in S803 does not change the determination conditions (S803-NO), the imaging procedure setting unit 1031 proceeds to S805 to determine the final determination conditions. If the parameters are changed in S804 (S803-YES), the final determination conditions are determined based on the changed parameters. If the determination conditions have not been changed (S803-NO), the determination conditions set in S802 are determined as the final determination conditions.

[0030] In S806, radiation irradiation is initiated. When the exposure switch 108 attached to the radiation control device 104 is pressed, the radiation control device 104 controls the radiation source 101 and radiation irradiation is initiated.

[0031] In S807, the determination unit 2003 of the FPD 102 determines whether the cumulative dose of radiation has reached a threshold. If the cumulative dose has not reached the threshold (S807-NO), radiation irradiation continues. On the other hand, in the determination in S807, if the cumulative dose of radiation reaches a predetermined dose after the radiation source 101 has started exposure (S807-YES), determination information (irradiation stop signal) is transmitted from the FPD 102 to the imaging control device 103, and the irradiation stop signal is transmitted from the imaging control device 103 to the radiation control device 104.

[0032] In S808, when the radiation control device 104 receives an irradiation stop signal, it controls the radiation source 101 to stop radiation irradiation from the radiation source 101. Also, if the irradiation time set before subject imaging is reached, the radiation control device 104 stops radiation irradiation from the radiation source 101 regardless of whether or not an irradiation stop signal has been received.

[0033] (Configuration of FPD Processing Unit 200) Next, using Figure 3, the functions related to AEC operation of the radiation imaging device 102 (FPD) will be explained. The FPD processing unit 200 of the radiation imaging device 102 is provided in a pixel area in which a plurality of pixels for detecting radiation are arranged, and processes output signals output from a plurality of detection areas, including detection pixels that output signals corresponding to the radiation exposure amount. The FPD processing unit 200 has a functional configuration consisting of a calculation unit 2001, a determination condition setting unit 2002, a determination unit 2003, and a communication IF unit 2004. Here, the communication IF unit 2004 functions as a communication interface for sending and receiving data with the imaging control device 103.

[0034] The calculation unit 2001 within the FPD processing unit 200 receives dose information representing the two-dimensional distribution of radiation dose (hereinafter referred to as monitor signal value) as an output signal from each detection area (for example, the detection area 1021 in Figure 1), performs calculation processing on the received monitor signal value, and outputs the calculated monitor signal value. Here, the calculated monitor signal value may be, for example, the average value of the monitor signal values ​​of the detection pixels included in each detection area, or the average value of the monitor signal values ​​of a predetermined number of detection pixels selected from among multiple detection pixels included in the detection area. Note that the calculation processing on the monitor signal value is not limited to calculating the average value, and calculation processing may be performed on the monitor signal values ​​(detection pixel signal values) of multiple detection pixels included in the detection area according to an algorithm held in the FPD 102.

[0035] The judgment condition setting unit 2002 sets judgment conditions for controlling radiation irradiation, including a threshold value for dose information (monitor signal value) that indicates a representative value for each detection area, a detection area selection pattern selected from multiple detection areas, and a judgment logic to be applied to the monitor signal value (output signal) output from the detection area selected based on the selection pattern. Based on the judgment logic, a monitor signal value (output signal) can be acquired for comparison with the threshold value. The judgment condition setting unit 2002 sets a judgment logic to be applied to the output signal output from the detection area selected based on the selection pattern in order to acquire a signal to be compared with the threshold value. The judgment conditions (threshold value, detection area selection pattern, judgment logic) set in the judgment condition setting unit 2002 are set by the imaging procedure setting unit 1031 of the imaging control device 103 via the communication IF unit 2004. That is, the judgment conditions (threshold value, detection area selection pattern, judgment logic) set in the judgment condition setting unit 2002 are set by the imaging procedure setting unit 1031 of the imaging control device 103 and are set based on the judgment conditions acquired via the communication IF unit 2004. The judgment conditions set here (threshold, detection area selection pattern, judgment logic) are information used in AEC operation to determine whether the dose of irradiated radiation has reached the cumulative dose.

[0036] The determination unit 2003 determines whether the irradiation dose has reached a predetermined cumulative dose based on the result of comparing the signal obtained by applying a determination logic (AND, OR, AVE, N / A) to the monitor signal value output from the detection area (for example, A and B in Figure 4) selected according to the selection pattern of the determination conditions with a threshold, and generates determination information for controlling radiation irradiation. Here, the determination information becomes information (irradiation control information) for controlling radiation irradiation (continuing irradiation or stopping irradiation) in AEC. The determination information generated by the determination unit 2003 is transmitted to the imaging control unit 1032 via the communication IF unit 2004.

[0037] Before the irradiation time set in advance of imaging the subject is reached, if the monitor signal value is below a threshold, the determination information becomes information instructing the continuation of radiation irradiation (irradiation continuation signal). If the monitor signal value is above the threshold, the determination information becomes information instructing the cessation of radiation irradiation (irradiation stop signal). If the irradiation time set in advance of imaging the subject is reached, the radiation control device 104 stops the radiation irradiation from the radiation source 101 regardless of whether or not there is an irradiation stop signal.

[0038] If there are multiple detection areas selected by the imaging procedure setting unit 1031, the determination unit 2003 compares a threshold value with multiple monitor signal values ​​based on a determination method (AND condition, OR condition, AVG condition, etc.) expressed by the determination logic set by the imaging procedure setting unit 1031 to determine whether the irradiation dose has reached a predetermined cumulative dose.

[0039] When performing a determination process using an AND condition (logical AND), the determination unit 2003 determines whether the monitor signal values ​​of all multiple detection areas are above the threshold using the AND condition (logical AND). If the monitor signal values ​​of all multiple detection areas are above the threshold, it generates and outputs determination information (irradiation stop signal) to stop radiation irradiation. For example, if the monitor signal value of the detection area with the lowest monitor signal value among multiple detection areas is above the threshold, an irradiation stop signal is generated and output. In a determination process based on an AND condition (logical AND), radiation imaging can be performed without dose deficiency in all of the multiple detection areas.

[0040] Alternatively, when performing a determination process using an OR condition (logical OR), the determination unit 2003 determines, using an OR condition (logical OR), whether any of the monitor signal values ​​of multiple detection areas are above a threshold. If the monitor signal value of any of the detection areas is above the threshold, it generates and outputs determination information (irradiation stop signal) to stop radiation irradiation. For example, if the monitor signal value of the detection area with the highest monitor signal value among multiple detection areas is above the threshold, an irradiation stop signal is generated and output. Determination processing based on an OR condition (logical OR) allows for radiation imaging that suppresses excessive radiation exposure.

[0041] Also, when performing the determination process under the AVG condition (averaging), the determination unit 2003 determines whether the monitored signal value obtained by averaging the monitored signal values of a plurality of detection regions is greater than or equal to a threshold value under the AVG condition (averaging). When the averaged monitored signal value is greater than or equal to the threshold value, the determination unit 2003 generates and outputs determination information (irradiation stop signal) for stopping the irradiation of radiation.

[0042] In FIG. 3, the functional configuration of the FPD processing unit 200 provided on the FPD 102 side and the configuration in which the FPD 102 side executes the determination condition for automatic exposure control (AEC) have been described. However, the present invention is not limited to this configuration, and the functional configuration of the FPD processing unit 200 may be provided in the imaging control device 103, and the imaging control device 103 side may execute the determination condition for AEC. In this case, the monitored signal value of each detection region may be transmitted from the FPD 102 to the imaging control device 103 via the communication IF unit 2004, and based on the received monitored signal value, the imaging control unit 10,32 of the imaging control device 103 may execute the process related to the determination condition for AEC.

[0043] Next, a method for setting, by the imaging technique setting unit 1031, the determination condition related to the AEC operation based on the setting information (imaging technique setting information) in the imaging control device 103 according to the first embodiment will be described.

[0044] (Example of stand imaging) FIG. 4 is a diagram showing an example of setting the determination condition when the imaging environment of the FPD 102 is stand imaging. Here, the stand (standing stand) used in stand imaging is a gantry capable of imaging a radiation image in a standing position with the FPD 102 mounted, and the FPD 102 is detachable from the standing stand. As a feature of stand imaging, in stand imaging with the FPD 102 mounted on the standing stand, the FPD 102 is mounted vertically along the direction in which the standing stand is erected.

[0045] In the example of FIG. 4, the front view of the chest is set as the setting information, and the stand (standing stand) is set as the FPD installation environment of the imaging environment information. Also, as an example of the imaging conditions, the tube voltage (125 kV), tube current (320 mA), irradiation time (5 ms), and target dose (EIt: 200) are set.

[0046] As an example of setting the determination conditions, in the example shown in FIG. 4, for the detection area 1021, examples of five detection areas A to E will be used for explanation. Identification information (for example, A to E) is set for a plurality of detection areas, and based on the identification information, each detection area can be identified. In the five exemplary detection areas A to E, the detection areas A and B are provided on the upper side (upper stage side) of the paper surface. The detection areas D and E are provided on the lower side (lower stage side) of the paper surface compared to the positions of the detection areas A and B within the detection surface of the FPD 102. The vertical position of the detection area C is provided between the positions of the detection areas A and B and the positions of the detection areas D and E (central part) within the detection surface of the FPD 102. Also, the horizontal position of the detection area C is provided between the positions of the detection areas A and D and the positions of the detection areas B and E (central part) within the detection surface of the FPD 102.

[0047] When the region of interest images the lung field (front of the chest), based on the imaging technique and the imaging environment, it is desirable to select, as the detection area, the upper two detection areas A and B provided on the upper side (upper stage side) of the paper surface among the five detection areas A to E shown in FIG. 4.

[0048] In addition, the imaging technique setting unit 1031 has a rotation interlocking function for selecting a detection area (selection pattern of the detection area) in conjunction with the rotation direction of the FPD 102. Here, the rotation interlocking function refers to a function for selecting a detection area based on the determination result of the rotation direction of the FPD 102. The imaging technique setting unit 1031 can set the rotation interlocking function to be effective (ON), set the rotation interlocking function to be ineffective (OFF), or switch the ON / OFF setting of the rotation interlocking function based on the setting of the installation environment (stand, table, cassette, etc.) of the FPD 102.

[0049] The imaging technique setting unit 1031 sets a selection pattern for the detection area in conjunction with the rotation direction when it determines that the installation environment allows for the use of the rotation direction of the FPD 102, and does not set a selection pattern in conjunction with the rotation direction when it determines that the installation environment does not allow for the use of the rotation direction of the FPD 102. For example, if the installation environment is a stand, the rotation linkage function may be set to enabled (ON), and if the installation environment is a table or cassette, the rotation linkage function may be set to disabled (OFF). When the rotation linkage function is enabled (ON), the detection area is selected based on the set imaging technique (imaging area, imaging direction) and the orientation (rotation direction) of the FPD 102.

[0050] The imaging procedure setting unit 1031 acquires angular position information indicating the rotation direction in the installation environment based on the detection result of the detection unit of the FPD 102, and sets a selection pattern for the detection area based on the angular position information. If angular position information can be obtained from the detection result of a detection unit such as a gravity sensor mounted inside the FPD 102, the imaging procedure setting unit 1031 can determine the rotation direction of the FPD 102 when it is mounted on a standing stand, and therefore it is also possible to set the detection area in conjunction with the rotation direction of the FPD 102.

[0051] When the detection area is set to the two upper detection areas A and B, which correspond to the lung field, the judgment logic should preferably be an OR condition (logical disjunction) to suppress excessive radiation exposure. Also, when the target dose EIt value set in the imaging condition information is 200, the lung field area has a higher transmittance than the entire subject, so the threshold EI for controlling radiation exposure should be set higher than the target dose (EIt: 200), for example, threshold EI 300.

[0052] When the determination conditions shown in Figure 4 are set, the determination unit 2003 compares the monitor signal value of the detection area (A, B) selected by the determination conditions with the threshold value according to the determination logic (OR) to determine whether the irradiation dose has reached a predetermined cumulative dose. For example, as shown in Figure 4, if the irradiation dose (EI value) reached in detection areas A and B is 300, the irradiation dose (EI value) reached in detection area C is 100, and the irradiation dose (EI value) reached in detection areas D and E is 150, the determination unit 2003 can generate an irradiation control signal to control radiation irradiation based on the result of comparing the irradiation dose (EI value) of the detection area A or detection area B selected by the determination conditions with the threshold setting (EI value: 300).

[0053] In this way, by inputting the imaging procedure settings (imaging procedure: frontal chest, imaging environment: stand imaging, imaging conditions), it is possible to set the detection area selection pattern, judgment logic, and threshold as judgment conditions related to AEC operation.

[0054] (Example of Table Imaging) Figure 5 shows an example of setting the determination conditions when the imaging environment for the FPD 102 is table imaging. Here, the table used for table imaging (supine table) is a stand that allows for the acquisition of radiographic images in a supine position with the FPD 102 attached. The FPD 102 is detachable from the supine table. In table imaging with the FPD 102 attached to the supine table, a characteristic feature is that the FPD 102 is mounted horizontally along the direction in which the supine table extends.

[0055] In the example shown in Figure 5, the frontal chest is set as the imaging site, and a table (supine table) is set as the FPD installation environment. As an example of imaging conditions, tube voltage (95kV), tube current (200mA), irradiation time (10ms), and target dose (EIt:200) are set. As an example of setting the judgment conditions shown in Figure 5, we will explain using an example of multiple detection areas (five detection areas A to E), similar to the example in Figure 4.

[0056] Since the rotation direction of the FPD 102 cannot be determined when it is mounted horizontally on a supine table, it is desirable to disable (turn OFF) the rotation linkage function, which selects the detection area in conjunction with the rotation direction of the FPD 102.

[0057] In imaging environments (FPD installation environments) where it is difficult to determine the orientation (direction of rotation) of the FPD 102, it is necessary to be able to control the selection of the detection area regardless of the orientation of the FPD 102. For this reason, in imaging environments (FPD installation environments) where it is difficult to determine the orientation (direction of rotation) of the FPD 102, it is desirable to set the detection area to one detection area (for example, detection area C) located in the center of a plurality of detection areas provided within the detection surface of the FPD 102.

[0058] If the detection area used as the AEC determination criterion is set to a single detection area located in the center, then it is only necessary to control radiation irradiation using the detection result in that single detection area, and therefore there is no need to set up a determination logic. In Figure 5, N / A is set to indicate that there is no need to set up a determination logic.

[0059] Furthermore, when the target dose EIt value set in the imaging condition information is 200, the central longitudinal stagnation region of the FPD 102 has lower transmittance than the entire subject. Therefore, the threshold EI used to control radiation irradiation needs to be set lower than the target dose (EIt: 200), for example, as threshold EI 100.

[0060] When the determination conditions shown in Figure 5 are set, the determination unit 2003 compares the monitor signal value of the detection area (C) selected by the determination conditions with the threshold value according to the determination logic (N / A) to determine whether the irradiation dose has reached a predetermined cumulative dose. For example, as shown in Figure 5, even if the irradiation dose (EI value) that reaches detection areas A and B is an irradiation dose of 300 that exceeds the threshold setting (EI value: 100), and the irradiation dose (EI value) that reaches detection areas D and E is a dose index of 150 that exceeds the threshold setting (EI value: 100), the determination unit 2003 can generate an irradiation control signal to control radiation irradiation based on the result of comparing the irradiation dose (EI value: 100) that reaches detection area C selected by the determination conditions with the threshold setting (EI value: 100).

[0061] In this way, by inputting the imaging procedure settings (imaging procedure: frontal chest, imaging environment: table imaging, imaging conditions), it is possible to set the detection area selection pattern, judgment logic, and threshold as judgment conditions related to AEC operation.

[0062] (Example of Cassette Imaging) Figure 6 shows an example of setting the determination conditions when the imaging environment of the FPD 102 is cassette imaging. Cassette imaging is an imaging method in which imaging is performed using the FPD 102 alone, and in cassette imaging, the position and orientation (direction of rotation) of the FPD 102 can be freely set for imaging. One of the features of cassette imaging with the FPD 102 alone is that the position and orientation (direction of rotation) of the FPD 102 relative to the subject 105 can be freely set.

[0063] In the example shown in Figure 6, the frontal chest is set as the imaging site, and a cassette is set as the FPD installation environment. As an example of imaging conditions, the tube voltage (80kV), tube current (160mA), irradiation time (12.5ms), and target dose (EIt: 200) are set. As an example of setting the judgment conditions shown in Figure 6, we will explain using an example of multiple detection areas (five detection areas A to E), similar to the example in Figure 4.

[0064] In cassette imaging, if the FPD 102 is installed horizontally, it is not possible to determine the orientation (direction of rotation) of the FPD 102. Therefore, when cassette imaging is set as the installation environment for the FPD 102, it is desirable to disable (turn off) the rotation linkage function, which selects the detection area in conjunction with the rotation direction of the FPD 102.

[0065] In imaging environments (FPD installation environments) where it is difficult to determine the orientation (direction of rotation) of the FPD 102 and the subject position cannot be fixed each time, it is necessary to be able to control the selection of the detection area regardless of the orientation of the FPD 102 or the subject position. For this reason, in imaging environments (FPD installation environments) where the orientation (direction of rotation) of the FPD 102 cannot be determined and the subject position cannot be fixed, it is desirable to set the detection area to select all detection areas (for example, detection areas A to E) from among the multiple detection areas provided within the detection surface of the FPD 102 so that as many detection areas as possible are located within the subject.

[0066] When multiple detection areas are set as the detection area used as the AEC judgment condition, it is desirable to set the judgment logic to AVE (averaging condition) because the radiation irradiation can be controlled using the average value of the detection results in all detection areas, thereby bringing the entire subject closer to the threshold EI value.

[0067] When the judgment conditions shown in Figure 6 are set, the judgment unit 2003 compares the monitor signal values ​​of the detection areas (A to E) selected by the judgment conditions with the threshold value according to the judgment logic (AVE) to determine whether the irradiation dose has reached a predetermined cumulative dose. For example, as shown in Figure 6, if the irradiation dose (EI value) reached in detection areas A and B is 300, the irradiation dose (EI value) reached in detection area C is 100, and the irradiation dose (EI value) reached in detection areas D and E is 150, the average value of the irradiation doses (EI values) of the multiple detection areas A to E will be an EI value of 200. Based on the result of comparing the average value (EI value: 200) of the irradiation doses reached in the detection areas (A to E) selected by the judgment conditions with the threshold value (EI value: 200), the judgment unit 2003 can generate an irradiation control signal to control the irradiation of radiation.

[0068] When the target dose EIt value set in the imaging condition information is 200, the threshold EI for controlling radiation irradiation should be set to 200, the same as the target dose EIt value. In this way, by inputting the imaging procedure settings (imaging procedure: frontal chest, imaging environment: cassette imaging, imaging conditions), the selection pattern of the detection area, the judgment logic, and the threshold can be set as judgment conditions related to AEC operation.

[0069] (Second Embodiment) In the second embodiment, a method for changing the determination conditions according to the information of the subject to be imaged will be described. The subject information includes body size information, including the body thickness of the subject. If the imaging technique setting unit 1031 determines that the body size information indicates a body that is thinner than the standard subject thickness, it may change the detection area selection pattern, determination logic, and threshold, which are set in advance based on the imaging technique and imaging environment. For example, the imaging technique setting unit 1031 may change the selection pattern so that the area in which radiation reaches the FPD 102 without passing through the subject (pass-through area) is not included in the detection pattern of the detection area. If the selection pattern is changed, the imaging technique setting unit 1031 may change the determination logic and threshold based on the changed selection pattern.

[0070] Alternatively, the subject information may include information indicating metallic regions within the subject's body, and the imaging technique setting unit 1031 may change the detection pattern settings so that metallic regions are not included in the detection pattern of the detection region when metallic regions are present within the subject's body. If the selected pattern is changed, the imaging technique setting unit 1031 may change the judgment logic or threshold based on the changed selected pattern.

[0071] As an example, in addition to the imaging area and imaging direction, subject information (for example, body size information including the subject's age, sex, height, weight, body width, and body thickness) may be added as imaging procedure information. Based on the information stored in the memory unit 1036, the imaging procedure setting unit 1031 can obtain reference body size information indicating the standard body size range of the subject from the subject information such as the subject's age, sex, height, and weight. The imaging procedure setting unit 1031 compares the reference body size information with the subject's body size information included in the subject information and determines that the subject thickness is standard if the subject's body size information is within the body size range of the reference body size information. Furthermore, if the subject's body size information exceeds the upper limit of the body size range of the reference body size information, the imaging procedure setting unit 1031 determines that the subject has a thicker body than the standard subject thickness. Furthermore, if the subject's body size information falls below the lower limit of the body size range of the reference body size information, the imaging procedure setting unit 1031 determines that the subject has a thinner body than the standard subject thickness.

[0072] If the subject's physique information determines that the subject is thinner than the standard subject thickness, a pass-through region may occur where the radiation does not penetrate the subject 105 but instead directly enters the detection region 1021 of the FPD 102. When the subject's physique information indicates that the subject is thinner than the standard subject thickness, the imaging procedure setting unit 1031 may change the detection region selection pattern and determination logic that can be selected when the subject's physique information is standard, so that the AEC operation is not affected by the occurrence of the pass-through region. The imaging procedure setting unit 1031 may also change the determination logic and threshold based on the changed selection pattern.

[0073] Figure 7 shows an example of imaging subjects with different body thicknesses when the chest lateral imaging technique is set. The detection area shown in Figure 7 is the same as in the example in Figure 4, and the explanation will use examples of multiple detection areas (five detection areas A to E). The installation environment of the FPD 102 is shown as an example of a stand (standing stand). The left diagram of Figure 7 (7A) is an example of imaging when the subject thickness is standard, and all detection areas A to E are contained within the subject area, so it is desirable to select all detection areas A to E in AEC operation, set the judgment logic to AVE (averaging condition), and set the threshold to the same as the target dose.

[0074] On the other hand, the right-hand diagram of Figure 7 (7B) illustrates imaging when the subject thickness is thin, and not all detection areas A to E are contained within the subject area. If imaging is performed using the settings for a standard subject thickness, radiation will directly enter detection areas A and D, potentially leading to insufficient dose due to the threshold being reached too quickly. Therefore, insufficient dose can be avoided by excluding detection areas A and D, which may be areas where the detection is missed, and changing the selection pattern of detection areas to detection areas B, C, and E, which are contained within the subject thickness, or by setting the judgment logic to AND (logical conjunction), or by setting the threshold higher than the target dose. In this way, the settings related to AEC operation can be changed to match the characteristics (body size information) of the subject being imaged.

[0075] According to this embodiment, it is possible to provide a radiation imaging technology that allows for easy setting of conditions for automatic exposure control.

[0076] (Third Embodiment) It is also possible to obtain information indicating the characteristics of the subject to be imaged from images of the same subject that have been imaged in the past. For example, the imaging procedure setting unit 1031 may obtain information related to the radiation transmission of the subject, such as the thickness of the subject and the presence or absence of metal regions inside the subject's body, from information linked to previously imaged images, or it may reflect past judgment conditions (selection pattern of detection area, judgment logic, threshold setting (sensitivity, density)) from past imaging in the setting of judgment conditions.

[0077] For example, the storage unit 1036 may store past judgment conditions that were finally decided during past imaging of a subject (patient) acquired from an external server via a network, as well as information linked to previously captured images. The storage unit 1036 may be configured to retrieve past judgment conditions and information linked to previously captured images based on identification information (patient ID) set for each subject. Furthermore, when imaging a subject to be imaged, the judgment conditions may be set by reflecting information on past judgment conditions (light field selection, judgment logic, threshold (sensitivity, density)) determined during past imaging based on the subject's identification information (patient ID) in the settings related to AEC operation.

[0078] The imaging procedure setting unit 1031 may, based on subject identification information (e.g., patient ID) as subject information, determine that the subject's physique is thinner than the standard subject thickness based on the physique information linked to images of the same subject previously acquired. In such cases, the imaging procedure setting unit 1031 may change the detection pattern of the detection area, which is pre-set based on the imaging procedure and imaging environment. For example, the imaging procedure setting unit 1031 may change the selection pattern so that areas where radiation reaches the FPD 102 without passing through the subject (pass-through areas) are not included in the detection pattern of the detection area. If the selection pattern is changed, the imaging procedure setting unit 1031 may change the determination logic and threshold based on the changed selection pattern.

[0079] Furthermore, the imaging technique setting unit 1031 may, based on the subject identification information and information linked to previously captured images of the same subject, determine that a metallic region is present within the subject's body, and if it determines this, change the detection area selection pattern, determination logic, and threshold, which are pre-set based on the imaging technique and imaging environment. For example, the imaging technique setting unit 1031 may change the selection pattern so that metallic regions contained within the subject's body are not included in the detection pattern of the detection area. If the selection pattern is changed, the imaging technique setting unit 1031 may change the determination logic and threshold based on the changed selection pattern.

[0080] According to this embodiment, it is possible to provide a radiation imaging technology that allows for easy setting of conditions for automatic exposure control.

[0081] [Other Embodiments] The disclosed technology can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more functions.

[0082] The technical ideas derived from this disclosure are not limited to the exemplary embodiments disclosed, but are intended to encompass various modifications of the exemplary embodiments, or substitutions with equivalent structures or functions. The scope of the following claims should be interpreted in the broadest way to encompass all such modifications and equivalent structures and functions.

[0083] This application claims priority based on Japanese Patent Application No. 2024-162453, filed on September 19, 2024, and all of its contents are incorporated herein by reference.

[0084] 100: Radiation imaging system, 102: Radiation imaging device (FPD), 103: Imaging control device, 200: FPD processing unit, 1021: Detection area, 1031: Imaging procedure setting unit, 1032: Imaging control unit

Claims

1. A radiation imaging system that can utilize an AEC function that controls the stopping of radiation based on the dose of radiation incident on a radiation imaging device, comprising: means for registering setting information for an imaging procedure; and means for automatically setting at least one setting for the AEC function for radiation imaging by the imaging procedure based on the setting information, or for presenting the user with at least one candidate setting for the AEC function.

2. The radiation imaging system comprises a radiation imaging device that generates an image based on the radiation, having a plurality of detection regions provided in a pixel region in which a plurality of pixels for detecting radiation irradiated from a radiation generator are arranged, and including a detection pixel that outputs a signal corresponding to the amount of radiation irradiated; and an imaging control device that communicates with the radiation generator and the radiation imaging device and controls radiation imaging, wherein the imaging control device includes setting means for setting, according to input setting information, a selection pattern of the detection regions, a threshold for the radiation dose, and a determination logic to be applied to an output signal output from the detection region selected based on the selection pattern in order to acquire a signal to be compared with the threshold, as determination conditions for controlling the irradiation of the radiation, and the radiation imaging device includes determination means for generating determination information for controlling the irradiation of the radiation based on the result of comparing a signal obtained by applying the determination logic to the output signal output from the detection region selected according to the selection pattern with the threshold.

3. The radiation imaging system according to claim 2, characterized in that the setting information includes information including the imaging area and imaging direction of the subject, and information indicating the installation environment in which the radiation imaging device is installed.

4. The radiation imaging system according to claim 3, characterized in that the setting information includes imaging conditions including the tube voltage, tube current, irradiation time of the radiation generator, and the target dose of the radiation irradiated by the radiation generator.

5. The radiation imaging system according to claim 4, characterized in that the setting means sets the selection pattern of the detection area, the determination logic, and the threshold based on the imaging area, the imaging direction, the installation environment, and the imaging conditions.

6. The radiation imaging system according to claim 5, characterized in that the setting means sets the selection pattern of the detection area in conjunction with the rotation direction when it is determined that the installation environment is an installation environment in which the rotation direction of the radiation imaging device can be utilized.

7. The radiation imaging system according to claim 6, characterized in that the setting means acquires angular position information indicating the direction of rotation in the installation environment based on the detection result of the detection means of the radiation imaging device, and the setting means sets a selection pattern of the detection area based on the angular position information.

8. The radiation imaging system according to claim 5, characterized in that the setting means does not set the selection pattern linked to the rotation direction when it is determined that the installation environment is an installation environment in which the rotation direction of the radiation imaging device cannot be utilized.

9. The radiation imaging system according to claim 2, further comprising a display control means for displaying the determination conditions set by the setting means on a display means, wherein the setting means changes the determination conditions displayed on the display means based on input from an input means.

10. The radiation imaging system according to claim 2, characterized in that the setting means changes the determination conditions set based on the setting information based on the subject information.

11. The radiation imaging system according to claim 10, wherein the subject information includes body size information including the body thickness of the subject, and the setting means determines that the body size information indicates a body size that is thinner than a standard subject thickness, and changes the setting of the detection pattern so that the region in which the radiation reaches the radiation imaging device without passing through the subject is not included in the detection pattern of the detection region.

12. The radiation imaging system according to claim 10, wherein the subject information includes information indicating a metallic region within the subject's body, and the setting means changes the setting of the detection pattern so that the metallic region is not included in the detection pattern of the detection region when the subject's body contains the metallic region.

13. The radiation imaging system according to claim 10, characterized in that, as information about the subject, if the setting means determines that the body size information, including the body thickness of the subject linked to an image of the same subject previously captured, is thinner than the standard subject thickness, the setting means changes the setting of the detection pattern so that the region in which the radiation reaches the radiation imaging device without passing through the subject is not included in the detection pattern of the detection region.

14. The radiation imaging system according to 12, characterized in that the setting means, based on the identification information of the subject, determines that a metallic region is included in the body of the subject, and based on information linked to images of the same subject previously captured, changes the setting of the detection pattern so that the metallic region is not included in the detection pattern of the detection region.

15. The radiation imaging system according to claim 11, characterized in that the setting means changes the determination logic or the threshold setting based on the change in the detection pattern.

16. The radiation imaging system according to claim 2, characterized in that the setting means sets the determination conditions using past determination conditions that were set when capturing an image of the same subject that was captured in the past, based on the identification information of the subject.

17. The determination logic includes a logical OR condition for determining whether any of the signal values ​​of the plurality of detection regions selected by the selection pattern is greater than or equal to the threshold; a logical AND condition for determining whether all of the signal values ​​of the plurality of detection regions selected by the selection pattern are greater than or equal to the threshold; and an averaging condition for determining whether the signal value obtained by averaging the signal values ​​of the plurality of detection regions selected by the selection pattern is greater than or equal to the threshold, wherein the determination means applies one of the logical OR condition, the logical AND condition, and the averaging condition to the output signal output from the detection region, as the determination logic, in the case of the radiation imaging system according to claim 2.

18. The radiation imaging system according to claim 2, characterized in that when the setting means sets one of the plurality of detection areas as the selection pattern of the detection area, it does not set the judgment logic among the judgment conditions.

19. An imaging control device for a radiation imaging system that can utilize an AEC function that controls the stopping of radiation based on the dose of radiation incident on a radiation imaging device, comprising: means for registering setting information for an imaging procedure; and means for automatically setting at least one setting for the AEC function for radiation imaging by the imaging procedure based on the setting information, or for presenting the user with at least one candidate setting for the AEC function.

20. A control method for an imaging control device of a radiation imaging system that can utilize an AEC function that controls the stopping of radiation based on the dose of radiation incident on the radiation imaging device, the control method comprising: a step of registering setting information for the imaging procedure; a step of automatically setting at least one setting for the AEC function for radiation imaging by the imaging procedure based on the setting information, or a step of presenting the user with at least one candidate setting for the AEC function.

21. A program that causes a computer to execute the control method described in claim 20.

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