Radiography system, radiation imaging method, and program

Abstract

This invention provides a radiography system that allows the operator to appropriately determine whether the required dose is being applied to the light-gathering field during radiography using automatic exposure control. [Solution] The radiography system according to the present invention includes a radiation generating device that irradiates radiation, a radiography device that generates a radiographic image based on the radiation, and a control device that communicates with the radiography device and receives the radiographic image and controls its operation, and is characterized by comprising an acquisition means for acquiring a radiographic image obtained based on the radiation, and a calculation means for calculating a plurality of dose index values ​​from the radiographic image.

Description

Technical Field

[0001] The present invention relates to a radiation imaging system, a radiation imaging method, and a program.

Background Art

[0002] As a radiation imaging device used for medical image diagnosis or non-destructive inspection by radiation such as X-rays, a radiation imaging device having a matrix substrate having a pixel array in which a switch such as a TFT (thin film transistor) and a conversion element such as a photoelectric conversion element are combined has been put into practical use.

[0003] In recent years, the multifunctionalization of radiation imaging devices has been studied. As one of them, it has been studied to incorporate a function of monitoring the irradiation of radiation. With this function, for example, it becomes possible to detect the timing when the irradiation of radiation from the radiation source is started, the timing when the irradiation of radiation should be stopped, and the irradiation amount or integrated irradiation amount of radiation.

[0004] Patent Document 1 discloses a radiation imaging system including a radiation imaging device having a pixel for monitoring the irradiation of radiation, a radiation source, and an imaging control device. When the radiation imaging system detects the timing to stop the irradiation, an irradiation stop signal is transmitted from the radiation imaging device to the radiation generation device. In Patent Document 1, although there is no disclosure of a specific control signal, the existing radiation exposure control is input to the exposure control part inside the radiation generation device as an analog signal from a radiation receiving part such as an ionization chamber or a phototimer. Then, automatic exposure control (AEC) is performed by detecting that the integrated value such as analog signal integration exceeds a predetermined threshold value and stopping the radiation, thereby performing dose control.

[0005] On the other hand, after imaging, the radiation image is analyzed to calculate a dose index value obtained by quantifying the dose of radiation received by the radiation image detection device on the GUI.

[0006] One example of a dose index is the Exposure Index (EI). Dose indices are values ​​used to evaluate the dose used in radiography. EI is an index standardized by the International Electrotechnical Commission (IEC) as IEC62494-1. Specifically, a region within the radiographic image is defined for calculating the EI value, and a representative value is extracted from the pixel values ​​of the pixels in that region. This extracted representative value is then transformed and displayed as a dose index value. Medical facilities manage EI information and independently set a target value, EIt (Target Exposure Index), which represents the optimal dose for radiographic images (for example, good image quality and minimum dose). The deviation DI (Deviation Index) between the calculated EI value and EIt is then used to recognize dose deficiencies or excesses, helping to ensure optimal imaging. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 4217505 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] For example, when using automatic exposure control (AEC) for lung imaging, it is common practice to set the light-gathering field for both lungs and perform radiography. In this case, radiation exposure can be reduced by stopping the radiation when the optimal dose is reached in both lungs. Therefore, it is desirable that the EI value and target EIt value be displayed or set based on the light-gathering field.

[0009] However, with the current equipment, the EI value is displayed as a dose index for the entire radiation image, and a target value EIt is set, making it impossible to determine from the numerical value whether the dose required for the light-gathering field of automatic exposure control is being applied.

[0010] This invention has been made in view of the above problems, and one of its objectives is to provide a radiography system that allows the operator to appropriately determine whether the required dose is applied to the light-gathering field in radiography using automatic exposure control.

[0011] Furthermore, not limited to the aforementioned objectives, the effects and benefits derived from each configuration shown in the embodiments for carrying out the invention described later, which cannot be obtained by conventional art, can also be considered as another objective of the disclosure in this specification. [Means for solving the problem]

[0012] The radiography system according to the present invention includes a radiation generating device that irradiates radiation, a radiography device that generates a radiographic image based on the radiation, and a control device that communicates with the radiography device and receives the radiographic image and controls its operation, and is characterized by comprising an acquisition means for acquiring a radiographic image obtained based on the radiation, and a calculation means for calculating a plurality of dose index values ​​from the radiographic image. [Effects of the Invention]

[0013] According to the present invention, in radiography using automatic exposure control, the operator can appropriately determine whether the required dose is applied to the light-gathering field. [Brief explanation of the drawing]

[0014] [Figure 1] A diagram showing an example of a radiography system. [Figure 2] A diagram showing an example of a radiography apparatus. [Figure 3] A diagram showing an example of the arrangement of the light-gathering field and the shooting area. [Figure 4] A diagram showing an example of the arrangement of the light-gathering field and the shooting area. [Figure 5] A diagram showing an example of a control unit for the imaging device within a radiography apparatus. [Figure 6] A diagram showing an example of a control device within a radiography system. [Figure 7]Figure showing an example of a flowchart for calculating EI value [Figure 8] Figure showing an example of a method for displaying a dose index [Figure 9] Figure showing an example of a method for displaying a dose index [Figure 10] Figure showing an example of the operation of a radiation imaging system [Figure 11] Figure showing an example of a method for displaying a dose index [Figure 12] Figure showing an example of a method for displaying a dose index [Figure 13] Figure showing an example of a method for displaying a dose index [Figure 14] Figure showing an example of the operation of a radiation imaging system

Mode for Carrying Out the Invention

[0015] [Embodiment] [First Embodiment] Hereinafter, a radiation imaging system according to an embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a radiation imaging system according to the embodiment.

[0016] As shown in FIG. 1, the radiation imaging system 10 is provided in a radiation room 1 that performs radiation imaging by radiation irradiation and a control room 2 installed near the radiation room 1.

[0017] The radiation room 1 includes, as the radiation imaging system 10, a radiation imaging device 300, a standing stand 302, a first communication cable 307, an access point (AP) 320, a communication control device 323, a radiation generation device 324, a radiation source 325, a second communication cable 326, and a third communication cable 327.

[0018] The control room 2 includes, as the radiation imaging system 10, a control device 310, an irradiation switch 311, an input device 313, a display device 314, an in-hospital LAN 315, and a fourth communication cable 316.

[0019] The configuration of each device installed in the radiology room 1 and the control room 2 is not limited to the above; any configuration that functions as a radiography system 10 is acceptable.

[0020] The radiography apparatus 300 comprises a power control unit 301 consisting of a battery or the like, a wired communication unit 303, and a wireless communication unit 304. The radiography apparatus 300 detects radiation that has passed through the subject 306 and generates a radiographic image. In this embodiment, the image includes not only the state displayed on the display unit but also the state in which it is stored as image data in the database or storage unit.

[0021] The wired communication unit 303 enables the exchange of information, for example, through a cable connection using a communication standard with a predetermined agreement, or a standard such as Ethernet (registered trademark).

[0022] The wireless communication unit 304 is composed of a circuit board equipped with, for example, an antenna and a communication IC (Integrated Circuit). The circuit board equipped with the communication IC performs communication processing of a protocol based on wireless LAN via the antenna. There are no particular limitations on the frequency band, standards, or methods of wireless communication in wireless communication, and proximity wireless methods such as NFC (Near Field Communication), Bluetooth (registered trademark), or UWB (Ultra Wide Band) may be used. Furthermore, the wireless communication unit may have multiple wireless communication methods and select them as appropriate for communication.

[0023] The standing stand 302 is a mount that allows for radiographic imaging in a standing position by attaching the radiography device 300. The radiography device 300 can be attached to and detached from the standing stand 302, and imaging can be performed both when the device is attached and when it is detached.

[0024] The first communication cable 307 is a cable for connecting the radiography apparatus 300 and the communication control device 323.

[0025] The access point 320 communicates wirelessly with the radiography apparatus 300. For example, when the radiography apparatus 300 is removed from the standing stand 302 for use, the access point 320 is used to relay communication between the radiography apparatus 300, the control device 310, and the radiation generator 324. Figure 1 shows an example of communication via the access point 320, but either the radiography apparatus 300 or the communication control device 323 can act as an access point and communicate directly without going through the access point 320.

[0026] The communication control device 323 controls the access point 320, the radiation generator 324, and the control device 310 to enable them to communicate with each other.

[0027] The radiation generator 324 controls the radiation source 325 to irradiate radiation based on predetermined irradiation conditions.

[0028] The radiation source 325 irradiates the subject 306 with radiation according to the control of the radiation generator 324.

[0029] The second communication cable 326 is a cable for connecting the access point 320 and the communication control device 323.

[0030] The third communication cable 327 is a cable for connecting the radiation generator 324 and the communication control device 323.

[0031] The control device 310 communicates with the radiation generator 324 and the radiography device 300 via the communication control device 323, and provides overall control of the radiography system 10.

[0032] The irradiation switch 311 receives input for the timing of radiation irradiation through the operation of the operator 312.

[0033] The input device 313 is a device that receives instructions from the operator 312, and various input devices such as keyboards and touch panels are used.

[0034] The display device 314 is a device that displays image-processed radiation images or GUIs, and a display or the like is used.

[0035] The hospital's internal LAN315 is the core network within the hospital.

[0036] The fourth communication cable 316 is a cable for connecting the control device 310 and the communication control device 323 in the radiology room 1.

[0037] Figure 2 shows a radiography apparatus 300. As shown in Figure 2, the radiography apparatus 300 has a radiation detector 100. The radiation detector 100 has the function of detecting irradiated radiation. The radiation detector 100 has a plurality of pixels arranged to constitute a plurality of rows and a plurality of columns. In the following description, the region in the radiation detector 100 where the plurality of pixels are arranged will be referred to as the detection region. The plurality of pixels include imaging pixels 101 for acquiring a radiation image or irradiation information, and correction pixels 121 for removing dark current components and crosstalk components.

[0038] In this embodiment, the imaging pixel 101 will be described as the detection pixel 101 for the purpose of acquiring irradiation information. The detection pixel 101 may be used only for acquiring radiation images, or only for acquiring irradiation information. Furthermore, it may acquire both radiation images and irradiation information. In other words, the detection pixel 101 only needs to be configured to acquire at least one of the information from either radiation images or irradiation information.

[0039] The detection pixel 101 includes a first conversion element 102 that converts radiation into an electrical signal, and a first switch 103 positioned between the column signal line 106 and the first conversion element 102.

[0040] The first conversion element 102 is composed of a scintillator that converts radiation into light and a photoelectric conversion element that converts light into an electrical signal. The scintillator is generally formed in a sheet shape to cover the detection area and is shared by multiple pixels. Alternatively, the first conversion element 102 is composed of a conversion element that directly converts radiation into light.

[0041] The first switch 103 includes, for example, a thin-film transistor (TFT) in which the active region is composed of a semiconductor such as amorphous silicon or polycrystalline silicon (preferably polycrystalline silicon).

[0042] The area containing the detection pixels 101 and correction pixels 121 for acquiring irradiation information is positioned at any location within the detection area of ​​the radiography apparatus 300. For example, similar to a conventional separate AEC sensor, it may be arranged in multiple areas such as A to C in Figure 3, or K to O in Figure 4.

[0043] The radiography apparatus 300 has a plurality of column signal lines 106 and a plurality of drive lines 104.

[0044] Each column signal line 106 corresponds to one of several columns in the detection area. Each drive line 104 corresponds to one of several rows in the detection area.

[0045] Each drive line 104 is driven by the drive circuit 221.

[0046] The first electrodes of the first conversion element 102 and the second conversion element 122 are connected to the first main electrodes of the first switch 103 and the second switch 123, and the second electrodes of the first conversion element 102 and the second conversion element 122 are connected to the bias wire 108. Here, one bias wire 108 extends in the column direction and is commonly connected to the second electrodes of multiple conversion elements 102 and 122 arranged in the column direction.

[0047] The bias wire 108 receives a bias voltage Vs from the power supply circuit 226 for the element. The bias voltage Vs is supplied from the power supply circuit 226 for the element.

[0048] The power control unit 301 consists of a battery, a DC-DC converter, etc. The power control unit 301 includes a power supply circuit 226 for the components and generates power for the analog circuit and power for the digital circuit that performs drive control and communication.

[0049] The second main electrodes of the first switches 103 of multiple detection pixels 101 constituting one column and the second switches 123 of the correction pixels 121 are connected to a single column signal line 106. The control electrodes of the first switches 103 of multiple detection pixels 101 constituting one row and the second switches 123 of the correction pixels 121 are connected to a single drive line 104. The multiple column signal lines 106 are connected to a readout circuit 222. Here, the readout circuit 222 includes multiple detection units 132, a multiplexer 134, and an analog-to-digital converter (hereinafter referred to as AD converter) 136.

[0050] Each of the multiple column signal lines 106 is connected to the corresponding detection unit 132 among the multiple detection units 132 of the reading circuit 222. Here, one column signal line 106 corresponds to one detection unit 132.

[0051] The detection unit 132 includes, for example, a differential amplifier. The multiplexer 134 selects a plurality of detection units 132 in a predetermined order and supplies the signals from the selected detection units 132 to the AD converter 136.

[0052] The AD converter 136 converts the supplied signal into a digital signal and outputs it.

[0053] The signal processing unit 224 outputs information indicating radiation irradiation to the radiography apparatus 300 based on the output of the readout circuit 222 (AD converter 136). Specifically, the signal processing unit 224 performs, for example, characteristic correction processing to remove dark current components and crosstalk components of the radiography apparatus 300 using correction pixels, radiation irradiation detection, and calculation of radiation irradiation dose and integrated irradiation dose.

[0054] The imaging device control unit 225 controls the drive circuit 221 and the readout circuit 222, etc., based on information from the signal processing unit 224 and control commands from the control device 310.

[0055] Figure 5 shows the imaging device control unit 225 of the radiography apparatus 300. As shown in Figure 5, the imaging device control unit 225 includes a drive control unit 400, a CPU 401, a memory 402, a generator control unit 403, an image control unit 404, and a communication switching unit 405.

[0056] The drive control unit 400 controls the drive circuit 221 and the read circuit 222 based on information from the signal processing unit 224 and commands from the control device 310. It also communicates with the radiography device 300 to receive radiographic images and control its operation.

[0057] The CPU 401 controls the entire radiography apparatus 300 using programs and various data stored in the memory 402.

[0058] Memory 402 stores programs and various data used by the CPU 401 when it performs processing. This data includes various data obtained through the processing of the CPU 401, as well as radiographic images.

[0059] The generator control unit 403 controls communication with the radiation generator 324 based on information from the signal processing unit 224 and the drive control unit 400.

[0060] The radiation generator control unit 403 and the radiation generator 324 exchange information regarding the control of the radiation generator (for example, notifications of the start and stop of radiation irradiation, radiation dose, cumulative radiation dose, etc.).

[0061] The radiation generator control unit 403 notifies the radiation generator 324 of a stop notification among the information regarding the control of the radiation generator when the radiation dose in the radiation detection area (lighting field) that monitors the radiation dose reaches a reference threshold (target cumulative dose). The lighting field is, for example, the area shown from A to C in Figure 3, or from K to O in Figure 4. That is, the detection pixel 101 included in the radiation detection area (lighting field area) corresponds to an example of a dose detection means that detects the received dose during radiation irradiation. The radiation generator control unit 403 detects the radiation incident on the lighting field with the detection pixel 101, and the signal processing unit 224 calculates the cumulative dose, which is the cumulative value of the dose (received dose) detected over a predetermined period.

[0062] The generator control unit 403 notifies the system to stop when the radiation dose in the light field selected for monitoring reaches a reference threshold (hereinafter referred to as the "reached dose monitoring function"). If multiple light fields are selected for monitoring, for example, there are three control methods: In the OR control method, the generator control unit 403 notifies the system to stop when the integral value of any one of the selected light fields reaches the target cumulative dose. Alternatively, in the AVERAGE control method, the generator control unit 403 notifies the system to stop when the average value of the integral values ​​of multiple light fields reaches the set target cumulative dose. Alternatively, in the AND control method, the generator control unit 403 notifies the system to stop when the integral values ​​of all multiple light fields reach the set target cumulative dose. Other control methods may also be used, and these may be combined in calculations.

[0063] For example, in Figure 11, if four light-gathering fields (R1, R2, R4, R5) are selected, considering that the radiography device rotates during use, it can be determined that it is sufficient for radiation to be delivered to two parallel light-gathering fields to the target value. In this case, a combination of operators such as (R1ANDR2)OR(R2ANDR5)OR(R5ANDR4)OR(R4ANDR1) can be specified, and a stop notification can be given based on the two light-gathering fields that first reach the target value.

[0064] While OR, AVERAGE, and AND control methods were given as examples, other control methods and operators (such as NAND, NOR, and XOR) can also be used in combination. In other words, the control method for automatic exposure control can be any control method that uses at least one of the following operators: AND, OR, AVERAGE, NAND, NOR, and XOR.

[0065] Furthermore, the mode in which the generator control unit 403 notifies of a stop is set by, for example, the radiography apparatus 300, the radiation generator 324, or the control device 310. Alternatively, there may be a mode in which radiation irradiation is not stopped based on the reached radiation dose, or a general exposure control sensor (such as an ion chamber / phototimer) not shown may be attached to the outside of the radiography apparatus 300 to stop radiation irradiation based on the radiation dose. In addition, although a generator control unit 403 is provided in this embodiment, a configuration in which radiation irradiation is detected by the signal processing unit 224 without communication with the radiation generator 324 and radiography is performed is also possible.

[0066] The image control unit 404 stores the image from the reading circuit 222 in the memory 402 and controls communication with the control device 310. The image control unit 404 and the control device 310 exchange information regarding radiation images and control (e.g., control commands).

[0067] The communication switching unit 405 switches the communication units so that when the wired cable 322 is connected to the radiography device 300, communication by the wired communication unit 303 is enabled, and when the wired cable 322 is disconnected from the radiography device 300, communication by the wireless communication unit 304 is enabled.

[0068] Figure 6 shows the control device 310. As shown in Figure 6, the control device 310 includes a determination unit 501, a calculation unit 502, and a display control unit 503.

[0069] The determination unit 501 determines the region (region of interest) for which dose index values ​​are calculated in the radiographic image generated by the radiographic imaging device 300. Here, the region for which dose index values ​​are calculated is broadly divided into the light-gathering field as shown in A to C in Figure 3, or K to O in Figure 4, and predetermined regions as shown in P in Figure 3 and Q in Figure 4. The latter region is any region, such as the entire radiographic image, a region specified by the operator, or a region corresponding to the imaging area. Note that the above is just an example and is not limited thereto.

[0070] Furthermore, in this embodiment, for example, the area for calculating the dose index value is represented by a rectangle as shown in Figure 8, but it is not limited to this. For example, it may be any shape such as a circle or a trapezoid.

[0071] The dose index value calculated in the region determined by the determination unit 501 is, for example, the EI value. In this embodiment, the EI value is used as the dose index value, but the same technique can be applied to dose indices in general. Furthermore, the dose index value may be a value that is proportional to the pixel value of the radiation image, or it may be a value that is inversely proportional to it.

[0072] The calculation unit 502 calculates the dose index value for the region determined by the determination unit 501. Alternatively, a dose index target value (e.g., EIt) that can be determined to be the optimal dose may be set for each region, and a deviation index (e.g., DI) may be calculated. The target dose index EIt and the deviation index DI are standardized indices as IEC62494-1. Specifically, the deviation index DI is calculated using the following formula.

[0073] DI = 10 log10(EI / EIt) Generally, a deviation index (DI) greater than 0 is considered to indicate a higher-than-normal dose, while a deviation index (DI) less than 0 is considered to indicate a lower-than-normal dose.

[0074] Furthermore, the dose index target values ​​that are set do not necessarily need to be set for each region. For example, when setting dose index target values ​​for the first, second, and third regions, it is also acceptable to set a first dose index target value common to the first and second regions, and a second dose index target value for the third region.

[0075] The display control unit 503 displays at least one of the following indicators calculated by the calculation unit 502 on the display device 314: the dose index value, the dose index target value, and the deviation index. The method of displaying the indicators on the display device 314 may be changed depending on the imaging conditions.

[0076] Furthermore, in this embodiment, the determination unit 501, calculation unit 502, and display control unit 503 are described as functions provided by the control device 310, but the radiography apparatus 300 may also be configured to have the functions of the determination unit 501, calculation unit 502, and display control unit 503. In other words, it is sufficient that at least one of the control device 310 and the radiography apparatus 300 has functions equivalent to the determination unit 501, calculation unit 502, and display control unit 503.

[0077] The procedure by which the calculation unit 502 calculates the EI value from the image is explained using the flowchart in Figure 7.

[0078] (S701: Removal of material outside the irradiation area) First, in step S701, the determination unit 501 excludes areas outside the region of interest of the diagnostic image that have not been irradiated from the captured image from the EI value calculation area. Methods for exclusion include, for example, calculating based on collimator information or tube-FPD distance (FDD) information, extracting irradiated areas from the image using prior information on each imaging site, or making a determination using machine learning.

[0079] (S702: Removal of the area equivalent to a direct line) Next, in step S702, the determination unit 501 identifies the direct line region and excludes the region outside the region of interest from the EI value calculation region. Methods for exclusion include, for example, the empirically based fixed threshold method, mode method, differential histogram method, p-tile method, or discriminant analysis method.

[0080] (S703: Removal of unwanted areas such as metal) Furthermore, in step S703, the determination unit 501 excludes low-dose regions from the EI value calculation area that are within the region of interest but should not be used as dose indicators for the region of interest in a normal diagnostic image. For example, methods such as the region growth method or the snake method can be used for exclusion.

[0081] Either the process described above is applied to the region for which the dose index value determined in advance by the determination unit 501 is calculated, or the process is applied to the entire image, and then the region for which the dose index value determined by the determination unit 501 is calculated is extracted to determine the region for calculating the EI value.

[0082] Furthermore, the processes S701 to S703 described above may be performed selectively or not. Also, the order of processing is not limited to the above; for example, the removal process in S703 may be performed before the removal process in S702.

[0083] (S704: Calculate representative values ​​for the extracted region) Next, in step S704, the calculation unit 502 calculates representative values ​​in the region of interest of the radiation image determined through the processing in steps S701 to S703. Representative values ​​are, for example, pixel values ​​such as the mean, median, or mode. In this case, if there are multiple regions of interest, such as when multiple light-gathering fields are set, representative values ​​are calculated for each region of interest. This allows the operator to recognize the dose values ​​in each region of interest.

[0084] (S705: Convert representative values ​​to EI values) Finally, in S705, the calculation unit 502 converts the representative value into a dose based on the known relationship between the incident dose and the pixel value. Then, it multiplies the converted dose by a constant to calculate the dose index value. More specifically, it converts the representative value so that 100 = 1 μGy to calculate the dose index value (EI value). At the same time, it calculates the deviation index DI from the target dose index value EIt, and the operator confirms whether the radiation image was taken with the expected radiation dose.

[0085] Next, using Figures 8 and 9, we will explain an example of how dose index values ​​are displayed on the display device 314.

[0086] The display control unit 503 displays the dose index value calculated by the calculation unit 502 on the display device 314.

[0087] The dose index value may be displayed as an annotation at the edge of the radiation image, as shown in Figure 8(a), or superimposed on the image area where the dose index value was calculated, as shown in Figure 8(b). Furthermore, it may be displayed separately from the radiation image. For example, as shown in Figure 8(c), it may be displayed adjacent to the radiation image. Also, as shown in Figure 8(d), it may be displayed without accompanying the radiation image. Furthermore, as shown in Figure 9(a), the dose index value may be displayed on the radiation image in grayscale (or color scale), or as shown in Figure 9(b), only the grayscale (or color scale) may be displayed separately. Also, as shown in Figure 9(c), they may be combined. That is, at least two pieces of information regarding the value calculated by the calculation unit 502 may be displayed with at least one of the following differences: color and / or intensity.

[0088] Figures 8(a) to (d) and 9(a) to (c) show examples of displaying dose index values ​​using text and color, but the display method can be defined by any combination of identifiable expressions such as text, symbols, diagrams, size, color, and shape. Furthermore, the display control unit 503 may also display the dose index target value and the deviation index value together with the dose index value. The dose index target value and the deviation index may be displayed using the same display method as the dose index value, or they may be displayed using a different, arbitrary display method. Alternatively, the dose index value and deviation index value themselves may not be displayed at all, and instead, a warning dialog box may be displayed if they exceed a predetermined threshold, for example. There may be only one threshold, or one threshold may be set for each area where the dose index value is calculated.

[0089] Furthermore, when the display control unit 503 notifies that radiation irradiation has been stopped, it may also indicate on the display device 314 which of the one or more light fields was used to make the final decision to stop the radiation. If the control method is AND, it indicates the one or more light fields that last reached the target dose. Alternatively, if the control method is OR, it indicates the light field that first reached the threshold. Alternatively, if the control method is AVERAGE, it indicates all light fields. The method of indication may be, for example, as text information, or by highlighting the display indicating the light field on the image. Also, the dose index may be displayed only for the light field information used to make the final decision to stop the radiation, or the dose index of all light fields may be displayed and only the light field used to make the final decision to stop the radiation may be marked.

[0090] Next, the operation of the radiography system 10 during imaging will be explained using Figure 10.

[0091] When power is supplied to the radiography system 10 and the radiography device 300 is powered on, initial settings are performed and communication with the control device 310 becomes possible.

[0092] (S101: Enter subject information and imaging information) First, in step S101, the radiography system 10 sets patient information such as the patient's ID, name, and date of birth in the control device 310. The radiography system 10 also sets imaging information such as the imaging area, light field, and dose index target value for the patient 306. The patient information and imaging information may be set automatically, for example, by selecting an examination order received via the hospital LAN 315. Alternatively, the imaging information may be set by the operator 312 by selecting a pre-configured imaging protocol. Or, the patient information and imaging information may be set by the operator 312 by direct input. Based on the input information, the radiography system 10 sets the light field of the radiography device 300. After the patient 306 information and imaging area information are set in the control device 310, the operator 312 fixes the posture of the patient 306 and the radiography device 300. Furthermore, operator 312 inputs the dose, maximum irradiation time, tube current, tube voltage, site information, light field, dose index target value, etc., to control device 310. Control device 310 transmits the input radiation irradiation conditions, site information, light field, dose index target value, etc., to the radiography apparatus 300 and radiation generator 324. Alternatively, the input may be made to the radiation generator 324, and the system may notify the control device 310 and radiography apparatus 300 of the information. Here, control device 310 may acquire information that is managed in association with at least one of the patient information and imaging information. Information managed in association with site information includes, for example, AEC light field selection information, automatic exposure control method when multiple light fields are selected (e.g., AND method), and target cumulative irradiation dose which is the threshold for stopping radiation. In other words, control device 310 can acquire information regarding the automatic exposure control method associated with at least one of the patient information and imaging information. Specifically, for example, if the location information is the front of the chest, the right and left lighting fields (Figure 4K, L) corresponding to both lung fields are selected and managed in association with the AND method as the automatic exposure control method. Alternatively, if the location information is the side of the chest, the central lighting field (Figure 4M) is selected and managed in association with it.In this embodiment, step S702 shows an example where the control device 310 acquires information managed in association with the input or notified body part information. However, this information may be managed separately for subject information or imaging information that differs from the body part information. For example, it may be managed in association with imaging procedure, imaging posture, imaging direction, presence or absence of a grid, or type of radiography equipment.

[0093] (S102: Photo taken) When the preparation for imaging is complete, in step S102, the operator 312 presses the irradiation switch 311. When the irradiation switch 311 is pressed, radiation is emitted from the radiation source 325 towards the subject 306. At this time, the radiography device 300 communicates with the radiation generator 324 to control the start of radiation irradiation. The radiation emitted to the subject 306 passes through the subject 306 and enters the radiography device 300. If the radiography device 300 is set to use the dose arrival monitoring function, the detection pixel 101 detects the radiation incident in the light-gathering field, and the signal processing unit 224 calculates the cumulative irradiation dose, which is the cumulative value of the dose detected (arrival dose) over a predetermined period. The imaging device control unit 225 calculates a reference threshold from the cumulative irradiation dose information from the signal processing unit 224 and the area information and imaging conditions entered by the operator 312, and determines the timing to stop radiation irradiation according to the mode set in the generator control unit 403. Based on the determined radiation irradiation stop timing, the radiography apparatus 300 notifies the radiation generator 324 of the stop via the first communication cable 307, the communication control device 323, and the third communication cable 327. The radiation generator 324 stops irradiating with radiation based on the notified radiation irradiation stop timing. The radiography apparatus 300 notifies of the stop of radiation irradiation as a detection result of detecting radiation, but is not limited to this. The radiography apparatus 300 may also transmit the received dose at predetermined time intervals as a detection result, and the radiation generator 324 may calculate the integrated value of the received dose. After radiation irradiation stops, the radiography apparatus 300 converts the incident radiation into visible light and then detects it as a radiation image signal with a photoelectric conversion element. The radiography apparatus 300 drives the photoelectric conversion element to read out the radiation image signal and converts the analog signal into a digital signal with an AD conversion circuit to obtain a radiation image.

[0094] (S103: Received radiographic images) In step S103, the radiography system 10 transfers the obtained radiographic image from the radiography apparatus 300 to the control device 310 via the first communication cable 307, the communication control device 323, and the third communication cable 327. The control device 310 processes the received digital radiographic image. The control device 310 displays the processed radiographic image on the display device 314. The control device 310 also functions as an image processing device and a display control device.

[0095] (S104: Dose arrival monitoring function) In step S104, the control device 310 determines whether the dose-reaching monitoring function is enabled or disabled. If the dose-reaching monitoring function is enabled (S104 / Yes), the process proceeds to step S105. On the other hand, if the dose-reaching monitoring function is disabled (S104 / No), the process proceeds to step S106.

[0096] (S105: The light field is used as the calculation area) In S105, the determination unit 501 determines the light-collecting field set in S101 as the calculation area for calculating the radiation dose. For example, in the case of lung imaging, light-collecting fields are often set for both lungs when performing radiography. In this case, the calculation area for calculating the radiation dose is the light-collecting field set for both lungs. Note that the calculation area determined by the determination unit 501 in S105 does not necessarily have to coincide with the light-collecting field; for example, it may be an area based on the light-collecting field obtained by the process shown in Figure 7.

[0097] (S106: A predetermined calculation area) In S106, the determination unit 501 determines a predetermined area as the calculation area for calculating the radiation dose. The predetermined area is set by the operator 312 in S101, for example. However, if the predetermined area is an area that can be determined independently of the shooting information or the operator 312's settings, such as the entire image area, the operator 312 does not necessarily have to set it. Alternatively, the operator 312 may change the area after shooting.

[0098] Furthermore, in this embodiment, the display area is determined by whether the dose monitoring function is enabled or disabled, but this is not the only way to do so.

[0099] (S107: Calculate dose index values ​​for each region) In step S107, the control device 310 transfers the received digital radiation image to the calculation unit 502. The calculation unit 502 then calculates dose index values ​​from the received radiation image for the previously determined calculation area. At this time, for example, dose index values ​​are calculated for each of the light-collecting fields set for both lungs.

[0100] (S108: Calculate the deviation index value for each area) In step S108, the calculation unit 502 calculates the deviation index value. In this embodiment, the dose index and deviation index are calculated by the control device 310, but this may also be done by the radiography device 300 or by another calculation device (not shown).

[0101] (S109: Display the calculated value) In step S109, the control device 310 transmits the dose index and deviation index calculated by the calculation unit 502 to the display control unit 503, and the display control unit 503 displays, for example, the information shown in Figure 11. Figure 11 shows an example in which the received dose monitoring function is enabled and the lung field imaging is performed with both lung regions R1 and R2 shown in Figure 11(b) as the light-collecting field, and the dose index and deviation index are displayed for each region as shown in Figures 11(a) and (c).

[0102] Furthermore, the setting for whether or not to display on the display device 314 may be made before the image is taken, or after the image is taken by the operator 312. The display settings may also be changed by setting the received dose monitoring function. In addition, the system may be controlled to display an icon or dialog box (not shown) when the received dose index or deviation index meets certain conditions. Examples of such conditions include when the dose index or deviation index is greater than a predetermined value.

[0103] In this embodiment, the image is shown immediately after being captured, but the same method may be used to display images taken in the past. Furthermore, the actual light field used in the dose monitoring function may be acquired from the radiation imaging device 300 and reflected in the display content. For example, when radiation is stopped, the display device 314 can display which of the one or more representative light fields was used to make the final decision to stop the radiation. That is, the control device 310 can explicitly display one or more representative light fields used to make the decision to stop radiation based on the control method. If the control method is AND, one or more light fields that last reached the target dose can be explicitly displayed; if it is OR, one or more light fields that first reached the threshold can be explicitly displayed; and if it is AVERAGE, all light fields can be explicitly displayed. The method of explicit display can be as text information or by indicating the location of the light field on the image. This allows the operator to easily recognize which light field was used to stop radiation irradiation. The operator can also easily recognize which light field was used to stop radiation irradiation and the numerical value of the dose index in that light field.

[0104] The above completes the series of processes performed by the radiography system 10.

[0105] According to the above, in radiography, the operator can appropriately determine whether the required dose is applied to the light-gathering field for automatic exposure control.

[0106] Furthermore, in imaging where multiple regions of interest exist, such as when multiple light-gathering fields are set, the operator 312 can determine whether the dose irradiated to each region of interest was appropriate by checking the respective dose index values ​​and deviation index values ​​displayed on the display device 314. For example, if the imaging dose can be reduced using the reach dose monitoring function, and it can be confirmed that an appropriate dose was delivered to each region of interest, it becomes easy to determine that the imaging was performed appropriately.

[0107] [Second Embodiment] In the second embodiment, the configuration of the radiography system 10 that calculates and displays dose index values ​​for both a predetermined area and the light-gathering field of automatic exposure control is described. This allows the operator to appropriately determine whether the required dose is applied to both the predetermined area and the light-gathering field of automatic exposure control.

[0108] The processing of the radiography system according to this embodiment will be explained below using Figures 12 to 14. The functional configuration is the same as in the first embodiment, so a description will be omitted.

[0109] First, using Figures 12 and 13, we will explain an example of how dose index values ​​are displayed on the display device 314.

[0110] The display control unit 503 displays the first dose index value and the second dose index value calculated by the calculation unit 502 on the display device 314. The first dose index value and the second dose index value may be displayed as annotations at the edge of the radiation image, as shown in Figure 12(a), or they may be displayed superimposed on each other, as shown in Figure 12(b), with the first dose index value superimposed at an arbitrary position on the radiation image and the second dose index value superimposed at the position of the light-collecting field on the radiation image where the dose index value was calculated. Furthermore, they may be displayed separately from the radiation image, as shown in Figure 12(c), or without a radiation image, as shown in Figure 12(d). In addition, as shown in Figure 13(a), the dose index value may be displayed in grayscale (or color scale) to represent the relative position of the radiation image and the position of the light-collecting field on the radiation image, or only the grayscale (or color scale) may be displayed separately, as shown in Figure 13(b). They may also be combined, as shown in Figure 13(c). In other words, at least two pieces of information relating to the value calculated by the calculation unit 502 may be displayed with at least one of the following differences: color and / or intensity.

[0111] Figures 13(a) to (d) and 13(a) to (c) show examples of how dose index values ​​are displayed using text and color, but the display method is defined by any combination of identifiable expressions such as text, symbols, diagrams, size, color, and shape. Furthermore, the display control unit 503 may display the first dose index target value, the first deviation index value, the second dose index target value, and the second deviation index value together with the first dose index value and the second dose index value. The first dose index target value and the first deviation index value may be displayed with the first dose index value, and the second dose index target value and the second deviation index value may be displayed with the second deviation index value, using the same display method, or they may be displayed using different arbitrary display methods. Alternatively, the first dose index value, the first deviation index value, the second dose index target value, and the second deviation index value themselves may not be displayed at all, and instead, for example, a warning dialog box may be displayed if the values ​​exceed a predetermined threshold.

[0112] Next, the operation of the radiography system 10 during imaging in the second embodiment will be described using Figure 14.

[0113] (S1401: Enter subject information and imaging information) First, in step S1401, the radiography system 10 sets patient information such as the patient's ID, name, and date of birth in the control device 310. The radiography system 10 also sets imaging information such as the imaging area, light field, and dose index target value for the patient 306. The patient information and imaging information may be set automatically, for example, by selecting an examination order received via the hospital LAN 315. Alternatively, the imaging information may be set by the operator 312 by selecting a pre-configured imaging protocol. Or, the patient information and imaging information may be set by the operator 312 by direct input. Based on the input information, the radiography system 10 sets the light field of the radiography device 300. After the patient 306 information and imaging area information are set in the control device 310, the operator 312 fixes the posture of the patient 306 and the radiography device 300. Furthermore, operator 312 inputs the dose, maximum irradiation time, tube current, tube voltage, site information, light field, and dose index target value to the control device 310. The control device 310 transmits the input radiation irradiation conditions, site information, light field, and dose index target value to the radiography device 300 and the radiation generator 324. Alternatively, the input may be made to the radiation generator 324, and the information may be notified to the control device 310 and the radiography device 300.

[0114] (S1402: Photo taken) Once the preparation for imaging is complete, in step S1402, the operator 312 presses the irradiation switch 311. When the irradiation switch 311 is pressed, radiation is emitted from the radiation source 325 towards the subject 306. At this time, the radiography device 300 communicates with the radiation generator 324 to control the start of radiation irradiation. The radiation emitted to the subject 306 passes through the subject 306 and enters the radiography device 300. If the radiography device 300 is set to use the dose arrival monitoring function, the detection pixel 101 detects the radiation incident in the light-gathering field, and the signal processing unit 224 calculates the cumulative irradiation dose, which is the cumulative value of the dose detected (arrival dose) over a predetermined period. The imaging device control unit 225 calculates a reference threshold from the cumulative irradiation dose information from the signal processing unit 224 and the area information and imaging conditions entered by the operator 312, and determines the timing to stop radiation irradiation according to the mode set in the generator control unit 403. Based on the determined radiation irradiation stop timing, the radiography apparatus 300 notifies the radiation generator 324 of the stop via the first communication cable 307, the communication control device 323, and the third communication cable 327. The radiation generator 324 stops irradiating with radiation based on the notified radiation irradiation stop timing. The radiography apparatus 300 notifies of the stop of radiation irradiation as a detection result of detecting radiation, but is not limited to this. The radiography apparatus 300 may also transmit the received dose at predetermined time intervals as a detection result, and the radiation generator 324 may calculate the integrated value of the received dose. After radiation irradiation stops, the radiography apparatus 300 converts the incident radiation into visible light and then detects it as a radiation image signal with a photoelectric conversion element. The radiography apparatus 300 drives the photoelectric conversion element to read out the radiation image signal and converts the analog signal into a digital signal with an AD conversion circuit to obtain a radiation image.

[0115] (S1403: Received radiographic images) In step S103, the radiography system 10 transfers the obtained radiographic image from the radiography apparatus 300 to the control device 310 via the first communication cable 307, the communication control device 323, and the third communication cable 327. The control device 310 processes the received digital radiographic image. The control device 310 displays the processed radiographic image on the display device 314. The control device 310 also functions as an image processing device and a display control device.

[0116] (S1404: Calculate dose index values ​​for the region of interest) In step S1404, the control device 310 transfers the received digital radiation image data to the calculation unit 502. The calculation unit 502 calculates dose index values ​​for multiple regions of interest based on the received radiation image data. More specifically, the calculation unit 502 calculates a first dose index value from a predetermined region of the radiation image generated based on the received radiation image data. Hereinafter, the predetermined region will be described as the entire radiation image, but is not limited to this. The calculation unit 502 also calculates a second dose index value from the radiation image generated based on the received radiation image data, based on the field of view.

[0117] (S1405: Calculate the deviation index value of the area of ​​interest) In step S1405, the calculation unit 502 calculates the deviation index value. In this embodiment, the control device 310 calculates the dose index and the deviation index value, but this may be done by the radiography apparatus 300 or by another calculation device (not shown).

[0118] (S1406: Display the calculated value) In step S1407, the calculation unit 502 transfers the first dose index value, the second dose index value, the first dose index target value, the first deviation index value, the second dose index target value, and the second deviation index value to the display control unit 503, and the display control unit 503 displays, for example, the information shown in Figure 12. That is, the display control unit 503 displays information about the values ​​calculated by the calculation unit 502 on the display unit.

[0119] Figure 12 shows an example in which the dose monitoring function is enabled and, in imaging of the lung field region with both the K and L lung regions shown in Figure 12(b) as the light-collecting field, dose index values ​​(first dose index value and second dose index value) and deviation index values ​​(first deviation index value and second deviation index value) are displayed for the entire radiographic image and for each of the monitored light-collecting fields, as shown in Figures 12(a) and (c).

[0120] In this way, by displaying dose index values ​​(first dose index value and second dose index value) and deviation index values ​​(first deviation index value and second deviation index value) for the entire radiation image and each area of ​​the light-gathering field being monitored, it is possible to confirm whether the dose was appropriate for the region of interest in the radiation image and the light-gathering field set as the target to be monitored. Whether or not to display on the display device 314 may be set before the image is taken, or it may be set by the operator 312 after the image is taken. The display settings may also be changed by setting the received dose monitoring function. In addition, it may be possible to control the display to show an icon or dialog box (not shown) when the first dose index value, second deviation index value, first deviation index value, and second deviation index value meet certain conditions. Examples of specific conditions include when any of the index values ​​of the first dose index value, second deviation index value, first deviation index value, and second deviation index value are greater than a predetermined value.

[0121] In this embodiment, we refer to an image taken immediately after capture, but the same method may be used to display images taken in the past. In this case, the second dose index calculation unit 502 may acquire the light field used in the dose arrival monitoring function from the radiation imaging device 300 or the image data control unit 404 in order to calculate the second dose index value, and reflect this in the display content.

[0122] The series of processes of the radiography system 10 in the second embodiment are then carried out.

[0123] According to the above, the operator 312 can appropriately determine whether the required dose is applied to both the predetermined area and the light-gathering field of the automatic exposure control by checking the first dose index value and the second dose index value displayed on the display device 314. For example, if the predetermined area is the entire area of ​​the image, the operator can check both the dose index irradiated to the entire area and the dose index irradiated to the light-gathering field in a later step.

[0124] Furthermore, for example, if the acquired dose can be reduced using the dose monitoring function, and it can be confirmed that the appropriate dose is applied to the region of interest in the radiation image and its respective light-gathering field, it becomes easy to determine that the imaging was performed appropriately.

[0125] [Other embodiments] The present invention 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 that implements one or more functions.

[0126] A processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or a field-programmable gateway (FPGA). It may also include a digital signal processor (DSP), a dataflow processor (DFP), or a neural processing unit (NPU).

[0127] The radiography system in each of the embodiments described above may be implemented as a single device, or as a combination of multiple devices that can communicate with each other to perform the above-described processing; both are included in the embodiments of the present invention. The above-described processing may also be performed using a common server device or group of servers. The multiple devices constituting the radiography system only need to be able to communicate at a predetermined communication rate, and do not need to be located in the same facility or in the same country.

[0128] Embodiments of the present invention include a configuration in which a software program that realizes the functions of the above-described embodiment is supplied to a system or device, and the computer of the system or device reads and executes the code of the supplied program.

[0129] Therefore, the program code installed on the computer to implement the processing according to the embodiment is itself one of the embodiments of the present invention. Furthermore, based on the instructions contained in the program read by the computer, the operating system running on the computer may perform part or all of the actual processing, and the functions of the above-described embodiment can also be realized through that processing.

[0130] Furthermore, the present invention is not limited to the embodiments described above. For example, it can be adapted not only for still image capture but also for video recording. Various modifications (including organic combinations of each embodiment) are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention. In other words, configurations that combine each of the above-described embodiments are all included in the embodiments of the present invention. [Explanation of symbols]

[0131] 10. Radiography System 300 radiography equipment 301 Power Control Unit 302 Standing Stand 303 Wired Communications Department 304 Wireless Communication Section 306 subjects 307 First communication cable 310 Control device 311 Irradiation switch 312 Operator 313 Input device 314 Display device 315 Hospital LAN 316 Fourth communication cable 320 access points 323 Communication control device 324 Radiation Generator 325 Radiation Source 326 Second communication cable 327 Third communication cable

Claims

1. A radiography system including a radiography apparatus that acquires radiographic images based on radiation, and a control device that communicates with the radiography apparatus and receives radiographic images and controls its operation, Setting means for setting a region of interest used for automatic exposure control and a dose index target value corresponding to the region of interest before the aforementioned radiation image is acquired, After the aforementioned radiation image is acquired, a calculation means calculates a dose index value corresponding to the region of interest, and calculates an index based on the dose index target value and the calculated dose index value, A radiography system equipped with [specific features / equipment].

2. The radiation imaging system according to claim 1, further comprising a display control means for displaying the dose index value and the index on a display unit.

3. The radiography system according to claim 2, wherein the display control means displays the dose index value and the index on the display unit in a state superimposed on the radiographic image.

4. The setting means sets a plurality of regions of interest used for automatic exposure control and a plurality of dose index target values ​​corresponding to the plurality of regions of interest, The radiography system according to claim 1, wherein the calculation means calculates a plurality of dose index values ​​corresponding to the plurality of regions of interest, and calculates a plurality of indices based on the plurality of dose index target values ​​and the calculated plurality of dose index values.

5. The radiation imaging system according to claim 1, wherein the dose index value is a value that is proportional to or inversely proportional to the pixel value of the radiation image.

6. The radiation imaging system according to claim 2, wherein the display control means displays on the display unit whether or not the dose index value is greater than the dose index target value.

7. The radiography system according to claim 2, wherein the display control means displays the magnitude of the dose index value on the display unit in an identifiable manner using a color scale or grayscale.

8. The radiography system according to claim 7, wherein the display control means superimposes the color scale or grayscale onto the radiographic image to display the magnitude of the dose index value on the display unit in an identifiable manner.

9. The setting means sets a plurality of regions of interest used for automatic exposure control and a plurality of dose index target values ​​corresponding to the plurality of regions of interest, The calculation means calculates a plurality of dose index values ​​corresponding to the plurality of areas of interest, and calculates a plurality of indices based on the plurality of dose index target values ​​and the calculated plurality of dose index values. The radiation imaging system according to claim 2, wherein the display control means displays on the display unit whether the dose index value is greater than the dose index target value for each of the plurality of regions of interest.

10. The radiation imaging system according to claim 2, wherein the display control means displays a warning dialog on the display unit when the dose index value is greater than the dose index target value.

11. The calculation means further calculates the dose index value for the entire radiation image, The radiography system according to claim 2, wherein the display control means displays the dose index value of the entire radiographic image and the dose index value corresponding to the region of interest on the display unit.

12. When the aforementioned index is defined as DI, the dose index value as EI, and the dose index target value as EIT, The radiography system according to any one of claims 1 to 11, wherein the calculation means calculates the index DI by the following formula. DI=10 log10(EI / EIt)

13. A radiography method for a radiography system, comprising a radiography apparatus that acquires radiographic images based on radiation, and a control device that communicates with the radiography apparatus and receives radiographic images and controls its operation, Before acquiring the aforementioned radiation image, a setting step is performed to set a region of interest used for automatic exposure control and a dose index target value corresponding to the region of interest. After the aforementioned radiation image is acquired, a calculation step is performed to calculate a dose index value corresponding to the region of interest, and to calculate an index based on the dose index target value and the calculated dose index value. A radiography method for a radiography system equipped with radiography equipment.

14. A program for causing a computer to execute the radiography method described in claim 13.

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