X-ray image processing device, X-ray diagnostic device, and X-ray image processing method

Abstract

To obtain positional information of a diaphragm area in an X-ray image accurately and stably .SOLUTION: An X-ray image processing device according to an embodiment has a determination unit and an adjustment unit. The determination unit determines whether or not to use an extraction result of extraction processing on a diaphragm area of an image base with respect to an X-ray image, based on imaging conditions corresponding to the X-ray image. When it is determined that the extraction result is to be used, the adjustment unit adjusts the extraction result based on system control information relating to an X-ray diaphragm, and calculates positional information of the diaphragm area included in the X-ray image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to an X-ray image processing apparatus, an X-ray diagnostic apparatus, and an X-ray image processing method. [Background technology]

[0002] In X-ray image diagnosis, X-ray images are sometimes inverted from negative to positive for interpretation. With this inversion, the image area blocked by the X-ray aperture (aperture area) is displayed in white instead of black. If the aperture area is displayed in white, it becomes difficult to interpret the image area (exposure field area) that is surrounded by the aperture area and corresponds to the radiation field. For this reason, there is a function called an electronic shutter that applies a mask to the aperture area and paints it black.

[0003] Known methods for extracting the aperture area include image-based methods such as a method of analyzing an X-ray image and a method of image recognition using AI (Artificial Intelligence). However, with this method, the expected accuracy may not be obtained depending on the shape of the aperture area depicted in the X-ray image. Another known extraction method is a method of estimating the aperture area from the control information of the aperture device. However, with this method, the expected accuracy may not be obtained depending on mechanical factors, installation factors, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-217973 [Patent Document 2] JP 2020-192090 A [Patent Document 3] Japanese Patent Application Publication No. 6-289985 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to realize highly accurate and stable acquisition of position information of the aperture region of an X-ray image. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The X-ray image processing apparatus according to the embodiment includes a determination unit and an adjustment unit. The determination unit determines whether or not to use an extraction result of an image-based extraction process of an aperture area for an X-ray image based on an imaging condition corresponding to the X-ray image. When it is determined that the extraction result is to be used, the adjustment unit adjusts the extraction result based on system control information related to the X-ray aperture, and calculates position information of the aperture area included in the X-ray image. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an X-ray diagnostic apparatus according to this embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the positional relationship (without positional accuracy failure) between the aperture region, the radiation field region, and the frame line of the electronic shutter in an X-ray image when the arrangement angle of the X-ray tube is 0 degrees. [Diagram 3] FIG. 3 is a diagram showing an example of the positional relationship (with poor positional accuracy) between the aperture region, the radiation field region, and the frame line of the electronic shutter in an X-ray image when the arrangement angle of the X-ray tube is tilted from 0 degrees. [Figure 4] FIG. 4 is a diagram showing an example of the positional relationship (this embodiment) between the aperture region, the radiation field region, and the frame line of the electronic shutter in an X-ray image when the arrangement angle of the X-ray tube is tilted from 0 degrees. [Diagram 5] FIG. 5 is a diagram showing an outline of processing by the processing circuit according to this embodiment. [Figure 6] FIG. 6 is a diagram showing an outline of the adjustment process performed by the processing circuit of FIG. [Figure 7]FIG. 7 is a diagram showing a processing example of the first X-ray examination by the X-ray diagnostic apparatus of FIG. [Figure 8] FIG. 8 is a diagram showing an example of a setting screen for the adjustment parameters set in step SA1 of FIG. [Figure 9] FIG. 9 is a diagram illustrating the input / output relationship of a trained model used in image recognition using AI, which is utilized in step SA4 of FIG. [Figure 10] FIG. 10 is a diagram showing a schematic flow of the processes in steps SA8 to SA9 in FIG. [Figure 11] FIG. 11 is a diagram showing an example of a determination process by the determination function executed in step SA3 of FIG. [Figure 12] FIG. 12 is a diagram showing a first adjustment processing example by the narrowing region adjustment function executed in step SA6 of FIG. [Figure 13] FIG. 13 is a diagram showing the definition of the position information of the aperture region in the first adjustment processing example. [Figure 14] FIG. 14 is a diagram showing a second adjustment processing example by the narrowing region adjustment function executed in step SA6 of FIG. [Figure 15] FIG. 15 is a diagram showing the definition of the position information of the aperture region in the second adjustment processing example. [Figure 16] FIG. 16 is a diagram showing a processing example of the second X-ray examination by the X-ray diagnostic apparatus of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of an X-ray image processing apparatus, an X-ray diagnostic apparatus, and an X-ray image processing method will be described in detail with reference to the drawings.

[0009] The X-ray image processing apparatus according to this embodiment is a computer that processes X-ray images generated by an X-ray diagnostic apparatus. The X-ray image processing apparatus may be a computer included in the X-ray diagnostic apparatus, or may be a computer separate from the X-ray diagnostic apparatus. Hereinafter, the medical image processing apparatus is assumed to be a computer included in the X-ray diagnostic apparatus.

[0010] Fig. 1 is a diagram showing the configuration of an X-ray diagnostic apparatus 1 according to this embodiment. As shown in Fig. 1, the X-ray diagnostic apparatus 1 has an X-ray imaging unit 3 and an X-ray image processing device 5. The X-ray imaging unit 3 and the X-ray image processing device 5 are connected to each other by wire or wirelessly so as to be able to communicate with each other.

[0011] Although the X-ray diagnostic device 1 can be any type of device, such as a general X-ray device, an X-ray fluoroscopy device, a circulatory system device, or a mammography device, for the sake of specificity in the following explanation, it is assumed that the X-ray diagnostic device 1 is an X-ray fluoroscopy device. An X-ray fluoroscopy device is also called a digital X-ray TV system.

[0012] As shown in FIG. 1, the X-ray imaging unit 3 is a mechanical system that performs X-ray imaging. The X-ray imaging unit 3 includes an X-ray tube 11, a high-voltage generator 12, a diaphragm device 13, an X-ray detector 14, a holding device 15, a driving device 17, a top plate 31, a holding device 33, and a driving device 35. The X-ray tube 11 is connected to the high-voltage generator 12 via a high-voltage cable. The high-voltage generator 12 generates a high voltage to be applied to X-rays in response to a control signal from a system control circuit 56 of the X-ray image processing device 5. The X-ray tube 11 generates X-rays in response to the application of the high voltage from the high-voltage generator 12. The X-ray tube 11 is provided with a diaphragm device 13. The diaphragm device 13 adjusts the positions of a plurality of diaphragm blades that block X-rays to form an irradiation field. The diaphragm device 13 adjusts the positions of the diaphragm blades in response to a control signal from the system control circuit 56.

[0013] The X-ray detector 14 detects the X-rays generated from the X-ray tube 11. Specifically, the X-ray detector 14 is an FPD (Flat Panel Detector) having a plurality of detector pixels arranged in a two-dimensional plane, a readout circuit, and an A / D conversion circuit. Each detector pixel detects the X-rays generated from the X-ray tube 11 and generates an electric signal (detection signal) according to the intensity of the detected X-rays. The readout circuit reads out the detection signals from the plurality of detector pixels in units of frames at a predetermined timing. The A / D conversion circuit A / D converts the detection signals read out from the plurality of detector pixels to generate digital X-ray image data related to the subject. The generated X-ray image data is transmitted to the storage device 52 of the X-ray image processing device 5.

[0014] The holding device 15 is a mechanical device that holds the X-ray tube 11 and the X-ray detector 14. The holding device 15 supports the X-ray tube 11 and the X-ray detector 14 so that they can move freely. The holding device 15 is driven by receiving a drive signal from the drive device 17. The drive device 17 supplies a drive signal to the holding device 15 in response to a control signal from the system control circuit 56. The X-ray tube 11, the X-ray detector 14, and the holding device 15 are positioned by the supply of the control signal.

[0015] The top board 31 is a plate-like structure on which a subject is placed. The holding device 33 is a support structure that supports the top board 31 so that it can be moved freely. The holding device 33 supports the top board 31 so that it can be raised or lowered between +90 degrees and -90 degrees with respect to the horizontal direction. The holding device 33 is driven by receiving a drive signal from a driving device 35. The driving device 35 supplies a drive signal to the holding device 33 in response to a control signal from a system control circuit 56. The top board 31 is positioned by the supply of the control signal.

[0016] The X-ray imaging unit 3 according to this embodiment can be applied to any of the above-table, under-table, and C-arm systems. For example, in the case of the C-arm system, the holding device 33 that supports the tabletop and the holding device 15 that supports the X-ray tube 11 and the X-ray detector 14 are realized by a single mechanical device. In the case of the C-arm system, the X-ray tube 11 and the X-ray detector 14 are provided on the C-arm. The C-arm is supported by a holder so as to be rotatable around a rotation axis. The holder of the C-arm is slidably provided on a guide having a long axis shape. The guide is supported on a base placed on the floor so as to be rotatable around a rotation axis. The guide supports the tabletop 31 via a tabletop arm with a gap that forms a moving space for the C-arm.

[0017] With the above structure, the base supports the C-arm, holder, guide, table arm, and table 31 individually or integrally so that the C-arm can rotate around the rotation axis of the holder, the C-arm can slide along the long axis of the guide, and the table 31 can be raised or lowered around the rotation axis of the base. This makes it possible for the base to position the C-arm at any position on the table 31 from any direction while freely raising or lowering the table 31.

[0018] 1, the X-ray image processing device 5 is a computer that controls the X-ray diagnostic device. The X-ray image processing device 5 has a system control circuit 56 as a core, a processing circuit 51, a storage device 52, an input device 53, a communication device 54, and a display device 55. The processing circuit 51, the storage device 52, the input device 53, the communication device 54, the display device 55, and the system control circuit 56 are connected to each other via a bus so as to be able to communicate with each other.

[0019] The processing circuit 51 has a processor as a hardware resource. The processing circuit 51 executes a processing program according to this embodiment, and realizes an acquisition function 511, a parameter setting function 512, a determination function 513, an image-based extraction function 514, a narrowing region adjustment function 515, and a display control function 516. Note that each of the functions 511 to 516 is not limited to being realized by a single processing circuit. A processing circuit may be configured by combining a plurality of independent processors, and each processor may execute a program to realize each of the functions 511 to 516.

[0020] By implementing the acquisition function 511, the processing circuitry 51 acquires the X-ray image generated by the X-ray detector 14.

[0021] By implementing the parameter setting function 512, the processing circuit 51 sets various parameters. The parameters to be set include imaging conditions and system control information. The imaging conditions include an examination protocol, a procedure, an X-ray condition, and a division setting. The system control information is control information related to the imaging of an X-ray image, and includes, for example, control information related to a mechanical or electronic X-ray aperture. The mechanical X-ray aperture means the aperture device 13. The electronic X-ray aperture means a mask applied to an aperture area included in an X-ray image, that is, an electronic shutter. The system control information includes aperture control information as control information related to a mechanical X-ray aperture. The aperture control information is control information of a mechanical device of an X-ray diagnostic device that affects the position of an aperture area drawn in an X-ray image. The aperture control information includes, for example, control information for positioning the aperture blades of the aperture device 13, control information for positioning the C-arm, control information for positioning the top board 31, and the like. The system control information includes, as control information related to an electronic X-ray aperture, parameters related to the position of a mask (electronic shutter) applied to an aperture area included in an X-ray image. The parameters include adjustment parameters used in the adjustment process by the aperture region adjustment function 515 and adjustment parameters used for the mask (electronic shutter) by the display control function 516.

[0022] By implementing the determination function 513, the processing circuit 51 determines whether or not to use the extraction result of the image-based aperture region extraction process for the X-ray image based on the imaging conditions corresponding to the X-ray image. The extraction result of the image-based aperture region extraction process is called first aperture position information.

[0023] By implementing the image-based extraction function 514, the processing circuit 51 performs an image-based aperture region extraction process on the X-ray image to obtain first aperture position information. The image-based aperture region extraction process is a process for processing the X-ray image to extract an aperture region, which is an image region where X-rays are blocked by the aperture blades of the aperture device 13. This is distinguished from the system control information-based extraction process described later.

[0024] By implementing the aperture region adjustment function 515, the processing circuit 51 calculates final aperture position information of the aperture region included in the X-ray image. For example, when the determination function 513 determines that the extraction result (first aperture position information) of the image-based aperture region extraction process is to be used, the processing circuit 51 adjusts the first aperture position information based on the system control information to calculate the final aperture position information of the aperture region included in the X-ray image. More specifically, the processing circuit 51 calculates position information (second aperture position information) of the aperture region based on the system control information, and adjusts the first aperture position information based on the second aperture position information. When it is determined that the first aperture position information is not to be used, the processing circuit 51 sets the second aperture position information obtained based on the system control information as the final aperture position information.

[0025] By implementing the display control function 516, the processing circuit 51 displays various data via the display device 55. The processing circuit 51 can also perform various image processing on the X-ray image and display the X-ray image after image processing. The image processing includes various image processing such as negative-positive inversion (black and white inversion) and masking (electronic shutter), as well as gradation processing, image filter processing, and noise reduction processing. For example, the processing circuit 51 performs negative-positive inversion on the X-ray image to generate a negative-positive inverted image, and based on the final aperture position information, masks the aperture area included in the negative-positive inverted image to generate a masked image, and displays the masked image.

[0026] The storage device 52 is a storage device such as a semiconductor storage device, such as a hard disk drive (HDD) or a solid state drive (SSD), that stores various data. For example, the storage device 52 stores the X-ray image transmitted from the X-ray detector 14, the imaging conditions set by the parameter setting function 512, and system control information.

[0027] The input device 53 receives various input operations from an operator, converts the received input operations into electrical signals, and outputs the electrical signals. As the input device 53, for example, a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touch pad, a touch panel display, or the like can be appropriately used. The input device 53 is not limited to a physical device, and may be a computer terminal connected via a communication device 54, a tablet terminal capable of wireless communication, or the like.

[0028] The communication device 54 performs data communication with other computers via wired or wireless communication (not shown).

[0029] The display device 55 displays various data by implementing a display control function 516 of the processing circuit 51. As the display device 55, for example, a CRT display, a liquid crystal display, an organic EL display, an LED display, a plasma display, or any other display known in the art can be appropriately used. The display device 55 may also be a projector.

[0030] The system control circuit 56 has a processor as a hardware resource. The system control circuit 56 controls the entire X-ray diagnostic apparatus 1 by executing a control program. Specifically, the system control circuit 56 supplies a control signal to the high voltage generator 12 so as to perform X-ray exposure according to the X-ray conditions. The high voltage generator 12, which has received the control signal, applies a high voltage according to the control signal to the X-ray tube 11, and the X-ray tube 11 generates X-rays in response to the high voltage. The system control circuit 56 supplies a control signal according to the aperture control information to the aperture device 13. The aperture device 13, which has received the control signal, moves the aperture blades according to the control signal to adjust the irradiation field. In addition, the system control circuit 56 causes the processing circuit 51 to realize functions 511 to 516.

[0031] The above-mentioned configuration of the X-ray diagnostic apparatus 1 is an example, and is not limited thereto, and various modifications are possible. For example, the system control circuit 56 and the processing circuit 51 may be configured as a single circuit, rather than separate circuits. In addition, the processing circuit 51, the storage device 52, the input device 53, the communication device 54, the display device 55, and the system control circuit 56 do not all need to be mounted on a single computer, and may be distributed and mounted on multiple computers.

[0032] Next, an example of the operation of the X-ray diagnostic apparatus 1 according to this embodiment will be described in detail.

[0033] The X-ray diagnostic device 1 according to this embodiment performs automatic shuttering, which is an automatic process of the electronic shutter, stably and with high accuracy. In the X-ray diagnostic device 1, X-ray images are inverted from negative to positive and then interpreted. The aperture area of ​​the negative-positive inverted image is displayed in white, making it difficult to interpret the radiation field area that is the subject of interpretation. The electronic shutter is a technique for masking the aperture area included in an X-ray image such as a negative-positive inverted image, and the auto shutter is an application of the electronic shutter that automatically identifies the aperture area from the X-ray image. The aperture area is displayed in black by the electronic shutter, making it easier to interpret the radiation field area.

[0034] There is a method of using the position information of the second aperture area calculated based on the aperture control information as the final aperture position information, which is the input information for the electronic shutter. In an ideal case where there is no positional accuracy problem of the aperture blades, the position information of the second aperture area accurately represents the position information of the aperture area included in the X-ray image.

[0035] Fig. 2 is a diagram showing an example of the positional relationship between an aperture area 62, an exposure field area 63, and a frame line 64 of an electronic shutter in an X-ray image 61 when the arrangement angle of the X-ray tube 11 is 0 degrees. Fig. 2 illustrates an ideal case where there is no positional accuracy defect of the aperture blades. As shown in Fig. 2(a), a frame line 64 of an electronic shutter is set in an X-ray image 61, and a mask is applied outside the frame line 64, and a mask is not applied inside the frame line 64. Since the aperture area 62 is not reflected inside the frame line 64, a high-quality reading image can be provided.

[0036] For example, due to poor positional accuracy caused by mechanical factors such as aging, gravity, and installation failure, the diaphragm blades may not move to the intended position even if they move accurately according to the diaphragm control information, and thus the irradiation field may not be formed at the intended position. For example, as shown in (b) of FIG. 3, the X-ray tube 11 may be tilted from 0 degrees, causing poor positional accuracy of the diaphragm blades due to gravity, etc. In this case, the position of the irradiation field area 63 in the X-ray image 61 is shifted, and the diaphragm area 62 is reflected inside the frame line 64. In this case, the diaphragm area 62 part located inside the frame line 64 is not masked, and the irradiation field area 63 part located outside the frame line 64 is masked.

[0037] There is a method of using the first aperture position information obtained by image-based extraction processing as the final aperture position information, which is the input information for the electronic shutter. As an image-based extraction processing, image recognition processing of the aperture area using AI is highly accurate, but the accuracy varies depending on the form of various image areas included in the X-ray image, for example, when the irradiation field area is small, the aperture area cannot be correctly recognized.

[0038] The processing circuit 51 adjusts the first aperture position information obtained by the image-based extraction process based on the system control information including the aperture position information, and stably and highly accurately obtains the final aperture position information, which is the input information for the electronic shutter. According to this embodiment, for example, as shown in (b) of FIG. 4, even if the position accuracy of the aperture blades is poor due to gravity or the like, it is possible to accurately set a frame line 64 inside an exposure field region 63 according to the position of an aperture region 62 included in an X-ray image 61.

[0039] FIG. 5 is a diagram showing an overview of processing by the processing circuit 5 according to this embodiment. As shown in FIG. 5, the processing circuit has an X-ray image acquisition unit, a system control information acquisition unit, and a target area acquisition unit. The X-ray image acquisition unit acquires an X-ray image. The system control information acquisition unit acquires system control information related to capturing an X-ray image. The target area acquisition unit acquires a target area representing at least one of a narrow area and an irradiation field area in the X-ray image based on the X-ray image and the system control information. The target area acquisition unit includes a first extraction unit, a second extraction unit, and a calculation unit. The first extraction unit extracts a first candidate area included in the X-ray image by image processing. The second extraction unit extracts a second candidate area included in the X-ray image based on the system control information. The calculation unit finds the target area based on the first candidate area and the second candidate area. The first extraction unit corresponds to an image-based extraction function 514. The second extraction unit and the calculation unit correspond to a narrow area function 515. The first extraction unit, the second extraction unit, and the calculation unit perform an adjustment process for the target region.

[0040] FIG. 6 is a diagram showing an outline of the adjustment process by the processing circuit. As shown in FIG. 6, the processing circuit 5 obtains first aperture position information obtained by image-based extraction processing and second aperture position information obtained by system control information-based extraction processing. The first aperture position information is position information of the aperture area included in the X-ray image obtained by performing image processing on the X-ray image by the image-based extraction function 514. The second aperture position information is position information of the aperture area included in the X-ray image calculated by the adjustment function 515 based on system control information related to the X-ray aperture, for example, aperture control information. Then, the processing circuit 5 obtains third aperture position information, which is the above-mentioned final aperture position information, based on the first aperture position information and the second aperture position information. In addition, the first aperture position information, the second aperture position information, and the third aperture position information are the position information of the aperture area, but the aperture area and the irradiation field area are in a two-sided relationship as shown in Figs. 2 to 4, etc., so by obtaining the position information of the aperture area, the position information of the irradiation field area can be obtained, and conversely, by obtaining the position information of the irradiation field area, the position information of the aperture area can be obtained, that is, the position information of the aperture area and the position information of the irradiation field area can be regarded as the same. Therefore, obtaining the position information of the aperture area is equivalent to obtaining the position information of the irradiation field area, and obtaining the position information of the irradiation field area is equivalent to obtaining the position information of the aperture area. In the following description, only obtaining the position information of the aperture area is described. However, the following embodiment can be implemented by replacing the position information of the aperture area with the position information of the irradiation field area, or the position information of the aperture area and the position information of the irradiation field area.

[0041] Next, a description will be given of an example of the X-ray examination process performed by the X-ray diagnostic apparatus 1. The flow of the X-ray examination is roughly divided into two methods.

[0042] (First X-ray inspection) FIG. 7 is a diagram showing a processing example of the first X-ray examination by the X-ray diagnostic device 1. As shown in FIG. 7, the processing circuitry 51 sets parameters such as imaging conditions by implementing the parameter setting function 512 (step SA1). The imaging conditions set in step SA1 include an examination protocol, a procedure, X-ray conditions, and division settings. The X-ray conditions include a tube current value, a tube voltage value, a tube current time product, an X-ray exposure time, and irradiation field information. The irradiation field information is information about the irradiation field formed by a plurality of aperture blades of the aperture device 13. Specifically, the irradiation field information includes the irradiation field size and the irradiation field position. The irradiation field size is defined by the width and length of the irradiation field. The irradiation field position is defined by the position of the irradiation field in the X-ray image. The irradiation field information may be set by an operator in step SA1, or may be automatically determined by the processing circuitry 51, etc., such as when the irradiation field is automatically determined by the processing circuitry 51, etc., following a catheter, a guide wire, etc. during X-ray fluoroscopy. The imaging conditions are not limited to those mentioned above, and various parameters such as the positions and angles of the X-ray tube 11 and the tabletop 31, the FOV size, the image size, etc. can be set.

[0043] As other parameters set in step SA1, parameters of aperture control information included in the system control information are set.

[0044] The aperture control information is calculated based on the irradiation field information. Specifically, the aperture control information is specified by the X-coordinate Xsys, the Y-coordinate Ysys of the reference point of the irradiation field area, the width Wsys of the irradiation field area, and the length Hsys of the irradiation field area. The origin of the coordinate system is set, for example, to the upper left corner of the X-ray image, and the reference point of the irradiation field area is set to the upper left corner of the irradiation field area in the X-ray image. That is, Xsys is equal to the X-direction distance from the upper left corner of the X-ray image to the upper left corner of the irradiation field area, and Ysys is equal to the Y-direction distance from the upper left corner of the X-ray image to the upper left corner of the irradiation field area. Based on Xsys, Ysys, Wsys, and Hsys, the positions of the left diaphragm blade (hereinafter, left blade), the right diaphragm blade (hereinafter, right blade), the upper diaphragm blade (hereinafter, upper blade), and the lower diaphragm blade (hereinafter, lower blade) are expressed. For example, the position of the left wing is expressed as Xsys, the position of the right wing is expressed as Xsys+Wsys, the position of the upper wing is expressed as Ysys, and the position of the lower wing is expressed as Ysys+Hsys.

[0045] As described above, the parameters according to this embodiment include the parameters of the aperture control information, as well as the parameters related to the position of the mask (electronic shutter) applied to the aperture region included in the X-ray image as control information related to the electronic X-ray aperture. The parameters include adjustment parameters used in the adjustment process by the aperture region adjustment function 515 and adjustment parameters used for the mask (electronic shutter) by the display control function 516.

[0046] Fig. 8 is a diagram showing an example of a setting screen 71 for adjustment parameters. As shown in Fig. 8, the setting screen 71 is a GUI (Graphical User Interface) screen including a setting area 72, a SYS button 73, and an AI button 74. The SYS button 73 is a GUI button for switching the input field of the setting area 72 from the input field for adjustment parameters of step SA6 to the input field for adjustment parameters of step SA7. The AI ​​button 74 is a GUI button for switching the input field of the setting area 72 from the input field for adjustment parameters of step SA7 to the input field for adjustment parameters of step SA6. Fig. 8 illustrates an example in which the AI ​​button 74 is pressed.

[0047] As shown in FIG. 8, the setting area 72 is a setting area for adjustment parameters. In the setting area 72, a schematic diagram of the aperture area and the irradiation field area in the X-ray image is displayed, and the schematic diagram displays input fields for various adjustment parameters. The "common" input field is an input field for adjustment parameters common to steps SA6 and SA7. That is, the "common" input field is an input field for parameters of shutter control information. The "AI" input field is an input field for adjustment parameters used in step SA6. For example, the "common" input field on the upper side of the setting area 72 is input with the value of the adjustment parameter of the electronic shutter for the aperture area of ​​the upper blade, and the "AI" input field is input with the value of the adjustment parameter for the first aperture position information of the upper blade. Note that when the SYS button 73 is pressed, the "system" input field is displayed instead of the "AI" input field. As a result, the value of the system-based adjustment parameter for each blade is input in the setting area 72.

[0048] The values ​​of all the parameters set in step SA1 are recorded in an electronic file such as an XML (Extensible Markup Language) file, and the electronic file is stored in the storage device 52. The values ​​of the parameters stored in the electronic file can be edited by an operator via an input device 53 or the like. Furthermore, editing restrictions may be imposed depending on the type of parameter.

[0049] When step SA1 is performed, the system control circuit 56 performs X-ray photography according to the photography conditions, and the processing circuit 51 acquires an X-ray image by implementing the acquisition function 511 (step SA2). In step SA2, the position of the aperture blades of the aperture device 13 is adjusted according to the aperture control information. X-ray photography may be performed by one-shot photography or by sequential photography. In one-shot photography, one X-ray image is obtained using a relatively high tube voltage. In sequential photography, time-series X-ray images are obtained using a relatively low tube voltage. Sequential photography is also called X-ray fluoroscopy. In this embodiment, steps SA3 and after are repeated for each X-ray image.

[0050] When step SA2 is performed, the processing circuit 51 determines whether or not to execute image-based aperture region extraction processing by implementing the determination function 513 (step SA3). In step SA3, the processing circuit 51 performs a determination process based on the shooting conditions set in step SA1. Step SA3 is equivalent to determining whether or not to use the first aperture position information obtained by the image-based extraction function 514 for calculating final aperture position information. Details of the determination process will be described later.

[0051] When it is determined in step SA3 that the image-based extraction process of the aperture area is to be executed (step SA3: YES), the processing circuit 51 executes the image-based extraction process of the aperture area (image-based extraction process) by implementing the image-based extraction function 514 (step SA4). In step SA4, the processing circuit 51 performs the image-based extraction process on the X-ray image generated in step SA2 to obtain first aperture position information that is position information of the aperture area included in the X-ray image. The image-based extraction process may use image analysis such as a Hough transform, or may use image recognition using AI. In the image recognition using AI, the processing circuit 51 recognizes the aperture area included in the X-ray image by utilizing a machine learning model. Hereinafter, the image-based extraction process is assumed to be image recognition using AI.

[0052] FIG. 9 is a diagram showing a schematic input / output relationship of a trained model used for image recognition using AI. As shown in FIG. 9, the trained model is trained to input an X-ray image and output first aperture position information. The trained model may be a neural network. The input X-ray image may be an original X-ray image acquired from the X-ray detector 14, or an X-ray image that has been preprocessed, such as noise removal. The input X-ray image may be a downsampled X-ray image having a smaller image size than the original X-ray image. The aperture position information output from the trained model may be used as the first aperture position information as it is, or the aperture position information output from the trained model after being arbitrarily adjusted by system control information or the like may be used as the first aperture position information.

[0053] When step SA4 is performed, the processing circuit 51 calculates position information of the aperture region (second aperture position information) based on the aperture control information by implementing the aperture region adjustment function 515 (step SA5). When step SA5 is performed, the processing circuit 51 adjusts the first aperture position information based on the second aperture position information and the system control information (step SA6). In step SA6, the processing circuit 51 compares the first aperture position information with the second aperture position information, and if the first aperture position information deviates from the second aperture position information by more than a threshold value, adjusts the first aperture position information based on the second aperture position information and the system control information. The adjustment process in step SA6 can also be expressed as an electronic shaping process of the aperture region.

[0054] On the other hand, if it is determined in step SA3 that the image-based aperture area extraction process is not to be performed (step SA3: NO), the processing circuit 51 realizes the aperture area adjustment function 515 to calculate the position information of the aperture area based on the aperture control information (step SA7).

[0055] When step SA6 or step SA7 is performed, the processing circuit 51 performs negative-positive inversion of the X-ray image by implementing the display control function 516 (step SA8). The X-ray image after negative-positive inversion is called a negative-positive image. When step SA8 is performed, the processing circuit 51 performs a mask (electronic shutter) on the aperture area of ​​the negative-positive image generated in step SA8 based on the final aperture position information obtained in step SA6 or step SA7 by implementing the display control function 516 (step SA9). The negative-positive inversion image to which the mask (electronic shutter) has been applied is called a mask image. When step SA9 is performed, the processing circuit 51 performs a display control function 516 to display the mask image generated in step SA9 (step SA10).

[0056] Fig. 10 is a diagram showing a typical flow of processing in steps SA8 to SA9. As shown in Fig. 10, in an X-ray image 61 before negative-positive inversion SA8, a gradation curve showing the correspondence between an input pixel value (projection value) and an output pixel value (grayscale value) is set so that the higher the input pixel value, the higher the output pixel value. Note that, a lower output pixel value is assigned a lower grayscale value corresponding to white, and a higher output pixel value is assigned a higher grayscale value corresponding to black. In an X-ray image 61 before negative-positive inversion SA8, specifically, a relatively dark grayscale value is assigned to an aperture region 62, and a relatively light grayscale value is assigned to an exposure field region 63.

[0057] Next, the processing circuit 51 performs negative-positive inversion SA8 on the X-ray image 61 as shown in Fig. 10 to generate a negative-positive image 61B. In the negative-positive inversion SA8, the gradation curve is inverted. That is, the gradation curve is set so that the lower the input pixel value, the higher the output pixel value. In the negative-positive image 61B, a relatively light gradation value is assigned to the aperture region 62, and a relatively dark gradation value is assigned to the exposure field region 63.

[0058] Next, as shown in FIG. 10, the processing circuit 51 executes masking (electronic shutter) SA9 based on the negative-positive image and the final aperture position information obtained in step SA6 or SA7 to generate a mask image 61C. In step SA9, the processing circuit 51 first sets a frame line 64 of the electronic shutter on the negative-positive image based on the final aperture position information. The frame line 64 is set at the position of the aperture area 62, in other words, at the boundary between the aperture area 62 and the irradiation field area 63. The frame line 64 may be set at a position that matches the final aperture position information, or may be set at a position that is a predetermined distance inside the position that matches the final aperture position information. Next, the processing circuit 51 applies a mask to the image area outside the frame line 64, that is, the aperture area 62, to which a specific gradation value is assigned. The specific gradation value is set to a gradation value corresponding to black.

[0059] According to this embodiment, the frame line 64 is set based on the position information obtained with high accuracy based on the first aperture position information and the second aperture position information, so that it is possible to reduce the aperture area 62 from being reflected in the frame line 64 or the exposure field area 63 from being overlapped with the mask. This makes it possible to provide a high-quality interpretation image.

[0060] The electronic shutter is not limited to being applied to a negative-positive image, but may be applied to any X-ray image in which a stop region is depicted, such as an X-ray image before negative-positive inversion.

[0061] When step SA10 is performed, the first X-ray inspection ends.

[0062] Next, the details of the determination process by the determination function 513 executed in step SA3 will be described.

[0063] Fig. 11 is a diagram showing an example of the determination process by the determination function 513 executed in step SA3. As shown in Fig. 11, the processing circuitry 51 determines whether or not to use the first aperture position information based on the examination protocol, the procedure, the X-ray conditions, and the division setting included in the imaging conditions.

[0064] As shown in FIG. 11, first, the processing circuit 51 checks the examination protocol (step SB1). In step SB1, it is checked whether the examination protocol of the current examination is suitable for image-based extraction processing. For example, in step SA1, an OK flag indicating that the examination protocol is "suitable for image-based extraction processing" or an NG flag indicating that the examination protocol is "not suitable for image-based extraction processing" is set as a parameter. For example, an NG flag may be set for an upper gastrointestinal examination, and an OK flag may be set for a simple bone examination. When an OK flag is set for an examination protocol, it is determined that the examination protocol is not unsuitable for image-based extraction processing, and when an NG flag is set for an examination protocol, it is determined that the examination protocol is unsuitable for image-based extraction processing.

[0065] If it is not confirmed in step SB1 that the examination protocol is unsuitable for the image-based extraction process (step SB1: OK), the processing circuit 51 checks the procedure (step SB2). In step SB2, it is confirmed that the procedure of the current examination is a non-spot view and is one of one-shot photography, sequence photography (movie photography), and DA photography (angiography). For example, if spot view is set as the procedure in step SA1, it is determined in step SB2 that the procedure of the current examination is unsuitable for the image-based extraction process. For example, if spot view is not set as the procedure in step SA1 and one-shot photography, sequence photography, and DA photography are set, it is determined in step SB2 that the procedure of the current examination is not unsuitable for the image-based extraction process. For example, if spot view is not set as the procedure in step SA1 and one-shot photography, sequence photography, and DA photography are not set, it is determined in step SB2 that the procedure of the current examination is unsuitable for the image-based extraction process. For example, if spot view is not set as the procedure in step SA1 and one-shot photography, sequence photography, and DA photography are not set, it is determined in step SB2 that the procedure of the current examination is unsuitable for the image-based extraction process. In addition, DSA imaging, tomosynthesis imaging, and long-length imaging may also be determined to be unsuitable for image-based extraction processing.

[0066] If it is not confirmed in step SB2 that the procedure is unsuitable for image-based extraction processing (step SB2: OK), the processing circuit 51 checks the X-ray conditions (step SB3). In step SB3, it is confirmed whether the X-ray conditions for the current examination are set to ON for ABC (Auto Brightness Control) or ATR (Auto Tube Voltage Regulation). For example, if ABC or ATR is set to ON in step SA1, it is determined in step SB3 that the X-ray conditions for the current examination are not unsuitable for image-based extraction processing. If both ABC and ATR are set to OFF in step SA1, it is determined in step SB3 that the X-ray conditions for the current examination are unsuitable for image-based extraction processing.

[0067] In step SB3, the processing circuit 51 may determine whether the irradiation field size, which is an X-ray condition, is unsuitable for image-based extraction processing. If the irradiation field size is smaller than the first threshold, it may be determined that it is unsuitable for image-based extraction processing. This is because in the case of small irradiation field area photography in which the aperture area in the X-ray image is large and there is almost no irradiation field area, the recognition accuracy of the aperture area is not high in image recognition by AI. Conversely, if the irradiation field size is larger than the second threshold, it may be determined that it is unsuitable for image-based extraction processing. This is because in the case of small irradiation field area photography in which the aperture area in the X-ray image is large and there is almost no irradiation field area, the recognition accuracy of the aperture area is not high in image recognition by AI.

[0068] If it is not confirmed in step SB3 that the X-ray conditions are unsuitable for image-based extraction processing (step SB3: OK), the processing circuit 51 checks the segmentation settings (step SB4). In step SB4, it is confirmed that the imaging method for the current examination is non-segmented imaging. For example, if the imaging method is not set to segmented imaging in step SA1, it is determined in step SB4 that the segmentation settings for the current examination are not unsuitable for image-based extraction processing. If the imaging method is set to segmented imaging in step SA1, it is determined in step SB4 that the segmentation settings for the current examination are unsuitable for image-based extraction processing.

[0069] If it is not confirmed in step SB4 that the division setting is unsuitable for the image-based extraction process (step SB4: OK), the processing circuit 51 determines to execute the image-based extraction process (step SA3: YES).

[0070] On the other hand, if the examination protocol is confirmed in step SB1 to be unsuitable for image-based extraction processing (step SB1: NG), if the procedure is confirmed in step SB2 to be unsuitable for image-based extraction processing (step SB2: NG), if the X-ray conditions are confirmed in step SB3 to be unsuitable for image-based extraction processing (step SB3: NG), or if the division settings are confirmed in step SB4 to be unsuitable for image-based extraction processing (step SB4: NG), the processing circuit 51 determines not to perform image-based extraction processing (step SA3: NO).

[0071] This completes the determination process by the determination function 513 executed in step SA3.

[0072] The order of the above-mentioned determination processes is not limited to the order of steps SB1→SB2→SB3→SB4, and may be any order. Also, various determinations can be made instead of or in addition to the above-mentioned steps SB1 to SB4.

[0073] For example, the processing circuit 51 may determine not to execute the image-based extraction process when the tabletop structure, such as the tabletop 31, the tabletop support structure, or the tabletop accessory, enters the irradiation field. This is because the tabletop structure is a high X-ray absorber and a linear structure, and therefore may be confused with an aperture blade in image recognition by AI. The tabletop support structure may be an arm that supports the tabletop 31 or a frame that reinforces the tabletop 31, and the tabletop accessory may be, for example, a handle provided on the tabletop 31 for the subject to grasp. In a C-arm type X-ray fluoroscopy device, the position and angle (hereinafter referred to as the structural arrangement parameter value) of the X-ray tube 11 and the tabletop 31 in combination with the FOV determines whether the tabletop structure enters the irradiation field. For example, the combination of the AP / PA angle, the RAO angle, the LAO angle, the tabletop height, and the FOV determines whether the left and right ends of the tabletop enter the irradiation field. In the case of the over-table method or under-table method, whether or not the top structure, such as the left and right ends of the top, falls within the irradiation field is determined by the combination of the left and right positions of the top and the FOV.

[0074] The processing circuitry 51 holds a table that records combinations of structural layout parameter values ​​and FOVs that cause a tabletop structure to fall within the radiation field. If the combination of structural layout parameter values ​​and FOVs associated with the X-ray image to be processed is recorded in the table, the processing circuitry 51 determines not to execute image-based extraction processing, and if not, determines to execute image-based extraction processing.

[0075] Next, the details of the adjustment process by the aperture region adjustment function 515 executed in step SA6 will be described. The processing circuit 51 selects an adjustment algorithm according to the way of defining the final aperture position information. There are two ways of definition: when the exposure field region is rectangular and when it is square. The adjustment process when the exposure field region is rectangular is called the first adjustment process, and the adjustment process when the exposure field region is square is called the second adjustment process.

[0076] FIG. 12 is a diagram showing a first adjustment processing example by the aperture region adjustment function 515 executed in step SA6. FIG. 13 is a diagram showing a definition of the position information of the aperture region in the first adjustment processing example. As shown in FIG. 13, when the irradiation field region is rectangular, the position information of the aperture region is defined using the X coordinate of the reference point P1, the Y coordinate of the reference point P1, the width W of the irradiation field region, and the height H of the irradiation field region. The reference point P1 is set, for example, to the upper left corner point of the four corners of the irradiation field region. In this case, the coordinates of the reference point P1 are represented by (X, Y). The coordinates of the lower left corner point P2 are defined as (X, Y+H), the coordinates of the lower right corner point P3 are defined as (X+W, Y+H), and the coordinates of the upper right corner point P4 are defined as (X+W, Y). That is, the position of the left wing corresponds to X, the position of the right wing corresponds to X+W, the position of the upper wing corresponds to Y, and the position of the lower wing corresponds to Y+H.

[0077] As shown in Fig. 12, when the final aperture position information is defined by the X coordinate of the reference point, the Y coordinate of the reference point, the horizontal width of the irradiation field area, and the vertical width of the irradiation field area, the processing circuitry 51 executes fine adjustment, adjustment by the maximum FOV, comparison adjustment with the position information of the aperture area based on the aperture control information, rejection by the minimum FOV and / or confidence flag, and confirmation of the aperture operation during sequence shooting, in order, for the first aperture position information. The following will be described in detail.

[0078] As shown in FIG. 12, the processing circuit 51 performs fine adjustment of the extraction result (first aperture position information) of the image-based extraction process (step SC1). In step SC1, the processing circuit 51 adjusts the output values ​​Xai, Yai, Wai, and Hai of the first aperture position information obtained in step SA4 (hereinafter referred to as the current output values ​​of the first aperture position information) based on the adjustment parameters set in step SA1. The fine adjustment in step SC1 is performed to correct a characteristic specific to image recognition using AI, for example, in which the first aperture position information tends to be biased toward the upper left in image recognition using AI. The adjusted values ​​of the first aperture position information (hereinafter referred to as the adjusted values) are denoted as Xt, Yt, Wt, and Ht.

[0079] After step SC1, the processing circuit 51 performs adjustment based on the maximum FOV (step SC2). In step SC2, the processing circuit 51 adjusts the adjustment values ​​Xt, Yt, Wt, and Ht obtained in step SC1 based on the ratio of the minimum amount of aperture reflection to the maximum FOV. More specifically, based on the adjustment values ​​Xt, Yt, Wt, and Ht, the reflection amounts of the left blade, right blade, upper blade, and lower blade in the X-ray image are calculated, and each reflection amount is compared with the ratio of the minimum amount of aperture reflection to the maximum FOV. If the reflection amount is small compared to the ratio, the adjustment values ​​Xt, Yt, Wt, and Ht are adjusted based on the output values ​​of the second aperture position information (hereinafter, referred to as the current output values ​​of the second aperture position information) Xsys, Ysys, Wsys, and Hsys. The adjustment in step SC2 may be performed in the order of the left blade, right blade, upper blade, and lower blade. By the process of step SC2, even if the aperture is instructed to be fully open but is not fully open at the time of shooting, the electronic shutter is set to be fully open.

[0080] After step SC2, the processing circuit 51 performs a comparison adjustment with the aperture position information (second aperture position information) based on the aperture control information (step SC3). In step SC3, the processing circuit 51 calculates a difference value between the first aperture position information and the second aperture position information for each aperture blade, and compares the difference value of each aperture blade with a predetermined difference threshold. The difference threshold is set for each aperture blade. A blade that is greater than the difference threshold is adjusted based on the second aperture position information. If the difference value is greater than the difference threshold, the position of the blade is replaced with a value based on the second aperture position information. Note that if the difference value is greater than the difference threshold, the position of the blade may be replaced with a value based on the first aperture position information and the second aperture position information, for example, an intermediate value.

[0081] The difference value compared with the difference threshold is, for example, specified by the absolute value of the subtraction value of the second aperture position information from the first aperture position information of the blade. The difference value may be the subtraction value itself, that is, a value with + or -. In this case, if the actual irradiation field is always on the outside with respect to the system control information as an installation policy, if the first aperture position information is closer to the image center than the second aperture position information, it can be reliably determined that there is an abnormality. The adjustment in step SC3 may be performed in the order of the left blade, right blade, upper blade, and lower blade. The difference threshold may also be set according to the position and angle of the top board 31 and the X-ray tube 11. For example, a table may be created in which the difference threshold is recorded for each combination of the position and angle of the top board 31 and the X-ray tube 11 for each of the left blade, right blade, upper blade, and lower blade. The processing circuitry 51 can refer to the table and read out the difference threshold suitable for the combination of the current examination. The difference threshold is not limited to a table, and may be determined by a calculation formula or a machine learning model,

[0082] After step SC3, the processing circuit 51 performs rejection based on the minimum FOV and the confidence flag (step SC4). In step SC4, if the current output value Wsys of the second aperture position information is smaller than the minimum width of the FOV or if the current output value Hsys is smaller than the minimum height of the FOV, the processing circuit 51 replaces the adjustment values ​​Xt, Yt, Wt, and Ht with the current output values ​​Xsys, Ysys, Wsys, and Hsys of the second aperture position information, respectively. Note that, if the confidence flag is zero, the processing circuit 51 may replace the adjustment values ​​Xt, Yt, Wt, and Ht with the current output values ​​Xsys, Ysys, Wsys, and Hsys, respectively.

[0083] When step SC4 is performed, the processing circuit 51 checks the aperture operation during sequence imaging (step SC5). In step SC5, if the current output value Xsys of the second aperture position information matches the previous output value Xsysl (the output value of the second aperture position information calculated in step SA5 for the X-ray image to be processed immediately before), and the current output value Ysys matches the previous output value Ysysl, and the current output value Wsys matches the previous output value Wsysl, and the current output value Hsys matches the previous output value Hsysl, the processing circuit 51 replaces the adjustment values ​​Xt, Yt, Wt, and Ht with the previous output values ​​Xsysl, Ysysl, Wsysl, and Hsysl, respectively.

[0084] After step SC5, the processing circuit 51 stores the previous values ​​(step SC6). In step SC6, the processing circuit 51 stores the current output values ​​Xt, Yt, Wt, and Ht as the previous output values ​​Xoutl, Youtl, Woutl, and Houtl of the final aperture position information (the output values ​​of the final position information calculated in step SA6 for the X-ray image to be processed one time before). In addition, the processing circuit 51 stores the current output values ​​Xsys, Ysys, Wsys, and Hsys of the second aperture position information as the previous output values ​​Xsysl, Ysysl, Wsysl, and Hsysl of the second aperture position information.

[0085] After step SC6, the processing circuit 51 outputs the final aperture position information (step SC7). In step SC7, the processing circuit 51 replaces the current output values ​​Xt, Yt, Wt, and Ht with the current output values ​​Xout, Yout, Wout, and Hout of the final aperture position information and outputs them.

[0086] With this, the first adjustment process is completed.

[0087] FIG. 14 is a diagram showing a second adjustment processing example by the aperture region adjustment function 515 executed in step SA6. FIG. 15 is a diagram showing the definition of the position information of the aperture region in the second adjustment processing example. As shown in FIG. 15, when the irradiation field region is a rectangle, the position information of the aperture region is defined using the X coordinate and the Y coordinate of each point of the four corners of the irradiation field region. In this case, it is defined as the upper left corner point P1 (X1, Y1), the lower left corner point (X2, Y2), the lower right corner point (X3, Y3), and the upper right corner point (X4, Y4). That is, the position of the left wing is defined by X1, Y1, X2, and Y2, the position of the right wing is defined by X3, Y3, X4, and Y4, the position of the upper wing is defined by X1, Y1, X4, and Y4, and the position of the lower wing is defined by X2, Y2, X3, and Y3.

[0088] In addition, in the second adjustment processing example, Xsys, Ysys, Wsys, and Hsys are used as the second aperture position information. Therefore, for example, in the left side of the irradiation field area, MIN(X1,X2), MAX(X1,X2), and AVERAGE(X1,X2) may be used to generate a straight line parallel to X, Y, W, and H, or the distance between the straight line and points P1 and P2 may be obtained to obtain MIN, MAX, AVERAGE, and the logical product or logical sum of area value judgment.

[0089] 14, when the final aperture position information is defined by the X and Y coordinates of each point at the four corners, the processing circuit 51 sequentially performs adjustment based on the maximum FOV for the first aperture position information, comparison adjustment with the position information of the aperture region based on the aperture control information, rejection based on the minimum FOV and / or confidence flag, and confirmation of the aperture operation during sequence shooting. The details will be described below.

[0090] As shown in FIG. 14, the processing circuit 51 performs fine adjustment of the extraction result (first aperture position information) of the image-based extraction process (step SD1). For example, the processing circuit 51 performs current output values ​​X1ai,...,X4ai,Y1ai,...,Y4ai of the first aperture position information based on the adjustment parameters set in step SA1. Note that in step SD1, the processing circuit 51 may replace the current output values ​​X1ai,...,X4ai,Y1ai,...,Y4ai of the first aperture position information obtained in step SA4 with adjustment values ​​X1t,...,X4t,Y1t,...,Y4t of the first aperture position information. That is, in the second adjustment process, fine adjustment of the first aperture position information may not be performed.

[0091] After step SD1, the processing circuit 51 adjusts the asymmetry (step SD2). Note that the processing circuit 51 does not have to adjust the asymmetry in step SD2.

[0092] After step SD2, the processing circuit 51 performs adjustment based on the maximum FOV (step SD3). In step SD3, the processing circuit 51 adjusts the adjustment values ​​X1t,...,X4t,Y1t,...,Y4t obtained in step SD1 based on the ratio of the minimum amount of aperture reflection to the maximum FOV. More specifically, based on the adjustment values ​​X1t,...,X4t,Y1t,...,Y4t, the processing circuit 51 calculates the amount of reflection of the left wing, right wing, upper wing, and lower wing in the X-ray image, and compares each reflection amount with the ratio of the minimum amount of aperture reflection to the maximum FOV. If the amount of reflection is small compared to the ratio, the adjustment values ​​X1t,...,X4t,Y1t,...,Y4t are adjusted based on the current output values ​​Xsys, Ysys, Wsys, Hsys of the second aperture position information. The adjustment in step SC2 should be performed in the order of the left blade, right blade, upper blade, and lower blade. Even if the aperture is instructed to be fully open by the process in step SD3 but is not fully open at the time of shooting, the electronic shutter will be fully open.

[0093] After step SD3, the processing circuit 51 performs a comparison adjustment with the aperture position information (second aperture position information) based on the aperture control information (step SD4). In step SD4, the processing circuit 51 calculates the difference between the first aperture position information and the second aperture position information for each blade, and compares the difference for each blade with a predetermined difference threshold. Any blade whose difference is larger than the difference threshold is adjusted based on the second aperture position information. The adjustment in step SD4 is preferably performed in the order of the left blade, right blade, upper blade, and lower blade.

[0094] When step SD4 is performed, the processing circuit 51 performs rejection based on the minimum FOV and the confidence flag (step SD5). In step SD5, if the current output value Wsys of the second aperture position information is smaller than the minimum width of the FOV or if the current output value Hsys is smaller than the minimum height of the FOV, the processing circuit 51 replaces the adjustment values ​​X1t,...,X4t,Y1t,...,Y4t with values ​​based on the current output values ​​Xsys, Ysys, Wsys, and Hsys of the second aperture position information. That is, X1t is replaced with Xsys, Y1t is replaced with Ysys, X2t is replaced with Xsys, Y2t is replaced with Ysys+Hsys, X3t is replaced with Xsys+Wsys, Y3t is replaced with Ysys+Hsys, X4t is replaced with Xsys+Wsys, and Y4t is replaced with Ysys. When the confidence flag is zero, the processing circuit 51 may replace the adjustment values ​​X1t, . . ., X4t, Y1t, . . ., Y4t with values ​​based on the current output values ​​Xsys, Ysys, Wsys, Hsys of the second aperture position information.

[0095] After step SD5, the processing circuit 51 checks the aperture operation during sequence shooting (step SD6). In step SD6, if the current output value Xsys of the second aperture position information matches the previous output value Xsysl, the current output value Ysys matches the previous output value Ysysl, the current output value Wsys matches the previous output value Wsysl, and the current output value Hsys matches the previous output value Hsysl, the processing circuit 51 replaces the adjustment values ​​X1t,...,X4t, Y1t,...,Y4t with the previous output values ​​X1outl,...,X4outl, Y1outl,...,Y4outl of the final aperture position information, respectively.

[0096] After step SD6, the processing circuit 51 stores the previous values ​​(step SD7). In step SD7, the processing circuit 51 stores the adjustment values ​​X1t, . . ., X4t, Y1t, . . ., Y4t as the previous output values ​​X1outl, . . ., X4outl, Y1outl, . . ., Y4outl of the final aperture position information, respectively. In addition, the processing circuit 51 stores the current output values ​​Xsys, Ysys, Wsys, and Hsys of the second aperture position information as the previous output values ​​Xsysl, Ysysl, Wsysl, and Hsysl of the second aperture position information, respectively.

[0097] After step SD7, the processing circuit 51 outputs the final aperture position information (step SD8). In step SD8, the processing circuit 51 replaces the adjustment values ​​X1t, . . ., X4t, Y1t, . . ., Y4t with the current output values ​​X1out, . . ., X4out, Y1out, . . ., Y4out of the final aperture position information and outputs them.

[0098] This completes the second adjustment process.

[0099] When the above conditions for each step are met in the first and second adjustment processes and the adjustment value is adjusted, the step in which the adjustment was made and the amount of adjustment may be stored as a log in the storage device 52. In this case, the processing circuit 51 can display the step in which the adjustment was made and the amount of adjustment on the display device 55 in response to a request via the input device 53 or the like. This can be used for system testing and stability evaluation in clinical FT.

[0100] As described above, according to the first and second adjustment processes, the first aperture position information is adjusted based on the second aperture position information and the system control information. It is not necessary to carry out all the steps shown in FIG. 12 or FIG. 14. For example, only the comparison and adjustment of the first aperture position information and the second aperture position information in step SC3 or step SD4 may be carried out. That is, the first aperture position information may be adjusted based on the second aperture position information.

[0101] (Second X-ray) Fig. 16 is a diagram showing a processing example of the second X-ray examination by the X-ray diagnostic apparatus 1. As shown in Fig. 16, in the second X-ray examination, the processing circuitry 51 determines whether or not to use the first aperture position information after performing the image-based extraction process. The second X-ray examination will be described in detail below.

[0102] 16, the processing circuit 51 first sets parameters such as shooting conditions by implementing the parameter setting function 512 (step SE1). The process of step SE1 is similar to the process of step SA1.

[0103] When step SE1 is performed, the system control circuit 56 performs X-ray photography according to the photography conditions, and the processing circuitry 51 acquires an X-ray image by implementing the acquisition function 511 (step SE2). The process of step SE2 is similar to the process of step SA2.

[0104] After step SE2, the processing circuit 51 executes an image-based extraction process of an aperture region (image-based extraction process) (step SE3) by implementing the image-based extraction function 514. The process of step SE3 is similar to the process of step SA4.

[0105] After step SE3, the processing circuit 51 calculates position information of the aperture region (second aperture position information) based on the aperture control information by implementing the aperture region adjustment function 515 (step SE4). The process of step SE4 is similar to the process of step SA5.

[0106] After step SE4 is performed, the processing circuit 51 determines whether or not to use the first aperture position information obtained in step SE3 by implementing the determination function 513 (step SE5). The process of step SE5 is similar to the process of step SA3.

[0107] If it is determined in step SE5 that the first aperture position information is to be used (step SE: YES), the processing circuit 51 adjusts the first aperture position information based on the second aperture position information and the system control information (step SE6). The process of step SE6 is similar to the process of step SA6.

[0108] On the other hand, if it is determined in step SE5 that the image-based aperture area extraction process is not to be used (step SE5: NO), the processing circuit 51 sets the second aperture position information as the final aperture position information by implementing the aperture area adjustment function 515 (step SE7).

[0109] When step SE6 or step SE7 is performed, the processing circuit 51, by implementing the display control function 516, performs negative-positive inversion of the X-ray image (step SE8), applies a mask (electronic shutter) to the aperture region of the negative-positive image generated in step SE8 based on the final aperture position information obtained in step SE6 or step SE7 (step SE9), and displays the mask image generated in step SE9 (step SE10). The processing of steps SE8 to SE10 is similar to the processing of steps SA8 to SA10, respectively.

[0110] When step SE10 is performed, the second X-ray inspection ends.

[0111] (Variation 1) In step SA4, the processing circuit 51 according to the first modification determines whether or not to execute image-based extraction processing according to the aperture control method. There are symmetric control and asymmetric control as aperture control methods. Symmetric control is a method of controlling the upper and lower blades in conjunction with each other, and the left and right blades in conjunction with each other. A pair of upper and lower blades, and a pair of left and right blades, are arranged symmetrically with respect to the center of the image. The irradiation field area in the symmetric control is rectangular, and aperture position information is defined by X, Y, W, and H. Asymmetric control is a method of individually controlling the upper, lower, left, and right blades. The asymmetric control may be a method of moving a rectangular irradiation field area such as a spot view on an X-ray image, or may be a method of forming the irradiation field into an arbitrary shape. The irradiation field area in the asymmetric control is rectangular, and aperture position information is defined by X and Y.

[0112] When the aperture control method is symmetrical control, the processing circuit 51 evaluates the asymmetry of the pair of aperture blades with respect to the image center of the X-ray image. When the processing circuit 51 evaluates that there is asymmetry, it determines not to execute the image-based extraction process, and when it evaluates that there is no asymmetry, it determines to execute the image-based extraction process. For example, for a pair of upper and lower blades, the distance from the image center to the upper side of the irradiation field area and the distance from the image center to the lower side of the irradiation field area are calculated, and when the difference between the two distances is equal to or greater than a threshold, it is evaluated that the upper and lower blades are asymmetrical. In this case, the aperture position information of the upper and lower blades may be obtained by executing step SA7. The left and right blades are also evaluated for asymmetry in the same manner. When it is evaluated that the left and right blades are not asymmetrical, it is preferable to obtain the aperture position information of the left and right blades by executing steps SA4 to SA6.

[0113] The above-mentioned first modification can also be applied to the determination in step SE5 as to whether or not to use the first aperture position information.

[0114] As described above, according to the first modification, the geometric characteristics of the aperture region according to the aperture control method can be utilized to improve the accuracy of the final aperture position information.

[0115] (Variation 2) In the case of not performing spot view and oblique incidence, the processing circuit 51 may reject the first aperture position information if the following conditions regarding the irradiation field shape are not satisfied. Incidentally, oblique incidence is a method in which X-rays are incident obliquely on the X-ray detector 14. The first condition regarding the irradiation field shape is when the upper and lower sides are horizontal, and the left and right sides are oblique lines that are symmetrical with respect to the center of the image in terms of both position and angle. The second condition is a value calculated based on SID / oblique incidence angle, where the ratio of the upper side length to the lower side length is the angle between the imaging axis and the X-ray detection surface of the X-ray detector 14. In the case of oblique incidence, the irradiation field area in the X-ray image has a trapezoidal shape, so the first and second conditions are set as conditions for determining that the irradiation field area is trapezoidal.

[0116] Based on the aperture area recognized by the image-based extraction process, the processing circuit 51 determines whether the upper and lower sides of the irradiation field shape are horizontal and whether the left and right sides are symmetrical with respect to the image center in terms of both position and angle as a first condition. If the first condition is satisfied, the processing circuit 51 calculates the ratio of the upper and lower side lengths of the irradiation field area and the SID / oblique angle of the current examination as a second condition, and determines whether the ratio of the upper and lower side lengths is a value calculated based on the SID / oblique angle. If the second condition is satisfied, the processing circuit 51 executes the adjustment process shown in FIG. 12 or FIG. 14 in step SA6. If the first condition or the second condition is not satisfied, the processing circuit 51 executes step SA7 instead of step SA6.

[0117] In addition, in the case of performing spot view and oblique entry, conditions different from the above first and second conditions are imposed. When spot view is performed, the position of the irradiation field area differs depending on the position of the irradiation field area in the X-ray image, so conditions more complicated than the above first and second conditions are imposed. For example, when the irradiation field area is shifted to the right side of the X-ray image, the upper and lower sides are horizontal, the left side is vertical, and the right side is oblique, but the angle of the oblique line on the right side differs depending on the position of the irradiation field area.

[0118] As described above, according to the second modification, the geometric characteristics of the aperture area in oblique shooting can be utilized to improve the accuracy of the final aperture position information.

[0119] (Variation 3) In the above embodiment, even in the case of sequential imaging, steps SA3 to SA10 are performed for each of the time-series X-ray images. However, this embodiment is not limited to this. Steps SA3 to SA10 may be performed only for a specified X-ray image, such as the first X-ray image, among the time-series X-ray images. Steps SA3 to SA10 may be performed at predetermined time intervals, or steps SA3 to SA10 may be performed each time the aperture device 13 is operated. For X-ray images for which steps SA3 to SA10 are not performed, the process can be omitted by using the previous value of the final aperture position information (final aperture position information of the previous image). In image recognition by AI, the accuracy of the first aperture position information may be unstable due to temporal and spatial variations in the X-ray image brightness value caused by quantum noise. By using the previous value of the final aperture position information (final aperture position information of the previous image), it is possible to reduce the instability of the accuracy of such first aperture position information.

[0120] There are cases where multiple sequence photographs are taken in a single X-ray examination. In this case, if the current image vertical width and image horizontal width match the previous image vertical width and image horizontal width, the processing circuit 51 may use the previous output values ​​Xsys, Ysys, Wsys, and Hsys as the previous output values ​​Xsysl, Ysysl, Wsysl, and Hsysl, and the previous output values ​​Xout, Yout, Wout, and Hout as the previous output values ​​Xoutl, Youtl, Woutl, and Houtl. By using the aperture position information of the previous series in this way, it is possible to reduce the processing load.

[0121] (Variation 4) In the above embodiment, the X-ray image processing device 5 is mounted on the X-ray diagnostic device 1. However, this embodiment is not limited to this. The X-ray image processing device 5 may be a computer separate from the X-ray diagnostic device, for example, a computer dedicated to image interpretation. In this case, the X-ray image processing device 5 acquires X-ray images from an image storage device such as the X-ray diagnostic device or PACS, and executes steps SA3 to SA10 or steps SE3 to SE10 for the acquired X-ray images. When acquiring time-series X-ray images generated by sequential imaging, the X-ray image processing device 5 executes steps SA3 to SA10 or steps SE3 to SE10 for each X-ray image.

[0122] (Summary) The X-ray image processing apparatus according to the embodiment includes a processing circuit 51. The processing circuit 51 determines whether or not to use the extraction result (first aperture position information) of the image-based aperture area extraction process for the X-ray image based on the imaging conditions corresponding to the X-ray image. When it is determined that the first aperture position information is to be used, the processing circuit 51 adjusts the first aperture position information based on the system control information related to the X-ray aperture, and calculates the position information of the final aperture area included in the X-ray image.

[0123] According to the above configuration, it is determined whether or not to use the first aperture position information based on the imaging conditions, and only when it is determined to use the first aperture position information, the position information of the final aperture area to be used for the electronic shutter can be obtained by adjusting the first aperture position information based on the system control information. In this way, the first aperture position information can be used only in a situation suitable for using the first aperture position information, and even when the first aperture position information is used, the first aperture position information is adjusted based on the system control information, so that it is possible to improve the accuracy of the final aperture position information regardless of the shape of the aperture area depicted in the X-ray image, mechanical factors, installation factors, etc.

[0124] According to at least one of the embodiments described above, position information of the aperture area of ​​an X-ray image can be obtained with high accuracy and stability.

[0125] The term "processor" used in the above description means a circuit such as a CPU, a GPU, or an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). The processor realizes its function by reading and executing a program stored in a memory circuit. Instead of storing a program in a memory circuit, the processor may be configured to directly incorporate the program in its circuit. In this case, the processor realizes its function by reading and executing a program incorporated in its circuit. Instead of executing a program, a function corresponding to the program may be realized by a combination of logic circuits. Each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize its function. Furthermore, the multiple components in FIG. 1 may be integrated into a single processor to realize its function.

[0126] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0127] 1 X-ray diagnostic equipment 3. X-ray Department 5. X-ray image processing device 11 X-ray tube 12 High voltage generator 13 X-ray detector 13 Squeezing device 14 X-ray detector 15 Holding device 17 Drive unit 31 Tabletop 33 Holding device 35 Drive unit 51 Processing circuit 52 Storage device 53 Input Devices 54 Communication Equipment 55 Display equipment 56 System Control Circuit 511 Acquisition Function 512 Parameter setting function 513 Judgment function 514 Image-based extraction function 515 Aperture area adjustment function 516 Display control function

Claims

1. a determination unit that determines whether or not to use an extraction result of an image-based aperture region extraction process for the X-ray image based on an imaging condition corresponding to the X-ray image; an adjustment unit that adjusts the extraction result based on system control information related to a position of the X-ray aperture when it is determined that the extraction result is to be used, and calculates position information of an aperture region included in the X-ray image; An X-ray image processing apparatus comprising:

2. an extraction unit that performs the extraction process on the X-ray image, the determination unit determines whether or not to perform the extraction process based on the photographing conditions; When it is determined that the extraction process is to be performed, the extraction unit performs the extraction process on the X-ray image to obtain the extraction result of the narrowed area included in the X-ray image.

2. The X-ray image processing apparatus according to claim 1.

3. When it is determined that the extraction process is not to be performed, the extraction unit does not perform the extraction process on the X-ray image, The adjustment unit calculates the position information of the aperture region included in the X-ray image based on the system control information.

3. The X-ray image processing apparatus according to claim 2.

4. The X-ray image processing apparatus according to claim 2 , wherein the extraction unit performs image recognition of the aperture region included in the X-ray image by utilizing a machine learning model as the extraction process.

5. The X-ray image processing apparatus according to claim 1 , wherein the adjustment unit calculates the position information of the aperture region included in the X-ray image based on the system control information, and adjusts the extraction result based on the position information.

6. The X-ray image processing apparatus according to claim 1 , further comprising a display control unit that displays the X-ray image by applying a mask to the narrowed area included in the X-ray image based on the position information.

7. The X-ray image processing apparatus according to claim 6 , wherein the display control unit performs negative-positive inversion on the X-ray image to generate a negative-positive inversion image, and applies a mask to the aperture region included in the negative-positive inversion image based on the position information.

8. The X-ray image processing apparatus according to claim 1 , wherein the system control information includes aperture control information which is control information for a mechanical device of an X-ray diagnostic apparatus that affects a position of the aperture region drawn on the X-ray image.

9. 9. The X-ray image processing apparatus according to claim 8, wherein said system control information further includes control information relating to a position of a mask applied to said aperture region included in said X-ray image.

10. The X-ray image processing apparatus according to claim 1 , wherein the determination unit determines whether or not to use the extraction result based on an examination protocol, a procedure, an X-ray condition, and a division setting included in the imaging conditions.

11. The X-ray image processing apparatus according to claim 1 , wherein the adjustment unit selects an adjustment algorithm depending on how the position information of the aperture region is defined.

12. 12. The X-ray image processing apparatus according to claim 11, wherein when the position information is defined by an X coordinate of a reference point, a Y coordinate of the reference point, a horizontal width of an exposure field area, and a vertical width of the exposure field area, the adjustment unit sequentially performs fine adjustment on the extraction result, adjustment using a maximum FOV, comparison adjustment with position information of the aperture area based on aperture control information, rejection using a minimum FOV and / or a confidence flag, and confirmation of aperture operation during sequential shooting.

13. 12. The X-ray image processing apparatus according to claim 11, wherein when the position information is defined by the X coordinate and the Y coordinate of each point at the four corners, the adjustment unit sequentially performs the following on the extraction result: adjustment using a maximum FOV; comparison adjustment with position information of an aperture region based on aperture control information; rejection using a minimum FOV and / or a confidence flag; and confirmation of aperture operation during sequential shooting.

14. An X-ray tube that generates X-rays; a diaphragm device for adjusting an irradiation field of X-rays generated from the X-ray tube; an acquisition unit that acquires an X-ray image from an X-ray detector that detects X-rays that have passed through the aperture device and transmitted through a subject; a determination unit that determines whether or not to use an extraction result of an image-based aperture region extraction process for the X-ray image based on an imaging condition corresponding to the X-ray image; an adjustment unit that adjusts the extraction result based on system control information related to the X-ray aperture when it is determined that the extraction result is to be used, and calculates position information of the aperture area included in the X-ray image; An X-ray image processing apparatus comprising:

15. determining whether or not to use an extraction result of an image-based aperture region extraction process for the X-ray image based on an imaging condition corresponding to the X-ray image; When it is determined that the extraction result is to be used, the extraction result is adjusted based on system control information related to the X-ray aperture, and position information of the aperture region included in the X-ray image is calculated. An X-ray image processing method comprising:

Images