X-ray diagnostic apparatus and method for setting X-ray conditions

Abstract

To set an X-ray condition for reducing an exposure dose and improving image quality.SOLUTION: An X-ray diagnostic device includes a determination part, a calculation part, and a setting part. The determination part determines a region of an object in an X-ray image on the basis of the X-ray image. The calculation part calculates a statistical value on the region on the basis of a plurality of pixel values included in the region. The setting part sets an X-ray condition on the generation of an X-ray on the basis of the statistical value.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to an X-ray diagnostic apparatus and an X-ray condition setting method.

Background Art

[0002] Conventionally, in controlling the luminance in an X-ray diagnostic apparatus, there is ABC (auto brightness control) control. The ABC control is a control of X-ray conditions that uniformly sets a region of interest (hereinafter referred to as ROI) over the entire area of an X-ray image and maintains the balance between an optimal image quality according to the thickness of a subject and the exposure. Thereby, it is possible to realize X-ray control that achieves both the exposure dose and the image quality and sets optimal X-ray conditions.

[0003] However, in the conventional ABC control, there are cases where the optimal X-ray conditions cannot be set, and it may not be possible to achieve both the optimal exposure dose and the image quality, such as when a procedure for a subject or an object having a high X-ray absorption rate is included in the X-ray image. As a result, the patient may be irradiated with an excessive dose of X-rays, and sufficient image quality may not be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems 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 set X-ray conditions capable of reducing the exposure dose and improving the image quality. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. It is also possible to position the problems corresponding to the respective effects of each configuration shown in the embodiments described later as other problems. [Means for solving the problem]

[0006] The X-ray diagnostic apparatus according to this embodiment comprises a determination unit, a calculation unit, and a setting unit. The determination unit determines the region of the object in the X-ray image based on the X-ray image. The calculation unit calculates statistical values ​​related to the region based on a plurality of pixel values ​​included in the region. The setting unit sets the X-ray conditions related to X-ray generation based on the statistical values. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows an example of the configuration of an X-ray diagnostic apparatus according to an embodiment. [Figure 2] Figure 2 is a flowchart showing an example of the procedure for setting X-ray conditions according to the embodiment. [Figure 3] Figure 3 is a diagram illustrating an embodiment, showing an example of the target area and catheter in an X-ray image. [Figure 4] Figure 4 is a diagram illustrating an example of the weights in the target region excluding the high absorption region, relating to an embodiment. [Figure 5] Figure 5 illustrates an example of an application of the embodiment, showing an example of the target region, catheter, and stent in an X-ray image. [Figure 6] Figure 6 illustrates an example of the weights in the target region excluding the high absorption region, relating to an application example of the embodiment. [Modes for carrying out the invention]

[0008] The following describes embodiments of the X-ray diagnostic apparatus and the X-ray condition setting method with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0009] (Embodiment) Figure 1 shows an example of the configuration of the X-ray diagnostic apparatus 100 according to this embodiment. The X-ray diagnostic apparatus 100 comprises an X-ray generating unit 1, a high-voltage generating unit 2, an X-ray detection unit 3, a holding arm 4, a patient table 5, a mechanism unit 6, a mechanism control unit 7, an electrocardiograph 8, an image calculation and storage unit 9, a display unit 10, a system control unit 11, and an operation unit 12.

[0010] The X-ray generating unit 1 generates X-rays. The X-ray generating unit 1 includes, for example, an X-ray tube 1a and an X-ray diaphragm 1b. The X-ray tube 1a is a vacuum tube that generates X-rays by irradiating thermionic electrons from the cathode (filament) to the anode (target) by applying a high voltage from the high voltage generating unit 2 and supplying filament current. X-rays are generated when thermionic electrons collide with the target. The X-ray tube 1a includes, for example, a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermionic electrons. Note that the type of X-ray tube 1a is not limited to the rotating anode type, and any type of X-ray tube can be applied.

[0011] The X-ray diaphragm 1b shapes the X-ray irradiation field of the X-ray tube 1a. The X-ray diaphragm 1b is located in front of the X-ray emission window of the X-ray tube 1a. The X-ray diaphragm 1b has four aperture blades made of metal plates, such as lead. The aperture blades are driven by a drive device (not shown) according to the region of interest input by the operator via the control unit 12 or input interface. The X-ray diaphragm 1b adjusts the area where X-rays are shielded to any size by sliding these aperture blades with the drive device. With the adjusted aperture blades, the X-ray diaphragm 1b shields X-rays outside the aperture area. In this way, the X-ray diaphragm 1b focuses the X-rays generated by the X-ray tube 1a so that they are irradiated onto the region of interest of the subject P.

[0012] The high-voltage generation unit 2 comprises an electrical circuit including a transformer and a rectifier, a high-voltage generator, and an X-ray control device. The high-voltage generation unit 2 has the function of generating the high voltage applied to the X-ray tube 1a and the filament current supplied to the X-ray tube 1a. The X-ray control device controls the output voltage according to the X-rays irradiated by the X-ray tube 1a. The high-voltage generation unit 2 may be a transformer type or an inverter type. The high-voltage generation unit 2 may also be provided on the holding arm 4.

[0013] The X-ray detection unit 3 detects X-rays generated by the X-ray tube 1a. The X-ray detection unit 3 includes, for example, a flat panel detector 3a, an image data generation unit 3b, and a gate driver 3c, which correspond to an X-ray detector. The flat panel detector 3a is implemented, for example, by a flat panel detector (FPD). The FPD has multiple semiconductor detection elements. Semiconductor detection elements include direct conversion types that directly convert X-rays into electrical signals, and indirect conversion types that convert X-rays into light using a phosphor and then convert that light into an electrical signal. Either type may be used for the FPD. The electrical signal generated by the FPD is output to the image data generation unit 3b.

[0014] The image data generation unit 3b consists of a charge-voltage converter 3b-1, an A / D (Analog to Digital) converter 3b-2, and a parallel-serial converter 3b-3. The charge-voltage converter 3b-1 converts the electrical signal output from the flat panel detector 3a into a voltage signal and outputs it to the A / D converter 3b-2. Under the control of the system control unit 11, the A / D converter 3b-2 converts the electrical signal converted into a voltage signal into X-ray image data as digital data and outputs it to the parallel-serial converter 3b-3. Under the control of the system control unit 11, the parallel-serial converter 3b-3 converts the A / D-converted X-ray image data from parallel data to serial data and outputs it to the image processing and storage unit 9.

[0015] The gate driver 3c drives the detection element of the planar detector 3a under the control of the system control unit 11.

[0016] The holding arm 4 movably holds an X-ray tube 1a that generates X-rays and a flat detector 3a that faces the X-ray tube 1a and detects X-rays. In other words, the X-ray tube 1a and the flat detector 3a are attached to the ends of the holding arm 4 so as to face each other. The holding arm 4 rotatably supports the X-ray collimator 1b and the flat detector 3a with the straight line connecting the focal point where X-rays are generated in the X-ray tube 1a and the central part in the flat detector 3a as the rotation axis. The holding arm 4 rotates the X-ray collimator 1b and the flat detector 3a around the rotation axis by the operation of the holding arm moving mechanism 6a. Note that the holding arm 4 may hold the X-ray generation unit 1 and the X-ray detection unit 3 such that, for example, the source image distance (hereinafter referred to as SID) can be changed.

[0017] The hospital bed 5 has a top plate and a base. The subject P is placed on the top plate. The base supports the top plate so as to be movable in parallel, for example, along the long axis direction of the top plate, the short axis direction of the top plate, and the vertical direction. Further, the base supports the top plate so as to be rotatable with the short axis direction of the top plate, the long axis direction of the top plate, and the vertical direction, etc. as the rotation axes.

[0018] The mechanism unit 6 has a holding arm moving mechanism 6a and a hospital bed moving mechanism 6b. The holding arm moving mechanism 6a and the hospital bed moving mechanism 6b are realized by, for example, a motor or an actuator. The holding arm moving mechanism 6a moves the holding arm 4 to a position indicated by the user or a preset position under the control of the mechanism control unit 7. The hospital bed moving mechanism 6b moves the top plate of the hospital bed 5 to a position indicated by the user or a preset position under the control of the mechanism control unit 7.

[0019] The mechanism control unit 7 controls the mechanism unit 6 under the control of the system control unit 11. For example, based on an input operation received from the operator via the operation unit 12, the mechanism control unit 7 controls the moving operation of the holding arm moving mechanism 6a and the moving operation of the bed moving mechanism 6b. Specifically, the mechanism control unit 7 reads out the mechanism control program stored in the storage and expands it onto the memory in the processor in the mechanism control unit 7, and controls the moving operation of the holding arm moving mechanism 6a and the moving operation of the bed moving mechanism 6b according to the expanded mechanism control program.

[0020] The electrocardiograph 8 measures the temporal change in the action potential of the heart of the subject P and outputs the electrocardiogram phase, which is the measurement result, to the image calculation and storage unit 9. Although the electrocardiograph 8 is provided outside the X-ray diagnostic apparatus 100, it may be provided in the X-ray diagnostic apparatus 100. Also, when it is not necessary to acquire the electrocardiogram phase of the subject P, the electrocardiograph 8 can be appropriately omitted. Further, instead of the electrocardiograph 8, a pulse wave meter or the like may be used.

[0021] The image calculation and storage unit 9 includes an image data storage unit 9a and an image calculation unit 9b. The image data storage unit 9a is composed of a hard disk drive (HDD), a semiconductor memory, and the like. The image data storage unit 9a stores the X-ray image data output from the image data generation unit 3b. At this time, the image data storage unit 9a may store the X-ray image data in association with the electrocardiogram phase output from the electrocardiograph 8.

[0022] The image calculation unit 9b performs amplification processing, image calculation processing, etc. on the X-ray image data stored in the image data storage unit 9a to generate an X-ray image as the display target. At this time, the image calculation unit 9b may associate the generated X-ray image with the electrocardiogram phase output from the electrocardiograph 8. Also, according to an instruction such as an image display by the operator, the image calculation unit 9b causes the X-ray image stored in the image data storage unit 9a to be output to the display image memory 10a of the display unit 10 under the control of the system control unit 11.

[0023] The image processing unit 9b has a determination function 91, a calculation function 93, and a setting function 95. The image processing unit 9b that implements the determination function 91, the calculation function 93, and the setting function 95 corresponds to the determination unit, the calculation unit, and the setting unit. The determination function 91 determines the region of an object in an X-ray image (hereinafter referred to as the target region) based on the X-ray image. For example, the determination function 91 determines the target region in an X-ray image by various image processing methods such as various segmentation processes, image recognition processes, or trained models that have been trained to implement image recognition and segmentation processes (for example, a trained neural network that implements semantic segmentation).

[0024] Specifically, the determination function 91 determines the target area from among several pre-divided sections in the X-ray image. These sections correspond to, for example, multiple divided regions obtained by dividing the X-ray image into an n × m grid (where n and m are natural numbers greater than or equal to 2). Since these sections divide the X-ray image, they each contain multiple pixels. Each of these sections corresponds to a unit that uniformly applies the weights described later to the multiple pixels contained within that section. To make the explanation more concrete, the sections will be described below as multiple divided regions obtained by dividing the X-ray image into a 5 × 5 grid.

[0025] The object is, for example, a catheter. In this case, the determination function 91 determines the region where the catheter is located (the target region) among multiple compartments by image processing of the X-ray image. In addition, the determination function 91 further determines the region within the target region that includes the tip of the catheter by image processing of the X-ray image or the target region. The determination function 91 determines in the X-ray image a region of high-absorption material (hereinafter referred to as the high-absorption region) that is superimposed on the object and has an X-ray absorption rate higher than a predetermined X-ray absorption rate. The predetermined X-ray absorption rate is, for example, the X-ray absorption rate of teeth, bones, and various devices placed inside the subject (for example, pacemakers, transesophageal echocardiography (TEE) probes, artificial joints, etc.).

[0026] If the high-attenuation material is bone and teeth, the determination function 91 determines the high-attenuation region by performing a detection process based on anatomical findings on the X-ray image. If the high-attenuation material is various devices, the determination function 91 determines the high-attenuation region by recognizing the device on the X-ray image. For example, if the high-attenuation material is a TEE probe, the high-attenuation region is determined based on a fusion image of the X-ray image and the echo (ultrasound) image. Since existing methods can be appropriately used for recognition and detection processes related to high-attenuation materials, a detailed explanation is omitted.

[0027] Furthermore, the determination function 91 may re-determine the area of ​​the object in response to the movement of at least one of the holding arm 4 and the top plate. Specifically, the determination function 91 responds to the receipt of a movement instruction to the mechanism 6 output from the mechanism control unit 7 or the system control unit 11 by performing image processing on the X-ray image and re-determining the area of ​​the object.

[0028] The calculation function 93 calculates statistical values ​​for the region of the determined object based on multiple pixel values ​​contained within that region. For example, the calculation function 93 calculates these statistical values ​​using weights that gradually decrease from the tip of the determined catheter towards the end of the catheter. Specifically, the calculation function 93 sets the maximum weight (e.g., weight 1) for the region where the tip of the catheter is located (hereinafter referred to as the tip region) and the minimum weight (e.g., weight 0) for the region where the end of the catheter is located (hereinafter referred to as the end region). In other words, the calculation function 93 assigns the maximum weight to multiple pixels contained in the tip region and the minimum weight to multiple pixels contained in the end region. Furthermore, the calculation function 93 sets weights from the region adjacent to the tip region to the region adjacent to the end region so that the weight in each region gradually decreases from the tip region towards the end region.

[0029] To make the explanation more concrete, the weights will be represented as ratios between 0 and 1. However, the weights are not limited to ratios between 0 and 1 and can be set as appropriate. Furthermore, the setting of weights may be implemented using a function other than the calculation function 93 (for example, a weight setting function).

[0030] The calculation function 93 calculates statistical values ​​using, for example, the following equation (1). As shown in equation (1), the statistical values ​​correspond to the weighted mean. Note that in equation (1), multiple pixel values ​​belonging to a section with a weight of 0 are excluded from the calculation of equation (1).

[0031]

number

[0032] In equation (1), the subscript i is an argument that indicates a pixel. Also, in equation (1), ROI is the region in the X-ray image that excludes the region with zero weight and the high-absorption region from the target region (hereinafter referred to as the calculated region). That is, the ROI is the region among multiple sections that includes the object and does not include the region with zero weight and the high-absorption region, and is the region determined to be the periphery of the object. w in equation (1) i This is the weighting coefficient for the i-th pixel, i.e., the weighting coefficient assigned to the section to which the i-th pixel belongs. Also, in equation (1), p i This is the pixel value of the i-th pixel. The calculation function 93 calculates statistical values ​​using equation (1) by excluding the region related to the highly absorbent material from the region related to the object.

[0033] Furthermore, if at least one of the holding arm 4 and the top plate moves, the calculation function 93 may recalculate the statistical value based on the multiple pixel values ​​included in the newly determined region in response to the movement of at least one of the holding arm 4 and the top plate.

[0034] The setting function 95 sets the X-ray conditions related to X-ray generation based on the calculated statistical values. These X-ray conditions include the tube voltage kV applied to the X-ray tube 1a, and the product of the tube current supplied to the X-ray tube 1a and the X-ray irradiation time (tube current-time product mAs). The setting function 95 compares the statistical values ​​with a threshold value, for example. The threshold value is pre-stored in the memory of the image processing unit 9b. The threshold value can be set, changed, and adjusted as appropriate by user instructions via the operation unit 12. The setting function 95 compares the statistical values ​​with the threshold value. Based on the comparison result between the statistical values ​​and the threshold value, the setting function 95 sets the X-ray conditions. The setting function 95 outputs the set X-ray conditions to the system control unit 11. Setting the X-ray conditions corresponds to, for example, adjusting at least one of the tube voltage kV and the tube current-time product mAs in the X-ray conditions related to the X-ray image (hereinafter referred to as ABC control). Since various known methods can be used for adjusting the X-ray conditions in ABC control, a detailed explanation is omitted.

[0035] The display unit 10 includes a display image memory 10a, a D / A (Digital to Analog) converter 10b, a display control unit 10c, and a monitor 10d. The display image memory 10a stores image data output from the image data storage unit 9a and outputs it to the D / A converter 10b. The D / A converter 10b converts the image data output from the display image memory 10a into an analog signal and outputs it to the display control unit 10c. The display control unit 10c displays an X-ray image based on the image data output from the D / A converter 10b on the monitor 10d.

[0036] The display unit 10 can be implemented as a display. In this case, the display can be, for example, a liquid crystal display (LCD), a cathode ray tube (CRT) display, an organic electroluminescent display (OELD), a plasma display, or any other display as appropriate. The display may be a desktop type, or it may consist of a tablet terminal that can communicate wirelessly with the system control unit 11 and the image processing / storage unit 9. Furthermore, if the monitor 10d displays the X-ray image as digital data, the D / A converter 10b is not required.

[0037] The system control unit 11 controls the X-ray generator 1, high-voltage generator 2, gate driver 3c, A / D converter 3b-2, parallel-to-serial converter 3b-3, mechanism control unit 7, image processing and storage unit 9, display unit 10, etc., based on input operations received from the operator via the operation unit 12. Specifically, the system control unit 11 reads the system control program, loads it into its memory, and controls each part of the X-ray diagnostic apparatus 100 according to the loaded control program.

[0038] The control unit 12 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs them to the system control unit 11. The control unit 12 is implemented, for example, by an input interface. The control unit 12 receives from the operator operations for operating at least one of the holding arm 4 and the patient bed 5, X-ray conditions related to X-ray generation, conditions related to image processing performed by the image processing unit 9b, etc. As the control unit 12, for example, a mouse, keyboard, trackball, switch, button, joystick, foot switch, touchpad, and touch panel display can be used as appropriate. The control unit 12 is mounted on a console device installed in a control room separate from the examination room, for example. The control unit 12 may also be provided on the holding arm 4, etc.

[0039] In this embodiment, the operation unit 12 is not limited to being equipped with physical operating components such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to the system control unit 11 is also included as an example of the operation unit 12. The operation unit 12 may also be composed of a tablet terminal or the like that can communicate wirelessly with the system control unit 11.

[0040] The processing circuits that implement the above-mentioned mechanism control unit 7, image processing unit 9b, system control unit 11, etc., have as hardware resources a processor such as a CPU (Central Processing Unit), MPU (Micro Processing Unit), GPU (Graphics Processing Unit), and memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0041] The various functions performed by the processor are stored in memory (not shown) in the form of programs that can be executed by the computer. The processor is a processor that realizes the functions corresponding to each program by reading and executing programs from memory. In other words, each circuit, when a program is read, possesses the function corresponding to the read program.

[0042] For example, the processing circuit that implements the image processing unit 9b executes the decision function 91, the calculation function 93, and the setting function 95 using a processor that runs a program loaded into memory. The processing circuits 21 that execute the decision function 91, the calculation function 93, and the setting function 95 correspond to the decision unit, the calculation unit, and the setting unit, respectively. Note that the decision function 91, the calculation function 93, and the setting function 95 are not limited to being implemented by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and the decision function 91, the calculation function 93, and the setting function 95 may be implemented by each processor executing a program.

[0043] Furthermore, the processing circuit that realizes the image processing unit 9b may be implemented by a processor such as an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), another Complex Programmable Logic Device (CPLD), or a Simple Programmable Logic Device (SPLD).

[0044] The overall configuration of the X-ray diagnostic apparatus 100 according to this embodiment has been described above. Under this configuration, the X-ray diagnostic apparatus 100 according to this embodiment performs a process of setting X-ray conditions based on an X-ray image (hereinafter referred to as the X-ray condition setting process). The X-ray condition setting process determines a target area in an X-ray image based on the X-ray image using a determination function 91, a calculation function 93, and a setting function 95, calculates statistical values ​​related to the determined target area based on a plurality of pixel values ​​included in the said area, and sets X-ray conditions related to X-ray generation based on the calculated statistical values. The X-ray condition setting process corresponds to ABC control having the technical features of this embodiment.

[0045] The procedure for setting X-ray conditions will be explained below with reference to Figure 2. Figure 2 is a flowchart showing an example of the procedure for setting X-ray conditions. To make the explanation more concrete, the object will be assumed to be a catheter.

[0046] (X-ray condition setting process) (Step S201) The system control unit 11 controls each unit in the X-ray diagnostic device 100 to perform X-ray imaging on the subject P. The imaging in this embodiment can be applied to either a single-shot X-ray (roentgen) in which a high dose of X-rays is irradiated onto the subject P, or fluoroscopic imaging in which a low dose of X-rays is irradiated onto the subject P continuously or intermittently.

[0047] The high-voltage generation unit 2 generates a high voltage according to the set X-ray conditions and applies the generated high voltage to the X-ray tube 1a. In addition, the high-voltage generation unit 2 supplies tube current to the X-ray tube 1a for the duration of irradiation according to the set X-ray conditions. The X-ray detection unit 3 generates an X-ray image based on the detected X-rays. The X-ray detection unit 3 outputs the generated X-ray image to the image data storage unit 9a. The image data storage unit 9a outputs the X-ray image to the image processing unit 9b and the display unit 10. The display unit 10 displays the X-ray image on the monitor 10d.

[0048] (Step S202) The processing circuit in the image processing unit 9b performs image processing such as segmentation on the X-ray image using the determination function 91. The determination function 91 determines the target region in the X-ray image through image processing. Furthermore, the determination function 91 further determines the region containing the catheter tip (tip compartment) and the high-attenuation region within the target region through image processing of the X-ray image or the target region.

[0049] (Step S203) The image processing unit 9b uses the calculation function 93 to set weights in the region excluding the high-absorption region from the target region. At this time, the determination function 91 determines the region used for calculating statistical values ​​by excluding the region with zero weight and the high-absorption region from the target region.

[0050] Figure 3 shows an example of the target region 33 and catheter 35 in the X-ray image 31. In Figure 3, the dashed grid lines indicate multiple compartments. As shown in Figure 3, the catheter 35 is detected across six compartments. The thick lines indicating these six compartments, including the catheter 35, correspond to the target region 33. Also, as shown in Figure 3, the region of vertebral body Vb is determined across five compartments. The five compartments including vertebral body Vb correspond to the high-attenuation region. The region of the L-shaped target region 33 excluding the high-attenuation region is shown by diagonal lines in Figure 3. The region 39 shown in Figure 3 corresponds to the tip compartment, including the tip 37 of the catheter.

[0051] Figure 4 shows an example of weights in the target region 33 excluding the high-absorption region. As shown in Figure 4, for example, the calculation function 93 sets the weight of the tip compartment 39, which includes the tip 37 of the catheter, to 100%, and the weights of the two terminal compartments, which include the end 41 of the catheter, to 0%. The calculation function 93 also sets the weights from the compartment adjacent to the tip compartment 39 to the compartment adjacent to the terminal compartment, so that the weight gradually decreases from the tip compartment 39 towards the terminal compartment. At this time, the determination function 91 determines the calculation region by excluding the region with zero weight and the high-absorption region from the target region 33. The calculation region in Figure 4 has a region corresponding to a weight of 100%, a region corresponding to a weight of 70%, and a region corresponding to a weight of 30%.

[0052] (Step S204) The image processing unit 9b calculates statistical values ​​for the target region 33 using the calculation function 93, which uses multiple pixel values ​​and weights included in the target region 33. Specifically, the calculation function 93 calculates statistical values ​​for the target region 33 by applying the weights and pixel values ​​in the target region (calculation region), excluding the areas with a weight of 0% and the high-absorption region, to equation (1).

[0053] (Step S205) The image processing unit 9b compares the statistical value calculated by the setting function 95 with the threshold. Next, the setting function 95 determines whether or not to change the X-ray conditions based on the comparison result between the statistical value and the threshold. If the setting function 95 determines to change the X-ray conditions based on the comparison result between the statistical value and the threshold (Yes in step S205), the process in step S206 is executed. If the setting function 95 does not determine to change the X-ray conditions based on the comparison result between the statistical value and the threshold (No in step S205), the X-ray conditions are maintained and the process in step S207 is executed.

[0054] (Step S206) The image processing unit 9b modifies the X-ray conditions based on the comparison result between statistical values ​​and thresholds using the setting function 95. In other words, the setting function 95 sets the X-ray conditions related to X-ray generation based on statistical values. Subsequent X-ray exposure is performed according to the modified X-ray conditions.

[0055] (Step S207) If X-ray imaging of subject P is not completed (No in step S207), the process from step S201 onwards is repeated. Also, if X-ray imaging of subject P is completed (Yes / No in step S207), the X-ray condition setting process is completed.

[0056] As a modification of this embodiment, the X-ray condition setting process may be performed at a predetermined frame rate for generating the X-ray image. In this case, the determination function 91 may re-determine the area of ​​the object in response to the movement of at least one of the holding arm 4 and the top plate. Specifically, the determination function 91 responds to the receipt of a movement instruction output from the system control unit 11 to the mechanism control unit 71 by performing image processing on the X-ray image and re-determining the area of ​​the object.

[0057] Furthermore, as a modification of this embodiment, if the object moves in multiple X-ray images in a time series due to the beating of the subject P's heart, the target region 33 may be determined by the following procedure. For example, the determination function 91 determines the region of the object by performing various image processing on the X-ray image corresponding to the end-systolic or end-diastolic phase of the electrocardiogram output from the electrocardiograph 8. Alternatively, the determination function 91 may determine the region of the object in each of the multiple X-ray images by performing various image processing on the multiple X-ray images in a time series. In this case, the determination function 91 determines the region of the object by superimposing the regions determined across the multiple X-ray images. At this time, high-absorption regions are excluded from the target region 33. In this way, the determination function 91 determines the region of the object so as to encompass the range of movement of the object in the multiple X-ray images. That is, when the position of the object moves in multiple X-ray images acquired in a time series, the determination function 91 determines the range of movement of the object as the region of the object.

[0058] According to the X-ray diagnostic apparatus 100 of the embodiment described above, the region of the object in the X-ray image (target region 33) is determined based on the X-ray image, statistical values ​​related to the target region 33 are calculated based on a plurality of pixel values ​​included in the target region 33, and X-ray conditions related to X-ray generation are set based on the calculated statistical values. For example, according to this X-ray diagnostic apparatus 100, if the object is a catheter, the region including the tip of the catheter (tip section) 39 is further determined based on the X-ray image, and the statistical values ​​are calculated using a weight that gradually decreases from the tip 37 of the catheter 35 toward the end of the catheter. In addition, according to this X-ray diagnostic apparatus 100, the region of a high-absorbent material superimposed on the object in the X-ray image and having a higher X-ray absorption rate than a predetermined X-ray absorption rate is determined in the X-ray image, and statistical values ​​are calculated by excluding the region related to the high-absorbent material from the region related to the object.

[0059] Based on these considerations, the X-ray diagnostic apparatus 100 according to this embodiment allows the calculation region, which includes the area of ​​interest of the object but excludes high-absorption regions, to be set as the region of interest for ABC control. In other words, the X-ray diagnostic apparatus 100 allows the calculation of statistical values ​​for ABC control by optimizing weighting in the region of interest according to the presence of interfering objects (high-absorption materials such as bones, teeth, and various devices) superimposed on the object of ABC control, and the clinical situation. Therefore, the X-ray diagnostic apparatus 100 allows for real-time ABC control suitable for the region of interest by utilizing anatomical information according to the actual procedure. The X-ray diagnostic apparatus 100 allows for the reduction of radiation exposure to the subject P and improvement of image quality around the region of interest by setting X-ray conditions through appropriate ABC control.

[0060] Furthermore, according to the X-ray diagnostic apparatus 100 of this embodiment, when the position of an object moves in a plurality of X-ray images acquired in a time series, the range in which the object moves is determined as the target area. For example, according to this X-ray diagnostic apparatus 100, the target area is determined again in response to the movement of at least one of the holding arm 4 and the top plate, and statistical values ​​are recalculated based on the plurality of pixel values ​​included in the re-determined target area in response to the movement.

[0061] Furthermore, with this X-ray diagnostic device 100, when an object moves in multiple X-ray images over time due to the heartbeat of the subject P, the target region is determined by various image processing operations applied to the X-ray images corresponding to the end-systolic or end-diastolic phases of the electrocardiographic potential output from an external biosignal measurement device such as an electrocardiograph 8. Therefore, with this X-ray diagnostic device 100, depending on the actual situation of various procedures performed on the subject P (e.g., percutaneous coronary intervention (PCI)), information acquired from peripheral devices of the X-ray diagnostic device 100 such as the electrocardiograph 8 and anatomical information can be utilized to achieve real-time ABC control that is most suitable for the region of interest. This further reduces the radiation exposure to the subject P and further improves image quality around the region of interest.

[0062] (Examples of application) This application example involves the object including at least one of the following: a catheter 35 and a marker provided on a stent or balloon. In this case, the user's area of ​​interest may be pre-set as the stent or balloon by the control unit 12. In this application example, the determination function 91 further determines the region related to the stent or marker from among multiple sections by image processing of the X-ray image. The calculation function 93 then calculates statistical values ​​by assigning weights to the pixel values ​​in the region related to the stent or marker. To make the explanation more specific, the following description will focus on the case where the object includes both a catheter 35 and a stent.

[0063] The determination function 91 detects stents and determines the region related to the stent (hereinafter referred to as the stent region) by applying image processing for detecting stents in the X-ray image to the X-ray image. The stent region is, for example, a region that includes at least a part of the outer surface of the stent in the X-ray image. The image processing for detecting stents is implemented using known techniques such as various segmentation processes, image recognition processes, or trained models that have been trained to detect stents (for example, a trained neural network that realizes semantic segmentation). Specifically, the determination function 91 determines the stent region from among a plurality of pre-divided sections in the X-ray image.

[0064] Figure 5 shows an example of the target region 33, catheter 35, and stent 34 in an X-ray image 32. As shown in Figure 5, the catheter 35 is detected across six compartments. The thick lines indicating these six compartments, including the catheter 35, correspond to the target region 33. Also, as shown in Figure 5, the region of vertebral body Vb is determined across five compartments. The five compartments including vertebral body Vb correspond to the high-attenuation region. The region of the L-shaped target region 33 excluding the high-attenuation region is shown by diagonal lines in Figure 5. The region 39 shown in Figure 5 is the tip compartment, including the tip 37 of the catheter. The stent 34 shown in Figure 5 is located in the stent region 36 below the tip compartment 39. That is, the stent region 36 is adjacent to the tip compartment 39.

[0065] The calculation function 93 assigns weights to the pixel values ​​in the stent region 36 and calculates statistical values ​​using equation (1). For example, the calculation function 93 sets a greater weight for the pixel values ​​in the stent region 36 than the weight for the tip compartment 39. Specifically, the calculation function 93 sets a weight of 1 for the stent region 36, a weight of 0.7 for the tip compartment 39, and a weight of 0 for the terminal compartment. In addition, the calculation function 93 sets weights in the region of the catheter 35 from the compartment adjacent to the tip compartment 39 to the compartment adjacent to the terminal compartment, so that the weight gradually decreases from the tip compartment 39 to the terminal compartment.

[0066] Figure 6 shows an example of weights in the target region 33 excluding the high-absorption region. As shown in Figure 6, for example, the calculation function 93 sets the weight of the stent region 36, which includes the stent 34, to 100%, the weight of the tip compartment 39, which includes the tip 37 of the catheter, to 70%, and the weights of the two terminal compartments, which include the end 41 of the catheter, to 0%. The calculation function 93 also sets the weights from the compartment adjacent to the tip compartment 39 to the compartment adjacent to the terminal compartment, so that the weight gradually decreases from the tip compartment 39 towards the terminal compartment. At this time, the determination function 91 determines the calculation region by excluding the region with zero weight and the high-absorption region from the target region 33. The calculation region in Figure 6 has the stent region 36 corresponding to a weight of 100%, the tip compartment 39 corresponding to a weight of 70%, and the region corresponding to a weight of 30%.

[0067] The calculation function 93 calculates statistical values ​​for the target region 33 using multiple pixel values ​​and weights contained in the target region 33. Specifically, the calculation function 93 calculates statistical values ​​for the target region 33 by applying the weights and pixel values ​​in the calculation region to equation (1). The processing after the calculation of the statistical values ​​is the same as in the embodiment, so the explanation is omitted.

[0068] As a variation of this application example, the target object may be at least one of the following specified by the user: a vascular bifurcation and a lesion. A lesion is, for example, a calcified area. Specifically, the X-ray image is generated, for example, using a contrast agent and displayed on the monitor 10d. At this time, the determination function 91 determines the area relating to the vascular bifurcation and the calcification by image processing of the X-ray image. As a result, the bifurcation and the calcification area are highlighted in the X-ray image displayed on the monitor 10d. When the user specifies the vascular bifurcation and / or calcification area via the operation unit 12, the calculation function 93 sets the weight of the area including the vascular bifurcation and / or calcification area to the maximum value of 1, similar to the stent area 36 in the variation. As a result, the calculation function 93 assigns weights to the pixel values ​​in the area relating to the bifurcation or lesion and calculates statistical values. Other processes are the same as in this application example, so their explanation is omitted.

[0069] According to the X-ray diagnostic apparatus 100 of the embodiment described above, if the object further includes at least one of a stent and a marker provided on a balloon in addition to the catheter 35, the region relating to the stent or marker is further determined, and statistical values ​​are calculated by assigning weights to the pixel values ​​in the region relating to the stent 34 or marker. Furthermore, according to the X-ray diagnostic apparatus 100, if the object has at least one of a vascular bifurcation and a lesion specified by the user, the region relating to the bifurcation or lesion is further determined, and statistical values ​​are calculated by assigning weights to the pixel values ​​in the region relating to the bifurcation or lesion.

[0070] As a result, this X-ray diagnostic device 100 can perform appropriate ABC control according to the area and device of interest to the user. Other effects are the same as in the embodiment, so a description will be omitted.

[0071] When the technical concept of this embodiment is realized by an X-ray condition setting method, the X-ray condition setting method includes determining the region of the object in the X-ray image based on the X-ray image, calculating statistical values ​​for the region based on multiple pixel values ​​included in the determined region, and setting X-ray conditions for X-ray generation based on the calculated statistical values. The processing procedure corresponding to the X-ray condition setting method corresponds to the procedure for X-ray condition setting processing, so a description is omitted. Furthermore, the effects of the X-ray condition setting method are the same as in the embodiment, so a description is omitted.

[0072] According to at least the embodiments, modifications, and applications described above, it is possible to set X-ray conditions that can reduce radiation exposure and improve image quality.

[0073] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0074] 1 X-ray generating unit 1a x-ray tube 1b X-ray diaphragm 2. High-voltage generation unit 3 X-ray detection unit 3a Planar detector 3b Image Data Generation Unit 3b-1 Charge / Voltage Converter 3b-2 A / D converter 3b-3 Parallel-to-Serial Converter 3c gate driver 4 Holding Arms 5 berths 6 Mechanism 6a Holding arm movement mechanism 6b Bed transfer mechanism 7 Mechanism Control Unit 8. Electrocardiograph 9. Image Processing and Memory Unit 9a Image data storage unit 9b Image Processing Unit 10 Display 10a Display image memory 10b D / A converter 10c Display Control Unit 10d monitor 11 System Control Unit 12 Control section 31 X-ray image 32 X-ray image 33. Target Area 34 stents 35 Catheter 36 Stent Areas 37. Tip of the catheter 39 Front Section 41. End of catheter 91 Decision Function 93 Calculation function 95 Settings Function 100 X-ray diagnostic equipment

Claims

1. A determination unit that determines the region of the object in the X-ray image based on the X-ray image, A calculation unit that calculates statistical values ​​relating to the region based on a plurality of pixel values ​​included in the region, A setting unit that sets X-ray conditions related to X-ray generation based on the aforementioned statistical values, Equipped with, The object is a catheter, The determination unit further determines the region including the tip of the catheter, The calculation unit calculates the statistical value using a weight that gradually decreases from the tip towards the end of the catheter. X-ray diagnostic equipment.

2. If the object includes, in addition to the catheter, at least one of a stent and a marker provided on the balloon, The determination unit further determines the region relating to the stent or the marker, The calculation unit calculates the statistical value by assigning weights to the pixel values ​​in the region relating to the stent or the marker. The X-ray diagnostic apparatus according to claim 1.

3. The object in question is, in addition to the catheter, at least one of the following: a vascular bifurcation and a lesion specified by the user. The determination unit further determines the region relating to the bifurcation or the lesion, The calculation unit calculates the statistical value by assigning weights to the pixel values ​​in the region relating to the branch or the lesion. The X-ray diagnostic apparatus according to claim 1.

4. The determination unit, in response to the movement of at least one of the following, the holding arm that movably holds the X-ray tube that generates X-rays and the X-ray detector that faces the X-ray tube and detects the X-rays, and the top plate on which the subject is placed, determines the region again. The calculation unit, in response to the movement, recalculates the statistical value based on the plurality of pixel values ​​included in the re-determined region. The setting unit sets the X-ray conditions based on the statistical values ​​that have been recalculated. The X-ray diagnostic apparatus according to any one of claims 1 to 3.

5. A determination unit that determines the region of the object in the X-ray image based on the X-ray image, A calculation unit that calculates statistical values ​​relating to the region based on a plurality of pixel values ​​included in the region, A setting unit that sets X-ray conditions related to X-ray generation based on the aforementioned statistical values, Equipped with, The determination unit determines, in the X-ray image, a region of a high-absorbent material that superimposes on the object and has a higher X-ray absorption rate than a predetermined X-ray absorption rate, The calculation unit calculates the statistical value by excluding the region relating to the highly absorbent material from the region relating to the object. X-ray diagnostic equipment.

6. When the object moves in a series of X-ray images due to the heartbeat of the subject, the determination unit determines the region of the object by performing various image processing operations on the X-ray image corresponding to the end-systolic or end-diastolic phase of the electrocardiogram output from the electrocardiograph. The X-ray diagnostic apparatus according to any one of claims 1 to 5.

7. The determination unit determines the range in which the object moves as the region of the object when the position of the object moves in multiple X-ray images acquired in a time series. The X-ray diagnostic apparatus according to any one of claims 1 to 6.

8. Based on the X-ray image, the region of the object in the X-ray image is determined. Based on the multiple pixel values ​​included in the region, statistical values ​​relating to the region are calculated. Based on the aforementioned statistical values, the X-ray conditions related to X-ray generation are set. Equipped with, The object is a catheter, Determining the region of the object further involves determining the region including the tip of the catheter, The calculation of the aforementioned statistical value is performed using a weight that gradually decreases from the tip to the end of the catheter. X-ray condition setting method.

9. Based on the X-ray image, the region of the object in the X-ray image is determined. Based on the multiple pixel values ​​included in the region, statistical values ​​relating to the region are calculated. Based on the aforementioned statistical values, the X-ray conditions related to X-ray generation are set. Equipped with, Determining the region of the object involves determining in the X-ray image a region of a high absorber that superimposes on the object and has a higher X-ray absorption rate than a predetermined X-ray absorption rate. Calculating the aforementioned statistical value involves excluding the region relating to the high absorber from the region relating to the object, and then calculating the aforementioned statistical value. X-ray condition setting method.

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