X-ray diagnostic apparatus and medical image processing method

Abstract

This system detects the amount of displacement in X-ray images acquired by an X-ray diagnostic device and allows for the correction of the X-ray image's position. [Solution] The X-ray diagnostic apparatus according to the embodiment comprises an X-ray tube that generates X-rays, an X-ray detector that detects X-rays that have passed through a subject, an X-ray image acquisition means that collects an X-ray image based on the X-rays detected by the X-ray detector, a transmitting means that emits radio waves, a receiving means that receives the radio waves, a receiving data generation means that generates received data based on the radio waves received by the receiving means, and a correction means that corrects the position of the collected X-ray image based on the received data generated by the receiving data generation means.

Description

Technical Field

[0001] Embodiments of the present invention relate to an X-ray diagnostic apparatus and a medical image processing method.

Background Art

[0002] In order to extract a blood vessel image necessary for diagnosis from an X-ray image captured by an X-ray diagnostic apparatus, there is a technique called rotational DSA (Digital Subtraction Angiography) in which subtraction processing is performed on a mask image and a contrast image captured while rotating. However, if there is a displacement caused by, for example, the body movement of a patient who is the subject during imaging, a displacement occurs between the mask image and the contrast image, and a clear display image may not be obtained as a motion artifact. In order to reduce such motion artifacts, pixel shift processing for correcting in the X direction and the Y direction in pixel units for each frame of the captured X-ray image must be manually performed. For this reason, extra effort is required.

[0003] Furthermore, in the imaging of a contrast image performed following the imaging of the mask image, in order to eliminate or minimize the influence of vibrations of a C-arm or the like, the timing of the start of imaging is set as a parameter of the imaging sequence. The setting of this parameter is manually performed in the form of setting a waiting time based on empirical values or the like.

[0004] Also, when performing 3D imaging with an X-ray diagnostic apparatus, it is inevitable to correct for displacement due to sagging of the C-arm itself due to the angling operation of the C-arm. However, in order to perform correction for sagging, it is necessary to register in advance the amount of displacement at each angling of the C-arm as calibration data. Moreover, the calibration data must be measured and registered regularly, for example, every three months, which is an extra effort.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-88666 [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is to detect the amount of displacement of an X-ray image acquired by an X-ray diagnostic device and to correct the position of the X-ray image. However, the problems that the embodiments disclosed herein and in the drawings aim to solve 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]

[0007] The X-ray diagnostic apparatus according to this embodiment includes an X-ray tube that generates X-rays, an X-ray detector that detects X-rays that have passed through a subject, an X-ray image acquisition means that collects an X-ray image based on the X-rays detected by the X-ray detector, a transmitting means that emits radio waves, a receiving means that receives the radio waves, a receiving data generation means that generates received data based on the radio waves received by the receiving means, and a correction means that corrects the position of the collected X-ray image based on the received data generated by the receiving data generation means. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the configuration of an X-ray diagnostic apparatus according to the first embodiment. [Figure 2] Figure 1 is a block diagram that represents the functions performed by the processing circuit of the X-ray diagnostic device shown in Figure 1, using blocks. [Figure 3] Figure 1 is a perspective view of the imaging device in the X-ray diagnostic apparatus shown. [Figure 4] Figure 1 is an overall side view of the X-ray diagnostic equipment. [Figure 5]This diagram illustrates the operation of an imaging device equipped with a C-arm when performing rotational DSA imaging. [Figure 6] This figure shows an example of a mask image captured by the X-ray diagnostic apparatus according to the first embodiment. [Figure 7] This figure shows an example of a contrast image captured by the X-ray diagnostic apparatus according to the first embodiment. [Figure 8] This figure shows an example of a subtraction image generated by the X-ray diagnostic apparatus according to the first embodiment. [Figure 9] This diagram schematically shows the position of the subject's head when a mask image was captured. [Figure 10] This diagram schematically shows the position of the subject's head when a contrast image was captured. [Figure 11] This figure shows an example of point cloud data of a subject when a mask image was acquired. [Figure 12] This figure shows an example of point cloud data of a subject when a contrast image was acquired. [Figure 13] This diagram shows a flowchart illustrating an example of the medical image generation process performed by the X-ray diagnostic apparatus according to the first embodiment. [Figure 14] This diagram schematically illustrates the relationship between the X-ray image and the received data in each frame. [Figure 15] This is an overall side view illustrating an example of the configuration of an X-ray diagnostic apparatus according to the second embodiment. [Figure 16] This diagram shows a flowchart illustrating an example of the content of the imaging start control process performed by the X-ray diagnostic device in the second embodiment. [Figure 17] This diagram shows a flowchart illustrating the contents of the X-ray imaging process performed by the X-ray diagnostic apparatus according to the third embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, the X-ray diagnostic apparatus and the medical image processing method according to the present embodiment will be described with reference to the drawings. In the following description, components having substantially the same functions and configurations will be denoted by the same reference numerals, and duplicate descriptions will be made only when necessary.

[0010] 〔First Embodiment〕 FIG. 1 is a diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. In the following, the X-ray diagnostic apparatus 1 for angiography having a C-arm will be described as an example, but other types of X-ray imaging apparatuses such as a multi-purpose X-ray diagnostic apparatus or an X-ray TV bed apparatus may also be used as the X-ray diagnostic apparatus 1.

[0011] As shown in FIG. 1, the X-ray diagnostic apparatus 1 according to the present embodiment includes an imaging apparatus 3, a bed apparatus 5, a drive unit 7, an operation unit 9, an X-ray high voltage apparatus 11, a processing circuit 25, a storage circuit 27, a display unit 29, and an input interface 31. For ease of explanation, in the following, the longitudinal direction of the bed apparatus 5 will be the y-axis, the vertical direction will be the z-axis, and the direction orthogonal to the y-axis and the z-axis will be the x-axis as appropriate.

[0012] The imaging apparatus 3 includes an X-ray tube holder 19, an X-ray detector 21, and a holding device 23. The X-ray tube holder 19 holds an X-ray tube 13 that irradiates an object P with X-rays and an X-ray aperture 15 for narrowing down the X-rays irradiated from the X-ray tube 13.

[0013] The holding device 23 includes a C-arm 23a. The C-arm 23a supports the X-ray tube holder 19 including the X-ray tube 13 and the image receiving unit 40 including the X-ray detector 21. That is, the X-ray tube 13 of the X-ray tube holder 19 and the X-ray detector 21 of the image receiving unit 40 are supported by the C-arm 23a included in the holding device 23. The C-arm 23a is an example of an arm included in the imaging apparatus 3 for supporting the X-ray tube holder 19 and the image receiving unit 40, and other shaped arms may also be used. That is, the shape of the arm included in the imaging apparatus 3 is arbitrary as long as it can support the X-ray tube holder 19 and the image receiving unit 40.

[0014] The X-ray tube 13 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 X-ray high-voltage device 11 and supplying filament current. In the X-ray tube 13, X-rays are generated when thermionic electrons collide with the target. For example, the X-ray tube 13 includes a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermionic electrons. However, the type of X-ray tube 13 is not limited to the rotating anode type, and any type of X-ray tube can be applied.

[0015] The X-ray diaphragm 15 is located in front of the X-ray irradiation window in the X-ray tube 13. The X-ray diaphragm 15 has four diaphragm blades made of, for example, metal plates such as lead. The diaphragm blades are driven by a drive device according to the region of interest input by the operator via the control unit 9 or the input interface 31.

[0016] Specifically, the X-ray diaphragm 15 adjusts the area where X-rays are shielded to a desired size by sliding these diaphragm blades using a drive device. The adjusted diaphragm blades allow the X-ray diaphragm 15 to shield X-rays outside the aperture area. As a result, the X-ray diaphragm 15 focuses the X-rays generated by the X-ray tube 13 so that they are directed to the region of interest of the subject P, thereby suppressing unnecessary exposure to the subject P.

[0017] The X-ray detector 21 detects X-rays generated by the X-ray tube 13 in the X-ray tube holder 19. The X-ray detector 21 is, for example, 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 surface on which the multiple semiconductor elements of the X-ray detector 21 are arranged becomes the X-ray image receiving surface.

[0018] The electrical signals generated by multiple semiconductor detection elements upon X-ray incidence are output to an analog-to-digital converter (A / D converter), which is not shown in the diagram. The A / D converter converts the electrical signals into digital data. The A / D converter outputs the digital data to the processing circuit 25.

[0019] In this embodiment, the image receiving unit 40 is provided with an X-ray detector 21 and a displacement detector 24 for detecting the amount of displacement during X-ray imaging. For example, the X-ray diagnostic device 1 uses the displacement detector 24 to detect the amount of displacement of the subject P between the time of mask image acquisition and the time of contrast image acquisition. In the example in Figure 1, the image receiving unit 40 is composed of the X-ray detector 21 and the displacement detector 24.

[0020] A top plate 5a is provided on the upper surface of the patient device 5 to support the patient P. The top plate 5a of the patient device 5 is located between the X-ray tube 13 and the X-ray detector 21 and supports the patient P. The patient device 5 is also provided with an operating unit 9 for operating the imaging device 3 and the patient device 5. Based on the commands for operation from this operating unit 9, the drive unit 7 moves the imaging device 3 and the patient device 5. The drive unit 7 comprises an image receiving unit moving unit 71, an arm moving unit 73, a top plate moving unit 75, and an X-ray tube holding unit moving unit 77.

[0021] The image receiving unit moving unit 71 is a mechanism for moving the image receiving unit 40, the arm moving unit 73 is a mechanism for moving the C arm 23a of the holding device 23, the tabletop moving unit 75 is a mechanism for moving the tabletop 5a of the patient bed device 5, and the X-ray tube holding unit moving unit 77 is a mechanism for moving the X-ray tube holding unit 19. These mechanisms of the drive unit 7 constitute the moving mechanism in this embodiment.

[0022] The X-ray high-voltage device 11 includes an electrical circuit such as a transformer and a rectifier, a high-voltage generator, and an X-ray control device. The high-voltage generator generates the high voltage applied to the X-ray tube 13 and the filament current supplied to the X-ray tube 13. The X-ray control device controls the output voltage according to the X-rays irradiated by the X-ray tube 13. The X-ray high-voltage device 11 may be installed in the holding device 23 or in a location other than the holding device 23.

[0023] The processing circuit 25 controls the operation of the entire X-ray diagnostic apparatus 1 in accordance with electrical signals related to input operations output from the operation unit 9 or the input interface 31. The processing circuit 25 has hardware resources such as a processor including a CPU (Central Processing Unit), MPU (Micro Processing Unit), and GPU (Graphics Processing Unit), and memory including ROM (Read Only Memory) and RAM (Random Access Memory).

[0024] In this embodiment, the various processing functions performed in the processing circuit 25 are stored in the memory circuit 27 in the form of a program that can be executed by a computer. The processing circuit 25 is a processor that realizes the functions corresponding to each program by reading and executing the program from the memory circuit 27. In other words, each circuit, when it has read a program, will have the function corresponding to the program that has been read.

[0025] Figure 2 is a block diagram showing the functions performed by the processing circuit 25 according to this embodiment, represented by blocks. As shown in Figure 2, in this embodiment, the processing circuit 25 implements a basic control function 251, an X-ray image acquisition function 252, a received data generation function 253, a correction function 254, a display image generation function 255, and a display function 256, all through a processor that executes a program loaded into memory.

[0026] The basic control function 251 controls the overall operation of the X-ray diagnostic apparatus 1. In particular, in this embodiment, it controls the drive of the drive unit 7 to control the position and orientation of the holding device 23, the X-ray tube holding unit 19, and the image receiving unit 40. The processing circuit 25 that executes the basic control function 251 corresponds to the basic control unit in this embodiment.

[0027] The X-ray image acquisition function 252 acquires X-ray images based on the X-rays detected by the X-ray detector 21 of the imaging unit 40. In this embodiment, since the X-ray diagnostic device 1 performs rotational DSA imaging and 3D imaging, the X-ray image acquisition function 252 performs X-ray imaging while rotating the C-arm 23a and sequentially acquires multiple consecutive X-ray images. The X-ray images acquired by the X-ray image acquisition function 252 are stored, for example, in the memory circuit 27. The processing circuit 25 that executes the X-ray image acquisition function 252 corresponds to the X-ray image acquisition means in this embodiment.

[0028] The received data generation function 253 generates received data. As will be described in detail later, the displacement detector 24 is equipped with a receiver 24b (Figure 3) that receives radio waves, and the received data generation function 253 generates received data based on the radio waves received by this receiver 24b. The received data generated by the received data generation function 253 is stored in, for example, the memory circuit 27. The processing circuit 25 that executes the received data generation function 253 corresponds to the received data generation means in this embodiment.

[0029] The correction function 254 corrects the X-ray image acquired by the X-ray image acquisition function 252. As will be described in detail later, the correction function 254 corrects the position of the acquired X-ray image based on the received data generated by the received data generation function 253. The processing circuit 25 that executes the correction function 254 corresponds to the correction means in this embodiment.

[0030] The display image generation function 255 generates a display image for display on the display unit 29 based on the collected X-ray image. This display image is a so-called medical image. When the display image generation function 255 generates a display image, it uses the X-ray image corrected by the correction function 254. Therefore, if the position has been corrected by the correction function 254, the display image generation function 255 generates a display image using the X-ray image of the corrected position. Alternatively, if the X-ray image has been downsampled by the correction function 254, the display image generation function 255 generates a display image based on the downsampled series of X-ray images. The processing circuit 25 that executes the display image generation function 255 corresponds to the display image generation means in this embodiment.

[0031] The display function 256 displays, for example, a display image generated by the display image generation function 255 or an X-ray image stored in the memory circuit 27 on the display unit 29. For example, if a display image is stored in the memory circuit 27, the display function 256 reads this display image from the memory circuit 27 and displays it on the display unit 29. The processing circuit 25 that executes the display function 256 corresponds to the display function 256 in this embodiment.

[0032] Furthermore, the basic control function 251, X-ray image acquisition function 252, received data generation function 253, correction function 254, display image generation function 255, and display function 256 are not limited to being implemented by a single processing circuit. A processing circuit can be configured by combining multiple independent processors, with each processor executing a program to realize the basic control function 251, X-ray image acquisition function 252, received data generation function 253, correction function 254, display image generation function 255, and display function 256.

[0033] As shown again in Figure 1, the memory circuit 27 is a circuit commonly referred to as memory, and is composed of storage devices such as HDDs (Hard Disk Drives), SSDs (Solid State Drives), and integrated circuit memory devices that store various types of information. For example, the memory circuit 27 stores projection data and image data, data on the position and angle of the C-arm 23a of the holding device 23 and the position and angle of the top plate 5a of the bed device 5, and programs corresponding to various functions that are read and executed by the processing circuit 25.

[0034] The memory circuit 27 may be a drive device that reads and writes various information to portable storage media such as CDs (Compact Discs), DVDs (Digital Versatile Discs), and flash memory, as well as semiconductor memory elements such as RAM (Random Access Memory), in addition to HDDs and SSDs. Furthermore, the storage area of ​​the memory circuit 27 may be located in an external storage device connected to the X-ray diagnostic apparatus 1 via a network.

[0035] The display unit 29 consists of, for example, a display that displays medical images, an internal circuit that supplies display signals to the display, and peripheral circuits such as connectors and cables that connect the display and the internal circuit. The internal circuit generates display data by superimposing supplementary information such as subject information and projection data generation conditions onto the image data. Next, the internal circuit performs D / A conversion on the obtained display data.

[0036] In this embodiment, the display unit 29 displays a GUI (Graphical User Interface) or the like for receiving various operations from the operator. As the display unit 29, 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 can be used as appropriate.

[0037] Furthermore, the display unit 29 may be composed of a device intended for fixed installation, known as a desktop type, or it may be composed of a portable tablet terminal or the like that can communicate wirelessly with the processing circuit 25.

[0038] The input interface 31 receives various input operations from the operator and converts the received input operations into electrical signals, which are then output to the processing circuit 25. For example, the input interface 31 receives from the operator operations for operating the imaging device 3 and the patient bed device 5, X-ray conditions related to X-ray generation, and conditions related to image processing performed by the display image generation function 255.

[0039] The input interface 31 can be, for example, a mouse, keyboard, trackball, switch, button, joystick, foot switch, touchpad, or touch panel display, as appropriate. The input interface 31 is provided, for example, on the holding device 23. Furthermore, if the input interface 31 consists of a touchpad or touch panel, it may be provided integrally with the display unit 29. In other words, the display unit 29 can also be made to have the functions of the input interface 31.

[0040] In this embodiment, the input interface 31 is not limited to those comprising physical operating components such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display.

[0041] For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device located separately from the main unit of the device, and outputs this electrical signal to the processing circuit 25, is also included as an example of an input interface 31. The input interface 31 may also consist of the processing circuit 25 and a wireless communication-enabled tablet terminal or the like.

[0042] Next, the configuration of the X-ray diagnostic apparatus 1 according to this embodiment will be described in more detail based on Figures 3 and 4. Figure 3 shows a perspective view of the imaging device 3 in the X-ray diagnostic apparatus 1 shown in Figure 1, and Figure 4 shows an overall side view of the X-ray diagnostic apparatus 1 shown in Figure 1.

[0043] As shown in Figures 3 and 4, one end of the C-arm 23a in the X-ray diagnostic apparatus 1 is provided with an X-ray tube holder 19, and the other end is provided with an image receiving unit 40. The C-arm 23a is fixed in place with both the X-ray tube holder 19 and the image receiving unit 40 facing each other.

[0044] Furthermore, rails are provided on the back or side of the C-arm 23a, and the rails of the C-arm 23a are held slidably by clamping them with the connecting portion 50 provided on the fixed arm 52. In other words, the C-arm 23a held by the connecting portion 50 can slide in an arc shape along the direction of arrow A on the C-arm 23a.

[0045] Furthermore, the connecting part 50 is rotatably attached to the fixed arm 52. That is, the connecting part 50 rotates in the direction of arrow B about the y-axis. Therefore, the C-arm 23a held by the connecting part 50 also rotates in the direction of arrow B about the y-axis. This allows the X-ray tube 13 and the X-ray detector 21 to move around the subject P lying on the tabletop 5a of the patient device 5, rotating from any direction, enabling continuous X-ray imaging of the subject P.

[0046] Furthermore, in this embodiment, a displacement detector 24 is provided in the image receiving unit 40 together with the X-ray detector 21. The displacement detector 24 in this embodiment is configured to include one transmitter 24a that emits radio waves and two receivers 24b that receive these radio waves. In other words, the transmitter 24a and receivers 24b of the displacement detector 24 are provided in the image receiving unit 40 together with the X-ray detector 21.

[0047] For example, in this embodiment, the transmitter 24a emits millimeter-wave radar or a laser as radio waves, and the receiver 24b receives these radio waves reflected from the subject P or the like. The X-ray diagnostic apparatus 1 in this embodiment detects the movement of the subject P based on the radio waves received by the receiver 24b. The transmitter 24a that emits radio waves corresponds to the transmitting means in this embodiment, and the receiver 24b that receives radio waves corresponds to the receiving means in this embodiment.

[0048] The examination table device 5 comprises a top plate 5a on which the subject P is placed, and a stand 5b that supports the top plate 5a. The top plate 5a is movable in the vertical and horizontal directions, so that the subject P is appropriately positioned between the X-ray tube 13 of the X-ray tube holder 19 and the X-ray detector 21 of the image receiving unit 40.

[0049] As explained with reference to Figures 1 and 2, these rotational and movement operations in the X-ray diagnostic apparatus 1 are realized by the control of the drive unit 7 by the basic control function 251 of the processing circuit 25. Furthermore, these rotational and movement operations may be performed automatically by the X-ray diagnostic apparatus 1 based on settings, or they may be performed based on operation input from an operator via the operation unit 9 or input interface 31.

[0050] Next, rotational DSA imaging performed by the X-ray diagnostic apparatus 1 according to this embodiment will be explained using Figures 5 to 8. Figure 5 is a diagram illustrating the operation of the imaging apparatus 3 equipped with a C-arm 23a when performing rotational DSA imaging. Figure 6 is a diagram showing an example of a mask image, Figure 7 is a diagram showing an example of a contrast image, and Figure 8 is a diagram showing an example of a subtraction image.

[0051] As shown in Figure 5, in rotational DSA imaging, the C-arm 23a rotates around the subject P while continuously performing X-ray imaging, and multiple mask images and multiple contrast images are collected. In this embodiment, the imaging technique in which X-ray imaging is performed continuously while rotating the holding device 23 that holds the X-ray tube 13 is called continuous X-ray imaging.

[0052] The mask image illustrated in Figure 6 is an X-ray image taken immediately before the contrast agent was injected into subject P. The contrast image illustrated in Figure 7 is an X-ray image taken when the contrast agent was passing through the target blood vessel. The subtraction image illustrated in Figure 8 is an image generated by digitally subtracting the mask image illustrated in Figure 6 from the contrast image illustrated in Figure 7.

[0053] A subtraction image is obtained by subtracting the mask image, which is continuously captured during the first rotation of the C-arm 23a, from the contrast image, which is continuously captured during the second rotation of the C-arm 23a. When generating this subtraction image, there must be no displacement of the subject P between the time the mask image is captured and the time the contrast image is captured. If the subject P is displaced due to body movement or other reasons, motion artifacts will occur in the subtraction image.

[0054] The imaging position of the mask image captured during the first rotation of the C-arm 23a and the imaging position of the contrast image captured during the second rotation of the C-arm 23a coincide. In other words, the imaging positions of the mask image and the contrast image in the same frame coincide. Therefore, if there is no body movement of the subject P, the contrast agent image is clearly emphasized and extracted in the subtraction image. Conversely, if there is body movement of the subject P, motion artifacts will occur in the subtraction image. For this reason, in the X-ray diagnostic apparatus 1 according to this embodiment, the amount of displacement due to body movement of the subject P is detected by the displacement detector 24, and the position of the captured X-ray image is corrected to suppress the occurrence of motion artifacts.

[0055] Various devices can be used for the displacement detector 24 provided in the X-ray diagnostic apparatus 1 according to this embodiment. For example, when using a millimeter-wave radar for the displacement detector 24, the transmitter 24a and receiver 24b can be the IWR series from TI or the A1111 from Acconeer. By using a millimeter-wave radar, data such as distance, angle, and velocity to the object can be obtained by measurement using the FMCW (Frequency Modulated Continuous Wave) method. The measurement device using a millimeter-wave radar can be configured, for example, with an RF circuit section that generates, transmits, and receives high-frequency radio millimeter-wave signals, an analog signal processing section that performs low-pass filtering and A / D conversion, and a digital section such as a microcontroller that performs FFT processing of the digitally converted data.

[0056] The components necessary for these millimeter-wave radar measurements are available in a compact CMOS-based millimeter-wave radar device, and such a device can be used as a displacement detector 24. Furthermore, due to its compact design, it can be positioned near the X-ray detector 21 in the image receiving unit 40 without interfering with it.

[0057] Furthermore, a laser can be used as the displacement detector 24. For example, when using a laser, LiDAR can be used as the transmitter 24a and receiver 24b. LiDAR is an abbreviation for Light Detection And Ranging or Laser Imaging Detection And Ranging, and it measures the time difference between when near-infrared laser light is emitted in a pulsed manner and when it hits an object and bounces back. By using millimeter-wave radar and lasers as radio waves to detect the displacement of an object in this way, it becomes possible to measure three-dimensional distances, which was difficult with two-dimensional measurements such as optical cameras, and the displacement of the subject P can be detected with high accuracy.

[0058] Next, an example of how to calculate the angle θ when subject P moves will be explained based on Figures 9 and 10. Figure 9 schematically shows the position of subject P's head when the mask image is captured, and Figure 10 schematically shows the position of subject P's head when the contrast image is captured. As can be seen by comparing Figures 9 and 10, subject P's head, which should not move between the capture of the mask image and the capture of the contrast image, has moved slightly in a clockwise direction. As a result, the position of the tip of subject P's nose has moved from position W to position W'.

[0059] Two receivers 24b are positioned at a distance l apart, and each of these two receivers 24b receives radio waves emitted from transmitter 24a and reflected off the tip of the subject P's nose. The y-axis is the body axis, and the z-axis is the reference axis (0 degrees). Let θ be the angle between one of the two receivers 24b and the reference axis. Let d be the distance from one of the two receivers 24b to the tip of the subject P's nose, and let d + △d be the distance from the other receiver 24b to the tip of the subject P's nose. In this case, △d can be expressed by the following equation (1). △d=lsinθ ··· Equation (1)

[0060] Furthermore, if we denote the phase difference of the radio waves as Φ and the wavelength of the radio waves as λ, then Φ can be expressed by the following equation (2). Φ = 2π × △d / λ ... Equation (2)

[0061] Substituting equation (1) into equation (2), we obtain equation (3) below. Φ=2π×lsinθ / λ ··· Equation (3) Transforming equation (3), θ becomes equation (4) below. θ = sin -1 (λΦ / 2πl) ··· Equation (4)

[0062] This theory allows for the calculation of the angle θ. Furthermore, since the distance d to the tip of the nose can also be measured, the displacement detector 24 can detect when the tip of the subject P's nose moves, and thus detect the specific amount of displacement. In this way, by using the displacement detector 24, it is possible to measure not only distance but also angle, allowing for the detection of body movements such as head rotation of the patient with high accuracy.

[0063] In Figures 9 and 10, the movement of a point, the tip of the nose of subject P, was detected. However, in the X-ray diagnostic apparatus 1 according to this embodiment, the entire body of subject P is represented as point cloud data, and this point cloud data is used as received data to detect the amount of displacement of subject P. That is, the presence or absence of body movement of subject P and the amount of displacement are detected by the difference between the point cloud data of subject P when the mask image is captured and the point cloud data of subject P when the contrast image is captured. If the displacement detector 24 is configured with a two-dimensional optical camera, it is difficult to detect movement in the z-axis direction (height direction). However, by configuring the displacement detector 24 with a transmitter 24a that emits radio waves and a receiver 24b that receives radio waves, three-dimensional measurement of subject P becomes possible.

[0064] Figures 11 and 12 show examples of point cloud data representing the entire subject P lying supine on the top plate 5a of the bed device 5. Specifically, Figure 11 shows an example of point cloud data of subject P when a mask image is acquired, and Figure 12 shows an example of point cloud data of subject P when a contrast image is acquired. In the point cloud data of the entire body of subject P, each part of subject P is captured as a point, and the entire subject P is represented by connecting these points to each other. The movement of each point itself is detected in the manner described in Figures 9 and 10 above.

[0065] The displacement detector 24 in this embodiment uses, for example, millimeter-wave radar or laser as radio waves. Since these millimeter-wave radars or lasers are not affected by the subject P's clothing, even if the subject P is lying supine on the tabletop 5a and covered with a surgical drape, the displacement caused by the subject P's body movement can be detected. Therefore, the displacement of the subject P detected by the displacement detector 24 can be applied to areas other than the head, which is not covered by the drape. In other words, the entire body of the subject P, including the chest, abdomen, and lower limbs, can be used as the detection target using the displacement detector 24. This allows for a wider range of detection of the subject P's body movement compared to detecting the subject P's body movement using existing optical cameras or the like.

[0066] As can be seen by comparing the point cloud data, which is the received data in Figures 11 and 12, body movement occurs in the subject P between the time the mask image is captured and the time the contrast image is captured. By representing the subject P with point cloud data measured in three dimensions, it becomes possible to accurately grasp the nature of the body movement and to accurately detect the amount of displacement of the subject P.

[0067] In other words, when using existing optical cameras, the subject P is basically a two-dimensional image. Therefore, the amount of displacement with respect to the angle when the subject P rotates their head in the rotational direction relative to the body axis cannot be measured with existing optical cameras. In this case, the amount of displacement with respect to the angle of the head is not taken into consideration, and the correction of the displacement is based on simple two-dimensional coordinate data, so it is not possible to accurately correct the position of the X-ray image. In contrast, when using the displacement detector 24 according to this embodiment, the body movement of the subject P can be measured in three dimensions, so the position correction of the X-ray image can be performed based on three-dimensional coordinates, and the accuracy of the correction can be improved.

[0068] However, the point cloud data of subject P is merely one example of received data generated based on radio waves received by the receiver 24b of the displacement detector 24. The type of received data generated by the receiver 24b based on the radio waves it receives and the detection of the movement of subject P are arbitrary. In other words, as long as it is possible to generate received data based on the radio waves received by the receiver 24b, detect the movement of subject P based on this generated received data, and correct the position of the acquired X-ray image, the format of the generated received data is not limited to point cloud data of subject P.

[0069] Next, the medical image generation process performed by the X-ray diagnostic apparatus 1 according to this embodiment will be described based on Figure 13. The medical image generation process shown in Figure 13 is realized by the processing circuit 25 reading and executing the medical image generation program stored in the memory circuit 27. Furthermore, the medical image generation process in Figure 13 exemplifies the process when the X-ray diagnostic apparatus 1 performs the rotational DSA imaging described above.

[0070] As shown in Figure 13, the X-ray diagnostic device 1 collects a mask image (step S10). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 collects a mask image by rotating the C-arm 23a around the subject P and continuously capturing multiple X-ray images. When this mask image is collected, no contrast agent is injected into the blood vessels of the subject P.

[0071] Furthermore, in this embodiment, when collecting mask images, the received data generation function 253 in the processing circuit 25 of the X-ray diagnostic apparatus 1 collects mask images in synchronization with the reception of radio waves received by the receiver 24b of the displacement detector 24. More specifically, in this embodiment, point cloud data of the subject P at the time of mask image acquisition is generated based on the radio waves received by the receiver 24b of the displacement detector 24, and saved as received data for each frame. That is, the captured mask image and the received data based on the point cloud data of the subject P at the time of mask image acquisition are collected in synchronization for each frame. In this embodiment, the collected series of mask images and the received data associated with these mask images are stored, for example, in the memory circuit 27. For this reason, the memory circuit 27 holds the collected mask images and the generated received data, associated with the imaging angle of the mask image.

[0072] Next, as shown in Figure 13, the X-ray diagnostic device 1 collects contrast images (step S12). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 collects contrast images by rotating the C-arm 23a again around the subject P and continuously acquiring multiple X-ray images. However, when the contrast images are acquired, a contrast agent is injected into the blood vessels of the subject P.

[0073] Furthermore, in this embodiment, when acquiring contrast images, the received data generation function 253 in the processing circuit 25 of the X-ray diagnostic apparatus 1 acquires contrast images in synchronization with the radio waves received by the receiver 24b of the displacement detector 24. More specifically, in this embodiment, point cloud data of the subject P at the time of contrast image acquisition is generated based on the radio waves received by the receiver 24b of the displacement detector 24, and saved as received data for each frame. That is, the acquired contrast image and the received data based on the point cloud data of the subject P at the time of acquisition of this contrast image are acquired in synchronization for each frame. In this embodiment, a series of acquired contrast images and the received data associated with these multiple contrast images are stored, for example, in the memory circuit 27. For this reason, the memory circuit 27 holds the acquired contrast images and the generated received data, associated with the imaging angle of the contrast images.

[0074] Next, as shown in Figure 13, the X-ray diagnostic device 1 performs a process to correct the position of the collected X-ray image (step S14). In this embodiment, the correction function 254 in the processing circuit 25 of the X-ray diagnostic device 1 corrects the position of the collected X-ray image. Specifically, the X-ray diagnostic device 1 reads the received data of the same frame from the memory circuit 27, compares the two, determines whether or not there is body movement of the subject P, and corrects the position of the X-ray image if it is determined that there is body movement.

[0075] Figure 14 schematically illustrates the relationship between the X-ray image and the received data in each frame. As shown in Figure 14, for example, when acquiring a mask image, suppose the C-arm 23a rotates around the subject P and acquires X-ray images for n frames, from frame 1 to frame n. Corresponding to these n X-ray images, n pieces of received data representing the subject P as point cloud data are also generated and stored in the memory circuit 27. In other words, the mask image and received data acquired in the same frame are stored in association.

[0076] Next, when acquiring the contrast image, the C-arm 23a rotates again around the subject P at the same angle and orientation, and X-ray images are taken for n frames, from frame 1 to frame n. These n X-ray images correspond to n received data points representing the subject P as point cloud data, which are then stored in the memory circuit 27. In other words, the contrast image and the received data acquired in the same frame are stored in association with each other.

[0077] Here, "identical frame" means that the rotation angle and orientation of the C-arm 23a are the same. In other words, in the same frame, if there is no movement of the subject P, the received data representing the subject P as a point cloud will be the same.

[0078] In step S14, in order to determine whether or not the subject P moved, the X-ray diagnostic device 1 compares the received data in the same frame to determine whether or not the subject P moved between the time the mask image was captured and the time the contrast image was captured. In this embodiment, for example, if the difference between the received data when the mask image was captured and the received data when the contrast image was captured is greater than the first threshold, it is determined that the subject P moved.

[0079] For example, for frame 1, the received data when the mask image of frame 1 is captured is compared with the received data when the contrast image of frame 1 is captured to determine whether there was any movement of the subject P. In this embodiment, the difference value of the point cloud data of the two received data is calculated, and if this difference value is greater than a first threshold, it is determined that there was movement of the subject P. That is, the difference between each point in the point cloud data of the mask image and each point in the point cloud data of the contrast image is calculated as a vector quantity, and if the sum of the absolute values ​​of these vector quantities is greater than a first threshold, it is determined that there was movement of the subject P.

[0080] If body movement is detected, the X-ray diagnostic device 1 corrects the position of the X-ray image. For example, the X-ray diagnostic device 1 calculates the amount of displacement of the subject P based on the received data and applies pixel shift processing to the X-ray image. More specifically, the amount of displacement of the contrast image relative to the mask image is represented by a vector quantity, and the displacement of the contrast image is corrected based on this vector quantity. When correcting the contrast image, the vector quantity is converted to a correction value corresponding to a two-dimensional image as needed, and the contrast image is corrected.

[0081] In step S14, the correction function 254 in the processing circuit 25 of the X-ray diagnostic device 1 performs the process of correcting the X-ray image for all frames 1 to n. In this embodiment, if the difference between the received data at the time of mask image acquisition and the received data at the time of contrast image acquisition is less than or equal to the first threshold, it is determined that there was no movement of the subject P, and no correction of the X-ray image is performed.

[0082] Furthermore, in this embodiment, the X-ray image with corrected position is stored in the memory circuit 27 in place of the original X-ray image. That is, when a pixel shift process is performed on a contrast image to correct its position, the contrast image with corrected position is stored in the memory circuit 27 as the contrast image of the corresponding frame.

[0083] Next, as shown in Figure 13, the X-ray diagnostic apparatus 1 performs a process to generate a subtraction image (step S16). In this embodiment, the display image generation function 255 in the processing circuit 25 of the X-ray diagnostic apparatus 1 generates a subtraction image based on the mask image and the contrast image.

[0084] Specifically, the X-ray diagnostic device 1 generates a subtraction image by performing a subtraction process on the contrast image based on the mask image. In the example in Figure 14, first, the mask image and contrast image of frame 1 are read from the memory circuit 27, and the mask image of frame 1 is used to perform a subtraction process on the contrast image of frame 1 to generate a subtraction image of frame 1. In this embodiment, positional correction may have been applied to the contrast image, but when generating the subtraction image, it is not necessary to be aware of whether or not positional correction has been applied to the contrast image.

[0085] When generating subtraction images, even if a shift occurs due to the subject P's body movement between the time the mask image was captured and the time the contrast image was captured, the amount of shift is corrected in the correction process in step S14 and stored in the memory circuit 27. Therefore, the X-ray diagnostic apparatus 1 according to this embodiment can obtain subtraction images with suppressed motion artifacts. The generated subtraction images are stored and retained, for example, in the memory circuit 27.

[0086] Next, as shown in Figure 13, the X-ray diagnostic apparatus 1 generates a display image based on the subtraction image generated in step S16 (step S18). In this embodiment, the display image generation function 255 in the processing circuit 25 of the X-ray diagnostic apparatus 1 generates the display image based on the subtraction image. For example, the X-ray diagnostic apparatus 1 generates the display image by displaying the subtraction image continuously over time. The generated display image is stored and held in, for example, the memory circuit 27.

[0087] Next, as shown in Figure 13, the X-ray diagnostic apparatus 1 displays the display image generated in step S18 (step S20). In this embodiment, the display function 256 in the processing circuit 25 of the X-ray diagnostic apparatus 1 reads the display image from the memory circuit 27 and displays it on the display unit 29. The operator can change the frame of the subtraction image displayed on the display unit 29 by, for example, making an operation input via the input interface 31. That is, the subtraction images from frame 1 to frame n can be arbitrarily displayed on the display unit 29. From this viewpoint, in this embodiment, the subtraction image generated in step S16 can also be said to be a type of display image. With this step S20, the medical image generation process according to this embodiment is completed.

[0088] In this medical image generation process, in step S14, contrast images in which body movement is detected are subjected to pixel shift processing to correct the positional shift of the contrast images. Therefore, artifacts caused by the subject P's body movement can be suppressed when generating subtraction images and display images. However, the process for correcting the position of the contrast images is not limited to pixel shift processing; various other processes can be applied.

[0089] For example, in rotational DSA imaging or 3D imaging, if body movement of subject P is detected, the corresponding frame can be omitted. Specifically, the correction function 254, for example, if the difference value of subject P's body movement in frame m becomes greater than the second threshold, determines that body movement occurred in frame m, and omits frame m to avoid using it. In other words, if the difference value calculated based on the received data of two identical frames, a mask image and a contrast image, is greater than the second threshold, it determines that body movement occurred, and corrects the positions of the mask images and contrast images excluding the affected mask image and contrast image from among multiple mask images and multiple contrast images.

[0090] In this case, for example, the correction function 254 deletes the X-ray image from the memory circuit 27. That is, it deletes the mask image and contrast image of frame m, in which motion was determined to have occurred, from the memory circuit 27. Therefore, the display image generation function 255 does not generate a subtraction image of frame m in which motion occurred. Furthermore, the display image generation function 255 generates the display image without using the subtraction image of frame m in which motion occurred. In this case, the display image generation function 255 cannot use the X-ray image of the angle of the C-arm 23a that images frame m, but the X-ray images of frames m-1 and m+1, which show the angles of the C-arm 23a before and after frame m, can be used to generate the display image.

[0091] Therefore, in rotational DSA imaging, the display image may appear as if the X-ray image of frame m has been skipped, but the occurrence of motion artifacts can be suppressed. On the other hand, in 3D imaging, the display image is reconstructed based on the collected X-ray images, so although the X-ray image of frame m is downsampled, which may cause a degradation in resolution, it is thought that this can be sufficiently compensated for by the X-ray images of other frames. In other words, in this embodiment, the practice of downsampled and not using the X-ray image of frame m in which body movement is detected is also considered a type of correction of the position of the X-ray image.

[0092] As described above, according to the X-ray diagnostic apparatus 1 of this embodiment, when body movement of the subject P is detected based on the data received by the displacement detector 24, the position of the X-ray image is corrected, thereby making it possible to obtain a display image that suppresses the occurrence of artifacts due to the body movement of the subject P. In other words, based on the amount of displacement detected by the displacement detector 24, pixel shift processing can be automatically performed to correct the X and Y directions on a pixel-by-pixel basis for each frame in which the X-ray image is captured.

[0093] More specifically, the difference between the point cloud data of subject P at the time of mask image acquisition and the point cloud data of subject P at the time of contrast image acquisition is calculated as a difference value. If this difference value is greater than a first threshold, it is determined that subject P has moved, and pixel shift processing is applied to the contrast image to correct the position. As a result, motion artifacts in the subtraction image generated based on the mask image and contrast image can be reduced.

[0094] [Second Embodiment] The X-ray diagnostic apparatus 1 according to the second embodiment, in addition to the first embodiment described above, uses a displacement detector 24 to detect vibrations when the C-arm 23a is stopped, and controls the start timing of continuous X-ray imaging, which is performed by rotating the holding device 23 that holds the X-ray tube 13. More specifically, in the first embodiment described above, the displacement detector 24 is used to detect vibrations when the C-arm 23a is stopped, and controls the start timing of contrast image acquisition when the C-arm 23a has finished acquiring the mask image during rotational DSA imaging. The differences from the first embodiment described above will be explained below.

[0095] Figure 15 shows an overall side view of the X-ray diagnostic apparatus 1 according to this embodiment, and corresponds to Figure 4 of the first embodiment described above. As shown in Figure 15, in the X-ray diagnostic apparatus 1 according to this embodiment, for example, a marker 60 is provided on the top plate 5a as a reference point. The marker 60 is an example of a fixed reference point with respect to the C-arm 23a on which the displacement detector 24 is provided. In other words, the reference point is a fixed point with respect to the transmitter 24a and the receiver 24b.

[0096] Furthermore, the marker 60 can be set as a reference point at any position as long as it is a relatively fixed component when X-ray imaging of the subject P. In addition, the marker 60 can be made of any component that reflects the radio waves emitted by the transmitter 24a. The size of the marker 60 is also arbitrary, but it must be large enough so that the radio waves reflected by the marker 60 can be received by the receiver 24b.

[0097] In this embodiment, the X-ray diagnostic apparatus 1 detects vibrations of the C-arm 23a using a displacement detector 24 provided on the image receiving unit 40 when the C-arm 23a is stopped. Specifically, the transmitter 24a of the displacement detector 24 emits radio waves, and the receiver 24b receives the radio waves reflected by the marker 60, thereby detecting vibrations of the C-arm 23a. In other words, the marker 60 is fixed, and the amount of displacement in distance and direction relative to this marker 60 is detected as vibrations of the C-arm 23a.

[0098] However, the reference point does not necessarily have to be physically added, as in the case of this marker 60. For example, the edge of the top plate 5a may be used as a reference point, and the displacement detector 24 may detect the amount of displacement. In particular, when the X-ray diagnostic device 1 is an angiography device, the leading edge of the top plate 5a has a certain thickness in order to ensure the shape and strength of the top plate 5a. For this reason, when X-ray imaging is performed, the leading edge of the top plate 5a often appears in the X-ray image. For this reason, it is considered quite possible for the displacement detector 24 to detect vibration by using the edge of the top plate 5a as a reference point.

[0099] Alternatively, the reference point can be virtually set within the system. For example, by specifying a reference point within the system for 3D calibration data, it is possible to capture changes over time. Furthermore, it is possible to detect vibrations by using any point in the point cloud data of the subject P acquired using the displacement detector 24 as a reference point.

[0100] Figure 16 is a flowchart illustrating the contents of the imaging start control process performed by the X-ray diagnostic apparatus 1 in this embodiment. The imaging start control process shown in Figure 13 is realized by the processing circuit 25 reading and executing the imaging start control process program stored in the memory circuit 27. Furthermore, this imaging start control process is performed between the mask image collection process in step S10 and the contrast image collection process in step S12 in the medical image generation process shown in Figure 13.

[0101] In other words, the C-arm 23a rotates around the subject P and captures multiple mask images. After capturing these multiple mask images, the C-arm 23a returns to its starting position to capture the next contrast image. That is, the position of the C-arm 23a when it starts capturing the mask images is the same as the position of the C-arm 23a when it starts capturing the contrast images. At the starting position, the C-arm 23a waits to begin capturing the contrast image.

[0102] However, even if the C-arm 23a is stopped and waiting, due to its structure, vibrations inevitably remain associated with the rotation of the C-arm 23a to acquire the mask image. When the C-arm 23a vibrates, the X-ray tube 13 and X-ray detector 21 also vibrate. Although these vibrations of the C-arm 23a subside after a reasonable amount of time, this would require a long time to start acquiring the contrast image. For this reason, a waiting time is set in advance between the completion of mask image acquisition and the start of contrast image acquisition. This pre-set time is sufficient to roughly eliminate the effect of vibrations on contrast image acquisition. For example, the time setting is such that contrast image acquisition starts 2 seconds and 3 minutes after the C-arm 23a returns to its starting position after mask image acquisition is complete.

[0103] Such waiting times tend to be set to be longer than necessary to allow for a margin of safety, as the degree of vibration of the C-arm 23a may vary each time. This, in turn, means that the overall acquisition time for both the mask image and the contrast image becomes longer. Therefore, in the X-ray diagnostic apparatus 1 according to this embodiment, the vibration of the C-arm 23a is detected by the displacement detector 24 to determine whether the vibration of the C-arm 23a is at a magnitude that allows for the start of contrast image acquisition. This eliminates the need to pre-set a longer waiting time before starting contrast image acquisition, thereby shortening the overall acquisition time.

[0104] Another approach is to start acquiring contrast images at a timing that cancels out the vibration of the C-arm 23a. That is, it is known that when the C-arm 23a is vibrating, there are timings at which the vibrations of the C-arm 23a resonate and timings at which they cancel each other out. For this reason, in the X-ray diagnostic apparatus 1 according to this embodiment, the vibration of the C-arm 23a can be detected using the displacement detector 24, and contrast image acquisition can be started at a timing that cancels out the vibration of the C-arm 23a.

[0105] In terms of specific processing, as shown in Figure 16, the X-ray diagnostic device 1 detects vibration of the C-arm 23a (step S30). In this embodiment, the X-ray image acquisition function 252 and the received data generation function 253 in the processing circuit 25 of the X-ray diagnostic device 1 detect vibration of the C-arm 23a using the received radio waves. That is, the received data generation function 253 generates received data based on the radio waves reflected at the reference point, and the X-ray image acquisition function 252 analyzes this received data to detect vibration of the C-arm 23a. Various methods can be considered for detecting vibration of the C-arm 23a, as described above.

[0106] Next, the X-ray diagnostic device 1 determines whether it is time to start acquiring contrast images (step S32). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 determines whether it is time to start acquiring contrast images based on the vibration of the C-arm 23a detected in step S30. As described above, various timings are possible for starting to acquire contrast images.

[0107] If it is not time to start acquiring a contrast image (step S32: NO), the X-ray diagnostic device 1 returns to step S30 and continues to detect vibrations of the C-arm 23a. On the other hand, if it is time to start acquiring a contrast image (step S32: YES), the X-ray diagnostic device 1 starts acquiring a contrast image (step S34). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 starts acquiring a contrast image. This completes the imaging start control process according to this embodiment.

[0108] As described above, the X-ray diagnostic apparatus 1 according to this embodiment is configured such that the timing of starting continuous X-ray imaging of contrast images after completing continuous X-ray imaging of mask images is set to a timing that eliminates or minimizes the effect of vibration of the C-arm 23a, thereby suppressing motion artifacts caused by vibration of the C-arm 23a. In other words, it becomes possible to generate display images with reduced artifacts caused by vibration of the C-arm 23a.

[0109] In addition, the second embodiment was described based on the premise of an X-ray diagnostic apparatus 1 equipped with a function to reduce motion artifacts caused by the body movement of the subject P in the first embodiment, but it is not necessarily required to have a function to reduce motion artifacts. That is, an embodiment can be realized in which the displacement detector 24 is used to detect vibrations of the C-arm 23a without being used to detect the body movement of the subject P.

[0110] [Third Embodiment] The X-ray diagnostic apparatus 1 according to the third embodiment, in addition to the first embodiment described above, or in addition to the second embodiment described above, detects positional displacement caused by the sagging of the C-arm 23a itself due to the angle adjustment operation of the C-arm 23a using a displacement detector 24, and corrects the display image. In the following, an embodiment in which a function to correct positional displacement caused by the sagging of the C-arm 23a itself is added to the X-ray diagnostic apparatus 1 according to the second embodiment described above, will be explained, but it is also possible to add the same function to the X-ray diagnostic apparatus 1 according to the first embodiment described above.

[0111] Figure 17 is a flowchart illustrating the content of the X-ray imaging process performed by the X-ray diagnostic apparatus 1 according to this embodiment. The X-ray imaging process shown in Figure 17 is realized by the processing circuit 25 reading and executing the X-ray imaging program stored in the memory circuit 27. Furthermore, this X-ray imaging process is performed in the process of collecting a mask image (step S10) and the process of collecting a contrast image (step S12) in the medical image generation process shown in Figure 13. In other words, the X-ray imaging process in Figure 17 is a process that can be applied to all types of continuous X-ray imaging, which involves continuously taking multiple X-ray images while rotating the C-arm 23a.

[0112] As shown in Figure 17, first, the X-ray diagnostic device 1 rotates the C-arm 23a to the X-ray imaging position (step S40). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 rotates the C-arm 23a to move the X-ray tube 13 and the X-ray detector 21 to the position where X-ray imaging should be performed.

[0113] Next, as shown in Figure 17, the X-ray diagnostic device 1 performs X-ray imaging at this X-ray imaging position (step S42). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 irradiates X-rays from the X-ray tube 13 and detects the X-rays that have passed through the subject P with the X-ray detector 21, thereby performing X-ray imaging.

[0114] Next, as shown in Figure 17, the X-ray diagnostic device 1 measures the amount of displacement due to the sagging of the C-arm 23a using the displacement detector 24 (step S44). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 measures the amount of displacement using the data received from the displacement detector 24. As described in the second embodiment, this displacement detection is performed by measuring the amount of displacement using the marker 60 or the edge of the top plate 5a as a reference point.

[0115] During X-ray imaging, the position and angle of the C-arm 23a vary depending on the area of ​​the subject P to be imaged. The C-arm 23a is equipped with an imaging unit 40 that includes an X-ray detector 21, and the weight of this imaging unit 40 and the weight of the C-arm 23a itself cause sagging in the C-arm 23a. This sagging of the C-arm 23a is a form of deflection, a deviation from the design position. The amount of deviation from the design position due to this sagging changes depending on the angle of the C-arm 23a. Therefore, in this embodiment, a deviation detector 24 is used to measure the amount of deviation due to the sagging of the C-arm 23a.

[0116] Specifically, the distance and angle from the displacement detector 24 to a reference point are predetermined as design values, depending on the angle of the C-arm 23a. The X-ray diagnostic device 1 measures how much the measured distance and angle differ from these predetermined design values ​​based on the received data generated by the received data generation function 253. In other words, the difference between the predetermined design values ​​and the measured values ​​based on the received data is calculated as the displacement amount, which is a vector quantity. To put it another way, this displacement amount represents how much the actual position of the X-ray detector 21 is deviated from the design position of the X-ray detector 21 located nearby the displacement detector 24. Here, the design position mentioned above is not necessarily limited to the design position, but may be a value according to any setting used as a reference, or it may be an arbitrary angle value at the X-ray image acquisition position.

[0117] In this embodiment, the X-ray diagnostic device 1 measures the amount of displacement of the C-arm 23a relative to its design value based on the data received by the displacement detector 24, in synchronization with X-ray imaging. Specifically, received data is generated based on radio waves received by the receiver 24b of the displacement detector 24 provided in the image receiving unit 40, and the X-ray diagnostic device 1 measures the amount of displacement based on this received data.

[0118] In this X-ray imaging process, the X-ray imaging in step S42 and the measurement of the displacement amount in step S44 may be performed simultaneously, or one of them may be performed slightly before the other. In this embodiment, this state is described as measuring the displacement amount of the C-arm 23a relative to the design value or reference value based on the data received by the displacement amount detector 24, in synchronization with the acquisition of the X-ray image.

[0119] Next, as shown in Figure 17, the X-ray diagnostic device 1 determines whether the current X-ray image acquisition position is the last X-ray image acquisition position (step S46). In this embodiment, the X-ray image acquisition function 252 in the processing circuit 25 of the X-ray diagnostic device 1 determines whether the current X-ray image acquisition position is the last X-ray image acquisition position. Here, the last X-ray image acquisition position means the final position in which the C-arm 23a is rotated to acquire continuous X-ray images.

[0120] If the X-ray diagnostic device 1 determines that the current X-ray image acquisition position is not the last X-ray image acquisition position (step S46: NO), it returns to step S40 in order to continue the operation of performing X-ray imaging while rotating the C-arm 23a. That is, it rotates the C-arm 23a to the next X-ray imaging position and performs the acquisition of the next X-ray image.

[0121] On the other hand, if the X-ray diagnostic device 1 determines that the current X-ray image acquisition position is the last X-ray image acquisition position (step S46: YES), it terminates the X-ray imaging process. For example, if this X-ray imaging process is the mask image acquisition process (step S10) in the medical image generation process shown in Figure 13, the mask image acquisition process is terminated. Also, for example, if this X-ray imaging process is the contrast image acquisition process (step S12) in the medical image generation process shown in Figure 13, the contrast image acquisition process is terminated.

[0122] The X-ray images and displacement amounts collected in this X-ray imaging process are used in the correction process in step S14 of the medical image generation process shown in Figure 13. That is, in step S14, the position of the collected X-ray images is corrected based on the measured displacement amount. In other words, for each of the acquired X-ray images, the displacement amount due to the sagging of the C-arm 23a is corrected to reduce its impact on the X-ray images. As a result, in step S18, a display image suitable for diagnostic imaging can be generated.

[0123] Note that the mask image acquisition process and the contrast image acquisition process are merely examples of X-ray image acquisition processes performed by the X-ray imaging process shown in Figure 17, and the X-ray imaging process shown in Figure 17 can also be applied to processes for acquiring other types of X-ray images.

[0124] As described above, according to the X-ray diagnostic apparatus 1 of this embodiment, the positional displacement due to the sagging of the C-arm 23a is measured based on the data received by the displacement detector 24. That is, the amount of displacement of the C-arm 23a relative to the design value or reference value due to the angle adjustment operation of the C-arm 23a is collected in synchronization with X-ray imaging. Then, by correcting the position of the X-ray image acquired in synchronization based on this displacement amount, it is possible to suppress the deterioration of the image quality of the X-ray image due to positional displacement and generate a suitable display image.

[0125] Generally, positional displacement due to the sagging of the C-arm 23a itself during angle adjustment is unavoidable. To compensate for this displacement of the X-ray detector 21, it is necessary to periodically register the amount of displacement of the C-arm 23a at each angle adjustment as calibration data in advance. This calibration data registration needs to be done, for example, every three months, and the position of the acquired X-ray image is corrected based on this registered calibration data. However, periodic updates of calibration data are a burden in managing the X-ray diagnostic device 1. According to the X-ray diagnostic device 1 of this embodiment, it is not necessary to perform such periodic updates of calibration data, and the management burden of the X-ray diagnostic device 1 can be reduced.

[0126] Although the third embodiment was described based on the assumption that the X-ray diagnostic apparatus 1 has a function to reduce motion artifacts caused by the movement of the subject P in the first embodiment, it is not necessarily required to have a function to reduce motion artifacts. In other words, an embodiment can be realized in which the displacement detector 24 is used to measure the amount of displacement from the design value or reference value due to the sagging of the C-arm 23a, without using it to detect the movement of the subject P. In other words, this embodiment can be applied to any X-ray imaging method that needs to suppress the effects of sagging in the acquired X-ray image.

[0127] In the first to third embodiments described above, the holding device 23 is configured with a C-arm 23a, but the shape of the arm of the holding device 23 is not limited to C-shape and may be other shapes. For example, the shape of the arm of the holding device 23 may be Ω-shaped. In other words, the first embodiment can be applied to any X-ray diagnostic device 1 that needs to detect the movement of the subject P, the second embodiment can be applied to any X-ray diagnostic device 1 that needs to detect the vibration of the holding device 23, and the third embodiment can be applied to any X-ray diagnostic device 1 that needs to detect the amount of positional deviation of the holding device 23 from the design value or reference value.

[0128] According to at least one embodiment described above, received data can be generated based on the radio waves received by the receiver 24b, and the position of the collected X-ray image can be corrected based on this received data.

[0129] In the above description, the term "processor" refers to circuits such as CPUs (Central Processing Units), GPUs (Graphics Processing Units), Application Specific Integrated Circuits (ASICs), and programmable logic devices (e.g., Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and Field Programmable Gate Arrays (FPGAs)). When the processor is a CPU, for example, it performs its functions by reading and executing programs stored in memory circuits. On the other hand, when the processor is an ASIC, for example, the program is directly incorporated into the processor's circuitry instead of being stored in memory circuits. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor and perform its functions. Furthermore, the multiple components shown in Figure 1 may be integrated into a single processor to perform its functions.

[0130] 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]

[0131] 1. X-ray diagnostic equipment 3. Imaging device 5 Bed equipment 5a Top plate 5b table 5c bed mattress 7 Drive Unit 9 Control section 11 X-ray high-voltage equipment 13 X-ray tube 19 X-ray tube holder 21 X-ray detector 23 Holding device 23a C-arm 24. Shift Amount Detector 24a Transmitter 24b Receiver 25 Processing Circuit 27 Memory circuit 29 Display section 31 Input Interfaces 40 Image receiving section 50 Connection part 52 Fixed Arm 60 Markers 71 Image receiving unit movement unit 73 Arm movement section 75 Tabletop moving part 77 X-ray tube holding part moving part 251 Basic Control Functions 252 X-ray image acquisition function 253 Received data generation function 254 Correction function 255 Display image generation function 256 Display function

Claims

1. An X-ray tube that generates X-rays, An X-ray detector that detects X-rays that have passed through the subject, An X-ray image acquisition means collects an X-ray image based on the X-rays detected by the aforementioned X-ray detector, A means of transmitting radio waves, Receiving means for receiving the aforementioned radio waves, A receiving data generation means that generates received data based on the radio waves received by the receiving means, A correction means for correcting the position of the collected X-ray image based on the received data generated by the received data generation means, An X-ray diagnostic device equipped with [specific features / features].

2. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray image acquisition means acquires an X-ray image in synchronization with the reception of the radio waves by the receiving means.

3. The X-ray diagnostic apparatus according to claim 2, wherein the received data generation means holds the X-ray image collected by the X-ray image acquisition means and the received data generated by the received data generation means in correspondence with the imaging angle of the X-ray image.

4. The X-ray diagnostic apparatus according to claim 3, wherein the correction means determines whether or not the subject is moving based on the received data, and corrects the position of the X-ray image if it is determined that there is movement.

5. The X-ray image acquisition means collects a mask image, which is a plurality of image data collected in chronological order with respect to the subject before the administration of the contrast agent, and a contrast image, which is a plurality of image data collected in chronological order with respect to the subject after the administration of the contrast agent. The X-ray diagnostic apparatus according to claim 4, wherein the correction means determines that there is body movement when the difference value calculated based on two received data corresponding to a mask image and a contrast image corresponding to a first imaging angle is greater than a first threshold.

6. The X-ray diagnostic apparatus according to claim 5, wherein the correction means, when it is determined that there is body movement, performs pixel shift processing on the X-ray image according to the amount of displacement of the subject.

7. An X-ray diagnostic apparatus according to claim 6, comprising a display image generation means for generating a display image based on collected X-ray images, the display image generation means for generating the display image using an X-ray image that has undergone pixel shift processing by the correction means.

8. The X-ray diagnostic apparatus according to claim 3, wherein the correction means determines whether or not the subject is moving based on the received data, and if it is determined that there is movement, corrects the position of the X-ray images excluding the X-ray image among a plurality of X-ray images.

9. The X-ray image acquisition means collects a mask image, which is a plurality of image data collected in chronological order with respect to the subject before the administration of the contrast agent, and a contrast image, which is a plurality of image data collected in chronological order with respect to the subject after the administration of the contrast agent. The X-ray diagnostic apparatus according to claim 8, wherein the correction means determines that there is body movement when the difference value calculated based on two received data corresponding to a mask image and a contrast image corresponding to a first imaging angle is greater than a second threshold.

10. An X-ray diagnostic apparatus according to claim 7, comprising a display image generation means for generating a display image based on collected X-ray images, and further comprising a display image generation means for generating the display image without using the X-ray images thinned by the correction means.

11. The received data generation means generates the received data based on radio waves reflected at a fixed reference point relative to the transmitting means and the receiving means. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray image acquisition means determines, based on the received data, the timing to start continuous X-ray imaging, which involves continuously imaging X-rays while rotating a holding device that holds the X-ray tube.

12. The X-ray diagnostic apparatus according to claim 11, wherein the X-ray image acquisition means detects vibration of the holding device based on the received data and determines the timing to start continuous X-ray imaging at a timing that eliminates or minimizes the effect of vibration of the holding device.

13. The X-ray image acquisition means, in synchronization with the acquisition of the X-ray image, measures the amount of deviation from the design value of the holding device that holds the X-ray detector based on the received data, The correction means corrects the position of the collected X-ray image based on the measured amount of displacement. The X-ray diagnostic apparatus according to claim 1.

14. The X-ray diagnostic apparatus according to claim 1, wherein the X-ray image acquisition means continuously acquires the X-ray image while rotating a holding device that holds the X-ray tube.

15. The X-ray diagnostic apparatus according to any one of claims 1 to 14, wherein the radio waves are millimeter-wave radar or laser.

16. The X-ray diagnostic apparatus according to any one of claims 1 to 14, wherein the transmitting means and the receiving means are provided together with the X-ray detector in the image receiving unit.

17. An X-ray tube that generates X-rays, An X-ray detector that detects X-rays that have passed through the subject, An X-ray image acquisition means collects an X-ray image based on the X-rays detected by the aforementioned X-ray detector, A means of transmitting radio waves, Receiving means for receiving the aforementioned radio waves, A medical image processing method for processing X-ray images collected by an X-ray diagnostic device equipped with the following, The X-ray diagnostic apparatus includes the step of generating received data based on the radio waves received by the receiving means, The X-ray diagnostic apparatus performs the step of correcting the position of the collected X-ray image based on the received data, A medical image processing method comprising the following.

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