X-ray diagnostic equipment

Abstract

The system is designed to provide a simple configuration that allows for the acquisition of information indicating the relative positional relationship between the X-ray tube and the X-ray detector, which is necessary for X-ray diagnostic equipment. [Solution] An X-ray diagnostic apparatus according to one embodiment comprises an X-ray tube, an X-ray diaphragm device, an X-ray detector, and a calculation unit. The X-ray diaphragm device houses an X-ray diaphragm that defines the irradiation field of the X-rays irradiated from the X-ray tube and is equipped with a feature object. The X-ray detector detects the X-rays irradiated from the X-ray tube and transmitted through the subject. The calculation unit calculates information indicating the relative positional relationship between the X-ray tube and the X-ray detector based on the image of the feature object depicted in the X-ray image based on the transmission data acquired by the X-ray detector.

Description

Technical Field

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

Background Art

[0002] There are various types of X-ray diagnostic apparatuses, such as general X-ray imaging apparatuses, X-ray apparatuses for consultation, and X-ray TV apparatuses. Among these, general X-ray imaging apparatuses and X-ray apparatuses for consultation have a relatively simple configuration and are, for example, apparatuses for performing X-ray imaging of the chest and the like. In addition to being able to acquire X-ray imaging images as still images, an X-ray TV apparatus is configured to be able to acquire X-ray images as moving images so that intravascular treatment using a medical device such as a catheter, that is, IVR (Interventional Radiology), can be performed.

[0003] In X-ray diagnosis using these X-ray diagnostic apparatuses, exposure management is important. One of the exposure management methods is a method called the NDD method (Numerical Dose Determination). The NDD method is a method for calculating the patient surface exposure dose from the imaging parameters during an X-ray examination. And one of the imaging parameters used in the NDD method is SID (Source-to-Image Distance). SID is the distance from the focal point of the X-ray source to the X-ray detector. SID is required to calculate the patient surface exposure dose based on the NDD method.

[0004] As a method for obtaining SID, there is a method of measuring the distance from the focal point of the X-ray source to the X-ray detector using an external sensor such as an encoder. However, when applying this method to, for example, a ceiling-suspended X-ray imaging apparatus used in general X-ray imaging, it is necessary to provide a sensor such as an encoder and a belt on the ceiling rail to detect the position of the X-ray source, but a considerable cost is required to implement these mechanisms.

[0005] Furthermore, with mobile X-ray equipment and general X-ray imaging equipment, it is possible to manually measure the distance from the X-ray source's focal point to the X-ray detector using a measuring tape or similar tool. However, in a clinical setting, manually measuring the SID value using a measuring tape and then inputting the measured SID value into the equipment is a time-consuming process.

[0006] On the other hand, another method for obtaining the SID is to refer to the SID value pre-entered as part of the imaging protocol. However, this method cannot obtain the SID value under the actual positioning conditions. Therefore, the calculated dose value may not be accurate depending on the positioning conditions.

[0007] In addition, for example, in X-ray imaging performed in a standing position or using a mobile X-ray machine, X-rays may not enter the X-ray detector from the front, but rather at an oblique angle. In such cases, it would be extremely useful to be able to easily measure information regarding the oblique angle. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-044134 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is to enable the acquisition of information indicating the relative positional relationship between the X-ray tube and the X-ray detector, which is necessary in an X-ray diagnostic apparatus, with a simple configuration. 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 each embodiment described later can also be positioned as other problems. [Means for solving the problem]

[0010] An X-ray diagnostic apparatus according to one embodiment comprises an X-ray tube, an X-ray diaphragm, an X-ray detector, and a calculation unit. The X-ray diaphragm houses an X-ray diaphragm that defines the irradiation field of the X-rays irradiated from the X-ray tube and is equipped with a feature object. The X-ray detector detects the X-rays irradiated from the X-ray tube and transmitted through the subject. The calculation unit calculates information indicating the relative positional relationship between the X-ray tube and the X-ray detector based on the image of the feature object depicted in the X-ray image based on the transmission data acquired by the X-ray detector. [Brief explanation of the drawing]

[0011] [Figure 1] An external view showing an example of the configuration of the X-ray diagnostic apparatus 1 according to the first embodiment. [Figure 2] This figure schematically shows the configuration of the X-ray tube device, X-ray diaphragm device, and X-ray detector, which are part of the configuration of the X-ray diagnostic apparatus of the first embodiment. [Figure 3] A block diagram showing an example of the functional configuration of the X-ray diagnostic apparatus 1 of the first embodiment. [Figure 4] A diagram illustrating the first method for calculating SID using the X-ray diagnostic device 1 according to the first embodiment. [Figure 5] A diagram illustrating the second method for calculating SID using the X-ray diagnostic device 1 according to the first embodiment. [Figure 6] (a) and (b) are diagrams showing the first modified form of the feature, and (c) and (d) are diagrams showing the second modified form of the feature. [Figure 7] (a) and (b) are diagrams showing a third modification of the feature, and (c) and (d) are diagrams showing a fourth modification of the feature. [Figure 8] A diagram showing the fifth variation of the characteristic. [Figure 9] This diagram illustrates the concept of removing features detected by an X-ray detector through image processing. [Figure 10] A block diagram showing the functional configuration of the second embodiment. [Figure 11] A diagram illustrating the concept of the angle of inclination calculation process in the first example of the second embodiment. [Figure 12]A diagram illustrating the concept of the angle of inclination calculation process in the second example of the second embodiment. [Figure 13] A diagram illustrating the hiding process as an alternative to image processing. [Modes for carrying out the invention]

[0012] The following describes in detail an embodiment of the X-ray diagnostic apparatus with reference to the drawings.

[0013] (First embodiment) Figure 1 is an external view showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. The X-ray diagnostic apparatus 1 illustrated in Figure 1 is an example of a general X-ray imaging apparatus that performs simple X-ray imaging of the chest, etc., but the X-ray diagnostic apparatus 1 is not limited to this and may include any apparatus that can change the relative positional relationship between the X-ray detector and the X-ray focal position, for example, a mobile X-ray apparatus that can be moved between patient rooms, or an X-ray TV apparatus. The X-ray diagnostic apparatus 1 includes, for example, an imaging apparatus 10, a supine imaging table 130, and a standing imaging table 140.

[0014] The imaging apparatus 10 includes an X-ray tube apparatus 100, an X-ray diaphragm apparatus 110, and an X-ray detector 120. Of these, the X-ray tube apparatus 100 and the X-ray diaphragm apparatus 110 are held by an X-ray tube holder 152. There are two types of X-ray tube holders 152, for example, a ceiling-type X-ray tube holder and a floor-type X-ray tube holder, but Figure 1 shows an example of the appearance of a ceiling-type X-ray tube holder 152. The ceiling-type X-ray tube holder 152 includes a ceiling rail 151, a trolley section 153, and an orthogonal movement section 154. By moving the trolley section 153 along the ceiling rail 151, the X-ray tube apparatus 100 and the X-ray diaphragm apparatus 110 can be moved in parallel, and by moving the orthogonal movement section 154 relative to the trolley section 153 in a direction perpendicular to the extension direction of the ceiling rail 151, the X-ray tube apparatus 100 and the X-ray diaphragm apparatus 110 can be moved in parallel. Furthermore, a user interface 230 (operating unit 230) is provided close to the X-ray tube device 100 and the X-ray diaphragm device 110, which allows for manual operation of the angle and position of the X-ray tube device 100 and the X-ray diaphragm device 110, as well as manual control of X-ray irradiation.

[0015] The lying-position imaging table 130 is configured as a bed on which a patient can lie horizontally in a lying position on the top plate 131 for imaging. Below the top plate 131 of the lying-position imaging table 130, an X-ray detector 120 which is a component of the imaging device 10 is disposed. On the other hand, the standing-position imaging table 140 is a device for imaging the subject P in a standing position. The standing-position imaging table 140 holds the X-ray detector 120 so as to be movable in the vertical direction by a support stand 141.

[0016] The X-ray detector 120 is configured to include, for example, an FPD (Flat Panel Detector). The X-rays irradiated from the X-ray tube 101 (see FIG. 2) housed in the X-ray tube device 100 pass through the subject P (for example, the patient P) on the top plate 131 and are detected by the X-ray detector 120.

[0017] FIG. 2 is a diagram schematically showing the configurations of the X-ray tube device 100, the X-ray aperture device 110, and the X-ray detector 120 among the configurations of the X-ray diagnostic apparatus 1 according to the embodiment. [[ID=​​​​​​​​​​By independently moving the four aperture blades 112A, 112B, 112C, and 112D in the four directions indicated by the black arrows in Figure 2(b), the size and position of the aperture 116 through which the X-rays emitted from the X-ray tube 101 pass can be controlled. This control of the X-ray aperture 111 allows for the control of the position and size of the X-ray field relative to the subject P.

[0021] A cover member 114 capable of transmitting X-rays and visible light is provided on the outer circumferential surface of the case of the X-ray diaphragm 110, on the surface in the direction in which the X-rays are emitted toward the subject P. The cover member 11 is formed of a resin material such as an acrylic plate, for example.

[0022] In the X-ray diagnostic apparatus 1 of this embodiment, a "feature 115," which is an example of a feature detectable by the X-ray detector 120, is provided on the X-ray diaphragm 110. Similar to the diaphragm 112, feature 115 is made of a material that shields X-rays, such as lead, iron, and tungsten. The size of feature 115 is determined according to the SID, and the relative size of the feature 15 shown in Figure 2 and subsequent figures with respect to the diaphragm blades 112 is for convenience only. The size of feature 115 includes the vertical and horizontal lengths of feature 115 as viewed from the X-ray tube 101 (or X-ray detector 120) side. Feature 115 can be provided at any position between the X-ray tube 101 and the X-ray detector 120, but specifically, it can be provided on the X-ray diaphragm 111 or the cover member 114 of the X-ray diaphragm 110.

[0023] In the first example of feature 115 shown in Figure 2, two characteristic-shaped appendages (for example, two convex protrusions) are provided on one of the four aperture blades 112 (for example, aperture blade 112A). This feature 115 protrudes into a portion of the aperture opening 116. As a result, as shown in Figure 2(c), the shape of feature 115 is detected in a portion of the periphery of the irradiation field of the X-ray detector 120.

[0024] "Feature 115" may be an appendage with a distinctive shape attached to a part of the X-ray aperture 111 or the cover member 114, or it may be a notch created by cutting out a part of the X-ray aperture 111 in an arbitrary distinctive shape (for example, a concave shape). In the former case, the appendage is provided such that a part of the side surface of the aperture blade 112 extends toward the opposing aperture blade 112. In the latter case, the notch is provided such that a part of the side surface of the aperture blade 112 is recessed toward the opposing side surface.

[0025] Furthermore, "feature 115" may be a through-hole of any distinctive shape formed in a part of the X-ray aperture 111. For example, "feature 115" may be a through-hole of a distinctive shape such as a circle, square, or triangle, or a distinctive shape that imitates a symbol, number, letter, etc., formed in a part of the X-ray aperture 111.

[0026] Furthermore, "feature 115" may be any distinctive shape pattern provided on the cover member 114, such as an acrylic plate. For example, "feature 115" may be a grid pattern, or a pattern of distinctive shapes such as circles, squares, triangles, symbols, numbers, or letters provided on the cover member 114.

[0027] Figure 3 is a block diagram showing an example of the functional configuration of the X-ray diagnostic apparatus 1 according to the first embodiment. The X-ray diagnostic apparatus 1 comprises an imaging device 10 and a control device 20. As mentioned above, the imaging device 10 comprises an X-ray tube device 100, an X-ray diaphragm device 110, and an X-ray detector 120. On the other hand, the control device 20 comprises an X-ray high-voltage circuit 200, a processing circuit 210, a memory circuit 220, a user interface 230, and a display 240.

[0028] The X-ray high-voltage circuit 200 applies high voltage and tube current to the X-ray tube under the control of the X-ray control function F02 of the processing circuit 210.

[0029] The memory circuit 220 stores the processor program of the processing circuit 210, as well as X-ray images and various other data generated by the processing circuit 210.

[0030] The user interface 230 includes an input device that can be operated by the user and an input circuit that receives signals from the input device. The input device can be implemented as, for example, a control console, a joystick, a trackball mouse, a keyboard, a touch panel that allows input operations by touching the operating surface, a touchscreen that integrates a display screen and a touchpad, a non-contact input circuit using an optical sensor, or an audio input circuit.

[0031] The display 240 is composed of a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display. The display 240 displays various data in addition to the X-ray image generated by the processing circuit 210. Note that all or part of the X-ray image and data displayed on the display 240 may also be displayed on the touch panel or touchscreen of the user interface 230.

[0032] The processing circuit 210 has one or more processors. It realizes the following functions through software processing by executing programs stored in the memory circuit 220. Alternatively, the processing circuit 210 may be configured to realize each function through hardware processing performed by an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), or it may realize each function through a combination of software and hardware processing.

[0033] As shown in Figure 3, the processing circuit 210 implements the following functions: aperture control function F01, X-ray control function F02, image generation function F03, calculation function F04, and image processing function F05. Of these, the calculation function F04 has an SID calculation function F05 and a radiation dose calculation function F06 as its internal configuration.

[0034] The aperture control function F01 controls the size and position of the aperture opening 116 adjusted by the X-ray aperture 111 according to control data input from the user via the user interface 230. The X-ray control function F02 also outputs control signals to the X-ray high-voltage circuit 200 in order to control the tube voltage and tube current of the X-ray tube according to control data input from the user via the user interface 230 or control data specified in a pre-set protocol.

[0035] The image generation device F03 generates an X-ray image based on the transmission data output from the X-ray detector 120. As described above, the X-ray diagnostic device 1 of the first embodiment is configured to have a feature 115 on the X-ray diaphragm 110. This feature 115 is detected by the X-ray detector 120, and the detected feature 115 is depicted in the X-ray image generated by the image generation function F03. The calculation function F04 calculates information indicating the relative positional relationship between the X-ray tube 101 and the X-ray detector 120 based on the image of the feature 115 depicted in the X-ray image based on the transmission data acquired by the X-ray detector 120.

[0036] The SID calculation function F05 of the calculation function F04 uses at least the dimensions of the feature 115 detected by the X-ray detector 120, that is, based on the dimensions of the feature 115 depicted in the X-ray image (hereinafter referred to as the detected dimensions), to calculate information indicating the relative positional relationship between the X-ray tube 101 and the X-ray detector 120 as an X-ray imaging-related index. An example of an X-ray imaging-related index is the SID. The specific method for calculating the SID will be described later.

[0037] The radiation dose calculation function F06 of the calculation function F04 calculates the radiation dose, such as the patient surface exposure dose, using the NDD method, based on the SID calculated by the SID calculation function F05, as well as information such as tube current and tube voltage input from the X-ray control function F02, etc.

[0038] The image processing function F07 performs various image processing on the X-ray images generated by the image generation device F03, and also performs removal processing to make features 115 that are unnecessary for interpreting X-ray images for diagnosis less prominent.

[0039] Figure 4 is a diagram illustrating the first method for calculating the SID using the X-ray diagnostic apparatus 1 according to the first embodiment. Figure 5 is a diagram illustrating the second method for calculating the SID. As mentioned above, the type of feature 115 used in calculating the SID is not particularly limited, but in Figures 4 and 5, as shown in Figures 4(a) and 5(a), an example is used in which two convex-shaped protrusions provided on one aperture blade 112A are used as feature 115.

[0040] In the first method for calculating the SID, calibration imaging is performed separately from normal diagnostic imaging, as shown in Figures 4(b) and 4(c). The calibration imaging obtains the detected dimensions of the feature 115 detected by the X-ray detector 120. For example, the distance D1 between the opposite sides of two convex protrusions is obtained as the reference dimension (hereinafter referred to as the reference detected dimension) D1 of the feature 115 in the calibration imaging. The SID in the calibration imaging is also measured using an appropriate measuring means, such as a measuring tape. Then, for example, the measured SID is set as the reference SID in the processing circuit 210 via the user interface 230.

[0041] On the other hand, in a normal diagnostic imaging, the SID at the time of diagnosis is unknown, and the detection dimension D2 of the feature 115 detected by the X-ray detector 120 (i.e., the distance D2 between the opposing sides of the two convex protrusions provided on the aperture blade 112A) is acquired, similar to calibration imaging.

[0042] Then, the SID calculation function F05 of the processing circuit 210 calculates the unknown diagnostic SID using the ratio of the reference detection dimension D1 of the feature 115 to the detection dimension D2 of the feature detected by the X-ray detector 120 in a diagnostic imaging with the SID unknown (i.e., (D2 / D1)), and the reference SID, which is a known SID. Specifically, the diagnostic SID is calculated based on the following (Equation 1).

[0043] Diagnosis SID=Reference SID*(D2 / D1) (Formula 1) Figures 5(a) to 5(c) illustrate a second method for calculating the SID. In this second method, the SID is calculated using only normal diagnostic imaging, without calibration imaging. However, in this second method, as shown in Figure 5(a), the actual dimensions D4 of feature 115 and, as shown in Figure 5(c), the distance L1 from the X-ray focal point to feature 115 are used to calculate the diagnostic SID. Here, the actual dimensions D4 of feature 115 are, for example, the distance D4 between the opposite sides of the two convex protrusions provided on the aperture blade 112A, similar to Figure 4(a). The distance L1 is the distance L1 from the X-ray focal point to the two convex protrusions provided on the aperture blade 112A in the direction perpendicular to the X-ray detector 120 from the X-ray focal point.

[0044] During diagnostic imaging, with the diagnostic SID unknown, the detection dimension D3 of the feature 115 detected by the X-ray detector 120 (i.e., the distance D3 between the opposing sides of the two convex protrusions provided on the aperture blade 112A) is acquired, as shown in Figure 5(b).

[0045] Then, the SID calculation function F05 of the processing circuit 210 calculates the unknown diagnostic SID using the ratio (i.e., (D3 / D4)) between the actual dimensions D4 of feature 115 and the detected dimensions (i.e., D3) of feature 115 detected by the X-ray detector 120 during diagnostic imaging when the SID is unknown, and the distance L1 from the X-ray focal point to feature 115. Specifically, the diagnostic SID is calculated based on the following (Equation 2).

[0046] SID at diagnosis = (L1) * (D3 / D4) (Equation 2) Next, with reference to Figures 6 to 8, several modified examples of the feature 115 provided in the X-ray diaphragm 110 and the feature 115 detected by the X-ray detector 120 are shown.

[0047] Figures 6(a) and 6(b) show a first modified example of feature 115. While feature 115 of the first embodiment described above is a convex projection (protrusion) provided on the side surface of the aperture blade 112A, feature 115 of the first modified example is a concave notch (recess) provided on the side surface of the aperture blade 112A. With this first modified example as well, the diagnostic SID can be calculated by applying the detected dimension Db between the two notches 115 detected by the X-ray detector 120, or the actual dimension Da between the two notches 115, to (Equation 1) or (Equation 2).

[0048] Figures 6(c) and 6(d) show a second modified example of feature 115. In the first embodiment described above, feature 115 is a plurality of (specifically, two) convex-shaped protrusions provided on the aperture blade 112A, and the diagnostic SID is calculated by applying the distances D1, D2 and D3, D4 between the plurality of (specifically, two) features 115 to (Equation 1) or (Equation 2). In contrast, in the second modified example, feature 115 is a single characteristic shape provided on the aperture blade 112A, and the length of a predetermined part of this feature 115 is used as the actual dimension of feature 115, or the detected dimension detected by the X-ray detector 120. For example, as shown in Figure 6(c), the length of one side of a single protrusion provided on the aperture blade 112A is used as the actual dimension Da of feature 115, and the length of the corresponding side detected by the X-ray detector 120 is used as the detected dimension Db. Then, by applying these actual dimensions Da and detected dimensions Db to (Equation 1) or (Equation 2), the diagnostic SID can be calculated.

[0049] Figures 7(a) and 7(b) show a third modified example of feature 115. In the third modified example, a through-hole of an arbitrary characteristic shape is provided in a predetermined aperture blade 112 (for example, one aperture blade 112A) that constitutes all or part of the X-ray aperture 111. In other words, feature 115 according to the third modified example is the portion of the predetermined aperture blade 112 that constitutes the X-ray aperture 111 that is provided with a through-hole for passing X-rays. Figures 7(a) and 7(b) illustrate a circular through-hole, but other shapes such as a square or triangle, or a through-hole with a characteristic shape that imitates a symbol, number, letter, etc., may also be used. With the through-holes in Figures 7(a) and 7(b), SID can be obtained with a simple configuration without processing the side surfaces of the aperture blades 112 that face the opposing aperture blades 112.

[0050] In Figures 7(a) and 7(b), the aperture blade 112A is configured to have one through-hole (i.e., feature 115), but it is also possible to have multiple (e.g., two) through-holes (i.e., feature 115) in the aperture blade 112A. In this case, the SID can be calculated based on the distance between the multiple (e.g., two) through-holes.

[0051] Figures 7(c) and 7(d) show a fourth modified example of feature 115. Feature 115 of the fourth modified example consists of a convex feature 115A provided on the first aperture blade 112A, which is one of the multiple aperture blades constituting the X-ray aperture 111, and a concave feature 115B provided on the side surface of the second aperture blade 112B, which faces the first aperture blade. The convex feature 115A and the concave feature 115B are formed to interlock with each other when the X-ray aperture 111 is closed. As shown in the through-holes in Figures 7(a) and 7(b), as the opening narrows, the convex tip of feature 115A is inserted into the concave part of aperture blade 112B. Therefore, since feature 115A does not abut against the side surface of the opposing aperture blade 112B, SID can be obtained with a simple configuration even when the opening is very small.

[0052] In the first embodiment, feature 115 is attached as a separate appendage to the upper side (X-ray tube side) of the aperture blade 112A, as shown in Figures 2(a) and 2(b). This is to prevent the aperture blades 112A and 112B from interfering with each other when the X-ray aperture 111 is closed. In contrast, in the fourth modification of feature 115, the shape of feature 115 is formed in the X-ray aperture 111 itself so that it does not interfere with each other even when the X-ray aperture 111 is closed, thus eliminating the need for an appendage.

[0053] In Figures 7(c) and 7(d), the aperture blade 112A is provided with one convex feature 115A, and the aperture blade 112B is provided with one concave feature 115B on its side surface. However, the aperture blade 112A may be provided with multiple (e.g., two) convex features 115A, and the aperture blade 112B may also be provided with multiple (e.g., two) concave features 115B on its side surface. In this case, the SID can be calculated based on the distance between the multiple features 115A (or between the multiple features 115B).

[0054] Figures 8(a) to 8(e) show a fifth modified example of feature 115. Feature 115 of the fifth modified example is a pattern provided on a cover member 114 (for example, an acrylic plate) which is part of the case 113 housing the X-ray aperture 111 and is provided on a transmission window that transmits X-rays toward the subject. The shape of the pattern provided on the cover member 114 is not particularly limited and can be any shape. For example, it may be a rectangular pattern as shown in Figures 8(b) and 8(c), or a grid-like pattern as shown in Figures 8(d) and 8(e). The SID can then be calculated based on the dimension Da of a part of the pattern provided on the cover member 114 and the detection dimension Db of the corresponding part detected by the X-ray detector 120.

[0055] The method for forming a pattern on the cover member is not particularly limited, but for example, a pattern can be formed by attaching a tungsten wire with a thickness of about 100 μm to the cover member 114.

[0056] When forming a grid-like pattern as shown in Figures 8(d) and 8(e), the pattern can be formed using four wires. In the captured image, the four wires are superimposed on the image of the subject. At this time, the wires provided on the cover member 114 are close to the focal point, so they are depicted as blurred wire images. Therefore, this image is first subjected to a Hough transform. In the image after the Hough transform, the images of the four wires are represented as points. On the other hand, the image after the Hough transform also contains image information other than the wires, so thresholding is used to replace low pixel values ​​with zero. Then, by performing an inverse Hough transform, an image in which only the wires are extracted can be created. Furthermore, by calculating the distance between the wires using thresholding, the SID can be calculated. When measuring the distance between the wires, the SID may be calculated using the bidirectional average value in either the horizontal or vertical direction.

[0057] Figures 9(a) to 9(d) illustrate the concept of a process to erase the region of the feature 115 detected by the X-ray detector 120 through image processing, in order to make the feature 115 less noticeable on the X-ray image. The feature 115 of the first embodiment described above, and the feature 115 of each modified example, are detected by the X-ray detector 120 and will therefore be depicted in the X-ray image as is. For this reason, depending on the size and position of the feature 115, it may interfere with image diagnosis. Therefore, in the X-ray diagnostic apparatus 1 of the first embodiment, the image processing function F07 of the processing circuit 210 erases the feature 115 detected by the X-ray detector 120 and depicted in the X-ray image through image processing, as shown in Figures 9(c) and 9(d).

[0058] Furthermore, the process of erasing the feature 115 depicted in the X-ray image by image processing can also be applied to a fifth modified example of feature 115, which involves forming a grid or other pattern on the cover member 114 using wires or the like.

[0059] <Second Embodiment> Figure 10 is a block diagram showing the functional configuration of the second embodiment. The second embodiment differs from the first embodiment in that the calculation function F04 implemented by the processing circuit 210 further includes an oblique angle calculation function F08, but the other configurations are the same as those of the first embodiment.

[0060] Figures 11(a) to 11(c) illustrate the concept of the oblique angle calculation process in the first example of the second embodiment. In normal X-ray imaging, the X-ray tube 101 and the X-ray detector 120 are positioned directly opposite each other during imaging. However, depending on the purpose of imaging, imaging may be performed with the X-rays incident on the X-ray detector 120 at an oblique angle, as shown in Figure 11(a). Furthermore, when using the mobile X-ray device 1 to image patients in hospital rooms or patients during surgery, it may be difficult to image with the X-ray tube 101 and the X-ray detector 120 directly opposite each other. In such imaging situations, it is useful to know the angle of incidence of the X-rays to the X-ray detector 120, i.e., the oblique angle.

[0061] In the first example of the second embodiment, a grid-like pattern using wires or the like is used as feature 115, similar to the fifth modification in the first embodiment. The oblique angle calculation function F08 of the processing circuit 210 calculates the oblique angle of X-rays relative to the X-ray detector 120 as an X-ray imaging-related index from the degree of distortion of the grid-like pattern detected by the X-ray detector 120. The oblique angle of X-rays is an example of an X-ray imaging-related index. The calculated oblique angle is output to, for example, the user interface 230 and provided to the user.

[0062] For example, as shown in Figure 11(a), when X-rays are taken from below to above the subject P, the features 115 of the mutually orthogonal grid pattern shown in Figure 11(b) are detected by the X-ray detector 120 as vertical wires tilted at an angle, as shown in Figure 11(c). By detecting this wire tilt angle from the X-ray image, the angle of oblique entry can be calculated.

[0063] Alternatively, the relationship between the wire's inclination angle and the X-ray's oblique entry angle can be obtained in advance through experiments or other means, and this relationship can be saved, for example, as a lookup table. Then, the oblique entry angle associated with the wire's inclination angle detected during diagnostic imaging can be obtained by referring to the lookup table.

[0064] Figures 12(a) to 12(c) illustrate the concept of the angle-in-angle calculation process in a second example of the second embodiment. The feature 115 used in this second example is a characteristic pattern that includes positional information of at least three spatially separated points.

[0065] The oblique angle calculation function F08 of the processing circuit 210 calculates the oblique angle of X-rays relative to the X-ray detector 120 as an X-ray imaging-related index, based on the difference in shape between a first characteristic pattern provided on the X-ray diaphragm 110 (a characteristic pattern including positional information of at least three spatially separated points as described above) and a second characteristic pattern detected by the X-ray detector 120. The calculated oblique angle is output to, for example, the user interface 230 and provided to the user.

[0066] (Hide / hide processing as an alternative to image processing) Figures 9(a) to 9(d) illustrate how the image processing function F07 removes the region of feature 115 detected by the X-ray detector 120 through image processing. Alternatively, the image processing function F07 may also perform a non-display process on the non-display region containing feature 115 depicted in the X-ray image. This case will be explained using Figure 13. To further enhance

[0067] Figure 13 shows a display process as an alternative to image processing, illustrating feature 115 depicted in the X-ray image IM. The image processing function F07 sets a hidden area A in the X-ray image IM to include feature 115. The image processing function F07 performs a hiding process that makes it possible to visually hide elements of the hidden area A, which is part of the X-ray image IM. For example, elements of the hidden area A of the X-ray image IM are hidden using CSS (Cascading Style Sheets). This makes it possible to hide elements of the hidden area A when the X-ray image IM is displayed by the control device 20 of the X-ray diagnostic device 1 or by an external device (e.g., a viewer) of the X-ray diagnostic device 1, and the operator of the control device 20 or viewer can selectively switch the hidden elements of the hidden area A to be displayed.

[0068] Thus, even without hiding the features 115 of the X-ray image IM using image processing as shown in Figures 9(a) to 9(d), image processing can be replaced with a hiding process, and in that case, processing time can be reduced compared to the case of image processing. Furthermore, although it is a principle to display all data of the X-ray irradiation area, it may be acceptable to hide it because the hidden area A is very small and the image itself within the hidden area A is not being processed.

[0069] In each embodiment, the calculation function and image processing function are examples of the calculation unit and image processing unit, respectively.

[0070] According to at least one embodiment described above, information indicating the relative positional relationship between the X-ray tube and the X-ray detector necessary for an X-ray diagnostic device (e.g., SID information and oblique angle information) can be obtained with a simple configuration.

[0071] While several embodiments of the present invention 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 carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made 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]

[0072] 1. X-ray diagnostic equipment 10 Imaging device 20 Control device 100 X-ray tube equipment 101 X-ray tube 110 X-ray diaphragm 111 X-ray aperture 112 aperture blades 114 Cover component 115 Features F04 Calculation Function F05 SID Calculation Function F07 Image Processing Function F08 Oblique Angle Calculation Function

Claims

1. X-ray tube and An X-ray diaphragm device comprising an X-ray diaphragm that defines the irradiation field of the X-rays irradiated from the aforementioned X-ray tube, and equipped with a characteristic object, An X-ray detector that detects the X-rays irradiated from the X-ray tube and transmitted through the subject, A calculation unit calculates information indicating the relative positional relationship between the X-ray tube and the X-ray detector based on an image of the feature object depicted in an X-ray image based on transmission data acquired by the X-ray detector, An X-ray diagnostic device equipped with [specific features / features].

2. The calculation unit calculates the SID (Source-to-Image Distance), which is the distance from the X-ray focal point to the X-ray detector, as information indicating the relative positional relationship. The X-ray diagnostic apparatus according to claim 1.

3. The calculation unit calculates information indicating the relative positional relationship based on the dimensions of the feature object provided in the X-ray diaphragm device as depicted in the X-ray image. The X-ray diagnostic apparatus according to claim 1.

4. The calculation unit calculates an unknown SID using the ratio of the reference detection dimension, which is the dimension of the feature object depicted in the X-ray image collected by calibration imaging when the SID, which is the distance from the focal point of the X-ray to the X-ray detector, is set to a known SID, to the dimension of the feature object depicted in the X-ray image collected during inspection, and the known SID. The X-ray diagnostic apparatus according to claim 1.

5. The calculation unit calculates the SID based on the ratio of the actual dimensions of the feature object to the dimensions depicted in the X-ray image, and the distance from the X-ray focal point to the feature object. The X-ray diagnostic apparatus according to claim 1.

6. The aforementioned feature is a plurality of members, each having a plurality of characteristic shapes provided on the side surface of at least one of the plurality of aperture blades constituting the X-ray aperture, and the dimension of the feature as depicted in the X-ray image is the distance between the plurality of members. The X-ray diagnostic apparatus according to claim 4 or 5.

7. The aforementioned characteristic shape is a shape that includes at least one of a convex shape and a concave shape. The X-ray diagnostic apparatus according to claim 6.

8. The feature is a member having a distinctive shape provided on the side surface of at least one of the multiple aperture blades constituting the X-ray aperture, and the dimension of the feature as depicted in the X-ray image is the length of the member. The X-ray diagnostic apparatus according to claim 4 or 5.

9. The aforementioned characteristic shape is a shape that includes at least one of a convex shape and a concave shape. The X-ray diagnostic apparatus according to claim 8.

10. The aforementioned features are a convex portion provided on a first aperture blade, which is one of the plurality of aperture blades constituting the X-ray aperture, and a concave portion provided on a second aperture blade facing the first aperture blade. The convex portion and the concave portion are formed to interlock with each other when the X-ray aperture is closed. The X-ray diagnostic apparatus according to claim 6.

11. The aforementioned features are a convex portion provided on a first aperture blade, which is one of the plurality of aperture blades constituting the X-ray aperture, and a concave portion provided on a second aperture blade facing the first aperture blade. The convex portion and the concave portion are formed to interlock with each other when the X-ray aperture is closed. The X-ray diagnostic apparatus according to claim 8.

12. The aforementioned feature is part of the case housing the X-ray aperture, and is provided on a cover member provided in a transmission window that transmits the X-rays toward the subject. The X-ray diagnostic apparatus according to claim 4 or 5.

13. The aforementioned feature is a grid-like pattern provided on the cover member. The X-ray diagnostic apparatus according to claim 12.

14. The calculation unit further calculates the angle of oblique entry of the X-rays to the X-ray detector from the degree of distortion of the grid-like pattern detected by the X-ray detector, as information indicating the relative positional relationship. The X-ray diagnostic apparatus according to claim 1.

15. An image processing unit that performs an erasure process to make partial images corresponding to the feature objects depicted in the X-ray image less conspicuous. Furthermore, The X-ray diagnostic apparatus according to claim 1.

16. An image processing unit that performs a non-display process on the region containing the feature object depicted in the X-ray image. Furthermore, The X-ray diagnostic apparatus according to claim 1.

17. A distinctive feature provided in the X-ray diaphragm device is a part of the case housing the X-ray diaphragm, which is a grid-like pattern provided on a cover member provided in a transmission window that transmits the X-rays toward the subject. The calculation unit calculates the angle of oblique entry of the X-rays to the X-ray detector from the degree of distortion of the grid pattern detected by the X-ray detector, as information indicating the relative positional relationship. The X-ray diagnostic apparatus according to claim 1.

18. The feature provided in the X-ray diaphragm is a characteristic pattern that includes positional information of at least three spatially separated points. The calculation unit calculates the angle of oblique entry of the X-rays to the X-ray detector as information indicating the relative positional relationship, based on the difference in shape between the first characteristic pattern provided in the X-ray diaphragm and the second characteristic pattern detected by the X-ray detector. The X-ray diagnostic apparatus according to claim 1.

19. The aforementioned feature is a portion of one of the multiple aperture blades constituting the X-ray aperture, which is a part of the aperture blades, that has a through hole for allowing the X-rays to pass through. The X-ray diagnostic apparatus according to claim 4 or 5.

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