X-ray diagnostic apparatus and method for controlling the X-ray diagnostic apparatus

Abstract

To reduce a burden of a subject in a case of executing both of two-dimensional imaging and tomosynthesis imaging.SOLUTION: An X-ray diagnostic apparatus includes an X-ray tube, an X-ray detection part and an imaging control part. The X-ray tube applies X-ray to a subject. The X-ray detection part detects the x-ray emitted from the X-ray tube. An imaging control function executes two-dimensional imaging at a specific irradiation angle out of an imaging range that defines a range of irradiation angles of the X-ray to the subject, controls the X-ray tube to execute tomosynthesis imaging at another irradiation angle other than the specific irradiation angle, and continuously executes the tomosynthesis imaging and two-dimensional imaging from one end to the other end within the imaging range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, in an examination using an X-ray diagnostic apparatus, two-dimensional imaging and tomosynthesis imaging are sometimes performed consecutively on a positioned subject.

[0003] For example, in a mammography device, both 2D imaging and tomosynthesis imaging may be performed consecutively on the breast of a subject held in place by a compression plate. In this case, in addition to the time required for each of the 2D imaging and tomosynthesis imaging, time is also required for moving from the 2D imaging position to the tomosynthesis imaging start position, or from the tomosynthesis imaging end position to the 2D imaging position. Therefore, the breast is continuously compressed during this time, placing a significant burden on the subject.

[0004] Furthermore, for example, two-dimensional imaging and tomosynthesis imaging overlap at some positions, meaning that conventional technology places a heavy burden on the subject in terms of radiation exposure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-187042 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to reduce the burden on the subject when performing both 2D imaging and tomosynthesis imaging. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be considered as other problems. [Means for solving the problem]

[0007] An X-ray diagnostic apparatus according to an embodiment includes an X-ray tube, an X-ray detection unit, and an imaging control unit. The X-ray tube irradiates a subject with X-rays. The X-ray detection unit detects the X-rays emitted from the X-ray tube. The imaging control function controls the X-ray tube to perform two-dimensional imaging at a specific irradiation angle within an imaging range that defines the range of X-ray irradiation angles for the subject, and to perform tomosynthesis imaging at irradiation angles other than the specific irradiation angle, thereby continuously performing tomosynthesis imaging and two-dimensional imaging from one end of the imaging range to the other. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a mammography apparatus according to the first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of the imaging process performed by the mammography apparatus according to the first embodiment. [Figure 3] FIG. 3 is a graph showing an example of a change in angular velocity of the arm according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing an example of processing executed by the mammography apparatus according to the first embodiment. [Figure 5] FIG. 5 is an explanatory diagram showing an example of the imaging process executed by the mammography apparatus according to the second embodiment. [Figure 6] FIG. 6 is a graph showing an example of a change in angular velocity of the arm according to the second embodiment. [Figure 7]FIG. 7 is an explanatory diagram showing an example of the behavior of the mammography apparatus 1 according to the second embodiment during two-dimensional imaging. [Figure 8] FIG. 8 is a flowchart showing an example of processing executed by the mammography apparatus according to the second embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing an example of the imaging process executed by the mammography apparatus according to the first modification. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of a mammography apparatus according to the second modification. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of a mammography apparatus according to the third modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. Note that the X-ray diagnostic apparatus and the control method for the X-ray diagnostic apparatus are not limited to the embodiments shown below. In the following description, similar components will be given common reference numerals, and duplicated descriptions will be omitted.

[0010] (First embodiment) Fig. 1 is a block diagram showing an example of the configuration of a mammography device 1 according to the first embodiment. As shown in Fig. 1, the mammography device 1 includes a breast imaging unit 10 and a console device 20. The mammography device 1 is an example of an X-ray diagnostic device.

[0011] The breast imaging unit 10 compresses the breast B, which has been positioned by an operator such as a radiologist, and performs X-ray imaging. The breast imaging unit 10 performs X-ray imaging on each of the left and right breasts B. In this embodiment, the X-ray imaging performed by the breast imaging unit 10 includes two-dimensional imaging (mammography imaging) and tomosynthesis imaging. The breast imaging unit 10 performs two-dimensional imaging and tomosynthesis imaging consecutively while maintaining the position of the breast B.

[0012] Here, two-dimensional imaging is an imaging method for obtaining a planar image by irradiating breast B with X-rays from one direction. Tomosynthesis imaging is an imaging method for obtaining a three-dimensional image by sequentially irradiating breast B with X-rays from multiple directions. The X-ray imaging directions for breast B include the cranio-caudal (CC) direction, the medial-lateral oblique (MLO) direction, etc.

[0013] The mammography unit 10 includes an X-ray high voltage device 101, an X-ray tube 102, an X-ray aperture 103, a compression paddle 104, a mounting table 105, an X-ray detector 106, an arm 107, a system control circuit 108, an arm drive circuit 109, and a compression paddle drive circuit 110.

[0014] The X-ray high voltage device 101 generates a high voltage under the control of the system control circuit 108, and applies the generated high voltage to the X-ray tube 102. The X-ray tube 102 irradiates X-rays toward the breast B placed on the mounting table 105 based on the high voltage applied by the X-ray high voltage device 101.

[0015] The X-ray aperture 103 includes, for example, a pair of aperture blades provided on each of the top and bottom and the left and right (four blades in total). The aperture blades are formed into flat plates from a material such as lead that blocks X-rays. The X-ray aperture 103 opens and closes the aperture blades under the control of the system control circuit 108, and forms an irradiation range (irradiation field) of the X-rays irradiated from the X-ray tube 102.

[0016] The compression plate 104 is a transparent or semi-transparent plate made of a material such as resin through which X-rays pass, and compresses the breast B placed on the mounting table 105. The compression plate 104 is movably supported by an arm 107, and is moved toward and away from the mounting table 105. The mounting table 105 is a table on which the breast B is placed, and is supported by the arm 107. The mounting table 105 is provided at a position opposite the X-ray tube 102, and includes an X-ray detector 106 inside.

[0017] The X-ray detector 106 is configured by, for example, an FPD, etc. The X-ray detector 106 detects X-rays that are emitted from the X-ray tube 102 and transmitted through the breast B. The X-ray detector 106 supplies a detection signal corresponding to the detected X-rays to the console device 20.

[0018] The arm 107 has, for example, an X-ray tube support mechanism and a mounting table support mechanism, which are provided so that they can be moved independently by an arm drive circuit 109. The X-ray tube support mechanism supports the X-ray tube 102 and the X-ray aperture 103. The mounting table support mechanism supports the compression plate 104 and the mounting table 105.

[0019] The system control circuit 108 is configured by, for example, a processor. The system control circuit 108 receives control signals supplied from the console device 20, and controls the X-ray high voltage device 101, the X-ray tube 102, the X-ray aperture 103, the mounting table 105, the X-ray detector 106, the arm 107, the arm drive circuit 109, and the compression paddle drive circuit 110 based on the control signals.

[0020] The arm drive circuit 109 is composed of, for example, a motor, an actuator, etc. The arm drive circuit 109 drives the arm 107 under the control of the system control circuit 108. The position of the X-ray imaging (2D imaging and tomosynthesis imaging) relative to the breast B changes by driving the arm 107. The compression plate drive circuit 110 is composed of, for example, a motor, an actuator, etc. The compression plate drive circuit 110 drives the compression plate 104 under the control of the system control circuit 108. By driving the compression plate 104, the breast B placed on the mounting table 105 is compressed.

[0021] On the other hand, the console device 20 has a processing circuit 21, an input interface 22, a display 23, and a memory circuit 24.

[0022] The processing circuitry 21 is composed of, for example, a processor. The processing circuitry 21 controls the various components of the console device 20 and the system control circuitry 108 of the mammography unit 10, thereby controlling the entire mammography apparatus 1. The processing circuitry 21 also functions as an imaging control function 211, a detection function 212, a display control function 213, a generation function 214, and a reconstruction function 215 by reading and executing programs stored in the memory circuitry 24.

[0023] Here, the imaging control function 211 is an example of an imaging control unit, and the reconstruction function 215 is an example of a reconstruction unit.

[0024] The imaging control function 211 controls the X-ray tube 102 to perform two-dimensional imaging at a specific irradiation angle within an imaging range that specifies the range of X-ray irradiation angles for breast B, and to perform tomosynthesis imaging at irradiation angles other than the specific irradiation angle, thereby continuously performing tomosynthesis imaging and two-dimensional imaging from one end of the imaging range to the other end.

[0025] For example, the imaging control function 211 sets an imaging range (e.g., -15° to +15°) and controls the X-ray tube 102 and the arm 107 via the system control circuit 108 to perform tomosynthesis imaging and two-dimensional imaging continuously from one end of the imaging range to the other end.

[0026] It should be noted that the arm 107 supports the X-ray tube 102, and therefore when the arm 107 is moved, the X-ray tube 102 also moves together with the arm 107. Therefore, it can be said that the angular velocity of the arm 107, which represents the moving speed of the arm 107, represents the moving speed of the X-ray tube 102.

[0027] Furthermore, when starting two-dimensional imaging, if tomosynthesis imaging has been performed immediately before, the imaging control function 211 performs two-dimensional imaging based on the imaging conditions of the immediately preceding tomosynthesis imaging. Specific processing executed by the imaging control function 211 will be described later.

[0028] The detection function 212 detects the position of the X-ray tube 102. For example, the detection function 212 detects that the focal point of the X-ray tube 102 has reached the imaging position for two-dimensional imaging. Specifically, the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging (for example, the angle of the arm 107 in the CC direction is 0°) based on the detection result of the detector.

[0029] For example, the detector may be a potentiometer that detects the rotation angle or the amount of movement, an encoder that is a position detection sensor, etc. The encoder may be a so-called absolute encoder such as a magnetic type, a brush type, or a photoelectric type. Furthermore, the detection function 212 may use various types of detectors as appropriate, such as a rotary encoder that outputs rotational displacement as a digital signal or a linear encoder that outputs linear displacement as a digital signal.

[0030] The display control function 213 displays various images on the display 23. For example, the display control function 213 displays X-ray images obtained by two-dimensional imaging or tomosynthesis imaging, tomographic images generated by the reconstruction function 215, etc. Hereinafter, an X-ray image obtained by two-dimensional imaging will also be referred to as a two-dimensional image. Also, an X-ray image obtained by tomosynthesis imaging will also be referred to as a tomosynthesis image.

[0031] The generation function 214 generates an X-ray image. Specifically, the generation function 214 first acquires, from the mammography unit 10, a detection signal corresponding to the X-ray detected by the X-ray detector 106 of the mammography unit 10. Next, the generation function 214 performs image processing based on the detection signal to generate an X-ray image. The image processing performed by the generation function 214 includes, for example, frequency processing, dynamic range compression processing, and gradation processing.

[0032] The reconstruction function 215 generates tomographic images. For example, the reconstruction function 215 performs image reconstruction on a plurality of tomosynthesis images obtained by tomosynthesis imaging using a technique such as FBP (Filtered Back Projection) or OS-EM, thereby generating a plurality of tomographic images.

[0033] The input interface 22 is configured with an input device that accepts various input operations from an operator. The input interface 22 accepts the input operations from the operator and supplies the processing circuit 21 with an electrical signal corresponding to the accepted input operation.

[0034] For example, the input interface 22 is composed of various buttons such as a mouse, keyboard, trackball, and exposure switch, a touchpad that performs input operations by touching the operation surface, a touchscreen that integrates a display screen and a touchpad, a non-contact input circuit using an optical sensor, and a voice input circuit.

[0035] The display 23 is configured as a display device that displays various types of information. For example, the display 23 displays a GUI (Graphical User Interface), an X-ray image, etc. under the control of the display control function 213.

[0036] The memory circuitry 24 is configured, for example, with semiconductor memory elements such as RAM (Random Access Memory) and flash memory, a hard disk, an optical disk, etc., and stores various information, various data, and various programs. For example, the memory circuitry 24 stores a GUI (Graphical User Interface), X-ray images, etc. The memory circuitry 24 also stores programs that are executed by the processing circuitry 21 and cause the processing circuitry 21 to function as an imaging control function 211, a detection function 212, a display control function 213, a generation function 214, and a reconstruction function 215.

[0037] The functions of the mammography apparatus 1 configured as above will be described with reference to Figures 2 and 3. Figure 2 is an explanatory diagram showing an example of the imaging process performed by the mammography apparatus 1 according to the first embodiment. Note that the compression paddle 104 is not shown in Figure 12.

[0038] When imaging is not being performed, the X-ray tube 102 and the X-ray aperture 103 are located at fixed positions as shown in Fig. 2(a). When imaging is being performed, the subject's breast B is placed on the mounting table 105 at this fixed position and compressed by the compression paddle 104. Then, when the imaging control function 211 receives an imaging instruction from a user such as a doctor or technician, it moves to the start position of tomosynthesis imaging (for example, -15°) as shown in Fig. 2(b).

[0039] At this time, the detection function 212 detects that the X-ray tube 102 has moved to the start position of tomosynthesis imaging. When the detection function 212 detects that the X-ray tube 102 has reached the start position of tomosynthesis imaging, the imaging control function 211 performs tomosynthesis imaging while moving the position of the X-ray tube 102 relative to the breast B (X-ray detector 106), as shown in FIG. 2(c).

[0040] Next, the detection function 212 detects that the X-ray tube 102 has reached the imaging position (for example, 0°) for two-dimensional imaging. When the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging, the imaging control function 211 temporarily stops the movement of the X-ray tube 102.

[0041] Then, the imaging control function 211 performs two-dimensional imaging at the imaging position for two-dimensional imaging, as shown in Fig. 2(d). Here, the imaging control function 211 may determine imaging conditions for two-dimensional imaging, such as tube voltage and tube current, based on the imaging conditions of the tomosynthesis imaging performed immediately before. In this case, the imaging control function 211 performs two-dimensional imaging based on the determined imaging conditions.

[0042] After the two-dimensional imaging is completed, the imaging control function 211 resumes the movement of the X-ray tube 102 and resumes the tomosynthesis imaging, as shown in Fig. 2(e). Then, the detection function 212 detects the end position of the tomosynthesis imaging (for example, +15°). When the detection function 212 detects that the X-ray tube 102 has reached the start position of the tomosynthesis imaging, the imaging control function 211 ends the tomosynthesis imaging.

[0043] Furthermore, the generation function 214 generates a tomosynthesis image and a two-dimensional image based on the detection results detected by the X-ray detector 106 in the above-described tomosynthesis imaging and two-dimensional imaging. Then, the reconstruction function 215 generates a plurality of tomographic images by performing image reconstruction based on the tomosynthesis image and the two-dimensional image.

[0044] It is preferable that, when reconstructing an image, the reconstruction function 215 corrects the two-dimensional image based on the dose ratio between the tomosynthesis image and the two-dimensional image, and generates a tomographic image using the corrected two-dimensional image.

[0045] Here, the reason why the reconstruction function 215 corrects the two-dimensional image will be explained. As described above, when tomosynthesis imaging and two-dimensional imaging are performed consecutively in the mammography apparatus 1, the tomosynthesis image of the tomosynthesis imaging will be missing at the imaging position of the two-dimensional imaging. Therefore, the reconstruction function 215 uses the two-dimensional image obtained at the imaging position of the two-dimensional imaging as the tomosynthesis image at that imaging position.

[0046] However, in 2D imaging, the radiation dose is higher than in tomosynthesis imaging, and if reconstruction processing is performed using 2D images as they are, there is a possibility that a tomographic image will not be generated correctly. Therefore, the reconstruction function 215 performs image reconstruction using 2D images corrected based on the dose ratio between the tomosynthesis image and the 2D image. This improves the accuracy of the generated tomographic image.

[0047] Fig. 3 is a graph showing an example of changes in the angular velocity of the arm 107 in the first embodiment. The vertical axis of Fig. 3 represents the angular velocity of the arm 107, and the horizontal axis represents the elapsed time from the start of imaging. Note that the periods (c), (d), and (e) shown in Fig. 3 correspond to the imaging periods (c), (d), and (e) described in Fig. 2.

[0048] 3, the arm 107 moves at a constant angular velocity during periods (c) and (e) corresponding to tomosynthesis imaging, and is stationary during period (d) corresponding to two-dimensional imaging.

[0049] In this way, by successively performing tomosynthesis imaging and two-dimensional imaging from one end of the imaging range to the other, it is possible to reduce imaging time. The reason for this will be explained below.

[0050] For example, when performing tomosynthesis imaging after 2D imaging, first, 2D imaging is performed at a specific irradiation angle such as an irradiation angle of 0°, then the system moves to the start position of tomosynthesis imaging and performs tomosynthesis imaging from one end of the imaging range to the other.Furthermore, for example, when performing 2D imaging after tomosynthesis imaging, tomosynthesis imaging is performed from one end of the imaging range to the other, then the system moves to the start position of 2D imaging at an irradiation angle of 0°, and 2D imaging is performed at that irradiation angle.

[0051] In such an imaging method, when switching between two-dimensional imaging and tomosynthesis imaging, it takes time to move the X-ray tube 102. Furthermore, in tomosynthesis imaging, imaging is performed at an irradiation angle that overlaps with two-dimensional imaging, so imaging is performed at some imaging angles that overlap.

[0052] On the other hand, when tomosynthesis imaging and two-dimensional imaging are performed continuously from one end of the imaging range to the other, as in this embodiment, the time required to move the X-ray tube 102, which occurs when switching between two-dimensional imaging and tomosynthesis imaging, can be reduced, thereby shortening the imaging time.

[0053] Furthermore, it is possible to prevent overlapping imaging at the same imaging angle between 2D imaging and tomosynthesis imaging, thereby reducing the amount of radiation exposure to the subject.

[0054] Next, the processing executed by the mammography apparatus 1 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the processing executed by the mammography apparatus 1 according to the first embodiment. Note that this processing is premised on the assumption that the breast B of the subject has been placed on the placement table 105 and that compression of the breast B has begun by the compression paddle 104.

[0055] When the imaging control function 211 receives an imaging instruction from the user, it moves the X-ray tube 102 to the start position of tomosynthesis imaging (step S1). When the X-ray tube 102 reaches the start position as a result of movement of the X-ray tube 102, the detection function 212 detects that the X-ray tube 102 is located at the start position of tomosynthesis imaging. Next, the imaging control function 211 starts tomosynthesis imaging (step S2). In step S2, the imaging control function 211 performs tomosynthesis imaging while moving the X-ray tube 102.

[0056] Furthermore, when the movement of the X-ray tube 102 causes the X-ray tube 102 to reach the imaging position for two-dimensional imaging, the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging (step S3). When the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging, the imaging control function 211 temporarily stops the movement of the X-ray tube 102 (step S4).

[0057] Next, the imaging control function 211 starts two-dimensional imaging with the movement of the X-ray tube 102 stopped (step S5). At this time, the imaging control function 211 may determine the imaging conditions for the two-dimensional imaging based on the imaging conditions of the immediately preceding tomosynthesis imaging. When the imaging control function 211 confirms that the two-dimensional imaging has ended (step S6), it resumes the movement of the X-ray tube 102 (step S7). Furthermore, the imaging control function 211 resumes tomosynthesis imaging in parallel with step S7 (step S8).

[0058] When the X-ray tube 102 moves to reach the end position of the tomosynthesis imaging, the detection function 212 detects that the X-ray tube 102 is located at the end position of the tomosynthesis imaging. When the detection function 212 detects that the X-ray tube 102 is located at the end position of the tomosynthesis imaging, the imaging control function 211 ends the tomosynthesis imaging and ends this processing (step S9).

[0059] In this way, the mammography apparatus 1 according to the first embodiment is equipped with an imaging control function 211 that controls the X-ray tube 102 to perform two-dimensional imaging at a first angle indicating the imaging position for two-dimensional imaging, and to perform tomosynthesis imaging at a second angle within the imaging range that does not include the first angle, thereby continuously performing tomosynthesis imaging and two-dimensional imaging from one end of the imaging range to the other.

[0060] For example, when tomosynthesis imaging is performed after 2D imaging, both 2D imaging and tomosynthesis imaging are performed at the 2D imaging position. In contrast, the imaging control function 211 according to the first embodiment performs only 2D imaging at the 2D imaging position, thereby shortening the imaging time compared to when tomosynthesis imaging is performed after 2D imaging. Furthermore, for example, in the mammography apparatus 1, the subject's breast B is continuously compressed during the imaging time, so shortening the imaging time can reduce the burden on the subject.

[0061] Furthermore, by shortening the imaging time, the amount of radiation exposure can be reduced, and therefore the mammography apparatus 1 according to the first embodiment can also reduce the burden on the subject from the perspective of radiation exposure.

[0062] The imaging control function 211 also performs control to stop the X-ray tube 102 at the imaging position for 2D imaging, perform 2D imaging, and resume tomosynthesis imaging after the 2D imaging. By performing 2D imaging by stopping the X-ray tube 102 at the imaging position for 2D imaging, it is possible to capture a high-quality 2D image without blurring.

[0063] Furthermore, the imaging control function 211 determines the imaging conditions for 2D imaging from the projection image obtained by the immediately preceding tomosynthesis imaging, which eliminates the need to perform imaging to determine the conditions, and is believed to reduce imaging time and exposure dose.

[0064] In addition, the mammography apparatus 1 according to the first embodiment is equipped with a reconstruction function 215 that corrects two-dimensional images captured by two-dimensional imaging in accordance with the dose ratio between the two-dimensional image and multiple projection images obtained by tomosynthesis imaging, and performs reconstruction processing.

[0065] By correcting the two-dimensional image according to the dose ratio and performing image reconstruction processing, multiple high-quality tomographic images can be generated using the two-dimensional image without performing tomosynthesis imaging at the two-dimensional imaging position.

[0066] (Second embodiment) Next, a mammography apparatus 1 according to a second embodiment will be described. In the second embodiment, a configuration will be described in which two-dimensional imaging is performed without stopping the movement of the X-ray tube 102 at the imaging position for two-dimensional imaging. In the description of the second embodiment, parts that show the same operations as those in the first embodiment described above will be given the same reference numerals in the drawings, etc., and detailed description thereof will be omitted.

[0067] The imaging control function 211 according to the second embodiment will be described below with reference to Figures 5 to 7. Figure 5 is an explanatory diagram showing an example of imaging processing executed by the mammography apparatus 1 according to the second embodiment. Note that (c) in Figure 5 is the same as (c) in Figure 2, and therefore its description will be omitted.

[0068] When performing both tomosynthesis imaging and two-dimensional imaging, the imaging control function 211 controls tomosynthesis imaging by moving the X-ray tube 102 in the same manner as in the first embodiment described above (see (c) of FIG. 5). Furthermore, when the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging, the imaging control function 211 slows down the moving speed of the X-ray tube 102. Then, as shown in (d1) of FIG. 5, the imaging control function 211 performs two-dimensional imaging while moving the X-ray tube 102 at a speed slower than that during tomosynthesis imaging.

[0069] Then, when the two-dimensional imaging is completed, the imaging control function 211 returns the moving speed of the X-ray tube 102 to the original speed and resumes tomosynthesis imaging, as shown in Fig. 5(e). After that, the same processing as in Fig. 2 is performed.

[0070] Fig. 6 is a graph showing an example of changes in the angular velocity of the arm 107 in the second embodiment. The vertical axis of Fig. 6 represents the angular velocity of the arm 107, and the horizontal axis represents the elapsed time from the start of imaging.

[0071] 6, the arm 107 moves at a constant angular velocity during periods (c) and (e) corresponding to tomosynthesis imaging. Also, the arm 107 moves at a constant angular velocity slower than that during tomosynthesis imaging during period (d1) corresponding to two-dimensional imaging.

[0072] In the above example, the angular velocity of the arm 107 is reduced during two-dimensional imaging, but two-dimensional imaging may be performed while maintaining the angular velocity of the arm 107 during tomosynthesis imaging.

[0073] In this way, by starting tomosynthesis imaging, performing 2D imaging without stopping once the 2D imaging is reached, and then resuming tomosynthesis imaging after the 2D imaging is completed, it is possible to shorten the imaging time for tomosynthesis imaging and the entire 2D imaging compared to stopping at the 2D imaging position and performing 2D imaging.

[0074] However, when two-dimensional imaging is performed while the X-ray tube 102 is moving, there is a possibility that the two-dimensional image will be blurred. Therefore, while capturing a two-dimensional image, the distance that the projected image of the breast B (object) moves on the incident surface of the X-ray detector 106 must be kept within the allowable value for blur. This distance changes depending on the angular velocity of the arm 107 during two-dimensional imaging and the imaging time for two-dimensional imaging. Therefore, the imaging control function 211 determines the angular velocity of the arm 107 during two-dimensional imaging and the imaging time for two-dimensional imaging in order to keep this distance within the allowable value for blur.

[0075] The above processing will be explained below with reference to Figure 7. Figure 7 is an explanatory diagram showing an example of the behavior of the mammography apparatus 1 according to the second embodiment during two-dimensional imaging. This diagram shows the behavior of each part related to two-dimensional imaging of the mammography apparatus 1 when two-dimensional imaging is performed while the arm 107 rotates around the center of rotation AC. It is assumed that the focal position FS of the X-ray tube 102 at the start of two-dimensional imaging and the focal position FE of the X-ray tube 102 at the end are both located on a plane parallel to the X-ray detector 106.

[0076] In FIG. 7, the arm rotation radius (mm) is represented by r, the source image distance (SID) (mm) is represented by s, and the distance between the breast B and the X-ray detector 106 (PID) (mm) is represented by p.

[0077] Here, if the imaging period (time) of 2D imaging is t and the angular velocity (deg / s) during 2D imaging is w, then the angle by which the X-ray tube 102 rotates during the 2D imaging period is expressed as w×t. Furthermore, if the distance that the focal point of the X-ray tube 102 moves within a plane parallel to the X-ray detector 106 during the 2D imaging period is d, then d = 2r×sin(w×t / 2). Furthermore, if the distance that the projection image of the breast B moves on the incident plane of the X-ray detector 106 during the 2D imaging period is D, then D = 2r×sin(w×t / 2)×(p / (sp)).

[0078] If the allowable blur value (mm) is c, the imaging control function 211 determines the angular velocity w of the arm 107 and the imaging period t of the two-dimensional imaging so that D≦c, and performs two-dimensional imaging. Note that the imaging control function 211 preferably controls the tube voltage and tube current to be higher than those during tomosynthesis imaging so that the dose is not insufficient when two-dimensional imaging is performed with the determined angular velocity w of the arm 107 and the imaging period t of the two-dimensional imaging.

[0079] Next, the processing executed by the mammography apparatus 1 according to the second embodiment will be described. Fig. 8 is a flowchart showing an example of the processing executed by the mammography apparatus 1 according to the second embodiment. Note that steps S11 to S13 are the same as steps S1 to S3 in Fig. 4, and therefore their description will be omitted.

[0080] When the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging, the imaging control function 211 slows down the moving speed of the X-ray tube 102 (step S14). Next, the imaging control function 211 starts two-dimensional imaging with the moving speed of the X-ray tube 102 slowed down (step S15).

[0081] At this time, the imaging control function 211 determines the imaging conditions for the two-dimensional imaging based on the imaging conditions of the immediately preceding tomosynthesis imaging. The imaging control function 211 performs two-dimensional imaging while moving the X-ray tube 102 in accordance with the imaging conditions, and confirms that the imaging process has been completed (step S16).

[0082] When the imaging control function 211 confirms that the imaging process for two-dimensional imaging has ended, it returns the moving speed of the X-ray tube 102 to the original speed (step S17). The subsequent processing steps S18 and S19 are similar to steps S8 and S9 in Fig. 4, and therefore their explanation will be omitted.

[0083] In this way, the imaging control function 211 of the mammography apparatus 1 according to the second embodiment starts tomosynthesis imaging from one end of the imaging range and performs two-dimensional imaging without stopping the X-ray tube at the imaging position for two-dimensional imaging. The imaging control function 211 also performs two-dimensional imaging at a moving speed and imaging time of the X-ray tube 102 determined according to the allowable blur amount, and adjusts the tube voltage and tube current to be larger than those during tomosynthesis imaging.

[0084] As a result, the mammography apparatus 1 according to the second embodiment can shorten the overall imaging time for tomosynthesis imaging and 2D imaging compared to when the mammography apparatus 1 stops at the 2D imaging position and performs 2D imaging. In addition, because the tube voltage and tube current are adjusted, degradation of the image quality of the 2D image can be prevented.

[0085] Furthermore, the imaging control function 211 according to the second embodiment performs two-dimensional imaging by slowing down the moving speed of the X-ray tube 102 at the imaging position for two-dimensional imaging. This reduces the possibility of blurring occurring in the two-dimensional image.

[0086] The above-described embodiment can be modified as needed by changing some of the configurations or functions of the mammography apparatus 1. Therefore, several modifications of the above-described embodiment will be described below as other embodiments. The following mainly focuses on differences from the above-described embodiment, and detailed descriptions of commonalities with the content already described will be omitted. The modifications described below may be implemented individually or in appropriate combinations.

[0087] (Variation 1) In the second embodiment described above, the angular velocity of the arm 107 and the two-dimensional imaging time are determined so that the distance that the projected image of the breast B (object) moves on the incident surface of the X-ray detector 106 falls within the allowable blurring value, and imaging is performed. However, the method for preventing blurring is not limited to this, and other methods may be used.

[0088] For example, the X-ray detector 106 may be configured to be movable, and during two-dimensional imaging, the imaging control function 211 may move the X-ray detector 106 in the direction opposite to the moving direction of the X-ray tube 102 via the system control circuit 108, thereby preventing blurring of the two-dimensional image. The imaging process performed by the imaging control function 211 in this variant will now be described.

[0089] Fig. 9 is an explanatory diagram showing an example of the imaging process executed by the mammography apparatus 1 according to Modification 1. Note that (c) in Fig. 9 is the same as (c) in Fig. 2, and therefore a description thereof will be omitted.

[0090] When the detection function 212 detects that the X-ray tube 102 has reached the imaging position for two-dimensional imaging, the imaging control function 211 starts moving the X-ray detector 106 in the direction opposite to the moving direction of the X-ray tube 102, as shown in Fig. 9(d2). Then, the imaging control function 211 performs two-dimensional imaging while moving the X-ray tube 102 and the X-ray detector 106, as shown in Fig. 9(d2).

[0091] As described above, blurring of the two-dimensional image occurs because the distance that the projection image of breast B moves on the incident surface of X-ray detector 106 increases during two-dimensional imaging, as shown by D in Fig. 7. Here, if X-ray detector 106 is moved in the direction opposite to the movement direction of X-ray tube 102 during two-dimensional imaging, the projection image of breast B moves on the incident surface of X-ray detector 106 in the direction opposite to the movement direction of X-ray tube 102.

[0092] This cancels out the effect of movement of the projected image of breast B caused by movement of the X-ray tube 102. Therefore, the same effect as when the distance that the projected image of breast B moves on the incident surface of the X-ray detector 106 during two-dimensional imaging is reduced can be obtained. In other words, blurring of the two-dimensional image can be suppressed.

[0093] If the moving speed of the X-ray detector 106 is too slow compared to the moving speed of the X-ray tube 102, the above-mentioned effect may not be fully achieved. On the other hand, if it is too fast, blurring of the two-dimensional image may occur due to the movement of the X-ray detector 106. Therefore, it is preferable to adjust the moving speed of the X-ray detector 106 depending on the configuration of the mammography apparatus 1 and the imaging conditions of the X-ray tube 102 during two-dimensional imaging.

[0094] For example, as in Figure 7, if the angular velocity of the arm 107 during two-dimensional imaging is w, the imaging period is t, and the tolerance for blur (mm) is c, the imaging control function 211 determines the movement speed of the X-ray detector 106 so that the movement distance D of the X-ray detector 106 during this imaging period t is D≦c.

[0095] Then, when the two-dimensional imaging is completed, the imaging control function 211 returns the X-ray detector 106 to the position before the start of the two-dimensional imaging, and then resumes the tomosynthesis imaging.

[0096] 9, after the two-dimensional imaging is completed, the X-ray detector 106 is returned to the position before the start of the two-dimensional imaging, but the imaging control function 211 may stop the movement of the X-ray detector 106 after the two-dimensional imaging is completed, and immediately resume tomosynthesis imaging at the position where the X-ray detector 106 was stopped.

[0097] In this case, since the position of the X-ray detector 106 is different from when the tomosynthesis imaging started, the reconstruction function 215 performs image reconstruction processing by correcting the tomosynthesis image based on the positional relationship between the X-ray tube 102 and the X-ray detector 106. Furthermore, it is necessary to adjust the position of the X-ray detector 106 when the tomosynthesis imaging started so that X-rays are not irradiated outside the detection range of the X-ray detector 106 when the tomosynthesis imaging is resumed.

[0098] Next, the processing performed by the mammography apparatus 1 according to this modified example will be described with reference to Fig. 8. Since much of the processing performed by the mammography apparatus 1 according to this modified example is the same as in the second embodiment, only the parts that differ from the second embodiment will be described.

[0099] In this modification, in step S14, the imaging control function 211 moves the X-ray detector 106 in the opposite direction to the movement direction of the X-ray tube 102 at substantially the same speed as the movement speed of the X-ray tube 102, instead of slowing down the movement speed of the X-ray tube 102. Also, in step S17, the imaging control function 211 returns the X-ray detector 106 to the position it was in before the start of two-dimensional imaging. Other processing is the same as in the second embodiment.

[0100] According to this modification, blurring of a two-dimensional image can be prevented without stopping the X-ray tube 102 during two-dimensional imaging.

[0101] (Variation 2) In the above-described first and second embodiments, a configuration in which a two-dimensional image is directly acquired by two-dimensional imaging has been described. However, the method of acquiring a two-dimensional image is not limited to this, and for example, a configuration in which a two-dimensional image is acquired based on the imaging result of two-dimensional imaging and an image after image reconstruction processing by the reconstruction function 215 may be adopted. A configuration for realizing this configuration will be described below.

[0102] 10 is a block diagram showing an example of the configuration of a mammography apparatus 1 according to Modification 2. The mammography apparatus 1 according to this modification further includes a synthesis function 216. The synthesis function 216 generates a second synthesized two-dimensional image based on two-dimensional images captured by two-dimensional imaging and a first synthesized two-dimensional image generated based on images reconstructed by the reconstruction function 215.

[0103] Specifically, the synthesis function 216 generates a first synthesized two-dimensional image based on the multiple tomographic images generated by the image reconstruction process by the reconstruction function 215. Next, the synthesis function 216 synthesizes the two-dimensional image generated by the generation function 214 with the first synthesized two-dimensional image to generate a second synthesized two-dimensional image.

[0104] More specifically, the synthesis function 216 weights and adds a first synthesized two-dimensional image to the two-dimensional image generated by the generation function 214 based on the dose of the two-dimensional image, to generate a second synthesized two-dimensional image.

[0105] According to this modified example, even if the dose during two-dimensional imaging is insufficient, a high-quality two-dimensional image can be obtained by combining the two-dimensional image obtained by two-dimensional imaging with a first composite two-dimensional image synthesized based on a tomosynthesis image.

[0106] (Variation 3) In the above-described first and second embodiments, a configuration has been described in which two-dimensional imaging and tomosynthesis imaging are performed while one X-ray tube 102 is moving. However, for example, a configuration in which two-dimensional imaging and tomosynthesis imaging are performed using multiple X-ray tubes may also be used. A configuration for realizing this configuration will be described below.

[0107] 11 is a diagram showing an example of the configuration of a mammography apparatus 1 according to Modification 3. The mammography apparatus 1 of this modification includes an X-ray irradiation unit 112. The X-ray irradiation unit 112 includes multiple compact X-ray tubes 113, multiple compact X-ray apertures 114, and a housing 115.

[0108] The compact X-ray tubes 113 (113a to 113k) and the compact X-ray apertures 114 (114a to 114k) are housed in a housing 115. The X-ray irradiator 112 is configured to be able to selectively irradiate X-rays from each of the multiple compact X-ray tubes 113 toward the breast B under the control of the imaging control function 211.

[0109] 11, for the sake of convenience of explanation, the number of the multiple miniature X-ray tubes 113 and the multiple miniature X-ray apertures 114 is 11, but the number of the multiple miniature X-ray tubes 113 and the multiple miniature X-ray apertures 114 is not limited to 11. Also, in FIG. 11, the multiple miniature X-ray tubes 113 and the multiple miniature X-ray apertures 114 are arranged in a straight line, but they may also be arranged in a curved line.

[0110] For example, consider a case where the imaging control function 211 sets an imaging range (for example, -15° to +15°). In this case, the imaging control function 211 performs tomosynthesis imaging with an irradiation angle of -15° using the small X-ray tube 113a, an irradiation angle of -12° using the small X-ray tube 113b, an irradiation angle of -9° using the small X-ray tube 113c, an irradiation angle of -6° using the small X-ray tube 113d, and an irradiation angle of -3° using the small X-ray tube 113e.

[0111] After completing tomosynthesis imaging at an irradiation angle of -3°, the imaging control function 211 performs 2D imaging (irradiation angle 0°) with the compact X-ray tube 113f. After completing 2D imaging, the imaging control function 211 performs tomosynthesis imaging at an irradiation angle of +3° with the compact X-ray tube 113g, an irradiation angle of +6° with the compact X-ray tube 113h, an irradiation angle of +9° with the compact X-ray tube 113i, an irradiation angle of +12° with the compact X-ray tube 113j, and an irradiation angle of +15° with the compact X-ray tube 113k.

[0112] In this modification, the focal position of each miniature X-ray tube 113 is adjusted so that X-rays can be emitted at the corresponding irradiation angle.

[0113] Furthermore, for example, the imaging control function 211 may be configured to perform tomosynthesis imaging at irradiation angles other than the above-mentioned irradiation angles by performing imaging while changing the focal position of each small X-ray tube 113. For example, the imaging control function 211 performs tomosynthesis imaging at irradiation angles of −14° and −13° by changing the focal point of the small X-ray tube 113a.

[0114] This modification can achieve the same effects as the above-described embodiment. Furthermore, this modification eliminates the need to move the X-ray tube, eliminating the need to control the angular velocity of the arm 107. Therefore, the mammography apparatus 1 according to this modification can capture blur-free two-dimensional images without special control such as adjusting the angular velocity of the arm 107 and the imaging time.

[0115] (Variation 4) In the above-described embodiment and modified example, the X-ray diagnostic apparatus is a mammography apparatus. However, the X-ray diagnostic apparatus is not limited to a mammography apparatus. For example, the X-ray diagnostic apparatus may be an X-ray imaging apparatus capable of tomosynthesis imaging.

[0116] In the mammography device 1 described in each embodiment, each processing function is stored in a storage circuit in the form of a program executable by a computer. The processing circuit is a processor that realizes the function corresponding to each program by reading and executing the program from the storage circuit. In other words, once a program has been read, the processing circuit has the function corresponding to the read program.

[0117] In the above-described embodiments, each processing function is realized by a single processing circuit, but the embodiments are not limited to this. For example, the processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Furthermore, each processing function of the processing circuit may be realized by being appropriately distributed or integrated into a single or multiple processing circuits.

[0118] The term "processor" used in the above description refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). The processor realizes its functions by reading and executing programs stored in storage 111.

[0119] In the above-described embodiments, the storage circuitry has been described as storing programs corresponding to each processing function. However, a configuration may be adopted in which multiple storage circuits are distributed and the processing circuitry reads corresponding programs from individual storage circuits. Furthermore, instead of storing programs in storage circuits, the programs may be directly embedded in the processor circuitry. In this case, the processor realizes the functions by reading and executing the programs embedded in the circuitry.

[0120] The components of each device according to the above-described embodiments are conceptual and functionally independent, and are not necessarily physically configured as shown in the drawings. In other words, the specific form of distribution and integration of each device is not limited to that shown in the drawings, and all or part of the devices can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc. Furthermore, all or any part of the processing functions performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0121] The control method described in the above-described embodiment can be realized by executing a prepared control program on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. This control program can also be recorded on a non-transitory computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and executed by being read from the recording medium by a computer.

[0122] According to at least one of the embodiments described above, it is possible to reduce the burden on the subject when performing both two-dimensional imaging and tomosynthesis imaging.

[0123] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0124] 1. Mammography equipment 10 Mammography Department 20 Console device 21 Processing circuit 211 Shooting control function 212 Detection function 213 Display Control Function 214 Generation function 215 Reconfiguration function 216 Synthesis Function

Claims

1. an X-ray tube that irradiates an object with X-rays; an X-ray detection unit that detects the X-rays irradiated from the X-ray tube; an imaging control unit that controls the X-ray tube to perform two-dimensional imaging at a specific irradiation angle within an imaging range that defines a range of irradiation angles of the X-rays to the subject, and to perform tomosynthesis imaging at irradiation angles other than the specific irradiation angle, and that continuously performs the tomosynthesis imaging and the two-dimensional imaging from one end of the imaging range to the other end; Equipped with the imaging control unit continuously performs the tomosynthesis imaging and the two-dimensional imaging while moving the X-ray tube from one end to the other end of the imaging range; When the X-ray tube reaches the specific irradiation angle, the relative moving speed of the X-ray tube with respect to the X-ray detection unit is changed to perform the two-dimensional imaging; When the X-ray tube reaches the specific irradiation angle, the moving speed of the X-ray tube is reduced; determining a moving speed of the X-ray tube and an imaging period so that a moving distance of a projected image of the X-rays transmitted through the subject on the X-ray detection unit is within a threshold value in the two-dimensional imaging; X-ray diagnostic equipment.

2. the imaging control unit controls the X-ray tube to be higher in the two-dimensional imaging than in the tomosynthesis imaging.

2. The X-ray diagnostic apparatus according to claim 1.

3. a reconstruction unit that performs image reconstruction using the two-dimensional image corrected based on a dose ratio between the tomosynthesis image obtained by the tomosynthesis imaging and the two-dimensional image obtained by the two-dimensional imaging, 3. The X-ray diagnostic apparatus according to claim 1 or 2.

4. a synthesis unit that synthesizes the two-dimensional image and a first synthesized two-dimensional image synthesized based on the tomographic image generated by the image reconstruction, and generates a second synthesized two-dimensional image.

4. The X-ray diagnostic apparatus according to claim 3.

5. the subject is a breast, Further provided is a mounting table on which the breast is placed.

5. An X-ray diagnostic apparatus according to claim 1.

6. 1. A control method for an X-ray diagnostic apparatus including an X-ray tube that irradiates an object with X-rays and an X-ray detection unit that detects the X-rays irradiated from the X-ray tube, comprising: an imaging control step of performing two-dimensional imaging at a specific irradiation angle within an imaging range that defines a range of irradiation angles of the X-rays to the subject, controlling the X-ray tube to perform tomosynthesis imaging at an irradiation angle other than the specific irradiation angle, and continuously performing the tomosynthesis imaging and the two-dimensional imaging from one end of the imaging range to the other end; Including, the imaging control step includes continuously performing the tomosynthesis imaging and the two-dimensional imaging while moving the X-ray tube from one end to the other end of the imaging range; When the X-ray tube reaches the specific irradiation angle, the relative moving speed of the X-ray tube with respect to the X-ray detection unit is changed to perform the two-dimensional imaging; When the X-ray tube reaches the specific irradiation angle, the moving speed of the X-ray tube is reduced; determining a moving speed of the X-ray tube and an imaging period so that a moving distance of a projected image of the X-rays transmitted through the subject on the X-ray detection unit is within a threshold value in the two-dimensional imaging; A method for controlling an X-ray diagnostic apparatus.

Images