Medical image processing apparatus, x-ray diagnostic apparatus, and medical image processing program

Abstract

To support observation of an object site in this specification and under a situation accompanied by pulsations.SOLUTION: A medical image diagnostic apparatus includes an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a plurality of X-ray images captured for a plurality of cardiac phases which are taken of a subject in at least two different directions. The calculation unit calculates a three-dimensional shape of an object site included in the plurality of X-ray images for each of the plurality of cardiac phases on the basis of the plurality of acquired X-ray images. The calculation unit calculates at least one of a change in the shape of the object site viewed from a plurality of X-ray irradiation directions and a change in the position of the object site viewed from a specific X-ray irradiation direction between the plurality of cardiac phases for each of the plurality of X-ray irradiation directions. The determination unit determines an X-ray irradiation direction in which the calculated change satisfies a condition of the plurality of irradiation directions.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A treatment called IVR (Interventional Radiology) that uses X-ray diagnostic equipment such as X-ray angiography equipment is widely used. IVR, which literally translates to "image-guided treatment" in Japanese, refers to inserting thin medical devices into blood vessels to diagnose and treat targeted diseases while viewing inside the body using medical imaging diagnostic equipment such as X-ray angiography equipment (hereinafter simply referred to as an angiography equipment), X-ray CT equipment, or ultrasound diagnostic equipment. Medical devices inserted into blood vessels include, for example, thin tubes called catheters, balloons or stents attached to the tip of catheters, and guidewires for guiding catheters to the areas within blood vessels to be diagnosed or treated.

[0003] In IVR using an angiography system, an X-ray tube and X-ray detector mounted on a C-arm are used to capture images of the subject (e.g., a patient) in real time. Then, while observing the X-ray fluoroscopic images obtained by this imaging, the doctor who performs the procedure manually advances a medical device such as a guidewire or catheter through the subject's blood vessels until it reaches the area to be diagnosed or treated (hereinafter referred to as the target area).

[0004] Identifying the shape and position of the target area is extremely important for doctors performing procedures, so the technician sets the working angle of the C-arm (i.e., the angle at which X-rays are emitted onto the subject) so that the target area can be most easily observed.

[0005] However, when the target area is a cardiac blood vessel such as a coronary artery, the shape and position of the target area vary depending on the cardiac phase due to pulsation. For this reason, for example, an inexperienced operator may need time to determine the appropriate working angle of the C-arm for observing the target area. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-37037 Summary of the Invention [Problem to be solved by the invention]

[0007] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to support the observation of a target area even under conditions involving pulsation. 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 positioned as other problems. [Means for solving the problem]

[0008] According to one embodiment, a medical image diagnostic apparatus includes an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a plurality of X-ray images taken for a plurality of cardiac phases, the plurality of X-ray images being obtained by capturing a subject from at least two different directions. The calculation unit calculates, for each of the plurality of cardiac phases, a three-dimensional shape of a target region included in the plurality of X-ray images based on the acquired X-ray images. The calculation unit also calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases. The determination unit determines, from among the plurality of irradiation directions, an X-ray irradiation direction in which the calculated change satisfies a condition. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of the arrangement of an X-ray diagnostic apparatus according to a first embodiment. [Figure 2] 1 is a block diagram showing an example of the arrangement of various functions realized by a processing circuit in a medical image processing apparatus according to a first embodiment. [Figure 3] 4 is a flowchart showing an example of the operation of the medical image processing apparatus according to the first embodiment. [Figure 4] FIG. 1 is a first explanatory diagram of the operation concept of the medical image processing apparatus according to the first embodiment. [Figure 5] FIG. 2 is a second explanatory diagram of the operation concept of the medical image processing apparatus according to the first embodiment. [Figure 6] FIG. 3 is a third explanatory diagram of the operation concept of the medical image processing apparatus according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a display as support information for a user. [Figure 8] 10 is a flowchart showing an example of the operation of the medical image processing apparatus according to the second embodiment. [Figure 9] FIG. 10 is a first explanatory diagram of the operation concept of the medical image processing apparatus according to the second embodiment. [Figure 10] FIG. 10 is a second explanatory diagram of the operation concept of the medical image processing apparatus according to the second embodiment. [Figure 11] 10 is a flowchart showing an example of the operation of the medical image processing apparatus according to the third embodiment. [Figure 12] FIG. 11 is a first explanatory diagram of the operation concept of the medical image processing apparatus according to the third embodiment. [Figure 13] FIG. 20 is a second explanatory diagram of the operation concept of the medical image processing apparatus according to the third embodiment. [Figure 14] FIG. 10 is a block diagram showing an example of the arrangement of various functions realized by a processing circuit in a medical image processing apparatus according to a fourth embodiment. [Figure 15] 10 is a flowchart showing an example of the operation of the medical image processing apparatus according to the fourth embodiment. [Figure 16] FIG. 10 is a first explanatory diagram of the operation concept of the medical image processing apparatus according to the fourth embodiment. [Figure 17]FIG. 20 is a second explanatory diagram of the operation concept of the medical image processing apparatus according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The medical image processing apparatus, the X-ray diagnostic apparatus, and the medical image processing program according to the embodiments will be described below with reference to the drawings. In each drawing, the same elements are given the same reference numerals, and redundant description will be omitted.

[0011] (First embodiment) 1 is a diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. The X-ray diagnostic apparatus 1 is configured to include a medical image processing apparatus 10 and an apparatus main body 20.

[0012] The device main body 20 includes an X-ray imaging system, and includes, for example, a gantry device 2, a bed 3, a controller 4, and an image generation circuit 5. The device main body 20 is installed, for example, in a procedure room where examinations and treatments are performed. Of the device main body 20, the image generation circuit 5 may be installed in a control room adjacent to the procedure room together with the medical image processing device 10 described below.

[0013] The gantry device 2 includes an X-ray irradiation device 21, an X-ray detection device 22, a C-arm driving mechanism 23, and a C-arm 24.

[0014] The X-ray irradiator 21 is provided at one end of the C-arm 24. The X-ray irradiator 21 is provided so as to be movable back and forth under the control of the controller 4. The X-ray irradiator 21 has an X-ray source (e.g., an X-ray tube) and a movable diaphragm device. The X-ray tube receives high-voltage power from a high-voltage generator and generates X-rays according to the conditions of the high-voltage power. The movable diaphragm device movably supports diaphragm blades made of an X-ray blocking material at the X-ray irradiation port of the X-ray tube. A radiation quality adjustment filter for adjusting the radiation quality of the X-rays generated by the X-ray tube may be provided in front of the X-ray tube.

[0015] The X-ray detection device 22 is provided at the other end of the C-arm 24, facing the X-ray irradiation device 21. The X-ray detection device 22 is provided so as to be movable back and forth under the control of the controller 4. The X-ray detection device 22 includes an FPD (Flat Panel Detector) 221 and an ADC (Analog to Digital Converter) 222.

[0016] The FPD 221 has a plurality of detecting elements arranged two-dimensionally. The detecting elements of the FPD 221 are arranged so that the scanning lines and signal lines intersect at right angles. A grid may be provided on the front surface of the FPD 221. The grid is made of grid plates made of lead or other material with high X-ray absorption and aluminum or wood or other material with high X-ray transmittance, arranged alternately, to absorb scattered rays incident on the FPD 221 and improve the contrast of the X-ray image.

[0017] The ADC 222 converts the projection data of the time-series analog signal (video signal) output from the FPD 221 into a digital signal, and outputs the digital signal to the image generating circuit 5.

[0018] The C-arm 24 positions the X-ray irradiator 21 and the X-ray detector 22 facing each other with the subject at the center. Under the control of the controller 4, the C-arm 24 moves the X-ray irradiator 21 and the X-ray detector 22 as a unit in an arc direction of the C-arm 24 by the C-arm drive mechanism 23. Note that, although a configuration in which the device main body 20 is provided with the C-arm 24 and the C-arm 24 operates the X-ray irradiator 21 and the X-ray detector 22 as a unit will be described as an example, this configuration is not limiting. For example, the device main body 20 may not be provided with the C-arm 24, and the X-ray irradiator 21 and the X-ray detector 22 may operate independently.

[0019] FIG. 1 shows an example of the configuration of a single-plane type X-ray diagnostic apparatus 1 having only one C-arm 24, but the X-ray diagnostic apparatus 1 may also be a bi-plane type X-ray diagnostic apparatus 1 that uses two arms to enable fluoroscopy from two directions simultaneously.

[0020] The bed 3 is supported on the floor surface and supports a top plate (catheter table) 31. The bed 3 can slide (in the X- and Z-axis directions), move up and down (in the Y-axis direction), and roll the top plate 31 under the control of the controller 4. Note that the gantry device 2 will be described as an under-tube type in which the X-ray irradiator 21 is located below the top plate 31, but the gantry device 2 may also be an over-tube type in which the X-ray irradiator 21 is located above the top plate 31.

[0021] The controller 4 includes a CPU (Central Processing unit) and a memory (not shown). For alignment purposes, the controller 4 controls the driving of the X-ray irradiator 21, the X-ray detector 22, and the C-arm 24 of the gantry 2, as well as the driving of the bed 3, under the control of the image generating circuit 5. The controller 4 also controls the operations of the X-ray irradiator 21, the X-ray detector 22, the C-arm driving mechanism 23, etc., for surgical X-ray photography and X-ray fluoroscopy under the control of the image generating circuit 5.

[0022] The image generating circuit 5 is configured based on a computer and generates an X-ray image of the subject based on the digital signal acquired by the gantry device 2. The image generating circuit 5 generates a moving X-ray fluoroscopic image (hereinafter simply referred to as a fluoroscopic image) from an X-ray detection signal of the subject acquired in real time during an IVR procedure using a medical device 60 such as a catheter. The image generating circuit 5 can also generate a still X-ray image.

[0023] In this specification, a thin medical instrument that is inserted into tubular tissue such as a blood vessel to diagnose or treat a subject is referred to as a medical device 60. Medical devices that are inserted into blood vessels include the thin tube called a catheter mentioned above, as well as a balloon or stent attached to the tip of a catheter, and a guidewire for guiding the catheter to a site to be diagnosed or treated within the blood vessel.

[0024] 1 also illustrates a device operation unit 61 that controls the advancement of the medical device 60 in addition to the medical device 60. The device operation unit 61 is an instrument that allows a doctor or other technician to insert the medical device 60, such as a guidewire or a catheter, into a blood vessel and manually control the advancement of the medical device 60 to a predetermined target site.

[0025] The medical image processing apparatus 10 is a device configured to be connectable to an apparatus main body 20, and is configured as a computer such as a workstation or a personal computer. The medical image processing apparatus 10 includes a display 101, a processing circuitry 102, a memory circuitry 103, an input interface 104, and a network interface 105.

[0026] The display 101 is, for example, a large display device that is placed in a position that is easily visible to the operator during surgery. The display 101 displays not only the X-ray fluoroscopic image generated by the image generation circuitry 5, but also user support information such as various data and images for supporting the procedure that are generated by the processing circuitry 102. This user support information will be described later.

[0027] The processing circuitry 102 has a dedicated or general-purpose processor, and realizes various functions described below through software processing by executing programs stored in the storage circuitry 103. The processing circuitry 102 may be configured with hardware such as an ASIC (Application Specific Integration Circuit) or a programmable logic device such as an FPGA (Field Programmable Gate Array). The various functions described below can also be realized through hardware processing using these devices. Furthermore, the processing circuitry 102 may realize various functions described below by combining software processing and hardware processing.

[0028] The input interface 104 includes an input device that can be operated by an operator and an input circuit that inputs signals from the input device. The input device can be realized by a mouse, keyboard, trackball, switch, button, joystick, touchpad that performs input operations by touching the operation surface, touchscreen that combines the display screen and touchpad, non-contact input circuit using an optical sensor, voice input circuit, etc. When the input device receives an input operation from the operator, the input circuit generates an electrical signal corresponding to the input operation and outputs it to the processing circuit 102.

[0029] The input interface 104 includes a circuit for connecting a portable memory such as a USB memory, a memory card, a magnetic disk, or an optical disk, and inputting data recorded in the portable memory.

[0030] The network interface 105 is a circuit for connecting to various networks such as a hospital network or the Internet via wired or wireless means.

[0031] The storage circuitry 103 is configured by, for example, semiconductor memory elements such as RAM (Random Access Memory) and flash memory, a hard disk, an optical disk, etc. The storage circuitry 103 stores various processing programs (including application programs and OS (Operating System) etc.) used in the processing circuitry 102 and data required for executing the programs. The storage circuitry 103 can also store various data such as image data input via the input interface 104 and the network interface 105.

[0032] FIG. 1 also shows an electrocardiograph 70 that can be connected to the X-ray diagnostic apparatus 1.

[0033] FIG. 2 is a block diagram showing an example of the configuration of various functions realized by the processing circuitry 102 of the medical image processing apparatus 10 according to the first embodiment.

[0034] The processing circuitry 102 realizes an acquisition function F01, a calculation function F02, a display control function F03, and a determination function F04.

[0035] The acquisition function F01 acquires a plurality of X-ray images (e.g., fluoroscopic images) taken for a plurality of cardiac phases, the X-ray images being taken of a subject from at least two different directions. The acquisition function F01 acquires the plurality of X-ray images in association with the respective angles of the C-arm corresponding to the X-ray irradiation direction when the X-ray images are taken (i.e., the respective working angles of the C-arm).

[0036] The acquisition function F01 may acquire the plurality of X-ray images captured by ECG gating in association with each of a plurality of cardiac phases. Alternatively, the acquisition function F01 may acquire a plurality of X-ray images corresponding to a plurality of different cardiac phases over a period of one cardiac cycle or more without relying on ECG gating.

[0037] The calculation function F02 calculates the three-dimensional shape of the target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of X-ray images acquired by the acquisition function F01. The calculation function F02 also calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in the shape of the target region as viewed from multiple X-ray irradiation directions and a change in the position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases.

[0038] The determination function F04 determines, from among the multiple irradiation directions, an X-ray irradiation direction in which the calculated change satisfies a condition. For example, the determination function F04 determines a specific X-ray irradiation direction from the three-dimensional shape calculated for the multiple cardiac phases so that the change in the shape (e.g., length) and position of the target area as seen from the X-ray irradiation direction is small between the multiple cardiac phases.

[0039] Furthermore, the determination function F04 determines the above-mentioned specific irradiation direction as the working angle of the C-arm that holds the X-ray tube that irradiates X-rays so that the irradiation direction can be changed.

[0040] The display control function F03 generates virtual projection images for each of a plurality of cardiac phases, which are obtained when the target region is virtually irradiated with X-rays from the X-ray irradiation direction determined by the determination function F04, and displays a composite image obtained by combining the virtual projection images for each of the plurality of cardiac phases on the display 101. The determined specific X-ray irradiation direction is displayed on the display 101, and changes in the shape and position of the target region are displayed on the display 101 in association with the plurality of cardiac phases and the X-ray irradiation direction.

[0041] Hereinafter, more specific operations of the medical image processing apparatus 10 according to the first to third embodiments will be described with reference to FIGS.

[0042] FIG. 3 is a flowchart showing an example of the operation of the medical image processing apparatus 10 according to the first embodiment, and FIGS. 4 to 7 are explanatory diagrams of the operation concept of the medical image processing apparatus 10 according to the first embodiment.

[0043] In step ST10 of Fig. 3, a contrast medium is injected into a blood vessel. The processing of step ST10 may be performed under the control of the medical image processing apparatus 10 or the apparatus main body 20, or may be performed manually by a user.

[0044] In step ST11, multiple fluoroscopic images (i.e., fluoroscopic images depicting contrast blood vessels) taken from a first irradiation direction (e.g., irradiation direction A in FIG. 4) and a second irradiation direction (e.g., irradiation direction B in FIG. 4) for multiple cardiac phases are acquired from the device main body 20.

[0045] 4A and 4B are diagrams illustrating the concept of generating the fluoroscopic images acquired in step ST11. Fig. 4A is a diagram showing the timing at which fluoroscopic images are generated at multiple cardiac phases (e.g., cardiac phase cp1, cardiac phase cp2, cardiac phase cp3, ..., cardiac phase cpN) with dashed lines on the waveform of an ECG (Electrocardiogram) signal.

[0046] FIG. 4(b) shows how fluoroscopic images are generated by fluoroscopy of the heart, which is an organ to be imaged in a subject, using X-rays from two different irradiation directions (irradiation direction A and irradiation direction B). In each of irradiation direction A and irradiation direction B, fluoroscopic images are generated for multiple cardiac phases (e.g., cardiac phase cp1, cardiac phase cp2, cardiac phase cp3, ..., cardiac phase cpN). While an example with two irradiation directions will be described below, three or more irradiation directions may also be used, in which case fluoroscopic images for multiple cardiac phases are generated for each of the three or more irradiation directions.

[0047] The above-mentioned multiple fluoroscopic images are generated, for example, by the image generating circuit 5 of the device main body 20. In step ST11, the multiple fluoroscopic images generated in this manner are acquired from the device main body 20 by the acquisition function F01 of the medical image processing device 10.

[0048] In step ST12, information about the target region is acquired. The method for identifying the target region is not particularly limited. For example, the target region may be identified by specifying one of the numbers #1 to #15 (classification numbers established by the American Heart Association (AHA)) assigned to coronary arteries, such as the #2 portion of the right coronary artery (RCA). Alternatively, the target region may be identified by a user specifying the start and end points of the target blood vessel depicted on the fluoroscopic image using a user interface such as a pointer. Alternatively, the target region may be identified by the medical image processing apparatus 10 automatically detecting the position of a marker depicted on the fluoroscopic image or a stenotic portion of the blood vessel.

[0049] In step ST13, the three-dimensional shape of the target region is calculated by modeling the shapes of blood vessels contained in the fluoroscopic images. Fig. 5 is a diagram showing the processing concept of step ST13. The left side of Fig. 5 is the same as the right side of Fig. 4, and shows fluoroscopic images of irradiation directions A and B corresponding to multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN) acquired in step ST11.

[0050] In step ST13, the three-dimensional shape of the blood vessels is calculated from these fluoroscopic images for each of the multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN) as shown in the center of FIG. 5. For two fluoroscopic images taken from two directions, irradiation direction A and irradiation direction B, at the same cardiac phase (e.g., cardiac phase cp1), the three-dimensional shape of the blood vessels at cardiac phase cp1 is calculated using a technique such as stereo matching. By performing this process for other cardiac phases, the three-dimensional shape of the blood vessels can be calculated for each of the multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN).

[0051] Furthermore, in step ST13, the target region is extracted from the 3D shape calculated based on the information about the target region acquired in step ST12. Then, the 3D shape of the extracted target region is modeled for each cardiac phase. Through this processing, the 3D shape of the target region of the blood vessels included in the fluoroscopic image is calculated for each cardiac phase. The right side of FIG. 5 shows the calculated (i.e., modeled) 3D shapes of the target region for each of multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN). The processing of step ST13 is performed by the calculation function F02 of the processing circuitry 102.

[0052] In step ST14, the specific irradiation direction is determined based on the X-ray irradiation direction whose calculated change satisfies the condition among the multiple irradiation directions. Here, methods for determining the specific irradiation direction based on the X-ray irradiation direction whose calculated change satisfies the condition include, for example, determining the X-ray irradiation direction whose calculated change is the smallest as the specific irradiation direction, or determining the irradiation direction selected by the user from among the irradiation directions whose calculated change is smaller than a threshold as the specific irradiation direction. Preferably, the specific irradiation direction is determined based on the three-dimensional shape of the blood vessels of the modeled target region so that the change in the shape and position of the target region as viewed from the X-ray irradiation direction between multiple cardiac phases is minimized. Figure 6 shows an example of determining the specific irradiation direction as the irradiation direction whose change in the shape and position of the target region as viewed from the X-ray irradiation direction is the smallest among multiple cardiac phases.

[0053] FIG. 6 is a diagram showing the processing concept of step ST14. The left side of FIG. 6 is a diagram showing the 3D shape of the target region for multiple cardiac phases, which is the processing result of step ST13. In step ST14, the 3D shape of the target region for each cardiac phase is projected at multiple irradiation angles, and the 2D shape and position of the projected target region for each irradiation angle (i.e., for each projection angle) are compared between the multiple cardiac phases. The multiple irradiation angles here do not refer to the irradiation angles at which X-rays are actually irradiated, but rather to projection angles that are calculated and virtually set in multiple arbitrary directions by the determination function F04 of the processing circuitry 102 to determine a specific irradiation angle.

[0054] In the example shown in Figure 6, the three-dimensional shape of the target area is projected from the M direction from irradiation angle (1) to irradiation angle (M), and the shape and position of the target area at the projected multiple cardiac phases (cardiac phases cp1, cp2, cp3, ..., cpN) are compared for each irradiation angle.

[0055] In this example, from irradiation angle (1) to irradiation angle (4), the shape of the target area (a roughly vertically elongated rod shape) seen from each irradiation angle hardly changes between multiple cardiac phases, but the change in each position of the target area is greatest at irradiation angle (1) and smallest at irradiation angle (4).

[0056] On the other hand, when comparing irradiation angle (4) and irradiation angle (5), the shape (e.g., length of the target region) and position of the target region change little between multiple cardiac phases at irradiation angle (4), but the shape (e.g., length of the target region) changes significantly at irradiation angle (5).Furthermore, at irradiation angle (M), both the shape (e.g., length of the target region) and position of the target region change significantly between multiple cardiac phases.

[0057] In the example shown in FIG. 6, the determination function F04 determines the irradiation direction (4) that has the least change in the shape and position of the target region between the multiple phases as the specific irradiation direction.

[0058] 3, in step ST15, the determined specific irradiation direction is displayed on the display 101 so as to be presentable to the user. Furthermore, as shown in step ST16, changes in the shape and position of the target region may be displayed on the display 101 in association with a plurality of cardiac phases and a plurality of irradiation directions.

[0059] FIG. 7 is a diagram showing an example of display on the display 101 as support information for the user. The display 101 displays substantially the same content as the explanatory diagram of the operational concept in FIG. 6 . As shown in FIG. 7 , in steps ST15 and ST16, the display control function F03 may generate, for each of multiple cardiac phases, virtual projection images of a target region virtually irradiated with X-rays for each of multiple irradiation directions, and display a composite image by combining the virtual projection images for each of the multiple cardiac phases. In this case, the user may select a desired composite image from the multiple composite images (see FIG. 7 ) displayed on the display 101 via the input interface 104. In this case, the determination function F04 may determine, in step ST17, the irradiation direction corresponding to the composite image selected by the user as a specific irradiation direction, and cause the apparatus main body 20 to irradiate the subject with X-rays based on this specific irradiation direction. In this way, it is possible to present to the user, as a recommended C-arm working angle, an irradiation angle that minimizes changes in the shape and position of the target region between multiple cardiac phases. As a result, even in a situation where pulsation occurs, the user can easily determine an appropriate working angle of the C-arm for observing the target region. The processing of steps ST15 and ST16 is performed by the display control function F03 of the processing circuitry 102.

[0060] Based on such support information displayed on the display 101, the user decides whether or not to accept the recommended specific irradiation angle.

[0061] In step ST17, the appropriate working angle of the C-arm corresponding to the specific irradiation direction approved by the user is output from the medical image processing device 10 to the device main body 20. The device main body 20 then sets the working angle of the C-arm according to the output value of the appropriate working angle and performs X-ray fluoroscopy on the subject.

[0062] (Second embodiment) Fig. 8 is a flowchart showing an example of the operation of the medical image processing apparatus 10 according to the second embodiment, and Fig. 9 and Fig. 10 are explanatory diagrams of the operation concept of the medical image processing apparatus 10 according to the second embodiment. The configurations of the medical image processing apparatus 10 and the apparatus main body 20 according to the second embodiment are the same as those in Figs. 1 and 2.

[0063] In the first embodiment, the three-dimensional shape of a target region is calculated from a fluoroscopic image in which the blood vessel itself is visualized by fluoroscopic imaging using a contrast agent. In contrast, in the second embodiment, the three-dimensional shape of a target region is calculated by detecting markers attached to a medical device. Medical devices such as stents and balloons have X-ray-opaque markers attached to at least two positions on their front and rear ends. Because medical devices such as stents and balloons are ultimately moved to the target region to be examined or treated, the three-dimensional shape of the target region can be calculated by detecting the positions of at least two markers from the fluoroscopic image. In other words, even in a situation where the blood vessel itself is not visualized in the fluoroscopic image because a contrast agent is not injected, the three-dimensional shape of the target region can be calculated by detecting the positions of the markers attached to the medical device such as a stent or balloon.

[0064] 8, a medical device equipped with a marker is inserted into a subject. Next, in step ST21, a plurality of fluoroscopic images (fluoroscopic images depicting the marker) captured from the first and second irradiation directions (irradiation direction A and irradiation direction B) for a plurality of cardiac phases are acquired from the device main body 20. The method for generating a plurality of fluoroscopic images in the device main body 20 is the same as that of the first embodiment described with reference to FIG.

[0065] In step ST22, information about the target site is acquired. The process in step ST22 is also similar to that in step ST12 in the first embodiment.

[0066] In step ST23, the three-dimensional shape of the target region is calculated based on the three-dimensional positions of at least two markers included in the perspective image. Fig. 9 is a diagram illustrating the operational concept of the processing in step ST23.

[0067] 5, the left side of Fig. 9 shows fluoroscopic images of irradiation directions A and B corresponding to multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN) acquired in step ST21. However, in the second embodiment, these fluoroscopic images depict markers rather than blood vessels themselves.

[0068] In step ST23, the three-dimensional positions of the markers are calculated from these fluoroscopic images for each of the multiple cardiac phases (cardiac phases cp1, cp2, cp3, ..., cpN) as shown in the center of Figure 9, and the three-dimensional shape of the blood vessel near where the medical device is inserted is calculated using a technique such as stereo matching, as in the first embodiment.

[0069] Furthermore, in step ST23, based on the information about the target site acquired in step ST22, the three-dimensional shape of the blood vessels near where the medical device is inserted is extracted as the three-dimensional shape of the target site. Through this processing, the three-dimensional shape of the target site of the blood vessels included in the fluoroscopic image is calculated for each cardiac phase. The right side of FIG. 9 shows the calculated three-dimensional shapes of the target site for each of multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN). In the second embodiment, the three-dimensional shape of the target site is estimated based on the positional relationship between the two markers. The processing of step ST23 is also performed by the calculation function F02 of the processing circuitry 102, as in the first embodiment.

[0070] In the next step ST24, a specific irradiation direction is determined from the three-dimensional shape so that there is little change in the shape and position of the target region as viewed from the X-ray irradiation direction between multiple cardiac phases.

[0071] 10 is a diagram showing the processing concept of step ST24. In step ST14 in the first embodiment, as explained using FIG. 6, a specific irradiation direction is determined based on the three-dimensional shape of the target region in the blood vessels depicted by contrast imaging. In contrast, in step ST24 in the second embodiment, a specific irradiation direction is determined based on the three-dimensional shape of the target region estimated from the positional relationship between two markers depicted in a fluoroscopic image. Although the first embodiment and the second embodiment use different methods for calculating the three-dimensional shape of the target region, the method for determining a specific irradiation direction using the calculated three-dimensional shape is the same. Therefore, a description of the method for determining a specific irradiation direction in the second embodiment will be omitted.

[0072] Furthermore, the processes from step ST15 to step ST17 in FIG. 9 are also the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0073] (Third embodiment) Fig. 11 is a flowchart showing an example of the operation of the medical image processing apparatus 10 according to the third embodiment, and Fig. 12 and Fig. 13 are explanatory diagrams of the operation concept of the medical image processing apparatus 10 according to the third embodiment. The configurations of the medical image processing apparatus 10 and the apparatus main body 20 according to the third embodiment are the same as those in Figs. 1 and 2.

[0074] In the first embodiment, the three-dimensional shape of the target region is calculated from a fluoroscopic image in which the blood vessels themselves are depicted by fluoroscopic imaging using a contrast agent, while in the second embodiment, the three-dimensional shape of the target region is calculated by detecting at least two markers attached to a medical device.

[0075] In contrast, in the third embodiment, the three-dimensional shape of the target region is calculated based on three-dimensional information about the movement path of a radiopaque portion provided at the tip of the guidewire. In the second embodiment, the three-dimensional shape of the target region can be calculated based on the positional relationship of at least two markers provided on the medical device. On the other hand, since the number of radiopaque portions provided at the tip of the guidewire is usually one, it is difficult to calculate the three-dimensional shape of the target region using only the positional information of the radiopaque portion itself. Therefore, in the third embodiment, the positions of the radiopaque portions are recorded every moment, and the three-dimensional shape of the target region is calculated based on the three-dimensional information about the movement path of the radiopaque portions.

[0076] In step ST30 of FIG. 11, a guide wire having a radiopaque portion at its tip is inserted into the subject.

[0077] In step ST31, a plurality of fluoroscopic images (fluoroscopic images depicting the X-ray opaque portion of the tip of the guidewire) taken from the first and second irradiation directions (irradiation direction A and irradiation direction B) for a plurality of cardiac phases are acquired from the device main body 20 from time to time. The processing of step ST31 is performed by the acquisition function F01 of the processing circuitry 102. The method of generating a plurality of fluoroscopic images in the device main body 20 is the same as that of the first embodiment described with reference to FIG.

[0078] Furthermore, in step ST31, a movement path of the distal end of the guidewire is generated on the plurality of fluoroscopic images based on the moment-to-moment position information of the radiopaque portion advancing inside the blood vessel. The process of generating the movement path may be performed by the acquisition function F01 or the device main body 20.

[0079] In step ST32, information about the target site is acquired. The process in step ST32 is also similar to step ST12 in the first embodiment.

[0080] In step ST33, the three-dimensional shape of the target region is calculated based on three-dimensional information of the movement path of the radiopaque portion of the tip of the guide wire contained in the fluoroscopic image. Fig. 12 is a diagram illustrating the operational concept of the processing in step ST33.

[0081] 5 in the first embodiment, the left side of Fig. 12 shows fluoroscopic images of irradiation directions A and B corresponding to a plurality of cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN) acquired in step ST31. However, in the third embodiment, these fluoroscopic images depict not the blood vessel itself but the movement path of the radiopaque portion at the tip of the guidewire.

[0082] In step ST33, from these fluoroscopic images, the three-dimensional shape of the movement path of the guidewire tip is calculated for each of multiple cardiac phases (cardiac phases cp1, cp2, cp3, ..., cpN), as shown in the center of Figure 12, using a technique such as stereo matching, as in the first embodiment.

[0083] Furthermore, in step ST33, the three-dimensional shape of the target region is extracted from the three-dimensional shape of the movement path of the guidewire tip based on the information about the target region acquired in step ST32. Through this processing, the three-dimensional shape of the target region is calculated for each cardiac phase from the movement path included in the fluoroscopic image. The right side of FIG. 12 shows the calculated three-dimensional shape of the target region for each of multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN). In the third embodiment, the three-dimensional shape of the target region is estimated from the movement path of the radiopaque portion of the guidewire tip. The processing of step ST33 is also performed by the calculation function F02 of the processing circuitry 102, as in the first embodiment.

[0084] In the next step ST34, a specific irradiation direction is determined from the three-dimensional shape so that there is little change in the shape and position of the target region as viewed from the X-ray irradiation direction between multiple cardiac phases.

[0085] 13 is a diagram showing the processing concept of step ST34. In step ST34 in the third embodiment, a specific irradiation direction is determined based on the three-dimensional shape of the target region estimated from the movement path of the guidewire distal end. In the third embodiment, the method of determining a specific irradiation direction using the calculated three-dimensional shape (or estimated three-dimensional shape) is the same as in the first and second embodiments. Therefore, a description of the method of determining a specific irradiation direction in the third embodiment will be omitted.

[0086] Furthermore, the processes from step ST15 to step ST17 in FIG. 11 are also the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0087] (Fourth embodiment) 14 is a block diagram showing an example of the configuration of various functions realized by the processing circuitry 102 of the medical image processing apparatus 10 according to the fourth embodiment. The medical image processing apparatus 10 of the fourth embodiment differs from the first to third embodiments in that it has an extraction function F05 instead of the calculation function F02. In addition, the function realized by the acquisition function F01 of the processing circuitry 102 differs from the first to third embodiments. Furthermore, the fourth embodiment differs from the first to third embodiments in that the acquisition function F01 of the processing circuitry 102 acquires three-dimensional images (e.g., X-ray CT images) from an external image server 80.

[0088] Depending on the condition of the subject (e.g., patient), blood vessels in the affected target region may be blocked or severely constricted, preventing the flow of contrast media or the passage of medical devices such as guidewires, stents, and balloons. In such cases, it is difficult to obtain the three-dimensional shape of the target region from fluoroscopic images captured by the device main body 20 connected to the medical image processing device 10, as in the first to third embodiments. Therefore, in the fourth embodiment, the three-dimensional shape of the target region is obtained from three-dimensional images, such as X-ray CT images or MRI images, captured in advance of the same patient.

[0089] FIG. 15 is a flowchart showing an example of the operation of the medical image processing apparatus 10 according to the fourth embodiment, and FIGS. 16 and 17 are explanatory diagrams of the operation concept of the medical image processing apparatus 10 according to the fourth embodiment.

[0090] In step ST40 of FIG. 15, for example, X-ray CT images are acquired as a plurality of three-dimensional images of the subject captured in advance for a plurality of cardiac phases.

[0091] In the next step ST41, the acquired three-dimensional image and the fluoroscopic image captured by the device main body 20 are aligned by known technology using information such as the angle of the C-arm when capturing the fluoroscopic image. In the next step ST42, information about the target site is acquired by the same method as in step ST12 of the first embodiment.

[0092] In the next step ST43, the three-dimensional shape of the target region is extracted from a plurality of three-dimensional images for a plurality of cardiac phases.

[0093] Fig. 16 is a diagram showing the operational concept from step ST40 to step ST43. The diagram on the left side of Fig. 16 shows, for example, X-ray CT images after alignment, which are multiple X-ray CT images of the heart of the same patient taken at multiple cardiac phases (cardiac phases cp1, cp2, cp3, . . . , cpN).

[0094] In step ST43, the target region is extracted from each of these multiple X-ray CT images to obtain the three-dimensional shape of the target region for multiple cardiac phases (cardiac phases cp1, cp2, cp3, ..., cpN) as shown on the right side of Figure 16.

[0095] In step ST44, a specific irradiation direction is determined from the three-dimensional shape so that changes in the shape and position of the target region viewed from the X-ray irradiation direction are minimized between multiple cardiac phases. FIG. 17 is a diagram illustrating the operational concept of step ST44. The processing of step ST44 is substantially the same as the processing of step ST14 in the first embodiment (see FIG. 3). FIG. 17 is also substantially the same as FIG. 6, which explains the processing of step ST14 in the first embodiment. Therefore, to avoid redundancy, the description of step ST44 and FIG. 17 will be omitted.

[0096] Steps ST15 and ST16 are the same as those in the first to third embodiments, and the determined specific irradiation direction is displayed on the display 101 so as to be presentable to the user. Furthermore, changes in the shape and position of the target area may be displayed on the display 101 in association with multiple cardiac phases and multiple irradiation directions.

[0097] Step ST17 is also the same as in the first to third embodiments, in which the appropriate working angle of the C-arm corresponding to the specific irradiation direction approved by the user is output from the medical image processing device 10 to the device main body 20. The device main body 20 then sets the working angle of the C-arm in accordance with the output value of the appropriate working angle, and performs X-ray fluoroscopy on the subject.

[0098] In addition, the acquisition function, calculation function, determination function, extraction function, and display control function in each embodiment described so far are examples of the acquisition unit, calculation unit, determination unit, extraction unit, and display control unit described in the claims, respectively.

[0099] As described above, according to the medical image processing device of each embodiment, it is possible to easily determine an appropriate working angle of the C-arm for observing a target region even under conditions involving pulsation.

[0100] Although several embodiments of the present invention 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, and modifications 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 described in the claims and their equivalents. [Explanation of symbols]

[0101] 1 X-ray diagnostic equipment 10 Medical image processing device 20 Device body 24 C-arm 101 Display 102 Processing circuit F01 Acquisition function F02 Calculation function F03 Display control function F04 Decision function F05 Extraction function

Claims

1. an acquisition unit that acquires a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being obtained by photographing a subject from at least two different directions; a calculation unit that calculates, for each of the plurality of cardiac phases, a three-dimensional shape of a target region included in the plurality of X-ray images based on the plurality of acquired X-ray images, and calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases; a determination unit that determines an X-ray irradiation direction in which the calculated change satisfies a condition from among the plurality of irradiation directions; A medical image processing device comprising:

2. a display control unit that generates, for each of the plurality of cardiac phases, a virtual projection image in the case where the target region is virtually irradiated with X-rays from the determined X-ray irradiation direction, and displays a composite image obtained by combining the virtual projection images for the plurality of cardiac phases; The medical image processing apparatus according to claim 1 , further comprising:

3. an acquisition unit that acquires a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being obtained by photographing a subject from at least two different directions; a calculation unit that calculates a three-dimensional shape of a target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of acquired X-ray images, a calculation unit that calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases; a display control unit that generates, for each of the plurality of cardiac phases, virtual projection images of the target region when virtually irradiated with X-rays in each of the plurality of irradiation directions, and displays a composite image obtained by combining the virtual projection images for each of the plurality of cardiac phases; A medical image processing device comprising:

4. a determination unit that causes an apparatus main body including an X-ray imaging system to irradiate an object with X-rays in an irradiation direction corresponding to a composite image selected by a user from among the composite images generated for each of the plurality of irradiation directions; The medical image processing apparatus according to claim 3 , further comprising:

5. the determination unit determines the specific irradiation direction as a working angle of a C-arm that holds an X-ray tube that irradiates the X-rays so as to change the irradiation direction. The medical image processing device according to claim 1 .

6. the acquiring unit acquires the plurality of X-ray images captured by electrocardiography synchronization in association with each of a plurality of cardiac phases. The medical image processing device according to claim 1 or 3.

7. each of the plurality of X-ray images is an X-ray image in which blood vessels are depicted by contrast photography; the calculation unit calculates the three-dimensional shape of the target region by modeling the shape of blood vessels included in the X-ray image; the determination unit determines the specific irradiation direction using a three-dimensional shape of the target portion of the blood vessel that has been modeled. The medical image processing device according to claim 1 or 3.

8. each of the plurality of X-ray images is an X-ray image depicting at least two markers attached to a medical device; the calculation unit calculates the three-dimensional shape of the target region based on the three-dimensional positions of the at least two markers; the determination unit determines the specific irradiation direction from the calculated three-dimensional shape so as to minimize changes in the shape and position of the target site as viewed from the irradiation direction of the X-rays. The medical image processing device according to claim 1 .

9. each of the plurality of X-ray images is an X-ray image depicting an X-ray opaque portion provided at a distal end portion of a guide wire; the calculation unit calculates the three-dimensional shape of the target region based on three-dimensional information of a movement path of the radiopaque portion; the determination unit determines the specific irradiation direction from the calculated three-dimensional shape so as to minimize changes in the shape and position of the target site as viewed from the irradiation direction of the X-rays. The medical image processing device according to claim 1 .

10. an acquisition unit that acquires a plurality of three-dimensional images of a subject, the three-dimensional images being captured in advance for a plurality of cardiac phases; an extracting unit that extracts a three-dimensional shape of a target region included in the three-dimensional images from each of the three-dimensional images for the plurality of cardiac phases; a determination unit that determines a specific irradiation direction of the X-rays from the three-dimensional shapes extracted for the plurality of cardiac phases so that changes in the shape and position of the target region as viewed from the irradiation direction of the X-rays are small between the plurality of cardiac phases; A medical image processing device comprising:

11. The change in the shape of the target site as viewed from the X-ray irradiation direction is a change in the length of the target site at an angle at which the three-dimensional shape of the target site is observed. The medical image processing device according to claim 10.

12. The three-dimensional image is an X-ray CT image. The medical image processing device according to claim 10.

13. The display and a display control unit that displays the determined specific irradiation direction of the X-rays on the display, and also displays changes in the shape and position of the target region on the display in association with the multiple cardiac phases and the irradiation direction of the X-rays; The medical image processing apparatus according to claim 1 , 3 or 10 , further comprising:

14. an X-ray tube that irradiates an X-ray toward a subject; an X-ray detector that detects X-rays that have passed through the subject; a C-arm that holds the X-ray tube and the X-ray detector so as to change the irradiation direction of the X-rays; an acquisition unit that acquires a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being obtained by taking images of a subject from at least two different directions using the C-arm; a calculation unit that calculates a three-dimensional shape of a target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of acquired X-ray images, a calculation unit that calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases; a determination unit that determines an X-ray irradiation direction in which the calculated change satisfies a condition among the plurality of irradiation directions; An X-ray diagnostic apparatus comprising:

15. an X-ray tube that irradiates an X-ray toward a subject; an X-ray detector that detects X-rays that have passed through the subject; a C-arm that holds the X-ray tube and the X-ray detector so as to change the irradiation direction of the X-rays; an acquisition unit that acquires a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being obtained by taking images of a subject from at least two different directions using the C-arm; a calculation unit that calculates a three-dimensional shape of a target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of acquired X-ray images, a calculation unit that calculates, for each of the plurality of X-ray irradiation directions, at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases; a display control unit that generates, for each of the plurality of cardiac phases, virtual projection images of the target region when virtually irradiated with X-rays in each of the plurality of irradiation directions, and displays a composite image obtained by combining the virtual projection images for each of the plurality of cardiac phases; A medical image processing device comprising:

16. an X-ray tube that irradiates an X-ray toward a subject; an X-ray detector that detects X-rays that have passed through the subject; a C-arm that holds the X-ray tube and the X-ray detector so as to change the irradiation direction of the X-rays; an acquisition unit that acquires a plurality of three-dimensional images of a subject, the three-dimensional images being captured in advance for a plurality of cardiac phases; an extracting unit that extracts a three-dimensional shape of a target region included in the three-dimensional images from each of the three-dimensional images for the plurality of cardiac phases; a determination unit that determines a specific irradiation direction of the X-rays from the three-dimensional shapes extracted for the plurality of cardiac phases so that changes in the shape and position of the target region as viewed from the irradiation direction of the X-rays are small between the plurality of cardiac phases; An X-ray diagnostic apparatus comprising:

17. acquiring a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being taken from at least two different directions of the subject; calculating a three-dimensional shape of a target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of acquired X-ray images; calculating at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases for each of the plurality of X-ray irradiation directions; determining an X-ray irradiation direction in which the calculated change satisfies a condition among the plurality of irradiation directions; A medical image processing program that allows a computer to execute the above.

18. acquiring a plurality of X-ray images taken for a plurality of cardiac phases, the X-ray images being taken from at least two different directions of the subject; calculating a three-dimensional shape of a target region included in the plurality of X-ray images for each of the plurality of cardiac phases based on the plurality of acquired X-ray images; calculating at least one of a change in shape of the target region as viewed from a plurality of X-ray irradiation directions and a change in position of the target region as viewed from a specific X-ray irradiation direction between the plurality of cardiac phases for each of the plurality of X-ray irradiation directions; generating, for each of the plurality of cardiac phases, virtual projection images of the target region virtually irradiated with X-rays in each of the plurality of irradiation directions, and displaying a composite image obtained by combining the virtual projection images for each of the plurality of cardiac phases; A medical image processing program that allows a computer to execute the above.

19. acquiring a plurality of pre-recorded 3D images of a subject, the pre-recorded 3D images being taken for a plurality of cardiac phases; extracting a three-dimensional shape of a target region included in the plurality of three-dimensional images from each of the plurality of three-dimensional images for the plurality of cardiac phases; determining a specific irradiation direction of the X-rays from the three-dimensional shapes extracted for the plurality of cardiac phases so that changes in the shape and position of the target region as viewed from the irradiation direction of the X-rays are small between the plurality of cardiac phases; A medical image processing program that allows a computer to execute the above.

Images