JP5595745B2 - X-ray fluoroscope - Google Patents

Description

  The present invention relates to an X-ray fluoroscopic apparatus that makes X-rays transparent (X-ray fluoroscopy) inside a subject, and an X-ray fluoroscopic image processing method that processes an image of a subject obtained by X-ray fluoroscopy. In particular, the present invention is intended to optimize surgery performed by inserting a cord-like insertion instrument into a subject under fluoroscopy.

  2. Description of the Related Art In recent years, surgery that is performed by inserting a cord-like insertion device composed of a thin cord-like member into the body due to advantages such as minimally invasiveness to a subject has been remarkably spread. Examples of the cord-like insertion instrument inserted into the body include an electrode catheter, an ablation catheter, a microcatheter, and a guide wire introduced together with the catheter. In this specification, a cord-like insertion instrument including these is hereinafter referred to as a “wire”. In general, since a wire absorbs X-rays more easily than a human body, it is observed as a black thin line on an X-ray image.

  An example of a surgery in which a wire is used is catheterization under fluoroscopy. Under fluoroscopic catheterization, a catheter is inserted into a body from an artery or the like of a thigh, and the treatment is performed by guiding the catheter to an affected part while referring to an X-ray fluoroscopic image displayed in real time. The surgeon must guide the catheter to the affected part through an appropriate route through the blood vessel stretched like a maze. The operation for this is performed by manipulating the portion of the catheter that is outside the body. Thus, skilled procedures are required for catheterization under fluoroscopy.

  When the catheter is to enter a desired branch at the branch point of the blood vessel or to pass through a stenosis site, the distal end portion of the catheter is first inserted into the course. Therefore, the surgeon performs extremely delicate operations such as appropriately combining operations such as advance, retreat, and twist. In addition, if the catheter is advanced in a state where the distal end portion is not properly inserted in the path, complications such as piercing the blood vessel may occur. In other words, the insertion operation of the distal end is very important in catheterization under fluoroscopy, but the degree of difficulty is also high.

  In view of such circumstances, a technique of providing a guide wire at the distal end portion of the catheter has been adopted. In the insertion operation of the distal end portion, the operator first inserts a guide wire into a target path, and then follows the guide wire to advance the entire catheter. The catheter is gradually advanced by repeating this operation. The guide wire is flexible and elastic. The distal end portion of the guide wire is strongly bent, and the distal end portion can be easily inserted into the target branch by a twisting operation. In addition, the guide wire has a structure with a high X-ray absorption coefficient, thereby improving the visibility under X-ray fluoroscopy. Specifically, the guide wire is depicted as a relatively clear black line in the fluoroscopic image.

  As described above, the guide wire can be easily recognized in the fluoroscopic image, but the branch or stenosis portion of the blood vessel cannot be recognized (the portion where the calcification has occurred may appear faint). Therefore, the position where the guide wire should be entered is confirmed by occasionally letting out the contrast medium from the catheter and observing the image of the contrast medium that appears for only a few seconds. However, the amount of contrast agent used is limited because it imposes a burden on the kidney function of the patient. Therefore, the surgeon performs the operation quickly while the contrast agent image is valid, or stores the position of the contrast agent image and performs the operation.

  Various techniques for improving the visibility of a wire in such a fluoroscopic catheterization are known. For example, Patent Literature 1 discloses a technique for detecting a black line (an image region corresponding to a wire) in an X-ray fluoroscopic image, enhancing the black line, and reducing noise in other parts. This technique is effective for observing an extremely thin black line having a thickness of about one pixel. In addition, this technique is intended to improve the visibility of the wire in each frame of the X-ray fluoroscopic image displayed as a moving image.

  In Patent Document 2, body movement of a subject is detected from image data, a region in a moving direction with low frequency is detected from the detection result of the body motion, and this detection region is included in the current fluoroscopic image. A technique for highlighting is disclosed. This technique attempts to detect the position of the wire using body movement.

JP 2001-283215 A JP 2006-255217 A

  By the way, in the operation using the wire, the image of the wire constantly moves in a complicated manner in the frame of the X-ray fluoroscopic image due to the local motion (heartbeat, breathing, etc.) or the global motion (body motion, etc.) of the subject. There was a problem. In order to perform such delicate operations as described above, it is necessary to clearly grasp the positional relationship between the blood vessels (particularly branches and stenosis) and the wire, but if the image moves like this, the positional relationship can be grasped. Will be difficult.

  To cope with this problem, conventionally, measures have been taken such as holding the patient's breath to make the movement of the image as small as possible. However, the movement of the image due to the heartbeat cannot be stopped. Furthermore, patients undergoing this surgery have cardiovascular disease and can often only hold their breath for a short time. If the wire could not be advanced during this time, the operation was interrupted, the patient was rested for a while, and the patient had to hold their breath again.

  Moreover, even if the entry target of the wire was confirmed using the contrast agent, it was easy to lose sight of the entry target due to the movement of the image. Furthermore, even if the position of the entry target is confirmed, the tip of the wire and the entry target can only be stored as a relative positional relationship. Therefore, the surgeon wanted to reconfirm the entry target each time the wire was advanced a little.

  Further, when inserting a wire into a desired branch, it is necessary to twist the bent portion of the tip of the wire toward the branch. However, the size of the bent portion is only a few millimeters at most, and it is difficult to confirm from the image of the moving wire whether the bent portion is twisted as intended. For this reason, the surgeon took this confirmation work over time.

  As described above, it is difficult and time-consuming to advance the wire while referring to the constantly moving image. For this reason, the time during which X-ray fluoroscopy is performed also becomes longer, and as a result, the exposure dose received by the patient and the operator has increased.

  The surgeon's fatigue was great because it was necessary to perform an operation for a long time while following the moving image with his eyes. As a result, there was a risk of a vicious circle in which the operation time would be longer.

  In addition, prolonged surgery increases the physical burden on the patient. In addition, for patients who are competing for a moment, lengthening the operation is a very serious problem. For example, if an acute patient with strong coronary artery spasm or occlusion is undergoing fluoroscopic catheterization to quickly expand the coronary artery and resume blood flow, the operation should be completed in as little time as possible. It is desirable to make it.

  As described above, the factor that increases the difficulty of catheterization under fluoroscopy and causes a long time is that the image of the wire constantly moves around due to heartbeat and respiration.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an image of a wire in an X-ray fluoroscopic image displayed as a moving image in real time in a surgery performed by inserting the wire into the body. It is to suppress the movement of.

In order to achieve the above-described object, the invention according to claim 1 is configured to transmit an X-ray irradiation means for irradiating an X-ray toward a subject in a state in which a cord-like insertion instrument is inserted, and transmits the subject. An X-ray fluoroscopic device that forms and displays a moving image depicting the inside of the subject based on a detection result by the X-ray detection unit, A specifying means for specifying an image of the insertion instrument in real time from a plurality of frames included in the moving image, a curved shape of the image of the insertion instrument in one of the frames of the moving image, and a frame in the past An alignment process for obtaining a degree of coincidence with the curved shape of the image of the insertion instrument and performing an alignment process between the one frame and the past frame in real time based on the obtained degree of coincidence. And means, by sequentially displaying the frames processed by the positioning process unit in real time, and display means for displaying the insertion instrument alignment moving image suppressing the movement of the image of the insertion instrument, a.
According to a third aspect of the present invention, an X-ray irradiating means for irradiating an X-ray toward a subject in a state in which a cord-like insertion instrument is inserted, and the X-ray transmitted through the subject are detected. And an X-ray fluoroscopic device that forms and displays a moving image depicting the inside of the subject based on a detection result of the X-ray detecting unit, the plurality of X-ray fluoroscopic devices included in the moving image A means for identifying the image of the insertion instrument in real time from the frame of the frame, and a degree of coincidence between the image of the insertion instrument in one of the frames of the moving image and the image of the insertion instrument in a frame from the past The registration processing means for performing the registration processing of the one frame and the past frame in real time, and sequentially processing the frames processed by the alignment processing means in real time. Display means for displaying an insertion instrument alignment moving image by indicating, the alignment processing means, for each frame other than the first two frames of the frames of a predetermined period of the moving image, Based on the result of the alignment with respect to two or more past frames and the result of the alignment between the frame and the latest frame of the two or more frames in the past, the frame and the Align with the first of two or more past frames.
The invention according to claim 5 detects an X-ray irradiation means for irradiating an X-ray toward a subject in a state where a cord-like insertion instrument is inserted, and detects the X-ray transmitted through the subject. And an X-ray fluoroscopic device that forms and displays a moving image depicting the inside of the subject based on a detection result of the X-ray detecting unit, the plurality of X-ray fluoroscopic devices included in the moving image A means for identifying the image of the insertion instrument in real time from the frame of the frame, and a degree of coincidence between the image of the insertion instrument in one of the frames of the moving image and the image of the insertion instrument in a frame from the past The registration processing means for performing the registration processing of the one frame and the past frame in real time, and sequentially processing the frames processed by the alignment processing means in real time. And display means for displaying an insertion instrument alignment moving image, the alignment processing means, together with the image of the insertion instrument of the one frame and the insertion instrument of the past frame. position of the bent portion of the insertion instrument in the image of the will row the positioning process so as to substantially coincide.

  According to the present invention, it is possible to display in real time a moving image in which the movement of the image of the insertion tool is suppressed with respect to the frame of the moving image. Since this moving image is a moving image obtained by performing alignment between frames based on the degree of coincidence of the image of the insertion instrument, the movement of the image of the insertion instrument relative to a normal fluoroscopic image is reduced. It is suppressed. Therefore, according to the present invention, it is possible to suppress the movement of the image of the insertion instrument due to the movement of the subject in the fluoroscopic image observed in real time in the catheterization under fluoroscopic fluoroscopy.

It is a figure showing the whole structure of 1st Embodiment of the X-ray fluoroscopy apparatus which concerns on this invention. It is a block diagram showing the structure of the control system of the X-ray fluoroscopic apparatus shown in FIG. It is a figure showing the flame | frame depicting the wire inserted in the body which the X-ray fluoroscope shown in FIG. 1 displays. It is a figure showing the outline | summary of the flame | frame shown in FIG. It is a figure showing the image of the wire extracted from the flame | frame shown in FIG. It is a figure showing the two-dimensional curve based on the image of the wire shown in FIG. It is a figure showing a part of image of the several wire obtained along a time series by the X-ray fluoroscopy apparatus shown in FIG. It is a figure showing the two-dimensional curve based on the image of the time series wire shown in FIG. It is a figure showing the two-dimensional curve based on the image of the wire in two frames shown in FIG. It is a figure showing the superposition state of two two-dimensional curves shown in FIG. It is a flowchart showing operation | movement of the X-ray fluoroscopy apparatus shown in FIG. It is a figure for demonstrating 2nd Embodiment of the X-ray fluoroscopic apparatus which concerns on this invention, and is a figure for demonstrating the state from which the image of a wire remove | deviates from a trim frame. It is a block diagram showing the structure of the control system of 2nd Embodiment of the X-ray fluoroscopic apparatus which concerns on this invention. It is a figure for demonstrating the trim frame determined by the X-ray fluoroscope shown in FIG. It is a flowchart showing operation | movement of the X-ray fluoroscope shown in FIG. It is a figure for demonstrating the modification of 2nd Embodiment of the X-ray fluoroscopy apparatus which concerns on this invention. It is a block diagram showing the structure of the control system of 4th Embodiment of the X-ray fluoroscopic apparatus which concerns on this invention. It is a flowchart showing operation | movement of the X-ray fluoroscope shown in FIG. It is a figure for demonstrating the image displayed by the operation | movement shown in FIG. 18, and is a figure showing the frame after affine transformation application. It is a figure for demonstrating the image displayed by the operation | movement shown in FIG. 18, and is a figure showing the contrast blood vessel image superimposed and displayed on the flame | frame after affine transformation application shown in FIG. It is a figure for demonstrating the image displayed by the operation | movement shown in FIG. 18, and is a figure showing the image which superimposedly displayed the flame | frame after the affine transformation application shown in FIG. 19, and the contrast blood vessel image shown in FIG. In the fifth embodiment of the X-ray fluoroscopic apparatus according to the present invention, it is a diagram showing a state in which a geometric figure is superimposed and displayed on a wire tracking moving image. It is a block diagram showing the structure of the control system of 6th Embodiment of the X-ray fluoroscopic apparatus which concerns on this invention. FIG. 24 is a diagram for explaining a case where a three-dimensional blood vessel image is acquired by another medical image diagnostic apparatus in the X-ray fluoroscopic apparatus shown in FIG. 23. FIG. 24 is a diagram for explaining a case where a three-dimensional blood vessel image is acquired by another medical image diagnostic apparatus in the X-ray fluoroscopic apparatus shown in FIG. 23. It is a figure for demonstrating the modification of the X-ray fluoroscope shown in FIG. 23, and is a figure for demonstrating a position shift between a blood vessel image and a wire tracking moving image. It is a figure for demonstrating the modification of the X-ray fluoroscope shown in FIG. 23, and is a figure showing the wire tracking moving image seen from the 1st and 2nd direction. It is a figure for demonstrating the modification of the X-ray fluoroscopy apparatus shown in FIG. 23, and is a figure showing the state by which alignment with the blood vessel image and a wire tracking moving image is made irrespective of the direction. In the seventh embodiment of the X-ray fluoroscopic apparatus according to the present invention, it is a diagram showing the correspondence relationship between the position of the tip image of the wire in the wire tracking moving image and the position in the three-dimensional blood vessel image. It is a figure showing the display mode of the wire tracking moving image by 7th Embodiment of the X-ray fluoroscopy apparatus concerning this invention. It is a figure showing the display mode of the tracking screen by 7th Embodiment of the X-ray fluoroscopy apparatus concerning this invention. In the seventh embodiment of the X-ray fluoroscopy device according to the present invention, it is a diagram showing a case where there are a plurality of positions in the three-dimensional blood vessel image corresponding to the positions of the tip image of the wire in the wire tracking moving image. It is a figure showing the display mode of the tracking screen displayed in the case shown in FIG. It is a figure for demonstrating the modification of 7th Embodiment of the X-ray fluoroscopy apparatus which concerns on this invention. It is a figure for demonstrating the other modification of 7th Embodiment of the X-ray fluoroscopy apparatus which concerns on this invention.

  An example of an embodiment of the present invention will be described in detail with reference to the drawings. Hereinafter, embodiments of the X-ray fluoroscopic apparatus according to the present invention will be described in detail. The X-ray fluoroscopic apparatus is configured to execute the X-ray fluoroscopic image processing method according to the present invention.

  The X-ray fluoroscopic apparatus according to this embodiment is used in a surgery performed by inserting a wire into the body of a subject. Hereinafter, a case where the present invention is applied to a fluoroscopic catheterization will be described in detail. This X-ray fluoroscopic apparatus is intended to optimize the work performed while observing in real time a wire or blood vessel that moves based on the operation of the operator. More specifically, the X-ray fluoroscopic apparatus suppresses the movement of the wire image caused by the motion of the subject (heartbeat, respiration, body movement, etc.) in the moving image for observing the state inside the body. Therefore, the visibility of the image of the wire is improved.

  In this embodiment, unless otherwise specified, “image” and “image data” are not distinguished. Image data processed by the X-ray fluoroscopic apparatus is generally paint data (also called raster data, bitmap data, etc.). The paint data is image data formed by pixels such as pixels and voxels, and is formed by assigning values (pixel values) to the respective pixels. An image is a representation of this image data so as to be visible by a predetermined computer program. As described above, the image data and the image substantially correspond one to one.

<First Embodiment>
[Device configuration]
The configuration of the X-ray fluoroscopic apparatus according to this embodiment will be described. A configuration example of this X-ray fluoroscopic apparatus is shown in FIG. This X-ray fluoroscopic apparatus has the same mechanical configuration as the conventional one.

  The subject 1 represents a patient who is subjected to catheterization under fluoroscopy. The subject 1 is placed on the top 2. The top plate 2 is a part of a couch device (not shown). The bed apparatus is provided with a drive mechanism for moving the top board 2. In this embodiment, the subject 1 is placed so as to lie on the top 2. Some X-ray fluoroscopy devices are provided with an upright mounting table that supports the subject in a standing position. However, in X-ray fluoroscopic catheterization, the object is usually supported in a supine position on the top plate. The specimen is treated.

  The C arm 3 is a support member formed in a substantially “C” shape. An X-ray tube 4 and an X-ray diaphragm 5 are supported on one end side of the C arm 3, and an X-ray detector 6 is supported on the other end side. Thereby, the X-ray tube 4 and the X-ray diaphragm 5 and the X-ray detector 6 are arranged at positions facing each other with the subject 1 interposed therebetween.

  The C arm 3 is movably held by a drive mechanism 8. The drive mechanism 8 moves the C arm 3 under the control of the arithmetic and control unit 20, thereby changing the positions and inclination angles of the X-ray tube 4, the X-ray diaphragm 5 and the X-ray detector 6. The X-ray tube 4 is an example of the “X-ray irradiation means” in the present invention. The X-ray detector 6 is an example of the “X-ray detector” of the present invention.

  The X-ray tube 4 generates X-rays 7 when a high voltage is applied from the high-voltage generator 9. The X-ray diaphragm 5 has diaphragm blades that regulate the irradiation range (solid angle and cross-sectional shape) of the X-ray 7 generated from the X-ray tube 4. The aperture controller 10 changes the irradiation range of the X-ray 7 by moving the position of the aperture blade. The operations of the high voltage generator 9 and the aperture controller 10 are controlled by the arithmetic and control unit 20.

  The X-ray 7 whose irradiation range is regulated by the X-ray diaphragm 5 is irradiated to the subject 1. The X-ray 7 that has passed through the subject 1 is projected to the X-ray detector 6. The X-ray detector 6 detects the X-ray 7, converts the detection result into an electric signal, and transmits it to the detection control unit 11. The detection control unit 11 transmits this electric signal to the arithmetic control device 20. The detection control unit 11 controls the operation of the X-ray detector 6.

  The X-ray detector 6 can be configured using, for example, a flat panel detector (FPD) or an image intensifier (I.I.).

  In this embodiment, the X-ray tube 4 is controlled to irradiate the X-rays 7 at a predetermined time interval. This time interval is set to, for example, about 1/30 second to 1/5 second (5-30 irradiations per second). Note that the X-ray fluoroscopic apparatus can perform irradiation at a maximum of several tens of times / second, for example, but this time interval is selected in order to reduce X-ray exposure to the subject 1 and the operator. Thereby, a moving image with a frame rate of about 5 to 30 frames / second is obtained. Instead of repeatedly irradiating X-rays in this way, it is also possible to irradiate X-rays continuously.

  The arithmetic and control unit 20 controls each part of the X-ray fluoroscopic apparatus and executes various arithmetic processes. The arithmetic and control unit 20 has the same configuration as a general computer, for example. As an example, the arithmetic and control unit 20 includes a microprocessor, a storage device (RAM, ROM, hard disk drive, etc.), a communication interface, and the like. An operation device, an input device, and a display device are connected to the arithmetic control device 20.

  A system control unit 21 in the arithmetic and control unit 20 controls each unit of the X-ray fluoroscopic apparatus. One example is as follows: the drive mechanism 8 is controlled to move the C-arm 3; the high-voltage generator 9 is controlled to change the X-ray conditions (such as the dose of the X-ray 7); The control unit 10 is controlled to change the irradiation range of the X-ray 7; the detection control unit 11 is controlled to control the operation of the X-ray detector 10. Further, the system control unit 21 controls each unit of the arithmetic and control unit 20.

  The image processing unit 23 forms an image (digital image data) of the subject 1 based on the electrical signal transmitted from the X-ray detector 6 via the detection control unit 11. The image processing unit 23 performs various image processing on the image. Details of the image processing unit 23 will be described later.

  The display control unit 24 displays information on the display unit 31 under the control of the system control unit 21. The display unit 31 is configured using a display device such as a liquid crystal display (LCD) or a CRT (Cathode Ray Tube) display. The display unit 31 is an example of the “display unit” of the present invention together with the system control unit 21 and the display control unit 24.

  The operation unit 32 is used for operating the X-ray fluoroscopic apparatus and inputting information. The operation unit 32 includes operation devices and input devices such as a keyboard, a mouse, and a control panel.

(Image processing unit)
A configuration example of the image processing unit 23 will be described with further reference to FIG. The image processing unit 23 is provided with a wire specifying unit 41 and an alignment processing unit 43.

  The image processing unit 23 executes processing described below in real time. The real-time processing in this embodiment is the result of immediately executing the processing for the frame in response to the electrical signal (corresponding to one frame) from the X-ray detector 6 being input to the arithmetic and control unit 20. Is output (displayed). Thereby, it becomes possible to display the state of the wire as a moving image within a delay time that is considered practically not delayed.

(Wire identification part)
As described above, in this embodiment, a moving image having a frame rate of about 5 to 30 frames / second is obtained. The wire specifying unit 41 specifies a guide wire image in each of a plurality of frames constituting the moving image. The wire specifying unit 41 is an example of the “specifying unit” of the present invention.

  Here, the frame refers to each of a series of still images constituting a moving image. Further, the plurality of frames do not have to be all frames constituting the moving image. For example, it may be a plurality of frames determined according to the start timing and end timing of characteristic functions (described later) of this embodiment. During the operation, a moving image of about several frames to about 30 frames per second is continuously generated over a long time (for example, several hours), but the function according to this embodiment is used, for example, about several minutes. It is. The image processing unit 23 starts its operation together with an instruction to start using the function according to this embodiment, and executes the following processing. The frames to be processed by the image processing unit 23 are a series of frames acquired after the use start instruction.

  The operation of the wire specifying unit 41 will be described in more detail. An example of the frame is shown in FIG. Frame F represents the catheter and guide wire inserted from the femoral artery inserted into the coronary artery via the aorta. In general, an X-ray image is often displayed so that a portion with a small amount of X-ray transmission is drawn black and a portion with a large amount of white is drawn white. FIG. 3 also follows this display method. A schematic diagram of the image shown in FIG. 3 is shown in FIG.

  An image C ′ that looks like a dark band in the frame F is a shadow of the catheter. In addition, an image C that looks slightly black and is located at the distal end portion of the catheter image C ′ is a shadow of the guide wire. The tip of the catheter is open. The distal end side of the guide wire protrudes from this opening. In addition, a large bend near the center of the guide wire occurs because the catheter is fitted at the branch from the aorta to the coronary artery. When the tip portion of the guide wire image C is viewed in detail, it is slightly bent. This is a bend that is attached to the guide wire in advance so that the guide wire can be easily inserted into the branching portion of the blood vessel. Frame F depicts such a state.

  In FIG. 4, an image depicting a body tissue such as a blood vessel, an organ, or a bone is omitted for easy viewing (the same applies to the other schematic diagrams below). In an actual frame, as shown in FIG. 3, a complex shading pattern corresponding to the body tissue is also depicted. In this embodiment, an image and its substance (catheter, guide wire, body tissue, etc.) are not distinguished unless otherwise specified.

  In this embodiment, a frame as shown in FIG. 3 is processed. In order to specify the image C of the wire more easily and with high accuracy, first, the wire specifying unit 41 performs enhancement processing to make the image C clearer. As an example of this enhancement processing, after performing non-linear lightness conversion to reduce the density unevenness of the image C of the wire, an image filter processing for extracting a component having a high spatial frequency from among various spatial frequency components of the image is performed. There is a way. This image filtering process removes a global and smooth gradation and leaves only local and minute fluctuation components.

  The emphasis process is not limited to the above example. For example, the content of the enhancement process can be determined as appropriate in accordance with the X-ray fluoroscope used and the characteristics of the subject. Further, it is possible to realize the enhancement process by appropriately combining known image processing techniques.

  The wire identification unit 41 performs an appropriate pattern extraction process on the frame F to identify the wire image C. As this pattern extraction processing, any image processing technique such as threshold processing regarding pixel values and spatial filter processing can be used as appropriate. Further, for specifying the wire image C, instead of specifying the entire image C, its outline may be specified.

  Mathematically, a wire is a smooth curve (three-dimensional curve) embedded in real space (three-dimensional space). On the other hand, an image obtained by the X-ray fluoroscope is a two-dimensional curve obtained by projecting the three-dimensional curve onto a plane. In this projection, the position of the X-ray tube 4 (that is, the generation position of the X-ray 7) is used as a viewpoint, and the detection surface of the X-ray detector 6 is used as a projection plane. Therefore, the specified wire image C can be understood as a two-dimensional curve (this is also represented by the same symbol C).

  The wire specifying unit 41 extracts the image C of the wire specified from the frame F. The alignment processing unit 43 represents the extracted image C as a two-dimensional curve (described later). An example of the extracted wire image C is shown in FIG. An example of a two-dimensional curve C based on the wire image C is shown in FIG.

  For each frame based on the electrical signal sequentially sent from the X-ray detector 6 at the aforementioned time interval, the wire specifying unit 41 executes the above processing in real time. FIG. 7 shows a part of a plurality of time-series wire images C obtained thereby.

  FIG. 8 shows a two-dimensional curve C based on the wire image C shown in FIG. 7 extracted from each temporally continuous frame group. The position and shape of the two-dimensional curve C change little by little as a result of movement of the subject 1 due to movement caused by respiration, heartbeat, and the like, and deformation of the wire itself due to movement of the wire in the blood vessel.

  When observing a wire inside the body, it is desirable to irradiate X-rays from a direction orthogonal to the wire as much as possible. This is because the movement of the wire is most easily understood on the video (moving image). Comparing the image C of the wire between two temporally adjacent frames, the difference between them is a slight change in shape and length, and the deformation and position of the wire due to parallel movement and rotational movement due to the movement of the subject 1. Although there are changes, the forms are similar to each other.

  Note that the tip portion of the wire may suddenly change shape due to an operation of twisting the wire or a collision with the blood vessel wall. However, the other portions reflect the shape of the blood vessel at the position where the wire actually passes and hardly deform rapidly. In this embodiment, the following processing is executed using this fact.

(Alignment processing unit)
The alignment processing unit 43 performs the following processing on each frame other than the first frame in a series of frames to which the function according to this embodiment is applied. At this time, the first frame is referred to as a position reference in the processing for the subsequent frames. The alignment processing unit 43 aligns the frame and the past frame so that the wire image C in the frame and the wire image C in the past frame overlap best. The alignment processing unit 43 is an example of the “alignment processing means” in the present invention. Hereinafter, the frame alignment process will be described in detail.

  First, the alignment processing unit 43 obtains a two-dimensional curve C representing the shape of the wire image C in each frame (see FIG. 6). At this time, image processing such as thinning processing is performed as necessary.

  First, an outline of processing for aligning two adjacent frames will be described. FIG. 9 shows a two-dimensional curve based on the wire image C in the frames f and g shown in FIG. FIG. 9A shows a two-dimensional curve Cf corresponding to the frame f, and FIG. 9B shows a two-dimensional curve Cg corresponding to the frame g. Note that the two-dimensional curve Cf is indicated by a solid line and the two-dimensional curve Cg is indicated by a broken line in consideration of the overlapping described later. The same applies to the coordinate axes in each figure.

  Next, the alignment processing unit 43 obtains coordinate transformation that best matches the two-dimensional curves Cf and Cg. This coordinate transformation includes translation and rotation. Such coordinate transformation can be expressed as affine transformation. However, the affine transformation used here does not include enlargement / reduction and reflection.

  The obtained affine transformation is to relatively translate and / or rotate the wire image C of the frame g in accordance with the wire image C of the frame f. This affine transformation is denoted as T (g, f).

  When determining the affine transformation T (g, f), it is necessary to consider the influence of deformation caused by the movement of the wire in the body. For this purpose, the entire two-dimensional curves Cf and Cg are not combined, but a deviation occurring at both end portions is allowed. In particular, since a sharp deformation may occur at the tip portion as described above, a relatively large deviation is allowed. For example, as shown in FIG. 10, the tip portions of the two-dimensional curves Cf and Cg do not need to be overlapped as accurately as other portions.

The alignment processing unit 43 generates weighting functions W _f and W _g corresponding to the positions of the two-dimensional curves Cf and Cg.

In general, a large weight is set for a portion for which superimposition is strictly performed, and a small weight is set for a portion that allows deviation. Since the vicinity of the tip portion of the wire is easily deformed as described above, the weight is reduced. Moreover, it is possible to give a weight according to the bending degree in each point of a wire. For example, it is desirable to increase the weight in a position where the bending of the wire is large. The weight functions W _f and W _g are generated by appropriately setting the weight at each position in view of these matters.

  Since the superposition is performed by applying the affine transformation T (g, f) shown in Expression (1) to the frame g, the parameters θ, u, and v need to be appropriately determined. Here, the parameter θ represents the rotational movement amount, and the parameters u and v represent the parallel movement amount.

A two-dimensional curve obtained by applying the affine transformation T (g, f) to the two-dimensional curve (x _g , y _g ) of the frame g is defined as (x _g ′, y _g ′). Assuming that E is a value obtained by evaluating the degree of inconsistency between the two-dimensional curve (x _f , y _f ) and the two-dimensional curve (x _g ′, y _g ′) of the frame f with an appropriate scale, the value of E is approximately Parameters θ, u, and v are calculated so as to be minimized.

As a more specific configuration, for example, the following can be performed. _Let D be the distance between each point p on the two-dimensional curve (x _f , y _f ) and a point q on the two-dimensional curve (x _g ′, y _g ′) that is closest to the point p. In consideration of the following, the evaluation scale E of the degree of inconsistency is considered.

The sum shown in Equation (2) is assumed for all points on the two-dimensional curve (x _f , y _f ). If the values of θ, u, and v are changed, the value of E also changes, so that θ, u, and v where E is substantially minimized are searched. This search can be performed by a technique such as a known nonlinear least square method.

  As described above, an appropriate affine transformation T (g, f) is determined. When this is applied to the frame g, the wire images C of the frames f and g are almost superposed, so that the frames f and g are aligned. In the above example, the affine transformation parameters are calculated so that the degree of inconsistency is substantially minimized. On the contrary, the degree of coincidence is evaluated by an appropriate scale, and the degree of coincidence is substantially maximized. It goes without saying that the affine transformation parameters may be obtained as described above.

  In the above calculation, alignment of two adjacent frames is executed. In this embodiment, since frames are sequentially formed in time series, in order to suppress the movement of the wire image C in the moving image, it is necessary to accumulate the affine transformations sequentially. . For this purpose, the alignment processing unit 43 executes the following processing.

A frame immediately before the first frame to be subjected to motion suppression processing is referred to as a frame F0, and subsequent frames are sequentially referred to as frames F1, F2, F3,... (Not shown). At this time, the frame Fn (n = 1,2,3, ····) an affine transformation that is applied to when the _{T n,} the alignment processing unit 43, each affine transformation _{T n} in the following formula Ask.

The positioning process unit 43, executes this way the affine transformation T _n obtained sequentially, by going sequentially applied to the corresponding frame Fn, the alignment of a plurality of frames are sequentially acquired in real time To do.

  In this way, after the next frame g is aligned with the first frame f, the frame h following the frame g is aligned with “g aligned with the first frame f”. Will be. Therefore, the frame h is substantially correctly aligned with the frame f. The same applies hereinafter. In this way, it is possible to generate a moving image (insertion instrument positioning moving image) in which the wire image C is almost stationary.

  The wire tracking moving image obtained in this way consists of a frame of the same size as the X-ray fluoroscopic image (that is, the same X-ray irradiation area), but the image area including the wire image is trimmed from the frame (necessary) If so, it can be enlarged and displayed separately from the normal fluoroscopic image. The image area to be trimmed will be referred to as a “trim frame”. The size and position of the trim frame can be set manually. When this trim frame is used, only an image around the wire of interest is displayed as a wire tracking moving image, and other portions are not displayed. If other parts are displayed, a moving image in which an image of a tissue such as a bone moves is displayed, which imposes a burden on the observer's eyes. The trim frame will be further described in the second embodiment.

[Operation]
The operation of the X-ray fluoroscope configured as described above will be described. An example of the operation of this X-ray fluoroscopic apparatus is shown in FIG.

  It is assumed that the subject 1 is placed on the top 2 and a wire is inserted into the body of the subject 1. It is assumed that the X-ray tube 4 and the X-ray detector 6 are arranged so as to see through a region including the affected area, and the X-ray diaphragm 5 is set to an appropriate irradiation range.

  The surgeon performs a predetermined operation using the operation unit 32 and instructs the start of X-ray fluoroscopy (S1). Upon receiving this instruction, the system control unit 21 controls the high voltage generator 9 and the detection control unit 11 to start X-ray fluoroscopy of the subject 1. In this embodiment, the X-ray tube 4 emits X-rays at a predetermined time interval, and the X-ray detector 6 detects the transmission of the X-rays emitted intermittently. The system control unit 21 causes the display unit 31 to display a moving image (normal perspective moving image) having a frame rate corresponding to the time interval via the display control unit 24 (S2). At this time, frames sequentially acquired corresponding to intermittent irradiation of X-rays are sequentially sent to the image processing unit 23 by the system control unit 21.

  Note that the normal perspective moving image displayed in step 2 is displayed without being subjected to a process related to a motion suppression function described later. Displaying this normal fluoroscopic moving image is a legal restriction.

  In a state where the image C of the wire is depicted in the moving image, the surgeon operates the operation unit 32 to instruct the start of the function (motion suppression function) according to this embodiment (S3). Upon receiving this instruction, the system control unit 21 causes the image processing unit 23 to execute the following processing. Details of the following processes have been described above.

  In this operation example, a case where a plurality of processes are sequentially executed for each frame will be described for the sake of easy understanding. However, a process for a new frame is sequentially performed while a process for a certain frame is being executed. (So-called pipeline processing) is also possible. As an example, while executing the process of specifying the wire image for a certain frame, the process of enhancing the wire image for the next frame may be executed.

  First, the wire specifying unit 41 emphasizes the image of the wire in each of the frame F1 acquired at the timing when the start of the motion suppression function is instructed and the immediately preceding frame F0 as necessary.

  Next, the wire specifying unit 41 specifies the emphasized wire image from each of the frames F0 and F1, and extracts it as a two-dimensional curve (S4). Thereby, a new image (frame) as shown in FIG. 6 is formed for each of the frames F0 and F1. These new frames will also be described using symbols F0 and F1, respectively.

The alignment processing unit 43 generates weight functions W _F0 and W _F1 corresponding to the two-dimensional curves (x _F0 , y _F0 ) and (x _F1 , y _F1 ) based on the frames F0 and F1, respectively. Further, the alignment processing unit 43 uses these weight functions W _F0 and W _F1 to determine an affine transformation T ₁ for superimposing the wire image of the frame F0 and the wire image of the frame F1 (S5).

If generation of the wire tracking the moving image has not been started (S6: No), the image processing unit 23, the rotational movement amount θ and the parallel movement amount u of the determined affine transformation T _1, v is respectively less than the predetermined value (S7). This predetermined value is preset. When it is determined that the value is equal to or greater than the predetermined value (S7: No), the process shifts to processing for the next frame F2 without performing alignment of the frames F0 and F1 (S12). If a predetermined time (for example, a time for one heartbeat (about 1 second)) has elapsed without being determined that the rotational movement amount θ or the like is less than the predetermined value, alignment is performed from the frame being processed at the time of the elapse. Processing is started and generation of a wire tracking moving image is started (S8).

When it is determined that the rotational movement amount θ and the parallel movement amounts u and v of the affine transformation T _i are less than a predetermined value for a certain frame F (i−1) and Fi (S7: Yes), the alignment processing unit 43 applies the affine transformation T _i to the frame Fi to execute alignment of the frames F (i−1) and Fi, and starts generating a wire tracking moving image (S8).

  The system control unit 21 displays the aligned wire tracking moving image after the frame F (i-1) via the display control unit 24 (S9). At this time, the wire tracking moving image is displayed together with the normal fluoroscopic moving image. Note that the displayed wire tracking moving image may be one after image processing (for example, brightness adjustment, contrast adjustment, filter processing, noise suppression processing, etc.) for improving visibility, or these images. The thing before performing a process may be sufficient.

  If the instruction to end the motion suppression function has not been given yet (S10, No), the process proceeds to the next frame F (i + 1) (S12). As described above, a part of the process for the frame F (i + 1) may be executed between the processes for the frames F (i−1) and Fi. In any case, the wire image enhancement processing and identification processing (S4) are executed for the frame F (i + 1).

The alignment processing unit 43 obtains an affine transformation T (i + 1, i) between the frames Fi and F (i + 1). Further, as shown in the above equation (3), the alignment processing unit 43 combines the affine transformation T (i + 1, i) and the affine transformation T _i and applies it to the frame F (i + 1). The transformation T _{i + 1} = T (i + 1, i) T _i is determined (S5). Since generation of the wire tracking moving image is started, the process proceeds to step 8 (S6: Yes).

The alignment processing unit 43 performs alignment of the frame F (i + 1) with respect to the frame Fi by applying the determined affine transformation T _{i + 1} to the frame F (i + 1), and generates a wire tracking moving image (S8). ).

  The system control unit 21 displays the next frame F (i + 1) in the wire tracking moving image via the display control unit 24 (S9).

  The image processing unit 23 repeatedly executes the above-described processing on sequentially acquired frames until the operator gives an instruction to end the function. When an instruction to end the function is given (S10, Yes), the above processing is executed until the frame (referred to as the final frame) obtained at the timing of the instruction, and the motion suppression function is ended. That is, when there is a frame (remaining frame) in which the above processing is not completed (S11, Yes), the above processing is executed up to the final frame and the function is terminated. On the other hand, when there is no remaining frame (S11, No), the function is terminated. This is the end of the description of this operation example.

[Action / Effect]
The operation and effect of the X-ray fluoroscopic apparatus according to this embodiment will be described.

  This X-ray fluoroscopic device specifies an image of a wire in each of a plurality of frames constituting the moving image with respect to a moving image acquired in real time in catheterization under X-ray fluoroscopy. The plurality of frames is, for example, a frame group acquired from a frame immediately before the timing of the start instruction of the motion suppression function (the frame F0) to a frame of the timing of the instruction to end the function. The X-ray fluoroscopic apparatus sequentially specifies wire images for sequentially acquired frames. In addition, in order to improve the precision and accuracy of the specific process, it is possible to perform an enhancement process for enhancing the wire image in each frame in advance.

  This X-ray fluoroscopic apparatus has the following frames Fi (frames in which the rotational movement amount θ and the like are less than a predetermined value, that is, frames in which the displacement of the two-dimensional curve is small with respect to the immediately preceding frame). The frame Fn and the past frame are aligned so that the wire image in the frame Fn (n = i, i + 1, i + 2,...) And the wire image in the past frame are overlapped. This processing is also sequentially performed on the frames in which the wire images are sequentially specified.

  Further, the X-ray fluoroscopic apparatus displays a wire tracking moving image based on a plurality of frames after the alignment. The wire tracking moving image is presented as a moving image by sequentially displaying frames that have been sequentially aligned (at a frame rate corresponding to an X-ray irradiation interval).

In the alignment process, the wire image in the frame Fn and the wire image in the previous frame are relatively translated and / or rotated to overlap. Translation and rotation movement is represented as an affine transformation T _n. In addition, as described above, this alignment processing is not performed so that the guide wire images completely coincide with each other, but is performed so that the guide wire images are optimally overlapped with each other in the category of parallel movement and rotational movement. It is.

  In the alignment process, the following processes are sequentially performed on sequentially acquired frames to align the entire frame after frame F (i-1). That is, in the alignment processing, each of the frames other than the first two frames (frames F (i + 1), F (i + 2), F (i + 3),. Based on the result of alignment for one or more frames and the result of alignment between the frame Fn and the latest frame (frame F (n-1)) of the two or more frames in the past. Fn and the first frame (frame F (i-1)) of two or more past frames are aligned.

  According to such an X-ray fluoroscopic apparatus, since the position of a plurality of frames can be aligned so that the positions of the wire images in the frame are overlapped, the movement of the wire is suppressed in the fluoroscopic catheterization. It is possible to display the wire tracking moving image in real time.

  If the above-described trim frame is used, only the image around the wire of interest is displayed as the wire tracking moving image. Thereby, other parts where the tissue such as bone moves around are excluded from the display image, so that the visibility of the wire tracking moving image is improved.

In this embodiment, alignment processing is performed for each frame with reference to the immediately preceding frame, but the present invention is not limited to this. In the present invention, each frame can be aligned with reference to, for example, one or a plurality of frames preceding by several frames. That is, each frame may be configured to be aligned with reference to one or more past affine transformations T _k and T _k−1 . More specifically, instead of applying the affine transformation _{T k} calculated in the frame _{Fk, T} k, T _k-1, another affine transformation calculated from _{··· S (T k, T k} -1, · ..) is applied to the frame Fk. The affine transformation S is, for example, a parallel movement amount <u obtained by weighted smoothing of the parallel movement parameters u _j and v _{j of} T _j (j = k, k−1,...) And the rotational movement parameter θ _j. >, <V>, and an affine transformation having a rotation angle <θ>. According to this configuration, even if the affine transformation of the frame Fk is calculated as a somewhat inappropriate transformation due to accidental noise or calculation error, the influence can be suppressed, so that the wire tracking video with high visibility can be suppressed. Can provide an image.

  Also, instead of executing the above process for all the frames, the above process is executed every several frames, and for the frame for which the above process has not been executed, the result of the alignment of the frame in which the above process was executed immediately before It is also possible to configure so as to perform alignment using. In any case, the present invention executes the alignment process for each frame with reference to one or more previous frames.

  In the above description of the operation, the generation of the wire tracking moving image is started from a frame having a small rotational movement amount θ or the like (step 7 “Yes” in FIG. 11), but the generation start timing of the wire tracking moving image is limited to this. Is not to be done. For example, when performing an operation while taking an electrocardiogram of the subject 1, an output signal from an electrocardiograph attached to the subject 1 is analyzed to detect a timing at which the movement of the body tissue due to the heartbeat becomes small (for example, one heartbeat) The detection processing is performed for a minute time), and the generation of the wire tracking moving image can be started from the frame obtained at that timing. As a result, as in the case of the above description of the operation, the generation and display of the wire tracking moving image can be started at a timing at which the movement of the image due to the heartbeat becomes small.

  As described above, the operation according to this embodiment includes the step of determining affine transformation (conversion decision phase: steps 4 and 5 in FIG. 11) and the step of applying and displaying the determined affine transformation (conversion application phase). : Steps 8 and 9).

<Second Embodiment>
Another embodiment of the present invention will be described. The reason why the operator refers to the X-ray fluoroscopic image in the catheterization under X-ray fluoroscopy is mainly because it is desired to observe the vicinity of the tip of the wire in detail. Therefore, an image (moving image) of a part other than the vicinity of the tip of the wire is not so important. In this embodiment, in view of such a fact, a technique for improving the visibility near the tip of the wire will be described after performing the processing described in the first embodiment.

  The X-ray fluoroscopic apparatus according to this embodiment operates to cut out and enlarge an image region in the vicinity of the distal end portion of the wire image (that is, an image corresponding to the distal end portion of the wire). In order to realize this, the X-ray fluoroscopic apparatus according to this embodiment is configured as follows, for example.

  Hereinafter, cutting out an image area from each frame is referred to as “trimming”. In addition, the boundary of the image area trimmed from each frame is referred to as a “trim frame”. The image area having the trim frame as a boundary is an example of the “predetermined range” in the present invention.

  It is assumed that the size of the trim frame set for each frame is determined in advance. This size may be a predetermined default value or may be set in advance by an operator or the like. Further, the size once determined may be adjusted appropriately.

  Since the wire moves in the blood vessel, it is possible that the distal end portion of the image of the wire (referred to as the distal end image) is detached from the trim frame. A specific example thereof will be described with reference to FIG. In the frame Fn shown in FIG. 12A, the front end image Ca is located near the center of the trim frame R. If the wire is moved in this state, the tip image Ca may come out of the trim frame R as shown in a frame F (n + 1) shown in FIG.

Therefore, for each frame Fn, it performs a process of specifying a position of the tip image after affine transformation T _n has been subjected. This specifying process can be executed based on the shape information of the wire image obtained in the first embodiment (for example, the coordinate value of each point of the two-dimensional curve).

  If the position of the trim frame is determined so that the specific position of the front-end image is always arranged at a predetermined position (for example, the center) in the trim frame, the problem that the front-end image deviates from the trim frame is solved. However, as described above, the position of the tip image may change abruptly due to the movement or twisting operation of the wire. Therefore, in such a countermeasure, the position of the trim frame moves abruptly. If it does so, it will become impossible to achieve the visibility improvement of the tip image which is the original purpose of this embodiment. That is, in this embodiment, it is necessary to smoothly change the position of the trim frame while capturing the tip image in the trim frame. For this purpose, the following configuration is applied.

  The X-ray fluoroscopic apparatus according to this embodiment has substantially the same configuration as that of the first embodiment. A configuration example of the characteristic part of this embodiment is shown in FIG. The image processing unit 23 includes a tip image specifying unit 51 and a trim frame position calculating unit 52 in addition to the wire specifying unit 41 and the alignment processing unit 43 similar to those in the first embodiment.

  The tip image specifying unit 51 specifies the tip image Ca of the guide wire in each of the plurality of frames as described above. The tip image specifying unit 51 is an example of the “tip portion specifying means” of the present invention.

The trim frame position calculation unit 52 executes the following processing. The position of the front-end image Ca in the frame Fn after the affine transformation T _n is applied is (x _n , y _n ), and the center position of the trim frame (represented by the symbol Rn) in the frame Fn is (X _n , Y _n ). And Here, the position (x _n , y _n ) of the tip image Ca is the coordinate value of the tip of the two-dimensional curve described in the first embodiment. At this time, the center position (X _n , Y _n ) of the trim frame Rn is obtained by the following calculation.

Here, the coefficient a is a real number between 0 and 1. The coefficient a is set in advance. The coefficient a is about 0.1, for example. With this configuration, the center position (X _n , Y _n ) of the trim frame Rn responds to the position (x _n , y _n ) of the tip image Ca as a so-called first-order lag system (in control engineering). . Accordingly, the center position (X _n , Y _n ) of the trim frame Rn smoothly follows the position (x _n , y _n ) of the tip image Ca with a slight delay.

  The trim frame position calculation unit 52 obtains the position of the trim frame Rn with respect to each frame Fn (n = 1, 2, 3,...) As described above. Thereby, the position of the trim frame Rn with respect to each frame Fn can be determined so that the front end image does not come off the trim frame and the position of the trim frame changes smoothly. The trim frame position calculation unit 52 is an example of the “change means” in the present invention.

Note that the center position (X ₀ , Y ₀ ) of the trim frame in a frame to which the process related to the trim frame is first applied (for example, the frame F0 or the frame Fi of the first embodiment) is set in advance. It shall be. As the center position (X ₀ , Y ₀ ), for example, the position of the tip image Ca in the frame F0 can be used.

  The trim frame thus determined will be described with reference to FIG. FIG. 14A shows a state where the tip image Ca is located near the center of the trim frame Rn in the frame Fn, as in FIG. 12A.

The trim frame position calculation unit 52 is based on the center position (X _n , Y _n ) of the trim frame Rn in the frame Fn and the position (x _{n + 1} , y _{n + 1} ) of the front end image Ca in the frame F (n + 1). The center position (X _{n + 1} , Y _{n + 1} ) of the trim frame R (n + 1) with respect to the frame F (n _{+ 1} ) is calculated. The trim frame R (n + 1) centered on this coordinate value (X _{n + 1} , Y _{n + 1} ) includes the front end image Ca in the frame F (n + 1) as shown in FIG. Further, the trim frame R (n + 1) is displayed so as to move smoothly from the immediately preceding trim frame Rn.

  The operation of the X-ray fluoroscopic apparatus according to this embodiment will be described. An example of this operation is shown in FIG. Note that part or all of the description of the same processing as in the first embodiment may be omitted.

When an instruction to start the motion suppression function is given (S21), the wire specifying unit 41 specifies the wire image in each of the frames F0 and F1 (S22), and the alignment processing unit 43 is between the frames F0 and F1. the determining an affine transformation _{T 1,} to align This is applied to the frame F1 (S23).

Next, the tip image specifying unit 51 specifies the tip image Ca in each of the frames F0 and F1 (S24). The coordinate value of the front-end image Ca of the frame F0 is used as the initial center position (X ₀ , Y ₀ ) of the trim frame as described above.

Based on the initial center position (X ₀ , Y ₀ ) and the coordinate values (x ₁ , y ₁ ) of the tip image Ca in the frame F1, the trim frame position calculation unit 52 is the center position of the trim frame R1 with respect to the frame F1. (X ₁ , Y ₁ ) is calculated (S25).

The image processing unit 23 extracts a partial image (corresponding to an image in the trim frame) in the frame F0 having a predetermined shape and size with the initial center position (X ₀ , Y ₀ ) as the center, and in the frame F1. A partial image surrounded by the trim frame R1 is extracted (S26).

  The system control unit 21 enlarges and displays the partial image of the frame F1 after the partial image of the frame F0 via the display control unit 24 (S27). Enlarged display means that the frame is enlarged and displayed as compared with the partial image when the frame is displayed as it is.

  Further, the time interval for switching the display of the frames F0 and F1 is the same as the irradiation interval of the X-rays 7. The partial image corresponding to the frame F0 is displayed in advance at a predetermined timing, and the partial image of the frame F0 is displayed from the partial image of the frame F0 at the timing when the partial image of the frame F1 is extracted in step 26. You may switch.

  Steps 28 and 29 are the same as steps 10 and 11 in FIG. 11 of the first embodiment. When there is a next frame (S28, No: S29, Yes), the image processing unit 23 extracts the partial image of the frame Fn by repeating the above process (steps 22 to 26). Then, the system control unit 21 displays this partial image instead of the partial image of the frame F (n-1) via the display control unit 24 (S27).

  As a result, a moving image based on the partial image drawn in the trim frames Rn of the plurality of frames Fn is displayed. The frame rate of this moving image corresponds to the irradiation interval of the X-rays 7. This moving image is an example of the “partial moving image” of the present invention.

  On the other hand, when there is no next frame (S28, Yes: S29, No), the motion suppression function ends. This is the end of the description of this operation example.

  According to the X-ray fluoroscopic apparatus according to this embodiment, it is possible to smoothly change the position of the trim frame while capturing the tip image in the trim frame. Moreover, according to this X-ray fluoroscope, the movement of the tip part of the wire resulting from the movement of the subject 1 can be suppressed, and the partial moving image in the trim frame can be enlarged and displayed. Thereby, the visibility of the tip portion of the wire is improved.

  Note that a normal fluoroscopic image may be displayed in parallel with the partial moving image. At this time, a graphic or the like representing the boundary of the partial moving image (that is, the trim frame) can be displayed in the normal fluoroscopic image. Thereby, it is possible to easily grasp which partial area in the normal fluoroscopic image is enlarged and displayed as the partial moving image. In addition, there is an advantage that the surrounding state of the partial moving image can be grasped by a normal fluoroscopic image while grasping the dynamics of the distal end portion of the wire by the partial moving image.

  In addition, it is desirable to configure so that an operator or the like can appropriately change the magnification rate of the partial moving image. An instruction for this can be configured to be performed by appropriate means such as voice input, a switch, a keyboard, a dial, and a pointing device. As a result, the distal end portion of the guide wire and its vicinity can be observed at a desired magnification, and the visibility and convenience are improved.

  Further, the shape of the trim frame is not limited to a rectangle. For example, a trim frame having an arbitrary shape such as a circle or an ellipse can be applied.

  In this embodiment, the position of the trim frame is determined so as to follow the tip portion of the wire in real time, but the present invention is not limited to this. In the above description, the configuration in which the tip of the wire is positioned approximately at the center of the trim frame has been described. Therefore, it is also useful to configure so that an appropriate point in the direction of travel of the wire is at the approximate center of the trim frame instead of the tip of the wire. A specific example of this configuration will be described with reference to FIG. First, for the frame Fn shown in FIG. 16A, the tangent at the tip portion of the wire image C is calculated. At this time, the strongly bent portion at the tip of the wire can be excluded from the calculation of the tangent. Next, the traveling direction of the wire is estimated from this tangent. A vector (wire traveling direction vector) indicating the estimated traveling direction is indicated by a symbol α. Subsequently, a target point e is a position separated from the tip of the wire image C by an appropriate distance (for example, about 1/4 of the size of the trim frame Rn) along the wire traveling direction vector α. Then, the trim frame R (n + 1) of the next frame F (n + 1) is set so that the center of the trim frame is positioned at this point e. Accordingly, the trim frame can be moved so that the wire is advanced in the traveling direction.

  Further, the trim frame can be configured to move when the wire (the tip portion thereof) is likely to come off from the current trim frame or when the wire is removed. In this case, the positional relationship between the trim frame and the wire is detected as follows, for example. The position of each point of the guide wire can be grasped by, for example, the two-dimensional curve of the first embodiment. On the other hand, since the center position of the trim frame is known and its shape and size are also known, the position of each point on the trim frame (boundary) can also be grasped. The image processing unit 23 obtains the shortest distance between the specific part (for example, the tip part) of the wire and the trim frame. Further, the image processing unit 23 specifies in which direction the position of the point on the trim frame from which the shortest distance is obtained is located with respect to the center position of the trim frame. The image processing unit 23 determines the position of the next trim frame so that the trim frame moves by a predetermined distance in this specific direction. The predetermined distance may be, for example, a default value set in advance, or may be determined based on a change in the shortest distance along the time series (in other words, the speed of the specific part).

  Instead of moving the trim frame, the size of the trim frame may be changed to prevent a specific portion of the wire from going out of the frame.

<Third Embodiment>
Another embodiment of the present invention will be described. In the first and second embodiments, alignment between frames is performed by obtaining an affine transformation representing parallel movement and rotational movement. However, when rotational movement is performed by affine transformation, interpolation processing may be required to create a transformed image (frame). Then, the amount of calculation increases and the processing time becomes longer, and depending on the processing capability of the image processing unit 23, there is a risk of hindering real-time processing while performing X-ray fluoroscopy.

  On the other hand, in many of the rotational movements implemented in the present invention, the rotational angle is actually small. Therefore, it may be effective to reduce the calculation process by applying affine transformation that considers only parallel movement while omitting rotational movement. That is, in the affine transformation, the rotational movement amount is fixed at θ = 0, and the calculation process is performed by determining a value that minimizes the sum E shown in Expression (2) for only the parallel movement amounts u and v. realizable.

  According to this embodiment, the alignment is performed in consideration of only the parallel movement without considering the rotational movement, so that the partial moving image is displayed by simple calculation compared to the first and second embodiments. be able to. However, since the influence of rotation caused by the motion of the subject 1 is reflected in the partial moving image, the movement of the wire image cannot be suppressed as much as the partial moving images of the first and second embodiments.

  Further, the magnification of the partial moving image (that is, each partial image) is set to a / b times (a> b), and the center position of the trim frame is an integral multiple of 1 / b of the pixel size of the original image (frame). Can be set to be This eliminates the need for floating-point calculation in the interpolation calculation required when creating a partial image that is an enlarged image, and further reduces the amount of calculation and the calculation time.

  In addition, if the amount of parallel movement based on affine transformation is set to an integer multiple of the frame pixel interval (distance between adjacent pixels), interpolation processing becomes unnecessary, and the calculation amount and calculation time can be further reduced. Become.

<Fourth Embodiment>
Another embodiment of the present invention will be described. In catheterization performed by inserting a wire into a blood vessel, in the above-described embodiment, alignment between frames is performed by identifying an image of the wire in each frame and determining affine transformation. As a result, on the image subjected to affine transformation, the position of the image of the wire is substantially constant (unless the wire is moved in the blood vessel), and the position of the image of the blood vessel that cannot be visually recognized (the movement of the wire) It is almost constant (with or without). Therefore, when an arbitrary still image is superimposed and displayed on the moving image, the relative positional relationship between the still image and the blood vessel image is almost unchanged. This embodiment takes advantage of this fact.

  In catheterization under fluoroscopy, in order to observe the branching of a blood vessel, the shape of a stenosis, and the like, an image of a blood vessel (contrast-enhanced blood vessel image) that is contrasted by occasionally letting out a contrast medium from the catheter is displayed. Therefore, if this contrasted blood vessel image is recorded and subjected to affine transformation and then superimposed on the moving image, the contrasted blood vessel image represents the shape and position of the actual blood vessel almost accurately. Note that the contrast-enhanced blood vessel image is superimposed on the wire tracking moving image, and the partial image of the contrast-enhanced blood vessel image is superimposed on the partial moving image. This function facilitates grasping and storing of the target position where the wire is advanced, and can further reduce the number of times the contrast agent is used.

  In order to realize such a function, the X-ray fluoroscopic apparatus according to this embodiment includes the following means: (a) detection means for detecting the acquisition timing of the contrast blood vessel image; (b) contrast blood vessel Means for forming an image; (c) means for superimposing and displaying a contrast-enhanced blood vessel image on a moving image. In addition to these, it is also possible to provide means for instructing whether or not to perform superimposed display.

  The X-ray fluoroscopic apparatus according to this embodiment has substantially the same configuration as that of the first embodiment. Note that, when a contrast blood vessel image is displayed superimposed on a partial moving image, the X-ray fluoroscopic apparatus according to this embodiment has substantially the same configuration as that of the second embodiment. Hereinafter, a case where a contrasted blood vessel image is superimposed and displayed on the wire tracking moving image will be described in detail. When the contrast blood vessel image is superimposed on the partial moving image, the characteristic component of this embodiment is added to the configuration shown in FIG. 2, and the superimposed display can be realized by executing the same processing as described below. .

  A configuration example of the characteristic part of this embodiment is shown in FIG. The image processing unit 23 includes an acquisition timing detection unit 61 and a contrast blood vessel image forming unit 62 in addition to the wire specifying unit 41 and the alignment processing unit 43 similar to those in the first embodiment.

  The acquisition timing detection unit 61 detects the acquisition timing of the contrast blood vessel image while a plurality of frames are sequentially acquired. The acquisition timing detector 61 is an example of the “detector” of the present invention.

  The acquisition timing detection unit 61 has the following configuration, for example. FIG. 17 shows a case where a third configuration described later is applied.

  The first configuration is for manually inputting a contrast blood vessel image acquisition timing. The acquisition timing detection unit 61 according to the first configuration includes the operation unit 32. The operator or the like operates the operation unit 32 (predetermined switch, pedal, etc.) at a timing when acquisition of a contrasted blood vessel image is desired, and instructs acquisition of a contrasted blood vessel image. Upon receiving this operation, the system control unit 21 causes the image processing unit 23 to form a contrasted blood vessel image.

  The second configuration automatically detects that the contrast medium has flowed out of the catheter, and uses this detection timing as the acquisition timing. As a method for injecting a contrast agent, a method of manually operating a syringe connected to a catheter, a method of operating an operation unit 32 (predetermined switch or pedal) manually, and operating an auto injector connected to the catheter, etc. There is.

  When the syringe is manually operated, the acquisition timing detection unit 61 according to the second configuration is configured to include a sensor provided in the syringe. This sensor detects that the syringe has been operated and sends an electrical signal to the system controller 21. Upon receiving this electrical signal, the system control unit 21 causes the image processing unit 23 to form a contrasted blood vessel image.

  On the other hand, when the auto injector is used, the acquisition timing detection unit 61 according to the second configuration is configured to include the operation unit 32. The system control unit 21 causes the image processing unit 23 to form a contrasted blood vessel image in response to the operation using the operation unit 32. As another configuration example, the acquisition timing detection unit 61 intercepts, for example, a signal transmitted from the operation unit 32 to the autoinjector by the system control unit 21 and outputs a blood vessel image to the image processing unit 23 corresponding thereto. Let it form.

  The third configuration is to detect the inflow of the contrast agent into the blood vessel by analyzing sequentially acquired frames, and use this as the acquisition timing of the contrast blood vessel image. When the contrast agent flows into the blood vessel, an image of the blood vessel, which has been difficult to identify until then, clearly appears. The third configuration utilizes this phenomenon.

  More specifically, when a contrast agent enters the blood vessel, a shadow due to the contrast agent appears in the image (frame), and an image region (blood vessel region) corresponding to the blood vessel portion is depicted darkly. Thereby, the average value of the pixel values in the frame decreases. Since the wire image is specified by the wire specifying unit 41, only the wire image and a pixel group in the vicinity of the wire image may be used as an object for calculating the average value.

  In addition, in a frame that has been subjected to appropriate image processing (for example, enhancement processing of a wire image), a shadow due to a contrast agent is clearly depicted. There is no significant change in the image area other than the blood vessel area. That is, when a contrast agent enters the blood vessel, the variation of pixel values (statistics such as dispersion and standard deviation) in the frame increases. Since the wire image is specified by the wire specifying unit 41, only the wire image and the pixel group in the vicinity of the wire image may be used as a target for calculating the variation.

  Considering the above, the acquisition timing detection unit 61 according to the third configuration can be configured as follows. To the acquisition timing detection unit 61, frames subjected to affine transformation are sequentially input from the alignment processing unit 43. The acquisition timing detection unit 61 calculates a predetermined statistic of the pixel value in the pixel group for each input frame. This predetermined statistical value may be an average value or a variation (variance, standard deviation, etc.). The acquisition timing detection unit 61 stores sequentially calculated statistics in time series.

  When the average value is calculated, the acquisition timing detection unit 61 compares the past average value that has already been stored with the newly calculated average value, and the new average value decreases compared to the past. Judgment is made. This determination processing is executed, for example, by determining whether the new average value is lower than a predetermined threshold value with respect to the past average value with respect to the new average value and a predetermined number of average values in the past. . When the new average value has decreased by a predetermined threshold value or more, the acquisition timing detection unit 61 determines that this is the acquisition timing of the contrast blood vessel image. That is, the acquisition timing detection unit 61 monitors the average value of the pixel values of sequentially acquired frames to detect a sudden decrease in the average value, and operates so that this detection timing is used as the acquisition timing of the contrast blood vessel image. To do. When the acquisition timing is detected, the acquisition timing detection unit 61 notifies the contrasted blood vessel image forming unit 62 to that effect.

  On the other hand, in the case where a variation (dispersion) is calculated, the acquisition timing detection unit 61 compares the previously stored past variance with the newly calculated variance, and the new variance is compared with the past. Determine if it is rising. This determination process is executed, for example, by determining whether the new variance is higher than a predetermined threshold with respect to the past variance for the new variance and a predetermined number of variances in the past. When the new variance increases by a predetermined threshold value or more, the acquisition timing detection unit 61 determines that this is the acquisition timing of the contrast blood vessel image. That is, the acquisition timing detection unit 61 operates to monitor the dispersion of the pixel values of sequentially acquired frames to detect a rapid increase in the dispersion, and use this detection timing as the acquisition timing of the contrast blood vessel image. When the acquisition timing is detected, the acquisition timing detection unit 61 notifies the contrasted blood vessel image forming unit 62 to that effect.

  The contrast blood vessel image forming unit 62 is an example of the “contrast blood vessel image forming unit” of the present invention, and operates in response to the notification from the acquisition timing detection unit 61. The contrast blood vessel image forming unit 62 executes the following processing, for example. As the first processing, the contrast-enhanced blood vessel image forming unit 62 selects a frame corresponding to the detected acquisition timing, that is, a frame in which an abrupt decrease in average value (or an abrupt increase in variation) is detected. Recording (capture) as an image. In this captured frame (capture frame), the blood vessel region is clearly depicted by the contrast effect. Here, the capture frame needs to be a frame that has been aligned.

  The first process has an advantage of ease, but also has the following drawbacks. That is, since the contrast agent released into the blood vessel does not immediately mix with blood, muscular irregularities may occur in the contrasted blood vessel image. In general, the strength of the contrast effect (that is, shading) is accompanied by temporal fluctuation. Therefore, there is a possibility that an optimal contrasted blood vessel image cannot be obtained with only one frame as in the first process.

  In order to deal with such a problem, a contrast blood vessel image forming unit 62 selects a series of frames obtained within a predetermined period including the detected acquisition timing and combines them to form a contrast blood vessel image. Can be configured. These series of frames are each after affine transformation.

  As a method for forming a single contrast blood vessel image from a series of frames, there is a method of forming a minimum value image to obtain a contrast blood vessel image. A minimum value image is formed by associating pixels in a series of frames according to positions, selecting the minimum value of the pixel values of the pixels at each position, and assigning the selected minimum value to the pixel. This is an image. In this method, it is important to use a frame after affine transformation in order to suppress pixel positional deviation.

  Furthermore, considering that a contrasted blood vessel image is sufficient if the blood vessel region is clearly depicted, noise reduction processing such as smoothing processing or quantization processing is performed on each frame (or the minimum value image) to be strong. It is desirable to improve visibility by reducing noise.

  In addition, it is desirable to devise measures so that the wire image depicted in the contrasted blood vessel image is not confused with the wire image in the overlapping partner moving image. As an example of this contrivance, a regular pattern (hatching, polka dots, checkerboard, etc.) can be added to the wire image in the contrast-enhanced blood vessel image and displayed translucently.

  The operation of the X-ray fluoroscopic apparatus according to this embodiment will be described. An example of the operation is shown in FIG. When receiving an instruction to start the motion suppression function (S61), the wire specifying unit 41 specifies the image of the wire in the acquired frame (S62). Next, the alignment unit 43 obtains an affine transformation based on the specified wire image and performs alignment between frames (S63).

  The acquisition timing detection unit 61 executes the process for detecting the acquisition timing of the contrasted blood vessel image as described above together with the start of the motion suppression function (S61). Until the acquisition timing is detected (S64, No), the frames to which the affine transformation is applied are sequentially displayed on the display unit 31 (S65: S70, No: S71, Yes) as in the first embodiment. : S72). Thereby, a wire tracking moving image depicting the inside of the subject 1 is displayed.

  When the acquisition timing is detected (S64, Yes), the contrast blood vessel image forming unit 62 forms a contrast blood vessel image based on the frame corresponding to the detection timing (or a series of frames including this) (S68). . This contrast-enhanced blood vessel image (capture frame) is acquired after the alignment (step S63) is started. When the acquisition timing is detected, the contrasted blood vessel image is not superimposed and displayed (S66, No), and the process proceeds from step 64 to step 68.

  The system control unit 21 causes the contrast blood vessel image formed in step 68 to be superimposed and displayed on the frame to which the affine transformation is applied in step 63 via the display control unit 24 (S69). Then, the processing shifts to the next frame (S70, No: S71, Yes: S72).

  For the next frame, the image processing unit 23 specifies an image of the wire (S62), performs affine transformation, and aligns the frames (S63). The acquisition timing has been detected (S64, Yes). The image processing unit 23 determines whether the frame after application of the affine transformation and the contrasted blood vessel image are displayed in a superimposed manner, that is, whether a contrasted blood vessel image has already been formed (S66). This is because the contrast blood vessel image is not formed before the processing of the next frame due to the calculation ability of the contrast blood vessel image forming unit 62 and the like.

  When it is determined that the image is not yet superimposed (S66, No), the contrast blood vessel image forming unit 62 continues the formation process of the contrast blood vessel image (S68). In this example of operation, this process is repeated until superimposed display is performed.

  If it is determined in step 66 that the superimposed display has already been made (S66, Yes), the system control unit 21 switches the frame currently being processed (after applying the affine transformation) via the display control unit 24. Displayed (S67). This switching display is as follows. The display mode immediately before the switching display is such that the contrasted blood vessel image is superimposed on the frame immediately before the frame currently being processed. In this switching display, the frame currently being processed is displayed, and the contrasted blood vessel image is displayed superimposed on this frame. At this time, the contrast-enhanced blood vessel image displayed in a superimposed manner is the same still image. As a result, an image in which the same contrast blood vessel image is superimposed and displayed on the wire tracking moving image in which the frames are sequentially switched is observed. That is, an image in which a contrasted blood vessel image that is a still image is superimposed on the wire tracking moving image is observed.

  This switching display can be realized, for example, by forming a superimposed image of each frame and the contrasted blood vessel image each time and displaying it sequentially. In addition, this switching display sets the first layer for displaying the frame and the second layer for displaying the contrasted blood vessel image, and continuously displays the contrasted blood vessel image on the second layer. This can also be realized by sequentially switching the frames to be displayed on the layer.

  Since Steps 70 and 71 are the same as Steps 10 and 11 of the first embodiment, description thereof will be omitted.

  The images displayed in the above operation example will be described with reference to FIGS. FIG. 19 shows the frame F after applying the affine transformation. In the frame F, a catheter image C ′ and a wire image C are depicted. FIG. 20 shows a contrasted blood vessel image V. In the contrasted blood vessel image V, an image depicting the shape of the blood vessel, that is, a shadow Va by the contrast agent is depicted. In the above operation example, the frame F and the contrasted blood vessel image V are superimposed and displayed. The display mode is shown in FIG. That is, in FIG. 21, the shadow Va of the blood vessel is displayed so as to overlap the images C and C ′ depicted in the frame F. The frame F is updated and displayed at a predetermined frame rate.

  According to this embodiment, a contrast blood vessel image can be superimposed and displayed on a wire tracking moving image displayed in real time. The contrasted blood vessel image is a static image, but as described above, the relative positional relationship between the blood vessel region and the contrasted blood vessel image in the frame after the application of the affine transformation is almost unchanged. The relative positional relationship between the region and the contrasted blood vessel image is also almost unchanged. Therefore, by grasping the position of the blood vessel shown in the contrasted blood vessel image, the position of the blood vessel in the wire tracking moving image can be almost grasped. Therefore, the surgeon can grasp the position and state of the wire and further perform an operation while using the blood vessel shown in the contrasted blood vessel image as a mark.

  The contrasted blood vessel image is merely a guide. What the operator should pay attention to is the wire tracking video. Therefore, it is desirable to display a contrasted blood vessel image so as not to hinder the observation of the wire tracking moving image. It is also necessary to avoid misunderstanding that the contrasted blood vessel image is a part of the wire tracking moving image.

  For example, it is possible to display a contrasted blood vessel image in color and translucent by adding a predetermined display color to pixels corresponding to the contrasted blood vessel image. At this time, the gray value of the pixel represents an X-ray image at the current time, and the color represents a contrasted blood vessel image taken in the past. When selecting the display color, avoid white, black, gray and similar colors and avoid highly saturated colors (eg red, blue, green, yellow, etc.) so as not to interfere with the observation of the X-ray image at the current time. It is desirable to use a very thin color.

  Needless to say, the above processing of this embodiment is combined with the second embodiment in order to display a contrasted blood vessel image in the partial moving image. At this time, the image processing unit 23 cuts out a partial image (partially contrasted blood vessel image) of the contrast-enhanced blood vessel image within the trim frame set in the frame corresponding to the acquisition timing, The enlarged image of the partial image in the trim frame in the acquired frame is superimposed and displayed. Thereby, it is possible to display a partial contrast-enhanced blood vessel image superimposed on the partial moving image.

  There are cases where it is desired to re-take a contrasted blood vessel image, such as when the contrasted blood vessel image displayed in a superimposed manner is inappropriate. In such a case, a predetermined operation is performed to cancel the superimposed display of the contrasted blood vessel image to display only the moving image, and then the same operation and processing as in the above operation example are executed to display a new contrasted blood vessel image superimposed. Can be made.

  For example, there is a case where it is desired to cancel the display of the contrasted blood vessel image when the contrasted blood vessel image hinders observation of the moving image. In addition, there is a case where it is desired to display again the contrasted blood vessel image once released in order to confirm the target for advancing the wire. For this purpose, it is desirable that the display / non-display of the contrasted blood vessel image can be switched by a predetermined operation. When the superimposed display is canceled, the contrasted blood vessel image is stored in preparation for a redisplay instruction. In addition, a new contrast blood vessel image may be formed in response to a re-display instruction and superimposed on the moving image.

  As described above, the contrast-enhanced blood vessel image is an image representing the form of blood vessels in (at least) a region near the current position of the wire. This contrasted blood vessel image is an example of the “blood vessel image” of the present invention.

<Fifth Embodiment>
In the fourth embodiment, when a still image is superimposed on a wire tracking moving image, the relative positional relationship between the blood vessel region and the still image in the wire tracking moving image (each frame thereof) is substantially unchanged. Using this, the contrasted blood vessel image was used as a still image and superimposed on the moving image. However, the still image superimposed and displayed on the wire tracking moving image is not limited to the contrasted blood vessel image.

  In this embodiment, a predetermined geometric figure is superimposed and displayed on the wire tracking moving image. As an example thereof, as shown in FIG. 22, a grid pattern M is superimposed and displayed on the partial moving image in the trim frame R. In each frame of the partial moving image, a catheter image C ′, a guide wire image C, and other human tissue images are displayed. The lattice-like pattern M can be referred to as a guide for the position when the guide wire is advanced. This makes it easier for the surgeon to grasp and memorize the target position for advancing the guide wire.

  Of course, other similar geometric figures can be superimposed and displayed on the wire tracking moving image (partial moving image).

  Examples of the process for displaying such a geometric figure include the following. An image depicting the figure is stored in the storage unit 22 in advance. When receiving the superimposition display instruction, the system control unit 21 reads out the image from the storage unit 22 and causes the wire control moving image to be superimposed and displayed via the display control unit 24. Thereafter, a portion corresponding to the trim frame is cut out, and a partial moving image on which a geometric figure is superimposed is generated. As another processing example, instead of performing the above-described reading, the system control unit 21 responds to an instruction for superimposition display, and the system control unit 21 displays the figure on the display screen of the display unit 31 on which the partial moving image is displayed. It is also possible to realize the desired superimposed display by drawing.

<Sixth Embodiment>
In this embodiment, a case will be described in which an image different from the fourth and fifth embodiments is displayed superimposed on the wire tracking moving image. As described above, since the relative positional relationship between the blood vessel region and the still image in the wire tracking moving image (each frame) is almost unchanged, it is possible to display an arbitrary still image superimposed on the moving image. .

  In the fourth embodiment, a contrast-enhanced blood vessel image acquired while performing catheterization under X-ray fluoroscopy is superimposed and displayed on a wire tracking moving image. In contrast, in this embodiment, a case will be described in which a blood vessel image formed in advance is displayed superimposed on a wire tracking moving image. The blood vessel image is an image representing the shape of the blood vessel, and in particular, an image representing the shape of the blood vessel in the region near the current position of the wire.

  Examples of blood vessel images include the following: (1) An image of a blood vessel drawn, such as an anatomical chart or a sketch by an operator, digitized by a scanner or the like, or a blood vessel drawn by a drawing application software (2) Two-dimensional blood vessel image acquired by prior examination using a medical image diagnostic apparatus such as a contrast X-ray imaging apparatus; (3) X-ray CT apparatus, MRI, biplane X-ray imaging apparatus, etc. 3 A two-dimensional blood vessel image obtained by rendering a three-dimensional blood vessel image (volume data describing a three-dimensional structure of a blood vessel) formed by a prior examination using a medical image diagnostic apparatus capable of three-dimensional imaging.

  Among these, for (1) and (2), the target image is stored in the storage unit 22 in advance, and the system control unit 21 that has received an instruction for superimposed display reads it and displays it on the moving image. Just do it. The alignment between the blood vessel image and the moving image may be automatically performed by pattern recognition processing or the like, or may be manually performed using the operation unit 32. In such a configuration, the storage unit 22 is an example of the “storage unit” of the present invention. Hereinafter, (3) will be described in detail.

  A method of forming a three-dimensional blood vessel image using an X-ray CT apparatus or MRI is known. Further, it is also known to process a three-dimensional blood vessel image by manual operation or the like and add additional information such as a treatment plan chart. The three-dimensional blood vessel image obtained in this way is expressed as a geometric figure defined by a coordinate system based on a couch top such as an X-ray CT apparatus.

  A technique for generating a three-dimensional blood vessel image using a pair of contrast images taken by a biplane X-ray imaging apparatus is also known. This three-dimensional blood vessel image may be used. In particular, the function according to the present invention can be provided in the biplane X-ray imaging apparatus. Thereby, it is possible to generate a three-dimensional blood vessel image from a pair of images obtained by photographing the patient currently undergoing fluoroscopy in the same posture, and to execute the processing according to this embodiment using the three-dimensional blood vessel image. .

  Although the three-dimensional blood vessel image itself is stored as digital data, even if it is displayed on the screen as it is, the structure of the blood vessel cannot be visually recognized. Therefore, it is necessary to form a two-dimensional image representing the appearance when the blood vessel structure is observed from a predetermined direction, based on the three-dimensional blood vessel image, and then display the image on the screen. This process is generally called “rendering”. Therefore, whatever the 3D blood vessel image is, the result of rendering is a 2D image as computer graphics. Note that the above observation direction in rendering is referred to as a “viewpoint”.

  In this embodiment, a two-dimensional image as computer graphics obtained by rendering is displayed as a blood vessel image superimposed on the wire tracking moving image. When this blood vessel image is stored in the storage unit 22 in advance and is read out and superimposed on the wire tracking moving image, it is the same as the case (2) above. In the following, a case will be described in which a three-dimensional blood vessel image is stored in the storage unit 22, is rendered as needed to form a two-dimensional image, and the two-dimensional image is superimposed on the wire tracking moving image.

  The viewpoint in rendering needs to be set appropriately. As the simplest method, a standard viewpoint can be determined in advance, and rendering can be performed by observing a three-dimensional blood vessel image from the standard viewpoint. However, as described below, it is possible to form a blood vessel image that is more suitable for the wire tracking moving image by taking advantage of the fact that a three-dimensional blood vessel image is obtained.

  FIG. 23 shows a configuration example of the characteristic part of the X-ray fluoroscopic apparatus according to this embodiment. The storage unit 22 stores a three-dimensional blood vessel image G formed in advance in advance. The three-dimensional blood vessel image G represents the three-dimensional form of the blood vessel of the subject 1, and is an example of the “three-dimensional image” of the present invention.

  The image processing unit 23 includes a viewpoint determination unit 71, a rendering unit 72, and an image adjustment unit 73 in addition to the wire specifying unit 41 and the alignment processing unit 43 similar to those in the first embodiment.

  The viewpoint determination unit 71 determines a viewpoint for rendering the three-dimensional blood vessel image G. This process is executed as follows, for example. Hereinafter, a case where the X-ray fluoroscopic apparatus is configured as an IVR-CT (Interventional Radiology-Computed Tomography) apparatus will be described. The IVR-CT apparatus is a combination of an X-ray fluoroscopy apparatus and an X-ray CT apparatus.

  The IVR-CT apparatus is provided with a constituent part as the X-ray fluoroscopic apparatus shown in FIG. 1 and a constituent part as an X-ray CT apparatus (not shown). Since the X-ray CT apparatus is well known, its configuration will be briefly described below. The X-ray CT apparatus includes a couch device having a top plate, an X-ray scanning gantry, and an arithmetic control device. In the IVR-CT apparatus, the top plate for the X-ray fluoroscopic apparatus and the top board for the X-ray CT apparatus are the same. The arithmetic and control unit may be the same as the arithmetic and control unit 20 in FIG. 1 or may be provided as a separate unit.

  In the IVR-CT apparatus, catheterization under fluoroscopy is performed immediately after the examination with the X-ray CT apparatus, and a three-dimensional blood vessel image G is obtained by the X-ray CT apparatus. In the IVR-CT apparatus, when performing catheterization under fluoroscopy immediately after the examination with the X-ray CT apparatus, the subject lies on the top board in the same posture without getting off the top board.

  The viewpoint determination unit 71 uses the focal position of the X-ray tube 4 when performing catheterization under X-ray fluoroscopy as a viewpoint. Here, the focal position of the X-ray tube 4 is a position where electrons output from the cathode of the X-ray tube 4 collide with the target (anode) and generate X-rays.

  A specific example of processing for determining the viewpoint will be described. When performing catheterization under X-ray fluoroscopy, the X-ray tube 4, the X-ray diaphragm and the X-ray detector 6 are positioned so that an image of an area including the affected part of the subject 1 can be obtained. The movement of the X-ray tube 4 or the like is controlled by the system control unit 21, whereby the system control unit 21 recognizes the position of the X-ray tube 4 or the like. The viewpoint determination unit 71 receives position information of the X-ray tube 4 from the system control unit 21 and obtains a focal position as a viewpoint.

  Next, as in the case where the 3D blood vessel image G is formed by another medical image diagnostic apparatus, the posture of the subject 1 in the examination for acquiring the 3D blood vessel image G and the subject in the catheterization under fluoroscopy A case where the posture of the specimen 1 is different will be described. Even in this case, the viewpoint can be appropriately determined by the simple alignment as described below.

  When acquiring a three-dimensional blood vessel image G with another medical image diagnostic apparatus (not shown), the subject 1 is placed on the top 2A of the medical image diagnostic apparatus as shown in FIG. As usual, the medical image diagnostic apparatus defines a position using a unique three-dimensional coordinate system (X, Y, Z) having a predetermined reference position of the top 2A as an origin. That is, the position of the three-dimensional blood vessel image G is expressed as a coordinate value in a three-dimensional coordinate system unique to the medical image diagnostic apparatus of the blood vessel T to be imaged.

  X-ray fluoroscopic catheterization is performed by the X-ray fluoroscopic apparatus according to this embodiment. As shown in FIG. 25, the subject 1 is placed on the top 2. At this time, it is desirable to instruct the subject 1 to take the same posture as when the three-dimensional blood vessel image G is acquired.

  Further, the top plate 2, the X-ray tube 4, and the X-ray are set so that the focal position of the X-ray tube 4 and the position and direction of the X-ray detector 6 are known in a three-dimensional coordinate system unique to other medical image diagnostic apparatuses. A detector 6 is arranged. For example, the top plate 2 and the X-ray tube 4 so that a straight line connecting the focal position of the X-ray tube 4 and the center line of the X-ray detector 6 is vertical and the blood vessel T is depicted in the center of the fluoroscopic image. The position of the X-ray detector 6 is adjusted.

  In this way, it is possible to associate the position of the subject 1 on the top 2A of another medical image diagnostic apparatus with the position of the subject 1 on the top 2 of the X-ray fluoroscopic apparatus. . That is, a three-dimensional coordinate system (X ′, Y ′, Z ′) is also defined for the top 2 and the subject 1 is arranged at a position where the same blood vessel T can be imaged by both apparatuses. Therefore, the coordinate value of the blood vessel T expressed in the three-dimensional coordinate system (X, Y, Z) and the coordinate value of the blood vessel T expressed in the three-dimensional coordinate system (X ′, Y ′, Z ′) Can be associated with each other.

  As described above, a fluoroscopic image representing how the three-dimensional blood vessel image G appears when the current focal position of the X-ray tube 4 is used as a viewpoint is obtained although the accuracy is somewhat inferior. As described above, the X-ray tube 4 and the X-ray detector 6 are arranged to face each other in a substantially vertical direction with respect to the top 2 on which the subject 1 is placed. The viewpoint determination unit 71 employs the focal position of the X-ray tube 4 at this time as a viewpoint.

  The rendering unit 72 renders the three-dimensional blood vessel image G using the viewpoint determined by the viewpoint determination unit 71 to form a two-dimensional blood vessel image. The rendering process at this time has been described above.

  The image adjustment unit 73 adjusts the enlargement ratio and position of the two-dimensional blood vessel image so as to be superimposed on the wire tracking moving image. This process may be performed manually or automatically.

  When performing manually, the system control unit 21 causes the display unit 31 to display the wire tracking moving image and the two-dimensional blood vessel image via the display control unit 24. At this time, the wire tracking moving image and the two-dimensional blood vessel image may be displayed in an overlapping manner or may be displayed side by side. In any case, it is sufficient to display so that the display sizes of both images can be visually recognized and compared. An operator or the like adjusts the enlargement ratio and position of the two-dimensional blood vessel image by performing a predetermined operation using the operation unit 32. In response to this operation, the image adjustment unit 73 adjusts the enlargement ratio and position of the two-dimensional blood vessel image, and the adjustment result is displayed on the display unit 31. Note that the position is adjusted by parallel movement and / or rotational movement. In addition, if it is impossible to determine whether the superposition state is just based on the wire image, it is determined whether the real-time blood vessel image contrasted by injecting a contrast medium into the blood vessel from a catheter or the like and the blood vessel image are aligned. Can adjust the superposition position.

  A case where the two-dimensional blood vessel image is automatically adjusted will be described. The enlargement ratio can be calculated based on the current position information of the X-ray tube 4 and the X-ray detector 6. That is, since the X-ray 7 output from the X-ray tube 4 travels while enlarging its cross section and is projected onto the X-ray detector 6, the cross-sectional enlarged state (angle, solid angle) and the X-ray This is because the imaging magnification is determined according to the distance between the tube 4 and the X-ray detector 6.

  Note that the imaging magnification varies depending on the distance between the anatomical structure (blood vessel T or the like) to be imaged and the X-ray tube 4, but the same anatomical structure was imaged in both the two-dimensional blood vessel image and the fluoroscopic image. This is not necessary. Also, the operator wants to observe a wire tracking moving image, and the two-dimensional blood vessel image is merely a mark for confirming the state of a nearby blood vessel, so it is not necessary to obtain the enlargement rate so strictly.

  Here, the case where a two-dimensional blood vessel image based on the three-dimensional blood vessel image G is handled has been described. However, for a two-dimensional blood vessel image obtained by imaging the inside of the subject 1 with a contrast X-ray imaging apparatus, a contrast X-ray imaging apparatus is used. The magnification can be calculated based on the position of the X-ray tube at the time of imaging with X-ray and the position of the X-ray tube 4 at the time of imaging with the X-ray fluoroscope.

  It is also possible to adjust the enlargement ratio and position by executing the pattern matching process.

  Once the adjustment is made, the position of the blood vessel in the real-time wire tracking moving image (but not visible unless contrasted) and the two-dimensional blood vessel image are used unless the positions of the X-ray tube 4 and the X-ray detector 6 are changed thereafter. Means that the surgeon can advance the guide wire while grasping the position of the blood vessel with reference to the two-dimensional blood vessel image.

  Furthermore, even if the positions of the X-ray tube 4 and the X-ray detector 6 are changed, the blood vessel image can be configured to continue to overlap the wire tracking moving image. That is, once the blood vessel image and the wire tracking moving image are aligned as described above, the operator or the like then images the affected part from different directions by rotating the C arm 3 or the like. The direction taken first is referred to as a “first direction”, and the different direction is referred to as a “second direction”.

  Then, a positional shift may occur between the blood vessel image and the wire tracking moving image. As shown in FIG. 26, this positional deviation occurs when there is a positional deviation γ along the first direction β1 between the actual blood vessel T and the virtual position T ′ of the blood vessel T in the three-dimensional image. FIG. 27A shows the wire tracking moving image δ1 viewed from the first direction β1, and FIG. 27B shows the wire tracking moving image δ2 viewed from the second direction β2.

  Accordingly, by observing the wire tracking moving image from the second direction β2 and moving the virtual position of the three-dimensional image along the first direction β1, the first direction β1 as shown in FIG. Even if the image is taken from the second direction β2 (not only an arbitrary direction), the blood vessel image and the wire tracking moving image are aligned.

  Moreover, in the biplane X-ray imaging apparatus equipped with the function according to the present invention, since imaging can be performed from two directions at the same time, the imaging from the two directions as described above and the position adjustment between the images using them can be performed using the C-arm. Needless to say, it is not necessary to divide 3 into two parts by rotating 3 or the like.

  In this embodiment, the case where the enlargement ratio and position of the two-dimensional blood vessel image are adjusted has been described. However, the wire tracking moving image (the frame thereof) may be adjusted. Generally, it is only necessary that the enlargement ratio and position can be relatively adjusted between the wire tracking moving image and the two-dimensional blood vessel image. However, since the two-dimensional blood vessel image is superimposed and displayed where the wire tracking moving image is already displayed in real time, it may be difficult to see if the size or position of the wire tracking moving image is changed. Therefore, as described above, it is considered desirable to adjust the two-dimensional blood vessel image side.

<Seventh Embodiment>
In the sixth embodiment, the configuration in which a two-dimensional blood vessel image obtained by rendering a three-dimensional blood vessel image acquired in advance by X-ray CT or MRI is displayed in a superimposed manner on the wire tracking moving image has been described in detail. In this case, another useful function can be realized. In this embodiment, an X-ray fluoroscopic apparatus capable of realizing this useful function will be described. The X-ray fluoroscopic apparatus according to this embodiment has the same configuration as that of the sixth embodiment.

  By adjusting the enlargement ratio and position for superimposed display, the position in the two-dimensional blood vessel image corresponding to an arbitrary part (particularly, the tip image) of the wire image in the wire tracking moving image can be known. Accordingly, as shown in FIG. 29, the position Q of the wire tip image in the wire tracking moving image (frame F) corresponds to a straight line L connecting the viewpoint P and a specific position Q ′ in the three-dimensional blood vessel image G. ing. In FIG. 29, symbol Ga represents a blood vessel image depicted in the three-dimensional blood vessel image G. A symbol Ta represents a blood vessel image depicted in a two-dimensional blood vessel image superimposed on the wire tracking moving image (frame F). In FIG. 29, the three-dimensional blood vessel image G is arranged at a virtual position.

  Thus, it can be considered that the position Q ′ closest to the straight line L in the blood vessel image Ga in the three-dimensional blood vessel image G corresponds to the position Q of the tip image of the wire. Therefore, rendering is performed when the three-dimensional blood vessel image G is viewed from another viewpoint to form another two-dimensional blood vessel image, and the position of the tip image of the wire in the other two-dimensional blood vessel image is specified and displayed. It is possible. This function is called a three-dimensional tracking function.

  In the three-dimensional tracking function, in addition to the processing according to the sixth embodiment, rendering corresponding to each of the two viewpoints is performed on the three-dimensional blood vessel image G to form two two-dimensional blood vessel images. The position of the tip image of the wire is displayed on the top. Thereby, images as shown in FIGS. 30 and 31 are displayed.

  FIG. 30 shows a display mode of the wire tracking moving image (frame F). In this wire tracking moving image, the catheter image C ′ and the wire image C are depicted as described above. Furthermore, as described in the sixth embodiment, a two-dimensional blood vessel image T1 and a tip position image Q1 are superimposed and displayed on this wire tracking moving image. The two-dimensional blood vessel image T1 is obtained by rendering the three-dimensional blood vessel image G with respect to the first viewpoint. The tip position image Q1 is an image representing the position of the tip image of the wire.

  As shown in FIG. 31, a tracking screen 31 a for displaying an image based on the three-dimensional tracking function is displayed on the display unit 31. The tracking screen 31a is displayed side by side with the wire tracking moving image shown in FIG. Two two-dimensional images T1 and T2 are displayed side by side on the tracking screen 31a. The two-dimensional image G1 is obtained by rendering the three-dimensional blood vessel image G for the first viewpoint as described above. On the other hand, the two-dimensional image T2 is obtained by rendering the three-dimensional blood vessel image G from a second viewpoint different from the first viewpoint. Furthermore, tip position images Q1 and Q2 are displayed on the two-dimensional images T1 and T2, respectively.

  By performing such a display, the surgeon can grasp the shape of the blood vessel viewed from different directions while observing the wire tracking moving image, and can clearly determine where the tip of the wire is located in the blood vessel. I can grasp it.

  Thus, when displaying the two-dimensional blood vessel images T1 and T2 from two viewpoints, it is particularly effective when the two viewpoints are set to be orthogonal to each other. One of these two viewpoints (the first viewpoint in the above example) is the same viewpoint as when the wire tracking moving image (frame F) is captured. By displaying the two-dimensional blood vessel images T1 and T2 from two viewpoints orthogonal to each other in this way, it is possible to easily grasp the positional relationship in the depth direction that cannot be understood from the two-dimensional blood vessel image and the wire tracking moving image from one viewpoint. It becomes possible to do. It is also possible to form and display three or more two-dimensional blood vessel images corresponding to three or more different viewpoints.

  According to the three-dimensional tracking function described in this embodiment, it is possible to grasp where the current position of the tip portion of the wire is in the three-dimensional blood vessel image.

  Since the 3D blood vessel image is created based on the 3D medical image of the subject, if one point in the 3D blood vessel image is designated, this point is the point in the original 3D medical image. Whether to correspond to is automatically determined. Therefore, in this embodiment, the point corresponding to the current position of the distal end portion of the wire can be displayed in various images based on the three-dimensional medical image. Examples of the image based on the three-dimensional medical image include a tomographic image, an MPR (Multiplanar Reconstruction) image, a volume rendering image, and a surface rendering image. Thereby, a function similar to that of a known surgical navigator can be provided. The operation navigator presents a three-dimensional position of an affected area and its surrounding tissues during an operation.

  This function can also be used as a surgical navigator device. For this purpose, an interface (operation unit 32) capable of inputting spatial coordinates online and in real time is provided. In use, a three-dimensional image of a subject is input in advance as in a normal surgery navigator. Then, the coordinate information of the position in the three-dimensional medical image corresponding to the current position of the tip of the wire is input to the surgery navigator device online in real time. Thereby, the function can be applied to the surgery navigator device.

  In addition to pointing out the problems that can occur in the three-dimensional tracking function, the solution is presented. When the three-dimensional tracking function is performed, there is no problem as long as there is one point in the three-dimensional blood vessel image that intersects the straight line L as shown in FIG.

  However, there may be a case where there are a plurality of points in the three-dimensional blood vessel image that intersect with the straight line L. An example is shown in FIG. In the three-dimensional blood vessel image G, a blood vessel image Gb is depicted. A two-dimensional blood vessel image depicting the blood vessel image Tb is superimposed and displayed on the wire tracking moving image (frame F). A straight line L connecting the viewpoint P and the position D on the blood vessel image Tb intersects the blood vessel image Gb of the three-dimensional blood vessel image G at two positions E1 and E2. Then, when the tip portion of the wire exists at the position D, the position corresponding to the position D cannot be uniquely specified. Whether or not this problem has occurred can be determined by determining whether or not a plurality of positions in the three-dimensional blood vessel image G corresponding to the position D have been obtained.

  Even in such a case, the biplane X-ray imaging apparatus equipped with the function according to the present invention can perform imaging from two directions at the same time, so it is determined whether the position corresponding to the position D is E1 or E2. Because it can, it does not matter. However, this is a problem in an apparatus having only one X-ray source and one X-ray detector and capable of imaging at the same time only from a single direction (such as having a normal C-arm).

  In order to deal with such a problem, for example, the following method can be taken. It is assumed that at the present time, the above-described problem occurs and a plurality of positions E1, E2,... In the three-dimensional image correspond to the positions of the tip images of the wires. This viewpoint is referred to as a first viewpoint. An image rendered with respect to the first viewpoint and superimposed on the moving image is referred to as a first two-dimensional blood vessel image.

  The viewpoint determination unit 71 obtains a second viewpoint different from the first viewpoint (for example, a viewpoint orthogonal to the first viewpoint). The rendering unit 72 renders the three-dimensional blood vessel image G for the second viewpoint to form a second two-dimensional blood vessel image. The image adjustment unit 73 adjusts the position of the second two-dimensional blood vessel image.

  The image processing unit 23 obtains a position corresponding to the distal end portion of the wire in each two-dimensional blood vessel image based on the position information of the wire image specified by the wire specifying unit 41. This process is executed as follows, for example. First, the tip portion of the wire image in one of the plurality of frames constituting the moving image is identified based on the identification result by the wire identification unit 41. Next, a position in the first two-dimensional image corresponding to the tip portion is specified. Subsequently, a position in the three-dimensional blood vessel image G corresponding to the specific position in the first two-dimensional image is specified. Then, a position in the second two-dimensional image corresponding to the specific position in the three-dimensional blood vessel image G is specified. The image processing unit 23 that executes such processing is an example of the “position specifying unit” of the present invention.

  The system control unit 21 displays the first and second two-dimensional blood vessel images on the tracking screen 31a. Furthermore, the system control unit 21 displays all the positions obtained by the image processing unit 23 on each two-dimensional blood vessel image.

  A display example at this time is shown in FIG. One tip position image H1 is displayed in the first two-dimensional blood vessel image K1. Two tip position images J1 and J2 are displayed in the second two-dimensional blood vessel image K2. In this case, it is unknown whether the position corresponding to the tip position image H1 is the tip position image J1 or J2. However, the above problem is solved by manipulating the wire and moving it back and forth to change the number of displayed tip position images.

  Another solution to the above three-dimensional tracking problem will be described with reference to FIG. In FIG. 34, for a straight line L passing through the position Wa of the tip image of the wire image C and the viewpoint P, the straight line L intersects with the blood vessel image Gb of the three-dimensional blood vessel image G at two points E1 and E2. Yes.

  The image processing unit 23 selects not only the position Wa of the tip image in the wire image C but also a position D ′ corresponding to another part of the wire image C. This process is executed based on the identification result by the wire identification unit 41. The position to be selected is arbitrary, but as an example, a position away from the front image by a predetermined distance or a rear end position can be selected.

  Next, the image processing unit 23 specifies a position in the blood vessel image Tb in the two-dimensional blood vessel image corresponding to the selected position D ′. Since the two-dimensional blood vessel image is superimposed on the wire tracking moving image (frame F), the position can be easily specified based on the image alignment result. This specific position is also represented by the symbol D ′.

  Furthermore, the image processing unit 23 specifies a position E3 in the three-dimensional blood vessel image G corresponding to the position D ′. Even when the above-described problem occurs in the tip image of the wire, the position in the three-dimensional blood vessel image G is often obtained uniquely for other parts. If a plurality of positions are identified even at this stage, a position corresponding to another part of the wire image C is selected until a position in the three-dimensional blood vessel image G is uniquely obtained. What is necessary is just to repeat said process.

  Subsequently, the image processing unit 23 selects one of the two or more specific positions E1 and E2 based on the position E3 in the specified three-dimensional blood vessel image G. This process can be executed based on, for example, the positional relationship or distance between the positions E1 and E2 with respect to the position E3. Further, by displaying the positions E1, E2, and E3 together with the two-dimensional blood vessel image, the operator or the like may select an appropriate position. Here, it is assumed that E2 is selected.

  Further, the image processing unit 23 specifies a position corresponding to the selected position E2 in the second two-dimensional blood vessel image based on the second viewpoint.

  Other solutions for the above three-dimensional tracking problem are as follows. When the above problem occurs, the image processing unit 23 searches for the latest time point (frame) at which this problem has not occurred in the past.

  That is, the image processing unit 23 specifies the position in the three-dimensional blood vessel image G corresponding to the tip image of the wire for the frames F1 to F (n−1) past the current frame Fn. Then, the image processing unit 23 selects the latest frame in which only one such position is specified in the three-dimensional blood vessel image G from the past frames F1 to F (n−1).

  As shown in FIG. 35, a specific position in the three-dimensional blood vessel image G corresponding to this latest frame is denoted by reference numeral E4.

  Subsequently, the image processing unit 23 calculates the distance between the specific position E4 in the three-dimensional blood vessel image G corresponding to the latest frame and the specific positions E1 and E2 intersecting the straight line L. This distance may be a Euclidean distance based on the three-dimensional coordinate system in which the three-dimensional blood vessel image G is defined, or may be a road along the blood vessel image Gb.

  Furthermore, the image processing unit 23 selects a specific position where the calculated distance is the minimum. In the case shown in FIG. 35, the position E1 is selected. Then, the image processing unit 23 specifies a position corresponding to the selected position E1 in the second two-dimensional blood vessel image based on the second viewpoint.

<Eighth Embodiment>
When an operation is performed using a plurality of wires, images of the plurality of wires may be drawn on the fluoroscopic image at the same time. For example, ablation may be performed for the purpose of treating arrhythmia. At this time, two wires (electrode catheter and ablation catheter) are simultaneously inserted into the blood vessel. The electrode catheter is fixed in a state where its tip is in close contact with the heart wall. The ablation catheter cauterizes a part of the myocardium by applying an electric current with the tip of the ablation catheter placed sequentially at appropriate positions by the operator. In such ablation, the following two cases may occur: (1) When the distal end of the ablation catheter is moved to an appropriate position, the catheter is operated by displaying the ablation catheter in a substantially stationary state. (2) Appropriate target location where the distal end of the ablation catheter should be moved by displaying in a state where the electrode catheter is generally stationary (and thus the movement of the surrounding myocardium is generally stationary) When it is desirable to be able to support the work of judging. At this time, in each of the above embodiments, it is not possible to uniquely determine which wire image is to be processed. In order to solve this problem, the following method can be applied.

  In the first method, an image of the wire closest to the center of the angle of view of the fluoroscopic image is selected. This takes into account that the image of the wire currently being operated is often placed at the center of the display screen.

  In order to realize this method, first, the wire specifying unit 41 determines whether two or more images of the wire have been specified based on the specifying result. This process can be realized, for example, by counting the number of connected components of the specified set of pixels based on the arrangement of the pixels specified as the wire image.

  When two or more wire images are specified, the image processing unit 23 selects the wire image closest to the center of the frame. At this time, it is necessary to calculate the distance between each wire image and the frame center. This distance is defined as follows, for example. First, the distance between each point (each pixel) in the image of each wire and the frame center is calculated. Next, the point which becomes the minimum value among the calculated distances is selected. The minimum value of the distance is set as the distance between the wire image and the frame center. It is also possible to calculate the distance between the tip image of each wire and the frame center and define it as the distance between the wire image and the frame center. The image processing unit 23 that executes this technique is an example of the “first selection means” in the present invention.

  The alignment processing unit 43 performs alignment between frames so as to superimpose images of wires selected from the respective frames. Thereby, a moving image can be displayed based on an appropriate wire image.

  When a wire image in one frame is selected, it is possible to select a wire image in the frame by referring to the position and shape of the wire image for the subsequent frames. Note that the position and shape of the image of the wire are obtained from the result of identification by the wire identification unit 41.

  In the second method, first, alignment is performed for each of a plurality of wire images. The image processing unit 23 calculates the accuracy of alignment in the image of each wire. As the accuracy of this alignment, for example, the deviation amount of the wire image between the frames when the alignment is performed by obtaining affine transformation (parallel movement and rotational movement) is used. As this deviation amount, for example, an image correlation value of the wire image between frames may be used.

  Further, the image processing unit 23 selects an image of a wire having the lowest alignment accuracy. In other words, the second method is to select an image of a wire having the largest time series change that cannot be explained by parallel movement or rotational movement. This is because the wire selected in this way is estimated to have been lowered in alignment accuracy due to advancement, retraction, deformation, etc. caused by the operator performing an operation procedure on the wire. I want to do that because it is in the vicinity of the wire that is just adding manipulation techniques. The image processing unit 23 that executes this technique is an example of the “second selection unit” in the present invention.

  In addition, it is thought that a change of a shape has the most influence as such a time series change. Thus, the selection may be made with reference to the amount that characterizes the shape of the wire image. Examples of such an amount include the curvature of the bent portion, the difference in distance between the position where the curvature is maximum and both ends.

  The alignment processing unit 43 performs alignment between frames so as to superimpose images of wires selected from the respective frames. Thereby, a moving image can be displayed based on an appropriate wire image.

  In the third method, a wire tracking moving image is displayed based on any wire image for the time being. The surgeon observes the displayed wire tracking moving image, and if the wire tracking moving image is acceptable, the surgeon performs the operation as it is.

  On the other hand, when a wire tracking moving image tracking a wire other than the wire that the surgeon wants to see is displayed, the surgeon performs a predetermined operation using the operation unit 32. Upon receiving this operation, the image processing unit 23 processes each frame based on another wire image. Thereby, a wire tracking moving image based on another wire image is newly displayed. Note that switching to another wire image can be easily performed based on the identification result by the wire identification unit 41. The surgeon or the like may repeat the above operation until a wire tracking moving image that tracks the wire to be viewed is displayed.

  In this technique, the operation unit 32 is an example of the “operation unit” of the present invention, and the image processing unit 23 is an example of the “switching unit”.

<Ninth Embodiment>
In each of the embodiments described above, it may be assumed that the identification of the wire image fails or the alignment between frames fails. In that case, an appropriate affine transformation cannot be obtained, and accordingly, an appropriate wire tracking moving image cannot be displayed, or the moving image is disturbed in the middle. However, even in such a case, it is desirable to maintain the state of the wire tracking moving image as much as possible.

  The first method for that purpose is to display the immediately preceding frame F (n−1) without displaying the frame Fn as a wire tracking moving image when the above-described failure occurs in the frame Fn. is there. In this case, the wire tracking moving image stops without changing the displayed image (that is, temporarily freezes), but if the process without the failure is performed, the freeze state is solved. As a result, the wire tracking moving image starts to move. If display is performed at a frame rate of about 10 frames per second, there is no practical problem even if one or two of the frames fail.

  In each of the above embodiments, it is desirable that the frame Fn in which the failure has occurred be handled as if it did not exist and be ignored. That is, when a frame in which the above failure does not occur (for example, frame F (n + 1)) is obtained, this frame F (n + 1) is not the frame Fn in which the failure has occurred, and the failure does not occur. This is because the effect of the function according to the present invention can be maintained because the alignment is performed with respect to the frame F (n-1).

As another method, if the failure in the frame Fn is generated, as a substitute for the affine transformation T _n which has not been calculated, the affine transformation T _(n-1) corresponding to the frame F (n-1) the immediately preceding It is possible to align the frame Fn.

As yet another technique, affine transformations T _(n-1) , T _(n-2) , T _(n-3) , corresponding to a plurality of frames (for example, about several to several tens) immediately before the frame Fn , The affine transformation corresponding to the frame Fn may be estimated and applied. This processing is executed by the image processing unit 23 as “estimating means” of the present invention.

The process for estimating the affine transformation is executed by appropriately applying a known signal processing technique. For example, considering that heartbeats and breathing are performed almost periodically, it is assumed that the fluctuation of the rotation angle θ in the past frame can be approximated by a periodic function using time as a parameter. The image processing unit 23 estimates the fluctuation period based on the temporal change of the rotation angle θ in the past affine transformations T _(n-1) , T _(n-2) , T _(n-3). To do.

Further, the image processing unit 23 extrapolates the waveform of the past rotation angle θ based on the estimated value of the fluctuation period, and estimates the rotation angle θ in the affine transformation T _n .

Similarly, with respect to the parallel movement amounts u and v, based on the same cycle, the past movements based on the past affine transformations T _(n-1) , T _(n-2) , T _(n-3) . translation amount u, v of the waveform by interpolating outside respectively, and estimates the amount of parallel movement u in the affine transformation T _n, v, respectively.

  In addition, while substituting the affine transformation as described above, information indicating that can be displayed on the display unit 31 or notified by voice output.

  Further, if failures occur continuously in a series of frames, there is a risk that the surgeon's concentration may be cut away from the disturbance of the wire tracking moving image. Therefore, it is possible to configure the motion suppression function to stop in response to the failure for a predetermined number of frames. Similarly, it is also possible to configure the motion suppression function to stop in response to failure continuing for a predetermined time.

  This process is executed by the image processing unit 23 as the “stop unit” of the present invention. For this purpose, the image processing unit 23 is provided with a counter that counts the number of times the processing has failed (the number of frames), a timer that counts the time during which the processing has failed continuously, and the like.

  Even when the motion suppression function is stopped, the same moving image (ordinary fluoroscopic image) is displayed as before. At this time, information indicating that the motion suppression function is stopped can be displayed or notified by voice output.

  Further, even when a moving image in which the movement of the wire image is suppressed is not displayed, processing for specifying the wire image or alignment processing may be executed. In that case, it is possible to automatically restart the motion suppression function in response to obtaining an appropriate affine transformation.

DESCRIPTION OF SYMBOLS 1 Subject 2 Top plate 4 X-ray tube 6 X-ray detector 20 Arithmetic control device 21 System control part 22 Storage part 23 Image processing part 24 Display control part 31 Display part 32 Operation part 41 Wire specific part 43 Positioning process part 51 Tip image specifying unit 52 Trim frame position calculating unit 61 Acquisition timing detecting unit 62 Contrast-enhanced blood vessel image forming unit 71 Viewpoint determining unit 72 Rendering unit 73 Image adjusting unit

Claims (20)

X-ray irradiating means for irradiating X-rays toward a subject with a cord-like insertion instrument inserted therein, and X-ray detecting means for detecting the X-rays transmitted through the subject, An X-ray fluoroscopic apparatus that forms and displays a moving image depicting the inside of the subject based on a detection result by a line detection unit,
A specifying means for specifying an image of the insertion instrument in real time from a plurality of frames included in the moving image;
The degree of coincidence between the curve shape of the image of the insertion instrument in one frame of the frames of the moving image and the curve shape of the image of the insertion instrument in the past frame is determined. The alignment processing means for performing the alignment processing of the one frame and the past frame in real time,
Display means for displaying an insertion instrument alignment moving image in which movement of the image of the insertion instrument is suppressed by sequentially displaying the frames processed by the alignment processing means in real time;
An X-ray fluoroscopic apparatus comprising: The alignment processing means performs the alignment by performing parallel movement and / or rotational movement of the one frame so that the degree of coincidence becomes substantially maximum.
The X-ray fluoroscopic apparatus according to claim 1. X-ray irradiating means for irradiating X-rays toward a subject with a cord-like insertion instrument inserted therein, and X-ray detecting means for detecting the X-rays transmitted through the subject, An X-ray fluoroscopic apparatus that forms and displays a moving image depicting the inside of the subject based on a detection result by a line detection unit,
A specifying means for specifying an image of the insertion instrument in real time from a plurality of frames included in the moving image;
Based on the degree of coincidence between the image of the insertion instrument in one of the frames of the moving image and the image of the insertion instrument in a frame earlier than the frame, the alignment of the one frame and the past frame is performed. Alignment processing means for performing processing in real time;
Display means for displaying an insertion instrument alignment moving image by sequentially displaying the frames processed by the alignment processing means in real time;
With
The alignment processing means, for each frame other than the first two frames of the frames of the moving image for a predetermined period, the alignment result with respect to two or more previous frames, the frame and the frame Based on the result of the alignment with the latest frame of the two or more past frames, align the frame with the first frame of the two or more past frames.
X-ray fluoroscopic apparatus characterized by the above. The alignment processing means performs the alignment processing so that the position of the bent portion of the insertion instrument in the image of the insertion instrument in the previous frame substantially coincides with the position of the bent portion of the insertion instrument. ,
The X-ray fluoroscopy device according to any one of claims 1 to 3, wherein X-ray irradiating means for irradiating X-rays toward a subject with a cord-like insertion instrument inserted therein, and X-ray detecting means for detecting the X-rays transmitted through the subject, An X-ray fluoroscopic apparatus that forms and displays a moving image depicting the inside of the subject based on a detection result by a line detection unit,
A specifying means for specifying an image of the insertion instrument in real time from a plurality of frames included in the moving image;
Based on the degree of coincidence between the image of the insertion instrument in one of the frames of the moving image and the image of the insertion instrument in a frame earlier than the frame, the alignment of the one frame and the past frame is performed. Alignment processing means for performing processing in real time;
Display means for displaying an insertion instrument alignment moving image by sequentially displaying the frames processed by the alignment processing means in real time;
With
The alignment processing unit assigns a weight to each point according to the degree of bending at each point of the image of the insertion instrument, evaluates the degree of coincidence based on the weight, and The alignment processing is performed so that the position of the bent portion of the insertion instrument in the image of the insertion instrument and the image of the insertion instrument in the past frame substantially coincide with each other.
X-ray fluoroscopic apparatus characterized by the above. The specifying means specifies the image of the insertion instrument in each of the sequentially acquired frames in real time,
The alignment processing means calculates a parameter for translational and / or rotational movement of the one frame based on sequentially specified images of the insertion tool, and sets the value of the parameter to the magnitude of the parameter value. The X-ray fluoroscopic apparatus according to claim 1, wherein a frame on which the alignment process is started is determined based on the X-ray fluoroscopic apparatus.   3. The X-ray according to claim 2, wherein the alignment processing unit starts the alignment processing at a timing at which movement of a body tissue due to a heartbeat becomes small based on an electrocardiographic signal of the subject. Fluoroscopy device. The alignment processing means includes
A tip section specifying means for specifying, based on the identification result of the image by the specifying unit to the distal end portion of the image of the insertion instrument in each frame of the insertion tool Align moving image,
In order to set a predetermined range of a predetermined size for each of the frames of the moving image, for each frame other than the first frame of the frames of the moving image, the position of the tip portion in the frame and the Changing means for changing the position of the predetermined range in the frame so that the tip portion is included in the predetermined range based on the position of the predetermined range in the past frame;
Including
The display means displays a partial moving image obtained by cutting out an image within the predetermined range from each frame in real time;
The X-ray fluoroscopic apparatus according to any one of claims 1 to 6, wherein The display means simultaneously displays the insertion instrument alignment moving image that has not been changed by the changing means and the partial moving image, and displays an image representing the boundary of the partial moving image as the insertion instrument alignment moving image. Displayed in the image,
The X-ray fluoroscopic apparatus according to claim 8. It said display means superimpose blood vessel image showing the form of the blood vessels in the region near the current position of the insertion instrument into the insertion instrument position location Align moving image,
The X-ray fluoroscopic apparatus according to any one of claims 1 to 9, wherein The display means superimposes and displays a blood vessel image representing a blood vessel shape in a region near the current position of the insertion instrument on the partial moving image.
The X-ray fluoroscopy device according to claim 8 or 9, wherein The blood vessel image is a contrasted blood vessel image based on a frame obtained by the X-ray irradiation means and the X-ray detection means in a state where a contrast agent is injected into the blood vessel of the subject.
The X-ray fluoroscopic apparatus according to claim 10 or 11, wherein Detecting means for detecting the acquisition timing of the contrasted blood vessel image while sequentially acquiring the frames of the moving image by the X-ray irradiation means and the X-ray detection means;
Corresponding to the detection timing being detected by the detecting means, the contrasted blood vessel image forming means for selecting the acquired at least one frame and forming the contrast blood vessel image based on the at least one frame; In addition,
The X-ray fluoroscopic apparatus according to claim 12. The detection means, for each of the sequentially acquired frames, decreases the average value of pixel values in the pixel group near the image of the specified insertion instrument, or increases the variation in pixel value in the pixel group. Detecting the acquisition timing by detecting,
The X-ray fluoroscopic apparatus according to claim 13. Storage means for storing in advance an image representing the blood vessel morphology of the subject;
The display means displays the blood vessel image based on the stored image.
The X-ray fluoroscopic apparatus according to claim 10 or 11, wherein The stored image is a three-dimensional image representing a three-dimensional form of the blood vessel of the subject,
Rendering means for rendering the three-dimensional image to form a two-dimensional image;
The display means displays the two-dimensional image as the blood vessel image;
The X-ray fluoroscopic apparatus according to claim 15. When two or more images of the insertion instrument are identified by the identification means, the image processing apparatus further comprises first selection means for selecting the image of the insertion instrument closest to the center of the frame,
The alignment processing means performs the alignment so that the degree of coincidence between the image in the one frame and the image in the past frame is substantially maximized.
The X-ray fluoroscopic apparatus according to any one of claims 1 to 16, wherein The alignment processing means performs the alignment for the image of each insertion instrument when two or more images of the insertion instrument are specified by the specifying means,
A second selection means for obtaining the accuracy of the alignment in the image of each insertion instrument, and selecting the image of the insertion instrument having the lowest alignment accuracy;
The alignment processing means performs the alignment so that the degree of coincidence between the image in the one frame and the image in the past frame is substantially maximized.
The X-ray fluoroscopic apparatus according to any one of claims 1 to 17, wherein Operation means;
In response to the operation means being operated when the alignment of the image of the selected insertion instrument is being performed, the alignment of the image is terminated, and the other insertion instrument Switching means for starting the alignment of the image,
The X-ray fluoroscopy device according to claim 17 or claim 18, characterized by that. When the image of the insertion instrument is not specified by the specifying means or when the positioning cannot be performed by the alignment processing means, the translation and / or rotation is performed based on a frame earlier than the one frame. An estimation means for obtaining an estimated amount of movement;
The X-ray fluoroscopic apparatus according to claim 2, wherein: