JP7334590B2 - X-ray fluoroscopy method and X-ray fluoroscopy apparatus - Google Patents

Description

The present invention relates to an X-ray fluoroscopy method and an X-ray fluoroscopy apparatus.

2. Description of the Related Art In radiation therapy in which radiation as therapeutic beams such as X-rays and proton beams is applied to an affected area such as a tumor, it is necessary to accurately irradiate the affected area with radiation. However, not only the body of the subject may move, but also the affected area itself may move. For example, a tumor near a subject's lungs moves significantly based on respiration. For this reason, a radiotherapy apparatus has been proposed that has a configuration in which a marker is placed near a tumor, the position of the marker is detected by an X-ray imaging apparatus, and irradiation of therapeutic radiation is controlled (see Patent Document 1).

In such a radiotherapy apparatus, a first X-ray imaging system comprising a first X-ray tube and a first X-ray detection section and a second X-ray imaging system comprising a second X-ray tube and a second X-ray detection section are provided. A ray imaging device is used to image a marker placed in the body, and three-dimensional positional information is obtained using a two-dimensional fluoroscopic image obtained by the first X-ray imaging system and a two-dimensional fluoroscopic image obtained by the second X-ray imaging system. obtain. By performing X-ray fluoroscopy continuously in this way and calculating the three-dimensional position information of the markers in real time, the markers of the moving parts can be detected and tracked with high accuracy. Then, by controlling the irradiation of therapeutic radiation when the position of the detected marker is placed within the gating window set during treatment planning, highly accurate radiation irradiation according to the movement of the tumor is performed. It becomes possible to

When obtaining the position information of this marker, image recognition is performed to recognize the marker in the image of the area containing the marker. Patent Document 2 discloses a local structure detection unit that detects a local structure in a region of interest around a marker candidate point, and a device determination unit that determines whether the local structure is a device such as a marker. , and a device position acquisition unit that obtains the coordinates of the center of gravity of a local structure, and is capable of accurately detecting markers regardless of their shape.

Japanese Patent No. 3053389 Japanese Patent No. 6455358

As such markers, markers made of gold spheres are generally used. Such spherical markers have the advantage of being recognized as having the same shape when observed from any direction, but have the disadvantage of being easily dropped from the vicinity of the affected area of the subject. For this reason, linear markers, which are coil-shaped and flexible and have high adhesion to the affected tissue of the subject, are also frequently used.

When such a linear marker is used, the marker itself curves according to body movements of the subject. Therefore, when specifying the position of the marker, the position of the center of gravity of the marker can be calculated by image processing, and the calculated position can be recognized as the position of the marker. On the other hand, when a doctor selects marker positions from an X-ray fluoroscopic image to set a gating window during treatment planning, it is difficult to calculate the position of the center of gravity. In such a case, the position of one of the edges of the linear marker may be recognized as the position of the marker.

When tracking the position of a marker using such a linear marker, image recognition as described in Patent Document 2, for example, is performed in order to recognize the marker. In such a case, when the linear marker is greatly curved, a phenomenon may occur in which the positions of both edges of the linear marker are reversed during image recognition.

11 and 12 are schematic diagrams showing how the linear marker M is observed from two different directions.

As shown in these figures, the linear marker M is curved in close contact with the affected tissue of the subject. The degree of curvature varies depending on the direction in which the image of the marker M is acquired, as shown in these figures. At this time, it is assumed that both edges T1 and T2 of the marker M are arranged at the positions shown in FIG. 11 in the field of view (View1) from one direction and the field of view (View2) from the other direction. In such a case, when image recognition is performed, the positions of both edges T1 and T2 of the marker M may be reversed and recognized as shown in View2 of FIG. Such a phenomenon becomes remarkable especially when the marker M is greatly curved. In this way, when the positions of both edges T1 and T2 of the marker M are exchanged and recognized, when the position of one of the edges of the linear marker M is recognized as the position of the marker M, that The position will be recognized incorrectly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. An object of the present invention is to provide an X-ray fluoroscopy method and an X-ray fluoroscopy apparatus capable of accurately recognizing the position of an edge.

A first aspect of the present invention uses two X-ray imaging systems consisting of an X-ray irradiator and an X-ray detector to capture an X-ray image containing linear markers placed in the body of a subject. An X-ray fluoroscopy method for detecting the position of the marker that moves with the body movement of the subject by specifying the position of the edge of the marker by collecting data from two different directions, wherein each X-ray When the epipolar geometry is set with the focus of the irradiation unit as the projection center of the camera and the image detected by each X-ray detection unit viewed from the focus of each X-ray irradiation unit as the projection plane of the camera, a pair of projection planes a determination step of determining whether the position of one edge of the marker in a pair of projection planes does not meet the epipolar constraint; and a changing step of changing the position of the other edge of the marker in one projection plane to the position of the one edge.

According to the first aspect of the present invention, when recognizing the position of a marker using the position of the edge of a linear marker, the position of the edge of the marker can be accurately determined even if the marker is greatly curved. can be recognized.

1 is a perspective view showing an X-ray imaging apparatus that executes an X-ray fluoroscopy method according to an embodiment of the present invention together with a therapeutic beam irradiation apparatus 90; FIG. 2 is a block diagram showing the main control system of the X-ray imaging apparatus; FIG. 1 is a perspective view of a marker M used in an X-ray fluoroscopy method according to an embodiment of the invention; FIG. FIG. 4 is an explanatory diagram showing an image recognition operation for recognizing a marker M from an X-ray image acquired by an X-ray imaging system; FIG. 4 is an explanatory diagram showing an image recognition operation for recognizing a marker M from an X-ray image acquired by an X-ray imaging system; FIG. 4 is an explanatory diagram showing an image recognition operation for recognizing a marker M from an X-ray image acquired by an X-ray imaging system; It is a schematic diagram for demonstrating epipolar geometry. 4 is a flow chart showing a position detection operation of a marker M; FIG. 2 is a schematic diagram showing a state in which epipolar geometry is applied to the X-ray imaging apparatus shown in FIG. 1; FIG. 10 is an enlarged view showing View1 and View2 in FIG. 9; It is a schematic diagram which shows a mode that the linear marker M was observed from two different directions. It is a schematic diagram which shows a mode that the linear marker M was observed from two different directions.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an X-ray imaging apparatus that executes an X-ray fluoroscopy method according to an embodiment of the present invention together with a treatment beam irradiation apparatus 90. FIG. The X-ray imaging apparatus and the treatment beam irradiation apparatus 90 constitute a radiotherapy apparatus.

The therapeutic beam irradiation device 90 performs radiation therapy on a subject on the medical examination table 27, and rotates about an isocenter with respect to a base 91 installed on the floor of the treatment room. It comprises a movable gantry 92 and a therapeutic beam irradiation unit 93 arranged on the gantry 92 for emitting a therapeutic beam. The gantry 92 is structured to be rotatable within a range of 360 degrees with respect to the base 91 together with the therapeutic beam irradiation unit 93 . Therefore, according to this therapeutic beam irradiation apparatus 90, by rotating the gantry 92 to an arbitrary angular position with respect to the base 91, the irradiation direction of the therapeutic beam emitted from the therapeutic beam irradiation unit 93 can be changed. becomes possible.

The X-ray imaging apparatus used together with this treatment beam irradiation apparatus 90 performs X-ray fluoroscopy for performing moving body tracking for specifying the position of the affected part of the subject. That is, during radiotherapy using the above-described therapeutic beam irradiation apparatus 90, it is necessary to accurately irradiate radiation to the affected area that moves along with body movement of the subject. For this reason, in this X-ray imaging apparatus, the subject is viewed from two different directions, and image recognition is performed on the fluoroscopic images, thereby recognizing the marker placed near the specific site of the subject. By detecting the position and calculating the three-dimensional positional information of the marker, the marker is detected with high accuracy, which is a so-called moving object tracking.

This X-ray imaging apparatus includes a first X-ray tube 11a, a second X-ray tube 11b, a third X-ray tube 11c, a fourth X-ray tube 11d (collectively referred to as "X-ray tube 11"), and a first X-ray tube. A flat panel detector 21a, a second flat panel detector 21b, a third flat panel detector 21c, and a fourth flat panel detector 21d (collectively referred to as "flat panel detector 21") are provided. The X-rays emitted from the first X-ray tube 11a are detected by the first flat panel detector 21a after passing through the subject on the examination table 27. FIG. The first X-ray tube 11a and the first flat panel detector 21a constitute a first X-ray imaging system. The X-rays emitted from the second X-ray tube 11b are detected by the second flat panel detector 21b after passing through the subject on the examination table 27. FIG. The second X-ray tube 11b and the second flat panel detector 21b constitute a second X-ray imaging system. The X-rays emitted from the third X-ray tube 11c are detected by the third flat panel detector 21c after passing through the subject on the examination table 27. FIG. The third X-ray tube 11c and the third flat panel detector 21c constitute a third X-ray imaging system. The X-rays emitted from the fourth X-ray tube 11d are detected by the fourth flat panel detector 21d after passing through the subject on the examination table 27. FIG. The fourth X-ray tube 11d and the fourth flat panel detector 21d constitute a fourth X-ray imaging system.

When performing X-ray fluoroscopy for tracking a moving body, two of the first X-ray imaging system, second X-ray imaging system, third X-ray imaging system, and fourth X-ray imaging system are used as described later. A radiographic system is selected and used.

The examination table 27 comprises a base 28 and a subject placement part 29, also called a couch. The subject placement section 29 is movable in four-axis or six-axis directions with respect to the base section 28 .

FIG. 2 is a block diagram showing the main control system of the X-ray imaging apparatus.

This X-ray imaging apparatus includes a control unit 30 that controls the entire apparatus. This control unit 30 is composed of a computer in which software is installed. The function of each part included in this control part 30 is realized by executing software installed in the computer.

The control unit 30 includes a marker detection unit 31 for detecting the marker based on an image obtained by fluoroscopy of the linear marker indwelled in the subject's body by the X-ray imaging system, and a marker detection unit 31 for detecting the marker. and a therapeutic beam irradiation control unit 35 for transmitting a therapeutic beam irradiation signal to the therapeutic beam irradiation device 90 based on the position of the marker detected by the unit 31 . As will be described later, the marker detection unit 31 has, as functional configurations, a marker recognition unit 32 that recognizes a marker, and a marker recognition unit 32 that determines whether the position of one edge of the marker recognized by the marker recognition unit 32 matches the epipolar constraint. and an edge changing unit 34 for changing the position of the other edge of the marker to the position of the one edge when the position of one edge of the marker does not match the epipolar constraint. , provided.

This control unit 30 is connected to the X-ray tube 11, flat panel detector 21, examination table 27 and treatment beam irradiation device 90 described above. The control unit 30 is also connected to an operation unit 38 having an input mechanism such as a keyboard and a mouse and executing various operations, and a display unit 39 having a liquid crystal display panel or the like. Furthermore, this control unit 30 is connected online or offline to a treatment planning device 99 that formulates a treatment plan prior to radiotherapy. The treatment planning device 99 acquires CT image data of the subject photographed by a CT imaging device (not shown). The control unit 30 acquires this CT image data from the treatment planning device 99 .

FIG. 3 is a perspective view of a marker M used in the X-ray fluoroscopy method according to the embodiment of the invention.

This marker M has a linear shape composed of a coil made of gold. Since the marker M is coil-shaped and flexible, it adheres to and is fixed to the affected tissue of the subject. As such a marker, for example, the radiotherapy marker VISICOIL Marker Preload (trade name) provided by Seti Co., Ltd. can be used.

4 to 6 are explanatory diagrams showing an image recognition operation for recognizing the marker M from the X-ray image acquired by the X-ray imaging system.

When recognizing the image of the marker M, two X-ray imaging systems out of the first X-ray imaging system, the second X-ray imaging system, the third X-ray imaging system, and the fourth X-ray imaging system are used to recognize the subject. Images from two directions including the marker M placed in the body are acquired at a frame rate of about 20 to 30 fps. It should be noted that the linear marker M has a curved shape when placed in the subject's body.

Then, a candidate point P0 (see FIG. 4), which is a candidate for the linear marker M, is detected from the acquired image. In this case, out of the plurality of acquired images, the difference between the image of the frame at a certain point in time and the average of the images of the past few frames is calculated, and the static structures such as bones other than the marker M are found in the image. Then, the candidate point P0 is detected by applying a known Laplacian filter or the like as necessary. Then, in a predetermined region of interest E1 including the candidate point P0, local segmentation is performed around the candidate point P0 of the linear marker M to detect a local structure (hatched in FIG. 4). do.

Next, as shown in the upper part of FIG. 5, the end points of the local structure located at the ends of the predetermined region of interest E1 centered on the candidate point P0 are newly set as the candidate points P1 and P2 of the marker M, and further , as shown in the middle of FIG. 5, predetermined regions of interest E1-1 and E1-2 centered on the respective candidate points P1 and P2 are set, and in the new predetermined regions of interest E1-1 and E1-2 Perform local structure detection (segmentation processing). In this way, by repeating each operation of setting new candidate points and regions of interest and segmentation processing, the local structure is transformed into a global image corresponding to the overall image of the linear marker M, as shown in the lower part of FIG. expand to a more structured structure. Such structure dilation operations are performed until no local structures reach the edge of the given region of interest. Thereby, as shown in FIG. 6, the positions of both edges T1 and T2 of the marker M can be obtained.

The positions of both edges T1 and T2 of the marker M are different using two X-ray imaging systems out of the first X-ray imaging system, the second X-ray imaging system, the third X-ray imaging system, and the fourth X-ray imaging system. Observed from two directions. At this time, as described above, image recognition was performed even when the marker M was placed at the position shown in FIG. In this case, as shown in View 2 of FIG. 12, the positions of both edges T1 and T2 of the marker M may be reversed and recognized. Such a phenomenon becomes remarkable especially when the marker M is greatly curved. In this way, when the positions of both edges T1 and T2 of the marker M are exchanged and recognized, when the position of one of the edges of the linear marker M is recognized as the position of the marker M, that The position will be recognized incorrectly.

For this reason, in the X-ray fluoroscopy method according to the embodiment of the present invention, a configuration is adopted in which the position of the edge of the marker M is confirmed using the epipolar constraint in the epipolar geometry. .

FIG. 7 is a schematic diagram for explaining epipolar geometry.

Epipolar geometry indicates the geometric law between two images taken from different viewpoints. It is used when asking for FIG. 7 shows a state in which a point X existing in a three-dimensional space is perspectively projected onto projection planes View1 and View2 of a pair of cameras. In this figure, OL and OR indicate projection centers of a pair of cameras, and XL and XR indicate projections of point X on respective projection planes View1 and View2. Also, eL and eR indicate epipolar points that are projected points when the other camera is viewed from one camera. As shown in FIG. 7, eL, eR and OL, OR are arranged on the same straight line in the three-dimensional space.

In View1, a straight line connecting points X and OL is projected to one point. On the other hand, in View2, the line connecting eR and XR is called an epipolar line. This epipolar line is uniquely determined by the three-dimensional spatial position of point X, and all epipolar lines pass through epipolar points eL and eR. Once the projection XL of the point X in View1 is determined, an epipolar line connecting eR and XR in View2 is defined. The projection XR of the point X in View1 onto View2 is somewhere on this epipolar line. This is called an epipolar constraint. That is, when the same point is photographed by a pair of cameras, it always exists on each other's epipolar lines. And if it does not exist on the epipolar line, it means that the recognition of the position is erroneous in either View1 or View2.

Next, the operation of detecting the position of the marker M in order to track a moving object with this X-ray imaging apparatus will be described. FIG. 8 is a flow chart showing the position detection operation of the marker M. As shown in FIG. 9 is a schematic diagram showing a state in which epipolar geometry is applied to the X-ray imaging apparatus shown in FIG. 1, and FIG. 10 is an enlarged diagram showing View1 and View2 in FIG. In FIG. 10, of the four X-ray imaging systems, the first X-ray imaging system comprising the first X-ray tube 11a and the first flat panel detector 21a, the second X-ray tube 11b and the second flat panel detector 21b It shows the case of using a second X-ray imaging system consisting of:

Here, the position of the focus of the first X-ray tube 11a in FIG. 9 corresponds to the projection center OL of the camera in the epipolar geometry shown in FIG. 7, and the position of the focus of the second X-ray tube 11b in FIG. Corresponds to the projection center OR of the camera in geometry. The image View1 detected by the first flat panel detector 21a seen from the focal point of the first X-ray tube 11a in FIG. 9 corresponds to the projection plane View1 of the camera in the epipolar geometry shown in FIG. The image View2 detected by the second flat panel detector 21b seen from the focal point of the tube 11b corresponds to the projection plane View2 of the camera in the epipolar geometry shown in FIG.

When the position of the marker M is detected by the X-ray imaging apparatus, the first X-ray imaging system consists of the first X-ray tube 11a and the first flat panel detector 21a, and the second X-ray tube 11b and the second flat panel detector 21b. An image including the marker M is captured by using a second X-ray imaging system. Then, the marker recognition unit 32 shown in FIG. 2 recognizes the marker M by the image recognition operation shown in FIGS. 4 to 6, and specifies the positions of both edges T1 and T2. Then, the determination unit 33 shown in FIG. 2 determines whether or not the edge T1 used as the position of the marker M matches the epipolar constraint in View1 and View2 (step S1).

That is, the perpendicular length between the epipolar line L11 for the edge T1 in View1 shown in FIG. 10 and the epipolar line L21 for the edge T1 in View2 shown in FIG. 10 is calculated three-dimensionally. If the edge T1 as seen in View1 and the edge T1 as seen in View2 are coincident, then the epipolar constraint is met and the normal length should be substantially zero. Therefore, it is determined whether or not the perpendicular length between the epipolar line L11 for the edge T1 in View1 and the epipolar line L21 for the edge T1 in View2 is equal to or less than a preset value.

If the length of the vertical line is equal to or less than the set value, it is determined that the position of the edge T1 of the marker M is correctly recognized in View1 and View2 (step S5), and the process ends.

When the projection XL of the point X in View1 shown in FIG. 7 is determined, the epipolar line in View2 is uniquely determined, and the projection XR of the point X in View2 is arranged on this epipolar line. Therefore, as described above, depending on whether or not the perpendicular length between the epipolar line L11 for the edge T1 in View1 and the epipolar line L21 for the edge T1 in View2 is equal to or less than a preset value, the pair of projection planes Instead of determining whether the position of one edge T1 of marker M in View1, View2 meets the epipolar constraint, the edge T1 of marker M in View2 shown in FIG. Whether the position of one edge T1 of the marker M in the pair of projection planes View1 and View2 conforms to the epipolar constraint depending on whether or not it is on the epipolar line defined by T1 (the distance from the epipolar line is equal to or less than a certain value) It may be determined whether

On the other hand, when the perpendicular length between the epipolar line L11 for the edge T1 in View1 and the epipolar line L21 for the edge T1 in View2 is greater than the preset value, one edge T1 of the marker M in View2 is replaced with the position of the other edge T2, and the edge changing unit 34 shown in FIG. 2 changes the position of the other edge T2 of the marker in View2 to the position of the one edge T1 (step S2).

Then, the determining unit 33 shown in FIG. 2 determines whether the edge T1 after changing the position of the other edge T2 of the marker in View2 to the position of the one edge T1 matches the epipolar constraint in View1 and View2. It is determined whether or not (step S3). If the perpendicular length between the epipolar line L11 for the edge T1 in View1 and the epipolar line L22 for the changed edge T1 in View2 is equal to or less than a preset value, the position of the marker M in View1 and View2 is correctly recognized (step S5), and the process ends. On the other hand, when the perpendicular length between the epipolar line L11 for the edge T1 in View1 and the epipolar line L22 for the changed edge T1 in View2 is greater than a preset value, the position of the marker M is correctly recognized. It is determined that it is not (step S4), an error is displayed, etc., and the process ends.

By the above operation, even when the linear marker is greatly curved, the edge of the marker M can be detected by using the edges in View1 and View2 and the epipolar line without misidentifying the positions of both edges of the marker M. It becomes possible to detect the position of the edge correctly.

It will be appreciated by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.

(Section 1)
Using two X-ray imaging systems consisting of an X-ray irradiation unit and an X-ray detection unit, X-ray images containing linear markers indwelled in the subject's body are collected from two different directions to detect the markers. an X-ray fluoroscopy method for detecting the position of the marker that moves with the subject's body movement by specifying the position of the edge of the When the epipolar geometry is set with the image detected by each X-ray detection unit viewed from the focal point of each X-ray irradiation unit as the projection plane of the camera, one end edge of the marker on the pair of projection planes is a determination step of determining whether the position meets the epipolar constraint; and a changing step of changing the position of the edge of the to the position of the one edge.

According to the X-ray fluoroscopy method described in item 1, when recognizing the position of the marker using the position of the edge of the linear marker, even if the marker is greatly curved, the edge of the marker It is possible to accurately recognize the position.

(Section 2)
In the X-ray fluoroscopy method according to item 1, in the determination step, the epipolar constraint is satisfied depending on whether the distance of the pair of epipolar lines with respect to the position of the one edge in the pair of projection planes is equal to or less than a predetermined value. A method of X-ray fluoroscopy to determine if there is a match.

According to the X-ray fluoroscopy method described in item 2, it is possible to easily determine whether epipolar constraints are met based on the distance between a pair of epipolar lines.

(Section 3)
In the X-ray fluoroscopy method according to item 1 or item 2, the position of one edge of the marker on the pair of projection planes is epipolarized using the position of one edge after being changed in the changing step. A method of fluoroscopy, further comprising a checking step to see if the constraints are met.

According to the X-ray fluoroscopy method described in item 3, it is possible to more accurately recognize the position of the edge of the marker by confirming the conformity of the epipolar constraint based on the position of the edge after change. Become.

(Section 4)
Using two X-ray imaging systems consisting of an X-ray irradiation unit and an X-ray detection unit, X-ray images containing linear markers indwelled in the subject's body are collected from two different directions to detect the markers. An X-ray fluoroscope that detects the position of the marker that moves with the subject's body movement by specifying the position of the edge of the When the epipolar geometry is set with the image detected by each X-ray detection unit viewed from the focal point of each X-ray irradiation unit as the projection plane of the camera, one end edge of the marker on the pair of projection planes is a determination unit that determines whether the position matches the epipolar constraint, and if the determination unit determines that the position of one edge of the marker on the pair of projection planes does not match the epipolar constraint, one projection an edge changing unit that changes the position of the other edge of the marker on the plane to the position of the one edge.

According to the X-ray fluoroscopy apparatus according to the fourth aspect, when recognizing the position of the marker using the position of the edge of the linear marker, even if the marker is greatly curved, the edge of the marker It is possible to accurately recognize the position.

(Section 5)
In the X-ray fluoroscopy apparatus according to item 4, the determination unit satisfies the epipolar constraint by determining whether or not the distance between the pair of epipolar lines with respect to the position of the one edge on the pair of projection planes is equal to or less than a predetermined value. An X-ray fluoroscope that determines whether or not to

According to the X-ray fluoroscopy apparatus described in item 5, it is possible to easily determine whether epipolar constraints are met based on the distance between a pair of epipolar lines.

(Section 6)
6. In the X-ray fluoroscopy apparatus according to item 4 or 5, the determining unit uses the position of one edge after the edge changing unit changes the position of one of the markers on the pair of projection planes. X-ray fluoroscopy to see if the position of the edge of the .

According to the X-ray fluoroscopy apparatus according to item 6, it is possible to more accurately recognize the position of the edge of the marker by confirming the conformity of the epipolar constraint based on the position of the edge after change. Become.

It should be noted that the above description is for the description of the embodiments of the present invention, and does not limit the present invention.

Reference Signs List 11 X-ray tube 21 flat panel detector 27 examination table 30 control unit 31 marker detection unit 32 marker recognition unit 33 determination unit 34 edge change unit 35 treatment beam irradiation control unit 90 treatment beam irradiation device

Claims (6)

An X-ray system that uses two X-ray imaging systems consisting of an X-ray irradiation unit and an X-ray detection unit to collect X-ray images including linear markers placed in the subject's body from two different directions. A method of fluoroscopy, comprising:
When the epipolar geometry is set with the focus of each X-ray irradiation unit as the projection center of the camera and the image detected by each X-ray detection unit viewed from the focus of each X-ray irradiation unit as the projection plane of the camera,
a determination step of determining whether the position of one edge of the marker in a pair of projection planes matches an epipolar constraint;
a changing step of changing the position of the other edge of the marker on one of the projection planes to the position of the one edge when the position of one edge of the marker on the pair of projection planes does not meet the epipolar constraint; and,
and identifying the position of the edge of the marker, thereby detecting the position of the marker that moves with the subject's body movement. The X-ray fluoroscopy method according to claim 1,
In the determination step, an X-ray fluoroscopy method for determining whether or not an epipolar constraint is met by determining whether or not a distance between a pair of epipolar lines with respect to the position of the one edge on the pair of projection planes is equal to or less than a predetermined value. . In the X-ray fluoroscopy method according to claim 1 or claim 2,
X further comprising a confirmation step of confirming whether the position of one edge of the marker on the pair of projection planes conforms to the epipolar constraint using the position of one edge after being changed in the changing step. fluoroscopy method. An X-ray system that uses two X-ray imaging systems consisting of an X-ray irradiation unit and an X-ray detection unit to collect X-ray images including linear markers placed in the subject's body from two different directions. A fluoroscopy device,
When the epipolar geometry is set with the focus of each X-ray irradiation unit as the projection center of the camera and the image detected by each X-ray detection unit viewed from the focus of each X-ray irradiation unit as the projection plane of the camera,
a determination unit that determines whether the position of one edge of the marker on a pair of projection planes matches an epipolar constraint;
When the determining unit determines that the position of one edge of the marker on the pair of projection planes does not match the epipolar constraint, the position of the other edge of the marker on the one projection plane is changed to the position of the one edge. an edge changer that changes to a position;
and detecting the position of the marker that moves with the subject's body movement by specifying the position of the edge of the marker. In the X-ray fluoroscopy apparatus according to claim 4,
The determination unit determines whether or not the epipolar constraint is met based on whether or not the distance between the pair of epipolar lines with respect to the position of the one edge on the pair of projection planes is equal to or less than a predetermined value. In the X-ray fluoroscopy apparatus according to claim 4 or claim 5,
The determining unit uses the position of the one edge after being changed by the edge changing unit to check whether the position of the one edge of the marker on the pair of projection planes matches the epipolar constraint. X-ray fluoroscope.

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