Position information acquisition device, method, and program, and radiography apparatus

Abstract

To provide a position information acquisition device, method, and program, and a radiography apparatus, in which positions of feature points of surgical instruments, etc. within a subject can be determined in real time.SOLUTION: An image acquisition unit acquires a radiographic image set including a plurality of radiographic images, which have been generated by alternately illuminating a subject with radiation emitted from a plurality of radiation sources provided at different positions and alternately detecting the radiation transmitted through the subject using one detection unit, at a predetermined time interval. A feature point detection unit detects at least one common feature point in the subject from each of the plurality of radiographic images included in the radiographic image set. A position information derivation unit derives three-dimensional position information of the at least one feature point in the subject using a positional relationship between a position of the at least one feature point, on a detection surface of the detection unit, detected from each of the plurality of radiographic images and positions of the plurality of radiation sources.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a position information acquisition device, method, and program for acquiring three-dimensional position information of feature points in a subject, and a radiation imaging device.

Background Art

[0002] In surgical operations and catheter treatments, it is necessary to grasp the positional relationship between surgical instruments and human structures such as bones and blood vessels. However, conventionally, grasping the positional relationship between surgical instruments and human structures often relies on the experience and intuition of doctors, and problems such as misinsertion of surgical instruments and exceeding of the operation time have occurred. For this reason, during the operation, the subject is photographed by a fluoroscopic device, and the positional relationship between the surgical instrument and the human structure is grasped using the fluoroscopic image displayed on the display by the photographing. However, while the surgical instrument and the human structure have a three-dimensional positional relationship, the fluoroscopic image is a two-dimensional image. It is difficult to grasp the three-dimensional positional relationship between the surgical instrument and the human structure even by looking at the two-dimensional fluoroscopic image.

[0003] For this reason, the three-dimensional positional relationship between the surgical instrument and the human structure is grasped by fluoroscopic images from a plurality of directions obtained by photographing the subject, which is the patient, while changing the angle during the procedure, or by using a plurality of photographing devices simultaneously. In addition, a method of attaching a sensor to the surgical instrument to grasp the three-dimensional position of the surgical instrument has also been proposed.

[0004] However, when photographing the subject while changing the angle, it is necessary to move the photographing device during the procedure. In addition, when using a plurality of photographing devices simultaneously, although there is no need to move the photographing device, the working space of the doctor during the operation becomes smaller, so the technique may be hindered. In addition, the method using a sensor requires the preparation of a sensor.

[0005] Therefore, a method has been proposed in which a subject is irradiated with radiation from a plurality of radiation sources arranged at intervals, a plurality of radiation images obtained by photographing the subject from a plurality of positions are acquired, and a three-dimensional radiation image enabling stereoscopic viewing of the subject is generated from the plurality of radiation images (see, for example, Patent Document 1). According to the method described in Patent Document 1, a doctor can grasp the three-dimensional positional relationship between a surgical instrument and a human body structure by stereoscopically viewing the three-dimensional radiation image.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In surgical operations and catheter treatments, it is necessary to grasp the positional relationship between a surgical instrument and a human body structure in real time. However, in the method described in Patent Document 1, processing time is required to generate a three-dimensional radiation image. In recent years, since the resolution and density resolution of radiation images have improved, the data amount of image data representing radiation images has become extremely large. In order to generate a three-dimensional image from such a large amount of radiation image data, time is required for processing. For this reason, with the method described in Patent Document 1, it is difficult to grasp the position and further the positional relationship between a surgical instrument and a human body structure in a subject in real time.

[0008] The present disclosure has been made in view of the above circumstances, and an object thereof is to enable real-time grasping of the three-dimensional position of feature points such as surgical instruments in a subject.

Means for Solving the Problems

[0009] The position information acquisition device according to the present disclosure irradiates a subject with radiation alternately from a plurality of radiation sources arranged at different positions, and acquires, at a predetermined time interval, a set of radiation images composed of a plurality of radiation images generated by alternately detecting the radiation that has passed through the subject by one detection unit. A feature point detection unit that detects at least one common feature point in the subject from each of the plurality of radiation images included in the set of radiation images. A position information derivation unit that derives three-dimensional position information of at least one feature point in the subject by using the positional relationship between the positions of at least one feature point detected from each of the plurality of radiation images on the detection surface of the detection unit and the positions of the plurality of radiation sources.

[0010] The phrase "at a predetermined time interval" means, for example, a time interval corresponding to the frame rate of a moving image. As the predetermined time interval, for example, 25 to 60 fps or the like can be adopted. As a result, in the present disclosure, a combination of radiation images is acquired like a moving image. Note that all of the plurality of radiation images may be at the same time interval, or may be at different time intervals for each of the plurality of radiation images.

[0011] Note that the position information acquisition device according to the present disclosure may further include a display control unit that displays the position information on a display unit.

[0012] Further, in the position information acquisition device according to the present disclosure, the feature point detection unit may detect a point on a surgical instrument inserted into the subject as a feature point.

[0013] The radiation image photographing device according to the present disclosure includes a plurality of radiation sources arranged at a predetermined interval, A detection unit that is arranged to face the plurality of radiation sources and generates a radiation image of the subject by detecting the radiation emitted from each of the plurality of radiation sources and passing through the subject. A photographing control unit that controls the timing of emission of radiation from each of a plurality of radiation sources and the timing of detection of the radiation that has passed through the subject by a detection unit, irradiates the subject with radiation alternately from the plurality of radiation sources, and alternately detects the radiation that has passed through the subject by the detection unit, thereby generating a set of radiation images composed of a plurality of radiation images at a predetermined time interval, and includes a position information acquisition device according to the present disclosure.

[0014] In the radiation image photographing apparatus according to the present disclosure, the number of radiation sources may be two.

[0015] Further, in the radiation image photographing apparatus according to the present disclosure, the photographing control unit sequentially emits radiation from one of the two radiation sources at a first time interval, and sequentially emits radiation from the other radiation source at a second time interval that is equal to or greater than the first time interval, and controls the detection unit to detect radiation at all timings when radiation is emitted from the two radiation sources, The image acquisition unit may acquire, as a set of radiation images, two radiation images generated by detecting, by the detection unit, two radiations emitted from the two radiation sources adjacent to each other in time.

[0016] "Equal to or greater than the first time interval" means being the same as the first time interval and being greater than the first time interval.

[0017] The position information acquisition method according to the present disclosure irradiates a subject with radiation alternately from a plurality of radiation sources arranged at different positions, and acquires, at a predetermined time interval, a set of radiation images composed of a plurality of radiation images generated by alternately detecting the radiation that has passed through the subject by one detection unit, detects at least one common feature point in the subject from each of the plurality of radiation images included in the set of radiation images, Using the positional relationship between the positions of at least one feature point detected from each of a plurality of radiographic images on the detection surface of a detection unit and the positions of the plurality of radiation sources, three-dimensional positional information of at least one feature point within the subject is derived.

[0018] Note that it may be provided as a program for causing a computer to execute the method for acquiring positional information according to the present disclosure.

[0019] Another positional information acquisition device according to the present disclosure includes a memory that stores instructions for causing a computer to execute, and a processor configured to execute the stored instructions, and the processor irradiates a subject with radiation alternately from a plurality of radiation sources arranged at different positions, and acquires a set of radiographic images composed of a plurality of radiographic images generated by alternately detecting the radiation that has passed through the subject by one detection unit at a predetermined time interval, detects at least one common feature point within the subject from each of the plurality of radiographic images included in the set of radiographic images, and executes a process of deriving three-dimensional positional information of at least one feature point within the subject using the positional relationship between the positions of at least one feature point detected from each of the plurality of radiographic images on the detection surface of the detection unit and the positions of the plurality of radiation sources.

Advantages of the Invention

[0020] According to the present disclosure, the positions of feature points such as surgical instruments and human body structures within the subject can be grasped in real time.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a radiation imaging apparatus to which a position information acquisition device according to an embodiment of the present disclosure is applied. The radiation imaging apparatus according to the present embodiment is for acquiring and displaying a fluoroscopic image of a subject H as a moving image when performing a surgical operation or catheter treatment on the subject H and the like.

[0023] In the present embodiment, the x-axis is set in the left-right direction of FIG. 1, the y-axis is set in the depth direction of FIG. 1, and the z-axis is set in the direction perpendicular to the plane on which the radiation imaging apparatus 1 shown in FIG. 1 is placed.

[0024] As shown in FIG. 1, the radiation imaging apparatus 1 according to the present embodiment includes a C-arm 2. A imaging unit 3 is attached to one end of the C-arm 2, and a radiation irradiation unit 4 is attached to the other end of the C-arm 2 so as to face the imaging unit 3.

[0025] Inside the imaging unit 3, a radiation detector 5 such as a flat panel detector is provided. The radiation detector 5 corresponds to the detection unit of the present disclosure. Further, inside the imaging unit 3, a charge amplifier that converts the charge signal read from the radiation detector 5 into a voltage signal, a correlated double sampling circuit that samples the voltage signal output from the charge amplifier, and an AD (Analog Digital) conversion unit that converts the voltage signal into a digital signal, and other circuit boards are also installed. In the present embodiment, the radiation detector 5 is used, but it is not limited to the radiation detector 5 as long as it can detect radiation and convert it into an image. For example, it is also possible to use a detection device such as an image intensifier.

[0026] The radiation detector 5 can repeatedly record and read out radiation images, and a so-called direct type radiation detector that directly converts radiation such as X-rays into electric charges may be used, or a so-called indirect type radiation detector that once converts radiation into visible light and then converts the visible light into an electric charge signal may be used. Further, as a method for reading out a radiation image signal, it is desirable to use a so-called TFT readout method in which a radiation image signal is read out by turning on and off a TFT (Thin Film Transistor) switch, or a so-called optical readout method in which a radiation image signal is read out by irradiating reading light, but it is not limited to this and other methods may be used.

[0027] FIG. 2 is a schematic diagram showing the configuration of the radiation irradiation unit 4. As shown in FIG. 2, inside the radiation irradiation unit 4, a first radiation source 6A and a second radiation source 6B are housed. The first and second radiation sources 6A and 6B are arranged side by side in the depth direction (i.e., the y-axis direction) shown in FIG. 1 at a predetermined interval. The first and second radiations R1 and R2 emitted from the first and second radiation sources 6A and 6B are emitted from the first and second emission units 4A and 4B toward the imaging unit 3, respectively.

[0028] The first and second radiation sources 6A and 6B emit X-rays as radiation, and the timing of emitting radiation from the first and second radiation sources 6A and 6B and the timing of detecting the first and second radiations R1 and R2 by the radiation detector 5 are controlled by a imaging control unit 14 described later. Further, the radiation generation conditions in the first and second radiation sources 6A and 6B, that is, the selection of the materials of the target and the filter, the tube voltage, the irradiation time, etc. are also controlled by the imaging control unit 14.

[0029] In the radiation image capturing apparatus 1 of the present embodiment, a so-called SID (Source Image Distance), which is the distance between the detection surface 5A of the radiation detector 5 and the first and second radiation sources 6A and 6B of the radiation irradiation unit 4, is set to a fixed value.

[0030] The C-arm 2 of this embodiment is held by a C-arm holding unit 7 so as to be movable in the direction of arrow A shown in FIG. 1, such that the angles of the imaging unit 3 and the radiation irradiation unit 4 with respect to the z-direction (vertical direction) shown in FIG. 1 can be changed integrally. The C-arm holding unit 7 has a shaft portion 8, and the shaft portion 8 connects the C-arm 2 to a bearing 9 so as to be rotatable. Thereby, the C-arm 2 is enabled to rotate in the direction of arrow B shown in FIG. 1 with the shaft portion 8 as the rotation axis.

[0031] Also, as shown in FIG. 1, the radiation imaging apparatus 1 of this embodiment includes a main body unit 10. A plurality of wheels 11 are attached to the bottom of the main body unit 10, whereby the radiation imaging apparatus 1 of this embodiment is enabled to move. A support shaft 12 that extends and contracts in the z-axis direction of FIG. 1 is provided at the upper part of the housing of the main body unit 10 in FIG. 1. A bearing 9 is held on the upper part of the support shaft 12 so as to be movable in the direction of arrow C.

[0032] The radiation imaging apparatus 1 according to this embodiment has the above-described configuration, and irradiates a subject H lying supine on an imaging table 40 with radiation from below the subject H, and the radiation that has passed through the subject H is detected by a radiation detector 5 of the imaging unit 3 to acquire a radiation image of the subject H. Here, the C-arm 2 is movable in the directions of arrow A, arrow B, and arrow C, and the radiation imaging apparatus 1 is movable by the wheels 11. For this reason, the radiation imaging apparatus 1 according to this embodiment can image a desired part of the subject H lying supine on the imaging table 40 from a desired direction.

[0033] Also, an I / F (Interface) unit 13, an imaging control unit 14, and a position information acquisition device 15 according to this embodiment are incorporated in the main body unit 10.

[0034] The I / F unit 13 has a function of communicating wirelessly or by wire with a console and an external device (both not shown) that perform overall control regarding the imaging of radiation images by the radiation imaging apparatus 1. The radiation imaging apparatus 1 of the present embodiment performs imaging of the subject H based on an imaging instruction received from the console via the I / F unit 13.

[0035] The imaging control unit 14 causes the first and second radiation sources 6A and 6B of the radiation irradiation unit 4 to emit the first and second radiations R1 and R2, respectively, based on the imaging conditions accompanying the imaging instruction from the console. Further, the imaging control unit 14 detects the first and second radiations R1 and R2 that have passed through the subject H by the radiation detector 5 of the imaging unit 3 according to the timing when the first and second radiations R1 and R2 are emitted from the first and second radiation sources 6A and 6B, and generates the first radiation image G1 and the second radiation image G2 of the subject H. The generated first and second radiation images G1 and G2 are output to the main body unit 10. The timing of the emission of the first and second radiations R1 and R2 from the first and second radiation sources 6A and 6B and the timing of the detection of the first and second radiations R1 and R2 by the radiation detector 5 will be described later.

[0036] Also, a user interface 16 is provided on the upper part of the main body unit 10. The user interface 16 has a function for a user such as a technician and a doctor who perform imaging of radiation images by the radiation imaging apparatus 1 to give an instruction regarding the imaging of radiation images, a function for displaying the radiation image acquired by the imaging as a fluoroscopic image, and a function for providing information regarding the imaging of radiation images to the user. As an example of the user interface 16, a touch panel display or the like can be mentioned.

[0037] Next, the position information acquisition device according to the present embodiment will be described. FIG. 3 is a diagram showing the schematic configuration of the position information acquisition device according to the present embodiment. As shown in FIG. 3, the position information acquisition device 15 is a computer and includes a CPU (Central Processing Unit) 21, a memory 22, and a storage 23 as a standard computer configuration.

[0038] The position information acquisition program according to the present embodiment is installed in the position information acquisition device 15 according to the present embodiment. The position information acquisition program is stored in a storage device of a server computer connected to the network or a network storage in a state accessible from the outside, and is downloaded and installed in the position information acquisition device 15 via the I / F unit 13 in response to a request. Alternatively, it is recorded and distributed on a recording medium such as a DVD (Digital Versatile Disc) or a CD-ROM (Compact Disc Read Only Memory), and is installed in the position information acquisition device 15 from the recording medium.

[0039] The storage 23 is composed of a storage device such as a hard disk drive or an SSD (Solid State Drive), and stores various kinds of information including the position information acquisition program. The radiation image acquired by imaging is also stored in the storage 23.

[0040] In the memory 22, programs and the like stored in the storage 23 are temporarily stored in order to cause the CPU 21 to execute various processes. As processes to be executed by the CPU 21, the position information acquisition program includes an image acquisition process of acquiring a set of radiation images composed of first and second radiation images G1 and G2 acquired by the radiation imaging apparatus 1 at predetermined time intervals, a feature point detection process of detecting at least one common feature point in the subject H from each of the first and second radiation images G1 and G2 included in the set of radiation images, a position information derivation process of deriving three-dimensional position information of at least one feature point in the subject H by using the positional relationship between the positions of the detected feature points on the detection surface 5A of the radiation detector 5 and the positions of the first and second radiation sources 6A and 6B in the first and second radiation images G1 and G2, a three-dimensional information derivation process of deriving three-dimensional information regarding the target structure in the subject H, and a display control process of displaying the position information on the user interface 16.

[0041] Then, when the CPU 21 executes these processes according to the position information acquisition program, the computer functions as a position information acquisition device 15 including an image acquisition unit 31, a feature point detection unit 32, a position information derivation unit 33, a three-dimensional information derivation unit 34, and a display control unit 35.

[0042] The image acquisition unit 31 acquires a set of radiation images composed of first and second radiation images G1 and G2 of the subject H generated by the imaging control unit 14 controlling the first and second radiation sources 6A and 6B and the radiation detector 5. Hereinafter, the emission timings of the first and second radiations R1 and R2 from the first and second radiation sources 6A and 6B and the detection timings of the first and second radiations R1 and R2 by the radiation detector 5 will be described. FIG. 4 is a diagram for explaining the emission timings of the first and second radiations R1 and R2 from the first and second radiation sources 6A and 6B and the detection timings of the first and second radiations R1 and R2 by the radiation detector 5.

[0043] Note that FIG. 4 shows the emission timing T1 of the first radiation R1 from the first radiation source 6A, the emission timing T2 of the second radiation R2 from the second radiation source 6B, and the detection timing T3 of the first and second radiations R1 and R2 by the radiation detector 5. Note that T4 is the timing for deriving position information, which will be described later.

[0044] As shown in FIG. 4, when the first radiation R1 is emitted from the first radiation source 6A, the radiation detector 5 detects the first radiation R1 that has passed through the subject H and generates a first radiation image G1. When the radiation detector 5 generates the first radiation image G1, the second radiation R2 is emitted from the second radiation source 6B, and the radiation detector 5 detects the second radiation R2 that has passed through the subject H and generates a second radiation image G2. When the radiation detector 5 generates the second radiation image G2, the next first radiation R1 is emitted from the first radiation source 6A, and the radiation detector 5 detects the next first radiation R1 that has passed through the subject H and generates the next first radiation image G1. By repeating this, the first radiation image G1 and the second radiation image G2 are alternately and repeatedly acquired. The image acquisition unit 31 acquires the temporally adjacent first and second radiation images G1 and G2 as a set of radiation images.

[0045] Note that the time interval between the generation of the first and second radiation images G1 and G2 by the radiation detector 5 is 25 to 60 fps, for example, 30 fps. When the time interval between the generation of the first and second radiation images G1 and G2 is 30 fps, the emission timings of the first and second radiations R1 and R2 from the first and second radiation sources 6A and 6B, respectively, are 15 fps.

[0046] Here, the procedure for performing catheter treatment of an abdominal aortic aneurysm of the subject H using the radiation imaging apparatus 1 according to the present embodiment will be described. FIG. 5 is a diagram showing a fluoroscopic image displayed on the user interface 16 when performing catheter treatment. As shown in FIG. 5, in the catheter treatment of an abdominal aortic aneurysm, a bifurcated stent 51 inserted into a guide wire 52 is inserted from the artery at the base of one leg into the aorta 50, and one branch 51A of the stent 51 is expanded by the guide wire 52. Then, another guide wire 53 is inserted into the aorta 50 from the artery at the base of the other leg, and the work of passing the guide wire 53 through the other branch 51B of the stent 51 to expand the branch 51B of the stent 51 is performed. At this time, in the present embodiment, the first radiation image G1 or the second radiation image G2 of the abdominal aortic aneurysm of the subject H is displayed on the user interface 16 as a moving fluoroscopic image. While looking at the fluoroscopic image displayed on the user interface 16, the user performs the work of passing the guide wire 53 through the branch 51B of the stent 51.

[0047] Here, the diameter of the branch 51B of the stent 51 is small, and the fluoroscopic image displayed on the user interface 16 is a two-dimensional image. For this reason, the three-dimensional positional relationship between the end of the branch 51B of the stent 51 and the tip 53A of the guide wire 53 is difficult to understand. For example, in the fluoroscopic image shown in FIG. 5, it appears that the guide wire 53 is inserted into the branch 51B of the stent 51. However, actually, as shown in FIG. 6, there is a possibility that the guide wire 53 is not inserted into the branch 51B.

[0048] Also, when performing spinal fixation, a radiation image of the front of the subject H is taken to determine the insertion position of the screw, and while displaying the fluoroscopic image of the side of the subject H shown in FIG. 7 as a moving image, the depth and angle are confirmed, and the screw 55 is inserted into the lumbar vertebra 56. However, since the fluoroscopic image is a two-dimensional image, the insertion position and insertion angle of the screw 55 are difficult to understand, and there is a possibility of misinsertion. The present embodiment has been made to solve these problems.

[0049] The feature point detection unit 32 detects at least one common feature point in the subject H from each of the first and second radiographic images G1, G2 included in the set of radiographic images. For example, in the case of catheter treatment, the tip 53A of the guide wire 53 included in each of the first and second radiographic images G1, G2 is detected as a feature point. Also, in the case of lumbar spine fixation, the tip 55A and the rear end 55B of the screw 55 included in each of the first and second radiographic images G1, G2 are detected as feature points. In the present embodiment, the feature point detection unit 32 has a learned model that has been learned to detect feature points included in the first and second radiographic images G1, G2.

[0050] Note that the feature point includes not only a single pixel but also a region having a certain area composed of a plurality of pixels. For example, the tip 53A of the guide wire 53, the tip 55A of the screw 55, and the rear end 55B of the screw 55 have a certain area, and in the present embodiment, they are included in the feature points.

[0051] The learned model is composed of a neural network that has been subjected to deep learning (deep learning) so as to be able to detect feature points included in the first and second radiographic images G1, G2. The learned model is generated by learning a neural network using a large number of images with known feature points as teacher data. Thereby, when the first and second radiographic images G1, G2 are input, the feature point detection unit 32 detects a common feature point from the first and second radiographic images G1, G2 and outputs the two-dimensional position coordinates of the detected feature point.

[0052] Note that the learned model may be composed of, for example, a support vector machine (SVM (Support Vector Machine)), a convolutional neural network (CNN (Convolutional Neural Network)), and a recurrent neural network (RNN (Recurrent Neural Network)) in addition to the neural network that has been subjected to deep learning.

[0053] Further, the feature point detection unit 32 is not limited to detecting feature points using a learned model. For example, as a method for detecting feature points, any method can be used, such as a method of detecting feature points included in the first and second radiographic images G1 and G2 by template matching.

[0054] The position information derivation unit 33 derives three-dimensional position information of the feature points in the subject H using the positional relationship between the positions of the feature points detected from the first and second radiographic images G1 and G2 on the detection surface 5A of the radiation detector 5 and the positions of the first and second radiation sources 6A and 6B. FIG. 8 is a diagram for explaining the derivation of three-dimensional position information of the feature points. The position information derivation unit 33 acquires information on the source position S1 (sx1, sy1, sz1) of the first radiation source 6A, the source position S2 (sx2, sy2, sz2) of the second radiation source 6B, the position D1 (dx1, dy1, dz1) of the feature points detected in the first radiographic image G1, and the position D2 (dx2, dy2, dz2) of the feature points detected in the second radiographic image G2 shown in FIG.

[0055] The three-dimensional coordinates (sx1, sy1, sz1) of the source position S1 and the three-dimensional coordinates (sx2, sy2, sz2) of the source position S2 can be derived based on the positional relationship between the origin and the first and second radiation sources 6A and 6B when a coordinate system with an arbitrary position on the C-arm 2 of the radiographic imaging apparatus 1 as the origin is set. For example, in the present embodiment, a coordinate system can be set with the point that bisects the line connecting the centers of the first and second emission units 4A and 4B in the radiation irradiation unit 4 as the origin.

[0056] On the other hand, since the SID is known, the three-dimensional coordinates of the center position of the detection surface 5A of the radiation detector 5 with reference to the above origin can be derived. Further, using the three-dimensional coordinates of the center position of the detection surface 5A of the radiation detector 5, the three-dimensional coordinates of the positions D1 and D2 of the feature points can be derived from the two-dimensional position coordinates of the feature points in the first and second radiographic images G1 and G2 detected by the feature point detection unit 32.

[0057] The position information derivation unit 33 sets a straight line L1 connecting the source position S1 and the position D1 of the feature point, and a straight line L2 connecting the source position S2 and the position D2 of the feature point. When expressing an arbitrary point P1 on the straight line L1 and an arbitrary point P2 on the straight line L2 using the source positions S1, S2 and the positions D1, D2 of the feature points, the following formula (1) is obtained. In formula (1), t and s are respectively intermediate variables.

[0058] P1 = (1 - t)·S1 + t·D1 P2 = (1 - s)·S2 + s·D2 (1)

[0059] Ideally, the feature points in the subject H detected in the first and second radiographic images G1, G2 are located at the intersection in the three-dimensional space between the point P1 on the straight line L1 and the point P2 on the straight line L2. Therefore, in the present embodiment, the position information derivation unit 33 derives the three-dimensional coordinates of the point where the distance between the point P1 and the point P2 is minimized as the three-dimensional position information P0(x0, y0, z0) of the feature points detected in the first and second radiographic images G1, G2 by the following formula (2).

[0060] P0 = min(P1 - P2) 2 (2)

[0061] Note that when the image acquisition unit 31 acquires a set of radiographic images consisting of the first and second radiographic images G1, G2 at consecutive timings, the position information derivation unit 33 derives the position information P0 using the first and second radiographic images G1, G2 included in the acquired set of radiographic images. Therefore, the timing at which the position information derivation unit 33 derives the position information P0 is the timing T4 shown in FIG. 4.

[0062] The three-dimensional information derivation unit 34 captures the subject H from two directions and derives three-dimensional information regarding the target structure that is the target during the procedure included in the subject H. For example, in the case of catheter treatment for an abdominal aortic aneurysm, first, after the stent 51 is inserted, the branch 51A is expanded, and then, the operation of inserting the guide wire 53 into the branch 51B is performed. For this reason, the three-dimensional information derivation unit 34 derives the center position of the end of the branch 51B of the stent 51 as the three-dimensional information regarding the target structure. FIG. 9 is a diagram for explaining the imaging of the subject H from two directions, and FIG. 10 is a diagram showing the radiographic images acquired by the imaging from two directions.

[0063] The C-arm 2 moves to the state shown in FIG. 1, and according to the instruction of the user, the imaging control unit 14 irradiates the subject H with radiation from the direction of the arrow E1 shown in FIG. 9, whereby the radiographic image GE1 shown in FIG. 10 is acquired. Further, the radiation irradiation unit 4 is moved to the right side of the subject H in FIG. 1, and by irradiating the subject H with radiation from the direction of the arrow E2, the radiographic image GE2 shown in FIG. 10 is acquired. The radiographic images GE1 and GE2 include the image of the stent 51. The coordinates of the center positions of the radiographic images GE1 and GE2 are known because they coincide with the coordinates of the center position of the detection surface 5A of the radiation detector 5. For this reason, the three-dimensional information derivation unit 34 derives the three-dimensional coordinates of the center position of the end of the branch 51B into which the guide wire of the stent 51 is to be inserted in the radiographic images GE1 and GE2 in the same coordinate system as when the feature points are detected, as the three-dimensional information of the target structure.

[0064] Here, the coordinate system is not limited to the same one as when the feature points are detected. For example, a coordinate system with the center position of the end of the branch 51B of the stent 51 as the origin may be set.

[0065] Note that the three-dimensional information derivation unit 34 may cause the radiation imaging apparatus 1 to perform tomosynthesis imaging, generate a three-dimensional image of the target site of the subject H, and derive the three-dimensional information of the target structure from the three-dimensional image acquired by the tomosynthesis imaging.

[0066] In tomosynthesis imaging, while rotating the C-arm 2 in the direction of arrow A, radiation is emitted from one of the first and second radiation sources 6A and 6B (here, the first radiation source 6A) from a plurality of source positions to image the subject H, thereby acquiring a plurality of projection images. Then, the three-dimensional information derivation unit 34 reconstructs the plurality of projection images using a back-projection method such as the simple back-projection method or the filtered back-projection method, and generates tomographic images for each of a plurality of tomographic planes of the subject H. Then, a three-dimensional image composed of a plurality of tomographic images is generated.

[0067] The three-dimensional information derivation unit 34 performs coordinate transformation so that the coordinate system of the three-dimensional image coincides with the coordinate system of the feature points, and derives the three-dimensional coordinates of the center position of the end of the branch 51B of the stent 51 as the three-dimensional information of the target structure. At this time, a coordinate system with the center position of the end of the branch 51B of the stent 51 as the origin may be set.

[0068] Note that the three-dimensional information derivation unit 34 may also derive three-dimensional information from a three-dimensional image acquired in advance by a CT (Computed Tomography) device, an MRI (Magnetic Resonance Imaging) device, or the like. In this case, similar to the three-dimensional image acquired by the above tomosynthesis imaging, coordinate transformation is performed so that the coordinate system of the three-dimensional image acquired in advance coincides with the coordinate system of the feature points, and the three-dimensional coordinates of the center position of the end of the branch 51B of the stent 51 are derived as the three-dimensional information of the target structure. Also in this case, a coordinate system with the center position of the end of the branch 51B of the stent 51 as the origin may be set.

[0069] On the one hand, when performing lumbar spine fixation surgery, the three-dimensional information derivation unit 34 derives, as three-dimensional information of the target structure, the three-dimensional coordinates of the insertion position and the reaching position in a preset lumbar spine in the three-dimensional image of the subject H acquired by a CT device or an MRI device before the surgery. In this case, the three-dimensional information derivation unit 34 generates projection images GP1 and GP2 obtained by projecting the three-dimensional image in the directions of arrow E1 and arrow E2 shown in FIG. 9. FIG. 11 is a diagram showing the projection images in two directions. As shown in FIG. 11, the projection image GP1 is a front view of the lumbar spine of the subject H, and the projection image GP2 is a side view of the lumbar spine of the subject H. Here, through preoperative examination, the insertion position and the reaching position of the screw 55 are predetermined and set on the three-dimensional image. Therefore, the insertion position PS and the reaching position PE are specified in the projection images GP1 and GP2.

[0070] In addition, the three-dimensional information derivation unit 34 photographs the subject H from the two directions shown in FIG. 9 and acquires radiographic images GE11 and GE12 shown in FIG. 12. Then, the coordinate systems of the radiographic images GE11 and GE12 are made to coincide with the coordinate systems of the projection images GP1 and GP2, and the insertion position PS1 and the reaching position PE1 in the radiographic images GE11 and GE12 are specified. In this case, it is preferable that the coordinate system to be made to coincide is a coordinate system with the insertion position PS in the projection images GP1 and GP2 as the origin, but it is not limited thereto. The coordinate systems of the radiographic images GE11 and GE12 may be made to coincide with a coordinate system with an arbitrary point on the projection images GP1 and GP2 as the origin, or the coordinate systems of the projection images GP1 and GP2 may be made to coincide with the coordinate systems of the radiographic images GE11 and GE12.

[0071] The display control unit 35 displays the position information P0 on the user interface 16. At this time, the display control unit 35 displays the position information P0 using also the three-dimensional information of the target structure derived by the three-dimensional information derivation unit 34. FIG. 13 is a diagram showing a position information screen in the case of performing catheter treatment. As shown in FIG. 13, the position information screen 60 has a display area 61 for a fluoroscopic image and a display area 62 for the position information P0. In the display area 61, the first radiographic image G1 is sequentially displayed as a fluoroscopic image. For this reason, a fluoroscopic image is displayed as a moving image in the display area 61. Note that the second radiographic image G2 may be sequentially displayed as a fluoroscopic image in the display area 61.

[0072] Here, the three-dimensional information derivation unit 34 has derived the three-dimensional coordinates of the center position of the branch 51B of the stent 51 as the three-dimensional information of the target structure, and the position information derivation unit 33 has derived the position information P0 of the tip 53A of the guide wire 53. Further, the diameter of the branch 51B of the stent 51 is known. For this reason, the display control unit 35 generates a stent image GT0 that schematically represents the shape of the branch 51B of the stent 51 and displays it in the display area 62 for the position information. Note that the stent image GT0 is an image of the end of the branch 51B of the stent 51 viewed in the direction of its central axis. Further, the display control unit 35 displays a mark M0 representing the position of the tip 53A of the guide wire 53 in the display area 62. At this time, the display control unit 35 makes the positional relationship between the mark M0 and the stent image GT0 coincide with the positional relationship between the tip 53A of the guide wire 53 and the center position of the branch 51B of the stent 51 derived by the three-dimensional information derivation unit 34. Here, the position of the tip 53A of the guide wire 53 is acquired in three-dimensional coordinates. For this reason, the mark M0 represents the position of the tip 53A of the guide wire 53 in the image of the branch 51B of the stent 51 viewed in the direction of its central axis.

[0073] The user performs an operation of inserting the guide wire 53 into the body of the subject H while looking at the position information screen 60 so that the mark M0 is located inside the circle representing the end of the branch 51B in the stent image GT0. Here, the positional relationship between the stent image GT0 and the mark M0 shown in FIG. 13 indicates that the tip 53A of the guide wire 53 is separated from the end of the branch 51B of the stent 51. The user can adjust the position of the guide wire 53 inserted into the subject H so that the mark M0 is located inside the stent image GT0 while looking at the position information screen 60. Thereby, it is possible to reduce the insertion error of the guide wire 53 into the stent 51 as shown in FIG. 6 described above.

[0074] Note that the display control unit 35 may notify the user interface 16 that the guide wire 53 has reached the central position of the branch 51B of the stent 51 and has been inserted into the branch 51B. The notification may be by text display or by voice. Also, both display and voice may be used.

[0075] Also, the voice may change according to the distance between the tip 53A of the guide wire 53 and the central position of the branch 51B. For example, a beep sound may be intermittently output as the voice, and the interval of the beep sound may be made smaller as the tip 53A of the guide wire 53 approaches the central position of the branch 51B. Also, the voice may be changed when the tip 53A of the guide wire 53 is inserted into the branch 51B.

[0076] Also, when the tip 53A of the guide wire 53 passes through the end of the branch 51B without being inserted into the branch 51B, or when the tip 53A of the guide wire 53 is separated from the center of the branch 51B by a predetermined threshold or more, a warning to that effect may be given on the user interface 16.

[0077] On the other hand, a position information screen in the case of performing lumbar spine fixation surgery is shown in FIG. 14. As shown in FIG. 14, the position information screen 70 has a display area 71 for a fluoroscopic image and a display area 72 for position information. In the display area 71, a first radiographic image G1 obtained by photographing the lumbar spine from the side is sequentially displayed. For this reason, a fluoroscopic image is displayed as a moving image in the display area 71. Note that the image of the screw 55 is included in the first radiographic image G1. Further, a second radiographic image G2 may be sequentially displayed as a fluoroscopic image in the display area 71.

[0078] Here, the three-dimensional information derivation unit 34 derives the three-dimensional coordinates of the insertion position PS and the arrival position PE of the screw 55 in the lumbar spine as the three-dimensional information of the target structure. The position information derivation unit 33 derives the position information P0 of the tip 55A and the rear end 55B of the screw 55. For this reason, the display control unit 35 generates a tomographic image GD0 of the lumbar spine into which the screw 55 is inserted using a three-dimensional image of the subject H acquired in advance, and displays the generated tomographic image GD0 in the display area 72 for position information. Note that the tomographic image GD0 of the lumbar spine displayed in the display area 72 represents an axial cross section.

[0079] Further, the display control unit 35 displays a mark M1 obtained by projecting the screw 55 derived by the position information derivation unit 33 onto the tomographic plane of the tomographic image GD0 in the display area 72 for position information. At this time, the display control unit 35 makes the positional relationship between the tip and the rear end of the mark M1 and the insertion position PS and the arrival position PE on the tomographic image GD0 coincide with the positional relationship between the tip 55A and the rear end 55B of the screw 55 and the insertion position PS and the arrival position PE derived by the three-dimensional information derivation unit 34. Further, until the screw 55 reaches the insertion position PS, the display control unit 35 displays the remaining distance from the tip 55A of the screw 55 derived by the position information derivation unit 33 to the insertion position PS in the information display area 74. In the present embodiment, since a coordinate system with the insertion position PS as the origin is also set for the radiographic images G1 and G2, the distance from the origin of the current position of the tip 55A of the screw 55 can be derived as the remaining distance from the tip 55A of the screw 55 to the insertion position PS.

[0080] Further, the display control unit 35 derives an angle (referred to as the first angle) with respect to the axial cross-section of the axis of the screw 55 from the position of the tip 55A and the position of the rear end 55B of the screw 55 derived by the position information derivation unit 33. Further, from the puncture position PS and the arrival position PE derived by the three-dimensional information derivation unit 34, an angle (referred to as the second angle) at which the screw 55 should be inserted is derived. Then, the difference between the first angle and the second angle is derived, and the derived angle is displayed in the information display area 74. In FIG. 14, it is displayed that the remaining distance is 10 mm and the angle is 0 degrees. The fact that the angle is 0 degrees means that the angle at which the screw 55 is inserted coincides with the angle formed by the puncture position PS and the arrival position PE. After the screw 55 is inserted into the lumbar vertebra from the puncture position PS, the remaining distance from the tip 55A of the screw 55 to the arrival position PE may be displayed in the information display area 74.

[0081] In addition, when the tip 55A of the screw 55 is at a position separated from the puncture position PS by a predetermined threshold value or more, the display control unit 35 may give a warning. Further, when the angle of the screw 55 exceeds a predetermined threshold value (for example, 10 degrees), the display control unit 35 may give a warning.

[0082] The user can insert the screw 55 into the body of the subject H so that the screw 55 is inserted into the lumbar vertebra from the puncture position PS while viewing the display of the tomographic image GD0, the mark M1, and the information display area 74. Further, the screw 55 can be inserted into the lumbar vertebra of the subject H so that the inserted screw 55 correctly reaches the arrival position PE.

[0083] In the case of lumbar spine fixation surgery as well, the display control unit 35 may notify the user interface 16 that the tip 55A of the screw 55 has reached the insertion position PS and that the tip 55A of the screw 55 has reached the arrival position PE. Further, notification may also be made when the angle of the screw 55 matches the angle at which the screw 55 is to be inserted. The notification may be by text display, by voice, or by using both display and voice.

[0084] Also, the voice may change according to the distance between the tip 55A of the screw 55 and the insertion position PS and the arrival position PE. For example, a beep sound may be intermittently output as the voice, and the interval of the beep sound may be made smaller as the tip 55A of the screw 55 approaches the insertion position PS and the arrival position PE. Further, the voice may be changed when the tip 55A of the screw 55 reaches the insertion position PS and the arrival position PE.

[0085] Next, the processing performed in this embodiment will be described. FIG. 15 is a flowchart showing the processing performed in this embodiment. It is assumed that the three-dimensional information of the target structure has been previously derived by the three-dimensional information derivation unit 34 and stored in the storage 23.

[0086] The processing is started when the user gives an instruction to start imaging from the user interface 16, and the image acquisition unit 31 acquires a set of the first radiographic image G1 and the second radiographic image G2 (acquisition of a set of radiographic images; step ST1). When the set of the first radiographic image G1 and the second radiographic image G2 is acquired, the feature point detection unit 32 detects at least one common feature point from the first and second radiographic images G1 and G2 (step ST2). Next, the position information derivation unit 33 uses the positional relationship between the positions of at least one feature point detected from each of the first and second radiographic images G1 and G2 on the detection surface 5A of the radiation detector 5 and the positions of the first and second radiation sources 6A and 6B to derive three-dimensional positional information of at least one feature point in the subject H (step ST3).

[0087] Furthermore, the display control unit 35 displays the position information screen on the user interface 16 (step ST4) and returns to step ST1. Note that the processing from step ST1 to step ST4 is repeatedly performed until an instruction to end the processing is given.

[0088] As described above, in the present embodiment, at least one common feature point in the subject H is detected from each of the first and second radiation images G1 and G2, and the position on the detection surface 5A of the radiation detector 5 of at least one feature point detected from each of the first and second radiation images G1 and G2, and the positions of the first and second radiation sources 6A and 6B are used to derive the three-dimensional position information of at least one feature point in the subject H. Therefore, compared with the case of generating a three-dimensional image from a plurality of radiation images, the three-dimensional position information of the feature point can be obtained with a smaller amount of calculation. Therefore, according to the present embodiment, the three-dimensional position of a feature point such as a surgical instrument in the subject H can be grasped in real time.

[0089] In the above embodiment, the first radiation image G1 and the second radiation image G2 are alternately acquired, but the present invention is not limited to this. As shown in FIG. 16, the second radiation image G2 may be acquired once every several frames of the first radiation image G1. In FIG. 16, the second radiation image G2 is acquired once while four frames of the first radiation image G1 are acquired. In this case, the derivation of the position information is performed once while four frames of the first radiation image G1 are acquired.

[0090] In the above-described embodiment, when performing catheter treatment, the three-dimensional information derivation unit 34 derives the central position of the branch 51B of the stent 51 as the three-dimensional information of the target structure. However, the present invention is not limited to this. The feature point detection unit 32 may detect the central position of the branch 51B of the stent 51 from the first and second radiation images G1 and G2 as a feature point different from the tip 53A of the guide wire 53, and the position information derivation unit 33 may derive the position information of the central position of the branch 51B.

[0091] In the above-described embodiment, the radiation is not particularly limited, and in addition to X-rays, α-rays or γ-rays can be applied.

[0092] In the above-described embodiment, when performing catheter treatment and lumbar fixation, the position information acquisition device and the radiation image imaging device according to the present disclosure are applied. However, the present invention is not limited to this, and the present disclosure can be applied when performing any treatment as long as it is a treatment using a fluoroscopic image.

[0093] In the above-described embodiment, in the radiation irradiation unit 4, the first and second radiation sources 6A and 6B are arranged in the y-axis direction shown in FIG. 1. However, the first and second radiation sources 6A and 6B may be arranged in the x-axis direction.

[0094] In the above-described embodiment, the radiation irradiation unit 4 is assumed to have two radiation sources 6A and 6B. However, the present invention is not limited to this. It may have three or more radiation sources. In this case, the position information may be derived using a plurality of radiation images obtained by irradiating the subject H with radiation from three or more radiation sources. Specifically, the position information may be derived using a combination of two radiation images generated by radiation emitted from two of the three or more radiation sources.

[0095] Also, in the above-described embodiment, for example, as the hardware structure of a processing unit (Processing Unit) that executes various processes such as the image acquisition unit 31, the feature point detection unit 32, the position information derivation unit 33, the three-dimensional information derivation unit 34, and the display control unit 35, the following various processors (Processor) can be used. As described above, in addition to the CPU, which is a general-purpose processor that executes software (program) and functions as various processing units, among the above various processors, there are also programmable logic devices (Programmable Logic Device: PLD), such as FPGA (Field Programmable Gate Array), which are processors whose circuit configuration can be changed after manufacturing, and dedicated electric circuits, etc., which are processors having a circuit configuration specifically designed to execute specific processes, such as ASIC (Application Specific Integrated Circuit).

[0096] One processing unit may be composed of one of these various processors, or may be composed of a combination of two or more processors of the same type or different types (for example, a combination of multiple FPGAs or a combination of a CPU and an FPGA). Also, a plurality of processing units may be composed of one processor.

[0097] As an example of configuring a plurality of processing units with one processor, firstly, as represented by computers such as clients and servers, there is a form in which one processor is configured by a combination of one or more CPUs and software, and this processor functions as a plurality of processing units. Secondly, as represented by a system on chip (System On Chip: SoC), etc., there is a form in which a processor that realizes the functions of the entire system including a plurality of processing units with one IC (Integrated Circuit) chip is used. Thus, as a hardware structure, the various processing units are configured using one or more of the above various processors.

[0098] Furthermore, as the hardware structure of these various processors, more specifically, an electric circuit (Circuitry) combining circuit elements such as semiconductor elements can be used.

[0099] Hereinafter, the appended claims of the present disclosure will be described. (Appended Claim 1) An image acquisition unit that acquires, at a predetermined time interval, a set of radiation images composed of a plurality of radiation images generated by alternately irradiating a subject with radiation from a plurality of radiation sources arranged at different positions and alternately detecting the radiation that has passed through the subject by one detection unit; A feature point detection unit that detects at least one common feature point in the subject from each of the plurality of radiation images included in the set of radiation images; A position information acquisition device comprising: a position information derivation unit that derives three-dimensional position information of the at least one feature point in the subject by using the positional relationship between the position of the at least one feature point detected on the detection surface of the detection unit from each of the plurality of radiation images and the positions of the plurality of radiation sources. (Appended Claim 2) The position information acquisition device according to appended claim 1, further comprising a display control unit that displays the position information on a display unit. (Appended Claim 3) The position information acquisition device according to appended claim 1 or 2, wherein the feature point detection unit detects a point on a surgical instrument inserted into the subject as the feature point. (Appended Claim 4) A plurality of radiation sources arranged at a predetermined interval; A detection unit that is arranged opposite to the plurality of radiation sources and generates a radiation image of the subject by detecting the radiation emitted from each of the plurality of radiation sources and passing through the subject. Controlling the timing of radiation emission from each of the plurality of radiation sources and the timing of detection of the radiation transmitted through the subject by the detection unit, irradiating the subject with radiation alternately from the plurality of radiation sources, and detecting the radiation transmitted through the subject by the detection unit alternately, thereby generating a set of radiation images composed of a plurality of radiation images at a predetermined time interval, a shooting control unit; A radiation image photographing apparatus comprising the position information acquisition apparatus according to any one of claims 1 to 3. (Claim 5) The radiation image photographing apparatus according to claim 4, wherein the number of the radiation sources is two. (Claim 6) The shooting control unit sequentially emits radiation from one of the two radiation sources at a first time interval, emits radiation sequentially from the other radiation source at a second time interval longer than the first time interval, and controls the detection unit to detect the radiation at all timings when the radiation is emitted from the two radiation sources. The image acquisition unit acquires, as the set of radiation images, two radiation images generated by detecting two radiations emitted adjacently in time from the two radiation sources by the detection unit, the radiation image photographing apparatus according to claim 5. (Claim 7) Radiation is alternately irradiated to a subject from a plurality of radiation sources arranged at different positions, and a set of radiation images composed of a plurality of radiation images generated by alternately detecting the radiation transmitted through the subject by one detection unit is acquired at a predetermined time interval. Detecting at least one common feature point in the subject from each of the plurality of radiation images included in the set of radiation images. A position information acquisition method for deriving three-dimensional position information of at least one feature point in the subject by using the positional relationship between the position of the at least one feature point detected from each of the plurality of radiation images on the detection surface of the detection unit and the positions of the plurality of radiation sources. (Claim 8) A procedure for obtaining, at a predetermined time interval, a set of radiographic images composed of a plurality of radiographic images generated by alternately irradiating a subject with radiation from a plurality of radiation sources arranged at different positions and alternately detecting the radiation transmitted through the subject by one detection unit; A procedure for detecting at least one common feature point in the subject from each of the plurality of radiographic images included in the set of radiographic images; A position information acquisition program that causes a computer to execute a procedure for deriving three-dimensional position information of at least one feature point in the subject using the positional relationship between the positions of the at least one feature point detected from each of the plurality of radiographic images on the detection surface of the detection unit and the positions of the plurality of radiation sources.

Explanation of Reference Numerals

[0100] 1 Radiographic imaging apparatus 2 C-arm 3 Imaging unit 4 Radiation irradiation unit 4A, 4B Emitters 5 Radiation detector 5A Detection surface 6A First radiation source 6B Second radiation source 7 C-arm holder 8 Shaft portion 9 Bearing 10 Main body portion 11 Wheels 12 Support shaft 13 I / F unit 14 Imaging control unit 15 Position information acquisition device 16 User interface 21 CPU 22 Memory 23 Storage 31 Image acquisition unit 32 Feature point detection unit 33 Position information derivation unit 34 Three-dimensional information derivation unit 35 Display control unit 40 Imaging table 50 aorta 51 stent 52, 53 guide wire 53A tip of guide wire 55 screw 55A tip of screw 55B rear end of screw 56 lumbar vertebra 60, 70 position information screen 61, 71 display area of fluoroscopic image 62, 72 display area of position information 74 information display area D1, D2 positions of feature points in the first and second radiographic images G1 first radiographic image G2 second radiographic image GD0 tomographic image GE1, GE2, GE11, GE12 radiographic images GP1, GP2 projection images GT0 stent image H subject M0, M1 marks PS insertion position PE arrival position P0 position of feature point R1, R2 radiation S1, S2 positions of radiation sources T1~T4 timing

Claims

1. An image acquisition unit that acquires, at a predetermined time interval, a set of radiographic images composed of a plurality of radiographic images generated by alternately irradiating a subject with radiation from a plurality of radiation sources arranged at different positions and alternately detecting the radiation transmitted through the subject by one detection unit; From each of the plurality of radiographic images included in the set of radiographic images, within the subject A feature point detection unit that detects at least one common feature point; A position information acquisition device comprising: a position information derivation unit that derives three-dimensional position information of the at least one feature point in the subject by using the positional relationship between the positions of the at least one feature point detected on the detection surface of the detection unit from each of the plurality of radiographic images and the positions of the plurality of radiation sources.

2. The position information acquisition device according to claim 1, further comprising a display control unit that displays the position information on a display unit.

3. The position information acquisition device according to claim 1 or 2, wherein the feature point detection unit detects a point on a surgical instrument inserted into the subject as the feature point.

4. A plurality of radiation sources arranged at a predetermined interval; A detection unit that is arranged to face the plurality of radiation sources and generates a radiographic image of the subject by detecting radiation emitted from each of the plurality of radiation sources and transmitted through the subject; A photographing control unit that controls the timing of emission of radiation from each of the plurality of radiation sources and the timing of detection of the radiation transmitted through the subject by the detection unit, and alternately irradiates the subject with radiation from the plurality of radiation sources and alternately detects the radiation transmitted through the subject by the detection unit, thereby generating a set of radiographic images composed of a plurality of radiographic images at a predetermined time interval; A radiographic imaging device comprising the position information acquisition device according to any one of claims 1 to 3.

5. The radiographic imaging device according to claim 4, wherein there are two radiation sources.

6. The photographing control unit sequentially emits radiation from one of the two radiation sources at a first time interval, emits radiation sequentially from the other radiation source at a second time interval longer than the first time interval, and controls the detection unit to detect the radiation at all timings when the radiation is emitted from the two radiation sources. The radiation image capturing apparatus according to claim 5, wherein the image acquisition unit acquires, as a set of radiation images, two radiation images generated by detecting, by the detection unit, two radiations emitted adjacently in time from the two radiation sources.

7. A set of radiation images composed of a plurality of radiation images generated by alternately irradiating a subject with radiation from a plurality of radiation sources arranged at different positions and alternately detecting the radiation transmitted through the subject by one detection unit is acquired at a predetermined time interval. At least one common feature point in the subject is detected from each of the plurality of radiation images included in the set of radiation images. A position information acquisition method for deriving three-dimensional position information of the at least one feature point in the subject by using the positional relationship between the position of the at least one feature point on the detection surface of the detection unit detected from each of the plurality of radiation images and the positions of the plurality of radiation sources.

8. A procedure for acquiring, at a predetermined time interval, a set of radiation images composed of a plurality of radiation images generated by alternately irradiating a subject with radiation from a plurality of radiation sources arranged at different positions and alternately detecting the radiation transmitted through the subject by one detection unit. A procedure for detecting at least one common feature point in the subject from each of the plurality of radiation images included in the set of radiation images. A position information acquisition program for causing a computer to execute a procedure for deriving three-dimensional position information of the at least one feature point in the subject by using the positional relationship between the position of the at least one feature point on the detection surface of the detection unit detected from each of the plurality of radiation images and the positions of the plurality of radiation sources.

Images