Three-dimensional image data positioning method and x-ray machine

Abstract

To provide a three-dimensional image data positioning method and an X-ray machine that can perform accurate positioning of a plurality of pieces of CT data.SOLUTION: The three-dimensional image data positioning method includes the steps of: generating first CT data 23 on the basis of first X-ray image data 22 acquired by performing X-ray photography of a first portion 41 of a subject 40 together with at least three positioning members 30 having an isotropic shape; generating second CT data 25 including an overlapping range 26 overlapping a photographing range of the first CT data on the basis of second X-ray image data 24 acquired by performing X-ray photography of a second portion 42 of the subject 40 together with the at least three positioning members 30 arranged in the overlapping range 26; and performing positioning of the first CT data 23 and the second CT data 25 on the basis of the positioning members 30 in the first CT data 23 and the second CT data 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for aligning three-dimensional image data and an X-ray imaging apparatus. [Background technology]

[0002] Conventionally, a method for aligning three-dimensional image data is known, which aligns first CT data generated based on a first X-ray image with second CT data generated based on a second X-ray image and including an overlapping range that overlaps with the shooting range of the first CT data (for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses an imaging method using an X-ray CT device (X-ray imaging device) in which a part of a subject is irradiated with X-rays to capture an image (first X-ray image), and then, with the X-ray irradiation stopped, the subject is moved a predetermined distance in the body axis direction, and another part of the subject is irradiated with X-rays to capture an image (second X-ray image). The above-mentioned Patent Document 1 discloses that images of each part of the subject are captured so as to have an overlapping area (overlapping range) that is used for synthesis. The above-mentioned Patent Document 1 discloses that such movement of the subject and partial imaging of the subject are repeated, and the images of each part of the subject are synthesized to obtain an image of a wide range of the subject. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-61278 A Summary of the Invention [Problem to be solved by the invention]

[0005] Although not specified in the above Patent Document 1, the X-ray CT device (X-ray imaging device) shown in the above Patent Document 1 is considered to be a medical X-ray imaging device. In contrast, even in non-medical, measurement X-ray imaging devices, the imaging unit is moved and partial imaging of the subject is repeated, and the CT data of each part of the subject is synthesized to obtain CT data of the entire subject. At this time, the images of each part of the subject are captured so as to have an overlapping area that is used for synthesis.

[0006] However, when CT data of each part of the subject is synthesized, it is difficult to obtain the relative positional relationship between the CT data of each part of the subject due to the inclination of the subject placement part on which the subject is placed, the movement (drift) of the X-ray focus due to distortion caused by thermal expansion of the X-ray tube, and the like. In addition, in a method called best fit, in which one shape data is used as a reference and the other shape data is translated or rotated to move to a position where the relative distance with the other shape data is minimized, the larger the shape, the greater the contribution to positioning. In this case, the larger the shape, the longer the path length of the penetrating X-ray becomes, so that errors in the surface shape may be more likely to occur due to artifacts. Therefore, in the best fit method, shape data that may contain errors is used when connecting CT data, so alignment of the shape data may be difficult. As described above, when CT data of each part of the subject is synthesized to generate CT data of the entire subject, there is a problem that it is difficult to align the CT data of each part of the subject. Therefore, it is desired to align multiple CT data with high accuracy.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a method for aligning three-dimensional image data and an X-ray imaging apparatus that are capable of aligning multiple CT data with high accuracy. [Means for solving the problem]

[0008] A method for aligning three-dimensional image data in a first aspect of the present invention includes the steps of generating three-dimensional first CT data based on first X-ray image data obtained by X-raying a first portion of a subject with at least three positioning members having an isotropic shape, generating three-dimensional second CT data based on second X-ray image data obtained by X-raying a second portion including an overlapping range that overlaps with the imaging range of the first CT data and including a part of the first portion of the subject with at least three positioning members arranged in the overlapping range, and aligning the first CT data and the second CT data based on the positioning members having isotropic shapes in the first CT data and the second CT data.

[0009] An X-ray imaging device in a second aspect of the present invention includes an X-ray source that irradiates X-rays and a detector that detects X-rays irradiated from the X-ray source, and is equipped with an imaging unit that images a subject, and an image processing unit that generates CT data based on multiple X-ray image data images taken from multiple angles with different relative angles between the subject and the imaging unit, wherein the image processing unit generates three-dimensional first CT data based on first X-ray image data obtained by X-ray imaging of a first portion of the subject with at least three positioning members having an isotropic shape, generates three-dimensional second CT data based on second X-ray image data obtained by X-ray imaging of a second portion of the subject, including an overlapping range that overlaps with the imaging range of the first CT data and including a part of the first portion of the subject, with at least three positioning members arranged in the overlapping range, and aligns the first CT data with the second CT data based on the positioning members having isotropic shapes in the first CT data and the second CT data. Effect of the Invention

[0010] In the method for aligning three-dimensional image data in the first aspect and the X-ray imaging device in the second aspect, as described above, three-dimensional first CT data is generated based on first X-ray image data obtained by X-ray imaging of a first portion of a subject by an imaging unit together with at least three positioning members having an isotropic shape, three-dimensional second CT data is generated based on second X-ray image data obtained by X-ray imaging of a second portion including a part of the first portion of the subject by an imaging unit together with at least three positioning members arranged in an overlapping range, and alignment between the first CT data and the second CT data is performed based on the positioning members having an isotropic shape in the first CT data and the second CT data. As a result, even if the positions of the portions of the subject are shifted between the CT data due to the inclination of the subject placement unit or the movement (drift) of the X-ray focus, the alignment between the first CT data and the second CT data can be performed with high accuracy based on at least three positioning members arranged in the overlapping range of the first CT data and the second CT data. Furthermore, in the first CT data and the second CT data generated based on the X-ray image data captured while rotating the positioning member, the positioning member has an isotropic shape, so the center position of the positioning member can be obtained with high accuracy. Therefore, the first CT data and the second CT data can be aligned with high accuracy based on the positioning member having an isotropic shape, compared to the best-fit method that aligns shape data that may include errors. For these reasons, the first CT data and the second CT data can be aligned with high accuracy. Therefore, multiple CT data can be aligned with high accuracy. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing an example of an X-ray imaging apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining acquisition of first X-ray image data. [Diagram 3] FIG. 11 is a schematic diagram for explaining acquisition of second X-ray image data. [Figure 4]FIG. 13 is a schematic perspective view showing an example of a positioning jig and a positioning member. [Diagram 5] 11 is a schematic plan view showing an example of a positioning jig and a positioning member. FIG. [Figure 6] FIG. 4 is a diagram for explaining a process of acquiring first location information. [Figure 7] 11 is a diagram for explaining a process of acquiring second location information. FIG. [Figure 8] FIG. 11 is a flow diagram for explaining a registration process of the first CT data and the second CT data. [Figure 9] FIG. 13 is a schematic perspective view showing an example of a positioning jig and a positioning member according to a first modified example. [Figure 10] 13A and 13B are schematic diagrams showing an example of a positioning jig and a positioning member of a second modified example. [Figure 11] 13A and 13B are schematic diagrams showing another example of the positioning jig and the positioning member of the second modified example. [Figure 12] 13A and 13B are schematic diagrams showing an example of a positioning jig and a positioning member according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0013] (Overall configuration of X-ray equipment) The overall configuration of an X-ray imaging apparatus 100 according to this embodiment will be described with reference to FIGS.

[0014] 1, the X-ray imaging device 100 includes an imaging unit 1, a control unit 10, a storage unit 20, and a movement and rotation mechanism 60. The imaging unit 1 includes an X-ray source 2 and a detector 3. The control unit 10 includes an image processing unit 11 and an imaging control unit 12.

[0015] The X-ray source 2 is configured to irradiate X-rays to the subject 40. Specifically, the X-ray source 2 is configured to generate X-rays by causing electrons, which are generated by applying a high voltage to an electrode, to collide with a target. The X-ray source 2 is, for example, an X-ray generating device including an X-ray tube and a power supply.

[0016] The detector 3 is configured to detect X-rays irradiated from the X-ray source 2. The detector 3 is also configured to convert the detected X-rays into an electric signal (image signal). The detector 3 includes a light receiving section that receives X-rays and a conversion section that converts the received X-rays into an image signal. The detector 3 is, for example, a flat panel detector (FPD). The detector 3 is configured with a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements. The image signal of the detector 3 is sent to an image processing section 11.

[0017] The control unit 10 is configured by a processor such as a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit). The control unit 10 as hardware includes an image processing unit 11 and an imaging control unit 12 as software (program) functional blocks. The control unit 10 functions as the image processing unit 11 and the imaging control unit 12 by executing a program 21 stored in a storage unit 20. The image processing unit 11 and the imaging control unit 12 may be configured individually as hardware by providing a dedicated processor (processing circuit).

[0018] The image processing unit 11 is configured to control the detector 3. As shown in FIG. 2, the image processing unit 11 is configured to acquire first X-ray image data 22 based on X-rays detected by the detector 3 by X-ray imaging of the first portion 41 of the subject 40 together with the three positioning members 30 having an isotropic shape. The image processing unit 11 is configured to acquire a plurality of first X-ray image data 22 captured while rotating the subject 40 around the axis 43 by the moving and rotating mechanism 60. The image processing unit 11 is configured to generate first CT data 23 based on the acquired plurality of first X-ray image data 22. That is, the image processing unit 11 generates the first CT data 23 based on a plurality of first X-ray image data 22 captured from a plurality of angles at which the relative angle between the subject 40 and the imaging unit 1 is different.

[0019] As shown in FIG. 3, the image processor 11 is configured to acquire second X-ray image data 24 based on X-rays detected by the detector 3 by X-raying a second portion 42 including a part of a first portion 41 of the subject 40 together with three positioning members 30 arranged in the overlapping range 26, the second portion 42 including an overlapping range 26 overlapping with the imaging range of the first CT data 23. The overlapping range 26 overlapping with the imaging range of the first CT data 23 includes a first range 26a overlapping in the direction of an axis 43 of a rotation axis of the subject 40 perpendicular to a straight line connecting the X-ray source 2 and the detector 3. The image processor 11 is configured to acquire a plurality of second X-ray image data 24 captured while rotating the subject 40 around the axis 43 by the moving and rotating mechanism 60. The image processor 11 is configured to generate second CT data 25 based on the acquired plurality of second X-ray image data 24. That is, the image processor 11 generates the second CT data 25 based on a plurality of second X-ray image data 24 captured from a plurality of angles in which the relative angles between the subject 40 and the imaging unit 1 are different.

[0020] That is, in this embodiment, as shown in Fig. 2, a first portion 41 which is the upper part of the subject 40 is X-rayed together with the three positioning members 30 to obtain first X-ray image data 22 having the first portion 41 which is the upper part of the subject 40 as an imaging range. Also, as shown in Fig. 3, a second portion 42 which is the lower part of the subject 40 and includes a part of the upper part of the subject 40 is X-rayed together with the three positioning members 30 arranged in the overlapping range 26 to obtain second X-ray image data 24.

[0021] Moreover, the image processing unit 11 is configured to align the first CT data 23 and the second CT data 25 based on a positioning member 30 having an isotropic shape in the first CT data 23 and the second CT data 25. That is, the image processing unit 11 aligns the first CT data 23 and the second CT data 25 based on the positioning member 30 in an overlapping range 26 of the first CT data 23 and the second CT data 25, and combines the first CT data 23 and the second CT data 25 to obtain CT data of the entire subject 40.

[0022] In addition, when the magnification of the subject 40 in the first CT data 23 is different from the magnification of the subject 40 in the second CT data 25, the image processing unit 11 is configured to obtain a first distance 34 (see Figure 6) between at least two of the three positioning members 30 in the first CT data 23 and a second distance 35 (see Figure 7) between the at least two positioning members 30 corresponding to the first distance 34 in the second CT data 25, and to align the first CT data 23 with the second CT data 25 by enlarging or reducing at least one of the first CT data 23 and the second CT data 25 so as to match the first distance 34 with the second distance 35.

[0023] As shown in FIG. 1, the imaging control unit 12 controls the operation of the X-ray source 2. The imaging control unit 12 also controls the operation of the moving and rotating mechanism 60. The imaging control unit 12 is composed of a control device for the X-ray source 2, a control device for the moving and rotating mechanism 60, and the like. When acquiring a plurality of first X-ray image data 22 and when acquiring a plurality of second X-ray image data 24, the imaging control unit 12 controls the X-ray source 2 to irradiate X-rays and to stop the irradiation, and controls the moving and rotating mechanism 60 to position the subject 40 at a plurality of imaging angles in sequence. After acquiring a plurality of first X-ray image data 22, the imaging control unit 12 also controls the moving and rotating mechanism 60 to move the subject 40 in the vertical direction in order to acquire a plurality of second X-ray image data 24.

[0024] The storage unit 20 includes a non-volatile storage device. The non-volatile storage device is, for example, a hard disk drive, a solid state drive, or the like. The storage unit 20 stores various programs 21 executed by the processor. The storage unit 20 also stores a plurality of first X-ray image data 22 and first CT data 23 generated based on the plurality of first X-ray image data 22. The storage unit 20 also stores a plurality of second X-ray image data 24 and second CT data 25 generated based on the plurality of second X-ray image data 24.

[0025] In this embodiment, the positioning jig 50 provided with the three positioning members 30 is placed on the subject placement section 61 on which the subject 40 is placed, and X-ray photography is performed to obtain the first X-ray image data 22 and the second X-ray image data 24 of the subject 40 and the positioning members 30. Then, the image processing section 11 generates the first CT data 23 based on the plurality of first X-ray image data 22, and generates the second CT data 25 based on the plurality of second X-ray image data 24. Then, the image processing section 11 aligns the first CT data 23 and the second CT data 25 based on the center point 31 of the three positioning members 30. The center point 31 of the positioning members 30 is an example of the "center position of the positioning members" in the claims.

[0026] The moving and rotating mechanism 60 is configured to rotate the subject 40 around the axis 43. The moving and rotating mechanism 60 includes a subject placement section 61 on which the subject 40 is placed, a rotating section (not shown) that rotates the subject placement section 61, a rotation drive section (not shown) that imparts a driving force to the rotating section, a moving section (not shown) that moves the subject placement section 61 in the vertical direction, and a moving drive section (not shown) that imparts a driving force to the moving section. The rotating drive section and the moving drive section include, for example, motors.

[0027] (Positioning jig and positioning member) As shown in Fig. 4, the positioning jig 50 is configured to fix and position the positioning member 30. The positioning jig 50 is disposed on the subject placement section 61 (see Fig. 1). The positioning jig 50 is disposed on the subject placement section 61 so as to surround the subject 40. The positioning jig 50 is formed of a cylindrical member. The positioning jig 50 is moved together with the subject 40 in one vertical direction when the subject placement section 61 on which the subject 40 is placed is moved in one vertical direction by a moving section.

[0028] The positioning jig 50 is formed of, for example, a CFRP pipe. The material of the positioning jig 50 is not particularly limited as long as it has high X-ray transmittance. By using a material with high X-ray transmittance as the material of the positioning jig 50, the influence of the shadow of the positioning jig 50 in the X-ray image can be suppressed.

[0029] Three positioning members 30 are fixed to the outer peripheral surface of the positioning jig 50. This prevents the relative positions of the positioning members 30 from changing at least until X-ray imaging is completed. Methods for fixing the positioning members 30 to the positioning jig 50 include fixing with an adhesive or screwing, but any method can be used as long as it is possible to fix the positioning members 30 to the positioning jig 50.

[0030] 2 and 3, the positioning member 30 is provided at a position in the positioning jig 50 corresponding to an overlapping range 26 where the imaging range of the first CT data 23 (imaging range 22a of the first X-ray image data 22) and the imaging range of the second CT data 25 (imaging range 24a of the second X-ray image data 24) overlap. As shown in Fig. 5, the center points 31 of the three positioning members 30 are not on the same line, but are configured so that one plane 36 is specified by the three center points 31. Note that the one plane 36 specified by the center points 31 of the three positioning members 30 may be parallel to a horizontal plane or may intersect with the horizontal plane.

[0031] Moreover, the three positioning members 30 are arranged at intervals of approximately 120 degrees on the outer circumferential surface of the positioning jig 50 in a plan view. Note that the three positioning members 30 do not have to be arranged at intervals of approximately 120 degrees on the outer circumferential surface of the positioning jig 50, and may be arranged at any angle interval.

[0032] The positioning member 30 is placed on the positioning jig 50 so that the entire positioning member 30 is included in the overlapping range 26. Although details will be described later, the image processing unit 11 acquires position information (first position information 32) of the center point 31 of the positioning member 30 in the first coordinate system, and acquires position information (second position information 33) of the center point 31 of the positioning member 30 in the second coordinate system. Also, as will be described later, the positioning member 30 has a spherical shape. Since a small spherical shape can be measured with high accuracy, the size of the positioning member 30 may be reduced to an extent that does not affect the first CT data 23 and the second CT data 25. For example, there is no problem even if the ratio of one positioning member 30 to 1 / 20 or less in the horizontal direction of the overlapping range 26 between the imaging range of the first CT data 23 (imaging range 22a of the first X-ray image data 22) and the imaging range of the second CT data 25 (imaging range 24a of the second X-ray image data 24) shown in FIG. 2 and FIG. 3. For ease of explanation, the size of the positioning member 30 shown in the drawings differs from the actual size.

[0033] 4 and 5, the positioning member 30 has an isotropic shape. Specifically, the positioning member 30 has a shape that is point-symmetric with respect to the center of the positioning member 30 as the isotropic shape. More specifically, the positioning member 30 has a spherical shape that is point-symmetric. Note that the isotropic shape means that the shape of the positioning member 30 has no directivity or has little directivity.

[0034] The positioning member 30 is made of a material having the same or similar X-ray transmittance as the subject 40. The positioning member 30 is made of, for example, ceramics. The material of the positioning member 30 is not limited to ceramics, and may be, for example, a metal such as aluminum or iron, or a resin. It is preferable that the specific gravity of the material of the positioning member 30 is smaller than that of the material of the subject 40. This is because, if the specific gravity of the material of the positioning member 30 is larger than that of the subject 40, artifacts (noise) may occur due to the high absorption coefficient of the positioning member 30.

[0035] (Acquisition of first X-ray image data and generation of first CT data) Next, the acquisition of the first X-ray image data 22 and the generation of the first CT data 23 will be described with reference to FIG.

[0036] The subject 40 is placed on the subject placement section 61. The cylindrical positioning jig 50 is disposed on the subject placement section 61 so as to surround the periphery of the subject 40. The positioning jig 50 has a cylindrical shape. Note that the positioning jig 50 is not limited to a cylindrical shape, and may be a square tube shape.

[0037] Three positioning members 30 are fixed to the outer circumferential surface of the positioning jig 50. The three positioning members 30 are arranged in the positioning jig 50 in a range corresponding to an overlapping range 26 of the imaging range of the first CT data 23 (imaging range 22a of the first X-ray image data 22) and the imaging range of the second CT data 25 (imaging range 24a of the second X-ray image data 24). A first portion 41 of the subject 40 is set as the imaging range 22a of the first X-ray image data 22. The subject placement unit 61 is moved in the vertical direction by the moving unit so that the first portion 41 of the subject 40 becomes the imaging range.

[0038] Then, by changing the imaging angle of the subject 40 by the rotation mechanism, an X-ray image of the subject 40 is captured by the imaging unit 1 at each of a plurality of preset imaging angles. A first portion 41 of the subject 40 is X-rayed together with the three positioning members 30. The image processing unit 11 acquires (generates) first X-ray image data 22 from a detection signal (image signal) of the detector 3 for each of a plurality of preset imaging angles. The acquisition of the first X-ray image data 22 for each imaging angle is performed over a predetermined angle range set in advance.

[0039] The image processing unit 11 (see FIG. 1) is configured to generate first CT data 23 based on the acquired multiple first X-ray image data 22. The image processing unit 11 generates the first CT data 23 by executing a reconstruction process on a set of multiple first X-ray image data 22 required for one CT scan for each shooting angle. The first CT data 23 is an image that reflects a three-dimensional structure of a first portion 41 of the subject 40. The first CT data 23 can be in the form of a tomographic image, a three-dimensional image, or the like of the first portion 41 of the subject 40.

[0040] (Acquisition of second X-ray image data and generation of second CT data) Next, the acquisition of the second X-ray image data 24 and the generation of the second CT data 25 will be described with reference to Fig. 3. In this embodiment, after the acquisition of the plurality of first X-ray image data 22, the plurality of second X-ray image data 24 are acquired.

[0041] The second portion 42 of the subject 40 is set as the imaging range 24a of the second X-ray image data 24. The second portion 42 of the subject 40 includes a part of the first portion 41 of the subject 40. That is, a part of the first portion 41 of the subject 40 in the second portion 42 of the subject 40 is the overlapping range 26. After capturing the plurality of first X-ray image data 22, in order to capture the plurality of second X-ray image data 24, the subject placement unit 61 is moved upward along the axis 43 of the rotation axis of the subject 40 by the moving unit so that the second portion 42 of the subject 40 becomes the imaging range.

[0042] Then, by changing the imaging angle of the subject 40 by the rotation mechanism, an X-ray image of the subject 40 is captured by the imaging unit 1 at each of a plurality of preset imaging angles. The second portion 42 of the subject 40 is X-rayed together with the three positioning members 30. The acquisition of the second X-ray image data 24 and the generation of the second CT data 25 by the image processing unit 11 are performed in a similar manner to the acquisition of the first X-ray image data 22 and the generation of the first CT data 23, and therefore a description thereof will be omitted.

[0043] (Obtaining the center position of the positioning member) The image processing unit 11 acquires the shape of the positioning member 30 in the first CT data 23 and the second CT data 25. In this embodiment, the image processing unit 11 specifies the shape of the positioning member 30. There is no restriction on the method by which the image processing unit 11 specifies the shape of the positioning member 30. The first CT data 23 is data indicating the three-dimensional shape of the subject 40 in a first coordinate system defined by the P axis, the Q axis, and the R axis. The second CT data 25 is data indicating the three-dimensional shape of the subject 40 in a second coordinate system defined by the S axis, the T axis, and the U axis.

[0044] As shown in Fig. 6, the image processing unit 11 acquires first position information 32 (see Fig. 1) of the positioning member 30 in the first coordinate system. The image processing unit 11 acquires the first position information 32, which is position information of the positioning member 30 in the first CT data 23, based on the isotropic shape of the positioning member 30 in the first CT data 23. The first position information 32 includes position information of a center point 31 of the positioning member 30 in the first coordinate system. The image processing unit 11 acquires the center point 31 of the positioning member 30 in the first CT data 23 using a known method, and the acquisition method is not particularly limited.

[0045] The positioning member 30 has a spherical shape that is an isotropic shape. Therefore, the image processing unit 11 can accurately acquire the position information (first position information 32) of the center point 31 of the positioning member 30 in the first coordinate system. The image processing unit 11 acquires the position coordinates (P1, Q1, R1) of the center point 31a in the first coordinate system as the first position information 32 of the positioning member 30a. In addition, the image processing unit 11 acquires the position coordinates (P2, Q2, R2) of the center point 31b in the first coordinate system as the first position information 32 of the positioning member 30b. In addition, the image processing unit 11 acquires the position coordinates (P3, Q3, R3) of the center point 31c in the first coordinate system as the first position information 32 of the positioning member 30c. The acquired first position information 32 is stored in the storage unit 20 (see FIG. 1).

[0046] As shown in FIG. 7, the image processing unit 11 acquires second position information 33 (see FIG. 1) of the positioning member 30 in the second coordinate system. The second position information 33 includes position information of the center point 31 of the positioning member 30 in the second coordinate system. The image processing unit 11 acquires the center point 31 of the positioning member 30 in the second CT data 25 by a known method, and the acquisition method is not particularly limited. The image processing unit 11 acquires the position coordinates (S1, T1, U1) of the center point 31a in the second coordinate system as the second position information 33 of the positioning member 30a. In addition, the image processing unit 11 acquires the position coordinates (S2, T2, U2) of the center point 31b in the second coordinate system as the second position information 33 of the positioning member 30b. In addition, the image processing unit 11 acquires the position coordinates (S3, T3, U3) of the center point 31c in the second coordinate system as the second position information 33 of the positioning member 30c. The acquired second position information 33 is stored in the storage unit 20 (see FIG. 1).

[0047] (Matching of subject magnification of the first CT data and the second CT data) The image processing unit 11 acquires at least one of the distance between the center point 31a of the positioning member 30a and the center point 31b of the positioning member 30b, the distance between the center point 31a of the positioning member 30a and the center point 31c of the positioning member 30c, and the distance between the center point 31b of the positioning member 30b and the center point 31c of the positioning member 30c, in the first coordinate system, based on the first position information 32 in the first CT data 23. In this embodiment, the image processing unit 11 acquires the linear distance between the center point 31a of the positioning member 30a and the center point 31b of the positioning member 30b in the first coordinate system as a first distance 34 (see FIG. 6) based on the first position information 32 in the first CT data 23.

[0048] Furthermore, the image processing unit 11 acquires at least one of the distance between the center point 31a of the positioning member 30a and the center point 31b of the positioning member 30b, the distance between the center point 31a of the positioning member 30a and the center point 31c of the positioning member 30c, and the distance between the center point 31b of the positioning member 30b and the center point 31c of the positioning member 30c, based on the second position information 33 in the second CT data 25. In this embodiment, the image processing unit 11 acquires the linear distance between the center point 31a of the positioning member 30a and the center point 31b of the positioning member 30b in the second coordinate system as the second distance 35 (see FIG. 7) based on the second position information 33 in the second CT data 25.

[0049] Then, when the first distance 34 in the first CT data 23 and the second distance 35 in the second CT data 25 do not match, the image processing unit 11 enlarges or reduces at least one of the first CT data 23 and the second CT data 25 so that the first distance 34 and the second distance 35 match. This makes the subject magnification of the first CT data 23 and the subject magnification of the second CT data 25 match. In this embodiment, the image processing unit 11 is configured to enlarge or reduce the second CT data 25 so that the second distance 35 in the second CT data 25 matches the first distance 34 in the first CT data 23. In this case, the image processing unit 11 converts the second position information 33 in the second CT data 25 according to the enlargement or reduction of the second CT data 25. Note that the image processing unit 11 may be configured to enlarge or reduce the first CT data 23 so that the first distance 34 in the first CT data 23 matches the second distance 35 in the second CT data 25.

[0050] (Registration of the first and second CT data) The image processing unit 11 aligns the first CT data 23 and the second CT data 25 based on the first position information 32 and the second position information 33.

[0051] Specifically, the image processing unit 11 aligns the first CT data 23 with the second CT data 25 by aligning the position in each piece of the first position information 32 with the position in each piece of the second position information 33. That is, the image processing unit 11 aligns the position coordinates (P1, Q1, R1) of the center point 31a in the first CT data 23 with the position coordinates (S1, T1, U1) of the center point 31a in the second CT data 25. The image processing unit 11 also aligns the position coordinates (P2, Q2, R2) of the center point 31b in the first CT data 23 with the position coordinates (S2, T2, U2) of the center point 31b in the second CT data 25. The image processing unit 11 also aligns the position coordinates (P3, Q3, R3) of the center point 31c in the first CT data 23 with the position coordinates (S3, T3, U3) of the center point 31c in the second CT data 25. In this way, the first CT data 23 and the second CT data 25 are aligned with each other.

[0052] In addition, when the image processing unit 11 converts the second position information 33 in the second CT data 25 in accordance with the enlargement or reduction of the second CT data 25, the image processing unit 11 aligns the first CT data 23 with the second CT data 25 by matching the position in each piece of the first position information 32 with the position in each piece of the converted second position information 33.

[0053] (Registration process of the first CT data and the second CT data) The alignment process of the first CT data 23 and the second CT data 25 according to this embodiment will be described with reference to Fig. 8. The imaging operation is controlled by the imaging control unit 12. The acquisition of the first X-ray image data 22, the acquisition of the second X-ray image data 24, the generation of the first CT data 23, the generation of the second CT data 25, and the alignment of the first CT data 23 and the second CT data 25 are performed by the image processing unit 11. The order of the processing steps can be reversed or executed simultaneously as long as there is no contradiction between them.

[0054] In step S1, the image processor 11 performs X-ray photography of the first portion 41 of the subject 40 together with the three positioning members 30, and acquires a plurality of first X-ray image data 22 by photographing the subject 40 multiple times while rotating it around the axis 43. Then, the process proceeds to step S2.

[0055] In step S2, the photographing control unit 12 controls the moving unit to move the subject placement unit 61 upward along the axis 43 of the rotation shaft of the subject 40 so that the second portion 42 of the subject 40 is within the photographing range. Thereafter, the process proceeds to step S3.

[0056] In step S3, the image processor 11 X-rays a second portion 42 including an overlapping range 26 that overlaps with the imaging range of the first CT data 23 (first X-ray image data 22) and including a part of the first portion 41 of the subject 40 together with the three positioning members 30 arranged in the overlapping range 26, and acquires a plurality of second X-ray image data 24 by imaging the subject 40 a plurality of times while rotating it around the axis 43. Then, the process proceeds to step S4.

[0057] In step S4, the image processor 11 generates the first CT data 23 based on the plurality of first X-ray image data 22. After that, the process proceeds to step S5.

[0058] In step S5, the image processing unit 11 acquires first position information 32 of the center point 31 of the positioning member 30 in the first coordinate system based on the first CT data 23, and acquires a first distance 34 in the first coordinate system. After that, the process proceeds to step S6.

[0059] In step S6, the image processor 11 generates second CT data 25 based on the plurality of second X-ray image data 24. After that, the process proceeds to step S7.

[0060] In step S7, the image processing unit 11 acquires second position information 33 of the center point 31 of the positioning member 30 in the second coordinate system based on the second CT data 25, and acquires the second distance 35 in the second coordinate system. After that, the process proceeds to step S8.

[0061] In step S8, if the image processing unit 11 determines that the first distance 34 in the first CT data 23 and the second distance 35 in the second CT data 25 are different (Yes in step S8), the processing proceeds to step S9, and if the first distance 34 in the first CT data 23 and the second distance 35 in the second CT data 25 are the same (No in step S8), the processing proceeds to step S10.

[0062] In step S9, the image processing unit 11 enlarges or reduces the second CT data 25 so that the second distance 35 in the second CT data 25 matches the first distance 34 in the first CT data 23. This matches the subject magnification of the first CT data 23 with the subject magnification of the second CT data 25. The image processing unit 11 also converts the second position information 33 in the second CT data 25 in accordance with the enlargement or reduction of the second CT data 25.

[0063] In step S10, the image processing unit 11 aligns the first CT data 23 with the second CT data 25 by matching the positions in the first position information 32 with the positions in the second position information 33. Then, the process ends.

[0064] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0065] In this embodiment, as described above, the method for aligning three-dimensional image data includes the steps of generating three-dimensional first CT data 23 based on first X-ray image data 22 obtained by X-ray imaging by the imaging unit 1 of a first portion 41 of the subject 40 together with three positioning members 30 having an isotropic shape, generating three-dimensional second CT data 25 based on second X-ray image data 24 obtained by X-ray imaging by the imaging unit 1 of a second portion 42 including a part of the first portion 41 of the subject 40 together with three positioning members 30 arranged in the overlapping range 26, and aligning the first CT data 23 and the second CT data 25 based on the positioning members 30 having an isotropic shape in the first CT data 23 and the second CT data 25.

[0066] As a result, even if the positions of the parts of the subject are shifted between the CT data due to the inclination of the subject placement unit 61 or the movement (drift) of the X-ray focus, the first CT data 23 and the second CT data 25 can be aligned with high precision based on the three positioning members 30 arranged in the overlapping range 26 of the first CT data 23 and the second CT data 25. In addition, since the positioning member 30 has an isotropic shape in the first CT data 23 and the second CT data 25 generated based on the X-ray image data captured while rotating the positioning member 30, the center position of the positioning member 30 can be obtained with high precision. Therefore, the first CT data 23 and the second CT data 25 can be aligned with high precision based on the positioning member 30 having an isotropic shape, compared to the best fit method of aligning shape data that may include errors. For these reasons, the first CT data 23 and the second CT data 25 can be aligned with high precision. Therefore, a plurality of CT data can be aligned with high precision.

[0067] In addition, in this embodiment, as described above, the X-ray imaging device 100 is equipped with an image processing unit 11 that generates CT data based on multiple X-ray image data captured from multiple angles with different relative angles between the subject 40 and the imaging unit 1, and the image processing unit 11 generates three-dimensional first CT data 23 based on first X-ray image data 22 acquired by X-ray imaging of a first portion 41 of the subject 40 by the imaging unit 1 together with three positioning members 30 having an isotropic shape, generates three-dimensional second CT data 25 based on second X-ray image data 24 acquired by X-ray imaging of a second portion 42 including an overlapping range 26 that overlaps with the imaging range of the first CT data 23 and including a part of the first portion 41 of the subject 40 by the imaging unit 1 together with three positioning members 30 arranged in the overlapping range 26, and aligns the first CT data 23 and the second CT data 25 based on the positioning members 30 having an isotropic shape in the first CT data 23 and the second CT data 25.

[0068] As a result, similarly to the above-mentioned method for aligning three-dimensional image data, even if the positions of the parts of the subject are shifted between the CT data due to the inclination of the subject placement unit 61 or the movement (drift) of the X-ray focus, the first CT data 23 and the second CT data 25 can be aligned with high precision based on the three positioning members 30 arranged in the overlapping range 26 of the first CT data 23 and the second CT data 25. In addition, since the positioning member 30 has an isotropic shape in the first CT data 23 and the second CT data 25 generated based on the X-ray image data captured while rotating the positioning member 30, the center position of the positioning member 30 can be obtained with high precision. Therefore, the first CT data 23 and the second CT data 25 can be aligned with high precision based on the positioning member 30 having an isotropic shape, compared to the best-fit method for aligning shape data that may include errors. For these reasons, the first CT data 23 and the second CT data 25 can be aligned with high precision. Therefore, it is possible to provide the X-ray imaging apparatus 100 capable of aligning a plurality of CT data with high accuracy.

[0069] In addition, in the above embodiment, the following additional effects can be obtained by configuring as follows.

[0070] That is, in this embodiment, as described above, the positioning member 30 has an isotropic shape that is point-symmetric with respect to the center of the positioning member 30, and in the step of performing alignment, the first CT data 23 and the second CT data 25 are aligned based on the point-symmetric shape of the positioning member 30. Since the positioning member 30 has a point-symmetric shape, the center position of the positioning member 30 in the first CT data 23 and the second CT data 25 can be obtained with higher accuracy. Therefore, the first CT data 23 and the second CT data 25 can be aligned with higher accuracy.

[0071] In this embodiment, as described above, the positioning member 30 has a spherical shape that is point-symmetric, and in the step of performing alignment, the first CT data 23 and the second CT data 25 are aligned based on the center position of the spherical positioning member 30. Since the positioning member 30 has a spherical shape, the center position of the positioning member 30 can be easily and accurately acquired. Therefore, the first CT data 23 and the second CT data 25 can be easily and accurately aligned.

[0072] In the present embodiment, as described above, in the step of performing alignment, a first distance 34 between two of the three positioning members 30 in the first CT data 23 and a second distance 35 between the two positioning members 30 corresponding to the first distance 34 in the second CT data 25 are acquired, and alignment between the first CT data 23 and the second CT data 25 is performed by enlarging or reducing one of the first CT data 23 and the second CT data 25 so as to match the first distance 34 and the second distance 35. As a result, even if the subject magnification in the first CT data 23 and the subject magnification in the second CT data 25 are different, the subject magnification in the first CT data 23 and the subject magnification in the second CT data 25 can be matched by enlarging or reducing one of the first CT data 23 and the second CT data 25 so as to match the first distance 34 and the second distance 35. Therefore, the first CT data 23 and the second CT data 25, which have different subject magnifications, can be aligned with higher accuracy by matching the subject magnifications.

[0073] In this embodiment, as described above, the central positions of the three positioning members 30 are configured to specify one plane, not on the same line. This differs from an arrangement in which the positioning members 30 are aligned on the same line, and when aligning the first CT data 23 and the second CT data 25 based on the positioning members 30, the position and angle (tilt) of the subject 40 can be aligned by aligning the planes. This allows the first CT data 23 and the second CT data 25 to be aligned with even greater precision.

[0074] Furthermore, this embodiment further includes a step of acquiring a first X-ray image and a second X-ray image by X-ray photography in a state where the positioning jig 50 provided with the three positioning members 30 is placed on the subject placement unit 61 that rotates about an axis of rotation perpendicular to the straight line connecting the X-ray source 2 and the detector 3 as described above. This allows the positioning members 30 to be placed around the subject 40 without directly fixing each of the positioning members 30 to the subject 40. Therefore, the boundary between the positioning members 30 and the subject 40 is clear, and the subject 40 can be easily visually recognized.

[0075] Furthermore, in this embodiment, as described above, the positioning jig 50 is formed of a tubular member provided with the three positioning members 30 and surrounding the periphery of the subject 40. This allows the three positioning members 30 to be arranged so as to surround the periphery of the subject 40. Therefore, by using the tubular member, it is possible to easily arrange each of the three positioning members 30 at a distance from each other around the subject 40.

[0076] In the present embodiment, as described above, in the step of generating the second CT data 25, the overlapping range 26 that overlaps with the imaging range of the first CT data 23 is generated to include a first range 26a that overlaps in the axial direction of the rotation axis of the subject 40 perpendicular to the line connecting the X-ray source 2 and the detector 3. This makes it possible to precisely align the first CT data 23 and the second CT data 25 that are generated by sequentially capturing X-rays in the axial direction of the rotation axis of the subject 40.

[0077] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications (variations) within the meaning and scope of the claims.

[0078] For example, in the above embodiment, a positioning member is disposed in the overlapping range 26 where the imaging range of the first CT data 23 and the imaging range of the second CT data 25 overlap, and the two CT data of the first CT data 23 and the second CT data 25 are aligned based on the positioning member, but the present invention is not limited to this. For example, the present invention may be configured to align three or more CT data.

[0079] FIG. 9 for explaining the first modified example is a schematic diagram showing an example of a positioning jig 51 and positioning members 30d, 30e for explaining the alignment of three CT data. The positioning jig 51 is provided with three positioning members 30d belonging to the first group and three positioning members 30e belonging to the second group. The three positioning members 30d belonging to the first group are provided at positions corresponding to an overlapping range 26c where the imaging range of the third CT data (imaging range 27a of the third X-ray image data) and the imaging range of the fourth CT data (imaging range 27b of the fourth X-ray image data) overlap. The three positioning members 30e belonging to the second group are provided at positions corresponding to an overlapping range 26d where the imaging range of the fourth CT data (imaging range 27b of the fourth X-ray image data) and the imaging range of the fifth CT data (imaging range 27c of the fifth X-ray image data) overlap. The image processor is configured to align the third CT data with the fourth CT data based on the positioning member 30d belonging to the first group, and to align the fourth CT data with the fifth CT data based on the positioning member 30e belonging to the second group. The alignment of four or more CT data can be performed in the same manner as the alignment of three CT data. The relative positional relationship between the three positioning members 30d belonging to the first group and the relative positional relationship between the three positioning members 30e belonging to the second group may be the same or different.

[0080] In the above embodiment, the overlapping range overlapping with the imaging range of the first CT data (imaging range of the first X-ray image data) includes the first range 26a overlapping in the axial direction of the rotation axis of the subject perpendicular to the straight line connecting the X-ray source and the detector, but the present invention is not limited to this. For example, as shown in Figs. 10 and 11 for explaining the second modified example, the overlapping range overlapping with the imaging range of the first CT data (imaging range of the first X-ray image data) may include the second range 26b overlapping in the in-plane direction of the horizontal plane including the straight line connecting the X-ray source and the detector. Also, in the second modified example, the alignment of three or more CT data may be performed as in the first modified example. Note that Figs. 10 and 11 show an example of a positioning jig 52 and a positioning member 30f for explaining the alignment of the imaging ranges of four CT data (imaging ranges 28 of four X-ray image data).

[0081] In this case, the positioning member 30f is provided at a position in the positioning jig 52 corresponding to the second range 26b where the imaging ranges of the CT data overlap. In the positioning jig, at least three positioning members 30f may be arranged in the second range 26b where the imaging ranges of at least two pieces of CT data to be aligned are overlapped. For example, as shown in FIG. 10, the positioning jig 52 may have three positioning members 30f arranged in the second range 26b where the imaging ranges of the two pieces of CT data to be aligned are overlapped, or as shown in FIG. 11, the positioning jig 52 may have three positioning members 30f arranged in the second range 26b where the imaging ranges of the four pieces of CT data to be aligned are overlapped.

[0082] In the second modification, in the step of generating the second CT data, the second CT data is generated so as to include a second range that overlaps with the imaging range of the first CT data in an in-plane direction of a horizontal plane including a straight line connecting the X-ray source and the detector. This makes it possible to precisely align the first CT data and the second CT data generated by sequentially performing X-ray imaging in the in-plane direction of a horizontal plane including a straight line connecting the X-ray source and the detector of the subject.

[0083] Furthermore, as in a third modified example shown in FIG. 12, the overlapping range that overlaps with the imaging range of the first CT data may be configured to include both a first range 26a that overlaps in the axial direction of the subject's rotation axis perpendicular to the line connecting the X-ray source and the detector, and a second range 26b that overlaps in the in-plane direction of a horizontal plane including the line connecting the X-ray source and the detector.

[0084] In the above embodiment, the first CT data and the second CT data are aligned based on three positioning members provided at positions corresponding to the overlapping range of the positioning jig, but the present invention is not limited to this. For example, the first CT data and the second CT data may be aligned based on four or more positioning members provided at positions corresponding to the overlapping range of the positioning jig.

[0085] In the above embodiment, the positioning member is fixed to the outer circumferential surface of the positioning jig, but the present invention is not limited to this. For example, the positioning member may be fixed to the inner circumferential surface of the positioning jig. The positioning member may be fitted and fixed into at least three holes or at least three recesses formed in the positioning jig. The positioning member may be composed of at least three recesses (spaces) having an isotropic shape formed in the positioning jig.

[0086] In the above embodiment, the positioning member has a spherical shape as a point-symmetric shape, but the present invention is not limited to this. For example, the point-symmetric shape may be any one of a regular hexahedron (cube), a regular octahedron, a regular dodecahedron, and a regular icosahedron. As long as the positioning member has an isotropic shape, it does not have to have a point-symmetric shape, and may be, for example, a regular tetrahedron or a spheroid.

[0087] In the above embodiment, the positioning member is provided on the positioning jig, but the present invention is not limited to this. For example, the positioning member may be directly fixed to the subject.

[0088] In the above embodiment, the step of performing the alignment includes enlarging or reducing at least one of the first CT data and the second CT data so that at least one first distance and at least one second distance are matched, but the present invention is not limited to this. For example, a plurality of distances between the center points of a plurality of positioning members may be obtained, and at least one of the first CT data and the second CT data may be enlarged or reduced so that the obtained distances are matched. In addition, the step of performing the alignment may be configured to align the first CT data and the second CT data based on the center position of the positioning member without matching the first distance and the second distance and without enlarging or reducing at least one of the first CT data and the second CT data.

[0089] In the above embodiment, the central positions of the at least three positioning members are configured to define one plane, but the present invention is not limited to this. For example, the central positions of the at least three positioning members may be arranged on the same straight line.

[0090] In the above embodiment, the ratio of the overlapping range of the first CT data imaging range (imaging range of the first X-ray image data) and the second CT data imaging range (imaging range of the second X-ray image data) in the horizontal direction occupied by one positioning member is 1 / 20 or less, but the present invention is not limited to this. For example, the ratio of the overlapping range in the horizontal direction occupied by one positioning member may be more than 1 / 20.

[0091] In the above embodiment, the image processor matches the first distance and the second distance when the first distance in the first CT data and the second distance in the second CT data do not match, thereby matching the subject magnification of the first CT data and the subject magnification of the second CT data, but the present invention is not limited to this. Instead of matching the first distance and the second distance, the image processor may be configured as follows.

[0092] For example, in the third modified example, the image processor 11 acquires at least one of the measured distance between the center point of the positioning member 30a and the center point of the positioning member 30b, the measured distance between the center point of the positioning member 30a and the center point of the positioning member 30c, and the measured distance between the center point of the positioning member 30b and the center point of the positioning member 30c, based on the position coordinates of the positioning member in the positioning jig measured in advance by a contact or non-contact three-dimensional coordinate measuring device (not shown). The image processor 11 may be configured to correct the magnification of the first CT data 23 by matching the measured distance between at least one of the acquired center points with a first distance 34 in the first CT data 23 (see FIG. 6), and to correct the magnification of the second CT data 25 by matching the measured distance between at least one of the acquired center points with a second distance 35 in the second CT data 25 (see FIG. 7). The measured distance between the center points of the positioning members 30 measured in advance may be stored in the storage unit 20, and the image processing unit 11 may be configured to acquire the measured distance between the center points of the positioning members 30 stored in the storage unit 20. The three-dimensional coordinate measuring device includes a contact type measuring device that performs measurement by bringing a probe into contact with a measurement object, and a non-contact type measuring device that performs measurement by irradiating the measurement object with laser light or the like.

[0093] In the third modified example, as described above, in the step of performing alignment, a first distance 34 between at least two of the at least three positioning members 30 in the first CT data 23 and a second distance 35 between the at least two positioning members 30 corresponding to the first distance 34 in the second CT data 25 are obtained, a measured distance between at least two of the at least three positioning members 30 obtained based on a three-dimensional coordinate measurement of the positioning members 30 is obtained, and the first CT data 23 is enlarged or reduced so as to match the measured distance with the first distance 34, and the second CT data 25 is enlarged or reduced so as to match the measured distance with the second distance 35, thereby performing alignment between the first CT data 23 and the second CT data 25. This makes it possible to align the first CT data 23 and the second CT data 25, which have different subject magnifications, with more accuracy by matching the subject magnifications based on the measured distances obtained from the three-dimensional coordinate measuring device.

[0094] [Aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0095] (Item 1) generating three-dimensional first CT data based on first X-ray image data acquired by X-raying a first portion of a subject together with at least three positioning members having an isotropic shape; generating three-dimensional second CT data based on second X-ray image data acquired by X-raying a second portion including a part of the first portion of the subject, the second portion including an overlapping range that overlaps with an imaging range of the first CT data, together with the at least three positioning members arranged in the overlapping range; A method for aligning three-dimensional image data, comprising: a step of aligning the first CT data and the second CT data based on the positioning member having an isotropic shape in the first CT data and the second CT data.

[0096] (Item 2) the positioning member has a shape that is point-symmetric with respect to a center of the positioning member as the isotropic shape, 2. The method for aligning three-dimensional image data according to item 1, wherein in the step of performing alignment, alignment between the first CT data and the second CT data is performed based on a point-symmetric shape of the positioning member.

[0097] (Item 3) The positioning member has a spherical shape as the point-symmetric shape, 3. The method for aligning three-dimensional image data according to claim 2, wherein in the step of performing alignment, alignment between the first CT data and the second CT data is performed based on a center position of the spherical positioning member.

[0098] (Item 4) In the step of performing the alignment, Obtaining a first distance between at least two of the at least three positioning members in the first CT data and a second distance between the at least two of the positioning members corresponding to the first distance in the second CT data; 2. The method for aligning three-dimensional image data according to claim 1, further comprising: enlarging or reducing at least one of the first CT data and the second CT data so as to match the first distance and the second distance, thereby aligning the first CT data and the second CT data.

[0099] (Item 5) 2. The method for registering three-dimensional image data according to item 1, wherein the central positions of each of the at least three positioning members are configured to identify a plane rather than being on the same straight line.

[0100] (Item 6) 2. The method for aligning three-dimensional image data described in item 1, further comprising a step of acquiring the first X-ray image and the second X-ray image by placing a positioning jig having at least three positioning members on a subject mounting part that rotates about a rotation axis perpendicular to a line connecting an X-ray source and a detector, and then performing X-ray photography.

[0101] (Item 7) 7. The method for aligning three-dimensional image data according to item 6, wherein the positioning jig is formed by a cylindrical member having the at least three positioning members provided thereon and surrounding the subject.

[0102] (Item 8) 2. The method for aligning three-dimensional image data according to claim 1, wherein, in the step of generating the second CT data, the second CT data is generated so as to include at least a first range that overlaps with the imaging range of the first CT data, the first range being an overlap in an axial direction of a rotation axis of the subject that is perpendicular to a straight line connecting an X-ray source and a detector.

[0103] (Item 9) 2. The method for aligning three-dimensional image data according to claim 1, wherein, in the step of generating the second CT data, the second CT data is generated so as to include at least a second range that overlaps with the imaging range of the first CT data in an in-plane direction of a horizontal plane that includes a straight line connecting an X-ray source and a detector.

[0104] (Item 10) In the step of performing the alignment, Obtaining a first distance between at least two of the at least three positioning members in the first CT data and a second distance between the at least two of the positioning members corresponding to the first distance in the second CT data; obtaining a measured distance between at least two of the at least three positioning members, the measured distance being obtained based on a three-dimensional coordinate measurement relative to the positioning members; 2. The method for aligning three-dimensional image data according to claim 1, further comprising: enlarging or reducing the first CT data so as to match the measured distance with the first distance, and enlarging or reducing the second CT data so as to match the measured distance with the second distance, thereby aligning the first CT data with the second CT data.

[0105] (Item 11) an imaging unit that includes an X-ray source that irradiates X-rays and a detector that detects the X-rays irradiated from the X-ray source and that images an object; and an image processing unit that generates CT data based on a plurality of X-ray image data captured from a plurality of angles having different relative angles between the subject and the imaging unit, The image processing unit includes: generating three-dimensional first CT data based on first X-ray image data acquired by X-raying a first portion of the subject together with at least three positioning members having an isotropic shape by the imaging unit; generating three-dimensional second CT data based on second X-ray image data acquired by X-ray shooting a second portion including a part of the first portion of the subject, together with the at least three positioning members arranged in the overlapping range, by the imaging unit; An X-ray imaging apparatus that aligns the first CT data and the second CT data based on the positioning member having an isotropic shape in the first CT data and the second CT data.

[0106] (Item 12) a subject placement unit disposed between the X-ray source and the detector, for placing the subject thereon, and rotating about a rotation axis perpendicular to a line connecting the X-ray source and the detector; Item 12. The X-ray imaging apparatus according to item 11, wherein the positioning member is provided on a positioning jig that is placed on the subject placement portion.

[0107] (Item 13) Item 13. The X-ray imaging apparatus according to item 12, wherein the positioning jig is formed by a tubular member provided with the at least three positioning members and surrounding the subject. [Explanation of symbols]

[0108] 1. Filming Department 2 X-ray source 3. Detector 10 Control section 11 Image processing section 22 First X-ray image data 23 First CT data 24 Second X-ray image data 25 Second CT data 26, 26c, 26d overlapping range 26a 1st range 26b Second Range 30, 30a, 30b, 30c, 30d, 30e, 30f Positioning members 32 1st location information 33 Second location information 34 1st distance 35 2nd distance 36 plane 40 Subject 41 Part 1 42 Part 2 50, 51, 52, 53 Positioning jig 61 Subject placement section 100 X-ray equipment

Claims

1. generating three-dimensional first CT data based on first X-ray image data acquired by X-raying a first portion of a subject together with at least three positioning members having an isotropic shape; generating three-dimensional second CT data based on second X-ray image data acquired by X-raying a second portion including a part of the first portion of the subject, the second portion including an overlapping range that overlaps with an imaging range of the first CT data, together with the at least three positioning members arranged in the overlapping range; A method for aligning three-dimensional image data, comprising a step of aligning the first CT data and the second CT data based on the positioning member having an isotropic shape in the first CT data and the second CT data.

2. the positioning member has a shape that is point-symmetric with respect to a center of the positioning member as the isotropic shape, 2. The method for aligning three-dimensional image data according to claim 1, wherein in the step of performing alignment, alignment between the first CT data and the second CT data is performed based on a point-symmetric shape of the positioning member.

3. The positioning member has a spherical shape as the point-symmetric shape, 3. The method for aligning three-dimensional image data according to claim 2, wherein in the step of performing alignment, alignment between the first CT data and the second CT data is performed based on a center position of the spherical positioning member.

4. In the step of performing the alignment, Obtaining a first distance between at least two of the at least three positioning members in the first CT data and a second distance between the at least two of the positioning members corresponding to the first distance in the second CT data; The method for aligning three-dimensional image data according to claim 1, further comprising the step of: enlarging or reducing at least one of the first CT data and the second CT data so as to match the first distance and the second distance, thereby aligning the first CT data and the second CT data.

5. The method of claim 1 , wherein the central positions of each of the at least three positioning members are configured to specify a plane that is not collinear.

6. 2. The method for aligning three-dimensional image data according to claim 1, further comprising a step of acquiring the first X-ray image and the second X-ray image by taking X-rays while a positioning jig having at least three positioning members is placed on a subject placement unit that rotates about a rotation axis perpendicular to a line connecting an X-ray source and a detector.

7. 7. The method for aligning three-dimensional image data according to claim 6, wherein the positioning jig is formed of a tubular member having the at least three positioning members provided thereon and surrounding the subject.

8. 2. The method for aligning three-dimensional image data according to claim 1, wherein in the step of generating the second CT data, the second CT data is generated so as to include at least a first range that overlaps with the imaging range of the first CT data, the first range including a first range that overlaps in an axial direction of a rotation axis of the subject that is perpendicular to a straight line connecting an X-ray source and a detector.

9. 2. The method for aligning three-dimensional image data according to claim 1, wherein in the step of generating the second CT data, the second CT data is generated to include at least a second range that overlaps with the imaging range of the first CT data in an in-plane direction of a horizontal plane that includes a straight line connecting an X-ray source and a detector.

10. In the step of performing the alignment, Obtaining a first distance between at least two of the at least three positioning members in the first CT data and a second distance between the at least two of the positioning members corresponding to the first distance in the second CT data; obtaining a measured distance between at least two of the at least three positioning members, the measured distance being obtained based on a three-dimensional coordinate measurement relative to the positioning members; 2. The method for aligning three-dimensional image data according to claim 1, further comprising the steps of: enlarging or reducing the first CT data so as to match the measurement distance with the first distance; and enlarging or reducing the second CT data so as to match the measurement distance with the second distance, thereby aligning the first CT data with the second CT data.

11. an imaging unit that includes an X-ray source that irradiates X-rays and a detector that detects the X-rays irradiated from the X-ray source and that images an object; an image processing unit that generates CT data based on a plurality of X-ray image data captured from a plurality of angles that differ in relative angle between the subject and the imaging unit, The image processing unit includes: generating three-dimensional first CT data based on first X-ray image data acquired by X-raying a first portion of the subject together with at least three positioning members having an isotropic shape by the imaging unit; generating three-dimensional second CT data based on second X-ray image data acquired by X-ray imaging using the imaging unit, the second portion including an overlapping range that overlaps with an imaging range of the first CT data and including a part of the first portion of the subject together with the at least three positioning members arranged in the overlapping range; An X-ray imaging apparatus that aligns the first CT data and the second CT data based on the positioning member having an isotropic shape in the first CT data and the second CT data.

12. a subject placement unit disposed between the X-ray source and the detector, on which the subject is placed and which rotates about a rotation axis perpendicular to a line connecting the X-ray source and the detector; The X-ray imaging apparatus according to claim 11 , wherein the positioning member is provided on a positioning jig that is arranged on the subject placement portion.

13. 13. The X-ray imaging apparatus according to claim 12, wherein the positioning jig is formed of a tubular member provided with the at least three positioning members and surrounding the subject.

Images