JP7816538B2 - X-ray phase imaging system and X-ray phase imaging method - Google Patents

Description

The present invention relates to an X-ray phase imaging system and an X-ray phase imaging method, and more particularly to an X-ray phase imaging system and an X-ray phase imaging method that image an object while rotating the object and an imaging system relative to each other.

Conventionally, X-ray phase imaging systems are known that image a subject while rotating the subject and the imaging system relative to each other. Such an X-ray phase imaging system is disclosed, for example, in Japanese Patent Application Laid-Open No. 2019-45394.

JP 2019-45394 A discloses an X-ray imaging device including an X-ray source, an X-ray detector, multiple gratings arranged between the X-ray source and the X-ray detector, and a rotation mechanism. The rotation mechanism is configured to rotate the subject around an axis extending perpendicular to the X-ray irradiation axis. In other words, the X-ray imaging device disclosed in JP 2019-45394 A is configured to generate three-dimensional images. Furthermore, in JP 2019-45394 A, the X-ray imaging device is configured to image carbon fiber reinforced plastic (CFRP) as the subject.

JP 2019-45394 A

Here, it is known that CFRP containing carbon fibers has high mechanical strength (e.g., tensile strength) in the direction in which the fibers extend, but low mechanical strength (tensile strength) in the direction intersecting the direction in which the fibers extend. Therefore, to increase the mechanical strength (tensile strength) in a specific direction, CFRP is sometimes molded with the carbon fibers oriented in a specific direction. CFRP is composed of a resin matrix and carbon fibers, and during the molding process, the carbon fibers may be oriented in a direction different from the specific direction. For example, during the molding process of CFRP (subject), carbon fibers oriented along the plane of the subject to improve the tensile strength within a specific plane of the subject may be oriented in a direction intersecting the plane of the subject. In this case, the tensile strength within the plane of the subject decreases. Therefore, depending on the direction of the carbon fibers (fibers) in the CFRP (subject), the mechanical strength within the plane of the subject may decrease. However, the X-ray imaging device (X-ray phase imaging system) disclosed in JP 2019-45394 A generates a three-dimensional image of a subject, but is not configured to generate an image that allows a user to easily identify the location of reduced mechanical strength of the subject within a predetermined plane of the subject, including fibers. In this case, it is difficult for a user to identify the location of reduced mechanical strength of the subject within a predetermined plane of the subject, including fibers. Therefore, there is a need for an X-ray phase imaging system that allows a user to easily identify the location of reduced mechanical strength of a subject, including fibers, within a desired plane.

This invention has been made to solve the above-mentioned problems, and one object of this invention is to provide an X-ray phase imaging system and an X-ray phase imaging method that can easily identify the location where the mechanical strength of a subject containing fibers is reduced within a plane desired by the user.

In order to achieve the above object, an X-ray phase imaging system in a first aspect of the present invention is an X-ray phase imaging system that extracts fibers contained in a subject, and comprises: an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects X-rays irradiated from the X-ray source, and multiple gratings arranged between the X-ray source and the X-ray detector; a first rotation mechanism that relatively rotates the subject and the imaging system in a direction perpendicular to the X-ray irradiation axis; an image processing unit that generates a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the X-ray intensity distribution detected by the X-ray detector by imaging at multiple imaging angles while rotating the subject and the imaging system relatively using the first rotation mechanism; a filter processing unit that performs filtering using a filter to extract linear portions extending along a predetermined direction contained in the subject on a predetermined cross-section of the dark-field image at multiple angles with different filter angles on the predetermined cross-section; and a linear portion image generation unit that generates a linear portion image based on the multiple linear portions corresponding to the fibers extracted by the filtering processing unit.

In addition, an X-ray phase imaging method in a second aspect of the present invention is an X-ray phase imaging method for extracting fibers contained in a subject, and includes the steps of: imaging the subject, an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects X-rays irradiated from the X-ray source, and a plurality of gratings arranged between the X-ray source and the X-ray detector, while rotating them relatively in a rotational direction about a direction perpendicular to the X-ray irradiation axis, generating a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the intensity distribution of X-rays detected by the X-ray detector at the plurality of imaging angles; performing filtering using a filter that extracts linear portions extending along a predetermined direction contained in the subject on a predetermined cross-section of the dark-field image for a plurality of angles with different filter angles on the predetermined cross-section; and generating a linear portion image based on the extracted linear portions corresponding to the fibers.

In the X-ray phase imaging system of the first aspect and the X-ray phase imaging method of the second aspect, a linear portion image is generated based on a plurality of linear portions corresponding to fibers extracted by filtering, as described above. This allows the user to grasp the distribution of fibers in a given cross-section of the subject through the linear portion image, which is an image of linear portions corresponding to fibers in the given cross-section of the subject. Therefore, the user can grasp the locations of reduced mechanical strength in a fiber-containing subject within a plane perpendicular to the given cross-section. As a result, the user can easily grasp the locations of reduced mechanical strength in a fiber-containing subject within a desired plane by checking the linear portion image in the given cross-section of the subject.

1 is a schematic diagram showing the overall configuration of an X-ray phase imaging system according to an embodiment. 2 is a schematic diagram for explaining the configuration of a first rotation mechanism and a second rotation mechanism of an X-ray phase imaging system according to one embodiment. FIG. 1 is a schematic diagram for explaining the configuration of a grating position adjustment mechanism of an X-ray phase imaging system according to an embodiment. FIG. FIG. 2 is a schematic diagram for explaining a configuration for generating an X-ray phase contrast image. 1A and 1B are schematic diagrams for explaining a three-dimensional absorption image, a three-dimensional differential phase image, and a three-dimensional dark-field image generated by an X-ray phase imaging system according to an embodiment. 3A and 3B are schematic diagrams for explaining the shape and thickness direction cross section of a subject; FIG. 2 is a schematic diagram for explaining undulations of fibers in a cross section in the thickness direction. FIG. 2 is a schematic diagram of a dark-field image of a cross section along the thickness direction of a subject. 10A and 10B are schematic diagrams illustrating a configuration in which a filter processing unit according to an embodiment acquires an angle of a line portion. 10 is a schematic diagram for explaining a configuration in which a linear portion image generating unit generates a linear portion image according to an embodiment. FIG. 10A and 10B are schematic diagrams for explaining a plurality of dark-field images captured by changing the angle of the subject relative to a plurality of gratings. FIG. 10 is a schematic diagram illustrating a configuration for generating a composite extracted image from a plurality of linear partial images. 10A and 10B are schematic diagrams illustrating a first projection image generated by vector average projection, among the first projection images generated by the projection image generating unit according to an embodiment. 10 is a schematic diagram for explaining a first projection image generated by maximum intensity projection, among first projection images generated by a projection image generating unit according to an embodiment; FIG. 10A and 10B are schematic diagrams for explaining a second projected image generated by a projected image generating unit according to an embodiment. 1 is a schematic diagram for explaining a configuration in which an X-ray phase imaging system according to an embodiment displays a dark-field image, a first projection image, and a second projection image. 10 is a flowchart illustrating a process for displaying a projection image in an X-ray phase imaging system according to an embodiment. 10 is a schematic diagram for explaining a fiber direction weighted image generated by an X-ray phase imaging system according to a modified example. FIG.

Below, an embodiment of the present invention is described based on the drawings.

First, referring to Figure 1, we will explain the overall configuration of an X-ray phase imaging system 100 according to one embodiment of the present invention.

As shown in FIG. 1, the X-ray phase imaging system 100 is a device that uses the Talbot effect to image the interior of a subject 90. In this embodiment, the X-ray phase imaging system 100 is configured to extract fibers 90b (see FIG. 7) contained in the subject 90. The subject 90 is, for example, a fiber composite material containing fibers 90b. The subject 90 is, for example, CFRP.

The X-ray phase imaging system 100 includes an imaging system 6, a first rotation mechanism 7, and a computer 8. In this embodiment, the X-ray phase imaging system 100 also includes a second rotation mechanism 9, a display unit 10, an input reception unit 11, and a grating position adjustment mechanism 12.

The imaging system 6 includes an X-ray source 1, an X-ray detector 2, and multiple gratings. The multiple gratings are arranged between the X-ray source 1 and the X-ray detector 2. The multiple gratings include a first grating 3, a second grating 4, and a third grating 5. In this specification, the vertical direction is referred to as the Z direction, with the upward direction referred to as the Z1 direction and the downward direction referred to as the Z2 direction. The direction from the X-ray source 1 toward the X-ray detector 2 is referred to as the X direction, with one side referred to as the X1 direction and the other side referred to as the X2 direction. The direction perpendicular to the Z direction and X direction is referred to as the Y direction, with one side referred to as the Y1 direction and the other side referred to as the Y2 direction. In other words, Figure 1 is a schematic diagram of the X-ray phase imaging system 100 viewed from the Z1 direction.

In the X-ray phase imaging system 100, the X-ray source 1, the third grating 5, the first grating 3, the second grating 4, and the X-ray detector 2 are arranged in this order along the X-ray irradiation axis 50. That is, the third grating 5, the first grating 3, and the second grating 4 are arranged between the X-ray source 1 and the X-ray detector 2.

The X-ray source 1 is configured to irradiate the subject 90 with X-rays. Specifically, the X-ray source 1 is configured to generate X-rays when a high voltage is applied.

The X-ray detector 2 is configured to detect X-rays emitted from the X-ray source 1. The X-ray detector 2 is also configured to convert the detected X-rays into an electrical signal. The X-ray detector 2 is, for example, an FPD (Flat Panel Detector). The X-ray detector 2 is composed of multiple conversion elements (not shown) and pixel electrodes (not shown) arranged on the multiple conversion elements. The multiple conversion elements and pixel electrodes are arranged in the Y and Z directions at a predetermined period (pixel pitch). The detection signal (image signal) of the X-ray detector 2 is sent to the image processing unit 81, which will be described later.

The first grating 3 is positioned between the X-ray source 1 and the X-ray detector 2, and is irradiated with X-rays from the X-ray source 1. The first grating 3 has slits 3a and X-ray phase shifters 3b arranged at a predetermined period (grating pitch) 3c in the Y direction. Each slit 3a and X-ray phase shifter 3b is formed to extend linearly in the Z direction. The first grating 3 is a so-called phase grating. The first grating 3 is positioned between the X-ray source 1 and the second grating 4, and is provided to form a self-image (via the Talbot effect) using the X-rays irradiated from the X-ray source 1. The Talbot effect means that when coherent X-rays pass through a grating with slits formed in it, an image of the grating (self-image) is formed at a position a predetermined distance (Talbot distance) from the grating.

The second grating 4 is irradiated with X-rays from the first grating 3. The second grating 4 has a plurality of X-ray transparent portions 4a and X-ray absorbing portions 4b arranged at a predetermined period (grating pitch) 4c in the Y direction. Each X-ray transparent portion 4a and X-ray absorbing portion 4b is formed to extend linearly in the Z direction. The second grating 4 is a so-called absorption grating. The second grating 4 is positioned between the first grating 3 and the X-ray detector 2 and is configured to interfere with the self-image formed by the first grating 3. The second grating 4 is positioned at a Talbot distance from the first grating 3 to cause interference between the self-image and the second grating 4.

The third grating 5 is positioned between the X-ray source 1 and the first grating 3. The third grating 5 has a plurality of slits 5a and X-ray absorbing portions 5b arranged at a predetermined period (pitch) 5c in the Y direction. Each slit 5a and X-ray absorbing portion 5b is formed to extend linearly in the Z direction. Furthermore, each slit 5a and X-ray absorbing portion 5b is formed to extend parallel to one another. The third grating 5 is positioned between the X-ray source 1 and the first grating 3, and X-rays are irradiated from the X-ray source 1. The third grating 5 is configured to convert X-rays passing through each slit 5a into a line light source corresponding to the position of each slit 5a.

In this embodiment, the first grating 3, the second grating 4, and the third grating 5 are each arranged so that the grating pattern extends in the Z direction. The grating pattern includes slits 3a, X-ray phase change portions 3b, X-ray transmission portions 4a, X-ray absorption portions 4b, slits 5a, and X-ray absorption portions 5b.

The first rotation mechanism 7 is configured to rotate the subject 90 and the imaging system 6 relative to each other in a rotational direction about a direction perpendicular to the X-ray irradiation axis 50. Specifically, the first rotation mechanism 7 is configured to rotate the subject 90 relative to the imaging system 6 by rotating the subject 90 in a first rotational direction about a first axis 51 (see FIG. 2) that is perpendicular to the X-ray irradiation axis 50. In addition, in this embodiment, the first rotation mechanism 7 holds the second rotation mechanism 9. That is, the first rotation mechanism 7 rotates the subject 90 in the first rotational direction by rotating the second rotation mechanism 9 in the first rotational direction about the first axis 51. The detailed configuration of the first rotation mechanism 7 will be described later.

Computer 8 includes a processor 8a such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (Field-Programmable Gate Array) configured for image processing, and circuitry, as well as memory such as ROM (Read Only Memory) and RAM (Random Access Memory). Computer 8 also includes a storage unit 8b.

The processor 8a includes a control unit 80, an image processing unit 81, a filter processing unit 82, a linear partial image generation unit 83, and a projection image generation unit 84. The control unit 80 is configured to control the X-ray source 1, the first rotation mechanism 7, the second rotation mechanism 9, the grid position adjustment mechanism 12, and the like. The control unit 80, the image processing unit 81, the filter processing unit 82, the linear partial image generation unit 83, and the projection image generation unit 84 are configured in software as functional blocks realized by the processor 8a executing various programs. The control unit 80, the image processing unit 81, the filter processing unit 82, the linear partial image generation unit 83, and the projection image generation unit 84 may also be configured in hardware by providing a dedicated processor (processing circuit).

The image processing unit 81 is configured to capture images at multiple imaging angles while rotating the subject 90 and the imaging system 6 relative to each other using the first rotation mechanism 7, thereby generating a three-dimensional X-ray phase contrast image 40 including a three-dimensional dark-field image 43 (see Figure 5) based on the intensity distribution of X-rays detected by the X-ray detector 2. Details of the configuration by which the image processing unit 81 generates the X-ray phase contrast image 40 will be described later.

The filter processing unit 82 is configured to perform filtering using a filter described below on a predetermined cross section of the dark-field image 43. Details of the filtering performed by the filter processing unit 82 will be described later.

The linear portion image generation unit 83 is configured to generate the linear portion image 45 (see Figure 10) described below. Details of the process by which the linear portion image generation unit 83 generates the linear portion image 45 will be described later.

The projection image generation unit 84 is configured to generate a two-dimensional first projection image 47 (see Figure 13) by projecting the linear partial image 45 in the thickness direction (C direction (see Figure 5)) of the subject 90. In addition, in this embodiment, it is configured to generate a two-dimensional second projection image 48 (see Figure 15) by projecting the three-dimensional dark field image 43 in the in-plane direction of the subject 90. Details of the process by which the projection image generation unit 84 generates the first projection image 47 and the second projection image 48 will be described later.

The memory unit 8b is configured to store the X-ray phase contrast image 40 generated by the image processing unit 81, the linear partial image 45 generated by the linear partial image generation unit 83, the first projection image 47 and the second projection image 48 generated by the projection image generation unit 84, and various programs executed by the processor 8a. The memory unit 8b includes a non-volatile storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

The second rotation mechanism 9 is configured to rotate the subject 90 and the multiple gratings relative to each other in a rotational direction around the X-ray irradiation axis 50. Specifically, the second rotation mechanism 9 rotates the subject 90 in a rotational direction around the X-ray irradiation axis 50, thereby rotating the subject 90 relative to the multiple gratings. When facing the X-ray source 1, the second rotation mechanism 9 rotates the subject 90 in a second rotational direction around a second axis 52 that is collinear with the X-ray irradiation axis 50 and passes through the center of the subject support unit 9a (see Figure 2), described below. The second rotation mechanism 9 is rotated in a first rotational direction around the first axis 51 by the first rotation mechanism 7. Therefore, the direction in which the second axis 52 extends can change depending on the angle at which the second rotation mechanism 9 is rotated by the first rotation mechanism 7.

The display unit 10 displays the X-ray phase contrast image 40 generated by the image processing unit 81. In this embodiment, the display unit 10 is configured to display a first projection image 47 (see Figure 13) and a second projection image 48 (see Figure 15). The display unit 10 includes, for example, a liquid crystal monitor.

The input reception unit 11 is configured to receive operational input from the operator. The input reception unit 11 includes input devices such as a keyboard and a mouse.

The grating position adjustment mechanism 12 is configured to be able to move the first grating 3 in the X direction, Y direction, Z direction, a rotational direction Rz around the Z axis (see Figure 3), a rotational direction Rx around the X axis (see Figure 3), and a rotational direction Ry around the Y axis (see Figure 3).

(First Rotation Mechanism and Second Rotation Mechanism)
Next, the configurations of the first rotation mechanism 7 and the second rotation mechanism 9 according to this embodiment will be described with reference to FIG.

The first rotation mechanism 7 includes a mounting portion 7a, a drive unit 7b that rotates the mounting portion 7a around the first axis 51, and an origin sensor (not shown) that detects the origin when rotating the mounting portion 7a. The mounting portion 7a has a circular shape when viewed from above. A mounting surface 7c on which the second rotation mechanism 9 is mounted is provided on the Z1 direction side of the mounting portion 7a. In this embodiment, the first rotation mechanism 7 holds the second rotation mechanism 9 by placing the second rotation mechanism 9 on the mounting portion 7a (mounting surface 7c). In the example shown in FIG. 2, the first axis 51 is an axis extending in the Z direction.

In this embodiment, the first rotation mechanism 7 is configured to detachably hold the second rotation mechanism 9. The mounting surface 7c is provided with a recess 7d that engages with an engaging portion 9e of the second rotation mechanism 9, which will be described later. The recess 7d is located at the center of rotation of the mounting surface 7c.

As shown in Figure 2, the second rotation mechanism 9 comprises a subject placement section 9a, a drive section 9b, a drive force transmission member 9c, and a support member 9d.

The subject 90 (see Figure 1) is placed on the subject placement section 9a. In this embodiment, the subject placement section 9a is made of a resin material that has a higher X-ray transmittance than metal and a lower degree of X-ray scattering than metal. Note that placing the subject 90 on the subject placement section 9a does not only mean that the subject 90 is placed on the subject placement section 9a, but also means that the subject 90 is fixed to the subject placement section 9a by, for example, adhering it to the subject placement section 9a.

The subject placement section 9a is connected to the drive section 9b via a drive force transmission member 9c. The subject placement section 9a is rotated by the rotation of the drive section 9b being transmitted via the drive force transmission member 9c.

The drive unit 9b is configured to apply a drive force to rotate the subject placement unit 9a. The drive unit 9b is located away from the subject placement unit 9a and outside the X-ray irradiation range. Specifically, as shown in FIG. 2, the drive unit 9b is located away from the subject placement unit 9a in the Z2 direction. The drive unit 9b includes a motor that generates a drive force and a pulley.

The driving force transmission member 9c is configured to rotate the subject placement unit 9a using the driving force applied from the drive unit 9b. The driving force transmission member 9c is made of a rubber material.

The support member 9d is made of a resin material. The support member 9d is configured to rotatably support the subject placement section 9a on one side. The support member 9d rotatably holds the subject placement section 9a on the Z1 side.

In addition, in this embodiment, the support member 9d is provided with an engagement portion 9e that engages with the first rotation mechanism 7 so that when the second rotation mechanism 9 is held by the first rotation mechanism 7, a vertical line that is on the surface of the subject placement portion 9a and passes through the center of rotation of the subject placement portion 9a and the first axis 51 are aligned in the same straight line.

(Grid position adjustment mechanism)
As shown in FIG. 3, the grating position adjustment mechanism 12 includes an X-direction linear motion mechanism 12a, a Z-direction linear motion mechanism 12b, a Y-direction linear motion mechanism 12c, a linear motion mechanism connection unit 12d, a stage support unit drive unit 12e, a stage support unit 12f, a stage drive unit 12g, and a stage 12h.

The X-direction linear motion mechanism 12a, the Z-direction linear motion mechanism 12b, and the Y-direction linear motion mechanism 12c are configured to be movable in the X-direction, Z-direction, and Y-direction, respectively. The X-direction linear motion mechanism 12a, the Z-direction linear motion mechanism 12b, and the Y-direction linear motion mechanism 12c include, for example, stepping motors. The grating position adjustment mechanism 12 is configured to move the first grating 3 in the X-direction, Z-direction, and Y-direction by the operation of the X-direction linear motion mechanism 12a, the Z-direction linear motion mechanism 12b, and the Y-direction linear motion mechanism 12c, respectively.

The stage support unit 12f supports the stage 12h, on which the first grating 3 is placed, from below (Z2 direction) in Figure 3. The stage driver 12g is configured to reciprocate the stage 12h in the X direction. The bottom of the stage 12h is formed as a convex curved surface facing the stage support unit 12f, and is configured to rotate around the Y axis (Ry direction) as it moves back and forth in the X direction. The stage support driver 12e is configured to reciprocate the stage support unit 12f in the Y direction. The bottom of the stage support unit 12f is formed as a convex curved surface facing the linear motion mechanism connector 12d, and is configured to rotate around the X axis (Rx direction) as it moves back and forth in the Y direction. The linear motion mechanism connector 12d is attached to the Y-direction linear motion mechanism 12c so as to be rotatable around the Z axis (Rz direction). With the above configuration, the grating position adjustment mechanism 12 can cause the first grating 3 to perform stripe scanning in the Y direction by the operation of the Y-direction linear motion mechanism 12c.

(Configuration for generating X-ray phase contrast images)
Next, with reference to FIG. 4 , a configuration in which the image processing unit 81 (see FIG. 1 ) generates the X-ray phase contrast image 40 (see FIG. 1 ) will be described. The image processing unit 81 generates the X-ray phase contrast image 40 using intensity signal curves 20 and 21 acquired based on the intensity distribution of X-rays detected by the X-ray detector 2 (see FIG. 1 ). The X-ray phase contrast image 40 includes an absorption image, a differential phase image, and a dark-field image. The intensity signal curve 20 is a curve that indicates the distribution of X-ray intensity obtained by imaging with a subject 90 placed. The intensity signal curve 21 is a curve that indicates the distribution of X-ray intensity obtained by imaging with no subject 90 placed.

As shown in FIG. 4, an absorption image can be generated by the ratio of the average X-ray intensity Cs when imaging is performed with the subject 90 (see FIG. 1) in place to the average X-ray intensity Cr when imaging is performed without the subject 90 in place. A differential phase image can be generated by multiplying the phase difference Δφ between the intensity signal curve 20 obtained by imaging with the subject 90 in place and the intensity signal curve 21 obtained by imaging without the subject 90 in place by a number determined by a predetermined calculation. A dark-field image can be generated by the ratio of the visibility (Vr) when imaging is performed without the subject 90 in place to the visibility (Vs) when imaging is performed with the subject 90 in place. Vr can be calculated by the ratio of the amplitude Ar of the intensity signal curve 20 to the average intensity Cr. Vs can be calculated by the ratio of the amplitude As of the intensity signal curve 21 to the average intensity Cs.

(3D absorption image, differential phase image, and dark-field image)
In this embodiment, the X-ray phase contrast imaging system 100 (see FIG. 1 ) captures an image of the subject 90 while rotating it in a first rotation direction around a first axis 51 (see FIG. 2 ) using a first rotation mechanism 7 (see FIG. 1 ). Therefore, in this embodiment, the image processing unit 81 generates a three-dimensional absorption image 41, a three-dimensional differential phase image 42, and a three-dimensional dark-field image 43, as shown in FIG. 5 . That is, the X-ray phase contrast image 40 includes the three-dimensional absorption image 41, the three-dimensional differential phase image 42, and the three-dimensional dark-field image 43.

(Subject shape and fiber undulation)
Next, the shape of the subject 90 and the undulations of the fibers 90b contained in the subject 90 will be described with reference to FIGS. 6 and 7. FIG.

As shown in Figure 6, the subject 90 including fibers 90b (see Figure 7) has a plate-like shape. In the example shown in Figure 6, the subject 90 has a rectangular shape when viewed from the front. In this embodiment, the width direction of the subject 90 is defined as direction A. The height direction of the subject 90 is defined as direction B. The thickness direction of the subject 90 is defined as direction C. The height direction of the subject 90 is the direction in which the longest side of the subject 90 extends. The thickness direction of the subject 90 is the direction in which the shortest side of the subject 90 extends. The width direction of the subject 90 is a direction perpendicular to the height direction and thickness direction of the subject 90.

In this embodiment, for example, the subject 90 is made of planar sheet-like woven fiber fabrics oriented along the A direction, stacked in multiple layers along the C direction, and solidified with resin in order to improve the mechanical strength (tensile strength) in the A direction. Therefore, the fibers 90b (see Figure 7) are oriented along the A direction.

Here, the AC cross section of the subject 90 at a predetermined height is defined as the thickness direction cross section 90a of the subject 90.

The fibers 90b shown in Figure 7 represent fibers contained in the subject 90 that are undulating in the thickness direction of the subject 90. As shown in Figure 7, when the fibers 90b are undulating in the thickness direction cross section 90a, the tensile strength of the subject 90 in the width direction (direction A) is reduced. Note that in this specification, the undulation of the fibers 90b means that the fibers 90b undulate in a sine wave (S-shape) in the thickness direction of the subject 90, and that the fibers 90b are oriented in the thickness direction of the subject 90. Note that, for convenience, Figure 7 shows only one fiber 90b contained in the subject 90, but in reality, the subject 90 contains multiple fibers.

The dark-field image 43 shown in Figure 8 is an image of a thickness cross section 90a (see Figure 6) along the thickness direction of the subject 90 (see Figure 6). Note that the dark-field image 43 shown in Figure 8 is an enlarged dark-field image of a partial region of the dark-field image of the thickness cross section 90a.

If the fibers 90b are undulating in the thickness cross section 90a of the subject 90, a sine wave-like undulating white area will appear in the center of the subject 90 (see Figure 1), as shown in the area surrounded by rectangle 60 in the dark field image 43a. In this case, the mechanical strength (tensile strength in the A direction) of the subject 90 in the AB plane will be reduced.

Therefore, in this embodiment, the X-ray phase imaging system 100 (see Figure 1) is configured to extract fibers 90b oriented in the thickness direction of the subject 90 from the fibers contained in the subject 90.

(filter processing)
Specifically, the filter processing unit 82 (see FIG. 1 ) performs a filter process on the dark-field image 43 to extract fibers 90b oriented in the thickness direction of the subject 90 from among the fibers contained in the subject 90. Specifically, the filter processing unit 82 performs a filter process on the dark-field image 43 that captures a cross section selected by the user. Therefore, the user can extract fibers 90b in the desired cross section by selecting an image of the desired cross section. In this embodiment, an example is shown in which the user selects the dark-field image 43 that captures a thickness direction cross section 90a.

As shown in FIG. 9, the filter processing unit 82 is configured to perform filtering using a filter that extracts linear portions 44 (see FIG. 10) extending along a predetermined direction included in the subject 90 on a predetermined cross section of the dark-field image 43 (see FIG. 8), at multiple angles where the filter angle is different on the predetermined cross section. In this embodiment, the filter processing unit 82 is configured to extract linear portions 44 on a thickness cross section 90a (see FIG. 6) along the thickness direction of the subject 90 as the predetermined cross section. Specifically, the filter processing unit 82 is configured to perform filtering on multiple angles where the filter angle is different on the thickness cross section 90a within a predetermined angle range including the thickness direction of the subject 90. The filter angle is a parameter for determining the linear portions 44 to be extracted by the Gabor filter. In the example shown in FIG. 9, the filter angle is illustrated by the straight line portion 31 shown in the rectangle 30. In this embodiment, when the straight portion 31 is vertically oriented, it is set to 0 (zero) degrees, a counterclockwise direction is set to a positive rotation angle, and a clockwise direction is set to a negative rotation angle.

In this embodiment, the filter processing unit 82 is configured to perform filtering using, for example, a Gabor filter. A Gabor filter is a filter that extracts linear portions of an image that are oriented along the angle of the filter.

Graph 61 shown in Figure 9 is a graph showing the change in pixel value at a specified pixel when filter processing is performed on the dark-field image 43 (see Figure 8). In graph 61, the horizontal axis represents the filter angle and the vertical axis represents the pixel value.

In the example shown in Figure 9, pixel values were obtained when the filter angle was changed to -67.5 degrees, -45 degrees, -22.5 degrees, 0 degrees, 22.5 degrees, 45 degrees, 67.5 degrees, and 90 degrees. The first plot 62a in the graph 61 shows pixel values when the filter angle is -67.5 degrees. The second plot 62b shows pixel values when the filter angle is -45 degrees. The third plot 62c shows pixel values when the filter angle is -22.5 degrees. The fourth plot 62d shows pixel values when the filter angle is 0 degrees. The fifth plot 62e shows pixel values when the filter angle is 22.5 degrees. The sixth plot 62f shows pixel values when the filter angle is 45 degrees. The seventh plot 62g shows pixel values when the filter angle is 67.5 degrees. An eighth plot 62h shows pixel values when the filter angle is 90 degrees.

As shown in Figure 9, when the filter angle is changed, the pixel value changes depending on the direction of the fibers 90b (see Figure 7) of the subject 90. Specifically, the pixel value increases as the difference between the direction in which the fibers 90b of the subject 90 are oriented and the filter angle decreases. In the example shown in Figure 9, the pixel value is greatest when the filter angle is around -67.5 degrees.

The curve 63 shown in graph 61 is a curve obtained by fitting the first plot 62a to the eighth plot 62h with a sine function. The maximum value of the curve 63 shown in graph 61 is the direction (angle) of the linear portion 44 included in the subject 90 at that pixel. Therefore, the angle of the linear portion 44 can be obtained based on the curve 63 obtained by fitting. The filter processing unit 82 performs a similar filter process on each pixel of the dark-field image 43 (see Figure 8) to obtain the direction (angle) of the linear portion 44 included in the subject 90.

(Linear part image)
10 , in this embodiment, the filtering processing unit 82 (see FIG. 1 ) performs filtering on the dark-field image 43 at different filter angles to acquire multiple linear segments 44. Specifically, the filtering processing is performed multiple times on one dark-field image 43 at different filter angles to acquire multiple linear segments 44.

The first linear portion 44a is a linear portion 44 obtained by filtering the dark-field image 43 with a filter having an angle of -45 degrees. In other words, the first linear portion 44a is the portion of the linear portion 44 appearing in the dark-field image 43 that extends in the -45-degree direction.

The second linear portion 44b is a linear portion 44 obtained by filtering the dark-field image 43 with a filter having an angle of -22.5 degrees. In other words, the second linear portion 44b is the portion of the linear portion 44 appearing in the dark-field image 43 that extends in the -22.5-degree direction.

The third linear portion 44c is a linear portion 44 obtained by filtering the dark-field image 43 with a filter having an angle of 0 degrees. In other words, the third linear portion 44c is the portion of the linear portion 44 appearing in the dark-field image 43 that extends along the 0-degree direction.

In the example shown in Figure 10, for convenience, the linear portions 44 (first linear portion 44a to third linear portion 44c) are shown when the filter angles are -45 degrees, -22.5 degrees, and 0 degrees. In reality, the filter processing unit 82 performs filtering using filters with angles varying within a predetermined angle range, with 0 degrees as the center. For example, the filter processing unit 82 applies filters with angles of -45 degrees, -22.5 degrees, 0 degrees, 22.5 degrees, and 45 degrees to the dark-field image 43 to obtain the linear portions 44.

As shown in FIG. 10, the linear portion image generation unit 83 (see FIG. 1) is configured to generate a linear portion image 45 based on multiple linear portions 44 corresponding to fibers 90b (see FIG. 7) extracted by the filter processing unit 82. Specifically, the linear portion image generation unit 83 is configured to generate the linear portion image 45 by integrating the multiple linear portions 44 extracted by the filter processing unit 82. Note that in this embodiment, the linear portion image generation unit 83 is configured to perform the integration process by taking the highest pixel value among pixels at corresponding positions of the multiple linear portions 44 as the pixel value of the linear portion image 45. The linear portion image generation unit 83 generates the linear portion image 45 by performing the same process on all pixels of the linear portion 44.

(Weighting according to angle)
Here, when the above-described integration process is performed, the highest pixel value among the multiple linear portions 44 is set as the pixel value of the linear portion image 45, and therefore, information about the angle of the linear portion 44 is lost in the linear portion image 45. Therefore, even if a user checks the linear portion image 45, it is difficult to easily identify at a glance the portion of the subject 90 (see FIG. 1 ) in the AB plane where the mechanical strength is reduced. Therefore, in this embodiment, the linear portion image generation unit 83 is configured to weight the linear portions 44 so that the weight in the thickness direction of the subject 90 is maximized. Specifically, the linear portion image generation unit 83 is configured to weight the signal values (pixel values) of the linear portions 44 obtained by processing using filters with different angles according to the angle, and to weight the signal values (pixel values) so that the weight in the thickness direction of the subject 90 is maximized. In this embodiment, the linear portion image generation unit 83 weights the signal values of the multiple linear portions 44 by a cosine value corresponding to the angle, in order to maximize the weight in the thickness direction of the subject 90. Then, the linear portion image generation unit 83 generates a linear portion image 45 by performing an integration process on the multiple linear portions after weighting by the cosine value corresponding to the angle. As a result, the fibers 90b oriented in the thickness direction of the subject 90 are emphasized in the linear portion image 45. In other words, the linear portion image 45 is an image in which the fibers 90b oriented in the thickness direction of the subject 90 are emphasized.

(Multiple dark field images)
The dark-field image 43 (see FIG. 5) captured by the X-ray phase imaging system 100 (see FIG. 1) according to this embodiment is an image of fibers 90b (see FIG. 7) that extend in a direction intersecting the direction in which the plurality of gratings extend, among the fibers contained in the subject 90 (see FIG. 1). Therefore, depending on the orientation of the subject 90, some fibers may not be imaged in the dark-field image 43.

Therefore, in this embodiment, the image processing unit 81 (see Figure 1) is configured to generate multiple dark field images 43 obtained by changing the orientation of the subject 90 relative to the multiple gratings in a first rotation direction around the first axis 51 (see Figure 2) using the second rotation mechanism 9 (see Figure 1).

The example shown in Figure 11 shows the first dark-field image 43b to the third dark-field image 43d, generated by capturing images of the subject 90 at angles of 0 degrees, 45 degrees, and 90 degrees. The angle of the subject 90 refers to the relative angle of the subject 90 with respect to the lattice direction of the multiple lattices. In this embodiment, the angle of the subject 90 is determined by taking the Z1 direction as the reference (0 degrees), with a counterclockwise direction being a positive rotation angle, and a clockwise direction being a negative rotation angle. For convenience, the example shown in Figure 11 illustrates the second dark-field image 43c and the third dark-field image 43d rotated so that their orientations are aligned with the orientation of the first dark-field image 43b. For convenience, the example shown in Figure 11 illustrates examples in which the angle of the subject 90 is changed to 0 degrees, 45 degrees, and 90 degrees. However, if you want to check the distribution of fibers 90b (see Figure 7) of subject 90 in detail, it is preferable to change the angle of subject 90 to 0 degrees, 22.5 degrees, 45 degrees, 67.5 degrees, 90 degrees, -67.5 degrees, -45 degrees, and -22.5 degrees and take images.

The first dark-field image 43b is the dark-field image 43 when the angle of the subject 90 is 0 degrees. The second dark-field image 43c is the dark-field image 43 when the angle of the subject 90 is 45 degrees. The third dark-field image 43d is the dark-field image 43 when the angle of the subject 90 is 90 degrees.

As shown in Figure 11, different fibers are imaged in each dark field image 43 depending on the angle of the subject 90.

(Synthetic extracted image)
Therefore, in this embodiment, as shown in Fig. 12, the filter processing unit 82 (see Fig. 1) is configured to perform filtering using a Gabor filter on each of the multiple dark-field images 43 (see Fig. 11). The filter processing unit 82 performs filtering on each of the first to third dark-field images 43b to 43d at different filter angles and weights the images with cosine values corresponding to the angles, thereby obtaining first to third linear partial images 45a to 45c. Note that, for convenience, the example shown in Fig. 12 illustrates the second linear partial image 45b and the third linear partial image 45c rotated so that their orientations are aligned with the orientation of the first linear partial image 45a.

The first linear segment image 45a is a linear segment image 45 obtained by performing filter processing on the first dark-field image 43b. The second linear segment image 45b is a linear segment image 45 obtained by performing filter processing on the second dark-field image 43c. The third linear segment image 45c is a linear segment image 45 obtained by performing filter processing on the third dark-field image 43d.

In this embodiment, as shown in FIG. 12, the linear portion image generation unit 83 (see FIG. 1) is configured to generate a composite extracted image 46 by combining a plurality of linear portion images 45 generated based on a plurality of linear portions 44 obtained by the filter processing unit 82 (see FIG. 1) performing filtering using a filter on each of a plurality of dark-field images 43. In this embodiment, the linear portion image generation unit 83 is configured to generate a composite extracted image 46 by accumulating a plurality of linear portion images 45.

(First Projected Image and Second Projected Image)
Here, the dark-field image 43 (see FIG. 8) is a cross-sectional image of a thickness direction cross section 90a (see FIG. 6) of the subject 90 (see FIG. 1). Therefore, when the thickness of the subject 90 is small, it is difficult to grasp at a glance the state of the fibers 90b (see FIG. 7) extending in the thickness direction of the subject 90.

In this embodiment, as shown in FIG. 13, the projection image generation unit 84 (see FIG. 1) is configured to generate a first projection image 47 by projecting the dark-field image 43 in a direction along the thickness direction (direction C) of the subject 90. The first projection image 47 is an image that represents the distribution of the linear portions 44 in a direction along the thickness direction of the subject 90. The projection image generation unit 84 is configured to generate the first projection image 47 by projecting the linear portion image 45 in the thickness direction (direction C) of the subject 90 and in the in-plane direction (direction A) of the subject 90.

(Vector average projection image)
The first projection image 47 shown in FIG. 13 is a vector average projection image 47a obtained by averaging vectors based on the angles of linear portions 44 (see FIG. 10) extending in the thickness direction of the subject 90 (see FIG. 1) and the pixel values of the composite extraction image 46 (see FIG. 12) and projecting them in the C direction. The vector average projection image 47a is an image in which the linear portions 44 included in the subject 90 (see FIG. 1) are displayed in different ways depending on the angle, as shown in legend 70. The legend 70 indicates that the color gradually changes from red, purple, blue, and light blue within the angle range of 0 to 90 degrees. Furthermore, the color gradually changes from light blue, green, yellow, and red within the angle range of 90 to 180 degrees.

The vector average projection image 47a shown in Figure 13 is an image that is red overall, but includes green linear portions 44 in region 64. Therefore, it can be seen that region 64 contains linear portions 44 that are oriented in the thickness direction (direction C) of the subject 90.

Therefore, by checking the vector average projection image 47a, the user can easily understand the distribution (position and angle) of fibers 90b contained in the subject 90 in a direction along the thickness direction of the subject 90 when viewing the subject 90 from the X-ray source 1.

(maximum intensity projection image)
The first projection image 47 shown in FIG. 14 is a maximum intensity projection image 47b obtained by projecting the maximum pixel values of the composite extraction image 46 (see FIG. 12) in the C direction. As shown in legend 71, the orientation of the linear portions 44 (see FIG. 10) increases as the color of the maximum intensity projection image 47b approaches white, and decreases as the color of the maximum intensity projection image 47b approaches black. In this embodiment, the orientation of the linear portions 44 refers to whether or not they are oriented in the thickness direction of the subject 90. That is, the more the linear portions 44 are oriented in the thickness direction of the subject 90, the greater the orientation of the linear portions 44. Furthermore, the more the linear portions 44 are oriented in a direction perpendicular to the thickness direction of the subject 90, the less the orientation of the linear portions 44.

In the maximum intensity projection image 47b shown in Figure 14, region 65 contains white linear portions 44. Therefore, it can be seen that region 65 contains linear portions 44 oriented in the thickness direction (direction C) of subject 90.

Therefore, by checking the maximum intensity projection image 47b, the user can easily identify the fibers 90b oriented in the thickness direction of the subject 90.

(Second projected image)
In this embodiment, as shown in Figure 15, the linear portion image generation unit 83 (see Figure 1) is configured to extract a linear portion 44 (see Figure 10) in the in-plane direction of the subject 90 (see Figure 1) of the three-dimensional dark field image 43 (see Figure 5), and generate a two-dimensional second projection image 48 projected in the in-plane direction of the subject 90.

The second projection image 48 shown in Figure 15 is an image obtained by projecting in the B direction the vector average based on the angle of the linear portion 44 in a plane (in the AB plane) perpendicular to the thickness direction (C direction) of the subject 90 and the pixel values of a composite extracted image generated based on multiple linear portion images after filtering a dark-field image 43 that visualizes a thickness direction cross section 90a of the subject 90. The second projection image 48 is an image in which the linear portion 44 included in the subject 90 (see Figure 1) is displayed in different ways depending on the angle, as shown in legend 70. Legend 70 indicates that the color gradually changes from red, purple, blue, and light blue within the angle range of 0 to 90 degrees. Additionally, the color gradually changes from light blue, green, yellow, and red within the angle range of 90 to 180 degrees.

The second projection image 48 shown in Figure 15 is an image that is red overall, but region 66 includes blue linear portions 44. Therefore, it can be seen that region 66 contains linear portions 44 that are oriented in a direction perpendicular to the thickness direction of subject 90 (direction B).

Therefore, by checking the second projection image 48, the user can easily understand the distribution (position and angle) of fibers 90b within the AB plane of the subject 90, among the fibers contained in the subject 90, when the subject 90 is viewed from the X-ray source 1.

(Display of dark-field image, first projection image, and second projection image)
As shown in FIG. 16 , the display unit 10 is configured to display at least one of an absorption image 41 (see FIG. 5 ), a differential phase image 42 (see FIG. 5 ), and a dark-field image 43, a first projection image 47 (see FIG. 13 ), and a second projection image 48. In this embodiment, the display unit 10 is configured to display the dark-field image 43, the first projection image 47, and the second projection image 48 side by side. In the example shown in FIG. 16 , the display unit 10 displays a vector average projection image 47 a and a maximum intensity projection image 47 b as the first projection image 47. The display unit 10 is configured to display the dark-field image 43, the first projection image 47 (the vector average projection image 47 a and the maximum intensity projection image 47 b), and the second projection image 48 under the control of the control unit 80 (see FIG. 1 ).

(Projected image display processing)
Next, referring to Figure 17, we will explain the process by which the X-ray phase imaging system 100 (see Figure 1) according to this embodiment displays the dark-field image 43 (see Figure 16), the vector average projection image 47a (see Figure 16), the maximum intensity projection image 47b (see Figure 16), and the second projection image 48 (see Figure 16) on the display unit 10 (see Figure 16).

In step 101, the control unit 80 (see Figure 1) controls the X-ray source 1 (see Figure 1) and the first rotation mechanism 7 (see Figure 1) to image the subject 90 (see Figure 1) and the imaging system 6, which includes the X-ray source 1 that irradiates X-rays, the X-ray detector 2 that detects the X-rays irradiated from the X-ray source 1, and multiple gratings arranged between the X-ray source 1 and the X-ray detector 2 (see Figure 1), at multiple imaging angles while rotating them relatively in a rotational direction around a direction perpendicular to the X-ray irradiation axis 50 (see Figure 1).

In step 102, the image processing unit 81 (see Figure 1) generates a three-dimensional X-ray phase contrast image 40 (see Figure 1) including a three-dimensional dark-field image 43 (see Figure 4) based on the intensity distribution of X-rays detected by the X-ray detector 2 at multiple imaging angles.

In step 103, the filter processing unit 82 (see Figure 1) performs filtering using a filter that extracts linear portions 44 extending along a predetermined direction contained in the subject 90 for a predetermined cross section (thickness cross section 90a (see Figure 6)) of the dark field image 43, at multiple angles where the filter angle in the predetermined cross section is different.

In step 104, the linear portion image generation unit 83 (see Figure 1) generates a linear portion image 45 (see Figure 10) based on the extracted multiple linear portions 44 (see Figure 10) corresponding to the fibers 90b.

In step 105, the control unit 80 determines whether or not images have been captured at all of the predetermined angles of the subject 90 relative to the grid. If images have not been captured at all of the predetermined angles, the process proceeds to step 106. If images have been captured at all of the predetermined angles, the process proceeds to step 107.

In step 106, the control unit 80 rotates the subject 90 by controlling the second rotation mechanism 9 (see Figure 1). At this time, the control unit 80 rotates the subject 90 by a predetermined angle. In this embodiment, the control unit 80 rotates the subject 90 by 22.5 degrees. Then, the process proceeds to step 101.

Also, if processing proceeds from step 105 to step 107, in step 107, the linear portion image generation unit 83 (see Figure 1) combines multiple linear portion images 45 (see Figure 12) to generate a composite extracted image 46 (see Figure 12).

In step 108, the projection image generation unit 84 (see Figure 1) generates a first projection image 47 (see Figure 13). In this embodiment, the projection image generation unit 84 generates a vector average projection image 47a (see Figure 13) and a maximum value projection image 47b (see Figure 14).

In step 109, the projection image generation unit 84 generates a second projection image 48 (see Figure 15).

In step 110, the control unit 80 controls the display unit 10 to display the first projection image 47 (vector average projection image 47a and maximum intensity projection image 47b), the second projection image 48, and the dark-field image 43. The processing then ends.

Note that either the processing of step 108 or the processing of step 109 may be performed first. Furthermore, the processing of step 103 and the processing of step 104 may be performed together after the processing of step 105. Furthermore, imaging at all angles in step 106 may be performed sequentially for each angle around the first axis 51 in step 101.

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

In this embodiment, as described above, the X-ray phase imaging system 100 is an X-ray phase imaging system for extracting fibers contained in a subject 90, and includes an imaging system 6 including an X-ray source 1 that irradiates X-rays, an X-ray detector 2 that detects the X-rays irradiated from the X-ray source 1, and a plurality of gratings arranged between the X-ray source 1 and the X-ray detector 2; a first rotation mechanism 7 that rotates the subject 90 and the imaging system 6 relatively in a rotational direction about a direction perpendicular to the X-ray irradiation axis 50; and an X-ray detection system 6 that performs imaging at a plurality of imaging angles while rotating the subject 90 and the imaging system 6 relatively by the first rotation mechanism 7. The apparatus includes an image processing unit 81 that generates a three-dimensional X-ray phase contrast image 40 including a three-dimensional dark-field image 43 based on the intensity distribution of X-rays detected by the detector 2, a filter processing unit 82 that performs filtering using a filter to extract linear portions 44 extending along a predetermined direction included in the subject 90 on a predetermined cross section of the dark-field image 43, for a plurality of angles where the filter angle is different on the predetermined cross section, and a linear portion image generating unit 83 that generates a linear portion image 45 based on the plurality of linear portions 44 corresponding to fibers 90b extracted by the filter processing unit 82.

This allows the user to grasp the distribution of fibers 90b in a specified cross-section of the subject 90 by viewing the linear portion image 45, which is an image of the linear portions 44 corresponding to fibers 90b in the specified cross-section of the subject 90. Therefore, the user can grasp the locations of reduced mechanical strength in the fiber-containing subject 90 within a plane perpendicular to the specified cross-section. As a result, by checking the linear portion image 45 in the specified cross-section of the subject 90, the user can easily grasp the locations of reduced mechanical strength in the fiber-containing subject 90 within the desired plane.

In addition, in this embodiment, as described above, the X-ray phase imaging method is an X-ray phase imaging method for extracting fibers contained in the subject 90, and includes the steps of: imaging the subject 90 at multiple imaging angles while rotating an imaging system 6 including an X-ray source 1 that irradiates X-rays, an X-ray detector 2 that detects X-rays irradiated from the X-ray source 1, and multiple gratings arranged between the X-ray source 1 and the X-ray detector 2 relative to each other in a rotational direction perpendicular to the X-ray irradiation axis 50; generating a three-dimensional X-ray phase contrast image 40 including a three-dimensional dark-field image 43 based on the intensity distribution of the X-rays detected by the X-ray detector 2 at the multiple imaging angles; performing filtering on a predetermined cross section of the dark-field image 43 using a filter that extracts linear portions 44 extending along a predetermined direction contained in the subject 90, for multiple angles with different filter angles in the predetermined cross section; and generating a linear portion image 45 based on the extracted linear portions 44 corresponding to the fibers 90b.

This makes it possible to provide an X-ray phase imaging method that, similar to the above-mentioned X-ray phase imaging system 100, allows the user to easily identify the locations where the mechanical strength of the subject 90, including fibers, is reduced within the plane desired by the user.

In addition, in the above embodiment, the following additional effects are obtained by configuring as follows:

In other words, in this embodiment, as described above, the subject 90 containing fibers has a plate-like shape, and the filter processing unit 82 is configured to extract linear portions 44 in a thickness direction cross section 90a along the thickness direction of the subject 90 as a predetermined cross section. Here, the mechanical strength of the subject 90 in the in-plane direction is reduced in locations where fibers 90b oriented in the thickness direction of the subject 90 are distributed. Therefore, by configuring as described above, it is possible to extract fibers 90b oriented in the thickness direction of the subject 90 from among the fibers contained in the subject 90. As a result, the user can grasp the distribution of fibers 90b oriented in the thickness direction of the subject 90, and therefore the user can grasp locations where the mechanical strength of the subject 90 in the in-plane direction is reduced.

In addition, in this embodiment, as described above, the filter processing unit 82 is configured to perform filter processing at multiple angles with different filter angles within a predetermined angular range including the thickness direction of the subject 90 in the thickness direction cross section 90a. This makes it possible to extract fibers 90b oriented within a predetermined angular range including the thickness direction of the subject 90. As a result, it is possible to easily extract positions where the mechanical strength of the subject 90, including the fibers 90b, is reduced in the in-plane direction.

In addition, in this embodiment, as described above, the linear portion image generation unit 83 is configured to weight the linear portions 44 so that the weight in the thickness direction of the subject 90 is greatest. This allows the weighting of positions where the mechanical strength in the in-plane direction of the subject 90 is reduced to be maximized. As a result, the user can more easily grasp the positions where the mechanical strength in the in-plane direction of the subject 90, including the fibers 90b, is reduced.

In addition, in this embodiment, as described above, the linear portion image generation unit 83 is configured to weight the signal values of the linear portions 44 obtained by processing using filters of different angles according to the angle, and to weight the angle in the thickness direction of the subject 90 so that the weighting is greatest. This makes it easy to increase the weighting of signal values at positions in the linear portion image 45 where fibers 90b oriented in the thickness direction of the subject 90 are distributed. As a result, the signal values (pixel values) at positions in the linear portion image 45 where fibers 90b oriented in the thickness direction of the subject 90 are distributed are large, allowing the user to easily identify positions in the linear portion image 45 where the mechanical strength of the subject 90 in the in-plane direction is reduced.

Furthermore, in this embodiment, as described above, the linear portion image generation unit 83 is configured to generate a linear portion image 45 by integrating multiple linear portions 44 extracted by the filter processing unit 82. This makes it possible to generate a linear portion image 45 that includes linear portions 44 in various directions, unlike a configuration in which a linear portion image 45 is generated based on a single linear portion 44. As a result, by checking the linear portion image 45, the user can grasp in detail the locations where the mechanical strength of the subject 90 in the in-plane direction is reduced.

In addition, this embodiment further includes a projection image generation unit 84 that generates a two-dimensional first projection image 47 by projecting the linear partial image 45 in the thickness direction of the subject 90, as described above. Here, the linear partial image 45 is an image of the subject 90 viewed from the front (thickness direction of the subject 90). Therefore, if the thickness of the subject 90 is small, it is difficult to grasp in detail the direction and angle of extension of the fibers 90b in the direction along the thickness direction of the subject 90. On the other hand, since the first projection image 47 is an image obtained by projecting the linear partial image 45 in the thickness direction of the subject 90, it is easy to grasp the direction and angle of extension of the fibers 90b in the direction along the thickness direction of the subject 90, even if the thickness of the subject 90 is small. Therefore, as described above, by generating a two-dimensional first projection image 47 in which the linear partial image 45 is projected in the thickness direction of the subject 90, the user can easily grasp the details of the direction and angle in which the fiber 90b extends in the direction along the thickness direction of the subject 90 by checking the first projection image 47.

Furthermore, in this embodiment, as described above, the first projection image 47 is an image that represents the distribution of linear portions 44 in the thickness direction of the subject 90, and the projection image generation unit 84 is configured to generate the first projection image 47 by projecting the linear portion image 45 in the thickness direction of the subject 90 and in the in-plane direction of the subject 90. This allows the user to easily confirm the distribution of linear portions 44 in the thickness direction of the subject 90 in the first projection image 47. As a result, the user can easily grasp the distribution of fibers 90b in the thickness direction of the subject 90 in the first projection image 47.

Furthermore, as described above, this embodiment further includes a second rotation mechanism 9 that rotates the subject 90 and the multiple gratings relative to each other in a rotational direction around the X-ray irradiation axis 50. The image processing unit 81 is configured to generate multiple dark-field images 43 acquired by changing the orientation of the subject 90 relative to the multiple gratings using the second rotation mechanism 9. The filter processing unit 82 is configured to perform filtering using a filter on each of the multiple dark-field images 43. Here, in the dark-field image 43, fibers 90b of the subject 90 that extend in a direction parallel to the multiple gratings are imaged. Therefore, depending on the relative angle between the subject 90 and the multiple gratings, some fibers may not be imaged. Therefore, by configuring as described above, it is possible to extract fibers contained in the subject 90 regardless of the direction in which the fibers extend, based on the multiple dark-field images 43 acquired by changing the relative angle between the subject 90 and the multiple gratings using the second rotation mechanism 9. As a result, it is possible to extract fibers oriented in various directions contained in the subject 90, thereby accurately identifying locations where the mechanical strength of the subject 90 is reduced.

Furthermore, in this embodiment, as described above, the linear portion image generation unit 83 is configured to generate a composite extracted image 46 by combining a plurality of linear portion images 45 generated based on a plurality of linear portions 44 obtained by the filter processing unit 82 performing filtering using a filter on each of a plurality of dark-field images 43. As a result, the composite extracted image 46 is generated based on a plurality of linear portion images 45 that image fibers oriented in various directions contained in the subject 90, and therefore it is possible to generate a composite extracted image 46 that images fibers oriented in various directions.

In addition, in this embodiment, as described above, the linear portion image generation unit 83 is configured to extract linear portions 44 in the in-plane direction of the subject 90 from the three-dimensional dark-field image 43 and generate a two-dimensional second projection image 48 projected in the in-plane direction of the subject 90, and further includes a display unit 10 that displays the first projection image 47 and the second projection image 48. This allows the user to confirm the distribution of fibers 90b oriented in the thickness direction of the subject 90 using the first projection image 47, and to confirm the distribution of fibers in the in-plane direction of the subject 90 using the second projection image 48. As a result, the user can grasp the three-dimensional distribution of fibers contained in the subject 90, and can therefore grasp three-dimensionally the locations where the mechanical strength of the subject 90 is reduced.

In this embodiment, as described above, the X-ray phase contrast image 40 further includes a three-dimensional absorption image 41 and a three-dimensional phase differential image 42. The display unit 10 is configured to display at least one of the absorption image 41, the phase differential image 42, and the dark-field image 43, as well as the first projection image 47 and the second projection image 48. This allows the user to compare the absorption image 41, the phase differential image 42, and the dark-field image 43 with the first projection image 47 and the second projection image 48. Therefore, the user can confirm the distribution of fibers in the subject 90 using the first projection image 47 and the second projection image 48, and can also confirm the external shape of the subject 90 using the absorption image 41, the phase differential image 42, and the dark-field image 43. This improves user convenience (usability).

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

For example, in the above embodiment, an example of a configuration in which the X-ray phase imaging system 100 generates an X-ray phase contrast image 40, a linear partial image 45, a composite extracted image 46, a first projection image 47, and a second projection image 48 was shown, but the present invention is not limited to this. The X-ray phase imaging system 100 only needs to generate at least the X-ray phase contrast image 40 and the linear partial image 45.

While the above embodiment illustrates an example of a configuration in which the first projected image 47 and the second projected image 48, which are projected from the linear partial image 45, are displayed on the display unit 10, the present invention is not limited to this. For example, as shown in FIG. 18, the display unit 10 may be configured to display a fiber direction-enhanced image 49 that emphasizes the fibers 90c in the dark-field image 43. As shown in legend 72, the fiber direction-enhanced image 49 is an image that emphasizes the fibers 90c in accordance with the angle of the fibers 90c in the dark-field image 43 based on the linear partial image 45. Note that, similar to legend 70 (see FIG. 13) in the above embodiment, legend 72 gradually changes color from red, purple, blue, and light blue over the angle range of 0 to 90 degrees. Furthermore, the color gradually changes from light blue, green, yellow, and red over the angle range of 90 to 180 degrees.

The fibers 90c contained in the fiber direction-enhanced image 49 are mostly displayed in red, while the fibers 90b contained in region 67 are displayed in green and light blue. In other words, the fibers 90c contained in region 67 are oriented in the thickness direction (direction C) of the subject 90. By displaying the fiber direction-enhanced image 49 on the display unit 10, the user can easily grasp the distribution (position and angle) of the fibers 90c contained in the subject 90 that are oriented in the thickness direction of the subject 90.

In addition, in the above embodiment, an example was shown in which the subject 90 has a plate-like shape and the filter processing unit 82 performs filter processing on the thickness direction cross section 90a of the subject 90, but the present invention is not limited to this. The subject 90 may have a shape other than a plate-like shape. Furthermore, the filter processing unit 82 may perform filter processing on a cross section other than the thickness direction cross section 90a of the subject 90.

In addition, in the above embodiment, an example of a configuration was shown in which the linear portion image generation unit 83 weights the linear portion 44 so that the weight in the thickness direction of the subject 90 is greatest, but the present invention is not limited to this. The linear portion image generation unit 83 does not have to weight the linear portion 44.

In addition, in the above embodiment, an example of a configuration was shown in which the linear portion image generation unit 83 performs an accumulation process in which the highest pixel value among corresponding pixels of multiple linear portions 44 is set as the pixel value of the linear portion image 45, but the present invention is not limited to this. For example, the linear portion image generation unit 83 may be configured to generate the linear portion image 45 by adding the pixel values of corresponding pixels of multiple linear portions 44. Furthermore, the linear portion image generation unit 83 may be configured to generate the linear portion image 45 by averaging the pixel values of corresponding pixels of multiple linear portions 44.

In addition, while the above embodiment shows an example of a configuration in which the X-ray phase imaging system 100 includes a projection image generation unit 84, the present invention is not limited to this. For example, the X-ray phase imaging system 100 does not have to include a projection image generation unit 84. If the X-ray phase imaging system 100 does not include a projection image generation unit 84, for example, the control unit 80 may display either the linear partial image 45, the composite extracted image 46, or the fiber direction emphasized image 49 shown in FIG. 18 on the display unit 10 together with the dark field image 43.

In addition, in the above embodiment, an example of a configuration in which the projection image generation unit 84 generates both the vector average projection image 47a and the maximum intensity projection image 47b as the first projection image 47 was described, but the present invention is not limited to this. For example, the projection image generation unit 84 may be configured to generate either the vector average projection image 47a or the maximum intensity projection image 47b.

In addition, in the above embodiment, an example of a configuration in which the control unit 80 displays both the vector average projection image 47a and the maximum intensity projection image 47b on the display unit 10 as the first projection image 47 was shown, but the present invention is not limited to this. For example, the control unit 80 may be configured to display either the vector average projection image 47a or the maximum intensity projection image 47b on the display unit 10. Furthermore, the control unit 80 may be configured to display either the vector average projection image 47a or the maximum intensity projection image 47b on the display unit 10 based on a user selection.

In addition, in the above embodiment, an example of a configuration in which the control unit 80 displays the dark-field image 43, the first projected image 47, and the second projected image 48 on the display unit 10 was shown, but the present invention is not limited to this. For example, the control unit 80 may be configured to display at least the dark-field image 43 and the first projected image 47 on the display unit 10, and not to display the second projected image 48 on the display unit 10.

In addition, in the above embodiment, an example of a configuration in which the projection image generation unit 84 generates the second projection image 48 was shown, but the present invention is not limited to this. For example, the projection image generation unit 84 does not have to generate the second projection image 48.

Furthermore, in the above embodiment, an example of a configuration in which the X-ray phase imaging system 100 includes a second rotation mechanism 9 has been described, but the present invention is not limited to this. For example, the X-ray phase imaging system 100 does not have to include the second rotation mechanism 9. However, if the X-ray phase imaging system 100 does not include the second rotation mechanism 9, depending on the angle between the subject 90 and the multiple gratings, there is a possibility that fibers will not be imaged in the dark-field image 43. Therefore, it is preferable that the X-ray phase imaging system 100 include the second rotation mechanism 9.

In addition, in the above embodiment, an example of a configuration was shown in which the linear portion image generation unit 83 generates a composite extracted image 46 by combining multiple linear portion images 45, but the present invention is not limited to this. For example, the linear portion image generation unit 83 does not have to generate the composite extracted image 46. In this case, for example, the control unit 80 may be configured to display multiple linear portion images 45 together with the dark-field image 43 on the display unit 10.

In addition, in the above embodiment, an example of a configuration in which the control unit 80 displays the dark-field image 43 of the X-ray phase contrast image 40 on the display unit 10 was shown, but the present invention is not limited to this. For example, the control unit 80 may be configured to display any combination of the absorption image 41, the differential phase image 42, and the dark-field image 43 of the X-ray phase contrast image 40.

In addition, in the above embodiment, the filter processing unit 82 applies filters at angles of -45 degrees, -22.5 degrees, 0 degrees, 22.5 degrees, and 45 degrees to the dark-field image 43 to obtain the linear portion 44. While an example configuration has been shown, the present invention is not limited to this. The filter angle used when performing filter processing by the filter processing unit 82 can be set arbitrarily. Furthermore, the number of filter angles used when performing filter processing by the filter processing unit 82 can be set arbitrarily.

In addition, in the above embodiment, an example of a configuration in which the control unit 80 controls the second rotation mechanism 9 to change the angle of the subject 90 to 0 degrees, 45 degrees, and 90 degrees and capture an image was shown, but the present invention is not limited to this. The angle of the subject 90 relative to the multiple grids set by the control unit 80 can be set arbitrarily. Furthermore, the number of angles of the subject 90 relative to the multiple grids set by the control unit 80 can be set arbitrarily.

In addition, in the above embodiment, an example of a configuration in which the first rotation mechanism 7 rotates the subject 90, thereby rotating the subject 90 and the imaging system 6 relative to each other, was shown, but the present invention is not limited to this. For example, the first rotation mechanism 7 may be configured to rotate the imaging system 6, thereby rotating the subject 90 and the imaging system 6 relative to each other. However, if the first rotation mechanism 7 is configured to rotate the imaging system 6, the first rotation mechanism 7 will become larger. Therefore, it is preferable that the first rotation mechanism 7 be configured to rotate the subject 90.

In the above embodiment, as shown in Figure 2, an example of a configuration in which the second rotation mechanism 9 includes a subject placement unit 9a, a drive unit 9b, a drive force transmission member 9c, and a support member 9d is shown, but the present invention is not limited to this. The configuration of the second rotation mechanism 9 is not important as long as it can rotate the subject 90 in the second rotation direction around the second axis 52.

In addition, in the above embodiment, an example of a configuration in which the second rotation mechanism 9 rotates the subject 90, thereby rotating the subject 90 and multiple gratings relative to each other, was shown, but the present invention is not limited to this. For example, the second rotation mechanism 9 may be configured to rotate multiple gratings, thereby rotating the subject 90 and multiple gratings relative to each other. In this case, the second rotation mechanism 9 may be configured to rotate multiple gratings using a single rotation mechanism. Furthermore, the second rotation mechanism 9 may be configured to rotate a single grating using a single rotation mechanism. In this case, the second rotation mechanism 9 may be provided for each grating.

In addition, in the above embodiment, an example of a configuration in which the filter processing unit 82 uses a Gabor filter is shown, but the present invention is not limited to this. The filter processing unit 82 may be configured to perform filter processing using a filter other than a Gabor filter. For example, the filter processing unit 82 may be configured to perform filter processing to obtain a profile of the pixel values of each pixel along each of the A direction and B direction of the dark-field image 43 and to obtain the linear portion 44.

In addition, in the above embodiment, an example of a configuration in which the X-ray phase imaging system 100 images CFRP as the subject 90 was shown, but the present invention is not limited to this. For example, the X-ray phase imaging system 100 may be configured to image GFRP (glass fiber reinforced plastic) as the subject. Any subject may be imaged as long as it is a fiber composite material.

In addition, in the above embodiment, an example was shown in which the grating position adjustment mechanism 12 is configured to be able to move the first grating 3 in the X direction, Y direction, Z direction, rotational direction Rz, rotational direction Rx, and rotational direction Ry, but the present invention is not limited to this. In the present invention, the grating position adjustment mechanism 12 may be configured to be able to move only one or more of the X direction, Y direction, Z direction, rotational direction Rz, rotational direction Rx, and rotational direction Ry. Furthermore, the grating position adjustment mechanism 12 may be configured to be able to move the second grating 4 or the third grating 5. Note that when fringe scanning is performed, the grating position adjustment mechanism 12 needs to be configured to be able to move the grating in the direction in which fringe scanning is performed.

In addition, in the above embodiment, an example was shown in which the multiple gratings were configured to include a third grating 5 to increase the coherence of the X-rays irradiated from the X-ray source 1, but the present invention is not limited to this. If the coherence of the X-rays irradiated from the X-ray source 1 is high, the configuration may not include the third grating 5.

In addition, in the above embodiment, an example was shown in which the first grating 3 was a phase grating to form a self-image due to the Talbot effect, but the present invention is not limited to this. In the present invention, the self-image only needs to be a striped pattern, so an absorption grating may be used instead of a phase grating. When an absorption grating is used, optical conditions such as distance create a region where a striped pattern simply occurs (non-interferometer) and a region where a self-image due to the Talbot effect occurs (interferometer).

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

(Item 1)
An X-ray phase imaging system for extracting fibers contained in a subject, comprising:
an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects the X-rays irradiated from the X-ray source, and a plurality of gratings arranged between the X-ray source and the X-ray detector;
a first rotation mechanism that rotates the subject and the imaging system relative to each other in a rotation direction about a direction perpendicular to an irradiation axis of X-rays;
an image processing unit that generates a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the intensity distribution of X-rays detected by the X-ray detector by capturing images at a plurality of imaging angles while rotating the subject and the imaging system relative to each other using the first rotation mechanism;
a filter processing unit that performs filtering using a filter that extracts linear portions extending along a predetermined direction included in the subject on a predetermined cross section of the dark-field image, at a plurality of angles where the angle of the filter on the predetermined cross section is different;
and a linear portion image generating unit that generates a linear portion image based on the plurality of linear portions corresponding to the fibers extracted by the filtering processing unit.

(Item 2)
the subject including the fiber has a plate-like shape,
2. The X-ray phase imaging system according to claim 1, wherein the filter processing unit is configured to extract the linear portion in a thickness direction cross section along a thickness direction of the subject as the predetermined cross section.

(Item 3)
3. The X-ray phase imaging system according to item 2, wherein the filter processing unit is configured to perform the filter processing for a plurality of angles obtained by varying the angle of the filter within a predetermined angle range including the thickness direction of the subject in the thickness direction cross section.

(Item 4)
4. The X-ray phase imaging system according to claim 2, wherein the linear portion image generating unit is configured to weight the linear portion so that the weight in the thickness direction of the subject is greatest.

(Item 5)
Item 5. The X-ray phase imaging system according to item 4, wherein the linear portion image generating unit is configured to weight the signal values of the linear portion obtained by processing using the filters of different angles according to the angle, and to weight the angle in the thickness direction of the subject so that it is weighted most.

(Item 6)
6. The X-ray phase imaging system according to any one of items 2 to 5, wherein the linear portion image generating unit is configured to generate the linear portion image by integrating the plurality of linear portions extracted by the filter processing unit.

(Item 7)
7. The X-ray phase imaging system according to claim 6, further comprising a projection image generating unit that generates a two-dimensional first projection image by projecting the linear partial image in the thickness direction of the subject.

(Item 8)
the first projection image is an image representing a distribution of the linear portions in a direction along a thickness direction of the subject,
8. The X-ray phase imaging system according to claim 7, wherein the projection image generating unit is configured to generate the first projection image by projecting the linear partial image in a thickness direction of the subject and in an in-plane direction of the subject.

(Item 9)
a second rotation mechanism that rotates the object and the plurality of gratings relatively in a rotation direction around an irradiation axis of X-rays;
the image processing unit is configured to generate the dark-field images acquired by changing an orientation of the subject with respect to the gratings by the second rotation mechanism,
9. The X-ray phase imaging system according to any one of items 2 to 8, wherein the filter processing unit is configured to perform the filter processing using the filter on each of the plurality of dark-field images.

(Item 10)
Item 10. The X-ray phase imaging system according to Item 9, wherein the linear portion image generation unit is configured to generate a composite extracted image by combining the plurality of linear portion images generated based on the plurality of linear portions obtained by the filtering unit performing the filtering process using the filter on each of the plurality of dark-field images.

(Item 11)
the linear portion image generation unit is configured to extract the linear portion in an in-plane direction of the subject from the three-dimensional dark-field image, and generate a two-dimensional second projected image projected in the in-plane direction of the subject;
8. The X-ray phase imaging system according to claim 7, further comprising a display unit that displays the first projection image and the second projection image.

(Item 12)
the X-ray phase contrast image further includes a three-dimensional absorption image and a three-dimensional phase differential image;
Item 12. The X-ray phase imaging system according to item 11, wherein the display unit is configured to display at least one of the absorption image, the differential phase image, and the dark-field image, the first projection image, and the second projection image.

(Item 13)
An X-ray phase imaging method for extracting fibers contained in a subject, comprising:
imaging the subject at a plurality of imaging angles while rotating an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects the X-rays irradiated from the X-ray source, and a plurality of gratings disposed between the X-ray source and the X-ray detector relative to one another in a rotational direction about a direction orthogonal to an X-ray irradiation axis;
generating a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the intensity distribution of X-rays detected by the X-ray detector at a plurality of imaging angles;
performing a filtering process using a filter that extracts linear portions extending along a predetermined direction included in the subject on a predetermined cross section of the dark-field image at a plurality of angles where the angle of the filter on the predetermined cross section is different;
and generating a linear portion image based on the extracted linear portions corresponding to the fibers.

REFERENCE SIGNS LIST 1 X-ray source 2 X-ray detector 6 Imaging system 7 First rotation mechanism 9 Second rotation mechanism 10 Display unit 40 X-ray phase contrast image 41 Absorption image 42 Differential phase image 43 Dark field image 44 Linear portion 45 Linear portion image 46 Synthesized and extracted image 47 First projection image 48 Second projection image 50 X-ray irradiation axis 81 Image processing unit 82 Filter processing unit 83 Linear portion image generation unit 84 Projection image generation unit 90 Object 90a Thickness direction cross section 90b Fiber (fiber oriented in the thickness direction of the object)
100 X-ray imaging device

Claims (13)

An X-ray phase imaging system for extracting fibers contained in a subject, comprising:
an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects the X-rays irradiated from the X-ray source, and a plurality of gratings arranged between the X-ray source and the X-ray detector;
a first rotation mechanism that rotates the subject and the imaging system relative to each other in a rotation direction about a direction perpendicular to an irradiation axis of X-rays;
an image processing unit that generates a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the intensity distribution of X-rays detected by the X-ray detector by capturing images at a plurality of imaging angles while rotating the subject and the imaging system relative to each other using the first rotation mechanism;
a filter processing unit that performs filtering using a filter that extracts linear portions extending along a predetermined direction included in the subject on a predetermined cross section of the dark-field image, at a plurality of angles where the angle of the filter on the predetermined cross section is different;
and a linear portion image generating unit that generates a linear portion image based on the plurality of linear portions corresponding to the fibers extracted by the filtering processing unit. the subject including the fiber has a plate-like shape,
The X-ray phase imaging system according to claim 1 , wherein the filter processing unit is configured to extract the linear portion in a thickness direction cross section along a thickness direction of the subject as the predetermined cross section. The X-ray phase imaging system described in claim 2, wherein the filter processing unit is configured to perform the filter processing at multiple angles with different filter angles within a predetermined angle range including the thickness direction of the subject in the thickness direction cross section. The X-ray phase imaging system described in claim 3, wherein the linear portion image generation unit is configured to weight the linear portion so that the weight in the thickness direction of the subject is greatest. The X-ray phase imaging system described in claim 4, wherein the linear portion image generation unit is configured to weight the signal values of the linear portion obtained by processing using filters of different angles according to the angle, and to weight the angle in the thickness direction of the subject so that it is weighted most heavily. The X-ray phase imaging system described in claim 2, wherein the linear portion image generation unit is configured to generate the linear portion image by accumulating the multiple linear portions extracted by the filter processing unit. The X-ray phase imaging system of claim 6 further comprises a projection image generation unit that generates a two-dimensional first projection image by projecting the linear partial image in the thickness direction of the subject. the first projection image is an image representing a distribution of the linear portions in a direction along a thickness direction of the subject,
8. The X-ray phase imaging system of claim 7, wherein the projection image generating unit is configured to generate the first projection image by projecting the linear partial image in a thickness direction of the subject and in an in-plane direction of the subject. a second rotation mechanism that rotates the object and the plurality of gratings relatively in a rotation direction around an irradiation axis of X-rays;
the image processing unit is configured to generate the dark-field images acquired by changing an orientation of the subject with respect to the gratings by the second rotation mechanism,
The X-ray phase imaging system according to claim 2 , wherein the filtering unit is configured to perform the filtering process using the filter on each of the plurality of dark-field images. The X-ray phase imaging system described in claim 9, wherein the linear portion image generation unit is configured to generate a composite extracted image by combining the multiple linear portion images generated based on the multiple linear portions obtained by the filter processing unit performing the filtering process using the filter on each of the multiple dark-field images. the linear portion image generation unit is configured to extract the linear portion in an in-plane direction of the subject from the three-dimensional dark-field image, and generate a two-dimensional second projected image projected in the in-plane direction of the subject;
The X-ray phase imaging system according to claim 7 , further comprising a display unit that displays the first projection image and the second projection image. the X-ray phase contrast image further includes a three-dimensional absorption image and a three-dimensional phase differential image;
12. The X-ray phase imaging system according to claim 11, wherein the display unit is configured to display at least one of the absorption image, the differential phase image, and the dark-field image, the first projection image, and the second projection image. An X-ray phase imaging method for extracting fibers contained in a subject, comprising:
imaging the subject at a plurality of imaging angles while rotating an imaging system including an X-ray source that irradiates X-rays, an X-ray detector that detects the X-rays irradiated from the X-ray source, and a plurality of gratings disposed between the X-ray source and the X-ray detector relative to one another in a rotational direction about a direction orthogonal to an X-ray irradiation axis;
generating a three-dimensional X-ray phase contrast image including a three-dimensional dark-field image based on the intensity distribution of X-rays detected by the X-ray detector at a plurality of imaging angles;
performing a filtering process using a filter that extracts linear portions extending along a predetermined direction included in the subject on a predetermined cross section of the dark-field image at a plurality of angles where the angle of the filter on the predetermined cross section is different;
and generating a linear portion image based on the extracted linear portions corresponding to the fibers.