JP2011153869A - Light source grating, imaging apparatus for x-ray phase contrast image equipped with the source grating, and x-ray computed tomography system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source grating which enables a period to be changed in response to an imaging condition without the need of preparing two or more light source gratings beforehand. <P>SOLUTION: This light source grating is disposed between an electromagnetic wave source and imaging system, and is used when an electromagnetic wave emitted from the electromagnetic wave source is spatially split into two or more beams. The light source grating is configured by laminating a first substrate equipped with two or more openings and a second substrate equipped with two or more openings, and has an opening array by a two dimensional array formed of the two or more openings in the overlap between the first substrate and second substrate. The light source grating is configured to change the period of the opening array by the two dimensional array from a first period to a second period different from the first period by changing the relative position between the first substrate and second substrate in the planar direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source grating (shielding grating) used for spatial modulation of electromagnetic wave intensity, an X-ray phase contrast image imaging apparatus including the light source grating, and an X-ray computed tomography system.

Electromagnetic waves are used for imaging various subjects due to the characteristics resulting from the length of the wavelength.
A kind of X-rays of electromagnetic waves has high substance permeability and enables observation of the internal structure of a subject, and is therefore used for transmission imaging devices in industrial and medical fields.
In recent years, an imaging method using X-ray refraction and interference has also been developed. In these X-ray imaging methods, a technique for spatially dividing one X-ray into a plurality of beams is used.
For example, in Talbot-Lau interferometry, which is a method for imaging phase changes from interference fringes disclosed in Patent Document 1, X-rays are emitted by an X-ray light source grating disposed between an X-ray light source and an imaging system. Spatial coherence is ensured by using a plurality of narrow beams.
In addition, in the refraction method that increases the contrast of a captured image by utilizing the refraction of X-rays by the subject, the refraction phenomenon can be detected as the movement of the beam on the detector by making the X-rays into a plurality of beams. I am doing so.

WO2006 / 131235 specification

When a light source grating is used to capture a phase contrast image, in order to spatially divide one electromagnetic wave into a plurality of beams, it is common to provide a light source grating having a plurality of apertures between the electromagnetic wave source and the imaging system. It is.
At that time, the beam interval, so-called period, is determined according to the imaging conditions.
The light source grating is often a rigid body. In particular, in the X-ray region having a high transmission power, it is necessary to make the light source grating with a heavy metal having a high shielding ability.
However, the period of the light source grating is required according to the imaging conditions as described above.
Therefore, in order to meet such imaging conditions, it is necessary to prepare a plurality of light source grids in advance. In the case where the light source grid is made of a rigid body such as a metal, it takes time and effort to prepare. Become high.

  In view of the above problems, the present invention eliminates the need to prepare a plurality of light source gratings in advance, and makes it possible to change the period according to imaging conditions, and an X-ray phase contrast including the light source grating. An object is to provide an image pickup apparatus and an X-ray computed tomography system.

The present invention provides a light source grating configured as follows, an X-ray phase contrast image imaging apparatus including the light source grating, and an X-ray computed tomography system.
The light source grating of the present invention is a light source grating provided between an electromagnetic wave source and an imaging system, and used when spatially dividing an electromagnetic wave irradiated from the electromagnetic wave source into a plurality of beams,
The light source grid is configured by laminating a first substrate having a plurality of openings and a second substrate having a plurality of openings, and the first substrate and the second substrate Having an aperture array by a two-dimensional array formed by the plurality of apertures in an overlap;
A second period in which the period of the aperture array by the two-dimensional array is different from the first period from the first period by changing a relative position in the surface direction between the first substrate and the second substrate. It is characterized in that it can be changed to a cycle.

  According to the present invention, it is not necessary to prepare a plurality of light source gratings in advance, and a light source grating whose period can be changed in accordance with imaging conditions, and imaging of an X-ray phase contrast image including the light source grating. An apparatus and an X-ray computed tomography system can be realized.

The figure explaining the structural example of the light source grating | lattice in Embodiment 1 of this invention. The figure explaining the structural example of the light source grating | lattice in Embodiment 1 of this invention. The figure explaining the structural example of the light source grating | lattice in Embodiment 2 of this invention. The figure explaining the structural example of the light source grating | lattice in Embodiment 2 of this invention. The figure explaining the structural example of the light source grating | lattice in the 1st modification of Embodiment 2 of this invention. The figure explaining the structural example of the light source grating | lattice in the 2nd modification of Embodiment 2 of this invention. FIG. 7A illustrates a configuration example of an X-ray phase contrast image imaging apparatus using Talbot-Lau interferometry according to the first embodiment of the present invention. FIG. 7B is a table of the coordinates of points that are the basis of the pattern of the light source grid in the first embodiment. FIG. 8A is a diagram for explaining a configuration example by an X-ray refraction method in Embodiment 2 of the present invention. FIG. 8B is a table of coordinates of points that are the basis of the pattern in the light source grid according to the second embodiment.

Next, a light source that is provided between the electromagnetic wave source and the imaging system in the embodiment of the present invention and is used when a phase contrast image is captured by spatially dividing the electromagnetic wave irradiated from the electromagnetic wave source into a plurality of beams. A configuration example of the lattice will be described.
[Embodiment 1]
In the first embodiment, a configuration example of a light source grating in which two substrate having a large number of stacked openings is relatively rotated in the plane direction and the relative position of these substrates is changed to change the aperture arrangement period will be described.
The reference serving as the center of relative rotation may also serve as the opening, or may have a reference point different from the opening.
First, using FIG. 1A and FIG. 1B, a configuration example of two substrates having a plurality of openings including one opening that also serves as a reference for rotation and forming a light source grid by stacking them. Will be described.
The light source grid of the present embodiment is configured by laminating a first substrate having a plurality of openings and a second substrate having a plurality of openings. These first substrate and second substrate It has an opening array by a two-dimensional array formed by the plurality of openings in the overlap with the substrate.
Specifically, FIG. 1A is a front view illustrating the configuration of the first substrate in the present embodiment. The first substrate has an opening 4 through which a desired electromagnetic wave is transmitted on a substrate constituted by a shielding member 2 suitable for the desired electromagnetic wave.
For example, a square array opening having a first period 12 (see FIG. 2A) realized by the light source grating 20 (see FIG. 7A), and
In a pattern in which the square array openings of the second period 14 are overlapped so that one reference opening in each square array overlaps and the axes of the square array are parallel, the corresponding openings are continuous. Connect with openings to make one opening.
One opening serving as a reference may be at any position in the square array.
For example, if the first period 12 is a micrometer and the second period 14 (see FIG. 2B) is b micrometers,
The coordinates (x1, y1) of the square array of the first period 12 are (a × n, a × m) with the one opening serving as the reference 1 as the origin, and the coordinates (x2, y2) of the square array of the second period 14 ) Can be expressed as (b × n, b × m).
Here, n and m are integers, and the coordinates of the same combination of n and m are corresponding coordinates.
Corresponding (x1, y1) and (x2, y2) are connected to form the opening 4 of the first substrate 6 which is the (n, m) th opening.
FIG. 1B is a front view for explaining the configuration of the second substrate in the present embodiment. Similar to the first substrate, the second substrate has an opening 4 through which electromagnetic waves are transmitted on a substrate constituted by the shielding member 2 suitable for desired electromagnetic waves.
For example, a square array opening having a first period 12 realized by the light source grating 20 (see FIG. 7A);
In a pattern in which the square array openings of the second period 14 are overlapped so that one axis serving as a reference in each square array serves as a reference 1 and the corresponding axis of each square array has a certain rotation angle θ16. , The corresponding openings are connected to form one continuous opening.
For example, the first period 12 is a micrometer, and the second period 14 is b micrometers.
As a result, the coordinates (x1, y1) of the square array of the first period 12 can be expressed as (a × n, a × m) with one aperture serving as the reference 1 as the origin, and the square array of the second period 14 The coordinates (x3, y3) can be expressed as (Rnm × cos (θ + θnm), Rnm × sin (θ + θnm)).
Here, θ is the rotation angle, n and m are integers, Rnm = b × (n × n + m × m) ^ (1/2), and θnm = arctan (m / n).
Corresponding (x1, y1) and (x3, y3) are connected to form the opening 4 of the second substrate 6.
When (x1, y1) and (x2, y2) are connected, or (x1, y1) and (x3, y3) are connected, a straight line or a curved line may be used.
The width of the opening 4 corresponds to the opening width desired to be obtained by the light source grid 20, and may be the width of the opening 4 that realizes a desired opening width. The same opening width may be sufficient over the whole opening part 4, and a different opening width may be sufficient. By changing the opening width, the opening width of the light source grating 20 can be changed simultaneously with the period.

Next, a light source grating configured by stacking two substrates will be described with reference to FIGS. 2 (a) and 2 (b).
FIG. 2A is a diagram for explaining a configuration in which the first substrate 6 and the second substrate 8 are stacked so that the square arrangement of the first period 12 overlaps.
As shown in FIG. 2A, the opening array 10 constituted by the openings of the first substrate 6 and the openings of the second substrate 8 is formed at a position corresponding to the square array of the first period 12. Is done.
Next, the second substrate is rotated around the reference 1 by the clockwise rotation angle θ16.
FIG. 2B is a diagram for explaining the configuration of the light source grid in which the second substrate is stacked with the first substrate by rotating the second substrate by the rotation angle θ.
As shown in FIG. 2B, the opening array 10 constituted by the openings of the first substrate 6 and the openings of the second substrate 8 is formed at a position corresponding to the square array of the second period 14. Is done.
That is, a light source grid having an aperture array 10 whose period is changed by changing the angle of the second substrate 8 with respect to the first substrate 6 is obtained.
The shape of the opening array 10 changes depending on the angle between the first substrate and the second substrate.
The opening 3 in the first period 12 and the opening 5 in the second period 14 may be connected by a continuous opening, or may be connected by a discontinuous opening.

FIG. 2C shows a modification of the second substrate. As shown in FIG. 2 (c), the individual shapes of the opening array 10 of the first period 12 and the opening array 10 of the second period 14 are made uniform when the light source grating is configured by making it non-continuous. Can be.
In the case of discontinuity, the opening portion 7 of the third period corresponding to the period between the first period 12 and the second period 14 is replaced with the opening part 3 of the first period 12 and the second period. And 14 openings 5.
Thereby, although it is a discrete period, the light source grating | lattice which has the aperture array 10 with a fixed shape can be comprised.
In the present embodiment, for example, a 3 × 3 square array of light source grids 20 is described. However, the number of arrays may be any number as long as the individual openings 4 do not overlap.
Further, the number of arrangements in the vertical direction and the horizontal direction are different, and for example, a 3 × 4 arrangement may be used.

[Embodiment 2]
In the second embodiment, a configuration example of a light source grating that can change the aperture arrangement period by relatively translating two substrates having a large number of stacked apertures will be described.
First, a configuration example of two substrates having a large number of openings to be stacked will be described with reference to FIGS. 3A and 3B.
FIG. 3A is a front view for explaining the configuration of the first substrate in the present embodiment. Similar to the first embodiment, the first substrate has an opening 4 through which a desired electromagnetic wave is transmitted on a substrate constituted by a shielding member 2 suitable for the desired electromagnetic wave.
For example, the square array opening of the first period 12 and the square array opening of the second period 14 realized by the light source grating 20 are arranged in such a manner that the respective axes of the square array are parallel to each other and one reference opening overlaps.
In a pattern that is overlapped by shifting by a distance d in one axis, for example, in the horizontal axis direction, corresponding openings are connected by continuous openings to form one opening.
For example, the first period 12 is a micrometer, and the second period 14 is b micrometers.
As a result, the coordinates (x1, y1) of the square array of the first period 12 are (a × n, a × m) with the one opening serving as a reference as the origin, and the coordinates (x2) of the square array of the second period 14 , Y2) is represented by (b × n + d, b × m).
Here, n and m are integers, and the coordinates of the same combination of n and m are corresponding coordinates.
Corresponding (x1, y1) and (x2, y2) are connected to form the opening 4 of the first substrate 6.

FIG. 3B is a front view illustrating the configuration of the second substrate in the present embodiment.
Similar to the first substrate, the second substrate has an opening 4 through which the desired electromagnetic wave is transmitted on the substrate constituted by the shielding member 2 suitable for the desired electromagnetic wave.
For example, the square array opening of the first period 12 and the square array opening of the second period 14 realized by the light source grating 20 are arranged in such a manner that the respective axes of the square array are parallel to each other and one reference opening overlaps.
In a pattern in which one axis, for example, the vertical axis (translation direction) is shifted and overlapped by a movement distance d, corresponding openings are connected by continuous openings to form one opening.
For example, the first period 12 is a micrometer, and the second period 14 is b micrometers.
Accordingly, the coordinates (x1, y1) of the square array in the first period 12 are (a × n, a × m) with the one opening serving as a reference as the origin, and the coordinates (x3) of the square array in the second period 14 , Y3) is represented by (b × n, b × m + d).
Corresponding (x1, y1) and (x3, y3) are connected to form an opening 4 of the first substrate 6.
When (x1, y1) and (x2, y2) are connected, or (x1, y1) and (x3, y3) are connected, a straight line or a curved line may be used.
The width of the opening 4 corresponds to the opening width desired to be obtained by the light source grid 20, and may be the width of the opening 4 that realizes a desired opening width. The same opening width may be sufficient over the whole opening part 4, and a different opening width may be sufficient.
By changing the opening width, the opening width of the light source grating 20 can be changed simultaneously with the period.

Next, a light source grid 20 configured by stacking two substrates in the present embodiment will be described with reference to FIGS. 4A and 4B.
FIG. 4A is a diagram for explaining a configuration of a light source grating in which the first substrate 6 and the second substrate 8 are stacked so that the square arrangements of the first period 12 overlap each other.
As shown in FIG. 4A, the opening array 10 constituted by the openings 4 of the first substrate 6 and the openings of the second substrate 8 is located at a position corresponding to the square array of the first period 12. It is formed.
Next, the second substrate is translated by a distance d in both the vertical and horizontal axes.
FIG. 4B is a diagram illustrating the configuration of the light source grid 20 in which the second substrate is translated by a distance d in the vertical and horizontal axis directions.
As shown in FIG. 4B, the opening array 10 constituted by the openings 4 of the first substrate 6 and the openings of the second substrate 8 is located at a position corresponding to the square array of the second period 14. It is formed.
That is, the light source grid 20 has the aperture array 10 whose period is changed by translating the position of the second substrate 8 relative to the first substrate 6. The stacking direction of the first substrate and the second substrate may be an angle at which the orthogonal axes of the square array overlap.

FIG. 5A and FIG. 5B respectively show modifications in the case where the first substrate and the second substrate are stacked in this embodiment.
For example, as shown in FIGS. 5A and 5B, the first substrate may be stacked at a position rotated by 180 degrees compared to the case of the second substrate 8.
As shown in FIG. 5 (a), the shape of the opening array 10 having the first period 12 is closer to a circle than the opening array 10 shown in FIG. 4 (a), and as shown in FIG. 5 (b). The shape of the opening array 10 having the second period 14 is closer to a circle than the opening array 10 in FIG.

FIG. 6A and FIG. 6B show modifications of the first substrate and the second substrate of this embodiment, respectively.
As shown in FIGS. 6A and 6B, the openings 4 of the first substrate and the second substrate may be independent for each period of the opening arrangement as in the first embodiment. Good.
By being independent, the uniformity of the shape of the opening array 10 at a position that is a period between the first period 12 and the second period 14 is improved.
Moreover, you may have the opening part 4 corresponded in the square arrangement | sequence of the other period between the 1st period 12 and the 2nd period 14.
In the present embodiment, for example, a 3 × 3 square array of light source grids 20 is described. However, the number of arrays may be any number as long as the individual openings 4 do not overlap.
Further, the number of arrangements in the vertical direction and the horizontal direction are different, and for example, a 3 × 4 arrangement may be used.

Examples of the present invention will be described below.
[Example 1]
In Example 1, an X-ray light source grating used for X-ray phase imaging will be described with reference to FIG.
After a resist coating is applied to the surface of a silicon wafer having a thickness of 200 μm by double-side polishing with a 4-inch diameter, the following different resist patterns are formed in two 10 mm square areas by photolithography.
FIG. 7B shows the coordinates of the point that is the basis of the resist pattern in this embodiment in units of μm under the conditions of the first period a = 24 μm, the second period b = 20 μm, and the rotation angle θ = 5 degrees. This is the value calculated in.
One of the resist patterns has a width of 5 μm connecting corresponding points excluding (n, m) = (0, 0) of coordinates (x1, y1) and (x2, y2) shown in FIG. Is a line.
The other is a line having a width of 5 μm connecting corresponding points excluding (n, m) = (0, 0) of coordinates (x1, y1) and (x3, y3) shown in FIG. These are both patterns that leave a resist.

Next, after anisotropic etching is performed on the silicon wafer to a depth of 40 μm by deep-RIE, the resist pattern is removed by an asher.
Next, a titanium-gold sputtered film is formed on the wafer to form a seed layer for electrolytic plating. Nippon Electroplating Engineers Co., Ltd., Temperex 209A is put in the electrolytic plating apparatus as a plating solution, and the plating solution is plated for 400 minutes under the conditions of a temperature of 60 ° C. and a current density of 0.2 A / dm 2.
The gold adhering to the substrate surface is removed by buffing using a diamond slurry.
Thereafter, a 10 mm square region is cut out by dicing. As a result, two substrates having an X-ray transmission region having an opening width of 5 μm are obtained.
Next, the position adjustment mechanism 42, for example, a high-precision stepping motor is mounted on the two substrates so that the point (n, m) = (0, 0) overlaps and the position corresponding to (x1, y1) overlaps. Attach them one by one to the stage. The position adjustment mechanism 42 may be a high-precision stepping motor, for example, a piezoelectric actuator, or a manual precision adjustment screw.
The mounted stage uses at least a stepping motor that rotates in the plane. The two substrates are arranged as close as possible so as not to physically interfere with each other.
One of the substrates is rotated by a stepping motor so that the X-ray transmission regions of the substrate overlap with each other about (n, m) = (0, 0).

Next, an X-ray phase contrast image capturing apparatus using the Talbot-Lau interferometry shown in FIG. 7A in the present embodiment, which is configured by arranging the X-ray light source grating 20 thus manufactured. An example of the configuration will be described.
As shown in FIG. 7A, a light source grating 20 is arranged downstream of the X-ray light source 18, and the subject 24, the X-ray phase grating 26, and the X-ray amplitude grating 28 are arranged downstream of the light source grating 20. The X-ray imaging device 30 is sequentially arranged.
A light source grating 20 having a period of 24 μm is arranged so that the opening of (x1, y1) overlaps the front surface of the X-ray light source 18 having an X-ray energy of 17.5 keV (0.71 angstrom).
When a π-modulated two-dimensional phase grating having a vertical / horizontal period of 8 μm is used as the phase grating 26, if the distance 32 between the light source grating 20 and the phase grating 26 is 677 mm, the Talbot distance is 135 mm away from the phase grating 26 due to Talbot-low interference. A Talbot image appears at 34.

A net-like amplitude grating 28 and an X-ray image sensor 30 having a vertical and horizontal period of 4 μm are arranged at the Talbot distance 34, and a moire image formed by the Talbot image and the amplitude grating 28 is imaged by the X-ray image sensor 30.
Phase information is obtained by extracting and integrating phase information from the obtained moire image using a Fourier transform method.
The distance 32 between the light source grating 20 and the phase grating 26 is adjusted according to the thickness of the subject 24 and the enlargement ratio to be imaged.
For example, when the distance 32 between the light source grating and the phase grating is shortened from 677 mm to 564 mm and the enlargement ratio is increased, the period of the light source grating is also changed from 24 μm to 20 μm in order to satisfy the Talbot-Low interference condition.
When the stepping motor is rotated 5 degrees around the reference point (n, m) = (0,0), the corresponding first substrate point (x2, y2) and second substrate point (x3, y3) And the period of the light source grating 20 is reduced from 24 μm to 20 μm.
As a result, a Talbot image of the subject whose Talbot distance 34 is enlarged to a position of 141 mm is formed by Talbot-low interference, and a phase image is obtained from moire fringes.

[Example 2]
In Example 2, an X-ray light source grating used for X-ray refraction imaging will be described with reference to FIG.
First, two substrates are manufactured by the same method as in Example 1.
FIG. 8B shows the coordinates of the point that is the basis of the resist pattern in this embodiment in units of μm under the conditions of the first period a = 20 μm, the second period b = 25 μm, and the moving distance d = 5 μm. It is a calculated value.
One of the resist patterns is a line having a width of 10 μm connecting points corresponding to coordinates (x1, y1) and (x2, y2) shown in FIG.
The other is a line having a width of 5 μm connecting corresponding points of coordinates (x1, y1) and (x3, y3) shown in FIG. 8B, and these are patterns that leave a resist. Similar to Example 1, etching and electrolytic plating were performed on a silicon wafer with a 200-μm thickness of double-sided polishing with a 4-inch diameter, and two substrates having an X-ray transmission region with an opening width of 10 μm square and 5 μm were obtained by dicing after buffing. obtain.

Next, the position adjustment mechanism 42, for example, a high-precision stepping motor is mounted on the two substrates so that the point (n, m) = (0, 0) overlaps and the position corresponding to (x1, y1) overlaps. Attach them one by one to the stage.
The position adjustment mechanism 42 may be a high-precision stepping motor, for example, a piezoelectric actuator, or a manual precision adjustment screw.
A stage equipped with a high-precision stepping motor that moves at least 5 μm in both vertical and horizontal axes is used. The two substrates are arranged as close as possible so as not to physically interfere with each other.
Either one of the substrates is translated by a stepping motor so that the X-ray transmission regions of the substrates overlap.
The X-ray light source grid 20 thus produced is adjusted so that the corresponding (x1, y1) coordinates overlap on the two substrates and the period of the opening is 20 μm, and the focal spot size is 10 μm. It is arranged 30 cm downstream of the light source 18.

Next, a configuration example of an imaging apparatus for an X-ray phase contrast image using the X-ray refraction method shown in FIG.
As shown in FIG. 8A, the subject 24 and the X-ray imaging element 30 are sequentially arranged downstream of the light source grid 20.
The subject 24 is disposed near the light source grid 20. In the X-ray imaging device 30, the size 38 of one pixel is 100 μm.
When the distance 40 between the light source grating 20 and the X-ray imaging grating 30 is 120 cm, X-rays transmitted through the light source grating 20 are arranged with spots having a diameter of 65 μm on the X-ray imaging element 30 with a period of 100 μm. When there is no refraction at the subject 24, the X-ray travels along a straight locus 36. On the other hand, when there is refraction at the subject 24, the X-ray trajectory is bent after passing through the subject, and the spot position on the X-ray image sensor 30 is shifted.
This deviation corresponds to the refractive index of the subject, and the refractive index distribution of the subject 24 is obtained as an image by analyzing the spot deviation.
When the refraction at the subject 24 is large, the X-ray trajectory 22 after refraction bends greatly, the positions of adjacent spots are switched, and an error occurs in the refraction information.
In such a case, by increasing the period of the light source grating 20 and shortening the distance 40 between the light source grating 20 and the X-ray image sensor 30, the deviation of the spot on the X-ray image sensor 30 can be suppressed even for X-rays having a large refraction angle. And reduce the spot diameter.
When the two substrates of the light source grating 20 are erected and moved by 5 μm in both lateral directions, the period becomes 20 μm to 25 μm.
By using the light source grid 20 and shortening the distance 40 of the X-ray image sensor 30 from 120 cm to 90 cm, the spot diameter can be reduced from 65 μm to 50 μm, and the displacement of the spot can be suppressed.
In addition, the present invention can constitute an X-ray computed tomography system by incorporating the X-ray phase contrast image imaging apparatus described in the first and second embodiments.

1: Reference 2: Shielding member 3: First period opening 4: Substrate opening 5: Second period opening 6: First substrate 8: Second substrate 10: Aperture array 12: First 1 period 14: second period

Claims (7)

A light source grid provided between an electromagnetic wave source and an imaging system and used when spatially dividing an electromagnetic wave irradiated from the electromagnetic wave source into a plurality of beams,
The light source grid is configured by laminating a first substrate having a plurality of openings and a second substrate having a plurality of openings, and the first substrate and the second substrate Having an aperture array by a two-dimensional array formed by the plurality of apertures in an overlap;
A second period in which the period of the aperture array by the two-dimensional array is different from the first period from the first period by changing a relative position in the surface direction between the first substrate and the second substrate. A light source grating characterized by being configured to be able to be changed in period.   In changing the period, the first substrate and the second substrate are rotated relative to each other in a plane direction around a reference point, and the first substrate and the second substrate The light source grating according to claim 1, wherein the light source grating is configured to be capable of changing a relative position. The first substrate has a square array of coordinates of the first period as (x1, y1) with one opening serving as a reference 1 in the first substrate as an origin, and the second substrate in the second substrate. When the coordinates of the square array of the period are (x2, y2),
A point (x1, y1) represented by (x1, y1) = (a × n, a × m) and a point (x2, y2) = (b × n, b × m) (n, m) -th opening connecting y2),
When the coordinates of the square array of the second period on the second substrate are (x3, y3),
The point (x1, y1) represented by (x1, y1) = (a × n, a × m) and (x3, y3) = (Rnm × cos (θ + θnm), Rnm × sin (θ + θnm)) Connecting the represented points (x3, y3),
The light source grating according to claim 1, further comprising an opening corresponding to an (n, m) -th opening in the first substrate.
However,
a: the first cycle b: the second cycle θ: the rotation angle n, m: integer Rnm: = b × (n × n + m × m) ^ (1/2)
θnm: = arctan (m / n)   In changing the period, the first substrate and the second substrate can be translated relative to each other in the surface direction, and the relative position between the first substrate and the second substrate can be changed. The light source grid according to claim 1, wherein the light source grid is configured. The first substrate has a square array of coordinates of the first period as (x1, y1) with one opening serving as a reference 1 in the first substrate as an origin, and the second substrate in the second substrate. When the coordinates (x2, y2) of a square array with a period of
A point (x1, y1) represented by (x1, y1) = (a × n, a × m) and a point (x2, y2) = (b × n + d, b × m) (n, m) -th opening connecting y2),
When the coordinates of the square array of the second period on the second substrate are (x3, y3),
The point (x1, y1) represented by (x1, y1) = (a × n, a × m) and the point (x3) represented by (x3, y3) = (b × n, b × m + d) , Y3), and the (n, m) th aperture is connected.
However,
a: the first period b: the second period n, m: an integer,
d: Travel distance in the translation direction   6. A light source grating according to claim 1, and a position adjusting mechanism for adjusting a position of the light source grating, wherein an X-ray phase grating, an X-ray amplitude grating, and An X-ray phase contrast image imaging apparatus, wherein an X-ray imaging element is disposed.   An X-ray computed tomography system comprising the X-ray phase contrast image capturing apparatus according to claim 6.

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