JP2012170645A - X-ray imaging apparatus, and x-ray imaging method - Google Patents

Abstract

An object of the present invention is to provide an X-ray imaging apparatus capable of acquiring the maximum ratio of phase information to absorption information in a subject when acquiring a phase image of the subject by phase imaging.
An X-ray imaging apparatus comprising: an X-ray source;
A splitting element disposed between the X-ray source and the subject, comprising a plurality of openings for splitting the divergent X-rays irradiated from the X-ray source into a plurality of X-rays;
A detector disposed downstream of the subject in the irradiation direction of the X-ray beam in order to detect an X-ray beam by the divergent X-ray transmitted through the subject and refracted;
An arithmetic processing means for arithmetically processing information on an intensity change of the X-ray beam detected by the detector,
When the distance between the X-ray source and the dividing element is L1, and the distance between the dividing element and the detector is L2, the value of L2 / L1 is in the range of more than 1.0 and less than 2.4. Has been.
[Selection] Figure 1

Description

  The present invention relates to an X-ray imaging apparatus and an X-ray imaging method using X-rays.

Nondestructive inspection methods using radiation are used in a wide range of fields from industrial use to medical use.
For example, X-rays are electromagnetic waves having a wavelength of about 1 pm to 10 nm, and the absorption contrast method using the difference in mass attenuation coefficient of each substance makes use of the high X-ray transmissivity, so that internal cracks in metallic materials, etc. It has been put to practical use in security fields such as inspection, inspection of foreign matters mixed in food and baggage inspection.
However, polymer material systems such as plastic and acrylic resin are difficult to detect and detect by the absorption contrast method because the difference in mass attenuation coefficient is small.

Phase imaging that detects X-ray phase changes by the subject is effective for subjects that are composed of light elements that do not easily form contrast due to radiation absorption or that have a low density difference interface. is there.
Such a method using phase imaging is likely to be applied to imaging of polymer materials and medical systems such as soft tissues.
In various X-ray phase imaging, Patent Document 1 and Patent Document 2 propose an X-ray imaging method using a refraction effect caused by a phase change caused by an X-ray detection object.
These methods are designed to irradiate a subject with X-rays spatially divided by X-ray optical means and to irradiate the two-dimensional detector with X-rays refracted by the subject.
According to such a method, the amount of refraction of the refracted X-ray can be obtained from the intensity distribution of the two-dimensional detector.

JP 2008-200388 A International Publication No. 95/05725 Pamphlet

By the way, not only the methods described in Patent Document 1 and Patent Document 2, but also when visualizing the refractive index of the subject, the absorption information is completely separated from the refraction information, and the phase image of the subject is obtained only from the refraction information. It is difficult.
In Patent Document 1 and Patent Document 2, an average refractive index of a specific space of a subject can be detected, but it is a precondition that absorption in the specific space is uniform.
However, when the refractive index in a specific space is not uniform, the absorptance is not necessarily uniform.
Therefore, when obtaining the amount of refraction of the subject from the positional deviation of the X-ray beam formed on the detector, the minute change amount of the X-ray beam refracted by the subject and the unevenness in the intensity of the X-ray attenuated by the subject. The amount of change due to cannot be separated.

  In view of the above problems, the present invention provides an X-ray imaging apparatus and an X-ray imaging method capable of acquiring the maximum ratio of phase information to absorption information in a subject when acquiring a phase image of the subject by phase imaging. With the goal.

The X-ray imaging apparatus of the present invention
An X-ray source;
A splitting element disposed between the X-ray source and the subject, comprising a plurality of openings for splitting the divergent X-rays irradiated from the X-ray source into a plurality of X-rays;
A detector disposed downstream of the subject in the irradiation direction of the X-ray beam in order to detect an X-ray beam by the divergent X-ray transmitted through the subject and refracted;
An arithmetic processing means for arithmetically processing information on an intensity change of the X-ray beam detected by the detector,
When the distance between the X-ray source and the dividing element is L1, and the distance between the dividing element and the detector is L2, the value of L2 / L1 is in the range of more than 1.0 and less than 2.4. It is characterized by being.
In the X-ray imaging method of the present invention, divergent X-rays irradiated from an X-ray source are divided into a plurality of X-rays by a dividing element, and an X-ray beam by the divided divergent X-rays is transmitted to a subject. An X-ray imaging method for detecting a change in the intensity of an X-ray beam generated by a detector using a detector,
The splitting element, the subject, and the detector are arranged in this order on the optical path in the irradiation direction of the divergent X-ray by the X-ray source,
By making the relationship between the distance between the X-ray source and the splitting element and the distance between the splitting element and the detector into the relationship of the distance where the X-ray beam does not overlap on the detector,
It is possible to obtain the maximum ratio of phase information to absorption information in the subject.

  According to the present invention, it is possible to realize an X-ray imaging apparatus and an X-ray imaging method capable of acquiring the maximum ratio of phase information to absorption information in a subject when acquiring a phase image of the subject by phase imaging. it can.

The schematic diagram explaining the structural example of the X-ray imaging device in embodiment of this invention. The schematic diagram of the X-ray beam formed on the detector in embodiment of this invention. The figure which shows the simulation result of the geometry in embodiment of this invention. FIG. 2 is a schematic diagram illustrating a configuration example of an X-ray imaging apparatus according to Embodiment 1 of the present invention. The schematic diagram of the X-ray beam formed on the detector in Example 1 of this invention. The figure which shows the simulation image of the acrylic resin in Example 1 of this invention. The figure which shows the simulation result of the acrylic resin in Example 1 of this invention. The figure which shows the simulation result of the geometry in Example 1 of this invention. The figure which shows the simulation result of the geometry in Example 1 of this invention. FIG. 6 is a schematic diagram illustrating a configuration example of an X-ray imaging apparatus according to Embodiment 2 of the present invention.

In the present invention, the X-ray source, the dividing element, the subject, and the detector are arranged in this order on the optical path in the radiation direction of the divergent X-ray from the X-ray source, and the distance between the X-ray source and the dividing element is L1. When the distance between the dividing element and the detector is L2,
By finding that the ratio of the phase information to the absorption information in the subject can be obtained to the maximum by making these L1 and L2 a distance relationship in which the X-ray beams do not overlap on the detector. It is.
Such a value of L2 / L1 can be obtained from the focal point size f of the X-ray source, the aperture width Ga of the dividing element, and the pixel size Ps of the detector. Details of these will be described in the following embodiments of the present invention. It will be clarified by explanation of
FIG. 1 shows an X image obtained from an X-ray phase change using an X-ray source for generating a spherical wave, a dividing element for spatially dividing the generated X-ray, and a two-dimensional X-ray detector in this embodiment. The figure explaining the structural example of a linear imaging device is shown.
As shown in FIG. 1, the X-ray imaging apparatus of this embodiment includes an X-ray source 101 that generates divergent X-rays 102 and irradiates a subject.
Then, the dividing element 103, the subject 104, and the detector 106 are arranged on the optical path in the irradiation direction of the divergent X-ray 102 by the X-ray source 101 in this order.
The dividing element 103 that spatially divides the divergent X-ray 102 forms an X-ray beam having a sheet shape or a dot shape. This is a medical X-ray apparatus, like a focusing grid used to remove scattered X-rays generated during imaging of a subject, and a foil 112 and X made of a light element that easily transmits X-rays. It is formed by alternately overlapping foils 113 made of heavy elements that shield the lines.
The foil 112 for transmitting X-rays is made of aluminum, paper, synthetic resin, or the like.
On the other hand, platinum, gold, lead, tantalum, tungsten, or the like is used for the foil 113 for shielding X-rays.
Further, by fixing the both ends of the foil 113 for shielding X-rays while maintaining a certain interval, the portion that transmits X-rays may be air, and in this case, the air is also referred to as foil.

The detector 106 is disposed downstream of the subject in the irradiation direction of the X-ray beam in order to detect the X-ray beam by the divergent X-ray that has been transmitted through the subject and refracted. The detector 106 includes a plurality of pixels 111 arranged two-dimensionally.
FIG. 2 is a view of a part of the detector 106 as seen from the Y direction in FIG.
Since the intensity of the X-ray beam 105 is obtained by integrating the number of X-ray photons incident on the pixel 111 area, the spatial resolution of the detector 106 is determined by the spatial size of the pixel 111.
As shown in FIG. 2, by irradiating the X-ray beam 105 transmitted through the subject 104 across a plurality of pixels 111, it is possible to obtain the amount of change in position relative to the reference X-ray beam 114 when there is no subject. It is.
In general, as the width of the X-ray beam 105 formed by the detector 106 becomes narrower, the intensity difference caused by the positional deviation of the X-ray beam 105 with respect to the X-ray intensity detected by each pixel 111 is relatively improved.
Therefore, the possibility that the intensity difference caused by the positional deviation of the X-ray beam 105 is buried in noise is reduced, and the amount of refraction of the subject 104 can be clearly obtained, so that the phase detection sensitivity is improved.
In the present embodiment, the X-ray beam 105 refracted while passing through the subject, the positional deviation amount dxp of the reference X-ray beam 114 on the detector 106 when there is no subject, and the X-ray beam 105 as the detector. The phase detection sensitivity is represented by dxp / Gd by using the width Gd formed on 106.
In FIG. 2, the X-ray beam 105 straddles two adjacent pixels 111, but the number of straddling pixels 111 may be essentially any number as long as it straddles two or more.

As shown in FIG. 2, the width Gd formed on the detector 106 by the X-ray beam 105 is such that the brightness of the divergent X-ray 102 generated from the X-ray source is constant, the aperture width of the dividing element 103 is Ga, and the subject 104. When there is not, it can represent with the following formula 1.

Gd = Ga × (L1 + L2) / L1 + f × L2 / L1 Formula 1

Further, the positional deviation amount dxp on the detector 106 of the X-ray beam 105 refracted while passing through the subject and the reference X-ray beam 114 when there is no subject can be expressed by the following equation (2).

dxp = L2 × tan (α) (2)

Here, α is an angle at which the X-ray beam 105 is refracted by the subject 104.
Since the intensity of the X-ray beam 105 attenuated during transmission through the subject 104 changes according to the shape of the subject 104, the center of gravity position of the intensity of the X-ray beam 105 and the reference X-ray beam 114 when there is no subject. Deviation occurs in the center of gravity position of the intensity.
The positional deviation dxa of the X-ray beam 105 caused by the absorption difference of the subject 104 depends only on the shape and thickness of the subject 104.
It is difficult to completely separate the positional deviation dxp of the X-ray beam 105 caused by refraction of the subject 104 and the positional deviation dxa of the X-ray beam caused by the absorption component.
However, since dxa does not depend on L2, it is possible to increase the ratio of the phase information to the absorption information by increasing L2 from Equation 2.
In general, since dxp is smaller than the size of the pixel 111 of the detector 106, it is important to increase L2 in order to detect dxp.

However, in the case of using divergent X-rays 102 generated from a finite focal size, if L2 is large, adjacent X-ray beams 105 overlap on the detector 106, so accurate position information of each X-ray beam 105 is obtained. It becomes difficult to obtain.
The condition that adjacent X-ray beams 105 do not overlap on the detector 106 is that when the number of pixels 111 necessary for detecting position information in one-dimensional direction of one X-ray beam 105 is n, the following Expression 3 Can be expressed as

Gd + dxp + dxa <n × Ps Equation 3

Substituting Equation 1 into Equation 3 yields Equation 4 below.

Ga × (L1 + L2) / L1 + f × L2 / L1 + dxp + dxa <n × Ps Equation 4

Further, when Formula 4 is bundled with L2 / L1, it can be expressed by the following Formula 5.

L2 / L1 + (dxp + dxa) / (Ga + f) <(n × Ps−Ga) / (Ga + f) Equation 5

Ga + f is around 100 μm, whereas dxp + dxa is about several microns at the maximum, so Ga + f >> dxp + dxa, and Equation 5 can be converted into Equation 6 below.

L2 / L1 <(n × Ps−Ga) / (Ga + f) (Formula 6)

FIG. 3 is a diagram in which the geometry L2 / L1 of the apparatus is plotted on the horizontal axis and the phase detection sensitivity dxp / Gd is plotted on the vertical axis from Formula 1, Formula 2, and Formula 6.
The thin line in FIG. 3 is the calculation result when f = 100 μm, Ps = 100 μm, Ga = 33 μm, and n = 2.
From Equation 6, when L2 / L1 = 1.25, the phase detection sensitivity dxp / Gd takes the maximum value, and when L2 / L1> 1.25, the adjacent X-ray beams 105 overlap on the detector 106. It becomes difficult to obtain accurate position information of the line beam 105.
Similarly, the thick lines in FIG. 3 are the calculation results when f = 50 μm, Ps = 100 μm, Ga = 33 μm, and n = 2.
From Equation 6, when L2 / L1 = 2.0, the phase detection sensitivity dxp / Gd takes the maximum value, and when L2 / L1> 2.0, adjacent X-ray beams 105 overlap on the detector 106.
Although not shown in FIG. 3, the focus size of the X-ray source 101 is 50 to 150 μm, the size of the pixel 111 is 50 to 100 μm, and the opening width of the dividing element 103 is 20 to 75 μm. As a result, an appropriate L2 / L1 range in which the ratio of the phase information to the absorption information can be maximized is greater than 1.0 and less than 2.4 (1.0 <L2 / L1 <2.4).
In consideration of X-ray luminance and phase detection sensitivity, the focal point size of the X-ray source is set to 80 to 100 μm, the pixel size is set to 50 to 150 μm, and the opening width of the dividing element is set to 20 to 50 μm. And when
L2 which is the distance between the dividing element and the detector is 1.1 to 1.5 times longer than L1 which is the distance between the X-ray source and the dividing element (1.1 <L2 / L1 < 1.5), it is possible to obtain the maximum ratio of the phase information to the absorption information.

The dividing element 103 of the present embodiment is specified based on one dimension, but may be two-dimensional.
When the dividing element 103 is two-dimensional, the angles at which the X-ray beam 105 is refracted by the subject 104 are independent in the x direction and the y direction.
When the pixels 111 of the detector 106 are two-dimensionally arranged, the amount of refraction in the y direction can be obtained by the same method as the method for detecting the amount of refraction in the x direction shown in FIG.

Examples of the present invention will be described below.
[Example 1]
In the first embodiment, a configuration example of an X-ray imaging apparatus to which the present invention is applied will be described with reference to FIG.
In FIG. 4, 101 is an X-ray source for generating divergent X-rays 102, 103 is a splitting element, 104 is a subject, and 106 is a two-dimensional detector.
Reference numerals 108, 109, and 110 denote an X-ray source 101, a splitting element 103, and a moving / rotating unit for the detector 106, respectively. 107 denotes an arithmetic unit that performs processing on information on the intensity change of the X-ray beam detected by the detector. Arithmetic processing means).
In this embodiment, as the X-ray source 101, a rotating counter cathode type X-ray generator of molybdenum, silver or tungsten target is used.
The distribution of luminance at the source of divergent X-rays 102 generated from the X-ray source 101 is assumed to be a normal distribution, and the focal spot size is the full width at half maximum of the normal distribution function. Divergent X-rays 102 generated from the X-ray source 101 are spatially divided by a dividing element 103 arranged at a position 100 cm away from the X-ray source 101.

The dividing element 103 alternately overlaps the foil 112 for transmitting X-rays and the foil 113 for shielding X-rays, and the focusing position is at a position 100 cm from the dividing element 103 in the X-ray source direction.
There are four types of division elements 103, D25, D33, D50, and D75. The film thickness (Ga) of the foil 112 for transmitting X-rays and the film thickness (Gb) of the foil 113 for shielding X-rays, respectively. ) Are different as shown in Table 1 below.
[Table 1]

The subject 104 is installed immediately after the dividing element 103, and the distance between the dividing element 103 and the detector 106 is set to 10 to 300 cm.
FIG. 5 is a view of a part of the detector 106 as seen from the Y direction in FIG.
As shown in FIG. 5, the position and the amount of refraction of the X-ray beam 105 on the detector 106 can be obtained by irradiating the X-ray beam 105 transmitted through the subject 104 across a plurality of pixels 111. is there.
The pixel size in this embodiment is 100 μm.
The X-ray detection intensities of the two pixels when the X-ray beam 105 transmitted through the subject is irradiated are I01 and I02, and the X of the two pixels irradiated with the reference X-ray beam 114 when there is no subject When the line detection intensity is I11 and I12,
An intensity change dI of the X-ray beam 105 with respect to the reference X-ray beam 114 that can be detected by the detector 106 is expressed by the following Expression 7.

dI = (I01−I02) / (I01 + I02) − (I11−I12) / (I11 + I12)...

FIG. 6 shows a simulation result obtained by mapping dI of Equation 7 of each X-ray beam 105 that has passed through a cylindrical acrylic resin under the conditions of L1 = 1 m, L2 = 1 m, and f = 100 μm by using the dividing element of D25. Show.
The X-ray source 101 of this simulation uses a normal distribution function having a monochromatic light of 17.5 keV (0.071 nm) and a focal size of 100 μm.
The MTF spread function of the detector 106 is a normal distribution function that becomes 0.1 at 10 lp / mm.
It does not include a noise system typified by Poisson noise caused by spatial fluctuation caused by the X-ray beam 105 randomly reaching the detector 106 and the pixel 111. In the calculation of FIG. 6A, the complex refractive index 1-δ-iβ was used as the parameter of the acrylic resin.
In the calculation of FIG. 6B, the real part of the complex refractive index 1-δ-iβ was used as the parameter of the acrylic resin.
In the calculation of FIG. 6C, the imaginary part of the complex refractive index 1-δ-iβ was used as the parameter of the acrylic resin.
From this, the differential image of FIG. 6A is the absorption component and phase component of acrylic resin, the differential image of FIG. 6B is the phase component of acrylic resin, and the differential image of FIG. Each of the resin absorption components is calculated.
That is, by comparing FIG. 6B and FIG. 6C, the ratio of the phase information to the absorption information included in FIG.

The line profiles of the broken line parts in FIG. 6B and FIG. 6C are indicated by broken lines in FIG.
Since the signal intensity of the differential phase image is about four times larger than the signal intensity of the differential absorption image based on the broken line profiles in FIGS. 7A and 7B, the phase component included in FIG. It can be seen that the percentage is about 80%.
In the same simulation, the distance between the X-ray source 101 and the dividing element 103 was changed to 100 cm and the distance between the dividing element 103 and the detector 106 was changed from 10 to 300 cm for each of the dividing elements 103 of D25, D33, D50, and D75. FIG. 8 shows a plot of the ratio of the phase components included in the differential image at that time.
8 to D25, L2 = 130 cm, D33 divider 103, L2 = 120 cm, D50 divider 103, L2 = 120 cm, and D75 divider 103, L2 = 100 cm. The maximum percentage is obtained.

The absorption component depends on the shape and thickness of the subject 104, whereas the phase component depends on the distance between the splitting element 103 and the detector 106 according to Equation 2.
Therefore, when the same subject 104 is imaged with the same dividing element 103, the value of L2 / L1 at which the ratio of the phase component included in the obtained differential image is maximized is constant regardless of the values of L1 and L2. .
In FIG. 9, the distance between the X-ray source 101 and the dividing element 103 is changed to 25 cm, 50 cm, and 100 cm, and the distance between the dividing element 103 and the detector 106 is changed to 10 to 300 cm using the dividing element D25. The figure which plotted the ratio of the phase component contained in the differential image of the acrylic resin at that time is shown.
Increasing the distance between the X-ray source 101 and the dividing element 103 increases the proportion of the phase component included in the differential image, but the value of L2 / L1 at which the phase component is maximized is always 1.3.
When the same calculation is performed for the D25 splitting element under the condition of f = 90 μm, the phase component becomes maximum L2 / L1 is always 1.4, and the phase component is maximum under the condition of f = 80 μm. The value of L2 / L1 is always 1.5.

The value of L2 / L1 that maximizes the phase component obtained in this simulation is about 10% smaller than the value of L2 / L1 that maximizes the phase component obtained by Equation 6.
This is because the approximation of Ga + f >> dxp + dxa is used in the process of deriving Equation 6, and the blur of the X-ray beam 105 due to the MTF of the detector 106 is not taken into consideration.
However, from FIG. 9, the ratio of the phase component to the respective absorption components of L2 / L1 where the phase component obtained in this simulation is maximized and L2 / L1 where the phase component obtained by Equation 6 is maximized is
Since the difference is only about 1 to 2%, the subject 104 may be imaged using L2 / L1 obtained by Expression 6.

The actual geometry of the X-ray imaging apparatus that maximizes the ratio of the phase component included in the differential image using the X-ray source 101 having a focal size of 100 μm and the dividing element 103 having D = 25 from FIG.
L2 = 0.4 m when L1 = 0.3 m,
L2 = 1.3 m when L1 = 1 m,
L2 = 2m when L1 = 1.55m,
L2 = 2.6 m when L1 = 2.0 m,
Etc. are considered as options.
Similarly, from FIG. 8, in the dividing element 103 with D = 50,
L2 = 0.36m when L1 = 0.3m,
When L1 = 1.0m, L2 = 1.2m,
L2 = 2m when L1 = 1.67m,
L2 = 2.4m when L1 = 2m,
Etc. are considered as options.
From FIG. 9, when L2 / L1 is constant, the ratio of the phase component included in the differential image increases as L1 and L2 become longer. However, L1 + L2 directly affects the size of the apparatus, and the X-ray beam 105 There remains a problem that the X-ray intensity per book decreases.

[Example 2]
In the second embodiment, a method of simultaneously measuring two-dimensional X-ray position change detection in addition to the one-dimensional X-ray position change detection described in the first embodiment will be described.
A configuration example of the X-ray imaging apparatus will be described with reference to FIG. In FIG. 10A, 101 is an X-ray source that generates divergent X-rays, 103 and 201 are one-dimensional division elements, 104 is a subject, and 106 is a two-dimensional detector.
Reference numerals 108, 109, 117, and 202 denote moving / rotating units for the X-ray source 101, the first dividing element 103, the second dividing element 201, and the detector 106, respectively.

The X-ray generated from the X-ray source 101 is a portion where the foil 112 through which the X-rays of the first dividing element 103 transmit and the foil 112 through which the X-rays of the second dividing element 201 transmit spatially overlap. Can only penetrate. For this reason, the X-ray beam 105 divided by the dividing elements 103 and 201 forms a two-dimensional dot array.
Since the two-dimensional information in the general detector 106 is shifted by 90 degrees in the x and y directions, the direction in which the foils of the first dividing element 103 and the second dividing element 201 are laminated is It is most convenient when they are 90 degrees apart.
When the angle in the x direction and y direction of the two-dimensional information in the detector 106 is other than 90 degrees, the angles of the first dividing element 103 and the second dividing element 201 can be adjusted according to the angle. desirable.
Even if the angles of the detector 106 in the x and y directions are different from the angles in the direction in which the foils of the first split element 103 and the second split element 201 are laminated, Equation 7 is used. Thus, refraction information can be clarified by adding correction when creating a mapping of dI.

Since the angle at which the X-ray beam 105 is refracted by the subject 104 is independent in the x direction and the y direction, the ratio L2 / L1 that maximizes the ratio of the phase component of the subject 104 can be two-dimensional. Same as one dimension.
From this, in the case where a two-dimensional dividing element is used by using two pieces of the one-dimensional dividing element 103 of D25 and the one-dimensional dividing element 201 of D25 from FIGS.
When L2 / L1 = 1.3, the maximum ratio of the phase components can be obtained in both the x and y directions.
Further, from FIG. 8, even if the distance between the first dividing element 103 and the second dividing element 201 is about 10 cm, the error in the ratio of the phase components included in the differential images in the x and y directions is several percent. It is difficult to cause a big problem in image quality.
As shown in FIG. 9, the error of the ratio of the phase component included in the differential image generated by the positional relationship between the first split element 103 and the second split element 201 is the distance between the X-ray source 101 and the detector 106. The longer it is, the less it becomes.

  As shown in FIG. 10B, the two-dimensional dividing element may be formed by bonding two one-dimensional dividing elements 103 while maintaining 90 degrees in-plane with each other. In addition, a plate made of tungsten or the like that shields X-rays has holes formed in an array by electric discharge machining, or a substance that blocks X-rays is formed in an array by fine processing on a silicon substrate that transmits X-rays. May be good.

101: X-ray source 102: Divergent X-ray 103: Splitting element 104: Subject 105: X-ray beam 106: Detector 107: Computing device 108: Means for moving / rotating the X-ray source 109: Moving / rotating the splitting element Means 110: means for moving / rotating the two-dimensional detector 111: pixel 112: foil for transmitting X-ray 113: foil for shielding X-ray 114: reference X-ray beam when there is no subject

Claims (6)

An X-ray imaging apparatus,
An X-ray source;
A splitting element disposed between the X-ray source and the subject, comprising a plurality of openings for splitting the divergent X-rays irradiated from the X-ray source into a plurality of X-rays;
A detector disposed downstream of the subject in the irradiation direction of the X-ray beam in order to detect an X-ray beam by the divergent X-ray transmitted through the subject and refracted;
An arithmetic processing means for arithmetically processing information on an intensity change of the X-ray beam detected by the detector,
When the distance between the X-ray source and the dividing element is L1, and the distance between the dividing element and the detector is L2, the value of L2 / L1 is in the range of more than 1.0 and less than 2.4. An X-ray imaging apparatus characterized by that. The focal spot size of the X-ray source is 80 to 100 μm,
The size of the pixel is 50 to 150 μm,
When the width of the opening of the dividing element is 20 to 50 μm,
The X-ray imaging apparatus according to claim 1, wherein the value of L2 / L1 is configured to be in a range greater than 1.1 and less than 1.5. The distance L1 which is the distance between the X-ray source and the dividing element and the distance L2 which is the distance between the dividing element and the detector satisfy the following ranges, respectively. The X-ray imaging apparatus according to Item.

0.3m ≦ L1 ≦ 2m, 0.3m ≦ L2 ≦ 4.8m
  The X-ray imaging apparatus according to claim 1, wherein the X-ray beam transmitted through the dividing element has a sheet shape or a dot shape.   The X-ray imaging apparatus according to claim 1, wherein the X-ray beam straddles two or more adjacent pixels constituting the detector. Diversity X-rays irradiated from an X-ray source are divided into a plurality of X-rays by a dividing element, and the intensity change of the X-ray beam generated when the X-ray beam generated by the divided X-rays is transmitted through the subject. Is an X-ray imaging method for detecting
The splitting element, the subject, and the detector are arranged in this order on the optical path in the irradiation direction of the divergent X-ray by the X-ray source,
By making the relationship between the distance between the X-ray source and the splitting element and the distance between the splitting element and the detector into the relationship of the distance where the X-ray beam does not overlap on the detector,
An X-ray imaging method characterized in that a maximum ratio of phase information to absorption information in the subject can be acquired.

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