JP2008200359A - Radiographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic system obtaining a good image utilizable in medical diagnosis or biological diagnosis even in the case where a live animal or the human body is set as a subject. <P>SOLUTION: The radiographic system 100 has a subject stand 13 on which a subject H is arranged, a first diffraction lattice 15 for diffracting X rays, which are transmitted through the subject stand 13 to irradiate the subject H to produce a Talbot-effect, a second diffraction lattice 16 for diffracting X rays diffracted by the first diffraction lattice 15, an X-ray detector 14 for detecting X rays diffracted by the second diffraction lattice 16, and a diffraction lattice holding structure 17 for integrally holding the first diffraction lattice 15 and the second diffraction lattice 16. The diffraction lattice holding structure 17 and the subject stand 13 are formed as separate structures. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an X-ray imaging system, and more particularly to an X-ray imaging system capable of imaging an X-ray phase image.

Conventionally, as X-ray imaging, image diagnosis using an X-ray absorption image formed by X-ray absorption by a subject is generally used. However, for example, in the case of a subject with low X-ray absorption, such as the soft tissue of a human body or an animal, there is a problem that sufficient contrast cannot be obtained and image diagnosis is difficult or difficult.
Therefore, in order to discover changes in subjects with low X-ray absorption such as soft tissues, recently, instead of radiographic imaging, diagnostics using images obtained by MRI (magnetic resonance imaging) etc. have been studied. Has been. However, MRI imaging is a burden on the subject from the viewpoint of cost and time required for medical examination, and it is difficult to incorporate it into general periodic medical examinations. There was a problem that it was difficult to observe.

  On the other hand, as X-ray imaging, development of a technique for acquiring an X-ray phase image formed by an X-ray phase difference depending on a subject is underway. When this X-ray phase imaging is used for medical diagnosis, biodiagnosis, and food inspection, the contrast of the soft part of the subject is larger than that of the X-ray absorption image, or it can be clearly seen by the edge effect. It is possible to detect minute lesions and soft tissue lesions.

In X-ray phase imaging, various methods such as a crystal X-ray interferometer method, a DEI method, a propagation method, a Zemike phase difference microscope method, and a Talbot interferometer method have been developed.
For example, in the Talbot interferometer system disclosed in Patent Document 1, a plurality of Talbot effects by the first diffraction grating and moire fringe images obtained by the second diffraction grating are photographed by a fringe scanning method, and a phase shift image (phase difference image) is obtained. Image) and a phase shift differential image (differential phase image) are disclosed.
International Publication No. 2004/058070

  However, with the Talbot interferometer method, there is no problem with small subjects such as insects and stationary subjects such as food, plants, and phantoms. It has been found that there is a problem that if the positional relationship between the first diffraction grating and the second diffraction grating is shifted during X-ray irradiation, an image usable for medical diagnosis / biological diagnosis may not be obtained.

  That is, in X-ray imaging using a tungsten X-ray tube for obtaining a normal absorption image, a good image can be obtained by irradiating X-rays with high X-ray intensity in a very short time. Then, since the X-ray interference phenomenon is used, it is necessary to limit the wavelength range of the X-rays to be irradiated, so that the X-ray intensity is lowered and a long exposure is required. It was found that the allowable range of positional deviation between the first diffraction grating and the second diffraction grating that can be accepted is extremely narrow.

  Therefore, the present invention has been made to solve the above-described problems, and even when a live animal or a human body is used as a subject, an X-ray that can obtain a good image that can be used for medical diagnosis / biological diagnosis. An object is to provide a photographing system.

An X-ray imaging system according to the invention of claim 1 is provided.
A subject table for placing the subject;
A first diffraction grating that produces a Talbot effect by diffracting X-rays transmitted through the object table;
A second diffraction grating for diffracting X-rays diffracted by the first diffraction grating;
An X-ray detector for detecting X-rays diffracted by the second diffraction grating;
A diffraction grating holding structure that integrally holds the first diffraction grating and the second diffraction grating,
The diffraction grating holding structure and the subject table are separate structures.

The invention described in claim 2 is the X-ray imaging system according to claim 1,
A buffer means for buffering force and vibration applied to the object table is provided between the diffraction grating holding structure and the object table.

The invention described in claim 3 is the X-ray imaging system according to claim 1 or 2,
An X-ray source for irradiating the X-ray detector through the first diffraction grating and the second diffraction grating to the X-ray detector;
The ratio of the interval between the X-ray source and the first diffraction grating and the grating period of the first diffraction grating is such that the X-ray detector can detect a phase difference image or moire fringes. And a distance between the second diffraction grating and the grating period of the second diffraction grating.

According to a fourth aspect of the present invention, in the X-ray imaging system according to the third aspect,
The X-ray source is an X-ray tube or a microfocus X-ray source in which the half-value width of the wavelength distribution of X-rays to be irradiated is not more than 1/4 times the peak wavelength of the X-rays.

The invention according to claim 5 is the X-ray imaging system according to claim 3,
The peak wavelength of X-rays emitted from the X-ray source is 0.2 to 0.9 mm.

The invention described in claim 6 is the X-ray imaging system according to any one of claims 1 to 5,
At least one of the first diffraction grating and the second diffraction grating includes a diffraction member extending in one direction,
The diffraction grating holding structure holds at least one of the first diffraction grating and the second diffraction grating so as to be movable in a direction parallel to the diffraction grating surface and intersecting the extending direction of the diffraction member. And
A drive means for driving at least one of the movable first diffraction grating and the second diffraction grating is provided.

The invention described in claim 7 is the X-ray imaging system according to claim 6,
When the driving means is stopped and the X-ray detector is not reading an X-ray image, the X-ray source emits X-rays,
After the X-ray source stops X-ray irradiation, the X-ray detector starts reading an X-ray image, and the driving means drives at least one of the first diffraction grating and the second diffraction grating. Start
After the X-ray detector finishes reading the X-ray image and the driving means finishes driving at least one of the first diffraction grating and the second diffraction grating, the X-ray source emits X-rays. Control means for controlling the X-ray source, the X-ray detector and the drive means is provided so as to irradiate.

  According to the first aspect of the present invention, the diffraction grating holding structure integrally holds the first diffraction grating and the second diffraction grating, and the diffraction grating holding structure and the object table are separate structures. Even if force or vibration from the subject itself is applied to the subject table, such as when a live animal or human body is used as a subject, it is possible to prevent the positional relationship between the first diffraction grating and the second diffraction grating from being shifted. Even when an animal or a human body is used as a subject, a good image that can be used for medical diagnosis / biological diagnosis tends to be obtained.

  According to the second aspect of the present invention, since the force and vibration applied to the object table are buffered, even if force or vibration is applied to the object table from the object itself, the positional relationship between the first diffraction grating and the second diffraction grating is shifted. Therefore, even when a live animal or human body is used as a subject, a good image that can be used for medical diagnosis / biological diagnosis tends to be obtained.

  According to the third aspect of the present invention, even if force or vibration is applied to the subject table from the subject itself, it is possible to prevent the positional relationship between the first diffraction grating and the second diffraction grating from being shifted. Even when the human body is a subject, the positional relationship among the X-ray source, the first diffraction grating, and the second diffraction grating specified in this claim is satisfied, and better moire fringes that can be used for medical diagnosis and biological diagnosis are obtained. Tend to be.

  According to the fourth aspect of the present invention, the X-ray source is less expensive than the synchrotron X-ray source, and relatively long X-ray irradiation is required to perform X-ray imaging. Even if force or vibration is applied to the subject table, the positional relationship between the first diffraction grating and the second diffraction grating can be prevented from shifting, so even when a live animal or human body is the subject, medical diagnosis / biological diagnosis Therefore, a good image that can be used for the image tends to be obtained.

  According to the invention described in claim 5, since the peak wavelength of X-rays is 0.9 mm or less, even if the subject is a living animal or human body, the absorption exposure is reduced and the irradiation is performed for a long time such as 10 seconds or more. Furthermore, since the blurring of the subject H is suppressed during the photographing time, and the peak wavelength of the X-ray is 0.2 mm or more, the refraction due to the cartilage tissue of the human body can be sufficiently detected and obtained. Images can be used effectively for diagnosis and the like.

  According to the sixth aspect of the present invention, even when force or vibration is applied to the subject table from the subject itself, such as when a live animal or human body is the subject, the diffraction grating holding structure separate from the subject table is the driving means. Therefore, at least one of the first diffraction grating and the second diffraction grating can be driven with good positional accuracy, and a good image usable for medical diagnosis / biological diagnosis tends to be obtained.

  According to the seventh aspect of the present invention, the first diffraction grating and the second diffraction grating are moved to a desired positional relationship, and X-ray imaging can be performed in a stopped state, and the X-ray detector is not irradiated with X-rays. Since reading is performed at the timing, good reading can be performed, and a good image usable for medical diagnosis / biological diagnosis tends to be obtained.

Hereinafter, embodiments of an X-ray imaging system according to the present invention will be described with reference to the drawings.
The best mode column for carrying out the invention indicates a mode that the inventor recognizes as the best for carrying out the invention, and is used in the scope of the invention and in the claims. There are also expressions that seem to be asserted or defined at first glance, but these are only expressions that specify the form that the inventor recognizes as the best, and are used in the scope of the invention and in the claims. It is not intended to identify or limit the terminology used.

<First Embodiment>
A first embodiment of an X-ray imaging system according to the present invention will be described with reference to FIGS.

FIG. 1 shows a configuration example of an X-ray imaging apparatus applied to the X-ray imaging system in the present embodiment, and FIG. 2 is a diagram showing a control configuration of the X-ray imaging system.
As shown in FIG. 2, the X-ray imaging system 100 controls the X-ray imaging apparatus 1 that performs X-ray imaging of the subject H and the X-rays irradiated to the subject H by controlling each part of the X-ray imaging apparatus 1. And a console 3 that performs image processing of an X-ray image acquired by irradiating or irradiating X-rays.

  As shown in FIG. 1, the X-ray imaging apparatus 1 includes a support base 11 fixed to a floor surface with a bolt or the like. The support base 11 includes a support member 111 that extends in a direction perpendicular to the floor surface, and an upper portion of the support member 111 has an X-ray optical axis direction that is substantially vertical from above to below. An X-ray irradiation unit 12 that irradiates X-rays is provided. A subject table 13 that supports the subject H from below is disposed at a position below the X-ray irradiating unit 12 in the X-ray optical axis direction. An X-ray detector 14 that detects X-rays emitted from the X-ray irradiation unit 12 and transmitted through the subject H is provided at a position below the subject table 13 in the X-ray optical axis direction. In addition, a first diffraction grating 15 and a second diffraction grating 16 (see FIG. 3 and the like) are integrally held between the subject table 13 and the X-ray detector 14 and configured separately from the subject table 13. A diffraction grating holding structure 17 is provided.

  The X-ray irradiation unit 12 includes a high-voltage power supply 121 that supplies a high voltage to the X-ray tube 122 and an X-ray tube 122 (X-ray source) that generates X-rays with the high voltage supplied from the high-voltage power supply 121. Is provided. The X-ray irradiation unit 12 includes an X-ray source control unit 123, and the high voltage power supply 121 and the X-ray tube 122 are connected to the X-ray source control unit 123, respectively. The X-ray source control unit 123 controls the high voltage power supply 121 and the X-ray tube 122 based on a control signal from the control device 31 (see FIG. 2) of the console 3.

The X-ray tube 122 is an X-ray source that irradiates the X-ray detector 14 with X-rays via the first diffraction grating 15 and the second diffraction grating 16. Examples of the X-ray tube 122 include a Coolidge X-ray tube and a rotary anode X-ray tube widely used in medical sites and non-destructive inspection facilities. In the rotary anode X-ray tube, X-rays are generated when an electron beam emitted from the cathode collides with the anode. This is incoherent (incoherent) like natural light, and is not divergent X-rays but divergent light. If the electron beam continues to hit the place where the anode is fixed, the anode is damaged by the generation of heat. Therefore, in the normally used X-ray tube 122, the anode is rotated to prevent the life of the anode from being reduced.
By causing the electron beam to collide with a surface of a certain size of the anode, the generated X-rays are emitted toward the subject H from the plane of the certain size of the anode. The size of the plane viewed from the irradiation direction (subject direction) is called the actual focus (focus). The focal diameter (μm) can be measured by the method defined in (2.2) slit camera of 7.4.1 Focus test of JIS Z 4704-1994. Note that it is needless to say that the optional selection conditions in this measurement method can be measured with higher accuracy by selecting the conditions that give the highest accuracy in consideration of the measurement principle according to the properties of the X-ray irradiation unit 12. Yes.

  The X-ray source is preferably such that the half-value width of the wavelength distribution of the X-ray to be irradiated is ¼ times or less of the peak wavelength of the X-ray, and the X-ray source is limited to the X-ray tube. For example, the microfocus X-ray source described in JP-A-9-171788, JP-A-2000-173517, JP-A-2001-273860, and the like, for example, JP-A-5-217696, Synchrotron radiation X-ray sources described in Japanese Patent Application Laid-Open No. 2002-221500, etc., for example, Japanese Patent Application Laid-Open Nos. 47-024288, 64-6349, 63-304597, and Japanese Patent Application No. 63-304596, JP-A-1-109646, JP-A-58-158842, etc., for example, a laser X-ray source described in Japanese Patent No. 3490770 It may be a X-ray source, but not limited to.

    The peak wavelength of X-rays is 0.9 mm or less (especially 0.7 mm or less), so that even if the subject is a living animal or human body, the amount of absorbed exposure is reduced and no long-term irradiation such as 10 seconds or more is required. Furthermore, it is preferable that blurring of the subject H can be suppressed during the photographing time. The peak wavelength of the X-ray is 0.2 mm or more (particularly 0.4 mm or more), which improves the coherence of the X-ray and can sufficiently detect refraction due to, for example, human or animal cartilage tissue. The obtained image can be effectively used for diagnosis and the like, which is preferable.

In addition, as the X-ray tube 122, for example, a Coolidge X-ray tube or a rotary anode X-ray tube widely used in the medical field is preferably used. At that time, when Mo (molybdenum) used in mammography is used as the target (anode) of the X-ray tube, X-rays with a tube voltage set value of 22 kVp and a peak wavelength of 0.8 mm are generally irradiated. X-rays having a voltage set value of 39 kVp and a peak wavelength of 0.6 mm are irradiated. Further, when W (tungsten) used for general imaging is used as the target, the set values of the tube voltage are 30, 50, 100, and 150 kVp, and the peak wavelengths are 0.6 mm, 0.4 mm, 0.3 mm, 0. Two X-rays are usually irradiated.
Further, the focal diameter of the X-ray source is preferably 1 μm or more (particularly 7 μm or more) so that X-rays having a peak wavelength in the above range can be irradiated and a practical output intensity can be obtained. In addition, the focal diameter of the X-ray source is 50 μm or less (particularly 30 μm or less), while there are restrictions on the size of the imaging device, the coherence is improved, and a clear image is obtained using the Talbot effect. Therefore, it is preferable.

The subject table 13 is held by a holding member 18 held on the support base 11 and is fixed to the support member 111 so as to be substantially parallel to the floor surface. A portion of the holding member 18 that contacts the subject table 13 is provided with a buffer member 19 that absorbs and relieves shocks and vibrations. The subject table 13 is held by the holding member 18 via the buffer member 19. Yes.
The subject table 13 includes the first diffraction grating 15 and the first diffraction grating 15 in the horizontal direction at least in the direction in which the subject is supported on the subject table 13 and the direction in which the subject supported on the subject table 13 is separated. The shape protrudes from the two diffraction gratings 16 and the diffraction grating holding structure 17, and the subject may contact the first diffraction grating 15, the second diffraction grating 16, and the diffraction grating holding structure 17. Is reduced.
As a material of the buffer member 19, for example, hard rubber or various resins can be applied, but the material of the buffer member 19 is not limited thereto.

  The X-ray detector 14 includes a panel 141, a detector power supply unit 142, a detector communication unit 143, a detector control unit 144, and the like. The panel 141, the detector power supply unit 142, the detector communication unit 143, and the detector control unit 144 are each connected to a bus in the X-ray detector 14.

  The panel 141 is disposed on the surface of the X-ray detector 14 (the surface facing the subject H), and outputs X-ray image data based on the X-rays emitted from the X-ray irradiation unit 12 and transmitted through the subject H. Is.

In the present embodiment, the panel 141 is a two-dimensional image sensor, and the X-ray detector 14 reads a signal based on the X-ray irradiation amount for each of a number of pixels arranged two-dimensionally on the panel 141 to obtain X-ray image data. FPD (flat panel detector) that acquires Each pixel (not shown) of the panel 141 is arranged in a matrix.
In addition, the pixel pitch of panel 141 (P ₃ in formula (8) described later) is preferably 30 μm or more (particularly 60 μm or more) from the viewpoint of X-ray quantum noise, and sufficient detection of stripe deformation described later is possible. From a viewpoint, 300 micrometers or less (especially 150 micrometers or less) is preferable.
Such an FPD may be a direct FPD having an array sensor that detects X-rays by directly converting them into electric charges, or a scintillator that converts X-rays into light and light converted by the scintillator. It may be an indirect FPD having an array sensor that detects by converting into electric charge. Indirect FPD scintillators include those having columnar crystal phosphors, those in which phosphors are packed in a box formed in pixel units of an array sensor described in Japanese Patent No. 3661196, and the like. However, the present invention is not limited to these. In addition, the thicker the scintillator, the higher the sensitivity, and the thinner the scintillator, the higher the spatial resolution. The spectral sensitivity varies depending on the type of scintillator. The scintillator phosphor is preferably an alkali metal halide or alkaline earth metal halide such as CsI: Tl.

  The detector power supply unit 142 supplies power to each unit disposed in the X-ray detector 14. The detector power supply unit 142 is provided with, for example, a capacitor that can be charged and can handle power consumed during photographing. The configuration of the detector power supply unit 142 is not limited to that shown here.

  The detector communication unit 143 transmits / receives a signal to / from the console 3 via the interface 34 (referred to as “I / F” in FIG. 2) of the console 3, and transmits X-ray image data to the console 3. It is a functional part that can be used. In general, the X-ray imaging apparatus 1 is, for example, an X-ray imaging room covered with an X-ray shielding member such as a lead plate (a metal member having a property of suppressing transmission of radio waves or a property of reflecting radio waves). The console 3 is provided in an X-ray control room (not shown) in which an operator such as an X-ray engineer waits. For this reason, when the detector communication unit 143 transmits and receives signals wirelessly, a radio repeater (not shown) is provided in the X-ray imaging room, and signals are transmitted to and from the console 3 via the radio repeater. It is configured to be able to send and receive.

  The detector control unit 144 controls each unit provided in the X-ray detector 14 based on the control signal received by the detector communication unit 143. Specifically, the detector control unit 144 reads a signal based on the X-ray irradiation amount detected for each pixel of the panel 141, and detects the X-ray image data obtained as a result of the reading by detector communication. To the console 3 via the unit 143.

The diffraction grating holding structure 17 is, for example, a member formed in a frame shape as shown in FIG. 3. The first diffraction grating 15 is held on one surface of the diffraction grating holding structure 17, and the other A second diffraction grating 16 is held on the surface. The diffraction grating holding structure 17 is fixed to the support member 111 of the support base 11 via the buffer member 171 so that the first diffraction grating 15 and the second diffraction grating 16 are arranged substantially parallel to the floor surface. .
The buffer member 171 is formed of, for example, hard rubber or various resins as with the buffer member 19, but the material forming the buffer member 171 is not limited thereto.

  As described above, the diffraction grating holding structure 17 has a separate structure from the subject table 13, and the diffraction grating holding structure 17 and the subject table 13 buffer the force and vibration applied to the subject table 13. Buffer means 19 and 171 are arranged, respectively. As a result, even when a force is applied to the subject table 13 or a vibration occurs due to the subject H moving, the positional relationship between the first diffraction grating 15 and the second diffraction grating 16 held by the diffraction grating holding structure 17. Thus, there is no influence such as the occurrence of a shift.

  In the present embodiment, as shown in FIG. 4, X-rays emitted from the X-ray irradiator 12 and transmitted through the subject H pass through the first diffraction grating 15 and the second diffraction grating 16, and the X-ray detector 14. The Talbot interferometer is constituted by the X-ray irradiator 12, the first diffraction grating 15, and the second diffraction grating 16. The conditions for configuring the Talbot interferometer will be described later.

5 is a cross-sectional view of the first diffraction grating 15 taken along the line II in FIG.
As shown in FIGS. 4 and 5, the first diffraction grating 15 includes a substrate 151, a plurality of diffractive members 152 arranged on the substrate 151, and an adjacent diffractive member 152 so as to embed each other. A holding member 153 for holding the member 152 is provided, and a Talbot effect to be described later is generated by diffracting X-rays transmitted through the subject table 13 and the subject H held thereon. The substrate 151 is made of, for example, glass. Note that a surface of the substrate 151 on which the diffraction member 152 is disposed is a diffraction grating surface.

Each of the plurality of diffraction members 152 is a linear member extending in one direction (for example, the vertical direction in FIG. 4 in the present embodiment) orthogonal to the X-ray irradiation direction irradiated from the X-ray irradiation unit 12. .
The thickness of each diffraction member 152 is substantially equal. For example, in the case of an absorption type diffraction grating, 10 μm or more and 100 μm or less is preferable, and in the case of a phase type diffraction grating, 1 μm or more and 10 μm or less is preferable.

In addition, the arrangement interval (grating period) d ₁ (see FIG. 5) of the plurality of diffraction members 152 is constant, that is, the arrangement intervals of the plurality of diffraction members 152 are equal intervals, and an interval of 2 μm or more and 10 μm or less is preferable.

As a material constituting the plurality of diffraction members 152, a material having excellent X-ray absorption is preferable, and for example, a metal such as gold, silver, or platinum can be used. The diffractive member 152 is formed by, for example, plating or vapor-depositing these metals on the substrate 151.
The diffractive member 152 changes the phase velocity of the X-rays irradiated to the diffractive member 152. The diffractive member 152 is (1/3) × π or more (2/3) with respect to the irradiated X-rays. ) × π or less (particularly, (3/8) × π or more and (5/8) × π or less, ideally (1/2) × π)) is formed so-called phase type diffraction grating It is preferable that

6 is a cross-sectional view of the second diffraction grating 16 taken along the line II-II in FIG.
4 and 6, the second diffraction grating 16 is adjacent to the substrate 161, the plurality of diffraction members 162, and the adjacent diffraction members 162, similarly to the first diffraction grating 15. The holding member 163 that holds the diffractive member 162 is provided. The surface of the substrate 161 on which the diffractive member 162 is disposed is a diffraction grating surface.

  Moreover, although the 1st diffraction grating 15 and the 2nd diffraction grating 16 can be produced by well-known methods, such as the method of Unexamined-Japanese-Patent No. 2006-259264, for example, you may produce by a method not known.

  The second diffraction grating 16 is held by the diffraction grating holding structure 17 in such an arrangement that the extending direction of the diffraction member 162 coincides with the extending direction of the diffraction member 152 of the first diffraction grating 15. The image contrast is formed by diffracting the X-rays diffracted by one diffraction grating 15. The second diffraction grating 16 is desirably an amplitude type diffraction grating in which the diffraction member 162 is made thicker, but may have the same configuration as the first diffraction grating 15. For example, in the case of an absorption type diffraction grating, the thickness is preferably 20 μm or more and 200 μm or less, and in the case of a phase type diffraction grating, it is preferably 1 μm or more and 10 μm or less.

Next, the conditions under which the X-ray irradiation unit 12, the first diffraction grating 15, and the second diffraction grating 16 constitute a Talbot interferometer will be described.
First, from the coherence of X-rays, the focal length a of the X-ray source in the direction substantially orthogonal to the diffraction member, the distance L (see FIG. 1) from the X-ray source to the first diffraction grating, and the first diffraction grating to the first diffraction grating Assuming that the distance Z ₁ to the second diffraction grating (see FIG. 1), the distance Z ₂ from the second diffraction grating to the X-ray detector (see FIG. 1), and the peak wavelength λp of the irradiated X-rays, the first diffraction grating 15 The distance d ₁ (see FIG. 5) of the diffraction members and the distance d ₂ (see FIG. 6) of the diffraction members of the second diffraction grating 16 preferably satisfy the following formulas.
d ₁ <(L / a) × λp (1)
d ₂ <{(L + Z ₁ ) / a} × λp (2)

Further, the distance Z ₁ between the first diffraction grating 15 and the second diffraction grating 16 assumes that the first diffraction grating 15 is an absorptive diffraction grating, and the following condition is satisfied for any natural number m. It is ideal to satisfy.
Z ₁ = m × (d ₁ ² / λp)
Actually, it is preferable that the following condition is satisfied in any natural number m.
(M-1 / 8) × (d ₁ ² / λp) ≦ Z ₁ ≦ (m + 1/8) × (d ₁ ² / λp) (4)

Further, the distance Z ₁ between the first diffraction grating 15 and the second diffraction grating 16 is set to satisfy the following condition for any natural number m, assuming that the first diffraction grating 15 is a phase type diffraction grating. It is ideal to satisfy.
Z ₁ = (m−1 / 2) × (d ₁ ² / λp) (5)
Actually, it is preferable that the following condition is satisfied in any natural number m.
(M-5 / 8) × (d ₁ ² / λp) ≦ Z ₁ ≦ (m−3 / 8) × (d ₁ ² / λp) (6)
In these formulas (3) to (6),
λp: peak wavelength of X-rays irradiated from the X-ray irradiation unit,
Z ₁ : distance from the first diffraction grating to the second diffraction grating (see FIG. 7),
d ₁ : Distance between the diffraction members of the first diffraction grating (see FIG. 5)
It is.

Here, the Talbot effect means that when a plane wave passes through a diffraction grating, when the diffraction grating is a phase type diffraction grating, a self-image of the diffraction grating is formed at a distance given by Expression (3) or Expression (5). That is. However, if the distance satisfies Expression (4) or Expression (6), the following phenomenon occurs sufficiently, although it is slightly blurred.
In the case of the present embodiment, the X-rays irradiated from the X-ray irradiating unit 12 pass through the subject H, causing a phase shift of the X-rays due to the subject H. Therefore, the X-rays incident on the first diffraction grating 15 The wavefront is distorted. Therefore, the self-image of the first diffraction grating 15 is deformed depending on it. Subsequently, the X-ray passes through the second diffraction grating 16. As a result, the superposition of the deformed self-image of the first diffraction grating 15 and the second diffraction grating 16 causes an image contrast in the X-ray. This image contrast is generally moiré fringes and can be detected by the X-ray detector 14. The generated moire fringes are modulated by the subject H. The amount of modulation is proportional to the angle at which the X-ray is bent by the refraction effect of the subject H. Therefore, by analyzing the moiré fringes detected by the X-ray detector 14, the subject H and its internal structure can be detected.

Further, the ratio between the distance L between the X-ray tube 122 and the first diffraction grating 15 and the grating period d ₁ of the first diffraction grating 15 is determined by the X-ray detector 14 analyzing the moire fringes (or moire fringes). The ratio of the distance (L + Z ₁ ) between the X-ray tube 122 and the second diffraction grating 16 and the grating period d _{2 of} the second diffraction grating 16 is such that the obtained differential phase difference image and phase difference image) can be detected. As will be described later, this is ideal for adjusting the spacing of the stripes by only the small angle θ. That is, satisfying the following expression is ideal for adjusting the stripe interval only by the minute angle θ as will be described later.
d ₁ / L = d ₂ / (L + Z ₁ ) (7)

Note that the diffraction members 152 and 162 of the first diffraction grating 15 or the second diffraction grating 16 are relatively rotated by a minute angle θ around a virtual axis passing through the X-ray irradiation unit 12 and the X-ray detector 14. Are arranged. The interval between the generated moire fringes varies depending on the magnitude of θ. If there is no subject H, the moire fringe spacing is given by d ₃ / θ. Here, d ₃ is a distance obtained by projecting the distance between the diffractive members 152 of the first diffraction grating 15 from the center of the X-ray tube 122 onto the X-ray detection surface (that is, the X-ray detector 14). The distance between the diffraction members 162 of the diffraction grating 16 is the distance projected from the center of the X-ray tube 122 onto the X-ray detection surface (that is, the X-ray detector 14).
If a mechanism for changing the minute angle θ (for example, a mechanism for rotating one of the first diffraction grating 15 and the second diffraction grating 16 relative to the other) is provided, the moire fringes are adjusted as preferable for observation. It becomes possible to do. Further, if the minute angle θ is adjusted to be substantially zero, moire fringes do not appear in portions other than the portion corresponding to the subject H (that is, in the non-modulated portion). As a result, only the absorption contrast due to the subject H appears in the obtained X-ray image.

If it is not necessary to obtain an X-ray image having only the absorption contrast while the first diffraction grating 15 and the second diffraction grating 16 are arranged at predetermined positions, the condition of the above equation (7) does not need to be satisfied. D _1, d _{2, and} θ may be selected as appropriate so that the spacing between the stripes that can be detected by the line detector 14 is obtained.
The ratio of the distance L between the X-ray tube 122 and the first diffraction grating 15 and the grating period d ₁ of the first diffraction grating 15 is determined by the X-ray detector 14 analyzing the moire fringes (or moire fringes). The ratio of the distance (L + Z ₁ ) between the X-ray tube 122 and the second diffraction grating 16 and the grating period d _{2 of} the second diffraction grating 16 is such that the obtained differential phase difference image and phase difference image) can be detected. The term “close” means that the change in fringes generated by the X-ray detector 14 is close enough to be detected. Preferably, the pixel pitch P ₃ of the X-ray detector 14 satisfies the following expression.
[1- (d ₁ / L) × {(L + Z ₁ + Z ₂ ) / P ₃ }] × (d ₁ / L) ≦ d ₂ / (L + Z ₁ ) ≦ [1+ (d ₁ / L) × {(L + Z ₁ + Z ₂ ) / P ₃ }] × (d ₁ / L) (8)

  In the present embodiment, the diffraction grating holding structure 17 holds the first diffraction grating 15 so as to be movable in a direction parallel to the diffraction grating surface 153 and intersecting the extending direction of the diffraction member 152. The first diffraction grating 15 is provided with a piezoelectric actuator 20 (hereinafter simply referred to as “actuator” in FIG. 2 and the following description) that is deformed by applying a voltage.

The actuator 20 operates in accordance with an instruction signal from the console 3, and the first diffraction grating 15 is substantially parallel to the diffraction grating surface 153 of the first diffraction grating 15 and substantially intersects with the extending direction of the diffraction member 152. It is a drive means to move to the direction to do.
When the actuator 20 is driven, the first diffraction grating 15 is translated relative to the second diffraction grating 16.
The driving means is not limited to the piezoelectric actuator exemplified here as long as it can move the first diffraction grating 15 little by little.

The console 3 shown in FIG. 2 includes a control device 31 including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (all not shown).
The control device 31 includes an input device 32 for inputting an imaging preparation instruction, an imaging instruction, and instruction contents, a display device 33 for displaying an X-ray image, and an interface 34 connected to each part of the X-ray imaging apparatus 1. An image storage unit 35 that stores image information, a console power supply unit 36 that supplies power to each unit of the console 3, and the like are connected via a bus.

  For example, an X-ray irradiation request switch, a touch panel, a mouse, a keyboard, a joystick, or the like can be used as the input device 32. For example, an X-ray tube voltage, an X-ray tube current, or an X-ray can be operated by operating the input device 32. X-ray imaging conditions such as irradiation time, X-ray imaging control conditions such as imaging timing, imaging region, imaging method, image processing conditions, image output conditions, X-ray detector selection information (a plurality of imaging devices are connected to the console 3 If there is an instruction), instruction selection information such as order selection information and subject ID is input.

  The display device 33 is, for example, a CRT (Cathode Ray Tube) display, a liquid crystal display, or the like. The display device 33 is controlled by the control device 31 of the console 3 so that characters such as X-ray imaging conditions and image processing conditions, and X-rays are displayed. Display an image.

  The image storage unit 35 temporarily stores X-ray image data received from the X-ray detector 14 via the interface 34 and stores image-processed X-ray image data. As the image storage unit 35, a hard disk that is a large-capacity and high-speed storage device, a hard disk array such as a RAID (Redundant Array of Independent Disks), a silicon disk, or the like can be used.

  The console power supply unit 36 supplies power to each unit constituting the console 3 from an external power supply or an internal power supply.

  A control program and various processing programs for controlling each part of the X-ray imaging system 100 are stored in the internal storage device of the control device 31, and the CPU cooperates with the control program and the various processing programs to perform X-rays. The operation of each part of the imaging system 100 is comprehensively controlled to perform X-ray image imaging.

  For example, the control device 31 controls the X-ray source control unit 123 of the X-ray imaging apparatus 1 so as to adjust the voltage supplied from the high voltage power supply 121 to the X-ray tube 122. Then, the high voltage power supply 121 supplies a predetermined voltage to the X-ray tube 122, the X-ray tube 122 irradiates the subject H with X-rays, and the X-ray dose incident on the X-ray detector 14 is set in advance. When the X-ray dose is reached, the high-voltage power supply 121 stops supplying high voltage to the X-ray tube 122, and the X-ray source 2 stops X-ray irradiation.

In the present embodiment, the control device 31 reads the signal from the panel 141 in the X-ray detector 14 and moves from the X-ray source 2 when the movement of the first diffraction grating 15 by the actuator 20 is stopped. The X-ray source control unit 123 is controlled to perform the X-ray irradiation.
Whether or not the movement of the first diffraction grating 15 by the actuator 20 is stopped can be determined by detecting a voltage applied to the actuator 20, for example. In addition, when an acceleration sensor is fixed to the first diffraction grating 15, it may be determined by detecting from the output of the acceleration sensor, and a position sensor for detecting the position of the first diffraction grating 15 is provided. May be determined by detecting from the output of the position sensor, and when a speed sensor for detecting the movement of the first diffraction grating 15 is provided, it is detected from the output of the speed sensor. You may judge by doing.

  In addition, the control device 31 operates the detector control unit 144 of the X-ray detector 14 to start reading a signal based on the X-ray irradiation amount detected for each pixel of the panel 141, and obtains the result of the reading. The X-ray image data thus received is transmitted to the console 3 via the detector communication unit 143.

In addition, the control device 31 operates the actuator 20 to move the first diffraction grating 15 by a predetermined amount.
In the present embodiment, the first diffraction grating 15 is translated relative to the second diffraction grating 16 by the actuator 20 as described above. The direction of the first diffraction grating 15 is substantially parallel to the diffraction grating surface 153 of the first diffraction grating 15 and is substantially perpendicular to the extending direction of the diffraction member 152.

  As the first diffraction grating 15 translates relative to the second diffraction grating 16, the moire fringes move, and the movement distance (translation distance) of the first diffraction grating 15 is the grating of the first diffraction grating 15. When reaching one period, the moire fringe image is restored. In the present embodiment, the control device 31 performs X-ray imaging a plurality of times while translating the first diffraction grating 15 by, for example, an integral part of one period of the grating period of the first diffraction grating 15. ing.

  That is, when the first X-ray imaging is performed, the control device 31 operates the actuator 20 to move the first diffraction grating 15 relative to the second diffraction grating 16 by 1 / integer of one period of the grating period. The second shot is taken. Thereafter, the control device 31 operates the actuator 20 to translate the first diffraction grating 15 further in the same direction by an integral number of one cycle of the diffraction member 152 to perform the third imaging. The photographing and the movement of the first diffraction grating 15 are repeated a plurality of times.

Note that the control device 31 is adapted to acquire the movement amount information of the actuator 20 and obtain movement amount information for obtaining movement amount information regarding the movement amount of the first diffraction grating 15 by each actuator 20 during a plurality of imaging operations. It is designed to function as a means.
Note that the amount of movement by which the first diffraction grating 15 is moved by the actuator 20 may be set as a default in advance, or may be arbitrarily set by the operator as appropriate.

  In this embodiment, the X-ray detector 14 or the control device 31 corrects the offset / gain characteristics of each pixel unique to the X-ray detector 14. Then, for the X-ray image whose offset / gain characteristics have been corrected, the control device 31 transmits the subject H, the first diffraction grating 15 and the second diffraction grating 16 and detects the X-ray detected by the X-ray detector 14. Analyze line image contrast (moire fringes). Thereby, the control apparatus 31 calculates a differential phase image and a phase difference image based on the radiation dose of each pixel acquired from the X-ray detector 14. Further, the control device 31 acquires an absorption image based on the difference in the X-ray absorption rate of the subject H as necessary.

That is, in the present embodiment, as described above, X-ray imaging is performed a plurality of times while the first diffraction grating 15 is translated relative to the second diffraction grating 16, and the control device 31 It functions as a differential phase image acquisition means for obtaining a differential phase image from a plurality of X-ray images obtained by X-ray imaging and the movement amount information of the first diffraction grating 15.
Further, the control device 31 functions as a phase difference image acquisition unit that obtains a phase difference image from a plurality of X-ray images obtained by a plurality of X-ray images and movement amount information of the first diffraction grating 15.

  Hereinafter, a method for calculating the differential phase image and the phase difference image will be described.

  First, the differential phase image is a distribution image of the angle at which the X-ray is bent by the refraction effect by the subject H, and the control device 31 is detected by the X-ray detector 14 by using the fringe scanning method described below. An X-ray image in which moiré fringes appear (hereinafter referred to as “stripe image”) is converted into a differential phase image.

  In the fringe scanning method, imaging is performed while one of the first diffraction grating 15 and the second diffraction grating 16 is translated relative to the other. In this embodiment, the first diffraction grating 15 is replaced with the second diffraction grating 15. 16 is translated relative to 16.

As the first diffraction grating 15 moves, the moire fringes move, and when the translation distance (movement amount) reaches one period of the grating period of the first diffraction grating 15, the fringe image returns. In the fringe scanning method, such a change in the fringe image is recorded while moving the first diffraction grating 15 by an integral number of one period of the grating period, and the differential phase image φ (x , Y). (X, y) is a coordinate indicating the position of the pixel. The fringe image I (x, y) is generally given by the following equation (9), where the amount of movement is ξ.

Here, A _k (k = 0, 1,...) Is a constant determined by the shape of the first diffraction grating 15. Δ (x, y) represents the contribution of contrast generated regardless of the subject H due to distortion, manufacturing error, and arrangement error of the first diffraction grating 15. d is a grating period of the first diffraction grating 15 to be moved, and Z ₁ is an interval between the first diffraction grating 15 and the second diffraction grating 16. Now, it is assumed that M striped images are acquired by performing M times of X-ray imaging while changing ξ at step d / M (M: integer). If the term k> N is sufficiently small in the equation (3) and can be ignored, the following equation (10) is satisfied if M is selected so as to satisfy M> N + 1.

arg [] means extraction of declination. Ip (x, y) is the value of equation (3) when ξ = pd / M. d and Z ₁ are known, and Δ (x, y) can be obtained in advance by performing the same measurement when the subject H is not present (that is, ψ (x, y) = 0). Therefore, ψ (x, y) can be obtained from the above.

Next, the phase difference image is an image representing the phase shift itself by integrating the differential phase image, and the phase difference image Φ (x, y) and the differential phase image ψ (x, y) are: It is related by the following formula (11).

  Here, x corresponds to the direction in which the first diffraction grating 15 is translated by the fringe scanning method. Thus, the phase difference image Φ (x, y) is given by integrating the differential phase image ψ (x, y) along the x axis.

The phase difference image Φ (x, y) is given by the following formula (12), where n (x, y, z) is the refractive index distribution of the subject.

  When X-rays pass through the object, an X-ray image corresponding to the difference in X-ray absorption rate of the object is formed and detected by the X-ray detector 14. The image obtained by this is an absorption image. For example, when the subject H to be photographed is a bone part of a human body, a method of generating an X-ray image according to the difference in the X-ray absorption rate of such an object. The image with sufficient contrast can also be obtained.

  Note that any of these image generation methods can be sufficiently used according to the purpose of the X-ray imaging, and the control device 31 can output the differential phase image φ at the time of outputting the differential phase image. (X, y) is generated and output to the display device 33. At the time of outputting the phase difference image, the differential phase image is integrated to calculate the phase difference image Φ (x, y). Output. At the time of outputting an absorption image, the control device 31 generates an absorption image corresponding to the X-ray absorption contrast and outputs the absorption image to the display device 33.

  In addition, when a plurality of types of images (for example, differential phase images, phase difference images, and absorption images) are acquired by photographing, the control device 31 associates the plurality of types of images with each other in the image storage unit 35. It comes to memorize.

  Next, an X-ray imaging method executed by the X-ray imaging system 100 of the present embodiment will be described with reference to FIG.

  First, after holding the subject H on the subject table 13, the control device 31 transmits an X-ray imaging start signal for starting imaging to the X-ray irradiation unit 12 and the X-ray detector 14 of the X-ray imaging device 1 (step S1). ). At this time, the control device 31 resets the number N of photographings to zero.

  When an X-ray imaging start signal is transmitted from the control device 31, the high voltage power supply 121 supplies a high voltage to the X-ray tube 122, and the X-ray tube 122 irradiates the subject H with X-rays (step S2). . X-rays that have passed through the subject H pass through the first diffraction grating 15. At this time, X-rays are diffracted by the first diffraction grating 15 to generate the Talbot effect. Further, the X-ray passes through the second diffraction grating 16 and is detected by the X-ray detector 14.

  The control device 31 determines whether or not a predetermined X-ray dose has been irradiated (step S3). If the predetermined X-ray dose has not been reached (step S3; NO), the control device 31 returns to step S2 and continues the X-ray irradiation. When the predetermined X-ray dose has been reached (step S3; YES), the control device 31 operates the detector control unit 144 to read a signal based on the X-ray irradiation dose for each pixel from the panel 141. An X-ray image for acquiring line image data is read (step S4).

  The control device 31 determines whether or not the reading of the X-ray image by the X-ray detector 14 has been completed (step S5). If the reading has not been completed (step S5; NO), the control device 31 returns to step S4 and reads it. Let the operation continue. If the reading has been completed (step S5; YES), the control device 31 increments the number of photographing N to N + 1 (step S6), and determines whether a predetermined number of photographing has been completed (step S7).

  If the predetermined number of times of photographing has not been completed (step S7; NO), the control device 31 operates the actuator 20 so that the first diffraction grating 15 and the second diffraction grating 16 have a predetermined positional relationship. The first diffraction grating 15 is moved to a predetermined position for the next (N + 1) imaging (step S8). And the control apparatus 31 judges whether the 1st diffraction grating 15 moved to the predetermined imaging position (step S9), and when the 1st diffraction grating 15 has not moved to the predetermined imaging position (step S9; NO) ), The process returns to step S8 and the movement of the first diffraction grating 15 by the actuator 20 is continued.

On the other hand, when the first diffraction grating 15 has moved to the predetermined imaging position (step S9; YES), the control device 31 repeats step 2 to step 7 to perform the next (N + 1) imaging. Do.
When the predetermined number of times of imaging has been completed (step S7; YES), the control device 31 performs image processing of the captured X-ray image (step S10), and appropriately performs a differential phase image, a phase difference image, and absorption. Generate an image. Then, the generated image processed images are stored in the image storage unit 35 in association with each other (step S11), and the process is terminated.

  As described above, the time from the start of the first X-ray irradiation to the end of the last X-ray irradiation of the predetermined number of times of imaging is 10 seconds or less (particularly 3 seconds or less, particularly when the subject is a living animal or human body). Further, it is preferably 1 second or less) because blurring of the subject can be suppressed.

  As described above, according to the present embodiment, the diffraction grating holding structure 17 integrally holds the first diffraction grating 15 and the second diffraction grating 16, and the diffraction grating holding structure 17 and the subject. Since the base 13 has a separate structure, the first diffraction grating 15 and the second diffraction grating 15 and the second diffraction grating 15 are applied even when force or vibration is applied to the subject base 13 from the subject H itself, such as when the subject H is a living animal or a human body. Since it is possible to suppress a deviation in the positional relationship of the diffraction grating 16, even when a living animal or a human body is the subject H, a good image that can be used for medical diagnosis / biological diagnosis can be obtained.

  In the present embodiment, the FPD has been described as an example of the X-ray detector 14, but the X-ray detector 14 is not limited to this. Besides the FPD, for example, a cassette containing a stimulable phosphor sheet can be used as the X-ray detector 14.

  In this embodiment, the case where the actuator 20 is provided at one end of the first diffraction grating 15 has been described as an example. However, the diffraction grating provided with the actuator 20 may be the second diffraction grating 16. Good. In this case, the first diffraction grating 15 is fixed, and the second diffraction grating 16 is moved by a predetermined amount of movement by the actuator 20. Moreover, the actuator 20 may be provided in both the first diffraction grating 15 and the second diffraction grating 16, and the first diffraction grating 15 and the second diffraction grating 16 may be configured to be relatively movable.

In the present embodiment, the diffraction grating holding structure 17 is a member formed in a frame shape. However, the diffraction grating holding structure 17 includes the first diffraction grating 15 and the second diffraction grating 16. It is sufficient if the structure is held integrally and is configured separately from the subject table 13 and is not easily affected by vibrations and shocks generated from the subject table 13, and the shape and structure of the diffraction grating holding structure 17 are exemplified. It is not limited to things.
For example, as shown in FIG. 9, the diffraction grating holding structure 40 includes four columns 41 arranged so as not to interfere with the subject table 13, and the first diffraction grating 15 and the second diffraction grating are arranged by the columns 41. It is good also as a structure which hold | maintains 16 integrally.
Further, a filter 42 (Talborough filter) capable of obtaining characteristic X-rays having strong monochromaticity by removing the X-rays irradiated from the X-ray source 12 below the X-ray source 12 other than the X-rays having a specific wavelength. In this case, for example, the diffraction grating holding structure 40 is configured as shown in FIG. 9, and the filter 42 and the first diffraction grating are supported by the column 41 of the diffraction grating holding structure 17. 15 and the second diffraction grating 16 may be integrally held.

  In the present embodiment, X-ray imaging is performed a plurality of times while the first diffraction grating 15 is moved relative to the second diffraction grating 16, and differentiation is performed based on the X-ray image data obtained as a result. Although the case where a phase image or the like is generated has been described as an example, a differential phase image or the like may be generated based on X-ray image data obtained by one X-ray imaging.

<Second Embodiment>
A second embodiment of the X-ray imaging system according to the present invention will be described with reference to FIG.

This embodiment is a modification of the first embodiment, and is the same as the first embodiment except for the items described below.
As shown in FIG. 10, in the radiographic imaging apparatus 51 of this embodiment, a support base 53 is provided on a support base 52 fixed to the floor surface with bolts or the like. An imaging device main body 54 is supported on the support base 53 via a support shaft 55.

  The support base 53 is provided with a drive device 56 that drives the rotation of the support shaft 55, and the drive device 56 is provided with a known drive motor (not shown). The imaging device main body 54 rotates about the support shaft 55 as a rotation axis when the support shaft 55 is rotated in the CW direction and the CCW direction.

  An X-ray tube 57 that emits X-rays to the subject H is attached to the upper part of the imaging apparatus main body 54. A power supply unit 58 that supplies power is connected to the X-ray tube 57 via a support base 53, a support shaft 55, and an imaging apparatus main body 54. A diaphragm 59 for adjusting the X-ray irradiation field is provided at the X-ray emission port of the X-ray tube 57 so as to be freely opened and closed.

  A holding member 60 is fixed in the photographing apparatus main body 54 so as to extend in the vertical direction. A diffraction grating holding structure 61 is supported by the holding member 60 so as to be movable up and down with respect to the holding member 60 and to reduce shocks and vibrations. The position is adjusted by being moved up and down by a position adjusting device 62 having a drive motor or the like. The diffraction grating holding structure 61 is a structure that is configured separately from the subject table 13 and holds the first diffraction grating 66 and the second diffraction grating 67 together. That is, since the holding member 60 supports the diffraction grating holding structure 61 so as to mitigate shock and vibration, not only vibration / shock to the subject table 64 but also vibration caused by rotating the imaging apparatus main body 54. In addition, vibration generated in the photographing apparatus main body 54 is not transmitted to or mitigated by the diffraction grating holding structure 61 and the first diffraction grating 66 and the second diffraction grating 67 held thereby. .

  Note that, at a position between the X-ray tube 57 and the diffraction grating holding structure 61, a subject table 64 supported by a leg 63 fixed to the floor surface is held in a state substantially parallel to the floor surface. . The subject table 64 can support the subject H. That is, the subject table 64 is held by a structure different from the imaging apparatus main body 54 that holds the diffraction grating holding structure 61, and vibration / impact on the subject table 64 holds the diffraction grating holding structure 61 and the same. The first diffraction grating 66 and the second diffraction grating 67 are not transmitted or relaxed. In addition, a compression plate 65 that compresses and fixes the subject H from above is provided as necessary with the subject placed on the subject table 64. The movement of the compression plate 65 can be applied either automatically or manually.

Further, temperature sensors 66a and 67a for measuring the temperatures of the first diffraction grating 66 and the second diffraction grating 67 are measured at positions not photographed by X-rays.
Note that, for example, the first diffraction grating 66 and the second diffraction grating 67 have good thermal conductivity so that the temperatures of the first diffraction grating 66 and the second diffraction grating 67 are uniform in the respective planes and do not inhibit X-ray imaging. The first diffraction grating 66 and the second diffraction grating 67 are provided with Peltier elements or the like that can be attached to the two diffraction gratings 67 or can be heated and cooled by controlling the direction and magnitude of the current, for example. It is also possible to configure such that they can be heated and cooled.

Below the diffraction grating holding structure 61, a detector support base 69 that supports the X-ray detector 68 is supported so as to be movable up and down with respect to the holding member 60. The detector support base 69 is the position adjusting device described above. By 62, the position is adjusted by being lifted and lowered independently of the diffraction grating holding structure 61.
The X-ray detector 68 is supported on a detector support 69 so as to face the X-ray tube 57.

In FIG. 10, the X-ray detector 68 and the second diffraction grating 67 are expressed as having a certain distance Z ₂ between them in order to show that they are separate bodies. The X-ray detector 68 and the second diffraction grating 67 may be arranged in contact with each other, or the second diffraction grating 67 and the X-ray detector 68 are integrated. Also good.

1 is a side view showing a configuration example of a main part of a first embodiment of an X-ray imaging apparatus 1 constituting an X-ray imaging system according to the present invention. It is a block diagram which shows the control structure of an X-ray imaging system. FIG. 2 is a perspective sectional view of the diffraction grating holding structure of FIG. 1 and a first diffraction grating and a second diffraction grating held by the structure. It is a principal part perspective view explaining the X-ray transmission in the X-ray imaging apparatus 1 of FIG. It is II sectional drawing of FIG. 4 of a 1st diffraction grating. It is II-II sectional drawing of FIG. 4 of a 2nd diffraction grating. It is explanatory drawing explaining the positional relationship of the X-ray tube, a to-be-photographed object, a 1st diffraction grating, a 2nd diffraction grating, and an X-ray detector in the X-ray imaging apparatus 1 of FIG. It is a flowchart showing the flow of the X-ray imaging method performed with the X-ray imaging system of FIG. It is a side view which shows the principal part structure of the modification of the X-ray imaging apparatus 1 of FIG. It is a side view which shows the principal part structural example of 2nd Embodiment of the X-ray imaging apparatus 1 which comprises the X-ray imaging system in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 3 Console 11 Support base 12 X-ray irradiation apparatus 13 Subject stand 14 X-ray detector 15 First diffraction grating 16 Second diffraction grating 17 Diffraction grating holding structure 19 Buffer member (buffer means)
20 Actuator (drive means)
31 Control device (control means)
33 Display device 100 X-ray imaging system 122 X-ray tube 171 Buffer member (buffer means)
H Subject

Claims (7)

A subject table for placing the subject;
A first diffraction grating that produces a Talbot effect by diffracting X-rays transmitted through the object table;
A second diffraction grating for diffracting X-rays diffracted by the first diffraction grating;
An X-ray detector for detecting X-rays diffracted by the second diffraction grating;
A diffraction grating holding structure that integrally holds the first diffraction grating and the second diffraction grating,
An X-ray imaging system, wherein the diffraction grating holding structure and the subject table are separate structures.   2. The X-ray imaging system according to claim 1, further comprising buffer means for buffering force and vibration applied to the object table between the diffraction grating holding structure and the object table. An X-ray source for irradiating the X-ray detector through the first diffraction grating and the second diffraction grating to the X-ray detector;
The ratio of the interval between the X-ray source and the first diffraction grating and the grating period of the first diffraction grating is such that the X-ray detector can detect a phase difference image or moire fringes. The X-ray imaging system according to claim 1, wherein the X-ray imaging system is close to a ratio between an interval between the first diffraction grating and the second diffraction grating and a grating period of the second diffraction grating.   The X-ray source is an X-ray tube or a microfocus X-ray source in which a half-value width of a wavelength distribution of X-rays to be irradiated is not more than 1/4 times a peak wavelength of the X-rays. 3. The X-ray imaging system according to 3.   The X-ray imaging system according to claim 3, wherein a peak wavelength of X-rays irradiated by the X-ray source is 0.2 to 0.9 mm. At least one of the first diffraction grating and the second diffraction grating includes a diffraction member extending in one direction,
The diffraction grating holding structure holds at least one of the first diffraction grating and the second diffraction grating so as to be movable in a movable direction parallel to the diffraction grating surface and intersecting the extending direction of the diffraction member. And
6. The driving device according to claim 1, further comprising a driving unit that drives at least one of the movable first diffraction grating and the second diffraction grating in the movable direction. 7. X-ray imaging system. When the driving means is stopped and the X-ray detector is not reading an X-ray image, the X-ray source emits X-rays,
After the X-ray source stops X-ray irradiation, the X-ray detector starts reading an X-ray image, and the driving means drives at least one of the first diffraction grating and the second diffraction grating. Start
After the X-ray detector finishes reading the X-ray image and the driving means finishes driving at least one of the first diffraction grating and the second diffraction grating, the X-ray source emits X-rays. The X-ray imaging system according to claim 6, further comprising a control unit that controls the X-ray source, the X-ray detector, and the driving unit so as to irradiate.

Images