WO2013084657A1

WO2013084657A1 - Radiation imaging device

Info

Publication number: WO2013084657A1
Application number: PCT/JP2012/079004
Authority: WO
Inventors: 拓司多田; 温之橋本
Original assignee: 富士フイルム株式会社
Priority date: 2011-12-05
Filing date: 2012-11-08
Publication date: 2013-06-13
Also published as: JP2013138834A

Abstract

A radiation imaging device (1) is provided with a first support member (61) that supports the following: a first grid (31) that allows the passage of radiation from a radiation emission unit (11) and forms a first radiation image that includes a periodic intensity distribution; a second grid (32) that forms a second radiation image that includes a periodic intensity distribution generated by partially obscuring the first radiation image; and a radiation image detector (30) that detects the second radiation image and acquires image data. The first support member is disposed offset from a first extended region that extends in the array direction of a linear body (31b) of the first grid.

Description

Radiography equipment

The present invention relates to a radiation imaging apparatus.

X-rays are used as a probe for seeing through the inside of a subject because they have characteristics such as attenuation depending on the atomic numbers of elements constituting the substance and the density and thickness of the substance. X-ray imaging is widely used in fields such as medical diagnosis and non-destructive inspection.

In general X-ray imaging, a subject is placed between an X-ray source that emits X-rays and an X-ray image detector that detects an X-ray image, and a transmission image of the subject is captured. In this case, each X-ray radiated from the X-ray source toward the X-ray image detector has characteristics (atomic number, density, thickness) of the substance constituting the subject existing on the path to the X-ray image detector. ), The light is incident on the X-ray image detector. As a result, an X-ray transmission image of the subject is detected and imaged by the X-ray image detector. X-ray image detectors include a combination of an X-ray intensifying screen and film, a stimulable phosphor (accumulating phosphor), and a flat panel detector (FPD: Flat Panel Detector) using a semiconductor circuit. Widely used.

However, the X-ray absorptivity becomes lower as a substance composed of an element having a smaller atomic number, and the difference in the X-ray absorptivity is small in a soft tissue or soft material of a living body. There is a problem that (contrast) cannot be obtained. For example, most of the components of the cartilage part constituting the joint of the human body and the joint fluid in the vicinity thereof are water, and the difference in the amount of X-ray absorption between the two is small, so that it is difficult to obtain image contrast.

Against the background of such problems, in recent years, an X-ray phase for obtaining an image (hereinafter referred to as a phase contrast image) based on an X-ray phase change (angle change) by an object instead of an X-ray intensity change by an object. Imaging research is actively conducted. In general, it is known that when X-rays are incident on an object, the interaction is higher in phase than in X-ray intensity. For this reason, in X-ray phase imaging using a phase difference, it is possible to obtain a high-contrast image even for a weakly absorbing object having a low X-ray absorption ability, for example, an interphalangeal joint of a hand or a foot, an elbow joint, This is useful for visualizing the cartilage of joints such as knee joints.

As a kind of such X-ray phase imaging, in recent years, an X-ray imaging apparatus using an X-ray Talbot interferometer comprising two transmission diffraction gratings (phase type grating and absorption type grating) and an X-ray image detector has been proposed. It has been devised (for example, see Patent Documents 1 and 2).

In the X-ray Talbot interferometer, a first diffraction grating (phase type grating or absorption type grating) is arranged behind a subject, and a specific distance (Talbot interference distance) determined by the grating pitch of the first diffraction grating and the X-ray wavelength. The second diffraction grating (absorption type grating) is disposed only downstream, and the X-ray image detector is disposed behind the second diffraction grating. The Talbot interference distance is a distance at which X-rays that have passed through the first diffraction grating form a self-image (hereinafter referred to as a G1 image) that exhibits a periodic intensity distribution due to the Talbot interference effect. And modulated by the interaction (phase change) between the subject and the X-rays disposed between the X-ray source and the first diffraction grating.

In the X-ray Talbot interferometer, the moiré fringes generated by the superposition of the G1 image and the second diffraction grating are detected, and the phase of the subject is analyzed by analyzing the modulation of the periodic pattern appearing in the image corresponding to the moire fringes. Get information. For example, a fringe scanning method is known as a method for analyzing a periodic pattern appearing in an image. According to this fringe scanning method, the second diffraction grating is arranged with respect to the first diffraction grating in a direction substantially parallel to the plane of the first diffraction grating and substantially parallel to the grating pitch direction of the first diffraction grating. , Taking multiple shots while translating the grating pitch of the second diffraction grating at equal scan pitches, and refracting the subject from the change in the corresponding signal value for each pixel between the obtained multiple image data An X-ray angular distribution (phase shift differential image) is obtained, and a phase contrast image of the subject can be obtained based on the angular distribution.

International Publication No. 08/102598 International Publication No. 08/102685

The phase shift derivative obtained by the fringe scanning method is related to the grating pitch direction of the first diffraction grating, and the phase contrast image obtained based on this phase shift derivative includes an object that intersects the grating pitch direction. In particular, the edge of the subject substantially perpendicular to the lattice pitch direction is clearly depicted. That is, the arrangement of the subject is restricted by the grating pitch direction of the first diffraction grating. For example, in order to clearly depict a cartilage portion of a joint in phase contrast images of joints such as interphalangeal joints, elbow joints, and knee joints, it is necessary to arrange fingers, arms, and legs substantially along the lattice pitch direction.

Here, in the X-ray imaging apparatuses described in

Patent Documents

1 and 2, an X-ray source, a first diffraction grating, a second diffraction grating, a detector, and a subject table arranged in a vertical direction are provided by an arm member. It is a so-called vertical X-ray imaging apparatus that is supported, and the object table is disposed between the X-ray source and the first diffraction grating, or between the first diffraction grating and the second diffraction grating. Is done. The arm member is provided adjacent to the subject table in the direction of the grating pitch of the first diffraction grating. According to this configuration, a relatively long subject such as an arm or a leg can be placed on the grating pitch of the first diffraction grating. The arm member can become an obstacle when it is arranged along the direction.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a radiation imaging apparatus capable of appropriately arranging a subject and obtaining a clear phase contrast image.

(1) A first radiation image including a radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and including a periodic intensity distribution through the radiation emitted from the radiation irradiation unit. A second grating that forms a second radiation image including a periodic intensity distribution by partially shielding the first radiation image, and the second radiation image. A radiation image detector for detecting and acquiring image data; and the radiation irradiating unit, the first grating, the second grating, and the radiation image detector extending in an arrangement direction of the radiation irradiating unit, And a first support member that supports the first grating, the second grating, and the radiation image detector, wherein the first support member places the first grating in the arrangement direction of the linear bodies. An extended region, or an array of linear bodies of the second lattice Radiation imaging apparatus arranged out of the extended area extending in the direction.
(2) A radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and a radiation image including a periodic intensity distribution is formed by passing the radiation emitted from the radiation irradiation unit. 1 and a radiation image detector that detects the radiation image to acquire image data, the radiation irradiating unit, the first grating, and the radiation image detector extend in the arrangement direction of the radiation. An irradiation unit, a first grating, and a first support member that supports the radiation image detector, wherein the first support member extends the first grating in the arrangement direction of the linear bodies. A radiography apparatus arranged out of the extension area.

According to the present invention, when the subject is arranged along the arrangement direction of the linear body group of the first lattice, the first support member does not become an obstacle, and the subject is appropriately arranged to be clear. A phase contrast image can be obtained.

It is a schematic diagram which shows the structure of an example of the radiography apparatus for describing embodiment of this invention. It is a control block diagram of the radiography apparatus of FIG. It is a perspective view which shows the structure of the imaging | photography part of the radiography apparatus of FIG. It is a side view which shows the structure of the imaging | photography part of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the radiographic image detector contained in the imaging | photography part of FIG. It is a schematic diagram which shows the mechanism for changing the periodic pattern of the image acquired by the radiographic image detector of FIG. It is a schematic diagram for demonstrating the refraction | bending of the radiation by a to-be-photographed object. It is a schematic diagram for demonstrating an example of the production | generation method of the phase contrast image in the radiography apparatus of FIG. It is a schematic diagram for demonstrating the modification of the production | generation method of the phase contrast image of FIG. It is a graph which shows the signal waveform of the pixel of the image data obtained by the production | generation method of the phase contrast image of FIG. It is a schematic diagram for demonstrating the other example of the production | generation method of the phase contrast image in the radiography apparatus of FIG. It is a graph which shows the signal waveform of the pixel of the image data obtained by the production | generation method of the phase contrast image of FIG. FIG. 12 is a schematic diagram for explaining a modification of the method for generating the phase contrast image of FIG. 11. It is a schematic diagram for demonstrating the other modification of the production | generation method of the phase contrast image of FIG. It is a schematic diagram for demonstrating the other modification of the production | generation method of the phase contrast image of FIG. It is a schematic diagram for demonstrating the other example of the production | generation method of the phase contrast image in the radiography apparatus of FIG. It is a schematic diagram which shows arrangement | positioning of the supporting member of the radiography apparatus of FIG. 1 in relation to a 1st absorption type | mold grating | lattice. It is a schematic diagram which shows an example of the arrangement | positioning of the to-be-photographed object in the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram for demonstrating an example of the production | generation method of the phase contrast image in the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG. It is a schematic diagram for demonstrating an example of the production | generation method of the phase contrast image in the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG. It is a schematic diagram which shows the structure of the other example of the radiography apparatus for describing embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the radiography apparatus of FIG.

FIG. 1 shows a configuration of an example of a radiographic apparatus for explaining an embodiment of the present invention, and FIG. 2 shows a control block of the radiographic apparatus of FIG.

The X-ray imaging apparatus 1 is roughly divided into an X-ray imaging apparatus main body 2 and a console 3. The X-ray imaging apparatus body 2 includes an X-ray irradiation unit 11 that irradiates the subject H with X-rays, and an imaging unit that detects X-rays emitted from the X-ray irradiation unit 11 and transmitted through the subject H, and generates image data. 12. The console 3 controls the exposure operation of the X-ray irradiation unit 11 and the imaging operation of the imaging unit 12 of the X-ray imaging apparatus body 2 based on the operation of the operator, and calculates image data acquired by the imaging unit 12 Process to generate a phase contrast image.

The X-ray irradiation unit 11 and the imaging unit 12 are supported by a stand 13 installed on the floor. The stand 13 includes a base 60 fixed to the floor and an arm member 61 extending from the base 60 in the vertical direction (z direction in the illustrated example). The X-ray irradiation unit 11 is attached to the distal end portion of the arm member 61. The imaging unit 12 is disposed to face the X-ray irradiation unit 11 and is attached to a substantially central portion of the arm member 61.

The X-ray irradiation unit 11 includes an X-ray tube 18 as an X-ray source and a collimator unit 19. The X-ray tube 18 is of an anode rotating type, and is a filament (not shown) as an electron emission source (cathode) according to a high voltage applied from the high voltage generator 16 based on the control of the X-ray source control unit 17. X-rays are generated by emitting an electron beam from the motor and causing it to collide with the rotating anode 18a rotating at a predetermined speed. The colliding portion of the rotating anode 18a with the electron beam becomes the X-ray focal point 18b. The collimator unit 19 has a movable collimator 19 a that limits the irradiation field so as to shield a portion of the X-rays emitted from the X-ray tube 18 that does not contribute to the inspection area of the subject H.

The imaging unit 12 includes an X-ray image formed by a first absorption type grating 31 for detecting an X-ray phase change (angle change) caused by the subject H and an X-ray that has passed through the first absorption type grating 31. And a detection unit 14 that detects (hereinafter, this X-ray image is referred to as a G1 image). Although the details will be described later, the X-ray imaging apparatus 1 generates a phase contrast image using a fringe scanning method. The detection unit 14 includes a second absorption grating 32 superimposed on the G1 image, An X-ray image detector 30 that detects the G1 image on which the second absorption type grating 32 is superimposed, and a scanning mechanism 33 that translates the second absorption type grating 32 at a predetermined pitch are provided. The scanning mechanism 33 is configured by an actuator such as a piezoelectric element, for example.

In the illustrated example, the imaging unit 12 is configured as a unit in which the first absorption type grating 31 and the detection unit 14 (the second absorption type grating 32 and the X-ray image detector 30) are housed in one housing. Although attached to the arm member 61, the first absorption type grating 31, the second absorption type grating 32, and the X-ray image detector 30 are individually housed in appropriate housings, and individually. You may make it attach to the arm member 61. FIG. Further, the first absorption type grating 31, the second absorption type grating 32, and the X-ray image detector 30 may be appropriately combined to be unitized and attached to the arm member 61, for example, the first absorption type The mold grating 31 and the second absorption grating 32 may be unitized and attached to the arm member 61, and only the X-ray image detector 30 may be attached alone to the arm member 61, or the second absorption grating 32 may be attached. Alternatively, the X-ray image detector 30 may be unitized and attached to the arm member 61, and only the first absorption type grating 31 may be attached to the arm member 61 alone.

Further, the subject table 15 on which the subject H is placed is attached to the arm member 61 that supports the X-ray irradiation unit 11 and the imaging unit 12. The subject table 15 is disposed between the X-ray irradiation unit 11 and the imaging unit 12, more specifically, between the X-ray irradiation unit 11 and the first absorption grating 31.

The console 3 is provided with a control device 20 comprising a CPU, ROM, RAM and the like. The control device 20 includes an input device 21 through which an operator inputs an imaging instruction and the content of the instruction, an arithmetic processing unit 22 that performs arithmetic processing on the image data acquired by the imaging unit 12 and generates an X-ray image, and X A storage unit 23 for storing line images, a monitor 24 for displaying X-ray images and the like, and an interface (I / F) 25 connected to each unit of the X-ray imaging apparatus 1 are connected via a bus 26. .

As the input device 21, for example, a switch, a touch panel, a mouse, a keyboard, or the like can be used. By operating the input device 21, X-ray imaging conditions such as X-ray tube voltage and X-ray irradiation time, imaging timing, and the like. Is entered. The monitor 24 includes a liquid crystal display or the like, and displays characters such as X-ray imaging conditions and X-ray images under the control of the control device 20.

3 and 4 schematically show the configuration of the photographing unit 12.

The first absorption type grating 31 includes a substrate 31a and a plurality of X-ray shielding portions 31b (high radiation absorption portions) disposed on the substrate 31a. Similarly, the second absorption grating 32 includes a substrate 32a and a plurality of X-ray shielding portions 32b (high radiation absorption portions) arranged on the substrate 32a. The

substrates

31a and 32a are each formed of an X-ray transmissive member such as silicon, glass, resin, or the like that transmits X-rays.

The X-ray shielding part 31 b is configured by a linear member extending in one direction in a plane orthogonal to the optical axis C of the X-rays emitted from the X-ray irradiation part 11. As a material of each X-ray shielding part 31b, a material excellent in X-ray absorption is preferable, and for example, a heavy metal such as gold or platinum is preferable. These X-ray shielding portions 31b can be formed by a metal plating method or a vapor deposition method. Then, the X-ray shielding portion 31b is in a plane perpendicular to the optical axis C of the X-ray, the direction (hereinafter, x and direction) orthogonal to the one direction at a constant grating pitch p ₁ to each other a predetermined distance d ₁ is arranged with a gap.

The X-ray shielding part 32b is also composed of a linear member extending in one direction in a plane perpendicular to the optical axis C of the X-rays emitted from the X-ray irradiation part 11. As a material of each X-ray shielding part 32b, a material having excellent X-ray absorption such as heavy metals such as gold and platinum is preferable, and these X-ray shielding parts 32b can be formed by a metal plating method or a vapor deposition method. is there. Then, X-ray shielding portion 32b, in the plane orthogonal to the optical axis C of the X-ray, at a constant grating pitch p ₂ in the direction (x-direction) orthogonal to the one direction, at a predetermined interval d ₂ from each other Are arranged.

Since the first and

second absorption gratings

31 and 32 configured as described above do not give a phase difference to incident X-rays but give an intensity difference, they are also called amplitude gratings. The slit portions (low radiation absorbing portions) that are the regions of the distances d ₁ and d ₂ may not be voids. For example, the gaps may be filled with an X-ray low absorbing material such as a polymer or a light metal. Good.

The first and second

absorption type gratings

31 and 32 are configured to project the X-rays that have passed through the slit portion almost geometrically regardless of the presence or absence of the Talbot interference effect. More specifically, by setting the distances d ₁ and d ₂ to a value sufficiently larger than the effective wavelength of X-rays emitted from the X-ray irradiation unit 11, most of the irradiation X-rays are diffracted by the slits. Instead, a self-image of the first absorption type grating 31 can be formed behind the first absorption type grating 31. For example, when tungsten is used as the target of the radiation source and the tube voltage is 50 kV, the effective wavelength of X-ray is about 0.4 mm. In this case, if the distances d ₁ and d ₂ are set to about 1 to 10 μm, the radiation image formed by the radiation that has passed through the slit portion becomes such that the effect of diffraction can be ignored, and the first absorption grating 31 can be ignored. The self-image of the first absorption-type grating 31 is projected almost geometrically.

Since the X-ray radiated from the X-ray irradiation unit 11 is not a parallel beam but a cone beam with the X-ray focal point 18b as a light emitting point, the G1 image is enlarged in proportion to the distance from the X-ray focal point 18b. The The slits of the second absorption type grating 32 are determined so as to substantially match the pattern of the periodic intensity distribution of the G1 image at the position of the second absorption type grating 32. That is, when the distance from the X-ray focal point 18b to the first absorption grating 31 is L ₁ and the distance from the first absorption grating 31 to the second absorption grating 32 is L ₂ , the grating pitch p ₂ is determined so as to satisfy the relationship of the following formula (1).

In the Talbot interferometer, the distance L ₂ from the first absorption type grating 31 to the second absorption type grating 32 is limited to the Talbot interference distance determined by the grating pitch of the first diffraction grating and the X-ray wavelength. The X-ray imaging apparatus 1 has a configuration in which the influence of the incident X-ray diffraction by the first absorption type grating 31 is small, and the G1 image is obtained almost similarly behind the first absorption type grating 31. is therefore, the distance L _2, can be set independently of the Talbot distance.

Although the imaging unit 12 does not constitute a Talbot interferometer, the Talbot interference distance Z when it is assumed that X-rays are diffracted by the first absorption type grating 31 is the grating pitch p of the first absorption type grating 31. ₁ , using the grating pitch p _{2 of} the second absorption grating 32, the X-ray wavelength (effective wavelength) λ, and a positive integer m, the following expression (2).

Expression (2) is an expression representing the Talbot interference distance when the X-ray emitted from the X-ray irradiation unit 11 is a cone beam, “Timm 、 Weitkamp, et al., Proc. Of SPIE, Vol. 6318, It is known from “2006 63180S-1”.

In the present X-ray imaging apparatus 1, the imaging unit 12 is thinned by setting the distance L ₂ to a value shorter than the minimum Talbot interference distance Z when m = 1. That is, the distance L ₂ is set to a value in the range satisfying the following equation (3).

Incidentally, Talbot distance Z by the following equation (4) and in the case of X-rays emitted from the X-ray irradiation unit 11 can be regarded as substantially parallel beams, a distance L _2, the value of the range that satisfies the following equation (5) Set to.

However, the distance L ₂ does not necessarily satisfy the expressions (3) to (5), and deviates from the expressions (3) to (5), for example, when there is no request for thinning of the photographing unit 12. Range values can also be taken.

FIG. 5 schematically shows the configuration of the X-ray image detector 30.

The X-ray image detector 30 uses a flat panel detector (FPD: Flat Panel Detector) based on a thin film transistor (TFT: Thin Film Transistor) panel, and converts a plurality of pixels 40 by converting X-rays into electric charges. Are two-dimensionally arranged on the TFT active matrix substrate, a scanning circuit 42 for controlling the charge readout timing from the image receiver 41, the charges accumulated in each pixel 40 are read out, and the charges are converted into image data. And a data transmission circuit 44 that transmits the image data to the arithmetic processing unit 22 via the I / F 25 of the console 3. The scanning circuit 42 and each pixel 40 are connected by a scanning line 45 for each row, and the readout circuit 43 and each pixel 40 are connected by a signal line 46 for each column.

Each pixel 40 is a direct conversion type in which X-rays are directly converted into electric charges by a conversion layer (not shown) such as amorphous selenium and the converted electric charges are stored in a capacitor (not shown) connected to the lower electrode. The X-ray detection element can be configured. A TFT switch (not shown) is connected to each pixel 40, and the gate electrode of the TFT switch is connected to the scanning line 45, the source electrode is connected to the capacitor, and the drain electrode is connected to the signal line 46. When the TFT switch is turned on by the drive pulse from the scanning circuit 42, the charge accumulated in the capacitor is read out to the signal line 46.

Each pixel 40 can also be configured as an indirect conversion type X-ray detection element that uses a scintillator that converts X-rays into visible light, and converts visible light converted by the scintillator into electric charge and accumulates it. It is. Examples of the phosphor forming the scintillator include terbium activated gadolinium oxide (Gd ₂ O ₂ S: Tb) and thallium activated cesium iodide (CsI: Tl). The X-ray image detector is not limited to an FPD based on a TFT panel, and various X-ray image detectors based on a solid-state imaging device such as a CCD sensor or a CMOS sensor can also be used.

The readout circuit 43 includes an integration amplifier circuit, an A / D converter, a correction circuit, and an image memory. The integrating amplifier circuit integrates the charges output from each pixel 40 via the signal line 46, converts them into a voltage signal (image signal), and inputs it to the A / D converter. The A / D converter converts the input image signal into digital image data and inputs the digital image data to the correction circuit. The correction circuit performs offset correction, gain correction, and linearity correction on the image data, and stores the corrected image data in the image memory. As correction processing by the correction circuit, correction of X-ray exposure amount and exposure distribution (so-called shading) and pattern noise (for example, TFT) depending on the control conditions (drive frequency and readout period) of the X-ray image detector 30 are performed. Correction of the leak signal of the switch) may be included.

The X-ray image detector 30 is arranged so that its image receiving surface is orthogonal to the optical axis C of X-rays. Typically, the row direction or the column direction in the array of the pixels 40 of the image receiving unit 41 is the first. The one absorption type grating 31 is arranged so as to be parallel to the grating pitch direction (x direction).

In the imaging unit 12 configured as described above, a G1 image exhibiting a periodic intensity distribution reflecting the lattice structure of the first absorption type grating 31 is formed by the X-rays that have passed through the first absorption type grating 31. The The G1 image is intensity-modulated by being superimposed on the second absorption grating 32, and the intensity-modulated G1 image is captured by the X-ray image detector 30. The pattern period p ₁ ′ of the periodic intensity distribution of the G1 image at the position of the second absorption type grating 32 and the substantial grating pitch p ₂ ′ of the second absorption type grating 32 (substantial pitch after manufacture) Is slightly different due to manufacturing errors and placement errors. Among these, the arrangement error means that the substantial pitch in the x direction changes due to the relative inclination and rotation of the first and

second absorption gratings

31 and 32 and the distance between the two changes. I mean.

Due to the minute difference between the pattern period p ₁ ′ of the G1 image and the grating pitch p ₂ ′ of the second absorption type grating 32, the image contrast on the X-ray image detector 30 includes moire fringes. The period T in the x direction of the moire fringes is expressed by the following equation (6), where L is the distance from the X-ray focal point 18b to the X-ray image detector 30.

In order to detect the moire fringes with the X-ray image detector 30, the arrangement pitch P of the pixels 40 in the x direction needs to be at least not an integral multiple of the moire period T, and the following equation (7) needs to be satisfied. (Where n is a positive integer).

Further, it is possible to detect moire fringes even if the arrangement pitch P is larger than the moire period T within the range satisfying the expression (7), but the arrangement pitch P is preferably smaller than the moire period T. It is preferable to satisfy 8). This is because, in order to obtain a high-quality phase contrast image, moire fringes are preferably detected with high contrast in the phase contrast image generation process described later.

Since the arrangement pitch P of the pixels 40 is a value determined in terms of design (generally about 100 μm) and is difficult to change, the magnitude relationship between the arrangement pitch P of the pixels 40 and the period T of moire fringes is shown. For the adjustment, the positions of the first and

second absorption gratings

31 and 32 are adjusted, and at least one of the pattern period p ₁ ′ of the G1 image and the grating pitch p ₂ ′ of the second absorption grating 32 is set. It is preferable to change the period T of moire fringes by changing one.

FIG. 6 schematically shows a method of changing the period T of moire fringes.

The change of the moire fringe period T can be performed by relatively rotating one of the first and

second absorption gratings

31 and 32 about the optical axis C. For example, a relative rotation mechanism 50 that rotates the second absorption grating 32 relative to the first absorption grating 31 relative to the optical axis C is provided. When the second absorption type grating 32 is rotated by the angle θ by the relative rotation mechanism 50, the substantial grating pitch in the x direction of the second absorption type grating 32 is changed from “p ₂ ′” → “p ₂ ′”. / Cos θ ”, and as a result, the period T of moire fringes changes (FIG. 6A).

As another example, the change in the period T of the moire fringes is performed by centering one of the first and

second absorption gratings

31 and 32 on an axis perpendicular to the optical axis C and along the y direction. This can be done by relatively inclining. For example, a relative inclination mechanism 51 that inclines the second absorption type grating 32 relative to the first absorption type grating 31 about the axis in the direction orthogonal to the optical axis C and along the y direction. Provide. When the second absorption type grating 32 is inclined by the angle α by the relative inclination mechanism 51, the substantial lattice pitch in the x direction of the second absorption type grating 32 is changed from “p ₂ ′” → “p ₂ ′”. X cos α ”, and as a result, the period T of moire fringes changes (FIG. 6B).

As another example, the period T of the moire fringes can be changed by relatively moving one of the first and

second absorption gratings

31 and 32 along the direction of the optical axis C. it can. For example, with respect to the first absorption type grating 31, the second absorption type grating 32 is changed so as to change the distance L ₂ between the first absorption type grating 31 and the second absorption type grating 32. A relative movement mechanism 52 that relatively moves along the direction of the optical axis C is provided. When the second absorption type grating 32 is moved by the movement amount δ to the optical axis C by the relative movement mechanism 52, the G1 image of the first absorption type grating 31 projected on the position of the second absorption type grating 32. The pattern period of “p ₁ ′” → “p ₁ ′ × (L ₁ + L ₂ + δ) / (L ₁ + L ₂ )” changes, and as a result, the period T of moire fringes changes (FIG. 6C). ).

In the present X-ray imaging apparatus 1, the imaging unit 12 does not constitute a Talbot interferometer as described above, and therefore the distance L ₂ can be freely set. Therefore, the distance L as in the relative movement mechanism 52. A mechanism for changing the period T of moire fringes by changing ₂ can be suitably employed. The change mechanism (relative rotation mechanism 50, relative tilt mechanism 51, and relative movement mechanism 52) of the first and

second absorption gratings

31 and 32 for changing the period T of the moiré fringes is a piezoelectric element or the like. It can be configured by an actuator.

When the subject H is arranged on the subject table 15 arranged between the X-ray irradiation unit 11 and the first absorption type grating 31, the periodic intensity distribution of the G1 image is modulated by the subject H, and the G1 image And the moire fringes due to the superposition of the second absorption type grating 32 are also modulated. This modulation amount is proportional to the angle of the X-ray deflected by the refraction effect by the subject H. The image acquired by the X-ray image detector 30 includes a periodic pattern corresponding to moire fringes, and a phase contrast image of the subject H can be generated by analyzing the image including the periodic pattern. .

Hereinafter, an image analysis method will be described.

[Analysis method 1]
FIG. 7 shows one X-ray refracted according to the phase shift distribution Φ (x) of the subject H in the x direction.

Reference numeral 55 indicates an X-ray path that goes straight when the subject H does not exist. The X-ray that travels along the path 55 passes through the first and

second absorption gratings

31 and 32 and is an X-ray image. The light enters the detector 30. Reference numeral 56 indicates an X-ray path refracted and deflected by the subject H when the subject H exists. X-rays traveling along this path 56 are shielded by the second absorption type grating 32 after passing through the first absorption type grating 31.

The phase shift distribution Φ (x) of the subject H is expressed by the following formula (9), where n (x, z) is the refractive index distribution of the subject H and z is the direction in which the X-ray travels.

The G1 image projected from the first absorptive grating 31 to the position of the second absorptive grating 32 is displaced in the x direction by an amount corresponding to the refraction angle φ due to refraction of X-rays at the subject H. become. This displacement amount Δx is approximately expressed by the following equation (10) based on the fact that the refraction angle φ of X-rays is very small.

Here, the refraction angle φ is expressed by Expression (11) using the X-ray wavelength λ and the phase shift distribution Φ (x) of the subject H.

Thus, the displacement amount Δx of the G1 image due to the refraction of X-rays at the subject H is related to the phase shift distribution Φ (x) of the subject H. This displacement amount Δx is related to the phase shift amount ψ of the signal of each pixel of the image data (the signal phase difference between when the subject H is present and when it is not present) as shown in the following equation (12). Yes.

Accordingly, by obtaining the phase shift amount ψ of the signal of each pixel, the refraction angle φ is obtained from the equation (12), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (11). By integrating with respect to x, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H can be generated. In the X-ray imaging apparatus 1, the phase shift amount ψ is calculated using a fringe scanning method described below.

In the fringe scanning method, one of the first and second absorption-

type gratings

31 and 32 is translated in a stepwise manner within the plane where the grating is positioned, and the second is applied to the periodic intensity distribution of the G1 image. The imaging is performed while changing the phase of the periodic arrangement of the X-ray shielding portions 32b of the absorption type grating 32. In the present X-ray imaging apparatus 1, the second absorption type grating 32 is moved by the scanning mechanism 33 (see FIG. 1), but the first absorption type grating 31 may be moved.

Moire fringes move with the movement of the second absorption grating 32, and the translational distance in the grating pitch direction of the second absorption grating 32 is one period of the grating pitch of the second absorption grating 32 (the grating pitch). When p ₂ ) is reached (ie when the phase change reaches 2π), the moire fringes return to their original positions. Such a change in moire fringes is captured by the X-ray image detector 30 while moving the second absorption grating 32, and a plurality of signal values are obtained for each pixel from the obtained plurality of image data. A phase shift amount ψ of the signal of each pixel is obtained by performing arithmetic processing in the arithmetic processing unit 22.

In FIG. 8, the second absorption type grating 32 is moved in the grating pitch direction (x direction) by the scanning pitch (p ₂ / M) obtained by dividing the grating pitch p ₂ into M (integer of 2 or more). A state is shown typically.

The scanning mechanism 33 translates the second absorption type grating 32 in order to M scanning positions of k = 0, 1, 2,..., M−1. In the same figure, the initial position of the second absorption grating 32 is the same as the dark part of the G1 image at the position of the second absorption grating 32 when the subject H is not present. The initial position is k = 0, 1, 2,..., M−1.

First, at the position of k = 0, X-rays that are not refracted by the subject H mainly pass through the second absorption type grating 32. Next, when the second absorption grating 32 is moved in order of k = 1, 2,..., The X-rays passing through the second absorption grating 32 are not refracted by the subject H. While the line component decreases, the X-ray component refracted by the subject H increases. In particular, at k = M / 2, mainly only the X-rays refracted by the subject H pass through the second absorption type grating 32. When k = M / 2 is exceeded, on the contrary, the X-ray component that is refracted by the subject H decreases in the X-rays that pass through the second absorption grating 32, while the X-ray that is not refracted by the subject H. The line component increases. When images are taken by the X-ray image detector 30 at each position of k = 0, 1, 2,..., M−1, M signal values are obtained for each pixel.

In the example shown in FIG. 8, the second absorption grating 32 has been described as being moved in the grating pitch direction (x direction). However, as long as displacement in the grating pitch direction is involved, the second absorption grating 32 is shown in FIG. As described above, the second absorption type grating 32 may be moved in a direction intersecting with the grating pitch direction (x direction). By moving the second absorption type grating 32 in a direction crossing the grating pitch direction, the translation distance along the scanning direction until the translation distance in the grating pitch direction reaches the grating pitch p ₂ is equal to the grating pitch p. _Greater than ₂ . Therefore, the scanning pitch obtained by dividing the translation distance along the scanning direction into M pieces is also increased, and resistance to movement errors of the second absorption type grating 32 is increased. The refraction of the X-ray generated by passing through the subject H is only a few μrad, and the modulation of the moire fringe caused by this refraction and the phase change of the signal obtained by analyzing the moire fringe by the above-described fringe scanning method are also slight. is there. In the case of measuring such a slight change, it is possible to improve the detection accuracy of the phase information of the subject H by increasing the resistance against the movement error of the second absorption grating 32.

Hereinafter, a method of calculating the phase shift amount ψ of the signal of each pixel from the M signal values will be described.

When the signal value of each pixel when the second absorption type grating 32 is at the position k is I _k (x), I _k (x) is expressed by the following equation (13).

Here, x is a coordinate in the x direction of each pixel, A ₀ is the intensity of the incident X-ray, and _An is a value corresponding to the contrast of the signal (where n is a positive integer). ). Φ (x) represents the refraction angle φ as a function of the pixel coordinate x.

Next, using the relational expression of the following expression (14), the refraction angle φ (x) is expressed as the following expression (15).

Here, arg [] means extraction of the declination, and corresponds to the phase shift amount ψ of the signal of each pixel. Therefore, the refraction angle φ (x) is obtained by calculating the phase shift amount ψ of the signal of each pixel from the M signal values obtained for each pixel based on the equation (15).

FIG. 10 shows the signal waveform of one pixel that changes with the fringe scanning.

The M signal values obtained for each pixel periodically change with the period of the grating pitch p _{2 with} respect to the position k of the second absorption type grating 32. A broken line in FIG. 10 indicates a signal waveform when the subject H does not exist, and a solid line in FIG. 10 indicates a signal waveform when the subject H exists. The phase difference between the two waveforms corresponds to the phase shift amount ψ of the signal of each pixel.

Since the refraction angle φ (x) corresponds to the differentiation of the phase shift distribution Φ (x) as shown in the above equation (11), the refraction angle φ (x) is integrated along the x axis. A phase shift distribution Φ (x) is obtained. In the above description, the y-coordinate regarding the y-direction of the pixel is not taken into consideration. However, by performing the same calculation for each y-coordinate, a two-dimensional phase shift distribution Φ (x, y) is obtained. The above calculation is performed by the calculation processing unit 22, and the calculation processing unit 22 stores the phase shift distribution Φ (x, y) in the storage unit 23 as a phase contrast image.

[Analysis method 2]
FIG. 11 shows another example of a method for generating a phase contrast image in the X-ray imaging apparatus 1.

In the method described below, a plurality of pixels arranged in a direction intersecting with the moire fringe are analyzed as a unit, and the phase shift amount ψ of the signal of each pixel is calculated from one image data.

In the example shown in FIG. 11, the first and second

absorption type gratings

31 and 32 are arranged so as to be relatively rotated by an angle θ about the optical axis C, and the G1 image and the second absorption type grating are arranged. 32 is relatively rotated by an angle θ, and moire fringes having periodicity in the y direction are generated. Therefore, the analysis is performed with a plurality of pixels arranged in the y direction intersecting the moire fringes as one unit U. In the example shown in FIG. 11, five pixels arranged in the y direction are defined as one unit U.

As described above, the G1 image is displaced in the x direction by an amount corresponding to the refraction angle φ due to the refraction of X-rays at the subject H, and the moire fringes are displaced in the y direction as the G1 image is displaced in the x direction. Will do. As shown in FIG. 12, with the displacement of the moire fringes, the phase of the signal waveform obtained by interpolating the signal value of the pixel group constituting the unit changes for each unit. The phase difference between the waveform of the signal waveform (FIG. 12A) when the subject H is not present and the signal waveform (FIG. 12B) when the subject H is present is the phase of the pixel signal included in the unit. This corresponds to the displacement amount ψ.

Then, the phase shift amount ψ of the signal of each pixel can be obtained by performing the above analysis for each unit while shifting the unit of the pixel group to be analyzed, for example, by one pixel in the y direction. That is, the phase shift amount ψ of the k-th pixel 40 of the signal at the row of the y direction of pixels 40, the signal value of the k-th pixel 40 as _{_{_{_{I k, [I k, I}}}} k + 1, I k + 2, I k + 3, 5 signal values of I _{k + 4} ] and 5 signal values of [I _{k + 1} , I _{k + 2} , I _{k + 3} , I _{k + 4} , I _{k + 5} ] are used as the phase shift amount ψ of the signal of the (k + 1) th pixel 40. Can be obtained respectively. Note that the above analysis can be performed for each unit while shifting the unit of the pixel group by a plurality of pixels in the y direction within a range of 5 pixels or less as one unit. For example, assuming that each pixel is shifted by two pixels, the phase shift amount ψ of the signal of each of the kth and k + 1th pixels 40 uses five signal values of [I _k , I _{k + 1} , I _{k + 2} , I _{k + 3} , I _{k + 4} ]. , K + 2 and k + 3 pixels 40 can be obtained by using five signal values of [I _{k + 2} , I _{k + 3} , I _{k + 4} , I _{k + 5} , I _{k + 6} ]. .

The refraction angle φ is obtained from the phase shift amount ψ of the signal of each pixel using the equation (12), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (11), and this is integrated with respect to x. Thus, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H is generated.

It should be noted that the above analysis is possible if the moire fringes are resolved with 3 pixels or more arranged in the y direction as a unit. Therefore, the relationship to be satisfied between the moire period T in the y direction and the pitch P of the pixels 40 in the y direction is expressed by the following expression (16) when the G1 image is rotated, and the second absorption type grating 32 is rotated. Is given by the following equation (17).

Note that the number of pixels as a unit is preferably the number of pixels over which at least one period of the moire period T in the y direction is arranged. Here, when the moire period T in the y direction is set to be approximately M times the arrangement pitch P of the pixels 40 in the y direction (M is an integer), and the M pixels 40 are taken as one unit, the pixel 40 The signal values of the k-th pixel 40 in the y-direction array are I _k , and the M signal values of I _k to I _{k + M−1} are the first and second absorption gratings 31 in the fringe scanning method described above. , 32 is equivalent to M signal values acquired for the kth pixel 40 when the grid pitch is moved in the grid pitch direction at a scan pitch obtained by dividing the grid pitch into M pieces. .

FIG. 13 shows a modification of the analysis method of FIG.

In the example shown in FIG. 13, the grating pitch p _{2 of} the second absorption type grating 32 is different from the pitch p ₁ ′ of the G1 image, and moire fringes having periodicity in the x direction are generated. In order to make the grating pitch p _{2 of} the second absorption grating 32 different from the pitch p ₁ ′ of the G1 image, for example, one of the first and

second absorption gratings

31 and 32 is placed in the direction of the optical axis C. May be moved relative to each other, or the grating pitch of each of the first and

second absorption gratings

31 and 32 may be adjusted.

Then, the above analysis is performed with a plurality of pixels arranged in the x direction intersecting the moire fringes as one unit U. In the example shown in FIG. 13, four pixels arranged in the x direction are set as one unit U. However, in this example, if the moire fringes are resolved using three or more pixels arranged in the x direction as one unit, the above analysis is performed. The relationship to be satisfied between the period T of moire fringes in the x direction and the pitch P of the pixels 40 in the x direction is expressed by the following equation (18).

FIG. 14 shows another modification of the analysis method of FIG.

In the example shown in FIG. 14, the grating pitch p ₂ of the second absorption grating 32 is different from the pitch p ₁ ′ of the G1 image, and the second absorption grating 32 rotates relative to the G1 image. Moire fringes having periodicity are generated in the direction intersecting the x direction and the y direction.

As described above, if the moire fringe is resolved with three or more pixels arranged in the direction intersecting the moire fringe as a unit, the phase shift amount ψ of the signal of the pixel included in the unit is calculated for each unit. Therefore, in this example, the analysis can be performed with a plurality of pixels of 3 pixels or more arranged in the x direction as one unit U (FIG. 14A), or a plurality of pixels of 3 pixels or more arranged in the y direction can be analyzed. Analysis can also be performed as one unit U (FIG. 14B).

FIG. 15 shows another modification of the analysis method of FIG.

In the example shown in FIG. 11, the pattern period direction (x direction) of the periodic intensity distribution of the G1 image and the row direction or the column direction in the array of the pixels 40 in the X-ray image detector 30 match. In the example shown in FIG. 15, the first absorption type grating 31 and the X-ray image detector 30 are arranged so as to rotate relative to each other about the optical axis C, so that the periodic intensity distribution of the G1 image is obtained. Both the row direction and the column direction in the array of the pixels 40 intersect with the pattern periodic direction (x direction). Also in this case, as described above, if the moire fringe is resolved with a plurality of pixels of three or more pixels arranged in the direction intersecting the moire fringe as one unit U, the pixels included in the unit are determined for each unit. The amount of phase shift ψ of the signal can be calculated.

According to the analysis method 2 described above, a phase contrast image can be generated from one periodic pattern image, and thus only one imaging is required. Therefore, the first absorption type grating 31 or the second between multiple imagings. Therefore, the movement of the absorption type grating 32 and the scanning mechanism 33 that requires high accuracy are not required. Therefore, it is possible to improve the shooting workflow and simplify the apparatus. In addition, it is possible to eliminate the deterioration in image quality caused by the movement of the subject between each photographing.

[Analysis method 3]
FIG. 16 shows another example of a method for generating a phase contrast image in the X-ray imaging apparatus 1.

In the method described below, a periodic pattern of an image is analyzed using Fourier transform and inverse Fourier transform to generate a phase contrast image.

The periodic pattern of the image corresponding to the moire fringes formed by superimposing the G1 image and the second absorption type grating 32 can be expressed by the following equation (19), and the equation (19) is expressed by the following equation (20). Can be rewritten.

In Expression (19), a (x, y) represents the background, b (x, y) represents the amplitude of the spatial frequency component corresponding to the basic period of the periodic pattern, and (f _0x, f _0y ) represents the period. Represents the basic period of the pattern. In the formula (20), c (x, y) is represented by the following formula (21).

Therefore, information on the refraction angle φ (x, y) can be obtained by extracting the component of c (x, y) or c ^* (x, y). Here, equation (20) becomes the following equation (22) by Fourier transform.

In the formula _{_{_{(22), F (f x}}} , f y), A (f x, f y), C (f x, f y) , respectively f (x, y), a (x, y), c It is a two-dimensional Fourier transform for (x, y).

When one-dimensional gratings such as the first and

second absorption gratings

31 and 32 are used, the spatial frequency spectrum of the image has at least A (f _x , f _y ) as shown in FIG. a peak derived _{from, C (f x, f y} ) and ^{_{C * (f x, f y}} ) 3 peaks and the peak of the spatial frequency component corresponding to the fundamental period of the periodic pattern from the results across this . A _{_(f} x, f _y) peak derived from the origin, _{_{also, C (f x, f y}} ) and ^{_{_{C * (f x, f y}}} ) peak derived from the _{_{(± f 0x, ± f 0y}} ) It occurs at the position of (combined same order).

In order to obtain the refraction angle φ (x, y) from the spatial frequency spectrum of the image, a region including the peak frequency of the spatial frequency component corresponding to the basic period of the periodic pattern is cut out so that the peak frequency overlaps the origin of the frequency space. Move the clipped area and perform inverse Fourier transform. Then, the refraction angle φ (x, y) can be obtained from the complex number information obtained by the inverse Fourier transform. The method for generating the phase contrast image from the refraction angle φ (x, y) is the same as the above-described fringe scanning method.

According to the analysis method 3 described above, a phase contrast image can be generated from one periodic pattern image, and thus only one imaging is required. Therefore, the first absorption type grating 31 or the second between multiple imagings. Therefore, the movement of the absorption type grating 32 and the scanning mechanism 33 that requires high accuracy are not required. Therefore, it is possible to improve the shooting workflow and simplify the apparatus. In addition, it is possible to eliminate the deterioration in image quality caused by the movement of the subject between each photographing.

According to the analysis methods 1 to 3 described above, the refraction angle φ with respect to the x direction which is the lattice pitch direction of the first absorption type grating 31, that is, the differential of the phase shift distribution Φ is obtained, and the differential of the phase shift distribution Φ is obtained. In the phase contrast image obtained based on the above, the edge of the subject H that intersects the grating pitch direction of the first absorption type grating 31 is depicted, and in particular, substantially perpendicular to the grating pitch direction of the first absorption type grating 31. The edge of the subject H is clearly depicted. That is, the arrangement of the subject H is restricted by the lattice pitch direction of the first absorption-type lattice 31.

FIG. 17 shows the arrangement of the arm member 61 in relation to the first absorption type lattice 31.

As described above, the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15 are all supported by the arm member 61 of the stand 13, and X-ray irradiation is performed from above in the vertical direction (z direction) in which the arm member 61 extends. The unit 11, the subject table 15, and the imaging unit 12 are arranged in this order.

The imaging unit 12 having the first absorption type grating 31 is arranged so that the edge in the extending direction (y direction) of the X-ray shielding part 31 b of the first absorption type grating 31 follows the arm member 61. It is attached to the member 61. The arm member 61 places the first absorption grating 31 in the grating pitch direction (x in the plane A including the placement surface of the subject table 15 on which the subject H is placed, that is, the plane A extending to the arrangement position of the subject H. Area A1 that extends in the vertical direction and the area A1 that extends in the vertical direction, and that overlaps the area a2 in which the first absorption grating 31 extends in the extending direction (y direction) of the X-ray shielding portion 31b in the vertical direction. It extends in the vertical direction through A2. In other words, the arm member 61 deviates from a region where the mounting surface of the subject table 15 is extended in the lattice pitch direction (x direction) of the first absorption type grating 31, and the mounting surface of the subject table 15 is moved to the first surface. The absorption grating 31 extends in the vertical direction through a region extending in the extending direction (y direction) of the X-ray shielding portion 31b. In other words, since the grating pitch direction of the first absorption type grating 31 and the grating pitch direction of the second absorption type grating 32 substantially coincide with each other, the arm member 61 has the mounting surface of the subject table 15. Is removed from the region extending in the lattice pitch direction of the second absorption type grating 32, and passes through the region where the mounting surface of the subject table 15 is extended in the extending direction of the X-ray shielding portion 32 b of the second absorption type grating 32. Extending in the vertical direction.

FIG. 18 shows an example of the arrangement of the subject H.

In the X-ray imaging apparatus 1 configured as described above, the arm member 61 is not positioned at the tip of the subject table 15 with respect to the grating pitch direction (x direction) of the first absorption grating 31. Therefore, a relatively long subject H such as an arm or a leg can be arranged along the lattice pitch direction of the first absorption type lattice 31. Thus, for example, in the imaging of the knee joint shown in FIG. 18, the boundary between the joint fluid filling the joint space and the cartilage covering each of the femur B1 and the tibia B2 constituting the knee joint is the first absorption. Arranged so as to be substantially orthogonal to the lattice pitch direction (x direction) of the mold lattice 31, the edge of the cartilage is clearly depicted in the phase contrast image.

Further, the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15 are supported by the arm member 61 in a cantilever shape, and the arm member 61 is disposed so as to pass through the above-described region A2. The arm member 61 extending out of the area A1 and extending in the vertical direction can be disposed close to the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15. Thereby, the beam length can be shortened, and the tilt and vibration of the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15 can be prevented or suppressed. The refraction of the X-ray generated by passing through the subject H is only a few μrad, and the modulation of the moire fringe caused by this refraction and the phase change of the signal obtained by analyzing the moire fringe by the above-described fringe scanning method are also slight. is there. When such a slight change is measured, the relative position shift of the X-ray focal point 18b and the first and

second absorption gratings

31 and 32 affects the detection accuracy of the phase information of the subject H. By preventing or suppressing the tilt or vibration of the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15, the relative position of the X-ray focal point 18 b and the first and

second absorption gratings

31 and 32 can be prevented from shifting. Therefore, the detection accuracy of the phase information of the subject H can be increased.

Further, from the viewpoint of preventing or suppressing the displacement of the relative positions of the X-ray focal point 18b and the first and second

absorption type gratings

31 and 32, the subject table 15 absorbs or relaxes shocks, vibrations, and the like. It is attached to the arm member 61 via FIG. Accordingly, it is possible to prevent or suppress an impact when the subject H is placed on the subject table 15, vibration due to a movement (body movement) of the subject H during or during photographing, and the like, from being transmitted to the arm member 61. be able to. Thereby, as described above, the relative position shift of the X-ray focal point 18b and the first and

second absorption gratings

31 and 32 can be prevented or suppressed, and the detection accuracy of the phase information of the subject H can be improved. it can. As a material of the buffer member 15a, for example, hard rubber or various resins can be applied, but the material of the buffer member 15a is not limited thereto.

As described above, according to the X-ray imaging apparatus 1, when the subject H is arranged along the grating pitch direction of the first absorption type grating 31, the arm member 61 is not obstructed and the subject H is appropriately arranged. Thus, a clear phase contrast image can be obtained.

In addition, since most X-rays are not diffracted by the first absorption type grating 31 and are projected almost geometrically onto the second absorption type grating 32, the irradiated X-rays have high spatial coherence. It is not required and a general X-ray source used in the medical field can be used. The distance L ₂ from the first absorption type grating 31 to the second absorption type grating 32 can be set to an arbitrary value, and the distance L ₂ is set smaller than the minimum Talbot interference distance in the Talbot interferometer. Therefore, the photographing unit 12 can be downsized (thinned).

It is assumed that the second grating is superimposed on the projected image of the first grating to generate moire fringes, and therefore the first and second gratings are both absorption type gratings. However, the present invention is not limited to this. As described above, the present invention is also useful when the Moire fringes are generated by superimposing the second grating on the Talbot interference image. Therefore, the first grating is not limited to the absorption type grating but may be a phase type grating. When the first grating is a 0.5π phase grating, the Talbot interference distance Z is expressed by the following expression (23), and the pattern period p ₁ ′ of the Talbot interference image is expressed by the following expression (24). The When the first grating is a π phase grating, the Talbot interference distance Z is expressed by the following expression (25), and the pattern period p ₁ ′ of the Talbot interference image is expressed by the following expression (26). The

In addition, although the image obtained by imaging the phase shift distribution Φ is described as being stored or displayed as a phase contrast image, the phase shift distribution Φ is obtained by integrating the differential amount of the phase shift distribution Φ obtained from the refraction angle φ. Thus, the differential amount of the refraction angle φ and the phase shift distribution Φ is also related to the X-ray phase change by the subject. Therefore, an image of the refraction angle φ and an image of the differential amount of the phase shift are also included in the phase contrast image.

Further, the above-described phase contrast image generation processing may be performed on the moire fringes obtained by photographing (pre-photographing) in the absence of a subject, and the phase contrast image may be obtained. This phase contrast image reflects, for example, phase unevenness (initial phase shift) caused by non-uniformity of the first and

second absorption gratings

31 and 32. By subtracting the phase contrast image in the pre-photographing from the phase contrast image obtained by photographing (main photographing) in the presence of the subject, a phase contrast image in which the phase unevenness of the photographing unit 12 is corrected can be obtained. .

FIG. 19 shows a configuration of a modified example of the X-ray imaging apparatus 1.

19 differs from the X-ray imaging apparatus 1 shown in FIG. 1 in that the multi-slit 35 is disposed in the X-ray irradiation unit 11.

In the X-ray imaging apparatus 1 described above, when the distance from the X-ray irradiation unit 11 to the X-ray image detector 30 is set to a distance (1 m to 2 m) as set in a general hospital imaging room, The blur of the G1 image due to the focal size of the X-ray focal point 18b (generally about 0.1 mm to 1 mm) is affected, and there is a possibility that the image quality of the phase contrast image is degraded. Therefore, it is conceivable to install a pinhole immediately after the X-ray focal point 18b to effectively reduce the focal spot size. However, if the aperture area of the pinhole is reduced to reduce the effective focal spot size, the X-ray focal point is reduced. Strength will fall. In this example, in order to solve this problem, the multi slit 35 is disposed immediately after the X-ray focal point 18b.

The multi slit 35 is an absorption type grating (third absorption type grating) having the same configuration as that of the first and second

absorption type gratings

31 and 32, and a plurality of X-ray shielding portions extending in one direction are provided in the first slit. The first and second

absorption type gratings

31 and 32 are periodically arranged in the same direction (x direction) as the

X-ray shielding portions

31b and 32b. The purpose of the multi-slit 35 is to form small focal light sources (dispersed light sources) arranged at a predetermined pitch in the x direction by partially shielding the radiation emitted from the X-ray focal point 18b.

The lattice pitch p ₃ of the multi-slit 35 needs to be set so as to satisfy the following equation (27), where L ₃ is the distance from the multi-slit 35 to the first absorption-type lattice 31.

Expression (27) indicates that the projection image (G1 image) of the X-rays emitted from the small focus light sources dispersedly formed by the multi-slit 35 by the first absorption type grating 31 is the position of the second absorption type grating 32. This is a geometric condition for matching (overlapping).

In addition, since the position of the multi-slit 35 is substantially the X-ray focal position, the grating pitch p2 of the _second absorption grating 32 is determined so as to satisfy the relationship of the following equation (28).

As described above, in this example, the G1 images based on the plurality of point light sources formed by the multi-slit 35 are superimposed, so that the image quality of the phase contrast image can be improved without reducing the X-ray intensity. it can.

In this example, as a method for analyzing the periodic pattern of the image acquired by the X-ray image detector 30, any of the above-described analysis methods 1 to 3 can be applied. When accompanied by rotation about the optical axis C, the multi-slit 35 also rotates together with the first absorption grating 31 so that the grating pitch direction coincides with the grating pitch direction of the first absorption grating 31. It is preferred that Further, in the analysis method 1 described above, when changing the relative positional relationship between the G1 image and the second absorption grating 32, the multi-slit 35 can be moved in a direction intersecting the X-ray shielding portion. .

FIG. 20 shows the configuration of another example of a radiation imaging apparatus for explaining an embodiment of the present invention. Elements common to the X-ray imaging apparatus 1 shown in FIG. 1 are denoted by common reference numerals, and description thereof is omitted or simplified.

An X-ray imaging apparatus 101 shown in FIG. 20 is different from the X-ray imaging apparatus 1 shown in FIG. 1 in that the first absorption type grating 31 is disposed between the X-ray irradiation unit 11 and the subject table 15. ing.

The first absorption type lattice 31 is held by the holding member 34 and is attached to the arm member 61 via the holding member 34. Since the holding member 34 is supported by the arm member 61 in a cantilever shape, it is preferable that the holding member 34 has high rigidity. For example, a member having higher rigidity than the substrate 31a of the first absorption type lattice 31 is used. preferable. Thereby, the relative position shift of the X-ray focal point 18b and the first and

second absorption gratings

31 and 32 can be prevented or suppressed, and the detection accuracy of the phase information of the subject H can be improved.

In the configuration described above, the subject H is disposed between the first absorption type grating 31 and the second absorption type grating 32, but the first object formed at the position of the second absorption type grating 32. The G1 image of the absorption type grating 31 is modulated by the subject H. As in the X-ray imaging apparatus 1 shown in FIG. 1, the G1 image is intensity-modulated by superposition with the second absorption grating 32, and the intensity-modulated G1 image is captured by the X-ray image detector 30. Is done. Therefore, the X-ray imaging apparatus 101 can also obtain a phase contrast image of the subject H on the same principle as the analysis methods 1 to 3 described in the X-ray imaging apparatus 1 shown in FIG.

In this X-ray imaging apparatus 101, the subject H is irradiated with X-rays whose dose is almost halved by shielding with the first absorption type grating 31. Therefore, the exposure amount of the subject H is shown in FIG. It can be reduced to about half that of the X-ray imaging apparatus 1 shown.

In the X-ray imaging apparatus 101, the first grating is not limited to the absorption grating but may be a phase grating.

Further, in the X-ray imaging apparatus 101, the above-described multi slit 35 (see FIG. 19) can be provided.

FIG. 21 shows the configuration of another example of a radiation imaging apparatus for explaining the embodiment of the present invention. Elements common to the X-ray imaging apparatus 1 shown in FIG. 1 are denoted by common reference numerals, and description thereof is omitted or simplified.

In the X-ray imaging apparatus 201 shown in FIG. 21, the imaging unit 212 is roughly constituted by the first absorption type grating 31 and the X-ray image detector 230, and the second absorption type grating 32 is omitted. 1 is different from the X-ray imaging apparatus 1 shown in FIG.

The X-ray image detector 230 includes an image receiving unit 41 in which a plurality of pixels 40 that convert X-rays into electric charges and store them are two-dimensionally arranged, read out the electric charges accumulated in each pixel 40, and read them out as image data. To be sent to the console 3.

The plurality of pixels 40 are arranged at an arrangement pitch capable of resolving the periodic intensity distribution of the G1 image formed on the image receiving surface of the X-ray image detector 230. Specifically, the arrangement pitch P of the pixels 40 is set to a pitch of 1/2 or less, preferably 1/5 or less of the pattern period p ₁ ′ of the periodic intensity distribution of the G1 image, which is generally several μm. An X-ray image detector in which a plurality of pixels are arranged in such a small arrangement pitch is a CCD sensor or a read circuit that is formed on a semiconductor substrate made of single crystal silicon or the like, and a readout circuit that reads out the electric charge accumulated in each pixel. A solid-state imaging device such as a CMOS sensor can be used as a base. In addition, as long as the pixel arrangement pitch P is satisfied, the one configured based on the TFT panel may be used.

In the above configuration, the G1 image is formed on the X-ray image detector 230. When the subject H is arranged on the subject table 15 arranged between the X-ray irradiation unit 11 and the imaging unit 212, more specifically between the X-ray irradiation unit 11 and the first absorption type grating 31. The periodic intensity distribution of the G1 image is modulated by the subject H. The image acquired by capturing the G1 image by the X-ray image detector 230 includes a periodic pattern corresponding to the periodic intensity distribution of the G1 image. By analyzing this periodic pattern, the phase contrast of the subject H is analyzed. An image can be generated.

Hereinafter, a method for analyzing a periodic pattern of an image in the X-ray imaging apparatus 201 will be described.

[Analysis method 1]
The analysis of the periodic pattern of the image can be performed, for example, by the above-described fringe scanning method. First, the G1 image projected from the first absorption type grating 31 to the position of the X-ray image detector 230 is displaced in the x direction by an amount corresponding to the refraction angle φ due to refraction of X-rays at the subject H. It will be. This displacement amount Δx is approximately expressed by the following equation (29) based on the fact that the X-ray refraction angle φ is very small. L ₄ indicates the distance from the first absorption type grating 31 to the X-ray image detector 230.

Here, the refraction angle φ is expressed by Expression (30) using the X-ray wavelength λ and the phase shift distribution Φ (x) of the subject H.

Thus, the displacement amount Δx of the G1 image due to the refraction of X-rays at the subject H is related to the phase shift distribution Φ (x) of the subject H. The displacement amount Δx is related to the phase shift amount ψ of the signal of each pixel of the image data as in the following equation (31).

Therefore, by obtaining the phase shift amount ψ of the signal of each pixel, the refraction angle φ is obtained from the equation (31), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30). By integrating with respect to x, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H can be generated. The phase shift amount ψ is calculated using a fringe scanning method.

That is, the first absorption type grating 31 is translated in a stepwise manner relative to the X-ray image detector 230 in the grating pitch direction (x direction) of the grating, and the period of the pixel 40 with respect to the periodic intensity distribution of the G1 image. Shooting while relatively changing the phase of the target array. The movement of the first absorption type grating 31 can be performed by the scanning mechanism 33.

As the first absorption type grating 31 moves, the G1 image moves, and the translation distance (the amount of movement in the x direction) is one period of the grating period of the first absorption type grating 31 (grating pitch p ₁ ). (Ie, when the phase change reaches 2π), the G1 image returns to its original position. Such a change in the G1 image is picked up by the X-ray image detector 230 while moving the first absorption type grating 31 by a distance of 1 / integer of the grating pitch p ₁ , and a plurality of obtained image data A plurality of signal values are obtained from each pixel, and the arithmetic processing unit 22 performs arithmetic processing to obtain a phase shift amount ψ of the signal of each pixel. Then, the refraction angle φ is obtained from the phase shift amount ψ of the signal of each pixel using the equation (31), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30). By integrating, the phase shift distribution Φ (x) of the subject H, ie, the phase contrast image of the subject H is generated.

[Analysis method 2]
FIG. 22 shows another example of a method for generating a phase contrast image in the X-ray imaging apparatus 201.

A plurality of pixels arranged in the lattice pitch direction (x direction) of the first absorption type lattice 31 is defined as one unit, and the signal values I of the plurality of pixels constituting the unit are interpolated for each unit. In the example shown in the figure, signal values of a plurality of pixels are interpolated by a sine curve, and at least three points are sufficient for interpolation by the sine curve, and therefore three adjacent pixels are used as a unit.

As described above, the G1 image is displaced in the x direction by an amount corresponding to the refraction angle φ due to refraction of X-rays at the subject H. Along with the displacement of the G1 image, the phase of the signal waveform formed by interpolating the signal values I of a plurality of pixels constituting the unit changes for each unit. The phase difference between the waveform of the signal waveform (FIG. 22A) when the subject H is not present and the signal waveform (FIG. 22B) when the subject H is present is the phase of the signal of the pixel included in the unit. This corresponds to the displacement amount ψ. The refraction angle φ is obtained from the phase shift amount ψ of the signal of each pixel using the equation (31) and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30), and this is integrated with respect to x. Thus, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H is generated.

Note that the first absorption-type grating is assumed that the grating pitch direction (x-direction) of the first absorption-type grating 31 coincides with the row direction or the column direction in the arrangement of the pixels 40 in the X-ray image detector 230. Although the description has been made assuming that three pixels arranged in the lattice pitch direction of 31, that is, the pattern periodic direction of the periodic intensity distribution of the G1 image, are taken as one unit, the direction intersecting the periodic intensity distribution pattern of the G1 image If the periodic intensity distribution of the G1 image is resolved with a plurality of pixels of three or more arranged in a unit as a unit, the phase shift amount ψ of the signal of the pixel included in the unit can be calculated for each unit. Therefore, the first absorption grating 31 and the X-ray image detector 230 are arranged such that the row direction and the column direction in the arrangement of the pixels 40 intersect with the pattern period direction of the periodic intensity distribution of the G1 image. However, the optical axis C may be relatively rotated around the optical axis C.

[Analysis method 3]
Similarly to the X-ray imaging apparatus 1 shown in FIG. 1, the X-ray imaging apparatus 201 can also generate a phase contrast image by analyzing a periodic pattern of an image using Fourier transform and inverse Fourier transform. In this case, in the X-ray imaging apparatus 1 shown in FIG. 1, the periodic pattern of the image corresponds to moire fringes formed by superimposing the G1 image and the second absorption type grating 32. In the X-ray imaging apparatus 201, this corresponds to the periodic intensity distribution of the G1 image.

As described above, according to the X-ray imaging apparatus 201, the periodic intensity distribution of the G1 image is detected using a detector having a pixel pitch smaller than the period of the periodic intensity distribution of the G1 image, and this is analyzed to obtain phase information. Since the pixel pitch is small, the spatial resolution is excellent. Further, since the second absorption type grating 32 is not interposed, the detection accuracy of the phase information can be improved.

In the X-ray imaging apparatus 201, the first grating is not limited to the absorption grating but may be a phase grating.

In the X-ray imaging apparatus 201, the X-ray irradiation unit 11 can be provided with the multi slit 35 (see FIG. 19) described above. In this case, the multi-slit lattice pitch p ₃ is set to satisfy the following equation (32), where L ₃ is the distance from the multi-slit to the first absorption type lattice 31.

Expression (32) indicates that the projection image (G1 image) of the X-rays emitted from the small-focus light sources dispersedly formed by the multi-slits by the first absorption type grating 31 coincides with the position of the X-ray image detector 230. It is a geometrical condition for doing (overlapping).

In the X-ray imaging apparatus 201, the first absorption type grating 31 can also be disposed between the X-ray irradiation unit 11 and the subject table 15.

FIG. 23 shows a modification of the X-ray imaging apparatus of FIG.

In the X-ray imaging apparatus 201A shown in FIG. 23, the plurality of pixels 40 of the X-ray image detector 230A have a pattern period of the periodic intensity distribution of the G1 image formed on the image receiving surface of the X-ray image detector 230A. They are arranged at an arrangement pitch that causes moire in the relationship. Specifically, the arrangement pitch P of the pixels 40 is set to be approximately the same as the pattern period of the periodic intensity distribution of the G1 image, which is generally several μm.

In the above configuration, there is a slight difference between the pattern period p ₁ ′ in the x direction of the periodic intensity distribution of the G1 image and the arrangement pitch P in the x direction of the pixels 40 (not limited to design differences, but manufacturing errors and arrangement errors). If there is a difference due to this, moire occurs in the image acquired by the X-ray image detector 230A. The X-ray imaging apparatus 201A generates a phase contrast image of the subject H by analyzing the moire.

Since the arrangement pitch P of the pixels 40 is a value determined in terms of design and is difficult to change, when generating moire, the arrangement pitch P of the pixels 40 and the pattern period p of the periodic intensity distribution of the G1 image. _In order to adjust the relationship with ₁ ′, it is preferable to adjust the position of the first absorption grating 31 by changing the pattern period p ₁ ′ of the G1 image. As a mechanism for changing the pattern period of the periodic intensity distribution of the G1 image, a mechanism similar to the above-described relative rotation mechanism 50, relative tilt mechanism 51, and relative movement mechanism 52 (all refer to FIG. 6) is used. it can.

In the relationship between the array pitch P of the pixels 40 and the pattern period p ₁ ′ of the periodic intensity distribution of the G1 image, the period T in the x direction of moire generated in the image is expressed by the following equation (33).

When the subject H is arranged between the X-ray irradiation unit 11 and the absorption type grating 31, moire generated in an image acquired by the X-ray image detector 230A is modulated by the subject H. This modulation amount is proportional to the angle of the X-ray deflected by the refraction effect by the subject H. Therefore, a phase contrast image of the subject H can be generated by analyzing this moire.

Hereinafter, a method of analyzing image moire in the X-ray imaging apparatus 201A will be described.

[Analysis method 1]
The analysis of the periodic pattern of the image can be performed, for example, by the above-described fringe scanning method. First, the G1 image projected from the first absorption type grating 31 to the position of the X-ray image detector 230A is displaced in the x direction by an amount corresponding to the refraction angle φ due to refraction of X-rays at the subject H. It will be. This displacement amount Δx is related to the phase shift distribution Φ (x) of the subject H, as is apparent from the above equations (29) and (30).

As the G1 image is displaced in the x direction, the moire is also displaced in the x direction. When the displacement amount Δx of the G1 image reaches the period p ₁ ′, the moire returns to the original state. Is expressed by the following equation (34) using the displacement amount Δx of the G1 image, where T is the period of the moire in the x direction.

This displacement amount ΔX is related to the phase shift amount ψ of the signal of each pixel of the image data as shown in the following equation (35).

Accordingly, by obtaining the phase shift amount ψ of the signal of each pixel, the refraction angle φ is obtained from the equation (31), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30). By integrating with respect to x, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H can be generated. The phase shift amount ψ is calculated using a fringe scanning method.

That is, the first absorption type grating 31 is translated stepwise in the grating pitch direction (x direction) of the grating with respect to the X-ray image detector 230A, and the period of the pixel 40 with respect to the periodic intensity distribution of the G1 image. Shooting while relatively changing the phase of the target array. The movement of the first absorption type grating 31 can be performed by the scanning mechanism 33.

As the first absorption type grating 31 moves, the moire also moves, and the translation distance (amount of movement in the x direction) reaches one period (grating pitch p ₁ ) of the grating period of the first absorption type grating 31. Then (ie, when the phase change reaches 2π), the moire returns to the original state. Such movement of the absorption-type grating 31 with a change in the moiré taken while one scan pitch of an integral fraction of the grating pitch p _1, a plurality of signal values from a plurality of image data for each pixel obtained The phase shift amount ψ of the signal of each pixel is obtained by obtaining and performing arithmetic processing in the arithmetic processing unit 22. Then, the refraction angle φ is obtained from the phase shift amount ψ of the signal of each pixel using the equation (31), and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30). By integrating, the phase shift distribution Φ (x) of the subject H, ie, the phase contrast image of the subject H is generated.

In the moire analysis by the above-described fringe scanning method, the moire moves as a whole with the relative movement between the first absorption grating 31 and the X-ray image detector 230A. It is applicable even if it is longer than that.

[Analysis method 2]
FIG. 24 shows another example of a method for generating a phase contrast image in the X-ray imaging apparatus 201A.

A plurality of pixels arranged in the lattice pitch direction (x direction) of the first absorption type lattice 31 is used as a unit, and the signal value I of the plurality of pixels constituting the unit is interpolated for each unit. In the illustrated example, signal values of a plurality of pixels are interpolated by a sine curve, and at least three points are sufficient for interpolation by the sine curve, and therefore, three adjacent pixels are used as a unit. When the pattern period p ₁ ′ of the G1 image and the arrangement pitch P of the pixels 40 are in a relationship that causes moiré in the image, the signal values I of a plurality of pixels constituting the unit are interpolated for each unit. The period of the signal waveform is a moire period T.

As described above, the G1 image is displaced in the x direction by an amount corresponding to the refraction angle φ due to refraction of X-rays at the subject H. When the G1 image is displaced by Δx in the x direction, the moire is also displaced by ΔX in the x direction, and the phase of the signal waveform changes. The phase difference between the waveform of the signal waveform (FIG. 24A) when the subject H is not present and the signal waveform (FIG. 24B) when the subject H is present is the phase of the signal of the pixel included in the unit. This corresponds to the displacement amount ψ. The refraction angle φ is obtained from the phase shift amount ψ of the signal of each pixel using the equation (31) and the differential amount of the phase shift distribution Φ (x) is obtained using the equation (30), and this is integrated with respect to x. Thus, the phase shift distribution Φ (x) of the subject H, that is, the phase contrast image of the subject H is generated.

Note that the first absorption-type grating is assumed that the grating pitch direction (x-direction) of the first absorption-type grating 31 coincides with the row direction or the column direction in the arrangement of the pixels 40 in the X-ray image detector 230A. Although the description has been made assuming that the three pixels arranged in the lattice pitch direction of 31, that is, the pattern period direction of the periodic intensity distribution of the G1 image, are taken as one unit, with respect to the pattern period direction of the periodic intensity distribution of the G1 image, The first absorption-type grating 31 and the X-ray image detector 230A are arranged so as to rotate relatively around the optical axis C so that both the row direction and the column direction in the arrangement of the pixels 40 intersect. May be.

[Analysis method 3]
Similarly to the X-ray imaging apparatus 201 shown in FIG. 21, the X-ray imaging apparatus 201A can also generate a phase contrast image by analyzing the periodic pattern of an image using Fourier transform and inverse Fourier transform. In this case, the periodic pattern of the image corresponds to the periodic intensity distribution of the G1 image in the X-ray imaging apparatus 201 shown in FIG. 21, but the periodic pattern of the G1 image in the X-ray imaging apparatus 201A. This corresponds to moire caused by interference between the intensity distribution and the periodic arrangement of the pixels 40 of the X-ray image detector 230A.

According to the X-ray imaging apparatus 201A, the interference between the pattern period p ₁ ′ of the G1 image and the pixel pitch P of the X-ray image detector 230A causes moire in the image acquired by the X-ray image detector 230A. Then, a phase contrast image is generated based on the moire modulation caused by the subject H. In general, the S / N tends to decrease as the pixels in the X-ray image detector become smaller. Therefore, the pixel arrangement pitch in the X-ray image detector becomes smaller to detect the periodic intensity distribution of the fine G1 image. Therefore, it is possible to secure the S / N and improve the detection accuracy of the phase information.

FIG. 25 shows the configuration of another example of a radiation imaging apparatus for explaining the embodiment of the present invention. Note that elements common to the above-described

X-ray imaging apparatuses

1, 101, and 201 are denoted by common reference numerals, and description thereof is omitted or simplified.

An X-ray imaging apparatus 301 shown in FIG. 25 includes an arm member that supports the X-ray irradiation unit 11, the first and

second absorption gratings

31 and 32, the X-ray image detector 30, and the subject table 15. In addition to (first support member) 61, first and

second absorption gratings

31 and 32, X-ray image detector 30, and arm member (second support member) 361 that supports subject table 15. Is different from the X-ray imaging apparatus 1 shown in FIG.

The arm member 361 for supporting the subject table 15 and the imaging unit 12 positioned on the lower side in the vertical direction (downstream of the subject table 15 in the X-ray traveling direction along the optical axis C) has a first absorption. Since there is no influence when the subject H is arranged on the placement surface of the subject table 15 along the lattice pitch direction (x direction) of the mold lattice 31, there is no particular limitation on the arrangement, but the X-ray imaging apparatus 301 is not limited. The arm member 361 includes the first and

second absorption gratings

31, 32 and the arm member 61 in the extending direction (y direction) of the X-ray shielding part 31 b in the first absorption grating 31. The X-ray image detector 30 and the subject table 15 are arranged so as to be sandwiched therebetween. That is, the arm member 361 extends the first absorption type lattice 31 in the lattice pitch direction (x direction) on the opposite side of the first absorption type lattice 31 from the arm member 61 in the same manner as the arm member 61. The first absorption type grating 31 is provided so as to extend in the vertical direction through a region extending outside the region and extending in the extending direction (y direction) of the X-ray shielding portion 31b.

Further, from the viewpoint of preventing or suppressing the displacement of the relative positions of the X-ray focal point 18b and the first and

second absorption gratings

31 and 32, the subject table 15 includes a buffer member 15b that absorbs or relaxes shock, vibration, and the like. The arm member 361 is attached.

According to the X-ray imaging apparatus 301, the X-ray irradiation unit 11, the first and

second absorption gratings

31 and 32, the X-ray image detector 30, and the subject table 15 are supported by a plurality of support members ( By dividing the arm member 61 and the arm member 361), the load acting on each support member is reduced, and deformation of each support member is prevented or suppressed. Thereby, the shift of the relative positions of the X-ray focal point 18b and the first and

second absorption gratings

31 and 32 due to the deformation of the support member can be prevented or suppressed, and the detection accuracy of the phase information of the subject H can be improved. Can be increased.

In addition, the arm member 361 includes the first and

second absorption gratings

31, 32 and the arm member 61 in the extending direction (y direction) of the X-ray shielding portion 31 b in the first absorption grating 31. The X-ray image detector 30 and the object table 15 are arranged to be sandwiched between them. In the above-described fringe scanning method, when the second absorption grating 32 is translated in the x direction, the movement in the y direction is performed. It can be regulated and moved reliably in the x direction.

In the X-ray imaging apparatus 301, the first grating is not limited to the absorption grating but may be a phase grating.

Further, in the X-ray imaging apparatus 301, the X-ray irradiation unit 11 can be provided with the multi-slit 35 (see FIG. 19) described above.

FIG. 26 shows a modification of the X-ray imaging apparatus 301 of FIG.

In the X-ray imaging apparatus shown in FIG. 26, the first absorption type grating 31 is disposed between the X-ray irradiation unit 11 and the subject table 15 like the X-ray imaging apparatus 101 shown in FIG. The arm member 361 is different from the X-ray imaging apparatus 301 shown in FIG. 25 in that the arm member 361 supports the second absorption type grating 32, the X-ray image detector 30, and the subject table 15.

In this example as well, the first grating is not limited to the absorption grating, but may be a phase grating.

Also in this example, the multi-slit 35 (see FIG. 19) described above can be provided in the X-ray irradiation unit 11.

FIG. 27 shows another modification of the X-ray imaging apparatus 301 of FIG.

In the X-ray imaging apparatus shown in FIG. 27, the imaging unit is the imaging unit 212 of the X-ray imaging apparatus 201 shown in FIG. 21, and is roughly configured by the first absorption grating 31 and the X-ray image detector 230. In addition, the arm member 361 is different from the X-ray imaging apparatus 301 shown in FIG. 25 in that the first absorption grating 31, the X-ray image detector 230, and the subject table 15 are supported.

Also in this example, the first absorption grating 31 can be disposed between the X-ray irradiation unit 11 and the subject table 15.

FIG. 28 shows the configuration of another example of a radiation imaging apparatus for explaining an embodiment of the present invention. Note that elements common to the above-described

X-ray imaging apparatuses

In the X-ray imaging apparatus 401 shown in FIG. 28, the arm member 61 supports the X-ray irradiation unit 11, the first and

second absorption gratings

31 and 32, and the X-ray image detector 30. 1 differs from the X-ray imaging apparatus 1 shown in FIG. 1 in that it is supported by a support member (third support member) 461 different from the arm member 61. That is, in the X-ray imaging apparatus 401, the subject table 15 is separated from the X-ray imaging apparatus main body 2.

According to the present X-ray imaging apparatus 401, the X-ray irradiating unit 11 is subject to shock caused when the subject H is placed on the subject table 15, vibration due to movement (body movement) of the subject H during or during imaging. And the transmission to the stand 13 that supports the imaging unit 12, and as described above, the displacement of the relative positions of the X-ray focal point 18 b and the first and

second absorption gratings

31 and 32 is prevented or suppressed. The detection accuracy of the phase information of the subject H can be improved.

In the X-ray imaging apparatus 401, the first grating is not limited to the absorption grating but may be a phase grating.

Further, in the X-ray imaging apparatus 401, the X-ray irradiation unit 11 can be provided with the multi slit 35 (see FIG. 19) described above.

FIG. 29 shows a modification of the X-ray imaging apparatus 401 of FIG.

The X-ray imaging apparatus shown in FIG. 29 is similar to the X-ray imaging apparatus 101 shown in FIG. 20 in that the first absorption grating 31 is disposed between the X-ray irradiation unit 11 and the subject table 15. Different from the X-ray imaging apparatus 401 shown in FIG. The subject table 15 is supported by a support member 461 different from the arm member 61 that supports the X-ray irradiation unit 11, the first and

second absorption gratings

31 and 32, and the X-ray image detector 30. .

In this example as well, the first grating is not limited to the absorption type grating but may be a phase type grating.

Also in the book, the multi-slit 35 (see FIG. 19) described above can be provided in the X-ray irradiation unit 11.

FIG. 30 shows another modification of the X-ray imaging apparatus 401 of FIG.

In the X-ray imaging apparatus shown in FIG. 30, the imaging unit is the imaging unit 212 of the X-ray imaging apparatus 201 shown in FIG. 21, and is roughly configured by the first absorption grating 31 and the X-ray image detector 230. It differs from the X-ray imaging apparatus 401 shown in FIG. The subject table 15 is supported by a support member 461 different from the arm member 61 that supports the X-ray irradiation unit 11, the first absorption type grating 31, and the X-ray image detector 230.

FIG. 31 shows the configuration of another example of the radiation imaging apparatus for explaining the embodiment of the present invention. Note that elements common to the above-described

X-ray imaging apparatuses

1 and 201 are denoted by common reference numerals, and description thereof is omitted or simplified.

In the X-ray imaging apparatus 501 shown in FIG. 31, the X-ray irradiation unit 11 is supported by an arm member 61, and the imaging unit 12 and the subject table 15 are provided on a base (first stage) provided separately from the arm member 61. 2), the X-ray imaging apparatus 1 shown in FIG.

The pedestal 561 for supporting the imaging unit 12 located on the subject table 15 and the lower side in the vertical direction (downstream of the subject table 15 in the X-ray traveling direction along the optical axis C) is a first absorption type. The structure is not affected when the subject H is arranged on the placement surface of the subject table 15 along the lattice pitch direction (x direction) of the lattice 31, and is thus configured as a structure having higher rigidity than the arm member 61. Can do. In the illustrated example, the base 561 is configured by a plurality of leg members connected to each other. The subject table 15 is installed on a base 561 via a buffer member 15c.

As described above, by dividing the support of the X-ray irradiation unit 11, the imaging unit 12, and the subject table 15 into a plurality of support members (arm member 61 and base 561), the load acting on each support member is reduced. Thus, deformation of each support member is prevented or suppressed.

Further, by supporting the subject table 15 with a base 561 having higher rigidity than the arm member 61, the X-ray focal point 18b caused by the impact or vibration acting on the subject table 15, the first and second absorption gratings 31, The relative position shift of 32 can be prevented or suppressed by the rigid structure, and the detection accuracy of the phase information of the subject H can be improved.

In the X-ray imaging apparatus 501, the first grating is not limited to the absorption grating but may be a phase grating.

Moreover, in the X-ray imaging apparatus 501, the multi-slit 35 (see FIG. 19) described above can be provided in the X-ray irradiation unit 11.

FIG. 32 shows a modification of the X-ray imaging apparatus 501 of FIG.

The X-ray imaging apparatus shown in FIG. 32 has an imaging unit that is an imaging unit 212 of the X-ray imaging apparatus 201 shown in FIG. 21, and is roughly configured by the first absorption grating 31 and the X-ray image detector 230. It differs from the X-ray imaging apparatus 501 shown in FIG. The X-ray irradiation unit 11 is supported by the arm member 61, and the imaging unit 212 and the subject table 15 are supported by a base 561 provided on the base 60 separately from the arm member 61.

FIG. 33 shows a configuration of another example of the radiation imaging apparatus for explaining the embodiment of the present invention. In addition, description is abbreviate | omitted or simplified by attaching | subjecting a common code | symbol to the element which is common in the X-ray imaging apparatus 1 mentioned above.

The above-described X-ray imaging apparatus 1 irradiates X-rays substantially vertically downward, and basically performs imaging of the subject H in the supine position or the sitting position. The X-ray imaging shown in FIG. The apparatus 601 performs imaging of the subject H in a standing position, and differs from the X-ray imaging apparatus 1 described above in that X-rays are irradiated in a substantially horizontal direction.

In the X-ray imaging apparatus 601, the X-ray irradiation unit 11, the first absorption type grating 31, the second absorption type grating 32, and the X-ray image detector 30 are arranged in this order in a substantially horizontal direction, and an arm member 61 is supported. The arm member 61 deviates from a region where the first absorption type grating 31 is extended in the grating pitch direction (z direction), and the first absorption type grating 31 extends in the extending direction of the X-ray shielding part 31b (y direction). It extends in a substantially horizontal direction through a region extending in the horizontal direction.

The subject table 15 is provided so that a subject H (for example, a knee joint) placed thereon is disposed between the X-ray irradiation unit 11 and the first absorption type grating 31, and the arm member 61. It is supported by another support member.

In imaging of knee joints, there is a high need for imaging in a state where a load is applied in an upright position, and thus a standing type apparatus (lateral apparatus) such as the X-ray imaging apparatus 601 is preferable. Further, in the main line imaging apparatus 601, the arm member 61 is configured to be pivotable about the pivot axis 62, and the subject H can be photographed from various directions by pivoting the arm member 61.

In this X-ray imaging apparatus 601, the above-described multi slit 35 (see FIG. 19) can be provided in the X-ray irradiation unit 11.

Also in the X-ray imaging apparatus 601, as in the X-ray imaging apparatus 101 described above, the first absorption type grating 31 is placed between the X-ray irradiation unit 11 and the subject H placed on the subject table 15. Can be arranged.

Also in the X-ray imaging apparatus 601, the second absorption grating 32 can be omitted as in the

X-ray imaging apparatuses

201 and 201A described above.

Further, as shown in FIG. 34, in addition to the arm member 61, an arm member (supporting the X-ray source 11, the first absorption grating 31, the second absorption grating 32, and the X-ray image detector 30). A second support member 661 may be provided.

In the above description, the case where general X-rays are used as radiation has been described, but the present invention is not limited to X-rays, and radiation other than X-rays such as α-rays and γ-rays can also be used. It is. As for the X-ray imaging apparatus other than the X-ray imaging apparatus 1 described above, as in the X-ray imaging apparatus 1, the first grating is not limited to the absorption type grating but may be a phase type grating.

As described above, the following (1) to (34) radiation imaging apparatuses are disclosed in this specification.

(1) A first radiation image including a radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and including a periodic intensity distribution through the radiation emitted from the radiation irradiation unit. A second grating that forms a second radiation image including a periodic intensity distribution by partially shielding the first radiation image, and the second radiation image. A radiation image detector for detecting and acquiring image data; and the radiation irradiating unit, the first grating, the second grating, and the radiation image detector extending in an arrangement direction of the radiation irradiating unit, And a first support member that supports the first grating, the second grating, and the radiation image detector, wherein the first support member places the first grating in the arrangement direction of the linear bodies. An extended region, or an array of linear bodies of the second lattice Radiation imaging apparatus arranged out of the extended area extending in the direction.
(2) The radiation imaging apparatus according to (1), wherein a subject is disposed between the radiation irradiation unit and the first lattice.
(3) The radiation imaging apparatus according to (2), further including a second support member that supports the first grating, the second grating, and the radiation image detector.
(4) The radiographic apparatus according to (3), wherein the first support member and the second support member are arranged in the first lattice in the extending direction of the linear body in the first lattice, A radiation imaging apparatus supporting the first grating, the second grating, and the radiation image detector with the second grating and the radiation image detector interposed therebetween.
(5) The radiographic apparatus according to the above (3) or (4), comprising a subject table disposed between the radiation irradiating unit and the first grating and on which a subject is placed.
(6) The radiographic apparatus according to (5), wherein the subject table is supported by the first support member, or the first support member and the second support member.
(7) In the radiographic apparatus according to (6), the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table. Radiography equipment.
(8) The radiation imaging apparatus according to any one of (2) to (4), wherein the subject table is disposed between the radiation irradiating unit and the first lattice and on which a subject is placed; A radiation imaging apparatus comprising: a third support member that supports the subject table.
(9) The radiation imaging apparatus according to (1), wherein a subject is disposed between the first grating and the second grating.
(10) The radiographic apparatus according to (9), further including a second support member that supports the second grating and the radiographic image detector.
(11) The radiographic apparatus according to (10), wherein the first support member and the second support member are arranged in a direction in which a linear body extends in the first lattice, A radiation imaging apparatus supporting the second grating and the radiation image detector with the radiation image detector interposed therebetween.
(12) The radiation imaging apparatus according to (10) or (11), wherein the radiation imaging apparatus includes a subject table disposed between the first lattice and the second lattice and on which a subject is placed. .
(13) The radiographic apparatus according to (12), wherein the subject table is supported by the first support member, or the first support member and the second support member.
(14) In the radiographic apparatus according to (13), the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table. Radiography equipment.
(15) The radiographic apparatus according to any one of (9) to (11), wherein the object table is disposed between the first grating and the second grating, and the object is placed thereon. A radiation imaging apparatus comprising: a third support member that supports the subject table.
(16) The radiographic apparatus according to any one of (1) to (15), wherein a phase contrast image is generated using at least one image data acquired by the radiographic image detector by imaging a subject. A radiation imaging apparatus including an arithmetic processing unit.
(17) The radiographic apparatus according to (16), wherein a plurality of relative positional relationships are different from each other in phase relationship in the overlap between the periodic intensity distribution of the first radiation image and the periodic structure of the second grating. A scanning mechanism for arranging the first grating and the second grating, and the arithmetic processing unit shoots a subject under the relative positional relationship between the first grating and the second grating. A radiation imaging apparatus that generates a phase contrast image using a plurality of image data acquired by the radiation image detector.
(18) In the radiographic apparatus according to (17), the scanning mechanism may include either one of the first grating and the second grating within a plane on which the grating is arranged. A radiation imaging apparatus in which the first grating and the second grating are arranged in the relative positional relationship by translationally moving in a direction intersecting the arrangement direction of the linear bodies in the grating.
(19) In the radiographic apparatus according to (16), the periodic intensity distribution of the second radiation image includes a periodic intensity distribution of the first radiation image and a periodic structure of the second grating. And the arithmetic processing unit uses one image data obtained by photographing the subject and acquired by the radiation image detector, and a periodic pattern corresponding to the moire fringes in the image data. Radiation imaging apparatus for generating a phase contrast image based on the above.
(20) In the radiographic apparatus according to (19), the arithmetic processing unit includes the plurality of pixels that constitute one unit, with three or more pixels arranged in a direction intersecting the moire fringe as one unit. A radiation imaging apparatus that calculates a signal obtained by interpolating pixel signal values and generates a phase contrast image based on a phase shift amount of the signal when there is a subject and when there is no subject.
(21) The radiographic apparatus according to (19), wherein the arithmetic processing unit obtains a spatial frequency spectrum of the image data using Fourier transform, and extracts a fundamental frequency component of the periodic pattern from the spatial frequency spectrum. A radiation imaging apparatus that separates a frequency region that includes the same, and performs an inverse Fourier transform on the separated frequency region to generate a phase contrast image.
(22) A radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and a radiation image including a periodic intensity distribution is formed by passing the radiation emitted from the radiation irradiation unit. 1 and a radiation image detector that detects the radiation image to acquire image data, the radiation irradiating unit, the first grating, and the radiation image detector extend in the arrangement direction of the radiation. An irradiation unit, a first grating, and a first support member that supports the radiation image detector, wherein the first support member extends the first grating in the arrangement direction of the linear bodies. A radiography apparatus arranged out of the extension area.
(23) The radiation imaging apparatus according to (22), wherein a subject is disposed between the radiation irradiation unit and the first lattice.
(24) The radiation imaging apparatus according to (23), further including a second support member that supports the first grating and the radiation image detector.
(25) In the radiographic apparatus according to (24), the first support member and the second support member are arranged in a direction in which a linear body extends in the first lattice, A radiation imaging apparatus supporting the first grating and the radiation image detector with the radiation image detector interposed therebetween.
(26) The radiation imaging apparatus according to (24) or (25), wherein the radiation imaging apparatus includes a subject table that is disposed between the radiation irradiation unit and the first lattice and on which a subject is placed.
(27) The radiation imaging apparatus according to (26), wherein the subject table is supported by the first support member, or the first support member and the second support member.
(28) In the radiographic apparatus according to (27), the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table. Radiography equipment.
(29) The radiation imaging apparatus according to any one of (23) to (25), wherein the object table is disposed between the radiation irradiating unit and the first grating and on which an object is placed; A radiation imaging apparatus comprising: a third support member that supports the subject table.
(30) The radiation imaging apparatus according to any one of (22) to (29), wherein the subject is captured based on a periodic pattern included in at least one image data acquired by the radiation image detector. A radiation imaging apparatus including an arithmetic processing unit that generates a phase contrast image.
(31) The radiation imaging apparatus according to (30), wherein the radiation image detector has a resolution capable of resolving a periodic intensity distribution of the radiation image, and the periodic pattern is the radiation image. The radiographic apparatus corresponding to a periodic intensity distribution of
(32) The radiographic apparatus according to (30), wherein the radiological image detector has a resolution that generates moiré in relation to a period of the periodic intensity distribution of the radiographic image, and the periodic pattern Is a radiation imaging apparatus corresponding to the moire.
(33) A first radiation image that includes a radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and that includes a periodic intensity distribution through the radiation emitted from the radiation irradiation unit. A second grating forming a second radiation image including a periodic intensity distribution generated by partially shielding the first radiation image, and the second radiation image. A radiation image detector that detects image data and acquires image data; and the radiation irradiator that extends in an arrangement direction of the radiation irradiator, the first grating, the second grating, and the radiation image detector. A first support member that supports the first grating, the second grating, and a second support member that supports the radiation image detector, wherein the first support member includes An extension of the first lattice extending in the direction of arrangement of the linear bodies A radiation imaging apparatus arranged away from a long region or an extended region obtained by extending the second lattice in the arrangement direction of the linear bodies.
(34) A radiation irradiation unit and a periodic structure in which a large number of linear bodies are arranged, and a radiation image including a periodic intensity distribution is formed by passing the radiation emitted from the radiation irradiation unit. 1, a radiation image detector that detects the radiation image to acquire image data, the radiation irradiating unit, the first grating, and the radiation image detector extending in an arrangement direction of the radiation, A first support member that supports the irradiation unit; and a second support member that supports the first grating and the radiation image detector. The first support member includes the first grating. A radiation imaging apparatus arranged out of an extended region extending in the arrangement direction of the linear bodies.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on Dec. 5, 2011 (Japanese Patent Application No. 2011-266163) and a Japanese patent application filed on Oct. 24, 2012 (Japanese Patent Application No. 2012-234888). Incorporated herein by reference.

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 2 X-ray imaging apparatus main body 3 Console 11 X-ray irradiation part 15 Subject stand 18 X-ray tube (X-ray source)
30 X-ray image detector 31 First absorption grating (first grating)
31a Substrate 31b X-ray shielding part (linear body)
32 Second absorption type grating (second grating)
32a Substrate 32b X-ray shielding part (linear body)
61 Arm member (first support member)

Claims

A radiation irradiation unit;
A first grating having a periodic structure in which a large number of linear bodies are arranged, and forming a first radiation image including a periodic intensity distribution by passing the radiation emitted from the radiation irradiation unit; And a second grating for forming a second radiation image including a periodic intensity distribution by partially shielding the first radiation image;
A radiation image detector for detecting the second radiation image and acquiring image data;
The radiation irradiation unit, the first grating, the second grating, and the radiation image detector extend in the arrangement direction, and the radiation irradiation unit, the first grating, the second grating, and the radiation image detection. A first support member for supporting the vessel;
With
The first support member is disposed away from an extended region in which the first lattice extends in the arrangement direction of the linear bodies, or an extended region in which the second lattice extends in the arrangement direction of the linear bodies. Radiography equipment.
The radiation imaging apparatus according to claim 1,
A radiation imaging apparatus in which a subject is disposed between the radiation irradiating unit and the first grating.
The radiographic apparatus according to claim 2,
A radiation imaging apparatus comprising: a second support member that supports the first grating, the second grating, and the radiation image detector.
The radiographic apparatus according to claim 3,
The first support member and the second support member are arranged between the first grating, the second grating, and the radiation image detector in the extending direction of the linear body in the first grating. A radiation imaging apparatus that supports the first grating, the second grating, and the radiation image detector with the sandwiched therebetween.
The radiographic apparatus according to claim 3 or 4,
A radiation imaging apparatus comprising: a subject table disposed between the radiation irradiating unit and the first grid, on which a subject is placed.
The radiographic apparatus according to claim 5,
The radiographic apparatus in which the subject table is supported by the first support member or the first support member and the second support member.
The radiographic apparatus according to claim 6,
The radiation imaging apparatus, wherein the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table.
The radiographic apparatus according to any one of claims 2 to 4,
A subject table disposed between the radiation irradiating unit and the first grid and on which a subject is placed;
A third support member for supporting the subject table;
A radiographic apparatus comprising:
The radiation imaging apparatus according to claim 1,
A radiation imaging apparatus in which a subject is disposed between the first grating and the second grating.
The radiographic apparatus according to claim 9,
A radiation imaging apparatus comprising a second support member that supports the second grating and the radiation image detector.
The radiographic apparatus according to claim 10,
The first supporting member and the second supporting member sandwich the second grating and the radiation image detector in the extending direction of the linear body in the first grating, and these second supporting members A radiation imaging apparatus supporting a grating and a radiation image detector.
The radiographic apparatus according to claim 10 or 11,
A radiation imaging apparatus comprising: a subject table disposed between the first lattice and the second lattice, on which a subject is placed.
The radiographic apparatus according to claim 12,
The radiographic apparatus in which the subject table is supported by the first support member or the first support member and the second support member.
The radiographic apparatus according to claim 13,
The radiation imaging apparatus, wherein the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table.
The radiographic apparatus according to any one of claims 9 to 11,
A subject table disposed between the first grid and the second grid and on which a subject is placed;
A third support member for supporting the subject table;
A radiographic apparatus comprising:
The radiation imaging apparatus according to claim 1,
A radiation imaging apparatus including an arithmetic processing unit that images a subject and generates a phase contrast image using at least one image data acquired by the radiation image detector.
The radiographic apparatus according to claim 16, wherein
The first grating and the second grating are arranged in a plurality of relative positional relationships in which the phase relationship in the overlap between the periodic intensity distribution of the first radiation image and the periodic structure of the second grating is different from each other. A scanning mechanism,
The arithmetic processing unit images a subject under the relative positional relationship between the first grating and the second grating and uses a plurality of image data acquired by the radiation image detector to perform phase contrast. A radiography device that generates images.
The radiographic apparatus according to claim 17,
The scanning mechanism translates one of the first grating and the second grating in a direction intersecting the arrangement direction of the linear bodies in the grating in a plane where the grating is arranged. A radiation imaging apparatus that is moved and places the first grating and the second grating in the relative positional relationship.
The radiographic apparatus according to claim 16, wherein
The periodic intensity distribution of the second radiation image includes moiré fringes due to superposition of the periodic intensity distribution of the first radiation image and the periodic structure of the second grating,
The arithmetic processing unit captures a subject, uses one piece of image data acquired by the radiation image detector, and generates a phase contrast image based on a periodic pattern corresponding to the moire fringes in the image data. apparatus.
The radiographic apparatus according to claim 19, wherein
The arithmetic processing unit calculates a signal obtained by interpolating signal values of the plurality of pixels constituting one unit, with three or more pixels arranged in a direction intersecting the moire stripe as one unit, A radiation imaging apparatus that generates a phase contrast image based on a phase shift amount of the signal when there is an object and when there is no subject.
The radiographic apparatus according to claim 19, wherein
The arithmetic processing unit obtains a spatial frequency spectrum of the image data using Fourier transform, separates a frequency region including the fundamental frequency component of the periodic pattern from the spatial frequency spectrum, and separates the separated frequency region into the separated frequency region. A radiation imaging apparatus that generates a phase contrast image by performing inverse Fourier transform on the image.
A radiation irradiation unit;
A first grating having a periodic structure in which a large number of linear bodies are arranged, and forming a radiation image including a periodic intensity distribution by passing the radiation emitted from the radiation irradiation unit;
A radiation image detector for detecting the radiation image and acquiring image data;
A first support member that extends in the arrangement direction of the radiation irradiation unit, the first grating, and the radiation image detector, and supports the radiation irradiation unit, the first grating, and the radiation image detector;
With
The first support member is a radiation imaging apparatus arranged so as to be out of an extended region obtained by extending the first lattice in the arrangement direction of the linear bodies.
The radiation imaging apparatus according to claim 22,
A radiation imaging apparatus in which a subject is disposed between the radiation irradiating unit and the first grating.
The radiographic apparatus according to claim 23, wherein
A radiation imaging apparatus comprising: a first support member that supports the first grating and the radiation image detector.
The radiographic apparatus according to claim 24, wherein
The first support member and the second support member sandwich the first lattice and the radiation image detector in the extending direction of the linear body in the first lattice, and the first support member and the second support member A radiation imaging apparatus supporting a grating and a radiation image detector.
The radiographic apparatus according to claim 24 or 25, wherein:
A radiation imaging apparatus comprising: a subject table disposed between the radiation irradiating unit and the first grid, on which a subject is placed.
The radiographic apparatus according to claim 26, wherein
The radiographic apparatus in which the subject table is supported by the first support member or the first support member and the second support member.
The radiographic apparatus according to claim 27, wherein
The radiation imaging apparatus, wherein the subject table is supported by a support member that supports the subject table via a buffer member that buffers force and vibration acting on the subject table.
The radiographic apparatus according to any one of claims 23 to 25, wherein
A subject table disposed between the radiation irradiating unit and the first grid and on which a subject is placed;
A third support member for supporting the subject table;
A radiographic apparatus comprising:
The radiation imaging apparatus according to claim 22,
A radiation imaging apparatus comprising: an arithmetic processing unit that images a subject and generates a phase contrast image based on a periodic pattern included in at least one image data acquired by the radiation image detector.
The radiographic apparatus according to claim 30, wherein
The radiation image detector has a resolution capable of resolving a periodic intensity distribution of the radiation image,
The said radiographic apparatus with which the said periodic pattern respond | corresponds to the periodic intensity distribution of the said radiographic image.
The radiographic apparatus according to claim 30, wherein
The radiological image detector has a resolution that produces moiré in relation to the period of the periodic intensity distribution of the radiographic image,
The periodic pattern is a radiation imaging apparatus corresponding to the moire.
A radiation irradiation unit;
A first grating having a periodic structure in which a large number of linear bodies are arranged, and forming a first radiation image including a periodic intensity distribution by passing the radiation emitted from the radiation irradiation unit; And a second grating forming a second radiation image including a periodic intensity distribution caused by partially shielding the first radiation image;
A radiation image detector for detecting the second radiation image and acquiring image data;
A first support member that extends in the arrangement direction of the radiation irradiation unit, the first grating, the second grating, and the radiation image detector, and supports the radiation irradiation unit;
A second support member that supports the first grating, the second grating, and the radiation image detector;
With
The first support member is a radiation imaging apparatus arranged so as to be out of an extended region obtained by extending the first lattice in the arrangement direction of the linear bodies.
A radiation irradiation unit;
A first grating having a periodic structure in which a large number of linear bodies are arranged, and forming a radiation image including a periodic intensity distribution by passing the radiation emitted from the radiation irradiation unit;
A radiation image detector for detecting the radiation image and acquiring image data;
A first support member that extends in an arrangement direction of the radiation irradiation unit, the first grating, and the radiation image detector, and supports the radiation irradiation unit;
A second support member for supporting the first grating and the radiation image detector;
With
The first support member is a radiation imaging apparatus arranged so as to be out of an extended region obtained by extending the first lattice in the arrangement direction of the linear bodies.