JP2003116828A - Method and apparatus for photographing radiation image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately generate a phase contrast image by using radiation images obtained at a plurality of photographing positions. SOLUTION: The method for photographing the radiation image comprises the steps of arranging a plurality of detection panels 31, 32, and 33 at the plurality of the photographing positions, irradiating the panels 31, 32, and 33 with an X-ray 12 transmitted through an object 21, and obtaining image data Sn which represent the X-ray images of the subject at the plurality of the photographing positions. The panels 31, 32 and 33 have thicker fluorescent substance as the panels 31, 32 and 33 separate farther from the object 21, and the sensitivity become higher. An arithmetic unit 40 generates image data Sp which represents the phase contrast image from the image data Sn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects radiation applied to a subject at a plurality of photographing positions having different distances from the subject to obtain a plurality of radiation images, and uses these plurality of radiation images to perform phase contrast. The present invention relates to a radiation image capturing method and apparatus suitable for generating an image.

[0002]

2. Description of the Related Art Conventionally, radiation (X-ray, α
Rays, β rays, γ rays, electron rays, ultraviolet rays, etc.) to radiate the radiation that has passed through the subject, such as a stimulable phosphor sheet or a radiation detection panel in which a plurality of detection elements are arranged two-dimensionally. Image data representing a radiation image of a subject is detected by a detector, various image processing is performed on the image data, and the image data is then reproduced.

Here, in the method using the stimulable phosphor sheet, a part of the radiation energy transmitted through the subject is accumulated, and when excitation light is irradiated thereafter, stimulated emission light of a light amount corresponding to the accumulated energy is emitted. Using the stimulable phosphor (stimulable phosphor), the radiation image information of the subject is recorded on the sheet-shaped stimulable phosphor (that is, the stimulable phosphor sheet), and the stimulable phosphor sheet is used as a laser beam. Is a method of generating stimulated emission light by scanning with excitation light such as, and photoelectrically reading the generated stimulated emission light to obtain image data representing a radiation image of a subject. Further, the method using the radiation detection panel uses a radiation detection panel in which a plurality of detection elements are two-dimensionally arranged, and generates an electric signal in each detection element according to the radiation dose applied to the radiation detection panel. This is a method of obtaining image data representing a radiation image of a subject based on this electric signal.

By the way, the radiation image thus obtained represents the difference in the intensity of the transmitted radiation in the subject as an image. For example, when a subject including a bone part and a soft part is photographed, the radiation that has passed through the bone part is greatly attenuated, so that the amount of radiation that reaches the detector is small, but the radiation that has passed through the soft part is not significantly attenuated, so that the detection is performed. The radiation dose reaching the vessel is relatively high. Therefore, in the case of such a subject, a radiographic image in which the bone portion is white and the soft portion is black and the contrast difference is large, that is, a large amount of information is obtained.

However, for example in breast cancer diagnosis,
When the subject is mainly composed of only the soft part, the difference in radiation attenuation amount due to the tissue is not so large, so that only a radiation image with a small contrast difference, that is, a small amount of information can be obtained.

Therefore, there has been proposed a phase contrast imaging method for visualizing a phase difference of radiation caused by passing through a subject. In this phase contrast imaging method, since radiation is an electromagnetic wave similar to light and a wave propagates and propagates, when two different substances are irradiated with radiation, the difference in how the radiation propagates in the substance causes The subject is photographed based on the fact that the phases of the radiation waves are different before and after the transmission of the substance, resulting in a phase difference. Here, when the subject is a soft part, the phase difference of the radiation becomes larger than the difference of the attenuation amount of the radiation, so the phase contrast imaging method is used to capture the phase difference of the radiation as a phase contrast image. This makes it possible to visualize a subtle difference in tissues contained in the soft part. For the phase contrast imaging method, see `` Pe
ter Cloetens, et al., "Quantitative aspects of coh
erent hard X-ray imaging: Talbot image and hologra
phic reconstruction ", Proc, SPIE, Vol.3154 (1977),
72-82 (Reference 1) "and" Peter Cloetens, et al., "
Hard x-ray phase imaging using simple propagation
of a coherent synchrotron radiation beam ", J. Phys.
D: Appl. Phys. 32 (1999), A145-A151 (reference 2) "for details. According to these documents, image data representing a plurality of radiographic images is obtained by performing imaging using a two-dimensional detector such as a radiation detection panel at a plurality of imaging positions having different distances from the subject, and a plurality of image data is obtained. A phase contrast image can be generated by performing a calculation based on a predetermined algorithm using.

On the other hand, when obtaining a radiation image, the radiation dose applied to the two-dimensional detector changes in inverse proportion to the square of the distance between the radiation source and the two-dimensional detector. Further, since the radiation spreads from the radiation source and propagates, the larger the distance between the subject and the two-dimensional detector, the larger the size of the radiation image detected by the two-dimensional detector. Therefore, there has been proposed a radiographic image capturing apparatus in which a gain when reading a radiographic image is adjusted and an enlargement ratio of the radiographic image is obtained according to the distance between the subject and the two-dimensional detector (Japanese Patent Laid-Open No. 2004-242242). 2000-245721).

[0008] Further, there has been proposed a method for obtaining a phase contrast image with high accuracy by performing enlarging / reducing processing and density converting processing on radiation images obtained at a plurality of photographing positions (Japanese Patent Application No. 2001-146138).
issue).

[0009]

However, if the reading gain is adjusted or the density is converted,
The work takes a long time and the radiation image cannot be detected efficiently.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to efficiently detect radiation and accurately generate a phase contrast image.

[0011]

A radiographic image capturing method according to the present invention irradiates a subject with radiation and detects the radiation transmitted through the subject at a plurality of photographing positions having different distances from the subject. In a radiographic image capturing method for acquiring a plurality of radiographic images, the radiographic image is acquired by a two-dimensional detector having a higher sensitivity at an imaging position farther from the subject.

The sensitivity of the two-dimensional detector increases as the phosphor content increases. Therefore, in the present invention, the sensitivity of the two-dimensional detector can be increased at a position farther from the subject by using the two-dimensional detector having a larger phosphor content at a photographing position farther from the subject.

Further, as the content of the phosphor increases, the thickness of the phosphor increases and the transmittance of radiation decreases. On the other hand,
The two-dimensional detector located at the photographing position close to the subject can detect the radiation image with high accuracy even if the two-dimensional detector is not so sensitive. For this reason, it is preferable to use a two-dimensional detector having a thinner phosphor and a higher radiation transmittance at an imaging position closer to the subject.

In the radiation image capturing method according to the present invention, a phase contrast image may be generated based on the plurality of radiation images.

The first radiographic image capturing apparatus according to the present invention is arranged at a plurality of image capturing positions at different distances from the subject, and detects radiation transmitted through the subject at the plurality of image capturing positions. A plurality of two-dimensional detectors having higher sensitivity at the farther imaging positions are provided, and a plurality of radiation images are acquired by detecting the radiation transmitted through the subject by the two-dimensional detectors at the plurality of imaging positions. It is characterized by that.

In the first radiation image capturing apparatus according to the present invention, the plurality of two-dimensional detectors may have a higher transmittance of the radiation at a capturing position closer to the subject.

The first radiographic image capturing apparatus according to the present invention may further include image generating means for generating a phase contrast image based on the plurality of radiographic images.

A second radiographic image capturing apparatus according to the present invention is a two-dimensional detector for detecting the radiation transmitted through an object,
Moving means for moving the two-dimensional detector in the optical axis direction of the radiation, and a position sensor for detecting that the two-dimensional detector has reached a plurality of predetermined imaging positions on a moving path by the moving means. A plurality of imaging units sequentially arranged in the optical axis direction, and the two-dimensional detection when the two-dimensional detector reaches each of the imaging positions based on a detection result of the position sensor. Read-out means for reading a signal from the imaging device to acquire a plurality of radiation images, and the two-dimensional detector of the imaging unit arranged far from the subject has higher sensitivity. It is a thing.

In the second radiographic image capturing apparatus according to the present invention, the reading means may be provided for each of the plurality of image capturing units. Thereby, the radiation images can be acquired at the same time in each imaging unit, and as a result, the radiation images can be efficiently acquired at all the imaging positions.

In the second radiographic image capturing apparatus according to the present invention, the two-dimensional detector of the image capturing unit arranged closer to the subject may have a higher transmittance of the radiation.

Further, in the second radiographic image capturing apparatus according to the present invention, based on the plurality of radiographic images,
You may make it further provide the image production | generation means which produces | generates a phase contrast image.

[0022]

According to the present invention, since the radiation image is acquired by using the two-dimensional detector which is more sensitive to the photographing position farther from the subject, even in the two-dimensional detector at the photographing position farther from the subject. As in the case of the two-dimensional detector located at the photographing position close to the subject, the radiation can be detected with high accuracy. Therefore, it is possible to make the densities of the plurality of obtained radiation images substantially equal to each other, and thereby it is possible to accurately generate the phase contrast image. Further, since it is not necessary to adjust the gain of the two-dimensional detector or the density of the obtained radiation image, it is possible to efficiently obtain the radiation image with which the phase contrast image can be obtained with high accuracy.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the first embodiment of the present invention is applied. As shown in FIG. 1, this phase contrast imaging apparatus detects an X-ray source 10 that irradiates an object with X-rays, an object support unit 20 that supports an object 21, and an X-ray transmitted through the object 21 to detect an object. Image data Sn representing a plurality of 21 X-ray images
The recording unit 30 that obtains (n = 1 to N) and the calculation unit 40 that generates the image data Sp representing the phase contrast image based on the plurality of image data Sn are provided.

The X-ray source 10 includes a radiation source 11 which emits synchrotron radiation, and a crystal 13 such as silicon which monochromates the synchrotron radiation into monochromatic X-rays (hereinafter simply referred to as X-rays) 12. The synchrotron radiation emitted from the radiation source 11 is reflected by the crystal 13 to obtain a monochromatic X-ray 12.

The subject support section 20 includes a support base 24 for supporting the subject 21.

The recording unit 30 is composed of a fluorescent substance, a plurality of detecting elements and a fluorescent substance which are two-dimensionally arranged, and is arranged at a plurality of preset photographing positions (three in the present embodiment). ) Detection panels 31, 32, 33, and read-out means 34, 35, 36 for reading out electric signals from a plurality of detection elements constituting each detection panel 31, 32, 33 to obtain a plurality of image data Sn. It should be noted that only one reading means is provided, and each detecting panel 3 is provided by this reading means.
The electrical signals may be sequentially read from 1, 32, and 33.

Here, as in the first embodiment, when photographing is performed using a plurality of detection panels 31, 32, 33,
The more the distance from the subject 21 to the photographing position, the smaller the X-ray dose irradiated to the detection panel and the larger the diffraction. Therefore, in the first embodiment, as the detection panel arranged at the photographing position farther from the subject 21,
It has high sensitivity. Specifically, FIG.
As shown in FIG. 5, the thickness of the phosphor is increased so that the detection panel arranged at a photographing position farther from the subject 21 has a larger phosphor content. As a result, the subject 2
The X-ray 12 can be accurately detected even at a position apart from 1, and the diffraction image can also be accurately detected.

It should be noted that the closer the detection panel is to the photographing position closer to the subject 21, the thinner the phosphor is. Therefore, the amount of attenuation of the X-ray 12 that reaches the detection panel located in the subsequent stage can be reduced.

The calculation unit 40 includes detection panels 31, 32, 3
3 so that the size of the X-ray image represented by the image data Sn obtained in 3 is the same as the size of the X-ray image represented by the image data S1 obtained at the imaging position closest to the subject 21. The X-ray image represented by Sn is subjected to reduction processing, and image data Sp representing a phase contrast image is obtained from the reduced image data Sn.

Here, as in the first embodiment, when photographing is performed using a plurality of detection panels 31, 32, 33,
The size of the X-ray image increases as the photographing position increases with the distance from the subject 21. Therefore, the size of the X-ray image represented by the image data Sn is corrected according to the distance from the subject 21. Specifically, the magnifying power at another shooting position with respect to the shooting position closest to the subject 21 is M (> 1).
In such a case, reduction processing is performed to make the size of the X-ray image 1 / M times.

Since the size of the X-ray image becomes large at the time of photographing, the dose of the X-ray 12 irradiated per unit area of the detection panel becomes small. In order to correct this, each pixel of the X-ray image may be multiplied by 1 / M ² to compensate for the decrease in the dose of the X-ray 12 due to the enlargement of the image.

Then, the image data S subjected to the reduction processing
Based on n, the image data Sp representing the phase contrast image is obtained by the method described in Document 1 above. The method described in Document 1 will be described below. It is assumed that the transmittance of the subject 21 is represented by the following formula (1).

[Equation 1] However, T (x, y): transmittance function A (x, y): transmittance intensity function ψ (x, y): phase shift amount function (x, y): coordinate value representing the position on the detection panel

Here, in the case of a thin object whose transmittance intensity is negligible (that is, A (x, y) is close to 1), the subject 21 and the detection panel 31 are expressed by the following equation (2). , 32, 33 and the spatial frequency component I _dn (fx, fy) obtained by Fourier transforming the image I _dn (x, y) captured at a distance dn (n = 1 to N).
The spatial frequency component of the amount of phase shift is calculated using this.

Here, the relationship between the X-ray dose applied to the detection panels 31, 32 and 33 and each pixel value of the image represented by the image data Sn can be detected in advance. Therefore, from this relationship, a conversion table for converting the pixel value of the image represented by the image data Sn into the X-ray dose is created, and the distance d is calculated by referring to this conversion table.
position of an image represented by the acquired image data Sn in n (x, y) image from the pixel value in the I _dn (x,
y) can be obtained.

[Equation 2] However, N: number of image data Sn f: spatial frequency ψ (fx, fy ≠ 0): spatial frequency component I _dn (fx, fy) of phase shift amount when frequency is not 0: I _dn (x, y) Spatial frequency component of

The phase shift amount, that is, the phase difference ψ (x, y) can be calculated by inverse Fourier transforming the spatial frequency component of the phase shift amount. here,
Since the phase difference ψ (x, y) takes a value in the range of 0 to 2π,
By assigning the calculated phase difference ψ (x, y) to an 8-bit value, for example, image data Sp representing a phase contrast image can be obtained.

In this case, the transmittance intensity is negligible A
Although it is assumed that (x, y) is close to 1, the phase shift amount can be calculated using a similar algorithm for a thick object.

Next, the operation of the first embodiment will be described. FIG. 3 is a flowchart showing the operation of the first embodiment. First, the radiation source 11 is driven so that the synchrotron radiation light is reflected by the crystal 13, whereby monochromatic X-rays 12 are emitted from the X-ray source 10 and X-rays the subject 21.
The line 12 is irradiated (step S1). Then, at the plurality of photographing positions, the reading means 34, 35, 36 read the electric signals of the plurality of detection elements constituting the detection panels 31, 32, 33, and the image data Sn at each photographing position.
Is acquired (step S2).

The acquired image data Sn is input to the arithmetic unit 40, where it is subjected to enlarging / reducing processing, and as described above, the image data Sp representing the phase contrast image is generated (step S3), and the processing ends. To do. The image data Sp is used for reproduction by a monitor or print output by a printer.

As described above, in the first embodiment,
Since the X-ray image is acquired by using the detection panel having a higher sensitivity at the photographing position farther from the subject 21, even the detection panel 33 at the photographing position farther from the subject 21 has the detection panel closer to the photographing position. 31
Similarly to, the X-ray 12 can be accurately detected.
Therefore, the densities of the plurality of X-ray images can be made substantially equal, and thus the image data Sp representing the phase contrast image can be accurately generated. Further, since it is not necessary to adjust the gains of the detection panels 31, 32, 33 and the density of the obtained X-ray image, it is possible to efficiently detect the X-ray image for obtaining the phase contrast image with high accuracy. it can.

Next, a second embodiment of the present invention will be described. FIG. 4 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the second embodiment of the present invention is applied. Since the second embodiment is different from the first embodiment only in the structure of the recording unit, the same structures as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. Omit it.

The recording unit 130 in the second embodiment is
It is provided with first and second photographing units 130A and 130B.

The first and second photographing units 130A,
Reference numeral 130B denotes a detection panel 131A, 131B composed of a fluorescent substance and a plurality of detection elements arranged two-dimensionally, and a detection panel 131A, 131B in a direction parallel to the traveling direction of the X-ray 12 transmitted through the subject 21. Moving means 132A, 132B for moving and detection panels 131A, 13
Read-out means 133A, 1 for obtaining image data Sna, Snb at each photographing position by reading electric signals from a plurality of detection elements constituting detection panels 131A, 131B at a plurality of photographing positions set in advance on the movement path of 1B.
33B.

The moving means 132A, 132B extend in the direction parallel to the traveling direction of the X-rays 12 and the supporting portions 135A, 135B formed with the female screw portion for supporting the detection panels 131A, 131B. Support part 135A,
Male screw portions 136A, 13 that are screwed into female screw portions of 135B
6B and a motor 13 for rotating the male screw portions 136A, 136B around a rotation shaft extending in the traveling direction of the X-ray 12.
7A, 137B, and control units 138A, 138B for controlling driving and stopping of the motors 137A, 137B. Then, the motor 1 is controlled by the control units 138A and 138B.
By driving 37A and 137B, the male screw portion 136
A and 136B are rotated, and the support portions 135A and 135B, that is, the detection panels 131A and 13B, are rotated according to the rotation direction.
1B moves toward the subject 21 and away from the subject 21.

Further, the first and second photographing units 13
The moving means 13 is provided at each photographing position in 0A and 130B.
Detection panel 131A moved by 2A and 132B,
Position sensors 51A, 52A, 51B, and 52B that detect that 131B has reached each of the photographing positions are provided. Position sensors 51A, 52A, 51B, 52B
Outputs a detection signal when the detection panels 131A and 131B reach the photographing position, which is read out by the reading means 133A and 1A.
33B is input. The reading means 133A and 133B are
When the detection signal is input, the detection panels 131A and 131
The electric signals are read from the plurality of detection elements constituting B to obtain the image data Sna and Snb at the photographing position.

In the second embodiment, in the first and second photographing units 130A and 130B,
Position sensors 51A, 52A and 51 are provided at two locations, respectively.
Since B and 52B are provided, four image data Sn (S1 to S4) are obtained at four image capturing positions.

Here, in the second embodiment, the sensitivity of the detection panel 131B constituting the photographing unit 130B on the side far from the subject 21 is the same as that of the detection panel 131A constituting the photographing unit 130A on the side closer to the subject 21. It is higher than the sensitivity. Specifically, the detection panel 13
The phosphor of 1B is made thicker than the phosphor of the detection panel 131A, and the content of the latter phosphor is made larger than that of the former phosphor. As a result, the X-ray 12 can be accurately detected even at a position away from the subject 21, and the diffraction image can also be accurately detected.

The arithmetic unit 40, as in the first embodiment,
The size of the X-ray image represented by the image data Sn is represented by the image data Sn so that it is the same as the size of the X-ray image represented by the image data S1 obtained at the imaging position closest to the subject 21. Reduction processing is performed on the X-ray image, and image data Sp representing a phase contrast image is obtained.

Next, the operation of the second embodiment will be described. FIG. 5 is a flowchart showing the operation of the second embodiment. First, the radiation source 11 is driven so that the synchrotron radiation light is reflected by the crystal 13, whereby monochromatic X-rays 12 are emitted from the X-ray source 10 and X-rays the subject 21.
The line 12 is irradiated (step S11). At the same time,
First, shooting is performed in the first shooting unit 130A. That is, the control unit 138A drives the motor 137A to move the detection panel 131A in a direction away from the initial position closest to the subject 21 (step S1).
2). The position sensors 51A and 52A are moved according to the movement.
At the timing when the detection signal from the
The electric signals of the plurality of detection elements constituting the detection panel 131A are read by the 33A to obtain the image data Sna at each photographing position (step S13).

In the first photographing unit 130A, the photographing is performed in the second photographing unit 130B after the photographing at the photographing position farthest from the subject 21.
That is, the control unit 138B drives the motor 137B to move the detection panel 131B in a direction away from the initial position closest to the subject 21 (step S14).
Then, at the timing when the detection signals from the position sensors 51B and 52B are input according to the movement, the reading means 133B.
Thus, the electric signals of the plurality of detection elements constituting the detection panel 131B are read to obtain the image data Snb at each photographing position (step S15).

The acquired image data Sna and Snb are input to the arithmetic unit 40, where the image data Sp representing the phase contrast image is generated (step S16) as in the first embodiment, and the process ends. The image data Sp is used for reproduction by a monitor or print output by a printer.

In the second embodiment, after the first photographing unit 130A has photographed,
Although the second photographing unit 130B is photographing, the first and second photographing units 130A and 130B
At the same time, the images may be taken simultaneously.

Further, in the second embodiment, two image pickup units are used, but three or more image pickup units may be used. In this case, a detection panel having a higher sensitivity is used as the detection panel used in the subsequent photographing unit.

Further, in the first and second embodiments, the sensitivity of the detection panel is set to be higher at the photographing position farther from the subject 21, but the detection panels are further arranged according to the number of detection panels in the preceding stage. The sensitivity of may be set.

Further, in the first embodiment, the X-ray images are acquired by the detection panels 31, 32, 33, but instead of the detection panels 31, 32, 33, the third panel shown in FIG. As in the embodiment, a plurality of (here, three) stimulable phosphor sheets 61, 62, 63 may be used.
In this case, a stimulable phosphor sheet arranged at a photographing position farther from the subject 21 has a thicker phosphor and higher sensitivity.

The stimulable phosphor sheets 61, 62, 6
When the X-ray image is accumulated and recorded on the sheet 3, each sheet 61,
62 and 63 are irradiated with excitation light to generate stimulated emission light,
A plurality of image data Sn representing an X-ray image is obtained by the reading unit 70 that photoelectrically reads the stimulated emission light.
The obtained plurality of image data Sn are input to the arithmetic unit 40 as in the first embodiment, and the image data Sp representing the phase contrast image is generated.

In each of the above embodiments, the radiation source 1
Although the one that emits the synchrotron radiation is used as No. 1, it is not limited to this. Also, subject 2
Although a monochromatic X-ray is used as the X-ray 12 for irradiating 1
It is not limited to monochromatic X-rays.

Further, in each of the above-described embodiments, the subject 21 is irradiated with the X-rays 12, but radiation other than X-rays (α rays, β rays, γ rays, electron rays, ultraviolet rays, etc.) is used. May be.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which a radiation image capturing apparatus according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining the thickness of a detection panel.

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the second embodiment of the present invention is applied.

FIG. 5 is a flowchart showing the operation of the second embodiment.

FIG. 6 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the third embodiment of the present invention is applied.

[Explanation of symbols]

10 X-ray source 11 radiation sources 12 X-ray 13 crystals 20 Subject support 21 subject 30,130 Recording section 31, 32, 33, 131A, 131B detection panel 33, 133A, 133B reading means 40 arithmetic unit 51A, 51B, 52A, 52B Position sensor 61,62,63 Accumulative phosphor sheet 70 Reader 130A, 130B shooting unit 132A, 132B moving means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01T 1/20 A61B 6/00 350A F term (reference) 2G088 EE01 EE27 FF02 GG19 GG20 GG21 GG25 JJ05 JJ24 KK32 LL08 LL15 4C093 AA30 CA04 CA29 EA20 EB17 EB18 EB21 EC29 FA32 FA53 FF13 FF33

Claims (10)

[Claims] 1. A radiographic image capturing method for acquiring a plurality of radiographic images by irradiating a subject with radiation and detecting the radiation that has passed through the subject at a plurality of capturing positions having different distances from the subject, A radiographic image capturing method, characterized in that the radiographic image is acquired by a two-dimensional detector having a higher sensitivity at a capturing position farther from the subject. 2. The radiographic image capturing method according to claim 1, wherein the two-dimensional detector has a higher transmittance of the radiation at an image capturing position closer to the subject. 3. The radiographic image capturing method according to claim 1, wherein a phase contrast image is generated based on the plurality of radiographic images. 4. The sensitivity is higher at a photographing position farther from the subject, which is arranged at each of a plurality of photographing positions having different distances from the subject and detects radiation transmitted through the subject at the plurality of photographing positions. A radiation image capturing apparatus comprising: a plurality of two-dimensional detectors, wherein a plurality of radiation images are acquired by detecting the radiation transmitted through the subject by the two-dimensional detectors at the plurality of capturing positions. 5. The radiographic image capturing apparatus according to claim 4, wherein the plurality of two-dimensional detectors have a higher transmittance of the radiation at an image capturing position closer to the subject. 6. The radiographic image capturing apparatus according to claim 4, further comprising image generating means for generating a phase contrast image based on the plurality of radiographic images. 7. A method for detecting radiation that has passed through an object 2
A two-dimensional detector, moving means for moving the two-dimensional detector in the optical axis direction of the radiation, and arrival of the two-dimensional detector at a plurality of predetermined imaging positions on the moving path by the moving means. When the two-dimensional detector reaches each of the photographing positions based on a detection result of the plurality of photographing units, which are provided with a position sensor for detecting and are sequentially arranged in the optical axis direction, and the position sensor. Read-out means for reading a signal from the two-dimensional detector to acquire a plurality of radiation images, and the two-dimensional detector of the imaging unit arranged away from the subject has higher sensitivity. A radiographic image capturing device. 8. The radiographic image capturing apparatus according to claim 7, wherein the reading unit is provided for each of the plurality of image capturing units. 9. The radiographic image capturing method according to claim 7, wherein the two-dimensional detector of the image capturing unit arranged closer to the subject has a higher transmittance of the radiation. apparatus. 10. Based on the plurality of radiographic images,
The radiographic image capturing apparatus according to claim 7, further comprising image generating means for generating a phase contrast image.