JP2000193609A - Radiation tomograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equipment capable of obtaining small-sized and high- contrast radiation tomograms. SOLUTION: A radiation source 20, a sample stand 30 and a two-dimensional radiation detector 40 are arranged respectively, so that a phase contrast image of a radiation permeating a sample 10 detected by the two-dimensional radiation detector 40. The sample stand 30 is tilted or rotated with a sample origin S as the center, and the two-dimensional radiation detector 40 is tilted or rotated with a detector origin D as the center by being controlled by a scanning part 60. A focus F of the radiation source 20, the sample origin S and the detector origin D are arranged on a straight line. Moreover besides, respective directions of the sample stand 30 and the two-dimensional radiation detector 40 are maintained mutually parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation tomography apparatus for detecting radiation transmitted through a sample with a two-dimensional radiation detector and obtaining a radiation tomographic image of the sample.

[0002]

2. Description of the Related Art A radiation tomography apparatus uses a non-destructive method for soldering a component, such as a surface mounting with a J-lead terminal, a flip chip mounting, or a bump mounting of a passive chip component, whose connection portion cannot be observed from an upper surface to a substrate. It is used for inspection and the like. As such a radiation tomography apparatus, for example, Japanese Patent Application Laid-Open No. Hei 2-501411, Japanese Unexamined Patent Publication No. Hei.
Japanese Patent Application Laid-Open Nos. 172763 and 9-61378 are known.

FIG. 9 is a diagram illustrating the configuration of a conventional radiation tomography apparatus. A sample (subject) 1 is fixed on a sample table 3, and a radiation source (for example, an X-ray source) 2 and a two-dimensional radiation detector (for example, an X-ray photographic film) 5 are arranged with the sample 1 interposed therebetween. . Then, the radiation source 2 or the two-dimensional radiation detector 4 rotates or translates. At this time, the focus F of the radiation source 2, the sample origins S and 2 of the sample 1
The detector origin D of the three-dimensional radiation detector 4 is maintained so as to be on a straight line. With such rotational tomography,
A radiation tomographic image parallel to the imaging surface of the two-dimensional radiation detector 5 and focused on a focal plane P passing through the sample origin S is obtained.

[0004] In the field of medical diagnosis, an X-ray CT apparatus is used. This X-ray CT apparatus can also be used for industrial nondestructive inspection. However, the X-ray CT apparatus is unsuitable for obtaining a tomographic image along a plane of a flat sample such as a printed circuit board. Therefore, for nondestructive inspection of a flat sample such as a printed circuit board, a rotational tomography method is used in a radiation tomography apparatus having the configuration shown in FIG.

[0005]

However, the above conventional radiation tomography apparatus rotates or translates an X-ray source connected to a high-voltage cable or an X-ray generator having a built-in high-voltage power supply with high mechanical accuracy. Because of the necessity, there is a problem that the structure becomes large and complicated.

[0006] The above-mentioned conventional radiation tomography apparatus includes:
Since a radiation tomographic image is obtained by using the radiation absorption distribution of the sample, there is a problem that a high-contrast radiation tomographic image cannot be obtained for a sample having a small change in radiation absorption.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a radiation tomography apparatus which is small and can obtain a high-contrast radiation tomographic image.

[0008]

According to the present invention, there is provided a radiation tomography apparatus comprising: (1) a radiation source for emitting radiation toward a sample; (2) a sample stage for fixing the sample; and (3) a sample stage. (4) a two-dimensional radiation detector for detecting a phase contrast image of transmitted radiation, and (4) a first linear detector passing through a focal point of the radiation source while maintaining the orientations of the sample stage and the two-dimensional radiation detector parallel to each other. Scanning means for tilting or rotating the sample stage about the point (2) and tilting or rotating the two-dimensional radiation detector about the second point on the straight line for scanning.

In this radiographic imaging apparatus, a radiation source,
Each of the sample stage and the two-dimensional radiation detector is arranged such that a phase contrast image of the radiation transmitted through the sample can be detected by the two-dimensional radiation detector. Controlled by the scanning means, the sample stage is tilted or rotated about a first point, and the two-dimensional radiation detector is tilted or rotated about a second point. The focal point, the first point and the second point of the radiation source lie on a straight line. The directions of the sample table and the two-dimensional radiation detector are maintained parallel to each other. That is, a rotation axis passing through the first point and perpendicular to the sample stage,
Are always parallel to the rotation axis perpendicular to the imaging surface of the two-dimensional radiation detector, and the rotation angles of the sample stage and the two-dimensional radiation detector around each rotation axis are always the same.

The sample table and the two-dimensional radiation detector are scanned in such a positional relationship, and radiation is emitted from the radiation source. The radiation penetrates the sample fixed to the sample stage and reaches the imaging surface of the two-dimensional radiation detector. If the two-dimensional radiation detector is, for example, an X-ray film, a phase contrast image is recorded on the X-ray film. If the two-dimensional radiation detector is, for example, a radiation image intensifier, information output from the radiation image intensifier is accumulated, and a phase contrast image is formed based on the accumulated information. . The phase contrast image obtained in this way is focused on the focal plane in the sample, and has a high contrast in which the boundary of the sample is emphasized.

Another radiation tomography apparatus according to the present invention comprises: (1) a radiation source for emitting radiation toward a sample;
(2) a sample stage for fixing the sample, (3) a two-dimensional radiation detector for detecting a phase contrast image of radiation transmitted through the sample, and (4) one of the sample stage and the two-dimensional radiation detector. Scanning means that scans by tilting or rotating about a point on a straight line that passes through the focal point of the radiation source, and (5) detection by a two-dimensional radiation detector accompanying scanning of the sample stage or the two-dimensional radiation detector by the scanning means Based on the obtained phase contrast image, a phase contrast image on a virtual imaging plane corresponding to the focal plane in the sample is obtained, and a radiation tomographic image on the focal plane in the sample is obtained based on the phase contrast image on the virtual imaging plane. And an image analysis means for obtaining.

In this radiographic imaging apparatus, a radiation source,
Each of the sample stage and the two-dimensional radiation detector is arranged such that a phase contrast image of the radiation transmitted through the sample can be detected by the two-dimensional radiation detector. Controlled by the scanning means, one of the sample stage and the two-dimensional radiation detector tilts or rotates about a point on a straight line passing through the focal point of the radiation source.

The sample table or the two-dimensional radiation detector is scanned in such a positional relationship, and radiation is emitted from the radiation source. The radiation penetrates the sample fixed to the sample stage and reaches the imaging surface of the two-dimensional radiation detector. A phase contrast image detected by the two-dimensional radiation detector by the image analysis means is converted into a phase contrast image on a virtual imaging surface corresponding to a focal plane in the sample, and is converted into a phase contrast image on the virtual imaging surface. Based on this, a radiation tomographic image at the focal plane in the sample is obtained. The phase contrast image obtained in this way is focused on the focal plane in the sample, and has a high contrast in which the boundary of the sample is emphasized.

The image analysis means inputs the phase contrast image information output from the two-dimensional radiation detector and the sample position information indicating the direction of the sample, and accumulates them in relation to each other to perform measurement. After the end, a radiation tomographic image in which each of a plurality of focal planes in the sample is focused may be obtained.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

First Embodiment First, a radiation tomography apparatus according to a first embodiment will be described. FIG.
1 is a configuration diagram of a radiation tomography apparatus according to a first embodiment. This radiation tomography apparatus includes a radiation source 20, a sample stage 30, a two-dimensional radiation detector 40, a detector stage 50, a scanning unit 60, and an image analysis unit 70. The radiation source 20 emits radiation toward the sample 10 which is a subject. The sample stage 30 fixes the sample 10. Detector base 50
Fixes the two-dimensional radiation detector 40. The two-dimensional radiation detector 40 detects a phase contrast image of radiation transmitted through the sample 10, and includes, for example, an X-ray photographic film, an imaging plate (stimulable luminescent material), a radiation image intensifier, and a CCD image. A semiconductor image sensor such as a sensor, or a radiation image sensor combining any of these with a scintillator is preferably used.

The sample stage 30 can be freely tilted or rotated around a sample origin S on the z-axis passing through the focal point F of the radiation source 20, and the detector stage 50 has a detector origin on the z-axis. It can be tilted or rotated around D. Scanning unit 60
The sample table 30 and the detector table 50 are maintained while keeping the respective directions of the sample table 30 and the detector table 50 parallel to each other.
Each is scanned while tilted or rotated. That is,
Even when scanning is performed by the scanning unit 60, the rotation axis C1 passing through the sample origin S and perpendicular to the surface of the sample table 30 and the rotation axis C2 passing through the detector origin D and perpendicular to the surface of the detector table 50 are always parallel,
In addition, the rotation angle of the sample table 30 around the rotation axis C1 and the rotation angle of the detector table 50 around the rotation axis C2 are always the same.

The image analysis unit 70 accumulates the radiation images detected by the two-dimensional radiation detector 40 in accordance with the scanning of the sample stage 30 and the detector stage 50 by the scanning unit 60 for tilting or rotation, respectively. A radiation tomographic image of the sample 10 is obtained based on the radiation image. When the two-dimensional radiation detector 40 is an X-ray photographic film or an imaging plate, the image analysis unit 70 is unnecessary.

The distance between the focal point F of the radiation source 20 and the sample origin S is R 1 ′, the distance between the sample origin S and the detector origin D is R 2 ′, and the imaging surface of the two-dimensional radiation detector 40. 40
The distance between A and the detector origin D is denoted by b, and the imaging surface 40A
Assuming that the distance between the focal plane P1 parallel to and the sample origin S is a, this distance a is

(Equation 1) Is satisfied, a radiation tomographic image focused on the focal plane P1 is obtained. Furthermore, this radiation tomography apparatus
A phase contrast imaging method described later is adopted, and the radiation image detected by the two-dimensional radiation detector 40 is a phase contrast image.

Next, the configurations of the sample stage 30 and the detector stage 50 in the radiation tomography apparatus according to the present embodiment will be described. Since the same configuration can be adopted for each of the sample table 30 and the detector table 50, the sample table 30 will be described below.

FIG. 2 is a configuration diagram of the sample stage 30 in the present embodiment. The sample table 30 shown in FIG.
A pair of support members 312 are fixed on the
A first rectangular frame 313 is provided between the pair of support members 312, and a second rectangular frame 31 is provided inside the first rectangular frame 313.
4 are provided. The sample 1 is placed in the second rectangular frame 314.
0 is fixed. The support member 312 includes a first rotation drive unit 315 that tilts the first rectangular frame 313 about the x-axis.
Is provided. The first rectangular frame 313 is provided with a second rotation drive section 316 that tilts the second rectangular frame 314 about the y-axis. Here, the x-axis and y
The axis has the origin S as the origin. In the sample stage 30, the first rotation driving unit 315
Then, each of the second rotation drive unit 316 rotates and the first rectangular frame 313 and the second rectangular frame 314 incline.

FIG. 3 is another configuration diagram of the sample stage 30 in the present embodiment. In the sample table 30 shown in this figure, an annular rotating frame 323 is provided on an annular fixed frame 321 via a ball bearing 322. The sample 10 is fixed to the rotating frame 323. The rotation drive unit 324 is connected to the fixed frame 32.
1, rotates under the control of the scanning unit 60, and rotates the rotating frame 323 via the gear 325 to rotate the rotating shaft C 1.
Rotate around. Note that the configurations shown in FIGS. 2 and 3 may be combined. In this case, the sample 10 can be tilted and rotated.

Next, a method of phase contrast imaging employed by the radiation tomography apparatus according to the present embodiment will be described. FIG. 4 is a diagram illustrating a method of phase contrast imaging. In this figure, each of the rotation axes C1 and C2 is parallel to the z-axis. Radiation source 2
The distance between the zero focal point F and the focal plane P1 is R1, and the distance between the focal plane P1 and the imaging plane 40A of the two-dimensional radiation detector 40 is R2. The phase contrast imaging method detects the phase contrast image by the two-dimensional radiation detector 40 by appropriately setting the values of the distances R1 and R2, and detects the phase contrast image even for the sample 10 having a small change in radiation absorption. A radiation tomographic image with an enhanced contour can be obtained.

The complex radiation absorption distribution q (x) of the sample 10 is

(Equation 2) It is represented by the following expression. Note that, for simplicity of explanation,
The radiation absorption distribution q (x) is represented as a function of only the coordinate x in the x-axis direction perpendicular to the z-axis. φ (x) is a term relating to phase shift, and μ (x) is a term relating to absorption. If these terms are sufficiently small, the above equation (2) becomes

(Equation 3) It is represented by the following formula.

If the radiation emitted from the radiation source 20 and transmitted through the sample 10 and reaches the imaging surface 40A of the two-dimensional radiation detector 40 follows the theory of Fresnel diffraction, the imaging surface 40
The radiation intensity distribution I (Mx) on A is given by the Fresnel-Kirchhoff integral

(Equation 4) It is represented by the following formula. Here, * is a convolution operation symbol, and F represents Fourier transform. u is sample 10
, Λ is the wavelength of radiation, and M is the projection magnification.

When this radiation intensity distribution I (M · x) is subjected to Fourier transform, a contrast transfer function F (u / M) on a spatial frequency is given by

(Equation 5) It is represented by the following formula. Where δ (u) is the delta function, m (u) is the Fourier transform of μ (x), and Φ (u) is φ
This is the Fourier transform of (x).

FIG. 5 shows cosχ and cosχ appearing in the above equation (5).
sinχ each,

(Equation 6) Is a graph plotted against a variable u ′ represented by As can be seen from this graph, the value of cosχ representing the absorption contrast is largest when the value of the distance R2 is 0, and decreases as the value of the distance R2 increases. On the other hand, the value of sinχ representing the phase contrast is 0 when the value of the distance R2 is 0, and increases as the value of the distance R2 increases.

Here, the absorption of the sample 10 is small, and m
If the approximation (u) = 0 is possible and the value of the variable u ′ is small, the above equation (4)

(Equation 7) It is approximated by the following equation. Here, Re is the classical electron radius, and ρ (x) is the electron density distribution. As described above, the radiation intensity distribution I (x) on the imaging surface 40A is the electron density distribution ρ
It is expressed by the second derivative of (x).

From the above, when the change in the electron density is large, the phase contrast becomes high. For example, even if the difference between the electron densities of the solution and the bubbles therein is small, if the change in the electron density is large near the boundary between the two, a phase contrast in which the boundary is enhanced can be obtained. This does not depend on the radiation wavelength λ, and it is not necessary that the radiation be monochromatic, so that any radiation source 20 can be used. According to the above equation (7), R2
The larger the value of / (1 + R2 / R1), the higher the phase contrast at the boundary. This phenomenon will be described with reference to FIG. 6. The radiation emitted from the radiation source is absorbed by the sample and is bent at the boundary where the change in electron density is large. Therefore, on the imaging surface of the two-dimensional radiation detector, Radiation becomes strong near the boundary, and a radiation tomographic image with an enhanced contour is obtained.

When the value of the variable u 'is large, such as when the internal structure of the sample 10 is small and the spatial frequency is large, or when the value of R2 / (1 + R2 / R1) is large, the above (7)
It cannot be approximated by the formula. The value of sinχ representing the phase contrast is the radiation wavelength λ, the distances R1 and R2.
And depends on the size of the internal structure of the sample 10,
It can be the maximum or zero. s
When the value of inχ is zero, the internal structure of the sample 10 cannot be seen. Also, the value of sinχ may be a negative value, in which case a negative contrast is obtained.

Therefore, the radiation wavelength λ and the distance R 1
, R2 should be appropriately set in accordance with the expected size of the internal structure of the sample 10 so that a radiation tomographic image having a desired phase contrast is obtained.
In particular, it is preferable that the value of the variable u ′ is set to be small and can be approximated by the above equation (7), since a radiation tomographic image having a high phase contrast can be obtained. Although the radiation does not need to be monochromatic, it is necessary to have a spatial coherence because a change in the radiation wavefront is recorded. .

For example, when the central wavelength λ of the radiation is 0.05 n
In order to make the value of sinχ representing the phase contrast about 0.3 when m is about 0.3, if the size of the internal structure of the sample 10 to be observed is about 10 μm, the distance R1 is about 250 μm.
mm and the distance R2 may be about 1000 mm. Conversely, if the approximate size of the internal structure of the sample 10 to be observed is known in advance, the distance is set so that the contrast of the spatial frequency is maximized, that is, χ (u) = π / 2. R1 and R2 may be adjusted. For example, when the central wavelength λ of the radiation is 0.02 nm, the approximate size of the internal structure of the sample 10 to be observed is 5
μm, the distance R1 is about 800 mm, and the distance R2
Should be about 2900 mm, and at this time, the phase contrast becomes maximum.

As described above, in order to obtain a high phase contrast image by employing the phase contrast imaging technique, the distance from the radiation source 10 to the detector base 50 is long and several meters are required. Therefore, if the conventional radiation tomography apparatus (FIG. 9) attempts to adopt this method, the rotational diameter or the parallel movement range of the radiation source or the two-dimensional radiation detector becomes very large, so that higher mechanical accuracy is obtained. Is required, resulting in a larger and more complicated structure. However, in the radiation tomography apparatus according to the present embodiment, as shown in FIGS. 1 to 3, the sample stage 30 is tilted or rotated around the sample origin S, and the detector stage 50 is set to the detector origin D. Since it is tilted or rotated to the center, high mechanical accuracy is not required as compared with the conventional radiation tomography apparatus, and the radiation source 20 is not required.
Does not become large in a direction perpendicular to a straight line (z axis) connecting the focal point F and the detector origin D to each other, and does not have a complicated structure.

In the radiation tomography apparatus according to the present embodiment, the radiation source 20, the sample stage 30, and the detector stage 50 are arranged so that a high phase contrast image can be obtained as described above. The sample stage 30 is tilted or rotated around the sample origin S under the control of the scanning unit 60, and the detector stage 50 is tilted or rotated around the detector origin D. At this time, the focus F of the radiation source 20, the sample origin S, and the detector origin D are on the same straight line (z axis). Further, even if the scanning is performed by the scanning unit 60, the sample origin S
The rotation axis C1 passing through the sample table 30 and perpendicular to the surface of the sample table 30, and the rotation axis C2 passing through the detector origin D and perpendicular to the surface of the sample table 50 are always parallel to each other. The rotation angle is always the same as the rotation angle of the detector base 50 around the rotation axis C2.

The phase contrast image of the sample 10 fixed to the sample table 30 is fixed to the detector table 50 during the period in which the sample table 30 and the detector table 50 are being scanned for tilting or rotation. Two-dimensional radiation detector 40
Is imaged. The image analysis section 70 accumulates the captured phase contrast image, and obtains a radiation tomographic image of the sample 10 based on the accumulated phase contrast image. The radiation tomographic image obtained at this time is an image which is parallel to the imaging surface 40A of the two-dimensional radiation detector 40 and is focused on the focal plane P1 at a distance a (formula (1)) from the sample origin S. , The boundary of the sample 10 has high contrast.

(Second Embodiment) Next, a radiation tomography apparatus according to a second embodiment will be described. FIG.
It is a lineblock diagram of the radiation tomography apparatus concerning a 2nd embodiment. In the radiation tomography apparatus according to the present embodiment, the point that the two-dimensional radiation detector 40 remains fixed without tilting or rotating, and the necessary processing corresponding thereto is performed by the image analysis unit 7.
1 is different from that according to the first embodiment.

In this embodiment, the method of phase contrast imaging is adopted, and the radiation source 20 and the sample table 3 are used.
Each of the zero- and two-dimensional radiation detectors 40 is arranged so as to obtain an image with a high phase contrast as described in the first embodiment. The sample stage 30 is controlled by the scanning unit 60 to tilt or rotate around the sample origin S on the z-axis. The two-dimensional radiation detector 40 is not scanned and remains fixed, and has a detector origin D on the z-axis.
In the present embodiment, the two-dimensional radiation detector 40 includes the imaging surface 4
A device that captures a phase contrast image of radiation on 0A and outputs information of the phase contrast image as an electric signal is used. For example, a radiation image intensifier, a CCD image sensor, or the like is preferably used.

The image analyzer 71 includes a coordinate converter 711 and an image storage / synthesis unit 712. Coordinate converter 711
The phase contrast image information output from the two-dimensional radiation detector 40 and the sample position information output from the scanning unit 60 are input. The sample position information indicates the azimuth (the direction of the rotation axis C1 and the rotation angle around the rotation axis C1) of the sample 10 due to the inclination and rotation of the sample table 30.
The coordinate conversion unit 711 virtualizes the virtual imaging plane P2 based on the sample position information. The virtual imaging plane P2 is separated from the detector origin D by a distance b obtained by substituting the distance a between the focal plane P1 in the sample 10 and the sample origin S into the equation (1). It is parallel to the plane P1. Then, the coordinate conversion unit 711 converts the phase contrast image of the radiation on the imaging surface 40A into a phase contrast image on the virtual imaging surface P2 based on the phase contrast image information output from the two-dimensional radiation detector 40. . The image accumulation / synthesis unit 712 includes:
By accumulating the phase contrast image on the virtual imaging plane P2,
On the basis of the accumulated phase contrast image, the sample 1
A radiation tomographic image focused on the focal plane P1 in 0 is obtained.

(Third Embodiment) Next, a radiation tomography apparatus according to a third embodiment will be described. FIG.
It is a lineblock diagram of the radiation tomography apparatus concerning a 3rd embodiment. The radiation tomography apparatus according to the present embodiment is different from that according to the second embodiment in that the image analysis unit 72 obtains a radiation tomographic image focused on each of the plurality of focal planes P1 in the sample 10.

The present embodiment also employs a phase contrast imaging technique, in which the radiation source 20, the sample stage 3
Each of the zero- and two-dimensional radiation detectors 40 is arranged so as to obtain an image with a high phase contrast as described in the first embodiment. The sample stage 30 is controlled by the scanning unit 60 to tilt or rotate around the sample origin S on the z-axis. The two-dimensional radiation detector 40 is not scanned and remains fixed, and has a detector origin D on the z-axis.
In the present embodiment, the two-dimensional radiation detector 40 includes the imaging surface 4
A device that captures a phase contrast image of radiation on 0A and outputs information of the phase contrast image as an electric signal is used. For example, a radiation image intensifier, a CCD image sensor, or the like is preferably used.

The image analysis unit 72 includes an image / detector position information storage unit 721 and a coordinate conversion / image storage / synthesis unit 722. The image / detector position information storage unit 721 receives the phase contrast image information output from the two-dimensional radiation detector 40 and the sample position information output from the scanning unit 60, and stores them in association with each other. . The sample position information indicates the azimuth (the direction of the rotation axis C1 and the rotation angle around the rotation axis C1) of the sample 10 due to the inclination and rotation of the sample table 30.

The coordinate transformation / image storage / synthesis unit 722 is provided with the second
It has substantially the same operation as the operation performed by the coordinate conversion section 711 and the image accumulation / combination section 712 in the embodiment. That is, the coordinate conversion / image storage / synthesis unit 722 takes out, after the end of the measurement, the one corresponding to the specific sample position information from the large number of phase contrast image information stored in the image / detector position information storage unit 721. Further, the coordinate conversion / image accumulation / synthesis unit 722 imagines a virtual imaging plane P2 corresponding to the specific sample position information. Then, the coordinate conversion / image storage / synthesis unit 722 converts the extracted phase contrast image information into a phase contrast image on the virtual imaging plane P2, and focuses on the focal plane P1 in the sample 10 based on the phase contrast image. To obtain a radiation tomographic image that matches. The coordinate conversion / image accumulation / synthesis unit 722 can obtain a radiation tomographic image in which each of a plurality of focal planes in the sample 10 is in focus by performing the above analysis on each sample position information.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the second and third embodiments, the two-dimensional radiation detector 40 is fixed by tilting or rotating the sample table 30.
0 may be fixed and the two-dimensional radiation detector 40 may be tilted or rotated. The processing in the image analysis unit in this case is the same.

[0044]

As described above in detail, according to the present invention, the radiation source, the sample stage and the two-dimensional radiation source are arranged so that the phase contrast image of the radiation transmitted through the sample is detected by the two-dimensional radiation detector. Since each detector is arranged, even for samples with small changes in radiation absorption,
A high-contrast radiation tomographic image can be obtained.

Further, if a phase contrast image is detected in the configuration of the conventional radiation tomography apparatus, higher mechanical accuracy is required, and a larger and more complicated structure is required. Since the phase contrast image is stored by tilting or rotating the sample stage and / or the two-dimensional radiation detector about a predetermined point, compared to a conventional radiation tomography apparatus,
No high mechanical accuracy is required, the size does not increase in the direction perpendicular to the straight line connecting the radiation source and the two-dimensional radiation detector, and the structure does not become complicated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a radiation tomography apparatus according to a first embodiment.

FIG. 2 is a configuration diagram of a sample stage.

FIG. 3 is another configuration diagram of the sample stage.

FIG. 4 is a diagram illustrating a method of phase contrast imaging.

FIG. 5 is a graph in which cos co and sinχ appearing in a contrast transfer function F (u) are plotted against a variable u ′.

FIG. 6 is a diagram illustrating that phase contrast increases at a boundary between samples.

FIG. 7 is a configuration diagram of a radiation tomography apparatus according to a second embodiment.

FIG. 8 is a configuration diagram of a radiation tomography apparatus according to a third embodiment.

FIG. 9 is a diagram illustrating a configuration of a conventional radiation tomography apparatus.

[Explanation of symbols]

10 ... sample, 20 ... radiation source, 30 ... sample stand, 40 ... 2
Dimensional radiation detector, 50: detector stand, 60: scanning unit, 7
0-72: Image analysis unit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiichi Tanaka 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture F-term in Hamamatsu Photonics Co., Ltd. 2G001 AA01 BA11 CA01 DA01 DA09 GA13 HA08 HA12 HA13 HA14 HA15 HA20 JA06 JA08 JA11 JA20

Claims (2)

[Claims] A radiation source for emitting radiation toward a sample; a sample stage for fixing the sample; a two-dimensional radiation detector for detecting a phase contrast image of radiation transmitted through the sample; While maintaining the orientation of each of the two-dimensional radiation detectors parallel to each other, the sample stage is tilted or rotated around a first point on a straight line passing through the focal point of the radiation source, and a second point on the straight line is rotated. Scanning means for scanning the two-dimensional radiation detector by tilting or rotating the two-dimensional radiation detector about a point. 2. A radiation source for emitting radiation toward a sample, a sample stage for fixing the sample, a two-dimensional radiation detector for detecting a phase contrast image of radiation transmitted through the sample, Scanning means for scanning by tilting or rotating any one of the two-dimensional radiation detectors about a point on a straight line passing through the focal point of the radiation source; and the sample stage or the two-dimensional radiation by the scanning means. A phase contrast image on a virtual imaging surface corresponding to a focal plane in the sample is obtained based on a phase contrast image detected by the two-dimensional radiation detector in accordance with scanning of the detector, and a phase on the virtual imaging surface is obtained. Image analysis means for obtaining a radiation tomographic image at the focal plane in the sample based on a contrast image.