JPH10300693A - Small angle scattering electromagnetic ct method and small angle scattering x-ray ct device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small angle scattering X-ray CT device for observing the inside of a sample with an improved sensitivity. SOLUTION: A small angle scattering X-ray CT device disperses X rays from an X-ray source 1 into incidence X rays 3 with a specific wavelength by a spectral crystal 2 and applies them to a sample 4, X rays 5 being scattered at a small scattering angle of 2θ from the sample 4 are diffracted by an analyzer crystal 6, a group of scattered X-ray images are measured by obtaining the scattered X-ray image from a number of directions while rotating the sample 4 by a rotary stand 4a by a detector 7 for detecting a scattered X-ray image from the diffracted, scattered X rays 5, and the internal structure of a sample is observed with a high sensitivity from the small angle scattering X-ray CT image being formed by a group of scattered X-ray images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-angle scattered electromagnetic wave CT method for nondestructively observing the inside of a sample, and more particularly to a small-angle scattered X-ray CT suitable for observing the internal structure of a sample with high sensitivity.
Related to the device.

[0002]

2. Description of the Related Art A two-dimensional or three-dimensional object can be uniquely reproduced from an infinite set of projected images.
Although it has been mathematically proven by Radon, the practical use and widespread use of the method is by CT by G. Hounsfield.
Scanner development began in 1973. This is because it has been recognized that the nondestructive observation of the inside of an object by the CT method is very useful as a medical diagnosis.
After that, the CT method is widely used not only for X-rays but also for wavelengths of light ranging from radio waves to γ-rays, electron beams, and ultrasonic waves. Further, in recent years, the application range of the X-ray CT technology established for medical diagnosis has been expanded for defect inspection of various industrial materials.

As for the X-ray CT apparatus, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 63-243851 discloses a method of interpolating a transmission image by a moving means of a subject and a detector. FIG. 7 shows a conventional example of an X-ray CT apparatus represented by the above publication. After appropriately shaping the X-ray 3 from the X-ray source 1 with the slit 9 or the like, the sample 4 is irradiated, and the transmitted X-ray image 10 is measured by the detector 7. If a one-dimensional detector is used as the detector 7, the transmission X at each position in the direction perpendicular to the traveling direction of the X-ray can be obtained.
Line intensity can be measured. The X-ray absorption amount at each position can be calculated from the transmitted X-ray intensity. Next, the sample 4 is rotated by a predetermined angle using a turntable, and the transmitted X-ray image 10 is measured. This measurement is repeated until the rotation angle of the sample becomes 180 ° or 360 °. Rotation angle φ and transmission X of the measured sample
By performing an image reconstruction operation on the two-dimensional data consisting of the position x of the line image, the X-ray absorption coefficient μ of the cross section of the sample through which the X-ray has passed is obtained.
Is obtained. Since μ depends on the composition and density, defects and density distribution inside the sample can be observed nondestructively by the CT method.

On the other hand, incident X-rays are not only absorbed but also scattered by the sample. If there is an electron density difference distribution inside the sample, the scattered X-ray has an intensity distribution reflecting the electron density difference distribution with respect to the scattering angle. FIG. 8 shows an example of a small-angle scattering X-ray apparatus.
The X-ray 3 from the X-ray source 1 is appropriately shaped by the slit 9 or the like, and then the sample 4 is irradiated. X-rays scattered from the sample 4 at a scattering angle of 2θ are measured by the detector 7. From the intensity distribution of the scattered X-rays measured by scanning the detector 7 at the scattering angle, information on the size, volume ratio, and number density of voids and the like that are the cause of the electron density difference distribution inside the sample can be obtained.

[0005]

However, the above prior art has the following problems. In recent years, in ceramics, glass, and metal composite materials, materials in which particles, whiskers, and the like are dispersed have been studied for the purpose of improving heat resistance and mechanical strength. In these particle dispersion strengthening materials, the mechanical properties strongly depend on the dispersion state of the particles in the material. For this reason, there is a demand for easily measuring the dispersion state such as the particle size, volume ratio, number density, and distance between particles. And also in the prior art, the dispersion state of the particles can be calculated indirectly from the X-ray intensity distribution scattered at a small angle. However, since there are uncertain factors such as assuming the particle size distribution, there remains a problem in responding to a demand to observe the dispersion state of particles more directly.

On the other hand, according to the X-ray CT method, the density distribution inside the sample can be directly measured. However, since the information obtained is the X-ray absorption coefficient μ, the sensitivity is insufficient when there is not much difference in the density distribution. There is also a problem in that. Therefore, an object of the present invention is to provide a small-angle scattered electromagnetic wave CT method and a small-angle scattered X-ray CT apparatus capable of observing the inside of a sample with high sensitivity.

[0007]

A feature of the small-angle scattered electromagnetic wave CT method according to the present invention that achieves the above object is a small-angle scattered electromagnetic wave CT method for reconstructing an image inside an object using a group of projected images. The shadow image is a scattered electromagnetic wave image obtained by irradiating the object with an electromagnetic wave and scattered from the object at a small angle, and the projected image group is a group of the scattered electromagnetic wave images obtained from many directions.

On the other hand, a feature of the small-angle scattered X-ray CT apparatus according to the present invention is that the small-angle scattered X-ray CT apparatus irradiates an object with X-rays and obtains a scattered X-ray image scattered from the object at a small angle. A means for detecting a group of scattered X-ray images obtained from multiple directions of the scattered X-ray image is provided.

According to the present invention, a group of scattered X-ray images radiated by X-rays and scattered from the sample at a small angle is used as a group of projection images. It can be observed with high sensitivity.

Hereinafter, the reason will be described. First, a projection image P (x ′, φ) of a conventional X-ray CT using a transmission X-ray image of a sample as a projection image is represented by the following equation (see FIG. 9). P (x ', φ) = ln (I ₀ / I) = ∫ μ (x, y) dy' (Equation 1) where I ₀ is the incident X-ray intensity, I is the transmitted X-ray intensity, and μ is X
It is a linear absorption coefficient. Next, the scattered X-rays
(Number density: m, number of electrons per particle: N), and a projected image P ′ (x ′, φ) in the present invention using a scattered X-ray image (scattering angle: 2θ) as a projected image. ) Is represented by the following equation (FIG. 6).
reference). P '(x', φ) = (I '/ I ₀ ) = ∫ μ' (x, y) dy '(Equation 2) μ' = r ₀ ² Ω (Nψ) ² m where I ' Is the scattered X-ray intensity, r ₀ is the classical electron radius, Ω is the solid angle of the detection element, and ψ is the void outline function describing the scattered X-ray profile. Since μ ′ can be described in the same form as μ in Equation (1), the distribution of μ ′ at the X-ray incident cross section can be calculated by using a conventional X-ray CT image reconstruction algorithm. Using the atomic scattering factor (f = f1 + if2) in consideration of X-ray absorption, the minute changes δμ and δμ ′ at each position on the tomographic plane are expressed by the following equations. δμ ∝δ (n ・ f2)
(Equation 3) δμ′∝ δ (N ′ · f1) ² (Equation 4) Here, δ is a minute change amount, n is the number of atoms in a unit volume,
N ′ indicates the number of atoms per particle. From the above equation, δμ ′ including the squared term is more sensitive to changes in the number of atoms (n or N ′) than δμ, that is, small-angle scattering X using the group of scattered X-ray images according to the present invention. It can be seen that the X-ray CT enables measurement with higher sensitivity than the conventional small-angle scattering X-ray CT using a group of transmitted X-rays.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment shown in FIG. 1 will be described as a first embodiment.
FIG. 1 is a diagram showing a small-angle scattering X-ray CT apparatus according to one embodiment of the present invention. In the figure, an X-ray from an X-ray source 1 is split into an incident X-ray 3 having a predetermined wavelength by a spectral crystal 2 and then irradiated onto a sample 4 as an object. After the scattered X-rays 5 scattered by the sample 4 at the scattering angle 2θ are diffracted by the analyzer crystal 6, measurement is performed by the detector 7.

The dispersive crystal 2 and the sample 4 were set on rotating tables (2a, 4a) each driven by a stepping motor. An analyzer crystal 6 as a diffracting crystal was installed on a rotating table 6a driven by a stepping motor installed on an arm (not shown) whose rotating axis coincides with the rotating axis of the rotating table 4a of the sample 4. Further, the detector 7 was set on a stepping motor driven turntable 7a set on an arm whose rotation axis coincides with the turn axis of the turntable 6a of the analyzer crystal 6.

Each turntable (2a, 4a, 6a, 7a) has a computer 8
, The rotation is controlled so that the scattered X-rays 5 can be received by the detector 7 as desired. X-ray source 1 includes
A rotating anti-cathode X-ray generator was used. In addition, Cu is used for the rotating anode, and the accelerating voltage and current of the electrons are 6
0 kV and 200 mA were set. As the spectral crystal 2, a channel cut crystal of Si was used. As an X-ray diffraction surface,
Utilizing the symmetric reflection of the (220) plane, the surface was mirror-polished and then subjected to an etching treatment for the purpose of removing processing strain.

The X-rays incident on the spectral crystal 2 are reflected four times in the channel cut plane, and then X-rays of Cu-Kα1 (0.1540 nm) are emitted from the spectral crystal 2. By reflecting the X-ray many times in the channel cut, an output X-ray with high parallelism could be obtained. The reason for this is that the reflectivity of the X-rays by the crystal is R, and the X-ray intensity after reflecting the X-rays n times is Rn. In a region where R is small, Rn is substantially close to 0. For sample 4, an epoxy resin rod in which polystyrene having a particle size of 450 nm was dispersed and embedded was used. The analyzer crystal 6 contains Si as well as the spectral crystal.
The channel cut of (220) was used, and the number of X-ray reflections was set to five times. As the detector 7, an X-ray camera (maximum resolution 500 nm), which is a two-dimensional detector with variable position resolution, was used.

Next, the operation from the measurement procedure of the small-angle scattered X-ray CT according to the present configuration will be described. First, adjust the spectral crystal, analyzer crystal, and detector of the optical system. Sample 4
The computer 8 adjusts the spectral crystal 2 so that the spectral crystal 2 emits the incident X-ray 3 of a predetermined wavelength while monitoring the emitted X-rays from the spectral crystal 2 with a scintillation counter or the like in a state where there is no light. Next, the sample 4 is set on the turntable 4a, and the scattered X-rays 5 from the sample 4 are measured by a scintillation counter or the like while scanning the incident angle of the analyzer crystal 6. FIG. 2 shows the result of the measurement. From the contents shown in FIG. 2, the minimum resolution θ in this optical system is 2.35 seconds (particle diameter: 6800
(corresponding to nm) and that the oscillation of the scattered X-ray intensity from polystyrene having a particle size of 450 nm can be observed. Then, the analyzer crystal 6 was set at a position at a scattering angle of about 200 seconds (arrow in the figure), and the adjustment of the optical system was completed.

Next, a scattered X-ray image from the sample 4 is measured by an X-ray camera in the above optical system. The measurement conditions were as follows: a single element size of 500 nm, a 1024 × 1024 element area, a signal from the X-ray camera was A / D converted, and sequentially recorded in a frame memory, and then data was recorded in the computer 8. Next, after rotating the sample 4 by a predetermined angle (1 ° in this measurement), an X-ray image scattered from the sample 4 is measured by an X-ray camera. This was repeated until the rotation angle of Sample 4 became 180 °.

Then, the computer 8 converts the scattered X-ray image P ′ (x ′, z ′, f) as a group of scattered X-ray images obtained from multiple directions of the scattered X-ray image as measurement data once recorded. A small angle scattered X-ray CT image is formed by performing an image reconstruction operation using an image reconstruction algorithm of a filtered back projection method used in a conventional X-ray CT, and polystyrene particles embedded in a matrix epoxy. Was obtained. That is, the internal structure of the sample could be observed.

In summary, the feature of the small-angle scattered electromagnetic wave CT method according to the present invention is to reconstruct an image of an n-dimensional object from an n-1 dimensional projected image of the n-dimensional object. The projected image that reconstructs an image of the inside of the object is a scattered electromagnetic wave image obtained by irradiating the object with an electromagnetic wave and scattering from the object at a small angle, and the projected image group is a group of scattered electromagnetic wave images obtained from many directions. There is a place. On the other hand, the feature of the small-angle scattered X-ray CT apparatus according to the present invention is that a scattered X-ray image scattered at a small angle from the object is obtained from many directions by irradiating the object with X-rays, and a scattered X-ray image group is detected. And means for reconstructing an image of the inside of the object using the scattered X-ray image group.

In the small-angle scattered X-ray CT apparatus according to one embodiment realized by utilizing the above-mentioned invention, the X-rays from the X-ray source 1 are separated into the incident X-rays 3 having a predetermined wavelength by the spectral crystal 2. And irradiates the sample 4 with a small scattering angle 2
The scattered X-rays 5 scattered in θ are diffracted by the analyzer crystal 6, and the detector 4 detects the scattered X-ray image from the scattered X-rays 5 while rotating the sample 4 on the turntable 4 a, A scattered X-ray image is obtained from a number of directions, a scattered X-ray image group is measured, and a sample is detected with high sensitivity from a small-angle scattered X-ray CT image formed by reconstructing an image of the inside of an object using the scattered X-ray image group. It can be said that it observes the internal structure.

As described above, in this embodiment, the projected image
Since a scattered X-ray image (group) was used as (group), a CT image having higher contrast than ordinary X-ray CT could be obtained. Further, in the present embodiment, since it is possible to use a generally used algorithm for CT images and a hard processor dedicated to fast Fourier transform, it is possible to speed up image reconstruction calculation of scattered CT images. There is. Further, in this embodiment, an X-ray camera can be used for the detector 7 in order to use X-rays as electromagnetic waves.
There is an effect that two-dimensional detection of a scattered X-ray image can be easily performed and measurement time can be reduced. In addition, since this X-ray camera can change the element size (position resolution),
There is an effect that a scattered CT image can be measured according to the sample size.

Furthermore, in this embodiment, since a channel cut crystal having five reflections is used as the analyzer crystal 6, the light receiving angle of the sample as viewed from the detector is very small, a few seconds, and the set angle from the sample 4 is small. No scattered X-rays enter the detector. Therefore, there is an effect that a scattered X-ray image measurement with very little background noise can be performed.

Next, a modification of the first embodiment shown in FIG. 1 will be described as a second embodiment. The second embodiment is an example in which an asymmetric reflection crystal is used as the analyzer crystal 6 in the first embodiment. The asymmetrical reflection crystal is obtained by cutting out the crystal surface in a direction non-parallel to the diffraction plane, and has a function of enlarging an X-ray image incident on the asymmetrical reflection crystal. This makes it possible to measure a scattered CT image having a resolution higher than the resolution of the detector. FIG. 3 shows a principle diagram for expanding the X-ray width by the asymmetric reflection crystal. (111) of Si was used as the asymmetric reflection crystal. At this time, the magnification b of the image is expressed by the following equation. b = dout / din = sin (θB + α) / sin (θB−α) (Equation 5) where dout is the output X-ray width, din is the incident X-ray width, θB is the Bragg angle for the Cu-Kα1 line, and α is This is the angle between the diffraction plane and the crystal surface. In this embodiment, α = 11.5
A scattered X-ray image with a magnifying power of 9 was measured using an asymmetric reflective crystal of ゜. As a result, a scattered CT image exceeding the resolution of the detector could be obtained.

In this embodiment, since the asymmetric reflection crystal is used as the analyzer crystal, the light receiving angle of the sample as viewed from the detector becomes as small as several tens of seconds as in the first embodiment of the present invention. Does not enter the detector. Therefore, there is an effect that a scattered X-ray image measurement with very little background noise can be performed.

Next, a third embodiment shown in FIG. 4 will be described as a third embodiment. FIG. 4 is a view showing a small-angle scattering X-ray CT apparatus according to another embodiment of the present invention. In the figure, the sample 4 is irradiated after the X-ray from the X-ray source 1 is shaped and parallelized by a slit 9. The scattered X-rays 5 scattered by the sample 4 at the scattering angle 2θ were restricted by the solar slit 11 and then measured by the detector 7. The sample 4 was set on a turntable 4a driven by a stepping motor. Further, the arm 1 whose rotation axis coincides with the rotation axis of the turntable 4a of the sample 4
On 3, a solar slit 11 and a detector 7 were installed.
The rotation of each turntable 4a and each arm 13 is controlled by a computer 8 via a motor driver and a driver controller.

The X-ray source 1 used was a rotating anti-cathode X-ray generator. Cu was used for the rotating anode, and the accelerating voltage and current of the electrons were 60 kV and 200 mA, respectively. As the slit 9, a four-quadrant slit made of a tantalum plate was used. By arranging two sets of 1 mm square slits,
X-rays with high parallelism could be incident on the sample. Sample 4 used an Al bar in which SiC fine particles were dispersed. As the detector 7, a photodiode array (PDA, one-dimensional detector) using a fluorescent film for X-ray-visible light conversion in an entrance window was used.

Next, a measurement procedure of the small-angle scattered X-ray CT according to the present configuration will be described. X-ray without sample 4
The slit 9 is adjusted while monitoring with DA. Next, the sample 4 is set on a turntable, and the PDA is rotated while maintaining a predetermined angle, and a scattered X-ray image at a scattering angle of 2θ is measured.
The signal from the PDA was A / D converted and sequentially recorded in a frame memory, and then data was recorded in the computer 8. Next, after rotating the sample by a predetermined angle (1 ° in this measurement), the sample 4
Is measured with a PDA. This was repeated until the rotation angle of the sample became 180 °. From the obtained scattered X-ray image group P ′ (x ′, f) as a group of scattered X-ray images, the image in the matrix Al was obtained by the image reconstruction algorithm of the filter-corrected backprojection method used in ordinary X-ray CT. A two-dimensional image of the SiC grains embedded in the substrate was obtained.

In this embodiment, the solar slit 11
Is provided in front of the detector, the solid angle of the sample viewed from the detector is limited, only the desired scattered X-rays from the sample 4 can be detected, and the scattered X-ray image measurement with little background noise can be performed. There is. Further, in the present embodiment, by inserting a Ni filter between the X-ray source and the sample 4, Cu-K
The intensity of X-rays other than α-rays is reduced, and measurement of a scattered X-ray image with little background noise becomes possible.

Further, in the present embodiment, since no crystal is used, there is an effect that measurement with a high X-ray intensity becomes possible and adjustment is simple. In addition,
In the present embodiment, since a one-dimensional detector is used, the amount of data is smaller than that of an X-ray camera, and there is an effect that an image reconstruction operation can be processed at a high speed. As a modification of the present embodiment, an infrared ray generator (laser, lamp, etc.) is used as a light source, and an infrared ray detector (cooled Si detector, PDA, etc.) is used as a detector. The sample is Si which is transparent to infrared rays, and a group of scattering images of infrared rays due to defects or vacancies existing in the Si is measured, so that a defect distribution image in the Si can be observed by the same method as described above.

Next, a fourth embodiment shown in FIG. 5 will be described as a fourth embodiment. FIG. 5 is a view showing a small-angle scattering X-ray CT apparatus according to another embodiment of the present invention. The means for detecting a group of scattered X-ray images obtained from multiple directions of the scattered X-ray image in the present embodiment includes a detector 7, a computer 8, and a driving means. Among them, the detector 7 and the computer 8 can also be used as a conventional X-ray CT apparatus. As a driving means, the measuring surface of the detector 7 is always directed in a direction perpendicular to the scattered X-rays 5 transmitted through the sample 4,
Face-to-face means for driving the detector 7 was used.
That is, one embodiment of the facing means is the turntable 4
a center of rotation (i.e., the axis of rotation)
It comprises a rail 12a laid with a (rotary axis) and a detector base 12b that moves while mounting the detector 7 along the rail 12a.

As a driving means provided in a means for obtaining a scattered X-ray image scattered at a small angle of the object from a plurality of directions and detecting a scattered X-ray image group, there is the above-mentioned facing means.
As described above, a single unit for rotating the turntable 4a on which the sample 4 is placed may be used. Further, a combination of the means for rotating the turntable 4a of the sample 4 and the facing means may be used. In the case of the combination means, it is desirable to control the movement of the detector base 12b in accordance with the rotation of the turntable 4a.
In other words, it can be said that the driving means included in the means capable of detecting a group of scattered X-ray images obtained from a plurality of directions of the scattered X-ray image rotates at least one of the sample 4 and the detector 7. However, it can be said that it is effective and desirable in terms of data collection (such as efficiency and accuracy) of the scattered X-ray image group if both rotations of the sample 4 and the detector 7 are correspondingly controlled. Furthermore, since the apparatus for rotating the detector 7 or the X-ray source 1 is large, the method of rotating only the sample 4 is preferable.

On the other hand, as a meeting means of another embodiment,
The rotating table 12c is mounted on the detector 7 and rotates, and the moving table 12d is mounted on the rotating table 12c and moves in a direction perpendicular to the direction of the incident X-rays 3. That is, a driving mechanism having an axis passing through the center of the measurement surface of the detector 7 as a rotation axis is installed between the detector 7 and the sample 4, and detection is performed while moving the detector 7 in a direction perpendicular to the incident X-ray 3. The detector 7 is rotated so that the measurement surface of the detector 7 is always perpendicular to the scattered X-rays 5. In this case, it is also possible to control the driving of the turntable 4a on which the sample 4 is mounted and rotated, and the turntable 12c and the moving table 12d.

Then, the X-rays from the X-ray source 1 are slit 9
The sample 4 is irradiated after being molded and parallelized. The detector 7 measured the transmitted X-rays 10 transmitted by the sample 4 or the scattered X-rays 5 scattered at the scattering angle 2θ. Sample 4
Was set on a rotating table 4a driven by a stepping motor.
The detector 7 was driven by a stepping motor. Each drive is controlled by a computer 8 via a motor driver and a driver controller. X-ray source 1
, A rotating anti-cathode X-ray generator was used. The rotating anode is made of Cu, and the electron acceleration voltage and current are 60
kV and 200 mA. As the slit 9, a four-quadrant slit made of a tantalum plate was used. As the detector 7, a photodiode array (that is, a PDA, which is a one-dimensional detector) using an X-ray-visible light conversion fluorescent film in an incident window was used.

Next, the procedure for measuring small-angle scattered X-ray CT with the above configuration will be described. Transmission X without sample 4
The slit 9 is adjusted while monitoring the line with the PDA.
Next, a conventional transmission X-ray image can be measured by measuring the transmission X-ray image of the sample while rotating the sample 4 placed on the turntable. Further, the PDA is driven by the above-mentioned driving means at a predetermined scattering angle 2θ to measure a scattered X-ray image. The signal from the PDA was A / D converted and sequentially recorded in a frame memory, and then data was recorded in the computer 8. Next, after rotating the sample by a predetermined angle (1 ° in this measurement),
A scattered X-ray image from the sample 4 is measured with a PDA. This was repeated until the rotation angle of the sample became 180 °. From the obtained scattered X-ray image P '(x', f), a two-dimensional image of the inside of the sample can be obtained by the image reconstruction algorithm of the filter correction back projection method used in ordinary X-ray CT. Was.

In this embodiment, the conventional X-ray CT
The apparatus is provided with a means for detecting a group of scattered X-ray images obtained from multiple directions of a scattered X-ray image scattered at a small angle from a sample as a projected image, thereby enabling a conventional transmission X-ray image to be detected. Not only X-ray CT images, but also small-angle scattering X-rays C according to the present invention.
The T image can be easily measured. And the small-angle scattering X-ray CT
The effect is that the internal structure of the sample can be observed with high sensitivity from the image. Furthermore, there is an advantage that it can be easily modified from the conventional X-ray CT apparatus.

That is, the small-angle scattering X-ray CT of the fourth embodiment
The apparatus is an apparatus obtained by adding means for detecting a group of scattered X-ray images obtained from a plurality of directions of scattered X-ray images scattered at a small angle from a sample to the conventional X-ray CT apparatus shown in FIG. is there. In other words, another feature of the small-angle scattered X-ray CT apparatus according to the present invention is that, in an X-ray CT apparatus that irradiates an object with X-rays, not only the transmitted X-ray transmitted through the object but also a small angle scattering from the object. In order to detect the scattered X-rays from multiple directions, a mechanism for translating the detector perpendicular to the direction of the scattered X-rays from the object (i.e., facing means), or so that the rotation axis coincides with the rotation axis of the object A drive mechanism (ie, drive means) for rotating the detector is added to the conventional X-ray CT apparatus. Then, in the means (generally the computer 8) of the small-angle scattering X-ray CT apparatus for performing image reconstruction calculation, processing for recording data of the scattered X-ray image group and / or processing for calculating the equation (4) is performed. The processing steps (program software) or the ROM in which the processing steps are written are added to the computer 8.

[0036]

According to the small-angle scattered X-ray CT apparatus of the present invention, a scattered X-ray image is used as a projected image, so that a CT image having a higher contrast than that of a conventional X-ray CT apparatus can be obtained. There is. Further, according to the small-angle scattering X-ray CT apparatus according to the present invention, by providing an analyzer crystal and / or a solar slit in front of the detector, the solid angle of the sample viewed from the detector can be limited, and the background noise is extremely low. There is an effect that it becomes possible to measure a scattered X-ray image with very little.

[Brief description of the drawings]

FIG. 1 is a diagram showing a small-angle scattering X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a scattered X-ray intensity distribution of a sample measured by the small-angle scattered X-ray CT apparatus of FIG. 1;

FIG. 3 is a view showing a principle of expanding an X-ray width by an asymmetric reflection crystal according to an embodiment of the present invention.

FIG. 4 is a view showing a small-angle scattering X-ray CT apparatus according to another embodiment of the present invention.

FIG. 5 is a view showing a small-angle scattering X-ray CT apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating a small-angle scattered electromagnetic wave CT method according to the present invention.

FIG. 7 is a diagram illustrating a conventional X-ray CT apparatus.

FIG. 8 is a diagram illustrating a conventional small-angle scattering X-ray apparatus.

FIG. 9 is a diagram illustrating a conventional X-ray CT method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... X-ray source, 2 ... Dispersion crystal, 2a, 4a, 6a, 7a,
12c: turntable, 3: incident X-ray, 4: sample, 5: scattered X
Line, 6: analyzer crystal, 7: detector, 8: calculator,
9: slit, 10: transmitted X-ray, 11: solar slit, 12a: rail, 12b: detector table, 12d: movable table, 13: arm.

Claims (6)

[Claims] 1. A small-angle scattered electromagnetic wave CT method for reconstructing an image of the inside of an object using a group of projected images, wherein the projected image is obtained by irradiating the object with an electromagnetic wave and scattering the object at a small angle from the object. A small-angle scattered electromagnetic wave CT method, wherein the projected image group is a group of the scattered electromagnetic wave images obtained from multiple directions. 2. The small-angle scattered electromagnetic wave CT method according to claim 1, wherein said electromagnetic waves are X-rays. 3. A small-angle scattered X-ray CT apparatus for irradiating an object with X-rays to obtain a scattered X-ray image scattered from the object at a small angle, wherein the scattered X-ray image obtained from a plurality of directions of the scattered X-ray image is provided. A small-angle scattered X-ray CT apparatus comprising means for detecting a group of line images. 4. The apparatus according to claim 3, wherein the means for detecting the scattered X-ray image group includes a driving means for rotating at least one of the object and a detector for detecting the scattered X-ray image. Small-angle scattering X-ray CT apparatus. 5. The apparatus according to claim 4, wherein the driving means mounts a crystal that diffracts the scattered X-rays from the object and the detector that detects a scattered X-ray image from the diffracted X-rays. A small angle scattered X-ray CT apparatus comprising means for independently controlling the rotation of each of the rotary tables whose rotation axes coincide with the rotation axis of the object. 6. The small-angle scattered X-ray detector according to claim 4, wherein said driving means has means for causing said detector to face perpendicularly to a direction of scattered X-rays detected by said detector from said object. Line CT device.