JPH06235703A - X-ray ct system - Google Patents

Abstract

PURPOSE:To provide an X-ray CT system in which data can be collected at high speed while fixing a specimen and a correct tomographic image of an object can be obtained. CONSTITUTION:The X-ray CT system comprises a mechanism for allowing rotation within a range of 180 deg. or more around the direction of an incident X-ray beam 1 so that the incident angle is fixed with respect to the incident X-ray beam 1, a first crystal 2 for taking out diffracted X-rays using Bragg reflection, a second crystal 3 equipped with a mechanism rotatable within a range of 180 deg. or more around the direction of the incident X-ray beam 1 in synchronism with the first crystal 2 so that the X-rays can be diffracted simultaneously when the first crystal 2 is rotated, a mechanism rotatable within a range of 180 deg. or more around the direction of the incident X-ray beam in synchronism with the rotary mechanisms for the first and second crystals 2, 3, and a one-dimensional or two-dimensional detector 5 for collecting the transmitted image of a specimen 4 at all times. The fixed specimen 4 is irradiated substantially normally with monochromatic X-rays within an angle range of 180 deg. or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention obtains a tomographic image of a substance by obtaining a monochromatic X-ray from a highly parallel white X-ray (for example, synchrotron radiation) as a X-ray source using a single crystal or the like. The present invention relates to an X-ray CT apparatus.

[0002]

2. Description of the Related Art X-ray CT is widely used for industrial and medical diagnosis. In the case of industrial use, it is being used for non-destructive inspection. Non-destructive detection of internal micro defects such as metal, ceramics or composite materials, and quality evaluation of each material based on the detection result. There is.

At present, there is a strong demand for improving the accuracy of the correspondence between the contrast of an X-ray CT image and the X-ray absorption coefficient. This is because the element / density distribution inside the material is measured with high accuracy by X-ray CT, and the measurement result is fed back to the manufacturing process to promote the material development. Further, in the case of medical diagnosis, it is necessary to evaluate the metabolic function of the living body by performing high-contrast imaging of blood vessels inside the living body.
Therefore, in order to improve the accuracy of correspondence between the contrast of the CT image and the X-ray absorption coefficient (improvement of quantitativeness of the CT image), research and development of a CT device using synchrotron radiation (SOR) is currently underway. .

As a conventional apparatus configuration in this case, synchrotron radiation (SOR) which is high intensity white X-ray with high parallelism is used as an X-ray source, and Bragg reflection of a single crystal such as Si or Ge is used. It constitutes a monochromator device. Then, a monochromatic X-ray (E ₁ ) is obtained, the monochromatic X-ray is detected by an X-ray detector having high spatial resolution, and high resolution and high precision element / density distribution measurement is performed. The monochromatic X-ray energy E _{1 in} that case is represented by the following equation.

[0005] lambda ₁ (X-ray _{wavelength) ≒ 12.4 / E 1 = 2dsinθ} B1 (1) θ B1: Bragg angle d (grating ^{spacing) = A / √ (h 2} + k 2 + l 2) <hkl>: Using Lattice surface of single crystal A: Lattice constant of single crystal

Here, FIG. 4 shows a conventional C having this configuration.
The example of schematic structure of T apparatus is shown. In the figure, 21 is a white X-ray, 22 is a fixed first crystal, 23 is a fixed second crystal, 24 is a subject, 25 is a detector, and 26 is a computer. In this apparatus, first, X-rays containing desired monochromatic X-ray energy are extracted from the white X-rays 21 by using the Bragg reflection of the single crystal (first crystal 22), and the subject 24
To irradiate. Then, the X-ray image transmitted through the subject 24 is magnified and monochromatic by utilizing the symmetrical or asymmetrical reflection of the Bragg reflection of the single crystal (second crystal 23) and detected by the detector 25. As an example of an X-ray CT apparatus using this method, Japanese Patent Application Laid-Open No. 61-256243 and Japanese Patent Application Laid-Open No. 63-256243.
There is one described in Japanese Patent No. 53456.

[0007]

However, the conventional X-ray C
The T device has the following problems. That is, in the conventional method, as in the example shown in FIG. 4, a series of operations of rotating the subject 24 by a specific minute angle and capturing a projection image is repeated, and the subject 24 is rotated at least 180 degrees. Need to let. This is synchrotron radiation (SOR), which is a high-intensity white X-ray with high parallelism as an X-ray source.
This is because the X-ray generator itself is huge when it is used, and it is difficult to rotate the X-ray source itself around the subject as in a normal medical CT apparatus. Therefore, in such an X-ray CT apparatus, it is necessary to fix the subject when detecting each projection image, and therefore a large number of operations of rotating and fixing the subject at a small angle must be repeated during CT image capturing. Due to such mechanical control, conventionally, there has been a problem that it is extremely difficult to speed up the collection of projection data.

In order to further improve the image quality of the CT image, the rotation axis of the subject and the X-ray beam surface must be perpendicular to each other. Therefore, conventionally, the rotation axis must be finely adjusted when the subject is installed. There is also a problem that it is necessary and the operation of the device is complicated.

In view of the above situation, it is an object of the present invention to provide an X-ray CT apparatus capable of obtaining high-speed tomographic images of an object while the subject is fixed and high-speed data acquisition is possible. .

[0010]

An X-ray CT apparatus according to the present invention comprises a single crystal for monochromating X-rays, an object supporting portion,
It has an X-ray detector, a controller for collecting signals from the X-ray detector and controlling the position of the single crystal, and software or hardware for CT image reconstruction. And, in particular, the direction of the incident X-ray beam is set to 1 as a rotation axis so that the incident angle with respect to the incident X-ray beam is always constant.
It is equipped with a mechanism that allows rotation in a range of 80 degrees or more, and uses a first crystal that extracts Bragg reflection X-rays and a diffraction X-ray generated when the first crystal is rotated. , A second crystal that is synchronized with the first crystal and has a mechanism capable of rotating in a range of 180 degrees or more about the incident X-ray beam direction as a rotation axis in order to always diffract simultaneously, or the second crystal. In a diffracted X-ray direction that is diffracted by rotating one crystal in a range of 180 degrees or more, a large number of second crystal groups having the same shape and material that are arranged in advance and the first and second crystals A one-dimensional or two-dimensional detector that is synchronized with a rotating mechanism and is capable of rotating in a range of 180 degrees or more with the incident X-ray beam direction as a rotation axis so that transmission images of a subject can be always collected. , Or detector element Are arranged in advance so as to surround the subject, and are composed of a one-dimensional or two-dimensional detector capable of electrically collecting transmission images of the subject without rotating themselves, and are fixed. In addition, a monochromatic X-ray can be irradiated almost vertically to the subject from an angle range of 180 degrees or more.

[0011]

According to the present invention, the first crystal utilizes symmetrical or asymmetrical reflection of a single crystal. In that case, the width size W _{1 of the} crystal is made larger than the width of the incident X-ray beam. Further, the first crystal is provided with a mechanism that can rotate in a range of 180 degrees or more while keeping the incident angle with respect to the incident X-ray beam as a rotation axis with the direction of the incident X-ray beam as a rotation axis. . Subsequently, the diffracted X-ray from the first crystal is diffracted by the second crystal. Then, the object having the outer size a or less is irradiated and detected by the X-ray detector. The second crystal has a width of W ₂ or more and a length of L ₂ or more, and diffracts by utilizing symmetrical reflection or asymmetrical reflection.

Further, in order that the diffracted X-rays generated when the first crystal is rotated can always be simultaneously diffracted by the second crystal, the second crystal is synchronized with the first crystal and the original incident X-ray beam is synchronized. Is provided with a mechanism capable of rotating in a range of 180 degrees or more with respect to the rotation axis, or a large number of second crystals having the same shape and material are arranged side by side in the diffraction X-ray direction from the first crystal.

Thereafter, the transmitted X-ray image of the subject is detected by the one-dimensional detector or the two-dimensional detector. This detector has a mechanism that can rotate in synchronism with the rotation mechanism of the first crystal and the second crystal so that transmission images of the subject can always be collected, or the detector element is Either one is arranged in advance so as to surround the sample, and the transmission image of the sample can always be electrically collected without rotating the detector itself.

According to the present invention, by having such a mechanism, it is possible to irradiate a fixed subject with a monochromatic X-ray almost vertically from an angle range of 180 degrees or more, and the transmitted X-ray is transmitted. Line images can be detected. Therefore,
An appropriate CT image using monochromatic X-rays can be obtained while the subject is fixed. The optimum value of the number of times the first crystal and the second crystal are rotated by the minimum angle, and the optimum value of the number (angle interval) of a large number of the second crystals are given from the sampling theorem. Further, when the size of the object is larger than the width d _IN of the incident X-ray beam 1, the second crystal needs to use a curved crystal to increase the irradiation beam size.

The conditions for irradiating a fixed subject with a monochromatic X-ray almost perpendicularly are given by the Bragg angles of the first and second crystals, the subject size, and the slice width of the CT image. . When the crystal lattice plane to be used is set to a low order to improve the X-ray intensity, the diffracted X-ray from the first crystal is diffracted on the way by the third crystal and then diffracted by the second crystal. It is also possible to do this (see Figure 3
Shown in). In this case, in order to always be able to simultaneously diffract the diffracted X-rays generated when the first crystal is rotated with the width W ₃ or more, the incident X-ray beam is synchronized with the third crystal. Equipped with a mechanism that allows it to rotate in a range of 180 degrees or more with respect to the rotation axis, or a third crystal having the same shape and material is diffracted from the first crystal X
Place a lot of them side by side in the line direction.

Further, when the third crystal is used, the conditions for irradiating the fixed object with the monochromatic X-rays almost always perpendicularly are the Bragg angles of the first crystal, the second crystal and the third crystal, It is given from the sample size and the slice width of the CT image. Note that the optimum value of the number of times the third crystal is rotated by the minimum angle, and the optimum value of the number (angle interval) when a large number of third crystals are arranged, are given from the sampling theorem as in the case of the second crystal. To be

Since the transmitted X-ray image of the subject is collected while rotating the first crystal, the X-ray intensity may differ in the irradiation cross section of the original X-ray source or the diffraction X-ray non-uniformity of the crystal. If so, intensity correction is necessary. That is, it is necessary to collect the data of Pθ in advance and set the final diffraction X-ray intensity when there is no subject as Pθ (x, θ). Here, x is the element number of the detector, and θ is the rotation angle of the first crystal, the second crystal, and the third crystal from the reference.

Further, the X-ray CT apparatus of the present invention includes a base for fixing the subject, control of the observation cross-section position of the subject, collection of signals from the X-ray detector, and control of each single crystal position control. It has a computer for performing the operation and software or hardware for CT image reconstruction. The single crystals used include Si, Ge, InSb and Li.
F and the like are preferable.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the X-ray CT apparatus according to the present invention will be described below with reference to FIGS. FIG. 1 shows a schematic configuration of an X-ray CT apparatus according to this embodiment, and FIG. 2 is a side view of a main part thereof.

The first crystal 2 utilizes the symmetric reflection or asymmetric reflection of a single crystal. In that case, the crystal width size W ₁
Is set to be equal to or larger than the width of the incident X-ray beam 1. Further, the first crystal 2 has the direction of the incident X-ray beam 1 as a rotation axis, and can be rotated in an angle range of 180 degrees or more while keeping the incident angle with respect to the incident X-ray beam 1 always constant. A mechanism not shown is provided.

For the monochromatic X-ray energy E ₁ , the following relation applies here: However, λ ₁ (X-ray wavelength) ≈12.4 / E ₁ = 2d ₁ sin θ _B1 (2) E ₁ : X-ray energy value d ₁ (lattice spacing) = A ₁ / √ (h ₁ ² + k ₁ ² +1) ₁ ² ) <h ₁ k ₁ l ₁ >: Lattice surface used by the first crystal 2 A ₁ : Lattice constant of the first crystal 2 θ _{B 1} : Bragg angle of the first crystal 2 α ₁ : Surface of the first crystal 2 Angle formed by the grating plane that causes Bragg reflection with W ₁ > d _IN (width of incident X-ray beam 1)

Subsequently, the diffracted X-ray from the first crystal 2 is diffracted by the second crystal 3. Then, the subject 4 having an outer size a or smaller is irradiated and detected by the X-ray detector 5. The second crystal 3 has a width of W ₂ or more and a length of L ₂ or more, and is diffracted by utilizing symmetrical reflection or asymmetrical reflection.

Further, in order that the diffracted X-rays generated when the first crystal 2 is rotated can always be simultaneously diffracted by the second crystal 3, the second crystal 3 is synchronized with the first crystal 2 and the original incidence is performed. It is equipped with a mechanism capable of rotating the X-ray beam 1 as an axis of rotation in an angle range of 180 degrees or more. Alternatively, a plurality of second crystals 3 having the same shape and material may be arranged side by side in the direction of the diffraction X-ray from the first crystal 2.

After that, the transmitted X-ray image of the subject 4 is detected by the one-dimensional detector or the two-dimensional detector 5.
The detector 5 has a mechanism capable of rotating in synchronization with the rotating mechanism of the first crystal 2 and the second crystal 3 described above, and is always in contact with the subject 4
It is possible to collect transmission images of. Alternatively,
A large number of detector elements are arranged in advance so as to surround the subject 4, whereby the detector itself is not rotated,
It is also possible to electrically collect transmission images of the subject 4, and any one of these methods is adopted.

The X-ray CT apparatus of the present invention is configured as described above, and it is possible to irradiate the fixed subject 4 with monochromatic X-rays almost vertically from an angle range of 180 degrees or more,
The transmitted X-ray image can be detected. Therefore, a CT image using monochromatic X-rays can be obtained with the subject 4 fixed.

However, λ ₂ (X-ray wavelength) ≈12.4 / E ₂ = 2d ₂ sin θ _B2 (3) d ₂ (lattice spacing) = A ₂ / √ (h ₂ ² + k ₂ ² + l ₂ ² ) < h ₂ k ₂ l ₂ >: Lattice surface used by the second crystal 3 A ₂ : Lattice constant of the second crystal 3 θ _B2 : Bragg angle of the second crystal 3 α ₂ : Surface of the second crystal 3 and Bragg reflection Angle formed by lattice plane λ ₁ = λ ₂ W ₂ ≧ W ₁ L ₂ ≧ d _OUT / sin (θ _B2 + α ₂ ) d _OUT : Required reflected beam size (required slice width for CT image capturing) | 2θ _B2 − 2θ _B1 −90 ° | ≦ Δθ (4) (It should be noted that the above formula (4) shows the condition that the fixed subject 4 is always irradiated with a monochromatic X-ray as described later.) Δθ = (180 / π) · r · b / a (5) r: slice width of CT image b: other region due to rotation axis shift with respect to a certain CT image slice plane The degree of overlap tolerance (tolerance of image quality degradation degree) a: size of the object 4

The optimum value of the number of times the first crystal 2 and the second crystal 3 are rotated by the minimum angle, and the optimum value of the number (angle interval) of the second crystals 3 arranged in a line, is the sampling theorem. It is known that is given by N _OP ≈π / 2 · M _OP +1 (6) However, N _OP : Optimum rotational scanning number within 180 degrees, M _OP : C
Matrix size of T image (for example, 256 × 256, M _OP = 256)

When the size of the object 4 is larger than the width d _IN of the incident X-ray beam 1, the second crystal 3 needs to be a curved crystal to enlarge the irradiation beam size. The conditional expression in that case is approximately as follows. 2Z · tan2θ + d _IN > a (7) θ = sin ⁻¹ {d _IN / (2R)} (8) where Z: distance between the second crystal 3 and the subject 4 a: size of the subject 4 R: second Curvature of curvature of crystal 3

As described above, the condition for irradiating the fixed subject 4 with the monochromatic X-rays almost vertically is always | 2θ _B2
−2θ _B1 −90 ° | ≦ Δθ (see equation (4)). Here, in FIG. 2, 10 is the angle (2θ _B1 ) formed by the first crystal diffraction X-ray direction with respect to the white X-ray incidence direction, and 11 is the angle formed by the second crystal diffraction X-ray direction with respect to the first crystal diffraction X-ray direction. (2θ _B2 ), and 12 is the angle (2θ _B2 −2θ) formed by the second crystal diffraction X-ray direction with respect to the white X-ray incident direction.
_B1 ) respectively.

Further, since the transmitted X-ray image of the subject 4 is collected while rotating the first crystal 2, when the X-ray intensity is different in the irradiation cross section of the original X-ray source 1 or the diffraction X-ray of the crystal is not uniform. If there is a possibility, intensity correction is necessary. That is, the final diffracted X-ray intensity when there is no subject 4 is Pθ (x, θ), and it is necessary to collect and store Pθ data in advance. Where x is the element number of the detector 5, θ is the first crystal from the reference 2,
It is the rotation angle of the second crystal 3. Further, the X-ray C of the present invention
The T apparatus is a table for fixing the subject 4, a computer for controlling the observation cross-sectional position of the subject 4, a process of collecting signals from the X-ray detector 5 and a control of each single crystal position control, and CT image reconstruction. Software or hardware for Moreover, Si, Ge, InSb, LiF etc. are mentioned as a suitable example of each single crystal used in the said case.

By the way, when the crystal lattice plane to be used is set to a lower order and the X-ray intensity is improved, the diffracted X-ray from the first crystal 2 is diffracted by the third crystal, and then the above-mentioned first crystal is used. It is also possible to diffract it with the double crystal 3. Therefore, a second embodiment using the third crystal will be described below with reference to FIG. In this case, in order that the third crystal 13 can always diffract the diffracted X-rays generated when the first crystal 2 is rotated and have a width of W ₃ or more,
Rotation about the incident X-ray beam 1 as a rotation axis in synchronization with
X-ray diffraction from the first crystal 2 by the third crystal 13 having a mechanism capable of 0 degree or more or having the same shape and material
Place a lot of them side by side in the line direction. The conditions under which monochromatic X-rays are always irradiated almost vertically to the subject 4 fixed using the third crystal 13 are as follows.

| 2θ _B2 −2θ _B1 + 2θ _B3 −90 ° | ≦ Δθ (9) where λ ₃ (X-ray wavelength) ≈12.4 / E ₃ = 2d ₃ sin θ _B3 (10) d ₃ (lattice spacing) = A ₃ / √ (h ₃ ² + k ₃ ² + l ₃ ² ) <h ₃ k ₃ l ₃ >: Lattice surface used by the third crystal 13 A ₃ : Lattice constant of the third crystal 13 θ _B3 : Third crystal Bragg angle α _{3 of} 13: angle formed by the surface of the third crystal 13 and the lattice plane that causes Bragg reflection λ ₃ = λ ₁ = λ ₂ W ₃ ≧ W ₁ Δθ = (180 / π) · r · b / ar : Slice width of CT image b: Allowable value of degree of overlap of other regions due to rotational axis shift with respect to a certain CT image slice surface (allowable value of image quality deterioration degree) a: Subject size Here, in FIG. 3, 14 is the first crystal the angle of the third crystal diffraction X-ray direction relative to the diffraction X-ray direction (2 [Theta] _B3), also 15 pairs white X-ray incident direction Angle of the second crystal diffraction X-ray direction _{(2θ B2 -2θ B1 + 2θ B3} ) respectively show that.

The optimum value of the number of times the third crystal 13 is rotated by the minimum angle, and the optimum value of the number (angle interval) of the third crystals 13 arranged in the same manner, is expressed by the equation (6). Given.

As in the case of the first embodiment, since the transmitted X-ray image of the subject 4 is collected while rotating the first crystal 2, the X-ray intensity in the irradiation cross section of the original X-ray source 1 is If they are different or if there is diffraction X-ray non-uniformity in the crystal, intensity correction is necessary. That is, the final diffraction X when there is no subject 4
It is necessary to collect the data of Pθ in advance and set the line intensity as Pθ (x, θ). Where x is the element number of the detector 5,
θ: First crystal 2, second crystal 3, third crystal 13 from the reference
Is the rotation angle of.

Next, in the X-ray CT apparatus shown in FIG. 3 of the present invention, an example in the case of about 32.5 kev which is near the energy value often used in high contrast imaging of a blood vessel contrast agent such as iodine. Will be explained. As the subject 4, assuming a human head, the size a is about 30 cm, and the width of the incident X-ray beam 1 is, for example, d _IN = 9 mm within the beam size of a high energy synchrotron radiation facility. Assuming that the distance from the second crystal 3 is, for example, Z = 50 cm, the curvature of the curvature of the second crystal 3 can be realized by R <31.9 mm from the equations (7) and (8).

The CT image matrix is 128 ×
Assuming 128, the optimum number of rotational scans within 180 degrees from equation (6) is N _OP = 202. When a large number of second crystals 3 are arranged, if the second crystals 3 having the same size as the beam size d _IN are arranged, the number that can be arranged is as follows because Z = 50 cm. πZ / d _IN ≈175 Although the number arranged in this way is less than the optimum value,
It can be realized without deteriorating the image quality so much.
As is clear from FIG. 3, the third crystal 13 has Z = 50.
Since it is more than cm, the number that can be arranged is 17
There are 5 or more, so there is no risk of degrading the image quality.

The condition of using the third crystal 13 and irradiating the fixed subject 4 with monochromatic X-rays at all times is | 2
θ _B2 −2 θ _B1 +2 θ _B3 −90 ° | ≦ Δθ (see the equation (9)). Next, the crystal plane to be specifically used will be examined.

If the crystal used is a Ge single crystal and the lattice plane <h ₁ k ₁ l ₁ > = <111> used by the first crystal 2, θ _B1 ≈3.3481 °, and the second crystal 3 , Lattice planes <h ₂ k ₂ l ₂ >, <h ₃ used by the third crystal 13
If k ₃ l _3> each _{<h 2 k 2 l 2>} = <777> and _{<h 3 k 3 l 3>} = <777>, | 2θ B2 -2θ B1 + 2θ B3 -90 ° | ≒ 0.
It becomes 174 °, and from the equation (5), the degree of overlap of another region due to the rotation axis shift with respect to a certain CT image slice plane is
When the slice width is about 5 mm, b = 18.2%, which can be realized without deteriorating the image quality in CT image capturing of the human head.

In the present invention, as can be seen from the above example, (9) depending on the monochromatic X-ray energy value used.
| 2θ _B2 −2θ _B1 + 2θ _B3 −90 ° | ≦
Lattice planes <h ₁ k ₁ l of the first crystal 2, the second crystal 3 and the third crystal 13 used so as to satisfy the condition of Δθ.
_{1>, <h 2 k 2} l 2>, it is necessary to select the _{<h 3 k 3 l 3>} .

[0040]

According to the present invention, the first crystal and the second crystal (third crystal) are rotated about the incident X-ray beam direction as a rotation axis, and are placed in the direction of the diffracted X-ray from the first crystal. The second crystal (or third crystal) is rotated synchronously to extract the diffracted X-rays, or the diffracted X-rays are extracted from a group of crystals placed side by side in advance to irradiate the subject, and a transmission image is collected by a detector. To do. Therefore, it is possible to always irradiate a fixed subject with a monochromatic X-ray vertically from an angle range of 180 degrees or more. Therefore, an X-ray CT apparatus capable of obtaining a CT image by a monochromatic X-ray with the subject fixed, capable of high-speed data collection, and not requiring fine adjustment of the rotation axis when the subject is installed is provided. Can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an X-ray CT apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view of the main part of the X-ray CT apparatus according to the first embodiment of the present invention.

FIG. 3 is a side view of the essential parts of a second embodiment of the X-ray CT apparatus of the present invention.

[Fig. 4] Monochromatic X from white X-rays such as synchrotron radiation
It is a figure which shows the structure of the conventional monochromatic X-ray CT apparatus which takes out and utilizes a line.

[Explanation of symbols]

1 White X-ray 2 First crystal capable of rotation with white X-ray direction as rotation axis 3 Second crystal capable of rotation with white X-ray direction as rotation axis 4 Subject 5 X-ray detector (one-dimensional or Two-dimensional detector) 10 Angle formed by first crystal diffraction X-ray direction with respect to white X-ray incident direction (2θ _B1 ) 11 Angle formed by second crystal diffraction X-ray direction with respect to first crystal diffraction X-ray direction (2θ _B2 ) 12 Angle formed by second crystal diffraction X-ray direction with respect to white X-ray incident direction (2θ _B2 -2θ _B1 ) 13 Third crystal rotatable about white X-ray direction as rotation axis 14 First crystal relative to X-ray diffraction direction Angle formed by three crystal diffraction X-ray directions (2θ _B3 ) 15 Angle formed by second crystal diffraction X-ray directions with respect to white X-ray incident direction (2θ _B2 -2θ _B1 + 2θ _B3 ) 21 White X-ray 22 Fixed first crystal 23 Fixed second crystal 25 X-ray detector One-dimensional or two-dimensional detector) 26 Computer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Hayashi 5-10-1 Fuchinobe, Sagamihara City Electronics Research Laboratories, Nippon Steel Co., Ltd. (72) Inventor Hirohisa Yamaji 5-10-1, Fuchinobe, Sagamihara Electronics Co., Ltd. Electronics Research Laboratory

Claims (1)

[Claims] 1. A single crystal for monochromating X-rays, an object supporting portion, an X-ray detector, a controller for collecting signals from the X-ray detector and controlling the position of the single crystal, and a CT. In an X-ray CT apparatus having image reconstruction software or hardware, a range of 180 degrees or more with the incident X-ray beam direction as a rotation axis so that the incident angle with respect to the incident X-ray beam is always constant. Equipped with a mechanism that allows you to rotate
In order to always be able to simultaneously diffract the first crystal that extracts the diffracted X-rays by utilizing the Bragg reflection and the diffracted X-rays generated when the first crystal is rotated, and 180 degrees with the incident X-ray beam direction as the axis of rotation
A second crystal provided with a mechanism capable of rotating in a range of 180 degrees or more, or the same shape previously arranged in all diffracted X-ray directions diffracted by rotating the first crystal in a range of 180 degrees or more. It is equipped with a large number of second crystal groups each having a material and a mechanism capable of rotating in a range of 180 degrees or more about the incident X-ray beam direction as a rotation axis in synchronization with the rotation mechanism of the first and second crystals. A one-dimensional or two-dimensional detector capable of collecting a transmission image of the subject, or a large number of detector elements are arranged in advance so as to surround the subject, and the transmission image of the subject is always displayed without rotating itself. It consists of a one-dimensional or two-dimensional detector that can be electrically collected, and can always irradiate a fixed object with a monochromatic X-ray almost vertically from an angle range of 180 degrees or more. What you did X-ray CT apparatus characterized.