JPH0783744B2 - X-ray tomography system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray tomography apparatus, and in particular, it is possible to measure a target portion of a subject with higher resolution by using an X-ray flux that is mainly parallel. The present invention relates to an X-ray tomography apparatus.

[Conventional technology]

X-ray tomography system (X-ray CT; X-ray, Computed Tomograph
y) was devised as a human body diagnostic device and is now widely used in medical institutions, but in recent years this device has been applied to inspection of defects in industrial materials and foreign substances, and its wide technical potential has been noted. Has been done. By the way, in recent years, attempts have been made to provide such an X-ray tomography apparatus with a function of measuring and displaying only a part of a subject with higher resolution. This is because, for example, it would be convenient if an apparatus capable of measuring the whole body of a human body could measure only the head with higher resolution.

For medical use, for example, in Japanese Unexamined Patent Publication No. 56-161039, by using a position-sensitive detector with a narrow element gap in the central portion and wide element gaps on both ends, only the central portion of interest is used. Techniques such as high-resolution tomographic images have been taken up. Further, in Japanese Patent Laid-Open No. 58-32749, a detector having a shape in which a detector having a dense element in the central portion and a detector having a coarse element is connected to one of the detectors is used. In addition, there has been proposed a method for measuring and displaying only the focused portion of the central portion with high resolution by using a fan beam which is not symmetrical with respect to the line connecting the light source and the center of rotation. Further, in Japanese Laid-Open Patent Publication No. 58-149739, a method for reducing the amount of scanning for the second-generation apparatus and extrapolating the outside of the target portion to obtain a high-resolution tomographic image only in the target portion. Is described.

Further, although a tomographic image measurement using a monochromatic X-ray will be described in an embodiment of the present invention described later, Japanese Patent Application Laid-Open No. 54-151387 discloses the tomographic image measurement using the monochromatic X-ray.
Regarding tomographic image measurement by monochromatic X-ray using synchrotron orbit synchrotron radiation, L. Grodzins, Nuclear Instrum
ents and Methods, 206, p.541, p.547 (1983), and A.
C. Thompson, et al., Nuclear Instruments and Methods in Physical Research, 222,
Reports such as P.319 (1987) have been made. The use of such monochromatic X-rays is extremely effective in improving the quantitativeness of tomographic images.

[Problems to be solved by the invention]

In order to measure and display a tomographic image of a portion of interest with high resolution, in the conventional invention, as described above, it is necessary to use a detector having a complicated shape such as a combination of a region with a narrow element spacing and a region with a wide element spacing. I got it. However, particularly when a detector having a very narrow element interval is used for evaluation of industrial materials and the like, it is actually difficult to prepare such a complicated shape.

On the other hand, as a task of CT technology, there is a desire to obtain a tomographic image with a higher resolution than the resolution of the detector currently achievable, because only the part of interest is required. There is a case where I want to measure with high resolution a portion of the subject that is wider than the entire length of the vessel.

In view of the above points, an object of the present invention is to provide an apparatus capable of measuring a tomographic image of a target portion with higher resolution without using a detector having a complicated shape.

[Means for solving problems]

An X-ray source and a detector for detecting X-rays transmitted through the subject;
An X-ray tomography apparatus comprising a data processing apparatus for processing transmission amount measurement data obtained by this detector to obtain a tomographic image of a subject, and changing resolution by an asymmetric reflection crystal plate provided in an X-ray path. The data processing device is provided with a means, and the X-ray transmitted through the entire subject and the X-ray transmitted through the target portion of the subject are reflected by the resolution changing means, and enlarged X-rays are detected by the detector and obtained. Based on the two sets of transmission amount measurement data obtained, or the detector detects X-rays that have been reduced by reflecting the X-rays that have passed through the portion of interest and the X-rays that have passed through the entire subject by the resolution changing means. It is possible to obtain a high-resolution tomographic image of the target portion of the subject based on the two sets of transmission amount measurement data obtained.

[Action]

According to the present invention, a high-resolution tomographic image of a target portion of a subject can be obtained even with a detector having a constant resolution.

Further, according to the present invention, only by providing the resolution changing means, it is possible to obtain high resolution transmission amount measurement data without complicating the structure of the detector itself in order to increase the resolution of the detector itself.

That is, a high-resolution tomographic image of the target portion can be obtained by combining the data by measuring the tomographic image of the entire subject and measuring the target portion with higher resolution. In particular, when an X-ray flux close to parallel is used, the asymmetric reflection crystal plate can be used as the resolution changing means and the image can be magnified. Therefore, by applying this to the attention cormorant measurement, the position used It is possible to obtain a tomographic image of the portion of interest at a resolution higher than that of the sensitive detector. This is very effective when a detector with a narrow element gap and a high resolution is originally used, and it is difficult to obtain a resolution higher than that by working the detector.

Further, in the case of an X-ray flux that is nearly parallel, the image can be reduced by using the asymmetric reflection crystal plate in the opposite direction. Therefore, by using this for the tomographic image measurement of the entire subject, It is possible to measure a wide range of objects. This is effective in that case because the total length of the detector is inevitably short when a detector with high resolution is used. In the other two examples, by using an asymmetric reflection crystal plate, a tomographic image by monochromatic X-rays will be measured as a result.
It is also excellent in quantification.

When a fan beam that spreads in a fan shape is used as the X-ray source, the resolution can be improved by bringing the subject relatively close to the X-ray source side. However, according to the conventional invention, the object is not moved until it protrudes from the fan beam. In the present invention, the measurement of X-rays transmitted through the entire subject is performed by placing the subject in a fan beam, and the measurement of the transmitted X-rays of a target portion is performed by the X-ray source until the subject protrudes from the fan beam. Perform relatively close to the side. As a result, further improvement in resolution can be expected. The resolution changing means of the present invention is configured by making the support base of the subject relatively movable toward and away from the X-ray source side up to a position beyond the spread range of the fan beam. The point that a high-resolution tomographic image of the target portion of the subject is obtained from the two measurement data is the same as that described above.

〔Example〕

First, the principle of the present invention will be outlined. It is the distance between the detection elements that determines the spatial resolution of the tomographic image by the tomographic image measurement method using the position-sensitive detector. However, there is a limit to narrowing this interval technically, and it is necessary to devise an optical system or the like in order to further improve the resolution of the tomographic image. When monochromatic X-rays that are nearly parallel are used as the light source, the image can be magnified using the asymmetric reflection crystal plate, and high resolution at the sample portion can be achieved. FIG. 3 illustrates the enlargement of this image. When the monochromatic X-ray 1 that has passed through the sample that is the subject is made incident so as to make a black angle θ _B with the diffraction crystal plane 19, the X-ray is generated. It is Bragg-reflected on the diffraction crystal plane 19 and is emitted to the crystal surface 18 at an asymmetrical angle as shown in FIG. At this time, the length l ₁ is expanded to l ₂ . The enlargement ratio is represented by the enlargement ratio = l ₂ / l ₁ = sin (θ _B + α) / sin (θ _B + α) (1). Where α is the diffraction crystal plane 19 and the crystal surface 18
It is the angle formed by. In this method, if X-rays that are continuous light and are nearly parallel are used as the light source, only X-rays having a wavelength that forms the diffraction crystal plane 19 of the asymmetric reflection crystal plate and the Brad angle θ _B are reflected by the Bragg reflection. Therefore, it is possible to perform monochromaticization and enlargement at the same time. Of course, this method can be used in this way.

The present invention is an apparatus using the above method for measuring a portion of interest. For the measurement of the entire tomographic plane of the subject, the measurement is performed without using the asymmetric reflection crystal plate as the resolution changing means, and in the subsequent measurement of the portion of interest, the measurement data with good resolution of the portion of interest is magnified by the asymmetric reflection crystal plate. To get From these data, it is possible to obtain a high-resolution monochromatic X-ray tomographic image of the target portion having a resolution higher than that of the detector.

When the light source is an X-ray which is nearly parallel, the asymmetric reflection by the crystal can be used not only for the enlargement as described above but also for the reduction as shown in FIG. Detectors with narrow element spacing
Since the total length is short, it may not be possible to cover the entire tomographic plane of the subject. In such a case, the reduction method described above makes it possible to measure a tomographic image of the entire cross section of the subject. This method can also be used in the device of the present invention. That is, first, the entire reduction plane of the subject is measured by this reduction method, and then the target portion is measured without placing the asymmetric reflection crystal plate or using the above-mentioned enlargement method, and the target portion is measured from both data. A monochromatic X-ray tomographic image with good resolution can be obtained.

As described above, the present invention, in measuring a tomographic image, includes measuring the entire tomographic plane of the subject and measuring the high resolution of the target portion in the tomographic image, It is about trying to get an image. There are various possible methods for actually combining these two measurement data,
When the number of angle pitches (the number of projected images) of both is set to the same number, the following method can be adopted. It is a method of combining both data for each projection, and its outline is shown in FIG. This figure shows the absorption curve of a certain projection, where X is the detector channel and θ is the incident X on the subject.
The angle of the line, μt, indicates the absorbance. In the figure, a curve 22 that spreads over the whole is data obtained by measurement of the entire fault plane, and a shaded portion 21 is an area obtained by high-resolution partial measurement. As can be seen from the enlarged view 24, the data obtained from the partial measurement 23
Has a large number of measured channels per unit length. By the way, in order to reproduce an image, it is necessary to have measurement data at equal intervals, so the outer part of the shaded area 21 is divided at the same intervals as the interval of the partial measurement data 23, and apparent measurement data is obtained. By calculating, it becomes possible to reproduce the image.

There are several possible methods for obtaining the apparent measurement data, but the simplest method is to connect two adjacent measurement data with a straight line and divide them to obtain the apparent measurement data. In addition, for several to several tens of adjacent measurement data, curve fitting a polynomial of degree 2 or higher,
A method of obtaining an optimum curve by the method of least squares and dividing the curve is also conceivable. In addition, a method of calculating from the data of several adjacent points by using the reciprocal of the distance from the division point to the measurement point as a weight is also considered. In any case, by combining the apparent measurement data obtained by such a method and the data obtained by the partial measurement, image reproduction becomes possible,
It is possible to obtain a high-resolution tomographic image of the part of interest.

As another method of combining the measurement data of the entire tomographic plane and the partial measurement data, the following method can be considered. That is, the area of the target portion to be obtained in advance is calculated by the method of first performing image reproduction of the entire tomographic plane and then shifting to partial measurement.
For example, by setting the scanning width at the time of partial measurement as a circle with the diameter as the diameter, etc., and by subtracting the amount absorbed outside this region from the whole tomographic image from the measurement data at the time of partial measurement, A high-resolution tomographic image of a part can be obtained. FIG. 6 shows the method. In the figure, the amount absorbed by the dotted line portion 28 of the subject 6 is obtained from the entire tomographic image, and is subtracted from the measured data to obtain the target portion.
Only 26 projection images are obtained. 27 shows the absorption curve of only the attention part.

Various methods can be considered for calculating the absorption amount in the dotted line portion 28, but each pixel of the entire tomographic image is finely divided, and the absorption coefficient of the obtained fine pixel is calculated from the original large pixel value. Further, a method for obtaining the absorption amount in the dotted line portion 28 by proportional distribution and the like from the transmission region of X-rays incident on each detection element and the overlapping degree of these fine pixels at each projection of each partial measurement Is simple. The value of the absorption coefficient of a fine pixel may be obtained from the values of four large adjacent pixels as shown in FIG. 7, for example. In the figure, 31 is a pixel at the time of measuring the entire tomographic image, and 32 is a fine pixel obtained by division. It is possible to calculate by weighting the reciprocal of the distance from the center of a large pixel to the center of a small pixel to be calculated and averaging. According to the method included in the device of the present invention, the fine pixel A represented by the hatched portion in FIG.
(4,4) of the absorption coefficient mu _{A (4,4)} is adjacent four large pixel A, B, C, and the absorption coefficient μ _A ~μ _D and D, from the center to the center of each pixel From the distance l _A ~ l _D , Get more. In this example, Becomes

By the way, such a data combination method has an advantage that it is not necessary to match the number of angle pitches.

Next, an embodiment of the present invention will be described with reference to FIG. First, an apparatus which is characterized in that an X-ray flux close to parallel is used and an image is magnified by asymmetric reflection in measuring a target portion will be described. The figure shows the outline. The device consists of a near parallel X-ray flux 1 (or 1 '),
An entrance slit 4 (or 4 ') for adjusting the shape of the X-ray flux, an exit slit 5 (or 5') for partially removing scattered rays of transmitted light of the subject 6, and an image for enlarging the image as necessary. Resolution changing means consisting of asymmetric reflection crystal plate 3,
Position-sensitive detector 9 (or 9 ') that finally detects X-rays, sequencer 13 that sends and receives data and transmits drive signals to the scanning system, etc. Control and arithmetic processing of the entire system including sequencer 13 A data processing device 14 including a computer for performing the above, an image display device 16 for displaying the obtained tomographic image, etc., a magnetic disk device 17 for storing data, a keyboard 15 for sending a command from a human, etc. . Reference numeral 10 is a rotary stage for the detector, 11 is a rotary stage for the asymmetric reflection crystal plate 3, and 12 is a support base for moving and adjusting the crystal plate 3. Reference numeral 8 denotes a supporting / rotating / scanning stage of the subject 6, and 7 denotes a target portion of the subject 6. 2 (or 2 '), which is the X-ray flux finally detected by the detector 9 (or 9').

First, the entire tomographic plane of the subject 6 is measured. In that case, the support 12 of the asymmetric reflection crystal plate 3 is moved so that the crystal plate 3 is out of the path of the X-ray flux, and the position-sensitive detector 9 ′ detects the total transmitted X-rays of the subject 6. X-ray flux 2 '
To detect. When one projection image measurement is completed, the subject 6
Is rotated by a certain angle and the next measurement is performed. This is repeated until the subject 6 rotates 180 to 360 degrees to obtain a series of transmission amount measurement data necessary for image reproduction.

Next, the measurement of the attention portion 7 will be performed. Next, the support 12 of the asymmetric reflection crystal plate 3 is moved in the opposite direction to bring it to a position where the crystal plate 3 asymmetrically reflects the X-ray flux. Subject 6
The X-rays that have passed through are asymmetrically reflected here, and are expanded as shown in FIG. 3 described above, and are incident on the position-sensitive detector 9. The detector 9 is obtained by moving the detector 9'to the position shown in the figure by a detector rotary stage 10. Therefore, the resolving power of the measurement system, which is determined by the resolution of the detector 9, is improved by this expanded amount, and the measurement data of the subject 6 with higher resolution can be obtained. When the incident X-ray flux 1 is monochromatic light, the asymmetric reflection crystal plate 3
Is carefully adjusted so that the monochromatic X-ray is reflected by the diffraction crystal plane 19 by Bragg reflection. Further, when continuous light is used for the incident X-ray flux 1 and the asymmetric reflection crystal plate 3 is used for monochromatization, the incident X-rays are separately separated during the first measurement of the entire tomographic plane of the subject 6. To obtain the same monochromatic X-ray. Since the asymmetric reflection is performed under extremely strict conditions, it is necessary to carefully cut out and set the crystal surface 18 of the asymmetric reflection crystal plate 3. Further, in measuring the tomographic image, the center of rotation of the subject 6 and the detectors 9, 9 '
Since it is necessary to strictly set the mutual positions of, the position of the center of rotation of the subject 6, the positions of the detectors 9 and 9'of the two measurements, the position and the angle of the asymmetric reflection crystal plate 3 before the measurement. It is necessary to adjust etc. sufficiently. The asymmetric reflection crystal plate 3 needs to be prepared in consideration of the wavelength of the X-rays used, the magnification, the shape of the X-ray flux, and the like. One thing to be aware of regarding data processing is that the X-ray flux expanded by the asymmetric reflection may be flipped left and right. Therefore, caution is required when obtaining a high-resolution tomographic image of the target portion 7 from both measurement data.

In this embodiment, synchrotron orbit radiant light was used as an X-ray flux that was nearly parallel, and was dispersed by a channel cut type Si single crystal spectrometer to obtain a monochromatic X-ray. This is because the synchrotron orbital radiation is almost parallel and has high intensity. The detectors 9 and 9'include element spacing of 25 μm and height of 2.5 m.
A photodiode array with m and 1024 elements was used. The detectors 9 and 9'have a scintillator coated on the surface for detecting X-rays. The asymmetric reflection crystal plate 3 as the resolution changing means uses a Si single crystal having a (220) diffraction surface, and the angle α formed between the crystal surface 18 and the diffraction crystal surface 19 is α =
Cut out to 6.2 °. First of all, in order to measure the whole tomographic image, the slit 4 ′ was used to set the X-ray flux to a width of 30 mm and a thickness of
It was molded to 0.5 mm. Further, the asymmetric reflection crystal plate 3 is set so as to be deviated from the path of the X-ray flux by moving the support 12. The detector 9 ′ is brought to the position in front of the incident X-ray 1 ′ by the detector rotation stage 10 and performs measurement. By repeating the rotation of the subject 6 and the measurement of the projected image, it is possible to measure the total transmission amount measurement data, which is the whole tomographic image of the subject 6 within a diameter of 25 mm.

Next, in order to measure the target portion 7, the incident X-ray flux was shaped by the slit 4 to have a width of 8 mm and a thickness of 0.5 mm. The asymmetric reflection crystal plate 3 is brought to a position where the X-ray flux can be asymmetrically reflected by the support 12. Before the measurement is started, the tilt and the tilt of the asymmetric reflection crystal plate 3 are adjusted so that the monochromatic X-rays to be used are reflected by the diffraction crystal plane 19 in the crystal plate 3 and incident on the detector 9. I'll do it. The setting position of the detector 9 is also confirmed before the measurement, and when the partial measurement is started, the position is accurately brought to that position. The asymmetric reflection crystal plate 3 used here is about 3 times as much as a monochromatic X-ray with a wavelength of 0.827Å (15 keV), about 5 times at a wavelength of 0.620 Å (20 keV), and a wavelength of 0.49.
At 6 Å (25keV), about 11 times expansion is performed,
A resolution superior to the inherent resolution of the detector 9 can be obtained by almost that amount. After all, the same scanning as in the case of measuring the entire tomographic image is performed to obtain high-resolution main part transmission amount measurement data of the target portion 7.

From the two sets of measurement data obtained in this way,
As the method of obtaining a tomographic image with high resolution, the above-mentioned two methods were used. That is, one is a method of correcting each projected image, and apparent measurement data is obtained by linear approximation of data of adjacent channels (FIG. 5). Another method is to obtain the entire tomographic image once, calculate the absorption amount outside the attention portion 7, and subtract it from the measurement data of the attention portion 7 to obtain the projection image of only the attention portion 7, and then This is a method for obtaining a tomographic image. (Fig. 6).

As described above, an example of application to image enlargement by asymmetric reflection using the asymmetric reflection crystal plate 3 at the time of measuring the attention portion 7 has been described, but the present invention is not limited to this embodiment. Other choices and combinations of measurement systems and data combination methods are possible. The light source is not limited to the synchrotron orbit synchrotron radiation, and of course, it does not matter. As the detectors 9 and 9 ', not only the photodiode array used in this embodiment, but also a gas chamber often used for medical purposes, an imaging tube having a higher resolution, or the like can be used. Several types of asymmetric reflection crystal plates 3 are preferably prepared in consideration of magnification, reflectance, X-ray flux shape, X-ray wavelength, and the like. In addition, when the X-rays are not completely parallel and have a slight spread, the asymmetric reflection crystal plate 3 can be processed so as to have a slightly concave surface and used. It is also possible to convert the X-rays to monochromatic for the first time at the time of asymmetric reflection without monochromating the X-rays, but in that case, separate spectroscopy is performed when measuring the entire tomographic image to extract the necessary monochromatic X-rays and It is necessary to carefully measure the positions of the surfaces.

Next, another embodiment will be described with reference to FIG. This embodiment is an example of an apparatus characterized in that an X-ray flux that is nearly parallel is used and an image is reduced by asymmetric reflection when measuring the entire tomographic image. The structure of the device is similar to that of FIG.
However, the asymmetric reflection crystal plate 3 which is the resolution changing means is fixed in a direction in which it is contracted, not expanded. When first measuring the entire tomographic plane of the subject 6, the crystal plate 3
By moving the support 12 of the crystal plate 3 to the X-ray of the incident X-ray 1.
Bring the flux to the position where it is asymmetrically reflected. The X-rays that have passed through the subject 6 are asymmetrically reflected here, reduced in size, and incident on the position-sensitive detector 9. With this method, it is possible to measure a tomographic image of the subject 6 having a width wider than the entire length of the detector 9. Next, the attention portion 7 is measured. The support 12 of the crystal plate 3 is moved so that the crystal plate 3 deviates from the path of the X-ray flux, and the transmitted light of the object 6 is detected by the detector 9'installed directly in front of the incident X-ray 1. To detect. Alternatively, an asymmetric reflection crystal plate for enlargement may be further provided in parallel on the asymmetric reflection crystal plan 3 for enlargement, and a smaller region may be measured with higher resolution. In this embodiment,
Since the asymmetric reflection crystal plate 3 is used for reduction, removing the crystal plate 3 from the path of the transmitted X-ray improves the resolution. The measurement scanning, the adjustment of the optical system and the asymmetric reflection crystal plate, the preparation, etc. are the same as those in the above-mentioned embodiment. The same applies to the case where the asymmetric reflection is stopped and the left and right sides are reversed. The use of this reduction method is particularly effective when such a detector 9 is used, because the position-sensitive detector 9 having a narrow element interval has a short total length.

In this embodiment, a system exactly the same as that of the above embodiment is adopted. That is, a synchrotron orbit radiated light is used as the X-ray flux, a photodiode array is used as the detector 9, and the same asymmetric reflection crystal plate 3 is turned to the same direction and fixed so as to perform reduction. did. For the measurement of the entire fault, the slit 4 forms an X-ray flux with a width of 60 mm and a thickness of 0.5 mm, and the X-rays transmitted through the subject 6 are reduced by the asymmetric reflection crystal plate 3 to be applied to the detector 9. It was made incident. In addition, in the measurement of the attention portion 7, here, X at the slit 4 '.
The line bundle was formed into a width of 15 mm and a thickness of 0.5 mm, and it was detected by a detector 9'placed in front of the incident light. The measurement data were combined by the same method as in the above-described example to obtain a high-resolution cross-sectional image of the target portion 7. Incidentally, the reduction rate is the reciprocal of the enlargement rate of the above-mentioned embodiment, and is the wavelength 0.827Å (15 ke
V) is about 1/3, and wavelength 0.620Å (20keV) is about 1/5.
The present invention is not limited to the present embodiment, such as the measurement system, the scanning system, the method of combining two sets of measurement data, and the like, exactly like the above-mentioned embodiments. In particular, when a photo tube such as a detector with higher resolution is used, the total length of the detector is short,
The present invention is effective. As the size of the subject 6 is increased, it is necessary to increase the reduction rate by that amount, but at this time, the total length of the asymmetric reflection crystal plate 3 is also required to be longer.

〔The invention's effect〕

According to the device of the present invention, a detector having a constant resolution is an X-ray that separately transmits the entire subject and a target portion, and at least one of the X-rays has a different resolution by the resolution increasing means. A set of transmitted X-rays is derived, and from the two sets of transmission amount measurement data obtained thereby, a tomographic image of the target portion of the subject can be obtained with a higher resolution than the intrinsic resolution of the detector by the data processing device. .

Further, according to the device of the present invention, it is possible to obtain high-resolution transmission amount measurement data without complicating the structure of the detector simply by providing the resolution changing means. It is possible to obtain a tomographic image of the part of interest at a high resolution.

Further, according to the device of the present invention, by using the resolution changing means in the opposite direction to the above, it is possible to measure an object having a width wider than the entire length of the detector.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an X-ray tomography apparatus according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of another embodiment of the present invention, and FIG.
Figures 4 and 5 are principle diagrams of image enlargement and reduction by an asymmetric reflection crystal plate, respectively, and Figures 5 and 6 are explanatory diagrams of a combination method of measurement data of the entire tomographic image and measurement data of a target portion, respectively. FIG. 7 is an explanatory diagram showing how to obtain the absorption coefficient in FIG. 1,1 ′ …… X-rays that are nearly parallel, 2,2 ′ …… Detected X-rays, 3
...... Asymmetric reflection crystal plate, 4,4 ′ …… Injection slit, 5,5 ′
...... Exit slit, 6 …… Subject, 7 …… Attention part, 8
...... Subject support rotation / scanning stage, 9,9 '…… Position sensitive detector, 10 …… Detector rotation stage, 11 …… Asymmetric reflection crystal plate rotation stage, 12 …… Asymmetric reflection crystal plate support Base, 13 ... Sequencer, 14 ... Data processing device,
15 …… Keyboard, 16 …… Image display device, 17 …… Magnetic disk device.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuhisa Usami 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-57-200134 (JP, A)

Claims (2)

[Claims] 1. An X-ray source, a detector for detecting X-rays transmitted through an object, and a data processing device for processing transmission amount measurement data obtained by the detector to obtain a tomographic image of the object. In the X-ray tomography apparatus, the data processing apparatus includes resolution changing means formed of an asymmetric reflection crystal plate provided in the X-ray path, and the data processing apparatus uses the X-rays that penetrate the entire subject and the resolution changing means. On the basis of two sets of transmission amount measurement data obtained by detecting and enlarging the X-rays transmitted by the X-ray transmitted through the target portion, or by the X-ray transmitted through the target portion and the resolution changing means. In this way, a high-resolution tomographic image of the target portion of the subject is obtained based on two sets of transmission amount measurement data obtained by detecting the reduced X-rays by reflecting and reducing the X-rays that pass through the entire subject. Specializing in what you got X-ray tomography apparatus according to. 2. The X-ray source according to claim 1, wherein the X-ray source is a fan beam, and the resolution changing means relatively contacts the support base of the subject to the X-ray source side to a position beyond the spread range of the fan beam. An X-ray tomography apparatus configured to be detachable.