JP2007252760A - X-ray tomographic method and x-ray tomographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To create a correct X-ray tomographic image regardless of the movement of a subject. <P>SOLUTION: A tomography position discriminating means 18 discriminates tomography positional data of an X-ray tomography means 12, and the tomography positional data are stored in a tomography position data storing means 19. First and second reference relative position operating means 26 and 27 compute the reference relative position of the subject to markers at two other positions stored in the tomography position data storing means 19, with one of the image data detected by a flat-panel X-ray detector 11 as the reference image data. Then, first and second corrected image data generating means 28 and 29 correct the relative position of the subject to the markers for other image data so that the relative position matches the reference relative position, and creates first and second corrected image data. Image data of a number of tomographic faces are created by an image processing means 24 based on the reference image data and the first and second corrected image data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is obtained by irradiating a subject with X-rays by an X-ray irradiation means such as an X-ray tube, and detecting the X-rays transmitted through the subject by an X-ray detection means such as a flat panel X-ray detector. The present invention relates to an X-ray tomography method and an X-ray tomography apparatus for creating an X-ray tomography image of an imaging target tomographic plane in a subject using the obtained image data.

For X-ray tomography, the X-ray tube is moved in the horizontal direction with respect to the subject, and the imaging unit is moved in the horizontal direction opposite to the X-ray tube, so that the X-ray is incident on the subject. There has been a configuration in which a direction is changed and a tomographic image is obtained based on a geometric positional relationship (see Patent Document 1).
JP 2000-126169 A

  However, in the case of the conventional example as described above, when it is desired to obtain tomographic images on a large number of tomographic planes, X-rays must be irradiated and photographed as many times as the number of tomographic images to be obtained. There has been a problem that the number of X-ray irradiations increases, the X-ray dose to be irradiated increases, and the burden of exposure on the subject increases.

  Therefore, based on the image data from the X-ray detection means obtained by photographing at a plurality of positions, the plurality of image data are positioned so that tomographic images on a large number of tomographic planes can be obtained with a small number of X-ray irradiation times. In order to create an X-ray tomographic image of an imaging target tomographic plane in a subject by processing so as to overlap each other.

  However, if the subject moves within the imaging time interval when imaging at a plurality of positions, the image data at different positions will be overlaid, and a problem that a correct X-ray tomographic image cannot be created. there were.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to enable a correct X-ray tomographic image to be created regardless of the movement of a subject.

The X-ray tomography method according to the first aspect of the present invention has the following configuration in order to achieve the above-described object.
That is, the X-ray irradiation means for irradiating the subject with X-rays, the X-ray detection means for detecting X-rays transmitted through the subject, and the relative positions of the X-ray irradiation means and the X-ray detection means X-ray tomography means for changing the setting to a plurality of positions around the imaging region for the specimen, imaging position data storage means for storing imaging position data in the X-ray tomography means, and image data from the X-ray detection means An X-ray tomographic image of an imaging target tomographic plane in the subject based on image data storage means for storing image data, imaging position data from the imaging position data storage means, and image data from the image data storage means An X-ray tomography apparatus including an image processing unit to be created is provided so that a marker whose relationship with the subject is specified in advance is moved integrally with the subject, and image data obtained together with the marker is obtained. The basis, is characterized in that to create an X-ray tomographic image by correcting the subject motion.

(Action / Effect)
According to the configuration of the X-ray tomography method of the first aspect of the present invention, the relative position between the X-ray irradiating means and the flat panel X-ray detector with the X-ray tomography means centered on the imaging region with respect to the subject. Is set to multiple positions, X-rays are irradiated at each position to obtain image data, and the position and size of the marker on the image data provided to move integrally with the subject are specified in advance. The movement of the subject is corrected based on the relationship with the subject, and the corrected image data is overlapped while being shifted in a direction parallel to the detection surface of the X-ray detection means, and X on the tomographic plane at a desired position A line tomographic image can be created.
Therefore, since an X-ray tomography apparatus is obtained based on image data in which the movement of the subject is corrected, a single X-ray irradiation amount can be reduced, and a plurality of tomographic planes can be obtained from a plurality of image data obtained by irradiation. Therefore, the number of times of X-ray irradiation can be reduced, and the X-ray tomographic image can be obtained as a whole with a small amount of X-ray irradiation and a small number of times of irradiation. Therefore, a correct X-ray tomographic image can be created regardless of the movement of the subject.

  According to a second aspect of the present invention, there is provided an X-ray irradiation means for irradiating a subject with X-rays, an X-ray detection means for detecting X-rays transmitted through the subject, the X-ray irradiation means and the X-ray detection. An X-ray tomography unit that changes a relative position with respect to the unit to a plurality of positions centering on an imaging region with respect to a subject, an imaging position data storage unit that stores imaging position data in the X-ray tomography unit, An image data storage unit for storing image data from the X-ray detection unit, an imaging target tomography in the subject based on the imaging position data from the imaging position data storage unit and the image data from the image data storage unit In an X-ray tomography apparatus comprising an image processing means for creating an X-ray tomographic image of a surface, together with a marker that is provided so as to move integrally with a subject and whose relationship with the subject is specified in advance Was based on the image data, constituting an image data correction means for creating a corrected image data by correcting the subject motion.

(Action / Effect)
According to the configuration of the X-ray tomography apparatus of the second aspect of the invention, the movement of the subject is corrected by the image data correction means, and the corrected image data is shifted in a direction parallel to the detection surface of the X-ray detection means. However, it is possible to create an X-ray tomographic image on a tomographic plane at a desired position by overlapping.
Therefore, an X-ray tomography apparatus suitable for carrying out the method according to the first aspect can be provided.

  According to a third aspect of the present invention, in the X-ray tomography apparatus according to the second aspect of the present invention, the image data correction means is provided on one of the plurality of image data stored in the image data storage means. The relative position between the subject and the marker is set as the reference relative position, and with other image data, the corrected image data is generated so that the relative position between the subject and the marker on the image data matches the reference relative position. Constitute.

(Action / Effect)
According to the configuration of the X-ray tomography apparatus of the invention according to claim 3, the movement of the subject in the other image data is determined based on one of the image data obtained by irradiating X-rays at a plurality of positions. It can be corrected.
Therefore, for example, when performing imaging at the first position, it is possible to avoid the trouble of artificially measuring the relative positional relationship between the marker and the subject and the relative positional relationship between the marker and the X-ray detection means, X-ray tomography can be performed easily.

According to the configuration of the X-ray tomography method of the first aspect of the present invention, the relative position between the X-ray irradiating means and the flat panel X-ray detector with the X-ray tomography means centered on the imaging region with respect to the subject. Is set to multiple positions, X-rays are irradiated at each position to obtain image data, and the position and size of the marker on the image data provided to move integrally with the subject are specified in advance. The movement of the subject is corrected based on the relationship with the subject, and the corrected image data is overlapped while being shifted in a direction parallel to the detection surface of the X-ray detection means, and X on the tomographic plane at a desired position A line tomographic image can be created.
Therefore, since an X-ray tomography apparatus is obtained based on image data in which the movement of the subject is corrected, a single X-ray irradiation amount can be reduced, and a plurality of tomographic planes can be obtained from a plurality of image data obtained by irradiation. Therefore, the number of times of X-ray irradiation can be reduced, and the X-ray tomographic image can be obtained as a whole with a small amount of X-ray irradiation and a small number of times of irradiation. Therefore, a correct X-ray tomographic image can be created regardless of the movement of the subject.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an overall perspective view of an X-ray tomography apparatus according to an embodiment of the X-ray tomography apparatus of the present invention, and FIG. 2 shows the positional relationship among an X-ray tube, a flat panel X-ray detector, and a subject. FIG. 2 is a schematic front view, in which a main column 2 is provided on a base 1, a holding unit 3 is provided on the main column 2, and a table 4 on which a subject H is mounted is provided on the holding unit 3. The subject H is provided on the surface of the abdomen so that the marker M moves integrally with the subject H with a tape or the like. For example, a sphere having a diameter of about 1 cm is used as the marker M, and an acrylic resin that can be identified without impairing the permeability to X-rays is used as the material.

  The holding unit 3 is provided so as to be capable of being driven and moved in the longitudinal direction of the subject H via an X-ray tube moving motor 6 (see FIG. 3) in which the column 5 can be rotated forward and backward. An X-ray tube 9 as an X-ray irradiating means for irradiating the subject H with X-rays can be driven to rotate around a horizontal axis through a swing motor 8 (see FIG. 3) capable of forward and reverse rotation at the tip. Is provided. Thereby, the position of the X-ray tube 9 can be changed in the longitudinal direction of the subject H around the imaging region with respect to the subject H.

X-ray detection means for detecting X-rays transmitted through the subject H so as to be able to be driven and moved in the longitudinal direction of the subject H via a detector moving motor 10 (see FIG. 3) capable of forward and reverse rotation below the table 4. Is a high-sensitivity flat panel X-ray detector 11 mainly composed of CdZnTe (cadmium zinc telluride). Accordingly, the position of the flat panel X-ray detector 11 can be changed in the longitudinal direction of the subject H around the imaging region with respect to the subject H.
As the flat panel type X-ray detector 11, a high sensitivity type using Se, PbI ₂ , HgI ₂ , CdTe or the like as a main material may be used.

  A configuration in which the position of the X-ray tube 9 is changed in the longitudinal direction of the subject H with the X-ray tube moving motor 6 and the swinging motor 8 as the center, and the detector moving motor 10. Thus, the X-ray tube 9 and the flat panel X-ray detector 11 are arranged in such a manner that the position of the flat panel X-ray detector 11 is changed in the longitudinal direction of the subject H around the imaging region with respect to the subject H. The X-ray tomographic imaging means 12 (see FIG. 3) is configured so that the relative position can be changed to a plurality of positions around the imaging region with respect to the subject.

As shown in the block diagram of FIG. 3, the X-ray tube moving motor 6 and the swing motor 8 are provided with X-ray tube position detecting means 13 such as a rotary encoder, and the movement amount of the X-ray tube 9 and the X-ray irradiation. Based on the direction, the position of the X-ray tube 9 around the imaging region can be detected.
Further, detector position detection means 14 such as a rotary encoder is attached to the detector moving motor 10 so that the position of the flat panel X-ray detector 11 centering on the imaging region can be detected.
An X-ray irradiation control unit 15 is connected to the X-ray tube 9 and is configured to set the irradiation X-ray dose based on an operation from the main control unit 16 and to control the irradiation timing.

Each of the flat panel X-ray detector 11, the X-ray tube position detection means 13, the detector position detection means 14 and the main control unit 16 is connected to the microcomputer 17.
The microcomputer 17 includes a photographing position determination means 18, a photographing position data storage means 19, an image data storage means 20, a reference image data storage means 21, first and second image data storage means 22, 23, and an image data correction means. 24 and image processing means 25 are provided.

The imaging position determination means 18 detects the position of the X-ray tube when the X-ray tomography means 12 sets the position data at the time when the X-ray is irradiated by the operation from the main controller 16, that is, the imaging position data. The determination is made based on the positions of the X-ray tube 9 and the flat panel X-ray detector 11 detected by the means 13 and the detector position detecting means 14, respectively.
The shooting position data storage means 19 stores the shooting position data determined by the shooting position determination means 18.

The image data storage means 20 stores image data detected by the flat panel X-ray detector 11.
The reference image data storage means 21 reads out, for example, image data obtained by the second imaging, which is set in advance from the three imagings by X-ray irradiation, from the image data storage means 20 and stores it as reference image data. ing.
The first image data storage means 22 reads out, for example, image data obtained by the first imaging among the three imagings by X-ray irradiation from the image data storage means 20 and stores it as the first image data. It is supposed to be.
In the second image data storage means 23, for example, image data obtained by the third imaging is read out from the image data storage means 20 and stored as second image data among the imagings by the X-ray irradiation three times. It is supposed to be.

The image data correcting unit 24 includes first and second reference relative position calculating units 26 and 27 and first and second corrected image data creating units 28 and 29.
In the first reference relative position calculation means 26, based on the reference image data from the reference image data storage means 21 and the position when the first image data from the shooting position storage means 19 is shot, The reference relative position between the subject H and the marker M in the image data is calculated and obtained. That is, the first image in the first imaging, which is detected by the flat panel X-ray detector 11 when the subject H does not move and is imaged in exactly the same state at the first time and the second time. The relative position between the subject H and the marker M on the data is obtained as the reference relative position.
In the second reference relative position calculation means 27, based on the reference image data from the reference image data storage means 21 and the position when the second image data from the shooting position storage means 19 is shot, the second reference relative position calculation means 27 The reference relative position between the subject H and the marker M in the image data is calculated and obtained. That is, the second image in the third imaging that is detected by the flat panel X-ray detector 11 when the subject H does not move and is imaged in the same state in the second and third times. The relative position between the subject H and the marker M on the data is obtained as the reference relative position.

In the first corrected image data creation means 28, the relative position between the subject H and the marker M in the actual first image data from the first image data storage means 22 and the first reference relative position calculation means 26. The reference relative position between the subject H and the marker M obtained in step 1 is compared, the first image data is corrected so that the relative position matches the reference relative position, and first corrected image data is created. It is like that.
In the second corrected image data creation means 29, the relative position between the subject H and the marker M in the actual second image data from the second image data storage means 22 and the second reference relative position calculation means 27. The reference relative position between the subject H and the marker M obtained in step (2) is compared, the second image data is corrected so that the relative position matches the reference relative position, and second corrected image data is created. It is like that.

In the image processing means 24, the first and second corrected image data from the first and second corrected image data creating means 28 and 29 are respectively applied to the reference image data from the reference image data storage means 21 in the horizontal direction. The X-ray tomographic image is appropriately created at a predetermined position by superimposing them while adjusting the shift amount.
In the figure, reference numeral 30 denotes a storage medium such as a floppy or CD for storing the X-ray tomographic image created by the image processing means 25 as data.

  Next, with respect to the procedure for creating the X-ray tomographic image, a schematic diagram for explaining the X-ray irradiation state in FIG. 4A and the image data extraction of the tomographic planes in FIGS. 4B and 4C. This will be described with reference to a schematic diagram provided for explanation of the above.

First, X-rays are emitted from the X-ray tube 9 at a predetermined position A1, and the first image data detected by the flat panel X-ray detector 11 disposed at the predetermined position B1 at that time is image data storage means. 20 is stored in the first image data storage means 22.
At this time, the position of the X-ray tube 9 is detected by the X-ray tube position detector 13 and the position of the flat panel X-ray detector 11 is detected by the detector position detector 14. The imaging position data is determined from the position A1 of the X-ray tube 9 and the position B1 of the flat panel X-ray detector 11, and the imaging position data determined by the imaging position determination means 18 is stored in the imaging position data storage means 19. Keep it.

Thereafter, the X-ray tube 9 is moved to the center position A, and the irradiation direction of the X-ray tube 9 is set at a position where the center of the X-ray bundle is first in the middle of the body thickness direction of the subject H. Then, the flat panel X-ray detector 11 is moved to the center position B and irradiated with X-rays in the same manner as described above. The reference image data detected by the flat panel X-ray detector 11 arranged at a predetermined position B is taken from the image data storage means 20 into the reference image data storage means 21 and stored.
Similarly, the imaging position data is determined from the position A of the X-ray tube 9 and the position B of the flat panel X-ray detector 11, and the imaging position data determined by the imaging position determination means 18 is used as the imaging position data storage means 19. Remember it.

Thereafter, the X-ray tube 9 is moved to the second position A2, and the irradiation direction of the X-ray tube 9 is set to a position where the center of the X-ray bundle is first in the middle of the body thickness direction of the subject H. The flat panel X-ray detector 11 is moved to the second position B2 and irradiated with X-rays in the same manner as described above. At that time, the second image data detected by the flat panel X-ray detector 11 arranged at the predetermined position B2 is taken from the image data storage means 20 into the second image data storage means 23 and stored therein.
Similarly, the imaging position data is determined from the second position A2 of the X-ray tube 9 and the second position B2 of the flat panel X-ray detector 11, and the imaging position data determined by the imaging position determination means 18 is determined. This is stored in the photographing position data storage means 19.

In each of the first and second reference relative position calculation means 26 and 27, as the reference relative position of the marker M with respect to the subject H, the height of the marker M with respect to the detection surface of the flat panel X-ray detector 11 and the position in the horizontal direction. And ask.
That is, as shown in the figure for explaining the calculation of the vertical position of the marker in FIG. 5A, the size S1 and the actual size S (predetermined value) of the marker M on the reference image The height h1 of the marker M with respect to the detection surface of the flat panel X-ray detector 11 is obtained based on the ratio (S / S1). That is, since the height h of the X-ray tube 9 with respect to the detection surface of the flat panel X-ray detector 11 is known in advance,
(H−h1) / h = S / S1
And
h1 = h · (1-S / S1)
Can be obtained as
Further, the horizontal position is the length from both ends of the image plane of the flat panel X-ray detector 11 in the reference image, as shown in FIG. 5B for explaining the calculation of the horizontal position of the marker. Find X and Y.
In FIG. 5, the marker M is exaggerated for easy understanding.

  Next, as shown in the drawing for explaining the correction operation by the first corrected image data creating means in FIG. 6A, based on the height h1 and the lengths X and Y obtained as described above. The relative position of the subject H and the marker M to be detected by the flat panel X-ray detector 11 when the X-ray tube 9 and the flat panel X-ray detector 11 are at the first positions A1 and B1. Is the reference position (M), the subject H (the image plane detected by the flat panel X-ray detector 11) in the actual first image data read from the first image data storage means 22, and the marker M1 Are compared with the above-mentioned reference relative position M, the differences DX1 and DY1 are corrected so as to match the reference relative position M, and first corrected image data is created.

  Similarly, as shown in the drawing for explaining the correction operation by the second corrected image data creating means in FIG. 6B, based on the height h1 and the lengths X and Y obtained as described above. Thus, when the X-ray tube 9 and the flat panel X-ray detector 11 are at the second positions A2 and B2, the relative relationship between the subject H and the marker M to be detected by the flat panel X-ray detector 11 The position is a reference position (M), and the subject H (image plane detected by the flat panel X-ray detector 11) and marker in the actual second image data read from the second image data storage means 23 and the marker Relative position with M2 The above-mentioned reference relative position M is compared, the differences DX2 and DY2 are corrected so as to match the reference relative position M, and second corrected image data is created.

  As described above, based on the reference image data DB and the first and second corrected image data DB1 and DB2 obtained at the three photographing positions, the image processing unit 24 converts the image data on a number of tomographic planes. It is designed to create.

  That is, image data is obtained on one tomographic plane D1 above the reference tomographic plane D (shown at a position floating above the subject H for the sake of clarity, but actually becomes a tomographic plane on the subject H). Considering the case, the reference image data DB and the first and second corrected image data DB1 and DB2 both include an X-ray component transmitted through the tomographic plane D1.

Therefore, considering the displacement amounts L1 and L2 of the position that passes through the center of the tomographic plane D1 at three positions [(b) of FIG. 4], the center positions are made to coincide as shown in (c) of FIG. The three reference image data DBs are superposed on the first and second corrected image data DB1 and DB2.
As a result, the X-rays transmitted through the tomographic plane D1 are tripled, and the image data of the tomographic plane D1 can be obtained at a high density.
In this way, by shifting by an integral multiple of the length corresponding to one pixel, the three reference image data DB and the first and second corrected image data DB1, DB2 can be accurately detected on a number of tomographic planes. Image data can be created.

  In the above-described embodiment, both the X-ray tube 9 and the flat panel X-ray detector 11 are moved to obtain the image data of the tomographic plane. As the present invention, the model shown in FIG. As shown in the figure, even if the configuration is such that only the X-ray tube 9 is moved and the flat panel X-ray detector 11 is not moved, as shown in the schematic diagram of FIG. It may be configured such that only the X-ray detector is moved and the X-ray tube 9 is not moved.

  In the above embodiment, an X-ray fluoroscopic apparatus having a plane parallel tomography function in which the X-ray tube 9 and the flat panel X-ray detector 11 are arranged to face each other is used. The present invention is not limited to such a type, and a type having a tomographic function using a C-arm can be realized. Further, a general X-ray imaging apparatus having a tomographic function that does not have a fluoroscopic function may be used. Further, as the X-ray detection means, an image intensifier may be used instead of the flat panel X-ray detector 11.

  In the above embodiment, the marker M is provided on the surface of the abdomen. For example, in the case of diagnosing the healing condition of the bone treated with the cast, the marker M is provided on the cast or the cast is provided. The marker M may be provided integrally in the body, such as using itself as a marker. The number of markers M is not limited to one, and two or three or more markers M may be provided at a predetermined distance.

1 is an overall perspective view of an X-ray tomography apparatus according to an embodiment of the present invention. It is a schematic front view which shows the positional relationship of an X-ray tube, a flat panel type X-ray detector, and a subject. It is a block diagram. (A) is a schematic diagram used for description of an X-ray irradiation state, and (b) and (c) are schematic diagrams used for description of image data extraction of a tomographic plane. (A) is a figure used for calculation explanation of the vertical position of a marker, and (b) is a figure used for calculation explanation of the horizontal position of a marker. (A) is a diagram for explaining the correction operation by the first corrected image data creating means, and (b) is a diagram for explaining the correcting operation by the second corrected image data creating means. (A) is a schematic diagram which shows the case where only an X-ray tube is moved, (b) is a schematic diagram which shows the case where only a flat panel type X-ray detector is moved.

Explanation of symbols

9 ... X-ray tube (X-ray irradiation means)
11. Flat panel X-ray detector (X-ray detection means)
DESCRIPTION OF SYMBOLS 12 ... X-ray tomography means 19 ... Imaging position data storage means 20 ... Image data storage means 24 ... Image data correction means 25 ... Image processing means H ... Subject M ... Marker

Claims (3)

  X-ray irradiation means for irradiating the subject with X-rays, X-ray detection means for detecting X-rays transmitted through the subject, and relative positions of the X-ray irradiation means and the X-ray detection means are determined with respect to the subject. X-ray tomography means for changing the setting to a plurality of positions around the imaging region, imaging position data storage means for storing imaging position data in the X-ray tomography means, and image data from the X-ray detection means are stored. An X-ray tomographic image of the tomographic plane to be imaged in the subject is created based on the image data storage means, the imaging position data from the imaging position data storage means, and the image data from the image data storage means. An X-ray tomography apparatus provided with an image processing means is provided so that a marker whose relationship with the subject is specified in advance is moved integrally with the subject, and based on image data obtained together with the marker X-ray tomography method characterized by creating an X-ray tomographic image by correcting the subject motion.   X-ray irradiation means for irradiating the subject with X-rays, X-ray detection means for detecting X-rays transmitted through the subject, and relative positions of the X-ray irradiation means and the X-ray detection means are determined with respect to the subject. X-ray tomography means for changing the setting to a plurality of positions around the imaging region, imaging position data storage means for storing imaging position data in the X-ray tomography means, and image data from the X-ray detection means are stored. An X-ray tomographic image of the tomographic plane to be imaged in the subject is created based on the image data storage means, the imaging position data from the imaging position data storage means, and the image data from the image data storage means. In an X-ray tomography apparatus comprising an image processing means, the subject is based on image data obtained together with a marker that is provided so as to move integrally with the subject and whose relationship with the subject is specified in advance. X-ray tomography apparatus comprising the image data correcting means for generating a corrected image data by correcting the movement of the body. 3. The X-ray tomography apparatus according to claim 2, wherein the image data correction means uses the relative position between the subject and the marker on one of the plurality of image data stored in the image data storage means as a reference. An X-ray tomography apparatus that generates corrected image data so that the relative position between the subject and the marker on the image data matches the reference relative position in the other image data.

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