JP2006288765A - Digital x-ray tomography method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in X-ray tomography by constitution using an image sensor in a thin and long shape and to provide an X-ray tomography method for reducing an exposure and obtaining high quality images. <P>SOLUTION: For each of a plurality of X-ray scanning track surfaces 1 having the same extent specified beforehand, by performing irradiation with an X-ray slit beam B extended in a vertical direction while parallelly moving it in a horizontal direction in the state of keeping an irradiation angle made different according to each of the X-ray scanning track surfaces 1, the transmission images of an object (o) by an X-ray image sensor 12a are radiographed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray tomographic imaging method and an X-ray tomographic imaging apparatus for synthesizing tomographic images by superimposing a plurality of transmission images obtained from the image receiving system when the X-ray tube and the image receiving system are moved. It is about.

The following patent document describes an apparatus for synthesizing tomographic images by superimposing a large number of transmission images obtained from an image receiving system when the X-ray tube and the image receiving system are moved.
The X-ray tomographic imaging apparatus captures the target cross section while defocusing other than the target cross section by photographing the X-ray tube and the image receiving system while moving the X-ray tube and the image receiving system in the opposite directions around the target point. The image receiving system of the X-ray tomographic imaging apparatus is composed of an image intensifier and a TV camera as shown in FIG. 1 of the patent document.

  FIG. 15 is a drawing for explaining the principle of the X-ray tomographic imaging. Here, when the X-ray tube 11 is at the position (1), the image receiving system 12 obtains a transmission image in which the points A, X, and B are projected onto the points A1, X1, and B1, and then the X-ray tube. When 11 is moved to position (2), a transmission image in which points A, X, and B are projected onto points A2, X2, and B2 is obtained. Then, if these two transmission images are superimposed so that X1 and X2 coincide, the tomographic layer in which the depth of the point X is the focal plane and the points A and B are blurred is synthesized. It is.

In recent years, digitalization of X-ray imaging apparatuses has progressed, and a CCD image sensor or the like is often used as an image receiving system. As such an image sensor, a planar image sensor that outputs a two-dimensional charge image, and a one-dimensional charge image that is output during scanning photography and arranged in time series, the two-dimensional image is displayed. An elongated image sensor to be generated can be used.
Japanese Patent No. 3166194 FIG.

  Here, if a digital image sensor is employed in the image receiving system of the X-ray tomographic imaging apparatus according to the above-mentioned patent document to further increase the digitization or resolution, a planar image sensor can be used as the image sensor. Although it is easy to configure, surface image sensors with a large light receiving area are available at a very high price even if they are available, and the cost has a significant impact on the marketability of the equipment used. Become.

  On the other hand, when the elongated image sensor is used as a CCD image sensor, it is required to scan and photograph a plurality of transmission images in order to synthesize a tomographic image, but scanning imaging requires time. Thus, the subject is exposed to a wide X-ray cone beam during the imaging period, and the problem of the amount of exposure occurs.

  This method uses the same principle as panoramic imaging in which tomography is performed using relative rotation of an X-ray generator and an X-ray image sensor with respect to a subject. Since the X-ray generator is moving away from the X-ray generator and the X-ray image sensor has a smaller swing angle with respect to the subject than the X-ray generator, the portion of the subject closer to the X-ray generator However, there is a problem that the portion near the X look-ahead detector is not blurred and appears clearly.

  In addition, in the configuration using a wide X-ray cone beam, the magnification of the projected image differs depending on the distance from the X-ray tube in the transmission image, so when the tomographic images are synthesized by superimposing these transmission images In addition, the degree of blur is different between before and after the focal plane, and there is a problem that a high-quality image cannot be obtained.

  An object of the present invention is to solve the above-mentioned problems in X-ray tomographic imaging using a configuration using an elongated image sensor, and the amount of exposure can be reduced and a high-quality image can be obtained. A linear tomographic imaging method and apparatus are provided.

  In order to solve the above-mentioned problem, in the digital X-ray tomographic imaging method according to claim 1 which is the first invention, each of a plurality of X-ray scanning orbit planes having the same spread specified in advance spreads in the vertical direction. The X-ray slit beam having the X-ray image sensor is irradiated with the X-ray image sensor while translating the X-ray slit beam having a different irradiation angle corresponding to each of the X-ray scanning orbit planes while maintaining the irradiation angle. The transmission image of the subject about each of the plurality of X-ray scanning trajectory planes obtained in this way is taken and shifted with a predetermined positional relationship and superimposed on each other, thereby obtaining a desired X-ray tomographic image of the subject. Generate.

  According to a second aspect of the present invention, there is provided a digital X-ray tomography apparatus according to claim 2, wherein the X-ray generator irradiates an X-ray slit beam, an elongated X-ray image sensor corresponding to the X-ray slit beam, and the X-ray image sensor. Moving means for relatively moving the X-ray image sensor and the elongated X-ray image sensor with the subject sandwiched therebetween, the X-ray generator, the elongated X-ray image sensor, and the moving means In a digital X-ray tomographic imaging apparatus comprising a control means for taking a transmission image of the subject by controlling the image, and an image processing means, the control means sets a specific cross section at the center of the region of interest of the subject By moving the setting means, the X-ray generator, and the elongated X-ray image sensor along a trajectory including at least a rotational movement component relative to the subject, An incident angle control means for specifying a plurality of incident angles of the line slit beam, and an X-ray slit beam irradiated from the X-ray generator are spread to maintain the specified incident angle and include the region of interest. The X-ray image sensor having the elongated shape is moved so that the X-ray slit beam follows the X-ray slit beam in parallel with the specific cross section. Imaging control means for acquiring imaging data, and the image processing means generates transmission image generation means for generating individual transmission images corresponding to the respective incident angles from the imaging data corresponding to the respective incident angles; Tomographic image synthesizing means for synthesizing the tomographic images of the subject by aligning individual transmission images corresponding to the corners at the position of the specific cross section and superimposing them on each other.

  The digital X-ray tomography apparatus according to claim 3 is the digital X-ray tomography apparatus according to claim 2, wherein the incident angle control means relatively moves the X-ray generator and the elongated X-ray image sensor along a predetermined curve. By doing so, a plurality of incident angles of the X-ray slit beam are specified.

  According to a fourth aspect of the present invention, in the digital X-ray tomography apparatus according to the second aspect, the incident angle control means relatively moves the X-ray generator and the elongated X-ray image sensor along a predetermined straight line. Thus, a plurality of incident angles of the X-ray slit beam are specified.

  A digital X-ray tomographic imaging apparatus according to a fifth aspect is the digital X-ray tomography apparatus according to the third aspect, wherein the moving means includes a turning unit to which the X-ray generator and the elongated X-ray image sensor are fixed, The imaging control means drives the axis moving table to move the X-ray generator and the elongated X-ray on a plane perpendicular to the rotating axis. Synchronize with the image sensor and translate in the same direction.

  The digital X-ray tomographic imaging apparatus according to claim 6 is the digital X-ray tomography apparatus according to claim 4, wherein the moving means is a swivel in which the X-ray generator and the elongated X-ray image sensor are attached so as to be capable of parallel translation. And the swivel that rotates the swivel unit, the imaging control means drives the swivel unit to synchronize the X-ray generator and the elongated X-ray image sensor in the same direction. Translate to.

  According to a seventh aspect of the present invention, there is provided the digital X-ray tomographic imaging apparatus according to the fourth aspect, wherein the moving means is a fixed base on which the X-ray generator and the elongated X-ray image sensor are attached so as to be movable in parallel. The incident angle control means translates the X-ray generator and the elongated X-ray image sensor in a reverse direction along a predetermined straight line, so that a plurality of incident angles of the X-ray slit beam can be obtained. The imaging control means synchronizes the X-ray generator and the elongated X-ray image sensor in parallel in the same direction.

  The digital X-ray tomography apparatus according to claim 8 is the digital X-ray tomography apparatus according to any one of claims 2 to 7, wherein the elongated X-ray image sensor outputs a charge image of the X-ray slit beam as a signal obtained by time delay integration. To do.

  In the digital X-ray tomographic imaging method according to claim 1, the X-ray slit beam having a spread in the vertical direction is maintained in a horizontal direction while maintaining an irradiation angle that is different according to each X-ray scanning orbit plane. Therefore, the X-ray exposure amount of the subject as a subject is reduced as compared with the method using a wide X-ray cone beam.

  In addition, since the irradiation angle is held during scanning of the transmission image, the magnification of the projected image is the same regardless of the movement distance, that is, the size of the image, in the parallel movement direction. When the tomographic images are synthesized by superimposing, the degree of blurring is equal before and after the focal plane, which also has the effect of obtaining a high-quality image.

  Since the digital X-ray tomographic imaging apparatus according to claims 2 to 8 is based on the method according to claim 1, the same effect is exhibited. Further, since an inexpensive elongated image sensor is used as the image sensor, the cost of the apparatus can be greatly reduced.

  As the best mode for carrying out the invention, first, the principle of the digital X-ray tomographic imaging method according to the first invention will be described with reference to FIGS. Next, a digital X-ray tomographic imaging apparatus according to the second invention will be described.

  1A and 1B are schematic views for conceptually explaining a digital X-ray tomographic imaging method according to the present invention, and FIG. 2 is a drawing for explaining an irradiation angle of an X-ray slit beam. FIG. 3 is a simple sketch of a subject for explaining the principle, and FIG. 4 is a diagram for explaining a plurality of transmission images and tomographic images.

  In the digital X-ray tomographic imaging method according to the present invention, the vertical direction irradiated from the X-ray generator 11 to each of a plurality of X-ray scanning orbit planes 1 (# 1 to # 3) having the same spread specified in advance. By irradiating the X-ray slit beam B having a spread to the X-ray image sensor 12a with the X-ray image sensor 12a irradiating the X-ray slit beam B while translating the X-ray slit beam B in the X-ray scanning orbit plane while maintaining the irradiation angle differently. A transmission image R (# 1 to # 3) of the subject o is captured by the X-ray slit beam B that has passed through the subject o, and each of the plurality of X-ray scanning orbit planes 1 (# 1 to # 3) thus obtained is captured. A desired X-ray tomographic image T of the subject o is generated by superimposing the transmission images R (# 1 to # 3) of the subject o on the basis of a predetermined positional relationship.

  The above “having a spread” means that the spread BL in the direction in which the X-ray slit beam B travels from the X-ray generator 11 is the same as shown in FIG. “Having a spread” means that the X-ray slit beam B has a fan-shaped spread width BW.

  That is, in the example of FIG. 1A, a specific section v that is to be an imaging plane of the X-ray tomographic image T is set in the region of interest s of the subject o, and three X-rays that pass through the specific section v. Scanning track surface 1 (# 1 to # 3) is defined. Each of the X-ray scanning orbit planes 1 (# 1 to # 3) is arranged so that the X-ray slit beam B moving laterally inside thereof maintains a specific irradiation angle, that is, with respect to a specific cross section v. It has an inclined quadrangular pyramid profile so as to maintain a unique incident angle. In this example, three X-ray scanning orbit planes 1 (# 1 to # 3) are used. However, this is only an example. If a larger number of X-ray scanning orbit planes are used, a smoother fault is obtained. An image can finally be obtained.

  The irradiation angle of the X-ray slit beam B is defined as shown in FIG. 2, and the X-ray slit beam B moving laterally inside the X-ray scanning orbit plane 1 (# 1 to # 3) The crossing angle with the cross section S is given as θ (# 1 to # 3). In the above example, the specific cross section v is the cross section S mentioned here.

  The X-ray image sensor 12a has an elongated shape and can be constituted by a CCD image pickup device or the like corresponding to the vertical spread of the X-ray slit beam B. The X-ray intensity corresponding to the horizontal position is measured and output while moving in the horizontal direction following the X-ray slit beam B that moves to the right.

  The width in the longitudinal direction of the detection surface of the X-ray image sensor 12a does not necessarily coincide with the width of the vertical spread of the X-ray slit beam B, and is actually irradiated from the detection surface of the X-ray image sensor 12a. Although the width of the vertical slit beam B in the vertical direction may be wider, only the portion of the X-ray slit beam B detected by the X-ray image sensor 12a is important for imaging. Since it is an element, the spread of the X-ray scanning orbital plane defined above is defined in the range from the irradiation from the X-ray generator 11 to the detection by the detection plane of the X-ray image sensor 12a.

  The transmission image R (# 1 to # 3) of the subject o by the X-ray slit beam B that has passed through the subject o is the X-ray scanning orbit plane 1 (# 1 to # 3) measured and output by the X-ray image sensor 12a. The X-ray intensities corresponding to the horizontal positions of are sequentially arranged in time series. The tomographic image T is synthesized by superimposing the transmission images R (# 1 to # 3) on the basis of a predetermined positional relationship. The synthesis of the tomographic image T will be described more specifically below in accordance with a simple subject example.

  The simple subject o shown in FIG. 3A has a wedge shape, and a metal plate M that absorbs X-rays and does not pass through is provided on an inclined surface that can be seen from the incident direction of the X fine slit beam B. The other portion oo shown in FIG. 3B is made of a material that transmits X. The subject o is disposed toward the X-ray scanning orbital plane 1 (# 2) so that the entire region is the region of interest s and the specific cross section v passes through the central portion of the metal plate M. Therefore, when viewed from the incident direction of the X fine slit beam B, the lower part of the metal plate M is on the near side with respect to the specific cross section v, and the upper part is on the back side. FIG. 3B is a sectional view taken along line AA in FIG.

  The transmission image of the wedge-shaped subject o is as shown in FIG. Here, the broken line indicates the position of the specific cross section v. The inclination of the metal plate M in the transmission images R (# 1) and R (# 3) is the incident direction of the X fine slit beam B in the transmission image R (# 1) with respect to the X-ray scanning orbit plane 1 (# 1). , The near side is displaced to the right side, whereas the transmission image R (# 3) for the X-ray scanning orbit plane 1 (# 3) is displaced to the left side. This can be easily understood by considering which side of the both sides of the wedge shape is visible when viewed from the X-ray scanning orbit planes 1 (# 1) and 1 (# 3). For convenience of understanding, R (# 1) to (# 3) indicate transmission images viewed from the X-ray generator 11 side.

  These transmission images R (# 1 to # 3) are superimposed on each other so that the metal plates M cross at the position of the specific cross section v, so that the tomographic image T at the specific cross section v is synthesized.

  In this tomographic image T, at the position of the specific cross section v when viewed from the incident direction of the X-ray slit beam B, the same metal plate M is superposedly superimposed, but on the near side or the far side. As it goes, the overlap of the same metal plate M gradually shifts from side to side. This means that in the tomographic image T, the image is clear and clear at the position of the specific section v, but the image is blurred at other positions.

  Therefore, when a living tissue or the like is photographed as the subject o, only the tissue near the specific cross section v of the region of interest s is clear, and an image in which the tissue at other positions is blurred and unclear can be obtained. As can be understood from FIG. 3, if the positions of the transmission images R (# 1) to (# 3) are shifted from each other and overlapped with each other, the position of the focused surface is set to the front of the specific section v. It is also possible to move to the side or back side. Here, the left and right displacement amounts of the transmission images R (# 1) to (# 3) and the position of the surface on which the focal point has a unique functional relationship.

  According to the above method, the X-ray slit beam B is configured to move laterally inside the X-ray scanning orbit plane 1 (# 1 to # 3). Compared with a configuration using a wide cone beam, the amount of X-ray exposure is greatly reduced.

  In addition, since the irradiation angle is maintained during scanning imaging in which the X-ray slit beam B moves in the lateral direction, the magnification of the projected image becomes equal in the translation direction regardless of the size of the image. Therefore, when the tomographic images are synthesized by superimposing the transmission images, the degree of blurring in the distant portions is equal before and after the specific cross section that is the focal plane, and a high-quality image is obtained.

  Here, as a second invention, an example of a digital X-ray tomography apparatus will be described with reference to FIGS.

  FIG. 5 is a block diagram conceptually illustrating the basic configuration of the digital X-ray tomography apparatus M. This digital X-ray tomography apparatus M has an X-ray generator 11 that irradiates an X-ray slit beam B having a spread in the vertical direction, and an X-ray having an elongated X-ray image sensor 12a corresponding to the spread. A moving means 13 for relatively moving the detector 12, the X-ray generator 11 and the X-ray detector 12 with the subject o interposed therebetween, and the X-ray generator 11 and the X-ray detector 12 A display operation unit 14 a is added, and a control unit 14 that controls the moving unit 13 to capture a transmission image of the subject o and an image processing unit 15 are provided.

  The X-ray generator 11 includes an X-ray tube that is supplied with a predetermined tube voltage or tube current to generate radial X-rays, a metal collimator in which a predetermined slit is formed, and the like. The line slit beam B is irradiated toward the X-ray detector 12 arranged opposite to the line slit beam B.

  The X-ray detector 12 is composed of a fluorescent filter that converts X-rays into visible light, an elongated X-ray image sensor 12a such as a CCD sensor having a long rectangular light receiving section, and the like. The intensity of X-rays converted into visible light is measured and imaging data is output. Further, a TDI (time delay integration) clock generator can be built in, and the sensitivity to X-rays can be increased, and the charge image of the X-ray slit beam B can be output as a time-delay integrated signal. .

  The moving means 13 horizontally places the swivel axis Z on a swivel part 13a to which the X-ray generator 11 and the X-ray detector 12 are fixed, and a plane XY perpendicular to the swivel axis Z of the swivel part 13. It comprises an axis moving table 13b to be moved. The turning of the turning part 13a and the horizontal movement of the turning axis Z in the XY plane are performed by a moving mechanism using three stepping motors controlled independently by the control means 14 as drive sources. A main body frame for supporting the shaft moving table 13b is not shown.

  The control unit 14 includes a cross-section setting unit 14b that sets a specific cross-section v at the center of a region of interest s (for example, a specific tooth) of a subject o (for example, a human head), an X-ray generator 11, and an X-ray detector 12. Are moved by a trajectory including at least a relative rotational movement component with respect to the subject o, thereby specifying a plurality of incident angles θ (# 1 to #n) of the X-ray slit beam with respect to the set specific cross section v. The X-ray slit beam B irradiated from the incident angle control means 14c and the X-ray generator 11 maintains a specified incident angle θ (#i) and has a spread including the region of interest s. Thus, the X-ray detector 12 is moved so as to follow the X-ray slit beam B in parallel with the specific cross section v, thereby corresponding to each incident angle θ (#i). Photographing control means 14d for obtaining the photographed photographing data.

  In the above, “having a rotational movement component” simply means that the incident angle θ of the X-ray slit beam with respect to the specific cross section v is variable and is different for each of the above-mentioned parallel movements.

  The image processing unit 15 generates transmission image R (# 1 to #n) corresponding to each incident angle from the photographing data corresponding to each incident angle θ (# 1 to #n). Then, the individual transmission images R (# 1 to #n) corresponding to the respective incident angles are aligned with the position of the specific cross section v, that is, the position at a position away from the specific cross section v is blurred. Then, it has tomographic image synthesizing means 15b for synthesizing the tomographic image T of the subject o by overlapping each other.

Here, the basic operation of the digital X-ray tomography apparatus M will be described with reference to FIGS.
FIG. 6 is a flowchart for explaining a tomographic image processing procedure of the digital X-ray tomography apparatus M configured as described above, and FIG. 7 is an X-ray generator 11 and an X-ray generator in the tomographic image processing procedure. It is the top view seen from the upper side explaining the relative movement with respect to the to-be-photographed object 12 with the X-ray image sensor 12a with which the line detector 12 is provided.

  In the cross-section setting step 101, a specific cross-section v is set at the center of the region of interest s (for example, a specific tooth) inside the subject o (for example, a human head). This is done by positioning at a predetermined location between the generator 11 and the X-ray image sensor 12a. Since the positioning is relative, the position of the subject o is fixed, the moving means 13 is driven by the control of the cross-section setting means 14b, and the X-ray generator 11 and the X-ray detector 12 are moved. The subject o may be positioned at an appropriate position using subject fixing means that can be freely moved and fixed.

  In the incident angle setting step 102, the moving means 13 is driven by the control of the incident angle control means 14c, and the swivel part 13a to which the X-ray generator 11 and the X-ray detector 12 are fixed is swung to the specific section v. A plurality of incident angles θ (#i) of the X-ray slit beam are specified. At this time, the relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is a turning movement indicated by a solid arrow 102 in FIG.

  In the X-ray imaging step 103, the X-ray generator 11 and the X-ray detector 12 are operated, the moving means 13 is driven by the control of the imaging control means 14d, and the X-ray generation is performed by the axis moving table 13b. The device 11 and the X-ray detector 12 are synchronized and translated in a direction parallel to the specific cross section v. Thus, the X-ray slit beam B irradiated from the X-ray generator 11 scans a predetermined spread including the region of interest s while maintaining the incident angle θ (#i), and the X-ray detector 12 To obtain imaging data corresponding to the incident angle θ (#i). At this time, the relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is a parallel movement indicated by a dashed arrow 103 in FIG.

  In the transmission image generation step 104, each transmission image R corresponding to the incident angle θ (#i) is arranged by the transmission image generation means 15a by arranging the shooting data corresponding to the incident angle θ (#i) in time series. (#I) is generated. In this case, a clearer transmission image R (#i) can be obtained by performing an appropriate image quality adjustment process (gradation process or the like).

  The imaging end determination step 105 determines whether transmission images R (# 1 to #n) corresponding to all incident angles θ (# 1 to #n) have been generated. If not, As the next incident angle θ (# i + 1), the process returns to the incident angle setting step 102 and the above processing is repeated.

  In the tomographic image synthesizing step 106, the tomographic image synthesizing means 15b converts the individual transmitted images R (# 1 to #n) corresponding to the incident angles θ (# 1 to #n) at positions away from the specific cross section v. The tomographic images T of the subject o are synthesized by aligning the portions so that the portions are blurred and overlapping each other.

  Next, another example of the digital X-ray tomographic imaging apparatus according to the second invention will be described with reference to FIGS.

  FIG. 8 is a block diagram conceptually illustrating the basic configuration of a digital X-ray tomography apparatus M1, which is another example, and FIG. 9 is an X-ray generator 11 and an X-ray detector in a tomography process procedure. It is the top view seen from the upper side explaining the relative movement with respect to the 12 subjects o.

  This digital X-ray tomography apparatus M1 is different from the above-mentioned digital X-ray tomography apparatus M in the configuration of the moving means 13A. Since other configurations are common, the description thereof will be omitted, and the moving means 13A will be described below.

  The moving means 13A includes a swivel part 13c to which the X-ray generator 11 and the X-ray detector 12 are synchronously attached so as to be movable in parallel and a swivel base 13d for rotating the swivel part 13c. The parallel movement of the X-ray generator 11 and the X-ray detector 12 in the turning unit 13c and the turning of the turning unit 13c by the turntable 13d are driven by three stepping motors controlled independently by the control means 14. Made by the moving mechanism. A main body frame for supporting the swivel base 13d is not shown.

  As shown in FIG. 8B, the X-ray generator 11 is movably provided on the rod RD1 of the link mechanism LK and the X-ray detector 12 is movably provided on the rod RD2 facing the rod RD1 inside the swivel unit 13c. .

  The other rods RD3 and RD4 are angularly displaced following the turning of the turning portion 13c. Therefore, the rod RD1 and the rod RD2 maintain a certain parallel relationship even if the turning portion 13c turns.

  Thereby, the X-ray generator 11 and the X-ray detector 12 are synchronously moved in the same direction on the rod RD1 and the rod RD2.

  The basic operation of the digital X-ray tomography apparatus M1 is substantially the same as that of the digital X-ray tomography apparatus M described above. That is, among the steps shown in FIG. 6, the cross-section setting step 101, the transmission image generation step 104, the imaging end determination step 105, and the tomographic image synthesis step 106 are the same as those in the digital X-ray tomography apparatus M described above. Since the description is the same, it will be omitted, and in the following, the cross-section setting step 101, the incident angle setting step 102, and the X-ray imaging step 103 will be described.

  In this example, in the incident angle setting step 102, the moving unit 13 is driven by the control of the incident angle control unit 14c, and the swivel unit 13c is swung by the swivel base 13d, so The incident angle θ (#i) is specified. At this time, in the turning unit 13c, the X-ray generator 11 and the X-ray detector 12 are returned to the reference position. At this time, the relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is a turning movement indicated by a solid arrow 102 in FIG.

  In the X-ray imaging step 103, the X-ray generator 11 and the X-ray detector 12 are operated, and the moving means 13 is driven by the control of the imaging control means 14d. 11 and the line detector 12 are moved in parallel in synchronization. At this time, the relative movement of the X-ray generator 11 and the elongated X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is a parallel movement indicated by a dashed arrow 103 in FIG. is there.

  Next, another example of the digital X-ray tomographic imaging apparatus according to the second invention will be further described with reference to FIGS.

  FIG. 10 is a block diagram for conceptually explaining the digital X-ray tomography apparatus M2 having a further different basic configuration, and FIG. 11 is an X-ray generator 11 and an X-ray detector in a tomography process procedure. It is the top view seen from the upper side explaining the relative movement with respect to the 12 subjects o.

  This digital X-ray tomography apparatus M2 differs from the above-described digital X-ray tomography apparatuses M and M1 in the configuration of the moving means 13B. Since other configurations are common, description thereof will be omitted, and the moving means 13B will be described below.

  The moving means 13B is composed of a fixed base 13e to which the X-ray generator 11 and the X-ray detector 12 are attached so that they can be moved synchronously and asynchronously in the same direction and in the reverse direction. The parallel movement of the X-ray generator 11 and the X-ray detector 12 is performed by a moving mechanism using two stepping motors controlled independently by the control means 14 as drive sources. Note that a main body frame for supporting the fixed base 13e is not shown.

  The basic operation of the digital X-ray tomography apparatus M2 is substantially the same as that of the digital X-ray tomography apparatus M described above. That is, among the steps shown in FIG. 6, the cross-section setting step 101, the transmission image generation step 104, the imaging end determination step 105, and the tomographic image generation step 106 are the same as the case of the digital X-ray tomography apparatus M described above. Since the description is the same, it will be omitted, and in the following, the cross-section setting step 101, the incident angle setting step 102, and the X-ray imaging step 103 will be described.

  That is, in this example, in the incident angle setting step 102, the moving means 13 is driven by the control of the incident angle control means 14c, and the X-ray generator 11 and the X-ray detector 12 are moved to a predetermined straight line by the fixed base 13e. , The plurality of incident angles of the X-ray slit beam B are specified. The relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o at this time is a parallel movement in the reverse direction indicated by the solid arrow 102 in FIG. They can be moved synchronously or asynchronously.

  In the X-ray imaging step 103, in a state where the X-ray generator 11 and the X-ray detector 12 are operated, the moving means 13 is driven by the control of the imaging control means 14d, and the X-ray generator is driven by the fixed base 13e. 11 and the X-ray detector 12 are synchronized and translated in the same direction. The relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o at this time is a parallel movement in the same direction indicated by a broken-line arrow 102 in FIG. .

Next, a more specific example of the digital X-ray tomographic imaging apparatus according to the second invention will be described with reference to FIGS. 12, 13, 6, and 14. FIG.
FIG. 12 is a perspective view of the digital X-ray tomography apparatus M3, FIG. 13 is a side view of the digital X-ray tomography apparatus M3, and FIG. 14 is a schematic perspective view from above explaining the processes of the incident angle setting step 102 and the X-ray imaging step 103. It is a top view.

  The digital X-ray tomography apparatus M3 includes a moving unit 13A including an X-ray generator 11 that irradiates an X-ray slit beam and an X-ray detector 120, and a main body frame that firmly supports the moving unit 13A. 16 is composed.

  The moving means 13A has a swivel portion 13a to which the X-ray generator 11 and the X-ray detector 12 are fixed, and a swivel axis in the Z direction on a plane XY perpendicular to the swivel axis Z of the swivel portion 13a. It comprises an axis moving table 13b that moves horizontally. This shaft moving table 13b has a shaft slide portion that can be freely moved in the XY plane by an X-axis stepping motor and a Y-axis stepping motor as an axis moving mechanism, and a swivel shaft connected thereto. Can be moved horizontally, and the turning portion 13a can be freely turned by the stepping motor for the turning shaft. The moving means can also move up and down along the main body frame 16 by a Z-axis stepping motor.

  The X-ray generator 11 incorporates an X-ray tube having a fixed anode, a metal collimator having a predetermined slit formed therein, etc., and receives a tube voltage and a tube current to expand in the vertical direction. The line slit beam B is irradiated toward the X-ray detector 120 arranged opposite to the line slit beam B.

  The X-ray detector 12 has an elongated X-ray image sensor 12a composed of a fluorescent filter that converts X-rays into visible light, a CCD sensor having a long rectangular light receiving portion, and the like, and an operation clock for the image sensor 12a. A cassette 12b containing a supplied TDI clock generator and the like is detachably attached to the cassette holder 12c. This cassette 12b can be replaced with another cassette containing an X film.

  A display operation unit 14a having operation switches and indicator lights is provided on a side surface of the housing frame 17 provided in the main body frame 16, and a control unit including a CPU or the like is further stored therein. The control unit controls the X-ray generator 11, the X-ray detector 12, and the moving unit 13A to generate a transmission image from the imaging data by the control unit 14 that captures a transmission image of the subject o, and further transmits the transmission image. The image processing means 15 for synthesizing the tomographic image of the subject o, and communicating with a remote control device, a workstation, etc. (not shown) to receive an imaging command, etc. It is also possible to send it out.

  The control unit 14 has the same configuration as that of the digital X-ray tomography apparatus M described above, and includes a cross-section setting unit 14b, an incident angle control unit 14c, and an imaging control unit 14d. The image processing unit 15 includes a transmission image generation unit 15a and a tomographic image synthesis unit 15b.

  Further, a subject fixing means 18 is attached to the housing frame 17. The subject fixing means 18 includes a handle 18a held by a subject who is the subject o, a chin holder 18b for supporting the subject's chin, and a temporal holder 18c that comes into contact with the subject's temporal region.

Here, the basic operation of the digital X-ray tomography apparatus M3 will be described with reference to FIGS.
Among the steps shown in FIG. 6, the transmission image generation step 104, the imaging end determination step 105, and the tomographic image synthesis step 106 are the same as those in the digital X-ray tomography apparatus M described above, and are therefore omitted. In the following, the cross-section setting step 101, the incident angle setting step 102, and the X-ray imaging step 103 will be described.

  In the section setting step 101, a specific section v is set at the center of the object of interest s (for example, a specific tooth) inside the object o (for example, the head of a person). Is positioned at a predetermined position between the X-ray generator 11 and the X-ray detector 12, and the operator determines the positional relationship between the object o, the X-ray generator 11, and the X-ray detector 12. The position and direction of the specific cross section v are registered in the control means 14 by operating the display operation unit 14a and moving the moving means 13A to an appropriate position while visually observing.

  In the incident angle setting step 102, the moving means 13A is driven by the control of the incident angle control means 14c, the turning part 13a to which the X-ray generator 11 and the X-ray detector 120 are fixed is turned, and the axis is further moved. By using the table 13b, the swivel axis is moved horizontally in an auxiliary manner to identify θ (#i), which is one of a plurality of incident angles θ (# 1 to #n) of the X-ray slit beam with respect to the specific section v. To do. At this time, the relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is mainly the turning movement indicated by the solid arrow 102 in FIG. Is.

  In the X-ray imaging step 103, the X-ray generator 11 and the X-ray detector 12 are operated, and the moving means 13A is driven by the control of the imaging control means 14d. The device 11 and the X-ray detector 12 are synchronized and translated in a direction parallel to the specific cross section v. Thus, the X-ray slit beam B irradiated from the X-ray generator 11 scans a predetermined spread including the object of interest s while maintaining the incident angle θ (#i), and the X-ray detector 12 To obtain imaging data corresponding to the incident angle θ (#i). At this time, relative movement of the X-ray generator 11 and the X-ray detector 12 (X-ray image sensor 12a) with respect to the subject o is indicated by arrows A1 → B1, A2 → B2, and A3 → B3 in FIG. The translation shown.

FIG. 3 is a schematic diagram conceptually illustrating a digital X-ray tomographic imaging method according to the first invention. Drawing explaining the irradiation angle of an X-ray slit beam. A simple sketch of the subject. The drawing explaining a plurality of transmission images and a tomographic image synthesized therefrom. The block diagram explaining the basic composition of the digital X-ray tomography apparatus by 2nd invention. The flowchart explaining the process sequence of tomography. FIG. 6 is a plan view for explaining movement of an X-ray generator and an X-ray image sensor in the configuration of the digital X-ray tomography apparatus (FIG. 5). The block diagram explaining the basic composition of the digital X-ray tomography apparatus which is another example. The top view explaining the movement of an X-ray generator and an X-ray image sensor in the configuration of the digital X-ray tomography apparatus (FIG. 8). Furthermore, the block diagram explaining the basic composition of the digital X-ray tomography apparatus which is another example. FIG. 11 is a plan view for explaining movement of an X-ray generator and an X-ray image sensor in the configuration of the digital X-ray tomography apparatus (FIG. 10). Furthermore, the perspective view of the digital X-ray tomography apparatus which is another example. The side view of a digital X-ray tomography apparatus (FIG. 12). FIG. 4 is a schematic perspective plan view for explaining processing of an incident angle setting step and an X-ray imaging step. The drawing explaining the principle of a conventional X-ray tomographic imaging method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray scanning orbit surface 11 X-ray generator 12 X-ray detector 12a X-ray image sensor 13, 13A, 13B, Moving means 13a, 13c Turning part 13b Axis moving table 13d Turning table 13e Fixed table 14 Control means 14b Cross-section setting Means 14c Incident angle control means 14d Imaging control means 15 Image processing means 15a Transmission image generation means 15b Tomographic image synthesizing means B X-ray slit beam M, M1, M2, M3, X-ray tomography apparatus o Subject s Region of interest v Specific cross section

Claims (8)

For each of a plurality of X-ray scanning orbit planes having the same spread specified in advance, an irradiation angle in which an X-ray slit beam having a spread in the vertical direction is differentiated corresponding to each of the X-ray scanning orbit planes is maintained. In this state, by irradiating while translating in the horizontal direction, a transmission image of the subject by the X-ray image sensor is taken,
The transmission images of the subject with respect to each of the plurality of X-ray scanning trajectory planes thus obtained are shifted with a predetermined positional relationship and superimposed on each other, thereby generating a desired X-ray tomographic image of the subject. , Digital X-ray tomography method. An X-ray generator for irradiating an X-ray slit beam, an elongated X-ray image sensor corresponding to the X-ray generator,
Moving means for relatively moving the X-ray generator and the elongated X-ray image sensor facing each other with a subject interposed therebetween;
Control means for controlling the X-ray generator, the elongated X-ray image sensor, and the moving means to take a transmission image of the subject;
In a digital X-ray tomography apparatus comprising an image processing means,
The control means includes
Cross-section setting means for setting a specific cross-section at the center of the region of interest of the subject;
By moving the X-ray generator and the elongated X-ray image sensor in a trajectory including at least a relative rotational movement component with respect to the subject, a plurality of X-ray slit beam with respect to the set specific cross section is obtained. An incident angle control means for specifying the incident angle;
Translating the X-ray slit beam irradiated from the X-ray generator in a direction parallel to the specific cross section while maintaining a specified incident angle and having a spread including a region of interest; and And an imaging control means for acquiring imaging data corresponding to each incident angle by moving the elongated X-ray image sensor so as to follow the X-ray slit beam,
The image processing means includes
Transmission image generation means for generating individual transmission images corresponding to the respective incident angles from the photographing data corresponding to the respective incident angles,
And a tomographic image synthesizing unit that synthesizes the tomographic images of the subject by aligning the individual transmission images corresponding to the respective incident angles at the positions of the specific cross sections and superimposing them on each other. Digital X-ray tomography system. In claim 2,
The incident angle control means specifies a plurality of incident angles of the X-ray slit beam by relatively moving the X-ray generator and the elongated X-ray image sensor along a predetermined curve. A digital X-ray tomography apparatus characterized by the above. In claim 2,
The incident angle control means specifies the plurality of incident angles of the X-ray slit beam by relatively moving the X-ray generator and the elongated X-ray image sensor along a predetermined straight line. A featured digital X-ray tomography system. In Claim 3, The said moving means is
A swivel unit to which the X-ray generator and the elongated X-ray image sensor are fixed, and an axis moving table that horizontally moves the swivel axis on a plane orthogonal to the swivel axis of the swivel unit;
The imaging control means drives the axis moving table to synchronize and translate the X-ray generator and the elongated X-ray image sensor in the same direction. Shooting device. The moving means according to claim 4,
The X-ray generator and the elongated X-ray image sensor are synchronously mounted so that they can move in parallel, and a swivel that rotates the swivel.
The imaging control means drives the swivel unit to synchronize the X-ray generator and the elongated X-ray image sensor in parallel and move in the same direction. apparatus. In claim 4,
The moving means is
The X-ray generator and the elongated X-ray image sensor are composed of a fixed base attached to be movable in parallel,
The incident angle control means specifies a plurality of incident angles of the X-ray slit beam by translating the X-ray generator and the elongated X-ray image sensor in a reverse direction along a predetermined straight line. And
The digital X-ray tomographic imaging apparatus characterized in that the imaging control means synchronizes the X-ray generator and the elongated X-ray image sensor in parallel in the same direction. In any one of Claims 2-7,
The elongate X-ray image sensor outputs a charge image of an X-ray slit beam as a signal obtained by time delay integration.

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