JP5798016B2 - X-ray equipment - Google Patents

Description

  The present invention relates to an X-ray imaging apparatus, and more particularly to restriction of an irradiation range of an X-ray beam of an X-ray CT imaging apparatus.

  Conventional X-ray imaging apparatuses include a panoramic X-ray tomography apparatus that can generate a panoramic X-ray tomographic image and an X-ray CT imaging apparatus that can generate a CT image (3D image) by irradiation with an X-ray cone beam. There is also an X-ray imaging apparatus that realizes the functions of the two apparatuses with a single apparatus.

  As a conventional panoramic X-ray tomography apparatus, for example, there is an X-ray imaging apparatus disclosed in Patent Document 1. This X-ray imaging apparatus is used for panoramic X-ray imaging (hereinafter simply abbreviated as “for panorama”) when forming an X-ray passage region (subject irradiation X-ray passage region) that actually irradiates a subject. At least one of the upper end and the lower end of the slit region (X-ray passage region) in the line shielding member is shielded, and only the necessary portion is set as the subject irradiation X-ray passage region, and the subject irradiation X-ray passage region is passed. The obtained X-ray is configured to be irradiated as an X-ray slit beam. This X-ray imaging apparatus has a function as an X-ray CT imaging apparatus in addition to a function as a panoramic X-ray tomography apparatus, and is used for generating a CT image at the time of irradiation with the X-ray slit beam. The subject irradiation X-ray passage region is determined by superimposing the X-ray passage region and the slit region in the X-ray shielding member (hereinafter simply referred to as “for CT”).

  Moreover, as a conventional X-ray CT imaging apparatus, for example, there is an X-ray CT imaging apparatus disclosed in Patent Document 2. This X-ray CT imaging apparatus enables both CT imaging with a wide area X-ray cone beam and CT imaging with a narrow area X-ray cone beam, and a wide area X-ray cone beam and a narrow area X-ray cone. The lower end position with the beam is matched.

Japanese Patent Laying-Open No. 2011-041598 (FIG. 10 (c)) JP 2006-130037 A

  In the conventional X-ray imaging apparatus disclosed in Patent Document 1, the subject irradiation X-rays obtained by superimposing the X-ray passage area of the CT X-ray shielding member and the slit area of the panoramic X-ray shielding member are overlapped. X-rays are passed through the passage area. Therefore, there is a problem in that the degree of freedom of the subject irradiation X-ray passage region is limited because it is restricted by the size of the X-ray passage region of the CT X-ray shielding member.

  Further, the X-ray CT imaging apparatus disclosed in Patent Document 2 merely discloses a variation in which only the portion near the lower end of the X-ray cone beam is used by shielding the upper end of the X-ray cone beam. There is a problem that the valuation of the cone beam shielding is poor, that is, the degree of freedom of the subject irradiation X-ray passing region is low.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an X-ray imaging apparatus in which the degree of freedom of the subject irradiation X-ray passage region, which is the X-ray passage region that is actually irradiated to the subject, is increased. To do.

According to a first aspect of the present invention, an X-ray imaging apparatus includes an X-ray generator that emits X-rays and a plurality of detection elements that output signals according to the intensity of the incident X-rays. A support unit that supports an X-ray generation unit including the X-ray generator and an X-ray detection unit including the X-ray detector; and the X-ray generator and the X-ray detector are An image for generating an X-ray image by performing image processing on a signal output from the X-ray detector and a turning mechanism for turning the support portion around the subject so as to face each other with a subject including a part interposed therebetween An X-ray irradiation restricting unit for restricting an irradiation range of X-rays emitted from the X-ray generator, the X-ray generating unit including first and second X-ray shielding units It has the X-ray emission direction side of the X-ray generator, passing of each of the first and second X-ray shielding section X-ray The first and second X-ray passage regions that allow the first X-ray and the first and second shielding regions that block the passage of the X-rays are provided, and the X-rays emitted from the X-ray generator are the first X-rays. A positional relationship capable of passing through the X- ray passing region or the second X-ray passing region is set, and the first X-ray passing region and the second X-ray passing region are overlapped on the X-ray irradiation path. Without matching, one of the first and second X-ray shielding portions is displaced relative to the other in the regulation direction intersecting with the X-ray irradiation direction, and the second X-ray shielding region Superposition of a part of the first X-ray passage region and a part of the first X-ray shielding region and a part of the second X-ray passage region are performed. Thus, the subject irradiation X-ray passage region through which X-rays pass is restricted in the X-ray irradiation restriction unit. Wherein the X-ray irradiation range regulatory process 1 can be realized.

  A second aspect of the present invention is the X-ray imaging apparatus according to the first aspect, wherein the axial direction of the pivot axis of the support portion is a vertical direction, and the direction along the axial direction of the pivot axis is a height direction. The center position of the X-ray detection surface of the X-ray detector is arranged higher than the X-ray focal point that is the X-ray generation point in the X-ray generator, and the regulation direction includes the height direction. In the first X-ray irradiation range restriction process, a part of the second X-ray shielding area of the second X-ray shielding part is overlapped with a part above the first X-ray passage area. This includes a process of partially shielding by combining them.

  A third aspect of the present invention is the X-ray imaging apparatus according to the first aspect, wherein the X-ray generator allows the X-rays emitted from the X-ray generator to pass through the first X-ray passage region. The first X-ray passage region is left as it is without superimposing the first X-ray passage region and the second X-ray shielding region on the X-ray irradiation path. A second X-ray irradiation range restriction process for restricting the subject irradiation X-ray passage area and a positional relationship in which the X-rays emitted from the X-ray generator can pass through the first and second X-ray passage areas. The first and second X-ray passage regions are set and overlapped on at least a part of the first X-ray passage region and the second X-ray passage region on the X-ray irradiation path. A third X-ray illumination that restricts the overlapping region of the subject as the subject irradiation X-ray passage region A range limiting process is further executable.

  A fourth aspect of the present invention is the X-ray imaging apparatus according to any one of the first to third aspects, wherein the first and second X-ray shielding portions in the first and second X-ray shielding portions. The X-ray passing area includes an area where an X-ray cone beam can be formed by regulating X-rays emitted from the X-ray generator when passing through the subject irradiation X-ray passing area.

  According to a fifth aspect of the present invention, in the X-ray imaging apparatus according to the fourth aspect, the first X-ray passage region has a wider formation width than the second X-ray passage region in the regulation direction. Features.

  The invention of claim 6 is the X-ray imaging apparatus according to claim 3, wherein the first X-ray passage region has a wider formation width than the second X-ray passage region in the regulation direction, X-rays that have passed through the subject irradiation X-ray passage region when the second X-ray irradiation range restriction process is performed by the X-ray generation unit are substantially the same as the X-ray imaging region of the dental arch of the subject. In the third X-ray irradiation range restriction process, the second X-ray passage region is entirely overlapped with a part of the first X-ray passage region, and the second X-ray irradiation region restriction process is performed. Including an entire narrow formation width X-ray passage area utilization process that uses the X-ray passage area as it is as the subject irradiation X-ray passage area, and the X-ray generation unit performs the narrow formation width X-ray passage area utilization process. X-rays that have passed through the subject irradiation X-ray passage area are the dentition of the subject. Of tooth, including X-ray cone beam only area is the X-ray imaging area including the part of the tooth.

  A seventh aspect of the present invention is the X-ray imaging apparatus according to any one of the first to third aspects, wherein the first and second X-ray shielding portions in the first and second X-ray shielding portions. Each of the X-ray passing regions includes a slit-like region capable of forming an X-ray slit beam by regulating the X-rays emitted from the X-ray generator when passing through the subject irradiation X-ray passing region.

  The invention according to claim 8 is the X-ray imaging apparatus according to claim 7, wherein the X-ray image includes a panoramic tomographic image, and the image processing is performed along a tomographic plane corresponding to the dental arch of the subject. And a process of generating a panoramic tomographic image by performing a process of superimposing overlapping portions of images.

  A ninth aspect of the present invention is the X-ray imaging apparatus according to the second aspect, wherein the subject holding unit that holds the subject at a predetermined holding position, and the support unit together with the subject holding unit along the height direction. And a subject holding portion lifting mechanism capable of lifting the subject holding portion along the height direction, wherein the subject holding portion lifting mechanism is supported by the lifting portion in the height direction. The position of the subject holding portion in the height direction can be displaced so as to cancel the amount of elevation of the subject.

  According to the invention of claim 1 in this invention, one of the first and second X-ray shielding portions is displaced relative to the other in the regulation direction intersecting with the X-ray irradiation direction, and the first 2 part of the X-ray shielding region and part of the first X-ray passage region, or part of the first X-ray shielding region and part of the second X-ray passage region. By performing the alignment, the first X-ray irradiation range restriction process for restricting the subject irradiation X-ray passage region through which the X-rays pass through the X-ray irradiation restriction unit can be realized.

  In the first X-ray irradiation range restriction process, the first or second overlapping content of a part of the second and first X-ray shielding areas and a part of the first and second X-ray passage areas By setting the various subject irradiation X-ray passage areas by changing the above, it is possible to realize various X-ray irradiation ranges.

  In addition, since the X-ray irradiation range is diverse, it is possible to set the X-ray irradiation range to be more limited to the region of interest, and there is an effect that the X-ray exposure amount of the subject is kept to the minimum necessary.

  According to the second aspect of the present invention, the first X-ray irradiation range restriction process causes a part of the upper part of the first (second) X-ray passage region to be the second (first) X-ray. It is shielded by the second X-ray shielding region of the line shielding part.

  For this reason, the center position of the X-ray detection surface of the X-ray detector may be higher than the X-ray focal point, which is the X-ray generation point in the X-ray generator, and an artifact may occur while performing X-ray imaging. X-rays passing through a region above the relatively high first (second) X-ray passage region can be effectively shielded.

  According to this invention of Claim 3, in addition to the said 1st X-ray irradiation range control process, by enabling the said 2nd and 3rd X-ray irradiation range control process, more various X-rays The effect which can implement | achieve an irradiation range is produced.

  According to this invention of Claim 4, various X-ray imaging using an X-ray cone beam is realizable.

  In addition, the CT imaging can be completed with the rotation of the support portion from a half rotation to approximately one rotation, so that the imaging can be performed in a short time and the burden on the subject can be reduced.

  According to this invention of Claim 5, a more various X-ray irradiation range is realizable by changing the formation width in the control direction between the 1st and 2nd X-ray passage area | regions.

  According to this invention of Claim 6, X-ray imaging of the 1st irradiation field by the 2nd X-ray irradiation range control process and the narrow formation width X-ray passage area whole of the 3rd X-ray irradiation range control process X-ray imaging of the second irradiation field smaller than the first irradiation field by the use processing can be selectively performed.

  According to this invention of Claim 7, various X-ray imaging using a X-ray slit beam is realizable including panoramic imaging.

  According to this invention of Claim 8, various panoramic tomographic images can be obtained using an X-ray slit beam.

  According to the invention of claim 9, the subject holding unit lifting mechanism can displace the position of the subject holding unit in the height direction so as to cancel the lifting amount of the support unit by the lifting unit in the height direction. Even if the X-ray irradiation position on the subject is changed in the height direction, the absolute value of the subject holding portion in the height direction can always be kept constant.

  As a result, X-ray irradiation in the height direction with respect to the subject can be performed without imposing a burden on the subject by always maintaining the placement of the subject's head or the like to be held by the subject holding unit at a constant absolute height. There is an effect that X-ray imaging can be performed by changing the position.

It is a schematic perspective view which shows the X-ray imaging apparatus which is embodiment of this invention. It is a front view which shows the cephalostat applicable to an X-ray imaging apparatus. It is a block diagram which shows the drive / control structure of an X-ray imaging apparatus. It is a perspective view which shows the internal structure of a X-ray generation part. It is explanatory drawing which shows the positional relationship of X-ray shielding in the case of the large irradiation field CT imaging | photography by an X-ray control part. It is explanatory drawing which shows the positional relationship of the X-ray shielding in the case of the small irradiation field CT imaging | photography (the 1) by an X-ray control part. It is explanatory drawing which shows the positional relationship of the X-ray shielding in the case of the small irradiation field CT imaging | photography (the 2) by an X-ray control part. It is explanatory drawing which shows the positional relationship of the X-ray shielding in the case of the panoramic imaging by an X-ray control part. It is explanatory drawing which shows typically the height adjustment content of the to-be-fixed part in the small irradiation field CT imaging | photography (the 2) shown in FIG. It is explanatory drawing which shows the specific example of the height displacement of a to-be-fixed part.

<Embodiment>
(1.1. Configuration and function of X-ray imaging apparatus)
FIG. 1 is a schematic perspective view showing an X-ray imaging apparatus 100 according to an embodiment of the present invention. The X-ray imaging apparatus 100 executes panoramic X-ray tomography, normal X-ray CT imaging (Computed Tomography), etc., and processes the projection data collected in the main body 1 and the main body 1 that collects projection data. Thus, the information processing apparatus 8 is broadly divided into information processing apparatuses 8 that generate various images (CT images, cephalo images, panoramic tomographic images, and the like).

  The main body 1 includes an X-ray generator 10 that emits X-rays composed of a bundle of X-rays toward a subject OB such as a subject, and an X-ray beam XB that includes X-rays emitted from the X-ray generator 10. The X-ray detection unit 20 for detecting the X-ray, the support unit 300 (the turning arm 30) for supporting the X-ray generation unit 10 and the X-ray detection unit 20, respectively, and the support unit 300 are suspended in a vertical direction with respect to the support column 50. A support frame 40 capable of moving up and down, a support column 50 extending in the vertical direction, and a main body control unit 60 are provided.

  In FIG. 1 and other drawings, a left-handed XYZ orthogonal coordinate system and an xyz orthogonal coordinate system are attached as necessary. Here, the direction parallel to the axial direction of the turning shaft 31 (here, the vertical direction) is defined as the “Z-axis direction”, the direction intersecting the Z-axis is defined as the “X-axis direction”, and the X-axis direction and the Z-axis direction. The direction intersecting the direction is defined as “Y-axis direction”. Although the X-axis and Y-axis directions can be arbitrarily determined, here, the left and right directions of the subject when the subject who is the subject OB is positioned in the X-ray imaging apparatus 100 and directly faces the column 50 are defined as X The axial direction is defined, and the front-rear direction of the subject is defined as the Y-axis direction. In the present embodiment, the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. In the following description, the Z-axis direction may be referred to as a vertical direction, and the direction on a plane defined in two dimensions, the X-axis direction and the Y-axis direction, may be referred to as a horizontal direction. The Z-axis direction may be the height direction.

  The xyz rectangular coordinate system is a three-dimensional coordinate system defined on the turning arm 30 that turns. Here, the direction in which the X-ray generation unit 10 and the X-ray detection unit 20 face each other is referred to as “y-axis direction”, and the horizontal direction orthogonal to the y-axis direction is referred to as “x-axis direction”. An orthogonal vertical direction is defined as a “z-axis direction”. In the present embodiment, the Z-axis direction is the same direction that has the same orientation as the z-axis direction. Further, the turning arm 30 of the present embodiment rotates around a turning shaft 31 extending in the vertical direction. Therefore, the xyz orthogonal coordinate system rotates around the Z axis (= z axis) with respect to the XYZ orthogonal coordinate system.

  In the illustrated example of the present embodiment, the turning shaft 31 extends in the vertical direction, but may be in other directions including the horizontal direction. For example, when the X-ray imaging apparatus 100 is configured as a bed type on which the subject is placed on his / her back, the swivel axis 31 is configured to extend in the horizontal direction.

  In the present embodiment, as shown in FIG. 1, the right hand direction when the subject faces the column 50 is the (+ X) direction, the back direction is the (+ Y) direction, and the vertical direction is upward ( + Z) direction. Further, when the X-ray generation unit 10 and the X-ray detection unit 20 are viewed from above, the direction from the X-ray generation unit 10 to the X-ray detection unit 20 is the (+ y) direction and the (+ y) side. right hand? The direction is the (+ x) direction and the upward direction is the (+ z) direction.

  In addition, X, Y, Z, x, y, z may be used to define a plane. For example, a two-dimensional plane extending in the x direction and the z direction is referred to as an xz plane.

  The X-ray generation unit 10 and the X-ray detection unit 20 are respectively suspended and fixed at both ends of the turning arm 30 and supported so as to face each other. The turning arm 30 is suspended and fixed to the support frame 40 via a turning shaft 31 extending in the vertical direction.

  The X-ray generator 10 includes an X-ray generator 11 having an X-ray tube as an X-ray source inside a housing not shown in FIG. The housing is attached to the support portion 300 so as to be rotatable around the Z axis. This rotation function is used, for example, at the time of cephalometric photography (see FIG. 2 described later).

  The X-ray detection unit 20 includes an X-ray detector 21 that detects X-rays transmitted through the subject OB. The X-ray detector 21 is configured on an X-ray detection substrate 22 and constitutes an image sensor including a plurality of X-ray detection elements arranged so as to spread on a two-dimensional plane (here, xz plane). Yes. The X-ray detection element outputs a signal corresponding to the intensity of the incident X-ray to the outside. The intensity of X-rays incident on the X-ray detection unit 20 is acquired by the image sensor as frame image data (image information) having a pixel value corresponding to the X-ray intensity at a required frame rate.

  As the X-ray detector 21, a MOS sensor or a CMOS sensor can be suitably used, but any electrical imaging sensor may be used. Specifically, various devices such as a flat panel detector (FPD) such as a CCD sensor and other solid-state imaging devices can be used. A single X-ray detector 21 may be used for any X-ray imaging, and the readout area may be changed in accordance with the shape of the X-ray beam incident on the X-ray detector 21. In any case, an electrical imaging sensor capable of obtaining at least a frame image is used for CT imaging.

  In the present embodiment, the support unit 300 is composed of a revolving arm 30 that revolves around the revolving shaft 31, and the X-ray generation unit 10 and the X-ray detection unit 20 are attached to both ends of the substantially rectangular parallelepiped revolving arm 30. It has been. However, the structure of the support part 300 which supports the X-ray generation part 10 and the X-ray detection part 20 is not restricted to this. For example, the X-ray generation unit 10 and the X-ray detection unit 20 may be supported in an opposed state by an annular member that rotates about the center of the annular portion.

  The support frame 40 is engaged with a column 50 that is erected so as to extend along the vertical direction. The support frame 40 has an upper frame 41 and a lower frame 42, which are constituent parts thereof, projecting on the side opposite to the side engaged with the support column 50, and has a substantially U-shaped structure.

  An upper end portion of the swing arm 30 is attached to the upper frame 41. As described above, the swing arm 30 is suspended from the upper frame 41 of the support frame 40, and the swing arm 30 moves up and down as the support frame 40 moves along the column 50.

  The lower frame 42 is provided with a subject fixing portion 421 including a rod for fixing the subject OB (here, the human head) from the left and right, a chin rest for fixing the chin, and the like. The swivel arm 30 is raised and lowered according to the height of the support frame 40 according to the height of the subject OB and adjusted to an appropriate position, and the subject OB is fixed to the subject fixing portion 421 in this state. In the example shown in FIG. 1, the subject fixing unit 421 fixes the subject OB so that the body axis of the subject OB is the same as or substantially the same as the axial direction of the turning shaft 31.

  In addition to the above, the subject fixing unit 421 includes various elements such as a head holder for fixing the head, an ear rod for fixing the ear, and a chair on which the subject is seated.

  As shown in FIG. 1, a main body control unit 60 that controls the operation of each component of the main body unit 1 is provided inside the X-ray detection unit 20. Moreover, each structure of the main-body part 1 is accommodated in the X-ray chamber 70 preferably. On the outside of the wall of the X-ray prevention chamber 70, various displays are provided with respect to the main body control unit 60 and a display unit 61 configured with a liquid crystal monitor or the like for displaying various information based on control from the main body control unit 60. An operation panel 62 composed of buttons and the like for realizing command input is attached. The operation panel 62 is also used for designating the position of an imaging region such as a living organ. There are various modes for X-ray imaging (panoramic X-ray tomography, CT imaging, cephalometric imaging, etc.), but the mode can be selected by operating the operation panel 62.

  The information processing apparatus 8 includes an information processing main body 80 configured by, for example, a computer or a workstation, and can transmit and receive various data to and from the main body 1 using a communication cable. However, data may be exchanged between the main body 1 and the information processing apparatus 8 wirelessly.

  For example, a display unit 81 including a display device such as a liquid crystal monitor and an operation unit 82 including a keyboard and a mouse are connected to the information processing body unit 80. The operator can give various commands to the information processing apparatus 8 via the operation unit 82. The display unit 81 can also be configured with a touch panel. In this case, the display unit 81 includes a part or all of the functions of the operation unit 82.

  FIG. 2 is a front view showing a cephalostat 43 applicable to the X-ray imaging apparatus 100. As shown in FIG. 2, the cephalostat 43 is attached to, for example, an arm 501 that extends in the horizontal direction from the middle of the column 50. The cephalostat 43 is provided with a fixture 431 for fixing the head in a fixed position and an x-ray detector 432 for cephalo imaging. As the cephalostat 43, various types including a cephalostat disclosed in Japanese Patent Application Laid-Open No. 2003-245277 can be adopted.

  FIG. 3 is a block diagram showing a drive / control configuration of the X-ray imaging apparatus 100 of the present embodiment. In FIG. 3, a portion having a control relationship that is strongly related to the feature of the present embodiment is indicated by a broken line.

  As shown in FIG. 3, the main body 1 includes a drive unit 65 including a turning motor 60R, an X-axis motor 60X, and a Y-axis motor 60Y. In the present embodiment, the drive unit 65 is built in the upper frame 41. The X-axis motor 60X and the Y-axis motor 60Y move the turning shaft 31 horizontally in the X-axis direction and the Y-axis direction, respectively. Further, the turning motor 60R rotates the turning arm around the Z axis of the turning shaft 31.

  The main body of the swivel arm 30 may be fixed to the swivelable turning shaft 31 so as not to turn, and the swiveling shaft 31 may be driven to turn by the turning motor 60R. The swivel arm 30 may be pivotally driven with respect to the swivel shaft 31 so as to be pivotable. In the latter case, the turning motor 60R may be provided inside the turning arm 30. Moreover, you may make it provide the main body of the turning arm 30 on the turning axis 31 which can turn further so that rotation is possible.

  That is, the driving unit 65 relatively moves the turning arm 30 horizontally or turns relative to the subject OB positioned at the required position. In the present embodiment, the drive unit 65 constitutes a turning mechanism for turning the support unit 300 (the turning arm 30) around the subject OB around the turning shaft 31, and the X-ray generator 11 and the X-ray detector are configured. 21, the support unit 300 is turned around the subject OB so as to face each other across the subject OB including the head.

  The main body control unit 60 includes a CPU 601 that executes various control programs including a program PG1 that controls the drive unit 65, a fixed disk such as a hard disk, a storage unit 602 that stores various data and programs PG1, a ROM 603, The RAM 604 is configured as a computer connected to the bus line.

  The CPU 601 executes the program PG1 stored in the storage unit 602 on the RAM 604, so that the X-ray generation unit control unit 601a and the X-ray detection unit 20 control the X-ray generation unit 10 according to various imaging modes. Functions as an X-ray detection unit control unit 601b. The X-ray generation unit control unit 601a can also control the X-ray irradiation X-ray dose, and also has a function of an X-ray irradiation control unit. Further, the X-ray generation unit control unit 601a drives the X-ray shielding unit drive unit 12D to control first to third X-ray irradiation range regulation processes, which will be described in detail later, with respect to the X-ray regulation unit 12.

  The CPU 601 also functions as a drive control unit 601c that drives and controls the drive unit 65, and controls the drive so that, for example, the X-ray generation unit 10 and the X-ray detection unit 20 move in a trajectory corresponding to various types of imaging.

  Further, the drive control unit 601c sends a control signal to the subject fixing unit driving unit 421D to adjust the height of the subject fixing unit 421, which will be described later, via the subject fixing unit driving unit 421D under the control of the drive control unit 601c. Is going.

  Note that the CPU 601 constituting the main body control unit 60 and the CPU 801 constituting the information processing main body unit 80 collectively constitute a control system.

  An operation panel 62 connected to the main body control unit 60 includes a plurality of operation buttons and the like. In addition to the operation buttons, a keyboard, a mouse, a touch pen, or the like can be used as an input device instead of the operation panel 62 or used together with the operation panel 62. Further, a voice command may be received and recognized by a microphone or the like. That is, the operation panel 62 is an example of an operation unit. Therefore, any operation means may be used as long as it can accept the operation of the operator. In addition, the display unit 61 can be configured by a touch panel. In this case, the display unit 61 includes a part or all of the functions of the operation panel 62.

  Various kinds of information necessary for operation of the main body 1 are displayed on the display unit 61 as characters, images, and the like. However, the display content displayed on the display unit 81 of the information processing apparatus 8 may be displayed on the display unit 61. Further, various commands may be issued to the main body unit 1 through a pointer operation with a mouse or the like on a character or image displayed on the display unit 61.

  The adjusting unit 601d specifies the position of the subject OB, and adjusts the trajectory when the X-ray generator 11 and the X-ray detector 21 are turned according to the position of the specified subject OB. As a method for specifying the position of the subject OB, for example, a method using a laser beam is conceivable. Specifically, a laser beam is emitted from a position detection unit 17 (here, a laser light source) provided in the X-ray generation unit 10, and the laser beam is irradiated to a characteristic position on the face of the subject. As described above, the X-ray generator 10 is moved. For example, by irradiating a position such as the mouth corner of the lips with a laser beam, the position of a canine that is a part of the dentition can be roughly specified. Thereby, the position of the dentition which the subject OB has can be roughly specified. Based on the positional information thus identified, the turning trajectories of the X-ray generator 11 and the X-ray detector 21 are adjusted (shifted). Thereby, CT imaging, panoramic X-ray tomography, etc. can be performed by appropriately adjusting the positional relationship between the X-ray generator 11, the X-ray detector 21, and the subject OB.

  The main body 1 images a region of interest (a living organ, a bone including a tooth, a joint, etc.) of the subject OB using X-rays in accordance with a command from the operation panel 62 or the information processing device 8. In addition, the main body 1 receives various commands, coordinate data, and the like from the information processing apparatus 8, and transmits X-ray projection data acquired by imaging to the information processing apparatus 8. In the present embodiment, as shown in FIG. 3, the X-rays emitted from the X-ray generator 11 in the X-ray generation unit 10 pass through the subject irradiation X-ray passage region regulated by the X-ray regulation unit 12. The X-ray beam XB obtained in this way is irradiated locally on the sensitive area Xr of the subject OB. The incident X-ray is detected by the X-ray detector 21 of the X-ray detector 20 facing the X-ray generator 11, and image processing based on the detection result of the X-ray detector 21 is performed by the information processing device 8. As a result, various X-ray imaging including CT imaging can be performed.

  The information processing main unit 80 includes a CPU 801 that executes various programs, a fixed disk such as a hard disk, and a general storage unit 802 that stores various data and programs PG2, a ROM 803, and a RAM 804 connected to a bus line. It has a configuration as a simple computer.

  The CPU 801 functions as a position setting unit 801a and an image information processing unit 801b by executing the program PG2 stored in the storage unit 802 on the RAM 804. The position setting unit 801a sets the position of the tomographic plane when generating a CT image or a panoramic tomographic image based on an operation input via the operation unit 82. Further, the image information processing unit 801b performs image processing on an image signal such as frame image data acquired at the time of CT imaging or panoramic X-ray tomography, and a CT image or panoramic tomographic image corresponding to the position of the tomographic plane. Is generated. When the CPU 801 functions as the position setting unit 801a and the image information processing unit 801b, the information processing device 8 functions as an image processing device.

  Note that the main body control unit 60 or the information processing main body unit 80 may acquire the programs PG1 and PG2 via a predetermined network line or the like. Further, the main body control unit 60 or the information processing main body unit 80 may acquire the programs PG1 and PG2 stored in a portable medium (CD-ROM or the like) by reading them with a predetermined reading device. .

  In the present embodiment, a CT imaging region is designated by the operator (operator) via the operation panel 62 or the operation unit 82. Specifically, a screen (illustration, panoramic tomographic image, or the like) that displays a part or the whole of the living body is displayed on the display unit 61 or the display unit 81, and an area that the operator wants to photograph is displayed via the operation panel 62 or the operation unit 82. To specify the shooting area. Alternatively, the region may be directly specified by inputting the name of the region or inputting the code from the operation panel 62 or the operation unit 82 without displaying the region specifying screen on the screen. Separately, the subject may be positioned by irradiating the subject with a visible light beam such as a laser beam from the position detection unit.

  Note that a control unit may be provided in the operation panel 62 to share a part of the control of the main body control unit 60, or the main body control unit 60 may be provided on the entire operation panel 62.

(1.2. Panorama X-ray tomography and generation of panoramic tomographic images)
At the time of panoramic X-ray tomography, the X-ray generator 11 and the X-ray detector 21 are arranged so as to face each other across the dentition of the subject OB, and rotate around the subject OB as an X axis. The motor 60X, the Y-axis motor 60Y, and the turning motor 06Y are driven (see FIG. 3). Further, the X-rays emitted from the X-ray generator 11 pass through the X-ray restricting portion 12 provided on the X-ray emission direction side with respect to the X-ray generator 11, thereby extending in the z-axis direction. Shaped into an X-ray slit beam. The X-ray slit beam that irradiates the subject OB is obtained by blocking an unnecessary X-ray portion by the X-ray restricting unit 12. Preferably, an X-ray restriction unit (not shown) is also provided immediately before the X-ray detector 21 on the X-ray detection unit 20 side so as to block unnecessary scattered X-rays in the X-ray detection unit 20.

  In panoramic X-ray tomography, a standard dental arch (horse-shoe-shaped curve) is assumed in advance. The X-ray generator 11 moves so that the X-ray beam XB is incident on the dental arch substantially perpendicularly.

  The X-ray generator 11 and the X-ray detector 21 are configured to drive the two-dimensional movement by the X-axis motor 60X and the Y-axis motor 60Y of the turning shaft 31 and the turning drive around the turning shaft 31 of the turning arm 30 by the turning motor 60R. The X-ray slit beam that irradiates the dental arch by a synthetic motion moves along a trajectory that takes a trajectory forming an envelope during panoramic X-ray tomography.

  Such movement of the X-ray generator 11 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-131656 (for example, FIG. 5) related to the applicant of the present application.

  In the X-ray detector 21, frame image data having pixel values corresponding to the intensity of incident X-rays is collected at a required frame rate and stored in the storage unit 802. The image information processing unit 801b reconstructs a panoramic tomographic image using the collected frame image data. Specifically, a process of sequentially superimposing overlapping portions of images on successive frame images (a process of adding pixel values (shift addition process)) is performed along a set tomographic plane. Thereby, a single panoramic tomographic image is generated. Various shift addition processes have been proposed so far, and these techniques can be applied as appropriate in the present application. The image information processing unit 801b can also perform image processing in CT imaging and cephalometric imaging using frame image data stored and collected in the storage unit 802.

<X-ray restriction part 12>
(Constitution)
FIG. 4 is a perspective view showing an internal configuration of the X-ray generation unit 10 in the X-ray imaging apparatus 100 of the present embodiment. As shown in the figure, the X-ray generator 10 includes an X-ray generator 11 and an X-ray restricting unit 12.

  The X-ray regulating unit 12 functions as an X-ray irradiation regulating unit that regulates the irradiation range of X-rays emitted from the X-ray generator 11. The X-ray restricting unit 12 is provided in the X-ray generation unit 10 on the X-ray emission direction side of the X-ray generator 11.

  As shown in the figure, the X-rays emitted from the X-ray generator 11 pass through the X-ray restricting unit 12, so that the X-ray irradiation direction L <b> 1 (y direction (the direction in which the X-ray detection unit 20 exists)). Irradiated towards.

  Hereinafter, the configuration of the X-ray restricting unit 12 serving as a characteristic part of the present embodiment will be described. The X-ray restricting unit 12 includes a frame BS, a horizontal displacement X-ray shielding plate XK1 and a vertical displacement X-ray shielding plate XK2 (first and second X-ray shielding units) housed in the frame BS. It has as a main component.

  The frame BS is fixed to the X-ray generator 11 in front of the X-ray generator 11, and the horizontal displacement X-ray shielding plate XK1 and the vertical displacement X-ray shielding plate XK2 are described later with respect to the frame BS. It is possible to displace.

  The flat part of the substrate BS1 of the frame BS is fixed to the front surface of the X-ray generator 11, and the end BS2 protrudes from one end in the x direction (left and right direction) of the substrate BS1 in the y direction (forward) and from the other end. The end portion BS3 protrudes in the y direction (forward), and the end portion BS4 protrudes from the one end of the substrate BS1 in the z direction (vertical direction), in the illustrated example, from the upper end in the y direction (forward).

  An opening OP1 is provided at a position where an X-ray emission hole through which X-rays are emitted from the X-ray generator 11 is located substantially in the center of the substrate BS1, thereby blocking the X-rays emitted from the X-ray generator 11. There is no such thing.

  The main body portion of the horizontal displacement X-ray shielding plate XK1 has a main body portion of a horizontally long rectangular planar structure in which the x direction is the longitudinal direction and the z direction is the short direction. Then, large irradiation field X-ray passage holes C1, X each defining an X-ray passage region (first X-ray passage region) each passing through the main body portion and allowing passage of X-rays in the main body portion. The line slit SL2, the X-ray slit SL1, and the middle irradiation field X-ray passage hole C2 are provided separately from each other along the x direction. In the horizontal displacement X-ray shielding plate XK1, the region that blocks the passage of X-rays relative to the X-ray passage region is a shielding region (first shielding region).

  The large irradiation field X-ray passage hole C1 is formed in the largest region, and the middle irradiation field X-ray passage hole C2 is formed in a region having a shorter formation width in the x direction than the large irradiation field X-ray passage hole C1. SL1 is formed in a region where the formation width in the x direction is shorter than that of the middle irradiation field X-ray passage hole C2, and the formation width of the X-ray slit SL2 is shorter than that in the middle irradiation field X-ray passage hole C2. The formation width in the direction is formed in a region shorter than the X-ray slit SL1.

  Both the formation width in the z direction of the middle irradiation field X-ray passage hole C2 and the formation width in the z direction of the large irradiation field X-ray passage hole C1 may be aligned with the maximum width that can be appropriately irradiated with X-rays. , One may be set smaller than the other.

  For example, when large-field CT imaging is performed in a range that is wide in the x-direction but narrow in the z-direction, the z of the large-field X-ray passage hole C1 is larger than the formation width in the z-direction of the middle-field X-ray passage hole C2. In the case where the formation width in the direction is reduced and the middle-field CT imaging is performed in a narrow range in the z-direction, the medium-field X-ray passage hole is larger than the formation width in the z direction of the large irradiation field X-ray passage hole C1 The formation width of C2 in the z direction is reduced.

  In the present embodiment, the large irradiation field X-ray passage hole C1 and the middle irradiation field X-ray passage hole C2 in the horizontal displacement X-ray shielding plate XK1 are used for CT imaging, and the X-ray slit SL1 is used for panoramic X-ray tomography, X The line slit SL2 is used for cephalometric imaging.

  The horizontal displacement X-ray shielding plate XK1 includes a female screw portion H1 having a screw hole penetrating in the x direction at one end of the lower portion (−z direction side) of the main body, and a through hole penetrating in the x direction at both ends of the upper portion (+ z direction side). Are provided, and a rotating shaft G1 made of a male screw and extending in the x direction is fitted into the female screw portion H1 so as to pass therethrough and guided into the guided members H2 and H2, respectively. The guide shaft G2, which is a member, is passed through. The guided members H2 and H2 are slidable with respect to the guide shaft G2 along the longitudinal direction of the guide shaft G2. The rotation shaft G1 is provided so as to be connected to the rotation shaft of the motor M1, and is formed to extend to the center of the frame BS. The motor M1 is fixedly provided on one of the end portions BS2 and BS3 of the frame body BS, on the inner side surface of the end portion BS2 in the illustrated example. One end of the guide shaft G2 is fixed to the inner side surface of one end portion BS2 of the frame body BS, and the other end is fixed to the inner side surface of the opposite end portion BS3 of the frame body BS.

  The female screw portion H1, the rotation shaft G1, the guided members H2 and H2, and the guide shaft G2 are arranged in the horizontal direction of the X-ray shielding portion that specifically displaces the X-ray shielding portion, specifically, the horizontal displacement X-ray shielding plate XK1. Configure the displacement mechanism.

  The rotation shaft G1 is rotated by the motor M1. The motor M1 is a mechanical element constituting the X-ray shielding unit driving unit 12D (see FIG. 3), and is driven according to the control signal from the X-ray generation unit control unit 601a (see FIG. 3) as described above.

  The X-ray shielding unit driving unit 12D may be configured by a motor M1 and a motor driver for the motor M1, and the control signal from the X-ray generation unit control unit 601a may be converted into a driving signal.

  Accordingly, the horizontal displacement X-ray shielding plate XK1 is driven by driving the female screw portion H1 along the x direction in the direction corresponding to the rotation direction (+ x direction or -x direction) according to the rotation operation of the rotation shaft G1 by the motor M1. The entire horizontal displacement X-ray shielding plate XK1 can be controlled to move along the x direction (horizontal direction). At this time, due to the presence of the guide shaft G2 penetrating the guided members H2 and H2, the displacement in the z direction and the y direction is reliably suppressed when the horizontal displacement X-ray shielding plate XK1 is moved. be able to.

  For the horizontal displacement X-ray shielding plate XK1, the displacement in the x direction is the displacement in the regulation direction intersecting the X-ray irradiation direction.

  As a result, under the control of the X-ray generator control unit 601a, the X-rays irradiated from the X-ray generator 11 are irradiated with the large irradiation field X-ray passage hole C1, the X-ray slit SL2, the X-ray slit SL1, and the middle irradiation field X. The horizontal displacement X-ray shielding plate XK1 can be positioned in a positional relationship that can pass through any of the line passage holes C2. That is, any one of the large irradiation field X-ray passage hole C1, the X-ray slit SL1, the X-ray slit SL2, and the middle irradiation field X-ray passage hole C2 can be positioned on the X-ray irradiation path.

  Although the z direction of the horizontal displacement X-ray shielding plate XK1 is fixed, the large irradiation field X-ray passage hole C1, the X-ray slit SL2, the X-ray slit SL1, and the middle irradiation field X-ray passage hole C2 are respectively The position of the subject irradiation X-ray passing region passing through the X-ray restricting unit 12 is set in advance so as to remain in the position completely included in the X-ray irradiation region from the X-ray generator 11 in the z direction. ing.

  On the other hand, the main body portion of the vertically displaced X-ray shielding plate XK2 has a main body portion having a substantially square planar structure with the same length in the z direction and the x direction, and an X-ray generator along the y direction. 11 and the horizontal displacement X-ray shielding plate XK1.

  And the small irradiation field X-ray passage hole C3 (2nd X-ray passage area | region) which is an X-ray passage area | region which accept | permits X-ray passage is provided in the center part of the main-body part. In the present embodiment, the small irradiation field X-ray passage hole C3 is used for CT imaging. The small irradiation field X-ray passage hole C3 has the same formation width as the large irradiation field X-ray passage hole C1 in the x direction, and is formed about half of the large irradiation field X-ray passage hole C1 in the z direction (regulation direction). It has a width. Further, the peripheral shielding region P3 in the lower direction (−z direction) of the small irradiation field X-ray passage hole C3 has a formation width equal to or larger than the formation width of the large irradiation field X-ray passage hole C1 in the z direction.

  In the horizontal displacement X-ray shielding plate XK2, a region that blocks the passage of X-rays with respect to the X-ray passage region is a shielding region (second shielding region).

  The formation width in the x direction of the small irradiation field X-ray passage hole C3 and the formation width in the x direction of the large irradiation field X-ray passage hole C1 may both be matched to the maximum width that can be appropriately irradiated with X-rays. , One may be set smaller than the other. The idea is the same as described regarding the setting of the formation width of the middle irradiation field X-ray passage hole C2 in the z direction and the formation width of the large irradiation field X-ray passage hole C1 in the z direction.

  The vertical displacement X-ray shielding plate XK2 penetrates in the z-direction into the upper and lower ends of the left portion (−x direction side) and the female screw portion H3 in which the screw hole penetrates in the z direction at one end of the right portion (+ x direction side) of the main body portion. Guided members H4 and H4 having through-holes provided therein are provided, and a rotation shaft G3 configured by a male screw and extending in the z direction is fitted into the female screw portion H3 so as to pass through the guide members H4 and H4. The guide shaft G4 which is a guide member is penetrated inside. The guided members H4 and H4 are slidable with respect to the guide shaft G4 along the longitudinal direction of the guide shaft G4. The rotation shaft G3 is provided so as to be connected to the rotation shaft of the motor M2, and is formed to extend to the center of the frame BS (upper part of the horizontal displacement X-ray shielding plate XK1). The motor M2 is fixedly provided on the inner upper surface of the end portion BS4 of the frame body BS. One end of the guide shaft G4 is fixedly provided on the upper surface inside the end portion BS4 of the frame body BS. The other end of the guide shaft G4 may be fixed to the bottom of the frame body BS.

  The female screw portion H3, the rotation shaft G3, the guided members H4 and H4, and the guide shaft G4 are the X-ray shielding portion, specifically, the X-ray shielding portion vertical direction for displacing the vertical displacement X-ray shielding plate XK2 in the vertical direction. Configure the displacement mechanism.

  The X-ray shielding part horizontal direction displacement mechanism and the X-ray shielding part vertical direction displacement mechanism are first and second X-ray shielding part displacement mechanisms for displacing the X-ray shielding part.

  The rotation shaft G3 is rotated by the motor M2. Similarly to the motor M1, the motor M2 is a mechanical element constituting the X-ray shielding unit driving unit 12D (see FIG. 3), and is driven according to a control signal from the X-ray generation unit control unit 601a.

  The X-ray shielding unit driving unit 12D may be configured by a motor M2 and a motor driver for the motor M2, and the control signal from the X-ray generation unit control unit 601a may be converted into a driving signal.

  Therefore, the vertically displaced X-ray shielding plate XK2 is driven by driving the female screw portion H3 along the z direction in the direction corresponding to the rotation direction (+ z direction or -z direction) according to the rotation operation of the rotation shaft G3 by the motor M2. The entire vertical displacement X-ray shielding plate XK2 can be controlled to move along the z direction. At this time, due to the presence of the guide shaft G4 provided penetrating in the guided members H4 and H4, the displacement in the x direction and the y direction is reliably suppressed when the vertical displacement X-ray shielding plate XK2 is moved. be able to.

  With respect to the vertical displacement X-ray shielding plate XK2, the displacement in the z direction is the displacement in the regulation direction that intersects the X-ray irradiation direction.

  As a result, the vertically displaced X-ray shielding plate XK2 can be appropriately moved along the z direction under the control of the X-ray generation unit control unit 601a.

  As described above, the X-ray restricting unit 12 controls the movement of the horizontal displacement X-ray shielding plate XK1 in the x direction and the vertical displacement X-ray shielding plate XK2 in the z direction under the control of the X-ray generation unit control unit 601a. Of the X-rays emitted from the X-ray generator 11 in combination with the movement control, an X-ray irradiation range restriction process for forming a subject irradiation X-ray passage region that passes through the X-ray restriction unit 12 (first to first described later). 3 X-ray irradiation range restriction processing) can be executed.

  Although the x direction of the vertically displaced X-ray shielding plate XK2 is fixed, the small irradiation field X-ray passage hole C3 is a range in which the subject irradiation X-ray passage area is formed by the small irradiation field X-ray passage hole C3. In the x direction, the position is set in advance so as to remain at a position completely included in the X-ray irradiation region from the X-ray generator 11.

<Large field CT imaging>
FIG. 5 shows a horizontal displacement X-ray shielding plate XK1 in the X-ray restricting unit 12 at the time of large-field CT imaging by the X-ray irradiation range restricting process (second X-ray irradiation range restricting process) of the X-ray restricting unit 12. FIG. 6 is an explanatory diagram showing a positional relationship in the z direction of the vertical displacement X-ray shielding plate XK2.

  As shown in the figure, the center position 21c of the X-ray detection surface of the X-ray detector 21 is arranged at a position higher in the z direction than the focal point F of the X-ray that is the generation point of the X-ray in the X-ray generator 11. The so-called launch irradiation is performed. The positional relationship between the X-ray generator 11 and the X-ray detector 21 in the z direction is the same in the small-field CT imaging (parts 1 and 2) and panoramic X-ray tomography shown in FIGS. It is.

  As shown in FIGS. 6A and 6B, the X-ray emitted from the X-ray generator 11 is irradiated through the large-field X-ray passage hole of the horizontal displacement X-ray shielding plate XK1 in the large-field CT imaging. The position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set by driving the motor M1 so that the position can pass C1. That is, the position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set so that the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 is positioned on the X-ray irradiation path. I do.

  On the other hand, as shown in FIGS. 4A and 4B, the vertically displaced X-ray shielding plate XK2 is moved upward (+ z direction), and the X-ray irradiation path from the focal point F of the X-ray generator 11 is changed. Set the retreat position so that it completely deviates. That is, the position of the vertical displacement X-ray shielding plate XK2 in the z direction is set so that the vertical displacement X-ray shielding plate XK2 is positioned outside and on the X-ray irradiation path. Therefore, on the X-ray irradiation path, the peripheral shielding region of the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 and the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 There is no overlap seen from the y direction.

  As a result, as shown in FIG. 6A, the X-ray irradiated from the focal point F of the X-ray generator 11 is a large irradiation field X-ray passage hole of the horizontal displacement X-ray shielding plate XK1 of the X-ray restricting portion 12. X-ray irradiation range restriction processing (second X-ray irradiation range restriction processing) for irradiating the entire DAA of the dental arch DA of the subject OB with the cone beam CB1 obtained by passing C1 as it is as the subject irradiation X-ray passage region. Large field CT imaging can be realized by executing. Note that substantially the entire dental arch DA of the subject OB may be an X-ray imaging region.

  By replacing the large irradiation field X-ray passage hole C1 in the positional relationship in the x direction shown in FIGS. 5 (a) and 5 (b) with the middle irradiation field X-ray passage hole C2, medium irradiation field CT imaging is realized. Can do.

<Small field CT imaging (1)>
FIG. 6 shows a horizontal displacement X-ray shielding plate XK1 in the X-ray restriction unit 12 at the time of small-field CT imaging by the X-ray irradiation range restriction process (third X-ray irradiation range restriction process) of the X-ray restriction unit 12. FIG. 5 is an explanatory diagram showing a positional relationship in the x direction and the z direction of the vertical displacement X-ray shielding plate XK2.

  As shown in FIGS. 5A and 5B, during small field CT imaging, as in the case of large field CT imaging shown in FIG. 5, horizontal displacement X-ray shielding is performed on the X-ray irradiation path. The position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set so that the large irradiation field X-ray passage hole C1 of the plate XK1 is located.

  On the other hand, as shown in FIGS. 4A and 4B, the vertically displaced X-ray shielding plate XK2 is moved from the retracted position shown in FIG. The small irradiation field X-ray passage hole C3 of the vertically displaced X-ray shielding plate XK2 is positioned on the irradiation path, and the small irradiation field X-ray passage hole C3 is in the large irradiation field X-ray passage hole C1 when viewed from the y direction. The position is set so that the positional relationship is completely included in the.

  Therefore, the overlapping area of the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 and the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 as viewed from the y direction is the small irradiation field. It becomes the X-ray passage hole C3 itself.

  As a result, as shown in FIG. 6A, the X-rays irradiated from the focal point F of the X-ray generator 11 are small irradiation field X-ray passage holes of the vertical displacement X-ray shielding plate XK2 of the X-ray restricting portion 12. X-ray irradiation range restriction processing for selectively irradiating the upper teeth DAU of the subject OB with the cone beam CB2 obtained by passing C3 as it is as the subject irradiation X-ray passage region (narrow in the third X-ray irradiation range restriction processing) Small irradiation field CT imaging can be realized by executing the formation width X-ray passage region whole use processing).

  A region where only a part of the small irradiation field X-ray passage hole C3 and a part of the large irradiation field X-ray passage hole C1 overlap may be set as the subject irradiation X-ray passage region. In this case, on the X-ray irradiation path, a region where at least a part of the small irradiation field X-ray passage hole C3 and at least a part of the large irradiation field X-ray passage hole C1 is the subject irradiation X-ray passage region.

  The horizontal displacement X-ray shielding plate XK1 has a large room for displacement in the x direction so that it can be completely retracted from the X-ray irradiation path passing through the small irradiation field X-ray passage hole C3. Small-field CT imaging may be performed in a state where only the hole C3 restricts X-rays emitted from the X-ray generator 11.

  As described above, in the third X-ray irradiation range restriction process, at least a part of the large irradiation field X-ray passage hole C1 and the small irradiation field X-ray passage hole C3 are overlapped to overlap the overlapping region with the subject irradiation X-ray passage region. And the process of setting only the small irradiation field X-ray passage hole C3 as the subject irradiation X-ray passage area.

  In the example of the small-field CT imaging of the present embodiment, only the region including a part of the teeth of the dental arch DA of the subject OB, particularly the region including a part of the teeth in the z direction, is X. This is the line imaging area.

  From the positional relationship in the x direction shown in FIGS. 5 (a) and 5 (b), a vertically displaced X-ray shielding plate is further disposed on the X-ray irradiation path than in the state shown in FIGS. 6 (a) and 6 (b). By moving XK2 downward, it is possible to realize small-field CT imaging that selectively irradiates the mandibular dentition DAL with the cone beam CB2.

<Small-field CT imaging (2)>
FIG. 7 shows a horizontal displacement X-ray shielding plate XK1 and a vertical displacement X-ray shielding in the X-ray restriction unit 12 in the small field CT imaging (part 2) by the X-ray irradiation range restriction process of the X-ray restriction unit 12. It is explanatory drawing which shows the positional relationship in the x direction and z direction of board XK2.

(Mandibular dentition DAL photography)
FIGS. 4A and 4B show small-field CT imaging for the lower dentition DAL. As shown in (a) and (b) of the figure, during the small field CT imaging (part 2), the horizontal direction on the X-ray irradiation path is the same as in the large field CT imaging shown in FIG. The position in the x direction of the horizontal displacement X-ray shielding plate XK1 is set so that the large irradiation field X-ray passage hole C1 of the displacement X-ray shielding plate XK1 is positioned.

  On the other hand, as shown in FIGS. 6A and 6B, the vertically displaced X-ray shielding plate XK2 is located below (−z direction) from the retracted position shown in FIG. 5 and from the complete irradiation position shown in FIG. A part of X-rays located above (+ z direction) and capable of passing through the large irradiation field X-ray passage hole C1 by the peripheral shielding region P3 under the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2. Is set in the z direction of the vertically displaced X-ray shielding plate XK2.

  That is, at a position where a part of the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 and a part of the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 overlap each other when viewed from the y direction. The vertical displacement X-ray shielding plate XK2 is moved in the z direction. In this state, the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 and the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 are irradiated with X-rays when viewed from the y direction. There is no overlap on the path.

  Accordingly, only the region that is not shielded by the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 in the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 is the subject irradiation X-ray passage region. Become.

  As a result, as shown in FIG. 6A, the large irradiation field X-ray passage hole C1 is within a range in which the X-ray is not shielded by the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 on the X-ray irradiation path. The cone beam CB3 is obtained by setting the region passing through the subject irradiation X-ray passage region. At this time, by setting the cone beam CB3 so as to form an irradiation region corresponding to the lower jaw dent row DAL of the subject OB, an X-ray irradiation range restriction process (first step) for selectively irradiating the lower dent row DAL of the subject OB. 1 X-ray irradiation range restriction process) can be executed to realize small-field CT imaging (part 2).

(Maxillary dentition DAU)
(C) and (d) in the figure show a small-field CT imaging for the maxillary dentition DAU. As shown in FIGS. 4C and 4D, the positional relationship between the horizontal direction X-ray shielding plate XK1 and the vertical direction displacement X-ray shielding plate XK2 in the x direction and the z direction is shown in FIGS. The cone beam CB3 is obtained in exactly the same positional relationship as shown in FIG.

  On the other hand, by lowering the subject fixing portion 421 downward (−z direction), the relative height of the subject OB with respect to the focal point F of the X-ray generator 11 is lowered, and the cone beam CB3 is moved to the upper teeth DAU of the subject OB. Is set so as to form an irradiation region corresponding to.

  As a result, as shown in FIG. 5C, the large irradiation field X-ray passage hole C1 is within the range where the X-ray is not shielded by the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 on the X-ray irradiation path X. An X-ray irradiation range restriction process (first X-ray irradiation range restriction process) is performed in which the cone beam CB3 obtained as a subject irradiation X-ray passage region is selectively irradiated to the upper teeth DAU of the subject OB. Thus, small-field CT imaging (part 2) can be realized.

  In the example of the small-field CT imaging of the present embodiment, only the region including a part of the teeth of the dental arch DA of the subject OB, particularly the region including a part of the teeth in the z direction, is X. This is the line imaging area.

  Although not shown, the horizontal displacement X-ray shielding plate XK1 and a set of X-ray shielding portion horizontal displacement mechanisms including the female screw portion H1, the rotation shaft G1, the guided members H2 and H2, and the guide shaft G2 are further provided on the substrate. A mechanism may be provided for mounting and displacing the entire substrate in the z direction with respect to the main body of the X-ray restricting unit 12. With this configuration, in addition to the displacement in the z direction of the vertically displaced X-ray shielding plate XK2, the horizontal displacement X-ray shielding plate XK1 can be displaced in the z direction, which can be used, for example, for adjusting the irradiation direction.

  The displacement in the z direction of the vertical displacement X-ray shielding plate XK2 with respect to the horizontal displacement X-ray shielding plate XK1 and the displacement in the z direction of the horizontal displacement X-ray shielding plate XK1 with respect to the vertical displacement X-ray shielding plate XK2 are also in the horizontal direction. This is the relative displacement of one of the displacement X-ray shielding plate XK1 and the vertical displacement X-ray shielding plate XK2 with respect to the other.

  Similarly, although not shown, a set of vertical displacement X-ray shielding plate XK2 and a set of X-ray shielding portion vertical displacement mechanisms including a female screw portion H3, a rotation shaft G3, guided members H2 and H2, and a guide shaft G2, Further, a mechanism for placing the whole substrate on the substrate and displacing the entire substrate in the x direction with respect to the main body of the X-ray regulating unit 12 may be provided. With this configuration, in addition to the displacement in the x direction of the horizontal direction displacement X-ray shielding plate XK1, the vertical direction displacement X-ray shielding plate XK2 can be displaced in the x direction, which can be used, for example, for adjusting the irradiation direction.

  The displacement in the x direction of the vertical displacement X-ray shielding plate XK2 relative to the horizontal displacement X-ray shielding plate XK1, and the displacement in the x direction of the horizontal displacement X-ray shielding plate XK1 relative to the vertical displacement X-ray shielding plate XK2 are also in the horizontal direction. This is the relative displacement of one of the displacement X-ray shielding plate XK1 and the vertical displacement X-ray shielding plate XK2 with respect to the other.

  In the above description, the terms “medium irradiation field X-ray passage hole C2” and “small irradiation field X-ray passage hole C3” are used, but C3 must necessarily be smaller in area than C2. Therefore, the terms and concepts of these terms may be replaced as follows.

  The middle irradiation field X-ray passage hole C2 is a horizontal limited irradiation field X-ray passage hole C2 (an X-ray passage hole that restricts the horizontal spread of the X-ray beam to be narrower than the large irradiation field X-ray passage hole C1). Yes.)

  The small irradiation field X-ray passage hole C3 is a vertical limited irradiation field X-ray passage hole C3 (an X-ray passage hole that restricts the vertical spread of the X-ray beam to be narrower than the large irradiation field X-ray passage hole C1). Yes.)

  The terms “intermediate field CT imaging” and “small field CT imaging” may be similarly considered as follows.

  Change the middle field CT imaging to the horizontal limited field CT imaging (the CT imaging in which the spread in the horizontal direction is narrower than the large field CT imaging).

  Change the small field CT imaging to the vertical limited field CT imaging (the CT imaging in which the vertical spread is narrower than the large field CT imaging).

  In the example shown in FIG. 7 described above, a part of X-rays that can pass through the large irradiation field X-ray passage hole C1 by the peripheral shielding region P3 below the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2. Although the position of the z direction of the vertically displaced X-ray shielding plate XK2 is set at a position where the X-ray can be shielded, the middle irradiation field X-ray passage hole C2 may be used instead of the large irradiation field X-ray passage hole C1. .

  That is, the position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set so that the middle irradiation field X-ray passage hole C2 of the horizontal displacement X-ray shielding plate XK1 is positioned on the X-ray irradiation path. The z-direction movement of the vertical displacement X-ray shielding plate XK2 is such that a part of the irradiation field X-ray passage hole C2 and a part of the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 overlap each other when viewed from the y direction. I do. In this way, a wider variety of subject irradiation X-ray passage areas can be set.

  Of course, as shown in FIGS. 5 (a) and 5 (b), the vertically displaced X-ray shielding plate XK2 is moved upward (+ z direction), and the X-ray irradiation path from the focal point F of the X-ray generator 11 is used. It is also possible to perform medium irradiation field CT imaging in which the entire irradiation field X-ray passage hole C2 is moved to the retracted position that completely deviates and the subject irradiation X-ray passage area is used.

  In addition, CT imaging can be performed in which the middle irradiation field X-ray passage hole C2 and the small irradiation field X-ray passage hole C3 are overlapped and the region where both overlap is the subject irradiation X-ray passage area. In this case, the position of the small irradiation field X-ray passage hole C3 can be moved and adjusted in the z direction within a range in the z direction where the middle irradiation field X-ray passage hole C2 and the small irradiation field X-ray passage hole C3 overlap.

  In this way, the middle irradiation field CT imaging in which the entire area of the middle irradiation field X-ray passage hole C2 is the subject irradiation X-ray passage area overlaps the middle irradiation field X-ray passage hole C2 and the small irradiation field X-ray passage hole C3. By the peripheral shielding region P3 by superimposing a part of the middle irradiation field X-ray passage hole C2 and a part of the peripheral shielding region P3 with the small irradiation field CT imaging (part 1) in which the region is the subject irradiation X-ray passage region. Small-field CT imaging (part 2) in which the region through which the X-rays pass through the middle irradiation field X-ray passage hole C2 in the unshielded range is the subject irradiation X-ray passage region can be further selected.

<Panorama shooting>
FIG. 8 shows a horizontal displacement X-ray shielding plate XK1 and a vertical displacement X-ray shielding plate XK2 in the X-ray restriction unit 12 at the time of panoramic (X-ray tomography) imaging by the X-ray irradiation range restriction process of the X-ray restriction unit 12. It is explanatory drawing which shows the positional relationship in x direction and z direction.

(Mandibular dentition DAL photography)
FIGS. 9A and 9B show panoramic imaging for the lower dentition DAL. As shown in FIGS. 6A and 6B, the horizontal displacement X-ray is so arranged that the X-ray slit SL1 of the horizontal displacement X-ray shielding plate XK1 is positioned on the X-ray irradiation path during panoramic imaging. The position of the shielding plate XK1 in the x direction is set. The X-ray passage region formed by the X-ray slit SL1 is a slit region.

  On the other hand, as shown in FIGS. 6A and 6B, the vertically displaced X-ray shielding plate XK2 is moved downward (−z direction) from the retracted position shown in FIG. 5 from the complete irradiation position shown in FIG. The X-ray can be partially shielded by the peripheral shielding region P3 below the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 by moving to the upper position. Set.

  That is, the vertical displacement X is at a position where a part of the X-ray slit SL1 of the horizontal displacement X-ray shielding plate XK1 and a part of the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 overlap each other when viewed from the y direction. The line shield plate XK2 is moved in the z direction. In this state, the X-ray slit SL1 of the horizontal displacement X-ray shielding plate XK1 and the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 completely overlap on the X-ray irradiation path when viewed from the y direction. Do not fit.

  Accordingly, only the region that is not shielded by the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 in the X-ray slit SL1 of the horizontal displacement X-ray shielding plate XK1 becomes the subject irradiation X-ray passage region.

  As a result, as shown in FIG. 5A, on the X-ray irradiation path, an area through which the X-ray passes through the X-ray slit SL1 in a range where the X-ray is not shielded by the peripheral shielding area P3 of the vertically displaced X-ray shielding plate XK2. X-ray slit beam XB1 is obtained using X as a subject irradiation X-ray passage region. At this time, by setting the X-ray slit beam XB1 so as to form an irradiation area corresponding to the lower jaw dent row DAL of the subject OB, the X-ray irradiation range restriction for selectively irradiating the lower dent row DAL of the subject OB. Panorama processing can be realized by executing processing (first X-ray irradiation range restriction processing).

(Maxillary dentition DAU)
FIGS. 7C and 7D show panoramic photography for the upper dentition DAU. As shown in FIGS. 4C and 4D, the positional relationship between the horizontal direction X-ray shielding plate XK1 and the vertical direction displacement X-ray shielding plate XK2 in the x direction and the z direction is shown in FIGS. The X-ray slit beam XB1 is obtained in exactly the same positional relationship as shown in FIG.

  On the other hand, by lowering the subject fixing portion 421 downward (−z direction), the relative height of the subject OB with respect to the focal point F of the X-ray generator 11 is lowered, so that the X-ray slit beam XB1 is the upper jaw of the subject OB. It sets so that the irradiation area | region corresponding to the dentition DAU may be formed.

  As a result, as shown in FIG. 5C, a region that passes through the X-ray slit SL1 in a range in which the X-ray is not shielded by the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 on the X-ray irradiation path. By executing an X-ray irradiation range restriction process (first X-ray irradiation range restriction process) for selectively irradiating the upper teeth DAU of the subject OB with the X-ray slit beam XB1 obtained as the subject irradiation X-ray passage region Panorama shooting can be realized.

  The panoramic imaging of the lower dentition DAL, the panoramic imaging of the upper dentition DAU, etc. includes a part of the teeth of the dental arch DA of the subject OB, particularly a part of the teeth in the z direction. This is an example of small-field panoramic imaging in which only the region is an X-ray imaging region.

  Similar to the large field CT imaging shown in FIGS. 5A and 5B, the vertically displaced X-ray shielding plate XK2 completely deviates from the X-ray irradiation path from the focal point F of the X-ray generator 11. The position of the vertical displacement X-ray shielding plate XK2 is set in the z direction so that the vertical displacement X-ray shielding plate XK2 is positioned outside the X-ray irradiation path, and X-ray irradiation is performed. On the path, the X-ray slit SL1 of the horizontal displacement X-ray shielding plate XK1 and the overlapping of the vertical displacement X-ray shielding plate XK2 and the peripheral shielding region of the small irradiation field X-ray passage hole C3 are seen from the y direction. Needless to say, panoramic imaging of the entire dental arch DAA of the dental arch DA or substantially the entire dental arch DA can be performed. Note that panoramic imaging of the entire dental arch DAA or substantially the entire dental arch DA is an example of large-field panoramic imaging.

  As for panoramic imaging, large-field panoramic imaging where the entire area of the slit SL1 is the subject irradiation X-ray passage area and small irradiation where the area where the slit SL1 overlaps the small irradiation field X-ray passage hole C3 is the subject irradiation X-ray passage area. Field panoramic photography (part 1) and overlap of a part of the slit SL1 and a part of the peripheral shielding area P3 cause the subject irradiation X-rays to pass through the area where the X-rays pass through the slit SL1 in a range not covered by the peripheral shielding area P3. Small-field panorama shooting (part 2) as an area can be further selected.

  Although illustration is omitted, in the large-field cephalometric imaging, the X-ray emitted from the X-ray generator 11 is horizontal instead of the large-field X-ray passage hole C1 shown in FIGS. 5 (a) and 5 (b). The position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set by driving the motor M1 so that the position can pass through the slit SL2 of the direction displacement X-ray shielding plate XK1, and on the X-ray irradiation path. The position of the horizontal displacement X-ray shielding plate XK1 in the x direction is set so that the slit SL2 of the horizontal displacement X-ray shielding plate XK1 is positioned.

  On the other hand, as shown in FIGS. 5A and 5B, the X-ray irradiation path from the focal point F of the X-ray generator 11 is moved by moving the vertical displacement X-ray shielding plate XK2 upward (+ z direction). Set to a retreat position that completely deviates from. That is, the position of the vertical displacement X-ray shielding plate XK2 in the z direction is set so that the vertical displacement X-ray shielding plate XK2 is positioned outside and on the X-ray irradiation path. Therefore, on the X-ray irradiation path, the slit SL2 of the horizontal displacement X-ray shielding plate XK1 and the peripheral shielding region of the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2 are viewed from the y direction. There is no overlap.

  In small-field cephalometric imaging, the vertical displacement X-ray shielding plate XK2 is positioned lower (−z direction) than in large-field cephalometric imaging, and the vertical-direction displacement X-ray shielding plate XK2 passes through the small irradiation field X-ray. The z direction of the vertically displaced X-ray shielding plate XK2 is set at a position where a part of the X-rays that can pass through the slit SL2 can be shielded by the peripheral shielding region P3 below the hole C3.

  In this way, it is possible to switch between large-field cephalo imaging and small-field cephalo imaging. For example, large-field cephalo imaging can be performed on the entire head or almost the entire head, and small-field cephalo imaging. Thus, it is possible to perform cephalometric imaging in which the upper part of the head is not irradiated with X-rays.

  As a range irradiated by the small-field cephalo imaging, for example, only a range including a measurement point measured by the cephalo imaging is irradiated with X-rays, so that only a range below the nadion position is irradiated with X-rays. Thus, the range from the portion slightly above the nadion position to the top of the head can be set so as not to irradiate X-rays. Of course, this range may be adjustable according to conditions such as physique.

<Height adjustment function by subject fixing unit 421>
FIG. 9 is an explanatory view schematically showing the contents of height adjustment of the subject fixing portion 421 in the small irradiation field CT imaging (part 2) shown in FIG. 9A corresponds to FIGS. 7A and 7B, and FIG. 9B corresponds to FIGS. 7C and 7D.

  First, the state displacement of the support frame 40 and the subject fixing portion 421 from the state shown in FIG. 9A to the state shown in FIG. 9B will be described.

  In the state shown in FIG. 9A, the cone beam CB3 irradiates the lower jaw dentition DAL. Since the area necessary for the irradiation of the lower dentition DAL and the irradiation of the upper dentition DAU is substantially equal, the horizontal displacement X-ray shielding plate XK1 and the vertical displacement with respect to the X-ray generation unit 11 provided in the turning arm 30 The positional relationship of the X-ray shielding plate XK2 can be maintained as it is, and it can be applied to irradiation of the maxillary dentition DAU as shown in FIG. 9 (b).

  That is, the support frame 40 is raised while maintaining the positional relationship between the X-ray generator 11 and the X-ray shielding plates XK1 and XK2.

  As a result, the support frame 40 in which the upper frame 41 and the lower frame 42 are integrally formed rises by a displacement amount D1. The displacement amount D1 is set to a height at which the cone beam CB3 can irradiate the entire maxillary dentition DAU when the position of the subject OB in the z direction is fixed.

  At this time, in the X-ray imaging apparatus 100 of the present embodiment, since the subject fixing unit 421 is provided on the lower frame 42, the subject fixing unit 421 is also configured as long as the subject fixing unit 421 is not moved relative to the lower frame 42. The displacement D1 increases from the state shown in FIG. Therefore, the cone beam CB3 cannot be irradiated to the maxillary dentition DAU of the subject OB as it is.

  Therefore, the shaft portion of the subject fixing portion 421 is lowered by the displacement amount D2 (= D1). That is, the subject fixing portion 421 is displaced by a descending amount D2 that cancels the ascent amount D1 of the lower frame 42 in the height direction, and the chin rest portion that is a subject holding portion in the subject fixing portion 421 also in the state shown in FIG. The absolute height of 421A is maintained in the state shown in FIG.

  Therefore, the absolute height of the subject OB does not change even with the state displacement shown in FIGS. As a result, as shown in FIG. 5B, the cone beam CB3 can be irradiated to the maxillary dentition DAU without changing the absolute height of the subject OB in the z direction.

  Needless to say, when the state shown in FIG. 9B is changed to the state shown in FIG. 9A, that is, when the support frame 40 is lowered by the displacement amount D1, the above is opposite. As the support frame 40 is lowered by the displacement amount D1, the shaft portion of the subject fixing portion 421 is raised by the displacement amount D2 (= D1).

  In the configuration example shown in FIG. 9, the support frame 40 is moved up and down by rotationally driving a pulley on which a belt for fixing the support frame 40 and a balance weight (not shown) on both ends is driven by a lift drive motor 40M. it can. The raising / lowering drive motor 40M can be driven, for example, when the operator operates the operation means 62.

  The balance weight, the belt for fixing the balance weight to both ends, the pulley around the belt, the lift drive motor 40M, and the like constitute a lift part as a support part lift mechanism.

  The subject fixing unit 421 is raised and lowered by an actuator (not shown). For this actuator, for example, a set of lifting mechanisms similar to the female screw portion H3, the rotating shaft G3, and the motor M2 shown in FIG. 4 is adopted, and the female screw portion similar to the female screw portion H3 is fixed to the shaft portion of the subject fixing portion 421. A configuration in which the subject fixing portion 421 is driven up and down by a motor similar to the motor M2 fixed inside the lower frame 42 is conceivable.

  If the support frame 40 is raised and the subject fixing portion 421 is lowered synchronously with the same amount of displacement, the subject OB does not move, and the absolute height of the subject OB in the z direction can be maintained. Similarly, when the support frame 40 is lowered, it is convenient to perform the lowering of the support frame 40 and the raising of the subject fixing portion 421 in synchronization with the same amount of displacement.

  FIG. 10 is an explanatory view showing another specific example of the height adjustment of the chin rest portion 421A in the subject fixing portion 421. In FIG. 9, the subject fixing unit 421 is driven up and down by an actuator, but FIG. 10 is an example in which the height of the subject fixing unit 421 can be adjusted manually. As shown in the figure, a groove 46a is provided on the side surface of the subject fixing shaft 421J on the convex portion 45d of the chin rest receiving portion 45 which is provided in a concave shape from the surface to the bottom surface of the lower frame 42 and can receive the subject fixing shaft 421J. The subject fixing portion 421 can be erected from the upper surface of the lower frame 42 by fixing the subject fixing shaft 421J while rotating so as to be fitted to any of the groove 46b.

  When photographing the lower dentition DAL shown in FIG. 9A, the projection 45d can be fitted into the groove 46a so that the chin rest 421a is at a relatively high position h1 from the surface of the lower frame 42. On the other hand, at the time of photographing the maxillary dentition DAU shown in FIG. 9B, the convex portion 45d can be fitted into the groove 46b so that the chin rest portion 421a is at a relatively low position h2 from the surface of the lower frame 42. At this time, it is set so as to satisfy “h1−h2 = D2 = D1”.

  In the example shown in the figure, the height of the end of the groove 46b with which the convex portion 45d abuts is fitted at a position higher than the height of the end of the groove 46a by the amount of D1 = D2.

  In the example of FIG. 10, basically, the operator selectively fits the convex portion 45d into either the groove 46a or the groove 46b depending on whether the subject to be photographed is an upper jaw tooth or a lower jaw tooth. After adjusting the height of the chin rest portion 421A, if necessary, the head frame may be positioned by adjusting the height of the entire support frame 40 with respect to the subject OB.

  When the height of the chin rest portion 421A is adjusted to photograph one of the upper jaw teeth and the lower jaw teeth and then the other shoot is taken, the subject OB temporarily removes the jaw when changing the height of the chin rest portion 421A. However, it can be configured at low cost.

  An actuator (not shown) for raising and lowering the subject fixing portion 421, a mechanism for adjusting the height of the chin rest portion 421A shown in FIG. 10 and the like constitute a subject holding portion raising and lowering mechanism.

  9 and 10 show an example of adjusting the height of the subject fixing portion 421 in the case of the small field CT imaging (part 2) shown in FIG. 7, but similarly, the panoramic imaging shown in FIG. This can also be applied to the height adjustment of the subject fixing portion 421 in FIG.

<Effects of the present embodiment>
According to the X-ray imaging apparatus 100 of the present embodiment, the X-ray shielding plates XK1 and XK2 (first and second X-rays) are arranged in the regulation direction (z direction) that intersects the X-ray irradiation direction (y direction). The vertical displacement X-ray shielding plate XK2 of the shielding portion) is superimposed relative to the horizontal displacement X-ray shielding plate XK1 as viewed from the y direction, and the X-ray restricting portion 12 is X-rayed. X-ray irradiation range restriction processing for restricting the subject irradiation X-ray passage area through which the camera passes is realized.

  Then, as shown in FIG. 7 (FIG. 8), the X-ray imaging apparatus 100 includes a part of the peripheral shielding area P3 (second X-ray shielding area) of the vertical displacement X-ray shielding plate XK2 and the horizontal displacement X. Y with a part of the large irradiation field X-ray passage hole C1 (the first X-ray passage region (other X-ray slit SL1, X-ray slit SL2, medium irradiation field X-ray passage hole C2)) of the radiation shielding plate XK1 The first X-ray irradiation range restriction process based on the superposition viewed from the direction can be executed. The first X-ray irradiation range restriction process is performed without using the small irradiation field X-ray passage hole C3 (second X-ray passage region) of the vertical displacement X-ray shielding plate XK2 on the X-ray path at all. A part of the peripheral shielding region P3 formed around the irradiation field X-ray passage hole C3 is used for overlapping with a part of the large irradiation field X-ray passage hole C1.

  By performing the first X-ray irradiation range restriction process using the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2, the contents of the subject irradiation X-ray passage region are changed, and various subject irradiations are performed. By setting the X-ray passage region, there is an effect that various X-ray irradiation ranges can be realized.

  In the first X-ray irradiation range restriction process, the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2 for small field CT imaging (part 1) shown in FIG. 6 is shown in FIGS. Further, since it can be realized by using as a shielding means at the time of small-field CT imaging (part 2) and panoramic imaging, the X-ray imaging apparatus 100 can be obtained with a relatively simple configuration.

  Further, in the first X-ray irradiation range restriction process shown in FIGS. 7 and 8, a part of the horizontal displacement X-ray shielding plate XK1 above the large irradiation field X-ray passage hole C1 (X-ray slit SL1) is partially removed. The vertical displacement X-ray shielding plate XK2 is shielded by the peripheral shielding region P3.

  For this reason, X-ray imaging is performed with the launch irradiation configuration of the panoramic X-ray imaging apparatus in which the center position 12c of the X-ray detection surface of the X-ray restricting unit 12 is arranged higher in the z direction than the focal point F in the X-ray generator 11. However, the upper region of the X-ray irradiation path, which has a relatively high possibility of artifacts, is effectively shielded, and the small irradiation field CT imaging (part 2) and the small irradiation field panoramic imaging (FIG. 7) shown in FIG. Panoramic shooting shown in FIG.

  This effect is shown, for example, in cone beam CB2 in the small field CT imaging (part 1) shown in FIG. 6 and in the small field CT imaging (part 2) shown in FIG. It can be seen from the comparison with the cone beam CB3.

  Furthermore, according to the X-ray imaging apparatus 100 of the embodiment, in addition to the first X-ray irradiation range restriction process, the second X-ray irradiation range restriction process at the time of large-field CT imaging shown in FIG. Since the third X-ray irradiation range restriction process at the time of small-field CT imaging (part 1) shown in FIG. 6 can be executed together, there is an effect that a wider variety of X-ray irradiation ranges can be realized. .

  Further, as shown in FIGS. 5 to 7, various X-ray CT imaging using cone beams CB1 to CB3 can be realized.

  In addition, the CT imaging can be completed when the turning of the revolving arm 30 is approximately one rotation from a half rotation, so that the imaging can be performed in a short time and the burden on the subject who is the subject OB can be reduced.

  Further, in the z direction, which is the regulation direction, formation between the large irradiation field X-ray passage hole C1 of the horizontal displacement X-ray shielding plate XK1 and the small irradiation field X-ray passage hole C3 of the vertical displacement X-ray shielding plate XK2. By changing the width, a wider variety of X-ray irradiation ranges can be realized.

  In addition, the X-ray imaging of the large field by the second X-ray irradiation range restriction process shown in FIG. 5 and the narrow formation width X-ray passage region of the third X-ray irradiation range restriction process shown in FIG. It is possible to selectively perform X-ray imaging of the small irradiation field by the entire use processing of the small irradiation field X-ray passage hole C3 that can be displaced in the z direction.

  Further, according to the present embodiment, X-ray imaging for the entire dental arch DAA in large-field CT imaging and large-field panorama imaging, and dentition in small-field CT imaging and small-field panorama imaging. Since X-ray imaging for a part of the bow DA can be selected, X-ray imaging can be performed with a minimum necessary X-ray exposure.

  Also, by executing the first X-ray irradiation range restriction process for panoramic imaging shown in FIG. 8, various X-ray imaging using the X-ray slit beam XB1 is realized, and various panoramic tomographic images are obtained. Can be obtained.

  Further, in the X-ray imaging apparatus 100 of the present embodiment, as shown in FIGS. 9 and 10, the subject fixing portion 421 is lifted and lowered by the support frame 40 (lower frame 42) in the height direction z direction. The height of the chin rest portion 421A, which is a subject holding portion that holds the subject OB, with respect to the surface of the lower frame 42 can be displaced so as to cancel out.

  For this reason, the irradiation range should be changed from the lower dentition DAL to the upper dentition DAU as shown in FIGS. 7 (c) and 8 (d) with respect to FIGS. Even if the X-ray irradiation position on the subject OB is changed in the height direction, the absolute value in the height direction of the holding position of the subject OB by the chin rest 421A can always be kept constant.

  As a result, the subject's head or the like, which is the subject OB held by the chin rest portion 421A of the subject fixing portion 421, is always kept at a certain absolute height, so that the subject OB is not burdened. There is an effect that X-ray imaging can be performed by changing the X-ray irradiation position in the height direction.

(Other)
In the X-ray restricting section 12 of the present embodiment described above, the horizontal displacement X-ray shielding plate XK1 is provided with the large irradiation field X-ray passage hole C1, the X-ray slits SL1 and SL2, and the middle irradiation field X-ray passage hole C2. The vertical displacement X-ray shielding plate XK2 is provided with a small irradiation field X-ray passage hole C3 so that various types of X-ray imaging can be realized.

  However, it is also conceivable that the X-ray shielding plates XK1 and XK2 each have only a CT imaging passage hole and constitute an X-ray restricting portion 12 dedicated to CT imaging. Similarly, it is also conceivable that only the X-ray shielding plates XK1 and XK2 each have only a panoramic imaging slit to form the X-ray restricting unit 12 dedicated to panoramic imaging.

  In this embodiment, the restriction direction is the z direction, and the large irradiation field X-ray passage hole C1 (X1) of the horizontal displacement X-ray shielding plate XK1 using the peripheral shielding region P3 of the vertical displacement X-ray shielding plate XK2. The first X-ray irradiation range restriction process is performed by blocking a part of the line slit SL1) and restricting the subject irradiation X-ray passage area, but the horizontal displacement X-ray shielding plate XK1 and the vertical displacement X-ray are performed. The relationship with the shielding plate XK2 may be reversed.

  For example, assuming that the restriction direction is the x direction (the direction intersecting the y direction which is the X-ray irradiation direction), the vertical direction displacement X-ray shielding plate is used by using a part of the peripheral shielding region of the horizontal displacement X-ray shielding plate XK1. A mode in which a first X-ray irradiation range restriction process for blocking a part of the small irradiation field X-ray passage hole C3 of XK2 and restricting the subject irradiation X-ray passage region is also conceivable (in this aspect, for example, in the Z direction) It is possible to arbitrarily set the diameter of the CT imaging region as seen from Fig. 1. Even if the turning shaft 31 comes out of the center position of the CT imaging region, the drive unit 65 moves the turning shaft 31 around the axis of the turning arm 30. By moving in synchronization with the turn, the X-ray generator 11 and the X-ray detector 21 are controlled to perform the CT imaging while maintaining the center position of the X-ray detector 21 at the center position of the CT imaging region.

  In the first X-ray irradiation range restriction process shown in FIG. 7 (FIG. 8), the large irradiation field X-ray passage hole C1 (X-ray slit SL1) of the horizontal displacement X-ray shielding plate XK1 and the vertical displacement X-ray shielding. The small irradiation field X-ray passage hole C3 of the plate XK2 is not overlapped at all when viewed from the y direction. It is sufficient that this non-overlapping relationship is satisfied only on the X-ray irradiation path of the X-ray generator 11.

DESCRIPTION OF SYMBOLS 10 X-ray generation part 11 X-ray generator 12 X-ray control part 20 X-ray detection part 21 X-ray detector 30 Turning arm 40 Support frame 40M Lifting drive motor 41 Upper frame 42 Lower frame 65 Drive part 100 X-ray imaging apparatus 300 Supporting part 421 Subject fixing part 421A Chin rest part 801b Image information processing part C1 Large irradiation field X-ray passage hole C2 Medium irradiation field X-ray passage hole C3 Small irradiation field X-ray passage hole CB1, CB2, CB3 X-ray cone beam SL1 X-ray Slit SL2 X-ray slit OB Subject P3 Peripheral shielding area XK1 Horizontal displacement X-ray shielding plate XK2 Vertical displacement X-ray shielding plate

Claims (9)

An X-ray generator for emitting X-rays;
An X-ray detector including a plurality of detection elements that output signals according to the intensity of incident X-rays;
A support unit for supporting an X-ray generation unit including the X-ray generator and an X-ray detection unit including the X-ray detector;
A turning mechanism for turning the support portion around the subject so that the X-ray generator and the X-ray detector face each other across the subject including the head;
An image information processing unit that performs image processing on a signal output from the X-ray detector and generates an X-ray image;
With
The X-ray generator is
Including an X-ray irradiation restricting portion for restricting an irradiation range of X-rays irradiated from the X-ray generator on the X-ray emission direction side of the X-ray generator, including first and second X-ray shielding portions;
The first and second X-ray shielding portions are provided with first and second X-ray passage areas that allow passage of X-rays and first and second shielding areas that block passage of X-rays, respectively. ,
Setting a positional relationship in which X-rays emitted from the X-ray generator can pass through the first X-ray passage region or the second X-ray passage region ;
Without overlapping the wherein the first X-ray passing region second X-ray passage region on the illumination path prior Symbol X-ray, the first and the regulation direction intersecting the irradiation direction of the X-ray One of the two X-ray shielding portions is displaced relative to the other, and a part of the second X-ray shielding region and a part of the first X-ray passage region overlap, or the Subject irradiation X-ray passage region through which X-rays pass in the X-ray irradiation restricting unit by executing superposition of part of the first X-ray shielding region and part of the second X-ray passage region The first X-ray irradiation range restriction process for restricting can be realized,
X-ray imaging device.

The X-ray imaging apparatus according to claim 1,
When the axial direction of the pivot axis of the support portion is a vertical direction and the direction along the axial direction of the pivot axis is the height direction, the center position of the X-ray detection surface of the X-ray detector is X Arranged higher than the X-ray focal point, which is the X-ray generation point in the line generator,
The regulation direction includes the height direction,
In the first X-ray irradiation range restriction process, a part of the second X-ray shielding area of the second X-ray shielding part is superimposed on a part above the first X-ray passage area. Including a process of partially shielding by
X-ray imaging device. The X-ray imaging apparatus according to claim 1,
The X-ray generator is
A positional relationship in which X-rays emitted from the X-ray generator can pass through the first X-ray passage region is set, and the first X-ray passage region and the second X-ray passage on the X-ray irradiation path are set. A second X-ray irradiation range restriction process for restricting the first X-ray passage area as the subject irradiation X-ray passage area without overlapping the X-ray shielding area of
A positional relationship in which X-rays emitted from the X-ray generator can pass through the first and second X-ray passage areas is set, and the first X-ray passage area and the first X-ray passage area on the X-ray irradiation path Third X-ray irradiation that restricts an overlapping region of the first and second X-ray passage regions as the subject irradiation X-ray passage region by overlapping at least a part of the second X-ray passage region. Range regulation processing,
Is more feasible,
X-ray imaging device. The X-ray imaging apparatus according to any one of claims 1 to 3,
The first and second X-ray passage areas in the first and second X-ray shielding portions respectively emit X-rays emitted from the X-ray generator when passing through the subject irradiation X-ray passage area. Including an area that can be regulated to form an X-ray cone beam,
X-ray imaging device. The X-ray imaging apparatus according to claim 4,
In the regulation direction, the first X-ray passage region has a formation width wider than that of the second X-ray passage region,
X-ray imaging device. The X-ray imaging apparatus according to claim 3,
In the regulation direction, the first X-ray passage region has a wider formation width than the second X-ray passage region,
X-rays that have passed through the subject irradiation X-ray passage region when the second X-ray irradiation range restriction process is performed by the X-ray generation unit are substantially the same as the X-ray imaging region of the dental arch of the subject. X-ray cone beam
In the third X-ray irradiation range restriction process, the entire second X-ray passage area is overlapped with a part of the first X-ray passage area, and the second X-ray passage area is left as it is as the subject. Including the entire narrow formation width X-ray passage area use processing as the irradiation X-ray passage area,
X-rays that have passed through the subject irradiation X-ray passage region during execution of the processing for using the entire narrow formation width X-ray passage region by the X-ray generation unit are part of the teeth of the dental arch of the subject. Including an X-ray cone beam in which only the region containing the teeth is the X-ray imaging region,
X-ray imaging device. The X-ray imaging apparatus according to any one of claims 1 to 3,
The first and second X-ray passage areas in the first and second X-ray shielding portions respectively emit X-rays emitted from the X-ray generator when passing through the subject irradiation X-ray passage area. Including a slit-like region that can be regulated to form an X-ray slit beam;
X-ray imaging device. The X-ray imaging apparatus according to claim 7,
The X-ray image includes a panoramic tomographic image,
The image processing includes a process of generating a panoramic tomographic image by performing a process of superimposing overlapping portions of images along a tomographic plane corresponding to the dental arch of the subject.
X-ray imaging device. The X-ray imaging apparatus according to claim 2,
A subject holding unit for holding the subject at a predetermined holding position;
An elevating part capable of raising and lowering the support part along with the subject holding part along the height direction;
A subject holding unit lifting mechanism capable of raising and lowering the subject holding unit along the height direction;
X-ray characterized in that the subject holding unit elevating mechanism is configured such that the position of the subject holding unit in the height direction can be displaced so as to cancel the amount of elevation of the support unit by the elevating unit in the height direction. Shooting device.

Images