JP5863454B2 - X-ray CT imaging apparatus and X-ray CT imaging method - Google Patents

Description

  In the present invention, for example, an object is placed between an X-ray generator and an X-ray detector, and X-rays emitted from the X-ray generator are detected by the X-ray detector to perform X-ray CT imaging. The present invention relates to a CT imaging apparatus and an X-ray CT imaging method.

  Conventionally, in the medical field or the like, X-rays are used to irradiate an object with X-rays to collect projection data, and the obtained projection data is reconstructed on a computer to obtain a Computerized Tomography image (CT image tomographic plane). X-ray CT imaging for generating images, volume rendering images, and the like) is performed.

  In such X-ray CT imaging, X-ray generation is performed by rotating the X-ray generator and the X-ray detector around the subject while the subject is placed between the X-ray generator and the X-ray detector. The subject is irradiated with cone-shaped X-rays (X-ray cone beam). Then, X-ray detection results (projection data) are collected by the X-ray detector, and three-dimensional data is reconstructed based on the collected X-ray detection results (projection data). An apparatus for performing such X-ray CT imaging is disclosed in, for example, Patent Document 1.

An X-ray CT imaging apparatus described in Patent Document 1 displaces a pair of channel collimators in front of an X-ray generator during X-ray CT imaging, thereby obtaining a CT imaging region (field of
The view (FOV)) is assumed to be a circle or an ellipse, and only the region of interest of the patient as the subject can be X-ray CT-captured.

  However, since the actual region of interest is the whole or a part of the arch-shaped dental arch region, X-ray exposure is performed by irradiating X-rays to unnecessary portions in a circular or elliptical CT imaging region. There is a possibility that the amount increases unnecessarily, or conversely, the entire region of interest cannot be irradiated with X-rays.

JP-A-11-19078

  Therefore, the present invention appropriately irradiates the region of interest with an X-ray cone beam by setting an appropriate CT imaging region, thereby reducing the amount of wasted X-ray exposure and ensuring that the region of interest is X-ray CT. An object is to provide an X-ray CT imaging apparatus and an X-ray CT imaging method capable of imaging.

According to the present invention, an X-ray generator that generates X-rays, an X-ray restricting unit that controls an irradiation range of the X-rays generated from the X-ray generator to form an X-ray cone beam, and an object are irradiated. An X-ray detector that detects the X-ray cone beam, a support that supports the X-ray generator and the X-ray detector facing each other with the subject interposed therebetween, and at least the support is swiveled. A support driving unit that rotates around the axis of the axis and rotates the X-ray generator and the X-ray detector around the subject; and a CT imaging region is a longitudinal direction along the dental arch region. The X-ray restricting portion in the lateral direction orthogonal to the axial direction of the swivel axis according to the CT imaging region so as to be a substantially oval shape having a shape or a substantially triangular shape conforming to the shape of the dental arch region X-ray CT imaging provided with an X-ray restriction control unit that variably controls the restriction during imaging It is a shadow device or a CT imaging method.

The dental arch region may be a region surrounded by an arch-like curve drawn by the dental row, or a region including a jaw bone in which the dental row is set, and further, an upper jaw, a lower jaw, or , Can be a region in both of them.
The swivel axis may be a swivel axis that is fixed with respect to the photographing apparatus main body, or a swivel axis that is configured to be relatively movable in the lateral direction according to the swivel angle of the support.

  The substantially oval shape having the longitudinal direction along the dental arch region described above is substantially the length of the closed region having a curved portion along a range having at least a predetermined length in an arch-like (arch-shaped) dental row. Specifically, it is a circular shape, and can be a substantially oval shape that is configured by an outwardly convex curve or straight line.

  Further, the substantially triangular shape that conforms to the shape of the dental arch region described above is a shape in which at least one corner or side of the three corners is rounded by an outwardly convex arc, At least one corner or side of the portion may be shaped along at least a part of the arch-shaped dental arch region.

  The CT imaging region setting means can be constituted by an input means such as a mouse, a pointing device or a push button, or a touch panel constituting a display means for displaying a dental arch image.

  According to the present invention, by setting an appropriate CT imaging region, the region of interest is appropriately irradiated with an X-ray cone beam, reducing the amount of unnecessary X-ray exposure and ensuring X-ray CT imaging of the region of interest. can do.

For details, C T imaging region so as to be substantially oval or adapted substantially triangular in shape of the dental arch region having a longitudinal direction along the dental arch area, depending on the CT imaging area And an X-ray restriction control unit that variably controls the restriction of the X-ray restriction part in the lateral direction orthogonal to the axial direction of the pivot axis during photographing, so by setting an appropriate CT imaging region, The region of interest can be appropriately irradiated with an X-ray cone beam, and the region of interest can be reliably subjected to X-ray CT imaging. Moreover, since an X-ray cone beam is appropriately irradiated with respect to a region of interest, useless X-ray exposure can be reduced.

As an aspect of the present invention, a CT imaging region setting unit that accepts a CT imaging region setting operation for the dental arch region is provided, and the set CT imaging region is added to the dental arch image displayed on the display unit. The setting area image shown can be displayed in a superimposed manner.
According to the present invention, a CT imaging region can be set more appropriately for the dental arch region.

  Specifically, since the setting area image indicating the set CT imaging area is superimposed and displayed on the dental arch image displayed on the display means, the setting CT imaging area has an appropriate shape, size, and It can be visually confirmed that the position is set. Therefore, a CT imaging region can be set more appropriately for the dental arch region.

  If the display means for displaying the dental arch image, which is an image of the dental arch area, is configured to allow operation input such as a touch panel, the CT imaging area setting operation is directly performed on the displayed dental arch area. Therefore, the CT imaging region can be set more easily and appropriately.

  Further, as an aspect of the present invention, the CT imaging region setting means sets the positions of one end and the other end of the region of interest on the curved curve of the dental arch region shown in the dental arch image displayed on the display means. It can be configured to accept a designation operation to be designated.

According to the present invention, the CT imaging region can be appropriately set for the region of interest with a simpler operation.
For example, CT corresponding to a designation operation for presetting a CT imaging region by a combination of two teeth designated as a start point and an end point and designating the positions of one end and the other end of the region of interest among the set CT imaging regions An imaging region can be set as a set CT imaging region. Accordingly, the CT imaging region can be appropriately set for the region of interest with a simpler operation.

Further, as an aspect of the present invention, the dental arch image displayed on the display unit is divided into a plurality of divided areas, and the CT imaging region setting unit accepts a designation operation for selecting any of the divided areas. It can be configured.
According to the present invention, the CT imaging region can be appropriately set for the region of interest with a simpler operation.

  Specifically, dividing the dentition into a plurality of groups, setting divided areas, displaying the dental arch image displayed on the display means divided into a plurality of divided areas, or displaying the range of the divided areas in a superimposed manner Thus, as the CT imaging region setting means, a designation operation for selecting one of the displayed divided areas can be accepted, and the CT imaging region can be appropriately set for the region of interest with a simpler operation.

Further, as an aspect of the present invention, the dental arch image can be a panoramic image that has been photographed for the subject.
According to the present invention, for example, it is possible to set a CT imaging region for a region of interest while confirming a patient-specific state such as a tooth defect with a panoramic image. Therefore, it is possible to more appropriately irradiate the region of interest with the X-ray cone beam, and further reduce the amount of wasted X-ray exposure.

In an embodiment of the present invention, the axial direction of the pivot axis and the longitudinal direction, the front Symbol X-ray regulating portion, the CT imaging area the X-ray cone beam irradiation range of the longitudinal direction and the transverse direction with respect to It can be configured by X-ray shielding means that variably shields and regulates the shielding amount to at least one of them.
According to the present invention, a CT imaging region corresponding to the set CT imaging region can be more reliably formed. Therefore, it is possible to reliably reduce the wasteful X-ray exposure dose.

Further, as an aspect of the present invention, the X-ray shielding means is moved in the lateral direction, respectively, and a lateral restriction shielding composed of two X-ray shielding plates for regulating the lateral spread of the X-ray cone beam. Can be composed of a plate.
Each of the above-mentioned laterally restricting shielding plates made up of two X-ray shielding plates that move in the lateral direction and restrict the lateral spread of the X-ray cone beam is generated by an X-ray generator. Is a means for shielding at least one of the left and right in the horizontal direction in the irradiation range, and can be a means for shielding only the horizontal direction or the horizontal direction together with the vertical direction.

  According to the present invention, a CT imaging region corresponding to the set CT imaging region can be more reliably formed while controlling the irradiation direction in the lateral direction of the X-ray cone beam. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

Further, as an aspect of the present invention, the X-ray shielding means moves in the vertical direction, and the vertical direction restriction shield is composed of two X-ray shielding plates that regulate the spread of the X-ray cone beam in the vertical direction. A plate can be provided.
Each of the above-described longitudinal restriction shielding plates, which are two X-ray shielding plates that move in the longitudinal direction and restrict the spread of the X-ray cone beam in the longitudinal direction, is generated by an X-ray generator. Is a means for shielding at least one of the upper part and the lower part in the vertical direction in the irradiation range, and can be a means for shielding only the vertical direction or the vertical direction together with the horizontal direction.

  According to the present invention, a CT imaging region corresponding to the set CT imaging region can be more reliably formed while controlling the irradiation direction in the vertical direction of the X-ray cone beam. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

  Further, as an aspect of the present invention, the vertical irradiation position adjustment for adjusting the vertical irradiation direction of the X-ray cone beam by adjusting the vertical position of the vertical restriction shielding plate with respect to the X-ray generator. Means may be provided.

  According to the present invention, for example, a local region of interest that is decentered in the vertical direction with respect to the X-rays emitted from the X-ray generator, such as only the upper jaw or only the lower jaw, is set as the set CT imaging region. However, a CT imaging region corresponding to the set CT imaging region can be more reliably formed. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

  Further, as an aspect of the present invention, a support body holding means for suspending and holding the swivel shaft, wherein the axial direction of the swivel axis is a vertical direction, a direction orthogonal to the vertical direction is a horizontal direction, and the support body holding The support drive unit comprising a two-dimensional movement mechanism that relatively moves the swivel axis in a two-dimensional direction in the horizontal direction with respect to the means. Alternatively, as an aspect of the present invention, the axial direction of the pivot axis is the vertical direction, the direction orthogonal to the vertical direction is the horizontal direction, and the subject holding means for holding the subject, and the pivot axis, And the support driving unit including a two-dimensional movement mechanism that relatively moves the subject holding unit in a two-dimensional direction in the horizontal direction.

  According to the present invention, it is possible to adjust the spread of the X-ray cone beam more appropriately with respect to the set CT imaging region even if it is the set CT imaging region that is eccentric from the center of the dental arch region.

  Further, as an aspect of the present invention, the support is made so that a trajectory of the slit-shaped X-ray slit beam extending in the vertical direction formed by the restriction of the X-ray shielding means forms an envelope in panoramic X-ray photography. A drive control unit that drives and controls the body drive unit can be provided.

  According to the present invention, when a panoramic image is required, a panoramic X can be obtained with an X-ray slit beam by an X-ray CT imaging apparatus capable of reducing a useless X-ray exposure without preparing another X-ray imaging apparatus. Line photography is also possible. Therefore, the versatility of the X-ray CT imaging apparatus that can reduce the wasteful X-ray exposure can be improved.

As an aspect of the present invention, the CT imaging region when the X-ray restriction control unit is viewed from the axial direction of the pivot axis has a substantially oval shape whose longitudinal direction is along the longitudinal direction of the dental arch region. Alternatively configured to control the X-ray restriction portion, the CT imaging area as viewed from the axial direction of the pivot axis, the top portion is located in front teeth near, substantially elliptic shape connecting the outer circumference of the dental arch region or It can be set as the structure which controls the said X-ray control part so that it may become a substantially triangular shape.

  The oval shape is a closed convex shape formed on a smooth, smooth curve and having at least one line-symmetrical portion, for example, an ellipse, two equal lengths. An oval rounded rectangle formed of parallel lines and two semicircles, a quadrangle whose corners are chamfered in an arc shape, or an oval shape can be used. However, the substantially oval shape is a concept including a shape that approximates a shape having at least one line-symmetric part.

And position the top to the front teeth near the substantially elliptic shape or a substantially triangular shape connecting the outer circumference of the dental arch region has a base along a convex substantially elliptic shape or a substantially triangular shape or front teeth toward the front teeth a substantially elliptic shape or form substantially triangular, the corner portion is chamfered in an arc, substantially triangular circular constituting the side portions in the curve, the three least one corner or side of the corner outward convex It is a concept including a substantially triangular shape that is rounded by an arc.

According to the present invention, by controlling the X-ray restricting portion, the longitudinal direction is substantially oval shape along the longitudinal direction of the dental arch region or the apex is located in the vicinity of the front teeth according to the shape of the set CT imaging region. and, by narrowed down to substantially elliptic shape or form substantially triangular connecting an outer periphery of the dental arch region, it is possible to reduce unnecessary exposure to the X-ray amount, it is possible to reduce the detection range of the X-ray detector.

Further, as an aspect of the present invention, the CT imaging region of the X-ray restriction control unit viewed from the axial direction of the pivot axis has a perfect circle shape in addition to at least one of the substantially oval shape and the substantially triangular shape. It can be set as the structure which controls the said X-ray control part so that it may become.
The perfect circle shape may be configured so that a perfect circle shape having a plurality of diameters can be selected, and further includes a substantially perfect circle shape whose radius slightly changes in the circumferential direction.

  According to the present invention, an appropriate CT imaging region can be set according to a part or a case, and a useless X-ray exposure dose can be reduced. Specifically, for example, when observing whether the wisdom teeth are close to lying down in the buried wisdom area, if you want to examine the status of tumor spread, or not only the longitudinal part of the dental arch area, The CT imaging area is configured to be selectable from a substantially oval shape, a substantially triangular shape, and a perfect circle shape according to various cases and parts such as diagnosis that require observation of the region extending on the lingual side and cheek side. As a result, it is possible to reduce the amount of wasted X-ray exposure that is irradiated to places other than the region of interest. Therefore, the versatility of the X-ray CT imaging apparatus that can reduce the wasteful X-ray exposure can be improved.

  According to the present invention, by setting an appropriate CT imaging region, the region of interest is appropriately irradiated with an X-ray cone beam, reducing the amount of unnecessary X-ray exposure and ensuring X-ray CT imaging of the region of interest. An X-ray CT imaging apparatus and an X-ray CT imaging method that can be provided can be provided.

1 is a schematic perspective view of an X-ray imaging apparatus. The partial front view of the X-ray imaging apparatus which mounted | wore with the cephalostat. 1 is a block diagram showing a configuration of an X-ray imaging apparatus. The schematic perspective view of a beam shaping mechanism. Explanatory drawing by the schematic perspective view of the X-ray generation part of the state which irradiated the X-ray cone beam in which the irradiation range was controlled. Explanatory drawing about position adjustment of a vertical direction shielding board and a horizontal direction shielding board. Explanatory drawing about position adjustment of the vertical direction shielding board and horizontal direction shielding board in another embodiment. Schematic of a setting screen for setting an oval CT imaging region. The schematic plan view which shows the locus | trajectory of X-ray CT imaging for the right dentition imaging object as an ellipse CT imaging region. Explanatory drawing about the mode of X-ray CT imaging | photography which image | photographs a right dentition imaging | photography object as an ellipse CT imaging area | region. Explanatory drawing about the mode of X-ray CT imaging | photography which image | photographs a right dentition imaging | photography object as an ellipse CT imaging area | region. The schematic plan view which shows the locus | trajectory of X-ray CT imaging which image | photographs a right dentition imaging | photography object as an ellipse CT imaging area | region. Explanatory drawing about the X-ray cone beam by which the vertical direction irradiation range with respect to the imaging | photography target object was controlled. Schematic of the setting screen of another embodiment which sets an oval CT imaging region. Schematic of the setting screen of another embodiment which sets an oval CT imaging region. Schematic of the setting screen of another embodiment which sets an oval CT imaging region. Schematic of the setting screen of another embodiment which sets an oval CT imaging region. FIG. 3 is a schematic plan view showing a trajectory of X-ray CT imaging for imaging an imaging object as an elliptic CT imaging region. Explanatory drawing about the shape of CT imaging area. The schematic plan view which shows the locus | trajectory of X-ray CT imaging which image | photographs a local imaging | photography object as a perfect circular CT imaging area | region. Schematic of the setting screen which sets a local imaging | photography object as a perfect circular CT imaging area | region. FIG. 3 is a schematic plan view showing a trajectory for panoramic shooting of a shooting target object. Explanatory drawing about the internal structure of the turning arm and upper frame for moving a turning axis. The block diagram which shows the structure of the X-ray imaging apparatus which moves the turning axis | shaft and regulates the breadth of an X-ray cone beam. The schematic plan view of another embodiment which shows the locus | trajectory which carries out panoramic imaging of the imaging | photography target object. The top view which compares and shows the case where CT imaging area | region is made into the conventional perfect circular CT imaging area | region, and the case where it is set as a substantially triangular CT imaging area | region. Explanatory drawing in the case of the conventional CT imaging | photography which made the CT imaging | photography area | region into the perfect circular CT imaging area | region.

Hereinafter, an X-ray CT imaging apparatus 1 according to the present invention will be described with reference to FIGS.
1 shows a schematic perspective view of the X-ray CT imaging apparatus 1, FIG. 2 shows a partial front view of the X-ray CT imaging apparatus 1 equipped with a cephalostat 43, and FIG. 3 shows the X-ray CT imaging apparatus 1. FIG. 4 is a schematic perspective view of the beam forming mechanism 13.

  FIG. 5 is a schematic perspective view of the X-ray generation unit 10 irradiated with an X-ray cone beam BX whose irradiation range is restricted, and FIGS. 6 and 7 illustrate the vertical shielding plate 14 and the horizontal shielding. The explanatory view about position adjustment of board 15 is shown.

  Specifically, FIG. 5A shows a schematic perspective view of the X-ray generation unit 10 in a state where the X-ray cone beam BX1 for the large irradiation field CT for the large irradiation field CT is irradiated, and FIG. The schematic perspective view of the X-ray generation part 10 of the state irradiated with the X-ray cone beam BX2 for small irradiation field CT for field CT is shown.

  FIG. 6A shows a front view of the position adjustment of the vertical shielding plate 14 and the horizontal shielding plate 15 when the irradiation range of the X-ray cone beam BX is restricted for the large irradiation field CT. FIG. 6B is a front view of the position adjustment of the vertical direction shielding plate 14 and the horizontal direction shielding plate 15 when the irradiation range of the X-ray cone beam BX is restricted to the small irradiation field CT, and FIG. The front view about the position adjustment of the vertical direction shielding board 14 and the horizontal direction shielding board 15 in the case of restrict | limiting the irradiation range of X-rays as X-ray slit beam BXP for panoramic imaging is shown. 7A, 7 </ b> B, and 7 </ b> C show cases where the same state as that in FIGS. 6A, 6 </ b> B, and 6 </ b> C is implemented by the L-shaped shielding plate 18.

  The X-ray CT imaging apparatus 1 sets an ellipse-like ellipsoidal CT imaging area CAa for a region of interest, an operation display unit 61 that functions as a display unit, and an oval shape set by the operation display unit 61. X-ray CT imaging is performed on the CT imaging area CAa, and the main body unit 2 that collects projection data and the information processing apparatus 8 that processes the projection data collected in the main body unit 2 to generate various images. Broadly divided.

The control unit 60 of the main body unit 2, the control unit of the information processing apparatus 8, and the arithmetic processing unit 801b (see FIG. 3) execute X-ray imaging in accordance with an X-ray imaging program IMP (not shown) including X-ray CT imaging. .
The program IMP proceeds through the image display step s100, the superimposed display step s110, the setting operation reception step s120, and the X-ray restriction step s130 in this order.

  The main body 2 accommodated in the hollow vertical rectangular parallelepiped X-ray chamber 70, the operation display unit 61 mounted on the wall surface of the X-ray chamber 70, and the outside of the X-ray chamber 70 are disposed. The information processing apparatus 8 is connected to each other by a connection cable 83.

  The main body 2 includes an X-ray generation unit 10 that emits an X-ray cone beam BX and an X-ray slit beam BXP that are configured by a bundle of X-rays toward the subject M1, and an X-ray emitted by the X-ray generation unit 10. The X-ray detection unit 20 for detecting the X-ray, the swing arm 30 as a support for supporting the X-ray generation unit 10 and the X-ray detection unit 20 respectively, the support column 50 extending in the vertical direction, and the swing arm 30 are suspended. The elevating unit 40 is movable up and down in the vertical direction with respect to the support column 50, and the main body control unit 60. Note that the X-ray generation unit 10, the X-ray detection unit 20, and the beam shaping mechanism 13 disposed on the X-ray detection unit 20 side of the X-ray generation unit 10 are used as the imaging mechanism 3.

  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 elevating unit 40 via a turning shaft 31 extending in the vertical direction.

  The swivel arm 30 has a substantially inverted U shape when viewed from the front, and swivels about a swivel shaft 31 provided at the upper end portion as a swivel center Sc. In the present embodiment, the turning center Sc is a fixed position with respect to the upper frame 41. In addition, the X-ray generation unit 10 and the X-ray detection unit 20 are attached to both ends of the revolving arm 30 that has a substantially inverted U shape when viewed from the front. The shape of the swivel arm 30 is not limited to this. For example, the X-ray generation unit 10 and the X-ray detection unit 20 are supported so as to face each other on a member that rotates around the center of the annular portion. May be.

  Here, in the following, the direction parallel to the axial direction of the turning shaft 31 (here, the vertical direction, that is, the vertical direction) is referred to as “Z-axis direction”, and the direction intersecting the Z-axis is referred to as “X-axis direction”. Further, a direction intersecting the X-axis direction and the Z-axis direction is defined as “Y-axis direction”. Although the X-axis and Y-axis directions can be arbitrarily determined, here the left and right sides of the subject when the subject who is the subject M1 is positioned in the X-ray CT imaging apparatus 1 and directly faces the column 50 are shown. The direction is defined as the X-axis direction, 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 the 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 the horizontal direction.

  On the other hand, for the three-dimensional coordinates on the turning arm 30 that turns, the direction in which the X-ray generation unit 10 and the X-ray detection unit 20 face each other is “y-axis direction”, and the horizontal direction is orthogonal to the y-axis direction. Is the “x-axis direction”, and the vertical direction perpendicular to the x- and y-axis directions is the “z-axis direction”. In the present embodiment and subsequent embodiments, the Z-axis direction is the same direction as the z-axis direction. Moreover, the turning arm 30 of this embodiment turns around the turning axis 31 extending in the vertical direction as a rotation axis. Therefore, the xyz orthogonal coordinate system rotates around the Z axis (= z axis) with respect to the XYZ orthogonal coordinate system.

  Further, when the X-ray generator 10 and the X-ray detector 20 shown in FIG. 1 are viewed from above, the direction from the X-ray generator 10 to the X-ray detector 20 is defined as the (+ y) direction, and this (+ y) The horizontal right-hand direction orthogonal to the direction (the front side of the illustrated subject M1 in the direction of the illustrated turning arm 30) is defined as the (+ x) direction, and the upward upward direction is defined as the (+ z) direction.

The raising / lowering part 40 is comprised by the upper frame 41 and the lower frame 42, and is a structure which protrudes on the opposite side to the side engaged with the support | pillar 50 standingly arranged along the perpendicular direction, ie, a front side.
The upper frame 41 functioning as a support holding means is attached with the pivot shaft 31 of the pivot arm 30, and the pivot unit 40 moves vertically along the support column 50, thereby moving the pivot arm 30 up and down. can do.

  The upper frame 41 is provided with a turning motor 37 (corresponding to the support driving unit) for turning the turning arm 30 around the turning shaft 31, and is composed of a belt, a pulley, a rotating shaft, and the like. Is transmitted to the turning arm 30 by a transmission mechanism (not shown) passing through the turning arm 30, and the turning arm 30 is turned. In the present embodiment, the turning shaft 31 is configured to extend along the vertical direction, but the turning shaft may be inclined at an arbitrary angle with respect to the vertical direction.

  Further, a bearing 38 (see FIG. 23) is interposed between the turning shaft 31 and the turning arm 30 so that the turning arm 30 rotates smoothly with respect to the turning shaft 31.

Note that the transmission mechanism and the turning motor 37 (see FIG. 23) including the turning shaft 31, the bearing 38, the belt, the pulley, and the rotating shaft are examples of the turning mechanism for turning the turning arm 30, and in the above-described turning mechanism, Although the revolving arm 30 revolves around the revolving shaft 31 that does not rotate, the present invention is not limited to such a structure.
For example, the turning arm 30 may be turned by rotating the turning shaft 31 fixed to the turning arm 30 with respect to the upper frame 41.

  The lower frame 42 is provided with a subject fixing portion 421 composed of an ear rod that fixes the subject M1 (here, the human head) from the left and right, a chin rest that fixes the chin, and the like.

  The swivel arm 30 is moved up and down in accordance with the height of the subject M1 as the elevating unit 40 is raised and lowered to an appropriate position, and the subject M1 is fixed to the subject fixing unit 421 in this state. In the example shown in FIG. 1, the subject fixing unit 421 fixes the subject M1 so that the body axis of the subject M1 is substantially the same as the axial direction of the turning shaft 31.

  The main body control unit 60 that functions as an X-ray restriction control unit and a drive control unit is a control unit that controls the operation of each component of the main body unit 2, and is disposed inside the X-ray detection unit 20 as shown in FIG. Has been.

  Further, on the outside of the main body control unit 60, that is, on the back side of the X-ray detection unit 20 where the X-ray detector 21 is installed, a touch panel that displays buttons and various information for inputting various commands. The operation display part 62 comprised by is attached.

  On the outside of the wall of the X-ray room 70 that accommodates the main body 2, an operation configured with buttons for inputting various commands and a touch panel for displaying various information based on the control from the main body control unit 60. A display unit 61 is attached.

Note that the operator (surgeon) may operate the main body unit 2 using the operation display unit 62 or may operate the main body unit 2 using the operation display unit 61.
Furthermore, the operation display unit 62 and the operation display unit 61 may be configured to share the operations and displays performed, or some or all of the operations and displays performed by the operation display unit 62 and the operation display unit 61 may be performed. It may be common.

  Furthermore, for example, when the X-ray chamber 70 is not provided, one of the operation display unit 62 and the operation display unit 61 may be omitted so that the operation display unit 61 is omitted. In the following, the display and operation by the operation display unit 61 will be described, but the display and operation by the operation display unit 62 may be replaced.

  The operation display unit 61 is also used for designating the position of an imaging region such as a living organ. In addition, there are various modes for X-ray imaging, but the mode may be selected by operating the operation display unit 61.

  Specifically, the operation display unit 61 displays a CT imaging region setting screen 200 for setting an oval CT imaging region CAa as shown in FIG. When displaying on the operation display unit 62, a CT imaging region setting screen 202 similar to the CT imaging region setting screen 200 is displayed on the operation display unit 62.

  The CT imaging region setting screen 200 functioning as a CT imaging region setting unit includes an image display unit 210 that displays a dental arch image 211, an upper and lower jaw selection unit 220, a selection range setting unit 230, and a condition setting unit 240. It is composed. The CT imaging region setting screen 200 in FIG. 8 is a length for setting an elliptical oval CT imaging region CAa along the arch-shaped curve constituting the dental arch with respect to the dental arch region X. This is a circular mode setting screen.

  For the displayed dental arch image 211 (image display step s100), the image display unit 210 designates a designation cursor (pointer) 212 that designates the center in the longitudinal direction of the set oval CT imaging area CAa, and a designation. A setting area indicating the set CT imaging area, which is an oval shape corresponding to the number of teeth surrounded by the oval CT imaging area CAa specified by the selection range setting unit 230 described later with respect to the center specified by the cursor 212 The CT imaging region line 213 that is an image is superimposed and displayed (superimposition display step s110).

  Strictly speaking, it can be considered that the set CT imaging area on the display indicated by the CT imaging area line 213 (in the above case, the oval CT imaging area CAa) and the actual CT imaging area in the three-dimensional space are distinguished. . However, in the embodiment shown in FIGS. 8 and 14, the set CT imaging region on the display and the CT imaging region in the actual three-dimensional space are preferably set so as to coincide with each other. However, it may be configured such that the set CT imaging area on the display is displayed by slightly modifying the CT imaging area in the actual three-dimensional space so that the operator (operator) can easily recognize it.

  The upper and lower jaw selection unit 220 includes an UPPER button 221 for setting the oval CT imaging area CAa to the upper jaw, a FULL button 222 for setting both the upper jaw and the lower jaw, and a LOWER button 223 for setting the lower jaw. .

  The selection range setting unit 230 includes a slide setting unit 231 configured with a scale 231a in which the number of teeth is set at equal intervals and a slider 231b that slides so that a desired number can be specified with respect to the scale 231a.

The condition setting unit 240 includes a Set button 241, a Reset button 242, a Start button 243, a Mode button 244, and a Return button 245.
The Set button 241 is an operation button for confirming the designated content of the oval CT imaging area CAa set by the image display unit 210, the upper and lower jaw selection unit 220, and the selection range setting unit 230 (executes the setting operation reception step s120). It is.
The Reset button 242 is an operation button for resetting the designated content of the oval CT imaging area CAa set by the image display unit 210, the upper and lower jaw selection unit 220, and the selection range setting unit 230.

The Start button 243 is an operation button for instructing start of X-ray CT imaging of the oval CT imaging area CAa based on the designation content determined by the Set button 241.
The Mode button 244 is a button for selecting various modes, and local imaging in the dental arch region X is performed from an oval mode in which an oval CT imaging region CAa including a plurality of teeth is set. This is an operation button for switching between a perfect circle mode in which a perfect circle CT imaging area CAd is set for a target. If the apparatus is capable of panoramic photography, the mode button 244 can be used to select the panoramic mode.
The panoramic imaging indicates panoramic X-ray imaging, and the panoramic image is a panoramic X-ray image.

The Return button 245 is an operation button for returning to an initial screen (not shown).
In the above description, the operation display unit 61 is configured with a touch panel, and the setting operation of the ellipse CT imaging area CAa by the operation of the designation cursor 212 displayed on the CT imaging area setting screen 200 is accepted. The unit 61 may be configured with a liquid crystal screen, and the setting operation of the CT imaging area CA may be received by a mouse, a pointing device, or an operation button arranged in the vicinity of the operation display unit 61.

  In the above description, the CT imaging region setting screen 200 is displayed on the operation display unit 61 and the setting operation of the CT imaging region CA is accepted. However, the CT imaging region setting screen 200 is displayed on the information processing apparatus 8 described later. It may be displayed on the display unit 81 and a setting operation for the CT imaging area CA may be accepted.

  The information processing apparatus 8 includes an information processing main body 80, 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. Can input 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.

  The information processing main body 80 is configured by, for example, a computer, a workstation, and the like, and can transmit and receive various data to and from the main body 2 through a connection cable 83 that is a communication cable. However, data may be transmitted and received between the main body 2 and the information processing apparatus 8 by wireless communication.

  The information processing device 8 is a processing device that processes the projection data acquired by the main body unit 2 to reconstruct three-dimensional data (volume data) expressed by voxels. A plane can be set and a tomographic image of that specific plane can be reconstructed.

  As shown in FIG. 2, a cephalostat 43 may be attached to the X-ray CT imaging apparatus 1. Specifically, the cephalostat 43 is attached to an arm 501 extending in the horizontal direction from the middle of the elevating unit 40, for example. 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.

  Next, the beam shaping mechanism 13 that shields and regulates the irradiation range of the X-rays generated by the X-ray generation unit 10 and forms the X-ray cone beam BX that spreads in a truncated pyramid shape toward the X-ray detection unit 20 is shown in FIG. This will be described with reference to FIGS.

  The X-ray generation unit 10 disposed opposite to the X-ray detection unit 20 in the swivel arm 30 includes an X-ray generator 10 a in which an X-ray tube is accommodated in a housing 11. The front surface of the housing 11 is provided with an exit port 12 that allows transmission of X-rays generated by the X-ray tube. A beam shaping mechanism 13 is disposed in front of the emission port 12 (on the near side in FIG. 4 and in the y-axis direction with respect to the X-ray generation unit 10).

  The beam shaping mechanism 13 that functions as an X-ray restricting unit includes a longitudinal shielding plate 14 (14a, 14b) that shields the longitudinal direction (z direction) in the X-ray irradiation range, and a lateral that shields the lateral direction (x direction). The direction shielding plate 15 (15a, 15b) and the shielding plate moving mechanism 16 (16a, 16b) for moving the vertical direction shielding plate 14 and the horizontal direction shielding plate 15 are configured.

  The vertical shielding plate 14 includes a horizontally long plate-like upper vertical shielding plate 14 a and a lower vertical shielding plate 14 b which are arranged on the upper and lower sides of the emission port 12 in front view. In addition, the horizontal shielding plate 15 includes a left-side horizontal shielding plate 15a and a right-side horizontal shielding plate 15b that are vertically long plates disposed on the left and right sides of the emission port 12 when viewed from the front. As shown in FIG. 4, the horizontal shielding plate 15 is arranged closer to the X-ray generation unit 10 than the vertical shielding plate 14, but the vertical shielding plate 14 is arranged closer to the X-ray generation unit than the horizontal shielding plate 15. You may arrange | position to 10 side.

  The shielding plate moving mechanism 16 includes a shielding plate longitudinal movement mechanism 16a that moves the two vertical shielding plates 14 in the vertical direction, and a shielding plate lateral direction that moves the two horizontal shielding plates 15 in the horizontal direction. There is a moving mechanism 16b.

  The shield plate vertical movement mechanism 16a is configured to position a vertical screw shaft 161a that is screwed into a screw groove 141 (guided member having a female screw inside) provided in the vertical direction with respect to the vertical shield plate 14. The vertical shielding plate 14 is moved in the vertical direction by rotating at 162a (162). Since the shielding plate vertical movement mechanism 16a is disposed above the upper vertical shielding plate 14a and below the lower vertical shielding plate 14b, the upper vertical shielding plate 14a and the lower It can move in the vertical direction independently of the side vertical shielding plate 14b.

  Specifically, there are two vertical screw shafts 161a independently on the upper and lower sides, one on the upper side is screwed into the screw groove 141 of the upper vertical shielding plate 14a, and one on the lower side is the lower vertical shielding plate. It is screwed into the screw groove 141 of 14b.

Further, the shielding plate longitudinal movement mechanism 16a is arranged laterally shifted with respect to the horizontally long plate-like longitudinal shielding plate 14, and the tilt regulating hole 142 (the longitudinal through hole is passed through the inside) on the opposite side in the lateral direction. Guide member) and a tilt regulating shaft 143 that passes through the tilt regulating holes 142 of both the upper vertical shielding plate 14a and the lower vertical shielding plate 14b, so that the vertical shielding plate 14 does not tilt. The shield plate can be moved in the vertical direction by the vertical movement mechanism 16a.
The shielding plate vertical direction moving mechanism 16a can function as a vertical direction irradiation position adjusting unit that controls the irradiation direction in the vertical direction of the X-ray cone beam BX.

  The shielding plate lateral movement mechanism 16b is configured to adjust the position of the lateral screw shaft 161b screwed into a thread groove 161 (guided member having a female screw inside) provided in the transverse direction with respect to the lateral shielding plate 15. The horizontal shielding plate 15 is moved in the horizontal direction by rotating at 162b (162). The shielding plate lateral movement mechanism 16b is disposed on the left side with respect to the left lateral shielding plate 15a and on the right side with respect to the right lateral shielding plate 15b. It can move laterally independently from the direction shielding plate 15b.

  Specifically, there are two longitudinal screw shafts 161b independently on the left and right sides, one on the left side is screwed into the screw groove 161 on the left side horizontal shielding plate 15a, and one on the right side is on the right side horizontal shielding plate 15b. Screwed into the thread groove 161.

  Further, the shield plate lateral movement mechanism 16b is arranged to be shifted in the vertical direction with respect to the vertically long plate-like lateral shield plate 15, and is provided with an inclination regulating hole 152 on the opposite side in the vertical direction. Since the tilt regulating shaft 153 is inserted through both the tilt regulating holes 152 of the lateral shielding plate 15b (guided member having a lateral through hole therein), the shielding plate moving mechanism 16 is not tilted. The shield plate can be moved in the horizontal direction by the horizontal movement mechanism 16b.

  As described above, the beam shaping mechanism 13 includes the vertical shielding plate 14, the lateral shielding plate 15, and the shielding plate moving mechanism 16, and is arranged in front of the emission port 12 in the X-ray generation unit 10 to generate X-rays. The X-ray irradiation range generated by the unit 10 can be shielded and restricted, and the X-ray cone beam BX spreading in a truncated pyramid shape toward the X-ray detection unit 20 can be formed.

  Specifically, the distance between the opposing edge portions 14c of the upper vertical shielding plate 14a and the lower vertical shielding plate 14b is adjusted by the shielding plate vertical movement mechanism 16a, and the left lateral shielding plate 15a and the right lateral shielding plate are adjusted. By adjusting the interval between the opposing edge portions 15c with respect to 15b by the shielding plate lateral movement mechanism 16b, the opposing edge portion 14c and the left lateral shielding plate between the upper vertical shielding plate 14a and the lower vertical shielding plate 14b. An opening 17 having a rectangular shape in front view for forming an X-ray cone beam BX having a desired shape can be formed by the opposing edge 15c between the 15a and the right lateral shielding plate 15b.

  More specifically, as shown in FIGS. 5 (a) and 6 (a), the interval between the opposing edges 14c in the upper vertical shielding plate 14a and the lower vertical shielding plate 14b is widely adjusted. The opening 17 becomes a large irradiation field opening 17a having a large square shape when viewed from the front by adjusting the distance between the opposing edge portions 15c in the left lateral shielding plate 15a and the right lateral shielding plate 15b. The X-ray transmitted through the aperture 17a has a large square cross section, and can be irradiated with a large irradiation field X-ray cone beam BX1 extending in a truncated pyramid shape toward the X-ray detection unit 20.

  On the other hand, as shown in FIG. 5B and FIG. 6B, the interval between the opposing edge portions 14c in the upper vertical shielding plate 14a and the lower vertical shielding plate 14b is adjusted narrowly, and the left side By adjusting the distance between the opposing edge portions 15c of the horizontal direction shielding plate 15a and the right side direction shielding plate 15b to be narrow, the opening 17 becomes a small irradiation field opening 17b having a small square shape when viewed from the front. The X-ray that has passed through 17b has a small square cross section, and can be irradiated with the X-ray cone beam BX2 for a small irradiation field that spreads in a truncated pyramid shape toward the X-ray detection unit 20.

  Further, as shown in FIG. 6 (c), the interval between the opposing edge portions 14c in the upper vertical shielding plate 14a and the lower vertical shielding plate 14b is adjusted to be wide so that the left lateral shielding plate 15a and the right lateral shield are arranged. By adjusting the distance between the opposing edge portions 15c with the direction shielding plate 15b to be narrow, the opening 17 becomes a rectangular panoramic photographing opening 17c that is vertically long when viewed from the front, and the X-ray transmitted through the panoramic photographing opening 17c has a cross section. The X-ray slit beam BXP (see FIG. 22) that is a vertically long rectangle in front view, extends vertically in a slit shape, and spreads in a vertically long truncated pyramid shape toward the X-ray detection unit 20 can be irradiated.

  The beam forming mechanism 13 has two openings 17 for irradiating a desired X-ray cone beam BX by moving two vertical shielding plates 14 and two horizontal shielding plates 15 respectively by a shielding plate moving mechanism 16. For example, as shown in FIG. 7, two L-shaped shielding plates 18 that are L-shaped in front view are arranged symmetrically with respect to the center of the opening 17, and the inner corners of the L-shaped shielding plate 18 are arranged. The opening 17 can be constituted by the edge portions 18a to be constituted.

  In this case, each L-type shielding plate 18 is provided with both a shielding plate longitudinal direction moving mechanism 16a and a shielding plate lateral direction moving mechanism 16b, and each L-type shielding plate 18 is moved in the longitudinal direction and the lateral direction so that the openings 17 are formed. The shape can be adjusted.

For example, a vertical movement mechanism similar to the shielding plate vertical movement mechanism 16a is provided on a base (not shown) that is displaced in the horizontal direction by a horizontal movement mechanism similar to the shielding plate horizontal movement mechanism 16b. Thus, one L-shaped shielding plate 18 is displaced in the vertical direction.
The shielding plate moving mechanism 16 can be configured by combining two sets of these lateral movement mechanism, base, vertical movement mechanism, and L-shaped shielding plate 18.

  The X-ray detector 20 disposed on the swivel arm 30 so as to face the X-ray generator 10 constitutes a main part by an X-ray detector 21 having a detection surface 21 ′ for detecting X-rays, and is reliably detected. An X-ray cone beam BX can be projected onto the surface.

  As shown in FIG. 3, the X-ray CT imaging apparatus 1 configured as described above may be on the side of the turning arm 30 as shown in FIG. The X-ray generation unit 10 and the X-ray detection unit 20 are connected to the main body control unit 60 and are driven according to a predetermined program, as described above. X-ray CT imaging can be appropriately performed on the oval CT imaging area CAa set for the imaging object. Hereinafter, an aspect in which the right dentition object OB1 is X-ray CT imaged by the X-ray CT imaging apparatus 1 will be described.

  In the following description, anterior tooth T1 including anterior teeth, a left molar tooth T2 including a left molar, and a right molar tooth T3 including a right molar (hereinafter, anterior tooth T1, left molar T2 and right molar T3). The range from the anterior teeth T1 to the right molars T3 in the upper dental arch constituted by the right dent imaging object OB1. Then, in order to perform X-ray CT imaging of the right dentition imaging object OB1 in the upper jaw, the right dentition imaging object OB1 (the range surrounded by the CT imaging region line 213 in FIG. 8) is taken from the axial direction of the turning shaft 31. A case where X-ray CT imaging is performed as an elliptical CT imaging area CAa having a long cylindrical shape along the right curve in the dental arch area X will be described.

  In FIG. 8 and the like, a mandible having a mandibular head is illustrated, but even when a CT imaging area CA is set for the upper jaw, the position of a tooth or the like can be determined by illustrating the shape of the mandible. Since it is possible to grasp, only the mandible is displayed without separating the mandible and the maxilla, and when the CT imaging area CA is set for the maxilla and when the CT imaging area CA is set for the mandible Each jawbone may be displayed on the operation display unit 61.

  First, in order to perform X-ray CT imaging of the right dentition imaging object OB1, a CT imaging area line 213 including the right dentition imaging object OB1 is displayed on the CT imaging area setting screen 200 displayed on the operation display unit 61. Set.

  Specifically, the right dentition object OB1 is selected by various buttons of the upper and lower jaw selection unit 220 according to one or both of the upper and lower foreheads. In FIG. 8, even when the UPPER button 221 is pressed by the upper and lower jaw selection unit 220 and the upper jaw is selected, the dental arch image 211 of the lower jaw having the jawbone head is displayed on the image display unit 210. However, the dental arch image 211 of the selected jaw bone may be switched and displayed by a selection operation in the upper and lower jaw selector 220.

  Next, with respect to the dental arch image 211 displayed on the image display unit 210 of the CT imaging area setting screen 200, the designation cursor 212 designates the center in the longitudinal direction in the oval CT imaging area CAa, and the selection range. The slider 231b in the setting unit 230 is slid to set the number of teeth included in the oval CT imaging area CAa.

  When the number of teeth specified by the slide setting unit 231 is an odd number, the center cursor in the longitudinal direction is designated by the designation cursor 212 as the center in the longitudinal direction in the oval CT imaging area CAa.

  Specifically, in the case where there are teeth TH1, TH2, and TH3, if the tooth TH2 is the center tooth in the longitudinal direction and the teeth TH1, TH2, and TH3 are CT imaging targets, the designated cursor is used. The tooth TH2 is designated at 212, and the number of three teeth is designated by the slide setting unit 231, and an oval CT imaging area CAa is set for the teeth TH1, TH2, TH3.

  When the number of teeth specified by the slide setting unit 231 is an even number, the specified cursor 212 is used as a center in the longitudinal direction of the oval CT imaging area CAa between two teeth near the center in the longitudinal direction. It will be specified.

  Specifically, there are teeth arranged as teeth TH1, TH2, TH3, TH4, and TH5, and when the teeth TH1 to TH4 are set as a region of interest, a point between the teeth TH2 and TH3 is designated by the designation cursor 212. Then, the number of four teeth is specified by the slide setting unit 231 to set the oval CT imaging area CAa for the teeth TH1 to TH4.

  However, it may be configured to designate a tooth near the center of the region of interest, as in the case where the designated number of teeth is an odd number, without necessarily designating between teeth. In this case, what range is actually set as the oval CT imaging area CAa can be arbitrarily determined.

  Specifically, when the tooth TH3 is designated and the number of four teeth is designated by the slide setting unit 231, the center portion of each of the teeth TH1 and TH5 is a boundary region, and the tooth TH1 An oval CT imaging region CAa may be set for the half region, the entire region of the teeth TH2 to TH4, and the half region of the tooth TH5.

  Furthermore, an oval CT imaging area CAa is set for the four teeth TH1 to TH4 near the front teeth, and an oval CT imaging area CAa is set for the four teeth TH2 to TH5 near the back teeth. Or, the setting range is rounded up to set the oval CT imaging area CAa for all of the teeth TH1 to TH5, or it is rounded down to set the oval CT imaging area CAa to the teeth TH2 to TH4. As described above, the position of the center in the longitudinal direction in the oval CT imaging region CAa may be slightly adjusted.

  The designation operation information of the center in the longitudinal direction of the oval CT imaging area CAa and the number of teeth included in the oval CT imaging area CAa, which are input on the CT imaging area setting screen 200, is transmitted to the information processing apparatus 8. The information processing apparatus 8 that has received the designation information transmits information regarding the oval CT imaging region line 213 set in advance according to the center position and the number of teeth to the operation display unit 61. The operation display unit 61 that has received information on the CT imaging region line 213 from the information processing device 8 uses the dental arch image 211 and the CT imaging region line based on the received information in the image display unit 210 of the CT imaging region setting screen 200. And 213 are displayed in a superimposed manner.

  The operator (operator) confirming the CT imaging region setting screen 200 confirms that the CT imaging region line 213 is set to a desired position and range with respect to the dental arch image 211, and the Set button 241 is pressed. When pressed, the CT imaging area line 213 is transmitted to the information processing apparatus 8 as the set oval CT imaging area CAa, and when the Start button 243 is further pressed, as described later, the set oval CT imaging is performed. Based on the area CAa, X-ray CT imaging of the right dentition object OB1 by the X-ray CT imaging apparatus 1 is started.

On the other hand, when the Reset button 242 is pressed, the designation operation by the image display unit 210, the upper and lower jaw selection unit 220, and the selection range setting unit 230 is canceled, and the initial state that is the default before the designation is returned.
It should be noted that a UNDO button and a REDO button (not shown) may be further provided so as to return to the previous operation state or to proceed to the next operation state from the returned position.

  X-ray CT imaging of the right dentition imaging object OB1 by the X-ray CT imaging apparatus 1 based on the set CT imaging area CA is performed with the subject M1 in a predetermined position in the X-ray CT imaging apparatus 1 (see FIG. 1). As shown in FIG. 9, the turning arm 30 turns the turning shaft 31 from the initial position (first turning position) where the turning arm 30 becomes the X-ray generation unit 10 on the right molar T3 side and the X-ray detection unit 20 on the left molar T2 side. The center Sc is turned by 180 degrees or more and photographed (X-ray restriction step s130).

  Note that although CT imaging can be performed even with a turn of only a 180 degree turning angle, it is preferable to obtain projection data for 180 degrees or more for any part of the CT imaging region, so that the rotation axis 31 of the X-ray cone beam BX can be obtained. It is further preferable to perform CT imaging at a turning angle obtained by adding a spread angle portion viewed from the axial direction to 180 degrees. Further, in order to generate a good image, it is more preferable to turn 360 degrees. However, in order to suppress an increase in CT imaging time and X-ray exposure while obtaining a good image, it is more preferable to finish CT imaging by a 360-degree turn.

  Note that the above-mentioned 180 degree turning angle, the turning angle obtained by adding 180 degrees to the spread angle of the X-ray cone beam BX as viewed from the axial direction of the turning axis 31, or the turning angle for 360 degrees is an image reconstruction. Assuming a range that includes a slight increase or decrease in angle that does not cause a substantial difference.

  Specifically, the X-ray CT imaging apparatus 1 projects the X-ray cone beam BX by a predetermined number of times while rotating the X-ray cone beam BX by rotating the rotation axis 31 about the rotation center Sc. Collect data. Specifically, the main body control unit 60 monitors the turning motor 37 and every time the turning arm 30 turning around the turning shaft 31 rotates by a predetermined angle, X-ray detection data in the X-ray detector 21 is detected. Are collected as projection data.

  The X-ray cone beam BX may be irradiated by the X-ray generator 10 so that the subject is always irradiated with the X-ray cone beam BX while the swivel arm 30 is swung. The X-ray cone beam BX may be irradiated intermittently in accordance with the timing at which the unit 20 detects X-rays. In the latter case, since the subject M1 is intermittently irradiated with X-rays, the X-ray exposure amount of the subject can be reduced.

  The collected projection data is sequentially transferred to the information processing apparatus 8 and stored in the storage unit 802, for example. The collected projection data is processed in the arithmetic processing unit 801b and reconstructed into three-dimensional data. The reconstruction calculation processing in the calculation processing unit 801b includes predetermined preprocessing, filter processing, back projection processing, and the like. Various arithmetic processing techniques including known techniques can be applied to these arithmetic processes.

  9 shows the trajectory of the X-ray generator 10a, the lateral shielding plate 15, and the X-ray detector 21 in the turning of the turning arm 30 from the initial position (first turning position) to the fifth turning position. Is shown by a solid line at the first turning position, and by a dotted line after the second turning position. FIG. 10A shows a schematic plan view of the state where the swing arm 30 is in the initial position (first swing position), and FIG. 10B shows a schematic plan view of the state where the swing arm 30 is in the second swing position. Show. Similarly, FIG. 11A is the third turning position, FIG. 11B is the fourth turning position, FIG. 12A is the fifth turning position, and FIG. 11B is the initial position (first turning position). The top schematic diagram of the state which synthesize | combined each state to thru | or the 5th turning position is shown.

  The turning positions shown in FIGS. 9 to 12 are shown only at predetermined angles for easy explanation of the situation of X-ray CT imaging, and the rotation continues without stopping during CT imaging. Done. As shown in FIG. 12A, as described above, the fifth turning position, which is a position turned 180 degrees from the initial position (first turning position), is the right dentition with respect to the X-ray generator 10 at the initial position. The position is symmetrical with respect to the photographing object OB1.

  As shown in FIGS. 9 to 12, the horizontal reference irradiation of the X-ray cone beam BX irradiated along the y-axis direction from the X-ray generation unit 10 in the revolving arm 30 revolving around the revolving center Sc from the initial position. The center line BCL1 passes through the turning center Sc and goes to the X-ray detection unit 20. However, the elliptical CT imaging area CAa having a long cylindrical shape including the right dentition imaging object OB1 is decentered to the + x side with respect to the turning center Sc, and therefore the X-ray cone beam irradiated from the X-ray generation unit 10 The beam forming mechanism 13 adjusts the irradiation direction in the horizontal direction of BX.

  That is, when performing CT imaging of the ellipsoidal CT imaging area CAa shown in FIG. 9, the ellipse CT imaging viewed from the X-ray generation unit 10 side as the turning position of the turning arm 30 changes. The amount of eccentricity with respect to the turning center Sc at the lateral end of the area CAa changes. The beam forming mechanism 13 adjusts the irradiation direction in the horizontal direction of the X-ray cone beam BX in accordance with the change in the amount of eccentricity.

  Further, since the lateral width of the oval cylindrical CT imaging area CAa including the right-side dentition imaging object OB1 is narrower than the X-ray cone beam BX that does not restrict the lateral spread, the X-ray cone The lateral spread of the beam BX is narrowly adjusted according to the width of the oval CT imaging area CAa having a long cylindrical shape.

Specifically, the lateral position of the lateral shielding plate 15 (15a, 15b) with respect to the emission port 12 is adjusted by the shielding plate lateral movement mechanism 16b according to the turning angle, and the lateral direction of the X-ray cone beam BX. And the opening 17 is decentered from the X-ray generator 10 toward the X-ray detector 20 toward the -x side with respect to the exit 12. The irradiation direction of the X-ray cone beam BX is adjusted according to the oval CT imaging area CAa.
Therefore, it is possible to reduce the X-ray exposure dose in the range indicated by the oblique lines in FIGS.

  More specifically, as shown in FIG. 10A, at the initial position (first turning position) where the X-ray cone beam BX is irradiated in a direction substantially orthogonal to the longitudinal direction of the oval CT imaging area CAa, The left lateral shielding plate 15a is slightly displaced to the -x side, and the right lateral shielding plate 15b is largely displaced to the + x side, so that it is about half of the large irradiation field opening 17a shown in FIG. An opening 17 having a width of 5 mm is formed. As a result, the X-ray cone beam BX is decentered to the + x side so that the −x side boundary line of the X-ray cone beam BX coincides with the horizontal reference irradiation center line BCL1, and the ellipse CT imaging is performed. The X-ray cone beam BX including substantially both ends in the longitudinal direction of the area CAa is irradiated.

  Therefore, as shown in FIG. 26 and FIG. 27, in FIG. 10A, compared with the case where a cylindrical CT imaging area CAo including the entire dental arch area X is acquired in the conventional X-ray CT imaging, the diagonal lines in FIG. It is possible to reduce the X-ray exposure dose in an unnecessary range for the oval CT imaging area CAa shown in FIG.

On the other hand, at the second turning position shown in FIG. 10B, the irradiation direction of the X-ray cone beam BX is substantially the same as the longitudinal direction of the oval CT imaging area CAa. The shielding plate 15a is further slightly displaced to the -x side, and the right lateral shielding plate 15b is further displaced to the + x side, so that it is approximately half of the initial position (first turning position) shown in FIG. An opening 17 having a width of about a certain width is formed, and the irradiation direction of the X-ray cone beam BX is decentered further to the + x side than the horizontal reference irradiation center line BCL1, and the oval CT imaging area CAa orthogonal to the longitudinal direction is formed. An X-ray cone beam BX including the width direction is irradiated.
Therefore, it is possible to reduce the X-ray exposure dose in a range that is not necessary for the oval CT imaging area CAa further than the initial position (first turning position).

  In the third turning position shown in FIG. 11A, the irradiation direction of the X-ray cone beam BX and the longitudinal direction of the oval CT imaging area CAa intersect each other, so that the right lateral shielding plate 15b is positioned at the initial value. The opening 17 having a width about 2/3 times the initial position (first turning position) shown in FIG. 10A is formed, and the irradiation direction at the second turning position is on the −x side. As a result, similarly to the initial position (first turning position), the X-ray cone beam BX is irradiated so that the −x side boundary line of the X-ray cone beam BX coincides with the horizontal reference irradiation center line BCL1. The direction is decentered to the + x side, and an X-ray cone beam BX including substantially both ends of an oval CT imaging area CAa whose longitudinal direction intersects the irradiation direction is irradiated.

  Therefore, although the reduction amount of the X-ray exposure in the unnecessary range compared with the second turning position is reduced, it is not necessary for the oval CT imaging area CAa further than the initial position (first turning position). The X-ray exposure amount in the range can be reduced.

In the fourth turning position shown in FIG. 11 (b), the intersection angle between the irradiation direction of the X-ray cone beam BX and the longitudinal direction of the oval CT imaging area CAa is larger than the third turning position, so that the left lateral shielding is performed. The plate 15a and the right lateral shield plate 15b are displaced to the -x side to form an opening 17 having a width comparable to the initial position (first turning position) shown in FIG. 10A, and at the second turning position. The X-ray cone beam BX including substantially both ends of the oval CT imaging region CAa is irradiated with the irradiation direction in the vicinity of the center in the width direction.
Therefore, it is possible to reduce the X-ray exposure dose in an unnecessary range with respect to the oval CT imaging area CAa to the same extent as the initial position (first turning position).

  Since the fifth turning position shown in FIG. 12A is a straight line symmetrical position passing through the turning center Sc with respect to the initial position, it is about the same as the initial position (first turning position) shown in FIG. And an irradiation direction eccentric to the −x side from the irradiation direction at the second turning position and to the −x side with respect to the vicinity of the center in the width direction, and an oval CT imaging area CAa. Are irradiated with an X-ray cone beam BX including substantially both ends. Therefore, it is possible to reduce the X-ray exposure dose in an unnecessary range with respect to the oval CT imaging area CAa to the same extent as the initial position (first turning position).

  As described above, the position of the oval CT imaging region CAa with respect to the horizontal reference irradiation center line BCL1 of the X-ray cone beam BX irradiated from the X-ray generation unit 10 toward the X-ray detection unit 20 is the rotation of the revolving arm 30. Since it changes according to the position, the horizontal position of the horizontal shielding plate 15 (15a, 15b) with respect to the emission port 12 is changed according to the turning angle of the horizontal shielding plate 15 (15a, 15b) by the shielding plate horizontal movement mechanism 16b. The X-ray cone beam BX is irradiated in the direction of the ellipse with the opening 17 decentered toward the X-ray side from the X-ray generator 10 toward the X-ray detector 20 with respect to the exit 12. Adjust according to the area CAa.

  Further, the vertical spread of the X-ray cone beam BX may also be regulated in accordance with the CT imaging target. For example, when the CT imaging target is a maxillary tooth, only the upper jaw part is regulated to be an irradiation target of the X-ray cone beam BX.

  FIG. 13 is a diagram of the X-ray generator 10a, the X-ray cone beam BX, and the X-ray generator 20 (specifically, the X-ray detector 21) viewed from the −x direction to the + x direction. It shows a situation where the object to be imaged is located above the upper jaw teeth.

  Furthermore, an oval cylindrical CT imaging area CAa including the right-side dentition imaging object OB1 is vertical to the X-ray cone beam BX irradiated horizontally from the X-ray generation unit 10 toward the X-ray detection unit 20. Since the beam is eccentric in the longitudinal direction with respect to the direction reference irradiation center line BCL2, the irradiation direction in the vertical direction of the X-ray cone beam BX irradiated from the X-ray generation unit 10 is adjusted by the beam shaping mechanism 13.

  In the illustrated example, the X-ray cone beam BX is irradiated horizontally, and the vertical reference irradiation center line BCL2 is perpendicularly incident on the detection surface 21 of the X-ray detector 21, but panoramic imaging described later is performed. Therefore, when the X-ray detector 21 is arranged higher than the X-ray generator 10a, the X-ray cone beam BX is irradiated at an elevation angle.

  Further, since the vertical height of the oval cylindrical CT imaging area CAa including the right dentition imaging object OB1 is narrower than the X-ray cone beam BX that does not regulate the vertical spread, The spread of the cone beam BX in the vertical direction is narrowly adjusted in accordance with the width of the elliptical CT imaging area CAa having a long cylindrical shape.

  Specifically, the vertical position of the vertical shielding plate 14 (14a, 14b) with respect to the emission port 12 is adjusted by the shielding plate vertical movement mechanism 16a, and the vertical spread of the X-ray cone beam BX is obtained by oval CT imaging. The X-ray cone beam is adjusted narrowly according to the height of the area CAa, and the opening 17 is decentered upward (+ z side) from the X-ray generation unit 10 toward the X-ray detection unit 20 with respect to the emission port 12. The irradiation direction of BX is adjusted according to the oval CT imaging area CAa.

  Further, as shown in FIG. 13B, an oval CT imaging region CAa with respect to the vertical reference irradiation center line BCL2 of the X-ray cone beam BX irradiated from the X-ray generation unit 10 toward the X-ray detection unit 20 is obtained. The position changes according to the turning position of the turning arm 30. Accordingly, the vertical position of the vertical shielding plate 14 (14a, 14b) with respect to the emission port 12 is adjusted by the shielding plate vertical movement mechanism 16a according to the turning position of the turning arm 30, and the opening to the emission port 12 is opened. 17 is decentered upward (+ z side) from the X-ray generation unit 10 toward the X-ray detection unit 20, and the irradiation direction of the X-ray cone beam BX is adjusted according to the oval CT imaging region CAa.

  In the illustrated example, the upper right corner of the ellipse CT imaging area CAa illustrated in FIG. 13B is closer to the turning center Sc than the position illustrated in FIG. 13A, and thus the upper end of the X-ray cone beam BX. Is also lowered toward the lower side (-z side) accordingly. The same adjustment is performed for the position of the lower left corner of the ellipse CT imaging area CAa and the height of the lower end of the X-ray cone beam BX.

In this way, the ellipsoidal CT imaging area CAa is narrower than the X-ray cone beam BX that is eccentric with respect to the turning center Sc and the horizontal reference irradiation center line BCL1 in the horizontal direction and that does not restrict lateral spread. On the other hand, the horizontal position of the horizontal shielding plate 15 (15a, 15b) with respect to the exit port 12 is adjusted by the shielding plate horizontal movement mechanism 16b according to the turning position of the turning arm 30, respectively, and the horizontal direction of the X-ray cone beam BX is adjusted. The spread of the direction is adjusted to be narrow according to the width of the oval CT imaging area CAa, and the opening 17 is displaced in the x direction with respect to the exit port 12 to change the irradiation direction of the X-ray cone beam BX to the oval CT. By adjusting according to the imaging area CAa, in the horizontal direction, the right dentition imaging object OB1 which is the area of interest is appropriately irradiated with an X-ray cone beam, While reducing the X-ray exposure amount can be reliably region of interest to the X-ray CT imaging.
The spread control of the X-ray cone beam BX by the beam shaping mechanism 13 is performed during imaging.

  Further, in the vertical direction, an ellipsoidal CT imaging area CAa that is decentered with respect to the vertical reference irradiation center line BCL2 and has a low height with respect to the X-ray cone beam BX that does not restrict the spread in the vertical direction. The vertical position of the vertical shielding plate 14 (14a, 14b) with respect to the exit 12 is adjusted by the shielding plate vertical movement mechanism 16a according to the turning position of the turning arm 30, and the X-ray cone beam BX is spread in the vertical direction. Is adjusted narrowly according to the height of the oval CT imaging area CAa, and the opening 17 is displaced in the z direction with respect to the exit port 12 to change the irradiation direction of the X-ray cone beam BX to the oval CT imaging area. By adjusting according to CAa, in the vertical direction, the right dentition object OB1 that is the region of interest is appropriately irradiated with an X-ray cone beam, and a wasteful X-ray exposure amount is obtained. While reducing can be reliably X-ray CT imaging a region of interest.

  In the above description, the vicinity of the center of the oval CT imaging area CAa is designated by the designation cursor 212 in the image display unit 210 of the CT imaging area setting screen 200, and the oval CT imaging area is selected by the selection range setting unit 230. Although the number included in CAa is designated and the ellipse CT imaging area CAa is set, the present invention is not limited to this designation method. In the following, another CT imaging region setting screen will be described with reference to FIGS.

  Similar to the CT imaging region setting screen 200 shown in FIG. 8, the CT imaging region setting screen 200A shown in FIG. 14 includes an image display unit 210A, an upper and lower jaw selection unit 220, and a condition setting unit 240. The selection range setting unit 230 in the area setting screen 200 is not provided. Since the upper and lower jaw selection unit 220 and the condition setting unit 240 in the CT imaging region setting screen 200A are the same as those in the CT imaging region setting screen 200, description thereof will be omitted.

  The image display unit 210A displays a dental arch image 211 and a designated cursor (pointer) 212, similarly to the image display unit 210 of the CT imaging region setting screen 200 shown in FIG. In the CT imaging area setting screen 200, in order to set the CT imaging area line 213, the vicinity of the center in the longitudinal direction of the oval CT imaging area CAa is designated by the designation cursor 212, but in the CT imaging area setting screen 200A, The start cursor and the end point, which are both ends in the longitudinal direction of the oval CT imaging area CAa, are designated by the designation cursor 212. The dental arch image 211 is an image of the jawbone viewed from the body axis direction.

  In FIG. 14, two designation cursors 212 are illustrated on the image display unit 210 </ b> A, but actually, the designation cursor 212 is moved after the designation tooth 212 is designated with one designation cursor 212, and the end point is designated. It is the structure which specifies the tooth which becomes. However, as shown in FIG. 14, the designation cursor 212 that designates the start point tooth may be fixed, another designation cursor 212 may appear, and the end point tooth may be designated by another designation cursor 212.

Further, in consideration of a case where the designation is wrong or a case where the designation is desired to be changed, the position of the start point and the end point may be changed.
Furthermore, although the CT imaging area CAa may be specified in units of teeth such as the start point tooth and the end point tooth as described above, the CT imaging area line 213 is shown in the default range, It may be configured such that both ends are pointed and held by the designated cursor 212 and moved by a drag operation to deform the CT imaging region line 213 so that the covered range can be changed.

  In the image display unit 210A on the CT imaging area setting screen 200A, the designation operation information in which the start and end teeth are designated using the designation cursor 212 is transmitted to the information processing apparatus 8, and the information processing apparatus 8 that has received the designation information Then, information regarding the ellipse CT imaging region line 213 set in advance according to the combination of the starting tooth and the ending tooth is transmitted to the operation display unit 61. In the dental arch region X, teeth are arranged in a total of 16 locations (if the target is only the upper jaw or only the lower jaw, there is one in each location, and 1 if the subject covers the upper and lower jaws). 120 total oval CT imaging region lines 213 may be set in advance in two locations (upper and lower teeth in total).

  Further, only one tooth may be configured to be able to perform CT imaging. In this case, if 16 CT imaging region lines (not shown) are added, 136 ellipse CT imaging region lines 213 are prepared. Can do.

  Note that the above-described 16 CT imaging area lines for CT imaging of only one tooth have special lengths that have almost no difference in length between the longitudinal direction and the lateral direction as a valuation of the oval CT imaging area. This is a circular CT imaging region.

  Further, 120 patterns may be prepared for each of the maxillary teeth, the mandibular teeth, and the upper and lower jaw teeth, and 120 parts for two portions of the upper jaw teeth, the lower jaw teeth, and the upper and lower jaw teeth. Alternatively, another 120 patterns may be prepared for the remaining one part.

Furthermore, it is good also as a setting remove | excluding wisdom teeth in order to restrict | limit only to the location where the frequency used as the planting object of an implant is high.
Further, the range surrounded by the CT imaging region line 213 may be configured as the oval CT imaging area CAa as it is, regardless of the number of teeth.

  The operation display unit 61 that has received information on the CT imaging region line 213 from the information processing device 8 uses the dental arch image 211 and the CT imaging region line based on the received information in the image display unit 210 of the CT imaging region setting screen 200. And 213 are displayed in a superimposed manner. Since the processing flow after the superimposed display is the same as the processing flow in the CT imaging region setting screen 200, description thereof is omitted.

  A CT imaging region setting screen 200B shown in FIG. 15, which is another setting screen, is similar to the CT imaging region setting screen 200A shown in FIG. 14, and includes an image display unit 210B, upper and lower jaw selection unit 220, and condition setting unit 240. It is composed. The upper and lower jaw selection unit 220 and the condition setting unit 240 in the CT imaging region setting screen 200B are the same as the CT imaging region setting screen 200 and the CT imaging region setting screen 200A, and thus description thereof is omitted.

  Similar to the image display unit 210 of the CT imaging region setting screen 200, the image display unit 210B displays a dental arch image 211 and a designated cursor 212. Further, the CT imaging region setting screen 200B displays the divided area 214 for dividing the dental arch image 211 in the image display unit 210B in a superimposed manner, and designates the divided area 214 for dividing the dental arch image 211 as a designated cursor (pointer). This is a configuration to be selected and designated at 212.

  In the image display unit 210B on the CT imaging region setting screen 200B, the designation operation information in which the division area 214 including the right dentition imaging object OB1 that is the region of interest is selected and designated by the designation cursor 212 is transmitted to the information processing device 8. The information processing apparatus 8 that has received the designation information transmits an oval CT imaging area CAa set in advance corresponding to the selected and designated divided area 214 to the X-ray CT imaging apparatus 1 to perform X-ray CT imaging. Run.

  In the CT imaging region setting screen 200B shown in FIG. 15, with respect to the dental arch image 211, a part centered on the front tooth T1, a part centered on the left molar T2, a part centered on the right molar T3, and Although five divided areas 214 are set in total for the left and right temporomandibular joint parts, the division pattern is not limited to this, and various patterns can be used as long as they are line-symmetric with respect to the midline that is the center of the dental arch image 211. A simple division pattern can be set. In addition, various division patterns are set in advance, and a switching button for switching the division pattern is provided on the CT imaging region setting screen 200B, and a desired division pattern is displayed on the image display unit 210B, and then the division area 214 is selected and designated. May be.

Alternatively, the line of the divided area may be pointed and held by the designation cursor 212 and moved by a drag operation to be deformed, and the divided pattern most suitable for the shape of the line after deformation may be called.
Note that the processing flow of X-ray CT imaging after selection designation of the divided area 214 is as described above, and thus description thereof is omitted.

  Further, the CT imaging region setting screen 200C shown in FIG. 16 which is another setting screen is similar to the CT imaging region setting screen 200A shown in FIG. 14 and includes an image display unit 210C, an upper and lower jaw selection unit 220, and a condition setting unit 240. It consists of. The upper and lower jaw selection unit 220 and the condition setting unit 240 in the CT imaging region setting screen 200C are the same as those in the CT imaging region setting screen 200 and the like, and thus description thereof is omitted.

  The image display unit 210 </ b> C displays a dental arch image 211. In the CT imaging region setting screen 200, in order to set the CT imaging region line 213, the vicinity of the center in the longitudinal direction of the CT imaging region CA is designated by the designation cursor 212. However, in the CT imaging region setting screen 200C, the touch pen 250 is used. The ellipse CT imaging area CAa is designated by the handwritten CT imaging area line 213C handwritten so as to surround the right dentition imaging object OB1, which is the region of interest, in an oval shape.

  In the image display unit 210C on the CT imaging region setting screen 200C, the designation operation information by the handwritten CT imaging region line 213C handwritten with the touch pen 250 is transmitted to the information processing device 8, and the information processing device 8 that has received the designation information A preset oval CT imaging area CAa, which is preset to be approximate to the CT imaging area line 213C, is transmitted to the X-ray CT imaging apparatus 1, and X-ray CT imaging is executed. Note that the CT imaging area CA needs to be a closed area configured with a convex curve toward the radially outer side, and therefore, even if the handwritten CT imaging area line 213C has a concave portion that faces the radially inner side, it is registered in advance. In the CT imaging area line 213, an approximate line among the CT imaging area lines 213 configured with a convex curve outward in the radial direction is defined as a CT imaging area CA. Or it is good also as CT imaging area | region CA by correcting the concave part which goes to the diameter inside in handwritten CT imaging | photography area line 213C to convex shape. Further, since the processing flow of X-ray CT imaging is as described above, description thereof is omitted.

  Furthermore, the CT imaging region setting screen 200D shown in FIG. 17 which is another setting screen is similar to the CT imaging region setting screen 200A shown in FIG. 14 in that the image display unit 210D, the upper and lower jaw selection unit 220, and the condition setting unit. 240. The upper and lower jaw selection unit 220 and the condition setting unit 240 in the CT imaging region setting screen 200D are the same as those in the CT imaging region setting screen 200 and the like, and thus description thereof is omitted.

  Instead of the dental arch image 211, the image display unit 210D displays a panoramic image 211D obtained by panoramic X-ray imaging of the dental arch region X of the patient as the subject in advance. The image display unit 210D is configured to designate the right dentition imaging object OB1 that is the region of interest as the CT imaging area CA by any of the methods described above. In the illustrated example, an oval CT imaging area CAa is designated as the CT imaging area CA, and the oval CT imaging area CAa is displayed so as to be surrounded by a curve indicated by 213.

  Designation operation information for the panoramic image 211D obtained by panoramic imaging of the dental arch region X of the patient as the subject in advance is transmitted to the information processing apparatus 8 on the CT display region setting screen 200D, and the designation information is accepted. The information processing apparatus 8 transmits information regarding the preset oval CT imaging region line 213 to the operation display unit 61.

  The operation display unit 61 that has received information related to the CT imaging region line 213 from the information processing device 8 uses the panoramic image 211D and the CT imaging region line 213 based on the received information in the image display unit 210 of the CT imaging region setting screen 200D. Is superimposed. Since the processing flow after the superimposed display is the same as the processing flow in the CT imaging region setting screen 200, description thereof is omitted.

  The three-dimensional position information of the panoramic tomographic position of the subject M1 fixed to the subject fixing unit 421 can be grasped by the arithmetic processing unit 801b from the positional relationship between the subject fixing unit 421 and the set panoramic tomographic position. The three-dimensional coordinates of the position designated by the position designation with respect to can be calculated by calculation.

  Also, even if the panoramic image 211D is a panoramic image captured by another X-ray imaging apparatus, the specified position is calculated by coordinate calculation as long as there is panoramic tomographic position information at the time of panoramic imaging. be able to.

  As described above, in the CT imaging region setting screens 200, 200A, 200B, 200C, and 200D, an oval CT imaging having an appropriate oval shape with respect to the right dentition imaging object OB1 that is the region of interest is performed by various methods. The area CAa can be set. However, depending on medical conditions and cases, a plurality of objects in the dental arch region X as shown in FIG. 18 may be used instead of the right dental imaging object OB1 occupying the right half of the dental arch region X as shown in FIG. An elliptical elliptical CT imaging area CAb having the front tooth T1 as the imaging object OB may be set.

  In this case, as shown in FIG. 18, an X-ray cone beam BX that is narrower in the width direction than the case where X-ray CT imaging is performed on the elliptical CT imaging area CAb is caused by the horizontal shielding plate 15 according to the turning angle. Control and illuminate and shoot. Even in such a narrow X-ray cone beam BX, the irradiation direction of the X-ray cone beam BX is elliptical by the left lateral shield plate 15a and the right lateral shield plate 15b that are independently displaced in the width direction. It can be changed and photographed according to the shape CT imaging area CAb. Therefore, it is possible to reduce the amount of X-ray irradiation to a portion that does not need to be irradiated with X-rays.

  In the above description, the ellipsoidal CT imaging area CAb, which is a small range compared to the oval CT imaging area CAa, has been described. However, depending on the symptom, medical treatment method, etc., the oval CT imaging area CAa or Not only the elliptical CT imaging area CAb but also various types of CT imaging areas CA as shown in FIG. 19, for example, can be set.

  For example, the ellipsoidal CT imaging area CAa1 shown in FIG. 19A has a longer longitudinal length in the curve of the dental arch area X than the oval CT imaging area CAa shown in FIG. It is configured in an oval shape integrally surrounding up to a position Kh where the right mandibular head is located in plan view at K.

  In addition, an oval CT imaging area CAa2 shown in FIG. 19B is an oval shape that integrally surrounds a part of the front teeth T1 and left molars T2 on the opposite side as compared to the oval CT imaging area CAa1. It consists of.

  A substantially triangular CT imaging region CAc shown in FIG. 19C surrounds the entire dental arch region X including the position Kh where the left and right mandibular heads are located in a plan view, and the corners on the front tooth T1 side are arranged in the order of the front teeth T1. It is a substantially triangular shape along. Specifically, the substantially triangular CT imaging region CAc has an arc shape at the corner and an arc shape in which a side portion connecting the corner and the corner is convex outward, and the corner along the front teeth T1 is arranged. It has a substantially triangular shape at the apex, and the arc shape of the base part connecting the positions Kh with the left and right mandibular heads in plan view is formed with a curve with a larger curvature than the arc shape of the hypotenuse part, so to speak, it is shaped like a rice ball. Yes. In addition, this substantially triangular shape can be rephrased as a substantially Rouleau triangular shape in which the corners of the three apexes of the Rouleau triangle are connected by an arc that protrudes outward.

  As described above, the substantially triangular CT imaging area CAc having such a configuration is a cylindrical CT imaging area CAo including the entire dental arch area X in the conventional X-ray CT imaging as shown in FIGS. As compared with the above, since the CT imaging region approaches the shape of the region of interest, it is possible to reduce the amount of irradiation to a portion that does not need to be irradiated with X-rays.

  Further, the substantially triangular CT imaging area CAc1 shown in FIG. 19D is similar to the substantially triangular CT imaging area CAc, and surrounds only the tooth area of the dental arch area X, and the front tooth T1 side. Are substantially triangular along the front teeth T1.

  On the other hand, the substantially triangular CT imaging area CAc2 shown in FIG. 19 (e) is different from the substantially triangular CT imaging areas CAc and CAc1, and is substantially triangular in which the curve along the front teeth T1 is on the bottom side. Then, it is substantially semicircular, and has a substantially triangular shape that is flat in the width direction and is configured by a curve in which the hypotenuse and the corner are substantially continuous as compared to the substantially triangular CT imaging areas CAc and CAc1.

  When performing CT imaging of the substantially triangular CT imaging area CAc shown in FIG. 19C, the turning position of the turning arm 30 changes in the same way as CT imaging of the oval CT imaging area shown in FIG. As a result, the amount of eccentricity with respect to the turning center Sc at the lateral end of the substantially triangular CT imaging region CAc viewed from the X-ray generation unit 10 side changes. The beam forming mechanism 13 adjusts the irradiation direction in the horizontal direction of the X-ray cone beam BX in accordance with the change in the amount of eccentricity.

  In the CT imaging of the substantially triangular CT imaging area CAc shown in FIG. 19C, the turning arm 30 takes a turning position corresponding to the third turning position in the CT imaging of the oval CT imaging area shown in FIG. Sometimes, the X-ray generator 10 faces the bottom portion of the substantially triangular CT imaging area CAc in the illustrated state. (Hereinafter, the positions corresponding to the first to fifth turning positions shown in FIG. 9 are defined as the first to fifth turning positions in CT imaging of the substantially triangular CT imaging area CAc.) X-rays at this time The center beam of the cone beam BX is incident along the normal line of the central portion of the bottom side of the substantially triangular CT imaging area CAc in plan view.

  Due to this positional relationship, the lateral width of the substantially triangular CT imaging area CAc as viewed from the X-ray generation unit 10 is the first turning position, the second turning position, the fourth turning position, and the fifth turning position, which are other turning positions. Compared to the largest. In accordance with this spread, it is necessary to maximize the opening degree (interval with respect to each other in the lateral direction) of the lateral shielding plate 15 (15a, 15b) with respect to the emission port 12.

  Further, in addition to the oval CT imaging area CAa, the elliptical CT imaging area CAb, and the substantially triangular CT imaging area CAc, as shown in FIG. An oval round-cornered rectangular CT imaging area CA, or a substantially rectangular CT imaging area CA with corners chamfered in an arc shape as shown in FIG. Although not shown, the CT imaging area CA can have various shapes such as an oval shape such as a substantially oval shape.

  In other words, the oval CT imaging area CAa in FIGS. 9 and 14, the elliptical CT imaging area CAb in FIG. 18, the oval CT imaging areas CAa1 and CAa2 in FIGS. 19A and 19B, and FIG. The oval and round oval CT imaging areas CA of f) and (g) and the oval CT imaging area CA such as a substantially oval shape are substantially long having a longitudinal direction along the dental arch area X. It can be summarized as a circular X-ray CT imaging region. The oval shape includes a substantially oval shape other than a substantially oval shape.

  Curves of the oval CT imaging areas CAa, CAa1, CAa2, the elliptical CT imaging areas CAb, the substantially triangular CT imaging areas CAc, CAc1, CAc2 described above, or the dental arch area X such as an oval shape, for example. As described above, in the CT imaging area CA having a portion along the horizontal direction, the horizontal position of the horizontal shielding plate 15 (15a, 15b) relative to the emission port 12 is changed by the shielding plate lateral movement mechanism 16b according to the turning angle. Each is adjusted so that the lateral spread of the X-ray cone beam BX is adjusted to the width of the CT imaging area CA, and the opening 17 with respect to the exit 12 is laterally directed from the X-ray generator 10 to the X-ray detector 20. This is realized by adjusting the irradiation direction of the X-ray cone beam BX according to the CT imaging area CA.

  The elliptical CT imaging areas CAa, CAa1, CAa2, and the elliptical CT imaging area CAb are set so that the longitudinal direction is along the dental arch area X. More specifically, the radial direction of the major axis is It is set so as to coincide with the tangential direction of the curved curve of the dental arch region X. The same applies to the oval CT imaging area CA.

  In this way, the CT imaging area CA follows the curve of the dental arch area X with respect to the size, range, and position in the dental arch area X of the right dental imaging object OB1, which is an example of the region of interest. By setting various shapes such as oval, elliptical, substantially triangular, or oval shape having a portion, the right dentition imaging object that is the region of interest can be surely reduced while reducing the amount of unnecessary X-ray exposure. Although OB1 can be taken with certainty, for example, when observing whether the wisdom is almost lying on its side in the area of the buried wisdom tooth, when it is desired to examine the spread of the tumor, or for the dental arch As shown in FIG. 20, for example, two or three right molars depending on various cases and parts such as diagnosis that require observation of not only the longitudinal portion of the region X but also the regions extending on the lingual side and the cheek side. Local topography of T3 As the object OB2, it may be better to the CT imaging area a true circular shape of a true circle CT imaging area CAd.

  In order to perform X-ray CT imaging on the perfect circular CT imaging region CAd surrounding the local imaging object OB2, as shown in FIG. 20, the lateral position of the lateral shielding plate 15 (15a, 15b) with respect to the emission port 12 Is adjusted by the shielding plate lateral movement mechanism 16b according to the turning angle, and the lateral spread of the X-ray cone beam BX is adjusted to the width of the perfect circular CT imaging region CAd, and with respect to the emission port 12. This is realized by decentering the opening 17 laterally from the X-ray generation unit 10 toward the X-ray detection unit 20 and adjusting the irradiation direction of the X-ray cone beam BX according to the perfect circular CT imaging area CAd. .

  Furthermore, in order to set the perfect circular CT imaging area CAd surrounding the local imaging object OB2, first, the Mode button 244 of the condition setting unit 240 in the CT imaging area setting screen 200 is pressed, as shown in FIG. Further, a local perfect CT imaging region setting screen 300 for setting a perfect circular CT imaging region CAd is displayed, and a perfect circular CT imaging region CAd is set on the local perfect circular CT imaging region setting screen 300. To do.

The local perfect CT imaging region setting screen 300 includes an image display unit 310 that displays the dental arch image 211, an upper and lower jaw selection unit 320, a selection range setting unit 330, and a condition setting unit 340. Yes.
The upper and lower jaw selection unit 320 and the condition setting unit 340 are similar to the upper and lower jaw selection unit 220 and the condition setting unit 240 in the CT imaging region setting screen 200, and include a Set button 341, a Reset button 342, a Start button 343, and a Mode button. 344 and the Return button 245, detailed description thereof is omitted.

  For the displayed dental arch image 311, the image display unit 310 performs a designation cursor (pointer) 312 for designating the center in the set circular CT imaging area CAd to be set, and a center designated by the designation cursor 312. A perfect oval CT imaging region line 313 corresponding to a radius specified by a selection range setting unit 330 described later is superimposed and displayed.

  The selection range setting unit 330 has a text box 331 for inputting a radius with respect to the center designated by the designation cursor 312, but may be configured to input a diameter.

First, in order to perform X-ray CT imaging of the local imaging object OB2, a circular shape including the local imaging object OB2 is displayed on the local perfect circle CT imaging area setting screen 300 displayed on the operation display unit 61. A CT imaging region line 312 is set.
More specifically, the local imaging object OB2 is selected by various buttons of the upper and lower jaw selection unit 320 according to one or both of the upper and lower foreheads, and the image display unit of the local perfect circle CT imaging region setting screen 300 is selected. With respect to the displayed dental arch image 211 displayed at 310, the designation cursor 312 is used to designate the center of the circle in the perfect circular CT imaging area CAd, and the value of the radius in the text box 331 in the selection range setting unit 330. Enter.

  Designated operation information based on the center of the circle in the perfect circular CT imaging region CAd and the radius value input in the text box 331 input and operated on the local perfect circular CT imaging region setting screen 300 is sent to the information processing apparatus 8. The information processing apparatus 8 that has been transmitted and receives the designation information transmits information related to the perfect CT imaging region line 312 to the operation display unit 61. The operation display unit 61 that has received information about the perfect circular CT imaging region line 312 from the information processing apparatus 8 receives the dental arch image 311 and the reception in the image display unit 310 of the local perfect circular CT imaging region setting screen 300. The perfect circle CT imaging region line 312 based on the obtained information is superimposed and displayed.

  The operator (operator) confirming the local perfect circular CT imaging region setting screen 300 has set the perfect circular CT imaging region line 312 at a desired position and range with respect to the dental arch image 311. When the Set button 341 is pressed, the perfect circle CT imaging region line 312 is transmitted to the information processing apparatus 8 as the set perfect circle CT imaging region CAd, and when the Start button 343 is further pressed. As described later, the X-ray CT imaging of the local imaging object OB2 by the X-ray CT imaging apparatus 1 is started.

  In the above description, the radius value indicating the size of the perfect CT imaging area CAd is numerically input in the text box 331. However, the perfect circle CT having the point designated by the designation cursor 312 as the center is used. The imaging region line 312 is superimposed on the dental arch image 211, and the point on the circumference of the displayed perfect circular CT imaging region line 312 is held by the designation cursor 312, and the size of the perfect circular CT imaging region line 312 is displayed. May be adjusted.

  In this way, for example, by setting the right and left molars T3 as the local local imaging object OB2, the CT imaging area can be set to a perfect circular CT imaging area CAd. An oval shape having a portion along the curve of the dental arch region X with respect to the size, range, and position of the dental arch region X of the right dental imaging object OB1 that is the region of interest; In addition to being able to reliably photograph the right dentition object OB1, which is a region of interest, while reducing the amount of unnecessary X-ray exposure by setting various shapes such as an elliptical shape, a substantially triangular shape, or an oval shape. The useless X-ray exposure amount can be further reduced and the usability can be improved for the local object OB2 corresponding to various cases and parts such as diagnosis.

  In the X-ray CT imaging apparatus 1 described above, as shown in FIG. 25, panoramic imaging can be performed by placing the axis of the turning shaft 31 at the turning center Sc fixedly set at a specific position.

  Specifically, the irradiation direction of the X-ray slit beam BXP for panoramic imaging formed by changing the restriction range by the beam shaping mechanism 13 is controlled by the lateral shielding plate 15 according to the turning angle.

In panoramic imaging, the X-ray slit beam BXP is formed by a panoramic imaging opening 17c formed by a beam shaping mechanism 13 shown in FIG.
As shown in FIG. 25, the X-ray generation unit 10, the horizontal shielding plate 15, and the X-ray detection unit 20 (X-ray detector 21) together with the turning arm 30 (not shown) are rotated from the turning start positions LC 1 to 180 that are the initial positions. Rotate the camera to the end position of the turn and take a panoramic shot.

In the illustrated example, the initial position LC1 is configured such that the X-ray generation unit 10 is positioned directly to the right of the dental arch region X, and the X-ray generation unit 10 turns behind the head.
The turning center Sc is set in the vicinity of the midline between the left and right innermost back teeth.

  In FIG. 25, LC2 and LC3 are turned at every turning angle of the turning arm 30 and LC4 is turned up to 90 degrees, and the turning angle from 90 degrees to 180 degrees is subject to right and left. The illustration is omitted.

During panoramic imaging, the dental arch region X is continuously irradiated with the X-ray slit beam BXP.
At the turning position LC1, the irradiation direction of the X-ray slit beam BXP is −x with respect to the horizontal reference center line SCL connecting the X-ray tube focal point of the X-ray generation unit 10 and the center of the detection surface of the X-ray detector 21. The position of the horizontal shielding plate 15 is controlled so that the position of the panoramic photographing opening 17c is decentered in the -x direction with respect to the horizontal reference center line SCL so as to be decentered in the direction.

  At the turning position LC2, the irradiation direction of the X-ray slit beam BXP is the + x direction with respect to the horizontal reference center line SCL connecting the X-ray tube focus of the X-ray generator 10 and the center of the detection surface of the X-ray detector 21. The lateral shielding plate 15 is position-controlled so that the position of the panoramic photographing opening 17c is slightly decentered in the + x direction with respect to the horizontal reference center line SCL so as to be slightly decentered.

  At the turning position LC3, the irradiation direction of the X-ray slit beam BXP is relative to the horizontal reference center line SCL connecting the X-ray tube focal point of the X-ray generation unit 10 and the center of the detection surface of the X-ray detector 21. Displacement control of the horizontal shielding plate 15 is performed so that the position of the panoramic photographing opening 17c is further decentered in the + x direction with respect to the horizontal reference center line SCL so as to be slightly decentered in the + x direction than in the LC.

From the turning position LC3 to the turning position LC4, an X-ray slit beam is applied to the horizontal reference center line SCL connecting the X-ray tube focal point of the X-ray generator 10 and the center of the detection surface of the X-ray detector 21. The position of the panoramic imaging opening 17c is set to the horizontal reference center so that the irradiation direction of BXP is returned to the -x direction and the irradiation direction of the X-ray slit beam BXP coincides with the horizontal reference center line SCL at the position LC4. The displacement of the horizontal shielding plate 15 is moved back to the −x direction with respect to the line SCL, and the panorama photographing opening 17c is moved to a position that is not decentered with respect to the horizontal reference center line SCL at the position LC4.
By the above control, the locus of the X-ray slit beam BXP can form the envelope EM.

  Further, as shown in FIG. 26, compared to the conventional circular CT imaging area CAo having a small diameter of 80 mm, including a part of the jawbone and wisdom teeth, for example, a perfect circular CT imaging having a large diameter of 100 mm. The area CAd may be set.

  However, according to the X-ray CT imaging of the substantially triangular CT imaging area CAc having a substantially triangular shape under the control of the beam forming mechanism 13 during the X-ray CT imaging of the present application configuration, the X of the 100 mm diameter circular CT imaging area CAd. Compared with line CT imaging, the X-ray exposure can be reduced by the hatched area shown in the figure. Therefore, it is preferable that the region of interest is included in the substantially triangular CT imaging region CAc because the X-ray exposure dose can be reduced from the perfect circular CT imaging region CAd having a diameter of 100 mm.

  Moreover, if all the teeth of the dental arch are stored in the conventional circular CT imaging area CAo with a small diameter of 80 mm, the wisdom teeth and jawbone can be converted into a conventional circular CT imaging area with a small diameter of 80 mm. Although it could not be stored in CAo, according to the X-ray CT imaging of the substantially triangular CT imaging area CAc under the control of the beam forming mechanism 13 during the X-ray CT imaging, all the teeth of the dental arch were acquired by X-ray CT imaging. After being accommodated in the area, the wisdom teeth and the jawbone can also be accommodated in the substantially triangular CT imaging area CAc. Furthermore, the entire tooth of the dental arch is obtained by the X-ray detector 21 having an X-ray detection surface having the same size as that used in the conventional X-ray CT imaging of the small circular CT imaging area CAo having a diameter of 80 mm. Since the X-ray CT imaging of the substantially triangular CT imaging area CAc in which the wisdom teeth and the jawbone are accommodated in the X-ray CT imaging area can be performed, the apparatus cost can be kept low.

Furthermore, panoramic imaging may be performed with the above-described X-ray CT imaging apparatus 1 as shown in FIG.
Specifically, the X-ray slit beam BXP whose irradiation direction is adjusted by the beam forming mechanism 13 while irradiating the panoramic X-ray slit beam BXP formed by changing the restriction range by the beam forming mechanism 13 is used. By turning the turning arm 30 so as to form a trajectory for panoramic X-ray imaging that becomes the envelope EM, and controlling the upper frame 41 having the turning motor 37, another X-ray is required even when a panoramic image is required. Panoramic X-ray imaging can be performed with the X-ray slit beam BXP by the X-ray CT imaging apparatus 1 that can reduce useless X-ray exposure without preparing a X-ray imaging apparatus.

  In order to form a panoramic X-ray imaging trajectory that becomes an envelope EM by the irradiated X-ray slit beam BXP, the internal structure of the revolving arm 30 and the upper frame 41 for moving the revolving shaft 31 is explained. As shown in FIG. 23, which is a block diagram showing a configuration of an X-ray imaging apparatus that restricts the spread of the X-ray cone beam by moving the turning shaft 31, the shaft moving mechanism 34 is attached to the upper frame 41. FIG. You may wear it.

  FIG. 23A is a partial cross-sectional view showing the upper frame 41 together with its internal structure, and FIG. 23B is a partial cross-sectional view showing the swing arm 30 and the upper frame 41 together with its internal structure. FIG. 23B shows the turning arm 30 and the upper frame 41 when the X-ray CT imaging apparatus 1 is viewed from the side, and FIG. 23A shows the upper frame 41 when viewed from above. Is shown.

  The shaft moving mechanism 34 attached to the upper frame 41 includes an XY table 35 that moves the turning shaft 31 in the horizontal direction together with the turning arm 30, and a drive motor 36 that drives the XY table 35.

  The XY table 35 includes a Y table 35Y that moves the swing arm 30 in the front-rear direction (Y-axis direction), and an X table 35X that is supported by the Y table 35Y and moves in the horizontal direction (X-axis direction). .

  The drive motor 36 includes a Y-axis drive motor 36Y that drives the Y table 35Y and an X-axis drive motor 36X that moves the X table 35X in the X direction with respect to the Y table 35Y.

  In the X-ray CT imaging apparatus 1, as shown in FIG. 23, the drive motor 36 is connected to the main body control unit 60, and the X-ray CT imaging apparatus 1 drives the X-ray CT imaging apparatus 1 according to a predetermined program, The table 35X is moved left and right (X direction), and the Y table 35Y is moved back and forth (Y direction). Thereby, the turning shaft 31 can be controlled to move two-dimensionally in the front-rear and left-right XY directions.

  The axis moving mechanism 34 functions as a two-dimensional moving mechanism for moving the turning shaft 31 relative to the subject fixing portion 421 in the two-dimensional direction in the horizontal direction, and supports the turning arm 30 together with the turning motor 37. A body drive unit is configured.

  In this way, by attaching the axis moving mechanism 34 to the upper frame 41, the CT imaging area CA is compared with the size, range, and position in the dental arch area X of the right dental imaging object OB1 that is the area of interest. Is set in various shapes such as an oval shape, an elliptical shape, a substantially triangular shape, or an oval shape having a portion along the curve of the dental arch region X, thereby reducing the amount of wasted X-ray exposure and ensuring An X-ray CT imaging apparatus 1 that can reliably image the right dentition object OB1 that is a region of interest, and an envelope by an X-ray slit beam BXP for panoramic imaging formed by changing the restriction range by the beam shaping mechanism 13 It is also possible to perform panoramic X-ray imaging with the X-ray slit beam BXP by turning the turning arm 30 so as to form a trajectory for panoramic X-ray imaging as an EM.

  In the above description, the shaft moving mechanism 34 is attached to the upper frame 41 so that the turning shaft 31 can be moved in the plane direction, and panoramic photography is possible. Even if it remains fixed, the subject fixing portion 421 arranged on the lower frame 42 may be configured to be relatively movable in the plane direction with respect to the upper frame 41 so that panoramic photography is possible. The upper frame 41 may include the shaft moving mechanism 34 and the subject fixing unit 421 may be configured to be relatively movable.

  As described above, the X-ray CT imaging apparatus 1 forms the X-ray cone beam BX by regulating the X-ray generator 10 that generates X-rays and the irradiation range of the X-rays generated from the X-ray generator 10. A beam shaping mechanism 13, an X-ray detection unit 20 that detects an X-ray cone beam BX irradiated with an X-ray cone beam BX irradiated on a subject, an X-ray generation unit 10, an X-ray detection unit 20, and the subject are sandwiched between them. The swivel arm 30 that is opposed to and supported with the object sandwiched therebetween, and at least the swivel arm 30 is driven to swivel around the swivel axis 31 so that the X-ray generation unit 10 and the X-ray detection unit 20 are A turning motor 37 that turns around, an operation display unit 61 that displays a dental arch image 211 that is an image of the dental arch region X, and the setting of an oval CT imaging region CAa for the dental arch region X CT imaging area setting screen for accepting operations 200, and the oval CT imaging area CAa having a longitudinal direction along the dental arch area X in accordance with the set oval CT imaging area CAa input by operation on the CT imaging area setting screen 200 Alternatively, the main body control unit 60 that controls the beam shaping mechanism 13 is provided so as to have a substantially triangular shape that matches the shape of the dental arch region X that matches the shape of the dental arch region. It is possible to appropriately irradiate the X-ray cone beam BX, reduce the amount of unnecessary X-ray exposure, and reliably perform X-ray CT imaging of the region of interest.

  Specifically, an operation display unit 61 that displays a dental arch image 211 that is an image of the dental arch region X, and a CT imaging region setting that accepts an operation for setting an oval CT imaging region CAa for the dental arch region X. In accordance with the screen 200 and the set ellipsoidal CT imaging area CAa input by operation on the CT imaging area setting screen 200, the oval CT imaging area CAa has a substantially long length along the dental arch area X. Since the main body control unit 60 that controls the beam forming mechanism 13 is provided so as to have a circular shape or a substantially triangular shape that matches the shape of the dental arch region X, the dental arch displayed on the operation display unit 61 is provided. While confirming the image 211, the setting operation of the oval CT imaging area CAa with respect to the dental arch area X is performed, and the main body according to the set oval CT imaging area CAa input through the CT imaging area setting screen 200 The control unit 60 The beam shaping mechanism 13 is controlled so that the circular CT imaging area CAa has a substantially oval shape having a longitudinal direction along the dental arch area X or a substantially triangular shape that matches the shape of the dental arch area X. . Accordingly, the region of interest can be appropriately irradiated with the X-ray cone beam BX, and the region of interest can be reliably subjected to X-ray CT imaging. In addition, since the X-ray cone beam BX is appropriately irradiated onto the region of interest, the wasteful X-ray exposure can be reduced.

  Since the operation display unit 61 that displays the dental arch image 211 that is an image of the dental arch region X is configured by a touch panel that can be operated and input, the dental arch region X displayed as the dental arch image 211 is displayed. The oval CT imaging area CAa can be set directly, and the oval CT imaging area CAa can be set more easily and appropriately.

In addition, since the CT imaging region line 213 indicating the set ellipsoidal CT imaging area CAa is superimposed and displayed on the dental arch image 211 displayed on the operation display unit 61, the dental arch area X is more appropriately lengthened. A circular CT imaging area CAa can be set.
Specifically, since the CT imaging region line 213 indicating the set oval CT imaging area CAa is superimposed on the dental arch image 211 displayed on the operation display unit 61, the set oval CT imaging is performed on the region of interest. It can be visually confirmed that the area CAa is set with an appropriate shape, size, and position. Therefore, the oval CT imaging area CAa can be set more appropriately for the dental arch area X.

  Further, as shown in FIG. 14, on the CT imaging region setting screen 200A, one end and the other end of the region of interest on the curved dental arch region X shown in the dental arch image 211 displayed on the operation display unit 61. Therefore, the ellipse CT imaging area CAa can be appropriately set for the region of interest with a simpler operation.

  In addition, since an oval CT imaging area CAa is set in advance by a combination of two teeth to be specified, the positions of one end and the other end of the region of interest are set in the set oval CT imaging area CAa. The oval CT imaging area CAa corresponding to the designation operation to be performed can be set as the set oval CT imaging area CAa. Therefore, the ellipse CT imaging area CAa can be appropriately set for the region of interest with a simpler operation.

  Further, as shown in FIG. 15, the dental arch image 211 displayed on the operation display unit 61 is divided into a plurality of divided areas 214 on the CT imaging region setting screen 200B, and is divided on the CT imaging region setting screen 200B. Since it is the structure which receives designation | designated operation which selects either of the areas 214, the ellipse CT imaging area | region CAa can be appropriately set with respect to a region of interest with simpler operation.

  Specifically, the CT area setting screen 200 is used to divide the dentition into a plurality of groups, set the divided area 214, and divide and display the dental arch image 211 displayed on the operation display unit 61 into the plurality of divided areas 214. As a result, a designation operation for selecting one of the displayed divided areas 214 is accepted, and the ellipse CT imaging region CAa can be appropriately set for the region of interest by a simpler operation.

  Further, in the CT imaging region setting screen 200D, in order to display the panoramic image 211D about the subject on the image display unit 210D, for example, while confirming the patient-specific state of the subject such as a missing tooth, Thus, an oval CT imaging area CAa can be set. Therefore, it is possible to more appropriately irradiate the region of interest with the X-ray cone beam BX, thereby further reducing the amount of wasted X-ray exposure.

  Further, the axial direction of the turning shaft 31 is the vertical direction, the direction orthogonal to the vertical direction is the horizontal direction, and the irradiation range of the X-ray cone beam BX with respect to the oval CT imaging region CAa is at least in the vertical direction and the horizontal direction. Since the longitudinal shielding plate 14 and the lateral shielding plate 15 that variably shield and regulate the shielding amount are provided in either of them, the oval CT imaging area CAa can be more reliably formed. Therefore, it is possible to reliably reduce the wasteful X-ray exposure dose.

  In addition, since the horizontal direction shielding plate 15 that includes two X-ray shielding plates that respectively move in the horizontal direction and restrict the lateral spread of the X-ray cone beam BX is provided, the horizontal direction of the X-ray cone beam BX is increased. The oval CT imaging region CAa can be more reliably formed while controlling the irradiation direction in the direction. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

  In addition, the vertical shielding plate 14 composed of two X-ray shielding plates that move in the vertical direction and restrict the spread of the X-ray cone beam BX in the vertical direction is provided, whereby the vertical direction of the X-ray cone beam BX is provided. The oval CT imaging region CAa can be more reliably formed while controlling the irradiation direction in the direction. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

  In addition, the vertical position of the vertical shielding plate 14 with respect to the X-ray generation unit 10 is adjusted, and the irradiation direction in the vertical direction of the X-ray cone beam BX is controlled by the main body control unit 60. Even when a local region of interest that is eccentric in the vertical direction with respect to the X-rays irradiated from the X-ray generation unit 10 such as only the lower jaw is set as the CT imaging region CA, the CT imaging region CA is more reliably detected. Can be formed. Therefore, it is possible to reduce the wasteful X-ray exposure amount and reliably perform X-ray CT imaging of the region of interest.

  In addition, since the upper frame 41 that suspends and holds the turning shaft 31 and the turning motor 37 that includes a two-dimensional movement mechanism that moves the turning shaft 31 relative to the upper frame 41 in the two-dimensional direction in the horizontal direction are provided. Even if the set oval CT imaging area CAa is eccentric from the center of the dental arch area X, the spread of the X-ray cone beam BX is more appropriate for the set oval CT imaging area CAa. Can be adjusted.

  Further, the trajectory of the slit-shaped X-ray slit beam BXP extending in the vertical direction formed by the restriction of the vertical shielding plate 14 and the horizontal shielding plate 15 forms an envelope EM in panoramic X-ray photography. Since the turning motor 37 is driven and controlled, the X-ray CT imaging apparatus 1 can reduce the amount of unnecessary X-ray exposure without preparing another X-ray imaging apparatus even when a panoramic image is required. Panoramic X-ray photography is also possible with the line slit beam BXP. Therefore, the versatility of the X-ray CT imaging apparatus 1 that can reduce the wasteful X-ray exposure dose can be improved.

  Further, the beam forming mechanism 13 is controlled so that the CT imaging area CA viewed from the axial direction of the turning shaft 31 of the main body control unit 60 has a substantially oval shape in the longitudinal direction along the longitudinal direction of the dental arch area X. The beam is such that the CT imaging area CA viewed from the configuration or the axial direction of the turning shaft 31 has a substantially semicircular or substantially triangular shape with the apex located in the vicinity of the front tooth T1 and connecting the outer periphery of the dental arch area X. By controlling the beam shaping mechanism 13 by controlling the shaping mechanism 13, the longitudinal direction is along the longitudinal direction of the dental arch area X according to the shape of the set oval CT imaging area CAa. By narrowing to a nearly oval shape, or a semi-circular shape or a triangular shape that connects the outer circumference of the dental arch region X with the apex located near the front tooth T1, it is possible to reduce unnecessary X-ray exposure and detect X-rays Inspection of part 20 It is possible to reduce the range.

  Further, the beam shaping mechanism 13 is controlled so that the CT imaging area CA viewed from the axial direction of the turning shaft 31 of the main body control unit 60 becomes a perfect circle shape in addition to a substantially oval shape and a substantially triangular shape. Thus, an appropriate perfect CT imaging region CAd can be set according to the part and case, and the amount of unnecessary X-ray exposure can be reduced.

  Specifically, for example, when observing whether the wisdom tooth is almost lying on its side in the buried dentition area, when examining the spread of the tumor, or not only in the longitudinal part of the dental arch area X The CT imaging area CA can be selected from a substantially oval shape, a substantially triangular shape, and a perfect circle shape according to various cases and parts such as a diagnosis that requires observation of the region extending on the lingual / cheek side. By comprising, the useless X-ray exposure amount irradiated to places other than the region of interest can be reduced. Therefore, the versatility of the X-ray CT imaging apparatus 1 that can reduce the wasteful X-ray exposure dose can be improved.

  In addition, X-ray CT imaging of the CT imaging area CA may be performed by normal scan CT or may be performed by offset scan CT. In normal scan CT, all projection data obtained during X-ray CT imaging is transmission image data of the entire CT imaging area CA obtained by irradiating the entire CT imaging area CA with the X-ray cone beam BX. .

  On the other hand, in the offset scan CT, the irradiation range of the X-ray cone beam BX irradiated to the CT imaging area CA is limited in the x direction with respect to the normal scan CT, and the X-ray cone beam BX is a part of the CT imaging area CA. The positional relationship of irradiating only the area of the part is realized. All projection data obtained during X-ray CT imaging is transmission image data of a partial area of the CT imaging area CA obtained by irradiating only a partial area of the CT imaging area CA with the X-ray cone beam BX. is there.

  However, since reconstruction of the CT image requires projection data with different projection angles of 180 degrees for all points in the CT imaging area CA, in the case of offset scanning CT, the swivel arm 30 is swung 360 degrees or more to perform CT. Projection data with different projection angles of 180 degrees is obtained for all points in the imaging area CA.

  Examples of offset scan CT are shown in, for example, FIGS. 3A to 4D of Japanese Patent Registration No. 4516626, FIGS. 16 to 20 of Japanese Patent Application Laid-Open No. 2008-114056, and FIGS. 2A to 12 of International Publication No. 2009/063974. Has been.

  According to the offset scan CT, it is only necessary to have an X-ray detection surface that can detect the X-ray cone beam BX that has passed through only a part of the CT imaging area CA. There is an advantage that X-ray CT imaging of a wide CT imaging area CA can be performed with the instrument 21.

In correspondence between the configuration of the present invention and the above-described embodiment,
The X-ray restricting portion of the present invention corresponds to the beam shaping mechanism 13,
Similarly,
The X-ray detector corresponds to the X-ray detector 21 in the X-ray detector 20,
The support corresponds to the swivel arm 30,
The support driving unit corresponds to the turning motor 37 and the shaft moving mechanism 34,
The display means corresponds to the operation display unit 61,
The CT imaging area corresponds to a CT imaging area CA, an oval CT imaging area CAa, an elliptical CT imaging area CAb, a substantially triangular CT imaging area CAc, and a perfect circular CT imaging area CAd,
The CT imaging region setting means corresponds to the CT imaging region setting screen 200 and the local perfect circular CT imaging region setting screen 300.
The X-ray restriction control unit and the drive control unit correspond to the main body control unit 60,
The setting area image corresponds to the CT imaging area line 213,
The captured panoramic image corresponds to the panoramic image 211D,
X-ray shielding means corresponds to a part of the longitudinal shielding plate 14, the lateral shielding plate 15 and the L-shaped shielding plate 18,
The lateral restriction shielding plate corresponds to the lateral shielding plate 15, the left lateral shielding plate 15a, the right lateral shielding plate 15b,
The longitudinal restriction shielding plate corresponds to the longitudinal shielding plate 14, the upper longitudinal shielding plate 14a, and the lower longitudinal shielding plate 14b,
The support holding means corresponds to the upper frame 41,
The subject holding means corresponds to the subject fixing unit 421. However, the present invention is not limited to the configuration of the above-described embodiment, and many embodiments can be obtained.

  For example, in the above description, the aspect in which the X-ray CT imaging apparatus 1 performs X-ray CT imaging using the X-ray CT imaging apparatus 1 as an imaging target for the entire dental arch region X configured by the front teeth T1, the left molars T2, and the right molars T3 has been described. The detection surface may be configured to be movable with respect to the X-ray detection unit main body. Thereby, the detection surface comprised with an expensive sensor can be formed small.

  In addition, on the CT imaging area setting screen or the like, the CT imaging area line 213 displayed on the image display unit 210 is held by an operation means such as a mouse, and the size or shape of the CT imaging area line 213 is changed to obtain a CT imaging area. The structure which sets CA may be sufficient.

  In the above description, X-ray CT imaging was performed using the dental arch region X, which is a dental region, as the imaging object OB, but X-ray CT imaging may be performed using only the temporomandibular joint as the imaging object OB. Furthermore, X-ray CT imaging may be performed not only in the dental region but also in local areas such as the limbs and the head and neck.

DESCRIPTION OF SYMBOLS 1 ... X-ray CT imaging apparatus 10 ... X-ray generation part 13 ... Beam shaping mechanism 14 ... Vertical shield 14a ... Upper vertical shield 14b ... Lower vertical shield 15 ... Lateral shield 15a ... Left lateral Shield plate 15b ... right side shield plate 18 ... L-type shield plate 20 ... X-ray detector 21 ... X-ray detector 30 ... swivel arm 31 ... swivel shaft 34 ... shaft moving mechanism 37 ... drive portion swivel motor 41 ... top Frame 61 ... Operation display section 200 ... CT imaging area setting screen 211 ... Dental arch image 211D ... Panorama image 213 ... CT imaging area line 214 ... Divided area 300 ... Local perfect circular CT imaging area setting screen 421 ... Subject fixing section BX ... X-ray cone beam BX1 ... X-ray cone beam BX2 for large irradiation field CT ... X-ray cone beam BXP for small irradiation field CT ... X-ray slit beam CA ... CT imaging area CAa ... Oval CT Shadow region CAb ... elliptical CT imaging area CAc ... generally triangular CT imaging area CAd ... perfect circle CT imaging area M1 ... object T1 ... anterior X ... dental arch area

Claims (17)

An X-ray generator for generating X-rays;
An X-ray regulating unit that regulates an irradiation range of the X-rays generated from the X-ray generator to form an X-ray cone beam;
An X-ray detector for detecting the X-ray cone beam irradiated on the subject;
A support that supports the X-ray generator and the X-ray detector in a state of facing each other with the subject interposed therebetween;
A support drive unit that drives at least the support to rotate around the axis of the rotation axis, and rotates the X-ray generator and the X-ray detector around the subject ;
C T imaging region so as to be substantially oval or adapted substantially triangular in shape of the dental arch region having a longitudinal direction along the dental arch area, according to the CT imaging area, said pivoting An X-ray CT imaging apparatus comprising: an X-ray restriction control unit that variably controls the restriction of the X-ray restriction unit in the lateral direction orthogonal to the axial direction of the axis during imaging. Display means for displaying a dental arch image which is an image of a dental arch region;
CT imaging region setting means for receiving a CT imaging region setting operation for the dental arch region,
The X-ray CT imaging apparatus according to claim 1, wherein a setting area image indicating the setting CT imaging area is superimposed and displayed on the dental arch image displayed on the display unit. The CT imaging region setting means;
3. The configuration according to claim 2 , wherein a designation operation for designating positions of one end and the other end of a region of interest on a curved curve of the curved dental arch region shown in the dental arch image displayed on the display unit is received. X-ray CT imaging device. The dental arch image to be displayed on the display means is displayed divided into a plurality of divided areas,
The CT imaging region setting means;
The X-ray CT imaging apparatus according to claim 2 , wherein a designation operation for selecting any one of the divided areas is received. The dental arch image,
The X-ray CT imaging apparatus according to claim 1, wherein the panoramic image has been captured for the subject. The axial direction of the pivot axis is the vertical direction ,
The X-ray restriction part
6. An X-ray shielding means for restricting an irradiation range of the X-ray cone beam with respect to the CT imaging region by variably shielding a shielding amount in at least one of the vertical direction and the horizontal direction. X-ray CT imaging apparatus according to any one of the above. The X-ray shielding means;
The X-ray CT imaging according to claim 6, wherein each of the X-ray CT scans is configured by a lateral restriction shielding plate including two X-ray shielding plates that respectively move in the lateral direction and restrict the spread of the X-ray cone beam in the lateral direction. apparatus. In the X-ray shielding means,
The X-ray according to claim 6 or 7, further comprising a longitudinal restriction shielding plate made of two X-ray shielding plates that respectively move in the longitudinal direction and restrict the spread of the X-ray cone beam in the longitudinal direction. CT imaging device. The vertical irradiation position adjusting means for adjusting the vertical irradiation position of the X-ray cone beam by adjusting the vertical position of the vertical restriction shielding plate with respect to the X-ray generator. X-ray CT imaging apparatus described in 1. The axial direction of the pivot axis is the vertical direction, and the direction perpendicular to the vertical direction is the horizontal direction,
A support holding means for hanging and holding the pivot shaft;
The said support body drive part which comprises the said support body drive part which consists of a two-dimensional movement mechanism which moves the said rotational axis relatively to the two-dimensional direction in the said horizontal direction with respect to the said support body holding means. X-ray CT imaging device. The axial direction of the pivot axis is the vertical direction, and the direction perpendicular to the vertical direction is the horizontal direction,
Subject holding means for holding the subject;
10. The support driving unit according to claim 1, further comprising a two-dimensional movement mechanism that includes a two-dimensional movement mechanism that moves the subject holding unit relative to the pivot axis in a two-dimensional direction in the horizontal direction. X-ray CT imaging device. The support driving unit is driven and controlled so that the locus of the slit-shaped X-ray slit beam extending in the vertical direction formed by the restriction of the X-ray shielding means forms an envelope in panoramic X-ray photography. The X-ray CT imaging apparatus according to claim 10 or 11, further comprising a drive control unit. The X-ray restriction control unit;
2. The X-ray restricting portion is controlled such that the CT imaging region viewed from the axial direction of the pivot axis has a substantially oval shape in the longitudinal direction along the longitudinal direction of the dental arch region. The X-ray CT imaging apparatus according to any one of 1 to 12. The X-ray restriction control unit;
The CT imaging area as viewed from the axial direction of the pivot axis, and the top portion is positioned in front teeth near the X-ray restriction portion so as to be substantially elliptic shape or a substantially triangular shape connecting the outer circumference of the dental arch region The X-ray CT imaging apparatus according to claim 1, wherein the X-ray CT imaging apparatus is configured to be controlled. The X-ray restriction control unit;
The X-ray restricting portion is controlled so that the CT imaging region viewed from the axial direction of the pivot axis becomes a perfect circle shape in addition to at least one of the substantially oval shape and the substantially triangular shape. The X-ray CT imaging apparatus according to claim 1. As C T imaging region is substantially oval or adapted substantially triangular in shape of the dental arch region having a longitudinal direction along the dental arch region, X-rays generated which are opposed across the subject with pivot support for supporting the vessel and the X-ray detector around the front Symbol object, according to the CT imaging area, the transverse direction of the X-ray restriction perpendicular to the axial direction of the pivot axis the support is pivoted X-ray CT imaging method with an X-ray restriction steps of variably controlling the regulations parts during shooting. An image display step of displaying a dental arch image that is an image of the dental arch region on the display means;
A setting operation reception step for receiving a setting operation of a CT imaging region for the dental arch region;
The X-ray CT imaging method according to claim 16, further comprising a superimposing display step of superimposing and displaying a setting area image indicating the setting CT imaging area on the dental arch image displayed on the display unit after the setting operation reception step. .