JP2020014662A - X-ray ct scanner - Google Patents

Abstract

To configure an X-ray generator to rotate around a subject as closely as possible thereto, while inhibiting the X-ray generator and an X-ray detector from coming into contact with the subject.SOLUTION: While an imaging region R is captured by X-ray CT imaging, an X-ray generator 22 and an X-ray detector 24 are rotatingly moved around a head part P within a rotating range of 270° or less, the X-ray detector 24 passes a side where the imaging region R is eccentrically located in the head part P, out of the periphery of the head part P, and the X-ray generator 22 passes an opposite side of the eccentrically-located side, out of the periphery of the head part P, so that the X-ray detector 24 forms an arc-shaped X-ray detection trajectory Or by the rotating movement. When the imaging region R set by an imaging region positioning part 40 is eccentric to any of the left/right with respect to a midline Mc of the head part P, the rotating range of a rotation support part 20 is set such that a central part OrM of the arc of the X-ray detection trajectory Or is eccentric to the same side with respect to the midline Mc as the eccentrically-located side of the imaging region R.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray CT imaging apparatus that performs X-ray imaging by rotating an X-ray generator and an X-ray detector around a subject.

  Patent Literature 1 discloses an X-ray CT imaging apparatus including a turning mechanism and a moving mechanism. The turning mechanism turns the turning means, in which the X-ray generator and the X-ray detector are arranged to face each other across the subject, about the turning axis. The moving mechanism moves the turning axis and / or the subject in a plane perpendicular to the turning axis. In this X-ray CT imaging apparatus, the center of the region of interest of the subject is always photographed differently from the turning axis of the turning mechanism by the combined movement of the turning means and the turning axis and / or the movement of the subject. The turning means is turned as the center of rotation of. Thereby, the magnification can be changed by relatively changing the distance between the X-ray generator and the rotation center and / or the distance between the X-ray detector and the rotation center.

  Patent Document 2 discloses that an X-ray generator and an X-ray detector are rotated when the X-ray CT imaging is performed by rotating the X-ray generator and the X-ray detector around the subject at a rotation angle of 180 degrees or more and less than 360 degrees. The turning drive unit is moved so that the X-ray generator moves on an orbit where the scattering degree of X-rays between the X-ray detector and the imaging target area is larger than the scattering degree between the X-ray detector and the imaging target area. A control technique is disclosed.

JP 2007-029168 A JP 2011-194032A

  As disclosed in Patent Document 1, if an X-ray generator is brought close to an imaging region and X-ray CT imaging is performed at a small magnification, a clear X-ray CT image can be obtained.

  However, in this case, since the X-ray generator turns near the subject, the X-ray generator may come into contact with the subject.

  In Patent Literature 2, since the X-ray generator and the X-ray detector pass through a position sufficiently distant from the subject regardless of the position of the imaging target area and the turning range, it is difficult to obtain a clear X-ray CT image. It is.

  Therefore, the present invention suppresses the contact between the X-ray generator and the X-ray detector that rotates around the subject, and makes the X-ray generator rotate as close to the subject as possible. It is an object to provide a clear X-ray CT image.

  In order to solve the above problems, an X-ray CT imaging apparatus according to a first aspect includes an X-ray generator that generates X-rays, an X-ray detector that detects the X-rays, the X-ray generator, A turning support mechanism that is supported so that the X-ray detector faces the subject with the head interposed therebetween, a turning drive mechanism that includes a turning mechanism that turns the turning support section, and a dental arch of the head. An imaging region position setting unit that receives a setting of a position of an X-ray CT imaging region in which a local region that is a region of the unit is subjected to X-ray CT imaging, and a turning control unit that controls the turning driving mechanism, While the turning control unit drives and controls the turning drive mechanism to perform X-ray CT imaging of the X-ray CT imaging area by the X-ray, the X-ray generator and the X-ray detector are moved around the head. The X-ray detector is turned in a turning range of 270 ° or less, and the X-ray detector is Of the periphery, the X-ray CT imaging region passes on the side unevenly distributed in the head, and the X-ray generator passes around the head on the side opposite to the unevenly distributed side, During X-ray CT imaging, the X-ray detector forms an X-ray detection trajectory of an arc by the turning movement, and the X-ray CT imaging area set by the imaging area position setting unit is positioned with respect to the center of the head. The center of the arc of the X-ray detection trajectory is biased toward the same side as the X-ray CT imaging area is biased with respect to the median. Thus, the turning range of the turning support portion is set.

  A second aspect is the X-ray CT imaging apparatus according to the first aspect, wherein the turning drive mechanism drives the turning support unit to set the turning range of 270 ° or less to 180 ° or 180 °. The X-ray generator and the X-ray detector are turned around the head in a turning range of an angle obtained by adding the spreading angle of the X-ray beam.

  A third aspect is the X-ray CT imaging apparatus according to the first or second aspect, wherein the X-ray detection trajectory is an arc trajectory having no concave portion toward the X-ray CT imaging area. To form.

  A fourth aspect is the X-ray CT imaging apparatus according to any one of the first to third aspects, wherein the X-ray CT imaging area set and received by the imaging area position setting unit targets an anterior tooth area In this case, the turning range of the turning support unit is set so that the center of the arc of the X-ray detection trajectory is located on the front side of the head on the plane including the median.

  A fifth aspect is the X-ray CT imaging apparatus according to any one of the first to fourth aspects, wherein a maximum distance of the surface of the head with respect to the center of the X-ray CT imaging area is provided. The turning diameter of the X-ray detector with respect to the center of the X-ray CT imaging area is set to be smaller than the maximum distance.

  A sixth aspect is the X-ray CT imaging apparatus according to any one of the first to fifth aspects, wherein the turning drive mechanism moves a turning axis on a mechanism that turns the turning support unit. A turning axis moving mechanism for moving in a direction intersecting the axial direction of the upper turning axis is included.

  A seventh aspect is the X-ray CT imaging apparatus according to the sixth aspect, wherein when performing X-ray CT imaging in the turning range of 270 ° or less, the setting received by the imaging region position setting unit is accepted. The position of the turning axis on the mechanism is moved according to the position of the X-ray CT imaging area, and the X-ray CT imaging is performed with the turning axis on the mechanism fixed at the center of the X-ray CT imaging area. Things.

  An eighth aspect is the X-ray CT imaging apparatus according to the sixth or seventh aspect, wherein the turning mechanism turns the turning support unit around a turning axis on the mechanism, The X-ray generator and the X-ray detector move the turning axis on the mechanism to cause the turning support unit to perform a synthetic motion, so that the X-ray generator and the X-ray detector can move the X-ray CT imaging area. The operation of turning around the center is enabled.

  A ninth aspect is the X-ray CT imaging apparatus according to the eighth aspect, further comprising a turning range setting unit configured to receive the setting of the turning range of 270 ° or less and the setting of the turning range of 360 ° or more. Assuming a maximum distance of the surface of the head with respect to the center of the X-ray CT imaging region, when a turning range of 360 ° or more is set by the turning range setting unit, the center of the X-ray CT imaging region is set. And the distance between the X-ray generator and the distance between the center of the X-ray CT imaging region and the X-ray detector, the smaller of which is the separation distance, the imaging region position setting unit The position of the turning axis on the mechanism with respect to the center of the X-ray CT imaging area is controlled such that the separation distance is greater than the maximum distance according to the set position of the X-ray CT imaging area. is there.

  A tenth aspect is the X-ray CT imaging apparatus according to the ninth aspect, wherein the turning range setting unit sets the turning range of the 270 ° or less to 180 ° or the spread of the X-ray beam irradiation at 180 °. A turning range of an angle obtained by adding the angle is received, and a turning range of 360 ° is received as the turning range of 360 ° or more.

  According to the first aspect, the X-ray generator and the X-ray detector are turned around the head in a turning range of 270 ° or less, and the X-ray detector is turned around the head. The X-ray CT area passes on the side of the head that is unevenly distributed, and the X-ray generator passes on the side of the head opposite to the unevenly distributed side. During X-ray CT imaging, the X-ray detector turns. An X-ray detection trajectory of an arc is formed by movement, and X-ray detection is performed when the X-ray CT imaging area set by the imaging area position setting unit is at a position deviated to the left or right with respect to the median head. In order to set the turning range of the turning support unit so that the center of the arc of the orbit is located on the same side as the X-ray CT imaging area is shifted with respect to the median, an X-ray generator and The contact of the X-ray detector with the head can be suppressed. Further, by setting the turning range as described above, it is possible to suppress the X-ray detector from coming into contact with the head. As a result, the X-ray detector can be turned as close as possible to the subject, and the X-ray detector is as sharp as possible. A line CT image can be obtained.

  According to the second aspect, it is possible to prevent the X-ray generator and the X-ray detector rotating around the subject from coming into contact with the subject when performing a half scan by CT imaging.

  According to the third aspect, since the X-ray detection trajectory is formed as an arc trajectory having no concave portion toward the X-ray CT imaging region, the X-ray detector is less likely to shake.

  According to the fourth aspect, when the X-ray CT imaging region set and received by the imaging region position setting unit targets the anterior tooth region, the center of the arc of the X-ray detection trajectory is set on the plane including the median. The X-ray generator and X-ray detector are prevented from coming into contact with the head even when X-ray CT imaging of the front teeth is performed to set the turning range of the turning support part so that it is located on the front side of the head. it can.

  According to the fifth aspect, when assuming the maximum distance of the surface of the head to the center of the X-ray CT imaging region, the diameter of the rotation of the X-ray detector with respect to the center of the X-ray CT imaging region is larger than the maximum distance. Since the X-ray detector is set to be small, it is possible to turn the X-ray detector as close to the subject as possible, and it is possible to obtain as clear an X-ray CT image as possible.

  According to the sixth aspect, the turning support is turned while the turning axis on the mechanism is maintained at a fixed position, or the turning mechanism turns the turning support about the turning axis on the mechanism. Then, the turning axis moving mechanism moves the turning axis on the mechanism to cause the turning support section to perform a synthetic motion, thereby connecting the X-ray generator and the X-ray detector to the X-ray CT imaging region. By turning around the center, the turning trajectory of the X-ray generator and the X-ray detector can be adjusted.

  According to the seventh aspect, when performing X-ray CT imaging in a turning range of 270 ° or less, the position of the turning axis on the mechanism according to the position of the X-ray CT imaging area set and received by the imaging area position setting unit. The X-ray generator and X-ray detector can turn on a stable trajectory because the X-ray generator and the X-ray detector are rotated to fix the rotation axis on the mechanism at the center of the X-ray CT imaging area and perform X-ray CT imaging. Thus, an X-ray CT image as clear as possible can be obtained.

  According to the eighth aspect, in synchronization with the turning mechanism turning the turning support section about the turning axis on the mechanism, the turning axis moving mechanism moves the turning axis on the mechanism and synthesizes the turning support section with the turning support section. By performing the movement, the X-ray generator and the X-ray detector perform an orbiting operation around the center of the X-ray CT imaging region, so that the X-ray generator and the X-ray detector have an orbital diameter. Adjustment and the like become possible.

  According to the ninth aspect, when a turning range of 360 ° or more is set, the position of the turning axis on the mechanism with respect to the center of the X-ray CT imaging region is set so that the separation distance becomes larger than the maximum distance. By controlling, it is possible to suppress the X-ray generator and the X-ray detector rotating around the subject from coming into contact with the subject.

  According to the tenth aspect, when performing a full scan by 360 ° CT imaging and a half scan by 180 ° CT imaging, the X-ray generator and the X-ray detector rotating around the subject come into contact with the subject. Can be suppressed.

FIG. 1 is a schematic diagram illustrating an X-ray CT imaging apparatus according to a first embodiment. 5 is a flowchart illustrating a processing example by a turning control unit. It is the schematic which shows the whole structure of the X-ray CT imaging apparatus which concerns on 2nd Embodiment. It is a schematic bottom view which shows a turning drive mechanism. FIG. 2 is a block diagram illustrating an electrical configuration of the X-ray CT imaging apparatus. It is a flowchart which shows the example of a process by a photography program. FIG. 7 is a diagram illustrating a display example on the operation panel device. FIG. 7 is a diagram illustrating a display example on the operation panel device. It is a figure showing the example of a reference table. It is explanatory drawing which shows the example of a setting of a turning range. It is a figure which shows a turning operation example. It is a figure which shows a turning operation example. It is a figure which shows a turning operation example. It is a figure showing the example of turning operation concerning a modification. It is a figure which shows the turning operation example which concerns on another modification. It is a figure which shows the turning operation example which concerns on another modification. It is a block diagram showing the electric composition of the X-ray CT imaging device concerning a 3rd embodiment. It is a flowchart which shows the example of a process by a photography program. FIG. 7 is a diagram illustrating a display example on the operation panel device. FIG. 7 is a diagram illustrating a display example on the operation panel device. It is a figure showing the example of a reference table. It is a figure which shows a turning operation example. It is a figure which shows a turning operation example. 9 is a flowchart illustrating a processing example according to a photographing program according to a modification. FIG. 7 is a diagram illustrating a display example on the operation panel device. FIG. 7 is a diagram illustrating a display example on the operation panel device. It is a figure showing the example of a reference table. It is a figure which shows a turning operation example. It is a figure which shows a turning operation example. It is a figure which shows the turning operation example which concerns on another modification. It is a figure which shows the turning operation example which concerns on another modification. It is a figure which shows the example of a movement trace by the movement of an X-ray detector. It is a figure showing another example of a trace of movement by movement of an X-ray detector. It is a figure showing a detector existence field and a safety field. FIG. 34 is a diagram showing a detector presence area and a safety area in the example shown in FIG. 33. It is a figure showing a detector existence field and a safety field in another example.

<< 1st Embodiment >>
Hereinafter, a medical X-ray CT imaging apparatus based on the embodiment will be described. FIG. 1 is a schematic diagram showing an X-ray CT imaging apparatus 10.

  The X-ray CT imaging apparatus 10 is an apparatus that performs X-ray CT (Computed Tomography) imaging of the head P of a subject, and includes a turning support unit 20, a turning drive mechanism 30, an imaging region position setting unit 40, and a turning control. And a unit 60.

  The turning support unit 20 supports the X-ray generator 22 and the X-ray detector 24 so as to face each other across the head P of the subject. The X-ray generator 22 generates X-rays (X-ray beams). The X-rays generated by the X-ray generator 22 may be formed into an X-ray cone beam by the restriction unit. The X-ray detector 24 detects the X-rays emitted from the X-ray generator 22. The X-ray generator 22 and the X-ray detector 24 are supported by the turning support unit 20 with a space between which the head P can be arranged. Then, the X-rays emitted from the X-ray generator 22 pass through the head P and enter the X-ray detector 24. The X-ray incident on the X-ray detector 24 is converted into an electric signal corresponding to the intensity of the X-ray for each unit pixel. An X-ray CT image or the like is generated based on each electric signal.

  The turning drive mechanism 30 includes a turning mechanism 32.

  The turning mechanism 32 turns the turning support section 20 about a turning axis X1 on a mechanism located between the X-ray generator 22 and the X-ray detector 24. For example, the turning mechanism 32 includes an electric motor and, if necessary, includes an acceleration / deceleration mechanism such as a gear. The turning mechanism 32 rotatably supports a shaft 33 projecting from the turning support 20 at a position between the X-ray generator 22 and the X-ray detector 24. The central axis of the shaft portion 33 is the turning axis X1 on the mechanism. Then, by the driving of the turning mechanism 32, the turning support portion 20 turns around the turning axis X1 on the mechanism. The swivel mechanism 32 may have any configuration as long as the swivel support unit 20 is swiveled about a swivel axis X1 on the mechanism.

  Here, when performing X-ray CT imaging under the control of the turning control unit 60, the turning mechanism 32 rotates the X-ray generator 22 and the X-ray detector 24 around the head P at a turning angle of 270 ° or less. It is possible to turn. For example, when performing X-ray CT imaging, the X-ray generator 22 and the X-ray detector 24 may be turned around the head P by 360 °, or may be turned at 270 ° or less (for example, 180 °). There can be. The turning angles of the X-ray generator 22 and the X-ray detector 24 are fixed at one angle of 270 ° or less (for example, 180 °), and are set at 270 ° or less (for example, 180 °). In some cases, the user can select the set angle and the turning angle of 360 ° by setting of the user. The turning mechanism 32 only needs to be able to turn the X-ray generator 22 and the X-ray detector 24 around the head P at 270 ° or less (for example, 180 °) when performing X-ray CT imaging. When rotating the X-ray generator 22 and the X-ray detector 24 around the head P by 270 ° or less (for example, 180 °), the X-ray detector 24 close to the head P By determining the turning range so as not to turn on the side of the part P farthest from the imaging region R, contact between the X-ray detector 24 and the head P can be avoided.

  When driving the turning support unit 20, the turning drive mechanism 30 sets the turning range of 270 or less to 180 ° or an angle obtained by adding the divergence angle of the irradiation of the X-ray beam to 180 ° (see an angle β in FIG. 15 described later). The X-ray generator 22 and the X-ray detector 24 may be turned around the head P in the turning range of. This makes it possible to prevent the X-ray generator 22 and the X-ray detector 24 rotating around the head P from coming into contact with the head P when performing a half scan by CT imaging around 180 °.

  Further, under the control of the turning control unit 60, the turning mechanism 32 causes the X-ray detector 24 to pass through the side of the head P where the imaging region R is unevenly distributed in the head P, and the X-ray generator 22 The X-ray generator 22 and the X-ray detector 24 pass through the side opposite to the side where the imaging region R is unevenly distributed in the head P and perform X-ray CT imaging. Swivel around head P. At this time, the state where the X-ray detector 24 is positioned closer to the imaging region R than the X-ray generator 22 is maintained.

  The state in which the X-ray detector 24 is kept closer to the imaging region R than the X-ray generator 22 means that the turning axis X1 is at the center A of the imaging region R during the turning. Assuming that the coincident state is maintained, it means that the turning axis X1 is closer to the X-ray detector 24 than the X-ray generator 22.

  Here, a maximum distance LD of the surface of the head P with respect to the center of the imaging region R is assumed (see FIG. 1). This maximum distance LD is the maximum distance LD around the entirety of the head P regardless of the turning range of the X-ray detector 24. Also, consider the turning diameter q of the X-ray detector 24 with respect to the center A of the imaging region R (see FIG. 1). Assuming that the X-ray detector 24 is turned while the turning axis X1 is coincident with the center A of the imaging region R, the turning diameter q is equal to the distance between the turning axis X1 and the X-ray detector 24. That is, in this case, the turning diameter q is fixedly determined by the structure of the turning support portion 20 itself. The turning diameter q is smaller than the maximum distance LD. Thereby, the X-ray detector 24 can be closer to the imaging region R than the X-ray generator 22, and the X-ray CT image can be sharpened.

  However, in this case, the X-ray detector 24 comes into contact with the head P depending on the turning range of the X-ray detector 24 around the head P. Therefore, when such a turn is performed, the turn range of the X-ray detector 24 is adjusted as described later.

  As will be described in a later embodiment, there may be a mode in which the turning axis X1 is turned around the center A of the imaging region R in synchronization with the turning of the X-ray generator 22 and the X-ray detector 24. In this case, the distance of the X-ray detector 24 from the virtual turning axis, which is the center when the X-ray generator 22 and the X-ray detector 24 turn, is the turning diameter q. That is, the turning diameter q in this case depends on the configuration of the turning support portion 20 itself (particularly, the distance between the turning axis X1 and the X-ray detector 24), and the turning mode of the X-ray detector 24 (particularly, the turning axis X1). (Diameter of turning).

  An X-ray CT imaging region R (hereinafter, sometimes simply referred to as an imaging region R) is a region to be subjected to X-ray CT imaging. An area that is not a whole area but a partial area of the subject in the XY direction when viewed from the Z direction, such as a part in front of the head P, is referred to as a local area. The imaging region position setting unit 40 is configured to be able to accept the setting of the local region, which is a part of the dental arch of the head P, as the X-ray CT imaging region R. The setting of the position of the imaging region R can be performed, for example, by designating a schematic dental arch image through a pointing device such as a touch panel or a mouse. The dental arch image may be based on an actually captured X-ray image. The dental arch image may be an image in which the dental arch is viewed in a plan view, or may be an image in which the dental arch is viewed in a front view or a side view. The designation of the position may be made through the direction key. In addition, the setting of the position of the imaging region R may be performed by designating or selecting one or more tooth formulas. The tooth formula is a formula in which each tooth is distinguished by a number or the like. The tooth type may be a Japanese type tooth type, an FDI type (Two-digit system) type tooth type, or an American type (Universal system) type tooth type. The above settings are made by the operator. The imaging region position setting unit 40 sets the position of the imaging region R to the turning control unit 60 based on the received position setting of the imaging region R.

  Examples of the position setting of the imaging region R with respect to the dental arch include a case where a molar region on one side is a part of the dental arch and a front tooth region which is a part of the dental arch. For example, when a molar on one side of the dental arch is designated as the imaging region R, a part of the dental arch at a position deviated to the left or right of the head P is used as the CT imaging region R as an X-ray CT. This is an example of a case where shooting is performed. In FIG. 1, the left side is the front side of the head P, the right side is the back side of the head P, and the molar region on one side (left side) of the dental arch is set as the imaging region R. I have. The imaging region position setting unit may be any interface as long as it can accept the setting of the position of the imaging region on a plane orthogonal to the turning axis X1 on the mechanism.

  The imaging region R may be, for example, the following region when viewed from the Z direction. For example, the imaging region R may be an entire head region or a local head imaging region (also referred to as a local head region) that is a partial region of the head. Hereinafter, examples of the head local imaging region include the entire dental arch, the entire jaw region, the dental arch local imaging region that is a partial region of the dental arch region (also referred to as the dental arch local region), the jaw. It is conceivable that the region is a jaw local imaging region (also referred to as a jaw local region) which is a part of the region.

  The turning control unit 60 controls the turning mechanism 32. The turning control unit 60 includes at least one processor. For example, the turning control unit 60 is configured by a computer including at least one processor, a RAM (Random Access Memory), a storage unit, an input / output unit, and the like. The storage unit is configured by a nonvolatile storage device such as a flash memory or a hard disk device, and stores a turning control program for controlling the turning mechanism 32 and the like. The RAM serves as a work area when at least one processor performs a predetermined process. The input / output unit is connected to the turning mechanism 32, the photographing area position setting unit 40, and the like. Then, at least one processor performs predetermined arithmetic processing in accordance with the turning control program stored in the storage unit, and controls the turning mechanism 32 according to the set position of the imaging region R.

  FIG. 2 is a flowchart showing a process performed by the turning control unit 60.

  That is, when performing X-ray CT imaging, the position of the imaging region R is set through the imaging region position setting unit 40 in step S1. The contents for which the position of the imaging region R can be set include the position setting for a part of the dental arch that is deviated to the right or left from the longitudinal axis of the head P. For example, it is possible to set a position for a right molar or a left molar which is a part of a dental arch.

  Thereafter, in the next step S2, the turning range is determined according to the position of the photographing region R set by the photographing region position setting unit 40.

  The turning range is expressed by, for example, from which position to which position the X-ray generator 22 and the X-ray detector 24 are turned around the head P. When a position is set to perform X-ray CT imaging with a part of the dental arch located at a position deviated to the right or left of the head P as the imaging region R, the X-ray generator 22 is set in accordance with the position. And the turning range of the X-ray detector 24 (that is, the turning support unit 20) is determined. Since the X-ray generator 22 and the X-ray detector 24 are located opposite to each other with the rotation axis X1 interposed therebetween, when the rotation range of the X-ray generator 22 is determined, the X-ray detector 24 When the turning range of the X-ray generator 22 is determined, the turning range of the X-ray detector 24 is also determined.

  Here, when the turning control unit 60 drives and controls the turning drive mechanism 30 to perform X-ray CT imaging of the imaging region R by X-rays, the X-ray generator 22 and the X-ray detector 24 Consider a case where the robot is turned around in a turning range of 270 ° or less. In this case, if the X-ray detector 24 is turned while the X-ray detector 24 is closer to the head P than the X-ray generator 22, a clearer X-ray CT image can be obtained. Therefore, it is preferable that the X-ray detector 24 pass through the side of the head P where the imaging region R is unevenly distributed in the head P. Conversely, the X-ray generator 22 may pass around the head P on the side opposite to the side where the imaging region R is unevenly distributed in the head P. Thus, the X-ray detector 24 may form the X-ray detection trajectory Or of the arc by the turning movement.

  For example, when the photographing region R is the front teeth, the photographing region R is unevenly distributed on the front side of the head P. Therefore, it is preferable that the X-ray detector 24 pass the front side of the head P and the X-ray generator 22 pass the rear side of the head P. Further, for example, when the imaging region R is a right molar (or a left molar), the imaging region R is unevenly distributed to the front right of the head P (or to the left front). Therefore, the X-ray detector 24 preferably passes rightward (or left front) of the head P, and the X-ray generator 22 preferably passes leftward (backward right) of the head P.

  It is also assumed that the photographing region R set by the photographing region position setting unit 40 is located at a position deviated left or right with respect to the median Mc of the head P. Here, the median Mc of the head P refers to a line or a plane including a left-right symmetric axis in the head P (the median Mc is illustrated in FIG. 1). When a part of the dental arch located at a position deviated to the left or right of the head P is set as the imaging region R, the part farthest from the center of the imaging region R around the head P is located at the position. Will be different.

  When the X-ray detector 24 turns around the head P while maintaining the state where the X-ray detector 24 is located closer to the imaging region R than the X-ray generator 22, the X-ray detector 24 performs imaging around the head P. If the user tries to turn the point farthest from the center of the region R, the X-ray detector 24 may come into contact with the head P. Therefore, the turning range of the turning support unit 20 is set so that the center portion OrM of the arc of the X-ray detection trajectory Or is located on the same side as the side on which the imaging region R is offset with respect to the median Mc. . Here, the center part OrM of the arc of the X-ray detection trajectory Or is the center of both ends in the X-ray detection trajectory Or. The arc formed by the X-ray detection trajectory Or does not need to be a continuous arc having the same curvature portion.

  For example, when the left molar is designated as the imaging region R, the imaging region R is biased to the left with respect to the median Mc. In such a case, the turning range of the turning support unit 20 is set so that the center portion OrM of the arc of the X-ray detection trajectory Or is located to the left with respect to the median Mc.

  Thus, the X-ray detector 24 can turn around the head P while avoiding a location far from the center of the imaging region R while approaching the imaging region R as much as possible. Further, when the left molar is designated as the imaging region R, the portion farthest from the center of the imaging region R around the head P exists on the right side of the head P. Since the X-ray generator 22 is relatively far from the imaging region R, it does not easily come into contact with the head P even if the X-ray generator 22 is turned around the head P and around a location far from the center of the imaging region R (X in FIG. 1). (See the arrow showing the movement locus of the line generator 22).

  Further, for example, when the right molar is designated as the imaging region R, the imaging region R is biased to the right with respect to the median Mc. In such a case, the turning range of the turning support unit 20 is set so that the center portion OrM of the arc of the X-ray detection trajectory Or is located to the right with respect to the median Mc.

  Accordingly, similarly to the above, the X-ray detector 24 can turn around the head P while avoiding a part far from the center of the imaging region R while approaching the imaging region R as much as possible. Further, since the X-ray generator 22 is relatively far from the imaging region R, it does not easily come into contact with the head P even if the X-ray generator 22 is turned around a location far from the center of the imaging region R around the head P.

  When a part of the dental arch is set as the imaging region R, the imaging region R set by the imaging region position setting unit 40 is located at a position deviated left or right with respect to the median Mc of the head P. It is not necessary to determine exactly whether or not. For example, when an X-ray CT image is taken of a leftward portion or a rightward portion of the front teeth, it may be considered that the rightward or leftward portion is not deviated from the median Mc. For example, the case of photographing the molars of the dental arch may be the case of performing X-ray CT imaging using a part of the dental arch located at a position deviated to the left or right of the head P as the imaging region R. .

  When the imaging region R is not deviated to either the left or right of the head P, the X-ray detector 24 may turn in the first half turning range of the head P.

  The turning range is determined, for example, in the storage unit in advance as a pattern associated with the position of the imaging region R (for example, the left molar region or the right molar region), and the imaging region to be set is set. In accordance with the size of the position of R, a configuration is possible in which the turning range associated with this is determined. More specifically, a standard head P is assumed as the turning range, and a direction from the center of the head P to the center A of the imaging region R is set as the center of the turning range of the X-ray detector 24. Or setting a direction from the center A of the imaging region R to a portion having the maximum distance LD around the head P as the center of the turning range of the X-ray generator 22.

  Further, each time the position of the center A of the imaging region R is set, the angle of the center A of the imaging region R with respect to the center of the head P is calculated, and X-ray detection is performed based on the calculated angle. The turning range of the container 24 (for example, a range in which the angle of the center A of the imaging region R with respect to the center A turns in the same direction (eg, 90 °) in both directions with the center as the center angle) may be determined. As the center position of the head P in this case, for example, a center position that is stored in advance assuming a standard head can be used.

  In the next step S3, while the turning control unit 60 drives and controls the turning drive mechanism 30 to perform X-ray CT imaging of the imaging region R with X-rays, the X-ray generator 22 and the X-ray detector 24 are moved to the head. The X-ray detector 24 is turned around the P within a turning range of 270 ° or less, and the X-ray detector 24 passes through the side of the head P where the imaging region R is unevenly distributed in the head P, and The generator 22 passes around the head P on the side opposite to the side where the imaging region R is unevenly distributed in the head P, and the X-ray detector 24 forms an arc X-ray detection trajectory Or by turning. To At this time, if the photographing region R set by the photographing region position setting unit 40 is located at a position deviated left or right with respect to the median Mc of the head P, as described above, based on the determined turning range. Then, the X-ray generator 22 and the X-ray detector 24 rotate. That is, the turning support unit 20 turns so that the central portion OrM of the X-ray detection trajectory Or is located on the same side as the side on which the imaging region R is offset with respect to the median Mc. At this time, X-rays emitted from the X-ray generator 22 enter the X-ray detector 24 through the head P, and data used to generate an X-ray CT image is obtained. An X-ray CT image is generated based on this data.

  According to the X-ray CT imaging apparatus 10 configured as described above, when the imaging region R is at a position deviated to the left or right with respect to the median Mc of the head P, the central portion OrM of the X-ray detection trajectory Or becomes The X-ray generator 22 and the X-ray detector 24 determine the turning range of the turning support unit 20 so that the imaging region R is positioned on the same side as the side on which the imaging region R is shifted with respect to the median Mc. Contact with the head P can be suppressed. Further, in the above range, the X-ray detector 24 can be brought as close as possible to the imaging region R, so that a clearer X-ray CT image can be obtained.

  For example, by turning the X-ray detector 24 under the condition that the turning diameter q of the X-ray detector 24 with respect to the center of the imaging region R is smaller than the maximum distance LD, the X-ray detector 24 turns as close to the subject as possible. Therefore, a clear X-ray CT image can be obtained as much as possible.

<< 2nd Embodiment >>
An X-ray CT imaging apparatus according to the second embodiment will be described.

  FIG. 3 is a schematic diagram showing the overall configuration of the X-ray CT imaging apparatus 110. Here, an example will be described in which the X-ray CT imaging apparatus 110 is configured to be able to execute not only CT imaging but also panoramic imaging, cephalometric imaging, and the like.

<Overall configuration>
The X-ray CT imaging device 110 includes an imaging main unit 120 and an X-ray image processing device 180. The imaging main unit 120 is a device that executes X-ray imaging such as X-ray CT imaging and collects projection data. The X-ray image processing device 180 is a device that processes projection data collected by the imaging main unit 120 and generates various images.

  The imaging main unit 120 includes a turning support unit 124 and a turning drive mechanism 130. The turning support unit 124 supports the X-ray generator 126 and the X-ray detector 128 so as to face each other with the head P as a subject therebetween. The turning support unit 124 includes a turning axis X1 on a mechanism serving as an axis for turning the turning support unit 124 at a position between the X-ray generator 126 and the X-ray detector 128. The turning drive mechanism 130 includes a turning mechanism 132 and a turning axis moving mechanism 134. The turning mechanism 132 is a mechanism that turns the turning support part 124 around a turning axis X1 on a mechanism between the X-ray generator 126 and the X-ray detector 128. The mechanical relationship between the turning mechanism 132, the turning support 124, the X-ray generator 126, and the X-ray detector 128 is as follows. In other words, the X-ray generator 126 and the X-ray detector 128 turn around the turning axis X1 on the mechanism as the turning support 124 turns around the turning axis X1 on the mechanism. The turning axis moving mechanism 134 is a mechanism that moves the turning axis X1 on the mechanism in a direction intersecting the turning axis X1. The turning axis moving mechanism 134 may be omitted.

  Preferably, the turning axis X1 on the mechanism is provided at a position closer to the X-ray detector 128 than the center position between the X-ray generator 126 and the X-ray detector 128. As an example of the effect obtained by providing the pivot axis X1 on the mechanism at a position closer to the X-ray detector 128 than the center position between the X-ray generator 126 and the X-ray detector 128, a mechanism during X-ray imaging It is possible to meet the demand to make the X-ray detector 128 as close as possible to the imaging region R in order to minimize the magnification while keeping the amount of movement of the upper pivot axis X1 as compact as possible, and to make the projected image clear. No.

  More specifically, the column 121 is supported on the base 120B in a vertical posture. An elevating part 122 is provided on the support 121 so as to be able to elevate and lower. The elevating unit 122 is driven up and down by a lifting drive mechanism. As the lifting drive mechanism, a moving mechanism including a ball screw mechanism and a motor, and a linear actuator such as a linear motor are used, and are incorporated in the column 121 to drive the lift section 122 up and down. A horizontal arm 123 is supported by the elevating unit 122 so as to extend in the horizontal direction. A turning drive mechanism 130 is incorporated at the tip of the horizontal arm 123. An arm 141 for a head fixing device described later extends from the column 121 in the same direction as the horizontal arm 123. A head fixing device 142 is provided at the tip of the head fixing device arm 141, and the head P is held by the head fixing device 142. In FIG. 3, the base end of the elevating unit 122 moves up and down behind the column 121. In this manner, the side on which the base end of the elevating unit 122 moves up and down is defined as the back surface, and the back is defined as the front surface. In FIG. 3, the horizontal arm 123 extends from the elevating unit 122 to the right of the column 121 in front view. I have. The head P is held by the head fixing device 142 in such a direction that the right side in the figure is the rear and the left side is the front.

  Here, the direction is defined for convenience of explanation.

  The XYZ rectangular coordinate system is a rectangular coordinate system defined in a three-dimensional space in which the imaging main unit 120 is installed. The direction parallel to the axial direction of the turning axis X1 on the mechanism is the Z-axis direction. In the present embodiment, the direction parallel to the axial direction of the turning axis X1 on the mechanism and the elevating direction of the elevating unit 122 are matched as the Z-axis direction. The direction orthogonal to the Z axis direction is the Y axis direction, and the direction orthogonal to both the Z axis direction and the Y axis direction is the X axis direction. The front and rear directions of the head P fixed to the head fixing device 142 are defined as Y-axis directions, and the left and right directions of the head are defined as X-axis directions. In the present application, the Z-axis direction may be called a Z-direction, the Y-axis direction may be called a Y-direction, and the X-axis direction may be called an X-direction.

  The direction from the head P toward the base 120B, that is, the lower side is the -Z side, and the direction away from the head P than the base 120B, that is, the upper side is the + Z side. The front side of the head P is the + Y side, and the rear side is the −Y side. The right side of the head P is the + X side, and the left side is the -X side. FIG. 3 shows each axial direction and each + and-.

  The xyz rectangular coordinate system is a rectangular coordinate system defined in the rotation support unit 124 that rotates around the rotation axis X1 on the mechanism and that constitutes an imaging system that performs X-ray generation and X-ray detection. Here, the axial direction of the turning axis X1 on the mechanism is the z-axis direction, and the z-axis direction matches the Z-axis direction in the XYZ orthogonal coordinate system. The direction in which the X-ray generator 126 and the X-ray detector 128 face each other is defined as the y-axis direction, and the direction orthogonal to the y-axis direction and the z-axis direction is defined as the x-axis direction. When the turning support 124 rotates about the turning axis X1 on the mechanism as the rotation axis, the xyz rectangular coordinate system rotates around the Z axis (= z axis) with respect to the XYZ rectangular coordinate system. In the present application, the z-axis direction may be called the z-direction, the y-axis direction may be called the y-direction, and the x-axis direction may be called the x-direction.

  In the y-axis direction, the X-ray detector 128 side is the + y side, and the X-ray generator 126 side is the -y side. Further, in the x-axis direction, the right side from the -y side to the + y side is the + x side, and the left side is the -x side. Further, the upper side in the vertical direction in the z-axis direction is the + z side, and the lower side is the -z side.

  FIG. 4 is a schematic bottom view showing the turning drive mechanism 130. As shown in FIGS. 3 and 4, the turning drive mechanism 130 is a turning axis moving mechanism 134 supported by a horizontal arm 123 as a kind of bracket, and a turning mechanism movably supported by the turning axis moving mechanism 134. 132.

  The turning axis moving mechanism 134 is a mechanism that moves the turning axis X1 on the mechanism in a direction crossing the turning axis X1 on the mechanism, here, a direction orthogonal to the turning axis X1 on the mechanism. Here, the turning axis moving mechanism 134 is constituted by an XY table mechanism, and moves the turning mechanism 132 to which the turning axis X1 on the mechanism is connected in a direction intersecting the turning axis X1 on the mechanism. Is moved in a direction intersecting the turning axis X1 of the mechanism. More specifically, the turning axis moving mechanism 134 includes a fixed table 134B, an X-direction movable support unit 135, an X-direction drive unit 136, a Y-direction movable support unit 137, a Y-direction drive unit 138, a movable table 139.

  The X-direction movable support portion 135 includes a pair of linear guides 135a that extend in the X-direction and are supported on the fixed table 134B in a spaced parallel state. The Y-direction movable support portion 137 includes a pair of linear guides 137a extending in the Y direction. The pair of linear guides 137a is in a posture intersecting with the pair of linear guides 135a (in this case, a posture orthogonal to the linear guides 135a), and extends in a parallel state at intervals on the pair of linear guides 135a. It is supported movably along the X direction. The movable table 139 is supported on a pair of linear guides 137a so as to be movable along a Y direction which is an extending direction thereof. The movable table 139 can move in the X direction by moving the Y-direction movable support portion 137 on the X-direction movable support portion 135 along the X direction. The movable table 139 can move in the Y direction by moving the movable table 139 on the Y-direction movable support portion 137 along the Y direction. Thus, the movable table 139 can freely move in a plane orthogonal to the turning axis X1 on the mechanism.

  The X-direction drive unit 136 is a mechanism that drives the Y-direction movable support unit 137 to reciprocate along the X direction. As the X-direction drive unit 136, for example, a ball screw mechanism or the like in which a nut 136c fixed to the Y-direction movable support unit 137 is screwed to a ball screw 136b that is driven to rotate in both forward and reverse directions by a motor 136a is used. be able to.

  The Y-direction drive unit 138 is a mechanism that drives the movable table 139 to reciprocate along the Y direction. As the Y-direction drive unit 138, for example, a ball screw mechanism or the like in which a nut 138c fixed to the movable table 139 is screwed to a ball screw 138b that is driven to rotate in both forward and reverse directions by a motor 138a can be used. .

  The turning mechanism 132 includes a motor 132a, and is supported by the movable table 139 in a hanging manner. A shaft portion 124c protruding upward from a middle portion in the extending direction of the turning support portion 124 is supported by the turning mechanism 132 in a hanging state. The rotational movement of the motor 132a is transmitted to the shaft portion 124c, and the turning support portion 124 is turned around the shaft portion 124c by the driving of the motor 132a. The central axis of the shaft portion 124c is the turning axis X1 on the mechanism. The turning axis X1 is located between the X-ray generator 126 and the X-ray detector 128 supported by the turning support 124. The rotational movement of the motor 132a is transmitted to the shaft portion 124c via a transmission mechanism such as a gear and a pulley, if necessary. The shaft portion 124c is provided along a vertical direction along the direction of gravity. Therefore, the turning axis X1 on the mechanism is also arranged along the vertical direction.

  Then, by driving the X-direction drive unit 136 and the Y-direction drive unit 138, the turning mechanism 132 supported by the movable table 139 can be moved along a plane orthogonal to the turning axis X1 on the mechanism. The movement of the turning axis X1 on the mechanism can be performed on a desired trajectory within the range of mechanical constraints, and in addition to the linear movement in the X direction and the linear movement in the Y direction, in particular, the X direction driving unit 136 in the X direction And the Y-direction drive by the Y-direction drive unit 138, it is possible to perform linear movement and curve movement in a direction oblique to both the X direction and the Y direction. The turning mechanism 132 can also be rotated to draw a circular orbit, an arc-shaped orbit, or a combination of a plurality of these.

  The mechanism for moving the movable table 139 in the X direction and the mechanism for moving the movable table 139 in the Y direction are not limited to the above examples, and a configuration using a linear actuator such as a linear motor can be adopted. It is not essential that the turning axis moving mechanism 134 has the above configuration. Further, the turning axis moving mechanism may be a mechanism for turning an arm supporting the turning mechanism and thereby turning the turning mechanism in a direction intersecting the turning axis X1 on the mechanism.

  The turning mechanism may be provided on the turning support. For example, the turning axis moving mechanism may directly move the turning axis X1 on the mechanism without going through the turning mechanism. As a more specific example, a shaft corresponding to the turning axis X1 on the mechanism is fixed to the movable table 139 in a non-rotatable manner so as to be movable in a direction intersecting the turning axis X1 on the mechanism. , The pivot support 124 is rotatably connected. Then, the turning mechanism 132 may be provided on the turning support portion 124, and the turning mechanism 132 may generate a rotational force with respect to the shaft, so that the turning support portion 124 turns with respect to the shaft.

  As shown in FIG. 3, the turning support portion 124 is a portion where the X-ray generator 126 and the X-ray detector 128 are supported so as to face each other across the head P. Here, the turning support portion 124 has a shape in which a hanging support portion 124b is provided at both ends of an elongated arm main body portion 124a, that is, a U-shape that opens downward. The shaft portion 124c protruding upward is protruded from an intermediate portion of the arm body portion 124a in the extending direction, and the shaft portion 124c is supported by the turning mechanism 132 in a hanging state.

  An X-ray generator 126 is provided on one of the hanging support portions 124b. The X-ray generator 126 generates X-rays. For example, the X-ray generator 126 includes an X-ray tube, and is configured to emit X-rays emitted from the X-ray tube toward the X-ray detector 128. The hanging support part 124b on the side where the X-ray generator 126 is provided is also an X-ray generation part 126a including the X-ray generator 126.

  Here, an X-ray regulating unit 129 that regulates the X-ray generated from the X-ray generator 126 into an X-ray cone beam is provided on the side where the X-ray detector 128 is irradiated with the X-ray. The X-ray restricting unit 129 is a member having an X-ray restricting hole formed therein, and allows a part of X-rays generated from the X-ray generator 126 to pass through according to the shape and size of the X-ray restricting hole. And shield the outside of the passing range. As a result, the range of the X-ray beam traveling to the X-ray detector 128 is restricted, and the X-ray is restricted to the X-ray cone beam. The X-ray regulating unit 129 is provided with a plurality of types of X-ray regulating holes to switch the X-ray regulating holes for regulating X-rays, or by moving a member forming the X-ray regulating holes to move the X-ray regulating holes. By adjusting the opening width of the X-ray, the amount of X-rays generated from the X-ray generator 126 to be blocked, that is, the regulated amount is adjusted.

  The X-ray restricting unit 129 includes, for example, four X-ray shielding members, and is located on the front surface of the X-ray irradiation port of the X-ray generator 126 on the + z side, −z side, and + x side centered on the X-ray irradiation port. Side and -x side. The + z side shielding member and the −z side shielding member are independently driven so as to be displaceable in the z direction, and the + x side shielding member and the −x side shielding member are independently driven so as to be displaceable in the x direction. Is controlled by an X-ray regulating unit drive control unit (not shown). The space surrounded by these X-ray shielding members is a region through which X-rays can pass, and is an X-ray regulating hole. An X-ray regulating hole having a desired shape is formed by the displacement drive control of the four X-ray shielding members. The region through which the X-rays can pass, that is, the X-ray restriction hole is, in other words, an X-ray passage permitting portion. The regulation width means the width of the restricted space, and is the width of the X-ray passage permitting portion, that is, the width of the X-ray regulation hole. Therefore, a relationship is established in which the regulation width is reduced to increase the regulation amount, and the regulation width is increased to decrease the regulation amount.

  An X-ray detector 128 is provided on the other hanging support portion 124 b, whereby the X-ray detector 128 is disposed to face the X-ray generator 126 with the head P interposed therebetween. The X-ray detector 128 detects the X-ray generated by the X-ray generator 126. For example, the X-ray detector 128 includes an X-ray detector having a planar detection surface, and can detect X-rays (X-ray cone beam) emitted from the X-ray generator 126 and passing through the head P. It is configured. With this X-ray detector 128, projection data by X-ray imaging can be obtained. The hanging support part 124b on the side where the X-ray detector 128 is provided is also the X-ray detection part 128a including the X-ray detector 128.

  In many cases, the X-ray detector 128 is actually housed in the exterior part. Therefore, when the X-ray detector 128 is housed in the exterior of the X-ray detection unit 128a, the presence or absence of contact with the head P is determined. Regarding the above, the X-ray detector 128 may be read as the X-ray detection unit 128a to consider the presence or absence of the contact. The same applies to the X-ray generator 126. When the X-ray generator 126 is housed in the exterior of the X-ray generator 126a, the X-ray generator 126 The presence or absence of the contact may be determined by reading it as the generation unit 126a.

  A space is provided between the X-ray generator 126 and the X-ray detector 128 so that the head P can be disposed.

  In the present embodiment, the X-ray generator 126 and the X-ray detector 128 are attached to both ends of the U-shaped turning support unit, but the X-ray generation unit and the X-ray detector are annular. It may be supported in a facing state by a member. Such an annular member can be pivotally supported by providing a shaft portion on a support member that crosses a part of the circumferential direction or the inside of the annular member. In the present embodiment, the X-ray generator 126 and the X-ray detector 128 are supported rotatably about a vertical axis, but are supported rotatably about an axis oblique to the vertical direction. Or may be supported rotatably about a horizontal axis.

  Then, the turning support part 124 can be moved up and down by the elevating part 122 according to the height of the head P. Further, the turning support mechanism 124 can be turned by the turning drive mechanism 130 such that the X-ray generator 126 and the X-ray detector 128 turn around the head P.

  Further, a head fixing device arm 141 extending in the horizontal direction is provided in a portion of the column 121 below the horizontal arm 123. The horizontal arm 123 and the head fixing device arm 141 extend in the same direction with the column 121 side as a base end. The head fixing device arm 141 extends toward the lower side of the horizontal arm 123, and a head fixing device 142 is provided at a distal end thereof. The head fixing device 142 is located between the X-ray generator 126 and the X-ray detector 128. The head fixing device 142 includes a chin rest 142a capable of placing and supporting the chin of the head P, which is a subject, and a holding portion 142b, which holds the head P, which is a subject, from both outer sides thereof. Then, the chin of the head P is supported on the chin rest 142a, and the head P is sandwiched by the holding portion 142b, so that the head P is located between the X-ray generator 126 and the X-ray detector 128. It is held in a fixed position. The head fixing device 142 may be configured as at least one of the chin rest 142a and the holding portion 142b. Further, a cephalographic head fixing device hanging arm 143 is provided so as to extend in the horizontal direction on a side opposite to the side where the horizontal arm 123 extends from the column 121, and the cephalographic head fixing device hanging arm 143. , A cephalographic head fixing device 144 is supported in a suspended state. An X-ray detector 128b for cephalometric imaging is incorporated in the cephalometric head fixing device 144.

  A main body control unit 150 including an operation panel device 158 is provided at an intermediate portion in the extending direction of the head fixing device arm 141. Note that, in FIG. 3, the operation panel device 158 of the main body control unit 150 is illustrated in an enlarged manner in the balloon.

  The head fixing device arm 141 may be configured to be able to move up and down. For example, the base end of the arm 141 for the head fixing device, that is, the portion near the column 121 of the arm 141 for the head fixing device can be moved along the longitudinal direction of the column 121 by an appropriate guide member. In this state, the base end of the arm 141 for the head fixing device is connected to the elevating part 122 so as to be able to move up and down behind the support 121. For connection, for example, a power source such as a motor is fixed to the base end of the arm 141 for the head fixing device, a screw shaft is connected to the rotating shaft of the motor, and a receiving member (screw) of the screw shaft is connected to the elevating unit 122. It is possible to employ a configuration in which the screw member is fixed, and the screw shaft is screwed into the receiving member of the screw shaft. With this configuration, the motor fixed to the base end of the head fixing device arm 141 is rotationally driven, so that the base end portion of the head fixing device arm 141 and the head The entire arm 141 for the part fixing device and the head fixing device 142 can be moved up and down.

  With this configuration, the lifting of the elevating unit 122 with respect to the column 121 and the lowering of the arm 141 for the head fixing device with respect to the elevating unit 122 are performed simultaneously with the same displacement amount, so that the head fixing device 142 and the head fixing device 142 are used. The horizontal arm 123 and the swivel support 124 can be raised with respect to the head P while maintaining the height of the head P fixed at a fixed value. By simultaneously lowering the elevating part 122 with respect to the column 121 and raising the head fixing device arm 141 with respect to the elevating part 122 with the same amount of displacement, the head fixing device 142 and the head P fixed to the head fixing device 142. The horizontal arm 123 and the turning support 124 can be lowered with respect to the head P while maintaining the height of the head P constant. In addition, the arm 141 for the head fixing device, the head fixing device 142, the horizontal arm 123, and the turning support 124 can be simultaneously raised or lowered. Further, with the heights of the horizontal arm 123 and the turning support 124 kept constant, the height of the arm 141 for the head fixing device and the head fixing device 142 can be adjusted by raising or lowering the same. Further, the head fixing device arm 141 and the head fixing device 142 may be driven up and down by an independent lifting mechanism independent of the lifting and lowering of the lifting unit 122.

  When performing X-ray imaging, the head support device 142 fixes the head P, which is a subject, and the rotation support unit 124 is stopped or rotated in accordance with a desired imaging mode. Take a picture. This makes it possible to obtain X-ray projection image data necessary to generate an X-ray CT image (simply referred to as an X-ray CT image or CT image), a panoramic image (simply referred to as a panoramic image), and the like. For example, by performing X-ray imaging while the rotation support unit 124 is turned, X-ray CT imaging projection image data necessary for generating an X-ray CT imaging image can be obtained. The X-ray CT imaging projection image data is projection image data for each direction obtained by irradiating the imaging region R with an X-ray cone beam from multiple directions, and can be collected in the form of frame image data. Further, by performing X-ray imaging while rotating the rotation support unit 124 in a certain range, panoramic imaging projection image data is obtained, and by performing image processing for reconstruction, a panoramic imaging image can be obtained. The panoramic photographed projection image data is projection image data for each direction obtained by irradiating the jaw region including the dental arch with the slit X-ray beam extending in the z direction from multiple directions while changing the irradiation position every moment. Yes, each one can be collected in the form of frame image data. The X-ray CT imaging apparatus 110 may also perform X-ray imaging for obtaining a cephalometric image or a pseudo intraoral image. For example, the head P is fixed on the cephalographic head fixing device 144 supported by the cephalographic head fixing device 144 that extends in the horizontal direction from the column 121 with the turning support 124 stopped. Then, X-rays are emitted from the X-ray detector 128 to perform X-ray imaging, whereby a cephalometric image can be obtained. It should be noted that the photographing function of the panoramic photographed image, the photographing function of the cephalo photographed image and the like may be omitted.

  The main body control section 150 is configured to be able to receive each instruction to the imaging main body section 120 and to be capable of controlling each operation of the imaging main body section 120. The main body control section 150 is fixed to a head fixing device arm 141 extending horizontally from the support column 121. The main control unit 150 is provided with an operation panel device 158 for displaying various information from the main control unit 150 and receiving various commands to the main control unit 150. Here, the operation panel device 158 includes a display device (display unit) 158a such as a liquid crystal display panel, and a touch detection unit 158b such as a touch panel provided on a display screen of the display device. By detecting a user's touch operation on the display screen by the touch detection unit, an operation on the X-ray CT imaging apparatus 110 can be received. A push button or the like may be provided near the operation panel device 158 or the like. Further, the display device and the input device that receives the operation of the user may be provided separately.

  The above components of the imaging main body 120 are housed in an X-ray protection room 146. Outside the wall of the X-ray prevention room 146, a push button switch called a deadman switch for instructing the main body control unit 150 to irradiate an X-ray is provided.

  The X-ray image processing apparatus 180 includes an information processing main unit 182 including, for example, a computer, and is connected to the imaging main unit 120 via a communication cable so that various data can be transmitted and received. However, data may be transmitted and received between the imaging main unit 120 and the X-ray image processing device 180 by wireless communication. The information processing main unit 182 can execute various image processing and the like based on data transmitted from the imaging main unit 120.

  The X-ray image processing device 180 is connected to a display unit 188 composed of a display device such as a liquid crystal monitor, and an operation unit 189 composed of a keyboard and a mouse. The operator can give various instructions to the information processing main unit 182 on the characters and images displayed on the display unit 188 by a pointer operation using a mouse or the like. The display unit 188 may be configured by a touch panel.

  Part or all of the processing of the X-ray image processing apparatus 180 may be executed by the main body control unit 150. Alternatively, part or all of the processing of the main body control unit 150 may be executed by the X-ray image processing device 180.

<About block diagram of X-ray CT imaging apparatus>
FIG. 5 is a block diagram showing an electrical configuration of the X-ray CT imaging apparatus 110.

  The main body control unit 150 of the main imaging unit 120 controls the X-ray imaging operation of the main imaging unit 120, and includes a CPU (Central Processing Unit) 151, a RAM (Random Access Memory) 152 as at least one processor, and a storage. The unit 153, the input / output units 154a and 154b, the operation input unit 155, the image output unit 156, and the like are configured by a computer interconnected via a bus line 157. The storage unit 153 is configured by a non-volatile storage device such as a flash memory or a hard disk device. The storage unit 153 receives various instructions related to X-ray imaging, and controls the turning drive mechanism 130, the X-ray generator 126, the X-ray regulating unit 129, and the like in accordance with the instructions to control the X-ray imaging operation. Is stored.

  Further, when the position of the imaging region R in the head P is set in the storage unit 153, the storage unit 153 is referred to when determining the turning range of the X-ray detector 128 according to the set position of the imaging region R. The reference table 153b is stored. The reference table 153b is a table in which the position of the imaging region R is associated with the turning range of the X-ray detector 128 and the like.

  The reference table 153b is one piece of information that constitutes drive control information of an imaging system including the turning support 124, the X-ray generator 126, and the X-ray detector 128 as elements. The reference table includes, for example, coordinate information of the turning axis X1 on the mechanism and information of a turning amount for turning the turning support unit 124 around the turning axis X1 on the mechanism. The coordinate information of the turning axis X1 on the mechanism may be information on the position where the turning axis X1 on the mechanism stays, or may be the trajectory information on the trajectory of moving the turning axis X1 on the mechanism.

  In the reference table 153b, the X-ray generators 126 and X with respect to the position of the imaging region R on the head P, the shape and size of the standard (for example, standard adult) head P, and the pivot axis X1 on the mechanism are provided. Considering each distance of the X-ray detector 128, the turning range of the X-ray detector 128 such that the X-ray generator 126 and the X-ray detector 128 do not come into contact with the head P at the time of turning is theoretically determined. Has been determined experimentally. Examples of the turning range and the like according to the position of the shooting region R will be described later. The RAM 152 is provided as a work area when the CPU 151 performs a predetermined process. The input / output unit 154a includes a motor of a turning mechanism 132 for turning the turning support unit 124 of the main imaging main unit 120, a motor of a turning axis moving mechanism 134 for moving the turning support unit 124, an X-ray generator 126, and an X-ray detector. The input / output unit 154b is communicably connected to the X-ray image processing device 180. The operation input unit 155 is connected to the touch detection unit 158b of the operation panel device 158, and the image output unit 156 is connected to the display unit 158a of the operation panel device 158.

  In the main body control unit 150, the CPU 151 performs arithmetic processing in accordance with the procedure described in the photographing program 153a, instructions received through the touch detection unit 158b, and the like, thereby forming a part of the dental arch of the head P of the subject. And a rotation control unit 151b that controls the rotation mechanism 132 and the rotation axis movement mechanism 134 when performing X-ray imaging such as X-ray CT imaging. Execute. Then, the CPU 151 controls the turning mechanism 132 and the turning axis moving mechanism 134 to turn the X-ray generator 126 and the X-ray detector 128 around the head P while passing the X-ray through the head P. The detection results of the X-rays detected by the detectors 128 and 128b can be obtained.

  The photographing program 153a and the reference table 153b are stored in the storage unit 153 in advance, but may be recorded on a recording medium such as a CD-ROM or DVD-ROM, an external flash memory, or The information may be provided to an existing X-ray CT imaging apparatus or an information processing main unit that controls the X-ray CT imaging apparatus by downloading from an external server via a network or the like.

  The X-ray image processing device 180 generates X-ray image data 185b based on the imaging data from the imaging main unit 120. The information processing main unit 182 includes a CPU 183 as at least one processor, a RAM 184, and a storage. The unit 185, the input / output unit 186, the operation input unit 189a, the image output unit 188a, and the like are configured by a computer interconnected via a bus line 182a. The storage unit 185 is configured by a non-volatile storage device such as a flash memory or a hard disk device, and the information processing main unit 182 converts the X-ray image data 185 b based on the imaging data from the imaging main unit 120. An image processing program 185a to be generated, X-ray image data 185b, and the like are stored. The storage unit 185 may store management data in which X-ray image data 185b is associated with identification information (patient identification information) of the head P and the like. Further, the X-ray image processing apparatus 180 receives data and the like related to the imaging conditions from the main body control unit 150, and stores the data and the like related to the imaging conditions in the generated X-ray image data 185b in the storage unit 185. Is also good. The RAM 184 is provided as a work area when the CPU 183 performs a predetermined process. The input / output unit 186 is connected to the imaging main unit 120, and receives X-ray imaging data obtained by the imaging main unit 120 via the input / output unit 186. Further, the operation input unit 189a is connected to the operation unit 189, and the image output unit 188a is connected to the display unit 188.

  The storage unit 185 may store the imaging data from the imaging main unit 120 as the projection image data 185c before the reconstruction. The projection image data 185c may be raw data that has not been processed at all, or may be pre-processed data that has been processed to some extent for reconstruction. The projection image data 185c is, for example, the above-described frame image data. Management data and the like in association with the above-described specific information of the head P (patient specific information) and / or data related to the imaging conditions are stored in the storage unit 185 in association with the image data 185b or the projection image data 185c. You may do so.

  In the information processing main unit 182, the CPU 183 performs arithmetic processing in accordance with the image processing program 185a, thereby generating desired X-ray image data based on the X-ray imaging data obtained by the imaging main unit 120. Is executed. That is, data such as a CT image, a panoramic photographed image, and a cephalo photographed image is generated in accordance with an instruction received through the main body control unit 150. The storage unit 185 stores the generated X-ray image data 185b.

  Note that some or all of the functions realized by the above units may be realized by hardware using a dedicated logic circuit or the like. In addition, some or all of the functions realized by the above-described units may be integrated and processed by a single processor, or may be appropriately distributed and processed by a plurality of processors.

<Setting of the position of the photographing region R and turning processing during photographing>
The control performed by the turning control unit 151b based on the shooting program 153a will be described with reference to a flowchart shown in FIG.

  When the setting to perform CT imaging is set, an operation to set the position of the imaging region R is accepted in step S11.

  Here, an example of receiving a setting operation of the position of the imaging region R will be described. FIG. 7 is a diagram showing a display example on the operation panel device 158. The display section 158a of the operation panel device 158 includes a panorama selection image 191a (see the character "Pan") for selecting a panorama shooting mode and a cephalo selection image 191b for selecting a cephalo shooting mode as images for selecting a shooting mode. (Refer to the character “Ceph”), and a CT selection image 191c (refer to the character “CT”) for selecting the CT imaging mode is displayed. Although “Pan”, “Ceph”, and “CT” are characters, they are displayed in a form that can be visually recognized as characters, and are character-shaped images in that sense. An image that symbolically represents each photographing without taking the form of characters may be used, or both may be used in combination. In the illustrated state, the CT imaging mode is selected by using the CT selection image 191c. The display section 158a displays a shooting area setting image 194 as an image for setting shooting conditions. Here, the photographing area setting image 194 is displayed on the right side of the display unit 158a. An illustration image 195 is displayed on the display unit 158a. Here, the illustration image 195 is displayed below the panorama selection image 191a, the cephalo selection image 191b, and the CT selection image 191c in the display unit 158a. The illustration image 195 is an image for showing the imaging region R, and here, a dental arch is displayed as an illustration image.

  The display unit 158a is provided with a touch detection unit 158b as a two-dimensional position detection unit that detects a touch position on the display area.

  When the operator touches any of the panorama selection image 191a, the cephalo selection image 191b, and the CT selection image 191c, the touch operation is detected by the touch detection unit 158b. As a result, the main body control unit 150 accepts whether to perform panoramic imaging, cephalometric imaging, or X-ray CT imaging.

  When the operator touches the shooting area setting image 194, as shown in FIG. 8, according to the touch operation, a plurality of shooting area selection images 194a, 194b, 194c corresponding to the shooting area setting image 194 are displayed. 194d and 194e are displayed. The plurality of photographing region selection images 194a, 194b, 194c, 194d, 194e indicate regions having different sizes (diameter, height) and the like. When the user selectively touches any one of the plurality of photographing region selection images 194a, 194b, 194c, 194d, 194e, a photographing region setting operation is accepted.

  In the example shown in FIG. 8, the imaging region selection images 194a and 194b are images for selecting an imaging region R having a diameter of 40 mm. The shooting region selection image 194a indicates that the height of the shooting region R is 80 mm, and the shooting region selection image 194b indicates that the height of the shooting region R is 40 mm. That is, in each photographing region selection image, the diameter is displayed in the upper part and the height is displayed in the lower part, and the numerical value indicates the size in units of millimeters. Regardless of the height of the imaging region R, the fact that the imaging region R has a diameter of 40 mm indicates that a part of the dental arch is designated. Therefore, it can be said that the imaging region selection images 194a and 194b are images for accepting that X-ray CT imaging is performed on a part of the dental arch.

  The photographing region selection images 194c, 194d, 194e are images for selecting a photographing region R having a diameter of 80 mm. The shooting area selection images 194c, 194d, and 194e indicate that the height of the shooting area R is 80 mm, 50 mm, and 40 mm, respectively. Regardless of the height of the imaging region R, the fact that the imaging region R has a diameter of 80 mm indicates that the entire dental arch viewed from the axial direction of the body axis is designated. Therefore, it can be said that the imaging region selection images 194b, 194c, 194d are images for accepting that X-ray CT imaging is performed on the entire dental arch.

  When the height is 80 mm, for example, both the upper and lower jaw regions are targeted, and when the height is 50 mm, for example, one of the upper and lower jaw regions when the head P is positioned so that the Frankfurt plane is horizontal. When the height is 40 mm, for example, one of the upper and lower jaw regions when the head P is positioned so that the Campel plane is horizontal is targeted.

  Now, assuming that the photographing region selection image 194b is selected, as shown in FIG. 7, the photographing region having a diameter of 40 mm and a height of 40 mm has been selected, as shown at the center of the upper right and lower sides. Become.

  Returning to FIG. 7, the photographing region image 195a is superimposed and displayed on the illustration image 195 (when the photographing region R having a diameter of 80 mm is selected, the photographing region image 195b is superimposed). As the photographing region images 195a and 195b, circles having a size corresponding to those set via the photographing region setting image 194 are displayed. The photographing region image 195a is an image displayed when the photographing region R targeting a part of the dental arch is selected, and the photographing region image 195b includes the photographing region R targeting the entire dental arch. It is an image displayed when selected. For example, in the example shown in FIG. 7, when the photographing region image 195a is displayed by selecting a photographing region having a diameter of 40 mm and a height of 40 mm, the operator touches a desired position of the illustration image 195, The imaging region image 195a moves to a position that specifies any part of the dental arch. As a result, the imaging region R can be specified at any position (for example, the front tooth region, the right molar region, and the left molar region) of the dental arch.

  The photographing region image 195a is designated by a pointer or the like, and the designated region and the peripheral region of the photographing region image 195a are enlarged and displayed. Then, the photographing region image 195a is moved to a desired position like a drag-and-drop operation so that the region can be designated. Alternatively, the photographing region image 195a may be designated by a pointer or the like, and the designated region and the peripheral region of the photographing region image 195a may be enlarged and displayed, and then the photographing region image 195a may be moved by a separate movement key. . On the screen, the illustration image 195 may be similarly moved with respect to the stationary shooting region image 195a so that the region can be designated.

  When the designation of the imaging region R is received, the turning support unit 124 is moved to a position where the turning support unit 124 can turn around the center A of the imaging region R by the driving of the turning axis moving mechanism 134, and the turning mechanism 132 turns the turning support unit 124. An angle around the axis X1 is determined toward the start of imaging.

  When the imaging region R targeting a part of the dental arch is selected, and the imaging region R is specified in the right molar region or the left molar region, the image is biased to either the left or right of the head P. This is a case where X-ray CT imaging is performed using a part of the dental arch at the position as an imaging region R.

  In the above example, an example in which the touch panel is used to specify the shooting mode, the shooting area R, and the like has been described. However, various settings are received via a switch (push button) that physically receives an operation. Is also good.

  As described above, in step S11, the imaging region position setting unit 151a receives the operation of setting the position of the imaging region R with respect to a part of the dental arch of the head P through the operation panel device 158. Here, the imaging region position setting unit 151a receives, via the operation panel device 158, a selection operation of one of the imaging region selection images 194a and 194b and a position setting for the illustration image 195 using the imaging region image 195a. The position setting of the photographing region R is received. In particular, the setting of the position of the imaging region R in which the local region that is a part of the dental arch Ar of the head P is to be subjected to X-ray CT imaging is received.

  In the next step S12, the turning range is determined according to the position of the set photographing area. The turning range indicates in what range the X-ray detector 128 is turned around the center A of the imaging region R. Such a turning range is expressed by, for example, a range from which angle to which one or both of the X-ray generator 126 and the X-ray detector 128 are turned around the center A of the imaging region R. In the present embodiment, as described in the first embodiment, while the turning control unit 151b drives and controls the turning drive mechanism 130 to perform X-ray CT imaging of the imaging region R with X-rays, the X-ray generator is used. 126 and the X-ray detector 128 are turned around the head P in a turning range of 270 ° or less (here, 180 °), and the X-ray detector 128 captures the image around the head P. The region R passes on the side of the head P which is unevenly distributed, and the X-ray generator 126 passes on the side of the head P opposite to the side where the imaging region is unevenly distributed. The detector 128 rotates and moves the X-ray detection trajectory Or of the arc (in the following description, (left), (right), and (mid) are added to Or for each of the left molar, the right molar, and the anterior tooth. (May be distinguished as orbits).

  As described in the first embodiment, when driving the turning support unit 124, the turning drive mechanism 130 sets the turning range of 270 or less to 180 ° or the spread angle of irradiation of the X-ray beam at 180 ° (see FIG. The X-ray generator 126 and the X-ray detector 128 may be turned around the head P in a turning range of an angle obtained by adding the angle β of FIG. 15).

  A mode in which the X-ray CT imaging apparatus 110 rotates the X-ray generator 126 and the X-ray detector 128 in a range of 270 ° or less, and a mode in which the X-ray generator 126 and the X-ray detector 128 rotate in 360 ° or more. It is also possible to envisage a configuration that can be switched between and, and this case will be described in a later embodiment.

  The determination of the turning range according to the position of the set photographing area can be performed with reference to a reference table as shown in FIG. 9, for example. That is, a reference table in which the turning range is associated with the position of the imaging region is registered in advance. As the turning range, for example, an angle at which the X-ray detector 128 starts turning and an angle at which the X-ray detector 128 ends turning around the center A of the imaging region R are defined. For example, as shown in FIG. 10, the -Y direction is set to 0 ° from the center A of the imaging region R, and the angle at which the X-ray detector 128 rotates clockwise is set to α (the angle range is set to αα, and αα is set to αα). (Left), (right), and (mid) may be added to distinguish angular ranges for left molars, right molars, and anterior teeth.) In the example shown in FIG. 9, an angle range αα (left), that is, an angle α (left1) to α (left2) is associated with the left molar. α (left1) is the angle at which the X-ray detector 128 starts to rotate, and α (left2) is the angle at which the X-ray detector 128 stops rotating. An angle range αα (right), that is, angles α (right1) to α (right2) are associated with the right molar. α (right1) is an angle at which the X-ray detector 128 starts rotating, and α (right2) is an angle at which the X-ray detector 128 stops rotating. In the example shown in FIG. 9, angles α (mid1) to α (mid2) are associated with the turning range (angle range αα (mid)) even when the position of the imaging region is set to the front teeth. The angle α (mid1) is the angle at which the X-ray detector 128 starts rotating, and the angle α (mid2) is the angle at which the X-ray detector 128 stops rotating.

  The turning ranges α (left1) to α (left2) associated with the left molars are set such that the center of the X-ray detection trajectory Or (left) is located to the left with respect to the median Mc. Similarly, the turning ranges α (right1) to α (right2) associated with the right molars are set such that the center of the X-ray detection trajectory Or (right) is located to the right with respect to the median Mc. I have.

  The turning range α (mid1) to α (mid2) associated with the front teeth is such that the center of the arc of the X-ray detection trajectory Or (mid) is located on the front side of the head P on the plane including the median Mc. Is set to

  Each of the turning ranges defines the turning range of the X-ray detector 128, and thus it can be said that it defines the turning range of the turning support 124.

  Based on the set imaging region R, it is determined whether the imaging region R is a left molar, a right molar, or an anterior tooth, and a corresponding turning range is determined based on the determination result. The determination of the position (left molar, right molar or anterior tooth) of the imaging region R based on the set imaging region R is performed, for example, in the anterior tooth region and the molar region where the coordinates of the center A of the imaging region R are set in advance. It can be determined by determining which one it belongs to. The imaging region in the lookup table may be divided into a larger number of regions for the dental arch.

  In the next step S13, a turning control based on the determined turning range is performed to perform CT imaging. While the turning control unit 151b drives and controls the turning drive mechanism 130 to perform X-ray CT imaging of the imaging region R by X-rays, the X-ray generator 126 and the X-ray detector 128 are rotated by 270 ° around the head P. The X-ray detector 128 is turned in the following turning range, and the X-ray detector 128 passes through the side of the head P around which the imaging region R is unevenly distributed in the head P. The X-ray detector 128 passes through the opposite side of the eccentric side of P, and forms an X-ray detection trajectory Or of an arc by turning movement during X-ray CT imaging.

  At this time, as described above, when the imaging region R is located at a position deviated left or right with respect to the median Mc of the head P, the center OrM of the arc of the X-ray detection trajectory Or becomes the median Mc. In contrast, the turning range of the turning support unit 124 is set such that the imaging region R is located on the same side as the one on which the shooting area R is located. The X-ray detection trajectory Or is an arc trajectory that does not approach so as to partially protrude toward the imaging region R, that is, an arc trajectory that does not have a concave portion toward the imaging region R. It is. In other words, the X-ray detection trajectory Or is an arc trajectory in which a curve that is convex on the outer peripheral side is continuous.

  Preferably, assuming a maximum distance LD of the surface of the head P with respect to the center A of the imaging region R, the turning diameter q of the X-ray detector 128 with respect to the center A of the imaging region R is set to be smaller than the maximum distance LD. Is done. That is, the X-ray generator 126 and the X-ray detector 128 are moved around the head P while maintaining the state in which the X-ray detector 128 is positioned closer to the imaging region R than the X-ray generator 126. Turn. In this case, the turning diameter q of the X-ray detector 128 with respect to the center A of the imaging region R is set to be smaller than the maximum distance LD.

  Here, when the imaging region R is the left molar, when performing X-ray CT imaging by irradiating the head P with X-rays generated from the X-ray generator 126, the X-ray detector 128 Turn around the range biased to the left. Further, when the imaging region R is a right molar, when performing X-ray CT imaging by irradiating the head P with X-rays generated from the X-ray generator 126, the X-ray detector 128 Turn around the range biased to. When the imaging region R is an anterior tooth, when the head P is irradiated with X-rays generated from the X-ray generator 126 and the X-ray CT imaging is performed, the X-ray detector 128 is moved in the left-right direction of the head P. Swirl an equal angle range from the center to the left and right.

  These turning operations will be described more specifically with reference to FIGS.

  In this case, as shown in FIG. 11, it is assumed that the imaging region R targeting a part of the dental arch Ar is located on the median Mc of the head P. That is, this is a case where the front tooth region which is a part of the dental arch Ar is set as the imaging region R. In this case, the part of the surface of the head P farthest from the imaging region R is the rear part of the head P. The X-ray generator 126 is farther from the imaging region R than the X-ray detector 128, and the X-ray generator 126 turns behind the head P. For example, considering the case where the X-ray generator 126 and the X-ray detector 128 are rotated by 180 °, the α (mid1) is set to 90 ° and α (mid2) is set to 270 °, and the X-ray detector 128 is set to 90 °. It is turned 180 ° in the range of the X-ray detection trajectory Or of 270 °. In this turning range, the central portion OrM of the X-ray detection trajectory Or is located forward of the head P on a plane including the median Mc. The turning angle may be a turning angle obtained by adding a fan angle of the X-ray beam to 180 °. From the viewpoint of image processing, a turning angle obtained by adding the fan angle of the X-ray beam to 180 ° is preferable. This is the same when the turning range is deviated to the left or right of the head P as described later. Even if the X-ray generator 126 and the X-ray detector 128 are turned in such a range, they can be turned without contacting the head P.

  On the other hand, it is assumed that X-ray CT imaging is performed with a part of the dental arch Ar located at a position deviated to the left or right from the front-back axis of the head P as an imaging region R. In FIG. 11, the photographing region R is pointed out at a position deviated leftward in the dental arch Ar in the head P indicated by a two-dot chain line.

  In this case, since the imaging region R is located closer to the X-ray detector 128 than the X-ray generator 126, when the X-ray detector 128 turns to the right of the head P, the X-ray detector 128 may come into contact with the head P.

  Therefore, as shown in FIG. 12, the X-ray detector 128 orbits the X-ray detection trajectory Or in a range deviated to the same side as the side where the part of the dental arch Ar is deviated (here, the left side). To do. Here, when viewed in a plan view, the X-ray detector 128 detects an X-ray in a range of 270 ° or less (here, 180 ° rotation) around a range deviated leftward from the center of the front part of the head P. It turns on the detection trajectory Or. For example, assuming that α (left1) is 40 ° and α (left2) is 220 °, the X-ray detector 128 is turned 180 ° in the range of 40 ° to 220 °. In this case, the central portion OrM of the X-ray detection trajectory Or is deviated to the left with respect to the median Mc. The X-ray detector 128 takes a trajectory from a position on the left rear side of the head to a position on the right front side of the head passing through the front side of the head. For the head P indicated by a solid line in FIG. 11, the range occupied by the trajectory of the X-ray detector 128 is equal to the left and right, while for the head P indicated by a solid line in FIG. Is less than half on the right and more than half on the left.

  The X-ray generator 126 takes a trajectory from a position on the right front of the head to a position on the left rear of the head passing through the back of the head. That is, the X-ray generator turns in a range deviated to the side opposite to the X-ray detector 128. Of course, the start position and the end position may be exchanged to make a reverse rotation.

  As a result, the X-ray detector 128 does not turn on the right side of the surface of the head P far from the imaging region R and the outside of the diagonally right rear part, and the X-ray detector 128 is less likely to contact the head P. Become. The X-ray generator 126 turns on the right side of the surface of the head P far from the imaging region R and the outside of the diagonally right rear, but is farther away from the imaging region R than the X-ray detector 128, so Contact with the head P is difficult.

  In addition, like the head P shown by the two-dot chain line in FIG. 12, the X-ray detector 128 is located on the opposite side (here, right side) from the side where the part of the dental arch Ar is biased (here, left side). When the user turns around the biased range, the X-ray detector 128 easily comes into contact with the head P.

  Therefore, contrary to FIG. 12, when a part of the dental arch Ar is deviated to the right side, as shown in FIG. 13, the X-ray detector 128 determines that the part of the dental arch Ar is deviated to the right. The X-ray detection trajectory Or in the range deviated to the same side as (here, the right side) is turned. For example, assuming that α (right1) is 130 ° and α (right2) is 310 °, the X-ray detector 128 is rotated 180 ° in the range of 130 ° to 310 °. In this case, the central portion OrM of the X-ray detection orbit Or is deviated to the right with respect to the median Mc. As a result, similarly to the above, the X-ray detector 128 does not turn on the left side of the surface of the head P far from the imaging region R and the outside of the diagonally rear left part, and the X-ray detector 128 It becomes difficult to contact with P.

  As described above, when performing X-ray CT imaging using a part of the dental arch Ar at a position deviated from the longitudinal axis of the head P as the imaging region R, the X-ray detector 128 relatively close to the head P is used. By turning in a range in which the part of the dental arch Ar is deviated to the same side as the deviated side, the contact of the X-ray detector 128 with the head P can be suppressed. In particular, when the X-ray detector 128 turns in a range of 270 ° or less, a range where the X-ray detector 128 does not turn around the imaging region R can be provided.

  Hereinafter, a description will be given of a setting example from a detector existence area where the X-ray detector 128 can exist and a safety area where the X-ray detector 128 cannot exist when performing X-ray CT imaging.

  The detection movement trace OD formed by the movement of the X-ray detector 128 during the X-ray CT imaging will be described with reference to FIG. The detected movement trace OD is determined when the turning support unit 124 moves from the turning start position ST to the turning end position ED, that is, when the X-ray detector 128 moves from the turning start position STd to the turning end position EDd. The trajectory drawn by the line detector 128. In FIG. 32, the detected movement trace OD is indicated by a hatched area. In the illustrated example, the detected movement trace OD when the turning support part 124 and the X-ray detector 128 make a 180 ° turn is shown. In this case, the detection movement trace OD is formed in a U-shape. For this reason, when looking around the center of rotation of the X-ray detector 128, there are an arc-shaped closed area CA and an open area OA. Since the closed area CA is U-shaped, the inner area CAI of the closed area CA is also U-shaped. The open area OA is located in the direction in which the center of the arc-shaped movement trajectory of the X-ray generator 126 is located with respect to the closed area CA. The X-ray detection trajectory Or is set as described above so that the inner area CAI does not touch the surface of the head.

  FIG. 33 shows another setting example. The turning angle of the turning support 124, that is, the turning angle of the X-ray detector 128 is a turning angle obtained by adding the fan angle fa of the X-ray beam to 180 °. The fan angle fa is set to an opening degree at which both ends in the x direction of the photographing region R can be exactly accommodated. In the illustrated example, fa / 2 is added in the negative direction of turning at the turning start position ST to the 180 ° turning range shown in FIG. 32, and fa / 2 is added in the positive direction of turning at the turning end position ED. Minutes have been added.

  Referring to FIG. 34, a detector existence area where the X-ray detector 128 exists and a safety area where the X-ray detector 128 does not exist will be described.

  The X-ray generator 126 and the X-ray detector 128 turn with a certain point as the turning center CTR. The turning center CTR is located at the position of the center A of the imaging region R during X-ray CT imaging. The X-ray CTB emitted from the X-ray generator 126 and passing through the turning center CTR is received by the X-ray detector 128. The area where the X-ray detector 128 exists in the illustrated state is the detector area DTA.

  The surface formed by the detection facing surface 128f which is the surface facing the turning center CTR of the X-ray detector 128 is defined as a detector surface 128fs, and the X-ray detector 128 between the detector surface 128fs and the turning center CTR is An area that does not exist is defined as a safe area SFA. In FIG. 34, the safety area SFA is an area with an oblique cross hatch. Within the safety area SFA, the distance DTD between the turning center CTR and the detector surface 128fs is not single but exists with a spread (as individual distance elements DTDe, for example, the illustrated distance elements DTDe1 and DTDe2, etc.). There is.).

  FIG. 35 is a diagram showing a detector presence area and a safety area in the setting example of FIG.

  With the turning movement of the X-ray detector 128, the same area as the detection movement trace OD is formed as the detector existence area DTA.

  The detector surface 128fs is formed in a U-shape when viewed from the Z direction with the turning movement of the detection facing surface 128f accompanying the turning movement of the X-ray detector 128.

  The safety area SFA is formed as a space surrounded by the detector surface 128fs.

  The distance between the turning center CTR in the safety area SFA and the surface of the head is DH. The distance DH is not unitary but exists with a wide range (as the individual distance element DHe, there is, for example, the illustrated distance element DHe1).

  For the distance DTD (all distance elements DTDe) and the distance DH (all distance elements DHe), the above-mentioned angle α is determined so that DTD> DH.

  However, when comparing the distance DH with the distance DTD, the comparison is performed so that the vector in the measurement direction of the distance element DTDe included in the distance DTD and the vector in the measurement direction of the distance element DHe included in the distance DH are aligned.

  The method of defining the safety zone SFA is not always unique. For example, as shown in FIG. 36, a region surrounded by the ends of the detector presence area DTA by the detector presence area DTA can be used as the safety area SFA.

  That is, in a broad concept, the safety area SFA may be considered as a peripheral area of the head P positioned outside the range of the detector existence area DTA, and the safety area SFA may be considered as an area surrounded by the detector existence area DTA. Good.

  However, the safety area SFA includes at least the safety area SFA shown in FIG.

  Assuming that a turning range corresponding to a certain shooting region R is a turning range RR, a detector presence area DTA is determined from the turning range RR, and the head P overlaps the safety area SFA based on a positional relationship between the head P and the shooting region R. , An angle α that does not overlap the detector presence area DTA is set.

  The angle α is, for example, the turning center CTR where the above-described detector surface 128fs is located at the position of the center A of the photographing region R with respect to the head P and the photographing region R positionally designated with respect to the head P. Can be determined by performing a simulation in which the surface of the head P is located within the safety area SFA.

  The X-ray generator 126 and the X-ray detector 128 rotate around the imaging region R of the head P, so that X-ray projection image data necessary for generating an X-ray CT image of the imaging region R is obtained. Is obtained, and an X-ray CT image is generated based on the data.

  When performing X-ray CT imaging in a turning range of 270 ° or less, the position of the turning axis X1 on the mechanism is moved according to the position of the shooting area R set and received by the shooting area position setting unit 151a, and It is preferable to perform X-ray CT imaging while fixing the rotation axis X1 at the position of the center A of the imaging region R. That is, when the position of the imaging region R (for example, the left molar or the right molar) is accepted by the imaging region position setting unit 151a, the position of the center A of the imaging region R in the XYZ coordinate system of the device 110 is determined. Therefore, the turning control unit 151b controls the turning axis moving mechanism 134 to move the turning axis X1 on the mechanism to the center A of the imaging region R. Then, X-ray CT imaging can be performed with the turning axis X1 on the mechanism fixed at the position of the center A of the imaging region R.

  Similarly, when the front teeth are set and received as the imaging region R, the position of the pivot axis X1 on the mechanism is moved, and the rotational axis X1 on the mechanism is fixed at the position of the center A of the imaging region R in the same manner. CT imaging may be performed.

  However, it is not essential to perform X-ray CT imaging while fixing the turning axis X1 on the mechanism to the position of the center A of the imaging region R, and turning the turning axis X1 on the mechanism around the center A of the imaging region R. The X-ray CT imaging may be performed while doing so.

<Effects>
According to the X-ray CT imaging apparatus 110 configured as described above, when the imaging region R is located at a position deviated left or right with respect to the median Mc of the head P, the central portion OrM of the X-ray detection trajectory Or. However, the X-ray generator 126 and the X-ray detector 128 are used to determine the turning range of the turning support 124 so that the imaging region R is located on the same side as the side on which the imaging region R is offset with respect to the median Mc. Can be prevented from contacting the head P. Further, in the above range, the X-ray detector 128 can be brought as close as possible to the imaging region R, so that a clearest X-ray CT image can be obtained.

  Further, since the X-ray detection trajectory Or is an arc trajectory that does not have a concave portion toward the imaging region R, the X-ray detector 128 is less likely to shake inward and outward, and a clear X-ray CT image is easily obtained. .

  In addition, when the imaging region R targets the front tooth region, the turning support portion 124 is arranged such that the central portion OrM of the arc of the X-ray detection trajectory Or is located on the front side of the head P on the plane including the median Mc. , The contact of the X-ray generator 126 and the X-ray detector 128 with the head P can be suppressed even when X-ray CT imaging of the front teeth is performed.

  Further, since the diameter of the rotation of the X-ray detector 128 with respect to the center A of the imaging region R is set smaller than the maximum distance LD, the X-ray detector 128 can be rotated as close to the head P as possible. As a result, a clear X-ray CT image can be obtained.

  In addition, since the turning drive mechanism 130 includes the turning axis moving mechanism 134 that moves the turning axis X1 on the mechanism in a direction intersecting the axial direction of the turning axis X1 on the mechanism, the turning axis X1 on the mechanism is moved to a fixed position. In the state where the turning support section 124 is turned while the turning support section 124 is turned, or the turning mechanism 132 turns the turning support section 124 about the turning axis X1 on the mechanism, the turning axis moving mechanism 134 turns the turning on the mechanism. The X-ray generator 126 and the X-ray detector 128 are turned around the center A of the imaging region R by moving the axis X1 to cause the turning support unit 124 to perform a synthetic motion, thereby obtaining an X-ray. The turning trajectory of the generator 126 and the X-ray detector 128 can be adjusted.

  Here, when performing X-ray CT imaging in a turning range of 270 ° or less, the position of the turning axis X1 on the mechanism is moved according to the position of the imaging region R set and received by the imaging region position setting unit 151a. X-ray CT imaging is performed with the turning axis X1 on the mechanism fixed at the position of the center A of the imaging region R. As a result, the X-ray generator 126 and the X-ray detector 128 can orbit in a stable orbit, and a clear X-ray CT image can be obtained as much as possible.

<Modification>
A modified example based on the first and second embodiments will be described.

  In the first and second embodiments, since the turning angle of the X-ray generator 126 and the X-ray detector 128 is 270 ° or less, the turning range of the X-ray detector 128 passing near the imaging region R is adjusted. Thus, a configuration for avoiding contact between the X-ray detector 128 and the head P has been proposed.

  When the turning angle of the X-ray generator 126 and the X-ray detector 128 turns 360 ° or more, the turning radius of the X-ray detector 128 is increased, and the X-ray detector 128 moves around the head P. It is possible to prevent the X-ray detector 128 from coming into contact with the head P even after one or more turns.

  The turning radius of the X-ray detector 128 is synchronized with the turning mechanism 132 turning the turning support portion 124 about the turning axis X1 on the mechanism, and the turning axis moving mechanism 134 moves the turning axis X1 on the mechanism. The X-ray generator 126 and the X-ray detector 128 are rotated around the center A of the imaging region R by moving the rotation support portion 124 to perform the synthetic motion, whereby the adjustment can be performed. In particular, here, when the X-ray generator 126 and the X-ray detector 128 are turned as described above, the turning axis moving mechanism 134 sets the turning axis X1 on the mechanism with the center A of the imaging region R as the rotation center. Rotate and move. The distance between the X-ray generator with respect to the center A of the imaging region R and the distance of the X-ray detector 128 with respect to the center A of the imaging region R can be kept constant.

  In the second embodiment, an example has been described in which the pivot axis X1 is closer to the X-ray detector 128 than to the X-ray generator 126. Therefore, if the X-ray detector 128 is turned while the turning axis X1 is coincident with the center A of the imaging region R partially specified in the dental arch Ar, the X-ray detection can be performed. The device 128 can turn near the shooting region R.

  Assuming this configuration, in the first modification, the X-ray generator 126 and the X-ray detector 128 are turned around the imaging region R by 360 ° or more for a part or all of the dental arch Ar. An example in which the turning radius is increased so that the X-ray detector 128 does not contact the head P will be described.

  In this case, as shown in FIG. 14, the turning axis X1 on the mechanism is moved away from the center A of the imaging region R toward the X-ray detector 128 so as to make the X-ray detector 128 farther away from the imaging region R. In this state, it is preferable to make a rotation around the center A of the photographing area R. That is, in a state where the turning axis X1 on the mechanism is located between the center A of the imaging region R and the X-ray detector 128, the turning axis X1 on the mechanism is turned in synchronization with the turning support 124. Just do it. In this case, the turning axis X1 on the mechanism moves on a circular orbit CL having a radius r, and the turning centers of the X-ray generator 126 and the X-ray detector 128 are kept in the same state as the center A of the imaging region R. It is. Assuming that the distance between the rotation axis X1 and the X-ray detector 128 is E (1) and the rotational radius of the mechanical rotation axis X1 with respect to the center of the imaging region R is r, the X-ray detector 128 with respect to the center A of the imaging region R. Has a rotation radius q of E (1) + r, so that the X-ray detector 128 can be turned with a larger diameter than that described in the second embodiment. When the distance between the rotation axis X1 and the X-ray generator 126 is E (2), the radius of rotation of the X-ray generator 126 with respect to the center A of the imaging region R is E (2) -r. In order to prevent the X-ray generator 126 from coming into contact with the head P, a range where E (1) + r is smaller than E (2) -r, that is, the X-ray detector 128 It is also assumed that r is set within a range approaching the photographing region R.

  The turning control of the turning axis X1 on the mechanism by the turning axis moving mechanism 134 can be realized by controlling as follows. The coordinates of the turning axis X1 on the mechanism are once considered with reference to FIG. For example, the coordinates of X and Y in the XYZ coordinate system of the center A of the imaging region R are (X (a), X (a)), and the turning angle of the turning support unit 124 by the turning mechanism 132 is θ (to the + X side). In the state where the X-ray generator 126 is provided and the X-ray detector (and the rotation axis X1) is on the −X side, it is assumed that they are rotated clockwise. The X coordinate of the turning axis X1 on the mechanism is “X (a) −rcosθ” by the X direction driving unit 136, and the Y coordinate of the turning axis X1 on the mechanism is “Y (a) + rsinθ” by the Y direction driving unit 138. The rotation axis movement mechanism 134 may be controlled in synchronization with the rotation control by the rotation mechanism 132. This control content can be similarly applied to the following modifications in which the turning axis X1 on the mechanism is turned.

  In the first modification, when the X-ray generator 126 and the X-ray detector 128 are turned 360 ° or more around the imaging region R, the turning radius is set so that the X-ray detector 128 does not contact the head P. Has been described, but this description can be applied to the case where the X-ray generator 126 and the X-ray detector 128 are turned by 270 ° or less.

  In the modification shown in FIGS. 15 and 16, both when the X-ray generator 126 and the X-ray detector 128 are turned at 270 ° or less (here, 180 °) and when they are turned at 360 °, An example in which the position of the mechanical turning axis X1 with respect to the center A of the imaging region R is controlled so that the position of the mechanical turning axis X1 is separated from the center A of the imaging region R will be described.

  FIG. 15 is an explanatory diagram showing a turning operation when the X-ray generator 126 and the X-ray detector 128 are turned at 270 ° or less (here, 180 °). In FIG. 15, it is assumed that a part (right molar) of the dental arch Ar is set as the imaging region R. FIG. 16 is an explanatory diagram showing a turning operation when the X-ray generator 126 and the X-ray detector 128 are turned 360 °. In FIG. 16, it is assumed that a part (front tooth) of the dental arch Ar is set as the imaging region R. Regardless of the position of the imaging region R, when the X-ray generator 126 and the X-ray detector 128 make a 360 ° turn, an operation and control for increasing the diameter of those turns are performed. Good. In the present modification, the turning axis X1 on the mechanism is located at the center between the X-ray generator 126 and the X-ray detector 128. For this reason, the distance of the X-ray generator 126 to the pivot axis X1 on the mechanism and the distance of the X-ray detector 128 to the pivot axis X1 are the same.

  When the X-ray generator 126 and the X-ray detector 128 are turned at 270 ° or less (here, 180 °), the contact between the X-ray detector 128 and the head P is avoided by adjusting the turning range. . For this reason, it is preferable to make the turning diameter of the X-ray detector 128 as small as possible and bring the X-ray detector 128 as close to the imaging region R as possible. Therefore, as shown in FIG. 15, while turning the turning axis X1 on the mechanism with the radius r (2) about the center A of the photographing region R, the turning support part 124 is moved about the turning axis X1 on the mechanism. Turn. More specifically, in synchronization with the turning mechanism 132 turning the turning support section 124 about the turning axis X1 on the mechanism, the turning axis X1 on the mechanism is moved by the turning axis moving mechanism 134 in the photographing region R. The vehicle is turned around the center A at a radius r (2). That is, the turning axis X1 on the mechanism moves on the circular orbit CL (2) having the radius r (2). In this case, in order to bring the X-ray detector 128 closer to the imaging region R, the turning axis X1 on the mechanism turns at a position away from the center A of the imaging region R toward the X-ray generator 126, and therefore, the turning on the mechanism. The axis X1 is between the center A of the imaging region R and the X-ray generator 126.

  If the X-ray generator 126 and the X-ray detector 128 are swiveled and CT imaging is performed with the rotation axis X1 on the mechanism coincident with the center A of the imaging region R, the X-ray detector 128 is largely separated from the imaging region R. A trajectory as shown in FIG. 15 is preferable when it is desired to take an image by bringing the X-ray detector 128 as close to the imaging region R as possible.

  When rotating the X-ray generator 126 and the X-ray detector 128 by 360 °, if the same orbit is drawn as described above, the X-ray detector 128 may come into contact with the rear part of the head P or the like.

  Therefore, in the example shown in FIG. 16, the turning support unit 124 is turned around the turning axis X1 on the mechanism while turning the turning axis X1 on the mechanism with the radius r (1) about the center A of the imaging region R. Turn. More specifically, in synchronization with the turning mechanism 132 turning the turning support section 124 about the turning axis X1 on the mechanism, the turning axis X1 on the mechanism is moved by the turning axis moving mechanism 134 in the photographing region R. The robot is turned around the center A at a radius r (1). Note that radius r (1) <radius r (2). The turning axis X1 on the mechanism moves on a circular orbit CL (1) having a radius r (1). Further, the turning axis X1 on the mechanism turns at a position distant from the center A of the imaging region R toward the X-ray generator 126, and therefore, the turning axis X1 on the mechanism is aligned with the center A of the imaging region R and the X-ray generation. With the vessel 126.

  In this case, the turning diameter of the X-ray detector 128 is larger than in the case shown in FIG. Here, it is larger by radius r (2) -radius r (1). Therefore, even if the X-ray detector 128 is rotated by 360 °, the X-ray detector 128 can rotate around the head P without making contact with the head P. Since the X-ray generator 126 turns at a position farther away from the imaging region R than the X-ray detector 128, contact with the head P is avoided.

  As described above, both when the X-ray generator 126 and the X-ray detector 128 are turned by 270 ° or less (here, 180 °) and when they are turned by 360 °, the turning axis X1 on the mechanism is set to be equal to or smaller than 270 °. It may be away from the center A of the photographing region R. In this case, depending on the positional relationship of the turning axis X1 between the X-ray generator 126 and the X-ray detector 128, the direction in which the turning axis X1 is shifted on the mechanism, the radius r (1), and the radius r (2) are different. The magnitude relationship may be reversed.

  When the X-ray generator 126 and the X-ray detector 128 are turned at 270 ° or less (here, 180 °), the turning axis X1 on the mechanism is turned around the center A of the imaging region R with a radius r. While rotating, the turning support unit 124 is turned around the turning axis X1 on the mechanism, and the X-ray generator 126 and the X-ray detector 128 are turned 360 °. The turning support 124 may be turned in a state where the turning support 124 is aligned with the center A. For example, when the turning axis X1 on the mechanism is at or near the center position between the X-ray generator 126 and the X-ray detector 128 as in the above modification, the X-ray generator 126 and the X-ray detection When the container 128 is turned 360 °, the turning support 124 may be turned in a state where the turning axis X1 on the mechanism coincides with the center A of the photographing region R.

  As described above, in synchronization with the turning mechanism 132 turning the turning support section 124 about the turning axis X1 on the mechanism, the turning axis X1 on the turning axis moving mechanism 134 mechanism is moved to turn the turning support section. Since the X-ray generator 126 and the X-ray detector 128 can rotate around the center A of the imaging region by performing the synthetic movement, the rotation can be performed according to the rotation range, the position of the imaging region R, and the like. Thus, it is possible to adjust the turning trajectory of the X-ray generator 126 and the X-ray detector 128, particularly the turning diameter.

  At this time, since the turning axis moving mechanism 134 rotates the turning axis X1 on the mechanism about the center A of the imaging region R as a rotation center, even if the turning axis X1 on the mechanism is moved, the X-ray generators 126 and X The line detector 128 can move along a trajectory of a circle or a trajectory close to a circle.

  In addition, during X-ray CT imaging, the distance between the X-ray generator 126 with respect to the center A of the imaging region R and the distance of the X-ray detector 128 with respect to the center A of the imaging region R are kept constant. X-ray CT imaging can be performed while keeping the rate constant.

<< 3rd Embodiment >>
An X-ray CT imaging apparatus according to the third embodiment will be described. In the description of the present embodiment, the same components as those described in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  FIG. 17 is a block diagram showing an electrical configuration of the X-ray CT imaging apparatus 210. Note that the X-ray CT imaging apparatus 210 according to the third embodiment is mounted on an apparatus having the same configuration as the X-ray CT imaging apparatus 110 described in the second embodiment.

  The X-ray CT imaging apparatus 210 differs from the X-ray CT imaging apparatus 110 in that the X-ray CT imaging apparatus 110 includes a turning range setting unit 251a, and that the imaging program 253a corresponding to the imaging program 153a is set in the turning range setting unit 251a. The point is that the turning control of the X-ray generator 126 and the X-ray detector 128 is performed according to the turning range.

  That is, the turning range setting unit 251a receives the setting of the turning range of the turning support unit 124 in X-ray CT imaging. The setting of the turning range is, for example, whether the turning is 270 ° or less or the turning is 360 ° or more.

  The turning control unit 251b corresponding to the turning control unit 151b, when the turning range setting unit 251a receives the setting of turning of 270 ° or less based on the photographing program 253a, as described in the second embodiment, The turning control of the X-ray generator 126 and the X-ray detector 128 is performed. That is, when the setting of the rotation of 270 ° or less is accepted, the rotation range of the X-ray detector 128 is biased to the same side as the imaging region R, so that the X-ray detector 128 and the head P Avoid contact.

  On the other hand, when the setting of the turning of 360 ° or more is accepted by the turning range setting unit 251a, the maximum distance of the surface of the head P with respect to the center A of the imaging region R is set to the maximum distance, and the centers A and X of the imaging region R are set. When the smaller of the distance from the line generator 126 and the distance between the center A of the imaging region R and the X-ray detector 128 is defined as the separation distance, the imaging region position setting unit 151a sets a part of the dental arch. Is set as an imaging region R, and X-ray CT imaging is performed. At this time, a mechanism with respect to the center A of the imaging region R is set so that the separation distance is larger than the maximum distance according to the position of the imaging region R. The position of the upper turning axis X1 is changed.

  FIG. 18 is a flowchart showing the processing by the turning control unit 251b.

  That is, when performing X-ray CT imaging, setting of the size of the imaging region is received in step S21. The size of the shooting area can be set and accepted in the same manner as described in the second embodiment.

  Proceeding to the next step S22, it is determined whether the size of the imaging region targets the entire dental arch or a part of the dental arch. If it is determined that the size of the imaging region is for the entire arch row, the process proceeds to step S32, and CT imaging is performed for the entire arch row. The turning trajectory of the X-ray detector 128 and the X-ray generator 126 in this case may be the same as that of performing X-ray CT imaging on a part of the front teeth of the dental arch.

  If it is determined in step S22 that the size of the imaging region targets a part of the dental arch row, the process proceeds to step S23.

  In step S23, the setting of the turning range is received.

  Here, an example of accepting the setting of the turning range will be described. FIG. 19 shows a display example in which an image for accepting the setting of the turning range is added to the display example on the operation panel device 158 described in the second embodiment. A turning range setting image 293 is additionally displayed on the display unit 158a of the operation panel device 158. Here, the turning range setting image 293 is displayed on the right side of the display unit 158a and below the shooting region setting image 194.

  When the operator touches the turning range setting image 293, a selection image corresponding to the turning range setting image 293 is displayed as shown in FIG. A 180 ° selection image 293a and a 360 ° selection image 293b are displayed as a plurality of turning range selection images. When the user selectively touches any one of the 180 ° selection image 293a and the 360 ° selection image 293b, the turning range setting operation is accepted. Of course, in addition to these or in place of the 180 ° selection image 293a, a 180 ° + fa selection image 293c (not shown) for selecting a turning angle obtained by adding the fan angle of the X-ray beam to 180 ° can be selected. Is also good.

  In the above example, the turning range is set using the touch panel. However, the turning range may be received via a switch (push button) or the like that physically receives the operation.

  In steps S23 and S24, when a 180 ° turn is accepted as the turn range, the processing of steps S25 to S27 is executed. The processing of steps S25 to S27 can be the same as the processing of steps S11 to S13 described in the second embodiment. This makes it possible to avoid contact between the X-ray detector 128 and the head P when X-ray CT imaging is performed by rotating the X-ray detector 128 or the like at 270 ° or less (180 °).

  In step S23, when a 360 ° turn is received as the turn range, the processing of steps S28 to S31 is executed.

  As described in the modification of the second embodiment, when the X-ray detector 128 is rotated by 360 °, the diameter of the rotation of the X-ray detector 128 may be increased. However, the position of the shooting area in the subject varies. If the position of the turning axis X1 on the mechanism is adjusted in accordance with the position of the imaging region in the subject, and if the turning trajectories of the X-ray generator 126 and the X-ray detector 128 that turn around the subject are devised, the position around the subject can be improved. The X-ray detector 128 can be brought as close as possible to the imaging region R while suppressing that the X-ray generator 126 and the X-ray detector 128 that turn around contact the subject. In steps S28 to S31, processing for that is executed.

  In step S28, an operation for setting the position of the imaging region R is accepted. Acceptance of the setting operation of the position of the imaging region R can be performed in the same manner as described in step S11.

  In the next step S29, the contents of the turning control and the regulation amount are determined according to the position of the set photographing area. The turning control content indicates what trajectory the X-ray generator 126 and the X-ray detector 128 are turned around the head P. The details of the turning control include the trajectory of at least one of the X-ray generator 126 and the X-ray detector 128, the moving trajectory of the turning axis X1 on the mechanism by the turning axis moving mechanism with respect to the turning speed by the turning mechanism 132, and the turning by the turning mechanism 132. It is represented by the movement coordinates of the X-direction drive unit 136 and the Y-direction drive unit 138 with respect to the turning speed of the turning of the support unit 124.

  When the rotation control content is determined, the distance between the center A of the imaging region R and the X-ray generator 126 when the X-ray generator 126 and the X-ray detector 128 are driven to rotate around the center A of the imaging region R is determined. Assuming that the smaller one of the distance between the center A of the imaging region R and the X-ray detector 128 is the separation distance D, the separation distance D is determined. Here, since the turning axis X1 is closer to the X-ray detector 128 in the turning support section 124, the separation distance D is the distance between the center A of the imaging region R and the X-ray detector 128. Since the head P is held at a fixed position by the head fixing device 142 and the imaging region is set as described above, the position of the imaging region R in the device 110 is known. .

  Further, since the distance of the X-ray generator 126 to the center A of the imaging region R is also determined, the magnification when the X-rays emitted from the X-ray generator 126 pass through the head P and enter the X-ray detector 128 Also determined. Assuming that the distance between the X-ray generator 126 and the X-ray detector 128 is DA and the distance between the X-ray generator 126 and the center A of the imaging region R is D, the magnification m is m = DA / D.

  Further, when the content of the turning control is determined, the minimum width of the X-ray for allowing the X-ray generated from the X-ray generator 126 to pass through the entire imaging region R is determined. The width of the X-ray restriction width (X-ray restriction hole) should also be set to the minimum width, or at least a range larger than the minimum width and a range in which the surrounding area is not excessively irradiated with X-rays. Can be.

  The determination of the turning control content and the regulation amount according to the set position of the imaging region can be performed by referring to a reference table as shown in FIG. 21, for example. That is, a reference table in which the details of the turning control, the separation distance D (magnification m), and the restriction width W are associated with the position of the imaging region is registered in advance. In the example shown in FIG. 21, the X-ray detector 128 is turned by the radius q (1) with respect to the case where the position of the imaging region is the front tooth, the separation distance D (1) (magnification m (1)), The restriction width W (1) is associated with the restriction width W (1). If the turning of the X-ray detector 128 at the radius q (1) is defined by the turning details of the turning axis X1, it can be expressed as turning the turning axis X1 at the radius r (1). Note that, in order to move the X-ray detector 128 away from the imaging region R, the turning axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the imaging region R. In addition, when the position of the imaging region is a molar, the X-ray detector 128 is turned with a radius q (2), the separation distance D (2) (magnification m (2)), and the regulation width W (2). ) Is associated. If the turning of the X-ray detector 128 at the radius q (2) is defined by the turning details of the turning axis X1, it can be expressed as turning the turning axis X1 at the radius r (2). In order to move the X-ray detector 128 away from the imaging region R, the rotation axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the imaging region R.

  The radius q (1) (r (1)), the separation distance D (1), the magnification m (1), the regulation width W (1), the radius q (2) (r (2)), the separation distance D ( 2), the magnification m (2), and the regulation width W (2) have specific numerical values. As described later, when the position of the imaging region is set to the front teeth, the X-ray detector 128 is located farther from the center A of the imaging region than when the position of the imaging region is set to the molar teeth. Radius q (1)> radius q (2) (radius r (1) <radius r (2)), separation distance D (1)> separation distance D (2), magnification m (1)> magnification m (2 ), The regulation width W (1)> the regulation width W (2).

  Based on the set imaging region R, it is determined whether the imaging region R is an anterior tooth or a molar, and based on the determination result, the corresponding turning control content, separation distance D (magnification m), and restriction width W Is determined. The determination of the position (front teeth or molars) of the photographing region R based on the set photographing region R is performed by, for example, determining whether the coordinates of the center A of the set photographing region R belong to the preset front tooth region or the molar region. Can be determined by determining. The imaging region in the lookup table may be divided into a larger number of regions for the dental arch.

  Here, in the reference table, it is assumed that the physique (size) of the head P is the same, and the contents of the turning control corresponding to the position of the photographing region R are defined. For each of (for example, a head for an adult physique and a head for a child's physique), the turning control content corresponding to the position of the imaging region R may be defined in the same manner as described above. In this case, according to the physique input by the runner, the turning control content corresponding to the position of the imaging region R corresponding to the physique may be determined.

  In the next step S30, the X-ray regulating unit 129 is controlled in accordance with the decided regulation widths W (1) and W (2), and the X-ray detector 128 sends the X-ray having a width corresponding to the imaging region R. The line is illuminated.

  In the next step S31, a CT control is performed by performing a turning control based on the determined turning control contents. That is, since the turning range of 360 ° or more is set by the turning range setting unit 251a, the distance between the center A of the imaging region R and the X-ray generator 126, the center A of the imaging region R and the X-ray detector When the smaller one of the distances to the distance 128 is defined as the separation distance D, a partial region of the dental arch Ar is set as the imaging region R, and X-ray CT imaging is performed. In accordance with the position of the imaging region R, a mechanism with respect to the center A of the imaging region R is set such that the separation distance D is larger than the maximum distance LD which is the maximum distance of the surface of the head P from the center A of the imaging region R. Change the position of the turning axis X1. Note that the maximum distance LD changes depending on the position of the imaging region R.

  This turning operation will be described more specifically with reference to FIGS.

  In the example shown in FIG. 22, a molar region on one side, which is a part of the dental arch Ar, is designated as the imaging region R. In the example shown in FIG. 23, the anterior tooth region that is a part of the dental arch Ar is designated as the imaging region R. The front tooth region is defined as a first imaging region R (1), and the molar region is defined as a second imaging region R (2).

  Assume a maximum distance LD of the imaging region R with respect to the surface of the head P. In the case where the front tooth region is the first imaging region R (1), the front tooth region is a local region at a position closer to the front of the head P (a position biased forward). The distance between the center A of the first imaging region R (1) and the rear surface of the head P is the maximum distance LD (1) (see FIG. 23). When the molar region is the second photographing region R (2), the molar region is located closer to the center in the front-rear direction of the head P and closer to one side in the width direction. The surface is farthest from the second imaging region R (2), and the distance between the center A of the second imaging region R (2) and the rear surface of the head P is the maximum distance LD (2) (see FIG. 22). Since the head P has a shape similar to an elliptical shape that is long in the front-rear direction, the maximum distance LD (1) when the front teeth are set to the first imaging region R (1) is generally smaller than the second molar region for the front teeth. It is larger than the maximum distance LD (2) in the case of the shooting area R (2). Therefore, when the front teeth are set to the first imaging region R (1), the imaging region of the X-ray generator 126 and the X-ray detector 128 is set to be smaller than the case where the molar region is set to the second imaging region R (2). It is better to turn the closer one outside.

  Therefore, when X-ray CT imaging is performed with the molar region as the second imaging region R (2), the mechanism is set so that the radius of rotation of the X-ray detector 128 is q (2) as shown in FIG. The turning support 124 is turned while the turning axis X1 is moved. The distance between the center A and the X-ray detector 128 in this case is the separation distance D (2). Here, the turning axis X1 on the mechanism is shifted to the X-ray detector 128 side and turned at the radius r (2).

  The concept of the detector surface, the detector presence area, and the safety area can be applied to X-ray CT imaging of 360 ° rotation. In the case of 360-degree X-ray CT imaging, the detector surface, the detector presence area, and the safety area all have an annular shape. Also in this relation, the shift radius r is determined so that DTD> DH.

  If the X-ray generator 126 and the X-ray detector 128 are turned along the same trajectory as the first imaging region R (1) as the front tooth region, the X-ray detector 128 may come into contact with the head P. The head P when the X-ray generator 126 and the X-ray detector 128 are turned on the same trajectory is shown by a two-dot chain line in FIG. The second imaging region R (2) for the head P indicated by the solid line is the first imaging region R (1) for the head P indicated by the two-dot chain line (see FIG. 22). As for the head P indicated by the two-dot chain line, it can be seen that the X-ray detector 128 may come into contact with the head P when it comes to the −Y side.

  Therefore, when performing X-ray CT imaging using the front tooth region as the first imaging region R (1), as shown in FIG. 23, the turning radius of the X-ray detector 128 is set to the radius q (1) (q (1)). > Q (2)), while turning the turning axis X1 on the mechanism, the turning support 124 is turned. The distance between the center A and the X-ray detector 128 in this case is the separation distance D (1). Here, the turning axis X1 on the mechanism is shifted toward the X-ray detector 128 and turned at a radius r (1) (r (1)> r (2)).

  In this case, the X-ray generator 126 turns while drawing a smaller radius than that shown in FIG. The X-ray detector 128 turns with a larger radius than the case shown in FIG. The relationship between the trajectory of the X-ray generator 126 and the trajectory of the X-ray detector 128 shown in FIG. 23 is closer to each other than those shown in FIG. Therefore, the X-ray generator 126 and the X-ray detector 128 can turn around the head P without making contact with the head P.

  Then, the X-ray generator 126 and the X-ray detector 128 rotate around the imaging regions R (1) and R (2) of the head P to generate an X-ray CT image of the imaging region R. Is obtained, and an X-ray CT image is generated based on the data.

  As described above, the turning radius r of the X-ray detector 128 is set so that the turning axis X1 on the mechanism coincides with the center A of the imaging region R, and the turning axis X1 on the mechanism is moved around the center A of the imaging region R. When turning, or turning the turning axis X1 around the center A, the turning axis X1 is shifted toward the X-ray detector 128 or the X-ray generator 126, and the amount of shift is adjusted. It can be adjusted by doing. The position of the turning axis X1 on the mechanism is adjusted according to the position of the turning axis X1 on the mechanism between the X-ray generator 126 and the X-ray detector 128.

  According to the present embodiment, when a turning range of 270 ° or less is set, the turning diameter r of the X-ray detector 128 with respect to the center A of the CT imaging region R is smaller than the maximum distance LD, and X Since the line detector 128 turns in a range deviated to the same side as a side in which a part of the dental arch Ar is deviated according to the position of the imaging region R set by the imaging region position setting unit 151a, X It is possible to prevent the ray generator 126 and the X-ray detector 128 from coming into contact with the head P, and to obtain an X-ray CT image that is as clear as possible.

  When a turning range of 360 ° or more is set, shooting is performed such that the separation distance D is larger than the maximum distance LD according to the position of the shooting region R set by the shooting region position setting unit 151a. By changing the position of the mechanical turning axis X1 with respect to the center of the region R, the X-ray generator 126 and the X-ray detector 128 that turn 360 degrees or more around the head P, which is the subject, come into contact with the head P. Can be suppressed.

  As the turning range of 270 ° or less, it is preferable to accept a turning range of 180 ° or an angle obtained by adding the spread angle of the X-ray beam irradiation (see the angle β in FIG. 15) to 180 °. Further, it is preferable that a 360 ° turning range be accepted as a turning range of 360 ° or more. As a result, when performing a full scan by CT imaging at 360 ° and a half scan by CT imaging at around 180 °, the X-ray generator 126 and the X-ray detector 128 that rotate around the head P Can be suppressed.

  Further, when adjusting the turning diameter of the X-ray generator 126 and the X-ray detector 128, the turning mechanism 132 turns in synchronization with turning the turning support portion 124 about the turning axis X1 on the mechanism. The axis moving mechanism 134 moves the turning axis X1 on the mechanism to cause the turning support part 124 to perform a synthetic motion, so that the X-ray generator 126 and the X-ray detector 128 are moved around the center A of the imaging region R. When turning, the turning axis moving mechanism 134 causes the turning axis X1 on the mechanism to rotate around the center A of the imaging region R as the rotation center. Therefore, when performing X-ray CT imaging, the turning axis X1 on the mechanism is moved. However, the X-ray generator 126 and the X-ray detector 128 can be turned along a trajectory as close to a circle as possible.

  In addition, during X-ray CT imaging, the distance between the X-ray generator 126 with respect to the center A of the imaging region R and the distance of the X-ray detector 128 with respect to the center A of the imaging region R are kept constant. X-ray CT imaging can be performed while keeping the rate constant.

<Modification>
When turning the X-ray generator 126 and the X-ray detector 128 around the imaging region R, the position of the turning axis may be controlled according to the size of the physique of the head P as the subject.

  In the following modified example, an example in which the separation distance D is adjusted according to the size of the physique of the head P, which is a subject, with respect to the processing of step S32 in the third embodiment will be described.

  In other words, the X-ray CT imaging apparatus 210 sets the size of the physique of the head P, which is a subject, as a physique setting of a subject that can accept a first physique and a second physique smaller than the first physique. A part 258 is provided (see FIG. 17, hereinafter referred to as a physique setting part 258). Further, the photographing program 253a includes a process of changing the position of the mechanical turning axis X1 with respect to the center A of the photographing region R in accordance with the size of the subject's physique set by the subject's physique setting unit 258. Therefore, the turning control unit 251b, based on the shooting program 253a, sets the mechanical turning axis X1 with respect to the center A of the shooting region R in accordance with the size of the physique of the subject set by the physique setting unit 258 of the subject. Execute the control to change the position. More specifically, the turning control unit 251b determines the separation distance when the physique of the set subject is the first physique according to the size of the physique of the subject set by the physique setting unit 258 of the subject. The position of the mechanical turning axis X1 with respect to the center A of the photographing region R such that D is larger than the separation distance D when the set physique of the subject is the second physique smaller than the first physique. To change.

  FIG. 24 is a flowchart showing the above processing by the turning control unit 251b.

  That is, when performing X-ray CT imaging for the entire old dentition, in step S41, the input setting of the physique is accepted.

  Here, an example of receiving a physique input operation will be described. FIG. 25 shows a display example in which an image for accepting a physique input operation is added to the display example on the operation panel device 158 described in the second embodiment. On the display unit 158a of the operation panel device 158, a physique setting image 393 is additionally displayed. Here, the physique setting image 393 is displayed on the right side of the display unit 158a and above the shooting region setting image 194.

  When the operator touches the physique setting image 393, a selection image corresponding to the physique setting image 393 is displayed as shown in FIG. As the plurality of physique selection images, a normal size selection image 393a (M size) and a large size selection image 393b (L size) are displayed. When the user selectively touches one of the normal size selection image 393a and the large size selection image 393b, the input operation of the physique of the head P as the subject is accepted.

  In the above example, the description has been given of an example in which the physique setting is performed using the touch panel. However, the physique setting may be received via a switch (push button) or the like that physically receives an operation.

  Returning to FIG. 24, in step S42, when the physique setting unit 258 receives the input operation of the physique of the head P through the operation panel device 158, the turning control unit 251b outputs the physique of the head P according to the received content. Make settings. Here, the physique setting unit 258 receives, via the operation panel device 158, an input operation for selecting one of the normal size selection image 393a and the large size selection image 393b, which are the physique sizes of a plurality of selection candidates, and thereby the head P Set the physique of the. The large size selection image 393b is an image for accepting a first physique, the normal size selection image 393a is an image for accepting a second physique smaller than the first physique, and one of them is selected. Then, the first physique and the second physique are selectively set.

  The physique setting unit 258 may automatically recognize the physique of the head P and set the physique. As an example of automatically recognizing the physique of the head P, for example, an image of the head P as a subject is extracted, a head region is extracted from the captured image, and the size of the head is calculated from the extracted head region. Setting the physique by recognizing the size of the head, providing a holding portion for holding the head P in the head fixing device 142 for fixing the head from the left and right or the front-back direction, and using a sensor or the like to determine the opening degree of the holding portion with a sensor or the like. By detecting, it is conceivable to recognize the size of the head and set the physique.

  In the next step S43, the details of the turning control, the regulated amount, and the like are determined according to the set physique. The determination of the turning control content and the regulation amount according to the set physique can be performed with reference to a reference table as shown in FIG. 27, for example. That is, the turning control contents, the separation distance D (magnification m), and the regulation width W are associated with each of the normal physique P (M) and the large physique P (L).

  In the example shown in FIG. 27, for the normal physique P (M), the X-ray detector 128 is turned with a radius q (M) as turning control contents, and the separation distance D (M) (magnification m (M) ) And the regulation width W (M) are associated with each other. Turning the X-ray detector 128 at the radius q (M) can be expressed as turning the turning axis X1 at the radius r (M), if it is defined by the turning details of the turning axis X1. Note that, in order to move the X-ray detector 128 away from the imaging region R, the turning axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the imaging region R. In addition, for the large physique P (L), the X-ray detector 128 is turned by the radius q (L), the separation distance D (L) (magnification m (L)), and the regulation width W (L) are supported. It is attached. Turning the X-ray detector 128 at the radius q (L) can be expressed as turning the turning axis X1 at the radius r (L), if it is defined by the turning details of the turning axis X1. In order to move the X-ray detector 128 away from the imaging region R, the rotation axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the imaging region R.

  The radius q (M) (r (M)), the separation distance D (M), the magnification m (M), the regulation width W (M), the radius q (L) (r (L)), the separation distance D ( Specific numerical values are defined for L), magnification m (L), and regulation width W (L). As described later, the X-ray detector 128 is positioned farther from the center A of the imaging region when the body size is large (P (L)) than when the body size is normal (P (M)). Radius q (M) <radius q (L) (radius r (M) <radius r (L)), separation distance D (M) <separation distance D (L), magnification m (M) <magnification m (L ), The regulation width W (M) <the regulation width W (L).

  In the next steps S44 and S45, the X-ray regulating unit 129 is controlled in accordance with the determined regulation amounts W (M) and W (L), and the X-ray detector 128 controls the width in accordance with the imaging region R. X-rays are irradiated.

  The turning operation based on the turning control will be described more specifically with reference to FIGS. FIG. 28 is an explanatory view showing a turning operation when the physique is a second physique P (M) having a relatively small physique, and FIG. 29 is a turning motion when a physique is a first physique P (L) having a relatively large physique. It is explanatory drawing which shows operation | movement.

  In the case where the physique is the second physique P (M), the turning support part 124 is turned so that the turning diameter of the X-ray detector 128 becomes the diameter q (M) as shown in FIG. Let it. More specifically, in synchronization with the turning mechanism 132 turning the turning support section 124 about the turning axis X1 on the mechanism, the turning axis X1 on the mechanism is moved by the turning axis moving mechanism 134 in the photographing region R. The vehicle is turned around the center A with a radius r (M). The turning axis X1 on the mechanism is shifted to the X-ray detector 128 side. Since the X-ray detector 128 is closer to the center A of the imaging region R than the X-ray generator 126, the separation distance D (M) is the distance between the center A of the imaging region R and the X-ray detector 128. . The separation distance D (M) is the maximum between the center A of the imaging region R and the surface of the head P (P2) having the smaller second physique P (M) in a direction orthogonal to the rotation axis X1. It is set larger than the distance LD. Therefore, the X-ray detector 128 can rotate around the head P (P2) without contacting the head P (P2) having the smaller second body size P (M). Since the X-ray generator 126 turns at a position farther away from the center A of the imaging region R than the X-ray detector 128, the X-ray generator 126 does not come into contact with the head P (P2) and It is possible to pivot around the part P (P2). On the orbit during X-ray imaging of the X-ray generator 126 and the X-ray detector 128 set for the imaging region R, the X-ray generator 126 is closer to the imaging center A than the X-ray detector 128. In this case, the separation distance D (not shown) is the distance between the center A of the imaging region R and the X-ray generator 126.

  The chin rest 142a is commonly used for both the head P having the second physique P (M) and the head P having the first physique P (L). The head P having the first physique P (L) is larger on the −Y side than the head P having the second physique P (M). Occupy the area. When the X-ray detector 128 turns in the same manner as described above for the first physique P (L) having a relatively large physique, the X-ray detector 128 turns the head P having the first physique P (L). May abut.

  Therefore, when the physique is the first physique P (L) having a relatively large physique, as shown in FIG. 29, the turning support portion 124 is turned so that the turning diameter q (L) of the X-ray detector 128 becomes the same. Let it. More specifically, in synchronization with the turning mechanism 132 turning the turning support section 124 about the turning axis X1 on the mechanism, the turning axis X1 on the mechanism is moved by the turning axis moving mechanism 134 in the photographing region R. The vehicle is turned around the center A with a radius r (L) (r (L)> r (M)). The turning axis X1 on the mechanism is shifted to the X-ray detector 128 side. Also in this case, since the X-ray detector 128 is closer to the center A of the imaging region R than the X-ray generator 126, the separation distance D (L) is equal to the center A of the imaging region R and the X-ray detector 128. D (L). The separation distance D (L) is the surface of the head P (P (L)) having the larger first physique P (L) with the center A of the imaging region R in the direction orthogonal to the rotation axis X1. Is set to be longer than the maximum distance LD. Therefore, the X-ray detector 128 moves around the head P (P (L)) without contacting the head P (P (L)) having the larger first physique P (L). Can turn. Since the X-ray generator 126 turns at a position farther away from the center A of the imaging region R than the X-ray detector 128, the X-ray generator 126 also does not contact the head P (P (L)). In addition, it is possible to turn around the head P (P (L)). On the orbit during X-ray imaging of the X-ray generator 126 and the X-ray detector 128 set for the imaging region R, the X-ray generator 126 is closer to the imaging center A than the X-ray detector 128. In this case, the separation distance D (not shown) is the distance between the center A of the imaging region R and the X-ray generator 126.

  It should be noted that, as shown in FIG. 28, a comparison is made between a second physique P (M) having a relatively small physique and a first physique P (L) having a relatively large physique as shown in FIG. Then, the distance between the center A of the imaging region R and the X-ray detector 128 is greater in the latter than in the former. Therefore, in order for the X-rays emitted from the X-ray generator 126 to pass through the entire imaging region R, the X-ray restricting unit 129 controls the X-rays at the time of the second physique P (M). The restriction width W (M) may be set to be smaller than the X-ray restriction width W (L) by the X-ray restriction unit 129 when the first physique is P (L). Thus, X-rays can be emitted in a range corresponding to the imaging region R. In other words, the regulation widths W (L) and W (M) are the separation distances D (L) and D (L) when the X-ray generator 126 and the X-ray detector 128 are turned around the center A of the imaging region R. M), and the X-ray regulating unit 129 adjusts the regulated amount of X-rays generated from the X-ray generator 126 according to the separation distances D (L) and D (M).

  The X-ray regulation width W by the X-ray regulation unit 129 may be adjusted only in the x-direction regulation width Wx, or may be adjusted in addition to the y-direction regulation width Wy.

  The X-ray generator 126 and the X-ray detector 128 rotate around the imaging region R of the head P to generate an X-ray CT image of the imaging region R covering the entire dental arch. Necessary X-ray image data is obtained, and an X-ray CT image is generated based on the data.

  According to this modification, the separation distance D (L) when the physique P (L) of the head P is large is determined by the physique P (M) according to the size of the physique of the head P set by the physique setting unit 258. ) Is smaller than the separation distance D (M) when the X-ray generator 126 is turned around the head P to change the position of the mechanical turning axis X1 with respect to the center A of the imaging region R. And the X-ray detector 128 can be prevented from contacting the head P.

  In the above modified example, the turning axis X1 on the mechanism is turned around the center A of the photographing region R both when the physique P (L) of the head P is large and when the physique P (M) is small. In the case where the turning axis X1 on the mechanism is located near the center between the X-ray generator 126 and the X-ray detector 128, as shown in FIG. 30, the second physique P (M) having a small physique is provided. , The turning axis X1 on the mechanism may be made to coincide with the position of the center A of the imaging region R. In this case, as shown in FIG. 31, when the physique of the head P is the first physique P (L), the turning axis X1 on the mechanism is shifted to the X-ray detector 128 side, and the The position of the turning axis X1 may be separated from the center of the imaging region R, and the position of the turning axis X1 on the mechanism with respect to the center A of the imaging region R may be changed. When the diameter of the rotation of the X-ray detector 128 is reduced, the position of the rotation axis X1 on the mechanism is set to the center of the imaging region R in a direction to shift the rotation axis X1 on the mechanism toward the X-ray generator 126. , And the position of the turning axis X1 on the mechanism with respect to the center A of the photographing region R may be changed.

  As described above, the smaller distance between the distance of the X-ray generator 126 to the center A of the imaging region R and the distance of the X-ray detector 128 to the center A of the imaging region R depends on the size of the physique. The process of adjusting the position of the turning axis X1 on the mechanism so that the distance is larger than the maximum distance can be applied to the process of performing X-ray CT imaging on a part of the dental arch Ar. When performing X-ray CT imaging on a part of the dental arch Ar, the X-ray generator 126 and the X-ray detector 128 are turned in a range of 270 ° or less, or 360 ° or more. Also, the process of adjusting the position of the turning axis X1 on the mechanism according to the size of the physique can be applied.

｛Modified example｝
Further, in each of the above-described embodiments and each of the modified examples, the description has been given on the assumption that the normal scan in which the entire imaging region R is irradiated with X-rays. The present invention can also be applied to a case where an offset scan for irradiating X-rays is performed.

  The components described in each of the above embodiments and modifications can be appropriately combined as long as they do not conflict with each other.

  Although the present invention has been described in detail as described above, the above description is merely an example in all aspects, and the present invention is not limited thereto. It is understood that innumerable modifications that are not illustrated can be assumed without departing from the scope of the present invention.

10, 110, 210 X-ray CT imaging apparatus 20, 124 Rotation support part 22, 126 X-ray generator 24, 128 X-ray detector 30, 230 Rotation drive mechanism 32, 132 Rotation mechanism 40, 151a Imaging area position setting part 60 , 151b, 251b Rotation control unit 120 Imaging main unit 129 X-ray restriction unit 134 Rotation axis moving mechanism 142 Head fixing device 150 Main unit control unit 151 CPU
153a, 253a Shooting program 153b Lookup table 158 Operation panel device 194 Image for setting shooting region 194a to 194e Image for selecting shooting region 195 Illustration image 195a, 195b Shooting region image 251a Turning range setting unit 258 Physical size setting unit 293 Image for turning range setting 293a 180 ° selection image 293b 360 ° selection image 393 Body size setting image 393a Normal size selection image 393b Large size selection image A Imaging center Ar Dental arch D Separation distance LD Maximum distance P Head R (X-ray CT) imaging region R ( 1) First shooting area R (2) Second shooting area q, r diameter

Claims (10)

An X-ray generator for generating X-rays,
An X-ray detector that detects the X-ray;
A turning support unit in which the X-ray generator and the X-ray detector are supported so as to face each other across the head of the subject;
A turning drive mechanism including a turning mechanism for turning the turning support portion,
An imaging region position setting unit that receives a setting of a position of an X-ray CT imaging region in which a local region that is a part of the dental arch of the head is subjected to X-ray CT imaging;
A turning control unit for controlling the turning drive mechanism,
With
While the turning control unit drives and controls the turning drive mechanism to perform X-ray CT imaging of the X-ray CT imaging region by the X-ray, the X-ray generator and the X-ray detector are connected to the head. Around the head in a turning range of 270 ° or less, and the X-ray detector passes through the side of the head where the X-ray CT imaging region is unevenly distributed in the head, An X-ray generator passes on the opposite side of the head around the head, and the X-ray detector forms an X-ray detection trajectory of an arc by the turning movement during the X-ray CT imaging. ,
When the X-ray CT imaging area set by the imaging area position setting unit is located at a position deviated to the right or left with respect to the center of the head, the center of the arc of the X-ray detection trajectory is An X-ray CT imaging apparatus, wherein a turning range of the turning support unit is set so that the X-ray CT imaging area is located on the same side as the side on which the X-ray CT imaging area is offset with respect to the median. The X-ray CT imaging apparatus according to claim 1,
The turning drive mechanism drives the turning support unit, and sets the X-ray generator in a turning range of 180 ° or an angle obtained by adding the spread angle of the X-ray beam irradiation to 180 ° as the turning range of 270 ° or less. An X-ray CT imaging apparatus for rotating the X-ray detector and the X-ray detector around the head. The X-ray CT imaging apparatus according to claim 1 or 2,
An X-ray CT imaging apparatus, wherein the X-ray detection trajectory is formed by an arc trajectory having no concave portion toward the X-ray CT imaging area. The X-ray CT imaging apparatus according to any one of claims 1 to 3,
When the X-ray CT imaging region set and received by the imaging region position setting unit targets the anterior tooth region, the center of the arc of the X-ray detection trajectory is positioned on the plane including the median of the head. An X-ray CT imaging apparatus for setting a turning range of the turning support portion so as to be located on a front side. The X-ray CT imaging apparatus according to any one of claims 1 to 4, wherein
Assuming a maximum distance of the surface of the head with respect to the center of the X-ray CT imaging region, a turning diameter of the X-ray detector with respect to the center of the X-ray CT imaging region is set to be smaller than the maximum distance. X-ray CT imaging apparatus. The X-ray CT imaging apparatus according to any one of claims 1 to 5, wherein
The X-ray CT imaging apparatus, wherein the turning drive mechanism includes a turning axis moving mechanism that moves a turning axis on a mechanism that turns the turning support unit in a direction that intersects an axial direction of the turning axis on the mechanism. The X-ray CT imaging apparatus according to claim 6,
When performing X-ray CT imaging in the rotation range of 270 ° or less, the position of the rotation axis on the mechanism is moved according to the position of the X-ray CT imaging area set and received by the imaging area position setting unit. An X-ray CT imaging apparatus for performing the X-ray CT imaging by fixing a pivot axis on the mechanism to a center position of the X-ray CT imaging region. The X-ray CT imaging apparatus according to claim 6 or claim 7,
Synchronously with the turning mechanism turning the turning support section about the turning axis on the mechanism, the turning axis moving mechanism moves the turning axis on the mechanism, so that the turning support section has a combined motion. The X-ray CT imaging apparatus, wherein the X-ray generator and the X-ray detector can perform an operation of rotating around the center of the X-ray CT imaging area. An X-ray CT imaging apparatus according to claim 8,
A turning range setting unit configured to receive the setting of the turning range of 270 ° or less and the setting of the turning range of 360 ° or more;
Assuming a maximum distance of the surface of the head with respect to the center of the X-ray CT imaging region, when a turning range of 360 ° or more is set by the turning range setting unit, the center of the X-ray CT imaging region is When the smaller of the distance from the X-ray generator and the distance between the center of the X-ray CT imaging area and the X-ray detector is set as the separation distance, the distance is set by the imaging area position setting unit. Controlling the position of the turning axis on the mechanism with respect to the center of the X-ray CT imaging region so that the separation distance is greater than the maximum distance according to the position of the X-ray CT imaging region. CT imaging device. The X-ray CT imaging apparatus according to claim 9,
The turning range setting unit,
As the rotation range of 270 ° or less, a rotation range of 180 ° or an angle obtained by adding the spread angle of the irradiation of the X-ray beam to 180 ° is received,
An X-ray CT imaging apparatus that accepts a 360 ° turning range as the 360 ° or more turning range.

Images