JP6903608B2 - X-ray CT imaging device - Google Patents

Description

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

Patent Document 1 discloses an X-ray CT imaging device including a swivel mechanism and a moving mechanism. The swivel mechanism swivels a swivel means in which an X-ray generator and an X-ray detector are arranged so as to face each other with a subject in between, around a swivel axis. The moving mechanism moves the swivel axis and / or the subject in a plane perpendicular to the swivel axis. In this X-ray CT imaging device, the center of the area of interest of the subject is always centered on the imaging different from the rotation axis of the rotation mechanism by the combined motion of the rotation of the rotation means and the rotation of the rotation axis and / or the movement of the subject. The swivel means is swiveled as the center of rotation of. As a result, the magnification can be changed by making the distance between the X-ray generator and the center of rotation and / or the distance between the X-ray detector and the center of rotation relatively changeable.

Patent Document 2 describes the X-ray generator and the X-ray detector as an X-ray generator when X-ray CT imaging is performed in which the X-ray generator and the X-ray detector are rotated around the subject at a rotation angle in the range of 180 degrees or more and less than 360 degrees. The swivel drive unit is moved so that the X-ray generator moves in an orbit where the degree of scattering of X-rays between the X-ray detector and the area to be photographed is greater than the degree of scattering between the X-ray detector and the area to be photographed. The technology to control is disclosed.

Japanese Unexamined Patent Publication No. 2007-209168 Japanese Unexamined Patent Publication No. 2011-194032.

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 Document 2, it is difficult to obtain a clear X-ray CT image because 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. Is.

Therefore, in the present invention, the X-ray generator and the X-ray detector that rotate around the subject are suppressed from coming into contact with the subject, and the X-ray generator rotates as close to the subject as possible. The purpose is to enable a clear X-ray CT image to be obtained.

In order to solve the above problems, the X-ray CT imaging apparatus according to the first aspect includes an X-ray generator that generates X-rays, an X-ray detector that detects the X-rays, the X-ray generator, and the above. One of a swivel support portion in which an X-ray detector is supported so as to face each other across the head of the subject, a swivel drive mechanism including a swivel mechanism for swiveling the swivel support portion, and an dentition arch of the head. An imaging area position setting unit that accepts the setting of the position of the X-ray CT imaging area that targets the local region that is the region of the X-ray CT imaging, a swivel control unit that controls the swivel drive mechanism, and a swivel control unit of 270 ° or less. A swivel range setting unit that receives a swivel range setting and a swivel range setting of 360 ° or more is provided, and the swivel control unit drives and controls the swivel drive mechanism to drive and control the swivel drive mechanism to obtain the X-ray CT imaging region by the X-ray. While performing the X-ray CT imaging of the above, the X-ray generator and the X-ray detector are swiveled around the head in a swivel range of 270 ° or less, and the X-ray detector is the head. The X-ray CT imaging region passes through the side of the head that is unevenly distributed in the periphery of the portion, and the X-ray generator passes through the side of the circumference of the head that is opposite to the side of the uneven distribution. During the X-ray CT imaging, the X-ray detector forms an arc X-ray detection trajectory by the turning movement, and the X-ray CT imaging area set by the imaging area position setting unit is in the middle of the head. On the other hand, when the position is biased to either the left or right, the central portion of the arc of the X-ray detection orbit is biased to the same side as the side where the X-ray CT imaging region is biased with respect to the center. As such, the swivel range of the swivel support portion is set , and in the case of the swivel range of 270 ° or less, the X-ray detector is closer to the X-ray CT imaging region than the X-ray generator. Positioned on the side, the X-ray detector is swiveled with a larger diameter in the case of the swivel range of 360 ° or more than in the case of the swivel range of 270 ° or less .

The second aspect is the X-ray CT imaging device according to the first aspect, wherein the swivel drive mechanism drives the swivel support portion, and the swivel range of 270 ° or less is set to 180 ° or 180 °. The X-ray generator and the X-ray detector are swiveled around the head in a swirling range of an angle including the spread angle of the X-ray beam irradiation.

The third aspect is the X-ray CT imaging apparatus according to the first or second aspect, which is an arc trajectory having no concave portion toward the X-ray CT imaging region with the X-ray detection trajectory. It is what forms.

A fourth aspect is the X-ray CT imaging device according to any one of the first to third aspects, wherein the X-ray CT imaging area set and accepted by the imaging area position setting unit targets the anterior tooth region. In this case, the swivel range of the swivel support portion is set so that the central portion of the arc of the X-ray detection trajectory is located on the front side of the head on the surface including the median.

A fifth aspect is the X-ray CT imaging apparatus according to any one of the first to fourth aspects, assuming the maximum distance of the surface of the head to the center of the X-ray CT imaging region. The diameter of the swirl 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.

A sixth aspect is the X-ray CT imaging device according to any one of the first to fifth aspects, wherein the swivel drive mechanism has a swivel shaft on a mechanism for swiveling the swivel support portion. Includes a swivel shaft moving mechanism that moves in a direction intersecting the axial direction of the upper swivel shaft.

The seventh aspect is the X-ray CT imaging apparatus according to the sixth aspect, and when X-ray CT imaging is performed in the turning range of 270 ° or less, the setting is received by the imaging area position setting unit. The position of the swivel shaft on the mechanism is moved according to the position of the X-ray CT imaging region, and the swivel shaft on the mechanism is fixed at the center position of the X-ray CT imaging region to perform the X-ray CT imaging. It is a thing.

An eighth aspect is the X-ray CT imaging device according to the sixth or seventh aspect, in synchronization with the swivel mechanism swiveling the swivel support portion about a swivel axis on the mechanism. The swivel shaft moving mechanism moves the swivel shaft on the mechanism to cause the swivel support portion to perform a combined motion, whereby the X-ray generator and the X-ray detector are in the X-ray CT imaging region. It is possible to turn around the center.

A ninth aspect is an X-ray CT imaging apparatus according to the eighth aspect, when assuming the maximum distance of the surface of the head with respect to the center of the front Symbol X-ray CT imaging area, in the pivoting range setting unit When a turning range of 360 ° or more is set, the distance between the center of the X-ray CT imaging area and the X-ray generator, and the distance between the center of the X-ray CT imaging area and the X-ray detector. When the smaller distance is defined as the separation distance, the separation distance becomes larger than the maximum distance according to the position of the X-ray CT imaging area set by the imaging area position setting unit. It controls the position of the swivel axis on the mechanism with respect to the center of the X-ray CT imaging region.

The tenth aspect is the X-ray CT imaging apparatus according to the ninth aspect, and the turning range setting unit spreads the irradiation of the X-ray beam to 180 ° or 180 ° as the turning range of 270 ° or less. It accepts a turning range with an angle added to it, and accepts a turning range of 360 ° as the turning range of 360 ° or more.
In the eleventh aspect, the X-ray generator that generates X-rays, the X-ray detector that detects the X-rays, and the X-ray generator and the X-ray detector face each other with the head of the subject interposed therebetween. A swivel support portion supported so as to perform, a swivel drive mechanism including a swivel mechanism for swiveling the swivel support portion, and a local region which is a part of the dentition arch of the head are subject to X-ray CT imaging. The X-ray CT imaging region setting unit that receives the setting of the position of the X-ray CT imaging region and the swivel control unit that controls the swivel drive mechanism are provided, and the swivel control unit drives and controls the swivel drive mechanism. While performing X-ray CT imaging of the X-ray CT imaging region with X-rays, the X-ray generator and the X-ray detector are swiveled around the head in a swivel range of 270 ° or less, and The X-ray detector passes the side around the head where the X-ray CT imaging region is unevenly distributed in the head, and the X-ray generator is unevenly distributed around the head. During the X-ray CT imaging, the X-ray detector forms an arc X-ray detection trajectory by the swivel movement, and the X-ray CT set by the imaging region position setting unit. When the imaging area is located at a position biased to the left or right with respect to the center of the head, the central portion of the arc of the X-ray detection orbit is biased to the center of the X-ray CT imaging area. The X-ray detection is performed when the swivel range of the swivel support portion is set so as to be biased to the same side as the side where the X-ray detector is located and the maximum distance of the surface of the head to the center of the X-ray CT imaging region is assumed. The diameter of the swirl of the device with respect to the center of the X-ray CT imaging region is set to be smaller than the maximum distance.
In the twelfth aspect, the X-ray generator that generates X-rays, the X-ray detector that detects the X-rays, and the X-ray generator and the X-ray detector face each other with the head of the subject in between. The object of X-ray CT imaging is a swivel support portion supported so as to be, a swivel drive mechanism including a swivel mechanism for swiveling the swivel support portion, and a local region which is a part of the dentition arch of the head. The X-ray CT imaging region setting unit that receives the setting of the position of the X-ray CT imaging region and the swivel control unit that controls the swivel drive mechanism are provided, and the swivel control unit drives and controls the swivel drive mechanism. While performing X-ray CT imaging of the X-ray CT imaging region with X-rays, the X-ray generator and the X-ray detector are swiveled around the head in a swivel range of 270 ° or less, and The X-ray detector passes the side around the head where the X-ray CT imaging region is unevenly distributed in the head, and the X-ray generator is unevenly distributed around the head. During the X-ray CT imaging, the X-ray detector forms an arc X-ray detection trajectory by the swivel movement, and the X-ray CT set by the imaging region position setting unit. When the imaging area is located at a position biased to the left or right with respect to the center of the head, the central portion of the arc of the X-ray detection orbit is biased to the center of the X-ray CT imaging area. The swivel range of the swivel support portion is set so as to be biased to the same side as the swivel support portion, and the swivel drive mechanism uses a swivel shaft on the mechanism for swiveling the swivel support portion as a swivel shaft on the mechanism. The swivel shaft moving mechanism includes a swivel shaft moving mechanism that moves the swivel shaft in a direction intersecting the axial direction of the above, and the swivel shaft moving mechanism rotates the swivel support portion around the swivel shaft on the mechanism. By moving the swivel axis on the mechanism and causing the swivel support portion to perform a synthetic motion, the X-ray generator and the X-ray detector can swivel around the center of the X-ray CT imaging region. It is possible, further provided with a turning range setting unit that accepts the setting of the turning range of 270 ° or less and the setting of the turning range of 360 ° or more, and the maximum of the surface of the head with respect to the center of the X-ray CT imaging region. Assuming a distance, when a turning range of 360 ° or more is set by the turning range setting unit, the distance between the center of the X-ray CT imaging area and the X-ray generator, and the X-ray CT imaging area. When the smaller of the distance between the center of the X-ray detector and the X-ray detector is defined as the separation distance, the maximum distance is set according to the position of the X-ray CT imaging region set by the imaging region position setting unit. Before The position of the swivel axis on the mechanism with respect to the center of the X-ray CT imaging region is controlled so that the separation distance becomes large.
A thirteenth aspect is the X-ray CT imaging apparatus according to the twelfth aspect, wherein the turning range setting unit irradiates an X-ray beam at 180 ° or 180 ° as the turning range of 270 ° or less. It accepts a turning range with an angle added to the expansion angle, and accepts a turning range of 360 ° as the turning range of 360 ° or more.

According to the first to twelfth aspects, the X-ray generator and the X-ray detector are swiveled around the head in a swivel range of 270 ° or less, and the X-ray detector is around the head. Of these, the X-ray CT imaging area passes through the unevenly distributed side in the head, the X-ray generator passes through the opposite side of the unevenly distributed side around the head, and X-ray detection is performed during X-ray CT imaging. When the X-ray detection trajectory of the arc is formed by the swirling movement and the X-ray CT imaging area set by the imaging area position setting unit is located at a position biased to the left or right with respect to the center of the head. In order to set the swivel range of the swivel support portion so that the central portion of the arc of the X-ray detection orbit is biased to the same side as the side where the X-ray CT imaging region is biased with respect to the midline, X-rays are used. It is possible to prevent the generator and the X-ray detector from coming into contact with the head. 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, and as a result, the X-ray detector can be swiveled as close to the subject as possible, and the X-ray is as clear 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 that swirl 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 by an arc trajectory having no concave portion toward the X-ray CT imaging region, the X-ray detector is less likely to be shaken.

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 central portion of the arc of the X-ray detection trajectory is the above-mentioned on the surface including the midline. Since the swivel range of the swivel support is set so that it is located on the front side of the head, it is possible to prevent the X-ray generator and X-ray detector from coming into contact with the head even when X-ray CT imaging of the front teeth is performed. it can.

According to the fifth and eleventh aspects, when the maximum distance of the surface of the head with respect to the center of the X-ray CT imaging region is assumed, the diameter of the rotation of the X-ray detector with respect to the center of the X-ray CT imaging region is the maximum. Since it is set smaller than the distance, the X-ray detector can be swiveled as close to the subject as possible, and an X-ray CT image as clear as possible can be obtained.

According to the sixth and twelfth aspects, the swivel support portion is swiveled while the swivel shaft on the mechanism is maintained at a fixed position, or the swivel support portion is swiveled around the swivel shaft on the mechanism. In synchronization with the above, the swivel shaft moving mechanism moves the swivel shaft on the mechanism to cause the swivel support portion to perform a synthetic motion, whereby the X-ray generator and the X-ray detector are X-ray CT. By turning around the center of the imaging area, it is possible to adjust the turning trajectory of the X-ray generator and the X-ray detector.

According to the seventh aspect, when X-ray CT imaging is performed 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 accepted by the imaging area position setting unit. X-ray CT imaging is performed by moving the swivel axis on the mechanism at the center of the X-ray CT imaging area, so that the X-ray generator and X-ray detector can swivel in a stable trajectory. Therefore, it is possible to obtain an X-ray CT image as clear as possible.

According to the eighth and twelfth aspects, the swivel shaft moving mechanism moves the swivel shaft on the mechanism to support the swivel in synchronization with the swivel mechanism swiveling the swivel support portion around the swivel shaft on the mechanism. The X-ray generator and the X-ray detector rotate around the center of the X-ray CT imaging area by causing the unit to perform a synthetic motion. It is possible to adjust the diameter to be used.

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

According to the tenth and thirteenth aspects, when performing a full scan by 360 ° CT imaging and a half scan by 180 ° CT imaging, an X-ray generator and an X-ray detector that rotate around the subject are the subjects. It is possible to suppress contact with.

It is the schematic which shows the X-ray CT imaging apparatus which concerns on 1st Embodiment. It is a flowchart which shows the processing example by a turning control part. 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 the turning drive mechanism. It is a block diagram which shows the electrical structure of the X-ray CT imaging apparatus. It is a flowchart which shows the processing example by a shooting program. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the example of the reference table. It is explanatory drawing which shows the setting example of a turning range. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example which concerns on the modification. It is a figure which shows the turning operation example which concerns on other modification. It is a figure which shows the turning operation example which concerns on other modification. It is a block diagram which shows the electrical structure of the X-ray CT imaging apparatus which concerns on 3rd Embodiment. It is a flowchart which shows the processing example by a shooting program. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the example of the reference table. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example. It is a flowchart which shows the processing example by the photographing program which concerns on the modification. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the display example in the operation panel apparatus. It is a figure which shows the example of the reference table. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example. It is a figure which shows the turning operation example which concerns on other modification. It is a figure which shows the turning operation example which concerns on other modification. It is a figure which shows the movement trace example by the movement of an X-ray detector. It is a figure which shows another movement trace example by movement of an X-ray detector. It is a figure which shows the detector existence area and a safety area. It is a figure which shows the detector existence area and the safety area in the example shown in FIG. 33. It is a figure which shows the detector existence area and a safety area in another example.

{First embodiment}
Hereinafter, a medical X-ray CT imaging device based on the embodiment will be described. FIG. 1 is a schematic view showing an X-ray CT imaging device 10.

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

The swivel support portion 20 supports the X-ray generator 22 and the X-ray detector 24 so as to face each other with the head P of the subject interposed therebetween. 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 regulator. 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 swivel support portion 20 in a state where the head P can be arranged between them. 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-rays incident on the X-ray detector 24 are converted into electric signals according to the intensity of the X-rays for each unit pixel. An X-ray CT image or the like is generated based on each of these electric signals.

The swivel drive mechanism 30 includes a swivel mechanism 32.

The swivel mechanism 32 swivels the swivel support portion 20 around a swivel shaft X1 on the mechanism located between the X-ray generator 22 and the X-ray detector 24. For example, the swivel mechanism 32 includes an electric motor and, if necessary, an acceleration / deceleration mechanism such as a gear. The swivel mechanism 32 supports the shaft portion 33 protruding from the swivel support portion 20 so as to be rotationally driveable 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 swivel shaft X1 on the mechanism. Then, by driving the swivel mechanism 32, the swivel support portion 20 swivels around the swivel shaft X1 on the mechanism. The swivel mechanism 32 may have any configuration as long as the swivel support portion 20 is swiveled around the swivel shaft X1 on the mechanism.

Here, the swivel mechanism 32 moves the X-ray generator 22 and the X-ray detector 24 around the head P at a swivel angle of 270 ° or less when performing X-ray CT imaging under the control of the swivel control unit 60. It is possible to turn. For example, when performing X-ray CT imaging, there are cases where the X-ray generator 22 and the X-ray detector 24 are swiveled around the head P by 360 ° and cases where the X-ray generator 22 and the X-ray detector 24 are swiveled at 270 ° or less (for example, 180 °). There can be. The turning angle of the X-ray generator 22 and the X-ray detector 24 is determined to be 270 ° or less (for example, 180 °) in addition to the case where the angle is 270 ° or less (for example, 180 °). In some cases, the angle set and the turning angle of 360 ° can be selected by the user's setting. The swivel mechanism 32 may be able to swivel 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 the X-ray generator 22 and the X-ray detector 24 are swiveled around the head P by 270 ° or less (for example, 180 °), the X-ray detector 24 close to the head P is used as described later. By determining the turning range so as not to turn the side of the part P farthest from the photographing region R, the contact between the X-ray detector 24 and the head P can be avoided.

When driving the swivel support unit 20, the swivel drive mechanism 30 adds an X-ray beam irradiation spread angle (see angle β in FIG. 15 to be described later) to 180 ° or 180 ° as a swivel range of 270 or less. The X-ray generator 22 and the X-ray detector 24 may be swiveled around the head P within the swirling range of. As a result, it is possible to prevent the X-ray generator 22 and the X-ray detector 24, which rotate around the head P, from coming into contact with the head P when performing a half scan by CT imaging at around 180 °.

Further, in the swivel mechanism 32, under the control of the swivel control unit 60, the X-ray detector 24 passes around the head P on the side where the imaging region R is unevenly distributed in the head P, and the X-ray generator 22 passes. The X-ray generator 22 and the X-ray detector 24 are subjected to X-ray CT imaging by passing the imaging region R around the head P on the side opposite to the side unevenly distributed in the head P. Turn around the head P. At this time, the state in which the X-ray detector 24 is positioned closer to the X-ray generator 22 with respect to the photographing region R is maintained.

The state in which the X-ray detector 24 is positioned closer to the X-ray generator 22 with respect to the photographing area R means that the turning axis X1 is located at the center A of the photographing area R during their rotation. Assuming that they are kept in agreement, it means that the swivel axis X1 is closer to the X-ray detector 24 than the X-ray generator 22.

Here, the maximum distance LD of the surface of the head P with respect to the center of the photographing region R is assumed (see FIG. 1). This maximum distance LD is the maximum distance LD in the entire circumference of the head P regardless of the turning range of the X-ray detector 24. Also, consider the diameter q of the swivel 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 swiveled with the swivel axis X1 aligned with the center A of the imaging region R, the swivel diameter q is equal to the distance between the swivel shaft X1 and the X-ray detector 24. That is, in this case, the diameter q of the swivel is fixedly determined by the configuration of the swivel support portion 20 itself. The turning diameter q is smaller than the maximum distance LD. As a result, the X-ray detector 24 can be brought closer to the imaging region R than the X-ray generator 22, and the X-ray CT image can be made clear.

However, in this case, depending on the turning range of the X-ray detector 24 around the head P, the X-ray detector 24 may come into contact with the head P. Therefore, when making such a turn, 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 swivel axis X1 is swiveled around the center A of the imaging region R in synchronization with the swivel of the X-ray generator 22 and the X-ray detector 24. In this case, the distance of the X-ray detector 24 with respect to 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 diameter q of the swivel in this case depends on the configuration of the swivel support portion 20 itself (particularly the distance between the swivel shaft X1 and the X-ray detector 24) and the swivel mode of the X-ray detector 24 (particularly, the swivel shaft X1). Determined according to the turning diameter).

The X-ray CT imaging area R (hereinafter, may be simply referred to as an imaging area R) is an area subject to X-ray CT imaging. A region that is not the entire region of the subject but a partial region in the spread in the XY directions when viewed from the Z direction, such as a part near the front of the head P, is referred to as a local region. The imaging area position setting unit 40 is configured to be able to accept the setting of the position 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 position of the photographing area R can be set, for example, by designating the schematic dentition 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 a plan view image of the dental arch, or may be a front view or a side view image. The position may be specified through the arrow keys. In addition, the position of the imaging region R may be set by designating or selecting one or more tooth types. The tooth formula is a formula in which each tooth is distinguished by a number or the like. The dentition may be a Japanese dentition, an FDI (Two-digit system) dentition, or an American (Universal system) dentition. The above settings are made by the operator. The shooting area position setting unit 40 sets the position of the shooting area R with respect to the turning control unit 60 based on the position setting of the received shooting area R.

As an example of setting the position of the imaging region R with respect to the dental arch, it is assumed that there is a molar region on one side that is a part of the dental arch and an anterior tooth region that is a part of the dental arch. For example, when the molar tooth on one side of the dental arch is designated as the imaging area R, a part of the dental arch located at a position biased to the left or right of the head P is used as the CT imaging area R for X-ray CT. This is an example of shooting. FIG. 1 shows a case where the left side is the front side of the head P, the right side is the rear 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. There is. The photographing area position setting unit may be any interface as long as it can accept the setting of the position of the photographing area in the plane orthogonal to the turning axis X1 on the mechanism.

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

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

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

That is, when performing X-ray CT imaging, the position of the imaging area R is set through the imaging area position setting unit 40 in step S1. The content that can set the position of the imaging region R includes the position setting for a part of the dental arch located at a position biased to the right or left from the anterior-posterior axis of the head P. For example, the position can be set with respect to the right molar or the left molar, which is a part of the dental arch.

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

The swivel range is represented by, for example, from which position to which position the X-ray generator 22 and the X-ray detector 24 are swiveled around the head P. When the position is set to perform X-ray CT imaging with a part of the dental arch that is biased to the left or right of the head P as the imaging area R, the X-ray generator 22 is set according to the position. And the swivel range of the X-ray detector 24 (that is, the swivel support 20) is determined. Since the X-ray generator 22 and the X-ray detector 24 are located at positions facing each other with the swivel shaft X1 interposed therebetween, when the swivel range of the X-ray generator 22 is determined, the X-ray detector 24 The turning range is also determined, and conversely, 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 swivel control unit 60 drives and controls the swivel 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 are placed on the head P. Consider the case of turning around in a turning range of 270 ° or less. In this case, if the X-ray detector 24 is swiveled 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 passes around the head P on the side where the photographing region R is unevenly distributed in the head P. On the contrary, it is preferable that the X-ray generator 22 passes around the head P on the side opposite to the side where the photographing region R is unevenly distributed in the head P. As a result, the X-ray detector 24 may form an arc X-ray detection trajectory Or by turning.

For example, when the photographing area R is an anterior tooth, the photographing area R is unevenly distributed on the anterior side in the head P. Therefore, it is preferable that the X-ray detector 24 passes the front side of the head P and the X-ray generator 22 passes the rear side of the head P. Further, for example, when the imaging region R is the right molar (or the left molar), the imaging region R is unevenly distributed to the front right side (or the front left side) in the head P. Therefore, it is preferable that the X-ray detector 24 passes the front right side (or the front left side) of the head P, and the X-ray generator 22 passes the rear left side (rear right side) of the head P.

Further, it is assumed that the shooting area R set by the shooting area position setting unit 40 is located at a position biased to the left or right with respect to the median Mc of the head P. Here, the median Mc of the head P means a line or a plane including the left-right symmetry axis in the head P (the median Mc is shown in FIG. 1). When a part of the dental arch that is biased to the left or right of the head P is defined as the imaging region R, the portion around the head P that is farthest from the center of the imaging region R is located at that position. It will be different depending on.

When the X-ray detector 24 turns around the head P while maintaining the state of being located closer to the X-ray generator 22 with respect to the imaging region R, the X-ray detector 24 photographs around the head P. The X-ray detector 24 may come into contact with the head P when trying to turn the farthest point from the center of the region R. Therefore, the turning range of the turning support portion 20 is set so that the central portion OrM of the arc of the X-ray detection trajectory Or is biased toward the same side as the side where the photographing region R is biased with respect to the median Mc. .. Here, the central portion OrM of the arc of the X-ray detection orbit Or is the center of both ends of the X-ray detection orbit Or. The arc formed by the X-ray detection trajectory Or does not have to be an arc in which the same curvature portions are continuous.

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 portion 20 is set so that the central portion OrM of the arc of the X-ray detection orbit Or is located biased to the left side with respect to the median Mc.

As a result, the X-ray detector 24 can rotate around the head P while avoiding a portion far from the center of the imaging region R while approaching the imaging region R as much as possible. When the left molar is designated as the imaging region R, the portion around the head P that is farthest from the center of the imaging region R exists on the right side of the head P. Since the X-ray generator 22 is relatively far from the imaging region R, it is difficult for the X-ray generator 22 to come into contact with the head P even if it turns around a portion far from the center of the imaging region R around the head P (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 portion 20 is set so that the central portion OrM of the arc of the X-ray detection orbit Or is positioned biased to the right with respect to the median Mc.

As a result, similarly to the above, the X-ray detector 24 can rotate around the head P while avoiding a portion 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 photographing area R, it is difficult to come into contact with the head P even if the X-ray generator 22 turns around a portion far from the center of the photographing area R around the head P.

When a part of the dental arch is used as the imaging region R, the imaging region R set by the imaging region position setting unit 40 is located at a position biased to the left or right with respect to the median Mc of the head P. It is not necessary to make a strict judgment as to whether or not it is. For example, in the case of X-ray CT imaging of the left-sided portion or the right-sided portion of the front teeth, it may be considered that the part is not biased to the left or right with respect to the median Mc. For example, the case of photographing the molar teeth of the dental arch may be the case of performing X-ray CT imaging with a part of the dental arch located at a position biased to the left or right of the head P as the imaging area R. ..

When the photographing area R is not biased to the left or right of the head P, the X-ray detector 24 may rotate in the turning range of the first half of the head P.

The determination of the turning range is stored 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, etc.), and the imaging region is set. It is possible to configure the configuration in which the turning range associated with the R position is determined according to the size of the position. More specifically, as the turning range, a standard head P is assumed, and the direction from the center of the head P toward the center A of the imaging region R is set as the center of the turning range of the X-ray detector 24. Alternatively, it is conceivable to set the direction from the center A of the photographing region R toward the portion of the head P around the maximum distance LD as the center of the turning range of the X-ray generator 22.

Further, the angle of the center A of the shooting area R with respect to the center of the head P is calculated each time according to the position of the center A of the shooting area R to be set, and X-ray detection is performed with the calculated angle as a reference. The turning range of the device 24 (for example, a range in which the same angle (for example, 90 °) is swiveled in both directions with the angle of the center A of the photographing region R with respect to the center A as the center angle) may be determined. As the center position of the head P in this case, for example, one stored in advance assuming a standard head can be used.

In the next step S3, while the swivel control unit 60 drives and controls the swivel 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 are headed. The X-ray detector 24 swivels around P in a swivel range of 270 ° or less, and the X-ray detector 24 passes through the side of the head P where the photographing region R is unevenly distributed in the head P, and X-rays are emitted. The generator 22 passes around the head P so that the imaging region R passes on the opposite side of the head P from the unevenly distributed side, and the X-ray detector 24 forms an arc X-ray detection trajectory Or by swirling movement. To. At this time, when the shooting area R set by the shooting area position setting unit 40 is located at a position biased to the left or right with respect to the median Mc of the head P, it is based on the determined turning range as described above. Then, the X-ray generator 22 and the X-ray detector 24 turn. That is, the swivel support portion 20 swivels so that the central portion OrM of the X-ray detection trajectory Or is biased toward the same side as the side where the photographing region R is biased with respect to the median Mc. At this time, the X-rays emitted from the X-ray generator 22 pass through the head P and enter the X-ray detector 24, and data used for generating an X-ray CT image is obtained. Based on this data, an X-ray CT image is generated.

According to the X-ray CT imaging device 10 configured in this way, when the imaging region R is located at a position biased to the left or right with respect to the midline Mc of the head P, the central portion OrM of the X-ray detection trajectory Or is The X-ray generator 22 and the X-ray detector 24 determine the turning range of the turning support portion 20 so that the imaging region R is biased to the same side as the biased side with respect to the midline 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 an X-ray CT image as clear as possible 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, it is possible to obtain an X-ray CT image as clear as possible.

{Second embodiment}
The X-ray CT imaging apparatus according to the second embodiment will be described.

FIG. 3 is a schematic view showing the overall configuration of the X-ray CT imaging device 110. Here, an example will be described in which the X-ray CT imaging device 110 is configured to be capable of performing not only CT imaging but also panoramic imaging, cephalo imaging, and the like.

<Overall configuration>
The X-ray CT imaging device 110 includes an imaging main body 120 and an X-ray image processing device 180. The imaging main body 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 the projection data collected by the photographing main body 120 to generate various images.

The photographing main body 120 includes a swivel support portion 124 and a swivel drive mechanism 130. The swivel 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, which is a subject, interposed therebetween. The swivel support unit 124 includes a swivel shaft X1 on a mechanism that serves as an axis for the swivel support unit 124 itself to swivel at a position between the X-ray generator 126 and the X-ray detector 128. The swivel drive mechanism 130 includes a swivel mechanism 132 and a swivel shaft moving mechanism 134. The swivel mechanism 132 is a mechanism for swiveling the swivel support portion 124 around a swivel shaft X1 on the mechanism between the X-ray generator 126 and the X-ray detector 128. The mechanical relationship between the swivel mechanism 132, the swivel support portion 124, the X-ray generator 126, and the X-ray detector 128 is as follows. That is, the swivel support portion 124 swivels around the swivel shaft X1 on the mechanism, so that the X-ray generator 126 and the X-ray detector 128 swivel around the swivel shaft X1 on the mechanism. The swivel shaft moving mechanism 134 is a mechanism for moving the swivel shaft X1 on the mechanism in a direction intersecting the swivel shaft X1. The swivel shaft moving mechanism 134 may be omitted.

Preferably, the swivel shaft X1 on the mechanism is provided at a position closer to the X-ray detector 128 than the central position of the X-ray generator 126 and the X-ray detector 128. As an example of the effect of providing the swivel axis X1 on the mechanism at a position closer to the X-ray detector 128 than the central position of the X-ray generator 126 and the X-ray detector 128, the mechanism during X-ray imaging. It is possible to meet the demand for the X-ray detector 128 to be as close to the imaging area R as possible in order to reduce the magnification as much as possible and make the projected image clear while keeping the movement amount of the upper swivel axis X1 as compact as possible. Can be mentioned.

More specifically, the support column 121 is supported on the base 120B in a vertical position. An elevating portion 122 is provided on the support column 121 so as to be able to elevate. The elevating unit 122 is elevated and driven by the elevating drive mechanism. As the elevating drive mechanism, a ball screw mechanism, a moving mechanism including a motor or the like, or a linear actuator such as a linear motor is used, and is incorporated in the support column 121 to elevate and drive the elevating portion 122. A horizontal arm 123 is supported by the elevating portion 122 so as to extend in the horizontal direction. A swivel drive mechanism 130 is incorporated in the tip of the horizontal arm 123. The head fixing device arm 141, which will be described later, extends from the support 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 portion of the elevating portion 122 moves up and down behind the support column 121. As described above, assuming that the side where the base end portion of the elevating portion 122 elevates and descends is the back surface and the back surface is the front surface, the horizontal arm 123 extends from the elevating portion 122 to the right of the support column 121 in front view. There is. The head P is held by the head fixing device 142 in a direction in which the right side shown in the figure is the rear side and the left side is the front side.

Here, the direction is specified for convenience of explanation.

The XYZ Cartesian coordinate system is a Cartesian coordinate system defined in the three-dimensional space in which the photographing main body 120 is installed. The direction parallel to the axial direction of the swivel shaft X1 on the mechanism is the Z-axis direction. In the present embodiment, the direction parallel to the axial direction of the swivel shaft X1 on the mechanism and the elevating direction of the elevating portion 122 are made to coincide with each other 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-back direction of the head P fixed to the head fixing device 142 is the Y-axis direction, and the left-right direction of the head is the X-axis direction. In the present application, the Z-axis direction may be referred to as the Z direction, the Y-axis direction may be referred to as the Y direction, and the X-axis direction may be referred to as the X direction.

The side from the head P toward the base 120B, that is, the lower side is the −Z side, and conversely, the side away from the head P toward 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 illustrates each axial direction and each + and-.

The xyz Cartesian coordinate system is a Cartesian coordinate system defined in a swivel support unit 124 that constitutes an imaging system that generates and detects X-rays that rotates around the axis of the swivel axis X1 on the mechanism. Here, the axial direction of the swivel axis X1 on the mechanism is the z-axis direction, and the z-axis direction coincides with the Z-axis direction in the XYZ Cartesian coordinate system. Further, 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 swivel support portion 124 rotates with the swivel axis X1 on the mechanism as the rotation axis, the xyz Cartesian coordinate system rotates about the Z axis (= z axis) with respect to the XYZ Cartesian coordinate system. In the present application, the z-axis direction may be referred to as the z-direction, the y-axis direction may be referred to as the y-direction, and the x-axis direction may be referred to as 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 is the + x side and the left side is the −x side from the −y side to the + y side. Further, in the z-axis direction, the upper side in the vertical direction is the + z side, and the lower side is the −z side.

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

The swivel shaft moving mechanism 134 is a mechanism for moving the swivel shaft X1 on the mechanism in a direction intersecting the swivel shaft X1 on the mechanism, in this case, in a direction orthogonal to the swivel shaft X1 on the mechanism. Here, the swivel shaft moving mechanism 134 is configured by an XY table mechanism, and the swivel mechanism 132 to which the swivel shaft X1 on the mechanism is connected is moved in a direction intersecting the swivel shaft X1 on the mechanism. The swivel shaft X1 of the above is moved in a direction intersecting the swivel shaft X1 on the mechanism. More specifically, the swivel 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, and a movable table. It is equipped with 139.

The X-direction movable support portion 135 includes a pair of linear guides 135a supported in the fixed table 134B in a parallel state at intervals and extending in the X direction. Further, 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 are in a posture intersecting the pair of linear guides 135a (here, a posture orthogonal to each other) and in a parallel state with an interval, and are extending in the extending direction on the pair of linear guides 135a. It is movably supported along the X direction. The movable table 139 is movably supported on a pair of linear guides 137a along the Y direction, which is the extending direction thereof. Then, the movable table 139 can be moved in the X direction by the Y-direction movable support portion 137 moving on the X-direction movable support portion 135 along the X direction. Further, the movable table 139 can be moved in the Y direction by moving the movable table 139 on the movable support portion 137 in the Y direction along the Y direction. As a result, the movable table 139 can freely move in a plane orthogonal to the swivel axis X1 on the mechanism.

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

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

The swivel mechanism 132 includes a motor 132a and is supported by the movable table 139 in a hanging shape. The shaft portion 124c protruding upward from the intermediate portion in the extending direction of the swivel support portion 124 is supported by the swivel mechanism 132 in a hanging state. The rotational motion of the motor 132a is transmitted to the shaft portion 124c, and the swivel support portion 124 is swiveled around the shaft portion 124c by driving the motor 132a. The central axis of the shaft portion 124c is the swivel shaft X1 on the mechanism. The swivel shaft X1 is located between the X-ray generator 126 supported by the swivel support portion 124 and the X-ray detector 128. The rotational movement of the motor 132a is transmitted to the shaft portion 124c via a transmission mechanism such as a gear or a pulley, if necessary. The shaft portion 124c is arranged along the vertical direction along the direction of gravity. Therefore, the swivel shaft 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 swivel mechanism 132 supported by the movable table 139 can be moved along a plane orthogonal to the swivel axis X1 on the mechanism. The swivel axis X1 on the mechanism can be moved in a desired trajectory within the range of mechanical constraints, and in addition to linear movement in the X direction and Y direction, in particular, in the X direction by the X direction drive unit 136. By combining the driving in the Y direction and the driving in the Y direction by the Y direction driving unit 138, it is possible to move in a straight line or a curve in a direction oblique to both the X direction and the Y direction. The swivel mechanism 132 may be rotationally moved so as 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. Further, it is not essential that the swivel shaft moving mechanism 134 has the above configuration. Further, the swivel shaft moving mechanism may be a mechanism that swivels the arm supporting the swivel mechanism and thus swivels and moves the swivel mechanism in a direction intersecting the swivel shaft X1 on the mechanism.

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

As shown in FIG. 3, the swivel support portion 124 is a portion in which the X-ray generator 126 and the X-ray detector 128 are supported so as to face each other with the head P in between. Here, the swivel support portion 124 has a shape in which hanging support portions 124b are provided at both ends of the elongated arm main body portion 124a, that is, a U-shape that opens downward. The shaft portion 124c projecting upward is projected from the intermediate portion of the arm main body portion 124a in the extending direction, and the shaft portion 124c is supported by the swivel 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 be capable of emitting X-rays emitted from the X-ray tube toward the X-ray detector 128. The hanging support portion 124b on the side where the X-ray generator 126 is provided is also an X-ray generator 126a including the X-ray generator 126.

Here, on the side where the X-ray detector 128 is irradiated with X-rays, an X-ray regulation unit 129 that regulates the X-rays generated from the X-ray generator 126 to the X-ray cone beam is provided. The X-ray regulation unit 129 is a member in which an X-ray regulation hole is formed, and allows a part of X-rays generated from the X-ray generator 126 to pass depending on the shape and size of the X-ray regulation hole. Shield the outside of the passage 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 regulation unit 129 is provided with a plurality of types of X-ray regulation holes to switch the X-ray regulation holes for restricting X-rays, or to move a member forming the X-ray regulation holes to move the X-ray regulation holes. By adjusting the opening width of the X-ray generator 126 or the like, the amount of X-rays generated from the X-ray generator 126 that is shielded, that is, the regulated amount is adjusted.

The X-ray regulation unit 129 is composed of, 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 centered on the X-ray irradiation port. It is provided on the side and the −x side, respectively. 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 control unit drive control unit (not shown). The space surrounded by these X-ray shielding members is an area through which X-rays can pass, and is an X-ray regulation hole. By the displacement drive control of the four X-ray shielding members, an X-ray regulating hole having a desired shape is formed. The region through which the X-ray can pass, that is, the X-ray regulation hole is, in other words, an X-ray passage allowance portion. The regulation width means the width of the regulated space, and is the width of the X-ray passage allowable portion, that is, the width of the X-ray regulation hole. Therefore, a relationship is established in which the regulation width is reduced in order to increase the regulation amount and the regulation width is increased in order to reduce the regulation amount.

An X-ray detector 128 is provided on the other hanging support portion 124b, whereby the X-ray detector 128 is arranged so as to face the X-ray generator 126 with the head P interposed therebetween. The X-ray detector 128 detects the X-rays 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) irradiated from the X-ray generator 126 and passed through the head P. It is configured. With this X-ray detector 128, projection data obtained by X-ray photography can be obtained. The hanging support portion 124b on the side where the X-ray detector 128 is provided is also an X-ray detector 128a including the X-ray detector 128.

Since the X-ray detector 128 is often actually housed in the exterior portion, when the X-ray detector 128 is housed in the exterior portion of the X-ray detector 128a, the presence or absence of contact with the head P is present. With respect to the above, it is advisable to read the X-ray detector 128 as the X-ray detector 128a and consider the presence or absence of the contact. The same applies to the X-ray generator 126, and when the X-ray generator 126 is housed in the exterior of the X-ray generator 126a, the X-ray generator 126 is X-rayed with respect to the presence or absence of contact with the head P. It may be read as the generating portion 126a to determine the presence or absence of the contact.

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

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

Then, the swivel support portion 124 can be raised and lowered by the elevating portion 122 according to the height of the head P. Further, the swivel drive mechanism 130 can swivel the swivel support portion 124 so that the X-ray generator 126 and the X-ray detector 128 swivel around the head P.

Further, a head fixing device arm 141 extending in the horizontal direction is provided in a portion of the support 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 support column 121 side as the base end portion. The head fixing device arm 141 extends toward the lower side of the horizontal arm 123, and the head fixing device 142 is provided at the tip 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 mounting and supporting the jaw of the head P as a subject, and a holding portion 142b for sandwiching and holding the head P as a subject from both outer sides thereof. Then, the jaw 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 between the X-ray generator 126 and the X-ray detector 128. It is held in place. The head fixing device 142 may be configured at least on one side of the chin rest 142a and the holding portion 142b. Further, a cephalo imaging head fixing device hanging arm 143 is provided so as to extend in the horizontal direction on the side opposite to the side on which the horizontal arm 123 extends from the support column 121, and the cephalo imaging head fixing device hanging arm 143 is provided. The head fixing device 144 for cephalo photography is supported in a suspended state. An X-ray detector 128b for cephalo imaging is incorporated in the head fixing device 144 for cephalo imaging.

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. In FIG. 3, the operation panel device 158 of the main body control unit 150 is enlarged and drawn in the outlet.

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

With this configuration, the head fixing device 142 and the head fixing device 142 are raised by simultaneously raising the elevating portion 122 with respect to the support column 121 and lowering the head fixing device arm 141 with respect to the elevating portion 122 with the same displacement amount. The horizontal arm 123 and the swivel support portion 124 can be raised with respect to the head P while maintaining the height of the head P fixed to the head P at a constant level. The head P fixed to the head fixing device 142 and the head fixing device 142 by simultaneously lowering the elevating portion 122 with respect to the support column 121 and raising the head fixing device arm 141 with respect to the elevating portion 122 with the same displacement amount. The horizontal arm 123 and the swivel support portion 124 can be lowered with respect to the head P while maintaining a constant height. Further, the head fixing device arm 141, the head fixing device 142, the horizontal arm 123, and the swivel support portion 124 can be raised or lowered at the same time. Further, while the heights of the horizontal arm 123 and the swivel support portion 124 are maintained constant, the heights of the head fixing device arm 141 and the head fixing device 142 can be adjusted by raising or lowering them. Further, the head fixing device arm 141 and the head fixing device 142 may be driven up and down by an independent elevating mechanism unrelated to the elevating and lowering of the elevating unit 122.

When performing X-ray imaging, the head P, which is the subject, is fixed by the head fixing device 142, and the swivel support portion 124 is stopped or rotated according to the desired imaging mode. Take a picture. As a result, it is possible to obtain X-ray projected image data necessary for generating an X-ray CT image (also simply referred to as an X-ray CT image or a CT image), a panoramic image (also simply referred to as a panoramic image), or the like. For example, by performing X-ray imaging in a state where the swivel support portion 124 is swiveled, it is possible to obtain X-ray CT imaging projected image data necessary for generating an X-ray CT imaging image. 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 photography in a state where the swivel support portion 124 is rotated by a certain range, panoramic image projected image data can be obtained, and panoramic image can be obtained by performing image processing for reconstruction. The panoramic projected image data is the projected image data for each direction obtained by irradiating from multiple directions while changing the irradiation position every moment with a gap X-ray beam extending the jaw region including the dental arch in the z direction. There are, and each of them can be collected in the form of frame image data. The X-ray CT imaging device 110 may also perform X-ray imaging for obtaining a cephalo imaging image and a pseudo-oral imaging image. For example, the head P is fixed to the cephalo imaging head fixing device 144 supported by the cephalo imaging head fixing device hanging arm 143 extending in the horizontal direction from the support column 121 with the swivel support portion 124 stopped. By irradiating X-rays from the X-ray detector 128 and performing X-ray photography, a cephalo-photographed image can be obtained. In addition, the shooting function of the panoramic shot image, the shooting function of the cephalo shot image, and the like may be omitted.

The main body control unit 150 is configured to be able to receive each instruction to the photographing main body 120, and is configured to be able to control each operation of the photographing main body 120. The main body control unit 150 is fixed to the head fixing device arm 141 extending in the horizontal direction from the support column 121. The main body control unit 150 is provided with an operation panel device 158 for displaying various information from the main body control unit 150 and receiving various commands to the main body 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 arranged on the display screen of the display device. By detecting the user's touch operation on the display screen with the touch detection unit, the operation on the X-ray CT imaging device 110 can be accepted. 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.

Each of the above-mentioned parts of the photographing main body part 120 is housed in the X-ray-proof chamber 146. On the outside of the wall of the X-ray-proof chamber 146, a push button switch called a deadman switch that gives an X-ray irradiation instruction to the main body control unit 150 is provided.

The X-ray image processing device 180 includes an information processing main unit 182 configured by, for example, a computer or the like, and is connected to the photographing main unit 120 by a communication cable so as to be able to transmit and receive various data. However, data may be transmitted / received by wireless communication between the photographing main body 120 and the X-ray image processing apparatus 180. The information processing main unit 182 can execute various image processing and the like based on the data transmitted from the photographing main unit 120.

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

A 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, a 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 the block diagram of the X-ray CT imaging device>
FIG. 5 is a block diagram showing an electrical configuration of the X-ray CT imaging device 110.

The main body control unit 150 of the shooting main body 120 controls the X-ray shooting operation of the shooting main body 120, and has a CPU (Central Processing Unit) 151 as at least one processor, a RAM (Random Access Memory) 152, and a memory. Units 153, input / output units 154a, 154b, operation input units 155, image output units 156, and the like are configured by computers interconnected via a bus line 157. The storage unit 153 is composed of a flash memory or a non-volatile storage device such as a hard disk device. The storage unit 153 receives various instructions regarding X-ray imaging, and controls the swivel drive mechanism 130, the X-ray generator 126, the X-ray regulation 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 photographing area R in the head P is set in the storage unit 153, it is referred to when determining the turning range of the X-ray detector 128 according to the set position of the photographing area R. Reference table 153b is stored. The reference table 153b is a table in which the position of the photographing region R is associated with the turning range of the X-ray detector 128 and the like.

The reference table 153b is one of the information constituting the drive control information of the imaging system including the swivel support portion 124, the X-ray generator 126, and the X-ray detector 128 as elements. The reference table includes, for example, coordinate information of the swivel shaft X1 on the mechanism and information on the swivel amount of swiveling the swivel support portion 124 around the axis of the swivel shaft X1 on the mechanism. The coordinate information of the swivel shaft X1 on the mechanism may be the information of the position where the swivel shaft X1 on the mechanism is retained, or the trajectory information of the trajectory for moving the swivel shaft X1 on the mechanism.

In the reference table 153b, the position of the imaging region R in the head P, the shape and size of the standard (eg, standard adult) head P, the X-ray generators 126 and X with respect to the swivel axis X1 on the mechanism. Considering each distance of the line detector 128, the turning range of the X-ray detector 128 so that they do not come into contact with the head P when the X-ray generator 126 and the X-ray detector 128 are turned is theoretical. , Has been determined experimentally. An example of a turning range or the like according to the position of the photographing area 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 swivel mechanism 132 that swivels the swivel support portion 124 of the main body 120, a motor of a swivel shaft moving mechanism 134 that moves the swivel support unit 124, an X-ray generator 126, and an X-ray detector. It is connected to 128, 128b, the X-ray regulation unit 129, and the like, and the input / output unit 154b is communicably connected to the X-ray image processing device 180. Further, 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 according to the procedure described in the photographing program 153a and the instruction received through the touch detection unit 158b, thereby performing a part of the dental arch of the head P of the subject. The function as a swivel control unit 151a that controls the swivel mechanism 132 and the swivel axis moving mechanism 134 when performing X-ray imaging such as X-ray CT imaging and the imaging area position setting unit 151a that accepts the setting of the position of the imaging region R with respect to Execute. Then, the CPU 151 controls the swivel mechanism 132 and the swivel shaft movement mechanism 134 to swivel the X-ray generator 126 and the X-ray detector 128 around the head P, and pass through the head P to obtain X-rays. The detection result of the X-ray 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, a DVD-ROM, or an external flash memory. , It may be provided to an existing X-ray CT imaging device or an information processing main unit that controls the X-ray CT imaging device by downloading from an external server via a network.

The X-ray image processing device 180 generates X-ray image data 185b based on the photographing data from the photographing main body 120, and the information processing main body 182 stores the CPU 183, the RAM 184, and the storage as at least one processor. 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 composed of a flash memory or a non-volatile storage device such as a hard disk device, and the information processing main unit 182 stores X-ray image data 185b based on the shooting data from the shooting main body 120. It stores the image processing program 185a to be generated, the X-ray image data 185b, and the like. The storage unit 185 may store management data in which the X-ray image data 185b is associated with the specific information (patient specific information) of the head P and the like. Further, the X-ray image processing device 180 receives data and the like related to the shooting conditions from the main body control unit 150, and the generated X-ray image data 185b is associated with the data and the like related to the shooting conditions and stored in the storage unit 185. May be 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 the X-ray imaging data obtained by the imaging main unit 120 is input 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 shooting data from the shooting main body 120 as the projected image data 185c before reconstruction. The projected image data 185c may be completely raw raw data or preprocessed data processed to some extent for reconstruction. The projected image data 185c is, for example, the frame image data described above. The management data and / or the data related to the imaging conditions associated with the above-mentioned specific information (patient specific information) of the head P and the like are stored in the storage unit 185 in association with the image data 185b or the projected image data 185c. You may do so.

In the information processing main unit 182, the CPU 183 performs arithmetic processing according to the image processing program 185a to generate desired X-ray image data based on the X-ray imaging data obtained by the imaging main unit 120. Execute the process as. That is, data such as a CT image, a panoramic image, and a cephalo image is generated according to an instruction received through the main body control unit 150. The storage unit 185 stores the generated X-ray image data 185b.

It should be noted that some or all the functions realized in each of the above parts may be realized by hardware by a dedicated logic circuit or the like. Further, some or all the functions realized in each of the above parts may be integratedly processed by one processor, or may be appropriately distributed and processed by a plurality of processors.

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

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

Here, an example of accepting an operation for setting the position of the shooting area R will be described. FIG. 7 is a diagram showing a display example in the operation panel device 158. On the display unit 158a of the operation panel device 158, as images for selecting the shooting mode, a panoramic selection image 191a for selecting the panoramic shooting mode (see the characters “Pan”) and a cephalo selection image 191b for selecting the cephalo shooting mode are displayed. (Refer to the character "Cef"), the CT selection image 191c for selecting the CT imaging mode (see the character "CT") is displayed. Although "Pan", "Ceph", and "CT" are characters, they are displayed in a form that can be visually recognized as characters, and in that sense, they are character-shaped images. It may be an image that symbolically represents each shooting without taking the form of characters, or both may be used together. In the illustrated state, the CT imaging mode is selected by using the CT selected image 191c. On the display unit 158a, a shooting area setting image 194 is displayed as an image for setting shooting conditions. Here, the image for setting the shooting area 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. This illustration image 195 is an image for showing the photographing area R, and here, the 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 with respect to 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 photography, cephalo photography, or X-ray CT imaging.

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

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

Further, the photographing area selection images 194c, 194d, and 194e are images for selecting the photographing area R having a diameter of 80 mm. Further, the photographing area selection images 194c, 194d, and 194e indicate that the heights of the photographing area R are 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 as an region. Therefore, it can be said that the imaging area selection images 194b, 194c, and 194d are images for accepting X-ray CT imaging of 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.

Assuming that the shooting area selection image 194b is selected now, it is shown that the shooting area having a diameter of 40 mm and a height of 40 mm is selected in FIG. 7, as shown in the center of the upper and lower sides on the right side. Become.

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

The shooting area image 195a is designated by a pointer or the like, the designated area and the peripheral area of the shooting area image 195a are enlarged and displayed, and then the shooting area image 195a is moved to a desired position and the area can be specified by dragging and dropping. Alternatively, the shooting area image 195a may be designated with a pointer or the like, the designated area and the peripheral area of the shooting area image 195a may be enlarged and displayed, and then the shooting area image 195a may be moved separately with the move key. .. On the screen, the illustration image 195 may be similarly moved with respect to the stationary shooting area image 195a so that the area can be specified.

When the designation of the photographing area R is accepted, the swivel support portion 124 is moved to a position where it can swivel with the center A of the photographing region R as the swivel center by the drive of the swivel shaft moving mechanism 134, and the swivel support portion 124 is swiveled by the swivel mechanism 132. The angle around the axis X1 is determined toward the start of shooting.

When the imaging area R for a part of the dental arch is selected and the imaging area R is specified for the right molar region or the left molar region, it is biased to either the left or right side of the head P. This is a case where X-ray CT imaging is performed with a part of the dental arch at the position as the imaging area R.

In the above example, the example of specifying the shooting mode, the shooting area R, etc. using the touch panel has been described, but various settings are accepted via a switch (push button) or the like that physically accepts the operation. May be good.

As described above, in step S11, the photographing area position setting unit 151a receives the setting operation of the position of the photographing area R with respect to a part of the dental arch of the head P through the operation panel device 158. Here, the shooting area position setting unit 151a receives the selection operation of either the shooting area selection image 194a or 194b and the reception of the position setting using the shooting area image 195a with respect to the illustration image 195 through the operation panel device 158. Accepts the position setting of the shooting area R. In particular, it accepts the setting of the position of the imaging region R for which the local region, which is a part of the dental arch Ar of the head P, is the target of the X-ray CT imaging.

In the next step S12, the turning range is determined according to the position of the set shooting area. The swivel range indicates the range in which the X-ray detector 128 is swiveled around the center A of the imaging region R. Such a turning range is represented by, for example, from which angle to which angle the X-ray generator 126 and one or both of the X-ray detector 128 are swiveled around the center A of the photographing region R. In the present embodiment, as described in the first embodiment, the X-ray generator while the swivel control unit 151b drives and controls the swivel drive mechanism 130 to perform X-ray CT imaging of the imaging region R by X-rays. The 126 and the X-ray detector 128 are swiveled around the head P in a swivel range of 270 ° or less (180 ° in this case), and the X-ray detector 128 takes a picture around the head P. The region R passes through the unevenly distributed side in the head P, and the X-ray generator 126 passes around the head P on the opposite side of the side where the imaging region is unevenly distributed, and X-rays are emitted during X-ray CT imaging. X-ray detection trajectory Or of arc by swivel movement of detector 128 (In the following explanation, (left), (right), (mid) are added to Or, and each for left molar, right molar, and anterior tooth. An example of forming an orbit) will be described.

As described in the first embodiment, when the swivel drive mechanism 130 drives the swivel support portion 124, the X-ray beam irradiation spread angle at 180 ° or 180 ° as a swivel range of 270 or less (FIG. The X-ray generator 126 and the X-ray detector 128 may be swiveled around the head P in a swivel range of an angle (see angle β of 15).

A mode in which the X-ray CT imaging device 110 swivels 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 are swiveled in a range of 360 ° or more. A configuration that can be switched between and is also conceivable, and this case will be described in a later embodiment.

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

The turning ranges α (left1) to α (left2) associated with the left molars are set so that the central portion of the X-ray detection trajectory Or (left) is biased 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 so that the central portion of the X-ray detection trajectory Or (right) is biased to the right with respect to the median Mc. There is.

Further, in the turning ranges α (mid1) to α (mid2) associated with the front teeth, the central portion of the arc of the X-ray detection trajectory Or (mid) is located on the front side of the head P on the surface including the median Mc. It is set to do.

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

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

In the next step S13, CT imaging is performed by performing turning control based on the determined turning range. While the swivel control unit 151b drives and controls the swivel 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 placed around the head P at 270 °. The X-ray detector 128 is swiveled in the following swivel range, and the X-ray detector 128 passes the side around the head P where the imaging region R is unevenly distributed in the head P, and the X-ray generator 126 is head. It passes through the side opposite to the unevenly distributed side of the periphery of P, and during X-ray CT imaging, the X-ray detector 128 forms an arc X-ray detection trajectory Or by swirling movement.

At this time, as described above, when the imaging region R is located at a position biased to the left or right with respect to the median Mc of the head P, the central portion OrM of the arc of the X-ray detection trajectory Or is the median Mc On the other hand, the turning range of the turning support portion 124 is set so that the photographing region R is biased to the same side as the biased side. The X-ray detection trajectory Or is an arc trajectory that does not partially approach the imaging region R so as to protrude, that is, an arc trajectory that does not have a concave portion toward the imaging region R. Is. In other words, the X-ray detection orbit Or is an arc orbit in which curves that are convex on the outer peripheral side are continuous.

Preferably, assuming the maximum distance LD of the surface of the head P with respect to the center A of the imaging region R, the diameter q of the swivel 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. Will be done. That is, while maintaining the state where the X-ray detector 128 is located closer to the X-ray generator 126 with respect to the imaging region R, the X-ray generator 126 and the X-ray detector 128 are placed around the head P. Turn. In this case, the diameter q of the swivel 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, the X-ray detector 128 is on the head P when the head P is irradiated with X-rays generated from the X-ray generator 126 to perform X-ray CT imaging. Try to turn in a range that is biased to the left. When the imaging region R is the right molar, the X-ray detector 128 is on the right side of the head P when the head P is irradiated with X-rays generated from the X-ray generator 126 to perform X-ray CT imaging. Try to turn in a biased range. Further, when the imaging region R is the front tooth, the X-ray detector 128 is in the left-right direction of the head P when the head P is irradiated with X-rays generated from the X-ray generator 126 to perform X-ray CT imaging. Make sure to turn an even angle range from the center to the left and right.

These turning operations will be described more specifically with reference to FIGS. 11 and 12.

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 midline Mc of the head P. That is, it is a case where the anterior tooth region which is a part of the dental arch Ar is set as the imaging region R. In this case, the portion of the surface of the head P that is farthest from the imaging region R is the rear portion 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 swiveled by 180 °, the α (mid1) is 90 °, the α (mid2) is 270 °, and the X-ray detector 128 is started from 90 °. Turn 180 ° within 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 in front of the head P on the surface including the median Mc. The turning angle may be 180 ° plus the fan angle of the X-ray beam. 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 point is the same when the turning range is biased 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 swiveled within such a range, they can be swiveled 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 biased to the left or right from the front-back axis of the head P as the imaging region R. In FIG. 11, in the head P indicated by the alternate long and short dash line, the imaging region R is pointed out at a position biased to the left in the dental arch Ar.

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

Therefore, as shown in FIG. 12, the X-ray detector 128 swivels the X-ray detection trajectory Or in a range biased to the same side as the side where a part of the dental arch Ar is biased (here, the left side). To do so. Here, when viewed in a plan view, the X-ray detector 128 is centered on a range biased to the left from the center of the front part of the head P, and X-rays in a range of 270 ° or less (here, turning 180 °). Turn on the detection orbit Or. For example, with α (left1) set to 40 ° and α (left2) set to 220 °, the X-ray detector 128 is swiveled 180 ° in the range of 40 ° to 220 °. In this case, the central portion OrM of the X-ray detection orbit Or is biased to the left with respect to the median Mc. The X-ray detector 128 takes a trajectory from the left rear position of the head, passing through the front side of the head to the right front position of the head. The range occupied by the orbit of the X-ray detector 128 for the head P shown by the solid line in FIG. 11 is even on the left and right, whereas the orbit of the X-ray detector 128 is occupied by the head P shown by the solid line in FIG. The range occupied by is less than half on the right and more than half on the left.

The X-ray generator 126 takes an orbit from the right anterior position of the head, passing behind the head to the left posterior position of the head. That is, the X-ray generator swivels in a range biased to the opposite side of the X-ray detector 128. Of course, the starting position and the ending position may be exchanged to reverse the rotation.

As a result, the X-ray detector 128 does not rotate on the right side of the surface of the head P, which is far from the imaging region R, and the outside of the diagonally right rear part, so that the X-ray detector 128 does not easily come into contact with the head P. Become. The X-ray generator 126 swivels on the right side of the surface of the head P, which is far from the photographing area R, and the outside of the diagonally right rear part, but is farther from the photographing area R than the X-ray detector 128. , It is difficult to contact the head P.

In addition, like the head P shown by the alternate long and short dash line in FIG. 12, the X-ray detector 128 is placed on the side opposite to the side where a part of the dental arch Ar is biased (here, the left side) (here, the right side). When the X-ray detector 128 is swiveled in a biased range, the X-ray detector 128 tends to come into contact with the head P.

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

In this way, when performing X-ray CT imaging with a part of the dental arch Ar at a position deviated from the anteroposterior axis of the head P as the imaging region R, the X-ray detector 128 relatively close to the head P By turning a portion of the dental arch Ar that is biased to the same side as the biased side, it is possible to prevent the X-ray detector 128 from coming into contact with the head P. In particular, when the X-ray detector 128 turns in a range of 270 ° or less, a range in which the X-ray detector 128 does not turn can be provided around the photographing region R.

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

FIG. 32 describes the detection movement trace OD formed by the movement of the X-ray detector 128 during X-ray CT imaging. The detection movement trace OD is the X when the turning support portion 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. This is the trajectory drawn by the line detector 128. In FIG. 32, the detected movement trace OD is indicated by a shaded area. In the illustrated example, the detection movement trace OD when the swivel support portion 124 and the X-ray detector 128 are swiveled by 180 ° is shown. In this case, the detection movement trace OD is formed in a U shape. Therefore, looking around the turning center of the X-ray detector 128, there are an arc-shaped closed region CA and an open region OA. Since the closed region CA is U-shaped, the inner region CAI of the closed region CA is also U-shaped. The open region OA is located in the direction in which the central portion of the arc-shaped movement locus of the X-ray generator 126 is located with respect to the closed region CA. The X-ray detection trajectory Or is set as described above so that the inner region CAI does not come into contact with the head surface.

FIG. 33 shows another setting example. The turning angle of the turning support portion 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 of the photographing region R in the x direction are just accommodated. In the illustrated example, for the 180 ° turning range shown in FIG. 32, fa / 2 minutes is added in the negative direction of turning at the turning start position ST, and fa / 2 is added in the positive direction of turning at the turning end position ED. Minutes have been added.

FIG. 34 describes a detector existence area in which the X-ray detector 128 exists and a safety area in which the X-ray detector 128 does not exist.

The X-ray generator 126 and the X-ray detector 128 swivel at a certain point as a swivel center CTR. The turning center CTR is placed at the position of the center A of the photographing area R at the time of 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 region where the X-ray detector 128 exists in the state shown in the figure is the detector presence region DTA.

Of the X-ray detectors 128, the surface formed by the detection facing surface 128f, which is the surface facing the turning center CTR, is defined as the detector surface 128fs, and the X-ray detector 128 located between the detector surface 128fs and the turning center CTR is The non-existent area is defined as the safety zone SFA. In FIG. 34, the safety zone SFA is a region with an oblique crosshatch. Within the safety zone SFA, the distance DTD between the turning center CTR and the detector surface 128fs exists not as a single unit but as a spread (as individual distance element DTDes, for example, the distance element DTDe1 and the distance element DTDe2 shown in the figure are used. There is.).

FIG. 35 is a diagram showing a detector existence area and a safety area of the setting example of FIG. 33.

As the X-ray detector 128 swivels, the same region as the detection movement trace OD is formed as the detector presence area DTA.

The detector surface 128fs is formed in a U shape when viewed from the Z direction as the detection facing surface 128f swivels as the X-ray detector 128 swivels.

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

The distance between the turning center CTR and the head surface in the safety zone SFA is defined as DH. The distance DH is not a single distance, but exists in a wide range (the individual distance element DH includes, 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 and the distance DTD, the vector of the measurement direction of the distance element DTDe included in the distance DTD and the vector of 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, the area surrounded by connecting the ends of the detector existing area DTA by the detector existing area DTA can be set as the safety area SFA.

That is, in a broad concept, the safety zone SFA can be considered as the peripheral region of the head P located outside the range of the detector presence zone DTA, and the safety zone SFA can be considered as the region surrounded by the detector presence zone DTA. Good.

However, the safety zone SFA includes at least the safety zone SFA shown in FIG. 35.

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

The angle α is, for example, the turning center CTR in which the detector surface 128 fs is located at the position of the center A of the imaging region R with respect to the head P and the imaging region R whose positions are designated with respect to the head P in the calculation. It can be determined by performing a simulation of rotating around the head P and finding a range in which the surface of the head P falls within the safety zone SFA.

Then, the X-ray generator 126 and the X-ray detector 128 rotate around the imaging region R of the head P, so that the X-ray projection image data required to generate the X-ray CT image of the imaging region R is generated. 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 accepted by the shooting area position setting unit 151a, and the position on the mechanism is changed. It is preferable to fix the swivel axis X1 at the position of the center A of the imaging region R and perform X-ray CT imaging. That is, when the position of the imaging region R (for example, the left molar or the right molar) is set and 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 apparatus 110 is determined. Therefore, the turning control unit 151b controls the turning shaft moving mechanism 134 to move the turning shaft X1 on the mechanism to the center A of the photographing region R. Then, the swivel axis X1 on the mechanism can be fixed at the position of the center A of the imaging region R to perform X-ray CT imaging.

Similarly, when the front tooth is set and accepted as the imaging region R, the position of the swivel shaft X1 on the mechanism is moved, the swivel shaft X1 on the mechanism is fixed at the position of the center A of the imaging region R, and X-rays are emitted. CT imaging may be performed.

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

<Effects, etc.>
According to the X-ray CT imaging device 110 configured as described above, when the imaging region R is located at a position biased to the left or right with respect to the midline Mc of the head P, the central portion OrM of the X-ray detection trajectory OrM However, in order to determine the turning range of the turning support portion 124 so that the imaging region R is biased to the same side as the biased side with respect to the midline Mc, the X-ray generator 126 and the X-ray detector 128 Can be prevented from coming into contact with 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 an X-ray CT image as clear as possible can be obtained.

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

Further, when the imaging region R targets the anterior tooth region, the swivel support portion 124 is located so 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 surface including the midline Mc. Since the turning range of the X-ray is set, it is possible to prevent the X-ray generator 126 and the X-ray detector 128 from coming into contact with the head P even when the front teeth are X-ray CT-photographed.

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 to be smaller than the maximum distance LD, the X-ray detector 128 can be rotated as close to the head P as possible. , It is possible to obtain an X-ray CT image as clear as possible.

Further, since the swivel drive mechanism 130 includes a swivel shaft moving mechanism 134 that moves the swivel shaft X1 on the mechanism in a direction intersecting the axial direction of the swivel shaft X1 on the mechanism, the swivel shaft X1 on the mechanism is positioned at a fixed position. The swivel shaft moving mechanism 134 swivels on the mechanism in synchronization with the swivel support portion 124 being swiveled while the swivel support portion 124 is swiveled or the swivel support portion 124 is swiveled around the swivel shaft X1 on the mechanism. By moving the axis X1 and causing the swivel support portion 124 to perform a combined motion, the X-ray generator 126 and the X-ray detector 128 are swiveled around the center A of the imaging region R, thereby causing X-rays. It is possible to adjust the turning trajectories of the generator 126 and the X-ray detector 128.

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 photographing area R set and accepted by the photographing area position setting unit 151a. X-ray CT imaging is performed by fixing the swivel axis X1 on the mechanism 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 turn in a stable orbit, and an X-ray CT image as clear as possible can be obtained.

<Modification example>
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. By doing so, we proposed a configuration that avoids contact between the X-ray detector 128 and the head P.

When the turning angle of the X-ray generator 126 and the X-ray detector 128 is 360 ° or more, the turning radius of the X-ray detector 128 is increased so that 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 turning one or more turns.

Regarding the radius of gyration of the X-ray detector 128, the swivel shaft moving mechanism 134 swivels the swivel shaft X1 on the mechanism in synchronization with the swivel mechanism 132 swiveling the swivel support portion 124 around the swivel shaft X1 on the mechanism. By moving the swivel support portion 124 to perform a synthetic motion, the X-ray generator 126 and the X-ray detector 128 can be adjusted by swiveling around the center A of the imaging region R. In particular, here, when the X-ray generator 126 and the X-ray detector 128 are rotated as described above, the rotation axis moving mechanism 134 uses the rotation axis X1 on the mechanism as the rotation center with the center A of the photographing region R as the rotation center. Rotate and move. Then, the distance of the X-ray generator to the center A of the photographing area R and the distance of the X-ray detector 128 to the center A of the photographing area R can be kept constant.

In the second embodiment, the example in which the swivel shaft X1 is closer to the X-ray detector 128 than the X-ray generator 126 has been described. Therefore, if the X-ray detector 128 is swiveled with the swivel axis X1 aligned with the center A of the photographing region R partially designated in the dental arch Ar, the X-ray detection is detected. The vessel 128 can rotate near the photographing area R.

On the premise of this configuration, in the first modification, when the X-ray generator 126 and the X-ray detector 128 are swiveled around the imaging region R by 360 ° or more for a part or all of the dental arch Ar. , An example of increasing the turning radius so that the X-ray detector 128 does not come into contact with the head P will be described.

In this case, as shown in FIG. 14, the swivel axis X1 on the mechanism is separated from the center A of the imaging region R toward the X-ray detector 128 so that the X-ray detector 128 is further separated from the imaging region R. In this state, it is preferable to rotate the image around the center A of the photographing area R. That is, with the swivel shaft X1 on the mechanism positioned between the center A of the imaging region R and the X-ray detector 128, the swivel shaft X1 on the mechanism is swiveled in synchronization with the swivel support portion 124. Just do it. In this case, the turning axis X1 on the mechanism moves on the 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 a state of coincident with the center A of the imaging region R. Is done. Assuming that the distance between the swivel axis X1 and the X-ray detector 128 is E (1) and the radius of gyration of the swivel axis X1 on the mechanism 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 The turning radius q of the above is E (1) + r, and the X-ray detector 128 can be swiveled with a larger diameter than that described in the second embodiment. Assuming that the distance between the turning axis X1 and the X-ray generator 126 is E (2), the radius of gyration 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, the range where E (1) + r is smaller than E (2) -r, that is, the X-ray detector 128 is from the X-ray generator 126. It is assumed that r is set in a range approaching the shooting area R.

The swivel control of the swivel shaft X1 on the mechanism by the swivel shaft moving mechanism 134 can be realized by controlling as follows. The coordinates of the swivel axis X1 on the mechanism are once considered away from FIG. For example, the coordinates of X and Y in the XYZ coordinate system of the center A of the photographing region R are set to (X (a) and X (a)), and the turning angle of the turning support portion 124 by the turning mechanism 132 is set to θ (+ X side). It is assumed that there is an X-ray generator 126 and the X-ray detector (and the swivel axis X1) is on the −X side, and these are angles that rotate clockwise). The X-direction drive unit 136 sets the X coordinate of the swivel shaft X1 on the mechanism to "X (a) -rcosθ", and the Y-direction drive unit 138 sets the Y coordinate of the swivel shaft X1 on the mechanism to "Y (a) + rsinθ". Therefore, the swivel shaft moving mechanism 134 may be controlled in synchronization with the swivel control by the swivel mechanism 132. This control content can be similarly applied to each of the following modified examples in which the swivel shaft X1 on the mechanism is swiveled.

In the first modification, when the X-ray generator 126 and the X-ray detector 128 are swiveled around the imaging region R by 360 ° or more, the swivel radius is prevented so that the X-ray detector 128 does not come into contact with the head P. Although the example of increasing the size has been described, this content is also applicable to the case where the X-ray generator 126 and the X-ray detector 128 are swiveled by 270 ° or less.

In the modified examples shown in FIGS. 15 and 16, both when the X-ray generator 126 and the X-ray detector 128 are swiveled by 270 ° or less (here, 180 °) and when they are swiveled by 360 °. An example of controlling the position of the swivel axis X1 on the mechanism with respect to the center A of the imaging region R so as to separate the position of the swivel shaft X1 on the mechanism 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 by 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. When the X-ray generator 126 and the X-ray detector 128 turn 360 ° regardless of the position where the photographing area R is set, the operation and control for increasing the diameter of the turn are performed. It is good. In this modification, the swivel shaft X1 on the mechanism is located at the center of the X-ray generator 126 and the X-ray detector 128. Therefore, the distance of the X-ray generator 126 with respect to the swivel shaft X1 on the mechanism and the distance of the X-ray detector 128 with respect to the swivel shaft X1 are the same.

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

If the swivel axis X1 on the mechanism is aligned with the center A of the imaging region R and the X-ray generator 126 and the X-ray detector 128 are swiveled to perform CT imaging, the X-ray detector 128 is largely separated from the imaging region R. When the X-ray detector 128 is to be photographed as close as possible to the photographing area R, the trajectory as shown in FIG. 15 is suitable.

When the X-ray generator 126 and the X-ray detector 128 are swiveled by 360 °, the X-ray detector 128 may come into contact with the rear portion of the head P or the like if a swivel trajectory similar to the above is drawn.

Therefore, in the example shown in FIG. 16, the swivel shaft X1 on the mechanism is swiveled with a radius r (1) around the center A of the imaging region R, and the swivel support portion 124 is centered on the swivel shaft X1 on the mechanism. Turn. More specifically, in synchronization with the swivel support portion 124 being swiveled around the swivel shaft X1 on the mechanism by the swivel mechanism 132, the swivel shaft X1 on the mechanism is swiveled by the swivel shaft moving mechanism 134 in the photographing region R. It is swiveled with a radius r (1) around the center A. The radius r (1) <radius r (2). The swivel axis X1 on the mechanism moves on the circular orbit CL (1) having a radius r (1). Further, the swivel axis X1 on the mechanism swivels at a position away from the center A of the imaging region R toward the X-ray generator 126, and therefore the swivel shaft X1 on the mechanism generates X-rays with the center A of the imaging region R. It is between the vessel 126.

The swivel diameter of the X-ray detector 128 in this case is larger than that shown in FIG. Here, the radius is increased by the radius r (2) − radius r (1). Therefore, even if the X-ray detector 128 is swiveled 360 °, the X-ray detector 128 can swivel around the head P without contacting the head P. Since the X-ray generator 126 turns at a position farther from the imaging region R than the X-ray detector 128, contact with the head P is avoided.

In this way, both when the X-ray generator 126 and the X-ray detector 128 are swiveled by 270 ° or less (here, 180 °) and when they are swiveled by 360 °, the swivel axis X1 on the mechanism It may be separated from the center A of the photographing area R. In this case, depending on the positional relationship of the swivel shaft X1 between the X-ray generator 126 and the X-ray detector 128, the direction in which the swivel shaft X1 on the mechanism deviates, and the radii r (1) and r (2) above. The magnitude relationship may be reversed.

Further, when the X-ray generator 126 and the X-ray detector 128 are swiveled by 270 ° or less (180 ° in this case), the swivel axis X1 on the mechanism is swiveled with a radius r about the center A of the imaging region R. When the swivel support portion 124 is swiveled around the swivel shaft X1 on the mechanism and the X-ray generator 126 and the X-ray detector 128 are swiveled 360 °, the swivel shaft X1 on the mechanism is set in the photographing region R. The swivel support portion 124 may be swiveled in a state of being aligned with the center A. For example, when the swivel axis X1 on the mechanism is at or near the center position of 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 detector are detected. When the device 128 is swiveled 360 °, the swivel support portion 124 may be swiveled with the swivel axis X1 on the mechanism aligned with the center A of the photographing region R.

In this way, in synchronization with the swivel mechanism 132 turning the swivel support portion 124 around the swivel shaft X1 on the mechanism, the swivel shaft X1 on the swivel shaft moving mechanism 134 mechanism is moved to move the swivel support portion. By causing 124 to perform a synthetic motion, the X-ray generator 126 and the X-ray detector 128 can rotate around the center A of the imaging region, so that the X-ray generator 126 and the X-ray detector 128 can rotate around the center A of the imaging region. Therefore, it is possible to adjust the turning trajectories of the X-ray generator 126 and the X-ray detector 128, particularly the turning diameter.

At this time, since the swivel shaft moving mechanism 134 rotates and moves the swivel shaft X1 on the mechanism with the center A of the imaging region R as the center of rotation, even if the swivel shaft X1 on the mechanism is moved, the X-ray generator 126 and X The line detector 128 can move along a circular orbit or a near-circular orbit.

Further, during the X-ray CT imaging, the distance of 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 enlarged in order to keep them constant. X-ray CT imaging can be performed while keeping the rate constant.

{Third embodiment}
The 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 designated by the same reference numerals and the description thereof will be omitted.

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

The X-ray CT imaging device 210 differs from the X-ray CT imaging device 110 in that it includes a turning range setting unit 251a, and an imaging program 253a corresponding to the imaging program 153a is set by the turning range setting unit 251a. This is a point where the X-ray generator 126 and the X-ray detector 128 are swiveled according to the swivel range.

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

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

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

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

That is, when performing X-ray CT imaging, the setting of the size of the imaging area is accepted in step S21. The size of the photographing 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 photographing area covers the entire dental arch or a part of the dental arch. When it is determined that the size of the imaging area covers the entire dentition row, the process proceeds to step S32, and CT imaging is performed on the entire dentition row. In this case, the turning trajectories of the X-ray detector 128 and the X-ray generator 126 may be the same as those for performing X-ray CT imaging on a part of the anterior teeth of the dental arch.

If it is determined in step S22 that the size of the photographing area covers a part of the tooth arch row, the process proceeds to step S23.

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

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 in the display example in the operation panel device 158 described in the second embodiment. An image 293 for setting a turning range 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 area 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. As a plurality of turning range selection images, 180 ° selection image 293a and 360 ° selection image 293b are displayed. When the user selectively touches either the 180 ° selected image 293a or the 360 ° selected 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. May be good.

In the above example, the example of setting the turning range using the touch panel has been described, but the setting of 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 processes of steps S25 to S27 are 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 the X-ray detector 128 or the like is swiveled by 270 ° or less (180 °) to perform X-ray CT imaging.

When a 360 ° turn is accepted as the turn range in step S23, the processes of steps S28 to S31 are executed.

As described in the modified example of the second embodiment, when the X-ray detector 128 is swiveled by 360 °, the swirling diameter of the X-ray detector 128 may be made larger. However, the position of the shooting area on the subject varies. If the position of the swivel axis X1 on the mechanism is adjusted according to the position of the shooting area on the subject, and the swivel trajectories of the X-ray generator 126 and the X-ray detector 128 that swivel around the subject are devised, the swivel trajectory around the subject is devised. The X-ray detector 128 can be brought as close as possible to the photographing region R while suppressing the contact of the X-ray generator 126 and the X-ray detector 128 that swirl around the subject with the subject. In steps S28 to S31, processing for that purpose is executed.

In step S28, the operation of setting the position of the photographing area R is accepted. The reception of the operation for setting the position of the photographing area R can be performed in the same manner as described in step S11.

In the next step S29, the turning control content and the regulation amount are determined according to the position of the set shooting area. The swivel control content indicates how the X-ray generator 126 and the X-ray detector 128 are swiveled around the head P. Such turning control contents include at least one locus of the X-ray generator 126 and the X-ray detector 128, a moving locus of the turning shaft X1 on the mechanism by the turning shaft moving mechanism with respect to the turning speed by the turning mechanism 132, and turning by the turning mechanism 132. It is represented by the moving coordinates of the X-ray drive unit 136 and the Y-direction drive unit 138 with respect to the turning speed of the support unit 124.

Once the swivel 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 swiveled around the center A of the imaging region R. Assuming that the smaller 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 swivel axis X1 is on the side close to the X-ray detector 128 in the swivel support portion 124, the separation distance D is the distance between the center A of the photographing 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 photographing area is set as described above, the position of the photographing area R in the apparatus 110 is known. ..

Further, since the distance of the X-ray generator 126 with respect 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 enter the X-ray detector 128 through the head P. 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 /. It becomes D.

Further, once the turning control content is determined, the minimum width of X-rays for allowing the X-rays generated from the X-ray generator 126 to pass through the entire imaging region R is determined, and therefore should be regulated by the X-ray detector 128. The width of the X-ray regulation width (X-ray regulation hole) should also be set to match the minimum width, or at least within a range larger than the minimum width and within a range that prevents excessive X-ray irradiation around the minimum width. Can be done.

The turning control content and the regulation amount according to the position of the set imaging region can be determined, for example, with reference to a reference table as shown in FIG. 21. That is, a reference table in which the turning control content, the separation distance D (magnification m), and the regulation width W are associated with the position of the photographing region is registered in advance. In the example shown in FIG. 21, the X-ray detector 128 is swiveled with a radius q (1) with respect to the position of the imaging region as the front tooth, the separation distance D (1) (magnification m (1)), and the like. The regulation width W (1) is associated with it. If turning the X-ray detector 128 with the radius q (1) is defined by the turning content of the turning shaft X1, it can be expressed as turning the turning shaft X1 with the radius r (1). In order to keep the X-ray detector 128 away from the photographing area R, the swivel axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the photographing area R. Further, the X-ray detector 128 is swiveled with a radius q (2), the separation distance D (2) (magnification m (2)), and the regulation width W (2) when the position of the imaging region is the molar. ) Is associated. If turning the X-ray detector 128 with the radius q (2) is defined by the turning content of the turning shaft X1, it can be expressed as turning the turning shaft X1 with the radius r (2). In order to keep the X-ray detector 128 away from the photographing area R, the swivel axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the photographing area 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 ( Specific numerical values are specified for 2), the magnification m (2), and the regulation width W (2). As will be described later, when the position of the imaging region is the front tooth, 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 the molar tooth. , 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) ), Regulation width W (1)> Regulation width W (2).

Based on the set imaging area R, it is determined whether the imaging area R is an anterior tooth or a molar, and based on the determination result, the corresponding turning control content, the separation distance D (magnification m), and the regulation width W Is determined. The determination of the position (anterior tooth or molar) of the imaging region R based on the set imaging region R is, for example, whether the coordinates of the center A of the set imaging region R belong to the preset anterior tooth region or the molar region. It can be judged by judging. The imaging region in the reference table may be divided into more regions with respect to the dental arch.

Here, in the reference table, on the premise that the physique (size) of the head P is the same, the turning control content corresponding to the position of the photographing area R is defined, but the head P having a different size is defined. (For example, a head for an adult's physique and a head for a child's physique) may be defined with turning control contents corresponding to the position of the photographing region R in the same manner as described above. In this case, it is preferable to determine the turning control content corresponding to the position of the photographing area R according to the physique according to the physique input by the runner.

In the next step S30, the X-ray regulation unit 129 is controlled according to the determined regulation widths W (1) and W (2), and the X-ray detector 128 has a width X corresponding to the imaging region R. Make sure the line is illuminated.

In the next step S31, CT imaging is performed by performing turning control based on the determined turning control content. That is, since the turning range setting unit 251a sets the turning range of 360 ° or more, the distance between the center A of the photographing area R and the X-ray generator 126 and the center A of the photographing area R and the X-ray detector When the smaller of the distances from 128 is defined as the separation distance D, a part of the range of the dentition arch Ar is set as the imaging area R and X-ray CT imaging is performed. On the mechanism of the imaging region R with respect to the center A so that the separation distance D becomes larger than the maximum distance LD, which is the maximum distance of the surface of the head P with respect to the center A of the imaging region R, depending on the position of the imaging region R. The position of the turning axis X1 of is changed. The maximum distance LD changes depending on the position of the photographing area R.

This turning operation will be described more specifically with reference to FIGS. 22 and 23.

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

The maximum distance LD of the photographing region R with respect to the surface of the head P is assumed. When the anterior tooth region is the first imaging region R (1), the anterior tooth region is a local region located at a position closer to the front of the head P (a position biased forward), so that the rear surface of the head P is the first. 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), which is the farthest from the first imaging region R (1) (see FIG. 23). When the molar region is defined as the second imaging region R (2), the molar region is located closer to the center of the head P in the anteroposterior direction and closer to one side in the width direction. The surface is the 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 anteroposterior direction, the maximum distance LD (1) when the anterior tooth is the first imaging region R (1) is usually the second molar region. It is larger than the maximum distance LD (2) when the shooting area R (2) is set. Therefore, when the anterior teeth are set to the first imaging area R (1), the imaging area of the X-ray generator 126 and the X-ray detector 128 is set as compared to the case where the molar region is set to the second imaging region R (2). The closer one should be swiveled outward.

Therefore, when performing X-ray CT imaging with the molar region as the second imaging region R (2), the mechanism is such that the turning radius q (2) of the X-ray detector 128 is set as shown in FIG. The swivel support portion 124 is swiveled by moving the swivel shaft X1. The distance between the center A and the X-ray detector 128 in this case is the separation distance D (2). Here, the swivel shaft X1 on the mechanism is shifted to the X-ray detector 128 side and swiveled with a radius r (2).

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

If the X-ray generator 126 and the X-ray detector 128 are swiveled in the same locus as above with the front tooth region as the first imaging region R (1), 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 swiveled along the same locus 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 alternate long and short dash line (see FIG. 22). It can be seen that the head P indicated by the alternate long and short dash line may come into contact with the head P when the X-ray detector 128 comes to the −Y side.

Therefore, when performing X-ray CT imaging with 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)). The swivel shaft X1 on the mechanism is moved so that the swivel support portion 124 is swiveled so as to have> q (2)). The distance between the center A and the X-ray detector 128 in this case is the separation distance D (1). Here, the swivel shaft X1 on the mechanism is shifted to the X-ray detector 128 side and swiveled with a radius r (1) (r (1)> r (2)).

In this case, the X-ray generator 126 turns with a smaller radius than in the case shown in FIG. The X-ray detector 128 turns with a larger radius than that shown in FIG. The relationship between the orbit of the X-ray generator 126 and the orbit of the X-ray detector 128 shown in FIG. 23 is closer to each other than those relationships shown in FIG. Therefore, neither the X-ray generator 126 nor the X-ray detector 128 can rotate around the head P without contacting 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. The X-ray image data required for the above is obtained, and an X-ray CT image is generated based on the data.

As described above, the swivel diameter r of the X-ray detector 128 is such that the swivel axis X1 on the mechanism coincides with the center A of the imaging region R, and the swivel shaft X1 on the mechanism is around the center A of the imaging region R. When turning or turning the turning shaft X1 around the center A, the turning shaft X1 is shifted to the X-ray detector 128 side or the X-ray generator 126 side, and the amount of these shifts is adjusted. It can be adjusted by doing so. The position of the swivel shaft X1 on the mechanism is adjusted according to the position of the swivel shaft X1 on the mechanism between the X-ray generator 126 and the X-ray detector 128.

According to the present embodiment, when the 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 rotates in a range biased to the same side as a part of the dentition arch Ar depending on the position of the imaging region R set by the imaging region position setting unit 151a, X It is possible to prevent the line generator 126 and the X-ray detector 128 from coming into contact with the head P, and to obtain an X-ray CT image as clear as possible.

Further, when a turning range of 360 ° or more is set, shooting is performed so that the separation distance D becomes larger than the maximum distance LD according to the position of the shooting area R set by the shooting area position setting unit 151a. By changing the position of the swivel axis X1 on the mechanism with respect to the center of the region R, the X-ray generator 126 and the X-ray detector 128 that swivel around the head P, which is the subject, by 360 ° or more 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 an angle obtained by adding the spreading angle of the X-ray beam irradiation (see the angle β in FIG. 15) to 180 ° or 180 °. Further, it is preferable to accept a turning range of 360 ° as a turning range of 360 ° or more. As a result, the X-ray generator 126 and the X-ray detector 128 that rotate around the head P when performing a full scan by CT imaging of 360 ° and a half scan by CT imaging of around 180 ° are performed on the head P. It is possible to suppress contact with.

Further, when adjusting the swivel diameters of the X-ray generator 126 and the X-ray detector 128, the swivel mechanism 132 swivels in synchronization with the swivel support portion 124 around the swivel shaft X1 on the mechanism. The axis movement mechanism 134 moves the swivel shaft X1 on the mechanism to cause the swivel support portion 124 to perform a combined motion, whereby 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 shaft moving mechanism 134 rotates and moves the turning shaft X1 on the mechanism with the center A of the imaging region R as the center of rotation, so that the turning shaft X1 on the mechanism is moved when performing X-ray CT imaging. However, the X-ray generator 126 and the X-ray detector 128 can be swiveled along a trajectory as close to a circle as possible.

Further, during the X-ray CT imaging, the distance of 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 enlarged in order to keep them constant. X-ray CT imaging can be performed while keeping the rate constant.

<Modification example>
When the X-ray generator 126 and the X-ray detector 128 are swiveled around the photographing region R, the position of the swivel axis may be controlled according to the size of the physique of the head P, which is the subject.

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

That is, the X-ray CT imaging device 210 sets the body shape of the head P, which is the subject, so that the first body shape and the second body shape smaller than the first body shape can be accepted. A unit 258 is provided (see FIG. 17, hereinafter referred to as a physique setting unit 258). Further, the photographing program 253a includes a process of changing the position of the turning axis X1 on the mechanism with respect to the center A of the photographing area R according to the size of the body shape of the subject set by the body shape setting unit 258 of the subject. Therefore, the turning control unit 251b of the turning axis X1 on the mechanism with respect to the center A of the shooting area R according to the size of the body shape of the subject set by the body shape setting unit 258 of the subject based on the shooting program 253a. Performs control to change the position. More specifically, the turning control unit 251b has a separation distance when the set body shape of the subject is the first body shape according to the size of the body body of the subject set by the body shape setting unit 258 of the subject. The position of the turning axis X1 on the mechanism with respect to the center A of the photographing region R so that D is larger than the separation distance D when the set body shape of the subject is smaller than the first body shape and is the second body shape. 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, the input setting of the physique is accepted in step S41.

Here, an example of accepting 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 in the display example in the operation panel device 158 described in the second embodiment. An image 393 for setting the physique is additionally displayed on the display unit 158a of the operation panel device 158. Here, the physique setting image 393 is displayed on the right side of the display unit 158a and above the shooting area setting image 194.

When the operator touches the physique setting image 393, as shown in FIG. 26, the selected image corresponding to the physique setting image 393 is displayed. As a plurality of body shape 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 either the normal size selection image 393a or the large size selection image 393b, the input operation of the physique of the head P, which is the subject, is accepted.

In the above example, the example of setting the physique using the touch panel has been described, but the physique setting may be accepted via a switch (push button) or the like that physically accepts the 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 receives the input operation of the physique of the head P according to the received contents. Make settings. Here, the physique setting unit 258 receives an input operation to select one from the normal size selection image 393a and the large size selection image 393b, which are the physique sizes of a plurality of selection candidates, through the operation panel device 158, and the head P Set the physique of. The large size selection image 393b is an image for reception of the first physique, and the normal size selection image 393a is an image for reception of the 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, the head P, which is the subject, is imaged, the head region is extracted from the captured image, and the size of the head is extracted from the extracted head region. To set the physique by recognizing this, the head fixing device 142 that fixes the head is provided with a holding portion that holds the head P by sandwiching it from the left and right or the front-back direction, and the opening degree of the holding portion is measured by a sensor or the like. By detecting it, it is conceivable to recognize the size of the head and set the physique.

In the next step S43, the turning control content, the regulation amount, and the like are determined according to the set physique. The turning control content and the regulation amount according to the set physique can be determined by referring to, for example, a reference table as shown in FIG. 27. That is, the turning control content, 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, the X-ray detector 128 is swiveled with a radius q (M) as the swivel control content with respect to the normal body shape P (M), and the separation distance D (M) (magnification m (M)). ), The regulation width W (M) is associated. If turning the X-ray detector 128 with a radius q (M) is defined by the turning content of the turning shaft X1, it can be expressed as turning the turning shaft X1 with a radius r (M). In order to keep the X-ray detector 128 away from the photographing area R, the swivel axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the photographing area R. In addition, the X-ray detector 128 is swiveled with a radius q (L) for a large body size P (L), the separation distance D (L) (magnification m (L)), and the regulation width W (L) correspond. It is attached. If turning the X-ray detector 128 with a radius q (L) is defined by the turning content of the turning shaft X1, it can be expressed as turning the turning shaft X1 with a radius r (L). In order to keep the X-ray detector 128 away from the photographing area R, the swivel axis X1 is shifted toward the X-ray detector 128 with respect to the center A of the photographing area 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)), and the separation distance D ( Specific numerical values are specified for L), the magnification m (L), and the regulation width W (L). As will be described later, when the physique P (L) is large, the X-ray detector 128 is located farther from the center A of the imaging region than when the physique P (M) is normal. , 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) ), Regulation width W (M) <Regulation width W (L).

In the next steps S44 and S45, the X-ray regulation unit 129 is controlled according to the determined regulation widths W (M) and W (L), and the width from the X-ray detector 128 according to the photographing area R. X-rays are emitted.

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

In the case of the second physique P (M) having a relatively small physique, as shown in FIG. 28, the swivel support portion 124 is swiveled so that the swivel diameter of the X-ray detector 128 is the diameter q (M). Let me. More specifically, in synchronization with the swivel support portion 124 being swiveled around the swivel shaft X1 on the mechanism by the swivel mechanism 132, the swivel shaft X1 on the mechanism is swiveled by the swivel shaft moving mechanism 134 in the photographing region R. It is swiveled with a radius r (M) around the center A. The swivel shaft 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 the direction orthogonal to the turning 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 physique P (M). Since the X-ray generator 126 turns at a position farther than the center A of the imaging region R than the X-ray detector 128, the X-ray generator 126 also does not come into contact with the head P (P2) and heads. It is possible to turn around the portion P (P2). The X-ray generator 126 is closer to the imaging center A than the X-ray detector 128 on the orbit during X-ray imaging of the X-ray generator 126 and the X-ray detector 128 set for the imaging area R. 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.

Since 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 imaging region R is the head in both heads P. The occipital region of 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), which is in a common position in the front part. Occupy the area. In the case of the first physique P (L) having a relatively large physique, when the X-ray detector 128 turns in the same manner as described above, the X-ray detector 128 has a head P having the first physique P (L). May come into contact with.

Therefore, in the case of the first physique P (L) having a relatively large physique, as shown in FIG. 29, the swivel support portion 124 is swiveled so as to have a swivel diameter q (L) of the X-ray detector 128. Let me. More specifically, in synchronization with the swivel support portion 124 being swiveled around the swivel shaft X1 on the mechanism by the swivel mechanism 132, the swivel shaft X1 on the mechanism is swiveled by the swivel shaft moving mechanism 134 in the photographing region R. It is swiveled with a radius r (L) (r (L)> r (M)) around the center A. The swivel shaft 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 the center A of the imaging region R and the X-ray detector 128. The distance to and 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 turning axis X1. It is set larger than the maximum distance LD with. Therefore, the X-ray detector 128 does not come into contact with the head P (P (L)) having the larger first physique P (L), but moves around the head P (P (L)). Can turn. Since the X-ray generator 126 turns at a position farther than the center A of the imaging region R than the X-ray detector 128, the X-ray generator 126 also does not come into contact with the head P (P (L)). In addition, it can rotate around the head P (P (L)). The X-ray generator 126 is closer to the imaging center A than the X-ray detector 128 on the orbit during X-ray imaging of the X-ray generator 126 and the X-ray detector 128 set for the imaging area R. 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.

In addition, as shown in FIG. 28, the case of the second physique P (M) having a relatively small physique and the case of the first physique P (L) having a relatively large physique as shown in FIG. 29 are compared. Then, the distance between the center A of the photographing region R and the X-ray detector 128 is larger in the latter than in the former. Therefore, in order to allow the X-rays emitted from the X-ray generator 126 to pass through the entire imaging region R, the X-rays by the X-ray regulation unit 129 at the time of the second physique P (M) The regulation width W (M) may be set smaller than the X-ray regulation width W (L) by the X-ray regulation unit 129 at the time of the first physique P (L). This makes it possible to irradiate X-rays in a range commensurate with the imaging region R. That is, the regulation widths W (L) and W (M) are the separation distances D (L) and D (M) when the X-ray generator 126 and the X-ray detector 128 are swiveled around the center A of the photographing region R. It is set according to 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 by the regulation width Wx in the x direction, but may also be adjusted by adding the regulation width Wy in the y direction.

Then, 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 dentition arch. The 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 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), the X-ray generator 126 that swivels around the head P in order to change the position of the swivel axis X1 on the mechanism with respect to the center A of the imaging region R. And the X-ray detector 128 can be prevented from coming into contact with the head P.

In the above modification, the swivel axis X1 on the mechanism is swiveled around the center A of the imaging region R both when the physique P (L) of the head P is large and when the physique P (M) is small. When the swivel axis X1 on the mechanism is located near the center of the X-ray generator 126 and the X-ray detector 128, the second physique P (M) having a small physique is shown in FIG. At this time, the turning axis X1 on the mechanism may be aligned with the position of the center A of the photographing region R. In this case, as shown in FIG. 31, when the head P has a large body shape P (L), the swivel axis X1 on the mechanism is shifted toward the X-ray detector 128 on the mechanism. It is preferable to move the position of the turning axis X1 away from the center of the photographing area R and change the position of the turning axis X1 on the mechanism with respect to the center A of the photographing area R. When reducing the turning diameter of the X-ray detector 128, the position of the turning shaft X1 on the mechanism is set at the center of the imaging region R in the direction of shifting the turning shaft X1 on the mechanism toward the X-ray generator 126. It is preferable to change the position of the turning axis X1 on the mechanism with respect to the center A of the photographing region R away from the center A.

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

{Modification example}
Further, in each of the above-described embodiments and modifications, the normal scan in which the entire imaging region R is irradiated with X-rays has been described, but the region offset from the center of the imaging region is narrower than the imaging region. It can also be applied when performing an offset scan that irradiates X-rays.

It should be noted that the configurations described in the above embodiments and the 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 an example in all aspects, and the present invention is not limited thereto. It is understood that innumerable variations not illustrated can be assumed without departing from the scope of the present invention.

10, 110, 210 X-ray CT imaging device 20, 124 Swivel support 22, 126 X-ray generator 24, 128 X-ray detector 30, 230 Swivel drive mechanism 32, 132 Swivel mechanism 40, 151a Imaging area position setting unit 60 , 151b, 251b Swivel control unit 120 Imaging main unit 129 X-ray control unit 134 Swivel axis movement mechanism 142 Head fixing device 150 Main unit control unit 151 CPU
153a, 253a Shooting program 153b Reference table 158 Operation panel device 194 Shooting area setting image 194a to 194e Shooting area selection image 195 Illustration image 195a, 195b Shooting area image 251a Turning range setting unit 258 Body size setting unit 293 Turning range setting image 293a 180 ° selection image 293b 360 ° selection image 393 physique setting image 393a normal size selection image 393b large size selection image A shooting center Ar dentition arch D separation distance LD maximum distance P head R (X-ray CT) shooting area R ( 1) 1st imaging area R (2) 2nd imaging area q, r diameter

Claims (13)

An X-ray generator that generates X-rays and
An X-ray detector that detects the X-rays and
A swivel support portion 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 swivel drive mechanism including a swivel mechanism that swivels the swivel support portion,
An imaging area position setting unit that accepts the setting of the position of the X-ray CT imaging area for which the local region, which is a part of the dental arch of the head, is the target of the X-ray CT imaging,
A swivel control unit that controls the swivel drive mechanism and
A turning range setting unit that accepts the setting of a turning range of 270 ° or less and the setting of a turning range of 360 ° or more,
With
While the swivel control unit drives and controls the swivel drive mechanism to perform X-ray CT imaging of the X-ray CT imaging region by the X-rays, the X-ray generator and the X-ray detector are held on the head. The X-ray detector is swiveled around in a swivel 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. The X-ray generator passes around the head on the opposite side of the unevenly distributed side, and during the X-ray CT imaging, the X-ray detector forms an X-ray detection trajectory of the arc by the turning movement. ,
When the X-ray CT imaging area set by the imaging area positioning unit is located at a position biased to the left or right with respect to the center of the head, the central portion of the arc of the X-ray detection trajectory is The swivel range of the swivel support portion is set so that the X-ray CT imaging region is biased to the same side as the biased side with respect to the median .
Further, in the case of the turning range of 270 ° or less, the X-ray detector is positioned closer to the X-ray CT imaging region than the X-ray generator.
An X-ray CT imaging device that swivels the X-ray detector with a larger diameter in the swivel range of 360 ° or more than in the swivel range of 270 ° or less. The X-ray CT imaging apparatus according to claim 1.
The swivel drive mechanism drives the swivel support portion, and the swivel range is 180 ° or 180 ° plus the spread angle of X-ray beam irradiation as the swivel range of 270 ° or less. An X-ray CT imaging device that swivels and moves 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 that forms the X-ray detection trajectory with an arc trajectory that does not have a concave portion toward the X-ray CT imaging region. 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 central portion of the arc of the X-ray detection trajectory is the head of the head on the surface including the median. An X-ray CT imaging device that sets the swivel range of the swivel support portion so as to be located on the front side. The X-ray CT imaging apparatus according to any one of claims 1 to 4.
Assuming the maximum distance of the surface of the head to the center of the X-ray CT imaging region, the diameter of the swivel 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 device. The X-ray CT imaging apparatus according to any one of claims 1 to 5.
The swivel drive mechanism is an X-ray CT imaging device including a swivel shaft moving mechanism that moves a swivel shaft on a mechanism that swivels the swivel support portion in a direction intersecting the axial direction of the swivel shaft on the mechanism. The X-ray CT imaging apparatus according to claim 6.
When X-ray CT imaging is performed in the swivel range of 270 ° or less, the position of the swivel shaft on the mechanism is moved according to the position of the X-ray CT imaging region set and accepted by the imaging region position setting unit. An X-ray CT imaging device that fixes the swivel axis on the mechanism at a position at the center of the X-ray CT imaging region and performs the X-ray CT imaging. The X-ray CT imaging apparatus according to claim 6 or 7.
The swivel shaft moving mechanism moves the swivel shaft on the mechanism in synchronization with the swivel mechanism swiveling the swivel support portion around the swivel shaft on the mechanism, and the swivel support portion has a combined motion. An X-ray CT imaging device capable of rotating the X-ray generator and the X-ray detector around the center of the X-ray CT imaging region. The X-ray CT imaging apparatus according to claim 8 .
When assuming the maximum distance of the surface of the head with respect to the center of the front Symbol X-ray CT imaging area, when the pivoting range setting pivoting range of more than 360 ° at the portion is set, the center of the X-ray CT imaging area When the smaller of the distance between the X-ray generator and the center of the X-ray CT imaging area and the X-ray detector is set as the separation distance, the imaging area position setting unit is used. The position of the swivel axis on the mechanism with respect to the center of the X-ray CT imaging region is controlled so that the separation distance becomes larger than the maximum distance according to the set position of the X-ray CT imaging region. Line CT imaging device. The X-ray CT imaging apparatus according to claim 9.
The turning range setting unit
As the turning range of 270 ° or less, a turning range of an angle obtained by adding the spread angle of the X-ray beam irradiation to 180 ° or 180 ° is accepted.
An X-ray CT imaging device that accepts a turning range of 360 ° as the turning range of 360 ° or more. An X-ray generator that generates X-rays and
An X-ray detector that detects the X-rays and
A swivel support portion 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 swivel drive mechanism including a swivel mechanism that swivels the swivel support portion,
An imaging area position setting unit that accepts the setting of the position of the X-ray CT imaging area for which the local region, which is a part of the dental arch of the head, is the target of the X-ray CT imaging,
A swivel control unit that controls the swivel drive mechanism and
With
While the swivel control unit drives and controls the swivel drive mechanism to perform X-ray CT imaging of the X-ray CT imaging region by the X-rays, the X-ray generator and the X-ray detector are held on the head. The X-ray detector is swiveled around in a swivel 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. The X-ray generator passes around the head on the opposite side of the unevenly distributed side, and during the X-ray CT imaging, the X-ray detector forms an X-ray detection trajectory of the arc by the turning movement. ,
When the X-ray CT imaging area set by the imaging area positioning unit is located at a position biased to the left or right with respect to the center of the head, the central portion of the arc of the X-ray detection trajectory is The swivel range of the swivel support portion is set so that the X-ray CT imaging region is biased to the same side as the biased side with respect to the median.
Assuming the maximum distance of the surface of the head to the center of the X-ray CT imaging region, the diameter of the swivel 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 device. An X-ray generator that generates X-rays and
An X-ray detector that detects the X-rays and
A swivel support portion 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 swivel drive mechanism including a swivel mechanism that swivels the swivel support portion,
An imaging area position setting unit that accepts the setting of the position of the X-ray CT imaging area for which the local region, which is a part of the dental arch of the head, is the target of the X-ray CT imaging,
A swivel control unit that controls the swivel drive mechanism and
With
While the swivel control unit drives and controls the swivel drive mechanism to perform X-ray CT imaging of the X-ray CT imaging region by the X-rays, the X-ray generator and the X-ray detector are held on the head. The X-ray detector is swiveled around in a swivel 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. The X-ray generator passes around the head on the opposite side of the unevenly distributed side, and during the X-ray CT imaging, the X-ray detector forms an X-ray detection trajectory of the arc by the turning movement. ,
When the X-ray CT imaging area set by the imaging area positioning unit is located at a position biased to the left or right with respect to the center of the head, the central portion of the arc of the X-ray detection trajectory is The swivel range of the swivel support portion is set so that the X-ray CT imaging region is biased to the same side as the biased side with respect to the median.
The swivel drive mechanism includes a swivel shaft moving mechanism that moves a swivel shaft on a mechanism that swivels the swivel support portion in a direction intersecting the axial direction of the swivel shaft on the mechanism.
The swivel shaft moving mechanism moves the swivel shaft on the mechanism in synchronization with the swivel mechanism swiveling the swivel support portion around the swivel shaft on the mechanism, and the swivel support portion has a combined motion. The X-ray generator and the X-ray detector can rotate around the center of the X-ray CT imaging region.
Further provided with a turning range setting unit that accepts the setting of the turning range of 270 ° or less and the setting of the turning range of 360 ° or more.
Assuming the maximum distance of the surface of the head to the center of the X-ray CT imaging area, when a turning range of 360 ° or more is set by the turning range setting unit, the center of the X-ray CT imaging area is used. When the smaller distance between the distance to 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, it is set by the imaging area position setting unit. An X-ray that controls the position of the swivel axis on the mechanism with respect to the center of the X-ray CT imaging region so that the separation distance becomes larger 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 12.
The turning range setting unit
As the turning range of 270 ° or less, a turning range of an angle obtained by adding the spread angle of the X-ray beam irradiation to 180 ° or 180 ° is accepted.
An X-ray CT imaging device that accepts a turning range of 360 ° as the turning range of 360 ° or more.

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