JP2002219127A - Panoramic x-ray ct photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a panoramic X-ray CT photographic device for photographing an area not involved in a cone beam, namely a successive portion of an entire tooth area, for which a cone beam limited for partial irradiation of a subject is used. SOLUTION: A panoramic X-ray CT photographic device which is capable of efficiently changing a width D × height M × length W and a scope of an image to be reformed when a panoramic X-ray CT photograph is taken, where an X-ray source at one end of a rotating arm that irradiates cone beam to a subject in a limited range and an X-ray detector at other end that transmits the subject area allowed to be oppositely arranged, while a central position of the rotating arm is successively shifted, when necessary to an appropriate range when rotated by a rotational driving unit and its driving control means to change rotational frequency/shifting range or shifting range/rotational frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a part of the head and neck of a subject with an X-ray cone beam to obtain a CT image and a panoramic CT image of a part of the head and neck region of the subject or an arbitrary range. The present invention relates to an X-ray CT imaging apparatus capable of performing the above.

[0002]

2. Description of the Related Art As a CT apparatus conventionally used for dentistry, a local irradiation X-ray CT apparatus is known as a known technique. This device uses a cone beam to locally irradiate an X-ray to a part of an object while rotating an orbiting arm in which an X-ray generator and an X-ray detector are arranged to face each other. More specifically, with the center of rotation of the turning arm fixed at the center of a local part to be imaged, which is a part of the subject, an X-ray generator including only the local part from the X-ray generator. While locally irradiating the arm, the swiveling arm is adjusted according to the photographing conditions.
By turning the angle range of 0 ° or less, an X-ray projection CT image of an arbitrary tomographic plane in a local site can be obtained. Also, when performing panoramic radiography, the center of rotation of the swiveling arm must be made so that the X-ray flux is approximately perpendicular to the dental arch when performing square projection panoramic radiography. A local irradiating X-ray which can be fixed at the center of a circle inscribed in the envelope where a trajectory of the line is generated and a local beam is radiated to the area of the inscribed circle to obtain a panoramic tomographic image CT devices are known.

A conventional local X-ray CT imaging apparatus of this type has a limited area in which CT imaging can be performed by a single imaging operation. For example, when performing an implant operation or the like, a comprehensive operation including the surrounding area is performed. In contrast to the need for basic diagnostic information, the imaging range is cylindrical with a diameter of 38 mm and a height of 29 mm, and its cross section is almost the same as the size of a dental film according to the intraoral method. May not be obtained. It has also been pointed out that when the position is shifted and the image is taken again to increase the amount of information, it is necessary to give due consideration to the positional relationship between the two and to spend extra nerves and time.

[0004]

SUMMARY OF THE INVENTION In the present invention, a conventional dental X-ray CT imaging apparatus has been developed in view of such a situation. It can be applied not only to X-ray CT imaging of a local area, or a certain area, or a continuous whole jaw area from right to left, but also to an otolaryngological area, and can also reconstruct a three-dimensional CT image if necessary. A first object is to provide a panoramic X-ray CT imaging apparatus.

Another object of the present invention is to provide a panoramic X-ray CT imaging apparatus capable of changing the size of a reconstructed image area, particularly in the depth direction, when performing X-ray CT imaging of a continuous area other than a local area. Is to provide.

It is still another object of the present invention to provide a panoramic X-ray CT apparatus which fully considers not only the function, operability, design and cost performance but also the safety of the subject.

[0007]

In order to achieve the above object, in a panoramic X-ray CT imaging apparatus according to the present invention,
A limited range of combi through a rotary drive unit and one end of a rotary arm connected directly or indirectly to a rotary shaft of a rotary arm rotation control motor in the rotary drive unit via a throttle. An X-ray source for irradiating a camera and an X-ray detector for detecting X-rays transmitted through the subject at the other end,
The rotation of the turning arm causes the C and C of the subject's head and neck to rotate.
In a so-called X-ray CT imaging apparatus that performs T imaging, the rotating arm that is connected to the rotating shaft of a rotating arm rotation control motor in the rotating drive unit and that hangs down from the rotating drive unit has the center of the rotating shaft. Multi-rotation is possible as a center of rotation, and the rotation drive control means is required for the photographing from the start of the photographing to the end of the photographing for the photographing region or range set by the photographing mode setting means. The rotation angle range is rotated, and the rotation center of the swivel arm is rotated during the rotation along a photographing trajectory set in advance by a photographing mode setting in a plane orthogonal to the rotation axis center as required. While sequentially moving, the image data of an arbitrary section in the head and neck region is fetched as a straight line, a curved line, or a combination thereof, and the image data is processed. Any site or I, is that it has to obtain a reconstructed image in the range.

The rotating arm, which is connected to the rotating shaft of a rotating arm rotation control motor in the rotating drive unit and hangs down from the rotating drive unit, can rotate multiple times around the center of the rotating shaft, and can take pictures. Depending on the imaging region or range set by the mode setting means, the rotational drive control means sets the rotation angle range necessary for the imaging with respect to the predetermined moving distance of the rotation center of the swing arm on the imaging trajectory. It is possible to change the number of rotations per unit distance or the movement distance per rotation.

The rotating arm, which is connected to the rotation axis of a rotation arm rotation control motor in the rotation drive unit and hangs down from the rotation drive unit, is capable of performing multiple rotations around the rotation axis center. Depending on the imaging region or range set by the mode setting means, the rotational drive control means sets the rotation angle range necessary for the imaging with respect to the predetermined moving distance of the rotation center of the swing arm on the imaging trajectory. This is programmed as an algorithm for determining the amount of change as the number of rotations per unit distance or the moving distance per rotation, and a selection means is provided.

The rotating arm, which is connected to the rotation axis of a rotation arm rotation control motor in the rotation drive unit and hangs down from the rotation drive unit, is capable of performing multiple rotations around the rotation axis as a rotation center. Depending on the imaging region or range set by the mode setting means, the rotational drive control means sets the rotation angle range necessary for the imaging with respect to the predetermined moving distance of the rotation center of the swing arm on the imaging trajectory. The change amount is numerically input as the number of rotations per unit distance or the movement distance per rotation, and can be arbitrarily changed.

The turning arm, which is connected to the rotation shaft of a rotation arm rotation control motor in the rotation drive unit and hangs down from the rotation drive unit, is capable of making multiple rotations around the rotation axis as a rotation center. Is provided with a safety switch for preventing subject interference.

A safety switch for preventing interference between the subject and the subject's head positioning device is provided between the subject's chair and the subject's head positioning device. That is, the following means are provided.

A chair for a subject, a positioning device for a head for a subject, a rotary drive unit provided above the chair, and a rotary shaft of a turning arm rotation control motor in the rotary drive unit, directly or indirectly. An X-ray source for irradiating a cone beam at one end of a rotating arm connected to the head, and an X-ray detector for detecting X-rays transmitted through a subject are arranged at the other end of the rotating arm. In a so-called X-ray CT imaging apparatus for performing CT imaging of the head and neck of a subject by rotating a camera, the X-ray CT apparatus is directly or indirectly connected to a rotation axis of a rotation arm rotation control motor in a rotation drive unit. The turning arm hanging from the rotary drive unit can rotate multiple times around the center of the rotation axis, and can be used for an imaging part or range set by the imaging mode setting means from the start of the imaging. Until the end of the shadow, and rotates the rotation angle range required for the photographing by the rotation control means, and,
During the rotation, the center of rotation of the turning arm is sequentially moved as necessary on a plane orthogonal to the center of the rotation axis along a photographing trajectory set in advance by a photographing mode setting, or That is, the rotation arm is sequentially moved in parallel along the center of the rotation axis while the rotation arm is rotating, or two selecting means are provided.

[0014] Further, the rotation drive control means does not move the rotation center of the revolving arm at the photographing start position at the photographing start position, for example, with respect to the photographing region or range set by the photographing mode setting means. After performing a predetermined rotation such as 180 ° or 360 °, the turning and movement are sequentially performed until the photographing completion position, and image data is acquired during this time. That is, the above-described predetermined rotation and the acquisition of image data can be performed again without moving the rotation center.

Then, an X-ray source for irradiating an X-ray cone beam opposed to both ends of the support frame so as to sandwich the subject and image data of the X-ray con-beam transmitted through the subject are acquired. X-ray detector, a chair unit having a head fixing device for positioning a subject prior to photographing, an elevating means for individually moving the head fixing device and the chair unit up and down, and the chair unit The rotary unit has a rotary drive means for turning and moving the camera in the horizontal direction, and the chair portion pivotally supported by a rotary shaft erected by the rotary drive means can perform multiple rotations around the rotary shaft. The rotation drive control means rotates the rotation angle range required for the imaging from the start of the imaging to the end of the imaging with respect to the imaging region or range set by the mode setting means, and during the rotation. The chair is rotating The shooting mode - if necessary along the predetermined shot trajectory by de setting is to sequentially movable between a plane perpendicular to the rotation axis center.

The position correcting means for correcting the position of the center or the start position of the imaging part which has been positioned in advance is more accurate from two directions orthogonal to the X and Y axes with respect to the imaging part. X-ray fluoroscopy is performed, images from these two directions are displayed on a monitor, and the monitor is displayed at the center of the displayed imaging target portion or at the respective center positions in the X and Y axis directions to be the imaging start positions. The center position cursor at the time of photographing is moved, and the position of the rotation center of the turning arm can be automatically corrected to the position where the cursor is moved via the rotation drive control means of the rotation drive unit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A panoramic X-ray CT apparatus constructed as described above has a multi-rotation with its rotation axis hanging from an X-ray source and a rotation drive unit in which an X-ray detector is arranged oppositely. The rotating arm which can be used is necessary for the photographing by the rotational drive control means from the start of the photographing to the end of the photographing for the photographing region or range arbitrarily set by the photographing mode setting means. Rotation angle range
In addition, the rotation center of the turning arm is photographed during the rotation.
Along the imaging trajectory set in advance by the setting, if necessary, in a plane orthogonal to the center of the rotation axis, while moving sequentially, a straight line of any part of the head and neck region, or a curve, or any combination thereof A CT image of a cross section and a panoramic CT image can be photographed. Each time, any of a minimum range, such as a dental mode, a block mode, and a panoramic mode, is required to obtain diagnostic information suitable for a surgical procedure. Select the area of dentistry, otolaryngology area,
It is now possible to obtain optimal diagnostic information that was previously impossible with a single imaging. It goes without saying that a three-dimensional image can be reconstructed.

Further, with respect to the rotation of the swing arm and the movement of the center of the rotation axis, means for changing the number of rotations of the swing arm per unit movement amount or the movement amount per rotation is provided. Particularly, the dimension of the constituent image range in the depth direction can be changed.

Further, the swivel arm, which can move multiple times with the rotation axis hanging from the rotation drive unit as a rotation center, is provided with a safety switch on the lower surface thereof for preventing subject interference. Damage to the subject due to runaway of the elevating function due to damage to the elevating switch of the subject chair can be avoided.

A safety switch for preventing interference between the subject and the head positioning device for the subject is provided between the chair for the subject and the head positioning device for the subject, so that the chair and the head positioning device for the subject have a fixed distance regardless of their respective heights. By providing a means that does not approach the following, runaway of the elevating function due to damage to the elevating switch of the chair for the subject, or the elevating mechanism of the head positioning device for the subject, or individual failure or failure of the elevating switch, etc. Therefore, harm to the subject due to both runaways can be avoided.

The turning arm, which is connected to the rotation shaft of a rotation arm rotation control motor in the rotation drive unit and hangs down from the rotation drive unit, can perform multiple rotations around the rotation axis center, and can take a picture. The rotation drive control means rotates the rotation angle range required for the imaging from the start of the imaging to the end of the imaging with respect to the imaging region or range set by the mode setting means, and during the rotation. Then, the center of rotation of the turning arm is sequentially moved as necessary along a shooting trajectory set in advance by the shooting mode setting in a plane orthogonal to the center of the rotation axis, or By sequentially moving parallel along the center of the rotation axis during rotation or by providing two selecting means, in an X-ray CT imaging apparatus using a cone beam,
Image data acquisition range and reconstructed image range that are affected by the cone beam irradiation angle can be expanded, and the best area suitable for the above-mentioned operative procedure can be selected to provide optimal diagnostic information in one shot. Becomes possible.

Further, the rotation drive control means does not move the rotation center of the revolving arm at the photographing start position at the photographing start position for the photographing site or range set by the photographing mode setting means, for example, After performing a predetermined rotation such as 180 ° or 360 °, the turning and movement are sequentially performed until the photographing completion position, and image data is acquired during this time. By performing the predetermined rotation again without moving the center of rotation and continuously acquiring image data, imaging using an X-ray cone beam with a limited volume, within the same moving range The range of reconstructed images can be greatly increased.

Then, an X-ray source for irradiating an X-ray cone beam opposed to both ends of the support frame so as to sandwich the subject, and image data by the X-ray con-beam transmitted through the subject are acquired. X-ray detector, a chair unit having a head fixing device for positioning a subject prior to photographing, an elevating means for individually moving the head fixing device and the chair unit up and down, and the chair unit The rotary unit has a rotary drive means for turning and moving the camera in the horizontal direction, and the chair portion pivotally supported by a rotary shaft erected by the rotary drive means can perform multiple rotations around the rotary shaft. The rotation drive control means rotates the rotation angle range required for the imaging from the start of the imaging to the end of the imaging with respect to the imaging region or range set by the mode setting means, and during the rotation. The chair is rotating Are sequentially moved in a plane orthogonal to the center of the rotation axis as needed along a photographing trajectory set in advance by a photographing mode setting, and a straight line or a curve of an arbitrary part of the head and neck region or It is possible to capture a CT image and a panoramic CT image of an arbitrary cross section by the combination, and at the same time, to greatly reduce the installation area of the apparatus.

The position correcting means for correcting the position of the center or the starting position of the imaging part which has been positioned in advance is more accurate from two directions orthogonal to the X and Y axes with respect to the imaging part. X-ray projection imaging is performed, images from these two directions are displayed on a monitor, and the monitor is displayed at the center of the displayed imaging target portion or at the respective center positions in the X and Y axis directions to be the imaging start position. It is possible to move the above-mentioned center position cursor at the time of shooting and automatically correct the position of the rotation center of the turning arm to the position where the cursor has moved, more accurately, via the rotation drive control means of the rotation drive unit. I made it.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings in comparison with a conventionally known example. FIG. 1 is a diagram showing a basic principle of a local irradiation X-ray CT imaging method mainly for dental use using a conventionally known cone beam (JP-A-2000-139902). In the figure, an X-ray source 1 and an X-ray detector 2 arranged opposite to a pivot arm (not shown) represent a center position Pa of a local part P for imaging a local part P to be actually imaged. As is apparent from the claims, the known example is configured such that the rotation center of the swing arm is fixed to the center position of a local part to be imaged, which is a part of the subject, and the X-ray generator receives The X-ray image of the local part is two-dimensionally turned by turning the turning arm in an angular range (a range of 360 ° or less) according to the imaging conditions while locally irradiating the X-ray cone beam including only the local part. There is disclosed a local irradiation X-ray CT imaging apparatus configured to generate an arbitrary tomographic plane image of a local site by performing image arithmetic processing on an X-ray projection image generated on an image sensor.

FIGS. 2 (a), 2 (b) and 2 (c) show the basic principle of a technique for obtaining a panoramic X-ray tomographic image of a dental arch according to a conventional method using the above-mentioned local irradiation X-ray CT imaging apparatus. It is shown. In this known example, as is apparent from the claims described above, the center of rotation of the turning arm wraps the trajectory of the ortho-X-ray cone beam necessary to obtain a panoramic image of the dental arch as a part of the subject. While being fixed to the center position of such a virtual local part, the turning arm is rotated by an angle range corresponding to the imaging condition,
By irradiating an X-ray cone beam including only the virtual local part, an X-ray projection image of the dental arch is extracted from the X-ray projection images of the dental arch sequentially generated on the two-dimensional image sensor. By processing the partial X-ray projection image generated by the ortho-X-ray cone beam, two-dimensional X-ray absorption coefficient distribution information of the dental arch is extracted as image information, and a panoramic image of the dental arch is generated. Irradiation X-ray C for generating an arbitrary tomographic image of a local region to be irradiated
T imaging device is disclosed

FIGS. 3 (a) and 3 (b) show the positional relationship between an X-ray source, an X-ray detector, an imaging part, a rotation center, and the like, and a reconstructed image which can be obtained by a cone beam having a limited volume. FIG. 3 is a diagram showing a range. In the figure, in performing CT imaging of a range of an imaging region 3 of a subject, an X-ray source 1 and an X-ray detector 2 disposed opposite to both ends of a turning arm (not shown) rotate the turning arm. The cone beam 4 emitted from the X-ray source 1 passes through the entire subject imaging region 3 while rotating at least 180 ° about the center O (the center of the subject imaging region). Is acquired by the X-ray detector as two-dimensional image data. Therefore, all parts of the imaging region 3 are taken in the X-ray detector as two-dimensional image data of at least 180 ° and stored in the storage device. Image processing such as arithmetic processing is performed on the stored two-dimensional image data by a computer, and a reconstructed image can be generated. In the figure, the range in which the reconstructed image can be obtained at the imaging site 3 is a cylinder having a diameter M × a height M. FIG. 2B shows that a reconstructed image of the imaging region 3 when the rotation center position of the swivel arm is continuously moved along an imaging trajectory to be described later in addition to rotation during imaging is possible. The basic range is shown, and the cross section has a width D × height M × length W of a square or a rectangle inscribed in the aforementioned diameter M. This length depends on the moving distance of the center of rotation of the swing arm.

FIGS. 4 (a) and 4 (b) are diagrams showing the imaging principle of the X-ray CT imaging apparatus of the present invention. In FIG. (A), the fundamental difference from the above-mentioned known technology is that, while using an X-ray cone beam with a limited volume, during imaging, the swing arm is rotated multiple times around its rotation axis, and By moving the center of rotation of the turning arm from time to time along a predetermined imaging trajectory in a plane perpendicular to the rotation axis, the X-ray cone beam includes an area not included in the known example. This is based on a completely new idea of continuously shooting in one shooting. In the figure, an X-ray source 1 and an X-ray detector 2 arranged opposite to a pivot arm (not shown)
In order to actually perform imaging, for example, to image the entire dentition area P, the X-ray source 1 emits a limited range of X-ray cone beams 4. During the shooting, the rotation arm rotates around a center of the rotation axis as a required rotation angle with respect to the shooting range, for example, 1800 ° (5 rotations). The photographing is performed while moving along the photographing trajectory set in advance. During this time,
All parts of the image reconstruction area of the imaged part are sequentially two-dimensionally imaged by X-ray detectors facing each other by 180 ° or more.
It is taken in as a tar. At this time, the number of captured image data to be captured is determined, for example, by the rotation angle of the revolving arm / the moving distance on the capturing orbit by an image capturing signal every 0.9 ° / 0.15 mm, and by 180 ° rotation / 30 mm movement. Image data of 200 shots is stored in the storage device via the X-ray detector 2. 2 obtained in this way
By performing image calculation processing such as back projection by a computer on the dimensional image data, and performing processing such as rearrangement at intervals of 0.15 mm, and for a circular arc portion according to the radius and angle, for example, A panoramic CT reconstructed image of the entire dentition region is generated and displayed on a display device. Further, it is needless to say that a hard copy, each image data, and an image can be stored in a storage device as needed. FIG. 2B shows a state in which the rotation center of the swing arm and the image data capturing range move on a predetermined photographing trajectory from time to time during the photographing.

FIG. 5 will be described in detail later. In order to secure the reconstructed image range as wide as possible, the rotation center axis of the swing arm is not moved at the photographing start position at the time of photographing.
After the image is rotated by 80 ° or 360 °, the image is rotated and moved successively, and again at the photographing completion position, as described above.
By taking a picture with the rotation center fixed at 80 or 360 degrees, the photography area can be effectively increased.

FIG. 6 is a schematic diagram showing a case where a panoramic CT image of the tooth and jaw area is performed.
A diagram showing the progress of the incident direction of a beam cone beam. For example, the imaging start position is set to 0 ° and the center is 900 °. The swivel arm rotates the X-ray source and the X-ray detector that are opposed to each other. This indicates that shooting is performed while rotating about the axis and moving sequentially from a shooting start position to a median position along a shooting trajectory set in advance on a plane orthogonal to the rotation axis.

FIG. 7 shows a panorama C of the entire dentition area.
This represents a case where the dental arch 6 of the subject is accurately positioned on the photographing trajectory 5 set in advance by the photographing mode setting means when performing T photographing by a method described later. (Start origin position) 7 is a position in the X-ray incident angle direction 0 ° of the swivel arm, after which the rotation of the swivel arm and the movement of the center of rotation on the imaging orbit advance, and the X-ray irradiation start position 8 The X-ray incident angle direction is 90
Indicates that the rotation and the movement further proceed, and the X-ray incident angle position at the reconstructed image start position 9 becomes 180 °. In addition, since the median line is bilaterally symmetrical with respect to the line, at the reconstructed image end position 10, the rotation and movement proceed as described above, and the X-ray incident angle position becomes 1440 ° in total, and the X-ray irradiation completion position 11, shooting completion position 1
2 are 1620 ° and 1800 °, respectively. Note that the above numerical values are, of course, not limited to the present numerical values in one embodiment.

As can be easily understood from the figure, for example, the imaging trajectory 5 used when capturing a panoramic CT image of the entire dentition area is equivalent to the virtual dental arch conventionally referred to in panoramic tomography. The rotation angle required for the above-mentioned shooting is
The rotation angle required for panoramic tomography and the necessary range of movement are also determined by the set imaging region and range, and are determined from an X-ray source provided at one end of a turning arm (not shown in the figure). Is irradiated with a vertically long cone beam suitable for panoramic tomography through a conventionally known X-ray aperture (not shown), and after passing through the subject, an image is continuously output to an X-ray detector (not shown) disposed opposite to the X-ray detector. Captured as data. The panning tomography is set by the imaging mode setting means based on the movement of the swivel arm at this time, so that the X-ray source and the X-ray detector arranged oppositely perform panoramic CT imaging of the rotation center of the swivel arm. The rotation drive unit and the rotation drive control means continuously rotate and move the panoramic tomography on the orbit (virtual dental arch) so that the main line of X-rays enters at substantially right angles to the tangential direction to the orbit. Can be easily implemented without any change in the mechanism, and it is a matter of course that the image data thus captured can be subjected to image processing to easily realize a panoramic tomographic image.

FIGS. 8 (a) and 8 (b) show an embodiment of a panoramic X-ray CT imaging apparatus according to the present invention. FIG. 8 (a) is a front view of the appearance, and FIG. In the figure, a rotary drive unit 15 supported on a support frame 14 rotates an X, Y axis table, an X, Y axis control motor therefor, and a rotating arm 16 therein, which will be described later. Components such as a control motor and a slip ring contact for realizing multiple rotations of the swivel arm 16. Swivel arm 16 hanging from rotary drive unit 15
An X-ray source 1 and an X-ray detector 2 are arranged opposite to each other at both ends. The swing arm 16 will be described later.
On its lower surface, a safety switch (1) 31 for preventing object interference
Is provided. The chair 17 for positioning the subject
A conventionally known head positioning device 18 capable of moving up and down and positioning the head of the subject includes a vertical actuator, a horizontal swing positioning mechanism, a front and rear adjustment mechanism, a chin rest, a light beam irradiation means for front and rear positioning, a temporal holding mechanism, and a fixed. It is composed of a main part such as a belt, and can move up and down independently of the chair 17 as shown by an arrow with a vertical actuator. Since the individual mechanisms and operations of the head positioning device 18 are well-known technologies conventionally used in a conventional dental panoramic X-ray imaging device, a cephalometric X-ray imaging device, and the like, a description thereof will be omitted. Further, in addition to the above-described light beam means in the drawing, a median beam irradiation means 19 for designating a median line of a subject (a subject) with a light beam, a front-rear positioning light for designating a front tooth reference position of the subject. A beam irradiating means 21 and a vertical positioning beam irradiating means 20 are provided. These light beam irradiating means are basically conventionally used in a dental area, such as a panoramic X-ray apparatus or a cephalometric X-ray apparatus. In the medical field, detailed description will not be given since various types of CT apparatuses, MRI apparatuses and the like have already been put to practical use. Also, the X-ray detector is based on I. It is needless to say that the present invention is not limited to I, CCD and the like, but includes a two-dimensional sensor such as TFT.

The procedure for actual photographing will be described. First, in order to easily seat the subject (subject) on the chair 17, the head positioning device 18 is moved via the horizontal swing positioning mechanism. After the subject is seated on the chair part 17 by swinging 90 ° in the horizontal direction, the X-ray source 1
The upper and lower positioning beam irradiating means 2 showing an imaging range in the height direction at an imaging part (the center of rotation of the rotation arm) determined by the angle of spread of the X-ray cone beam 4 emitted from the camera.
The height of the chair is adjusted so that the part to be imaged by the subject is located within the vertical width of the light beam emitted from zero.
Next, the head positioning device 18 is moved up and down to adjust the height so that the subject's chin contacts the chin rest. Next, the subject is aligned with the median beam emitted from the median beam irradiating means 19, and the temporal holding is performed as described above. If necessary, the subject's head is fixed with a fixing belt. Next, an imaging part is specified by an imaging mode setting unit (not shown). The X / Y-axis table control motor of the rotary drive unit 15 is positioned by the rotary drive control means at the center of rotation of the rotary arm 16 at the capture start position of the capture path set in advance according to the set capture site or range. .

Next, referring to FIG.
Two light beams 22 and 22 ′ which are irradiated from the X-ray source side and the X-ray detector side so as to overlap on the center line in the X-ray irradiation width direction toward the rotation arm rotation center, and Light beam 2 for confirming tomographic position irradiated orthogonally
At 2 '', it is checked whether or not the imaging start position is at an appropriate position with respect to the actual imaging part of the subject. If the position needs to be corrected, X is set using an operation box (not shown). ,
The position of the Y axis is corrected. 14 (a) and 14 (b) exemplify an embodiment of the position correcting means for more accurate position correction. The position correction means 43 is a standard position where the center of rotation of the swing arm is preset by each mote setting means, or after positioning the subject using the above-described light beam, X-ray fluoroscopy is performed from two directions orthogonal to the X and Y axes, images from these two directions are displayed on a monitor, and the X and Y axes to be used as the center of the displayed imaging target site or the imaging start position. The center position cursor at the time of shooting on the monitor is moved to each center position in the direction, and the rotation center position of the turning arm is automatically positioned at the position where the cursor has moved by the rotation drive control means, so that more accurate The diagnostic information required for can be obtained. Also this front,
It is natural that the density correction is performed at the time of photographing from the side. After the preparation for shooting is completed in this way, the set shooting is performed.

Next, FIG. 10 is a plan view of a rotary drive unit 15 according to an embodiment of the present invention, and FIG. 11 is a side view thereof. , A Y-axis table 23 that moves in the front-rear direction,
An X-axis table 24 that moves in the left-right direction by a shaft control motor, and a rotation control motor 27 for rotating the swivel arm 16 fixed to the X-axis table are connected to the swivel arm 16 via a connecting member 28. Is done. Slip rings 29 and 30 are provided to realize multiple rotations of the swing arm 16. Further, the swing arm 16
On the lower surface of the center of rotation, a plurality of limit switches and a safety switch (1) constituted by a touch panel are provided so as to immediately stop lifting and lowering of the chair unit 17 even if the top of the subject interferes even slightly. 31 are prepared. The circuit of this portion is, of course, a self-closed circuit. 32, 33, 34, 3
5, 36, 37, 38, etc. are various positioning sensors. Since the rotary drive unit 15 is configured in this manner, the swing arm that hangs from the rotary drive unit as described above can perform multiple rotations around the rotation axis center of the rotation control motor, and The rotation drive control means rotates the rotation angle range necessary for the imaging from the start of the imaging to the end of the imaging with respect to the imaging region or range set by the imaging mode setting means, and During the rotation, the center of rotation of the swivel arm is sequentially moved in a plane orthogonal to the center of the rotation axis along the imaging orbit set in advance by the imaging mode setting, and the head and neck region is moved. Any part or range of straight lines or curves,
Alternatively, by retrieving image data of an arbitrary cross section by a combination thereof and performing image processing on the image data, it is possible to obtain a reconstructed image of an arbitrary part or range.

Next, with reference to FIGS. 12 and 13, an embodiment in which a subject interference preventing safety switch is provided between the subject chair 17 and the subject head positioning device 18 will be described. Since the head positioning devices 18 are individually configured to be vertically movable, the lower surface of the head positioning device 18 and the seat surface of the chair 17 may abnormally approach each other depending on the manner of operation. In this case, an accident in which the thighs of the subject are compressed may be considered, so that the position sensors 40 and 40 'are provided between the thighs and the chair 17, and
By configuring the head positioning devices 18 so that they do not approach each other below a certain distance, safety measures against harm due to interference with the subject due to malfunction or the like are considered.

FIGS. 15 and 16 show some embodiments of the plan view of the reconstructed image area of the present invention.
First, in FIG. 15, FIG. 15 (a) shows an image taken by 180 ° or 360 ° using an X-ray cone beam whose irradiation range is the imaging region 3 while fixing the center of rotation about the center of rotation O. If the height is M, a cylinder having a diameter M × a height M is obtained. Figures (b) to (e) are
A case where a panoramic range is continuously photographed using a limited X-ray cone beam whose irradiation range is the photographing range 3 is shown, and the rotation center of the turning arm 16 is centered on the X-ray irradiation start position in the figure. As for the imaging region or range set by the imaging mode setting means, during the period from the start of the imaging to the end of the imaging, the rotation drive control means rotates the rotation angle range necessary for the imaging, and during the rotation, FIG. 3 shows that shooting is performed in a set range while sequentially moving the rotation center of the turning arm 16 along the shooting trajectory 5 set in advance by the shooting mode setting means. As is apparent from the figure, by changing the moving distance per unit rotation speed or the number of rotations per unit moving distance, particularly the D dimension of the range of the reconstructed image is D1 to D4.
It is possible to change as follows.

FIG. 16 shows another embodiment for changing the range of the reconstructed image. FIG. 16 (a) shows a limited X-ray cone beam having the imaging range 3 as the irradiation range. In the case of continuously photographing a panoramic range by using, first, at the photographing start position, the rotating arm is rotated 180 ° or 360 ° with the rotation center position fixed at the same time as the photographing is started. After the photographing, the rotation is continued, and the rotation center position of the revolving arm 16 is sequentially moved along the photographing trajectory set as described above with reference to FIG. Similarly, at the photographing end position, the reconstructed image range can be changed by performing the photographing by rotating the swivel arm 180 ° or 360 ° with the rotation center rotation center position fixed. This is particularly effective when performing continuous panoramic shooting within a limited operating range. Further, it is also possible to continuously change the moving distance for the unit rotation speed or the rotation speed for the unit moving distance during photographing.

FIG. 17 shows an example of a modified embodiment according to the present invention. In the figure, the subject is positioned with respect to an X-ray source 1 ′ and an X-ray detector 2 ′, which are arranged opposite to both ends of a support frame (2) 41 without rotating so as to sandwich the subject. Head fixing part 42 for positioning prior to photographing
The chair portion 43 having a head fixing portion and a lifting means for individually moving the chair portion up and down. Also, the head fixing part is 90 degrees horizontally so that the subject can easily enter and exit the chair.
で き Swings are taken into consideration and the position of the subject is considered. A chair 43 connected to a rotation shaft of a rotation control motor erected by a rotation drive means 44 disposed on the floor surface is movable in the rotation drive means 44 with respect to a horizontal plane, X, Y.
While the subject positioned by the axis table, the respective control motors for movement, and further the rotation control motor by the head fixing device and the chair unit in the same procedure as described above, is in the photographing mode, the photographing mode setting means is provided. The camera rotates in a necessary rotation range along a shooting trajectory set in advance, and performs shooting while sequentially moving in a necessary range.

FIG. 18 is an embodiment of a block diagram according to the present invention. In the figure, the X-ray detector is composed of II and a camera.
Changes to T) and the like are of course possible. In this case, a power supply and a relay box related to the CCD camera are not required.

[0042]

Since the present invention is configured as described above, it has the following effects.

While rotating the X-ray source and the X-ray detector opposed to the turning arm about the rotation center axis, the rotation center position is sequentially moved and scanned on a plane orthogonal to the rotation center axis. Any area that could not be imaged in the past due to the limited range not included in the X-ray cone beam, for example, fixed in the center of rotation of the entire tooth area, right molars to central incisors, maxillary sinus area, ear canal, etc. Can be imaged, and a three-dimensional CT image can be reconstructed as needed. In addition, since conventional panoramic tomography can be easily performed, it is possible to perform imaging for obtaining sufficient diagnostic information suitable for a surgical procedure each time, thereby increasing persuasiveness to a patient.

The position of the rotation center of the revolving arm, which is capable of making multiple rotations about the rotation axis hanging from the rotary drive unit, is set in advance according to the imaging region or range set by the imaging mode setting means. For the moving distance on the shooting orbit, the rotation angle range necessary for the shooting by the rotation drive control means the number of rotations per unit distance or
By changing the moving distance per rotation, the dimension in the depth direction (dimension D) can be changed in accordance with the purpose of photographing, and thus the range of the reconstructed image can be changed.

The swivel arm, which can move on the trajectory and multiple rotations hanging down from the rotary drive unit, has a plurality of limit switches and a touch panel on its lower surface. When an object interferes with an arbitrary part of the object with a force of several tens of grams, the movement of the chair lifting device is stopped immediately, so by installing such a safety switch to prevent subject interference In order to prevent harm to the subject due to runaway of the elevation function due to damage to the elevation switch of the subject chair or the like, care is taken.

A safety switch for preventing interference between the subject and the head positioning device for the subject is provided between the chair for the subject and the head positioning device for the subject. By providing a means for keeping the following, the run-down function of the elevating function due to damage to the elevating switch of the subject chair, or failure of the elevating mechanism of the subject head positioning device or the elevating switch, etc. Care is taken to prevent harm to the subject due to runaway or both.

Then, the revolving arm, which is suspended from the rotary drive unit and is capable of multiple rotations, is used to move the imaging part or range set by the imaging mode setting means from the start of the imaging to the end of the imaging. During the rotation, the rotation drive control means rotates the rotation angle range required for the photographing, and during the rotation, the rotation center of the turning arm is moved along the photographing trajectory set in advance by the photographing mode setting. Two means for selecting whether to sequentially move as necessary in a plane orthogonal to the center of the rotation axis or to move sequentially in parallel along the center of the rotation axis during rotation of the swing arm Thus, in a dental X-ray CT imaging apparatus using a cone beam, an image data acquisition range and reconstruction depending on the irradiation angle of the cone beam in the body axis direction of the subject or in a plane direction perpendicular to the body axis. Further to enlarge the image area, select the best area suitable for the above-described operative procedures, the possibility of providing the best diagnostic information becomes large in one shot.

Then, the rotation drive control means does not move the rotation center of the revolving arm at the photographing start position at the photographing start position, for example, at 180 ° with respect to the photographing region or range set by the photographing mode setting means. After performing a predetermined rotation such as ゜ or 360 °, the rotation and movement are sequentially performed until the photographing completion position, and image data is acquired during this time. By performing the above-mentioned predetermined rotation again without moving the center and continuously acquiring image data, the imaging using the X-ray cone beam of a limited volume can be performed again within the same moving range. It is possible to further increase the constituent image range, which is convenient when a larger reconstructed image range is required within a limited moving range. .

Then, an X-ray source for irradiating an X-ray cone beam opposed to both ends of the supporting frame so as to sandwich the subject, and image data of the X-ray con-beam transmitted through the subject are acquired. X-ray detector, a chair unit having a head fixing device for positioning a subject prior to photographing, an elevating means for individually moving the head fixing device and the chair unit up and down, and the chair unit The rotary unit has a rotary drive means for turning and moving the camera in the horizontal direction, and the chair portion pivotally supported by a rotary shaft erected by the rotary drive means can perform multiple rotations around the rotary shaft. The rotation drive control means rotates the rotation angle range required for the imaging from the start of the imaging to the end of the imaging with respect to the imaging region or range set by the mode setting means, and during the rotation. The chair is rotating While moving sequentially along a photographing trajectory set in advance by the photographing mode setting in a plane orthogonal to the center of the rotation axis, a straight line or a curve of an arbitrary part of the head and neck region, or A general practitioner who is said to be able to take a CT image of an arbitrary cross section and a panoramic CT image by a combination thereof, thereby greatly reducing the installation area of the apparatus and having a relatively small installation space. It becomes easy to make the model a purchase target.

Further, in order to accurately correct the position, the position correcting means performs X-ray fluoroscopy on the imaging region from two directions orthogonal to the X and Y axes, and monitors images from these two directions. X, Y to be displayed at the top and to be the center of imaging of the displayed imaging target portion or the imaging start position
The photographing center position cursor on the monitor is moved to each center position in the axial direction, and the rotation center position of the turning arm is automatically moved to the position where the cursor has moved, via the rotation drive control means of the rotation drive unit. More accurate positioning becomes possible, and necessary diagnostic information can be obtained accurately without being affected by the skill of the operator.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the principle of imaging of a local irradiation X-ray CT imaging method.

FIG. 2 is an explanatory view of a photographing principle regarding a method of obtaining a panoramic image of a dental arch according to a conventional method using a local irradiation X-ray CT photographing method.

FIG. 3 is a schematic diagram showing a positional relationship between respective parts and a reconstructed image range of the CT imaging method according to the present invention.

FIG. 4 is an explanatory view of the imaging principle of the panoramic X-ray CT imaging method according to the present invention.

FIG. 5 is an explanatory diagram of a case where a panning X-ray CT image is taken by fixing a rotation center position at a shooting start position and performing 360 ° rotation image shooting, and then successively moving and rotating along a shooting trajectory during shooting;

FIG. 6 is an explanatory diagram showing that an X-ray incident angle progresses with movement of a rotation center when performing panoramic X-ray CT imaging of a tooth jaw region.

FIG. 7 shows a panoramic X-ray CT of a tooth and jaw region of a subject.
Illustration of shooting range when shooting

FIG. 8 is an external view of a panoramic X-ray CT imaging apparatus according to the present invention, wherein (a) is a front view, (b) is a side view, and (c) is a plan view.

FIG. 9 is an explanatory diagram showing an example of installation of a safety switch for preventing subject interference on the lower surface of a swing arm.

10 is a detailed plan view of a rotary drive unit of the panoramic X-ray CT imaging apparatus according to the present invention shown in FIG. 8;

11 is a detailed side view of the rotary drive unit of the panoramic X-ray CT imaging apparatus according to the present invention shown in FIG.

FIG. 12 is an explanatory diagram showing an installation example in which a subject interference prevention switch is provided between a chair and a head positioning device.

FIG. 13 is an explanatory view showing an installation example in which a subject interference prevention switch is provided between a chair and a head positioning device.

FIG. 14 is an explanatory diagram of a position correcting unit of the panoramic X-ray CT imaging apparatus according to the present invention.

FIG. 15 is a diagram illustrating a change in a reconstructed image range of the panoramic X-ray CT imaging apparatus according to the present invention.

FIG. 16 is an explanatory diagram showing another example of a change in the reconstructed image range of the panoramic X-ray CT imaging apparatus according to the present invention.

FIG. 17 is an external view of another embodiment of a panoramic X-ray CT imaging apparatus according to the present invention.

FIG. 18 is a block diagram of an embodiment of a panoramic X-ray CT imaging apparatus according to the present invention.

[Explanation of symbols]

1. X-ray source 17. Chair part 2. X-ray detector 18. Head positioning device 3. Imaging part (imaging range) 3. Y-axis table Cone beam 24. X axis table 5. Shooting orbit 25. 5. Y-axis control motor Dental arch 26. X-axis control motor 7. Shooting start position 27. Rotation control motor 12. Imaging completion position 31. Safety switch (1) 13. Reconstructed image range 40. 13. Safety switch (2) Support frame 41. 14. Support frame (2) Rotation drive unit 42. Rotation drive means 16. Swivel arm 43. Position correction means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeshi Yamamoto 1-338 Enmyouji Wakiyama, Oyamazaki-cho, Otonun-gun, Kyoto (72) Inventor Fumiaki Akagi 3-7-18 Osumigaoka, Kyotanabe-shi, Kyoto F-term (reference) 4C093 AA10 AA22 CA33 CA37 DA05 FA13 FA33 FA44 FA55 5B057 AA09 BA03 BA24 CA02 CA08 CA12 CA16 CB02 CB08 CB12 CB13 CB16 CE10

Claims (10)

[Claims] 1. A chair for a subject, a positioning device for a head for a subject, a rotary drive unit provided above the chair, and a direct or indirect rotary shaft of a rotation arm rotation control motor in the rotary drive unit. An X-ray source for irradiating a subject with a limited range of comb beams at one end of a rotating arm that is connected to the screen, and an X-ray for detecting X-rays transmitted through the subject at the other end. Detectors are opposed to each other, and the rotating arm rotates to perform CT imaging of the head and neck of the subject.
In a so-called X-ray CT imaging apparatus, the turning arm that is directly or indirectly connected to the rotation axis of a rotation arm rotation control motor in the rotation drive unit and that hangs down from the rotation drive unit has the rotation axis center. Multi-rotation is possible as a rotation center, and it is necessary for the photographing by the rotation drive control means from the start of the photographing to the end of the photographing for the photographing part or range set by the photographing mode setting means. Within the rotation angle range, and during the rotation, the center of rotation of the turning arm is sequentially moved in a plane orthogonal to the center of the rotation axis along a shooting orbit set in advance by the shooting mode setting. And captures image data of an arbitrary section in a head and neck region or an arbitrary cross section by a straight line or a curve in a range, or a combination thereof, and performs image processing on the image data Any site or panoramic X-ray, characterized in that to obtain a reconstructed image of the range C by the
T imaging device. 2. Directly or indirectly connected to the rotation shaft of a rotation arm rotation control motor in the rotation drive unit,
The rotating arm hanging from the rotary drive unit can rotate multiple times around the center of the rotation axis, and the rotation angle required for the image capturing depending on the image capturing region or range set by the image capturing mode setting means. While rotating the range, if necessary, along the imaging trajectory set in advance, the rotation center of the swing arm, with respect to the movement distance when sequentially moving in a plane orthogonal to the rotation axis center, 2. The panorama according to claim 1, wherein a means for changing a rotation angle range necessary for the photographing as a number of rotations per unit distance or a movement distance per rotation is added by the rotation drive control means. X-ray CT imaging device. 3. Directly or indirectly connected to a rotation shaft of a rotation arm rotation control motor in the rotation drive unit,
The rotating arm hanging from the rotary drive unit can rotate multiple times around the center of the rotation axis, and the rotation angle required for the image capturing depending on the image capturing region or range set by the image capturing mode setting means. While rotating the range, if necessary, along the imaging trajectory set in advance, the rotation center of the swing arm, with respect to the movement distance when sequentially moving in a plane orthogonal to the rotation axis center, The rotation drive control means sets the rotation angle range necessary for the photographing as the number of rotations per unit distance or the movement distance per rotation, and is programmed as an algorithm for determining the amount of change. Item 4. The panoramic X-ray CT imaging apparatus according to Item 1. 4. Directly or indirectly connected to a rotation shaft of a rotation arm rotation control motor in the rotation drive unit,
The rotating arm hanging from the rotary drive unit can rotate multiple times around the center of the rotation axis, and the rotation angle required for the image capturing depending on the image capturing region or range set by the image capturing mode setting means. While rotating the range, if necessary, along the imaging trajectory set in advance, the rotation center of the swing arm, with respect to the movement distance when sequentially moving in a plane orthogonal to the rotation axis center, The rotation drive control means inputs a rotation amount range necessary for the photographing as a number of rotations per unit distance or a movement amount per rotation as a numerical value, and changes the rotation amount corresponding to the input value. 2. The panorama X according to claim 1,
X-ray CT apparatus. 5. The rotating arm, which can rotate multiple times around the center of the rotating shaft hanging from a rotary drive unit, is provided with a safety switch on its lower surface for preventing object interference. Item 7. A panoramic X-ray CT imaging apparatus according to any one of Items 1 to 4. 6. A subject safety switch for preventing interference between the chair and the head positioning device for the subject is provided between the chair and the head positioning device for the subject. 6. The panoramic X-ray CT imaging apparatus according to claim 1, wherein the panoramic X-ray CT imaging apparatus is kept away from. 7. A chair for a subject, a head positioning device for the subject, and a rotary drive unit provided above the chair.
An X-ray source for irradiating a cone beam to one end of a turning arm connected directly or indirectly to a rotation axis of a turning arm rotation control motor in the rotary drive unit, and a subject to the other end. In a so-called X-ray CT imaging apparatus in which an X-ray detector for detecting transmitted X-rays is opposed to each other, and the swiveling arm is rotated to perform CT imaging of the head and neck of a subject, a so-called X-ray CT imaging apparatus includes a rotary drive unit. The swing arm, which is directly or indirectly connected to the rotation axis of the rotation arm rotation control motor and hangs down from the rotation drive unit, is capable of making multiple rotations around the rotation axis center, and a photographing mode setting means. For the imaging region or range set by, from the start of the imaging to the end of the imaging, the rotation drive control unit rotates the rotation angle range required for the imaging, and, if necessary, rotation Then, the center of rotation of the turning arm is sequentially moved as necessary along a shooting trajectory set in advance by the shooting mode setting in a plane orthogonal to the center of the rotation axis, or 7. The panoramic X-ray CT imaging apparatus according to claim 2, wherein the panoramic X-ray CT imaging apparatus is configured to sequentially move in parallel along the center of the rotation axis during rotation or to have two selecting means. 8. The image forming apparatus according to claim 1, wherein the rotation drive control unit does not move the rotation center of the revolving arm at a shooting start position with respect to a shooting region or a range set by the shooting mode setting unit. After performing a predetermined rotation such as 180 ° or 360 °, the rotation and the movement along the photographing trajectory are sequentially performed, and the image data is fetched during the rotation. 8. The panoramic X-ray CT imaging apparatus according to claim 1, wherein the predetermined rotation is performed again without moving the center of rotation, and the image data is continuously acquired. 9. An X-ray for irradiating an X-ray cone beam disposed opposite to both ends of a support frame so as to sandwich a subject.
A chair having a radiation source, an X-ray detector for capturing image data from the X-ray cone beam transmitted through the subject, and a head fixing device for positioning the subject prior to imaging; It has lifting and lowering means for individually raising and lowering the apparatus and the chair part, and rotation driving means for turning and moving the chair part in the horizontal direction. The rotation driving means is connected to the rotation axis of the chair rotation control motor of the rotation driving means. Chair part
It is possible to make multiple rotations around the center of the rotation axis, and for the imaging region or range set by the imaging mode setting means, from the start of the imaging to the end of the imaging, by the rotation drive control means. The rotation angle range necessary for the photographing is rotated, and the rotation center of the chair during the rotation is orthogonal to the rotation axis center as necessary along a photographing trajectory set in advance by the photographing mode setting. While sequentially moving in the plane to be performed, image data of an arbitrary cross section by a straight line or a curve or a combination thereof of an arbitrary part of the head and neck region is captured, and an arbitrary part or range is obtained by performing image processing on this image data. A panoramic X-ray CT imaging apparatus characterized by obtaining a reconstructed image of 10. A center position or a photographing start position of a photographing part, which is preliminarily positioned by the rotation drive control means of the rotary drive unit with respect to the photographing part or range set by the photographing mode setting means, Further, in order to accurately correct the position, X-ray fluoroscopy was performed on the imaging region from two directions orthogonal to the X and Y axes, and images from these two directions were displayed on a monitor and displayed. X, which you want to be the center of imaging of the imaging target site or the imaging start position
The center position cursor at the time of shooting on the monitor is moved to each center position in the Y-axis direction, and the rotation center position of the turning arm is automatically moved to the position where the cursor is moved by the rotation drive control means of the rotation drive unit. 10. A panoramic X-ray CT imaging apparatus according to claim 1, further comprising a position correcting means capable of correcting the position of the panoramic X-ray.