JP2007143948A - Cone beam x-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cone beam X-ray CT apparatus which facilitates CT imaging and panoramic imaging without requiring a complicated mechanism and the control. <P>SOLUTION: The cone beam X-ray CT apparatus is equipped with a motor 14 driving a rotary arm 2 in either a CT imaging mode or a panoramic imaging mode which is set and an electromagnetic brake 9a, 9b which is provided on a path to keep the path described by the rotary arm 2 as a result of driving the rotary arm 2 by the motor 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray cone beam CT imaging apparatus that irradiates a part of a subject with an X-ray cone beam and obtains an arbitrary CT tomographic image and panoramic image of that part, and is particularly suitable for imaging a dentofacial region. The present invention relates to an X-ray cone beam CT imaging device.

Dental X-ray panoramic imaging is a tomography that shows the state of the dentition and its surrounding tissues and bones with a single image by continuously irradiating a slit-shaped X-ray beam along the dentition and performing curved tomography The image is displayed in a panoramic form.
In a conventional panoramic imaging apparatus, a revolving arm carrying an X-ray generation device and a two-dimensional X-ray detection device facing each other with a subject interposed therebetween is supported by, for example, a front / rear / left / right moving unit and a rotating unit, and a dental arch around the subject It moved in a complicated orbit that approximated the shape.
As a specific example, Patent Document 1 discloses performing special local CT imaging and panoramic imaging along a dentition.
JP 2002-219127 A

  However, the above-mentioned Patent Document 1 is a combination of an XY table mechanism that performs linear motion in two directions perpendicular to each other on the swivel plane of the arm, and a rotation mechanism that adjusts the rotation angle of the arm according to the dentition position. The table mechanism aligns the position of the imaging center with respect to the dentition, and the rotation mechanism controls the direction of the slit X-ray beam irradiated to the dentition, so combine them with at least three independent drive mechanisms. However, since complicated control is required, no consideration has been given to simplification of the mechanism.

  An object of the present invention is to provide a cone beam X-ray CT apparatus that can easily perform CT imaging and panoramic imaging without requiring a complicated mechanism and control.

  The above-mentioned purpose is to detect two-dimensionally the X-ray generation means that generates X-rays and the transmitted X-rays of the subject out of the X-rays that are arranged opposite to the X-ray generation means and irradiated from the X-ray generation means The X-ray detecting means, the rotating means for holding the X-ray generating means and the X-ray detecting means and rotating around the subject, and the fluoroscopic X-rays rotated by the rotating means in a plurality of directions. In a cone beam X-ray CT apparatus provided with an image processing means for creating a tomographic image of a subject, setting to set at least one of a rotating orbit and an elliptical orbit by a CT imaging mode or a panoramic imaging mode And a driving means for driving the rotating means in the photographing mode set by the setting means, and a driving path set by the rotating means as a result of being driven by the driving means. Is accomplished by comprising a fixing means that.

  According to the present invention, CT imaging and panoramic imaging can be performed with a simple mechanism.

Embodiments of the present invention will be described below with reference to the drawings.
In the embodiment of the present invention, an arm type X-ray cone beam CT imaging apparatus having a structure in which a rotating part of a turning arm as shown in FIG. 1 is installed on the floor side will be described as an example. FIG. 1 is a side view (partially sectional view) showing the configuration of the entire apparatus of the present invention, and FIG. 2 is a front view. A top view of the rotating mechanism is shown in FIG.

First, the apparatus is composed of a fixed portion 1a fixed to the floor surface, a shaft-like support structure portion 1b, and a space 1c placed on the upper portion thereof for installing the seat portion of the subject 7.
The total load of the fixed portion of the device is supported by the shaft-like support structure portion 1b, and the device is fixed to the floor via the fixed portion 1a. The shaft-like support structure 1b is hollow, and the power cable and the signal cable are inserted into and removed from the power supply, control device, and image processing device outside the scanner through this hollow portion, and power supply or signal exchange is performed. .

  The rotation mechanism of the swivel arm 2 is configured as follows. Around the shaft-like support structure 1b, the X-ray generation device 3a and the diaphragm device 3b and the X-ray detection device 4 which are opposed to each other with the subject 7 interposed therebetween are held by the support columns 2a and 2b, respectively. The rotating unit 2 that rotates around the subject 7 is installed in a state that can rotate horizontally with respect to the fixed base 1 via the rotating mechanism unit shown in FIG.

The support mechanism of the rotating unit 2 is composed of two stages, a circular track part and an elliptic track part.
First, the four slide blocks 12c in the circular track portion are fixed to a fixed portion 1a fixed to the floor surface, and the rail 12a side rotates with respect to the floor.

  The rail 12b of the elliptical track part is fixed on the same mounting plate 19 as the rail 12a of the circular track part, and the four slide blocks 12d of the elliptical track part are fixed to the turning arm 2. Of the four slide blocks 12d, the two elliptical track slide blocks on the X-ray detection device 4 side are fixed to the swivel arm 2 via the bearing 21 so that the angle with respect to the rail 12b can be changed according to the position of the elliptical track. Is done. The two elliptical orbit slide blocks on the opposite X-ray generator 3 side can move parallel to the bearing 21 and the X-ray cone beam axis 3b so that the angle with respect to the rail 12b can be changed according to the position of the elliptical orbit. It is fixed to the swivel arm 2 via a straight slide guide 17. Therefore, the X-ray detection device 4 makes a turning motion while maintaining a certain distance with respect to the elliptical track rail 12b, and the X-ray generation device 3a slides from the elliptical track 12b and changes its position accordingly. As a result, for the dentition whose size coincides with the locus (virtual dentition) drawn by one point on the X-ray beam axis equidistant from the elliptical track rail 12b, the enlargement ratio is constant and along the dentition A panoramic tomographic image can be taken with only the part sharp and the other part enlarged and dispersed.

  The incident direction of the X-ray cone beam with respect to the dentition and the shape of the virtual dentition trajectory can be adjusted by changing the interval and position of the elliptical orbit slide block 12d2 on the X-ray detector side. Although not shown, if a mechanism for changing the position of these slide blocks 12d with respect to the swivel arm 2 is provided in FIG. 3, a function with a constant magnification during panoramic shooting can be easily realized.

  The simplest method is to change the angle of the two elliptical orbit slide blocks on the X-ray detector side with respect to the rail according to the position of the elliptical orbit as well as the two elliptical orbit slide blocks on the X-ray generator 3 side. Is fixed to the swivel arm 2 through a bearing 21 and a linear slide guide 17 movable in parallel with the X-ray cone beam axis. A drive unit that slides and a position detection unit may be provided to control the position.

The rotation drive unit is configured as follows. In the subject seat installation space 1a, a motor 14 to which a timing belt pulley 15a is attached is installed, and with respect to the timing pulley 15b attached via a bearing around the shaft-like support structure 1b on the fixed side The rotation is driven via the timing belt 16. The rotational driving force is transmitted to the rotational driving link 18 provided on the opposite side of the timing belt. Since the link 18 and the swivel arm 2 are connected by a linear slide guide 17, even if the center position of the swivel arm 2 and the rotation drive unit changes due to the elliptical orbit, the slide guide on the link moves to drive the rotation. Force is transmitted smoothly to the swivel arm.
In addition, electromagnetic brakes 9a and 9b are incorporated in the rotation mechanisms of the circular and elliptical tracks as fixing means for fixing the respective rotational positions.

On the other hand, the head of the subject 7 is positioned and fixed by the head fixing device 6 as in the conventional device.
In addition, in order to make the height of the imaging region of the subject 7 coincide with the imaging area of the apparatus, the height of the subject with the subject 7 seated in the seat portion installation space 1c of the subject 7 A chair 8 that can adjust the height is installed.
Furthermore, around the subject 7, guards 13a and 13b are provided for preventing the subject's legs and parts of the body from coming into contact with the rotating part 2 of the apparatus.

  First, whether to perform CT imaging or panoramic imaging is set for the subject. According to the set imaging mode, the subject of the subject 7 is irradiated with the X-ray cone beam 3b by a computer program, and an arbitrary CT tomographic image and panoramic image of that portion are acquired. Image data collected from the two-dimensional X-ray detection device 4 is sent to an image processing device installed in an operation room away from the imaging room in which the imaging device is installed, and is subjected to arithmetic processing. Alternatively, it is reconstructed as a three-dimensional stereoscopic image and displayed on the image display device. Since the configuration of these image collection / reconstruction means is the same as that of the conventional apparatus, detailed description is omitted and not shown.

Next, the panorama shooting procedure will be described with reference to FIG.
First, the position of the subject 7 in the front-rear and left-right directions is adjusted as appropriate to adjust the dentition position to the optimum position, and the head is fixed to the head fixing device 6. A slit beam stop for panoramic photography is selected by the stop device 3c.
The circular orbit is fixed by the circular orbit-side electromagnetic brake 9a and the elliptical orbit-side brake 9b is released, thereby taking an image with the X-ray slit beam while rotating the turning arm only by the elliptic orbit.

  As described above, the enlargement ratio is constant for the dentition whose size coincides with the locus (virtual dentition) drawn by one point on the X-ray beam axis equidistant from the elliptical rail 12b according to the elliptical trajectory. It is possible to capture a panoramic tomographic image in which only the portion along the dentition is sharp and the other portion is enlarged and dispersed.

Next, a normal local CT imaging procedure will be described with reference to FIG.
Similar to the panoramic radiography, the position of the subject 7 in the front-rear and left-right directions is adjusted as appropriate to adjust the dentition position to the optimum position, and the head is fixed to the head fixing device 9.
A cone beam aperture for CT imaging is selected by the aperture device 3c.
The ellipsoidal track is fixed by the electromagnetic brake 9b, and the circular track side brake 9a is released to perform the CT imaging by rotating the turning arm only by the circular track. Since the elliptical track is fixed on the swivel arm side, it rotates on the circular track with the swivel arm.

In addition, a procedure for CT imaging by offset scanning will be described with reference to FIG.
As in the case of CT imaging, the position of the subject 7 in the front-rear and left-right directions is adjusted as appropriate to adjust the dentition position to the optimum position, and the head is fixed to the head fixing device 9.
A cone beam aperture for CT imaging is selected by the aperture device 3c.
First, the circular orbit is fixed by the electromagnetic brake 9a and the elliptical orbit side brake 9b is released, so that the turning arm rotates only by the elliptical orbit, and the rotation center position of the turning arm is moved to the required offset position.

Next, the ellipsoidal trajectory is fixed by the electromagnetic brake 9b, and the circular trajectory side brake 9a is released to perform the CT imaging by rotating the swivel arm only by the circular trajectory.
Since the rotation center of the swivel arm is offset by the movement on the elliptical orbit, it is possible to capture a CT image of a region extending in the lateral direction as compared with the case of normal CT imaging.

  If CT imaging is performed with a larger offset amount, CT imaging of a donut-shaped space is also possible. For example, CT imaging of only the part along the dentition, or tangential CT imaging of the part along the skull (such as the temporomandibular joint) without irradiating brain tissue with X-rays when applied to the head Is possible.

According to the embodiment, in a dental X-ray cone beam CT imaging apparatus, panoramic imaging, CT imaging, and offset CT imaging can be easily performed by a single rotation driving device. Furthermore, the control of the mechanism is simplified.
Also, by using slide guides as circular and elliptical orbits, it becomes easier to support the load of the swivel arm, and it is easy to suppress swivel arm deformation due to the load, thus simplifying the structure of the swivel arm and reducing the weight of the device Can be

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view (partially sectional view) showing a configuration of an entire apparatus of the present invention. 1 is a front view (partially sectional view) showing a configuration of an entire apparatus of the present invention. The top view which shows a rotation mechanism part. Explanatory drawing which shows the direction of the X-ray slit beam with respect to a dental arch at the time of panoramic photography. Explanatory drawing which shows the direction of the X-ray cone beam with respect to a dental arch at the time of local CT imaging | photography. Explanatory drawing which shows the direction of the X-ray cone beam with respect to a dental arch at the time of offset CT imaging | photography.

Explanation of symbols

  1a Device fixing part, 1b Shaft-like structure part, 1c Patient seat installation space, 2 Swivel arm, 2a X-ray generator column, 2b X-ray detector column, 3a X-ray generator, 3b X-ray cone beam , 3c Aperture device, 4 Two-dimensional X-ray detection device, 6 Head fixing device, 7 Subject, 7a Imaging area, 8 Chair, 8a Chair vertical movement mechanism, 9a Circular track electromagnetic brake, 9b Elliptical track electromagnetic brake 10a circular track, 10b elliptical track, 11 dental arch, 12a circular track slide rail, 12b elliptical track slide rail, 12c circular track slide block, 12d elliptical track slide block, 13a, 13b guard, 14 motor, 15a, 15b timing pulley , 16 Timing belt, 17 Linear slide guide, 18 Drive link, 19 Rail mounting plate, 20 Timing pulley bearing, 21 Slide guide bearing

Claims (4)

X-ray generation means for generating X-rays;
X-ray detection means for two-dimensionally detecting transmitted X-rays of the subject out of X-rays that are disposed opposite to the X-ray generation means and irradiated from the X-ray generation means;
A rotating means for holding the X-ray generating means and the X-ray detecting means and rotating around the subject;
Image processing means for creating a tomographic image of the subject by fluoroscopic X-rays in a plurality of directions rotated by the rotating means;
In a cone beam X-ray CT apparatus equipped with
Setting means for setting the rotating means and at least one of a circular or elliptical orbit according to a CT or panoramic imaging mode;
Driving means for driving the rotating means according to the photographing mode set by the setting means;
A cone beam X-ray CT apparatus comprising: fixing means provided on the orbit for holding the orbit drawn by the rotating means as a result of being driven by the driving means.   2. The cone beam X-ray CT apparatus according to claim 1, wherein the driving means rotationally drives the circular or elliptical orbit with a single driving unit.   The driving means substantially matches the size of the virtual dentition drawn by the trajectory with respect to the dentition having different sizes in the panoramic imaging mode, and the X-ray generation means and the X-ray detection means The rotation means for holding the X-ray generation means and the X-ray detection means is variably driven with respect to the elliptical trajectory so as to keep the geometric magnification determined by the positional relationship constant. Item 3. The cone beam X-ray CT apparatus according to any one of Items 1 and 2.   The driving means fixes the X-ray cone beam from the center of rotation of the circular orbit by fixing the position of the rotating means on the elliptical orbit while fixing the position and rotating the rotating means on the circular orbit. 4. The cone beam X-ray CT apparatus according to claim 1, wherein the cone beam X-ray CT apparatus is driven so as to perform offset imaging by shifting a central axis of the X-ray CT.

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