JPH0566129B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an X-ray temporomandibular joint imaging system using an upward head-side imaging method typified by the Schuler method among X-ray temporomandibular joint imaging methods. It is.

In general, factors that impede the diagnostic accuracy of X-ray imaging for abnormalities in temporomandibular joint function include: first, the temporomandibular joint is located in an anatomically complex position corresponding to the glenoid fossa;
In front of it is the articular tubercle with thick cortical bone, behind it is the mastoid process with the external auditory canal and the mastoid honeycomb, which is an air-containing sinus, and further medially is the thick bony tuberosity that includes the oblique platform of the sphenoid bone. Due to the presence of the skull base, overlap with other anatomical forms cannot be avoided when photographing. Second, the bone morphology of the temporomandibular joint has marked individual differences (individual differences), and at the same time, even within the same individual (same patient), there are left-right differences in the horizontal and vertical angles relative to the long axis of the mandibular condyle in the horizontal and vertical directions. This is also remarkable. Third, the soft tissues that make up the temporomandibular joints are constantly being remodeled, making it difficult to determine whether they are normal or abnormal. Furthermore, fourthly, in the temporomandibular joint region, it is difficult to find a reference point within the bone for measurement because there are individual differences in bone morphology, left-right differences, and remodeling. etc. are listed. Based on these points, various temporomandibular joint imaging methods have been proposed since then, but the most commonly used method today is the head-side upward imaging method, and the most representative one is Schula. The name law is known. The present applicant previously published an improved version of the apparatus for performing the above-mentioned Schuller photography method in Japanese Patent Application Laid-Open No.
An application was filed for a "temporomandibular joint X-ray imaging device" as shown in Publication No. 114133. The device is configured to swing and invert the X-ray source above the patient's head so that the left and right temporomandibular joints can be continuously imaged using a single X-ray source without changing the patient's orientation. This configuration allows patient orientation.
The drawback of conventional devices is that the left and right temporomandibular joints have to be photographed by changing the angle by 180 degrees, which requires time and effort to adjust the positioning each time the direction is changed, and furthermore, differences in left and right positioning tend to occur, reducing diagnostic accuracy. This solved the problem. As described above, the above-mentioned device is superior to conventional devices in terms of reproducibility, operability, cost, and stability of image quality, and is greatly useful for improving diagnostic accuracy. However, in recent years, the diagnostic accuracy of temporomandibular joint imaging has become increasingly demanding, and even in the above-mentioned equipment, the X-ray incident angle of the X-ray source is the same bilaterally symmetrical angle, so the above-mentioned factors inhibiting diagnostic accuracy The second term, that is, the left-right difference in the horizontal and vertical angles with respect to the long axis (horizontal and vertical directions) of the mandibular condyle in the same patient leads to a left-right deviation in the X-ray incident angle of the above device to the same patient, which reduces diagnostic accuracy. This is the current situation that has become a problem.

This invention was made in view of the above-mentioned current situation, and eliminates the drawbacks and problems of the conventional temporomandibular joint imaging device and the device disclosed in the above publication, and provides a high degree of diagnostic accuracy as well as excellent reproducibility and operability. The aim is to provide a convenient device. That is, it has one or two X-ray sources, and the
The line incidence angle is set at a predetermined depression angle and horizontal deviation angle with respect to the reference line connecting both external auditory foramina, and the device attempts to continuously image the left and right temporomandibular joints of the subject without changing their orientation. The left and right eigenvalues of the depression angle and horizontal declination angle measured by photographing the examiner's mandible from the body axis and frontal directions, as well as the left and right eigenvalues of the intersection position of the long axis of the mandibular condyle with respect to the reference line, as personal data. an eigenvalue storage means for storing eigenvalues, and a focal position of the X-ray source at the time of imaging and an
An X-ray device characterized by comprising an X-ray incident angle setting means for outputting a control signal for individually setting the right and left radiation incident angles, and an X-ray source driving means for moving the X-ray source in accordance with the control signal. This is related to a linear temporomandibular joint imaging device.

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the mandible of the human head, which is directly related to the apparatus of the embodiment, will be explained with reference to the drawings. FIG. 1 is a plan view of the subject's mandible projected from the body axis direction, and FIG. 2 is a front view of the mandible projected from the front. In Fig. 1, the long axis 2 of the mandibular condyle of the mandible 1,
2' and a reference line 3 shown by a dotted line, that is, a straight line connecting both external auditory foramina (not shown) or a straight line parallel to that straight line, the horizontal angles θ 1 and θ 3 of the long axes 2 and 2' of the mandibular condyle are the horizontal angles θ ₁ and θ ₃ It is. The vertical line in the center of the figure is the midline 4 of the horizontal plane. Similarly, in FIG. 2, the intersection angles between the mandibular condyle long axes 2, 2' of the mandible 1 and the reference line 3 are the vertical angles θ ₂ and θ ₄ of the mandibular condyle long axes 2, 2',
The central vertical line is the midline 5 of the vertical plane. In this way, the subject's mandible 1 and the mandibular condyle long axis 2,
2' is the left and right 2, including the shape, even in the same individual.
2′ and therefore the horizontal angle (θ ₁ ≠
θ ₃ ) and the vertical angle is usually (θ ₂ ≠θ ₄ ).

As mentioned above, in order to perform optimal X-ray imaging in response to the different temporomandibular joint morphology for each patient, we recommend that The mandibular bone is photographed in the axial and frontal directions of the head, and this is usually easily done using a well-known general X-ray device and a head fixation device (equipped with ear slots inserted into both external auditory canals). You can take pictures.
For example, from the image shown in Figure 1, the straight line connecting the centers of the ear rods inserted into the external auditory foramina is the reference line 3, and the long axis 2, 2' of the mandibular condyle relative to this line is the reference line 3.
The intersection angles θ ₁ , θ ₃ and the distances L 1 , L ₃ from the midline 4 of the intersections a ₁ , a _{3 ,} that is, the positions can be measured, and the above θ ₁ ,
θ ₃ indicates the eigenvalues of the right and left horizontal declination angles of the X-ray incident angle, and if L ₁ and L ₃ are determined, the X-ray incidence center line is 2,
2' horizontally coincides with the long axis of the mandibular condyle. Next, from the image in Figure 2, θ ₂ , θ ₄ and the intersection b ₂ ,
The positions L ₂ and L ₄ of b ₄ are also determined and become the eigenvalues of the right and left depression angles of the X-ray incident angle, and the X-ray incident center line also coincides with the vertical mandibular condyle long axes 2 and 2'. Instead of using the reference line 3 as the straight line connecting the external auricular foramina as described above, the same results can be obtained by using the midline 4 on the horizontal plane and the median line 5 on the vertical plane and measuring their intersecting angles and points of intersection. can be obtained, and any of them may be used.

Next, an explanation will be given of an embodiment of the present invention. The apparatus of the embodiment is of a type in which, for example, one X-ray source is supported on a swinging rod and is moved inverted from side to side. FIG. 3 is a circuit block diagram using a microcomputer, which is an embodiment of the eigenvalue storage means, the X-ray incident angle setting means, and the X-ray source driving means, which are the essential parts of the present invention. Personal data of various eigenvalues obtained by the above-mentioned preliminary photographing of the subject are stored in the eigenvalue force device 11 of a keyboard with a display, for example.
Input by. For example, each of these data
It is stored at a designated location in the fixed value storage circuit 12 of the IC memory. The above is an embodiment of the eigenvalue storage means, and the CPU 13 is a central processing unit that controls all activities of the microcomputer, and has a built-in clock pulse generator (not shown) and operates in synchronization with the pulses of the clock pulse generator. The interface circuit 14 receives a command from the CPU 13, reads out the unique value data from the storage circuit at an appropriate time, that is, immediately before photographing, and sends it as a signal to each control circuit. For example, when photographing the right temporomandibular joint, if the eigenvalue of the right horizontal declination angle θ ₁ is 18°, the eigenvalue signal input to the horizontal declination control circuit 15 is used as the control signal SC ₁ to move the horizontal declination angle using a pulse motor, for example. It is output to the motor 19. This motor 19 drives the X-ray source to set the horizontal declination angle to the above-mentioned 18°, and the set angle θ ₁ is detected by the horizontal declination angle detector 23 and is used as the control amount signal θ ₁ ' for the above-mentioned control. It is fed back to the circuit 15 and compared with the right horizontal deviation angle eigenvalue signal θ ₁ which is the target value, and the moving motor 19 drives the X-ray source until the deviation becomes zero.
At the same time as the horizontal declination eigenvalue signal θ ₁ , the storage circuit 12
Right median anteroposterior position eigenvalue L ₁ read from
For example, if 13 mm, the control circuit 16 moves the X-ray source focal point
A signal SP ₁ or SP ₃ for controlling the movement in the direction of arrow c or d parallel to is output to the movement motor 20, and the same feedback control as above is performed to move the incident center axis of the X-ray source to the long axis of the mandibular condyle passing through point _a1 . Match 2.
The right depression angle θ ₂ and the right midline vertical position eigenvalue L ₂ are also read out at the same time as above, and assuming that θ ₂ is, for example, 15°, L ₂
is 12 mm, as shown in Fig. ₂ , the X-ray source focal point
By moving in the vertical direction parallel to , that is, in the direction of arrow e or f, the center axis of X-ray incidence becomes completely coincident with the long axis 2 of the mandibular condyle in the vertical direction. The above solid control circuits 15, 16, 17, 18
is an embodiment of the X-ray incident angle setting means of the present invention, and the moving motors 19, 20, 21, and 22 are also embodiments of the X-ray source driving means, and the above operation is for left temporomandibular joint imaging. Once this is completed, the X-ray source supporting rocking rod is reversely moved across the subject's head by a rocking drive source (not shown), stops at a position facing the right temporomandibular joint, and then moves again. The microcomputer shown in FIG. 3 starts operating and takes pictures in the same way as above. FIG. 6 is a flowchart showing the process of operation of the microcomputer. 4 and 5 are schematic diagrams showing the selection of the X-ray incident angle of the X-ray source when photographing the left and right temporomandibular joints of a subject using the apparatus according to the embodiment of the present invention; FIG. 5 is a front view of the human body in the axial direction. The subject's head 31 has ear slots 32 and 33 provided in the device to open and close the left and right external ear holes.
A head rest 34 is supported by the head support 34 and is also movable back and forth on the positioning rod of the device in the front and rear directions.
Through fine adjustment, the eye and ear plane (the plane including the straight line connecting the upper edge of the ear rod and the lowermost point of the lower edge of the orbital mouth) is positioned and stably fixed, for example. On both sides of the head 31, film cassettes are configured to move forward and backward alternately in response to left and right imaging, and to take images with the subject's mouth closed and open, respectively. X-ray tube 37, which is not related and will not be explained in detail
is supported on one end of a swinging rod (not shown) (the four types of moving motors mentioned above are also not shown), and is located on the right side of the subject's head 31, when photographing the left temporomandibular joint 1L. It _is ideal that the incident angle center axis _{Xc of} the X-ray focal point and, as shown in FIG. 5, the central axis of the incident angle of the X-ray focal point
It is also ideal that the angle of X _c is the right depression angle θ ₂ and its intersection b ₂ . The operation of automatically setting the X-ray tube 37 in a position that satisfies the four characteristic values of the horizontal declination angle, the depression angle, its midline longitudinal position, and vertical position is as described above.
7 is inverted to the left side while straddling the subject's head 31. In Figure 4, the X-ray focus
If the angle formed by the central axis of incidence X _c ' of X' with the reference line 3 is the left horizontal deviation angle eigenvalue θ ₃ and the intersection position is a ₃ , it is ideal for imaging the right jaw joint area 1R. As can be seen, by moving the X-ray tube 37 in the direction of the arrow d parallel to the horizontal plane midline 4 from the focal position X ₀ of the simple reversal movement position, the ideal horizontal deviation position can be obtained.
is set to X′. Also, in Figure 5, the X-ray focal point
is flipped to the left and then arrives at the position X _' parallel to the vertical plane midline ₅ in the direction of _the arrow f from the position of The central axis of incidence X _c ' can be obtained. These four eigenvalues of the right temporomandibular joint imaging are performed automatically and instantaneously in the same manner as in the case of the left side.

The above is an embodiment of the present invention, but as mentioned earlier, this invention is applicable not only to a device that inverts and moves one X-ray tube, but also to a device in which X-ray tubes are arranged on the left and right sides. In this case, two sets of each circuit other than the memory circuit shown in FIG. 3 may be provided. Further, the control method of each control circuit shown in FIG. 3 does not necessarily have to be a feedback method. Further, the term "horizontal deviation backward" should be understood to include a range of about 0 to 20 degrees.

Since the present invention is constructed as described above, it solves the drawbacks and problems of the conventional temporomandibular joint imaging device or the device disclosed in the above-mentioned publication, and it can be used for each subject and for the left and right temporomandibular joints of the same patient. X-ray photography can be performed according to the shape of the patient, minimizing overlap with other anatomical shapes, and constantly adjusting the angle of incidence of the X-rays relative to the long axis of the mandibular condyle in relation to the joint cavity and joint space. This makes it possible to significantly improve diagnostic accuracy. Furthermore, by automatically and quickly optimally controlling the X-ray incident angle based on measurement data obtained from preliminary imaging, a convenient device with excellent reproducibility and operability can be provided.

[Brief explanation of the drawing]

Fig. 1 is a plan view illustrating the structure of the mandible in a typical human head, Fig. 2 is a front view of the mandible in Fig. 1, and Fig. 3 is an X-ray temporomandibular joint photograph of an embodiment of the present invention. Block diagram of the X-ray incident angle setting control circuit of the device,
FIG. 4 is a schematic plan view illustrating the operation of the left and right temporomandibular joint imaging of the apparatus according to the embodiment of the present invention, FIG. 5 is a schematic front view of FIG. 4, and FIG. 6 is a schematic diagram of the microcomputer shown in FIG. This is a flowchart showing the process of operation. X...X-ray source focal point, 6 _c , X _c '...X-ray incident center axis,
1... Mandible part, 2,215 mandibular condyle long axis, 3... Reference line connecting both external auditory foramina, θ ₂ , θ ₄ ... Angle of depression, 4... Horizontal plane midline, 5... Vertical plane median line, θ ₁ , θ ₃ ... Horizontal deviation angle (horizontal deviation angle), a ₁ , a ₃ ... Intersection of reference line 3 in the horizontal plane and mandibular condyle long axis 2, 2', L ₁ , L ₃ ... Above intersection
The distance (position) of a ₁ , a ₃ from the horizontal midline 4, b ₂ ,
b ₄ ... Intersection between reference line 3 and mandibular condyle long axis 2, 2' in vertical plane, L ₂ , L ₄ ... Distance (position) of above-mentioned intersection points b ₂ , b ₄ from vertical plane median line 5, 12 ...Eigenvalue storage means,
15, 16, 17, 18...X-ray incident angle setting means,
19, 20, 21, 22...X-ray source driving means.

Claims (1)

[Claims] 1. An X-ray source is supported at the tip of a swinging rod that can be swung at a predetermined angle, and the X-ray source is inverted and moved to a position facing the left and right temporomandibular joints of the subject, or two X-ray sources are moved at a predetermined angle, respectively. X-ray source
The angle of incidence of the line is tilted to a predetermined angle of depression with respect to the reference line connecting both external ear canals of the subject, and the angle of incidence is set so that it is shifted horizontally to the rear by a predetermined horizontal declination angle. In an apparatus configured to continuously photograph the left and right temporomandibular joints, the left and right eigenvalues of the depression angle and horizontal deviation angle and the reference line, which are measured by photographing the subject's mandibular region from the body axis and the front direction, in advance; an eigenvalue storage means for storing left and right eigenvalues of the intersection position of the long axis of the mandibular condyle as personal data;
The
By the line incidence angle setting means and the control signal,
1. An X-ray temporomandibular joint imaging apparatus, comprising: an X-ray source driving means for moving a radiation source.