JP3771341B2 - Dental panoramic tomography system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dental panoramic tomography apparatus.
[0002]
[Prior art]
In a conventionally proposed dental panoramic X-ray apparatus, a CCD sensor, which is an electric sensor having almost the same size as the X-ray irradiation field from the X-ray source, is used for the X-ray sensing part, or the cost is low. A plurality of low-priced small-size CCD sensors are used, and these CCD sensors are controlled at the same timing like a single sensor. This is because the tomography method using an X-ray film is applied even when an electrical sensor is used.
[0003]
That is, in the case of tomography using an X-ray film, the film feed speed is changed to obtain an arbitrary tomographic image. In other words, although the speed of movement in the longitudinal direction of the film is changed, The moving speed in the short direction is not changed. That is, the upper end and the lower end in the short direction of the film are fed at the same speed.
[0004]
As a result, as shown in FIG. 9, the tomographic plane 51 obtained by the tomography method using the X-ray film can be arbitrarily changed. However, the tomographic region 50 has a shape obtained by moving the tomographic plane 51 up and down in parallel. Absent.
[0005]
In the case of a conventional dental panoramic X-ray apparatus using electrical means, the movement corresponding to the film feed movement is faithfully reproduced as the charge feed movement charged to the CCD pixels. The shape is simply a parallel translation of the fault plane.
[0006]
[Problems to be solved by the invention]
For this reason, in a conventional dental panoramic X-ray apparatus, for a subject having a complicated shape such as a tooth row, the tomographic width of the tomographic plane 51 is widened so that the entire tooth row enters the tomographic region as much as possible. There was only. However, in this case, there is a limit in increasing the fault width of the fault plane 51, and as shown in FIG. 10, only the fault width t of about 3 to 6 mm can be obtained particularly in the front tooth portion 60.
[0007]
Therefore, as shown in FIG. 10, the front tooth portion 60 in which the crown portion 62 is inclined forward as compared with the root portion 61 cannot put the entire tooth into the tomographic region.
[0008]
In addition, in the dental panoramic X-ray apparatus using an electrical sensor, as shown in FIG. 11, tomographic areas 50a to 50c obtained by slightly shifting several tomographic planes 51 are obtained, and these are combined and sufficiently obtained. There is an attempt to obtain a large fault area. However, in this case, it takes time to obtain several tomographic areas 50a to 50c, and there is a problem that an electric memory capacity necessary for storing a tomographic image of a large tomographic area becomes large.
[0009]
The present invention has been made in view of the above circumstances, can set a tomographic region suitable for the entire tooth row having a complicated shape, requires a short image formation time, and further requires a required memory capacity. It is an object of the present invention to provide a dental panoramic tomography apparatus which can be reduced.
[0010]
[Means for Solving the Problems]
The invention described in claim 1 includes an X-ray source that irradiates a dentition that is a subject with X-rays, and an X-ray detection unit that includes an irradiation field that detects X-rays transmitted through the dentition that is a subject. A panoramic tomographic apparatus for dental use for obtaining a panoramic tomographic image of a dentition that is the subject, and is arranged corresponding to the irradiation field of the X-ray detection means, and is arranged in a plurality in the longitudinal direction of the irradiation field. It is characterized by comprising a light receiving means having a divided pixel group and a control means for separately controlling the charge transfer rate of the pixel group of the light receiving means.
[0011]
According to a second aspect of the present invention, in the dental panoramic tomography apparatus according to the first aspect, an optical fiber is provided between the X-ray detection means and the light receiving means.
[0012]
According to a third aspect of the present invention, in the dental panoramic tomography apparatus according to the first aspect, an image obtained by a television camera provided on the side of the subject is processed, such as the position of the front tooth portion that is the subject and the inclination of the tooth axis. Thus, the information is used to control the charge transfer rate of each pixel group of the light receiving means.
[0013]
According to a fourth aspect of the present invention, in the dental panoramic tomography apparatus according to the first aspect, there is provided means for irradiating the front tooth portion, which is a subject, with a light beam, and adjusting means for adjusting the direction or shape of the light beam. The position of the front tooth portion, the inclination of the tooth axis, etc. are obtained by a sensor provided in the adjusting means, and the charge transfer speed of each pixel group of the light receiving means is controlled using the information. To do.
[0014]
Hereinafter, the present invention will be described in further detail.
The present invention provides a dental panoramic tomography apparatus for obtaining only a necessary tomographic area from the beginning. That is, a plurality of CCDs or pixel groups arranged in the longitudinal direction of the irradiation field are controlled at different charge transfer rates. Therefore, as shown in FIG. 1, for example, three tomographic planes by three CCDs among a plurality of CCDs or pixel groups are set, and three tomographic regions 1, 2, and 3 based on the tomographic planes by three CCDs are substantially divided. The shape of the tooth 4 can be the same as that of the subject, and the entire tooth 4 can be placed in the tomographic regions 1, 2, and 3. This makes it possible to shorten the required image formation time and further reduce the required memory capacity. Less.
[0015]
In this case, it is possible to use a plurality of CCDs used as the light receiving means, or it is possible to use a CCD having a plurality of pixel groups that can be controlled separately on one silicon substrate. is there.
[0016]
Also, as shown in FIG. 2, one column of pixels of the CCD 10 corresponding to the direction orthogonal to the longitudinal direction of the irradiation field is grouped into a group of pixels 11, 12, and 13, and the charge transfer speed is controlled for each column. Then, as shown in FIG. 3, the tomographic region 15 can be set more finely according to the shape of the tooth 4.
[0017]
Of course, the pixels on the CCD 10 for photographing the lower jaw end and the upper jaw end do not need to be set so finely as a tomographic region, and may be handled as another group of pixels 14 as shown in FIG.
[0018]
As shown in FIG. 4, in the case where independent CCDs 10a and 10b are used as the light receiving means, another CCD 10c may be arranged beside the connecting portion for complementing the insensitive portion 16 between the CCDs 10a and 10b. Good. In FIG. 4, 10a1, 10b1, and 10c1 are effective surfaces of the CCDs 10a, 10b, and 10c.
[0019]
Further, in order not to provide the insensitive portion 16, as shown in FIG. 5, the image signal converted into light by the scintillator 17 as the X-ray detection means is an optical fiber, that is, three taper fibers 18a and 18b. , 18c can be led to each pixel of the two CCDs 10d and 10e.
[0020]
That is, by using the tapered fibers 18a and 18b, the same CCD 10d can be used for a portion that is separated on the irradiation field and that requires the same tomographic plane. At this time, the obtained image is reconstructed on a computer.
[0021]
Further, the position of the front tooth portion that is the subject, the inclination of the tooth axis, and the like are obtained by processing an image obtained by a television camera provided on the side of the subject, and this information is used to determine each pixel group of the light receiving means. The front teeth have means for controlling the transfer rate of electric charges, irradiating the front teeth part as a subject with a light beam, and adjusting means for adjusting the direction or shape of the light beam. It is also possible to obtain the position of the part, the inclination of the tooth axis, etc., and to control the charge transfer rate of each pixel group of the light receiving means using the information. In this way, it is possible to form an image corresponding to the inclination and position of the tooth axis of the front tooth portion.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0023]
6 and 7 illustrate an image construction method in the panoramic tomography apparatus according to the embodiment of the present invention. 6 and 7, an X-ray image of a point on S-A including the point O is formed at a point. This is detected by X-ray film and recorded. At this time, the image formed at point a includes information on all points on the SA from the X-ray source to the X-ray film. S is the position of the X-ray source. In FIG. 6 and FIG. 7, the other point is M, and the rotation center of the arm that supports the X-ray source and the X-ray film is R.
[0024]
Next, when the arm rotates and reaches the position shown in FIG. 7, an X-ray image on S′-A ′ including another point O is generated at point a ′.
[0025]
At this time, if the image on the X-ray film that moves as the arm rotates moves from point a to point a ′, the X-ray image corresponding to point O is recorded at point a ′ on the X-ray film. . On the other hand, an X-ray image of a point on S′-B ′ including M point is generated at point b ′ at the position of the lower arm. Therefore, when the image on the X-ray film is moved from the point a to the point a ′, the X-ray image at the point M is recorded at the point b ′ when the position of the lower arm is reached.
[0026]
If the movement of the X-ray film is repeated while sequentially rotating the arm, the X-ray image at the point O is repeatedly recorded at an arbitrary point a on the X-ray film. On the other hand, the X-ray image of the M point is dispersed and recorded at each point on the X-ray film. For this reason, a sufficient degree of blackening cannot be obtained. In this way, only the X-ray image at the point O is emphasized, and a tomographic image at the point O is obtained.
[0027]
When a CCD having a scintillator layer is used instead of the X-ray film, a charge corresponding to the X-ray image is charged to the pixel at the point a. The CCD sequentially transfers the charges charged in the cells constituting each pixel to the adjacent cells when the information is called, and performs analog / digital conversion at the final end to output as a digital quantity.
[0028]
Here, X-rays are irradiated at the arm position shown in FIG. 7, and an X-ray image of a point on SA is formed on a cell at point a on the CCD, and a charge corresponding to the intensity is charged. The Assuming that the amount of charge is Q1, the amount of charge of Q1 is sequentially transferred to the adjacent cells. However, when the X-ray is irradiated again in the next cycle of the power supply frequency when the arm comes to the position of S, S ′ An X-ray image of the point on -A ′ is formed on the cell of point a ′.
[0029]
At this time, if the charge amount Q1 first stored at the arm position a has moved to the cell at the point a ', the charge of Q2 is charged in addition to the charge of Q1. Q2 is a charge amount corresponding to the transmitted X-ray dose at all points on S′-A ′. At this time, only the X-ray image at the point O is added twice.
[0030]
In this way, by appropriately controlling the charge transfer speed of the CCD pixel, it moves on the CCD cell in the same way as an X-ray image of a certain point is repeatedly formed on the X-ray film. By repeatedly charging the amount of charge according to the X-ray image of the O point, only the X-ray image of the O point is emphasized, and a tomographic image of the O point is obtained. Here, if the charge Q1 at the point a is moved to the point b ′ when the arm is at the position of the lower arm, the charge corresponding to the transmitted X-ray dose at the point on S′-B ′ including the point M is added to Q1. Adapted. As described above, the position of the obtained tomographic image can be changed by changing the speed at which the charged charges are transferred into the cells constituting the pixel.
[0031]
FIG. 8 shows the overall configuration of the dental panoramic tomography apparatus of the present embodiment.
The dental panoramic tomography apparatus shown in FIG. 8 includes a control circuit 21 for controlling the charge transfer speed of a pixel group of three CCDs 31a to 31c described later, an image construction computer 22, an image monitor 24, and not shown. An arm rotation speed control circuit 25, an X-ray head control circuit 26 (not shown), a CPU 27 including a memory, an imaging start switch 28, a scintillator layer 29 for detecting X-rays, and a scintillator layer 29 will be described later. Optical fibers 30a to 30c for guiding light to the CCDs 31a to 31c, and CCDs 31a to 31c each having a plurality of pixel groups are provided.
[0032]
In this dental panoramic tomography apparatus, the crown portion of the anterior tooth, which is the subject of the patient, is positioned so as to be approximately at the position of the optical fiber that sends the image to the CCD 12. Positioning is performed by mechanically moving the height of the chin rest with a dial. At this time, a positioning gauge such as a laser pointer or a light beam can be used.
[0033]
Further, in the detailed photographing mode, manual adjustment is performed so that the light beam follows the inclination of the tooth axis of the front tooth viewed from the side of the subject, and information from a sensor provided in the adjustment mechanism is input to the memory of the CPU 17. The image information of the anterior tooth portion is stored by a TV camera provided separately, or image processing is performed, and the position of the tooth root portion, etc. is automatically estimated from the position of the crown portion of the anterior tooth portion and the inclination of the tooth axis. It is stored in the memory of the CPU 17.
[0034]
Next, when the imaging start switch 28 is pressed, the CPU 27 that has received a signal from the imaging start switch 28 sends a power supply signal to the X-ray head control circuit 26 to drive the X-ray head. Further, the CPU 27 sends a start signal to the arm rotation speed control circuit 25 and sends a transfer speed control signal to the transfer speed control 21 of the CCDs 31a to 31c.
[0035]
The transfer control signals of the CCDs 31a to 31c are controlled in synchronization with the movement of the arm. However, only the start position of the arm is detected by a limit switch or the like. To control the transfer speed of the CCDs 31a to 31c. Of course, the current position of the arm may be detected by a decoder, or the arm position may be detected by the number of pulses to the pulse motor for arm rotation.
[0036]
In the normal photographing mode, the CCDs 31a to 31c are controlled at the same transfer speed in the temporomandibular joint and the molar part, and the transfer speed of the CCD 31b that handles the crown part is more than the CCD 31a and 31c that takes the root part of the canine and anterior teeth. Controlled fast.
[0037]
In the detailed photographing mode, the speed difference ratio is based on information such as the inclination amount of the tooth axis previously stored in the CPU 27. When the inclination of the tooth axis is larger, the transfer speed of the CCD 31b is faster. As a result, the tomographic area moves to the front of the patient's face, that is, to the side farther from the X-ray head than the CCDs 31a and 31c, and the composite of the tomographic areas obtained by the CCDs 31a, 31b, and 31c is the root part. To the crown part.
[0038]
The operation of such a dental panoramic tomography apparatus makes it possible to set a tomographic area suitable for the entire dentition, thereby shortening the required image formation time and further reducing the required memory capacity. You can do it.
[0039]
【The invention's effect】
According to the first aspect of the present invention, it is possible to set a tomographic region suitable for the entire dentition as a subject, thereby shortening the required image forming time and further reducing the required memory capacity. A dental panoramic tomography apparatus can be provided.
[0040]
According to the second aspect of the present invention, since an optical fiber is provided between the X-ray detection unit and the light receiving unit, the degree of freedom of guiding the detection output of the X-ray detection unit to the light receiving unit is increased, and the subject is a subject. It is possible to provide a dental panoramic tomography apparatus capable of forming a finer image of a dentition. .
[0041]
According to the third and fourth aspects of the present invention, a tomographic image of the dentition that is the subject can be obtained more accurately by estimating the position of the tooth root from the position of the crown of the front tooth and the inclination of the tooth axis. It is possible to provide a dental panoramic tomography apparatus capable of
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a relationship between a dentition and a tomographic region in a dental panoramic tomography apparatus according to the present invention.
FIG. 2 is an explanatory diagram of CCD pixel groups in the dental panoramic tomography apparatus of the present invention.
FIG. 3 is a view showing a tomographic region of an anterior tooth portion in the dental panoramic tomography apparatus of the present invention.
FIG. 4 is an explanatory diagram showing the arrangement of three CCDs in the dental panoramic tomography apparatus of the present invention.
FIG. 5 is a perspective view showing the arrangement of a scintillator, three taper fibers, and three CCDs in the dental panoramic tomography apparatus of the present invention.
FIG. 6 is an explanatory diagram showing an image construction method in the dental panoramic tomography apparatus of the present invention.
FIG. 7 is an explanatory diagram showing an image construction method in the dental panoramic tomography apparatus of the present invention.
FIG. 8 is a block diagram showing a dental panoramic tomography apparatus according to an embodiment of the present invention.
FIG. 9 is an explanatory diagram of a tomographic plane and a tomographic region obtained by a conventional tomography method using an X-ray film.
FIG. 10 is an explanatory diagram of a tomographic region of an anterior tooth in a conventional example.
FIG. 11 is a perspective view showing a tomographic area obtained by synthesizing several tomographic planes in a conventional example.
[Explanation of symbols]
1 Fault area 2 Fault area 3 Fault area 4 Teeth row 10 CCD
11 pixel group 12 pixel group 13 pixel group 17 scintillator 18a taper fiber 21 control circuit 22 image construction computer 24 image monitor 25 rotational speed control circuit 26 X-ray head control circuit 27 CPU
28 Shooting start switch 29 Scintillator layer 30a Optical fiber 31a CCD

Claims (4)

An X-ray source for irradiating a dentition as a subject with X-rays; and an X-ray detection means having an irradiation field for detecting an X-ray transmitted through the dentition as a subject. A dental panoramic tomography apparatus for obtaining a panoramic tomographic image,
A light receiving means arranged corresponding to the irradiation field of the X-ray detection means and having a pixel group divided into a plurality in the longitudinal direction of the irradiation field;
Control means for separately controlling the charge transfer rate of the pixel group of the light receiving means;
A dental panoramic tomography apparatus characterized by comprising: The dental panoramic tomography apparatus according to claim 1, wherein an optical fiber is provided between the X-ray detection unit and the light receiving unit. The position of the front tooth portion that is the subject, the inclination of the tooth axis, and the like are obtained by processing an image obtained by a television camera provided on the side of the subject, and this information is used to determine the charge of each pixel group of the light receiving means. The dental panoramic tomography apparatus according to claim 1, wherein the transfer speed is controlled. It has means for irradiating the front tooth part, which is a subject, with a light beam, and adjustment means for adjusting the direction or shape of the light beam, and the position of the front tooth part, the inclination of the tooth axis, etc. by a sensor provided in the adjustment means 2. The dental panoramic tomography apparatus according to claim 1, wherein the information is used to control the charge transfer rate of each pixel group of the light receiving means.

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