JP2008220779A - Dental oct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a dental OCT (optical coherence tomography) measures both of hard tooth and soft periodontal tissues in the narrow and complicated oral cavity, directivities of top/bottom/left/right of tomographic images to be displayed are different according the postures of an operator and a patient and measured sites, the measurement range is narrow, and in some cases, it is often difficult to determine which position in the oral cavity a tomographic image shows. <P>SOLUTION: This dental OCT apparatus processes the tomographic image of a subject acquired by the OCT measured by an optical interference between a signal light reflected at a deep layer position from the surface inside the oral cavity of the subject and a reference light reflected at a path edge of the reference light, displays the respective tissues of the subject with different colors respectively and changes their gradations according to the attenuation of the detection signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an acquired tomographic image of a dental OCT apparatus, and more particularly to a tomographic image display apparatus that displays each tissue of an object to be inspected with different colors and continuous gradation corresponding to attenuation of a detection signal.

  Conventionally, as an optical tomographic image for medical use, for example, an OCT tomographic image in a living body such as an ophthalmologist or a dermatologist is practically used. However, an object to be inspected is a soft tissue, and measurement is performed from a wide open part. Therefore, the shape of the measuring device may be large, and since the measurement is in a certain direction, it is relatively easy to acquire and interpret the tomographic image, and the image may be black and white.

However, in the teeth of the oral examination object in the dental OCT apparatus, the surface is hard tissue enamel, the inner side is hard tissue dentin, and the lower outer side of the dentin is soft tissue gingiva. It is covered with hard and soft tissues.
In addition, the oral cavity is narrow and complicated, and the measurement differs depending on the posture of the operator and patient and the direction of measurement, and the direction of the measurement is narrow. Sometimes it was difficult to interpret.
In particular, the signal obtained from the hard tissue is minimal, and its display means requires a high level of technology, but at the time of diagnosis, the attenuation state of each tissue and its boundary line and the detection signal in the tissue can be seen at a glance by color display. It is desirable that the tomographic image can be discriminated and the directionality can be discriminated.

In view of the above, the present inventors have solved the above problems by the following means as a result of intensive experimental research.
(1) The light from the low-coherence light source is separated into signal light and reference light, which are guided to the signal light path and the reference light path, respectively, and the signal light is on the surface of the intraoral inspected object in the signal light path. Irradiation point scanning means is provided for scanning the irradiation point along the surface of the object to be inspected.
The reference optical path includes an optical element that reflects the reference light at a path end of the reference optical path, and is provided with a reference optical path length scanning unit that scans the optical path length of the reference light, and scans the optical path length of the reference light. Then, based on the optical interference between the signal light reflected at the deep layer position from the surface of the intraoral inspected object corresponding to the optical path length of the reference light and the reference light reflected at the end of the reference light, In a dental OCT device that measures the tomography of the object to be inspected, the tomographic image of the hard tissue or soft tissue of the intraoral inspected object or each tissue of the hard tissue and soft tissue has a different color and attenuates the detection signal. A dental OCT apparatus comprising a display device represented by corresponding continuous gradation.
(2) The dental OCT apparatus according to (1) above, wherein the intraoral subject is a tooth tissue, periodontal tissue, or tooth tissue and periodontal tissue.

According to the present invention,
In a dental OCT apparatus that measures a tomogram of an object to be inspected based on optical interference between signal light reflected at a deep layer position from the surface of an intraoral object to be inspected and reference light reflected at a road edge of the reference light,
Because the tomographic image of the test object is displayed in a continuous tone corresponding to the attenuation of the detection signal, the hard tissue or soft tissue or the hard tissue and soft tissue of the subject are displayed in different colors, respectively.
Conventionally, in a dental OCT apparatus, a tomographic image is obtained by a narrow and complicated operation in the oral cavity, the position and posture of a practitioner and a patient, vertical and horizontal directions that vary depending on the measurement site, and a narrow measurement range. In some cases, it was difficult to interpret the position of
At first glance, hard tissues such as tooth enamel and dentin in the oral cavity and soft tissues such as gingiva are separated by color and displayed in a continuous tone corresponding to the attenuation of the detection signal. It is possible to obtain a tomographic image in which the state of each tissue is known and the direction of the upper, lower, left, and right directions can be determined by color.

The best mode for carrying out the invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating the configuration of a dental OCT apparatus.
In the figure, 1 is a diagnostic probe, 2 is a reference optical path length scanning means, 5 is an optical element, 6 is reference light, 7 is a collimating lens, 8 is a depth direction scan, 9 is a low coherence light source, 10 is an optical fiber, 11 is a detection signal line, 12 is an optical fiber coupler, 13 is a photodetector, 14 is a control signal line, 15 is a signal processing unit, 16 is a computer, 17 is a display unit, 18 is a tomographic image, 19 is horizontal or vertical direction Scanning, 20 is signal light, 21 is a test object, 22 is a tooth, 23 is gingiva, 24 is enamel, 25 is dentin, 26 is pulp, and 27 is alveolar bone.

  The light from the low-coherence light source 9 is split into the signal light 20 to the device under test 21 and the reference light 6 by the optical fiber coupler 12 from the optical fiber 10, and the reference light 6 is optically transmitted by the reference optical path length scanning means 2. The interference light synthesized by the optical fiber coupler 12 is detected by the optical detector 13 together with the signal light 20 which is reflected and returned from the element 5 and returns from the object to be inspected 21, and its output is signal processed from the detection signal line 11. The image is input to the computer 16 via the unit 15, and the tomographic image 18 is displayed by color on the display unit 17. The tomographic image 18 displays a tomographic image composed of tissues of the gingiva 23, enamel 24, dentin 25, dental pulp 26, and alveolar bone 27.

FIG. 2 is a graph of signal intensity at each depth acquired when the teeth of the object to be inspected in FIG. 1 are scanned in the vertical direction and one point at that time is continuously scanned in the depth direction. Strength (dB), the horizontal axis indicates the distance (mm) in the depth direction.
The case is a healthy person's living teeth.
The above graph shows the surface of the enamel 24 where the initial signal intensity is maximum, and the signal intensity gradually attenuates as the distance in the depth direction increases like the enamel attenuation part 24 '. It reaches the surface of the dentin 25 where the next signal intensity suddenly increases.
After the dentin 25, the dentin continues in the depth direction, and the signal intensity gradually attenuates like the dentin attenuation part 25 '.
The original image of the tomogram (FIG. 3) is acquired by continuously scanning one point on the vertical axis in the vertical direction for a predetermined distance.

Figure 3 shows the original image of the tomographic image of the tooth enamel and dentin.
The vertical axis indicates the distance (mm) in the vertical direction, and the horizontal axis indicates the distance (mm) in the depth direction. In the figure, 28 is a space.
The original image is a black and white image. The signal strength with respect to the depth of the surface of the enamel 24, the surface of the dentin 25 and the space 28, and the depths of the enamel attenuation portion 24 ′ and the dentin attenuation portion 25 ′ is shown in continuous tone.
Then, various kinds of image processing are performed on the original image as described below.

FIG. 4 is a correction diagram of light attenuation depending on the distance in the depth direction, and the attenuation is corrected once for easy processing.
In the figure, the distance in the vertical direction (mm), and the horizontal axis indicates the distance in the depth direction (mm).
FIG. 5 is a diagram in which the noise component of FIG. 4 is removed. The noise component is removed by, for example, Fourier transform and Hanning function processing.
The vertical and horizontal axes in the figure are the same as in FIG.

FIG. 6 is a diagram illustrating coloring of enamel and dentin by an arbitrary color scheme and removal of detailed irregularities in a boundary portion by median processing.
This stage is image processing for emphasizing each tissue and its boundary.
Then, the portion of the enamel attenuation portion 24 ′ in FIG. 3 is colored green.
The portion of the dentin attenuation part 25 'is colored in hue blue to clarify the division.
FIG. 7 is an average processing diagram of the boundary of FIG.

FIG. 8 is a composite diagram with the original image. The original image having the continuous tone (FIG. 3) and the boundary averaging process diagram (FIG. 7) are combined, and the enamel 24 and dentin 25 portions are combined. Is displayed in any color that is easy to understand.
In the figure, the hue of the enamel 24 is colored yellow and red, and the hue of the dentin 25 is colored yellow and green.
FIG. 9 is a repeating view of the image composition of FIG. The quality area and continuous tone in the area are more clearly emphasized.

FIG. 10 is a tomographic image diagram of enamel, dentin, and gingiva in another example, and the example is a living tooth of a healthy person. In the figure, the hue of the gingiva 23 and the gingival attenuation part 23 'is red.
Therefore, three types of tissues and continuous gradations are displayed with different hues, the gingiva 23 of the subject 21 being red, the enamel 24 being a mixture of yellow and red, and the dentin 25 being a mixture of yellow and green. Has been.

The block diagram of composition explanation of a dental OCT device. The graph of the signal strength in each depth acquired when the tooth | gear of a to-be-inspected object is scanned to the vertical direction, and one point at that time is continuously scanned to the depth direction. Original image of tomographic images of tooth enamel and dentin. The correction figure of the attenuation of light by the distance of a depth direction. The figure which removed the noise component of FIG. Figure of removal of detailed irregularities at the boundary by coloration of enamel and dentin areas by arbitrary color scheme and median processing. FIG. 7 is an average processing diagram of the boundary of FIG. 6. Composite image with the original image. FIG. 9 is a repetition diagram of the image composition in FIG. 8. A tomographic image of enamel, dentin and gingiva.

Explanation of symbols

1: Diagnostic probe 2: Reference optical path length scanning means 5: Optical element 6: Reference light 7: Collimating lens 8: Depth scanning 9: Low coherence light source 10: Optical fiber 11: Detection signal line 12: Optical fiber coupler 13 : Photo detector 14: Control signal line 15: Signal processing unit 16: Computer 17: Display unit 18: Tomographic image 19: Horizontal or vertical scanning 20: Signal light 21: Inspected object 22: Tooth 23: Gingival 23 ': Gingival decay part 24: Enamel
24 ': Enamel attenuation part 25: Dentin 25': Dentin attenuation part 26: Pulp 27: Alveolar bone 28: Space

Claims (2)

The light from the low-coherence light source is separated into the signal light and the reference light and led to the signal light path and the reference light path, respectively, and the signal light is irradiated onto the surface of the intraoral inspected object in the signal light path. An irradiation point scanning means for scanning the irradiation point along the surface of the object to be inspected,
The reference optical path includes an optical element that reflects the reference light at a path end of the reference optical path, and is provided with a reference optical path length scanning unit that scans the optical path length of the reference light.
Scanning the optical path length of the reference light, the signal light reflected at a deep layer position from the surface of the intraoral subject to be inspected corresponding to the optical path length of the reference light, and the reference light reflected at the end of the reference light In a dental OCT apparatus that measures a tomography of an intraoral inspected object based on optical interference,
Provided with a display device that displays the tomographic images of the hard tissue or soft tissue of the intraoral subject to be examined, or the tomographic images of each tissue of the hard tissue and the soft tissue in different colors and in continuous gradation corresponding to the attenuation of the detection signal. A dental OCT apparatus characterized by   The dental OCT apparatus according to claim 1, wherein the intraoral subject is a tooth tissue, a periodontal tissue, or a tooth tissue and a periodontal tissue.